T-cell studies in the spondyloarthropathies

Association Between Protein Tyrosine Phosphatase Non-Receptor Type 22 (PTPN22) Polymorphisms and Risk of Ankylosing Spondylitis: A Meta-analysis

Background

Ankylosing spondylitis (AS) is a chronic autoimmune disease that involves the imbalance of peripheral tolerance possibly caused by the negative signal of activated T cells. The polymorphisms in the human protein tyrosine phosphatase non-receptor type 22 (PTPN22) gene have been pointed out to be related to the pathogenesis of AS, but conclusions over this issue remain contradictory. We attempted to give a more precise conclusion about the effects of PTPN22 polymorphisms on AS risk by means of a meta-analysis.

Material/Methods

PubMed, Embase, Wanfang, and Chinese National Knowledge Infrastructure (CNKI) were searched for relevant studies published in the English or Chinese language. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated with a fixed- or random-effects model to evaluate the correlation between PTPN22 rs2488457, rs1217414, and rs2476601 polymorphisms and AS susceptibility. Sensitivity analysis was also carried out to detect the stability of the results.

Results

The present meta-analysis showed a positive correlation of both PTPN22 rs2488457 and rs1217414 polymorphisms with AS risk under CC vs. GG, CC + GC vs. GG, CC vs. GC + GG, allele C vs. allele G (OR=1.39, 95% CI=1.04–1.85, P=0.646; OR=1.29, 95% CI=1.03–1.62, P=0.426; OR=1.26, 95% CI=1.02–1.56, P=0.971; OR=1.20, 95% CI=1.05–1.38, P=0.571), and TT vs. CC and TT vs. CT + CC models (OR=3.83, 95% CI=1.11–13.24, P=0.196; OR=3.83, 95% CI=1.09–13.42, P=0.244), respectively.

Conclusions

PTPN22 rs2488457 and rs1217414 polymorphisms may be risk factors for AS occurrence.

Analyses of immunosenescent markers in patients with autoimmune disease

The objective of this study was to evaluate the degree of immunosenescence in patients with autoimmune disease. T cell receptor excision circles (TREC) and the percentage of CD4+CD28null T cells were studied as markers of immunosenescence in 175 patients with chronic autoimmune arthritis, other connective tissue autoimmune diseases, multiple sclerosis and 60 healthy controls. In both the rheumatoid arthritis (RA) and multiple sclerosis patient group, TREC numbers were age-inappropriately declined which points to an accelerated thymic output. Furthermore, enhanced percentages of CD4+CD28null T cells could be detected in a significant proportion of patients included in this study. These immunosenescent phenomena seemed to be present already early in the disease process. High percentages of CD4+CD28null T cells were associated with the presence of RA linked HLA DR4 alleles and with plasma reactivity to cytomegalovirus. Further analysis of CD4+CD28null T cells provided indications for a restricted T cell receptor (TCR) BV gene expression and cytoplasmic stores of various cytotoxic molecules. This study indicates that the immune system of patients with autoimmune diseases shows signs of an accelerated aging. Both genetic factors, such as HLA DR4, and environmental factors, like CMV infection, might speed up this immunosenescence and contribute in this way to disease pathogenesis.

Contribution of TNFα, IL-1β and CINC-1 for articular incapacitation, edema and cell migration in a model of LPS-induced reactive arthritis

The protective effect of anti-CINC-1, -TNFalpha and -IL-1beta antisera on articular inflammatory incapacitation, articular diameter and synovial fluid cell content, which are correlated to nociception, edema and cell migration, respectively, were evaluated in a rat model of LPS-induced reactive arthritis. In this model, Escherichia coli lipopolysaccharide (LPS; 30 ng) was injected in a knee-joint previously primed with carrageenan (300 microg). Articular incapacitation was evaluated hourly by the automated registering of the knee-joint function during animal walking, and the knee-joint edema was evaluated by measuring the articular diameter increase. After 6 h, the animals were euthanized for collecting synovial fluid for the evaluation of cell migration. LPS produced dose-dependent incapacitation and edema. Anti-TNFalpha, -IL-1beta, and -CINC-1 antisera (20 and 40 microl) were used as pretreatment into knee-joint before LPS injection. At higher dose, Anti-TNFalpha and anti-CINC-1 were able to inhibit incapacitation, articular edema and mononuclear (MON) migration. Anti-IL1beta did not affect incapacitation at any dose, although inhibited edema and cell migration. Surprisingly, the higher dose of anti-IL1beta antisera did not inhibit cell migration, although inhibited articular edema. These findings corroborate the role TNFalpha has in different forms of arthritis, but points out the idea that CINC-1 (the homologue for human IL-8) may constitute a promising target for reactive arthritis management. Indeed, the potent antiedematogenic effect, and principally the anti-migration effect of anti-CINC-1, raises the possibility of a better control of disease progression than with anti-IL-1beta therapies.

Mechanisms of bone resorption and new bone formation in spondyloarthropathies

Spondyloarthropathies (SpA) share clinical features such as sacroiliitis, axial immobility, and peripheral arthropathies. They also share a strong association with human leukocyte antigen-B27, implicating T cells and antigen-presenting cells in the disease process. Inflammation seems to underlie the pathogenesis of SpA, particularly in the axial skeleton and entheses. Pathologic bone loss and formation occur simultaneously in inflamed regions, suggesting an inflammation-induced dysregulation of osteoclast and osteoblast activity. Pro-inflammatory cytokines such as tumor necrosis factor-alpha (TNFa) appear to be central to the disease, because TNFa blockade has been shown to effectively improve clinical outcome. Other cytokines such as transforming growth factor-beta, interferon-gamma (IFNg), and interleukin-18 are also likely to be important in SpA. Activated T cells have been shown to produce cytokines such as IFNg and receptor activator of nuclear-factor- kappaB ligand, with direct effects on osteoclastogenesis. The dual role of T cells in immunobiology and skeletal biology provides a possible link between human leukocyte antigen-B27, pro-inflammatory cytokines, and bone cells in SpA.

Proinflammatory responses to self HLA epitopes are triggered by molecular mimicry to Epstein-Barr virus proteins in oligoarticular juvenile idiopathic arthritis

OBJECTIVE

To evaluate whether abnormal T cell recognition may be generated by exposure to exogenous antigens presenting sequence homology with epitopes contained in self HLA alleles, and if such recognition may be part of the mechanisms that fuel inflammation in autoimmune diseases associated with certain HLA alleles.

METHODS

Cytotoxic responses of peripheral blood mononuclear cells to 9-mer peptides derived from HLA molecules (DRB1*1101, DRB1*0801, or DPB1*0201) associated with oligoarticular juvenile idiopathic arthritis (JIA) or homologous peptides derived from Epstein-Barr virus (EBV) proteins (Bolf1 or Balf2) were analyzed in patients with oligoarticular JIA and in healthy controls matched for HLA-DRB1*1101, DRB1*0801, or DPB1*0201. Production of proinflammatory cytokines in culture supernatants was determined by enzyme-linked immunosorbent assay.

RESULTS

T cell cytotoxic responses and production of proinflammatory cytokines in response to stimulation with self HLA-derived peptides were found only in patients with oligoarticular JIA, and not in controls. Patients with oligoarticular JIA, but none of the healthy controls, had EBV-self HLA cross-reactive T cells.

CONCLUSION

Our data suggest a disease- and allele-specific mechanism of autoimmunity in oligoarticular JIA. This mechanism may be part of the pathogenesis of the disease, and could be the basis of one of the likely multiple candidates for antigen-specific immunotherapy approaches in the future.

Pathways of cell activation in spondyloarthropathies

The initiating event in cell activation is unknown in most autoimmune diseases. The role of infection is clear in some cases, especially in reactive arthritis; however, there is little evidence of a specific organism in other spondyloarthropathies. Common pathways of cell-cell interaction and activation manifest in inflammation, but subtle differences may exist. The presence of T cells, macrophages, and B-lymphocytes suggest an autoimmune mechanism; the arthritogenic peptide theory has been proposed. Furthermore, the association of spondyloarthropathies with HLA-B27 suggests it may be important in synovial T-cell activation. Other cell types involved in the process of bone and cartilage destruction, including fibroblasts and osteoclasts, may also be activated. Endothelial activation and angiogenesis may be a critical primary event in these diseases. Finally, trauma (physical or psychological) in the form of stress may be an important factor; the nervous system and neuropeptides may play a role in cell activation and initiation of arthritis.

Insights into the Role of Infection in the Spondyloarthropathies

Certain infections play an important role in the pathogenesis of the human leukocyte antigen (HLA)-B27-associated reactive arthritis. Whether infections play a role in other forms of spondyloarthropathies is not as clear. The role of HLA-B27 as an antigen-presenting molecule is important in the pathogenesis of these diseases. Recent evidence has been obtained indicating that this molecule may have other functions unrelated to antigen-presentation in the interaction of reactive arthritis-triggering microbes and host. This paper reviews the recent studies on the role of infection in the spondyloarthropathies.

Psoriatic arthritis: clinical aspects, genetics, and the role of T cells

In the last 2 years there has been considerable progress in investigating the genetic and immunologic background of psoriasis and psoriatic arthritis. This review focuses on genetics and the role of T-cells in the immunopathogenesis of the disease, with particular reference to psoriatic arthritis.