| 1. |
- Lara, Sandra, et al.
(författare)
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Exploring complement-dependent cytotoxicity by rituximab isotypes in 2D and 3D-cultured B-cell lymphoma
- 2022
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Ingår i: BMC Cancer. - : BioMed Central. - 1471-2407. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The therapeutic IgG1 anti-CD20 antibody, rituximab (RTX), has greatly improved prognosis of many B-cell malignancies. Despite its success, resistance has been reported and detailed knowledge of RTX mechanisms are lacking. Complement-dependent cytotoxicity (CDC) is one important mode of action of RTX. The aim of this study was to systematically evaluate factors influencing complement-mediated tumor cell killing by RTX. Methods Different RTX isotypes, IgG1, IgG3, IgA1 and IgA2 were evaluated and administered on four human CD20(+) B-cell lymphoma cell lines, displaying diverse expression of CD20 and complement-regulatory protein CD59. Complement activation was assessed on lymphoma cells grown in 2 and 3-dimensional (3D) culture systems by trypan blue exclusion. CDC in 3D spheroids was additionally analyzed by Annexin V and propidium iodide staining by flow cytometry, and confocal imaging. Anti-CD59 antibody was used to evaluate influence of CD59 in RTX-mediated CDC responses. Statistical differences were determined by one-way ANOVA and Tukey post hoc test. Results We found that 3 out of 4 lymphomas were sensitive to RTX-mediated CDC when cultured in 2D, while 2 out of 4 when grown in 3D. RTX-IgG3 had the greatest CDC potential, followed by clinical standard RTX-IgG1 and RTX-IgA2, whereas RTX-IgA1 displayed no complement activation. Although the pattern of different RTX isotypes to induce CDC were similar in the sensitive lymphomas, the degree of cell killing differed. A greater CDC activity was seen in lymphoma cells with a higher CD20/CD59 expression ratio. These lymphomas were also sensitive to RTX when grown in 3D spheroids, although the CDC activity was substantially reduced compared to 2D cultures. Analysis of RTX-treated spheroids demonstrated apoptosis and necrosis essentially in the outer cell-layers. Neutralization of CD59 overcame resistance to RTX-mediated CDC in 2D-cultured lymphoma cells, but not in spheroids. Conclusions The results demonstrate that CDC outcome in CD20(+) B-cell lymphoma is synergistically influenced by choice of RTX isotype, antigen density, tumor structure, and degree of CD59 expression. Assessment of tumor signatures, such as CD20/CD59 ratio, can be advantageous to predict CDC efficiency of RTX in vivo and may help to develop rational mAbs to raise response rates in patients.
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| 2. |
- Lara, Sandra, et al.
(författare)
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Importance of antibody isotypes in antitumor immunity by monocytes and complement using human-immune tumor models
- 2021
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Ingår i: European Journal of Immunology. - : John Wiley & Sons. - 0014-2980 .- 1521-4141. ; 51:5, s. 1218-1233
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Tidskriftsartikel (refereegranskat)abstract
- Monoclonal antibodies (mAbs) have revolutionized clinical medicine, especially in the field of cancer immunotherapy. The challenge now is to improve the response rates, as immunotherapy still fails for many patients. Strategies to enhance tumor cell death is a fundamental aim, but relevant model systems for human tumor immunology are lacking. Herein, we have developed a preclinical human immune - three-dimensional (3D) tumor model (spheroids) to map the efficiency of tumor-specific isotypes for improved tumor cell killing. Different anti-CD20 Rituximab (RTX) isotypes alone or in combination, were evaluated for mediating complement-dependent cytotoxicity and antibody-dependent phagocytosis by human monocytic cells in 3D spheroids, in parallel with monolayer cultures, of human CD20(+) B-cell lymphomas. We demonstrate that the IgG3 variant of RTX has the greatest tumoricidal effect over other isotypes, and when combined with apoptosis-inducing RTX-IgG2 isotype the therapeutic effect can be substantially enhanced. The results show further that the treatment outcome by RTX isotypes is influenced by tumor morphology and expression of the complement inhibitor CD59. Hence, the human immune-3D tumor model is a clinical relevant and attractive ex vivo system to predict mAbs for best efficacy in cancer immunotherapy.
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| 3. |
- Lara, Sandra, et al.
(författare)
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The Human Monocyte : A Circulating Sensor of Infection and a Potent and Rapid Inducer of Inflammation
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:7
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Tidskriftsartikel (refereegranskat)abstract
- Monocytes were previously thought to be the precursors of all tissue macrophages but have recently been found to represent a unique population of cells, distinct from the majority of tissue macrophages. Monocytes and intestinal macrophages seem now to be the only monocyte/macrophage populations that originate primarily from adult bone marrow. To obtain a better view of the biological function of monocytes and how they differ from tissue macrophages, we have performed a quantitative analysis of its transcriptome in vivo and after in vitro stimulation with E. coli LPS. The monocytes rapidly responded to LPS by producing extremely high amounts of mRNA for the classical inflammatory cytokines, IL-1α, IL-1β, IL-6 and TNF-α, but almost undetectable amounts of other cytokines. IL-6 was upregulated 58,000 times, from almost undetectable levels at baseline to become one of the major transcripts already after a few hours of cultivation. The cells also showed very strong upregulation of a number of chemokines, primarily IL-8, Ccl2, Ccl3, Ccl3L3, Ccl20, Cxcl2, Cxcl3 and Cxcl4. IL-8 became the most highly expressed transcript in the monocytes already after four hours of in vitro culture in the presence of LPS. A high baseline level of MHC class II chains and marked upregulation of super oxide dismutase (SOD2), complement factor B, complement factor C3 and coagulation factor 3 (F3; tissue factor) at four hours of in vitro culture were also observed. This indicates a rapid protective response to high production of oxygen radicals, to increase complement activation and possibly also be an inducer of local coagulation. Overall, these findings give strong support for monocytes acting primarily as potent mobile sensors of infection and rapid activators of a strong inflammatory response.
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| 4. |
- Paivandy, Aida, et al.
(författare)
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Quantitative In-Depth Transcriptome Analysis Implicates Peritoneal Macrophages as Important Players in the Complement and Coagulation Systems
- 2022
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 23:3
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Tidskriftsartikel (refereegranskat)abstract
- To obtain a more detailed picture of macrophage (M phi) biology, in the current study, we analyzed the transcriptome of mouse peritoneal M phi s by RNA-seq and PCR-based transcriptomics. The results show that peritoneal M phi s, based on mRNA content, under non-inflammatory conditions produce large amounts of a number of antimicrobial proteins such as lysozyme and several complement components. They were also found to be potent producers of several chemokines, including platelet factor 4 (PF4), Ccl6, Ccl9, Cxcl13, and Ccl24, and to express high levels of both TGF-beta 1 and TGF-beta 2. The liver is considered to be the main producer of most complement and coagulation components. However, we can now show that M phi s are also important sources of such compounds including C1qA, C1qB, C1qC, properdin, C4a, factor H, ficolin, and coagulation factor FV. In addition, FX, FVII, and complement factor B were expressed by the M phi s, altogether indicating that M phi s are important local players in both the complement and coagulation systems. For comparison, we analyzed human peripheral blood monocytes. We show that the human monocytes shared many characteristics with the mouse peritoneal M phi s but that there were also many major differences. Similar to the mouse peritoneal M phi s, the most highly expressed transcript in the monocytes was lysozyme, and high levels of both properdin and ficolin were observed. However, with regard to connective tissue components, such as fibronectin, lubricin, syndecan 3, and extracellular matrix protein 1, which were highly expressed by the peritoneal M phi s, the monocytes almost totally lacked transcripts. In contrast, monocytes expressed high levels of MHC Class II, whereas the peritoneal M phi s showed very low levels of these antigen-presenting molecules. Altogether, the present study provides a novel view of the phenotype of the major M phi subpopulation in the mouse peritoneum and the large peritoneal M phi s and places the transcriptome profile of the peritoneal M phi s in a broader context, including a comparison of the peritoneal M phi transcriptome with that of human peripheral blood monocytes and the liver.
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| 5. |
- Akula, Srinivas
(författare)
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The mast cell transcriptome and the evolution of granule proteins and Fc receptors
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Protection against disease-causing pathogens, known as immunity, involves numerous cells organs, tissues and their products. To able to understand the biology of immune cells (hematopoietic cells) and their role in an immune system, we have used several different methods, including transcriptome analyses, bioinformatics, production of recombinant proteins and analyses of some of them, focusing on the granule proteases by substrate phage display.Hematopoietic cells express surface receptors interacting with the constant region of immunoglobulins (Igs) known as Fc receptors (FcRs). These receptors play major roles in the immune system, including enhancing phagocytosis, activating antibody dependent cellular cytotoxicity and cell activation. A detailed bioinformatics analysis of FcRs reveals that the poly-Ig receptors (PIGR), FcR-like molecules and common signalling γ chain all appeared very early with the appearance of the bony fishes, and thereby represent the first major evolutionary step in FcR evolution. The FcμR, FcαμR, FcγR and FcεR receptors most likely appeared in reptiles or early mammals, representing the second major step in FcR evolution.Cells of several of the hematopoietic cell lineages contain large numbers of cytoplasmic granules, and serine proteases constitute the major protein content of these granules. In mammals, these proteases are encoded from four different loci: the chymase, the met-ase, the granzyme (A/K) and the mast cell tryptase loci. The granzyme (A/K) locus was the first to appear and came with the cartilaginous fishes. This locus is also the most conserved of the three. The second most conserved locus is the met-ase locus, which is found in bony fishes. The chymase locus appeared relatively late, and we find the first traces in frogs, indicating it appeared in early tetrapods.To study the early events in the diversification of these hematopoietic serine proteases we have analyzed key characteristics of a protease expressed by an NK-like cell in the channel catfish, catfish granzyme–like I. We have used phage display and further validated the results using a panel of recombinant substrates. This protease showed a strict preference for Met at the P1 (cleavage) position, which indicates met-ase specificity. From the screening of potential in vivo substrates, we found an interesting potential target caspase 6, which indicates that caspase-dependent apoptosis mechanisms have been conserved from fishes to mammals.A larger quantitative transcriptome analysis of purified mouse peritoneal mast cells, cultured mast cells (BMMCs), and mast cells isolated from mouse ear and lung tissue identified the major tissue specific transcripts in these mast cells as the granule proteases. Mast cell specific receptors and processing enzymes were expressed at approximately 2 orders of magnitude lower levels. The levels of a few proteases were quite different at various anatomical sites between in vivo and cultured BMMCs. These studies have given us a new insights into mast cells in different tissues, as well as key evolutionary aspects concerning the origins of a number of granule proteases and FcRs.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Andrén, Maria, 1976-
(författare)
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The Role of Fc Gamma Receptors in Experimental Arthritis
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Induction of collagen-induced arthritis (CIA), an animal model for human rheumatoid arthritis, is dependent on anti-collagen type II (CII) antibodies. The effector mechanism by which autoantibodies contribute to inflammatory reactions in autoimmune diseases is not well understood. In this thesis I have studied the effector pathways used by IgG anti-CII antibodies to initiate arthritis, namely the IgG Fc receptors (FcγRs) and the complement system. We have found that FcγRIII is crucial for development of CIA, as CII-immunized mice lacking this receptor do not develop arthritis and IgG1 and IgG2b anti-CII antibodies require FcγRIII to trigger arthritis when transferred to naïve mice. The antibody-mediated arthritis was further enhanced in mice deficient in the inhibitory FcγRIIB, indicating that FcγRIIB regulates the activation of FcγRIII. Furthermore, we demonstrate that FcγRIII exist as three distinct haplotypes in mice, FcγRIII:H, FcγRIII:V and FcγRIII:T. Mice expressing the FcγRIII:H haplotype are more susceptible to CIA than mice expressing the FcγRIII:V haplotype, indicating that certain FcγRIII haplotype predisposes for CIA. We also show that the most likely FcγRIII-expressing effector cell in CIA is the macrophage, since FcγRIII-expressing macrophages exclusively can induce arthritis in FcγRIII-deficient mice challenged for CIA.The complement system was also investigated in development of CIA. We found that this effector pathway is also necessary for onset of arthritis, as CIA was inhibited by treatment with anti-complement factor 5 (C5) antibodies. C5-deficient mice could neither develop CIA unless provided with C5-containing sera. Taken together, the work presented in this thesis indicates that FcγRs and the complement system are crucial for the induction of experimental arthritis. These findings are important for understanding the mechanisms behind rheumatoid arthritis and blocking of these effector pathways may in the future be used as treatment of rheumatoid arthritis.
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| 10. |
- Carnrot, Cecilia, et al.
(författare)
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Marginal zone B cells are naturally reactive to collagen type II and are involved in the initiation of the immune response in collagen-induced arthritis
- 2011
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Ingår i: Cellular & Molecular Immunology. - : Springer Science and Business Media LLC. - 1672-7681 .- 2042-0226. ; 8:4, s. 296-304
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies against type II collagen (CII) are essential for development of collagen-induced arthritis (CIA), but how and where the B-cell response to CII is initiated is not fully known. We show here that naive DBA/1 mice display naturally reactive IgM and IgG anti-CII producing B cells prior to immunization. The CII-reactive B cells were observed in the spleen and recognized as marginal zone (MZ) B cells. After CII immunization, CII-specific B cells expanded rapidly in the spleen, in contrast to the lymph nodes, with the initial response derived from MZ B cells and later by follicular (FO) B cells. This was evident despite that the MZ B cells were subject to stringent tolerance mechanisms by having a greater Fc gamma receptor IIb expression than the FO B cells. Further, the MZ B cells migrated to the FO areas upon immunization, possibly providing antigen and activating FO T cells and subsequently FO B cells. Thus, around CIA onset increased numbers of IgG anti-CII producing FO B cells was seen in the spleen, which was dominated by IgG2a- and IgG2b-positive cells. These data demonstrate that CII-reactive MZ B cells are present before and expand after CII immunization, suggesting an initiating role of MZ B cells in the development of CIA.
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| 11. |
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| 12. |
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| 13. |
- Gjertsson, Inger, 1962, et al.
(författare)
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The impact of Fcgamma receptors on Staphylococcus aureus infection.
- 2002
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Ingår i: Microbial pathogenesis. - 0882-4010. ; 33:4, s. 145-52
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Tidskriftsartikel (refereegranskat)abstract
- Antibodies are known to be an important defence mechanism of the host's immune response towards certain invading microorganisms. Earlier findings have shown that antibodies directed to certain surface molecules on Staphylococcus aureus are of importance in systemic defence against infections. To further investigate the contribution of humoral immunity during intravenously induced S. aureus septicemia and arthritis we have studied the impact of IgG Fc receptors (FcgammaRs). DBA/1 mice deficient for the common gamma-chain (lacking the activating receptors, FcgammaRI, FcgammaRIII and FcepsilonRI) or the inhibitory FcgammaRII and corresponding littermate controls were used. We found that absence of FcgammaRII expression significantly increased the survival rate following severe infection with S. aureus. The FcgammaRII-/- infected mice showed increased levels of IL-10, elevated serum levels of IgG antibodies against clumping factor A and enhanced phagocytic capacity of granulocytes and monocytes, as compared to control mice. Deficiency in the common gamma-chain (FcgammaRI, III and FcepsilonRI) did not influence the arthritogenicity nor the mortality of systemic S. aureus infection. We conclude that expression of Fcgamma receptor II is of importance during S. aureus infection.
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| 14. |
- Hjelm, Fredrik, 1978-
(författare)
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Early Immunostimulatory Effects of IgE- and IgG Antibodies
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antibodies have the ability to influence their own production in a process called antibody feedback regulation. Depending on the type of antigen and the subclass of the antibody, the outcome of feedback regulation can be complete suppression or several hundred-fold enhancement of the antibody response.IgE and IgG3 enhance responses to soluble protein antigens. Previous results suggest that IgG3-mediated enhancement of antibody responses is dependent on complement and not Fc receptors for IgG. However, the Fc receptor-deficient animals used did not completely lack the IgG3-binding FcγRI. We re-examined the role of this receptor in a new mouse strain completely lacking FcγRI and found that IgG3-mediated enhancement was unperturbed, thus confirming a role for complement. To investigate the early responses resulting in IgE-mediated enhancement of antibody responses we used biotinylated antigen and found that mature follicular B cells and to a lesser extent transitional type 2 B cells capture IgE/antigen complexes. Adoptive transfer of CD4+ T cells expressing a transgenic TCR specific for ovalbumin demonstrated that these T cells localize near the B-cell follicle after 6-12 hours and that IgE, in contrast to IgG3, significantly increased specific T cell proliferation. After 3 days the T cells had gone through several rounds of divisions and showed an activated phenotype. Additional cell transfer studies identified CD23+ B cells as the responsible effector cells. These results indicate that the mechanism underlying IgE-mediated enhancement is rapid transport of IgE/antigen complexes by follicular B cells into B-cell follicles, followed by antigen presentation by CD23+ B cells to naïve CD4+ T cells. IgG3, inducing poor T cell responses, is more likely to depend on lowering the threshold for B-cell activation by co-ligating the B-cell receptor with the complement receptor 2/CD19 complex on the surface of the B cell.
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| 15. |
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| 16. |
- Kleinau, Sandra
(författare)
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Impact of Fc receptors and host characteristics on myeloid phagocytic response to rituximab-treated 3D-cultured B-cell lymphoma
- 2023
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Ingår i: IMMUNOTHERAPY ADVANCES. - : Oxford University Press. - 2732-4303. ; 3:1
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Tidskriftsartikel (refereegranskat)abstract
- Antibody-based immunotherapy is successful in treating cancer, but its effectiveness varies among patients. Therefore, understanding myeloid phagocytic responses to therapeutic antibodies is critical. Immunoglobulin Fc receptors and host characteristics were evaluated in phagocytosis of 3D-cultured CD20+ B-cell lymphoma (spheroids) treated with different anti-CD20 rituximab (RTX) monoclonal antibody isotypes. Monocytes from healthy donors of different ages and sexes were isolated, and their Fc receptors for IgG (Fc gamma RI, Fc gamma RIIa, Fc gamma RIIIa) and IgA (Fc alpha RI) were determined, as well as Fc receptor gene polymorphisms. Antibody-dependent phagocytosis was assessed using flow cytometry, confocal imaging, and Fc receptor blocking. RTX isotypes showed varying efficacy in stimulating the phagocytosis of spheroids. RTX-IgG3 proved to be the most efficient, followed by RTX-IgG1. Monocytes infiltrated RTX-treated spheroids at the periphery but migrated also into the core when stimulated with RTX-IgG3. Blocking Fc gamma RI or Fc gamma RIIa, but not Fc gamma RIIIa, with antibodies inhibited RTX-IgG1 and RTX-IgG3-mediated phagocytosis. Monocytes from younger women demonstrated higher Fc gamma RI and Fc gamma RIIa levels compared to older women, while older men displayed increasing Fc gamma RI and Fc gamma RIIIa levels compared to younger men. Monocytes from younger women displayed greater phagocytic activity compared to older women, while older men had better IgG-mediated phagocytosis than younger men. Single Fc receptor levels, or Fc gamma RIIa and Fc gamma RIIIa genetic variants, had a low correlation with phagocytic intensity, likely as a result of multiple engagements of Fcreceptors for IgG-mediated phagocytosis. In conclusion, antibody isotype, Fc receptors, age, and sex influence tumor phagocytosis. This study exposes the relationship between host traits and the efficacy of therapeutic antibodies, providing insights into cancer immunotherapy treatment.
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| 17. |
- Kleinau, Sandra, et al.
(författare)
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Importance of CD23 for collagen-induced arthritis : delayed onset and reduced severity in CD23-deficient mice
- 1999
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Ingår i: Journal of Immunology. - 0022-1767 .- 1550-6606. ; 162:7, s. 4266-4270
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Tidskriftsartikel (refereegranskat)abstract
- Increased expression of the low affinity receptor for IgE, FcepsilonRII/CD23 has been observed in rheumatoid arthritis. In view of this, we have investigated the expression and influence of CD23 in collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis. CD23+ cells were analyzed in lymph nodes of DBA/1 mice immunized with bovine collagen type II (BCII) in CFA or with CFA only. The percentage of CD23+ lymph node cells was increased in both BCII/CFA- and CFA-immunized mice at 1, 3, and 7 wk after immunization compared with unimmunized mice, indicating a role for the adjuvant to trigger general inflammation and CD23 expression. To investigate the functional role of CD23 in CIA, CD23-deficient mice on the DBA/1 genetic background were studied. After immunization with BCII/CFA, these mice developed CIA with delayed onset and reduced severity compared with wild-type mice. These findings suggest that an increased number of CD23+ cells is part of an inflammatory response and that CD23 expression is of pathogenic importance in the arthritic process.
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| 18. |
- Magnusson, Sofia, 1980-, et al.
(författare)
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Amelioration of collagen-induced arthritis by human recombinant soluble FcγRIIb
- 2008
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Ingår i: Clinical Immunology. - : Elsevier BV. - 1521-6616 .- 1521-7035. ; 127:2, s. 225-233
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Tidskriftsartikel (refereegranskat)abstract
- Immune complex (IC) binding to Fc gamma receptors (FcγRs) is central for inflammatory reactions seen in autoimmune diseases. Consequently, a therapeutic agent with a possibility to interfere with binding of pathogenic IC to FcγRs would be valuable in autoimmune disorders such as rheumatoid arthritis (RA). Here we have explored the therapeutic effect of a recombinant solublehuman FcγRIIb (sFcγRIIb) protein in collagen-induced arthritis (CIA). In vitro studies of the sFcγRIIb demonstrated binding to mouse IgG, suggesting that sFcγRIIb can absorb pathogenic IgG anticollagen type II (CII) IC in vivo. Hence, administration of sFcγRIIb significantly reduced CIA severity compared to control treated mice. The sFcγRIIb treated mice had significantly less IgG anti-CII antibodies in serum and lowermRNA levels of inflammatory cytokines compared to controlmice. In conclusion, sFcγRIIb treatment ameliorates CIA by reducing IC-stimulated inflammation and joint swelling. This suggests that recombinant sFcγRIIb may be useful as therapeutic agent in RA.
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| 19. |
- Magnusson, Sofia E, et al.
(författare)
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Dysregulated Fc receptor function in active rheumatoid arthritis
- 2014
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Ingår i: Immunology Letters. - : Elsevier BV. - 0165-2478 .- 1879-0542. ; 162:1 Pt A, s. 200-206
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Tidskriftsartikel (refereegranskat)abstract
- Given the critical role of Fc gamma receptors (FcgammaR) as primary targets for autoantibody-mediated effects an important issue is how the FcgammaR pathway is affected in autoimmune disorders. Here we investigated the FcgammaR function in monocytes from rheumatoid arthritis (RA) patients in relation to immunoglobulin levels and disease activity. Peripheral blood was obtained from 30 RA patients with clinical acute joint synovitis (active RA), 28 RA patients with no clinical signs of acute joint synovitis (non-active RA) and 34 healthy controls. Prior the functional studies the monocytes were characterized of their FcgammaRI (CD64), II (CD32), IIb (CD32b) and III (CD16) expression as well as their cell surface bound IgG. The monocytic FcgammaR function was assessed by binding of human IgG1 and IgG3 immune complexes (IC) and TNF secretion in vitro. IgG anti-citrullinated peptide antibodies (ACPA) were analyzed in the plasma. We found that monocytes from active RA patients had increased levels of FcgammaRI, II and cell surface IgG concurrently with impaired FcgammaR function. This was evident by reduced IgG1-IC binding and decreased TNF secretion in response to IgG3-IC. In contrast, monocytes from non-active RA patients displayed a normal FcgammaR function and had increased FcgammaRIIb expression together with elevated FcgammaRI, II and cell surface IgG. The ACPA levels did not differ in active and non-active RA patients but correlated with the monocytic FcgammaRIII expression in the patients. In conclusion, active RA patients display a dysregulated FcgammaR function that may represent a novel phenotypic and likely pathogenetic marker for active RA. A disease and FcgammaR function controlling effect is suggested by the increased inhibitory FcgammaRIIb in non-active RA.
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| 20. |
- Magnusson, Sofia E., et al.
(författare)
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High synovial expression of the inhibitory Fc gamma RIIb in rheumatoid arthritis
- 2007
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Ingår i: Arthritis Research & Therapy. - : Springer Science and Business Media LLC. - 1478-6362 .- 1478-6354. ; 9:3, s. R51-
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Tidskriftsartikel (refereegranskat)abstract
- Activating Fc gamma receptors (FcγRs) have been identified as having important roles in the inflammatory joint reaction in rheumatoid arthritis (RA) and murine models of arthritis. However, the role of the inhibitory FcγRIIb in the regulation of the synovial inflammation in RA is less known. Here we have investigated synovial tissue from RA patients using a novel monoclonal antibody (GB3) specific for the FcγRIIb isoform. FcγRIIb was abundantly expressed in synovia of RA patients, in sharp contrast to the absence or weak staining of FcγRIIb in synovial biopsies from healthy volunteers. In addition, the expression of FcγRI, FcγRII and FcγRIII was analyzed in synovia obtained from early and late stages of RA. Compared with healthy synovia, which expressed FcγRII, FcγRIII but not FcγRI, all activating FcγRs were expressed and significantly up-regulated in RA, regardless of disease duration. Macrophages were one of the major cell types in the RA synovium expressing FcγRIIb and the activating FcγRs. Anti-inflammatory treatment with glucocorticoids reduced FcγR expression in arthritic joints, particularly that of FcγRI. This study demonstrates for the first time that RA patients do not fail to up-regulate FcγRIIb upon synovial inflammation, but suggests that the balance between expression of the inhibitory FcγRIIb and activating FcγRs may be in favour of the latter throughout the disease course. Anti-inflammatory drugs that target activating FcγRs may represent valuable therapeutics in this disease.
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| 21. |
- Magnusson, Sofia E., et al.
(författare)
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Mast cell chymase contributes to the antibody response and the severity of autoimmune arthritis
- 2009
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 23:3, s. 875-882
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Tidskriftsartikel (refereegranskat)abstract
- Mast cells are implicated in rheumatoid arthritis, but the mechanism by which they contribute to disease progression is not clarified. Here we investigated whether mouse mast cell protease-4 (mMCP-4), a chymase present in the mast cell secretory granule, contributes to experimental arthritis. Two models of arthritis were investigated in mMCP-4(+/+) and mMCP-4(-/-) DBA/1 mice: collagen-induced arthritis (CIA) was induced by immunization with collagen II (CII) in Freund's complete adjuvant, and a passive model of arthritis was induced by administration of anti-CII antibodies. The clinical scores were significantly reduced in the mMCP-4(-/-) animals as compared to mMCP-4(+/+) controls in both arthritis models. In CIA, the number of affected paws was lower in the CII-immunized mMCP-4(-/-) mice, with less cartilage destruction, pannus formation, and mononuclear cell and mast cell influx in the mMCP-4(-/-) joints. Interestingly, the lower clinical scores in the CII-immunized mMCP-4(-/-) mice coincided with lower serum levels of immunoglobulin G anti-CII antibodies. Our findings identify a pathogenic role of mMCP-4 in autoimmune arthritis.
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| 22. |
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| 23. |
- Magnusson, Sofia, 1980-
(författare)
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The Role of Fc gamma Receptors and Mast Cell Chymase in Autoimmune Arthritis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In autoimmune diseases such as rheumatoid arthritis (RA), self-reactive antibodies are present at high levels, which contributes to disease pathogenesis. The antibodies mediate their effect predominantly by binding to Fc gamma receptors (FcγR) on various leukocytes, such as monocytes, macrophages and mast cells, where FcγR ligation leads to cell activation. In this thesis the role of FcγR in RA was investigated. We could, for the first time, demonstrate an increased expression of the inhibitory FcγRIIb in RA synovial tissue, while this receptor as well as FcγRI were almost absent in healthy synovial tissue. The enhanced FcγRI expression in RA synovia was reduced by one intraarticular injection of glucocorticoids, indicating that FcγRI participates in the joint inflammation. Interestingly, RA patients with an ongoing joint inflammation exhibited blood monocytes with immune compromised features, such as decreased FcγR binding of IgG1-IC and reduced TNF production. These effects were associated with high levels of auto-antibodies in the patients, implying that the monocyte FcγR are saturated with IgG. In order to investigate whether soluble FcγR could be used as a therapy in arthritis, we injected human soluble FcγR into mice with collagen-induced arthritis (CIA). The soluble FcγR reduced the levels of pathogenic IgG anti-collagen type II (CII) antibodies, arthritis severity and pro-inflammatory cytokines. Thus, suggesting that soluble FcγR may represent a novel therapeutic agent in RA. We also studied the disease-aggravating role of mast cells in arthritis by investigating mouse mast cell protease-4 (mMCP-4) in CIA. We found that mMCP-4 deficient mice displayed a reduced IgG anti-CII response and reduced arthritis severity. This indicates a role for mMCP-4 in adaptive immunity. In conclusion, these data demonstrate that IgG occupancy of FcγR and mast cell secretion of mMCP-4 play vital roles in the development of autoimmune arthritis.
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| 24. |
- Martinsson, Klara, et al.
(författare)
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The effect of activating and inhibiting Fc-receptors on murine mercury-induced autoimmunity.
- 2008
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Ingår i: Journal of Autoimmunity. - : Elsevier BV. - 0896-8411 .- 1095-9157. ; 31:1, s. 22-29
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Tidskriftsartikel (refereegranskat)abstract
- Fc-receptors for IgG (Fc gamma R) link cellular and humoral immune responses, controlling the balance between activating and inhibitory immune responses, and are involved in autoimmune diseases. Mercury (Hg) induces an autoimmune condition in genetically (H-2(s,q,f)) susceptible mice characterized by lymphoproliferation, hypergammaglobulinemia and IgG antinucleolar antibodies (ANoA). Here we investigate the role of activating (Fc gamma RI, Fc gamma RIII) and inhibitory (Fc gamma RIIb) Fc-receptors on mercury-induced autoimmunity (HgIA) using DBA/1 mice (H-2(q))(-) with targeted Fc gamma R mutations and wild type (wt) mice. Mice deficient for the FcR gamma-chain or FcyRIII and treated with 15 mg/L HgCl2 showed a delayed and attenuated IgG1, IgG2a and IgG2b ANoA response compared to wt mice. Female Hg-treated FcyRIIB(-/-) mice showed a significant increased of lgG2b ANoA development compared to wt mice. The total serum IgG1 response due to Hg was attenuated in FcR gamma(-/-) and Fe gamma RIII-/- mice compared to wt mice. Hg-treated Fc gamma RIIB-/- mice showed an increase of both serum IgG1 and IgE compared to wt mice. We conclude that FcyRIII is of importance for the rapidity and final strength of the ANoA response and the increase in serum IgG1 in HgIA, while lack of Fc gamma RIIb increases the IgG2b ANoA response and the serum IgG1 and IgE response.
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| 25. |
- Matt, Peter, et al.
(författare)
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AB0102 Effects of anti-rheumatic treatment on antibody levels and monocytic fc receptor status in early ra
- 2013
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 72:S3, s. A816-A816
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundFc receptors for IgG (Fcg R) play important roles in immune complex (IC)-mediated inflammation. Studies abrogating Fcg R actions have shown reduction of disease activity in animal models of arthritis. Monocytes are precursor cells of macrophages and osteoclasts, cell types that are highly involved in joint inflammation processes in rheumatoid arthritis (RA). We have investigated if antibody levels and monocytic Fc receptor expression and function in early RA are affected by anti-rheumatic treatment.ObjectivesTwenty sero-positive steroid- and DMARD naive early RA patients and thirty-three healthy controls (HC), gender- and age-matched, were included. The majority of patients were anti-citrullinated protein antibody (ACPA) positive. If not contraindicated treatment with Methotrexate + steroids was initiated. Patients were evaluated before and after 3-4 months of therapy. At follow up patients were grouped in good responders or non responders using EULAR response criteria.MethodsInflammatory laboratory parameters and immunoglobulins (Ig) were analyzed at the Akademiska University hospital laboratory with standardized procedures. Expression of Fc receptor for IgA (CD89) and IgG (FcγRIII, CD16; FcγRIIa, CD32a; FcγRIIb, CD32b; FcγRI, CD64) on CD14 positive monocytes were analyzed with flow cytometry. Fcg R function was evaluated with IgG1 and IgG3 immune complex (IC) binding and IgG stimulated TNFa -production. DAS28, HAQ and patient reported VAS-scores for pain, global assessment and morning stiffness defined disease activity.ResultsAt inclusion RA patients displayed elevated levels of total IgG, IgG1 and IgG3 compared to HC. Expression of CD64 (frequency of cells and mean fluorescence intensity) and surface bound IgG on CD64 positive cells were significantly increased in RA patients. The Fcg R function in the patients was altered: a decrease in IC binding was observed, but monocytic TNFa -production was comparable with HC, except for non-responders who at baseline presented lower TNFa release when stimulated with IgG1. IgG and IgA levels correlated positively with the number of CD64/CD16 positive monocytes. Fc receptor expressions and function correlated with disease activity parameters. ACPA levels showed no correlations with FcR expressions or disease activity parameters.At follow up mean DAS28 had decreased from 5.26 to 3.65 and mean HAQ from 0.95 to 0.45. The patients presented with significantly decreased levels of total Ig isotypes, IgG subclasses, ACPA and rheumatoid factor (RF) isotypes. Good responders excelled by down regulating CD64, decreasing CD16 on CD64 positive cells and increasing CD89. These results were not obtained in non-responders who instead increased the number of CD16 positive cells and CD64 positive cells. Interestingly, the monocytic expression of the inhibitory Fcg R (CD32b) was higher in good responders compared with non-responders at follow up.ConclusionsMonocytic Fc receptor status is altered in early RA. Especially CD64 seems to be important. Successful response to standard anti-rheumatic treatment downregulates its expression.
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| 26. |
- Matt, Peter, et al.
(författare)
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Elevated Membrane and Soluble CD64 : A Novel Marker Reflecting Altered Fc gamma R Function and Disease in Early Rheumatoid Arthritis That Can Be Regulated by Anti-Rheumatic Treatment
- 2015
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:9
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives Fc receptors (FcR) interacting with immune complexes (ICs) is a central event in the immune pathogenesis of rheumatoid arthritis (RA). Here we asked if a specific FcR is linked to RA pathogenesis and if FcR activities relate to disease and treatment outcome in early RA. Material and Methods Twenty autoantibody-positive RA patients and 33 HC were included. The patients were evaluated before and after treatment with methotrexate and prednisolone. At follow-up, the EULAR response criteria were applied to determine the individual treatment outcomes. Serum immunoglobulin levels were measured and the expression of FcR for IgG (Fc gamma R) and IgA (Fc alpha R) on peripheral blood monocytes were determined by flow cytometry. The monocytic Fc gamma R function was evaluated by human IgG1 and IgG3 IC-binding and TNF alpha stimulated release. Plasma levels of soluble FcRs (sFcRs) were determined with ELISA. Results The IgG1 and IgG3 levels were elevated in the RA sera. The RA monocytes expressed more CD64 and cell surface-bound IgG than HC monocytes, and showed an impaired Fc gamma R function as reflected by changes in IC-binding and decreased IC-stimulated TNF alpha secretion. These findings correlated significantly with different disease activity markers. Furthermore, sFcRs were elevated in the patient plasma, and sCD64 was specific for RA (compared with a reference group of patients with active psoriatic arthritis). Following treatment, immunoglobulins and sFcR levels were reduced, whereas membrane CD64 was only decreased in patients with good response to treatment. Conclusions Early RA patients display increased membrane and soluble CD64 and an impaired Fc gamma R function correlating with joint disease activity. Beneficial responses of anti-rheumatic treatment in patients reduce CD64. These data suggest sCD64 as an important objective biomarker in RA.
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| 27. |
- Matt, Peter
(författare)
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Fc receptors and immunoglobulins in polyarthritis : A matter of function, supply and demand?
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fc receptors (FcR) and immunoglobulins (Ig) play important roles in the defence against pathogens. However, altered interactions of these may promote chronic inflammation in rheumatic diseases. An excess of Igs forming immune complexes (IC) could lead to continuous FcR activation and spreading of autoimmune inflammation to other tissues.This work focuses on the evaluation of the FcR status and function in the two most common polyarthritides - psoriatic arthritis (PsA) and rheumatoid arthritis (RA) – in relation to various Igs, joint and skin disease activity, and effect of anti-rheumatic treatment (determined by the EULAR response criteria for RA). Monocyte subpopulations (defined by surface CD14 and CD16 expressions) in patients and HC were also characterised, since different monocyte subsets may have opposing functions in inflammatory conditions. In addition, the effect and safety of long-term B-cell suppression in advanced RA was studied.In PsA, elevated serum levels of IgG1, 2, and 3 were noted while the early naïve RA patients - besides being positive for autoantibodies like IgMRF, IgARF, IgGRF, and ACPA IgG - were distinguished by high levels of IgG1 and IgG3. Monocytes of PsA and RA patients were heavily loaded with IgG and expressed more CD64 (i.e. the high affinity FcγR) than HC. An increase in CD64 turnover was specific for early RA, while a higher CD16a (i.e. a low affinity FcγR) turnover was seen in both RA and PsA compared with HC. The FcγR function was impaired in both polyarthritides compared to HC, but the RA monocytes were more affected of this than the PsA monocytes. RA non-responders had a much lower capacity of IC binding compared with RA good responders. Alterations of the FcR status and function reflected joint disease activity markers in both polyarthritides but not the skin disease activity in PsA. I therefore conclude that the observed FcR statuses in both diseases were specific for joint inflammation. In addition, RA patients with high levels and the occurrence of several simultaneously appearing RF isotypes presented a minor FcγR function, while patients experiencing a good treatment effect were more likely to show low levels of Igs. This suggests that RFs/IC in excess could be important promotors of the ongoing inflammation in RA. However, for ACPA IgG no associations with the rheumatoid monocytic FcR status/function were noted. CD16negative classical monocytes were elevated in early naïve RA, especially in the non-responders - while PsA patients showed an increase in CD16low expressing cells compared to HC. These observations indicate that different monocyte subpopulations could be important in the two polyarthritides. In a cohort of RA patients with advanced disease, long-term B-cell suppression resulted in conversion to RF negativity which indicated a good treatment response but not an increased risk of infection. FcRs and Igs are important players that promote chronicity of inflammation in polyarthritis, especially in RA. An impaired FcγR function following an excess of Igs/IC reflects this state of the immune system. This work has identified an increased monocytic CD64 turnover as a RA specific feature. Future treatment options in RA might include supporting/normalizing the FcγR function. Today suppressing B-cell activity is an effective and relatively safe way to tackle the problem from the opposite side.
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| 28. |
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| 29. |
- Matt, Peter, et al.
(författare)
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Up-regulation of CD64-expressing monocytes with impaired Fc gamma R function reflects disease activity in polyarticular psoriatic arthritis
- 2015
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Ingår i: Scandinavian Journal of Rheumatology. - : Informa UK Limited. - 0300-9742 .- 1502-7732. ; 44:6, s. 464-473
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: The aim of this study was to assess monocyte Fc receptor (FcR) status and function in patients with active psoriatic arthritis (PsA) in relation to healthy controls (HC) and to disease activity.Method:The study population comprised 23 patients with active polyarticular PsA and 33 age- and gender-matched HC. Immunoglobulin (Ig) levels, inflammatory laboratory parameters, patient-reported outcomes of joint disease activity, skin scoring (Psoriasis Area and Severity Index, PASI), and joint status were determined in the patients. Monocytes were analysed for the expression of FcRs for IgG (FcR) class I (CD64), IIa (CD32a), IIb (CD32b), and III (CD16), the FcR for IgA (FcR) (CD89), and surface-bound IgG. The monocytic FcR function was assessed by evaluating IgG immune complex (IC) binding and tumour necrosis factor (TNF)- production following IgG-IC stimulation. The monocytes were further subdivided and analysed according to their CD14 and CD16 expression.Results:The PsA patients presented elevated serum levels of IgG1, 2, and 3 and increased numbers of CD64(+) monocytes. Furthermore, the PsA monocytes exhibited increased cell-bound IgG, and the FcR function was affected in terms of reduced IgG-IC-mediated TNF- release. These findings correlated significantly with different markers of joint disease activity. PsA was also accompanied by an increase in the CD16 low-expressing monocyte subset.Conclusions:An intensified humoral immune response affects monocytes and their FcR status in active polyarticular PsA. The up-regulated CD64(+) monocytes seem to be have an important role in psoriatic joint inflammation. These cells may prove to be a useful target in future PsA therapeutic interventions.
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| 30. |
- Myers, Linda K., et al.
(författare)
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T Cells Stimulated With an Analog Peptide of Type II Collagen Require the Fc Receptor gamma-Chain to Secrete Interleukin-4 and Suppress Autoimmune Arthritis in Mice
- 2011
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Ingår i: Arthritis and Rheumatism. - : Wiley. - 0004-3591 .- 1529-0131. ; 63:9, s. 2661-2670
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Tidskriftsartikel (refereegranskat)abstract
- Objective. To explore the characteristics of the T cell population that responds to an analog peptide (A9) of type II collagen and regulates autoimmunity, using the collagen-induced arthritis (CIA) model. Methods. Analog peptide A9 is a 26-amino acid peptide analogous to the sequence of a segment of type II collagen (CII(245-270)) but with substitutions at amino acid positions 260 (alanine for isoleucine), 261 (hydroxyproline for alanine), and 263 (asparagine for phenylalanine). We previously showed that A9 profoundly suppressed CIA and immune responses to type II collagen. In order to determine the mechanism of suppression, we used transgenic mice whose T cells express a type II collagen-specific receptor (T cell receptor) and performed passive cell transfer experiments. Results. The results demonstrated that suppression of CIA by A9 is dependent on T cells. Using multiparameter flow cytometry, we determined that the cells responsible for suppression were CD4+ and expressed high levels of Fc epsilon receptor I gamma chain (FcR gamma). To establish the significance of this finding, we obtained mice genetically deficient in FcR gamma in order to perform passive transfer experiments. The resulting FcR gamma(-/-) CD4+ T cells, when primed by culture with A9, could not transfer the suppression of arthritis or secrete cytokines in response to A9. Conclusion. Taken together, the results of this study suggest that the suppression of arthritis and the Th2 cytokine profile elicited by A9 is dependent on the presence of FcR gamma in T cells. These findings are novel and may have therapeutic potential for patients with autoimmune arthritis.
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| 31. |
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| 32. |
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| 33. |
- Nilsson, Kajsa E., et al.
(författare)
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Enhanced susceptibility to low-dose collagen-induced arthritis in CR1/2-deficient female mice : possible role of estrogen on CR1 expression
- 2009
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Ingår i: The FASEB Journal. - : Wiley. - 0892-6638 .- 1530-6860. ; 23:8, s. 2450-2458
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Tidskriftsartikel (refereegranskat)abstract
- The influence of complement receptor 1 and 2 (CR1/2) was investigated on the susceptibility to low-dose collagen-induced arthritis (CIA) in wild-type (WT) and CR1/2-deficient DBA/1 mice. Significantly enhanced CIA was observed in female CR1/2-deficient mice compared with WT female mice, while male mutant and WT mice showed similar arthritis development. The enhanced CIA was accompanied with higher complement levels and a prolonged IgM anti-collagen type II response. When investigating whether estrogen contributed to the different arthritis susceptibility, we found that ovariectomy rendered WT females more sensitive to low-dose CIA and to the same extent as CR1/2-deficient females, while CR1/2-deficient mice were unaffected by ovariectomy. Notably, the ovariectomized WT mice displayed reduced CR1(+) B220(+) B-cell numbers and CR1 expression compared with sham-operated WT mice, suggesting a stimulatory effect of estrogen on CR1. In accordance, a significant correlation was observed between reduced CR1 expression in B cells and increased age in healthy female blood donors but not in male donors. Our findings demonstrate an important role of CR1/2 in suppressing CIA in female mice under low-antigen conditions. The data suggest that estrogen promote CR1 expression in B cells. These findings provide insight to the increased frequency of rheumatoid arthritis in postmenopausal women.
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| 34. |
- Olaru, Florina, et al.
(författare)
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Proteolysis Breaks Tolerance toward Intact alpha 345(IV) Collagen, Eliciting Novel Anti-Glomerular Basement Membrane Autoantibodies Specific for alpha 345NC1 Hexamers
- 2013
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 190:4, s. 1424-1432
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Tidskriftsartikel (refereegranskat)abstract
- Goodpasture disease is an autoimmune kidney disease mediated by autoantibodies against noncollagenous domain 1 (NC1) monomers of alpha 3(IV) collagen that bind to the glomerular basement membrane (GBM), usually causing rapidly progressive glomerulonephritis (GN). We identified a novel type of human IgG4-restricted anti-GBM autoantibodies associated with mild nonprogressive GN, which specifically targeted alpha 345NC1 hexamers but not alpha 3NC1 monomers. The mechanisms eliciting these anti-GBM autoantibodies were investigated in mouse models recapitulating this phenotype. Wild-type and Fc gamma RIIB-/- mice immunized with autologous murine GBM NC1 hexamers produced mouse IgG1-restricted autoantibodies specific for alpha 345NC1 hexamers, which bound to the GBM in vivo but did not cause GN. In these mice, intact collagen IV from murine GBM was not immunogenic. However, in Col4a3(-/-) Alport mice, both intact collagen IV and NC1 hexamers from murine GBM elicited IgG Abs specific for alpha 345NC1 hexamers, which were not subclass restricted. As heterologous Ag in COL4A3-humanized mice, murine GBM NC1 hexamers elicited mouse IgG1, IgG2a, and IgG2b autoantibodies specific for alpha 345NC1 hexamers and induced anti-GBM Ab GN. These findings indicate that tolerance toward autologous intact alpha 345(IV) collagen is established in hosts expressing this Ag, even though autoreactive B cells specific for alpha 345NC1 hexamers are not purged from their repertoire. Proteolysis selectively breaches this tolerance by generating autoimmunogenic alpha 345NC1 hexamers. This provides a mechanism eliciting autoantibodies specific for alpha 345NC1 hexamers, which are restricted to noninflammatory IgG subclasses and are nonnephritogenic. In Alport syndrome, lack of tolerance toward alpha 345(IV) collagen promotes production of alloantibodies to alpha 345NC1 hexamers, including proinflammatory IgG subclasses that mediate posttransplant anti-GBM nephritis.
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| 35. |
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| 36. |
- Palm, Anna-Karin E., et al.
(författare)
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Activated mast cells promote differentiation of B cells into effector cells
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Based on the known accumulation of mast cells (MCs) in B cell-dependent inflammatory diseases, including rheumatoid arthritis, we hypothesized that MCs directly modulate B cells. We show here that degranulated, and to a lesser extent naive or IgE-sensitized, MCs activate both naive and B cell receptor-activated B cells. This was shown by increased proliferation, blast formation, and expression of CD19, MHC class II and CD86 in the B cells. Further, MCs stimulated the secretion of IgM and IgG in IgM(+) B cells, indicating that MCs can induce class-switch recombination in B cells. We also show that coculture of MCs with B cells promotes surface expression of L-selectin, a homing receptor, on the B cells. The effects of MCs on B cells were partly dependent on cell-cell contact and both follicular and marginal zone B cells could be activated by MCs. Our findings suggest that degranulated MCs support optimal activation of B cells, a finding that is in line with in vivo studies showing that MCs frequently degranulate in the context of B-cell driven pathologies such as arthritis. Together, our findings show that MCs have the capacity to differentiate B cells to effector cells.
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| 37. |
- Palm, Anna-Karin E., 1983-
(författare)
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Function and Regulation of B-cell Subsets in Experimental Autoimmune Arthritis
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- B lymphocytes play a significant role in autoimmune arthritis, with their function stretching beyond autoantibody production to cytokine secretion and presentation of autoantigen. However, the involvement and activation of different B-cell subset in the autoimmune response is not fully clear. The main focus of this thesis has been to understand the contribution of marginal zone (MZ) B cells in the induction of collagen-induced arthritis (CIA), a mouse model for rheumatoid arthritis (RA).We show that MZ B cells in the spleen of naïve mice display a natural self-reactivity to collagen type II (CII), the autoantigen used for immunization of CIA. The CII-reactive MZ B cells expand rapidly following immunization with CII, and produce IgM and IgG antibodies to CII. They also very efficiently present CII to cognate T cells in vitro and in vivo. Moreover, absence of regulatory receptors such as CR1/2 or FcγRIIb on the MZ B cells increases their proliferation and cytokine production in response to toll-like receptor, but not B-cell receptor, activation. Further, FcγRIIb-deficient MZ B cells present CII to T cells more efficiently than wild-type MZ B cells. We additionally demonstrate for the first time the existence of a small population of nodal MZ B cells in mouse lymph nodes. Similar to splenic MZ B cells, the nodal MZ B cells expand after CIA induction, secrete IgM anti-CII antibodies and can present CII to cognate T cells. Finally, we show that mast cells, associated with ectopic B cell follicles in inflamed RA joints, in coculture with B cells promote their expansion, production of IgM and IgG antibodies as well as upregulation of CD19 and L-selectin. Coculture with mast cells further causes the B cells to upregulate costimulators and class II MHC, important molecules for antigen-presenting function.In summary, my findings suggest that splenic and nodal self-reactive MZ B cells participate in breaking T-cell tolerance to CII in CIA. B-cell intrinsic regulation is needed to keep such autoreactive B cells quiescent. Mast cells can potentiate B-cell responses locally in the arthritic joint, thus feeding the autoimmune reaction.
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| 38. |
- Palm, Anna-Karin E., et al.
(författare)
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Function and regulation of self-reactive marginal zone B cells in autoimmune arthritis
- 2015
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Ingår i: Cellular & Molecular Immunology. - : Springer Science and Business Media LLC. - 1672-7681 .- 2042-0226. ; 12:4, s. 493-504
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Tidskriftsartikel (refereegranskat)abstract
- Polyreactive innate-type B cells account for many B cells expressing self-reactivity in the periphery. Improper regulation of these B cells may be an important factor that underlies autoimmune disease. Here we have explored the influence of self-reactive innate B cells in the development of collagen-induced arthritis (CIA), a mouse model of rheumatoid arthritis. We show that splenic marginal zone (MZ), but not B-1 B cells exhibit spontaneous IgM reactivity to autologous collagen II in naive mice. Upon immunization with heterologous collagen II in complete Freund's adjuvant the collagen-reactiveMZ B cells expanded rapidly, while the B-1 B cells showed a modest anti-collagen response. The MZ B cells were easily activated by toll-like receptor (TLR) 4 and 9-ligands in vitro, inducing proliferation and cytokine secretion, implying that dual engagement of the B-cell receptor and TLRs may promote the immune response to self-antigen. Furthermore, collagen-primed MZ B cells showed significant antigen-presenting capacity as reflected by cognate T-cell proliferation in vitro and induction of IgG anti-collagen antibodies in vivo. MZ B cells that were deficient in complement receptors 1 and 2 demonstrated increased proliferation and cytokine production, while Fc gamma receptor IIb deficiency of the cells lead to increased cytokine production and antigen presentation. In conclusion, our data highlight self-reactive MZ B cells as initiators of the autoimmune response in CIA, where complement and Fc receptors are relevant in controlling the self-reactivity in the cells.
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| 39. |
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| 40. |
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| 41. |
- Palm, Anna-Karin E., 1983-, et al.
(författare)
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Marginal zone B cells : From housekeeping function to autoimmunity?
- 2021
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Ingår i: Journal of Autoimmunity. - : Elsevier. - 0896-8411 .- 1095-9157. ; 119
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Tidskriftsartikel (refereegranskat)abstract
- Marginal zone (MZ) B cells comprise a subset of innate-like B cells found predominantly in the spleen, but also in lymph nodes and blood. Their principal functions are participation in quick responses to blood-borne pathogens and secretion of natural antibodies. The latter is important for housekeeping functions such as clearance of apoptotic cell debris. MZ B cells have B cell receptors with low poly-/self-reactivity, but they are not pathogenic at steady state. However, if simultaneously stimulated with self-antigen and pathogen- and/or damageassociated molecular patterns (PAMPs/DAMPs), MZ B cells may participate in the initial steps towards breakage of immunological tolerance. This review summarizes what is known about the role of MZ B cells in autoimmunity, both in mouse models and human disease. We cover factors important for shaping the MZ B cell compartment, how the functional properties of MZ B cells may contribute to breaking tolerance, and how MZ B cells are being regulated.
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| 42. |
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| 43. |
- Palm, Anna-Karin E., et al.
(författare)
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Nodal marginal zone B cells in mice : a novel subset with dormant self-reactivity
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Marginal zone (MZ) B cells, representing a distinct subset of innate-like B cells, mount rapid T-independent responses to blood-borne antigens. They express low-affinity polyreactive antigen receptors that recognize both foreign and self-structures. The spleen is considered the exclusive site for murine MZ B cells. However, we have here identified B cells with a MZ B-cell phenotype in the subcapsular sinuses of mouse lymph nodes. The nodal MZ (nMZ) B cells display high levels of IgM, costimulators and TLRs, and are represented by naive and memory cells. The frequency of nMZ B cells is about 1-6% of nodal B cells depending on mouse strain, with higher numbers in older mice and a trend of increased numbers in females. There is a significant expansion of nMZ B cells following immunization with an autoantigen, but not after likewise immunization with a control protein or with the adjuvant alone. The nMZ B cells secrete autoantibodies upon activation and can efficiently present autoantigen to cognate T cells in vitro, inducing T-cell proliferation. The existence of self-reactive MZ B cells in lymph nodes may be a source of autoantigen-presenting cells that in an unfortunate environment may activate T cells leading to autoimmunity.
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| 44. |
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| 45. |
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| 46. |
- Park, Jeoung-Eun, et al.
(författare)
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Molecular Basis for T Cell Response Induced by Altered Peptide Ligand of Type II Collagen
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:23, s. 19765-19774
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Tidskriftsartikel (refereegranskat)abstract
- Mounting evidence from animal models has demonstrated that alterations in peptide-MHC interactions with the T cell receptor (TCR) can lead to dramatically different T cell outcomes. We have developed an altered peptide ligand of type II collagen, referred to as A9, which differentially regulates TCR signaling in murine T cells leading to suppression of arthritis in the experimental model of collagen-induced arthritis. This study delineates the T cell signaling pathway used by T cells stimulated by the A9.I-A(q) complex. We have found that T cells activated by A9 bypass the requirement for Zap-70 and CD3-zeta and signal via FcR gamma and Syk. Using collagen-specific T cell hybridomas engineered to overexpress either Syk, Zap-70, TCR-FcR gamma, or CD3-zeta, we demonstrate that A9.I-A(q) preferentially activates FcR gamma/Syk but not CD3-zeta/Zap-70. Moreover, a genetic absence of Syk or FcR gamma significantly reduces the altered peptide ligand induction of the nuclear factor GATA3. By dissecting the molecular mechanism of A9-induced T cell signaling we have defined a new alternate pathway that is dependent upon FcR gamma and Syk to secrete immunoregulatory cytokines. Given the interest in using Syk inhibitors to treat patients with rheumatoid arthritis, understanding this pathway may be critical for the proper application of this therapy.
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| 47. |
- Prokopec, Kajsa
(författare)
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B cells in Autoimmunity : Studies of Complement Receptor 1 & 2 and FcγRIIb in Autoimmune Arthritis
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- B cells are normally regulated to prevent activation against self-proteins through tolerance mechanisms. However, occasionally there is a break in tolerance and B cells can become self-reactive, which might lead to the development of autoimmune disease. The activation of self-reactive B cells is regulated by receptors on the B cell surface, such as Fc gamma receptor IIb (FcγRIIb), complement receptor type 1 (CR1), and CR type 2 (CR2). In this thesis I have studied the role of FcγRIIb, CR1 and CR2 on B cells in autoimmune arthritis. By using a model for rheumatoid arthritis, I discovered that the initial self-reactive B cell response in arthritis was associated with the splenic marginal zone B cell population. Marginal zone B cells express high levels of CR1/CR2 and FcγRIIb, suggesting that they normally require high regulation. Further, female mice deficient in CR1/CR2 displayed increased susceptibility to arthritis compared to CR1/CR2-sufficient female mice. When investigating whether sex hormones affected arthritis susceptibility, we found that ovariectomy, of the otherwise fairly resistant CR1/CR2-sufficient mice, reduced the expression of CR1 on B cells and rendered the mice more susceptible to arthritis. In humans, a significantly reduced CR1 and FcγRIIb expression was found on B cells in aging women, but not in men. This may contribute to the increased risk for women to develop autoimmune disease as reduced receptor expression may lead to the activation of self-reactive B cells. In agreement, lower CR1, CR2 and FcγRIIb expression was seen in patients with rheumatoid arthritis. Finally, a soluble form of FcγRIIb was used to investigate FcγRIIb’s ability to bind self-reactive IgG in an attempt to treat autoimmune arthritis. Treatment of mice with established arthritis was associated with less self-reactive IgG antibodies and consequently less disease, suggesting that soluble FcγRIIb may be used as a novel treatment in arthritis.
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| 48. |
- Prokopec, Kajsa, et al.
(författare)
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Down regulation of Fc and complement receptors on B cells in rheumatoid arthritis
- 2010
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Ingår i: Clinical Immunology. - : Elsevier BV. - 1521-6616 .- 1521-7035. ; 137:3, s. 322-329
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Tidskriftsartikel (refereegranskat)abstract
- B cell tolerance is regulated by receptors that modulate B cell receptor signaling, such as Fc gamma receptor IIb (FcγRIIb; CD32b) and complement receptors (CR) 1 and 2. Deficiency in these receptors may contribute to autoimmunity. To address this we have investigated the receptor expression in healthy individuals in comparison with rheumatoid arthritis (RA) patients. In healthy subjects we found that women had overall lower Fcgamma;RIIb expression on B cells than men that significantly decreased with age. RA patients had fewer FcγRIIb, CR1 and CR2 positive B cells and decreased receptor expressions compared to healthy subjects. Further, the RA B cells displayed a significantly increased proliferative response when cultured with interleukin-2 in vitro. In summary, the dysregulated B cells in RA are associated with lower FcγRIIb, CR1 and CR2 levels. The reduced FcγRIIb expression on B cells in women may influence the increased frequency of autoimmunity in women.
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| 49. |
- Prokopec, Kajsa E., et al.
(författare)
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Up Regulated Complement and Fc Receptors in Juvenile Idiopathic Arthritis and Correlation with Disease Phenotype
- 2012
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Ingår i: Journal of Clinical Immunology. - : Springer Science and Business Media LLC. - 0271-9142 .- 1573-2592. ; 32:3, s. 540-550
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: The progress in identifying immunological mechanisms in juvenile idiopathic arthritis (JIA) has partly been hampered by the fact that the disease is heterogeneous. Here we have investigated complement and Fc receptors, as part of the inflammatory process, in two subgroups of JIA.METHODS: Blood from 26 patients with oligoarticular or polyarticular course type JIA and 21 healthy age and sex-matched controls were investigated by FACS and immunoassays.RESULTS: Increased numbers of monocytes and augmented plasma levels of C-reactive protein, C3a and IgG were found in both JIA subgroups. However, only polyarticular patients exhibited increased expression of Fc gamma receptor (FcγR) II and III and complement receptor (CR) 1 on monocytes along with enhanced CR1 expression on B cells. A correlation was observed between degree of receptor expression and C3a levels in the patients.CONCLUSIONS: Complement and Fc receptors are up regulated in children with multiple joint involvements, thus highlighting these pathways in the pathogenesis of polyarticular JIA.
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- Zhang, Jun-Jun, et al.
(författare)
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Murine Membranous Nephropathy : Immunization with alpha 3(IV) Collagen Fragment Induces Subepithelial Immune Complexes and Fc gamma R-Independent Nephrotic Syndrome
- 2012
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Ingår i: Journal of Immunology. - : The American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 188:7, s. 3268-3277
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Tidskriftsartikel (refereegranskat)abstract
- Membranous nephropathy (MN) is a leading cause of nephrotic syndrome in adults and a significant cause of end-stage renal disease, yet current therapies are nonspecific, toxic, and often ineffective. The development of novel targeted therapies requires a detailed understanding of the pathogenic mechanisms, but progress is hampered by the lack of a robust mouse model of disease. We report that DBA/1 mice as well as congenic Fc gamma RIII-/- and FcR gamma(-/-) mice immunized with a fragment of alpha 3(IV) collagen developed massive albuminuria and nephrotic syndrome, because of subepithelial deposits of mouse IgG and C3 with corresponding basement membrane reaction and podocyte foot process effacement. The clinical presentation and histopathologic findings were characteristic of MN. Although immunized mice produced genuine anti-alpha 3NC1 autoantibodies that bound to kidney and lung basement membranes, neither crescentic glomerulonephritis nor alveolitis ensued, likely because of the predominance of mouse IgG1 over IgG2a and IgG2b autoantibodies. The ablation of activating IgG Fc receptors did not ameliorate injury, implicating subepithelial deposition of immune complexes and consequent complement activation as a major effector pathway. We have thus established an active model of murine MN. This model, leveraged by the availability of genetically engineered mice and mouse-specific reagents, will be instrumental in studying the pathogenesis of MN and evaluating the efficacy of novel experimental therapies.
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