Suzanne E. Berlo

The Human Endoplasmic Reticulum Molecular Chaperone BiP Is an Autoantigen for Rheumatoid Arthritis and Prevents the Induction of Experimental Arthritis

Rheumatoid arthritis (RA) is the most common, crippling human autoimmune disease. Using Western blotting and tandem mass spectroscopy, we have identified the endoplasmic reticulum chaperone BiP, a 78-kDa glucose-regulated protein, as a possible autoantigen. It preferentially stimulated increased proliferation of synovial T cells from patients with RA but not from patients with other arthritides. Mice with established collagen- or pristane-induced arthritis developed IgG Abs to BiP. Although BiP injected in CFA failed to induce arthritis in several strains of rats and mice, including HLA-DR4+/−- and HLA-DR1+/+-transgenic animals, it completely inhibited the development of arthritis when given i.v. 1 wk before the injection of type II collagen arthritis. Preimmunization with BiP suppressed the development of adjuvant arthritis in Lewis rats in a similar manner. This is the first report of a mammalian chaperone that is an autoantigen in human RA and in experimental arthritis and that can also prevent the induction of experimental arthritis. These findings may stimulate the development of new immunotherapies for the treatment of RA.

Heat shock proteins induce T cell regulation of chronic inflammation

The significance of immune responses to certain heat shock proteins (HSPs) that develop in virtually all inflammatory diseases is only now becoming clear. In experimental models, HSPs prevent or arrest inflammatory damage, and initial clinical trials in chronic inflammatory disease have shown HSP peptides to promote production of anti-inflammatory cytokines—indicating immunoregulatory potential. HSPs are ubiquitous self-antigens that are highly expressed in inflamed tissues. The prokaryotic homologous proteins, present in every bacterial species, are dominantly immunogenic. This is striking, especially as these proteins have large areas of sequence homologies with the host (mammalian) counterparts. In several experimental models of autoimmune diseases, immunisation with bacterial HSPs inhibited disease development, as did oral/nasal administration. Based on the experimental evidence so far, it is tempting to speculate that: firstly, exposure to homologues of these self-antigens, as present in, for instance, the bacterial intestinal flora, has a decisive impact on the regulation of self-tolerance at the level of T cells; and secondly, such proteins or their derivative peptides may have a role in an antigen specific immunotherapy approach involving modulation of relevant T cells, without the immediate necessity of defining disease specific autoantigens. Recent findings in experimental asthma and atherosclerosis have indicated that the field of application of such immunotherapy can be broader than just autoimmunity.

IL-10 is critically involved in mycobacterial HSP70 induced suppression of proteoglycan-induced arthritis.

Background The anti-inflammatory capacity of heat shock proteins (HSP) has been demonstrated in various animal models of inflammatory diseases and in patients. However, the mechanisms underlying this anti-inflammatory capacity are poorly understood. Therefore, the possible protective potential of HSP70 and its mechanisms were studied in proteoglycan (PG) induced arthritis (PGIA), a chronic and relapsing, T cell mediated murine model of arthritis. Methodology/Principal Findings HSP70 immunization, 10 days prior to disease induction with PG, inhibited arthritis both clinically and histologically. In addition, it significantly reduced PG-specific IgG2a but not IgG1 antibody production. Furthermore, IFN-γ and IL-10 production upon in vitro restimulation with HSP70 was indicative of the induction of an HSP70-specific T cell response in HSP70 immunized mice. Remarkably, HSP70 treatment also modulated the PG-specific T cell response, as shown by the increased production of IL-10 and IFN-γ upon in vitro PG restimulation. Moreover, it increased IL-10 mRNA expression in CD4+CD25+ cells. HSP70 vaccination did not suppress arthritis in IL-10−/− mice, indicating the crucial role of IL-10 in the protective effect. Conclusions/Significance In conclusion, a single mycobacterial HSP70 immunization can suppress inflammation and tissue damage in PGIA and results in an enhanced regulatory response as shown by the antigen-specific IL-10 production. Moreover, HSP70 induced protection is critically IL-10 dependent.

Balancing the immune system: Th1 and Th2

CD4+ T cells are subdivided into Th1 and Th2 cells. Their relative presence or activation is thought to have a regulatory effect on immune behaviour. Until recently, the relative suppression of Th1 cells by the relative increase of Th2 activities, was thought to be a main mechanism of keeping or restoring the balance in a diseased immune system. Nowadays, however, a specialised subset of regulatory T cells is held to be responsible for the main effects of securing a balanced immune system. It is possible that heat shock proteins (hsps) are relevant antigens driving such regulation. Heat shock proteins are known to be immunodominant antigens of bacteria. They are evolutionarily strongly conserved proteins present in all eukaryotic and prokaryotic cellular organisms and are upregulated by several forms of stress. Despite (the paradigm of) self tolerance, hsp-epitopes homologous to endogenous host hsp sequences have been implicated as T cell epitopes to endow cross reactive, hsp specific T cells with the capacity to regulate inflammation, such as in experimentally induced autoimmune diseases. Such T cells were found to produce regulatory cytokines like IL10, in contrast with T cells induced with other conserved microbial proteins that are not upregulated by stress. Hsps have been implicated in immune regulation not only as upregulated targets of adaptive immunity during inflammatory stress, but recently also as triggering factors for innate immunity through activation via Toll-like receptors (TLRs). Th1 cells or proinflammatory T cells are known to produce cytokines with proinflammatory activities. Therefore they are supposed to be critically involved in inflammatory conditions such as autoimmune arthritis. Th2 or helper T cells are known to produce cytokines that help B cells to become activated and to switch their class of antibody. Some of the cytokines produced by Th2 cells (IL4, IL5, IL10, and IL13) also have immune …

Cartilage proteoglycan aggrecan epitopes induce proinflammatory autoreactive T cell responses in rheumatoid arthritis and osteoarthritis

Objectives: To explore potential T-cell epitopes of the core protein of human cartilage proteoglycan aggrecan (PG) in patients with rheumatoid arthritis (RA) or osteoarthritis. Methods: Peptide-specific T-cell proliferation and cytokine/chemokine production in response to PG-specific peptides were measured in RA and osteoarthritis patients and in healthy controls. Results: Peptides representing amino acid regions 16–39 and 263–282 of PG were most frequently recognised by T cells in a subset of patients with RA or osteoarthritis. Peripheral blood mononuclear cells from these PG-reactive RA and osteoarthritis patients showed increased production of proinflammatory cytokines/chemokines in response to PG peptide stimulation. As PG p263–282 was found to show high sequence homology with Yersinia Yop protein, the corresponding bacterial (Yersinia) peptide was also tested. Remarkably, RA and osteoarthritis patients responding to the Yersinia peptide also responded to p263–282 of PG suggesting a possibility of molecular mimicry in these patients. Conclusions: These results indicate that PG-specific peptides, located in the G1 domain of PG, can induce (auto)antigenic T-cell responses in RA and osteoarthritis patients. These peptides might thus be involved in the immune pathogenesis and/or cartilage degradation in RA and osteoarthritis.

Autoantigen-Specific IL-10-Transduced T Cells Suppress Chronic Arthritis by Promoting the Endogenous Regulatory IL-10 Response

Deficient T cell regulation can be mechanistically associated with development of chronic autoimmune diseases. Therefore, combining the regulatory properties of IL-10 and the specificity of autoreactive CD4+ T cells through adoptive cellular gene transfer of IL-10 via autoantigen-specific CD4+ T cells seems an attractive approach to correct such deficient T cell regulation that avoids the risks of nonspecific immunosuppressive drugs. In this study, we studied how cartilage proteoglycan-specific CD4+ T cells transduced with an active IL-10 gene (TIL-10) may contribute to the amelioration of chronic and progressive proteoglycan-induced arthritis in BALB/c mice. TCR-transgenic proteoglycan-specific TIL-10 cells ameliorated arthritis, whereas TIL-10 cells with specificity for OVA had no effect, showing the impact of Ag-specific targeting of inflammation. Furthermore, proteoglycan-specific TIL-10 cells suppressed autoreactive proinflammatory T and B cells, as TIL-10 cells caused a reduced expression of IL-2, TNF-α, and IL-17 and a diminished proteoglycan-specific IgG2a Ab response. Moreover, proteoglycan-specific TIL-10 cells promoted IL-10 expression in recipients but did not ameliorate arthritis in IL-10-deficient mice, indicating that TIL-10 cells suppress inflammation by propagating the endogenous regulatory IL-10 response in treated recipients. This is the first demonstration that such targeted suppression of proinflammatory lymphocyte responses in chronic autoimmunity by IL-10-transduced T cells specific for a natural Ag can occur via the endogenous regulatory IL-10 response.

Stress proteins as inducers and targets of regulatory T cells in arthritis.

Immunization with microbial or mammalian stress proteins or heat-shock proteins in models of experimental autoimmunity has been observed to lead to increased disease resistance. Furthermore, such immunization has been proposed to result in the induction and expansion of T cells that suppress disease upon transfer. Comparisons of microbial heat-shock proteins with other conserved immunogenic proteins of bacterial origin have indicated a unique capacity for heat-shock proteins to induce a regulatory phenotype in T cells, such as reflected by the production of IL10. Also, studies in children with chronic arthritis have indicated that T-cell responses to heat-shock proteins are associated with a benign course of the disease and with remission. Furthermore, in patients, heat-shock-protein-(HSP-) activated T cells were shown to display regulatory phenotypes consistent with CD4+CD25+ T regulatory cells.

Cartilage proteoglycan-specific T cells as vectors of immunomodulatory biologicals in chronic proteoglycan-induced arthritis.

Systemic administration of agents that neutralize or antagonize Th1-mediated pro-inflammatory responses has been demonstrated to ameliorate inflammation in chronic autoimmune disease. However, systemic administration of such immunosuppressive biologicals causes serious side effects and has only limited success. To minimize these side effects, autoantigen-specific lymphocytes have been proposed as a carrier to deliver immunosuppressive agents to sites of inflammation. Here we studied the effects of primary cartilage proteoglycan-specific CD4+ T cells that were transduced using an efficient method of viral transduction with active genes encoding IL-1beta receptor antagonist, soluble TNF-alpha receptor-Ig, IL-4 or IL-10 in chronic proteoglycan-induced arthritis in mice. This is the first study describing such gene therapy using primary CD4+ T cells in a chronic arthritis. Moreover, the impact of proteoglycan-specific Th1, Th2 or naïve T cells was studied. Although proteoglycan-TCR transgenic CD4+ T cells can transfer arthritis to lymphopenic recipients, none of the proteoglycan-TCR transgenic T cell phenotypes that were tested induced worsening of arthritis in wild type hosts. Proteoglycan-specific T cells ameliorated arthritis when expressing the transduced IL-10 gene, and not when expressing the other transgenes/phenotypes. Although all of the tested biologicals can suppress in a wide range of different inflammatory disorders, especially IL-10 would therefore serve as a promising candidate to be used in cellular gene therapy for chronic arthritis.

HSP Reactive T Cells are Anti-Inflammatory and Disease Suppressive in Arthritic Diseases

Immune responses to certain heat-shock proteins (HSP) develop in virtually all inflammatory diseases; however, the significance of such responses is only now becoming clear. In models of experimental arthritis, HSPs can prevent or arrest inflammatory damage, and in initial clinical trials in patients with chronic inflammatory diseases, including rheumatoid arthritis, HSP peptides have been shown to promote the production of anti-inflammatory cytokines, indicating immunoregulatory potential of HSP. Heat shock proteins, also called stress-proteins, are ubiquitous self-antigens that are over-expressed in inflamed tissues. For some reason, the prokaryotic homologous proteins, present in every bacterial species, are dominantly immunogenic. This is striking, especially given the fact that these proteins have large areas of sequence homologies with the host (mammalian) counterparts. Furthermore, in experimental models of arthritis, immunisation with bacterial heat shock proteins has been seen to lead to inhibition of disease development. In addition oral or nasal administration has similarly been seen to lead to disease inhibition. Based on the experimental evidence collected, it becomes attractive to suppose that the exposure to homologues of these self antigens, as present in for instance the bacterial intestinal flora, has a decisive impact on the regulation of self tolerance at the level of T cells. If so, it becomes attractive to use such proteins or their derivative peptides for modulation of inflammation relevant T cells as an antigen specific immunotherapy approach, without the immediate necessity of defining disease specific auto-antigens