Immunopathogenesis Of Rheumatoid Arthritis Research Articles

B cell depletion therapy using anti-CD20 antibodies in rheumatoid arthritis

Some patients with rheumatoid arthritis (RA) suffer from disease that is refractory to both conventional therapy and newer biological agents such as tumor necrosis factor (TNF) inhibitors. In recent years, there has been growing interest in, and enhanced understanding of, the contribution of B cells to the immunopathogenesis of RA. Rituximab (RTX), a chimeric monoclonal antibody against CD20 that effectively depletes B cells in peripheral blood, has been licensed for the treatment of malignant lymphoma for almost 10 years. Efficacy of rituximab in RA has already been demonstrated in randomized control trials, and US Food and Drug Administration has approved the combination of RTX with methotrexate for use in patients with RA, who have had an inadequate response to one or more TNF antagonist therapies. The long-term efficacy, especially about joint damage, and long-term safety need to be further investigated.

Rituximab

An important role for B cells in the immunopathogenesis of rheumatoid arthritis (RA) is recognized. Rituximab is a chimeric murine/human anti-CD20 monoclonal antibody that transiently depletes CD20+ B cells. A single course of rituximab (two intravenous infusions of 1,000mg given two weeks apart) with a stable dose of methotrexate significantly improved all measures of disease activity, fatigue, and health-related quality of life relative to placebo with methotrexate. This was demonstrated in the REFLEX trial, a 24-week, randomized, double-blind, double-dummy, international, phase III study in 520 patients who had active RA despite ongoing treatment with methotrexate and had experienced an inadequate response to anti-tumor necrosis factor (TNF) therapy. Patients in REFLEX (or other studies) who responded to, and required further treatment after, an initial course of rituximab continued to respond to subsequent courses of the drug. A small subgroup of patients in REFLEX continued to respond to their first course of rituximab through 48 weeks of follow-up. Long-term treatment (up to 56 weeks) with one or more courses of rituximab in REFLEX significantly inhibited joint structural damage, the first time this effect has been reported in patients with an inadequate response to TNF inhibitors. Rituximab was generally well tolerated; the majority of adverse events were related to the first infusion of the drug, were mild to moderate in severity, and were easily managed. The adverse event profile of rituximab was unchanged after repeat courses.

Specific modification of peptide-bound citrulline residues

Immune reactions to citrulline-containing proteins appear to be central in the immunopathogenesis of rheumatoid arthritis. Citrulline residues are introduced into proteins by deimination of arginine residues, likely by an enzymatic process. There is a need to characterize which proteins in the inflamed joints of rheumatoid patients contain citrulline in situ. The characterization of deiminated proteins will be greatly facilitated by specific modification of peptide-bound citrulline residues that will enable specific enrichment and detection of citrulline-containing peptides. This study presents the details of such a modification method. The chemistry behind the reaction of the ureido group of citrulline with 2,3-butanedione in the presence of antipyrine is unraveled. Parameters for optimization of the reaction with respect to specificity and completeness, including the testing of different acids, reactant concentrations, and reaction time, are presented. This modification reaction is specific for citrulline residues. The modified product shows a characteristic mass shift of +238 Da, as demonstrated by mass spectrometry. The product absorbs UV–Vis radiation at 464 nm, and it is demonstrated that this can be used to selectively monitor citrulline-containing peptides during the separation of protein digests. Finally, the structure of the product of modified citrulline is solved by nuclear magnetic resonance spectroscopy using N-butylurea as a model substance. The results presented should facilitate the development of tags that can be used for the enrichment and subsequent detection of citrulline-containing protein fragments by mass spectrometry.

B-cell targeted therapies in rheumatoid arthritis and systemic lupus erythematosus

B cells appear to have a central role in the immunopathogenesis of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE); both autoantibody production and B-cell anomalies are characteristic of these diseases. With the recent availability of biologic agents that can deplete B cells or block their function in vivo, it has become possible to target B cells therapeutically. Evidence strongly suggests that novel B-cell targeting agents are effective. In addition, the mechanistic specificity of B-cell targeted approaches, combined with the ability to test them in large randomized controlled trials, will provide an unprecedented opportunity to study the precise roles of B cells in the immunopathogenesis of RA and SLE. The largest volume of information is available for rituximab, a chimeric monoclonal antibody that depletes B cells by binding to the CD20 cell-surface antigen. Information from multiple investigator-sponsored trials and from off-label use suggests efficacy of this antibody in RA, SLE, and other autoimmune syndromes. Randomized controlled trials have also provided solid evidence for the efficacy of rituximab in RA and are ongoing in SLE. Other therapeutic agents supported by controlled data include cytotoxic T-lymphocyte-associated protein 4 immunoglobulin and antibodies against the interleukin-6 receptor and the B-cell survival molecule BLyS. Additional agents and targets are in earlier stages of development. The concerns about infectious complications have so far not proven to be justified. We can reasonably expect important advances in the understanding and treatment of RA and SLE in the next 5-10 years, as B-cell targeting methods become more widespread and sophisticated.

Limited VH gene usage in B-cell clones established with nurse-like cells from patients with rheumatoid arthritis

Nurse-like stromal cells (NLC) in synovia and bone marrow of patients with rheumatoid arthritis (RA) can support pseudoemperipolesis, protect from apoptosis and enhance immunoglobulin production of peripheral blood B cells isolated from healthy individuals, suggesting the profound contribution of hyperactivation of B cells in RA. In the course of establishing RA-NLC from RA patients, we observed the growth of B cells in the presence of RA-NLC. We cloned B cells from the synovium or bone marrow of RA patients using the limiting dilution technique. For established clones, nucleotide sequences of immunoglobulin and surface antigens were investigated. To investigate the dependence of these clones on NLC, differences in the proliferation and the amount of immunoglobulin produced in the presence or absence of NLC were compared. Immunocytochemical staining of various cells was performed using the antibody these clones produced. Nine B-cell clones established from RA patients showed RA-NLC-dependent growth. These B-cell clones expressed CD19, CD20, CD38, CD39 and CD40, suggesting that the cloned cells were mature and activated. All clones secreted immunoglobulins in culture media, which were specific for intracellular components of various cell lines, including RA-NLC. Interestingly, we found limited usage of immunoglobulin heavy-chain variable regions (VH) among B-cell clones from RA patients. These repertoires were reported to be detected preferentially in fetal livers. The present study provides a novel insight into the involvement of RA-NLC in the immunopathogenesis of RA via an autoreactive B cell development and/or activation mechanism.

Immunological therapies for rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory arthritis of the synovial joints that causes loss of function and a shortened life expectancy. In the last 10 years there have been major advances in the treatment of RA, including more aggressive use of disease-modifying anti-rheumatic drugs and the development of immune therapies targeted to molecules and cells important in the immunopathogenesis of RA. Molecular messengers that travel between cells (cytokines) have been found to be of major importance. Blocking the cytokine tumour necrosis factor alpha (TNF-alpha) produces significant improvement in RA, ankylosing spondylitis, psoriatic arthritis, psoriasis and Crohn's disease. The use of cytokine blockers has shown the extent to which immune and inflammatory pathways are shared in a number of inflammatory diseases. There has also been an important proof of principle that blocking single cytokines can produce profound effects in inflammatory diseases.

Discordant expression of HLA class II-associated co-chaperones and HLA-DRB alleles in cultured fibroblast-like synoviocytes

Human leukocyte antigen (HLA)-DR-positive synovial fibroblasts are frequently observed in rheumatoid arthritis (RA) and may be implicated in the autoimmune reaction because RA is associated with certain HLA-DRB1* alleles. The question of whether components of the class II antigen presentation pathway and specific DRB alleles are efficiently expressed by synovial fibroblasts is germane to this hypothesis. To address this, cultured fibroblast-like synoviocytes (cFLS) were analyzed for constitutive and interferon (IFN)-γ-induced expression of specific DRB alleles and class II-associated cochaperones. IFN-γ induction of invariant chain, DM, and DR molecules was observed in all cFLS, but expression of specific DR allotypes was variable. Interestingly, DM-modulated epitopes on RA-associated DR molecules were either absent or delayed, despite strong DM expression and a paucity of major histocompatibility complex/class II-associated invariant chain peptide complexes. Altered expression of specific peptide-dependent epitopes on RA-associated HLA-DR molecules suggests differences in antigen presentation by cFLS, which may have implications for the immunopathogenesis of RA.

Immunopathologie de la polyarthrite rhumatoïde

Rheumatoid arthritis (RA) is one of the most studied auto-immune disease. In fifty years, considerable progress in the comprehension of the immunopathogenesis of this disease has been achieved. The antigen responsible for RA is still unknown, however, the high specificity of auto-antibodies directed against citrullinated peptides provides some information on the structure of this antigen probably rich in citrullines residues. RA is a polyfactorial disease that involves hormones, genetic and environmental factors, but also immunological disorders which contribute to chronic synovitis. The mechanisms involved in the pathogenesis of the disease are complex and implicate innate immunity (toll like receptors, cytokines, complement) and adaptative immune response characterised by a T cell-mediated antigen specific response implicating antigen presenting cells, B and T lymphocytes. Immunopathogenesis of RA can be subdivided in three different phases: an early phase involving innate immunity, an established phase characterised by chronic synovitis depending essentially on adaptative immune response, and a destructive phase related to cytokines effect (TNFα, IL-1β, metalloproteinases, RANKL) but also a tumour-like proliferation of fibroblast such as synoviocytes related to apoptosis defect. The better understanding of RA immunopathogenesis has led to the development of specific therapeutic interventions such as biologic agents. Based on the pathogenic mechanisms, novel treatment targeting cytokines, intracellular signalling pathways or lymphocyte co-stimulation proteins.

B cell therapy for rheumatoid arthritis: the rituximab (anti-CD20) experience

Rheumatoid arthritis (RA) is a complex condition that is well characterised by chronic inflammation in the synovial membrane of affected joints, often with systemic manifestations. Yet the aetiology and precise...

The Pathogenesis of Rheumatoid Arthritis: A Guide to Therapy

The cause of rheumatoid arthritis (RA) is unknown; however, extensive research has yielded great insight into its pathogenesis. Lymphocytes play a significant role, but a lesser role in the perpetuation of late disease. The rheumatoid synovium is composed primarily of fibroblasts and monocytes that produce inflammatory cytokines, of which interleukin-1 and tumor necrosis factor are of key importance. Potential regulatory mechanisms balancing the effects of these cytokines are inadequate to prevent joint damage and subsequent disability. These cytokines seem responsible for stimulating destructive processes in the joint via induction of prostaglandins, angiogenesis, chemokines, adhesion molecules, osteoclastogenesis, and matrix metalloproteinases. This review discusses recent research findings in the immunopathogenesis of RA with respect to potential targets for therapy.

Involvement of CD4+,CD57+ T cells in the disease activity of rheumatoid arthritis.

To evaluate the relationship between the frequency of peripheral CD57+ T cells and the physical status of rheumatoid arthritis (RA) patients, and to perform cytokine analysis of these CD57+ T cells. Four-color fluorescence-activated cell sorter analysis was performed to detect both cell surface antigens and intracellular cytokines in peripheral blood leukocytes, using monoclonal antibodies against CD3, CD4, CD8, CD57, interferon-gamma (IFNgamma), and interleukin-4 (IL-4). RA patients were clinically evaluated with a modified Health Assessment Questionnaire (M-HAQ), joint score, face scale, and visual analog scale (VAS) assessing pain and disease activity. There was a significant correlation between the frequency of CD4+,CD57+ T cells and erythrocyte sedimentation rate (ESR), whereas a correlation was not found between the frequency of CD8+,CD57+ T cells and ESR. The frequency of CD4+,CD57+ T cells also showed a significant correlation with the mHAQ score, VAS, and face scale. Again, there was no significant correlation between the above-mentioned clinical scores and the frequency of CD8+,CD57+ T cells. Flow cytometric analysis of intracellular cytokines revealed that 14.5% of the CD57+ T cells produced IFNgamma, whereas only 2.8% of the CD57+ T cells produced IL-4 in RA patients. Evidence showing that the frequency of CD4+,CD57+ T cells among CD3+ cells of RA patients had a significant correlation not only with ESR but also with the physical status of the patients, and that a large proportion of the CD4+,CD57+ T cells had the capacity to produce IFNgamma, strongly suggests that these CD4+,CD57+ T cells are involved in the immunopathogenesis of RA.

Preliminary results of early clinical trials with the fully human anti-TNFα monoclonal antibody D2E7

Current pharmacological treatments for rheumatoid arthritis (RA), including non-steroidal anti-inflammatory drugs (NSAIDs), disease modifying anti-rheumatic drugs (DMARDs), and corticosteroids, have been moderately successful in alleviating the discomforts associated with swollen,...

An overview of immunomodulatory intervention in rheumatoid arthritis.

In recent years there has been exceptional progress in the development of immunomodulatory interventions for the treatment of rheumatoid arthritis (RA). Part of the impetus for the creation of novel therapies for RA has come from a growing appreciation of the substantial morbidity and mortality that this chronic, progressive disease causes for affected patients. In addition, there has been the realization that currently available therapeutics are suboptimal as regards both their efficacy and tolerability. The development of newer therapies has been facilitated by two factors; a greater understanding of the immunopathogenesis of RA and progress in biotechnology that has allowed the creation of specific inhibitors and other agents. Myriad studies performed by investigators throughout the world have helped delineate the immunologic basis of RA. It appears that various components of the immune system are involved in the initiation and propagation of this systemic inflammatory disease. T-cells, and in particular activated CD4(+) 'memory' T-cells, serve a central role in orchestrating the immune response that underlies rheumatoid inflammation. Other cells, including monocytes, fibroblasts, B-cells, dendritic cells, mast cells and neutrophils also contribute significantly to various aspects of disease. Adhesion molecules mediate many intercellular interactions, thus contributing to activities such as the accrual of cells within the synovium and the activation of cells. Cytokines, small peptides that exert numerous inflammatory activities and cause many of the signs and symptoms of RA, play a crucial role. Indeed, RA may be considered a disorder of 'cytokine dysregulation' in that the activity of proinflammatory cytokines such as TNF-alpha and IL-1 is enhanced, and overwhelms the effects of antiinflammatory factors. Finally, a host of other inflammatory mediators are involved in the disease process. Thus, many components of the immune response may be attractive therapeutic targets for immunomodulatory intervention in RA. Advances in biotechnology have permitted the creation of specific inhibitors of distinct components of the immune system. Monoclonal antibodies (MAbs) have been created to target various cell surface molecules and cytokines. At first, most MAbs were murine in origin, which can present problems as regards immunogenicity. More recently, progress in molecular biologic techniques has allowed the synthesis of hybrid antibodies that are partly human. Such techniques have also allowed the creation of cytokine receptors coupled to immunoglobulin molecules, and other constructs. These agents can be modified to provide optimal characteristics in terms of half-life, immunogenicity and specificity, and this is an exciting area of new development. Progress has also been made in molecular-based agents that directly modify the genes or gene products for specific targets. To date, a number of trials assessing novel immunomodulatory therapies have been undertaken. In some cases, such as with inhibitors of TNF-alpha, the results have been dramatic and exciting. Further development and refinement may allow the introduction of these agents into the clinic in the foreseeable future, and will provide an important area for further research. In other cases, for example with therapies targeting CD4(+) molecules, the results have not been as promising as was hoped. Nevertheless, critical analysis of the results of these studies has provided insights into the pathogenesis of RA which may prove quite valuable for future trials. A number of agents are being studied actively at the present time, and it is hoped that they too may generate novel therapies for, and a greater understanding of, this difficult disease. The future for immunomodulatory intervention in RA looks very promising. Greater understanding of the intricacies of the immune response that underlie this disease should continue to yield viable, specific targets for novel therapies. Advances in biopharmaceuticals should generate treatments that maximize efficacy while minimizing toxicity. This should allow the clinician truly to modify the disease and achieve tangible improvements in the lives of RA patients.

Rationale and risks of novel immunomodulatory therapies in rheumatoid arthritis.

The need for new therapies for the treatment of rheumatoid arthritis (RA) has arisen during an era where clinicians have realized that RA is a far more ominous condition than was thought previously. The last decade has revealed numerous studies depicting the limited long-term efficacy and tolerability of conventional disease-modifying antirheumatic drug (DMARD) therapies. Moreover, DMARDs have not been shown to be truly capable of modifying articular, functional and radiographic outcomes in patients with RA. These issues have been raised amidst significant advances in our understanding of the immunopathogenesis of RA and advances in biotechnology. Such advances have led to a revised approach to using conventional DMARDs, while new pharmacologic and biospecific interventions are being developed. This chapter will discuss the clinical and biologic rationale for novel therapies for patients with RA and the hazards imposed by the therapeutic manipulation of various immune effector mechanisms in patients with RA.

ANTI-TUMOR NECROSIS FACTOR-α MONOCLONAL ANTIBODY THERAPY FOR RHEUMATOID ARTHRITIS

Because it plays a central role in the immunopathogenesis of rheumatoid arthritis (RA), TNF-alpha is an attractive target for immunomodulatory therapy. In a number of rigorous studies, monoclonal antibodies (mAb) specific for TNF-alpha have proved efficacious in patients with active RA. Data from these studies and issues related to mechanisms of action, potential toxicity, and future directions for this novel therapeutic approach are considered in this review.

The role of T cells in the immunopathogenesis of rheumatoid arthritis: new perspectives.

The role of T cells in the immunopathogenesis of rheumatoid arthritis: new perspectives.

Antibody-dependent enhancement and persistence in macrophages of an arbovirus associated with arthritis.

Ross River virus (RRV) is the aetiological agent of epidemic polyarthritis (EPA) a predominantly rheumatic disease afflicting up to 5000 Australians annually. We show here for the first time that macrophages can be productively infected by RRV. Subneutralizing titres of anti-RRV IgG (but not IgM) also showed classical antibody-dependent enhancement (ADE) of RRV infection in macrophage and monocyte cell lines. No correlation between development of EPA and the pre-existence of ADE titres was apparent, nor could sera raised against a related arbovirus, Barmah Forest, enhance RRV infection. Tumour necrosis factor-alpha, implicated in the immunopathogenesis of rheumatoid arthritis, was not secreted by RRV-infected monocytes or macrophages. Macrophage cell lines infected with RRV were, however, capable of producing virus for over 50 days. RRV-induced arthritis may therefore be due to the persistent productive infection of macrophages, perhaps established by a brief period of ADE early in infection.

BIOLOGIC AGENTS FOR THE TREATMENT OF RHEUMATOID ARTHRITIS

Substantial progress has been made in our understanding of the immune system and immunopathogenesis of rheumatoid arthritis. This knowledge, combined with advances in biotechnology, has resulted in the development of biologic agents to selectively target elements of the immune system participating in the inflammatory response. This article reviews the available data from clinical trials of biologic agents for the treatment of rheumatoid arthritis. Randomized controlled trials comparing administration of a biologic agent to placebo are emphasized. Despite concerns raised by initial trials with these agents, they still offer the most promise as treatments for autoimmune diseases ++such as rheumatoid arthritis.

Mechanism of action of cyclosporin in rheumatoid arthritis.

Heterogenous population of cells, including macrophages, synoviocytes and lymphocytes play important roles in the immunopathogenesis of rheumatoid arthritis (RA). T cells, however, seem to be a common thread throughout the disease process. In inhibiting T lymphocytes, cyclosporin A presents a more selective form of therapy in RA. The immunosuppressive action of cyclosporin is primarily due to the inhibition of antigen/mitogen-induced secretion of lymphokines at the transcriptional level from T cell. The inhibition of Ca2(+)-dependent signaling pathways by cyclophilin-cyclosporin complexes in T cell appears to shut down lymphokine-gene transcription.

Possible Mechanisms of Action of Methotrexate in Patients with Rheumatoid Arthritis

Methotrexate has been reported to be effective in various animal models of arthritis as well as a variety of human disorders without a shared pathogenesis. Reports have emerged of the effect of the drug on lymphocytes, cytokines, leukotrienes, neutrophils, as well as a large variety of intracellular biochemical pathways. At present, it is not possible to identify which of the many possible mechanisms of action are relevant to its action when used in patients with rheumatoid arthritis (RA). More definitive insights may have to await a better understanding of the immunopathogenesis of RA.