Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0003864 (arthritis)
 69,039 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rheumatoid arthritis is a chronic inflammatory disease primarily affecting the joints. The search for arthritogenic autoantigens that trigger autoimmune responses in rheumatoid arthritis has largely focused on cartilage- or joint-specific Ags. In this study, we show that immunization with the ubiquitously expressed glycolytic enzyme glucose-6-phosphate isomerase (G6PI) induces severe peripheral symmetric polyarthritis in normal mice. In genetically unaltered mice, T cells are indispensable for both the induction and the effector phase of G6PI-induced arthritis. Arthritis is cured by depletion of CD4(+) cells. In contrast, Abs and FcgammaR(+) effector cells are necessary but not sufficient for G6PI-induced arthritis in genetically unaltered mice. Thus, the complex pathogenesis of G6PI-induced arthritis in normal mice differs strongly from the spontaneously occurring arthritis in the transgenic K/B x N model where Abs against G6PI alone suffice to induce the disease. G6PI-induced arthritis demonstrates for the first time the induction of organ-specific disease by systemic autoimmunity in genetically unaltered mice. Both the induction and effector phase of arthritis induced by a systemic autoimmune response can be dissected and preventive and therapeutic strategies evaluated in this model.
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PMID:Immunization with glucose-6-phosphate isomerase induces T cell-dependent peripheral polyarthritis in genetically unaltered mice. 1503 67

In the K/BxN mouse model of arthritis, autoantibodies against glucose-6-phosphate isomerase cause joint-specific inflammation and destruction. We have shown using micro-positron emission tomography that these glucose-6-phosphate isomerase-specific autoantibodies rapidly localize to distal joints of mice. In this study we used micro-positron emission tomography to delineate the stages involved in the development of arthritis. Localization of Abs to the joints depended upon mast cells, neutrophils, and FcRs, but not on C5. Surprisingly, anti-type II collagen Abs alone did not accumulate in the distal joints, but could be induced to do so by coinjection of irrelevant preformed immune complexes. Control Abs localized to the joint in a similar manner. Thus, immune complexes are essential initiators of arthritis by sequential activation of neutrophils and mast cells to allow Abs access to the joints, where they must bind a target Ag to initiate inflammation. Our findings support a four-stage model for the development of arthritis and identify checkpoints where the disease is reversible.
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PMID:Staging the initiation of autoantibody-induced arthritis: a critical role for immune complexes. 1518 52

Glucose-6-phosphate isomerase (GPI), recognized as an autoantigen in the K/BxN arthritis model, is a ubiquitous cytoplasmic enzyme. Anti-GPI antibodies (Abs) are also detected in the serum of patients with arthritic diseases including rheumatoid arthritis (RA). So far, 24 GPI variants have been reported and most of these variants relate to non-spherocytic hemolytic disease. To understand the mechanisms of anti-GPI Ab production, cDNAs from peripheral blood mononuclear cells of subjects with or without anti-GPI Abs were cloned and sequenced. We identified 39 new GPI variants (57-1596 bp). The frequency of GPI variants in healthy control subjects (HS) with anti-GPI Abs (27/73, 31.5%) was significantly higher than that in anti-GPI Ab-negative HS (5/78, 6.4%, p < 0.001). The frequency of GPI variants in anti-GPI Ab-positive RA patients (22/77, 28.6%) was more significantly higher than in anti-GPI Ab-negative patients (1/63, 1.6%, p < 0.0001). Our results suggest that GPI variants may play a crucial role in the production of autoantibodies against ubiquitous GPI autoantigens.
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PMID:Glucose-6-phosphate isomerase variants play a key role in the generation of anti-GPI antibodies: possible mechanism of autoantibody production. 1536 82

The antigens that trigger the pathogenic immune response in rheumatoid arthritis (RA) remain unknown. Until recently it was assumed that either viral or microbial antigens, or joint-specific antigens were the target of arthritogenic T and B lymphocytes in RA. Consequently, murine models of arthritis are induced by immunization with either joint-specific antigens such as type II collagen or microbial products such as streptococcal cell wall. In the K/BxN T-cell receptor transgenic mouse model arthritis is caused by a systemic autoimmune response to the ubiquitously expressed glycolytic enzyme glucose-6-phosphate isomerase (G6PI). The autoreactive transgenic T cells recognize G6PI and provide help for the production of arthritogenic IgG antibodies against G6PI. More recently it was shown that G6PI immunization induces severe symmetrical peripheral polyarthritis in genetically unaltered DBA/I mice. In that model CD4+ T cells are necessary not only for the induction but also for the effector phase of arthritis. Here we review the pathomechanisms that lead from systemic autoreactivity to arthritis in these models, consider the relevance of anti-G6PI immune reactivity for RA, and discuss the insights into the pathogenesis of RA and possibly other autoimmune conditions that can be gained from these models.
Arthritis Res Ther 2005
PMID:The role and clinical implications of G6PI in experimental models of rheumatoid arthritis. 1564 50

Although bacterial LPS has been used to boost the susceptibility to antibody-induced arthritis, the mechanism of the action of LPS remains to be clarified. We investigated whether signals triggered by Toll-like receptor (TLR)-4 mediate the effects of LPS in the context of anti-type II collagen-induced arthritis. The mice defective in the Tlr-4 gene (Tlr-4(lps-d)) were markedly less susceptible than wild type to arthritis, as manifested in arthritic index, incidence and synovitis. Levels of the pro-inflammatory mediators, tumor necrosis factor-alpha and cyclooxygenase-2, in their synovial tissue were also much lower. Serum C3 deposition through the alternative pathway and de novo synthesis of C3 were lower in the Tlr-4(lps-d) mice in the post-acute phase, pointing to an influence of TLR-4 signals on the turnover rate of complement cascades. T cells from the Tlr-4(lps-d) mice failed to proliferate in response to an auto-antigen, glucose-6-phosphate isomerase (GPI), unlike those from wild-type mice, and the serum level of GPI-specific IgG antibody was significantly lower than in the wild-type mice. Interestingly, type 2 responses, such as GPI-specific IgG1 and IL-4 production, were up-regulated in the Tlr-4(lps-d) mice. Taken together, our data suggest that the TLR-4 signaling pathway plays an essential role in the initiation and progression of auto-antibody/LPS-triggered arthritis by inducing pro-inflammatory mediators, C3 deposition, auto-antigen-specific adaptive immune responses and immune deviation between type 1 and type 2 responses.
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PMID:Essential roles of Toll-like receptor-4 signaling in arthritis induced by type II collagen antibody and LPS. 1568 36

K/BxN mice develop an inflammatory joint disease with many features characteristic of rheumatoid arthritis. This model is based on a T-cell receptor transgene, KRN, that has been shown to recognize both the foreign antigen bovine RNase, and the ubiquitously expressed self antigen, glucose-6-phosphate isomerase (GPI). We have used this model to investigate the initial events that occur during the autoimmune response to GPI. We and others have identified key mediators in the inflammatory response: Fc receptors (FcRs) (in particular FcRIII), the alternative pathway of complement, neutrophils, and mast cells. Using micro position emission tomography, we demonstrated that anti-GPI Immunoglobulin G (IgG) localizes specifically to the joints where arthritis occurs and that this localization is dependent on mast cells, neutrophils, FcRs, and immune complexes. The trigger of arthritis in this model is the KRN T-cell inducing the production of anti-GPI Ig. By overexpressing the ligand for the KRN T-cells in major histocompatibility complex class II-expressing cells, we demonstrated that KRN T-cells were able to escape tolerance induction in the thymus owing to insufficient levels of antigen in the thymus antigen-presenting cells. This allows the KRN T-cells to exit to the periphery, where they provide help to anti-GPI B-cells, inducing the production of arthritogenic Ig. To understand the joint specificity of the disease, we followed the anti-GPI B-cell response that naturally arises in K/BxN mice and showed that, although the GPI antigen is ubiquitously expressed, the anti-GPI B-cell response is focused on the lymph nodes draining the affected joints. Together, these studies have given us a greater understanding of how an autoimmune response is initiated at the level of both the adaptive and innate immune systems and demonstrate the versatility of the K/BxN arthritis model for studying human disease.
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PMID:Initiation of an autoimmune response: insights from a transgenic model of rheumatoid arthritis. 1610 55

Anti-glucose-6-phosphate isomerase (GPI) antibodies (Abs) solely induce arthritis in mice. High titers of anti-GPI Abs are found in some patients with rheumatoid arthritis (RA), but their pathogenic role remains elusive. The aim of this study was to evaluate the pathogenic role of anti-GPI Abs in cynomolgus monkeys. IgG fractions were separated from sera of anti-GPI Abs-positive RA patients and healthy subjects and directly injected into the metacarpophalangeal joints of 4 cynomolgus monkeys. At day 16, the joints were harvested and examined histologically and immunohistochemically. The expression of C5a receptor (C5aR) molecule in the synovium was quantified by real-time PCR using cDNA from monkey joints. In monkey joints, IgG including anti-GPI Abs resulted in recruitment of granulocytes and mononuclear cells, strong deposition of human IgG on the articular surface, and overexpression of C5aR, but no joint swelling. No infiltrated cells or IgG deposition were observed in monkeys injected with IgGs from healthy subjects. Our results suggest that IgG fraction from RA patients including anti-GPI Abs may play a crucial role in the generation of synovitis in monkeys, although the pathogenesis of anti-GPI Abs in RA patients is still uncertain.
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PMID:Immunoglobulin G from anti-glucose-6-phosphate isomerase antibodies positive patient with rheumatoid arthritis induces synovitis in cynomolgus monkeys. 1613 14

Autoantibodies in the form of immune complexes are known to be crucial mediators in initiating inflammation in a variety of autoimmune diseases. This has been well documented in the anti-collagen II antibody-induced arthritis animal model for a long time now. Recently, in the K/B x N mouse model (the F1 of the TCR-transgenic KRN and the diabetic NOD mice), anti-glucose-6-phosphate isomerase (GPI) autoantibodies have been shown to induce arthritis. Experimental work in the K/B x N model demonstrated key roles of autoantigenic immune complexes activating the alternative pathway of complement, the subsequent association with C5aR and Fc gammaRIII-mediated cell activation and production of the inflammatory cytokines IL-1 and TNF-alpha, finally leading to joint destruction. The presence of high amounts of inflammatory cytokines and matrix-degrading proteases at sites of inflammation obviously put the cytokine-producing macrophages as the next target for investigation in this model. Here, we show that mice depleted of macrophages by clodronate liposome treatment are completely resistant to K/B x N serum-induced arthritis. Reconstituting clodronate liposome-treated mice with macrophages from naive animals could reverse this resistance. Also, we found that deficiencies in the Wiskott-Aldrich syndrome protein and CD40, which are both implicated in macrophage activation, chemotaxis and phagocytosis, are not essential in serum-induced arthritis. Mast cell degranulation was seen in arthritogenic serum-treated mice even in the absence of macrophages, possibly suggesting that mast cell degranulation/activation acts hierarchically before macrophages in the inflammatory cascade of anti-GPI antibody-induced arthritis.
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PMID:A crucial role for macrophages in the pathology of K/B x N serum-induced arthritis. 1618 Feb 50

The pathogenic role of autoantibodies in rheumatoid arthritis (RA) remains elusive. Anti-glucose-6-phosphate isomerase (GPI) antibodies (Abs) are candidates for arthritogenic Abs because they directly induce arthritis in mice. High titers of anti-GPI Abs are found in some RA patients with severe forms. The aim of this study was to analyze the role of IgG, including anti-GPI Abs, in the joints of RA patients. Synovial tissue was obtained from 6 patients with RA (3 anti-GPI Abs- positive and 3 anti-GPI Abs- negative) and compared histologically and immunohistochemically for IgG and C3 deposition. IgG fractions were separated from the sera of anti-GPI Abs-positive RA patients and healthy subjects, and injected into the metacarpophalangeal joints of 4 cynomolgus monkeys. On day 16, the joints were harvested and examined histologically and immunohistochemically. The expression of the C5a receptor (C5aR) molecule in the synovium was quantified by real-time PCR using cDNA from the monkeys' joints. The synovia of anti-GPI Abs-positive RA patients showed diffuse infiltration of cells, including mast cells, and strong deposition of IgG and C3. In monkeys, IgG from RA patients, including anti-GPI Abs, resulted in recruitment of granulocytes and mononuclear cells, strong deposition of IgG on the articular surface, and overexpression of C5aR, but no joint swelling. No infiltrated cells or IgG deposition were observed in monkeys injected with IgGs from healthy subjects. Our results suggest that IgG fraction from RA patients, including that of anti-GPI Abs, may play a role in the synovitis of RA, although the pathogenesis of human anti-GPI Abs is still uncertain.
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PMID:The exploration of joint-specific immunoreactions on immunoglobulins G of anti-glucose-6-phosphate isomerase antibody-positive patients with rheumatoid arthritis. 1621 Dec 46

Anti-glucose-6-phosphate isomerase (GPI) antibodies are known to be arthritogenic autoantibodies in K/BxN mice, although some groups have reported that few healthy humans retain these antibodies. The expression of Fcgamma receptors (FcgammaRs) is genetically regulated and has strong implications for the development of experimental arthritis. The interaction between immune complexes and FcgammaRs might therefore be involved in the pathogenesis of some arthritic conditions. To explore the relationship between functional polymorphisms in FcgammaRs (FCGR3A-158V/F and FCGR2A-131H/R) and arthritis in individuals positive for anti-GPI antibodies, we evaluated these individuals with respect to FCGR genotype. Genotyping for FCGR3A-158V/F and FCGR2A-131H/R was performed by PCR amplification of the polymorphic site, followed by site specific restriction digestion using the genome of 187 Japanese patients with rheumatoid arthritis (including 23 who were anti-GPI antibody positive) and 158 Japanese healthy individuals (including nine who were anti-GPI antibody positive). We report here on the association of FCGR3A-158V/F functional polymorphism with anti-GPI antibody positive status. Eight out of nine healthy individuals who were positive for anti-GPI antibodies possessed the homozygous, low affinity genotype FCGR3A-158F (odds ratio = 0.09, 95% confidence interval 0.01-0.89; P = 0.0199), and probably were 'protected' from arthritogenic antibodies. Moreover, among those who were homozygous for the high affinity genotype FCGR3A-158V/V, there were clear differences in anti-human and anti-rabbit GPI titres between patients with rheumatoid arthritis and healthy subjects (P = 0.0027 and P = 0.0015, respectively). Our findings provide a molecular model of the genetic regulation of autoantibody-induced arthritis by allele-specific affinity of the FcgammaRs.
Arthritis Res Ther 2005
PMID:A functional variant of Fcgamma receptor IIIA is associated with rheumatoid arthritis in individuals who are positive for anti-glucose-6-phosphate isomerase antibodies. 1627 70


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