Intravenous tolerization with type II collagen induces interleukin-4-and interleukin-10-producing CD4+ T cells

Systemic Administration of Proteoglycan Protects BALB/c Retired Breeder Mice from Experimental Arthritis

This study was undertaken to evaluate the prophylactic potential of proteoglycan (PG) administration in experimental arthritis. Female BALB/c retired breeder mice received two (2xPG50 and 2xPG100 groups) or three (3xPG50 group) intraperitoneal doses of bovine PG (50 μg or 100 μg) every three days. A week later the animals were submitted to arthritis induction by immunization with three i.p. doses of bovine PG associated with dimethyldioctadecylammonium bromide adjuvant at intervals of 21 days. Disease severity was daily assessed after the third dose by score evaluation. The 3xPG50 group showed significant reduction in prevalence and clinical scores. This protective effect was associated with lower production of IFN-γ and IL-17 and increased production of IL-5 and IL-10 by spleen cells restimulated in vitro with PG. Even though previous PG administration restrained dendritic cells maturation this procedure did not alter the frequency of regulatory Foxp3⁺ T cells. Lower TNF-α and IL-6 levels and higher expression of ROR-γ and GATA-3 were detected in the paws of protected animals. A delayed-type hypersensitivity reaction confirmed specific tolerance induction. Taken together, these results indicate that previous PG inoculation determines a specific tolerogenic effect that is able to decrease severity of subsequently induced arthritis.

Functional Mechanism(s) of the Inhibition of Disease Progression by Combination Treatment with Fingolimod Plus Pathogenic Antigen in a Glucose-6-phosphate Isomerase Peptide-Induced Arthritis Mouse Model

We previously reported that combination treatment with fingolimod (FTY720) plus antigenic peptide of glucose-6-phosphate isomerase (residues 325-339) (GPI325-339) from the onset of symptoms significantly inhibited disease progression in a mouse model of GPI325-339-induced arthritis. In this study, we investigated the mechanism(s) involved. The model mice were treated from arthritis onset with FTY720 alone, GPI325-339 alone, or the combination of FTY720 plus GPI325-339. At the end of treatment, inguinal lymph nodes (LNs) were excised and examined histologically and in flow cytometry. Levels of apoptotic cells, programmed death-1-expressing CD4(+)forkhead box P3(-) nonregulatory T cells (non-Tregs), and cytotoxic T-lymphocyte antigen 4-expressing non-Tregs in inguinal LNs were markedly increased in the combination treatment group mice. Regulatory T cells (Tregs) were also increased. These results indicate that combination treatment with FTY720 plus GPI325-339 inhibits the progression of arthritis by inducing clonal deletion and anergy of pathogenic T cells and also by immune suppression via Tregs.

Red blood cells as innovative antigen carrier to induce specific immune tolerance

The route of administration, the dose of antigen as well as the type of antigen-presenting cells (APCs) targeted are important factors to induce immune tolerance. Despite encouraging results obtained in animal models, intravenous injection of soluble antigen is unsuccessful in human clinical trials on autoimmune disease due to inefficient antigen delivery. To improve antigen delivery, we used mouse red blood cells (RBCs) as antigen vehicles to specifically target APCs which are responsible for removal of senescent RBCs after phagocytosis. In this study, we demonstrated that antigen-delivery by RBCs induced a strong decrease in the humoral response compared with the ovalbumin (OVA) free form in mice. In addition, OVA-loaded RBC treated with [bis(sulphosuccinimidyl)] suberate (BS3), a chemical compound known to enhance RBC phagocytosis, induced an inhibition of antigen-specific T cell responses and an increase in the percentage of regulatory T cells. The state of tolerance induced is long lasting, antigen-specific and sufficiently robust to withstand immunization with antigen mixed with cholera toxin adjuvant. This RBC strategy, which does not abolish the immune system, constitutes an attractive approach for induction of tolerance compared to systemic immunosuppressant therapies already in use.

The splenic response to ischemic stroke: what have we learned from rodent models?

The majority of promising experimental compounds have failed in clinical trials, highlighting the need for novel approaches to treat stroke. Much research has been devoted to elucidating the signaling pathways involved in delayed neuroinflammation that can be targeted at clinically relevant time points. The field of stroke research has benefited from experiments characterizing the temporal expression profiles of candidate cytokines, chemokines, matrix metalloproteinases, and other putative pro-inflammatory molecules. Yet, these data have offered only a glimpse into the complex pathological sequelae and have not advanced the treatment of neuropathies. Upon recognition that peripheral immune cell activation is involved in penumbral expansion, the spleen has emerged as a novel target that mediates the peripheral immune response and promotes pro-inflammatory injury. Although the precise mechanisms have yet to be elucidated, accumulated evidence demonstrates that focal cerebral ischemia alters cytokine, chemokine, and immune cell profiles in the spleen. Additionally, removal of this peripheral lymphoid organ is neuroprotective, and the efficacy of several protective therapies has been linked to actions at the level of the spleen. Future experiments aimed at identifying the splenic lymphocyte populations that respond to ischemic stroke, as well as their signaling mechanisms, are critical in developing novel therapies.

Emerging opportunities for site-specific molecular and cellular interventions in autoimmune hepatitis

Current corticosteroid-based treatments of autoimmune hepatitis frequently have incomplete or unsatisfactory outcomes, side effects, and excessive immune suppression. The goal of this review is to describe the advances in developing animal models of autoimmune hepatitis and in treating diverse immune-mediated diseases that make pursuit of site-specific molecular and cellular inventions in autoimmune hepatitis feasible. Prime source and review articles in English were selected by a Medline search through October 2009. A murine model infected with an adenovirus expressing human CYP2D6 is a resource for evaluating new therapies because of its histological and serological features, persistence, and progressive hepatic fibrosis. Synthetic analog peptides that block autoantigen expression, a dimeric recombinant human fusion protein of cytotoxic T lymphocyte antigen-4, monoclonal antibodies against tumor necrosis factor-alpha, recombinant interleukin 10, tolerization techniques for disease-triggering autoantigens, T regulatory cell transfer, vaccination against antigen-specific cytotoxic CD8+ T cells, and gene silencing methods using small inhibitory RNAs are feasible interventions to explore. Treatments directed at dampening immunocyte activation with soluble cytotoxic T lymphocyte antigen-4, inhibiting immunocyte differentiation with recombinant interleukin 10, and improving immunosuppressive activity with regulatory T cell modulation have the most immediate promise. Progress in the development of an animal model of autoimmune hepatitis and experiences in other immune-mediated diseases justify the evaluation of site-specific molecular and cellular interventions in this disease.

Antigen-specific tolerogenic and immunomodulatory strategies for the treatment of autoimmune arthritis

OBJECTIVES

To review various antigen-specific tolerogenic and immunomodulatory approaches for arthritis in animal models and patients in regard to their efficacy, mechanisms of action, and limitations.

METHODS

We reviewed the published literature in Medline (PubMed) on the induction of antigen-specific tolerance and its effect on autoimmune arthritis, as well as the recent work on B-cell-mediated tolerance from our laboratory. The prominent key words used in different combinations included arthritis, autoimmunity, immunotherapy, innate immunity, tolerance, treatment, and rheumatoid arthritis (RA). Although this search spanned the years 1975 to 2007, the majority of the short-listed articles belonged to the period 1990 to 2007. The relevant primary as well as cross-referenced articles were then collected from links within PubMed and reviewed.

RESULTS

Antigen-specific tolerance has been successful in the prevention and/or treatment of arthritis in animal models. The administration of soluble native antigen or an altered peptide ligand intravenously, orally, or nasally, and the delivery of the DNA encoding a particular antigen by gene therapy have been the mainstay of immunomodulation. Recently, the methods for in vitro expansion of CD4+CD25+ regulatory T-cells have been optimized. Furthermore, interleukin-17 has emerged as a promising new therapeutic target in arthritis. However, in RA patients, non-antigen-specific therapeutic approaches have been much more successful than antigen-specific tolerogenic regimens.

CONCLUSION

An antigen-specific treatment against autoimmune arthritis is still elusive. However, insights into newly emerging mechanisms of disease pathogenesis provide hope for the development of effective and safe immunotherapeutic strategies in the near future.

Rosmarinic acid induces apoptosis of activated T cells from rheumatoid arthritis patients via mitochondrial pathway

T cells play an important role in the initiation and the progression of rheumatoid arthritis (RA) and depletion of potentially pathogenic T cells was suggested as an important therapeutic protocol. We determined if rosmarinic acid (RosA), known as a secondary metabolite from herbal plants, had apoptotic activity toward T cells from RA patients and further verified target T-cell subsets. CD3(+)CD25(+) activated T-cell subsets from most of the RA patients displayed significantly higher apoptosis rates than did the PBMCs and total CD3(+) T cells. Furthermore, activated and effector CD4(+) T cells, including CD4(+)CD25(+) and CD4(+)CD45RO(+) T cells, had a tendency of being more susceptible to RosA-induced apoptosis than that of resting and naïve T-cell subsets. RosA induced the release of cytochrome c from mitochondria and the blockage of mitochondrial depolarization inhibited apoptosis. Taken together, these results suggest that RosA induces apoptosis of activated T-cell subsets from RA patients via a mitochondrial pathway.

Induction of Bystander Suppression by Feeding Antigen Occurs despite Normal Clonal Expansion of the Bystander T Cell Population

The induction of bystander suppression, whereby the response against one Ag is suppressed when it is presented in the context of an Ag to which tolerance is already established, would be an important property of oral tolerance, because it would allow treatment of autoimmune and hypersensitivity responses where the initiating Ag is not known. Although bystander suppression has been described in oral tolerance, it is not known how its effects are mediated at the level of the bystander T cells. In addition, previous studies have not compared regimes in which Ag is fed in a tolerogenic or immunogenic manner, meaning that the possible effects of Ag competition have not been excluded. In this study we have used two populations of Ag-specific TCR transgenic CD4(+) T cells to examine the cellular basis of bystander suppression associated with oral tolerance in mice in vitro and in vivo. Our results show that bystander responses can be inhibited by feeding Ag and that these effects are more pronounced in mice fed protein in tolerogenic form than after feeding Ag with mucosal adjuvant. However, the expansion of the bystander-specific CD4(+) T cells is not influenced by the presence of oral tolerance. Thus, bystander suppression does not reflect clonal deletion or reduced clonal expansion of the bystander T cells, but may act by altering the functional differentiation of bystander T cells.

Intravenous Injection of a D1 Protein of the Smith Proteins Postpones Murine Lupus and Induces Type 1 Regulatory T Cells

T cells that recognize nucleoproteins are required for the production of anti-dsDNA Abs involved in lupus development. SmD1 83-119 (a D1 protein of the Smith (Sm) proteins, part of small nuclear ribonucleoprotein) was recently shown to provide T cell help to anti-dsDNA Abs in the NZB/NZW model of lupus. Using this model in the present study, we showed that high dose tolerance to SmD1 (600-1000 microg i.v. of SmD1(83-119) peptide/mo) delays the production of autoantibodies, postpones the onset of lupus nephritis as confirmed by histology, and prolongs survival. Tolerance to SmD1 83-119 was adoptively transferred by CD90+ T cells, which also reduce T cell help for autoreactive B cells in vitro. One week after SmD1 83-119 tolerance induction in prenephritic mice, we detected cytokine changes in cultures of CD90+ T and B220+ B cells with decreased IFN-gamma and IL-4 expression and an increase in TGFbeta. Increased frequencies of regulatory IFN-gamma+ and IL10+ CD4+ T cells were later detected. Such regulatory IL-10+/IFN-gamma+ type 1 regulatory T cells prevented autoantibody generation and anti-CD3-induced proliferation of naive T cells. In conclusion, these results indicate that SmD1 83-119 peptide may play a dominant role in the activation of helper and regulatory T cells that influence autoantibody generation and murine lupus.

Single immunization of newborn mice with heterologous type-II collagen induces arthritic disease

Collagen-induced arthritis (CIA) is a widely accepted model of autoimmune disease with significant similarities to rheumatoid arthritis in humans. CIA is provoked in susceptible strains upon immunization of adult mice with native type-II collagen in complete Freund's adjuvant (CFA). Neonatal exposure to antigen is supposed to result in T cell clone deletion and induction of tolerance. Here we report that the neonatal injection of bovine type-II collagen (bCII) to ICR (CD-2) mice triggers the development of autoimmune chronic joint inflammation. Compared with standard CIA significant joint swelling was not observed and anti-collagen antibodies were not detected if the second challenge with the antigen was not supplied. Histopathologic examination of the joints showed cell infiltration, synovial hyperplasia and at the later period bone destruction. Mice immunized as neonates expressed Ag-specific proliferative response and delayed type hypersensitivity (DTH) reaction to bCII.

FcgammaRI up-regulation induced by local adenoviral-mediated interferon-gamma production aggravates chondrocyte death during immune complex-mediated arthritis

Using various FcgammaR-deficient mice, we have obtained suggestive evidence that FcgammaRI on macrophages is responsible for severe cartilage destruction during arthritis mediated by immune complexes (ICs). This role of FcgammaRI is pronounced in the presence of activated Th1 cells and a likely Th1 cell-derived cytokine mediating up-regulation of FcgammaRI expression is interferon (IFN)-gamma. We now investigated whether local overexpression of IFN-gamma using an adenoviral vector is able to elevate cartilage destruction during experimental immune complex-mediated arthritis (ICA) and to what extent this process is FcgammaRI-mediated. IFN-gamma overexpression during ICA had no significant effect on the total cell mass infiltrating the knee joint. However, a higher percentage of macrophages expressing markers for a proinflammatory phenotype was found and these macrophages were situated in close proximity of the cartilage surface. Interestingly, cartilage destruction as studied by matrix metalloproteinase (MMP)-mediated proteoglycan damage (VDIPEN expression), chondrocyte death, and erosion was significantly increased. This effect of IFN-gamma was only found in the presence of ICs, as IFN-gamma overexpression during zymosan-induced arthritis, which is not IC-dependent, did not lead to severe cartilage destruction. These results imply a crucial role for ICs and the IgG-binding receptors in the aggravation of cartilage damage by IFN-gamma. Local overexpression of IFN-gamma induced increased FcgammaRI mRNA levels in synovium. To study whether this up-regulation of FcgammaRI mediates aggravation of cartilage destruction, ICA was raised in FcgammaRI(-/-) and their wild-type controls. IFN-gamma resulted in elevated VDIPEN expression, which was still present in FcgammaRI(-/-). Of great interest, chondrocyte death remained low in FcgammaRI(-/-). These results indicate that IFN-gamma overexpression deteriorates cartilage destruction in the presence of ICs and that FcgammaRI is crucial in the development of chondrocyte death.

Antigen inhibition of collagen-induced arthritis is associated with up-regulation of IL-4 mRNA and induction of Ox40 on T cells in draining lymph nodes

The addition of a foreign antigen to an inoculum completely inhibits the development of collagen-induced arthritis (CIA). However, the mechanism of this phenomenon, antigen -inhibition, is incompletely understood. Previous studies have demonstrated that the inhibition of arthritis is not mediated through suppression of the antibody response to cartilage antigens. In this paper we investigated cytokine mRNA levels in lymph nodes cells recovered 3, 7 or 16 days from animals immunized with either collagen II in IFA or OVA + collagen II in IFA. At day 7, but not at other time-points, IL-4 mRNA was up-regulated in the lymph nodes of OVA-inhibited non-arthritic animals compared to control animals which all developed arthritis. No significant differences between the two groups could be detected when expression of IFN-gamma, IL-2, TNF-alpha, IL-1beta or IL-10 mRNA was analysed. Flow cytometry analysis of draining lymph node cells demonstrated that the T cell marker Ox40 was up-regulated in the OVA-inhibited group. Our results indicate that the complete inhibition of CIA caused by addition of OVA to the collagen II inoculum is due to the presence of a TH2 environment resulting from an increased production of IL-4 mRNA and a parallel increase in Ox40+ T cells.

Depletion of collagen II-reactive T cells and blocking of B cell activation prevents collagen II-induced arthritis in DBA/1j mice

Collagen II (CII)-induced arthritis in DBA/1j mice is mediated by both CII-reactive T cells and anti-CII Ab-producing B cells. To determine the relative role of these processes in the development of arthritis, we specifically eliminated CII-reactive T cells by treating the mice with CII-pulsed syngeneic macrophages that had been transfected with a binary adenovirus system. These macrophages express murine Fas ligand in a doxycycline-inducible manner with autocrine suicide inhibited by concomitant expression of p35. The mice were treated i.v. with four doses of CII-APC-AdFasLp35Tet or a single dose of AdCMVsTACI (5 x 10(9) PFU), or both simultaneously, beginning 2 wk after priming with CII in CFA. Treatment with CII-APC-AdFasLp35Tet alone or in combination with a single dose of AdCMVsTACI prevented the development of CII-induced arthritis and T cell infiltration in the joint. The elimination of T cells was specific in that a normal T cell response was observed on stimulation with OVA after treatment with CII-APC-AdFasLp35Tet. Treatment with AdCMVsTACI alone prevented production of detectable levels of circulating anti-CII autoantibodies and reduced the severity of arthritis but did not prevent its development. These results indicate that the CII-reactive T cells play a crucial role in the development of CII-induced arthritis and that the anti-CII Abs act to enhance the development of CII-induced arthritis.

Immunogenicity of recombinant type IX collagen in murine collagen-induced arthritis

OBJECTIVE

Past attempts to isolate type IX collagen (CIX) from cartilage using limited proteolysis yielded partially degraded material. Recent application of recombinant technology, however, has allowed the preparation of intact native CIX. We used the murine collagen-induced arthritis model to characterize the immunologic properties of recombinant human CIX (rCIX) produced using a baculovirus expression system.

METHODS

A panel of B10 congenic mice was immunized with rCIX emulsified with Freund's complete adjuvant (CFA). The ability of the rCIX to induce tolerance and suppress arthritis was determined by administration intravenously or orally before challenge with CII/CFA.

RESULTS

None of the mice immunized with rCIX developed overt arthritis, although 2 of 5 HLA-DR1 transgenic mice developed limited digital erythema and swelling. Recombinant CIX administered by either route effectively induced suppression of arthritis, although the suppression was less pronounced than that induced with CII. Immune responses to CIX and CII were specific, suggesting that bystander suppression, rather than cross-reactivity with CII, was instrumental in suppressing arthritis.

CONCLUSION

These data show that CIX down-regulates arthritis in mice while having no associated risk of inducing arthritis.

The role of IL-12 in the induction of intravenous tolerance in experimental autoimmune encephalomyelitis

Intravenous administration of autoantigen is an effective method to induce Ag-specific tolerance against experimental autoimmune encephalomyelitis (EAE). IL-12 is a potent Th1 stimulator and an essential cytokine in the induction of EAE. The role of IL-12 in the induction of i.v. tolerance is not clear. In this study, we induced tolerance by i.v. administering myelin basic protein (MBP) peptide Ac1-11 (MBP1-11) in EAE. We observed significant suppression of IL-12 production by the lymph node cells of MBP1-11-injected mice. To see whether the low level of IL-12 is the cause or effect of tolerance, we administered IL-12 to the EAE mice at the time of i.v. MBP1-11 injection. Exogenous IL-12 abrogated the suppression of clinical and pathological EAE by i.v. tolerance. IL-12 blocked the suppressive effect of i.v. tolerance on the proliferative response to MBP1-11 and MBP1-11-induced production of IL-12 and IFN-gamma. Furthermore, IL-12 completely blocked the i.v. tolerance-induced type 1 T regulatory cell response. These data suggest that i.v. administration of autoantigen results in the suppression of endogenous IL-12 and the consequent switching of the immune response from an immunogenic to a tolerogenic form.

Constitutive expression of BCL-X(L) in the T lineage attenuates collagen-induced arthritis in Bcl-X(L) transgenic mice

OBJECTIVE

To determine if inhibition of T cell apoptosis through constitutive expression of Bcl-X(L) in the T lineage influences inflammatory arthritis in the mouse collagen-induced arthritis (CIA) model.

METHODS

The incidence and severity of arthritis were quantified in Bcl-X(L) transgenic mice and nontransgenic littermates after immunization with type II collagen (CII). To correlate T cell responses with disease phenotype, antigen-specific T cell proliferation was measured by (3)H-thymidine incorporation. Apoptosis and cell cycle progression were analyzed by flow cytometry using propidium iodide. Production of CII-specific interferon-gamma (IFNgamma), interleukin-5 (IL-5), and IL-10 was determined by enzyme-linked immunosorbent assay.

RESULTS

Disease severity in CIA was significantly attenuated in Bcl-X(L) transgenic mice compared with their nontransgenic littermates. Inhibition of CIA was associated with decreased T cell apoptosis, delayed cell cycle progression, and reduced IFNgamma production.

CONCLUSION

Rather than promoting inflammation, inhibition of apoptosis by expression of the Bcl-X(L) protein in the T lineage attenuates disease progression in CIA, probably through inhibition of IFNgamma production.

The role of IL-4 in regulation of murine collagen-induced arthritis

Collagen-induced arthritis (CIA) is a murine model of autoimmune-mediated polyarthritis. CIA can be prevented by the administration (intravenously) of CII, inducing regulatory CD4+ T cells which produce Th2 cytokines. However, the relative importance of IL-4 in suppressing arthritis remains unclear. To address this question, a neutralizing monoclonal antibody to IL-4 was given to mice treated with tolerized, CII-specific cells. The antibody significantly reversed the expected suppression of arthritis. Moreover, CII administered intravenously to DBA/1 IL4-/- mice (developed by backcrossing C57B1/6 IL4-/- to wild-type DBA/1 mice) was completely ineffective in suppressing disease. These data support the importance of IL-4 in the regulation of autoimmune arthritis. Compensatory increases in mRNA message for other Th2 cytokines were observed, but they did not restore suppression of arthritis. Antibodies to CII, mostly IgG2a, were increased in IL4-/- mice. These studies represent a unique opportunity to analyze the role of IL-4 and its absence on an autoimmune murine model of arthritis.

Role of glycopeptide-specific T cells in collagen-induced arthritis: an example how post-translational modification of proteins may be involved in autoimmune disease

Immunization of mice with type II collagen (CII), a cartilage-restricted protein, leads to collagen-induced arthritis (CIA), a model for rheumatoid arthritis (RA). CIA symptoms consist of an erosive joint inflammation caused by an autoimmune attack, mediated by both T and B lymphocytes. CD4+ alphabeta T cells play a central role in CIA, both by helping B cells to produce anti-CII antibodies, and by interacting with other cells in the joints, eg macrophages. In H-2q mice, most CII-specific CD4+ T cells recognize the CII(256-270) peptide presented on the major histocompatibility complex (MHC) class II Aq molecule. Post-translational modifications (hydroxylation and variable glycosylation) of the lysine residue at position 264 of CII generate at least four different T-cell determinants that are specifically recognized by distinct T-cell subsets. Most T cells recognize CII(256-270) glycosylated with the monosaccharide galactose, which is consequently immunodominant in CIA. Recent studies indicate that the arthritogenic T cells in CIA are glycopeptide-specific, suggesting that induction of self-tolerance may be rendered more difficult by glycosylation of CII. These data open the possibility that outoimmune disease may be caused by the creation of new epitopes by posttranslational modification of proteins under circumstances such as trauma, inflammation or ageing.

The immune tolerance network and rheumatic disease: immune tolerance comes to the clinic

The development of effective, new, biologically based therapies for RA has created real excitement and justifiable optimism in recent years among rheumatologists and among patients with rheumatic diseases. Recent advances in our understanding of the mechanisms of immune activation and immune tolerance provide further cause for optimism. Against this background, the establishment of the ITN is an important step. However, significant hurdles remain to be cleared. First, despite dramatic scientific progress, restoration of immune tolerance in the face of an established autoimmune response is still an elusive goal, even in the laboratory. Not only does the ITN face this fundamental scientific challenge, but it also faces daunting practical and political challenges. For example, can the ITN influence the research agenda of the pharmaceutical and biotechnology industries? This question and other important questions will only be answered as the ITN matures. Autoimmune disease, although individually uncommon, affects more than 2% of Americans. The rheumatologist is especially aware of the devastating potential of autoimmune diseases. If the ITN succeeds in linking basic research into the mechanisms of autoimmunity with clinical trials of promising new therapies, it can be expected to play a critical role in advancing the practice of clinical rheumatology.

Redirection of T cell effector function in vivo and enhanced collagen-induced arthritis mediated by an IL-2R beta/IL-4R alpha chimeric cytokine receptor transgene

Chronic inflammatory autoimmune diseases such as diabetes, experimental autoimmune encephalomyelitis, and collagen-induced arthritis (CIA) are associated with type 1 (Th1, Tc1) T cell-dependent responses against autoantigens. Immune deviation toward type 2 (Th2, Tc2) response has been proposed as a potential means of gene therapy or immunomodulation to treat autoimmune diseases based on evidence that type 2 cytokines can prevent or alleviate these conditions. In this report we assessed the effects of elevated type 2 responses on CIA using transgenic mice expressing an IL-2R beta/IL-4R alpha chimeric cytokine receptor transgene specifically in T cells. In response to IL-2 binding, this chimeric receptor transduces IL-4-specific signals and dramatically enhances type 2 responses. In contrast to published reports of Th2-mediated protection, CIA was exacerbated in IL-2R beta/IL-4R alpha chimeric receptor transgenic mice, with increased disease incidence, severity, and earlier disease onset. The aggravated disease in transgenic mice was associated with an increase in type 2 cytokines (IL-4, IL-5, IL-10) and an increase in collagen-specific IgG1 levels. However, IFN-gamma production is not affected significantly in the induction phase of the disease. There is also an extensive eosinophilic infiltration in the arthritic joints of the transgenic animal, suggesting a direct contribution of type 2 response to joint inflammation. Taken together, our findings provide novel evidence that enhancement of a polyclonal type 2 response in immunocompetent hosts may exacerbate an autoimmune disease such as CIA, rather than serving a protective role. This finding raises significant caution with regard to the potential use of therapeutic approaches based on immune deviation toward type 2 responses.

Possible role of peripheral CD14low monocytes in the development of collagen-induced arthritis in cynomolgus monkeys (Macaca fascicularis)

The changes in levels of peripheral major lymphocyte subsets were monitored with 10 adult cynomolgus monkeys (5 females and 5 males) during the 9 weeks after immunization with chick type-II collagen in Freund's complete adjuvant. Three females and 3 males developed overt arthritis determined by swelling of small joints and increase of plasma alkaline phosphatase as well as C-reactive protein. An increase of CD16+ NK cells was observed in four non-arthritis-developed monkeys (two females and two males). There was no significant difference in the fluctuation pattern of CD4+ T cell, CD8+ T cell and CD20+ B cell levels between arthritis-developed monkeys and non-developed ones. In addition, the percentages of CD45RA+ CD4+ T cells to total CD4+ T cells, CD28- CD8+ T cells to total CD8+ T cells, and IgD- B cells to total B cells did not significantly differ between them. On the other hand, a significant increase was demonstrated in CD14-positive cells at 3 weeks after immunization in only arthritis-developed monkeys regardless of sex. The expression of CD14 antigen on the surface of increased cells was low in comparison with those appearing in blood obtained before immunization. In addition, increased CD14low cells showed no response to LPS stimulation. However, there was no significant difference in antibody titer to both chick type-II and monkey type-II collagen between arthritis-developed monkeys and non-developed ones. These results suggest that an increase in number of CD14low monocytes with immature function might be a part of the autoimmune response, and that the appearance of these cells is of pathogenic importance in the arthritic process in cynomolgus monkeys regardless of the production of autoantibody.

Antigen-specific therapy for autoimmune disease

The application of self-antigens as therapeutic tools is validated in inbred animal models of autoimmune disease. Mechanisms of antigen-induced tolerance (apoptosis, anergy, regulatory T cells and immune deviation) are being clarified in relation to the properties of antigens and the modes and routes of their delivery. Mucosa-mediated tolerance remains the predominant mode of antigen-specific therapy but awaits demonstration of clinical efficacy in human autoimmune disease.