| 1. |
- Sjöwall, Christopher, 1975-, et al.
(författare)
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Abnormal Antinuclear Antibody Titers Are Less Common Than Generally Assumed in Established Cases of Systemic Lupus Erythematosus
- 2008
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 35, s. 1994-2000
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate antinuclear antibody (ANA) tests in established cases of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) by indirect immunofluorescence microscopy (F-ANA) and enzyme-immunoassays detecting antinucleosomal antibodies (ANSA-EIA). METHODS: Sera from 50 patients with SLE and 65 patients with RA were analyzed regarding abnormal concentrations of F-ANA (serum dilution >/= 1:200 = 95th percentile among 300 healthy blood donors). The sera were also analyzed with 2 commercial ANSA-EIA kits. RESULTS: An abnormal F-ANA titer occurred in 76% of the SLE sera compared to 23% in RA, and was not related to present use of antirheumatic drugs. At dilution 1:50, 84% of the SLE sera were F-ANA-positive compared to 20% of healthy women. Forty percent and 56%, respectively, of the SLE sera tested positive in the 2 ANSA-EIA kits. By the most sensitive assay, 96% of the ANSA-positive SLE sera produced a homogenous (chromosomal) F-ANA staining pattern compared to 18% of the ANSA-negative SLE sera. Ten of the 15 F-ANA-positive RA sera (63%) generated homogenous F-ANA staining and 13 (20%) tested positive in the most sensitive ANSA-EIA, but with no correlation to the F-ANA staining pattern. CONCLUSION: The sensitivity of F-ANA at an abnormal titer was surprisingly low (76%) in established cases of SLE. ANSA occurred in 56% of the SLE sera, but also in a fair number (20%) of RA sera. Practically all ANSA-positive SLE sera were identified by chromosomal F-ANA staining. We conclude that the antigen-specific antinucleosomal EIA does not have high enough diagnostic specificity to justify use of this analysis for routine diagnostic purposes.
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| 2. |
- Sjöwall, Christopher, et al.
(författare)
-
Abnormal Antinuclear Antibody Titers Are Less Common Than Generally Assumed in Established Cases of Systemic Lupus Erythematosus.
- 2008
-
Ingår i: Journal of Rheumatology. - 0315-162X. ; 35, s. 1994-2000
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate antinuclear antibody (ANA) tests in established cases of systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) by indirect immunofluorescence microscopy (F-ANA) and enzyme-immunoassays detecting antinucleosomal antibodies (ANSA-EIA). METHODS: Sera from 50 patients with SLE and 65 patients with RA were analyzed regarding abnormal concentrations of F-ANA (serum dilution >/= 1:200 = 95th percentile among 300 healthy blood donors). The sera were also analyzed with 2 commercial ANSA-EIA kits. RESULTS: An abnormal F-ANA titer occurred in 76% of the SLE sera compared to 23% in RA, and was not related to present use of antirheumatic drugs. At dilution 1:50, 84% of the SLE sera were F-ANA-positive compared to 20% of healthy women. Forty percent and 56%, respectively, of the SLE sera tested positive in the 2 ANSA-EIA kits. By the most sensitive assay, 96% of the ANSA-positive SLE sera produced a homogenous (chromosomal) F-ANA staining pattern compared to 18% of the ANSA-negative SLE sera. Ten of the 15 F-ANA-positive RA sera (63%) generated homogenous F-ANA staining and 13 (20%) tested positive in the most sensitive ANSA-EIA, but with no correlation to the F-ANA staining pattern. CONCLUSION: The sensitivity of F-ANA at an abnormal titer was surprisingly low (76%) in established cases of SLE. ANSA occurred in 56% of the SLE sera, but also in a fair number (20%) of RA sera. Practically all ANSA-positive SLE sera were identified by chromosomal F-ANA staining. We conclude that the antigen-specific antinucleosomal EIA does not have high enough diagnostic specificity to justify use of this analysis for routine diagnostic purposes.
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| 3. |
- Sjöwall, Christopher, 1975-
(författare)
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C-reactive protein (CRP) and anti-CRP autoantibodies in systemic lupus erythematosus : a study on the occurrence and clinical implications of anti-CRP antibodies and CRP-mediated complement activation
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by production of a wide range of autoantibodies, multiple organ involvement and by local formation or tissue deposition of immune complexes (ICs) in the inflamed organs. In contrast to most systemic inflammatory conditions, and despite raised levels of pro-inflammatory cytokines, SLE flares are rarely reflected by elevated C-reactive protein (CRP), an important acute-phase reactant in man with homologs in vertebrates and several invertebrates. As a part of the innate immune system, CRP binds certain molecules exposed on the surface of dying cells/apoptotic bodies and on the surface of pathogens and mediates their elimination by uptake in the reticuloendothelial system. CRP also interacts with IgG-containing immune complexes, binds Fc receptors and activates the complement system via C1q.The aims of this thesis were to investigate the complement activation properties of CRP; to elucidate if anti-CRP antibodies occur in SLE and, if so, whether anti-CRP antibody levels correlate with disease activity in SLE; to test the hypothesis that autoantibodies to pro-inflammatory cytokines prevent rise of CRP; and to survey if autoantibodies to certain nuclear antigens or to CRP correlate with cytokine-inducing properties of ICs from SLE sera.We have demonstrated that CRP bound to phosphorylcholine is a powerful activator of the classical complement pathway already in the CRP concentration range 4 to 10 mg/L, but with a marked inhibition at CRP levels above 150 mg/L. Autoantibodies to the monomeric form of CRP were found in approximately 40 percent of SLE patients and in a few sera from patients with primary Sjögren’s syndrome, but not in rheumatoid arthritis or in inflammatory bowel disease. The anti-CRP antibody levels showed significant correlations to several laboratory and clinical measurements, and anti-CRP positivity was associated with renal involvement in SLE. Native CRP levels were not correlated with anti-CRP or anti-cytokine antibody levels. Hence, the presence of antibodies to monomeric CRP or to CRP-inducing cytokines is an unlikely explanation to the relative failure of CRP response in patients with active lupus. However, antibodies to TNFα were found in subnormal levels at disease flares, whereas antibodies to TGFβ were found in supranormal levels as compared to healthy subjects. In contrast to antibodies against CRP and DNA, anti-SSA and anti-SSB antibodies may regulate the inflammatory process in SLE by enhancing IC formation and subsequent production of cytokines such as IL-6, IL-10 and IL-12p40. Hypothetically, anti-CRP autoantibodies may be of pathogenic importance, for instance by binding to monomeric CRP on cell and tissue surfaces and thereby increasing the risk of extrahepatic deposition of apoptotic material and in situ formation of ICs.
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| 4. |
- Sjöwall, Christopher, et al.
(författare)
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Serum levels of autoantibodies against C-reactive protein correlate with renal disease activity and response to therapy in lupus nephritis
- 2009
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Ingår i: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 11:6, s. R188-
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Serum levels of C-reactive protein (CRP) seldom reflect disease activity in systemic lupus erythematosus (SLE). We have previously shown that autoantibodies against neo-epitopes of CRP often occur in SLE, but that this does not explain the modest CRP response seen in flares. However, we have repeatedly found that anti-CRP levels parallel lupus disease activity, with highest levels in patients with renal involvement; thus, we aimed to study anti-CRP in a material of well-characterized lupus nephritis patients. Methods Thirty-eight patients with lupus nephritis were included. Treatment with corticosteroids combined with cyclophosphamide, mycophenolate mofetil or rituximab was started after baseline kidney biopsy. A second biopsy was taken after ≥ 6 months. Serum creatinine, cystatin C, complement, anti-dsDNA, anti-CRP and urinalysis were done on both occasions. Biopsies were evaluated regarding World Health Organisation (WHO) class and indices of activity and chronicity. Renal disease activity was estimated using the British Isles Lupus Assessment Group (BILAG) index. Results At baseline, 34/38 patients had renal BILAG-A; 4/38 had BILAG-B. Baseline biopsies showed WHO class III (n = 8), IV (n = 19), III to IV/V (n = 3) or V (n = 8) nephritis. Seventeen out of 38 patients were anti-CRP-positive at baseline, and six at follow-up. Overall, anti-CRP levels had dropped at follow-up (P < 0.0001) and anti-CRP levels correlated with renal BILAG (r = 0.29, P = 0.012). A positive anti-CRP test at baseline was superior to anti-dsDNA and C1q in predicting poor response to therapy as judged by renal BILAG. Baseline anti-CRP levels correlated with renal biopsy activity (r = 0.33, P = 0.045), but not with chronicity index. Anti-CRP levels were positively correlated with anti-dsDNA (fluorescence-enhanced immunoassay: r = 0.63, P = 0.0003; Crithidia luciliae immunofluorescence microscopy test: r = 0.44, P < 0.0001), and inversely with C3 (r = 0.35, P = 0.007) and C4 (r = 0.29, P = 0.02), but not with C1q (r = 0.14, P = 0.24). No associations with urinary components, creatinine, cystatin C or the glomerular filtration rate were found. Conclusions In the present study, we demonstrate a statistically significant correlation between anti-CRP levels and histopathological activity in lupus nephritis, whereas a baseline positive anti-CRP test predicted poor response to therapy. Our data also confirm previous findings of associations between anti-CRP and disease activity. This indicates that anti-CRP could be helpful to assess disease activity and response to therapy in SLE nephritis, and highlights the hypothesis of a pathogenetic role for anti-CRP antibodies in lupus nephritis.
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| 5. |
- Skoglund, Caroline, 1981-, et al.
(författare)
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C-reactive protein and C1q regulate platelet adhesion and activation on adsorbed immunoglobulin G and albumin.
- 2008
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Ingår i: Immunology and cell biology. - : Wiley. - 0818-9641 .- 1440-1711. ; 86:5, s. 466-74
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Tidskriftsartikel (refereegranskat)abstract
- Blood platelets and C-reactive protein (CRP) are both used clinically as markers of ongoing inflammation, and both participate actively in inflammatory responses, although the biological effects are still incompletely understood. Rapidly adhering platelets express receptors for complement factor 1q (C1q) and the Fc part of immunoglobulin G (IgG), and CRP is known to activate/regulate complement via C1q binding, and to ligate FcgammaRs. In the present study, we used normal human IgG pre-adsorbed to a well-characterized methylated surface as a model solid-phase immune complex when investigating the effects of CRP and C1q on platelet adhesion and activation. Protein adsorption was characterized using ellipsometry and polyclonal antibodies, and human serum albumin (HSA) and non-coated surfaces were used as reference surfaces. Platelet adhesion to IgG and HSA was inhibited by both C1q and CRP. Furthermore, CRP (moderately) and C1q (markedly) decreased the spreading of adhering platelets. The combination of C1q and CRP was slightly more potent in reducing cell adhesion to IgG, and also impaired the adhesion to HSA and non-coated surfaces. Platelet production of thromboxane B2 (TXB(2)) was also reduced by C1q both in the presence and absence of CRP, whereas CRP alone had no effect on TXB(2) production. We conclude that CRP and C1q regulate the behaviour of platelets, and that this may be an important immunoregulatory mechanism during inflammatory conditions.
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