| 1. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 2. |
- Andersson, Sofia E M, 1979, et al.
(författare)
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Collagen epitope expression on B cells is sufficient to confer tolerance to collagen-induced arthritis
- 2016
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Ingår i: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6362. ; 18
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Tidskriftsartikel (refereegranskat)abstract
- Background: The mechanisms underlying tolerance induction and maintenance in autoimmune arthritis remain elusive. In a mouse model of rheumatoid arthritis, collagen type II (CII)-induced arthritis, we explore the contribution of B cells to antigen-specific tolerance. Methods: To generate expression of the CII-peptide specifically on B-cell major histocompatibility complex type II, lentiviral-based gene therapy including a B-cell-specific Igk promoter was used. Results: Presentation of the CII-peptide on B cells significantly reduced the frequency and severity of arthritis as well as the serum levels of CII -specific IgG antibodies. Further, both frequency and suppressive function of regulatory T cells were increased in tolerized mice. Adoptive transfer of regulatory T cells from tolerized mice to naive mice ameliorated the development of CII-induced arthritis. Conclusion: Our data suggest that endogenous presentation of the CII-peptide on B cells is one of the key contributors to arthritis tolerance induction and maintenance.
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| 3. |
- Camponeschi, Alessandro, et al.
(författare)
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Dissecting Integrin Expression and Function on Memory B Cells in Mice and Humans in Autoimmunity.
- 2019
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Ingår i: Frontiers in immunology. - : Frontiers Media SA. - 1664-3224. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Immunological memory ensures life-long protection against previously encountered pathogens, and in mice and humans the spleen is an important reservoir for long-lived memory B cells (MBCs). It is well-established that integrins play several crucial roles in lymphocyte survival and trafficking, but their involvement in the retention of MBCs in secondary lymphoid organs, and differences between B cell subsets in their adhesion capacity to ICAM-1 and/or VCAM-1 have not yet been confirmed. Here, we use an autoimmune mouse model, where MBCs are abundant, to show that the highest levels of LFA-1 and VLA-4 amongst B cells are found on MBCs. In vivo blockade of VLA-4 alone or in combination with LFA-1, but not LFA-1 alone, causes a release of MBCs from the spleen into the blood stream. In humans, we find that in peripheral blood, spleens, and tonsils from healthy donors the highest expression levels of the integrins LFA-1 and VLA-4 are also found on MBCs. Consistent with this, we found MBCs to have a higher capacity to adhere to ICAM-1 and VCAM-1 than naïve B cells. In patients with the autoimmune disease rheumatoid arthritis, it is the MBCs that have the highest levels of LFA-1 and VLA-4; moreover, compared with healthy donors, naïve B and MBCs of patients receiving anti-TNF medication have enhanced levels of the active form of LFA-1. Commensurate levels of the active αL subunit can be induced on B cells from healthy donors by exposure to the integrin ligands. Thus, our findings establish the selective use of the integrins LFA-1 and VLA-4 in the localization and adhesion of MBCs in both mice and humans.
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| 4. |
- Camponeschi, Alessandro, et al.
(författare)
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Human CD38 regulates B cell antigen receptor dynamic organization in normal and malignant B cells.
- 2022
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Ingår i: The Journal of experimental medicine. - : Rockefeller University Press. - 1540-9538 .- 0022-1007. ; 219:9
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Tidskriftsartikel (refereegranskat)abstract
- CD38 is a multifunctional protein expressed on the surface of B cells in healthy individuals but also in B cell malignancies. Previous studies have suggested a connection between CD38 and components of the IgM class B cell antigen receptor (IgM-BCR) and its coreceptor complex. Here, we provide evidence that CD38 is closely associated with CD19 in resting B cells and with the IgM-BCR upon engagement. We show that targeting CD38 with an antibody, or removing this molecule with CRISPR/Cas9, inhibits the association of CD19 with the IgM-BCR, impairing BCR signaling in normal and malignant B cells. Together, our data suggest that CD38 is a new member of the BCR coreceptor complex, where it exerts a modulatory effect on B cell activation upon antigen recognition by regulating CD19. Our study also reveals a new mechanism where α-CD38 antibodies could be a valuable option in therapeutic approaches to B cell malignancies driven by aberrant BCR signaling.
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| 5. |
- Gjertsson, Inger, 1962, et al.
(författare)
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A close-up on the expanding landscape of CD21-/low B cells in humans
- 2022
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Ingår i: Clinical and Experimental Immunology. - : Oxford University Press. - 0009-9104 .- 1365-2249. ; 210:3, s. 217-229
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Forskningsöversikt (refereegranskat)abstract
- Memory B cells (MBCs) are an essential part of our immunological memory. They respond fast upon re-encountering pathogens and can differentiate into plasma cells that secrete protective antibodies. The focus of this review is on MBCs that lack, or express low levels of, CD21, hereafter referred to as CD21-/low. These cells are expanded in peripheral blood with age and during chronic inflammatory conditions such as viral infections, malaria, common variable immunodeficiency, and autoimmune diseases. CD21-/low MBCs have gained significant attention; they produce disease-specific antibodies/autoantibodies and associate with key disease manifestations in some conditions. These cells can be divided into subsets based on classical B-cell and other markers, e.g. CD11c, FcRL4, and Tbet which, over the years, have become hallmarks to identify these cells. This has resulted in different names including age-associated, autoimmune-associated, atypical, tissue-like, tissue-resident, tissue-restricted, exhausted, or simply CD21-/low B cells. It is however unclear whether the expanded 'CD21-/low' cells in one condition are equivalent to those in another, whether they express an identical gene signature and whether they have a similar function. Here, we will discuss these issues with the goal to understand whether the CD21-/low B cells are comparable in different conditions.
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| 6. |
- McGrath, Sarah, et al.
(författare)
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Correlation of Professional Antigen-Presenting Tbet+CD11c+ B Cells With Bone Destruction in Untreated Rheumatoid Arthritis
- 2024
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Ingår i: Arthritis & Rheumatology. - : John Wiley & Sons. - 2326-5191 .- 2326-5205.
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Subsets of CD21−/low memory B cells (MBCs), including double-negative (DN, CD27−IgD−) and Tbet+CD11c+ cells, are expanded in chronic inflammatory diseases. In rheumatoid arthritis (RA), CD21−/low MBCs correlate with joint destruction. However, whether this is due to the Tbet+CD11c+ subset, its function and pathogenic contribution to RA are unknown. This study aims to investigate the association between CD21−/lowTbet+CD11c+ MBCs and joint destruction as well as other clinical parameters and to elucidate their functional properties in patients with untreated RA (uRA). Methods: Clinical observations were combined with flow cytometry (n = 36) and single-cell RNA sequencing (scRNA-seq) and V(D)J sequencing (n = 4) of peripheral blood (PB) MBCs from patients with uRA. The transcriptome of circulating Tbet+CD11c+ MBCs was compared with scRNA-seq data of synovial B cells. In vitro coculture of Tbet+CD11c+ B cells with T cells was used to assess costimulatory capacity. Results: CD21−/lowTbet+CD11c+ MBCs in PB correlated with bone destruction but no other clinical parameters analyzed. The Tbet+CD11c+ MBCs have undergone clonal expansion and express somatically mutated V genes. Gene expression analysis of these cells identified a unique signature of more than 150 up-regulated genes associated with antigen presentation functions, including B cell receptor activation and clathrin-mediated antigen internalization; regulation of actin filaments, endosomes, and lysosomes; antigen processing, loading, presentation, and costimulation; a transcriptome mirrored in their synovial tissue counterparts. In vitro, Tbet+CD11c+ B cells induced retinoic acid receptor–related orphan nuclear receptor γT expression in CD4+ T cells, thereby polarizing to Th17 cells, a T cell subset critical for osteoclastogenesis and associated with bone destruction. Conclusion: This study suggests that Tbet+CD11c+ MBCs contribute to the pathogenesis of RA by promoting bone destruction through antigen presentation, T cell activation, and Th17 polarization. (Figure presented.).
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| 7. |
- Thorarinsdottir, Katrin
(författare)
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B cell subpopulations in the pathogenesis of rheumatoid arthritis
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- B cell depleting therapy has proven to be an effective treatment in rheumatoid arthritis (RA), a disease characterized by the presence of autoantibodies against citrullinated proteins (ACPA) and the Fc portion of IgG (rheumatoid factor, RF). This demonstrates the vital role B cells play in the disease. The aim of this thesis was to explore the role of B cell subpopulations in the pathogenesis of RA. Our interest in a specific B cell population arose with the discovery of murine autoreactive B cells, CD21-/low cells, which expressed low surface levels or lacked the complement receptor 2 (CD21). CD21 helps activate B cells, as it is a part of the B cell co-receptor complex. In Studies I-III we analyzed B cell populations in human peripheral blood with the help of flow cytometry utilizing multiple cell markers. In Studies II-III, clinical as well as radiographic data was collected from RA patients. In Study I we established that CD21-/low B cells are found in human peripheral blood and discovered that in healthy donors (HDs) this B cell population is mainly composed of memory B cells (MBCs) based on their phenotype and response to combined stimuli. In Study II we compared the B cell populations in peripheral blood of patients with established RA and HDs. We saw a higher proportion of a CD21-/low subpopulation, i.e. CD21-/low CD27-IgD- (double negative, DN) in patients with autoantibodies (ACPA/RF) compared to HDs. Additionally, the frequency of CD21- /low DN cells was higher in ACPA/RF positive patients with more joint destruction compared to those with less, and the CD21-/low DN population correlated positively with the level of destruction. The CD21-/low DN population was highly enriched in the inflamed joints of RA patients and a third of the cells expressed RANKL, which stimulates osteoclastogenesis. In Study III, we compared the B cell populations in peripheral blood in newly diagnosed untreated RA patients and HDs. We observed that the proportion of CD21+CD27+ MBCs correlated positively with RF and ACPA titers. In addition, the frequency of CD21+ DN cells and CD21-/low DN MBCs correlated positively with tender joint count and joint narrowing score respectively. In conclusion, it seems that different MBCs have different roles in RA where CD21+ CD27+ MBCs appear to drive the autoantibody response, the CD21+DN MBCs the joint inflammation and the CD21-/low DN MBCs the joint damage.
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| 8. |
- Thorarinsdottir, Katrin, et al.
(författare)
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Cartilage destruction in early rheumatoid arthritis patients correlates with CD21−/low double-negative B cells
- 2024
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Ingår i: Arthritis Research and Therapy. - 1478-6354 .- 1478-6362. ; 26:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Involvement of B cells in the pathogenesis of rheumatoid arthritis (RA) is supported by the presence of disease-specific autoantibodies and the efficacy of treatment directed against B cells. B cells that express low levels of or lack the B cell receptor (BCR) co-receptor CD21, CD21−/low B cells, have been linked to autoimmune diseases, including RA. In this study, we characterized the CD21+ and CD21−/low B cell subsets in newly diagnosed, early RA (eRA) patients and investigated whether any of the B cell subsets were associated with autoantibody status, disease activity and/or joint destruction. Methods: Seventy-six eRA patients and 28 age- and sex-matched healthy donors were recruited. Multiple clinical parameters were assessed, including disease activity and radiographic joint destruction. B cell subsets were analysed in peripheral blood (PB) and synovial fluid (SF) using flow cytometry. Results: Compared to healthy donors, the eRA patients displayed an elevated frequency of naïve CD21+ B cells in PB. Amongst memory B cells, eRA patients had lower frequencies of the CD21+CD27+ subsets and CD21−/low CD27+IgD+ subset. The only B cell subset found to associate with clinical factors was the CD21−/low double-negative (DN, CD27−IgD−) cell population, linked with the joint space narrowing score, i.e. cartilage destruction. Moreover, in SF from patients with established RA, the CD21−/low DN B cells were expanded and these cells expressed receptor activator of the nuclear factor κB ligand (RANKL). Conclusions: Cartilage destruction in eRA patients was associated with an expanded proportion of CD21−/low DN B cells in PB. The subset was also expanded in SF from established RA patients and expressed RANKL. Taken together, our results suggest a role for CD21−/low DN in RA pathogenesis.
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| 9. |
- Thorarinsdottir, Katrin, et al.
(författare)
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CD21(-/low) B cells associate with joint damage in rheumatoid arthritis patients
- 2019
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 90:2
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Tidskriftsartikel (refereegranskat)abstract
- Depletion of B cells is beneficial in rheumatoid arthritis (RA) patients with autoantibodies to citrullinated proteins (ACPA) and/or the Fc portion of immunoglobulins (rheumatoid factor [RF]), suggesting a role for B cells in disease pathogenesis. To date, however, the identity of specifically pathogenic B cell subsets has not been discovered. One candidate population is identified by the low expression or absence of complement receptor 2 (CD21(-/low) B cells). In this study, we sought to determine whether there was any correlation between CD21(-/low) B cells and clinical outcome in patients with established RA, either ACPA(+)/RF+ (n = 27) or ACPA(-)/RF- (n = 10). Healthy donors (n = 17) were included as controls. The proportion of the CD21(-/low) CD27(-)IgD(-) memory B cell subset in peripheral blood (PB) was significantly increased in ACPA(+)/RF+ RA patients compared with healthy donors, and the frequency of this subset correlated with joint destruction (r = 0.57, P < 0.04). The levels of the chemokines CXCL-9 and CXCL-10 were higher in synovial fluid than in plasma, and PB CD21(-/low) cells expressed the receptor, CXCR3. In synovial fluid, most of the B cells were CD21(-/low), approximately 40% of that population was CD27(-)IgD(-), and a third of those expressed the pro-osteoclastogenic factor receptor activator of the nuclear factor kappa B ligand (RANKL). This subset also secreted RANKL, in addition to other factors such as IL-6, even in the absence of stimulation. We interpret these data as reason to propose the hypothesis that the CD27(-)IgD(-) subset of CD21(-/low) B cells may mediate joint destruction in patients with ACPA(+)/RF+ RA.
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| 10. |
- Thorarinsdottir, Katrin, et al.
(författare)
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CD21-/low B cells in human blood are memory cells
- 2016
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Ingår i: Clinical and Experimental Immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 185:2, s. 252-262
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Tidskriftsartikel (refereegranskat)abstract
- The complement receptor 2 (CR2, CD21) is part of a complex (CD21/CD19/CD81) acting as a co-receptor to the B-cell receptor (BCR). Simultaneous triggering of the BCR and CD21 lowers the threshold for B-cell activation. Although CD21 is important, B cells that express low amounts or lack surface CD21 (CD21-/low) are increased in conditions with chronic inflammation, e.g. autoimmune diseases. However, little is known about the CD21-/low B-cell subset in peripheral blood from healthy donors. Here, we show that CD21-/low cells represent around 5% of B cells in peripheral blood from adults but are barely detectable in cord blood, after excluding transitional B cells. The CD21-/low subset can be divided into CD38-24+ and CD38-24low cells, where most of the CD38-24+ are CD27+IgM+IgD+ and the CD38-24low are switched CD27-. Expression levels of additional markers, e.g. CD95 and CD62L, are similar to those on classical memory B cells. In contrast to naïve cells, the majority of CD21-/low cells lack expression of the ABCB1 transporter. Stimulation with a combination of BCR, toll-like receptor (TLR) 7/8 and IL-2 induces proliferation and differentiation of the CD21-/low B-cells comparable to CD21+CD27+ memory B cells. The response excluding BCR agonist is not on par with that of classical memory B cells, though clearly above that of naïve B cells. This is ascribed to a weaker response by the CD38-24low subset, implying that some memory B cells require not only TLR but also BCR triggering. We conclude that the CD21-/low B cells in healthy donors are memory B cells.
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