Induction and suppression of collagen-induced arthritis is dependent on distinct fcgamma receptors

Receptors for immunoglobulin (Ig)G (FcgammaRs) are important for the antibody-mediated effector functions of the immune system. FcgammaRI and FcgammaRIII trigger cell activation through a common gamma chain, whereas FcgammaRII acts as a negative regulator of antibody production and immune complex-triggered activation. Here we describe the in vivo consequences of FcgammaR deficiency in a mouse model of human rheumatoid arthritis. FcRgamma chain-deficient mice on arthritis-susceptible DBA/1 background were immunized with collagen for induction of collagen-induced arthritis. The DBA/1 mice lacking FcRgamma chain were protected from collagen-induced arthritis in contrast to wild-type mice, although both groups produced similar levels of IgG anticollagen antibodies. In comparison, DBA/1 mice lacking FcgammaRII developed an augmented IgG anticollagen response and arthritis. These observations suggest a crucial role of FcgammaRI and FcgammaRIII in triggering autoimmune arthritis.     

Passive transfer of arthritis to mice by injection of human anti-type II collagen antibody

The serum IgG fraction from a patient with seronegative rheumatoid-like arthritis which contained a high anti-type II collagen antibody titer was injected intravenously into mice susceptible to type II collagen-induced arthritis. A mild, transient, inflammatory arthritis was observed in 20 to 25% of the animals, whereas histologic signs of disease were evident in most of the injected mice. Purified human anti-type II collagen immunoglobulin injected into the knee joints of mice was also shown to induce a transient, inflammatory arthritis. Radiolabeled human anti-type II collagen IgG was shown to accumulate in the peripheral joints of mice, and the specificity of the antibody was shown to be similar to the specificity of anticollagen antibody eluted from the joints of mice with collagen-induced arthritis.     

Synergy between adjuvant arthritis and collagen-induced arthritis in rats

Adjuvant arthritis (AA) in rats is susceptible to cell-mediated passive transfer. Collagen-induced arthritis (CIA) in rats is susceptible to passive transfer with antibody to type II collagen. We report here the development of strikingly severe arthritis in Lewis rats as the result of synergy between passively transferred antibody to type II collagen from rats with CIA and concanavalin A (Con A)-stimulated lymph node or spleen cells from syngeneic rats with AA. Similar synergy was seen in rats with AA given anticollagen antibody, in rats with CIA given Con A-stimulated adjuvant spleen cells, and in rats actively immunized with CII and complete Freund's adjuvant. The synergistic process caused a very severe polyarthritis, characterized by marked swelling and erythema in all the joints of the distal extremities, with histologic and radiographic evidence of early, extensive erosion of articular cartilage. Synergy was apparent if the lymphoid cells from AA rats were given up to 1 mo after a single injection of anticollagen antibody. No synergy was seen when normal rat immunoglobulin or anti-ovalbumin antibody was substituted for anticollagen antibody, when Con A-stimulated lymphoid cells from normal rats or donors with CIA were used, or when Con A-stimulated AA lymphoid cells were irradiated before transfer. Synergy between separate immune effector mechanisms may represent a general phenomenon in the pathogenesis of inflammatory joint disease.     

Type II collagen-induced arthritis in rats. Passive transfer with serum and evidence that IgG anticollagen antibodies can cause arthritis

We have found that serum from rats with type II collagen-induced arthritis, when fractionated with 50% ammonium sulfate and concentrated, would transfer arthritis to nonimmunized recipients. The arthritis in recipients developed within 18-72 h and displayed all of the major histopathologic characteristics of the early lesion in immunized animals but was transient and less severe. Although consideration was given to the possibility that a circulating immune complex was involved, no evidence of such a complex was detected. Further fractionation of the serum yielded an IgG anticollagen antibody that was fully active in transferring disease. The antibody's reaction was inhibited by the native bovine type II collagen used for immunization of donors and the antibody strongly cross-reacted with homologous type II collage but not with denatured collagen. These studies demonstrate that arthritis in rats can be induced with anti- type II collagen antibodies and suggest that an autoimmune process is involved. Because antibodies to collagen have also been detected in human rheumatic diseases, further investigation of the characteristics of collagen antibodies capable of inducing arthritis seems warranted.     

Recombinant galectin-1 and its genetic delivery suppress collagen-induced arthritis via T cell apoptosis.

Galectin-1 (GAL-1), a member of a family of conserved beta-galactoside-binding proteins, has been shown to induce in vitro apoptosis of activated T cells and immature thymocytes. We assessed the therapeutic effects and mechanisms of action of delivery of GAL-1 in a collagen-induced arthritis model. A single injection of syngeneic DBA/1 fibroblasts engineered to secrete GAL-1 at the day of disease onset was able to abrogate clinical and histopathological manifestations of arthritis. This effect was reproduced by daily administration of recombinant GAL-1. GAL-1 treatment resulted in reduction in anticollagen immunoglobulin (Ig)G levels. The cytokine profile in draining lymph node cells and the anticollagen IgG isotypes in mice sera at the end of the treatment clearly showed inhibition of the proinflammatory response and skewing towards a type 2-polarized immune reaction. Lymph node cells from mice engaged in the gene therapy protocol increased their susceptibility to antigen-induced apoptosis. Moreover, GAL-1-expressing fibroblasts and recombinant GAL-1 revealed a specific dose-dependent inhibitory effect in vitro in antigen-dependent interleukin 2 production to an A(q)-restricted, collagen type 2-specific T cell hybridoma clone. Thus, a correlation between the apoptotic properties of GAL-1 in vitro and its immunomodulatory properties in vivo supports its therapeutic potential in the treatment of T helper cell type 1-mediated autoimmune disorders.     

Dietary fish oil modulates macrophage fatty acids and decreases arthritis susceptibility in mice

B10.RIII and B10.G mice were transferred from a diet of laboratory rodent chow to a standard diet in which all the fat (5% by weight) was supplied as either fish oil (17% eicosapentaenoic acid [EPA], 12% docosahexaenoic acid [DHA], 0% arachidonic acid [AA], and 2% linoleic acid) or corn oil (0% EPA, 0% DHA, 0% AA, and 65% linoleic acid). The fatty acid composition of the macrophage phospholipids from mice on the chow diet was similar to that of mice on a corn oil diet. Mice fed the fish oil diet for only 1 wk showed substantial increases in macrophage phospholipid levels of the omega-3 fatty acids (of total fatty acid 4% was EPA, 10% docosapentaenoic acid [DPA], and 10% DHA), and decreases in omega-6 fatty acids (12% was AA, 2% docosatetraenoic acid [DTA], and 4% linoleic acid) compared to corn oil-fed mice (0% EPA, 0% DPA, 6% DHA, 20% AA, 9% DTA, and 8% linoleic acid). After 5 wk this difference between the fish oil-fed and corn oil-fed mice was even more pronounced. Further small changes occurred at 5-9 wk. We studied the prostaglandin (PG) and thromboxane (TX) profile of macrophages prepared from mice fed the two diets just before being immunized with collagen. Irrespective of diet, macrophages prepared from female mice and incubated for 24 h had significantly more PG and TX in the medium than similarly prepared macrophages from male mice. The increased percentage of EPA and decreased percentage of AA in the phospholipids of the macrophages prepared from the fish oil-fed mice was reflected in a reduction in the amount of PGE2 and PGI2 in the medium relative to identically incubated macrophages prepared from corn oil-fed mice. When this same fish oil diet was fed to B10.RIII mice for 26 d before immunization with type II collagen, the time of onset of arthritis was increased, and the incidence and severity of arthritis was reduced compared to arthritis induced in corn oil-fed mice. The females, especially those on the fish oil diet, tended to have less arthritis than the males. These alterations in the fatty acid pool available for PG and leukotriene synthesis suggest a pivotal role for the macrophage and PG in the immune and/or inflammatory response to type II collagen.     

Passive Transfer by Cells of Type II Collagen-Induced Arthritis in Rats

To investigate the role of immunologic hypersensitivity to collagen in the causation of type II collagen-induced arthritis in rats, passive transfer experiments were performed. Wistar/Lewis rats used in these experiments were demonstrated to be histocompatible by prolonged skin graft survival and mixed lymphocyte cultures. Popliteal lymph node weight assays excluded a potential for graft-vs.-host reactivity in this strain. 9 of 32 naive rats developed arthritis after intravenous receipt of pooled spleen and lymph node cells from donors that had been injected intradermally with type II collagen emulsified in incomplete Freund's adjuvant. This passively transferred synovitis was evident clinically as well as histologically. In control cell transfer experiments involving a total of 97 recipients, transfer of arthritis was shown to require viable cells sensitized to type II collagen. These controls included 17 rats receiving cells from unimmunized donors, 20 recipients of cells from donors injected with incomplete Freund's adjuvant alone, and 24 recipients of cells from rats injected with type I collagen in adjuvant. Deliberate addition of solubilized type II collagen to unsensitized cells at the time of transfer or injection of heat-killed sensitized cells also did not cause arthritis in a total of 36 recipients. These latter two control groups indicate that disease transfer was not the result of antigen carry-over. Intravenous injection of sera from arthritic donors was incapable of passively transferring clinical or histologic synovitis in 30 recipients. Thus, these studies directly implicate immunologic sensitivity to the cartilage type of collagen in the etiology of this autoimmune disease.     

Collagen II-pulsed antigen-presenting cells genetically modified to secrete IL-4 down-regulate collagen-induced arthritis

We explored the possibility that pulsed antigen-presenting cells (APC) provide a model vector system for site-specific delivery of immunosuppressive proteins during collagen-induced arthritis (CIA), an animal model for rheumatoid arthritis. Thus, mice were treated with either B cells or macrophages engineered to secrete IL-4 and loaded (or not) with type II collagen (CII). Systemic injection of an IL-4-producing B cell hybridoma resulted in a reduction of arthritis severity which was further improved when APC were incubated with CII before their transfer. Unmanipulated B cells loaded with CII also exerted a potent suppressive effect. Likely, clinical amelioration was observed in mice given at priming syngeneic bone marrow-derived macrophages producing IL-4 and pulsed with CII in comparison to the other groups. When the same dose of cells was transferred at disease onset, a moderate beneficial effect was observed. Whatever the APC inoculated, the beneficial effect did not rely upon an IL-4-driven shift towards Th2 phenotype. Systemic administration of fluorescent dye labeled macrophages to arthritic mice has shown that some of these cells rapidly migrate to joints. Moreover, IL-4 transfected macrophages retained their potent capacity to present CII peptides to T cells. These findings validate the use of CII peptide-loaded engineered APC as therapeutic vector cells in CIA and allow consideration of this strategy for the administration of various anti-inflammatory proteins.     

Immunization with T cell receptor V beta chain peptides deletes pathogenic T cells and prevents the induction of collagen-induced arthritis in mice.

Collagen-induced arthritis (CIA) in susceptible strains of mice is an animal model of T cell-mediated inflammatory polyarthritis. Analysis of T cell receptor (TCR) V beta gene usage in cells isolated from arthritic joints of BUB/BnJ (BUB) mice (H-2q, TCR V beta a) showed that TCR V beta chain gene usage was limited to TCR V beta 3 and V beta 10 gene families. All of the BUB mice immunized with a mixture of TCR V beta 3 and TCR V beta 10 peptides, but not with control TCR V beta 14 peptide, were refractory to the induction of CIA. Immunization with TCR V beta 3 and V beta 10 peptides completely blocked the development of clinical and subclinical inflammation, formation of pannus and synovial hyperplasia, and the erosion of cartilage and bone. Further studies revealed that preimmunization of BUB mice with V beta 10 peptide alone was sufficient to render the mice resistant to CIA. Analysis of TCR V beta chain gene expression in lymph node cells from arthritic and arthritis-protected mice showed the expression of TCR V beta 10 subfamily in all of the arthritic mice, but not in arthritis-protected mice. Immunization with TCR V beta peptides did not diminish the humoral responses to chicken type-II collagen and also elicited significant levels of anti-V beta 3 and anti-V beta 10 peptide antibodies. Antibodies cross-reactive with mouse chicken type-II collagen were detected in both the arthritic and arthritis-protected mice. Adoptive transfer of serum from arthritis-protected BUB mice significantly delayed the onset (P < 0.005) of arthritis in recipient BUB mice. In contrast, mice injected with serum from arthritic mice had early onset of arthritis. These results demonstrate that immunization of BUB mice with TCR V beta chain peptides elicited antibodies reactive with the self-TCR and prevented the induction of collagen-induced arthritis by eliminating or downregulating pathogenic T cells and consequently blocking the development of humoral immune response. These findings may have clinical applications in treating human autoimmune diseases characterized by common TCR gene usage.     

Regulation of autoimmunity and donor cell engraftment by recipient Lyt- 2+ cells during the graft-versus-host reaction

When lymphocytes from DBA/2 mice are transferred to (C57BL X DBA/2)F1 (BDF1) mice, the ensuing graft-vs.-host reaction (GVHR) causes an autoimmune illness resembling human SLE. To examine the role of recipient T cells in this process, BDF1 mice were depleted of L3T4+ or Lyt-2+ cells by thymectomy followed by treatment with mAbs to L3T4 or Lyt-2. This produced sustained depletion of these T cell subsets. Subsequent grafting with parental DBA/2 lymphocytes produced autoimmune disease in mice depleted of L3T4+ cells and controls but not in mice depleted of Lyt-2+ cells. Analysis of blood lymphocytes 4 wk after donor cell transfer demonstrated that BDF1 recipients depleted of Lyt-2+ cells were virtually repopulated with donor T lymphocytes, compared with less than or equal to 35% donor cell engraftment in all other groups. Thus, recipient Lyt-2+ cells influence both host cell engraftment and autoimmunity during the parent-into-F1 GVHR.     

Idiotype-anti-idiotype network. II. Activation of silent clones by treatment at birth with idiotypes is associated with the expansion of idiotype-specific helper T cells

BALB/c mice immunized with bacterial levan (BL) produce a vigorous antibody response that fails to include antibodies expressing the idiotype of the beta 2 leads to 6 fructosan-binding myeloma protein ABPC48 (A48). Treatment of newborn BALB/c mice at 1 d of age with 0.1- 10 microgram of either the A48 myeloma protein or monoclonal proteins that share idiotopes with the A48 family, followed by immunization with BL 2-4 wk later, produces an anti-BL response that is dominated by the A48Id. Various degrees of activation of the A48Id BL response were observed by injecting mice with A48 monoclonal protein only up until 3 wk of age. Activation of the A48Id clones by treating with A48 monoclonal protein was ineffective in mice who were older than 4 wk. Elicitation of an A48Id BL response required specific antigenic stimulation with either beta 2 leads to 6 or beta 2 leads to 1 fructosan epitopes, because it does not occur after injection with TNP- Ficoll in spite of the A48 treatment. The expansion of A48Id clones in mice treated at birth with A48 monoclonal protein is associated with an increase in A48Id-specific helper T cells. The binding specificity of these cells was demonstrated by infusing them into nu/nu BALB/c mice and observing that they rendered help that enalbed the animal to mount an anti-TNP response after immunization only with A48-TNP, but not with MOPC384-TNP conjugates. The helper activity of these cells is sensitive to the effects of treatment with anti-Lyt-1.2 antibodies plus complement. A predominantly A48Id BL-specific response can be transferred into lethally irradiated mice by infusing them with purified T and B cells from A48-treated mice. The transfer of this response can be ablated by treating the T cells with anti-Lyt-1.2 antibodies plus complement. These results indicate that A48Id-specific helper cells possess the ability to select the A48Id-bearing B cell precursors for expression, thus exerting a fine-tuning effect on the idiotypic expression of the anti-BL repertoire. We propose that this idiotype-induced idiotype response, which can be, in principal, induced by idiotypes provided by the mother, plays an important role in the expansion of precursors of antibody-forming cells during embryonic as well as postnatal life.     

Antibodies are not essential for the resolution of primary cytomegalovirus infection but limit dissemination of recurrent virus

Virus shedding from the epithelial cells of the serous acini of salivary glands is a major source for the horizontal transmission of cytomegalovirus. These cells are, different to other tissues, exempt from CD8 T lymphocyte control. CD4 T lymphocytes are essential to terminate the productive infection. Here, we prove that T-B cooperation and the production of antibodies are not required for this process. For the infection with murine cytomegalovirus, mutant mice were used which do not produce antibodies because of a disrupted membrane exon of the immunoglobulin mu chain gene. Also, in these mice the virus clearance from salivary glands is a function of CD4 T lymphocytes. However, these mice clear the virus and establish viral latency with a kinetics that is distinguishable from normal mice. Reactivation from virus latency is the only stage at which the absence of antibodies alters the phenotype of infection. In immunoglobulin-deficient mice, virus recurrence results in higher virus titers. The adoptive serum transfer proved that antibody is the limited factor that prevents virus dissemination in the immunodeficient host.     

Syngeneic transfer of autoimmune diabetes from diabetic NOD mice to healthy neonates. Requirement for both L3T4+ and Lyt-2+ T cells

We have developed a model of syngeneic adoptive transfer for type I diabetes mellitus of NOD mice. This model consists in injecting spleen cells from diabetic adult mice into newborn NOD recipients. 50% of recipients inoculated with 20 X 10(6) cells develop diabetes within the first 10 wk of life, at a time when none of the control littermates have yet become diabetic. The earliest successful transfers are observed at 3 wk of age, at a time when controls do not even exhibit histological changes in their pancreas. In addition we have shown that: (a) both males and females can be adoptively transferred, despite the fact that males rarely develop spontaneous diabetes in our colony; (b) diabetes transfer is a dose-dependent phenomenon that provides an in vivo assay for comparing the autoimmune potential of spleen cells from mice at various stages of their natural history; (c) the susceptibility of the recipients to the transfer is limited in time and declines after 3 wk; and (d) both L3T4+ and Lyt-2+ T cell subsets are necessary for the successful transfer. The neonatal syngeneic transfer provides an effective model for studies of the cellular events involved at regulatory and effector stages of autoimmune type I diabetes.     

Induction of dermal-epidermal separation in mice by passive transfer of antibodies specific to type VII collagen

Epidermolysis bullosa acquisita (EBA) is a subepidermal blistering disorder associated with tissue-bound and circulating autoantibodies specific to type VII collagen, a major constituent of the dermal-epidermal junction. Previous attempts to transfer the disease by injection of patient autoantibodies into mice have been unsuccessful. To study the pathogenic relevance of antibodies specific to type VII collagen in vivo, we generated and characterized rabbit antibodies specific to a murine form of this antigen and passively transferred them into adult nude, BALB/c, and C57BL/6 mice. Immune rabbit IgG bound to the lamina densa of murine skin and immunoblotted type VII collagen. Mice injected with purified IgG specific to type VII collagen, in contrast to control mice, developed subepidermal skin blisters, reproducing the human disease at the clinical, histological, electron microscopical, and immunopathological levels. Titers of rabbit IgG in the serum of mice correlated with the extent of the disease. F(ab')(2) fragments of rabbit IgG specific to type VII collagen were not pathogenic. When injected into C5-deficient mice, antibodies specific to type VII collagen failed to induce the disease, whereas C5-sufficient mice were susceptible to blister induction. This animal model for EBA should facilitate further dissection of the pathogenesis of this disease and development of new therapeutic strategies.     

Cross-reactivity of cell-mediated immunity between interstitial (type I) and basement membrane (type IV) collagens

In the present study, we demonstrate delayed-type hypersensitivity (DTH) to homologous type I collagen that cross-reacts with type IV collagen. Mice immunized with native or denatured type I collagens and challenged with these same antigens or native type IV collagen develop a peak DTH response on day 7. Challenge with denatured type IV collagen or collagenase-treated type IV collagen failed to elicit DTH in type I collagen-sensitized mice. Type I collagen-sensitized spleen cells adoptively transferred DTH to types IV and I collagen to normal recipients; T cell-depleted spleen cells failed to transfer immunity. Periodate-treated type IV collagen did not elicit DTH in mice sensitized to type I collagen; however, mice sensitized with type IV collagen displayed significant DTH when challenged with periodate- treated type IV collagen. Furthermore, treatment of type IV collagen with a mixed glycosidase or alpha-glucosidase before challenge eliminated the DTH response in type I collagen-sensitized mice; beta- galactosidase treatment of type IV collagen had no effect on this response. Mice sensitized with type IV collagen, however, displayed significant DTH when challenged with these glycosidase-treated antigens. Antibodies produced to types I and IV collagen by repeated immunizations were specific for the sensitizing antigen and did not react with other connective tissue antigens. These studies indicate that a CMI response to type I collagen recognizes similar antigenic determinants on the type IV collagen molecule. These cross-reacting determinants are dependent on conformation and contain carbohydrates, particularly glucose residues.     

Prevention of collagen-induced arthritis by gene delivery of soluble p75 tumour necrosis factor receptor

Collagen type II-induced arthritis (CIA) in DBA/1 mice can be passively transferred to SCID mice with spleen B- and T-lymphocytes. In the present study, we show that infection ex vivo of splenocytes from arthritic DBA/1 mice with a retroviral vector, containing cDNA for the soluble form of human p75 receptor of tumour necrosis factor (TNF-R) before transfer, prevents the development of arthritis, bone erosion and joint inflammation in the SCID recipients. Assessment of IgG subclass levels and studies of synovial histology suggest that down-regulating the effector functions of T helper-type 1 (Th1) cells may, at least in part, explain the inhibition of arthritis in the SCID recipients. In contrast, the transfer of splenocytes infected with mouse TNF-alpha gene construct resulted in exacerbated arthritis and enhancement of IgG2a antibody levels. Intriguingly, infection of splenocytes from arthritic DBA/1 mice with a construct for mouse IL-10 had no modulating effect on the transfer of arthritis. The data suggest that manipulation of the immune system with cytokines, or cytokine inhibitors using gene transfer protocols can be an effective approach to ameliorate arthritis.     

In vivo CD40-gp39 interactions are essential for thymus-dependent humoral immunity. II. Prolonged suppression of the humoral immune response by an antibody to the ligand for CD40, gp39

The ligand for CD40 has been recently identified as a 39-kd protein, gp39, expressed on the surface of activated CD4+ T helper cells (Th). In vitro, soluble CD40 and anti-gp39 have been shown to block the ability of Th to activate B cells, suggesting that gp39-CD40 interactions are important to T cell-dependent B cell activation. Here it is shown that in vivo administration of anti-gp39 dramatically reduced both primary and secondary humoral immune responses to erythrocytes and soluble protein antigens without altering responses to the T-independent type II antigen, trinitrophenyl-Ficoll. Treatment of mice for 4 d with anti-gp39 inhibited the anti-sheep red blood cell (SRBC) response for at least 3 wk and inhibited the expression of all immunoglobulin isotypes in secondary responses to the protein antigen, keyhole limpet hemocyanin. To examine the direct effect of anti-gp39 on Th function, SRBC-immune Th cells from anti-gp39-treated mice were adoptively transferred and shown to be fully capable of providing help. These results suggest that anti-gp39 treatment does not cause Th deletion or anergy. Anti-gp39 may mediate its profound immunosuppressive effects on humoral immunity by blocking gp39-CD40 interactions. Moreover, these studies establish gp39-CD40 as an important receptor-ligand pair for the targeting of therapeutic antibodies to control thymus-dependent humoral responses.     

Prevention of type II collagen-induced arthritis by in vivo treatment with anti-L3T4

The effect of in vivo administration of monoclonal anti-L3T4 antibody on the development of murine collagen-induced arthritis (CIA) was assessed. Treatment with anti-L3T4 resulted in a greater than 90% depletion of L3T4+ T cells in lymph nodes and spleen, an effect that appears entirely reversed 30 d after treatment. Administration of anti-L3T4 before immunization with type II collagen resulted in a significant decrease in arthritis incidence and delayed onset of the disease while treatment begun after a strong anticollagen IgG humoral response was underway was not effective in altering disease expression. These results suggest a prominent role for L3T4+ T cells in the pathogenesis of CIA.     

Biologic properties of romazarit (Ro 31-3948), a potential disease-modifying antirheumatic drug

The biologic effects of a new potential disease-modifying antirheumatic drug, romazarit (Ro 31-3948, 2-[[2-(4-chlorophenyl)-4-methyl-5-oxazolyl]methoxy]-2-methylpropio nic acid), have been investigated. In a 5-day adjuvant arthritis model, romazarit inhibited the development of hindpaw inflammation with a minimum effective dose of 30 mg kg-1. Plasma levels of the acute phase reactants seromucoid and haptoglobulin were also significantly reduced. Romazarit was equally effective in adrenalectomized animals, indicating that the compound is not acting via stimulation of the pituitary/adrenal axis. When the developing adjuvant arthritis was extended to 15 days romazarit showed dose-related improvements of all the symptoms of arthritis with a minimum effective dose of 25 mg kg-1. Romazarit caused a dose-dependent (range 20-250 mg kg-1) reduction in both the inflammatory and bony changes occurring during collagen arthritis in the rat, without any significant effect on anticollagen antibody titers except at the highest dose. Collagenase and prostaglandin E2 production in cultures of talus bones taken from rats with collagen arthritis were reduced by romazarit. In vitro romazarit was an extremely weak inhibitor of prostaglandin synthetase activity in both sheep seminal vesicle (IC50 6500 microM) and rat renal medulla (IC50 greater than 300 microM) cell-free preparations. Romazarit showed little or no activity in models of acute inflammation such as rabbit skin edema, carrageenan pleurisy or UV-induced erythema. In both acute and chronic tests romazarit displayed no ulcerogenic potential. In comparison with the structurally similar compound clobuzarit, hepatic changes such as increases in catalase and peroxisome proliferation-associated 80,000 mol.wt. protein were markedly less with romazarit. Clinical studies with romazarit are currently in progress.     

Identification of an immunosuppressive epitope of type II collagen that confers protection against collagen-induced arthritis

We have previously reported that collagen-induced arthritis can be suppressed by intravenous injection of native type II (CII) but not type I collagen. We have now identified denatured fragments of CII capable of suppressing collagen-induced arthritis and inducing tolerance. Purified CII was cleaved with cyanogen bromide (CB), and the major resulting peptides were isolated. Female DBA/1 mice were administered OVA, native CII, or one of the CB peptides, intravenously, before immunization with native CII, 6 wk after immunization, mice tolerized with CII and CB11 had a markedly lower incidence of arthritis compared with controls. There was a correlation between the overall antibody response and the incidence of arthritis. In addition, animals tolerized with either CII or CB11 had a decreased antibody response not only to CII, but also to each of the other CB peptides tested. To identify the epitope involved in suppression of arthritis, five synthetic peptides, 21-26 amino acids in length, corresponding to selected regions of CB11, were generated. Each of the peptides was injected intravenously into mice before immunization. Only one of these, CB11 122-147, was capable of suppressing arthritis. In addition, mice given the synthetic peptide CB11 122-147 neonatally were suppressed for arthritis and antibody responsiveness when immunized with CII at 8 wk of age. Thus, we have identified CB11 122-147 as an epitope of CII important in induction of tolerance and suppression of disease. Further experiments narrowing down the pivotal amino acids for the immunogenicity of this epitope and the role this epitope plays in induction and regulation of disease will enhance our understanding of how the immune response to collagen affects autoimmune arthritis.