Treatment of rheumatoid arthritis with chimeric monoclonal antibodies to tumor necrosis factor alpha

Rheumatoid arthritis

Rheumatoid arthritis is a systemic, inflammatory, autoimmune disorder. Enhanced understanding of molecular pathogenesis has enabled development of innovative biological agents that target specific parts of the immune system. These treatments have changed the course and face of rheumatoid arthritis and outcomes for patients and society. New knowledge has emerged of how environmental factors interact with susceptibility genes and the immune system in the pathogenesis of a major subset of rheumatoid arthritis. Research undertaken on the longitudinal disease process and molecular pathology of joint inflammation has led to new therapeutic strategies that promote early use of disease-modifying drugs with tight disease control and distinct and quantifiable treatment goals. Today, such approaches can halt most cases of joint destruction but not all instances of joint inflammation and comorbidity. Understanding the cause and pathogenesis of different rheumatoid arthritis subsets will lead not only to individualised treatments during early phases of the illness but also, possibly, to disease prevention.

Many cytokines are very useful therapeutic targets in disease

Cytokines are a large family of more than 100 small proteins that function as short-range mediators involved in essentially all biological processes. They have been found to be important rate-limiting signals, and it is now known that blocking some cytokines, e.g., TNF-alpha, and cytokine receptors, such as human EGFR 1 (HER1) or HER2, yields effective therapeutics that address unmet needs. This Review Series surveys three chronic inflammatory disease areas and two forms of cancer and discusses the important role of cytokines and their receptors in these disease processes. Their role as potential therapeutic targets is also highlighted.

Evidence that cytokines play a role in rheumatoid arthritis

A large number of cytokines are active in the joints of patients with rheumatoid arthritis (RA). It is now clear that these cytokines play a fundamental role in the processes that cause inflammation, articular destruction, and the comorbidities associated with RA. Following the success of TNF-alpha blockade as a treatment for RA, other cytokines now offer alternative targets for therapeutic intervention or might be useful as predictive biomarkers of disease. In this Review, we discuss the biologic contribution and therapeutic potential of the major cytokine families to RA pathology, focusing on molecules contained within the TNF-alpha, IL-1, IL-6, IL-23, and IL-2 families.

Quantitative measurement of cytokine expression in synoviocytes derived from rheumatoid arthritis patients

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterised by pain, swelling and progressive destruction of synovial joints. The synovial membranes of the affected joints markedly increase in size due to infiltration of several cell types, of which macrophages, lymphocytes and fibroblasts are most abundant. These cell types are activated and release a plethora of inflammatory mediators, such as cytokines, chem-okines and matrix metalloproteinases (MMPs). Synovial membranes can be removed from the joints of RA patients (most commonly when the respective joint is undergoing replacement therapy) and enzymati-cally digested, analyzed or cultured ex vivo. Analysing the cytokine profile of distinct populations of ex vivo RA-patients derived synoviocytes can provide an insight into the pathogenic mechanisms underlying RA. Additionally, since ex vivo cultures of synoviocytes spontaneously produce cytokines they serve as an excellent model for investigating the efficacy of novel anti-inflammatory drugs.

Systemic administration of tolerogenic dendritic cells ameliorates murine inflammatory arthritis

The expression of various cell surface molecules and the production of certain cytokines are important mechanisms by which dendritic cells (DC) are able to bias immune responses. This paper describes the effects of the inflammatory cytokine tumor necrosis factor (TNF)-α on DC phenotype and function. TNF-α treatment resulted in upregulation of MHC class II and CD86 in the absence of increased cell surface CD40 and CD80 or the production of IL-12. Additionally TNF-α treated cells were able to bias T cell responses towards an anti-inflammatory profile. On a note of caution this tolerogenic phenotype of the DC was not stable upon subsequent TLR-4 ligation as a 4 hour pulse of the TNF-α treated DC with lipopolysaccharide (LPS) resulted in the restoration of IL-12 production and an enhancement of their T cell stimulatory capacity which resulted in an increased IFN-γ production. However, TNF-α treated DC, when administered in vivo, were shown to ameliorate disease in collagen induced arthritis, an experimental model of inflammatory joint disease. Mice receiving TNF-α treated DC but not LPS matured DC had a delayed onset, and significantly reduced severity, of arthritis. Disease suppression was associated with reduced levels of collagen specific IgG2a and decreased inflammatory cell infiltration into affected joints. In summary the treatment of DC with TNF-α generates an antigen presenting cell with a phenotype that can reduce the pro-inflammatory response and direct the immune system towards a disease modifying, anti-inflammatory state.

Therapeutic efficacy of intra-articular adrenomedullin injection in antigen-induced arthritis in rabbits

Introduction

Adrenomedullin is a potent vasodilatory and hypotensive peptide as well as an endogenous immunomodulatory factor with predominantly anti-inflammatory effects. The purpose of the present study was to evaluate the therapeutic effects of adrenomedullin in rabbits with antigen-induced arthritis, an experimental model of rheumatoid arthritis.

Methods

Following the induction of arthritis in both knee joints by ovalbumin injection into the joint spaces of pre-immunized rabbits, increasing daily doses of adrenomedullin were injected into the knee joint spaces or saline was injected into the contralateral knee joint spaces as the control. For time-course experiments, adrenomedullin and saline were injected into the knee joint spaces daily for 7 days and 20 days. The degree of joint swelling and the histological change in the knee joints injected with adrenomedullin were compared with the control knee joints. Histological evaluation of the infrapatellar fat pads and synovial tissue was performed. TNFα, IL-6, vascular endothelial growth factor and transforming growth factor-beta mRNA levels in the synovial tissue were measured using real-time quantitative PCR.

Results

Daily injections of adrenomedullin into the knee joint spaces of rabbits with antigen-induced arthritis decreased joint swelling. Histological examination revealed that adrenomedullin reduced edematous changes and the infiltration of inflammatory cells in the synovial tissues. Analysis of mRNA levels showed that adrenomedullin significantly reduced TNFα mRNA expression by 21% to 49% in a dose-dependent manner, and dose-dependently increased IL-6 mRNA expression by 45% to 121%.

Conclusions

These results suggest that daily injections of adrenomedullin into the knee joint spaces of rabbits with antigen-induced arthritis ameliorated the inflammatory response in arthritic joints. Adrenomedullin may thus be useful as a treatment for rheumatoid arthritis; however, the effect of adrenomedullin on IL-6 production in the synovial tissue may be an undesirable adverse effect in rheumatoid arthritis therapy.

Sinomenine ameliorates arthritis via MMPs, TIMPs, and cytokines in rats

Rheumatoid arthritis (RA) is a chronic, inflammatory autoimmune disease that results in progressive joint destruction and substantial morbidity. The stem of the Chinese medicinal plant, Sinomenium acutum Rehder & Wilson (Family Menispermaceae), has been used to treat various rheumatic and arthritic diseases, of which the major bioactive component is sinomenine. We investigated the nature and molecular mechanisms of the anti-arthritic effect of sinomenine on collagen-induced arthritis in female Wistar rats. The results showed that sinomenine markedly suppressed the incidence and disease progression of established CIA, showing as dramatic reduction of paw swelling, ESR, and arthritic scores. Sinomenine suppressed the production of proinflammatory cytokines IL-1beta and IL-6 in serum, inhibited the protein expressions and activities of MMP-2 and MMP-9, and elevated the protein expressions and activities of TIMP-1 and TIMP-3 in rat paw tissues.

The development of targeted therapies in rheumatoid arthritis

The therapy of rheumatoid arthritis has been revolutionised by advances in the understanding of disease at a cellular and molecular level accompanied by the technology to target specific mediators of disease. Proposed therapeutic targets from in vitro and animal models however have frequently resulted in unexpected outcomes in clinical trials. These have included have included cytokines, chemokines, the T cell receptor trimolecular complex, T cells and B cells. The most successful strategies have resulted from a close dialogue between clinical and laboratory work. The key stages in the development of these agents and remaining unanswered questions are reviewed.

Neutralizing IL-21 and IL-15 inhibits pro-inflammatory cytokine production in rheumatoid arthritis

Interleukin IL-21 and IL-15 belong to the common gamma-chain receptor family. IL-15 represents a novel therapeutic target in rheumatoid arthritis (RA), whereas less is known about the role of IL-21 in human inflammatory diseases. We have analysed the effects of blocking IL-21 and IL-15 on spontaneous production of pro-inflammatory cytokines in RA synovial cell cultures. RA synovial membrane cells were cultured in the presence of an IL-21R-Fc chimera or a neutralizing IL-15 antibody and production of tumour necrosis factor (TNF)alpha, IL-6 and IL-1beta was measured by enzyme-linked immunosorbent assay (ELISA). Expression of IL-21 and IL-15 in RA synovium was measured by RT-PCR and ELISA. mRNA for IL-21 and IL-21R was detected in the culture cell lysates. Protein for IL-15 was found at detectable levels in the cell lysates. Both the IL-21R-Fc chimera and anti-IL-15 antibody inhibited cytokine release, although substantially more IL-21R-Fc was needed. IL-21R-Fc at the highest dose (100 microg/ml) significantly reduced TNFalpha production by 50%, IL-6 by 57% and IL-1beta by 81%. Anti-IL-15 antibody (5 microg/ml) significantly inhibited TNFalpha release by 51%, IL-6 by 37% and IL-1beta by 82% in line with previous published observations. The data confirm that IL-15 plays a role in RA and suggests that IL-21 is also involved in driving the pro-inflammatory cytokine response in RA.

Tumor necrosis factor alpha drugs in rheumatoid arthritis: systematic review and metaanalysis of efficacy and safety

BACKGROUND

To analyse available evidence on the efficacy and safety of anti-TNFalpha drugs (infliximab, etanercept and adalimumab) for treating rheumatoid arthritis (RA).

METHODS

We searched systematically for randomised controlled clinical trials on treatment of RA with anti-TNFalpha drugs, followed by a systematic review with metaanalysis. Trials were searched from MEDLINE, EMBASE and Cochrane Library databases. The American College of Rheumatology (ACR) efficacy response criteria were used. Safety parameters provided by the trials were also assessed. Positive and undesired effects were estimated using combined relative risks (RR), number needed to treat (NNT) and number needed to harm (NNH). Heterogeneity was evaluated by Cochrane's Q and I2 statistics.

RESULTS

Thirteen trials (7087 patients) met the inclusion criteria. The combined RR to achieve a therapeutic response to treatment with recommended doses of any anti-TNFalpha drug was 1.81 (95% CI 1.43-2.29) with a NNT of 5 (5-6) for ACR20. NNT for ACR50 [5 (5-6)] and ACR70 [7 (7-9)] were similar. Overall therapeutic effects were also similar regardless of the specific anti-TNFalpha drug used and when higher than recommended doses were administered. However, lower than recommended doses elicited low ACR70 responses (NNT 15). Comparison of anti-TNFalpha drugs plus methotrexate (MTX) with MTX alone in patients with insufficient prior responses to MTX showed NNT values of 3 for ACR20, 4 for ACR50 and 8 for ACR70. Comparison of anti-TNFalpha drugs with placebo showed a similar pattern. Comparisons of anti-TNFalpha drugs plus MTX with MTX alone in patients with no previous resistance to MTX showed somewhat lower effects. Etanercept and adalimumab administered as monotherapy showed effects similar to those of MTX. Side effects were more common among patients receiving anti-TNFalpha drugs than controls (overall combined NNH 27). Patients receiving infliximab were more likely to drop out because of side effects (NNH 24) and to suffer severe side effects (NNH 31), infections (NNH 10) and infusion reactions (NNH 9). Patients receiving adalimumab were also more likely to drop out because of side effects (NNH 47) and to suffer injection site reactions (NNH 22). Patients receiving etanercept were less likely to drop out because of side effects (NNH for control versus etanercept 26) but more likely to experience injection site reactions (NNH 5).

CONCLUSION

Anti-TNFalpha drugs are effective in RA patients, with apparently similar results irrespective of the drug administered. Doses other than those recommended are also beneficial. The main factor influencing therapeutic efficacy is the prior response to DMARD treatment. The effect of treatment with etanercept or adalimumab does not differ from that obtained with MTX. The published safety profile for etanercept is superior but the fact that no patients are treated with higher than recommended doses requires explanation.

Evaluation of the anti-inflammatory effect of infliximab in a mouse model of acute asthma

BACKGROUND AND OBJECTIVE

To evaluate the potential role of anti-tumour necrosis factor (TNF)-alpha mAb (infliximab) on the inflammatory response in a mouse model of acute asthma.

METHODS

BALB/c mice received intraperitoneal (i.p.) ovalbumin (OVA) on days 0 and 14, 100 microg of OVA intranasally on day 14 and 50 microg of OVA intranasally on days 25, 26 and 27. The low-dose (2.5 mg/kg) and high-dose (6.25 mg/kg) infliximab groups received i.p. infliximab before each i.p. sensitization and on challenge days 1, 6, 13, 20 and 27. The control group received i.p. injections of normal saline with alum on days 0 and 14 and normal saline without alum on days 14, 25, 26 and 27.

RESULTS

There were statistically significant decreases in the numbers of BAL fluid (BALF) neutrophils, eosinophils, as well as lung eosinophils in both the low- and high-dose infliximab groups when compared with the control OVA sensitized/challenged group. The lower dose of infliximab did not alter lung neutrophil counts, but a marked decrease was seen with the high dose of infliximab. After treatment with low and high doses of infliximab, BALF levels of regulated on activation normal T cell expressed and secreted (RANTES), granulocyte macrophage-colony stimulating factor (GM-CSF), TNF-alpha, IL-6, macrophage inflammatory protein (MIP)-2, and levels of RANTES, IL-4, GM-CSF, TNF-alpha, IL-6 and MIP-2 in lung tissue were significantly decreased when compared with the control OVA sensitized/challenged group. There was a significant decrease in BALF IL-4 only in the high-dose infliximab group.

CONCLUSIONS

These results show that an anti-TNF-alpha mAb has a considerable anti-inflammatory effect on allergen-induced lung inflammation in an animal model of acute asthma.

TNF-mediated inflammatory disease

TNF was originally described as a circulating factor that can cause necrosis of tumours, but has since been identified as a key regulator of the inflammatory response. This review describes the known signalling pathways and cell biological effects of TNF, and our understanding of the role of TNF in human disease. TNF interacts with two different receptors, designated TNFR1 and TNFR2, which are differentially expressed on cells and tissues and initiate both distinct and overlapping signal transduction pathways. These diverse signalling cascades lead to a range of cellular responses, which include cell death, survival, differentiation, proliferation and migration. Vascular endothelial cells respond to TNF by undergoing a number of pro-inflammatory changes, which increase leukocyte adhesion, transendothelial migration and vascular leak and promote thrombosis. The central role of TNF in inflammation has been demonstrated by the ability of agents that block the action of TNF to treat a range of inflammatory conditions, including rheumatoid arthritis, ankylosing spondylitis, inflammatory bowel disease and psoriasis. The increased incidence of infection in patients receiving anti-TNF treatment has highlighted the physiological role of TNF in infectious diseases.

Resting CD4+ effector memory T cells are precursors of bystander-activated effectors: a surrogate model of rheumatoid arthritis synovial T-cell function

Background

Previously we described a system whereby human peripheral blood T cells stimulated for 8 days in a cytokine cocktail acquired effector function for contact-dependent induction of proinflammatory cytokines from monocytes. We termed these cells cytokine-activated (Tck) cells and found that the signalling pathways elicited in the responding monocytes were identical whether they were placed in contact with Tck cells or with T cells isolated from rheumatoid arthritis (RA) synovial tissue.

Methods

Here, using magnetic beads and fluorescence-activated cell sorting, we extensively phenotype the Tck effector cells and conclude that effector function resides within the CD4⁺CD45RO⁺, CCR7^-, CD49d^high population, and that these cells are derived from the effector memory CD4⁺ T cells in resting blood.

Results

After stimulation in culture, these cells produce a wide range of T-cell cytokines, undergo proliferation and differentiate to acquire an extensively activated phenotype resembling RA synovial T cells. Blocking antibodies against CD69, CD18, or CD49d resulted in a reduction of tumour necrosis factor-α production from monocytes stimulated with CD4⁺CD45RO⁺ Tck cells in the co-culture assay. Moreover, blockade of these ligands also resulted in inhibition of spontaneous tumour necrosis factor-α production in RA synovial mononuclear cell cultures.

Conclusion

Taken together, these data strengthen our understanding of T-cell effector function, highlight the multiple involvement of different cell surface ligands in cell-cell contact and, provide novel insights into the pathogenesis of inflammatory RA disease.

Biologic treatments for systemic rheumatic diseases

Many rheumatologic disorders, most notably Sjögren's syndrome, are associated with dental complications and in some cases oral diseases may trigger or drive connective tissue disease. During the past three decades the treatment in rheumatology was revolutionized by the introduction of disease-modifying anti-rheumatic drugs. Advances in our understanding of the pathogenesis of rheumatic diseases have led to the discovery of critical mechanisms of inflammation and autoimmunity and the invention of new target-specific biologic agents. In this review, we will summarize the current state of biologic therapies in rheumatology and discuss the implications of these on oral health and disease.

Histological analysis of synovium in cases of effect attenuation associated with infliximab therapy in rheumatoid arthritis

To investigate the histological changes of synovium in cases of effect attenuation occurring after the use of infliximab in the treatment of rheumatoid arthritis (RA), we histologically assessed synovial tissue from ten methotrexate-treated RA patients and 12 infliximab-treated RA patients after arthroscopic synovectomy. The synovium was observed using hematoxylin and eosin (H&E) stain and analyzed immunohistochemically for expression of tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), matrix metalloproteinase-3 (MMP-3), B-cell transmembrane protein, cluster of differentiation 20 (CD20), nuclear factor kappa B (NFkB), bromodeoxyuridine (BrdU), and vascular endothelial growth factor (VEGF). H&E staining showed significant vascular proliferation in the synovium of the RA patients in the infliximab group (p < 0.05). Immunohistochemical examinations showed that TNF-alpha was completely blocked in patients with effect attenuation who received infliximab (p < 0.05). IL-6 was more strongly expressed in the interstitial cells of synovium of patients who received infliximab than in the cells of patients in the control group (p < 0.05). MMP-3 was expressed on the surface of synovium, and CD20 and BrdU were strongly expressed in the infliximab group compared with the control group (p < 0.05). NFkB was expressed in both groups. VEGF was decreased in the infliximab group compared with control. These findings indicate that the expression pattern of immunohistochemical findings in synovium was changed in effect attenuation cases among RA patients treated with infliximab.

Historical development of monoclonal antibody therapeutics

Since the first publication by Kohler and Milstein on the production of mouse monoclonal antibodies (mAbs) by hybridoma technology, mAbs have had a profound impact on medicine by providing an almost limitless source of therapeutic and diagnostic reagents. Therapeutic use of mAbs has become a major part of treatments in various diseases including transplantation, oncology, autoimmune, cardiovascular, and infectious diseases. The limitation of murine mAbs due to immunogenicity was overcome by replacement of the murine sequences with their human counterpart leading to the development of chimeric, humanized, and human therapeutic antibodies. Remarkable progress has also been made following the development of the display technologies, enabling of engineering antibodies with modified properties such as molecular size, affinity, specificity, and valency. Moreover, antibody engineering technologies are constantly advancing to enable further tuning of the effector function and serum half life. Optimal delivery to the target tissue still remains to be addressed to avoid unwanted side effects as a result of systemic treatment while achieving meaningful therapeutic effect.

Immunomodulatory effects of etanercept in a model of brain injury act through attenuation of the acute-phase response

TNF-alpha has proved to be a successful target in the treatment of many peripheral inflammatory diseases, but the same interventions worsen immune-mediated CNS disease. However, anti-TNF-alpha strategies may offer promise as therapy for non-immune CNS injury. In this study, we have microinjected IL-1beta or lipopolysaccharide (LPS) into the rat brain as a simple model of brain injury and have systemically administered the TNF-alpha antagonist etanercept to discover whether hepatic TNF-alpha, produced as part of the acute-phase response to CNS injury, modulates the inflammatory response in the brain. We report a significant reduction in neutrophil numbers recruited to the IL-1beta- or LPS-challenged brain as a result of TNF-alpha inhibition. We also show an attenuation in the levels of hepatic mRNA including TNF-alpha mRNA and of TNF-alpha-induced genes, such as the chemokines CCL-2, CXCL-5, and CXCL-10, although other chemokines elevated by the injury were not significantly changed. The reduction in hepatic chemokine synthesis results in reduced numbers of circulating neutrophils, and also a reduction in the numbers recruited to the liver as a consequence of brain injury. These findings suggest that TNF-alpha inhibitors may reduce CNS inflammatory responses by targeting the hepatic acute-phase response, and thus therapies for brain injury need not cross the blood-brain barrier to be effective.

Actin cytoskeleton dynamics linked to synovial fibroblast activation as a novel pathogenic principle in TNF-driven arthritis

Rheumatoid arthritis is a chronic inflammatory disorder whose origin of defect has been the subject of extensive research during the past few decades. While a number of immune and non-immune cell types participate in the development of chronic destructive inflammation in the arthritic joint, synovial fibroblasts have emerged as key effector cells capable of modulating both joint destruction and propagation of inflammation. Ample evidence of aberrant changes in the morphology and biochemical behaviour of rheumatoid arthritis synovial fibroblasts have established the tissue evading and "transformed" character of this cell type. We have recently demonstrated that actin cytoskeletal rearrangements determine the pathogenic activation of synovial fibroblasts in modelled TNF-mediated arthritis, a finding correlating with similar gene expression changes which we observed in human rheumatoid arthritis synovial fibroblasts. Here, we show that pharmacological inhibition of actin cytoskeleton dynamics alters potential pathogenic properties of the arthritogenic synovial fibroblast, such as proliferation, migration and resistance to apoptosis, indicating novel opportunities for therapeutic intervention in arthritis. Recent advances in this field of research are reviewed and discussed.

Tumor necrosis factor antagonist mechanisms of action: a comprehensive review

During the past 30 years, elucidation of the pathogenesis of rheumatoid arthritis, Crohn's disease, psoriasis, psoriatic arthritis and ankylosing spondylitis at the cellular and molecular levels has revealed that these diseases share common mechanisms and are more closely related than was previously recognized. Research on the complex biology of tumor necrosis factor (TNF) has uncovered many mechanisms and pathways by which TNF may be involved in the pathogenesis of these diseases. There are 3 TNF antagonists currently available: adalimumab, a fully human monoclonal antibody; etanercept, a soluble receptor construct; and infliximab, a chimeric monoclonal antibody. Two other TNF antagonists, certolizumab and golimumab, are in clinical development. The remarkable efficacy of TNF antagonists in these diseases places TNF in the center of our understanding of the pathogenesis of many immune-mediated inflammatory diseases. The purpose of this review is to discuss the biology of TNF and related family members in the context of the potential mechanisms of action of TNF antagonists in a variety of immune-mediated inflammatory diseases. Possible mechanistic differences between TNF antagonists are addressed with regard to their efficacy and safety profiles.

Sulfasalazine-induced immune thrombocytopenia

Sulfasalazine is a well established disease-modifying anti-rheumatic drug commonly used in the treatment of rheumatic disorders and inflammatory bowel disease. Sulfasalazine was generally well tolerated in clinical trials, the most frequently reported adverse effects being adverse gastrointestinal effects, headache, dizziness and rash; myelosuppression can also occur. We are now reporting the first case of autoimmune thrombocytosis following sulfasalazine treatment.

Pathogenesis and therapy of rheumatoid arthritis

Rheumatoid arthritis is a chronic disabling disease affecting at least 1% of the population on a worldwide basis. Research aimed at understanding the pathogenesis of this disease led to the identification of TNFalpha as a major pro-inflammatory cytokine expressed in the inflamed joints of patients with rheumatoid arthritis. Subsequently, in vitro studies provided evidence to suggest that TNFalpha played an important role in driving the expression of additional pro-inflammatory cytokines, such as IL-1, GM-CSF, IL-6, and IL-8, in synovial cell cultures. Another important finding that confirmed the pathological significance of TNFalpha was that mice genetically engineered to overexpress TNFalpha spontaneously developed arthritis. Subsequently, the therapeutic effect TNFalpha blockade was tested in animal models prior to clinical trials in human patients, which provided unequivocal verification of the validity of TNFalpha as a therapeutic target. Anti-TNFalpha therapy is now accepted as a fully-validated treatment modality for rheumatoid arthritis.

The use of TNF-alpha blocking agents in rheumatoid arthritis: an update

TNF-alpha has been found to play a pivotal role in the pathogenic mechanisms of rheumatoid arthritis (RA). Drugs targeting TNF-alpha have been developed to neutralise the deleterious effects of this inflammatory cytokine. There are, at present, three drugs available for the treatment of RA patients with active disease who are refractory to conventional treatments including methotrexate: 2 monoclonal antibodies, infliximab and adalimumab, and a fusion protein with p75 receptors, etanercept. These three agents have proved to be effective and safe in large placebo-controlled trials enrolling patients with established or early disease and showed effectiveness in controlling signs and symptoms of the disease, improving quality of life and in slowing and even arresting the progression of radiographic damage. With the long-term surveillance of these drugs were described serious adverse events, particularly infections such as tuberculosis, especially with infliximab. The risk for malignancies under TNF-alpha antagonists, especially lymphoma, remains controversial. Specific recommendations are given by international experts for selecting and monitoring RA patients with TNF-alpha antagonists. Other drugs targeting TNF-alpha such as PEGylated molecules (CDP870 or certolizumab) are in development. These new biological therapies blocking TNF-alpha undoubtedly constitute a considerable advancement in the management of RA, but careful evaluation at the initiation of the treatment and long-term surveillance of the patients receiving such drugs remains necessary.

Molecular interactions between T cells and fibroblast-like synoviocytes: role of membrane tumor necrosis factor-alpha on cytokine-activated T cells

The mechanism of fibroblast-like synoviocyte (FLS) transformation into an inflammatory phenotype in rheumatoid arthritis (RA) is not fully understood. FLS interactions with invading leukocytes, particularly T cells, are thought to be a critical component of this pathological process. Resting T cells and T cells activated through the T-cell receptor have previously been shown to induce inflammatory cytokine production by FLS. More recently, a distinct population of T cells has been identified in RA synovium that phenotypically resembles cytokine-activated T (Tck) cells. Using time lapse microscopy, the interactions of resting, superantigen-activated, and cytokine-activated T cells with FLS were visualized. Rapid and robust adhesion of Tck and superantigen-activated T cells to FLS was observed that resulted in flattening of the T cells and a crawling movement on the FLS surface. Tck also readily activated FLS to produce interleukin IL-6 and IL-8 in a cell contact-dependent manner that was enhanced by exogenous IL-17. Although LFA-1 and ICAM-1 co-localized at the Tck-FLS synapse, blocking the LFA-1/ICAM-1 interaction did not substantially inhibit Tck effector function. However, antibody blocking of membrane tumor necrosis factor (TNF)-alpha on the Tck surface did inhibit FLS cytokine production, thus illustrating a novel mechanism for involvement of TNF-alpha in cell-cell interactions in RA synovium and for the effectiveness of TNF-alpha blockade in the treatment of RA.

Interleukin-15 selectively expands CD57+CD28−CD4+ T cells, which are increased in active rheumatoid arthritis

Proinflammatory cytokines as well as CD4(+) T cells play critical roles in the pathogenesis of rheumatoid arthritis (RA). Recently, an increase of CD57(+) or CD28(-)CD4(+) T cells was demonstrated in RA, although the mechanism of the increase of these T cells is unclear. In this study, we first examined the relationship between CD57(+)CD4(+) T cells and CD28(-)CD4(+) T cells and found CD57(+)CD28(-)CD4(+) T cells, but neither CD57(+)CD28(+) nor CD57(-)CD28(+) cells, expanded in the peripheral blood of active RA. In vitro experiments revealed that CD57(+)CD28(-)CD4(+) T cells selectively expanded in response to IL-15. Furthermore IL-15-stimulated CD57(+)CD28(-)CD4(+) T cells induced TNF-alpha production from monocytes. These results suggest that CD57(+)CD28(-)CD4(+) T cells are involved in the pathogenesis of RA by responding to IL-15.

Human TNF-alpha gene vaccination prevents collagen-induced arthritis in mice

TNFalpha is a key factor in the pathogenesis of rheumatoid arthritis. To investigate whether heterologous TNFalpha gene vaccination could induce anti-TNFalpha antibodies via cross-reaction and prevent the inflammatory arthritis, we constructed two plasmids by inserting a full-length cDNA of human TNFalpha into a secreted vector (pSecTag-TNFalpha) and a non-secreted vector (pTARGE-TNFalpha), respectively. Administering either plasmid to collagen-induced arthritis (CIA) mice reduced paw swelling and synovium-infiltrating inflammatory cells. This reduction was accompanied by down-regulated TNFalpha in sera and joints. The spleen cells from treated CIA mice displayed decreased IFN-gamma mRNA levels and matrix metalloproteinase-9 bioactivity in comparison with those from CIA control. Furthermore, both spontaneous and collagen-specific proliferation of the lymphocytes was significantly decreased after treatment. Administration of plasmids led to an elicited production of antibodies to both human and mouse TNFalpha. These results suggest that human TNFalpha gene vaccination prevents CIA in mice likely by inducing cross-reactive antibodies against TNFalpha, and that heterologous gene vaccination might provide an effective therapeutic strategy to battle TNFalpha mediated diseases.

Tumor necrosis factor alpha −308 polymorphism is associated with rheumatoid arthritis in Han population of Eastern China

The aim of this study was to investigate the association of single nucleotide polymorphisms (SNPs) in tumor necrosis factor alpha (TNFalpha) promoter with rheumatoid arthritis (RA) in Chinese Han population. Six SNPs at positions -238, -244, -308, -376, -857, -863 within TNFalpha promoter were genotyped in 367 unrelated RA patients and 271 healthy controls, using direct DNA sequencing method. Allelic, genotypic, and haplotypic associations of these SNPs with RA were examined. The frequencies of TNFalpha -308A allele and the haplotype GACC (in order of -238, -308, -857, -863) were significantly lower in RA patients when compared with healthy controls (P = 0.0046, P = 0.0045, respectively) but TNFalpha -308 polymorphism was not related to the clinical manifestations of RA patients. These results implied that TNFalpha gene itself or a gene in linkage disequilibrium with it might be associated with RA in Han population of Eastern China.

Honokiol, a Natural Plant Product, Inhibits Inflammatory Signals and Alleviates Inflammatory Arthritis

Honokiol (HNK), a phenolic compound isolated and purified from magnolia, has been found to have a number of pharmacologic benefits, including anti-angiogenic and anti-inflammatory properties. HNK has long been used in traditional Asian medicine without toxic side effects. We and others have extensively studied signaling to B cells by CD40 and its Epstein Barr viral mimic, latent membrane protein 1 (LMP1), which has been implicated in exacerbation of chronic autoimmune disease. We asked whether HNK could inhibit CD40 and LMP1 inflammatory signaling mechanisms. In vivo, HNK stabilized the severity of symptomatic collagen-induced arthritis in both CD40-LMP1 transgenic mice and their congenic C57BL/6 counterparts. Ex vivo studies, including collagen-specific serum Ab and Ag recall responses, as well as CD40 or LMP1-mediated activation of splenic B cells, supported the anti-inflammatory effects of HNK. In mouse B cell lines expressing the human CD40-LMP1 chimeric receptor, CD40- and LMP1-mediated NF-kappaB and AP-1 activation were abrogated in a dose-dependent manner, with a concomitant decrease in TNF-alpha and IL-6. These promising findings suggest that the nontoxic anti-inflammatory properties of HNK could be valuable for blocking the autoimmune response.

B-cell depletion in patients with rheumatoid arthritis refractant to multiple TNF blockers and the interleukin 1 receptor-antagonist anakinra

To evaluate the efficacy of Rituximab in a negatively selected patient cohort, with inadequate response to different disease modifying drugs (DMARDs) and to at least two biologicals. Fifteen patients with severe rheumatoid arthritis with inefficacy of an average of 5 DMARDS and 2.5 TNF antagonists were treated with Rituximab. Eight patients were ineffectively pretreated with Anakinra as well. The disease activity score (DAS28) and the morning stiffness served for assessment of the clinical response. For maintenance treatment different conventional DMARDs were used (4xMTX, 4xLeflunomide, 1xmycophenolate, 1xsirolimus, 1xhydroxychloroquine). At baseline visit the mean DAS 28 was 5.9. The mean duration of morning stiffness was 99.6 min. At month 6 the mean DAS28 was 3.95. Forty percent (6 patients) showed a good and 33% (5 patients) a moderate response. Morning stiffness improved to 43 min. In this negatively selected group of patients Rituximab was safe and effective.

Update on cytokines in rheumatoid arthritis

PURPOSE OF REVIEW

There have recently been fewer publications describing novel cytokines in rheumatoid arthritis. In the present review we focus on cytokines not previously implicated in contributing to the pathogenesis of rheumatoid arthritis.

RECENT FINDINGS

The detection of IL-17 and factors that drive the differentiation and expansion of ThIL-17 cells, particularly in mouse models, clearly place IL-17 as a potential therapeutic target in rheumatoid arthritis. The emergence of other novel cytokines, notably IL-20 and IL-22, is of interest, not least by displaying proinflammatory effects particularly on fibroblasts - in contrast to their family member IL-10, the most potent anti-inflammatory cytokine. IL-32 is also of interest, with proinflammatory effects both on myeloid and nonmyeloid cells.

SUMMARY

It is unclear whether the novel cytokines described in the present review will influence clinical practise. The involvement of IL-17 in murine arthritis may not translate as effectively to human arthritis - the ultimate test is a clinical trial in humans. The lack of efficacy of a recent anti-MCP-1/CCL-2 trial in rheumatoid arthritis highlights this dilemma. Finally, while technological advances including microarray analysis have broadened the scope for cytokine detection in rheumatoid arthritis, these methods have yet to translate to therapy in the clinic.

S-nitrosoglutathione Prevents Interphotoreceptor Retinoid-Binding Protein (IRBP161–180)-Induced Experimental Autoimmune Uveitis

PURPOSE

Experimental autoimmune uveitis (EAU), an animal model of human uveitis, is an organ-specific autoimmune disease mediated by various inflammatory cytokines. In particular, tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta and interferon (IFN)-gamma are known to play a role in its pathogenesis. S-nitrosothiol S-nitrosoglutathione (GSNO), a slow nitric oxide (NO) donor, was reported to have beneficial effects in inflammatory disease in ischemia-reperfusion injury. The efficacy of GSNO treatment on interphotoreceptor retinoid-binding protein (IRBP)-induced EAU was investigated, using functional, histologic, and immunologic readouts.

METHODS

Mice were immunized with a single injection of IRBP(161180) peptide to induce EAU, followed by a daily treatment with GSNO (1 mg/kg). Electroretinogram (ERG) analysis, histopathology, and immunologic responses to IRBP were analyzed. The effects of GSNO treatment on the antigen-specific T-cell recall responses and their cytokine production were determined.

RESULTS

A single immunization of IRBP(161180) peptide led to significant structural damage of the retina and concomitant elimination of ERGs. Daily oral GSNO treatment from days 1-14 following immunization was found to be effective against IRBP-induced EAU. Histopathologic and ERG analysis both demonstrated significant retinal protection in GSNO-treated mice. The GSNO treatment of EAU animals significantly attenuated the levels of TNF-alpha, IL-1beta, IFN-gamma, and IL-10 in retinas, as measured by quantitative real-time polymerase chain reaction analysis. The splenocytes isolated from EAU- and GSNO-treated mice had lower antigen-specific T-cell proliferation in response to IRBP protein, and their cytokine production was inhibited.

CONCLUSIONS

The oral administration of GSNO significantly suppressed the levels of inflammatory mediators in the retinas of EAU mice. This suppression was associated with the maintenance of normal retinal histology and function. These results clearly demonstrated the therapeutic potential of GSNO in EAU, and provide new insights for the treatment of human uveitis.

Treatment of rheumatoid arthritis

PURPOSE

Current and investigational treatments of rheumatoid arthritis (RA) are described.

SUMMARY

The current therapies used to treat RA include nonsteroidal antiinflammatory drugs (NSAIDs), used for the management of pain and inflammation; disease-modifying antirheumatic drugs (DMARDs), used as first-line therapy for all newly diagnosed cases of RA; and biological-response modifiers, targeted agents that selectively inhibit specific molecules of the immune system. Glucocorticoids and other antirheumatic drugs are also used to treat RA. DMARDs include methotrexate, hydroxychloroquine, sulfasalazine, and leflunomide. NSAIDs and glucocorticoids are effective in controlling the pain, inflammation, and stiffness related to RA. Unlike NSAIDs, they slow clinical and radiographic progression of RA. The biological-response modifiers include infliximab, etanercept, and adalimumab (inhibitors of tumor necrosis factor [TNF]-alpha); anakinra, a recombinant inhibitor of interleukin-1; abatacept, the first costimulation blocker; and rituximab, a chimeric anti-CD20 monoclonal antibody. Investigational therapies for RA include anti-interleukin-6-receptor monoclonal antibodies, new TNF-alpha inhibitors (including one for oral administration), and antibodies against proteins critical for B-cell function and survival. Data accumulated in the past decade favor early aggressive therapy for patients suspected of having RA, including early referral to a rheumatologist, new diagnostic techniques, and aggressive therapy with DMARDs, glucocorticoids, and biological agents. The benefits of this approach have been demonstrated in clinical trials.

CONCLUSION

Pharmacologic treatments of RA include NSAIDs, glucocorticoids, DMARDs, and biological agents. With an improved understanding of the pathophysiology of RA and the evidence from various clinical trials with the agents, early aggressive therapy with a combination of drugs or biological agents may be warranted for the effective treatment of RA.

Expression and proinflammatory role of proteinase-activated receptor 2 in rheumatoid synovium: ex vivo studies using a novel proteinase-activated receptor 2 antagonist

OBJECTIVE

Serine proteinases activate the G protein-coupled receptor, proteinase-activated receptor 2 (PAR-2), via cleavage and exposure of a tethered ligand. PAR-2 is known to exert proinflammatory actions in a murine model of arthritis, since PAR-2-deficient mice exhibit strikingly reduced articular inflammation. This study was undertaken to examine synovial PAR-2 expression and to determine the effect of a novel PAR-2 antagonist on synovial cytokine production, in order to investigate the hypothesis that PAR-2 plays a critical role in the pathogenesis of rheumatoid arthritis (RA).

METHODS

Using a monoclonal antibody to human PAR-2, expression in RA synovium and cultured synovial fibroblasts was characterized. The novel PAR-2 antagonist, ENMD-1068, was added to primary cultures of RA synovial tissue, from which spontaneous cytokine release was measured.

RESULTS

PAR-2 was substantially up-regulated in RA synovium compared with control synovial tissue from patients with osteoarthritis or seronegative inflammatory arthritis, neither of which exhibited significant PAR-2 expression. Importantly, spontaneous release of tumor necrosis factor alpha and interleukin-1beta from RA synovium was substantially inhibited by ENMD-1068, in a dose-dependent manner.

CONCLUSION

These findings identify PAR-2 as a novel upstream regulator of proinflammatory cytokine production in RA and indicate its potential as a novel therapeutic target in inflammatory arthritis.

Tumor Necrosis Factor Gene Polymorphisms in Tunisian Patients With Behçet’s Disease

Behcet's disease (BD) is an inflammatory disorder that is mainly characterized by recurrent oral and genital ulcers, skin lesions, and uveitis. Recent reports focused on the genetic factors of susceptibility to this disease and especially the TNF in view of the major role played by this proinflammatory cytokine in the lesional process of Behcet's disease. In this report, we investigated the possible association between Behcet's disease and the TNF-alpha gene promoter polymorphisms -1031T/C, -308A/G, and the TNF-beta polymorphism +252A/G in Tunisian population. We compared the distribution of these polymorphisms between 89 BD patients and 157 healthy controls using polymerase chain reaction restriction fragment length-polymorphism (PCR-RFLP) analysis. The frequency of the TNF-alpha -1031C allele was significantly higher in Behcet's patients than in healthy controls (p = 0.015; chi(2) = 5.84; OR = 1.65; 95% CI = 1.08-2.54), whereas the frequencies of the TNF-alpha -308G and the TNF-beta +252G alleles were similar in the two compared groups. These results suggest that the variability of the TNF-alpha -1031T/C polymorphism can be associated with the susceptibility to Behcet's disease in our study group. Therefore, the TNF molecule may have an important genetically and/or functionally implication in the pathogenesis of BD in the Tunisian population.

Interactions between IL-32 and tumor necrosis factor alpha contribute to the exacerbation of immune-inflammatory diseases

IL-32 is a newly described cytokine in the human found to be an in vitro inducer of tumor necrosis factor alpha (TNFα). We examined the in vivo relationship between IL-32 and TNFα, and the pathologic role of IL-32 in the TNFα-related diseases – arthritis and colitis. We demonstrated by quantitative PCR assay that IL-32 mRNA was expressed in the lymphoid tissues, and in stimulated peripheral T cells, monocytes, and B cells. Activated T cells were important for IL-32 mRNA expression in monocytes and B cells. Interestingly, TNFα reciprocally induced IL-32 mRNA expression in T cells, monocyte-derived dendritic cells, and synovial fibroblasts. Moreover, IL-32 mRNA expression was prominent in the synovial tissues of rheumatoid arthritis patients, especially in synovial-infiltrated lymphocytes by in situ hybridization. To examine the in vivo relationship of IL-32 and TNFα, we prepared an overexpression model mouse of human IL-32β (BM-hIL-32) by bone marrow transplantation. Splenocytes of BM-hIL-32 mice showed increased expression and secretion of TNFα, IL-1β, and IL-6 especially in response to lipopolysaccharide stimulation. Moreover, serum TNFα concentration showed a clear increase in BM-hIL-32 mice. Cell-sorting analysis of splenocytes showed that the expression of TNFα was increased in resting F4/80⁺ macrophages, and the expression of TNFα, IL-1β and IL-6 was increased in lipopolysaccharide-stimulated F4/80⁺ macrophages and CD11c⁺ dendritic cells. In fact, BM-hIL-32 mice showed exacerbation of collagen-antibody-induced arthritis and trinitrobenzen sulfonic acid-induced colitis. In addition, the transfer of hIL-32β-producing CD4⁺ T cells significantly exacerbated collagen-induced arthritis, and a TNFα blockade cancelled the exacerbating effects of hIL-32β. We therefore conclude that IL-32 is closely associated with TNFα, and contributes to the exacerbation of TNFα-related inflammatory arthritis and colitis.

A Critical Role for Allograft Inflammatory Factor-1 in the Pathogenesis of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is characterized by massive synovial proliferation, angiogenesis, subintimal infiltration of inflammatory cells and the production of cytokines such as TNF-alpha and IL-6. Allograft inflammatory factor-1 (AIF-1) has been identified in chronic rejection of rat cardiac allografts as well as tissue inflammation in various autoimmune diseases. AIF-1 is thought to play an important role in chronic immune inflammatory processes, especially those involving macrophages. In the current work, we examined the expression of AIF-1 in synovial tissues and measured AIF-1 in synovial fluid (SF) derived from patients with either RA or osteoarthritis (OA). We also examined the proliferation of synovial cells and induction of IL-6 following AIF-1 stimulation. Immunohistochemical staining showed that AIF-1 was strongly expressed in infiltrating mononuclear cells and synovial fibroblasts in RA compared with OA. Western blot analysis and semiquantitative RT-PCR analysis demonstrated that synovial expression of AIF-1 in RA was significantly greater than the expression in OA. AIF-1 induced the proliferation of cultured synovial cells in a dose-dependent manner and increased the IL-6 production of synovial fibroblasts and PBMC. The levels of AIF-1 protein were higher in synovial fluid from patients with RA compared with patients with OA (p < 0.05). Furthermore, the concentration of AIF-1 significantly correlated with the IL-6 concentration (r = 0.618, p < 0.01). These findings suggest that AIF-1 is closely associated with the pathogenesis of RA and is a novel member of the cytokine network involved in the immunological processes underlying RA.