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1.
  • Appelgren, Daniel, et al. (author)
  • Active NET formation in Libman–Sacks endocarditis without antiphospholipid antibodies : A dramatic onset of systemic lupus erythematosus
  • 2018
  • In: Autoimmunity. - : Informa UK Limited. - 0891-6934 .- 1607-842X. ; 51:6, s. 310-318
  • Journal article (peer-reviewed)abstract
    • Although neutrophil extracellular traps (NETs) have been highlighted in several systemic inflammatory diseases, their clinical correlates and potential pathological role remain obscure. Herein, we describe a dramatic onset of systemic lupus erythematosus (SLE) with clear-cut pathogenic implications for neutrophils and NET formation in a young woman with cardiac (Libman–Sacks endocarditis) and central nervous system (psychosis and seizures) involvement. Despite extensive search, circulating antiphospholipid autoantibodies, a hallmark of Libman–Sacks endocarditis, could not be detected. Instead, we observed active NET formation in the tissue of the mitral valve, as well as in the circulation. Levels of NET remnants were significantly higher in serially obtained sera from the patient compared with sex-matched blood donors (p =.0011), and showed a non-significant but substantial correlation with blood neutrophil counts (r = 0.65, p =.16). The specific neutrophil elastase activity measured in serum seemed to be modulated by the provided immunosuppressive treatment. In addition, we found anti-Ro60/SSA antibodies in the cerebrospinal fluid of the patient but not NET remnants or increased elastase activity. This case illustrates that different disease mechanisms mediated via autoantibodies can occur simultaneously in SLE. NET formation with release of cytotoxic NET remnants is a candidate player in the pathogenesis of this non-canonical form of Libman–Sacks endocarditis occurring in the absence of traditional antiphospholipid autoantibodies. The case description includes longitudinal results with clinical follow-up data and a discussion of the potential roles of NETs in SLE.
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2.
  • Bengtsson, Torbjörn, 1955-, et al. (author)
  • Role of the actin cytoskeleton during respiratory burst in chemoattractant-stimulated neutrophils
  • 2006
  • In: Cell Biology International. - : Wiley. - 1065-6995 .- 1095-8355. ; 30:2, s. 154-163
  • Journal article (peer-reviewed)abstract
    • The aim of this study was to clarify the role of the actin cytoskeleton during chemotactic peptide fMet-Leu-Phe (fMLF)-stimulated respiratory burst in human neutrophil granulocytes. Reactive oxygen species (ROS) was measured as luminol-amplified chemiluminescence (CL) and F-actin content as bodipy phallacidin fluorescence in neutrophils treated with latrunculin B or jasplakinolide, an inhibitor and activator of actin polymerization, respectively. Latrunculin B markedly decreased, whereas jasplakinolide increased, the F-actin content in neutrophils, unstimulated or stimulated with fMLF. Latrunculin B enhanced the fMLF-triggered ROS-production more than tenfold. Jasplakinolide initially inhibited the fMLF-induced CL-response, however, caused a potent second sustained phase (>400% of control). Both actin drugs triggered a substantial CL-response when added 5-25 min after fMLF. This was also valid for chemotactic doses of fMLF, where latrunculin B and jasplakinolide amplified the ROS-production 5-10 times. By using specific signal transduction inhibitors, we found that the NADPH oxidase activation triggered by destabilization of the actin cytoskeleton occurs downstream of phospholipase C and protein kinase C but is mediated by Rho GTPases and tyrosine phosphorylation. In conclusion, rearrangements of the actin cytoskeleton are a prerequisite in connecting ligand/receptor activation, generation of second messengers and assembly of the NADPH oxidase in neutrophil granulocytes. © 2005 International Federation for Cell Biology. Published by Elsevier Ltd. All rights reserved.
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3.
  • Björk, Mathilda, et al. (author)
  • Quality of life and acquired organ damage are intimately related to activity limitations in patients with systemic lupus erythematosus
  • 2015
  • In: BMC Musculoskeletal Disorders. - : BioMed Central / Springer Verlag (Germany). - 1471-2474. ; 16:188
  • Journal article (peer-reviewed)abstract
    • Background: Systemic lupus erythematosus (SLE) is an autoimmune multi-organ disease, characterized by episodes of disease flares and remissions over time, which may restrain affected patients ability to perform daily activities. The purpose of the present study was to characterize variation in activity limitations among well-defined SLE patients, and to describe disease phenotypes, acquired organ damage and their relations to activity limitation and self-reported health, respectively. Methods: The disease phenotypes were organized into 4 different clinical groups and logistic regression analyses were used to identify how an elevated health assessment questionnaire (HAQ) score was related to disease variables such as phenotypes, disease activity and damage accrual. Correlation and multiple linear regression analyses were used to examine the association between each group of variables - background variables, disease variables and self-reported measurements - and the degree of elevated HAQ. Results: We found a higher proportion of activity limitation in patients with skin and joint involvement compared to others. The presence of activity limitation, as detected by the HAQ instrument, was significantly associated with quality of life (EuroQol-5D) and accrual of organ damage using the Systemic Lupus International Collaborative Clinics/ACR damage index. Conclusions: The findings highlight the differing requirements of the multi-professional rehabilitation interventions for the various SLE phenotypes in order to optimize the clinical care of the patients.
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4.
  • Enocsson, Helena, et al. (author)
  • Association of Serum C-Reactive Protein Levels With Lupus Disease Activity in the Absence of Measurable Interferon-α and a C-Reactive Protein Gene Variant
  • 2014
  • In: Arthritis & rheumatology (Hoboken, N.J.). - Hoboken, NJ, United States : John Wiley & Sons. - 2326-5191 .- 2326-5205. ; 66:6, s. 1568-1573
  • Journal article (peer-reviewed)abstract
    • Objectives: The type I interferon (IFN) system is important in the pathogenesis of systemic lupus erythematosus (SLE). We previously demonstrated an inhibitory effect of IFNα on interleukin 6 (IL-6) induced C-reactive protein (CRP) in vitro, hypothetically explaining the poor correlation between disease activity and CRP levels in SLE. Herein we investigated disease activity, IL-6 and CRP in relation to a CRP gene polymorphism and IFN.Methods: Sera from 155 SLE patients and 100 controls were analyzed for CRP. Patients were genotyped for a CRP single nucleotide polymorphism (rs1205) associated with low CRP levels. Serum IFNα and IL-6 was quantified by immunoassays. Clinical disease activity was assessed by SLE disease activity index 2000 (SLEDAI-2K).Results: CRP levels were increased in SLE patients compared to controls, but were not associated with SLEDAI-2K or IL-6 levels. However, exclusion of patients carrying at least one rs1205 minor allele revealed an association between disease activity and CRP levels (p=0.005). We found a strong association between disease activity and CRP levels (p<0.0005) when patients with measurable IFNα as well as the minor allele of rs1205 where excluded from the analysis. Similarly, when patients with raised IFNα and/or the rs1205 polymorphism were excluded, IL-6 associated with CRP levels.Conclusions: The present study demonstrates that serum IFNα as well as CRP genotype affects the CRP response in SLE patients. Lack of correlation between serum levels of CRP and disease activity could therefore be explained by activation of the type I IFN system and polymorphisms in the CRP gene. © 2014 American College of Rheumatology.
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5.
  • Enocsson, Helena, 1982- (author)
  • Biomarkers and mediators in systemic lupus erythematosus : IFNα versus the CRP response, and evaluation of suPAR and anti-dsDNA antibody assays
  • 2014
  • Doctoral thesis (other academic/artistic)abstract
    • Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease which may affect multiple organ systems. Interferon alpha (IFNα) and autoantibodies that form immune complexes with nuclear antigens (ANA) are hallmarks believed to drive the disease into a vicious circle of inflammation, tissue damage, autoantigen exposure and autoantibody production.In SLE, the disease course is characterized by episodes of exacerbations alternating with remissions. In order to best treat the patient it is important to closely monitor symptoms and signs of disease activity. Because of the disease heterogeneity, no single biomarker has yet been found to reflect SLE disease activity in general, although antidouble stranded DNA (anti-dsDNA) antibodies sometimes indicate activity, primarily with renal involvement, and constitutes an item of the SLE disease activity score SLEDAI-2K. However, the method of anti-dsDNA measurement is not standardized and therefore varies between different laboratories. In many other inflammatory conditions, such as rheumatoid arthritis and during bacterial infections, the C-reactive protein (CRP) level is a good indicator of ongoing inflammation, but in SLE and during viral infections, CRP commonly fails to reflect the degree of inflammation. Both viral infections and SLE are characterized by IFNα, and we thus aimed to elucidate whether IFNα can inhibit CRP production. Further, four assays for anti-dsDNA antibody measurements were evaluated with regard to SLE disease specificity and activity, and a new potential biomarker of inflammation, the soluble urokinase plasminogen activator receptor (suPAR), was assessed in relation to disease activity and organ damage.An in vitro inhibitory effect of IFNα on CRP transcription and production was found in hepatocytes, and this was consolidated by in vivo studies of CRP and IFNα in sera from well-characterized SLE patients (KLURING; Kliniskt lupusregister i nordöstra Götaland). Here, CRP and disease activity were associated among patients without IFNα and without a CRP lowering gene variant (SNP rs1205). The poor disease activity compliance of CRP could therefore be explained, at least in part, by polymorphisms in the CRP gene and increased levels of IFNα. Critical differences between the methods measuring anti-dsDNA were found regarding disease specificity and ability to reflect disease activity and the results suggests the Crithidia luciliae immunofluorescence test (CLIFT) for diagnostic purposes and a bead-based multiplex assay (FIDIS) for monitoring of disease activity. Evaluation of suPAR in SLE revealed no association of suPAR with disease activity, but interestingly instead with accumulated organ damage. suPAR could therefore possibly be used to advert patients at high risk of organ damage.A detailed biological and clinical characterization of established and emerging SLE biomarkers is of importance since it may improve the clinical management as well as increase the knowledge about disease mechanisms.
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6.
  • Enocsson, Helena, et al. (author)
  • C-Reactive Protein Levels in Systemic Lupus Erythematosus Are Modulated by the Interferon Gene Signature and CRP Gene Polymorphism rs1205
  • 2021
  • In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
  • Journal article (peer-reviewed)abstract
    • Objectives: Patients with systemic lupus erythematosus (SLE) often display modest elevations of C-reactive protein (CRP) despite raised disease activity and increased interleukin (IL-) 6. We asked to what extent IL-6 levels, the CRP polymorphism rs1205, and the type I interferon (IFN) gene signature affects the basal CRP levels in patients with SLE during a quiescent phase of the disease. Methods: CRP and IL-6 were analyzed in plasma from 57 patients meeting established classification criteria for SLE. The CRP polymorphism rs1205 was assessed and gene expression analyzed including four type I IFN-regulated genes (IGS). Results: CRP was increased in patients with detectable IL-6 levels (p=0.001) and decreased among IGS-positive subjects (p=0.033). A multiple linear regression model revealed IL-6 to have a positive association with CRP levels, whereas both IGS-positivity and CRP genotype (rs1205) AA/GA were negatively associated with CRP-levels. Conclusion: Our data offer an explanation to the modest CRP levels seen in viral infections and IFN-α driven autoimmunity and corroborate prior observations showing an IFN-α dependent downregulation of CRP. The latter observation, together with the fact that the CRP-lowering polymorphism rs1205 is overrepresented in human SLE, could explain low basal CRP and inadequate CRP-responses among patients with active SLE.
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7.
  • Enocsson, Helena, et al. (author)
  • Comparison of Surrogate Markers of the Type I Interferon Response and Their Ability to Mirror Disease Activity in Systemic Lupus Erythematosus
  • 2021
  • In: Frontiers in Immunology. - : Frontiers Media S.A.. - 1664-3224. ; 12
  • Journal article (peer-reviewed)abstract
    • Objectives: Type I interferons (IFNs) are central and reflective of disease activity in systemic lupus erythematosus (SLE). However, IFN-alpha levels are notoriously difficult to measure and the type I IFN gene signature (IGS) is not yet available in clinical routine. This study evaluates galectin-9 and an array of chemokines/cytokines in their potential as surrogate markers of type I IFN and/or SLE disease activity.Methods: Healthy controls and well-characterized Swedish SLE patients from two cross-sectional cohorts (n=181; n=59) were included, and a subgroup (n=21) was longitudinally followed. Chemokine/cytokine responses in immune complex triggered IFN-alpha activity was studied in healthy donor peripheral blood mononuclear cells (PBMC). Levels of chemokines/cytokines and galectin-9 were measured by immunoassays. Gene expression was quantified by qPCR.Results: The IGS was significantly (p<0.01) correlated with galectin-9 (rho=0.54) and CXCL10 (rho=0.37) levels whereas serum IFN-alpha correlated with galectin-9 (rho=0.36), CXCL10 (rho=0.39), CCL19 (rho=0.26) and CCL2 (rho=0.19). The strongest correlation was observed between galectin-9 and TNF (rho=0.56). IFN-alpha and disease activity (SLEDAI-2K) were correlated (rho=0.20) at cross-sectional analysis, but no significant associations were found between SLEDAI-2K and galectin-9 or chemokines. Several inflammatory mediators increased at disease exacerbation although CCL19, CXCL11, CXCL10, IL-10 and IL-1 receptor antagonist were most pronounced. Immune complex-stimulation of PBMC increased the production of CCL2, CXCL8 and TNF.Conclusion: Galectin-9 and CXCL10 were associated with type I IFN in SLE but correlated stronger with TNF. None of the investigated biomarkers showed a convincing association with disease activity, although CXCL10 and CCL19 performed best in this regard.
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8.
  • Enocsson, Helena, et al. (author)
  • Four Anti-dsDNA Antibody Assays in Relation to Systemic Lupus Erythematosus Disease Specificity and Activity
  • 2015
  • In: Journal of Rheumatology. - : The Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 42:5, s. 817-825
  • Journal article (peer-reviewed)abstract
    • Objective. Analysis of antibodies against dsDNA is an important diagnostic tool for systemic lupus erythematosus (SLE), and changes in anti-dsDNA antibody levels are also used to assess disease activity. Herein, 4 assays were compared with regard to SLE specificity, sensitivity, and association with disease activity variables. Methods. Cross-sectional sera from 178 patients with SLE, of which 11 were followed consecutively, from a regional Swedish SLE register were analyzed for immunoglobulin G (IgG) anti-dsDNA by bead-based multiplex assay (FIDIS; Theradig), fluoroenzyme-immunoassay (EliA; Phadia/Thermo Fisher Scientific), Crithidia luciliae immunofluorescence test (CLIFT; ImmunoConcepts), and line blot (EUROLINE; Euroimmun). All patients with SLE fulfilled the 1982 American College of Rheumatology and/or the 2012 Systemic Lupus International Collaborating Clinics (SLICC-12) classification criteria. Healthy individuals (n = 100), patients with rheumatoid arthritis (n = 95), and patients with primary Sjogren syndrome (n = 54) served as controls. Results. CLIFT had the highest SLE specificity (98%) whereas EliA had the highest sensitivity (35%). When cutoff levels for FIDIS, EliA, and EUROLINE were adjusted according to SLICC-12 (i.e., double the reference limit when using ELISA), the specificity and sensitivity of FIDIS was comparable to CLIFT. FIDIS and CLIFT also showed the highest concordance (84%). FIDIS performed best regarding association with disease activity in cross-sectional and consecutive samples. Fisher's exact test revealed striking differences between methods regarding associations with certain disease phenotypes. Conclusion. CLIFT remains a good choice for diagnostic purposes, but FIDIS performs equally well when the cutoff is adjusted according to SLICC-12. Based on results from cross-sectional and consecutive analyses, FIDIS can also be recommended to monitor disease activity.
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9.
  • Enocsson, Helena, et al. (author)
  • Interferon-alpha Mediates Suppression of C-Reactive Protein Explanation for Muted C-Reactive Protein Response in Lupus Flares?
  • 2009
  • In: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 60:12, s. 3755-3760
  • Journal article (peer-reviewed)abstract
    • Objective. C-reactive protein (CRP) is synthesized by hepatocytes in response to interleukin-6 (IL-6) during inflammation. Despite raised IL-6 levels and extensive systemic inflammation, serum CRP levels remain low during most viral infections and disease flares of systemic lupus erythematosus (SLE). Because both viral infections and SLE are characterized by high levels of interferon-alpha (IFN alpha), the aim of this study was to determine whether this cytokine can inhibit the induction of CRP. Methods. The interference of all 12 IFN alpha subtypes with CRP promoter activity induced by IL-6 and IL-1 beta was studied in a CRP promoter- and luciferase reporter-transfected human hepatoma cell line, Hep-G2. CRIP secretion by primary human hepatocytes was analyzed by enzyme-linked immunosorbent assay. Results. CRP promoter activity was inhibited by all single IFN alpha subtypes, as well as by 2 different mixtures of biologically relevant IFN alpha subtypes. The most prominent effect was seen using a leukocyte-produced mixture of IFN alpha (56% inhibition at 1,000 IU/ml). The inhibitory effect of IFN alpha was confirmed in primary human hepatocytes. CRP promoter inhibition was dose dependent and mediated via the type I IFN receptor. Transferrin production and Hep-G2 proliferation/viability were not affected by IFN alpha. Conclusion. The current study demonstrates that IFN alpha is an inhibitor of CRP promoter activity and CRP secretion. This finding concords with previous observations of up-regulated IFN alpha and a muted CRP response during SLE disease flares. Given the fundamental role of both IFN alpha and CRP in the immune response, our results are of importance for understanding the pathogenesis of SLE and may also contribute to understanding the differences in the CRP response between viral and bacterial infections.
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10.
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11.
  • Enocsson, Helena, et al. (author)
  • Serum C-reactive protein (CRP) associates with lupus disease activity in the absence of measurable interferon alpha and a CRP gene variant
  • 2014
  • In: Arthritis & rheumatology. - : Wiley. - 2326-5205 .- 2326-5191. ; 66:6, s. 1568-1573
  • Journal article (peer-reviewed)abstract
    • Objectives: The type I interferon (IFN) system is important in the pathogenesis of systemic lupus erythematosus (SLE). We previously demonstrated an inhibitory effect of IFNα on interleukin 6 (IL-6) induced C-reactive protein (CRP) in vitro, hypothetically explaining the poor correlation between disease activity and CRP levels in SLE. Herein we investigated disease activity, IL-6 and CRP in relation to a CRP gene polymorphism and IFNαMethods: Sera from 155 SLE patients and 100 controls were analyzed for CRP. Patients were genotyped for a CRP single nucleotide polymorphism (rs1205) associated with low CRP levels. Serum IFNα and IL-6 was quantified by immunoassays. Clinical disease activity was assessed by SLE disease activity index 2000 (SLEDAI-2K).Results: CRP levels were increased in SLE patients compared to controls, but were not associated with SLEDAI-2K or IL-6 levels. However, exclusion of patients carrying at least one rs1205 minor allele revealed an association between disease activity and CRP levels (p=0.005). We found a strong association between disease activity and CRP levels (p<0.0005) when patients with measurable IFNα as well as the minor allele of rs1205 where excluded from the analysis. Similarly, when patients with raised IFNα and/or the rs1205 polymorphism were excluded, IL-6 associated with CRP levels.Conclusions: The present study demonstrates that serum IFNα as well as CRP genotype affects the CRP response in SLE patients. Lack of correlation between serum levels of CRP and disease activity could therefore be explained by activation of the type I IFN system and polymorphisms in the CRP gene.
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12.
  • Enocsson, Helena, et al. (author)
  • Soluble urokinase plasminogen activator receptor : A valuable biomarker in systemic lupus erythematosus?
  • 2015
  • In: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 444, s. 234-241
  • Research review (peer-reviewed)abstract
    • Systemic lupus erythematosus (SLE) is a potentially severe autoimmune condition with an unpredictable disease course, often with fluctuations in disease activity over time. Long term inflammation and drug-related side-effects may subsequently lead to permanent organ damage, a consequence which is intimately connected to decreased quality of life and mortality. New lupus biomarkers that convey information regarding inflammation and/or organ damage are thus warranted. Today, there is no clinical biomarker that indicates the risk of damage accrual. Herein we highlight the urokinase plasminogen activator receptor (uPAR) and especially its soluble form (suPAR) that besides having biological functions in e.g. proteolysis, cell migration and tissue homeostasis, recently has emerged as a promising biomarker of inflammation and prognosis of several disorders. A strong association between suPAR and organ damage in SLE was recently demonstrated, and preliminary data (presented in this review) suggests the possibility of a predictive value of suPAR blood levels. The involvement of suPAR in the pathogenesis of SLE remains obscure, but its effects in leukocyte recruitment, phagocytic uptake of dying cells (efferocytosis) and complement regulation suggests that the central parts of the SLE pathogenesis could be regulated by suPAR, and vice versa.
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13.
  • Enocsson, Helena, et al. (author)
  • Soluble urokinase plasminogen activator receptor levels reflect organ damage in systemic lupus erythematosus
  • 2013
  • In: Translational Research. - : Elsevier. - 1931-5244 .- 1878-1810. ; 162:5, s. 287-296
  • Journal article (peer-reviewed)abstract
    • Assessments of disease activity and organ damage in systemic lupus erythematosus (SLE) remain challenging because of the lack of reliable biomarkers and disease heterogeneity. Ongoing inflammation can be difficult to distinguish from permanent organ damage caused by previous flare-ups or medication side effects. Circulating soluble urokinase plasminogen activator receptor (suPAR) has emerged as a potential marker of inflammation and disease severity, and an outcome predictor in several disparate conditions. This study was done to evaluate suPAR as a marker of disease activity and organ damage in SLE. Sera from 100 healthy donors- and 198 patients with SLE fulfilling the 1982 American College of Rheumatology classification criteria and/or the Fries criteria were analyzed for suPAR by enzyme immunoassay. Eighteen patients with varying degree of disease activity were monitored longitudinally. Disease activity was assessed by the SLE disease activity index 2000 and the physicians global assessment. Organ damage was evaluated by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology damage index (SDI). Compared with healthy control subjects, serum suPAR levels were elevated significantly in patients with SLE. No association was recorded regarding suPAR levels and SLE disease activity in cross-sectional or consecutive samples. However, a strong association was observed between suPAR and SDI (P andlt; 0.0005). Considering distinct SDI domains, renal, neuropsychiatric, ocular, skin, and peripheral vascular damage had.a significant effect on suPAR levels. This study is the first to demonstrate an association between serum suPAR and irreversible organ damage in SLE. Further studies are warranted to evaluate suPAR and other biomarkers as predictors of evolving organ damage.
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14.
  • Enocsson, Helena, et al. (author)
  • Soluble urokinase plasminogen activator receptor (suPAR) levels predict damage accrual in patients with recent-onset systemic lupus erythematosus
  • 2020
  • In: Journal of Autoimmunity. - : Elsevier BV. - 0896-8411 .- 1095-9157. ; 106
  • Journal article (peer-reviewed)abstract
    • Objective: The soluble urokinase plasminogen activator receptor (suPAR) has potential as a prognosis and severity biomarker in several inflammatory and infectious diseases. In a previous cross-sectional study, suPAR levels were shown to reflect damage accrual in cases of systemic lupus erythematosus (SLE). Herein, we evaluated suPAR as a predictor of future organ damage in recent-onset SLE. Methods: Included were 344 patients from the Systemic Lupus International Collaborating Clinics (SLICC) Inception Cohort who met the 1997 American College of Rheumatology classification criteria with 5-years of follow-up data available. Baseline sera from patients and age- and sex-matched controls were assayed for suPAR. Organ damage was assessed annually using the SLICC/ACR damage index (SDI). Results: The levels of suPAR were higher in patients who accrued damage, particularly those with SDI≥2 at 5 years (N = 32, 46.8% increase, p = 0.004), as compared to patients without damage. Logistic regression analysis revealed a significant impact of suPAR on SDI outcome (SDI≥2; OR = 1.14; 95% CI 1.03–1.26), also after adjustment for confounding factors. In an optimized logistic regression to predict damage, suPAR persisted as a predictor, together with baseline disease activity (SLEDAI-2K), age, and non-Caucasian ethnicity (model AUC = 0.77). Dissecting SDI into organ systems revealed higher suPAR levels in patients who developed musculoskeletal damage (SDI≥1; p = 0.007). Conclusion: Prognostic biomarkers identify patients who are at risk of acquiring early damage and therefore need careful observation and targeted treatment strategies. Overall, suPAR constitutes an interesting biomarker for patient stratification and for identifying SLE patients who are at risk of acquiring organ damage during the first 5 years of disease.
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15.
  • Enocsson, Helena, et al. (author)
  • The Complex Role of C-Reactive Protein in Systemic Lupus Erythematosus
  • 2021
  • In: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 10:24
  • Research review (peer-reviewed)abstract
    • C-reactive protein (CRP) is well-known as a sensitive albeit unspecific biomarker of inflammation. In most rheumatic conditions, the level of this evolutionarily highly conserved pattern recognition molecule conveys reliable information regarding the degree of ongoing inflammation, driven mainly by interleukin-6. However, the underlying causes of increased CRP levels are numerous, including both infections and malignancies. In addition, low to moderate increases in CRP predict subsequent cardiovascular events, often occurring years later, in patients with angina and in healthy individuals. However, autoimmune diseases characterized by the Type I interferon gene signature (e.g., systemic lupus erythematosus, primary Sjogrens syndrome and inflammatory myopathies) represent exceptions to the general rule that the concentrations of CRP correlate with the extent and severity of inflammation. In fact, adequate levels of CRP can be beneficial in autoimmune conditions, in that they contribute to efficient clearance of cell remnants and immune complexes through complement activation/modulation, opsonization and phagocytosis. Furthermore, emerging data indicate that CRP constitutes an autoantigen in systemic lupus erythematosus. At the same time, the increased risks of cardiovascular and cerebrovascular diseases in patients diagnosed with systemic lupus erythematosus and rheumatoid arthritis are well-established, with significant impacts on quality of life, accrual of organ damage, and premature mortality. This review describes CRP-mediated biological effects and the regulation of CRP release in relation to aspects of cardiovascular disease and mechanisms of autoimmunity, with particular focus on systemic lupus erythematosus.
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16.
  • Frodlund, Martina, 1978- (author)
  • Antinuclear and antiphospholipid antibodies versus disease manifestations and clinical outcomes in systemic lupus erythematosus
  • 2020
  • Doctoral thesis (other academic/artistic)abstract
    • Systemic lupus erythematosus (SLE) has an exceptionally heterogeneous clinical spectrum, ranging from mild disease limited to skin and joints to severe manifestations with renal disorder, central nervous system disease, severe cytopenias and thromboembolic events. Important clinical challenges include the prediction of disease flares and the identification of individuals that are likely to evolve severe disease with accrual of organ damage and worse prognosis. Autoantibodies, i.e. antinuclear antibodies (ANA) and antiphospholipid antibodies (aPL), and interferon alpha (IFN-α) that contribute to formation of immune complexes with nuclear antigens, are hallmarks considered to drive the disease in a vicious circle of antigen exposure, autoantibody production, inflammation and organ damage. There are few good biomarkers to predict severe SLE and organ damage. The aim of this PhD project was thus to increase the knowledge regarding ANA as well as aPL, and other potential biomarkers in relation to clinical features and disease outcomes in SLE.As expected, we found that the homogeneous ANA staining pattern was most common, and that it was associated with the occurrence of the ‘immunological disorder’ criterion. Speckled ANA was the second most common staining pattern, and it was inversely associated with arthritis, the ‘immunological disorder’ criterion and organ damage (Paper I). We also demonstrated that a considerable proportion of the patients lost ANA-positivity over time, whereas consistent staining patterns were most frequent (Paper V).Survival of patients with SLE has improved. Yet, in comparison to the general population, irreversible organ damage and increased mortality remains a critical concern. In Paper II, our cross-sectional analysis showed that more than a quarter of the patients had any aPL isotype (IgG, IgM or IgA class), and 14% were classified with antiphospholipid antibody syndrome (APS). A positive lupus anticoagulant (LA) test and/or IgG aPL tests were associated with most APS-related events and organ damage. Lupus nephritis, tobacco smoking, LA-positivity and the use of statins and/or corticosteroids were strongly associated with damage accrual, while hydroxychloroquine seemed to be protective. IgA aPL was not uncommon (16%) in Swedish cases of SLE, and analysis of IgA aPL may add information among clinically suspected APS-patients testing negative for LA and other aPL isotypes.Despite modern management and tax-funded health care with universal access, almost two thirds of the patients accrued organ damage over time, and the main causes of death were identified as malignancy, infection, and cardiovascular disease. We could confirm well established risk factors for organ damage such as APS, hypertension, and/or the use of corticosteroids, but we also observed that other factors such as pericarditis, haemolytic anaemia, lymphopenia and myositis seems to be of importance in this view (Paper IV).We also demonstrated that levels of the extracellular matrix protein osteopontin (OPN) was correlated with disease activity in patients with recent-onset SLE. In addition, OPN levels reflected global organ damage and were associated with APS and could have potential as a valuable biomarker in SLE (Paper III).Additional studies are warranted to further establish the clinical and mechanistic relevance of ANA seroconversion, OPN, as well as the importance of IgA aPL. Vigilance for malignancies, a restricted use of corticosteroids and prevention of cardiovascular disease and APS events are among modifiable factors to prevent organ damage and premature mortality.This thesis emphasizes the importance of autoantibodies in the pathogenesis, and diagnosis, of SLE. The autoantibody profile can be of great importance for tailored therapy in order to minimize the risk of organ damage accrual, morbidity as well as mortality.
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17.
  • Frodlund, Martina, et al. (author)
  • Immunoglobulin A anti-phospholipid antibodies in Swedish cases of systemic lupus erythematosus : associations with disease phenotypes, vascular events and damage accrual
  • 2018
  • In: Clinical and Experimental Immunology. - : WILEY. - 0009-9104 .- 1365-2249. ; 194:1, s. 27-38
  • Journal article (peer-reviewed)abstract
    • Immunoglobulin (Ig) G- and IgM-class anti-cardiolipin antibodies (aCL) and lupus anti-coagulant (LA) are included in the 1997 update of the American College of Rheumatology (ACR-97) systemic lupus erythematosus (SLE) criteria. Despite limited evidence, IgA-aCL and IgA anti-(2)-glycoprotein-I (anti-(2)GPI) were included in the 2012 Systemic Lupus International Collaborating Clinics criteria. The present study aimed to evaluate IgG-/IgA-/IgM-aCL and anti-(2)GPI occurrence in relation to disease phenotype, smoking habits, pharmacotherapy, anti-phospholipid syndrome (APS) and organ damage among 526 Swedish SLE patients meeting ACR-97. Patients with rheumatoid arthritis (n=100), primary Sjogren's syndrome (n=50) and blood donors (n=507) served as controls. Anti-phospholipid antibodies (aPL) were analysed by fluoroenzyme-immunoassays detecting aCL/anti-(2)GPI. Seventy-six (14%) SLE cases fulfilled the Sydney APS-criteria, and 1 aCL/anti-(2)GPI isotype (IgG/IgA/IgM) occurred in 138 SLE patients (26%). Forty-five (9%) of the SLE cases had IgA-aCL, 20 of whom (4%) lacked IgG-/IgM-aCL. Seventy-four (14%) tested positive for IgA anti-(2)GPI, 34 (6%) being seronegative regarding IgG/IgM anti-(2)GPI. Six (1%) had APS manifestations but were seropositive regarding IgA-aCL and/or IgA anti-(2)GPI in the absence of IgG/IgM-aPL and LA. Positive LA and IgG-aPL tests were associated with most APS-related events and organ damage. Exclusive IgA anti-(2)GPI occurrence associated inversely with Caucasian ethnicity [odds ratio (OR)=021, 95% confidence interval (CI)=006-072) and photosensitivity (OR=019, 95% CI=005-072). Nephritis, smoking, LA-positivity and statin/corticosteroid-medication associated strongly with organ damage, whereas hydroxychloroquine-medication was protective. In conclusion, IgA-aPL is not rare in SLE (16%) and IgA-aPL analysis may have additional value among SLE cases with suspected APS testing negative for other isotypes of aPL and LA.
  •  
18.
  • Frodlund, Martina, 1978-, et al. (author)
  • Longitudinal anti-nuclear antibody (ANA) seroconversion in systemic lupus erythematosus : a prospective study of Swedish cases with recent-onset disease
  • 2020
  • In: Clinical and Experimental Immunology. - : WILEY. - 0009-9104 .- 1365-2249. ; 199:3, s. 245-254
  • Journal article (peer-reviewed)abstract
    • Serum immunoglobulin (Ig)G anti-nuclear antibodies (ANA) detected by indirect immunofluorescence (IF) microscopy remains a hallmark of systemic lupus erythematosus (SLE). Whether or not IF-ANA status varies over time is controversial. We therefore designed a prospective study with longitudinal follow-up of patients with recent-onset SLE. The study population consisted of 54 recently diagnosed SLE cases, all meeting the 1982 American College of Rheumatology (ACR) and/or the 2012 Systemic Lupus International Collaborating Clinics (SLICC) criteria. Clinical follow-up data, including disease activity, organ damage and sera, were collected from clinical onset of SLE and onwards, in most cases yearly (0-96 months). IF-ANA was analysed on human epithelial cells-2 (HEp-2) cells and categorized regarding staining patterns. Using an addressable laser bead assay (FIDIS (TM) Connective profile), we measured IgG-ANA fine specificities against Ro52/SSA, Ro60/SSA, Sjogren's syndrome type B antigen (La/SSB), Smith antigen (Sm), Smith antigen/ribonucleoprotein (Sm/RNP), U1 RNP (U1RNP), dsDNA, ribosomal-P protein and histone. At baseline, all patients were judged ANA-positive at an abnormal titre corresponding to the 95th percentile of healthy blood donors, but seven of 54 patients (13%) lost ANA-positivity over time. Homogeneous (AC-1; 46%) and speckled (AC-4 or 5; 31%) were the most frequently observed patterns at inclusion, whereas 7% switched pattern at least once during follow-up. Established associations between ANA fine specificities and clinical data were confirmed. Levels of anti-Sm/RNP, but not of anti-dsDNA, correlated with clinical disease activity [modified SLE disease activity 2000 (mSLEDAI-2K)]. Our data indicate that a considerable proportion of Swedish patients with SLE lose ANA-positivity over time, whereas consistent staining patterns were frequent. The clinical and mechanistic relevance of ANA seroconversion remains uncertain. Further prospective evaluations in larger SLE populations with more diverse ethnicities are warranted.
  •  
19.
  • Frodlund, Martina, et al. (author)
  • The majority of Swedish systemic lupus erythematosus patients are still affected by irreversible organ impairment : factors related to damage accrual in two regional cohorts
  • 2019
  • In: Lupus. - : SAGE PUBLICATIONS LTD. - 0961-2033 .- 1477-0962. ; 28:10, s. 1261-1272
  • Journal article (peer-reviewed)abstract
    • Background Although the survival of patients with systemic lupus erythematosus (SLE) has improved, irreversible organ damage remains a critical concern. We aimed to characterize damage accrual and its clinical associations and causes of death in Swedish patients. Methods Accumulation of damage was evaluated in 543 consecutively recruited and well-characterized cases during 1998-2017. The Systemic Lupus International Collaborating Clinics (SLICC)/American College of Rheumatology damage index (SDI) was used to estimate damage. Results Organ damage (SDI >= 1) was observed in 59%, and extensive damage (SDI >= 3) in 25% of cases. SDI >= 1 was significantly associated with higher age at onset, SLE duration, the number of fulfilled SLICC criteria, neurologic disorder, antiphospholipid antibody syndrome (APS), hypertension, hyperlipidemia, depression and secondary Sjogren's syndrome (SS). In addition, SDI >= 3 was associated with serositis, renal and haematological disorders and interstitial lung disease. A multiple regression model identified not only well-known risk factors like APS, antihypertensives and corticosteroids, but pericarditis, haemolytic anaemia, lymphopenia and myositis as being linked to SDI. Malignancy, infection and cardiovascular disease were the leading causes of death. Conclusions After a mean SLE duration of 17 years, the majority of today's Swedish SLE patients have accrued damage. We confirm previous observations and report some novel findings regarding disease phenotypes and damage accrual.
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20.
  • Hansson, Kenny, 1972-, et al. (author)
  • Surface plasmon resonance detection of blood coagulation and platelet adhesion under venous and arterial shear conditions.
  • 2007
  • In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 23:2, s. 261-8
  • Journal article (peer-reviewed)abstract
    • A surface plasmon resonance (SPR) based flow chamber device was designed for real time detection of blood coagulation and platelet adhesion in platelet rich plasma (PRP) and whole blood. The system allowed the detection of surface interactions throughout the 6mm length of the flow chamber. After deposition of thromboplastin onto a section of the sensor surface near the inlet of the flow chamber, coagulation was detected downstream of this position corresponding to a SPR signal of 7 to 8 mRIU (7 to 8 ng/mm2). A nonmodified control surface induced coagulation 3.5 times slower. Platelet adhesion to gold and fibrinogen coated surfaces in the magnitude of 1.25 and 1.66 mRIU was also shown with platelets in buffer, respectively. SPR responses obtained with PRP and whole blood on surfaces that were methylated or coated with von Willebrand factor (vWF), fibrinogen, or collagen, coincided well with platelet adhesion as observed with fluorescence microscopy in parallel experiments. The present SPR detection equipped flow chamber system is a promising tool for studies on coagulation events and blood cell adhesion under physiological flow conditions, and allows monitoring of short-range surface processes in whole blood.
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21.
  • Hansson, Kenny, 1972-, et al. (author)
  • Whole blood coagulation on protein adsorption-resistant PEG and peptide functionalised PEG-coated titanium surfaces.
  • 2005
  • In: Biomaterials. - : Elsevier BV. - 0142-9612 .- 1878-5905. ; 26:8, s. 861-72
  • Journal article (peer-reviewed)abstract
    • The aim of this study was to investigate whole blood coagulation on low blood plasma protein adsorbing surfaces. For this purpose, the polycationic graft copolymer poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), PLL-g-PEG grafted with a cell adhesive peptide containing the amino acid sequence -Arg-Gly-Asp- (RGD), and PLL-g-PEG with a control peptide -Arg-Asp-Gly- (RDG) were adsorbed onto titanium (oxide), forming stable monomolecular adlayers through electrostatic attraction. Free oscillation rheometry and complementary techniques were used to measure the coagulation time (CT) and other interactions of the surfaces with native whole blood, recalcified platelet-rich plasma (PRP), and recalcified citrated platelet-free plasma (PFP). The results show that the uncoated titanium surfaces (reference) activated platelets and quickly triggered the coagulation cascade via the intrinsic pathway, whereas the PLL-g-PEG surfaces displayed a prolonged CT, approximately 2-3 times longer compared to uncoated titanium. We hypothesise that blood coagulates outside the vascular system independent of low protein adsorption to or activation by surfaces, due to the absence of an active down-regulation of procoagulative processes by the vascular endothelium.
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22.
  • Hemgren, Cecilia, et al. (author)
  • Elevated Serum Levels of Zonulin Family Peptides in Anticitrullinated Protein Antibody-Positive At-Risk Individuals Without Arthritis
  • 2024
  • In: Journal of Rheumatology. - : J RHEUMATOL PUBL CO. - 0315-162X .- 1499-2752. ; 51:2, s. 134-138
  • Journal article (peer-reviewed)abstract
    • Objective. Recent advances imply that early events triggering rheumatoid arthritis (RA) occur at mucosal surfaces. We aimed to evaluate whether intestinal permeability is altered in patients at increased risk of RA, and/or predicts the development of clinical arthritis, by measuring serum zonulin family peptides (ZFP) levels, which are shown to reflect intestinal barrier integrity. Methods. Two independent prospective observational cohorts were studied, including subjects with musculoskeletal symptoms and anticitrullinated protein antibodies (ACPA), but without clinical arthritis at baseline. In Sweden, 82 such at-risk patients were compared to 100 age-matched healthy blood donors. In the UK, 307 at-risk patients were compared to 100 ACPA-negative symptomatic controls. ZFP was measured in baseline sera by enzyme-linked immunoassays. Results. In the Swedish at-risk cohort, ZFP levels were significantly increased in patients compared to controls (mean 41.4 vs 33.6 ng/mL, P < 0.001) and Cox regression analysis showed prognostic value of ZFP for arthritis development (hazard ratio [HZ] 1.04 per ng/mL ZFP increase, 95% CI 1.01-1.07, P = 0.02). Elevated ZFP levels among ACPA-positive at-risk patients compared to symptomatic ACPA-negative controls were confirmed in the UK at-risk cohort (mean 69.7 vs 36.0 ng/ml, P < 0.001), but baseline ZFP were not associated with arthritis development (HR 1.00 per ng/mL ZFP increase, 95% CI 1.00-1.01, P = 0.30). Conclusion. Serum ZFP levels are elevated in ACPA-positive at-risk patients when compared to both healthy blood donors and symptomatic ACPA-negative controls. Thus, gut barrier function may be of importance in RA-associated autoimmunity. A possible prognostic value of serum ZFP merits further investigation, preferably in larger prospective cohorts.
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23.
  • Holm, Angelika (author)
  • Aquaporins in Infection and Inflammation
  • 2016
  • Doctoral thesis (other academic/artistic)abstract
    • The ability of eukaryotic cells to change their shape and to migrate directionally is highly dependent on active volume regulation in cells building up tissues as well as in individual cells. Transmembrane fluxes of water via specialized water channels, called aquaporins (AQPs), facilitate the changes of volume and shape, which additionally require a complex interplay between the plasma membrane and the cytoskeleton. AQPs have been shown to be involved in the development of inflammatory processes and diseases. The aims of the studies underlying this thesis were to further elucidate the expression and function of AQPs in both bacterial and viral infections as well as in the inflammatory disease, microscopic colitis. For this, molecular techniques qPCR, immunoblotting and live, holographic, confocal and super-resolution imaging were used.When cells of the innate immune system encounter pathogens they need to respond and prepare for migration and phagocytosis and do so through volume regulatory processes. The Gramnegative bacterium Pseudomonas aeruginosa utilizes a small molecule-based communication system, called quorum sensing (QS) to control the production of its virulence factors and biofilms. We found that P. aeruginosa with a complete QS system elicits a stronger phagocytic response in human blood-derived macrophages compared to its lasI-/rhlI- mutant lacking the production of the QS molecules N-butyryl-L-homoserine lactone (C4-HSL) and N-3-oxododecanoyl-L-homoserine lactone (3O-C12-HSL). Infection with P. aeruginosa further increases the expression of AQP9 and induces re-localisation of AQP9 to the front and trailing ends of macrophages. Moreover, the 3O-C12-HSL alone elevates the expression of AQP9, redistribute the water channel to the front and rear ends and increases the cell area and volume of macrophages. Both infection with the wild type P. aeruginosa and the treatment with 3OC12-HSL change the nano-structural architecture of the AQP9 distribution in macrophages.Viruses use the intracellular machinery of the invaded cells to produce and assemble new viral bodies. Intracellular AQPs are localised in a membranes of cellular organelles to regulate their function and morphology. C3H10T1/2 fibroblasts transiently expressing green fluorescent protein (GFP)-AQP6 show a reduced expression of AQP6 after Hazara virus infection and an increased cell area. Overexpressing AQP6 in C3H10T1/2 cells reduces the infectivity of Hazara virus indicating that AQP6 expression has a protective role in virus infections.Ion and water channels in the epithelial cell lining tightly regulate the water homeostasis. In microscopic colitis (MC), patients suffer from severe watery diarrhoeas. For the first time, we have shown that the expression of AQP1, 8 and 11 and the sodium/hydrogen exchanger NHE1 are reduced in colonic biopsies from MC patients compared to healthy control individuals. Following treatment with the glucocorticoid budesonide the patients experienced a rapid recovery and we observed a restored or increased expression of the AQPs and NHE1 during treatment, suggesting a role for AQPs in the diarrhoeal mechanisms in MC.Taken together, this thesis provides new evidence on the importance of water homeostasis regulation through AQPs during infections and inflammation and opens up a door for further investigations of roles for AQPs in inflammatory processes.
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24.
  • Kanmert, Daniel, et al. (author)
  • Designed Surface with Tunable IgG Density as an in Vitro Model for Immune Complex Mediated Stimulation of Leukocytes
  • 2010
  • In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 26:5, s. 3493-3497
  • Journal article (peer-reviewed)abstract
    • We present the design of an in vitro for immune-complex-mediated stimulation of leukocytes and its functional characteristics with respect to monocyte adhesion. The model was based on orientation-controlled immobilization of a humanized IgG1 monoclonal antibody (rituximab) via its interaction with a biotinylated peptide epitope derived from the CD20 marker. The peptide was linked to neutravidin covalently attached to it mixed self-assembled monolayer of carboxyl- and methoxy-terminated oligo(ethylene glycol) alkane thiolates on gold. The surface adhesion propensity of human monocytes (cell line U917) was highly dependent on the lateral IgG density and indicated that there exists a distance between IgG-Fc on the surface where interactions with Fc gamma receptors are optimal. This well-defined platform allows for a careful control of the size and orientation of artificial IgG immune complexes, it is easily made compatible with, for example, cellular imaging, and it will become useful for in vitro studies on the importance of Fc gamma receptor interactions in chronic immune-mediated diseases.
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25.
  • Kanmert, Daniel, et al. (author)
  • IgG Rheumatoid Factor Against the Four Human Fc-gamma Subclasses in Early Rheumatoid Arthritis (the Swedish TIRA Project)
  • Other publication (other academic/artistic)abstract
    • Rheumatoid factor (RF), i.e. a family of autoantibodies against the Fc part of IgG, is an important seromarker of rheumatoid arthritis (RA). Traditional particle agglutination without disclosing the antibody isotype remains the predominating diagnostic method in clinical routine. Although IgG-RF attracts pathogenic interest, its detection remains technically challenging. The present study aimed at developing a set of tests identifying IgG-RFs directed against the four IgG subclasses. IgG-RF against either subclass of human IgG-Fc were analyzed with four novel enzyme-linked immunosorbent assays (ELISAs) utilizing four recombinant human Fc-gamma fragments (hIgG1-4) as sources of antigen. Sera from 40 patients with recent-onset RA (20 seropositive and 20 seronegative by IgM-RF and IgA-RF-isotype specific ELISA) were analyzed. Sera from 20 healthy blood donors served as reference. Among the IgM-/IgA-RF positive RA-sera, IgG-RF was found directed against hIgG1, hIgG4, and most notably, with strikingly high reactivity against hIgG2, but not hIgG3. Significant correlations were seen between IgG-RF against hIgG2-Fc and IgA-RF (r = 0.513) and IgM-RF (r = 0.736) levels. Further prospective studies are warranted to elucidate any correlation to disease course and outcome.
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26.
  • Kanmert, Daniel, et al. (author)
  • IgG Rheumatoid Factors Against the Four Human Fc-gamma Subclasses in Early Rheumatoid Arthritis (The Swedish TIRA Project)
  • 2012
  • In: Scandinavian Journal of Immunology. - : Blackwell Publishing. - 0300-9475 .- 1365-3083. ; 75:1, s. 115-119
  • Journal article (peer-reviewed)abstract
    • Rheumatoid factor (RF), i.e. a family of autoantibodies against the Fc part of IgG, is an important seromarker of rheumatoid arthritis (RA). Traditional particle agglutination without disclosing the antibody isotype remains the predominating diagnostic method in clinical routine. Although IgG-RF attracts pathogenic interest, its detection remains technically challenging. The present study aimed at developing a set of tests identifying IgG-RFs directed against the four IgG subclasses. IgG-RF against either subclass of human IgG-Fc were analysed with four novel enzyme-linked immunosorbent assays (ELISAs) utilizing four recombinant human Fc-gamma fragments (hIgG14) as sources of antigen. Sera from 40 patients with recent onset RA (20 seropositive and 20 seronegative by IgM-RF and IgA-RF-isotype-specific ELISA) were analysed. Sera from 20 healthy blood donors served as reference. Among the IgM-/IgA-RF-positive RA-sera, IgG-RF was found directed against hIgG1 and hIgG2, but not against hIgG3 or hIgG4. Significant correlations were seen between IgG-RF against hIgG2-Fc and IgM-RF (r = 0.666) levels. Further prospective studies are warranted to elucidate any correlation to disease course and outcome.
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27.
  • Kanmert, Daniel (author)
  • Structure and Interactions of Human IgG-Fc
  • 2011
  • Doctoral thesis (other academic/artistic)abstract
    • This thesis involves structure and interaction studies of the Fc fragment of human IgG. For this purpose, hIgG-Fc of different subclasses were cloned and expressed in the eukaryotic host Pichia pastoris, where relevant protein modification at the post-translational level can be obtained.Sometimes, changes in pH, temperature and salt concentration or addition of moderate amounts of denaturants to a protein solution are associated with the protein forming non-natively folded states, such as the molten globule or the A state. IgG and some parts thereof are capable of forming another, so called alternatively folded state, usually induced by acidification in the presence of anions. This state is in many aspects related to the molten globule and the A state but with distinguishing properties related mainly to chemical stability and formation of oligomeric structures. The first part of this thesis describes two different alternatively folded states of hIgG-Fc of subclass 4. One of them was induced by decreasing the pH of the protein solution. Observed structural changes were highly dependent on the concentration of sodium chloride. The alternatively folded protein showed drastic changes in its secondary structure compared to the native protein and significant tertiary structure was lost. Moreover, it displayed an apparently increased chemical stability and had surface exposed hydrophobic patches resulting in the formation of higher order assemblies. In addition, it was shown for the first time that thermal induction of an alternatively folded state is also possible, with similar, but not identical, properties as the acid-induced state. Heat incubation for 20 hours at neutral pH and at a physiological salt concentration further resulted in the formation of protein aggregates. The dye Congo red had affinity for these aggregates, and when viewed under polarized light, it showed green birefringence. They also displayed binding of Thioflavin T and had a typical fibril appearance in the transmission electron microscope. Hence, the formed aggregates share key properties with structures constituting amyloid.The second part of this thesis is focused on interactions of the Fc-fragment with respect to both Fcγ-receptors on monocytes and the IgG autoantibody rheumatoid factor. Immune complexes and their binding to Fcγ-receptors are of pathogenic interest to rheumatoid arthritis. A surface mimic presenting full IgG molecules was designed as an in vitro immune complex model. Utilizing self-assembled monolayers composed of alkanethiolates with different chemical functionalities, the lateral IgG density could be tuned, enabling control of monocyte interaction with the surface. Importantly, the IgG molecules were homogeneously oriented to expose the Fc-fragment. The protein repellent properties of these  surfaces ensured that only differences in IgG concentration determined variations in cellular adhesion. In a separate study the specificities of IgG rheumatoid factor with respect to the different subclasses of hIgG-Fc were investigated, using sera from patients with early rheumatoid arthritis. Strikingly high IgG-RF reactivity against hIgG2-Fc was observed, together with raised levels against hIgG1-Fc and hIgG4-Fc. No reactivity against hIgG3-Fc was found.
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28.
  • Karlsson, Jesper, et al. (author)
  • Associations of C-reactive protein isoforms with systemic lupus erythematosus phenotypes and disease activity
  • 2022
  • In: Arthritis Research & Therapy. - : BioMed Central (BMC). - 1478-6362. ; 24
  • Journal article (peer-reviewed)abstract
    • Background: Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by a large production of autoantibodies and deficient clearance of cellular waste. The disease typically oscillates between episodes of elevated disease activity and quiescent disease. C-reactive protein (CRP) is a pentameric acute-phase protein usually reflecting inflammation and tissue damage. However, despite increased inflammation and elevated interleukin-6, the levels of CRP typically remain low or only slightly raised in SLE. Under certain conditions, pentameric CRP (pCRP) can dissociate into its monomeric isoform (mCRP), which mainly has been ascribed pro-inflammatory properties. The present study aims to investigate the potential relationship between pCRP and mCRP, respectively, with disease activity and clinical features of SLE.Methods: The levels of pCRP and mCRP were measured, by turbidimetry (high-sensitive) and sandwich enzyme-linked immunosorbent assay (ELISA) respectively, in serum samples from 160 patients with SLE and 30 patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). Twenty-two of the SLE cases were selected for analysis at two time-points; quiescent disease and active disease. The two CRP isoforms were evaluated in relation to disease activity and clinical features in the two diseases.Results: Levels of pCRP and mCRP were significantly lower in SLE than AAV (p < 0.001) and the ratio of mCRP/pCRP was higher in SLE compared to AAV. The mCRP/pCRP ratio was higher for patients in remission and able to significantly separate between active/quiescent disease in paired, but not in non-paired, samples from patients with SLE. Significant correlations were observed with SLICC/ACR damage index for pCRP levels as well as inversely with the mCRP/pCRP ratio. Lower mCRP levels associated with malar rash.Conclusion: As the interrelationship between the two isoforms appear to (a) discriminate between quiescent and active SLE and (b) differ between SLE and AAV, our data indicates that the two CRP isoforms could exert contrasting immunological effects and/or reflect different milieus. Given the biological effects of mCRP, it is possible that altered levels may indicate increased opsonization of immune complexes and apoptotic debris, and thereby prevent their deposition outside the reticuloendothelial system and manifestations such as lupus nephritis and lupus-related skin disease.
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29.
  • Karlsson, Jesper, et al. (author)
  • Extracellular vesicles opsonized by monomeric C-reactive protein (CRP) are accessible as autoantigens in patients with systemic lupus erythematosus and associate with autoantibodies against CRP
  • 2023
  • In: Journal of Autoimmunity. - : Elsevier BV. - 0896-8411 .- 1095-9157. ; 139
  • Journal article (peer-reviewed)abstract
    • The pentraxin C-reactive protein (CRP) is a pentameric protein now known to be able to undergo dissociation into a monomeric, modified isoform, referred to as mCRP. In carefully assessing the bioactivities of each isoform, mCRP has strong pro-inflammatory activities while pCRP has mild anti-inflammatory activities. Systemic lupus erythematosus (SLE) is a disease characterized by a vast number of autoantibodies, including anti-CRP autoan-tibodies which have been associated with SLE disease activity and lupus nephritis. The origin of these autoan-tibodies is currently unknown. Extracellular vesicles (EVs) have been implicated in SLE pathogenesis as they can expose nuclear antigens on their outside surface, thereby being a potential adjuvant for the generation of au-toantibodies. Herein, we studied exposure of both pCRP and mCRP on EVs in SLE plasma and the implications of each in disease activity, organ damage and clinical manifestations. We used flow cytometry to detect CRP iso-forms on EV surfaces in 67 well-characterized SLE patients and 60 sex-and age-matched healthy controls. Au-toantibodies against mCRP were measured using ELISA. We found an abundance of both pCRP and mCRP on SLE EVs compared to controls. Furthermore, mCRP+ but not pCRP+ EVs were elevated in patients with active disease and in anti-CRP positive patients. The proportions of mCRP+ EVs were lower in patients with acquired organ damage, especially in patients with lupus nephritis (LN), and displayed an inverse relationship with disease duration in LN and patients with active disease. Speculatively, these data suggest EV-bound mCRP as a relevant factor in SLE pathogenesis, which could contribute to development of anti-CRP autoantibodies by stimulating an immune response.
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30.
  • Kastbom, Alf, et al. (author)
  • Changes in anti-citrullinated protein antibody isotype levels in relation to disease activity and response to treatment in early rheumatoid arthritis
  • 2018
  • In: Clinical and Experimental Immunology. - : Wiley-Blackwell Publishing Inc.. - 0009-9104 .- 1365-2249. ; 194:3, s. 391-399
  • Journal article (peer-reviewed)abstract
    • Rheumatoid arthritis (RA) is a chronic inflammatory disease where serum analysis of anti-citrullinated peptide/protein antibodies (ACPA) is an important diagnostic/prognostic tool. Levels and changes of ACPA in RA patients have been studied previously in relation to disease course and therapy response, but less is known regarding ACPA isotype changes in early RA. Hence, recent-onset RA patients (n = 231) were subjected to a 3-year clinical and radiological follow-up. Serum samples were serially collected and ACPA isotypes were analysed using the second-generation cyclic citrullinated peptide (CCP) as capture antigen. Changes in ACPA isotype levels and status were related to disease course and pharmacotherapy. At inclusion, 74% of the patients tested positive for ACPA IgG; 55% for immunoglobulin (Ig)A, 37% for secretory IgA (SIgA) and 35% for IgM. The proportion of positive patients decreased significantly at follow-up regarding ACPA SIgA, IgM and IgA. During the initial 3 months, reduction of the 28-joint disease activity score (DAS28) correlated with reduced levels of ACPA IgG (Rho = 0 center dot 242, P = 0 center dot 003), IgA (Rho = 0 center dot 260, P = 0 center dot 008), IgM (Rho = 0 center dot 457, P amp;lt; 0 center dot 001) and SIgA (Rho = 0 center dot 402, P amp;lt; 0 center dot 001). Levels of ACPA SIgA (P = 0 center dot 008) and IgM (P = 0 center dot 021) decreased significantly among patients with good response to treatment, which was not seen regarding ACPA IgA or IgG. Changes in ACPA isotype levels were not associated with radiographic damage. In conclusion, ACPA SIgA and IgM declined rapidly upon anti-rheumatic therapy and correlated with decreased disease activity in recent-onset RA. This may indicate that down-regulation of mucosal immunity to citrullinated proteins/peptides and recruitment of new B cells are key features of therapy responses in early RA.
  •  
31.
  • Lewander, Per, et al. (author)
  • Circulating cartilage oligomeric matrix protein in juvenile idiopathic arthritis
  • 2017
  • In: Scandinavian Journal of Rheumatology. - : TAYLOR & FRANCIS LTD. - 0300-9742 .- 1502-7732. ; 46:3, s. 194-197
  • Journal article (peer-reviewed)abstract
    • Objectives: Raised serum cartilage oligomeric matrix protein (sCOMP) has been reported to predict erosive disease in early rheumatoid arthritis (RA). In juvenile idiopathic arthritis (JIA), subnormal sCOMP levels have been associated with ongoing inflammation and growth retardation. In this study we aimed to assess sCOMP, C-reactive protein (CRP), and insulin-like growth factor (IGF)-1 in children/adolescents with JIA and in referents.Method: We enrolled 52 JIA patients at planned outpatient visits and 54 inpatients with ongoing infection (infection referents). A total of 120 referents testing negative for immunoglobulin (Ig)E-mediated allergy (IgE referents) served as controls. All serum samples were analysed for COMP, IGF-1, and CRP.Results: The average sCOMP level was highest among the IgE referents and lowest among the infection referents. In the JIA patients, the level of sCOMP was not associated with the level of CRP or with clinical signs of disease activity.Conclusions: The results of this study do not support routine clinical analysis of sCOMP levels in patients with JIA.
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32.
  • Lewander, Per, et al. (author)
  • Serum levels of soluble urokinase plasminogen activator receptor in juvenile idiopathic arthritis: a single-center Swedish case-control study
  • 2023
  • In: Pediatric Rheumatology. - : BMC. - 1546-0096. ; 21:1
  • Journal article (peer-reviewed)abstract
    • ObjectivesReliable biomarkers in the early stages of idiopathic arthritis (JIA) are scarce and the disease heterogeneity makes it clinically challenging to predict the risk of joint damage. Biomarkers with prognostic potential are warranted in order to individualize treatment and follow-up in JIA. The soluble urokinase plasminogen activator receptor (suPAR) has been reported as an easily measurable biomarker for prognosis and severity in several rheumatic diseases but it has never been studied in JIA.MethodsSera from 51 well-characterized patients with JIA and 50 age- and sex-matched control subjects were collected and stored for later analysis of suPAR. Patients were carefully followed clinically over 3 years and analysis of erythrocyte sedimentation rate, C-reactive protein, rheumatoid factor (RF) and antibodies against cyclic citrullinated peptides (anti-CCP) were analyzed as part of clinical routine. Signs of joint erosions were evaluated by radiography.ResultsOverall, the levels of suPAR did not differ significantly between JIA patients and controls but those with polyarticular involvement showed higher suPAR (p = 0.013). In addition, elevated suPAR were associated with joint erosions (p = 0.026). Two RF/anti-CCP negative individuals with erosions showed high levels of suPAR.ConclusionsWe present new data on the biomarker suPAR in JIA. Our results indicate that, apart from RF and anti-CCP, analysis of suPAR could be of additional value in assessing the risk of erosions. Analysis of suPAR early could potentially guide treatment decision-making in JIA, but our observations should be confirmed in prospective studies.
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33.
  • Martinsson, Klara, et al. (author)
  • Elevated free secretory component in early rheumatoid arthritis and prior to arthritis development in patients at increased risk
  • 2020
  • In: Rheumatology. - : Oxford University Press. - 1462-0324 .- 1462-0332. ; 59:5, s. 979-987
  • Journal article (peer-reviewed)abstract
    • Objectives. Considering growing evidence of mucosal involvement in RA induction, this study investigated circulating free secretory component (SC) in patients with either recent-onset RA or with ACPA and musculoskeletal pain. Methods. Two prospective cohorts were studied: TIRA-2 comprising 452 recent-onset RA patients with 3 years of clinical and radiological follow-up, and TIRx patients (n = 104) with ACPA IgG and musculoskeletal pain followed for 290 weeks (median). Blood donors and three different chronic inflammatory diseases served as controls. Free SC was analysed by sandwich ELISA. Results. Serum levels of free SC were significantly higher in TIRA-2 patients compared with TIRx and all control groups (P < 0.01). Among TIRx patients who subsequently developed arthritis, free SC levels were higher compared with all control groups (P < 0.05) except ankylosing spondylitis (P = 0.74). In TIRA-2, patients with ACPA had higher baseline levels of free SC compared with ACPA negative patients (P < 0.001). Free SC status at baseline did not predict radiographic joint damage or disease activity over time. In TIRx, elevated free SC at baseline trendwise associated with arthritis development during follow-up (P = 0.066) but this disappeared when adjusting for confounders (P = 0.72). Cigarette smoking was associated with higher levels of free SC in both cohorts. Conclusion. Serum free SC levels are increased in recent-onset RA compared with other inflammatory diseases, and associate with ACPA and smoking. Free SC is elevated before arthritis development among ACPA positive patients with musculoskeletal pain, but does not predict arthritis development. These findings support mucosal engagement in RA development.
  •  
34.
  • Martinsson, Klara, et al. (author)
  • Extramucosal Formation and Prognostic Value of Secretory Antibodies in Rheumatoid Arthritis
  • 2022
  • In: Arthritis & Rheumatology. - Hoboken, NJ, United States : John Wiley & Sons. - 2326-5191 .- 2326-5205. ; 74:5, s. 801-809
  • Journal article (peer-reviewed)abstract
    • Objective To investigate levels and possible extramucosal formation of secretory Ig, including anti-citrullinated protein antibodies (ACPAs), in rheumatoid arthritis (RA). Methods Three patient groups were studied: 1) ACPA-positive patients with musculoskeletal pain without clinical arthritis, 2) patients with recent-onset RA, and 3) patients with established RA. In baseline serum samples (groups 1 and 2) and paired synovial fluid samples (group 3), we analyzed total secretory IgA, total secretory IgM, free secretory component (SC), and SC-containing ACPA. Extramucosal formation of SC-containing ACPA was investigated by preincubating RA sera and affinity-purified ACPA with recombinant free SC.Results Compared to healthy controls, serum levels of total secretory IgA and total secretory IgM were increased both in patients with early RA and at-risk patients (P < 0.05). Patients with early RA with elevated total secretory Ig had significantly higher disease activity during the 3-year follow-up period compared to those without increased levels. At-risk patients who developed arthritis during follow-up (39 of 82) had higher baseline total secretory IgA levels compared to those who did not (P = 0.041). In established RA, total secretory IgA and total secretory IgM levels were higher in serum than in synovial fluid (P < 0.0001), but SC-containing ACPAs adjusted for total secretory Ig concentration were higher in synovial fluid (P < 0.0001). Preincubation with recombinant free SC yielded increased SC-containing ACPA reactivity in sera as well as in affinity-purified IgA and IgM ACPA preparations.Conclusion Circulating secretory Ig are elevated before and at RA onset. In the presence of free SC, secretory Ig may form outside the mucosa, and SC-containing ACPAs are enriched in RA joints. These findings shed important new light on the mucosal connection in RA development.
  •  
35.
  • Nimeri, G, et al. (author)
  • Oxygen radical production in neutrophils interacting with platelets and surface-immobilized plasma proteins : role of tyrosine phosphorylation
  • 2003
  • In: Journal of Biomedical Materials Research. - : Wiley. - 0021-9304 .- 1097-4636 .- 1549-3296. ; 67A:2, s. 439-447
  • Journal article (peer-reviewed)abstract
    • The interaction between neutrophil granulocytes and platelets is considered to play an important role in the inflammatory process induced by an implanted foreign material. However, the cellular mechanisms involved remain incompletely understood. We used a luminol-dependent chemiluminescence (CL) technique to analyze the generation of reactive oxygen species (ROS) in human neutrophils interacting with different plasma protein-coated surfaces in the presence or absence of unstimulated or stimulated platelets. The role of tyrosine phosphorylation in the regulation of NADPH oxidase activity was evaluated with quantitative fluorescence microscopy and the specific tyrosine kinase inhibitor genistein. We found that the ROS-production is 2 to 3 times higher in neutrophils on immunoglobulin G (IgG)coated surfaces than in cells interacting with albumin- or fibrinogen-coated surfaces. Incubation with superoxide dismutase and catalase revealed that about 45% of the ROS was released extracellularly on IgG surfaces whereas corresponding values were 90% and 85% in neutrophils interacting with albumin and fibrinogen, respectively. The presence of platelets markedly increased the extracellular generation of ROS, mainly in neutrophils. interacting with IgG- or fibrinogen-coated surfaces whereas the intracellular production was only modestly affected. Quantitative fluorescence microscopy of neutrophils stained with FITC-conjugated anti-phosphotyrosine antibodies showed a correlation between tyrosine phosphorylation, cell spreading, and ROS production. Platelets markedly amplified the anti-phosphotyrosine staining on both fibrinogen- and IgG-coated surfaces whereas the low level of tyrosine phosphorylation in neutrophils on albumin-coated surfaces was not further elevated by platelets. Furthermore, the tyrosine kinase inhibitor genistein inhibited both extra- and intracellular ROS production in neutrophils regardless of the presence of platelets. We demonstrate that plasma protein coating and the presence of platelets are crucial for the inflammatory response of adhering neutrophils and that the oxidative response correlates with the extent of tyrosine phosphorylation of proteins in focal contacts. (C) 2003 Wiley Periodicals, Inc.
  •  
36.
  • Nimeri, G, et al. (author)
  • The influence of plasma proteins and platelets on oxygen radical production and F-actin distribution in neutrophils adhering to polymer surfaces
  • 2002
  • In: Biomaterials. - 0142-9612 .- 1878-5905. ; 23:8, s. 1785-1795
  • Journal article (peer-reviewed)abstract
    • It is well known that blood cell interactions with artificial surfaces might have deleterious effects on host tissue, however, the mechanisms involved are far from understood. In this study, neutrophil-platelet interaction on uncoated or protein-coated polymer surfaces was investigated. Cell spreading, reorganization of actin filaments and release of oxygen metabolites (measured as luminol-amplified chemiluminescence) were used as criteria for cell activation on positively charged, hydrophilic 1,2-diaminocyclohexane, and negatively charged, hydrophobic hexamethylene-disiloxane. The model surfaces were made by radio frequency plasma discharge polymerization. Neutrophil contact with the uncoated polymers induced a prolonged generation of oxygen radicals. Precoating of the polymer surfaces with human serum albumin (HSA) or fibrinogen, markedly reduced neutrophil activation, whereas coating with human immunoglobulin G (IgG), a well-known opsonin, resulted in significantly higher levels of cell activation. Consequently, protein coating overruled the activating effects of the polymer surfaces. The presence of unstimulated or thrombin-stimulated platelets markedly increased the reactivity of neutrophils against fibrinogen- and IgG-coated surfaces. However, neutrophils remained relatively unreactive in the presence of platelets on HSA-treated surfaces. Comparison of the different types of surfaces used, reveals a correlation between the degree of cell spreading, reorganization of the actin cytoskeleton and the amount of oxygen radicals produced. Our results suggest that the acute inflammatory reaction on a biomaterial surface is highly dependent on the nature and composition of the first adsorbed protein layer and the extent of platelet activation.
  •  
37.
  • Olsson, Lina M., et al. (author)
  • A single nucleotide polymorphism in the NCF1 gene leading to reduced oxidative burst is associated with systemic lupus erythematosus
  • 2017
  • In: Annals of the Rheumatic Diseases. - : BMJ Publishing Group Ltd. - 0003-4967 .- 1468-2060. ; 76:9, s. 1607-1613
  • Journal article (peer-reviewed)abstract
    • OBJECTIVES: Ncf1 polymorphisms leading to low production of reactive oxygen species (ROS) are strongly associated with autoimmune diseases in animal models. The human NCF1 gene is very complex with both functional and non-functional gene copies and genotyping requires assays specific for functional NCF1 genes. We aimed at investigating association and function of the missense single nucleotide polymorphism (SNP), rs201802880 (here denoted NCF1-339) in NCF1 with systemic lupus erythematosus (SLE).METHODS: We genotyped the NCF1-339 SNP in 973 Swedish patients with SLE and 1301 controls, using nested PCR and pyrosequencing. ROS production and gene expression of type 1 interferon-regulated genes were measured in isolated cells from subjects with different NCF1-339 genotypes.RESULTS: We found an increased frequency of the NCF1-339 T allele in patients with SLE, 11% compared with 4% in controls, OR 3.0, 95% CI 2.4 to 3.9, p=7.0×10(-20). The NCF1-339 T allele reduced extracellular ROS production in neutrophils (p=0.004) and led to an increase expression of type 1 interferon-regulated genes. In addition, the NCF1-339 T allele was associated with a younger age at diagnosis of SLE; mean age 30.3 compared with 35.9, p=2.0×1(-6).CONCLUSIONS: These results clearly demonstrate that a genetically controlled reduced production of ROS increases the risk of developing SLE and confirm the hypothesis that ROS regulate chronic autoimmune inflammatory diseases.
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38.
  • Pettersson, Sofia, 1977- (author)
  • Biodegradable gelatin microcarriers in tissue engineering : In vitro studies on cartilage and bone
  • 2009
  • Doctoral thesis (other academic/artistic)abstract
    • Tissue engineering is a multidisciplinary field that combines cells, biomaterial scaffolds and environmental factors to achieve functional tissue repair. This thesis focuses on the use of macroporous gelatin microcarriers as scaffolds in tissue engineering applications, with a special focus on cartilage and bone formation by human adult cells in vitro.In our first study, human articular chondrocytes were seeded on macroporous gelatin microcarriers. The microcarriers were subsequently encapsulated in coagulated blood-derived biological glues and cultured under free-swelling conditions for up to 17 weeks. Even in the absence of recombinant chondrogenic growth factors, the chondrocytes remained viable and metabolically active for the duration of the culture period, as indicated by an increased amount of cell nuclei and extracellular matrix (ECM). The ECM showed several cartilage characteristics, but lacked the cartilage specific collagen type II. Furthermore, ECM formation was seen primarily in a capsule surrounding the tissue-engineered constructs, leading to the conclusion that the used in vitro models were unable to support true cartilage formation.The capacity of human dermal fibroblasts to produce cartilage- and bone-like tissue in the previously mentioned model was also investigated. Under the influence of chondrogenic induction factors, including TGF-β1 and insulin, the fibroblasts produced cartilage specific molecules, as confirmed by indirect immunohistochemistry, however not collagen type II. Under osteogenic induction, by dexamethasone, ascorbate-2-phosphate and β–glycerophosphate, the fibroblasts formed a calcified matrix with bone specific markers, and an alkaline phosphatase assay corroborated a shift towards an osteoblast like phenotype. The osteogenic induction was enhanced by flow-induced shear stress in a spinner flask system.In addition, four different types of gelatin microcarriers, differing by their internal pore diameter and their degree of gelatin cross-linking, were evaluated for their ability to support chondrocyte expansion. Chondrocyte densities on the microcarriers were monitored every other day over a twoweek period, and chondrocyte growth was analyzed by piecewise linear regression and analysis of variance (ANOVA). No differences were seen between the different microcarriers during the first week. However, during the second week of culture both microcarrier pore diameter and gelatin crosslinking had significant impacts on chondrocyte density.Lastly, a dynamic centrifugation regime (f=12.5 mHz for 16 minutes every other day) was administered to chondrocyte-seeded microcarriers, with or without encapsulation in platelet rich plasma (PRP), to study the possible effect of dynamic stimuli on cartilage formation. Presence of PRP enhanced the structural stability of the tissue-engineered constructs, but we were not able to confirm any dose-response pattern between ECM formation and the applied forces. After 12 weeks, distinct gelatin degradation had occurred independent of both dynamic stimuli and presence of PRP.In summary, this thesis supports a plausible use for gelatin microcarriers in tissue engineering of cartilage and bone. Microcarrier characteristics, specifically gelatin cross-linking and pore diameter, have been shown to affect chondrocyte expansion. In addition, the use of human dermal fibroblasts as an alternative cell source for cartilage and bone formation in vitro was addressed.
  •  
39.
  • Pettersson, Sofia, et al. (author)
  • Cell expansion of human articular chondrocytes on macroporous gelatine scaffolds : — impact of micro carrier selection on cell proliferation
  • 2011
  • In: Biomedical Materials. - Bristol, UK : Institute of Physics Publishing Ltd.. - 1748-6041 .- 1748-605X. ; 6:6, s. 065001-
  • Journal article (peer-reviewed)abstract
    • This study investigates human chondrocyte expansion on four macroporous gelatine microcarriers (CultiSpher) differing with respect to two manufacturing processes—the amount of emulsifier used during initial preparation and the gelatine cross-linking medium. Monolayer-expanded articular chondrocytes from three donors were seeded onto the microcarriers and cultured in spinner flask systems for a total of 15 days. Samples were extracted every other day to monitor cell viability and establish cell counts, which were analysed using analysis of variance and piecewise linear regression. Chondrocyte densities increased according to a linear pattern for all microcarriers, indicating an ongoing, though limited, cell proliferation. A strong chondrocyte donor effect was seen during the initial expansion phase. The final cell yield differed significantly between the microcarriers and our results indicate that manufacturing differences affected chondrocyte densities at this point. Remaining cells stained positive for chondrogenic markers SOX-9 and S-100 but extracellular matrix formation was modest to undetectable. In conclusion, the four gelatine microcarriers supported chondrocyte adhesion and proliferation over a two week period. The best yield was observed for microcarriers produced with low emulsifier content and cross-linked in water and acetone. These results add to the identification of optimal biomaterial parameters for specific cellular processes and populations.
  •  
40.
  • Pettersson, Sofia, et al. (author)
  • Human articular chondrocytes on macroporous gelatin microcarriers form structurally stable constructs with blood-derived biological glues in vitro.
  • 2009
  • In: Journal of tissue engineering and regenerative medicine. - : Hindawi Limited. - 1932-7005 .- 1932-6254. ; 3:6, s. 450-60
  • Journal article (peer-reviewed)abstract
    • Biodegradable macroporous gelatin microcarriers fixed with blood-derived biodegradable glue are proposed as a delivery system for human autologous chondrocytes. Cell-seeded microcarriers were embedded in four biological glues-recalcified citrated whole blood, recalcified citrated plasma with or without platelets, and a commercially available fibrin glue-and cultured in an in vitro model under static conditions for 16 weeks. No differences could be verified between the commercial fibrin glue and the blood-derived alternatives. Five further experiments were conducted with recalcified citrated platelet-rich plasma alone as microcarrier sealant, using two different in vitro culture models and chondrocytes from three additional donors. The microcarriers supported chondrocyte adhesion and expansion as well as extracellular matrix (ECM) synthesis. Matrix formation occurred predominantly at sample surfaces under the static conditions. The presence of microcarriers proved essential for the glues to support the structural takeover of ECM proteins produced by the embedded chondrocytes, as exclusion of the microcarriers resulted in unstable structures that dissolved before matrix formation could occur. Immunohistochemical analysis revealed the presence of SOX-9- and S-100-positive chondrocytes as well as the production of aggrecan and collagen type I, but not of the cartilage-specific collagen type II. These results imply that blood-derived glues are indeed potentially applicable for encapsulation of chondrocyte-seeded microcarriers. However, the static in vitro models used in this study proved incapable of supporting cartilage formation throughout the engineered constructs.
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41.
  • Pettersson, Sofia, et al. (author)
  • The Role of Platelet Rich Plasma and Dynamic Centrifugation on Extracellular Matrix Formation of Human Articular Chondrocytes on Macroporous Gelatin Microcarriers in Pellet Culture
  • Other publication (other academic/artistic)abstract
    • Platelet rich plasma (PRP) has been investigated for its beneficial use in cartilage tissue engineering previously. Here, we address the effect of using PRP as encapsulating agent for gelatin-supported chondrocyte pellet culture in vitro. Furthermore, the concept of using dynamic centrifugation to stimulate extracellular matrix (ECM) formation of the chondrocytes is explored. Human articular chondrocytes were expanded on macroporous gelatin microcarriers in a spinner flask system. The cell-seeded microcarriers were allowed to form pellets with or without re-calcified citrated PRP, and subjected to dynamic centrifugation (f = 0.0125 Hz) for a total of 16 min every other day using a standard tabletop centrifuge. Three acceleration curves with differing top speeds (corresponding to 500 g, 1500 g and 3000 g respectively) were used for the experimental groups and unstimulated controls were set for comparison. Pellets were kept in culture for up to 12 weeks, paraffin embedded and sectioned for histological and immunohistochemical analysis. Results showed increasing numbers of cells and ECM with time, as well as a gradual degradation of the gelatin microcarriers, indicating ongoing cell proliferation and metabolism throughout the culture period. Cell densities and ECM formation were more pronounced in the PRP-containing groups after four weeks, although this difference diminished with time. At the last time point several cartilage markers were found in the produced ECM, however including the fibrocartilaginous marker collagen type I. Dynamic centrifugation did not visibly increase the ECM accumulation over the 12-week duration of this experiment, although non-conclusive indications of collagen fiber organization were seen in the two groups with the highest acceleration limits at the last time point.
  •  
42.
  • Roos, Karin, et al. (author)
  • Circulating anti-citrullinated protein antibodies containing secretory component are prognostic for arthritis onset in at-risk patients
  • 2021
  • In: Clinical and Experimental Immunology. - : Wiley. - 0009-9104 .- 1365-2249. ; 204:3, s. 344-351
  • Journal article (peer-reviewed)abstract
    • Autoantibodies related to rheumatoid arthritis (RA), such as anti-citrullinated protein antibodies (ACPA), are often detectable in the preclinical period years before arthritis onset. However, events triggering arthritis development remain incompletely known. We aimed to determine whether ACPA isotype levels are prognostic for arthritis development in patients presenting with immunoglobulin (Ig)G ACPA and musculoskeletal pain. Study participants (n = 82) had musculoskeletal pain of any sort and duration and a positive IgG ACPA test. None of the patients had arthritis upon clinical examination at baseline, but during follow-up (mean = 6 years), 48% developed at least one arthritic joint. IgG, IgA, IgM and secretory component (SC)-containing ACPA was measured in longitudinally collected serum samples. Cox regression analysis was performed to test the prognostic value of baseline antibody levels and changes over time. All analysed ACPA isotype levels were associated with arthritis development in univariable Cox regression analysis. In multivariable analysis, baseline SC ACPA levels were independently prognostic for arthritis development in multivariable analysis [hazard ratio (HR) = 1 center dot 006, 95% confidence interval (CI) = 1 center dot 001-1 center dot 010, P = 0 center dot 012]. There were no significant changes in ACPA isotype levels over time, and no significant association between changes over time and arthritis development. In this prospective longitudinal study, baseline serum SC ACPA levels, but neither IgG, IgA nor IgM ACPA are prognostic for future arthritis development. Repeated measurement of ACPA isotypes do not bring additional prognostic value. The results reinforce a mucosal connection in RA development and encourage further exploration of the mechanisms underlying secretory ACPA formation as a trigger for arthritis development.
  •  
43.
  • Roos Ljungberg, Karin, et al. (author)
  • Presence of salivary IgA anti-citrullinated protein antibodies associate with higher disease activity in patients with rheumatoid arthritis
  • 2020
  • In: Arthritis Research & Therapy. - : BMC. - 1478-6362. ; 22
  • Journal article (peer-reviewed)abstract
    • Background: Circulating IgA anti-citrullinated protein antibodies (ACPA) associate with more active disease, but a previous study implied that salivary IgA ACPA is related to a less severe disease. Therefore, we aimed to characterize the IgA ACPA response in the saliva and serum in relation to clinical picture and risk factors among patients with rheumatoid arthritis (RA).Methods: RA patients (n=196) and healthy blood donors (n=101), included in the cross-sectional study "Secretory ACPA in Rheumatoid Arthritis" (SARA), were analyzed for ACPA of IgA isotype, and for subclasses IgA1 and IgA2 ACPA in paired saliva and serum samples using modified enzyme-linked immunosorbent assays (ELISA) targeting reactivity to a cyclic citrullinated peptide (anti-CCP). Cutoff levels for positive tests were set at the 99th percentile for blood donors. Antibody levels were related to clinical characteristics, radiographic damage, smoking habits, and carriage of HLA-DRB1/shared epitope (SE).Results: IgA ACPA in the saliva was found in 12% of RA patients, IgA1 occurred in 10%, and IgA2 in 9%. In serum, IgA ACPA was found in 45% of the patients, IgA1 in 44%, and IgA2 in 39%. Levels of IgA ACPA in the saliva correlated significantly with serum levels of IgA (r=0.455). The presence of salivary IgA ACPA was associated with a higher erythrocyte sedimentation rate (ESR), 28-joint disease activity score, tender joint count, and patient global assessment at the time of sampling. None of the antibodies was associated with smoking, SE, or radiographic damage.Conclusion: Salivary IgA ACPAs were detected in a subset of RA patients in association with higher disease activity. This suggests that mucosal ACPA responses in the oral cavity may contribute to disease-promoting processes in RA.
  •  
44.
  • Roos Ljungberg, Karin, 1988- (author)
  • Secretory Autoantibodies in Rheumatoid Arthritis
  • 2022
  • Doctoral thesis (other academic/artistic)abstract
    • Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease in which autoantibodies, such as anti-citrullinated protein antibodies (ACPA), can be detected in the serum of patients. Autoantibodies may appear in the circulation years before clinical signs of joint inflammation occur, indicating that early immunological pathogenetic steps take place outside of the joints. Although many of these mechanisms are currently unknown, the initial events leading up to ACPA production are thought to occur at mucosal surfaces. In this thesis, mucosa-associated secretory ACPA are investigated in the circulation and in local mucosal secretions to: (i) improve the understanding of the mucosal connection in RA; and (ii) investigate whether these antibodies can improve diagnostics and prognostics in early RA. We identified circulating secretory component containing (SC) ACPA in a subpopulation of patients (both early and established RA) and at-risk patients, with a prevalence of 16%-21%. In addition, SC ACPA was detected in bronchoalveolar lavage fluid (BALF) and IgA ACPA in saliva, indicating local production in the lungs and in the oral cavity. In at-risk patients who were positive for IgG ACPA, we found that the levels of circulating SC ACPA at inclusion predicted arthritis development. Circulating SC ACPA was associated with higher disease activity, including increased levels of inflammatory markers, in patients with early RA. Levels of circulating SC ACPA were associated with high-resolution computed tomography (HRCT) findings (parenchymal lung abnormalities and bronchiectasis) and smoking, but not with risk genes (shared epitope). We confirmed the presence of salivary ACPA and identified a novel association with increased disease activity and functional disability. In summary, SC ACPA is present in the sera of patients with RA who manifest different phases of the disease, and we found associations with arthritis onset, smoking, systemic inflammation, and lung abnormalities. SC ACPA is also detectable in mucosal secretions from the lungs and the oral cavity. These findings suggest that mucosal ACPA production may be an important factor in RA development and progression, and that serum SC ACPA should be further evaluated as a prognostic marker for disease onset among at-risk individuals. 
  •  
45.
  • Saleh, Muna, et al. (author)
  • Variation of Complement Protein Levels in Maternal Plasma and Umbilical Cord Blood during Normal Pregnancy : An Observational Study
  • 2022
  • In: Journal of Clinical Medicine. - : MDPI AG. - 2077-0383. ; 11:13
  • Journal article (peer-reviewed)abstract
    • The complement system constitutes a crucial part of the innate immunity, mediating opsonization, lysis, inflammation, and elimination of potential pathogens. In general, there is an increased activity of the complement system during pregnancy, which is essential for maintaining the host's defense and fetal survival. Unbalanced or excessive activation of the complement system in the placenta is associated with pregnancy complications, such as miscarriage, preeclampsia, and premature birth. Nonetheless, the actual clinical value of monitoring the activation of the complement system during pregnancy remains to be investigated. Unfortunately, normal reference values specifically for pregnant women are missing, and for umbilical cord blood (UCB), data on complement protein levels are scarce. Herein, complement protein analyses (C1q, C3, C4, C3d levels, and C3d/C3 ratio) were performed in plasma samples from 100 healthy, non-medicated and non-smoking pregnant women, collected during different trimesters and at the time of delivery. In addition, UCB was collected at all deliveries. Maternal plasma C1q and C3d/C3 ratio showed the highest mean values during the first trimester, whereas C3, C4, and C3d had rising values until delivery. We observed low levels of C1q and C4 as well as increased C3d and C3d/C3 ratio, particularly during the first trimester, as a sign of complement activation in some women. However, the reference limits of complement analyses applied for the general population appeared appropriate for the majority of the samples. As expected, the mean complement concentrations in UCB were much lower than in maternal plasma, due to the immature complement system in neonates.
  •  
46.
  • Shleev, Sergey, et al. (author)
  • Electrochemical characterization and application of azurin-modified gold electrodes for detection of superoxide
  • 2006
  • In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 22:2, s. 213-219
  • Journal article (peer-reviewed)abstract
    • A novel biosensor for superoxide radical (O2{radical dot}-) detection based on Pseudomonas aeruginosa azurin immobilized on gold electrode was designed. The rate constant of azurin reduction by O2{radical dot}- was found to be 105 M-1 s-1 in solution and five times lower, i.e., 0.2 × 105 M-1 s-1, for azurin coupled to gold by 3,3′-dithiobis(sulfosuccinimidylpropionate) (DTSSP). The electron transfer rate between the protein and the electrode ranged from 2 to 6 s-1. The sensitivity of this biosensor to O2{radical dot}- was 6.8 × 102 A m-2 M-1. The response to the interference substances, such as uric acid, H2O2, and dimethylsulfoxide was negligible below 10 μM. The electrode was applied in three O2{radical dot}- generating systems: (i) xanthine oxidase (XOD), (ii) potassium superoxide (KO2), and (iii) stimulated neutrophil granulocytes. The latter was compared with luminol-amplified chemiluminescence. The biosensor responded to O2{radical dot}- in all three environments, and the signals were antagonized by superoxide dismutase. © 2006 Elsevier B.V. All rights reserved.
  •  
47.
  • Shleev, Sergey, et al. (author)
  • Simultaneous use of electrochemistry and chemiluminescence to detect reactive oxygen species produced by human neutrophils
  • 2008
  • In: Cell Biology International. - : Wiley. - 1065-6995 .- 1095-8355. ; 32:12, s. 1486-1496
  • Journal article (peer-reviewed)abstract
    • A novel approach for the simultaneous optical and electrochemical detection of biologically produced reactive oxygen species has been developed and applied. The set-up consists of a luminol-dependent chemiluminescence assay combined with two amperometric biosensors sensitive to superoxide anion radicals (O-2(center dot-))and hydrogen peroxide (H2O2), respectively. The method permits direct, real-time in vitro determination of both extra-and intracellular O-2(center dot-) and H2O2 produced by human neutrophil granulocytes. The rate of O-2(center dot-) production by stimulated neutrophils was calculated to about 10(-17) mol s(-1) per single cell. With inhibited NADPH oxidase, a distinct extracellular release of H2O2 instead of O-2(center dot-) was obtained from stimulated neutrophils with the rate of about 3 . 10(-18) mol s(-1) per single cell. When the H2O2 release was discontinued, fast H2O2 utilisation was observed. Direct interaction with and possibly attachment of neutrophils to redox protein-modified gold electrodes, resulted in a spontaneous respiratory burst in the population of cells closely associated to the electrode surface. Hence, further stimulation of human neutrophils with a potent receptor agonist (fMLF) did not significantly increase the O-2(center dot-) sensitive amperometric response. By contrast, the H2O2 sensitive biosensor, based on an HRP-modified graphite electrode, was able to reflect the bulk concentration of H2O2, produced by stimulated neutrophils and would be very useful in modestly equipped biomedical research laboratories. In summary, the system would also be appropriate for assessment of several other metabolites in different cell types, and tissues of varying complexity, with only minor electrode modifications.
  •  
48.
  • Sjöwall, Christoffer, et al. (author)
  • Beware of Antibodies to Dietary Proteins in "Antigen-specific" Immunoassays! Falsely Positive Anticytokine Antibody Tests Due to Reactivity with Bovine Serum Albumin in Rheumatoid Arthritis (The Swedish TIRA Project)
  • 2011
  • In: JOURNAL OF RHEUMATOLOGY. - : Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 38:2, s. 215-220
  • Journal article (peer-reviewed)abstract
    • Objective. To evaluate (1) to what extent sera from healthy subjects and patients with rheumatoid arthritis (RA) contain antibodies to bovine serum albumin (BSA); and (2) if anti-BSA antibodies interfere with results of enzyme-linked immunoassays (ELISA) containing BSA. Methods. The ELISA used was a previously developed in-house assay of autoantibodies to tumor necrosis factor (TNF). Anti-TNF and anti-BSA antibodies were analyzed by ELISA in 189 patients with early RA and 186 healthy blood donors. TNF preparations containing either BSA or human serum albumin (HSA) as carrier proteins were used as antigens in the anti-TNF assay. The presence and levels of antibodies were analyzed in relation to disease course and to the presence/absence of rheumatoid factor (RF). Results. In patients with RA, anti-TNF/BSA levels strongly correlated with anti-BSA levels (r = 0.81, p andlt; 0.001), whereas anti-TNF/HSA did not (r = -0.09). Neither the presence nor the levels of anti-BSA in RA patients were associated with disease progression, and antibody levels were not significantly altered compared to controls (p = 0.11). IgG reactivity with TNF/HSA was neglible. In paired sera, preincubation with BSA abolished the anti-TNF/BSA reactivity. There were no indications of RF interference with anti-BSA or anti-TNF reactivity. Conclusion. Antibodies to BSA are common in patients with RA as well as in healthy individuals. Their presence does not seem to be associated with RA disease activity or disease course, but may severely interfere with ELISA containing BSA. The use of BSA as a "blocking agent" or carrier protein in immunoassays should therefore be avoided.
  •  
49.
  • Sjöwall, Christoffer, et al. (author)
  • C-reactive protein, immunoglobulin G and complement co-localize in renal immune deposits of proliferative lupus nephritis
  • 2013
  • In: Autoimmunity. - : Informa UK Limited. - 0891-6934 .- 1607-842X. ; 46:3, s. 205-214
  • Journal article (peer-reviewed)abstract
    • The pattern recognition molecules C-reactive protein (CRP) and C1q are of big interest in relation to the pathogenesis of systemic lupus erythematosus (SLE). Circulating autoantibodies against CRP and C1q are frequently found in SLE patients with active disease, particularly in lupus nephritis (LN), and rising levels reportedly relate to disease activity and outcome. If CRP-, or dsDNA- and/or C1q-containing immune complexes (ICs) are pathogenic in LN, glomerular IgG-deposits would be expected to co-localize with these antigens. In search for proof of this concept, renal biospsies from patients with active LN (n = 5) were examined with high-resolution immunogold electron microscopy. Renal biopsies from patients with Henoch-Schonlein purpura, pauci-immune nephritis and renal cancer served as controls. IgG antibodies against CRP, C1q and nucleosomes were analyzed in pre-post flare sera. We could demonstrate that CRP, C1q, C3c and dsDNA were co-localized with IgG in electron dense deposits in the glomerular basement membrane/subendothelial space in all of the 5 LN patients. Deposits of IgG, CRP, complement and dsDNA were 10-fold higher in LN compared to controls. All SLE patients had circulating anti-nucleosome antibodies; 4/5 had serum antibodies against CRP, dsDNA, and C1q at biopsy/flare. Despite a limited number of cases, the results support the notion of a pathogenic role not only for anti-dsDNA antibodies, but also for anti-CRP and anti-C1q in LN. The glomerular ICs may have been generated by deposition of circulating ICs or by in situ IC formation.
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50.
  • Sjöwall, Christoffer, 1975-, et al. (author)
  • Pathogenic implications for autoantibodies against C-reactive protein and other acute phase proteins
  • 2007
  • In: Clinica Chimica Acta. - : Elsevier BV. - 0009-8981 .- 1873-3492. ; 378:1-2, s. 13-23
  • Journal article (peer-reviewed)abstract
    • Systemic lupus erythematosus (SLE) is a systemic rheumatic disease characterized clinically by multiorgan involvement and serologically by the occurrence of antinuclear antibodies. SLE patients may present with multiple autoantibodies to cytoplasmic and cell surface antigens as well as to circulating plasma proteins. Another feature of SLE is that serum levels of C-reactive protein (CRP) often remain low despite high disease activity and despite high levels of other acute phase proteins and interleukin-6, i.e. the main CRP inducing cytokine. Apart from its important role as a laboratory marker of inflammation, CRP attracts increasing interest due to its many intriguing biological functions, one of which is a role as an opsonin contributing to the elimination of apoptotic cell debris, e.g. nucleosomes, thereby preventing immunization against autoantigens. Recently, autoantibodies against CRP and other acute phase proteins have been reported in certain rheumatic conditions, including SLE. Although the presence of anti-CRP autoantibodies does not explain the failed CRP response in SLE, antibodies directed against acute phase proteins have several implications of pathogenetic interest. This paper thus highlights the biological and clinical aspects of native and monomeric CRP and anti-CRP, as well as autoantibodies against mannose-binding lectin, serum amyloid A and serum amyloid P component. © 2006 Elsevier B.V. All rights reserved.
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