Effectiveness of the soluble form of the interleukin-1 receptor accessory protein as an inhibitor of interleukin-1 in collagen-induced arthritis

OBJECTIVE: To investigate whether the soluble form of interleukin-1 (IL-1) receptor accessory protein (sIL-1RAcP), whose physiologic function remains to be established, can serve as a specific inhibitor of IL-1 signaling in vitro, and to evaluate its applicability in collagen-induced arthritis (CIA). METHODS: Soluble IL-1RAcP was cloned from murine liver complementary DNA and expressed by the use of either an adenoviral vector (AdRGD) for sIL-1RAcP or a stable-transfected NIH3T3 fibroblast cell line. The ability of affinity-purified sIL-1RAcP to inhibit IL-1 signaling was tested on NF-kappaB luciferase reporter fibroblasts and quantified by luminometer. To investigate therapeutic efficacy, sIL-1RAcP was both locally (knee joint) and systemically overexpressed in collagen-immunized male DBA/1 mice. Severity of arthritis was monitored visually, and the pathologic process in the joint was examined histologically. Serum was obtained from mice to quantify IL-6 and anti-bovine type II collagen (BCII) antibody levels. RESULTS: Incubation of the NF-kappaB reporter fibroblast with purified sIL-1RAcP protein showed a marked reduction of IL-1-induced, but not tumor necrosis factor-induced, NF-kappaB activation. This showed a novel role for sIL-1RAcP as a specific inhibitor of IL-1 signaling. Local transplantation of sIL-1RAcP-producing NIH3T3 fibroblasts into the knee before onset of CIA had little or no effect on general disease severity in these mice. Histologic evaluation of the knee joints receiving sIL-1RAcP cell transplantation showed a marked reduction in both joint inflammation and bone and cartilage erosion. Local treatment with sIL-1RAcP had no profound effect on serum levels of IL-6 and anti-BCII antibodies, which is indicative of the ongoing presence of arthritis in distal joints. In contrast to local treatment, systemic treatment with the AdRGD for sIL-1RAcP markedly ameliorated CIA in all joints. CONCLUSION: In this study we demonstrated that sIL-1RAcP is a biologically active and innovative inhibitor of IL-1, and treatment of mice with sIL-1RAcP had a profound prophylactic effect on collagen-induced arthritis.     

Soluble interleukin‐1 receptor accessory protein ameliorates collagen‐induced arthritis by a different mode of action from that of interleukin‐1 receptor antagonist

Objective

To discern the mode of interleukin‐1 (IL‐1) inhibition of soluble IL‐1 receptor accessory protein (sIL‐1RAcP) by comparison with IL‐1 receptor antagonist (IL‐1Ra) in arthritis.

Methods

Adenoviral vectors encoding either sIL‐1RAcP or IL‐1Ra were administered systemically before onset of collagen‐induced arthritis in DBA/1 mice. Anti–bovine type II collagen IgG and IL‐6 were quantified in serum. Proliferative response of splenic T cells was determined in the presence of sIL‐1RAcP or IL‐1Ra. The effect on IL‐1 inhibition of recombinant sIL‐1RAcP and IL‐1Ra was further examined in vitro, using NF‐κB luciferase reporter cell lines. Quantitative polymerase chain reaction was used to determine the relative messenger RNA expression of the IL‐1 receptors.

Results

Adenoviral overexpression of both sIL‐1RAcP and IL‐1Ra resulted in amelioration of the collagen‐induced arthritis. Both IL‐1 antagonists reduced the circulating levels of antigen‐specific IgG2a antibodies, but only IL‐1Ra was able to inhibit lymphocyte proliferation. By using purified lymphocyte populations derived from NF‐κB reporter mice, we showed that sIL‐1RAcP inhibits IL‐1–induced NF‐κB activity in B cells but not T cells, whereas IL‐1Ra inhibited IL‐1 on both cell types. A study in a panel of NF‐κB luciferase reporter cells showed that the sIL‐1RAcP inhibits IL‐1 signaling on cells expressing either low levels of membrane IL‐1RAcP or high levels of IL‐1RII.

Conclusion

We show that the sIL‐1RAcP ameliorated experimental arthritis without affecting T cell immunity, in contrast to IL‐1Ra. Our results provide data in support of receptor competition by sIL‐1RAcP as an explanation for the different mode of IL‐1 antagonism in comparison with IL‐1Ra.

     

The role of interleukin-1 receptor antagonist in the prevention and treatment of disease

Abstract

?Interleukin-1 (IL-1) and tumor necrosis factor α (TNF-α) play key proinflammatory roles in a variety of human diseases, including rheumatoid arthritis (RA). IL-1 receptor antagonist (IL-1Ra) is a naturally occurring structural variant of IL-1 that competitively inhibits receptor binding of IL-1. Four forms of IL-1Ra have been described: secretory IL-1Ra (sIL-1Ra) and three intracellular molecules (icIL-1Ra1, 2, and 3). Excess amounts of IL-1Ra are necessary to inhibit the biological effects of IL-1. The endogenous production of IL-1Ra plays an anti-inflammatory role, but the level of production of IL-1Ra in inflamed tissues may not be adequate to block IL-1 effectively. An allelic polymorphism in the IL-1Ra gene is associated with a variety of human diseases, largely of epithelial or endothelial cell origin. The disease associated allele IL1RN*2 may lead to a decreased production of icIL-1Ra1 by these cells, predisposing the patient to an imbalance in the IL-1 system. The therapeutic administration of IL-1Ra was found to be safe and efficacious in the treatment of RA. Intraarticular delivery of the IL-1Ra cDNA by ex vivo gene therapy in patients with RA was effective in enhancing local IL-1Ra production. This unique form of therapy is under further evaluation.     

The role of interleukin-1 receptor antagonist in the prevention and treatment of disease

 Interleukin-1 (IL-1) and tumor necrosis factor α (TNF-α) play key proinflammatory roles in a variety of human diseases, including rheumatoid arthritis (RA). IL-1 receptor antagonist (IL-1Ra) is a naturally occurring structural variant of IL-1 that competitively inhibits receptor binding of IL-1. Four forms of IL-1Ra have been described: secretory IL-1Ra (sIL-1Ra) and three intracellular molecules (icIL-1Ra1, 2, and 3). Excess amounts of IL-1Ra are necessary to inhibit the biological effects of IL-1. The endogenous production of IL-1Ra plays an anti-inflammatory role, but the level of production of IL-1Ra in inflamed tissues may not be adequate to block IL-1 effectively. An allelic polymorphism in the IL-1Ra gene is associated with a variety of human diseases, largely of epithelial or endothelial cell origin. The disease associated allele IL1RN^*2 may lead to a decreased production of icIL-1Ra1 by these cells, predisposing the patient to an imbalance in the IL-1 system. The therapeutic administration of IL-1Ra was found to be safe and efficacious in the treatment of RA. Intraarticular delivery of the IL-1Ra cDNA by ex vivo gene therapy in patients with RA was effective in enhancing local IL-1Ra production. This unique form of therapy is under further evaluation. Correspondence to:W.P. Arend     

Immunoregulatory effects of allogeneic mixed chimerism induced by nonmyeloablative bone marrow transplantation on chronic inflammatory arthritis and autoimmunity in interleukin-1 receptor antagonist-deficient mice

OBJECTIVE: To investigate the immunoregulatory effects of allogeneic mixed chimerism induced by T cell-depleted, nonmyeloablative bone marrow transplantation (BMT) on chronic inflammatory arthritis and autoimmunity in mice deficient in interleukin-1 receptor antagonist (IL-1Ra). METHODS: IL-1Ra(-/-) mice (H-2K(d)) were treated with antibody to asialoganglioside G(M1) (anti-natural killer cell), total body irradiation (500 cGy), and T cell-depleted, nonmyeloablative BMT derived from C57BL/6 mice (H-2K(b)). Engraftment and chimerism were evaluated in peripheral blood, lymph nodes, and spleen by multicolor flow cytometry. The severity of arthritis was evaluated by clinical scoring and histopathologic assessment. Levels of IgG1 and IgG2a subtypes of anti-type II collagen (anti-CII) antibodies were measured in serum samples. After T cells were stimulated with CII, ovalbumin, and phytohemagglutinin, T cell proliferative responses and levels of cytokine production (interferon-gamma [IFNgamma], tumor necrosis factor alpha [TNFalpha], interleukin-10 [IL-10], and IL-17) were assayed in culture supernatants. RESULTS: All IL-1Ra(-/-) mice receiving BMT showed marked improvement in arthritis within 3 weeks, as well as successful induction of mixed chimerism. These mice showed higher levels of IgG1, and lower levels of IgG2a anti-CII antibodies and weaker T cell proliferative responses than did mice in the control groups (either no treatment or conditioning alone without bone marrow rescue). In mixed chimeras, the levels of IFNgamma, TNFalpha, and IL-17 produced from CII-stimulated T cells were significantly suppressed and IL-10 production was significantly higher as compared with controls. CONCLUSION: The introduction of allogeneic mixed chimerism showed a strong immunoregulatory potential to correct established chronic inflammatory arthritis and autoimmunity originating from a dysregulated proinflammatory cytokine network.     

Rosiglitazone induces interleukin-1 receptor antagonist in interleukin-1beta-stimulated rat synovial fibroblasts via a peroxisome proliferator-activated receptor beta/delta-dependent mechanism

OBJECTIVE: To study the potency of 2 peroxisome proliferator-activated receptor gamma (PPARgamma) agonists, 15-deoxy-Delta(12,14)-prostaglandin J(2) (15-deoxy-PGJ(2)) and rosiglitazone, to modulate the expression of interleukin-1 receptor antagonist (IL-1Ra) in rat synovial fibroblasts. METHODS: Levels of messenger RNA for IL-1Ra and PPAR isotypes (alpha, beta/delta, gamma) were assessed by real-time polymerase chain reaction in rat synovial fibroblasts exposed to 10 ng/ml of IL-1beta. PPAR levels were assessed by Western blotting and secreted IL-1Ra levels by immunoassay. The potency of PPARgamma agonists and the PPARbeta/delta agonist GW-501516 on IL-1Ra levels was tested in the range of 1-10 microM and at 100 pM, respectively. The contribution of PPARgamma to the effects of rosiglitazone on IL-1Ra secretion was examined either by its overexpression or by inhibition using wild-type or dominant-negative constructs and the antagonist GW-9662 (10 microM), respectively. The dominant-negative strategy was also performed to investigate the possible contribution of PPARbeta/delta and NF-kappaB activation. RESULTS: IL-1beta-induced IL-1Ra production was increased by 10 microM rosiglitazone but was reduced dose-dependently by 15-deoxy-PGJ(2). Both agonists lowered IL-1beta secretion, but rosiglitazone alone reduced the imbalance of IL-1beta/IL-1Ra toward basal levels. Enhancement of IL-1beta-induced IL-1Ra production by rosiglitazone was not affected by PPARgamma overexpression or by its inhibition with dominant-negative PPARgamma or GW-9662. Inhibition of NF-kappaB was also ineffective against rosiglitazone but abolished the stimulating effect of IL-1beta on IL-1Ra. All PPAR isotypes were expressed constitutively in rat synoviocytes, but PPARgamma decreased dramatically upon IL-1beta exposure, whereas PPARbeta/delta remained stable. Dominant-negative PPARbeta/delta abolished the enhancement of IL-1Ra by rosiglitazone, whereas GW-501516 reproduced the effect of rosiglitazone on IL-1Ra secretion. CONCLUSION: Rosiglitazone stimulates IL-1Ra production by a PPARbeta/delta mechanism in activated rat synovial fibroblasts, further contributing to its potential antiarthritic properties and opening new perspectives for the modulation of inflammatory genes by specific PPAR agonists in articular cells.     

CD28-dependent differentiation into the effector/memory phenotype is essential for induction of arthritis in interleukin-1 receptor antagonist-deficient mice

OBJECTIVE: Interleukin-1 receptor antagonist (IL-1Ra)-deficient mice on a BALB/c background spontaneously develop a chronic inflammatory polyarthropathy closely resembling that of rheumatoid arthritis in humans. To elucidate the role of CD28 costimulatory signals in the development of this disease, we studied IL-1Ra/CD28-double-deficient mice. METHODS: We crossed IL-1Ra-deficient mice with CD28-deficient mice and observed the incidence and severity of arthritis. To investigate functions of IL-1Ra/CD28-double-deficient T cells, cells were stimulated with CD3 monoclonal antibody or allogeneic antigen-presenting cells (APCs) and their proliferative responses and levels of cytokine production were measured. RESULTS: Disease severity was lower in IL-1Ra/CD28-double-deficient mice than in mice that were deficient only in IL-1Ra, although incidence of arthritis was not affected by the presence or absence of CD28. When pathogenic IL-1Ra-KO T cells were transferred into nude mice, severe arthritis developed. Even though T cells from double-deficient mice showed the same diminished proliferative capacity as was seen in T cells from CD28-single-deficient animals, nude mice into which double-deficient T cells were transferred never developed arthritis. CONCLUSION: These findings indicate that IL-1Ra/CD28-double-deficient T cells can be activated by IL-1Ra-deficient activated APCs, resulting in induction of arthritis; however, these T cells did not induce the disease under normal conditions, because they did not differentiate into effector/memory phenotype.     

Blockade of the interleukin-21/interleukin-21 receptor pathway ameliorates disease in animal models of rheumatoid arthritis

OBJECTIVE: Interleukin-21 (IL-21) is a T cell-derived cytokine that modulates T cell, B cell, and natural killer cell responses. In this study, the effects of blocking IL-21 were examined in 2 rodent models of rheumatoid arthritis (RA) to determine whether IL-21 contributes to their pathologic processes. METHODS: DBA/1 mice were immunized with bovine type II collagen and then treated with murine IL-21 receptor Fc fusion protein (IL-21R.Fc), which was initiated after the onset of arthritis symptoms in 10% of the cohort. The mice were assessed 3 times per week for signs of disease, including histologic features as well as serum cytokine, Ig, and cytokine messenger RNA (mRNA) levels in the paws. In a separate experiment, Lewis rats were immunized with Freund's complete adjuvant followed by administration of IL-21R.Fc at the peak of inflammation in the joints. Rats were assessed daily for histologic features and for scoring of arthritis severity. In addition, the effects of IL-21R.Fc on the production of interferon-gamma (IFNgamma) by T cells were examined. RESULTS: Treatment of DBA/1 mice with IL-21R.Fc reduced the clinical and histologic signs of collagen-induced arthritis. Nonspecific IgG1 levels were decreased in response to treatment. The levels of IL-6 mRNA in the paws and the serum IL-6 levels were decreased after treatment with IL-21R.Fc. IFNgamma mRNA levels were increased in the paws, and the addition of IL-21R.Fc to collagen-activated lymph node cultures enhanced the levels of IFNgamma. Collagen-specific spleen cell responses in IL-21R.Fc-treated mice were observed as reduced levels of IFNgamma and increased levels of IL-6. Treatment of Lewis rats with IL-21R.Fc after induction of adjuvant-induced arthritis resulted in reversal of disease signs and improvements in histologic parameters. CONCLUSION: These findings demonstrate a pathogenic role for IL-21 in animal models of RA, and support consideration of IL-21 as a therapeutic target in human RA.     

IL-1 receptor accessory protein is essential for IL-33-induced activation of T lymphocytes and mast cells

Lack of the IL-1 receptor accessory protein (IL-1RAcP) abrogates responses to IL-33 and IL-1 in the mouse thymoma clone EL-4 D6/76 cells. Reconstitution with full-length IL-1RAcP is sufficient to restore responsiveness to IL-33 and IL-1. IL-33 activates IL-1 receptor-associated kinase-1, cJun-N-terminal kinase, and the NF-kappaB pathway in an IL-1RAcP-dependent manner and results in IL-2 release. IL-33 is able to induce the release of proinflammatory cytokines in bone marrow-derived (BMD) mast cells, indicating that IL-33 may have a proinflammatory potential like its relatives IL-1 and IL-18, in addition to its Th2-skewing properties in the adaptive response described previously. Blocking of murine IL-1RAcP with the neutralizing antibody 4C5 inhibits response of mouse thymoma cells and BMD mast cells to IL-33. The interaction of either membrane-bound or soluble forms of IL-1RAcP and IL-33Ralpha-chain depends on the presence of IL-33, as demonstrated by coimmunoprecipitation assays. These data demonstrate that IL-1RAcP is indispensable for IL-33 signaling. Furthermore, they suggest that IL-1RAcP is used by more than one alpha-chain of the IL-1 receptor family and thus may resemble a common beta-chain of that family.     

Combination benefit of treatment with the cytokine inhibitors interleukin-1 receptor antagonist and PEGylated soluble tumor necrosis factor receptor type I in animal models of rheumatoid arthritis

OBJECTIVE: To determine the potential for additive or synergistic effects of combination therapy with the recombinant anticytokine agents interleukin-1 receptor antagonist (IL-1Ra) and PEGylated soluble tumor necrosis factor receptor type I (PEG sTNFRI) in established type H collagen-induced arthritis (CIA) and developing adjuvant-induced arthritis (AIA) in rats. METHODS: Rats with established CIA or developing AIA were treated with various doses of IL-1Ra in a slow-release hyaluronic acid vehicle or with PEG sTNFRI, either alone or in combination with the IL-1Ra. The effects of treatment were monitored by sequential caliper measurements of the ankle joints or hind paw volumes, final paw weights, and histologic evaluation with particular emphasis on bone and cartilage lesions. RESULTS: Combination therapy with IL-1Ra and PEG sTNFRI in rats with CIA resulted in an additive effect on clinical and histologic parameters when moderately to highly efficacious doses of each protein were administered. Greater-than-additive effects were seen when an inactive dose of IL-1Ra was given in combination with moderately to minimally active doses of PEG sTNFRI. Plasma levels associated with the latter effect (for both proteins) were similar to those seen in rheumatoid arthritis (RA) patients in clinical trials with these agents. Combination therapy in the AIA model generally resulted in additive effects, but some parameters showed a greater-than-additive benefit. CONCLUSION: The results provide preclinical support for the hypothesis that IL-1Ra administered in combination with PEG sTNFRI might provide substantially more clinical benefit to RA patients than either agent alone at blood levels that are currently achievable in patients.     

Arthritis in mice that are deficient in interleukin-1 receptor antagonist is dependent on genetic background

OBJECTIVE: To determine the effect of deletion of interleukin-1 receptor antagonist (IL-1Ra) protein in an animal model of rheumatoid arthritis. METHODS: BALB/c mice deficient in IL-1Ra (IL-1Ra(-/-)) were bred with collagen-induced arthritis (CIA)-susceptible DBA/1 mice and B10 mice transgenic for HLA-DRB1*0101 (B10.DR1). After generation of IL-1Ra(-/-) mice on the DBA/1 and B10.DR1 backgrounds, the mice were observed for the development of spontaneous arthritis and immunized for induction of CIA. RESULTS: We found that although BALB/c mice deficient in IL-1Ra (BALB/c(-/-)) spontaneously developed chronic inflammatory arthritis, DBA/1 IL-1Ra-deficient (DBA/1(-/-)) and B10.DR1 IL-1Ra-deficient (B10.DR1(-/-)) mice did not. Splenocytes from BALB/c(-/-) mice produced elevated levels of IL-2, IL-4, IL-6, IL-10, IL-17, and granulocyte-macrophage colony-stimulating factor in response to anti-CD3 stimulation. After immunization with type II collagen (CII), DBA/1(-/-) and B10.DR1(-/-) mice had a significantly earlier onset of CIA, and with increased severity compared with IL-1Ra(+/+) mice. Immunization of BALB/c(-/-) mice with CII did not aggravate spontaneous arthritis. All of the immunized mice developed antibodies to CII that correlated with arthritis severity. Levels of antibody to CII in the BALB/c(-/-) strain were relatively low. CONCLUSION: These data indicate that the spontaneous arthritis of IL-1Ra deficiency is highly dependent on non-major histocompatibility complex genes and that autoimmunity to CII is not the major disease-inducing event. Class II immune response genes are more important for the regulation of CIA, and although these 2 models of arthritis share many pathogenic mechanisms, they also have significant differences.     

Function of interleukin-20 as a proinflammatory molecule in rheumatoid and experimental arthritis

OBJECTIVE: The pathogenesis of rheumatoid arthritis (RA) reflects an ongoing imbalance between proinflammatory and antiinflammatory cytokines. Interleukin-20 (IL-20) has proinflammatory properties for keratinocytes. In this study, we sought to determine whether IL-20 is involved in RA. METHODS: We analyzed IL-20 levels in synovial fluid from RA patients. IL-20 and its receptors were detected in RA synovial fibroblasts (RASFs), using immunohistochemical staining. The effect of IL-20 on endothelial cells, neutrophils, and RASFs was investigated using MTT and migration assays. The expression of IL-20 and its receptors in healthy rats and in rats with collagen-induced arthritis (CIA) was also analyzed. Soluble IL-20 receptor type I (sIL-20RI) or sIL-20RII was administered to rats with CIA by intramuscular electroporation, and the severity of arthritis was monitored. RESULTS: RA patients expressed significantly higher levels of synovial fluid IL-20 than did the rheumatic disease controls. IL-20 and its receptors were expressed in the synovial membranes and RASFs. IL-20 induced RASFs to secrete monocyte chemoattractant protein 1, IL-6, and IL-8, and it promoted neutrophil chemotaxis, RASF migration, and endothelial cell proliferation. Both IL-20 and IL-20RI were up-regulated in the rat CIA model. In vivo, electroporated sIL-20RI plasmid DNA decreased the severity of arthritis in the rats with CIA. CONCLUSION: IL-20 was up-regulated in the synovial fluid of RA patients and acted as a chemokine that attracted the migration of neutrophils and RASFs in vitro. The rat CIA model demonstrated that IL-20 was involved in the pathogenesis of arthritis, because sIL-20RI significantly reduced arthritis in rats with CIA. Thus, IL-20 may modulate the incidence and severity of arthritis and play important roles at local sites of inflammation.     

Effects of soluble interleukin-1 type II receptor on rabbit antigen-induced arthritis: clinical, biochemical and histological assessment.

OBJECTIVES: To investigate the effects of soluble interleukin-1 (IL-1) type II receptor (sIL-1RII) on a number of clinical, biochemical and histological parameters in rabbit antigen-induced arthritis. METHODS: Arthritis was induced by intra-articular injection of methylated bovine serum albumin (mBSA) into rabbits pre-sensitized to the same antigen. An initial i.v. bolus of sIL-1RII was administered, followed by s.c. mini-pump dosing for 14 days, starting at the time of the arthritis induction. Animals received vehicle (saline 500 microl + 5 microl/h), low-dose sIL-1RII (13.4 microg + 1.34 microg/h) or high-dose sIL-1RII (40.2 microg + 4.02 microg/h). RESULTS: Marked, dose-related inhibition of joint diameter, plasma prostaglandin E2 (PGE2), and synovial fluid IL-1alpha and IL-1beta concentrations were seen after administration of sIL-1RII. However, synovial fluid PGE2 concentrations and synovial fluid cell counts were not affected. A significant inhibitory effect was also seen histologically on soft-tissue swelling and joint damage with high-dose sIL-1RII. CONCLUSIONS: These results demonstrate that IL-1 plays an important role in the pathogenesis of rabbit antigen-induced arthritis, thus confirming it as an excellent animal model with respect to evaluating anti-cytokine therapies for rheumatoid arthritis.     

Soluble type II interleukin 1 (IL-1) receptor binds and blocks processing of IL-1 beta precursor and loses affinity for IL-1 receptor antagonist.

Two IL-1 receptors have been identified, termed type I and type II. The extracellular domain of the type II IL-1 receptor is released from certain cells and can function as a specific inhibitor of IL-1 beta activity. We assessed the ligand-binding properties of the type II membrane-bound and soluble IL-1 receptor (sIL-1R) from the human B cell line Raji by competition. Upon release, the affinity of sIL-1R for IL-1 alpha and IL-1 beta remained constant, and both soluble and cell surface IL-1 receptors bound to the same regions on the IL-1 beta molecule as defined by binding of a series of IL-1 beta mutant molecules. However, the affinity of sIL-1R for the IL-1 receptor antagonist (IL-1ra) decreased by a factor of 2000 when compared with the cell surface receptor. Type II sIL-1R and IL-1ra had an additive effect in inhibiting the binding of IL-1 beta to cell surface IL-1 receptors. In contrast, the combination of recombinant type 1 sIL-1R with IL-1ra abrogated the inhibition seen with each of the individual agents alone. The type II cell surface IL-1 receptor failed to bind the biologically inactive IL-1 beta precursor molecule, but binding to the IL-1 beta precursor was observed on cellular release of the receptor; this was confirmed with 35S-labeled IL-1 beta. Binding of IL-1 beta precursor by sIL-1R inhibited the precursor's ability to be processed to the mature, biologically active 17-kDa species. These observations suggest that the type II sIL-1R inhibits IL-1 beta at two steps, by preventing processing of propeptide and by blocking the interaction of mature IL-1 beta with type I IL-1 receptor. In addition, type II sIL-1R does not interfere with inhibition mediated by IL-1ra.     

IL-17 production from activated T cells is required for the spontaneous development of destructive arthritis in mice deficient in IL-1 receptor antagonist

IL-17 is a T cell-derived, proinflammatory cytokine that is suspected to be involved in the development of various inflammatory diseases. Although there are elevated levels of IL-17 in synovial fluid of patients with rheumatoid arthritis, the pathogenic role of IL-17 in the development of rheumatoid arthritis remains to be elucidated. In this report, the effects of IL-17 deficiency were examined in IL-1 receptor antagonist-deficient (IL-1Ra(-/-)) mice that spontaneously develop an inflammatory and destructive arthritis due to unopposed excess IL-1 signaling. IL-17 expression is greatly enhanced in IL-1Ra(-/-) mice, suggesting that IL-17 activity is involved in the pathogenesis of arthritis in these mice. Indeed, the spontaneous development of arthritis did not occur in IL-1Ra(-/-) mice also deficient in IL-17. The proliferative response of ovalbumin-specific T cells from DO11.10 mice against ovalbumin cocultured with antigen-presenting cells from either IL-1Ra(-/-) mice or wild-type mice was reduced by IL-17 deficiency, indicating insufficient T cell activation. Cross-linking OX40, a cosignaling molecule on CD4(+) T cells that plays an important role in T cell antigen-presenting cell interaction, with anti-OX40 Ab accelerated the production of IL-17 induced by CD3 stimulation. Because OX40 is induced by IL-1 signaling, IL-17 induction is likely to be downstream of IL-1 through activation of OX40. These observations suggest that IL-17 plays a crucial role in T cell activation, downstream of IL-1, causing the development of autoimmune arthritis.     

Prevention of murine collagen-induced arthritis in the knee and ipsilateral paw by local expression of human interleukin-1 receptor antagonist protein in the knee

Objective. To determine the efficacy of local human interleukin-1 receptor antagonist (HuIL-1Ra) gene therapy in murine collagen-induced arthritis (CIA). Methods. DBA/1 mice were immunized against bovine type II collagen. Before the onset of arthritis, NIH/3T3 fibroblasts transfected with pMFG-IRAP were transplanted into the knee cavity. Normal NIH/3T3 cells served as controls. Paws were evaluated macroscopically for redness, swelling, and deformities during the course of arthritis. Swelling of the knee joints was measured by external gamma counting of ^99mtechnetium accumulation in the joint. Paws and knee joints were dissected and processed for histologic studies to evaluate inflammation and cartilage destruction. Results. The NIH/3T3 fibroblasts survived in the joint cavity of DBA mice for at least 7 days. The transduced cells expressed immunoreactive and bioactive HuIL-1Ra in the knee joint, and produced sufficient amounts to block the effect of 1 ng of recombinant murine IL-1α on chondrocyte proteoglycan synthesis. The onset of CIA was almost completely prevented in knee joints containing HuIL-1Ra-producing cells, whereas joints containing normal cells showed severe inflammation and destruction of cartilage. Moreover, onset of CIA in the draining joints (ipsilateral paws) of the HuIL-1Ra gene-bearing knees was also prevented. Conclusion. Local production of HuIL-1Ra in the knee was able to ameliorate the effects of IL-1 on cartilage and could prevent the onset of CIA not only in that knee, but also in the “draining” paw. This indicates the feasibility of gene transfer as a therapeutic approach to modulating arthritis.     

The effects of treatment with interleukin-1 receptor antagonist on the inflamed synovial membrane in rheumatoid arthritis

OBJECTIVE: To evaluate the effects of treatment with interleukin-1 receptor antagonist (IL-1Ra) on synovial tissue in rheumatoid arthritis (RA). METHODS: Twelve patients with RA entering a randomized clinical trial of human recombinant IL-1Ra underwent synovial biopsies before and after treatment. Cellular infiltration and adhesion molecule expression were evaluated after immunohistochemical staining. RESULTS: There was a notable reduction in intimal layer macrophages and subintimal macrophages and lymphocytes after treatment with IL-1Ra at 150 mg/day (n=3). Increased cellular infiltration was observed in all patients receiving placebo (n=3); variable changes were observed after IL-1Ra 30 mg/day (n=6). In a limited study of adhesion molecule expression, down-regulation of E-selectin and vascular cell adhesion molecule-1 was observed after treatment with IL-1Ra 150 mg/day, but not after IL-1Ra 30 mg/day or placebo. The apparent arrest of progressive joint damage seen in four patients after treatment with IL-1Ra was associated with reduced intimal layer macrophage accumulation in all patients. CONCLUSION: Treatment of RA with IL-1Ra resulted in reduced mononuclear cell infiltration of synovial membrane, which may represent the in vivo inhibition of biologically relevant IL-1ss-mediated pathogenic effects.