Blockage of interleukin-6 receptor ameliorates joint disease in murine collagen-induced arthritis

From physiology to disease and targeted therapy: interleukin-6 in inflammation and inflammation-associated carcinogenesis

Since its discovery in 1986, originally as B cell stimulating factor 2, the knowledge on IL-6 for immune homeostasis and its pathophysiological implications has rapidly increased. It is now clear that IL-6, alone or in combination with other cytokines, is an architect for shaping and generating immune responses which exerts profound activities on the induction of acute-phase reactions, the differentiation of B lymphocytes, the modulation of T cell apoptosis, the activation of T helper cells and the balance between regulatory T cells and Th17 cells. In parallel to the identification of these physiologic functions, IL-6 has emerged as a critical mediator for perpetuating chronic inflammation and autoimmunity and is increasingly recognized as a key cytokine for linking chronic inflammation to cancer development. In this review, we begin by briefly summarizing the molecular events of IL-6 regulation and signaling and then describe the role of IL-6 in orchestrating innate and adaptive immune responses and its immunopathological relevance for chronic inflammatory diseases. We further outline how IL-6 links chronic inflammation and cancer development and finally provide an outlook on novel therapeutic strategies targeting IL-6 signaling for the treatment of chronic inflammatory diseases and cancer.

Mechanisms of tissue damage in arthritis

The destruction of articular structures in the course of inflammatory arthritides such as rheumatoid arthritis (RA) or seronegative spondyloarthropathies is the most serious direct consequence of these diseases. Indeed, joint damage constitutes the "organ damage" of RA and-just like in all other diseases with organ involvement-such damage will usually be irreversible, cause permanent loss of function and subsequent disability. Research has identified a number of mechanisms and mediators of damage to articular structures such as bone and cartilage, ranging from proinflammatory cytokines, signal transduction pathways and cells types, which will be discussed in this review.

IL-6 signal blockade ameliorates the enhanced osteoclastogenesis and the associated joint destruction in a novel FcγRIIB-deficient rheumatoid arthritis mouse model

OBJECTIVE

We earlier found that TNFα but not interleukin (IL)-17 is indispensable in the pathogenesis of spontaneously occurring rheumatoid arthritis (RA)-like disease in our newly established FcγRIIB-deficient C57BL/6 (B6) mouse model, designated KO1. Here, we examined the role of IL-6 in the pathogenesis of RA features in KO1, with particular reference to cartilage and bone destruction in arthritic joints.

METHODS

To evaluate the preventive effect of MR16-1, a rat anti-mouse IL-6 receptor (IL-6R) mAb, 4-month-old preclinical KO1 mice were divided into three groups: the first treated with MR16-1 for 6 months, the second treated with normal rat IgG, as a control, and the third left untreated. The incidence and severity of arthritis, immunological abnormalities, and transcription levels of receptor activator of NF-κB ligand (RANKL), osteoprotegerin (OPG), and inflammatory cytokines/chemokines in ankle joint tissues were compared among the three groups. The therapeutic effect of MR16-1 was examined by treating 7-month-old KO1 mice in the early stages of arthritis for 2 months.

RESULTS

Compared with the findings in the KO1 mice left untreated or treated with normal rat IgG, the development of arthritis was markedly suppressed in mice with MR16-1 treatment started from preclinical stages. The suppression was associated with the decrease in production of autoantibodies, rheumatoid factors (RF), and anti-cyclic citrullinated peptide (CCP). Histologically, marked synovitis, pannus formation, and cartilage and bone destruction associated with the increase in tartrate-resistant acid phosphatase (TRAP)-positive osteoclast generation were evident in the two control groups; however, these findings were virtually absent in MR16-1-treated mice. Real-time PCR analysis revealed that the up-regulated expression levels of MCP-1, IL-6, and TNFα, and the aberrantly high RANKL/OPG expression ratio in synovial joint tissues from the two control groups of mice with overt arthritis were significantly suppressed in MR16-1-treated mice. In mice with therapeutic MR16-1 treatment, there was no progression in arthritis score and the RANKL/OPG ratio in joint tissues was significantly suppressed.

CONCLUSIONS

Administration of an anti-IL-6R mAb ameliorated spontaneously occurring RA-like disease features, indicating that IL-6, as well as TNFα, plays a pivotal role in the pathogenesis of RA in KO1 mice. Current studies showed that, in addition to the role in enhancing autoantibody production, IL-6 promotes synovial tissue inflammation and osteoclastogenesis, leading to the severe synovitis with pannus formation and the progressive cartilage and bone destruction in multiple joints.

Targeting IL-6 by both passive or active immunization strategies prevents bleomycin-induced skin fibrosis

Introduction

Interleukin-6 (IL-6) is a pleiotropic cytokine for which preliminary data have suggested that it might contribute to systemic sclerosis (SSc). Our aims were to investigate, firstly, IL-6 expression in patients with SSc and, secondly, the efficacy of both passive and active immunization against IL-6 to reduce skin fibrosis in complementary mouse models of SSc.

Methods

Human serum levels and skin expression of IL-6 were determined by enzyme-linked immunosorbent assay and immunohistochemistry, respectively. We first evaluated the antifibrotic properties of the monoclonal anti-IL-6R antibody, MR16-1, in the bleomycin-induced dermal fibrosis mouse model, reflecting early and inflammatory stages of SSc. Then, we assessed the efficacy of MR16-1 in tight skin-1 (Tsk-1) mice, an inflammation-independent model of skin fibrosis. Additionally, we have developed an innovative strategy using an anti-IL-6 peptide-based active immunization. Infiltrating leukocytes, T cells, and B cells were quantified, and IL-6 levels were measured in the serum and lesional skin of mice after passive or active immunization.

Results

Serum and skin levels of IL-6 were significantly increased in patients with early SSc. Treatment with MR16-1 led in the bleomycin mouse model to a 25% (P = 0.02) and 30% (P = 0.007) reduction of dermal thickness and hydroxyproline content, respectively. MR16-1 demonstrated no efficacy in Tsk-1 mice. Thereafter, mice were immunized against a small peptide derived from murine IL-6 and this strategy led in the bleomycin model to a 20% (P = 0.02) and 25% (P = 0.005) decrease of dermal thickness and hydroxyproline content, respectively. Passive and active immunization led to decreased T-cell infiltration in the lesional skin of mice challenged with bleomycin. Upon bleomycin injections, serum and skin IL-6 levels were increased after treatment with MR16-1 and were significantly reduced after anti-IL-6 active immunization.

Conclusions

Our results support the relevance of targeting IL-6 in patients with early SSc since IL-6 is overexpressed in early stages of the disease. Targeting IL-6 by both passive and active immunization strategies prevented the development of bleomycin-induced dermal fibrosis in mice. Our results highlight the therapeutic potential of active immunization against IL-6, which is a seductive alternative to passive immunization.

Academic Clinical Trials and Drug Regulations in Japan: Impacts of Introducing the Investigational New Drug System

In Japan, academic clinical trials do not generally need to be conducted under good clinical practice and cannot therefore be used for regulatory submission for marketing authorization of new medical products. We reviewed 2 differential regulatory systems governing clinical trials in Japan and the development histories of 2 case products whose clinical trials at the early development stage were conducted by academic researchers and transferred to the private sector for further development toward commercialization in Japan. We further estimated that the introduction of the investigational new drug system may have accelerated the development of tocilizumab, an antibody drug for rheumatoid arthritis, at best by 2 years by utilizing the results of early exploratory clinical trials conducted by academic investigators. Similarly, an enlarged indication for JACE^®, a cultured epithelium autograft for severe burns, would have been expected at launch by utilizing the results of academic trials investigating various indications. These possible impacts and estimations would warrant introducing the investigational new drug system into Japan drug regulatory system.

Interleukin-6 receptor blockade enhances CD39+ regulatory T cell development in rheumatoid arthritis and in experimental arthritis

OBJECTIVE

The rationale for blocking interleukin-6 (IL-6) in rheumatoid arthritis (RA) lies chiefly in the proinflammatory effect of this cytokine. Few studies have evaluated the consequences of anti-IL-6 receptor (IL-6R) antibody treatment on Treg cells. This study was undertaken to elucidate the mechanism of action of anti-IL-6R antibody treatment by studying the effects on Treg cells in an experimental arthritis model and in patients with RA.

METHODS

Mice with collagen-induced arthritis (CIA) were treated with a mouse anti-IL-6R antibody (MR16-1), and changes in Treg, Th1, and Th17 cells were assessed at key time points during the course of the disease. Peripheral blood from 15 RA patients was collected on day 0 and after 3 months of tocilizumab treatment for flow cytometry analysis of Th17 and Treg cells.

RESULTS

In MR16-1-treated mice, Th17 cell frequencies were unchanged, whereas Treg cell frequencies were increased. The Treg cell phenotype showed marked changes, with an increase in the frequency of CD39+ Treg cells in the lymph nodes and spleen. Interestingly, similar CD39+ Treg cell expansion was observed in RA patients who were tocilizumab responders at 3 months, with no change in Th17 cell frequency. Moreover, fluorescence-activated cell-sorted CD39+ Treg cells from responder RA patients were functionally able to suppress the proliferation of conventional T cells.

CONCLUSION

In both CIA and RA, the frequency of functionally suppressive CD39+ Treg cells is increased as a result of anti-IL-6R treatment, whereas Th17 cells are unaffected. The modification of Treg cell frequency and phenotype may be one of the mechanisms involved in the therapeutic effect of IL-6 blockade in RA.

Anti-interleukin-6 receptor antibody (MR16-1) promotes muscle regeneration via modulation of gene expressions in infiltrated macrophages

BACKGROUND

Although rat anti-mouse IL-6 receptor (IL-6R) antibody (MR16-1) has been reported to effectively ameliorate various tissue damages, its effect on skeletal muscle regeneration has not been determined. Moreover, the localization, persistence and duration of action of this reagent in damaged tissues after systemic administration have not been assessed.

METHODS

The MR16-1 was administered i.p. immediately after cardiotoxin (CTX)-induced muscle damage on mice.

RESULTS

MR16-1 administered i.p. was observed only to the damaged muscle. This delivered MR16-1 was dramatically decreased from 3 to 7days post-injury concomitantly with a reduction of IL-6R expression. This reduction of the MR16-1 level in the damaged muscle was not rescued by additional administration of MR16-1, suggesting the short half-life of MR16-1 was not the factor for the remaining levels. In addition, a significant inhibitory effect of MR16-1 on phosphorylation of the signal transducer and activator of transcription 3 was observed in the macrophage-enriched area of damaged muscle 3days after injury. Finally, the acceleration of muscle regeneration observed at day 7 post-injury following MR16-1 treatment was associated with reduced expression of fibrosis-related genes, such as interleukin-10 and arginase, in the infiltrated macrophages.

CONCLUSIONS

These results suggest that MR16-1 which was found primarily localized in infiltrated macrophages in the damaged muscle might facilitate muscle regeneration via immune modulation.

GENERAL SIGNIFICANCE

These findings are deemed to provide further insight into the understanding not only of MR16-1 treatment on muscle regeneration, but also of the other anti-cytokine treatment on the cytokine-related disease.

Interleukin 6 and rheumatoid arthritis

Interleukin-6 (IL-6) is a representative cytokine featuring pleiotropic activity and redundancy. A transient synthesis of IL-6 contributes to host defense against infectious agents and tissue injuries by inducing acute phase reactions and immunological and hematopoietic responses. However, uncontrolled persistent production of IL-6 may lead to the development of several immune-mediated diseases. Rheumatoid arthritis (RA) is a chronic disease with joint and systemic inflammation resulting from immunological abnormalities and it has been found that IL-6 plays a key role in the development of this disease. Clinical trials in various parts of the world of tocilizumab, a humanized anti-IL-6 receptor antibody, have proved its efficacy and tolerable safety either as monotherapy or in combination with disease-modifying antirheumatic drugs. As a result, it is currently used as a first-line biologic for the treatment of moderate-to-severe RA in more than 100 countries. Clarification of the mechanism(s) through which tocilizumab exerts its effect on RA and of the reason(s) why IL-6 is continuously produced in RA can be expected to lead to the best use of this agent for RA patients and aid in investigations into the pathogenesis of RA.

Lipopolysaccharide accelerates collagen-induced arthritis in association with rapid and continuous production of inflammatory mediators and anti-type II collagen antibody

Collagen-induced arthritis (CIA) is an animal model for rheumatoid arthritis (RA). Lipopolysaccharide (LPS) is known to accelerate CIA; however, the pathogenetic mechanisms are not yet fully understood. In this study, type II collagen (CII)-immunized mice were found to have marked increases in degree of expression of mRNA of inflammatory mediators such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and macrophage inflammatory protein-2 (MIP-2) in their arthritic paws and of serum anti-CII antibody concentration before the onset of arthritis induced by LPS injection. The gene expression was rapid and continuous after direct activation of nuclear factor κB. The amounts of mRNA of TNF-α, IL-1β, and MIP-2, as well as of matrix metalloproteinases and the receptor activator of nuclear factor κB ligand, increased with the development of arthritis, correlated positively with clinical severity and corresponded with histopathological changes. Moreover, anti-TNF-α neutralizing antibody inhibited the development of LPS-accelerated CIA and a single injection of recombinant mouse TNF-α induced increases in anti-CII antibody concentrations, suggesting TNF-α may contribute to the development of arthritis by both initiation of inflammation and production of autoantibodies. These data suggest that exacerbation of RA by LPS is associated with rapid and continuous production of inflammatory mediators and autoantibodies.

Interleukin-6: from basic biology to selective blockade of pro-inflammatory activities

Cytokines receptors exist in membrane bound and soluble form. A soluble form of the human IL-6R is generated by limited proteolysis and alternative splicing. The complex of IL-6 and soluble IL-6R stimulates target cells not stimulated by IL-6 alone, since they do not express the membrane bound IL-6R. We have named this process trans-signaling. Soluble gp130 is the natural inhibitor of IL-6/soluble IL-6R complex responses. Recombinant soluble gp130 protein is a molecular tool to discriminate between gp130 responses via membrane bound and soluble IL-6R responses. Neutralizing monoclonal antibodies for global blockade of IL-6 signaling and the sgp130Fc protein for selective blockade of IL-6 trans-signaling have been used in several animal models of human diseases. Using the sgp130Fc protein or sgp130Fc transgenic mice we demonstrate in models of inflammatory bowel disease, peritonitis, rheumatoid arthritis, atherosclerosis pancreatitis, colon cancer, ovarian cancer and pancreatic cancer, that IL-6 trans-signaling via the soluble IL-6R is the crucial step in the development and the progression of the disease. Therefore, sgp130Fc is a novel therapeutic agent for the treatment of chronic inflammatory diseases and cancer and it undergoes phase I clinical trials as an anti-inflammatory drug since June 2013.

Targeting interleukin-6 in inflammatory autoimmune diseases and cancers

Interleukin-6 (IL-6) is a pleiotropic cytokine with significant functions in the regulation of the immune system. As a potent pro-inflammatory cytokine, IL-6 plays a pivotal role in host defense against pathogens and acute stress. However, increased or deregulated expression of IL-6 significantly contributes to the pathogenesis of various human diseases. Numerous preclinical and clinical studies have revealed the pathological roles of the IL-6 pathway in inflammation, autoimmunity, and cancer. Based on the rich body of studies on biological activities of IL-6 and its pathological roles, therapeutic strategies targeting the IL-6 pathway are in development for cancers, inflammatory and autoimmune diseases. Several anti-IL-6/IL-6 receptor monoclonal antibodies developed for targeted therapy have demonstrated promising results in both preclinical studies and clinical trials. Tocilizumab, an anti-IL-6 receptor antibody, is effective in the treatment of various autoimmune and inflammatory conditions notably rheumatoid arthritis. It is the only IL-6 pathway targeting agent approved by the regulatory agencies for clinical use. Siltuximab, an anti-IL-6 antibody, has been shown to have potential benefits treating various human cancers either as a single agent or in combination with other chemotherapy drugs. Several other anti-IL-6-based therapies are also under clinical development for various diseases. IL-6 antagonism has been shown to be a potential therapy for these disorders refractory to conventional drugs. New strategies, such as combination of IL-6 blockade with inhibition of other signaling pathways, may further improve IL-6-targeted immunotherapy of human diseases.

Effect of interleukin-6 receptor blockade on feto-maternal outcomes in a rat model of intrauterine inflammation

AIM

To study the effect of blocking the inflammatory cascade with interleukin-6 receptor antibody (anti-IL-6R) on feto-maternal outcomes in a rat model.

METHODS

Pregnant Sprague-Dawley rats (n = 38) were injected intraperitoneally (day 22) (control, anti-IL-6R 30 μg/kg, lipopolysaccharide [LPS] 250 μg/kg or 500 μg/kg alone or combined with anti-IL-6R) followed by preterm caesarian performed 12 h later. Resuscitated pups (n = 179) were given to surrogate mothers. Primary outcomes were maternal and pup mortality.

RESULTS

Fifty percent of pregnant rats died after LPS 500 μg/kg + anti-IL-6R injection but none in other groups. Neonatal mortality at 24 h was 63% and 86% in LPS 500 μg/kg and LPS 500 μg/kg + anti-IL-6R groups, respectively (P < 0.05). Surviving pups in the latter group presented a severe growth deficit compared to the LPS 500 μg/kg group (P < 0.01) and showed no difference with controls for open field testing. Maternal cytokine analysis after LPS 500 μg/kg + anti-IL-6R injection showed a tendency for increased IL-1 production (P = 0.06).

CONCLUSION

Paradoxically, the association of pregnancy, inflammation and anti-IL-6R increases the inflammatory effects of LPS.

Formal Synthesis of (+)-Madindoline A a Potent IL-6 Inhibitor Utilizing Enzymatic Discrimination of Quaternary Carbon

A formal synthesis of (+)-madindoline A was achieved. The Sunazuka's key intermediate (4 R,5 S)-(–)-3-butyl-4-( tert-butyldimethylsiloxy)-5-methoxycarbonyl-2,5-dimethyl-2-cyclopentenone was synthesized from easily available (2 S,3 S)-3-acetoxy-2-ethenyl-2-methylcyclopentanone. The starting material was reliably supplied by a chemo-enzymatic procedure in enantiomerically pure form. The synthesis was performed by straightforward transformations involving enone formation and regioselective introduction of the two alkyl side chains.

IL-6 receptor antagonist as adjunctive therapy with clotting factor replacement to protect against bleeding-induced arthropathy in hemophilia

BACKGROUND

The most common morbidity that results from hemophilia is bleeding-induced hemophilic arthropathy (HA), which once established may not be interrupted completely even by prophylactic clotting factor replacement. Specific therapies to oppose inflammatory cytokines, including Interleukin 6 (IL-6) receptor antagonists, have become important in the management of inflammatory arthritides.

OBJECTIVES

We investigated combining therapy using MR16-1, a rat IgG antibody directed against mouse IL-6 receptor (anti-IL-6R), with factor VIII (FVIII) replacement to protect against bleeding-induced arthropathy in hemophilia A mice.

METHODS

Three recurrent hemarthroses were induced in the knee joint capsule of FVIII knockout mice. Treatment at the time of each hemorrhage included either: no treatment; FVIII replacement given at the time of hemorrhage; FVIII replacement at hemorrhage plus anti-IL-6R as 4-weekly injections; FVIII replacement with non-specific control antibody (rat IgG); and anti-IL-6R alone without FVIII replacement. Six weeks following the first hemarthosis, joints were harvested and histopathology was scored for synovitis, for cartilage integrity and for macrophage infiltration.

RESULTS

Animals that received anti-IL-6R as an adjunct to FVIII replacement demonstrated the best survival and the least acute joint swelling and pathology on histologic examination of the synovium and cartilage (P < 0.05 for each parameter). All histopathologic parameters in the mice receiving FVIII+anti-IL-6R were limited and were comparable to findings in injured hemostatically normal mice. The major benefits of adjunctive anti-IL-6R were decreasing synovial hyperplasia, hemosiderin deposition and macrophage infiltration.

CONCLUSIONS

Short-course specific inhibition of inflammatory cytokines as an adjunct to replacement hemostasis may be an approach to minimize hemophilic joint degeneration.

Murine tumor necrosis factor α-induced adipose-related protein (tumor necrosis factor α-induced protein 9) deficiency leads to arthritis via interleukin-6 overproduction with enhanced NF-κB, STAT-3 signaling, and dysregulated apoptosis of macrophages

OBJECTIVE

To elucidate the role of tumor necrosis factor α-induced adipose-related protein (TIARP; or tumor necrosis factor α-induced protein 9 [TNFAIP-9]) in the development and pathogenesis of arthritis.

METHODS

We generated TIARP-deficient (TIARP(-/-) ) mice and investigated several organs in aged mice. Peritoneal macrophages were collected and cultured with lipopolysaccharide (LPS) and TNFα, and then the production of cytokines and subsequent NF-κB signal transduction were analyzed. We also examined the susceptibility of young TIARP(-/-) mice to collagen-induced arthritis (CIA). Draining lymph nodes and splenocytes were isolated and cultured, and serum levels of anti-type II collagen (anti-CII) antibodies, interleukin-6 (IL-6), and TNFα on day 60 were measured. We further investigated the effects of anti-IL-6 receptor monoclonal antibody (mAb) on the development of arthritis in TIARP(-/-) mice. IL-6/STAT-3 signaling was also analyzed using TIARP(-/-) macrophages.

RESULTS

TIARP(-/-) mice developed spontaneous enthesitis and synovitis, had high serum levels of IL-6, had increased CD11b+ cell counts in the spleen, and showed enhanced LPS- and TNFα-induced IL-6 expression in macrophages. Sustained degradation of IκBα with dysregulated apoptosis was also noted in TIARP(-/-) macrophages. CIA was clearly exacerbated in TIARP(-/-) mice, accompanied by marked neutrophil and macrophage infiltration in joints. The levels of anti-CII antibodies in serum were unchanged, whereas autoreactive Th1 cell and Th17 cell responses were higher in TIARP(-/-) mice. Treatment with anti-IL-6 receptor mAb prevented the development of CIA in TIARP(-/-) mice, and TIARP(-/-) macrophages showed increased IL-6-induced STAT-3 phosphorylation.

CONCLUSION

These findings suggest that TIARP acts as a negative regulator of arthritis by suppressing IL-6 production, its signaling and TNFα-induced NF-κB signaling, resulting in enhanced apoptosis in macrophages.

Therapeutic effects of extracts from Radix Toddaliae Asiaticae on collagen-induced arthritis in Balb/c mice

AIM OF THE STUDY

Radix Toddaliae Asiaticae (RTA), also named "Sanbaibang", is the dry root bark of Toddalia asiatica (L.) Lam. and has long been used as a traditional ethnic Chinese medicine for its considerable activity to alleviate pain and inflammation for patients suffering from rheumatism. It contains coumarin, alkaloids, triterpenes and volatile oils. Information regarding the anti-arthritis activity of RTA in vivo or in vitro is limited yet. In the present study, the aim is to investigate the therapeutic potential and underlying mechanisms of the ethyl alcohol extract (EtOH) and ethyl acetate fraction (EtOAc) from RTA on collagen II-induced arthritis (CIA) in mice.

MATERIALS AND METHODS

CIA animal model was performed by subcutaneous injection of type II bovine collagen (CII) on the 1st day and the 14th day of the experiment. Ethyl alcohol extract (542.8, 271.4, 135.7 mg/kg), ethyl acetate fraction (260.8, 130.4, 65.2 mg/kg) was orally administrated from the second antigen immunization for 3 weeks. Progression of edema of paws and knee joints was measured using a vernier caliper every 3 days from the 10th day after the first injection to the end of the experiment. The spleen index was measured and the knee joint changes were observed by pathological sections. ELISA was used to measure cytokines including tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6) and interleukin-10 (IL-10) in mice serum according to the manufacturer's instructions.

RESULTS

Administration of ethyl alcohol extract and ethyl acetate fraction remarkably reduced paws and joints swelling and decreased the spleen indexes. Histopathological examination demonstrated that RTA effectively protected bone and cartilage of knee joint from erosion, lesion and deformation versus those from the control group. Besides, the concentration of cytokines like TNF-α, IL-1β, IL-6 were significantly lower than the ones from the control group respectively, while cytokine like IL-10 was remarkably higher compare with the control group.

CONCLUSION

In this present study, it is demonstrated that administration of RTA has potential and therapeutic effect on CIA. The data suggests that RTA could have a contributory ethno-pharmacological role in improved management of RA patients.

Increased synovial expression of nuclear receptors correlates with protection in pristane-induced arthritis: a possible novel genetically regulated homeostatic mechanism

OBJECTIVE

To use microarray analyses of gene expression to characterize the synovial molecular pathways regulated by the arthritis regulatory locus Cia25 and to determine how it operates to control disease severity and joint damage.

METHODS

Synovial tissues from DA rats and DA.ACI(Cia25) rats obtained 21 days after induction of pristane-induced arthritis were used for RNA extraction and hybridization to Illumina RatRef-12 Expression BeadChips (22,228 genes). Genes with a P value≤0.01 and a fold difference in expression≥1.5 between DA rats and DA.ACI(Cia25) rats were considered significant.

RESULTS

Interleukin-1β (IL-1β) (7.4-fold), IL-6 (67-fold), Ccl2, Cxcl10, Mmp3, Mmp14, and innate immunity genes were expressed at increased levels in DA rats and at significantly lower levels in DA.ACI(Cia25) congenic rats. DA.ACI(Cia25) rats had increased expression of 10 nuclear receptor (NR) genes, including those known to interfere with NF-κB activity and cytokine expression, such as Lxra, Pparg, and Rxrg. DA.ACI(Cia25) rats also had increased expression of NR targets, suggesting increased NR activity. While Vdr was not differentially expressed, a Vdr expression signature was detected in congenic rats, along with up-regulation of mediators of vitamin D synthesis.

CONCLUSION

This is the first description of the association between increased synovial levels of NRs and arthritis protection. The expression of NRs was inversely correlated with the expression of key mediators of arthritis, suggesting reciprocally opposing effects either via NF-κB or at the genomic level in the synovial tissue. We consider that the NR signature may have an important role in maintaining synovial homeostasis and an inflammation-free tissue. These processes are regulated by the Cia25 gene and suggest a new function for this gene.

Targeting interleukin-6: all the way to treat autoimmune and inflammatory diseases

Interleukin (IL)-6, a cytokine featuring redundancy and pleiotropic activity, contributes to host defense against acute environmental stress, while dysregulated persistent IL-6 production has been demonstrated to play a pathological role in various autoimmune and chronic inflammatory diseases. Targeting IL-6 is thus a rational approach to the treatment of these diseases. Indeed, clinical trials of tocilizumab, a humanized anti-IL-6 receptor antibody have verified its efficacy and tolerable safety for patients with rheumatoid arthritis, Castleman's disease and systemic juvenile idiopathic arthritis, resulting in approval of this innovative biologic for treatment of these diseases. Moreover, a considerable number of case reports and pilot studies of off-label use of tocilizumab point to the beneficial effects of tocilizumab for a variety of other phenotypically different autoimmune and chronic inflammatory diseases. Elucidation of the source of IL-6 and of mechanisms through which IL-6 production is dysregulated can thus be expected to lead to clarification of the pathogenesis of various diseases.

Interleukin-6: from an inflammatory marker to a target for inflammatory diseases

The incidence and diversity of chronic inflammatory diseases is increasing worldwide. However, the complexity of clinical symptoms has made it difficult to develop therapies that provide a substantial improvement for extended periods of time in a wide range of patient groups. Thus, there is a need for new therapies that target inflammatory responses without compromising immune defense. Interleukin (IL)-6, one of the first identified cytokines, has recently been recognized as a potential target in inflammatory disease. Here, I discuss how this cytokine has evolved from being a marker of inflammation to a successful target to control inflammation. I will summarize the results from the recent clinical studies using IL-6 receptor blockade, and describe potential mechanisms by which IL-6 can contribute to the progression of inflammatory diseases.

Concordance of preclinical and clinical pharmacology and toxicology of therapeutic monoclonal antibodies and fusion proteins: cell surface targets

Monoclonal antibodies (mAbs) and fusion proteins directed towards cell surface targets make an important contribution to the treatment of disease. The purpose of this review was to correlate the clinical and preclinical data on the 15 currently approved mAbs and fusion proteins targeted to the cell surface. The principal sources used to gather data were: the peer reviewed Literature; European Medicines Agency 'Scientific Discussions'; and the US Food and Drug Administration 'Pharmacology/Toxicology Reviews' and package inserts (United States Prescribing Information). Data on the 15 approved biopharmaceuticals were included: abatacept; abciximab; alefacept; alemtuzumab; basiliximab; cetuximab; daclizumab; efalizumab; ipilimumab; muromonab; natalizumab; panitumumab; rituximab; tocilizumab; and trastuzumab. For statistical analysis of concordance, data from these 15 were combined with data on the approved mAbs and fusion proteins directed towards soluble targets. Good concordance with human pharmacodynamics was found for mice receiving surrogates or non-human primates (NHPs) receiving the human pharmaceutical. In contrast, there was poor concordance for human pharmacodynamics in genetically deficient mice and for human adverse effects in all three test systems. No evidence that NHPs have superior predictive value was found.

Immunotherapeutic implication of IL-6 blockade

IL-6 is a cytokine featuring redundancy and pleiotropic activity. While IL-6 contributes to host defense against acute environmental stress, continuous IL-6 production plays a significant pathological role in various autoimmune and chronic inflammatory diseases. To counter this drawback, tocilizumab, a humanized anti-IL-6 receptor antibody, was developed. Clinical trials have verified the efficacy of tocilizumab for patients with rheumatoid arthritis, Castleman's disease and systemic juvenile idiopathic arthritis, resulting in approval of this innovative biologic for their treatment. Moreover, a considerable number of case reports and pilot studies have indicated the beneficial effects of tocilizumab on other autoimmune and chronic inflammatory diseases. Further clinical studies to evaluate the efficacy and safety of tocilizumab for these diseases are essential.

The pathogenesis of rheumatoid arthritis: new insights from old clinical data?

Despite their different targets, biologic agents used for blockade of TNF and IL-6, inhibition of T-cell co-stimulation and B-cell depletion all have similar beneficial effects on the outcome of rheumatoid arthritis (RA). This observation raises questions as to whether the targets of these therapies might all be involved in a common pathogenetic pathway. However, blockade of TNF and IL-6 has a similar inhibitory effect on joint damage progression in patients with either early or late disease. In comparison, B-cell depletion and inhibition of T-cell co-stimulation seem to have a somewhat delayed effect on joint damage (compared with cytokine inhibition), which suggests that these approaches affect upstream pathogenetic events. This article discusses these disparities and presents hypotheses as to whether clinical trial data can be used to determine at which point a biologic agent might interfere with the pathogenetic cascade in RA.

Safety and efficacy of tocilizumab for the treatment of rheumatoid arthritis

Because of the pathological role of IL-6 in rheumatoid arthritis (RA), tocilizumab (TCZ), a humanized anti-IL-6 receptor monoclonal antibody, was expected to improve inflammation and joint destruction of RA. Indeed, randomized clinical trials demonstrated the clinical efficacy of TCZ as monotherapy or combined with methotrexate (MTX) for RA patients with inadequate responses to disease-modifying antirheumatic drugs, MTX or tumor necrosis factor (TNF) inhibitors. Although long-term tolerability for TCZ is superior to that for TNF inhibitors, information regarding the potency of drug free remission of TCZ is limited at present. In terms of its safety profile, the general risk of infection when using TCZ is comparable to that of TNF inhibitors. TCZ has some advantage in RA patients who can not use MTX and are non-responders to TNF inhibitors. In conclusion, TCZ is one of the most prospective next generation biologics for the treatment of RA.

Tocilizumab for the treatment of rheumatoid arthritis and other systemic autoimmune diseases: current perspectives and future directions

Interleukin (IL)-6 is a cytokine featuring redundancy and pleiotropic activity. While IL-6, when transiently produced, contributes to host defense against acute environmental stress, continuous dysregulated IL-6 production plays a significant pathological role in several systemic autoimmune diseases. In response to the expectation that IL-6 blockade would constitute a novel therapeutic strategy for the treatment of these diseases, tocilizumab, a humanized anti-IL-6 receptor antibody, was developed. Clinical trials have verified the efficacy and the safety of tocilizumab for patients with rheumatoid arthritis, resulting in approval of this innovative biologic for the treatment of rheumatoid arthritis in more than 90 countries worldwide. Pathological analyses of the effect of IL-6 on the development of autoimmune diseases and a considerable number of case reports and pilot studies have also indicated the beneficial effects of this antibody on other systemic autoimmune diseases, including systemic lupus erythematosus, systemic sclerosis, polymyositis, and large-vessel vasculitis.

Suppressive effect of an orally active MEK1/2 inhibitor in two different animal models for rheumatoid arthritis: a comparison with leflunomide

OBJECTIVE AND DESIGN

To examine the effects of a mitogen-activated protein kinase/extracellular signal-regulated kinase kinase 1/2-inhibitor, JTP-74057, on inflammatory arthritis development, and compare its anti-arthritic effect with leflunomide.

MATERIALS

Human, mouse, and rat peripheral blood mononuclear cells (PBMCs) were used. Lewis rats and DBA/1J mice were used for animal models.

TREATMENT

JTP-74057 was tested between 0.1-100 nM in in-vitro studies. JTP-74057 (0.01-0.3 mg/kg) and leflunomide (2-10 mg/kg) were administered orally in vivo.

METHODS

PBMCs were stimulated with lipopolysaccharide. Adjuvant-induced arthritis (AIA) and type II collagen-induced arthritis (CIA) was induced in Lewis rats or DBA1/J mice, respectively.

RESULTS

JTP-74057 blocked tumor necrosis factor-α and interleukin-6 production from PBMCs. AIA and CIA development were suppressed almost completely by 0.1 mg/kg of JTP-74057 or 10 mg/kg of leflunomide. In the CIA, JTP-74057, but not leflunomide, suppressed collagen-reactive T-cell proliferation ex vivo, whereas leflunomide, but not JTP-74057, suppressed anti-collagen antibody production.

CONCLUSIONS

JTP-74057 exerts potent anti-arthritic effects with a different profile from leflunomide, suggesting that JTP-74057 may be useful as a new therapeutic reagent in the treatment of rheumatoid arthritis.