Increased levels of soluble tumor necrosis factor receptors in the sera and synovial fluid of patients with rheumatic diseases

Expanding the armamentarium for the spondyloarthropathies

Ankylosing spondylitis (AS) is a member of the family of spondyloarthropathies, which are inflammatory arthritides largely involving the axial skeleton and commonly accompanied by peripheral arthritis. Genetic factors, particularly the presence of HLA-B27, are major contributors to the susceptibility for AS. Despite some therapeutic advances, the treatment options for patients with AS and related disorders have been limited. Several lines of evidence have led to the hypothesis that patients with AS might benefit from treatment with tumor necrosis factor (TNF). Specifically, TNF concentrations are known to be significantly elevated in the synovium of patients with rheumatoid arthritis (RA), in the inflamed gut of patients with inflammatory bowel disease, and in the inflamed sacroiliac joints of patients with AS. The anti-TNF agents have been shown to be of benefit in, and currently have indications for, RA (etanercept, infliximab, adalimumab), Crohn's disease (infliximab), and psoriatic arthritis (etanercept). Because the spondyloarthropathies share pathogenetic mechanisms with the above-specified disease states, studies have been conducted to evaluate the effectiveness of anti-TNF agents in several disorders, including AS. Data from clinical trials so far with infliximab and etanercept show that patients with AS and related disorders achieve significant improvement in clinical signs and symptoms based on validated outcomes measures. Computed tomography and magnetic resonance imaging (MRI) can facilitate the early diagnosis of AS. Studies with infliximab using MRI together with updated scoring methods demonstrated significant decreases in associated spinal inflammation. TNF antagonist therapy is well tolerated in patients with AS, with a side effect profile consistent with the prior experience of patients with RA.

Thyrocytes isolated from autoimmune-diseased thyroids secrete soluble tumor necrosis factor-R1 that is related to their elevated protein kinase C activity

Soluble tumor necrosis factor (TNF)-alpha receptors have the potential to modulate TNF-alpha activity during autoimmune thyroiditis. In this study we examined cell-surface TNF-alpha receptors and soluble TNF-alpha receptor production by thyrocytes from normal and MRL-lpr(-/-) (diseased) mice, which spontaneously develop autoimmune thyroiditis. We found that murine thyrocytes possess the 55-kd receptor (TNF-R1). Examination of soluble TNF-R1 production revealed that diseased thyrocytes produced sevenfold more soluble TNF-R1 than normal thyrocytes. Furthermore, basal protein kinase C (pKC) activity in diseased thyrocytes was 67% higher than that found in normal murine thyrocytes. The elevated basal pKC activity in diseased thyrocytes was related to their enhanced production of soluble TNF-R1 because inhibition of pKC activity with calphostin C caused soluble TNF-R1 production to decrease significantly. Additionally, soluble TNF-R1 production by murine thyrocytes was not a result of cell-surface receptor shedding but through secretion of a truncated version of TNF-R1. This was evident when cell-surface TNF-R1 levels were unchanged after treatment of diseased thyrocytes with calphostin C. Also, the 28-kd form of TNF-R1, which corresponds to the soluble receptor, was present in the intracellular membranes of the diseased thyrocytes.

Role of novel biological therapies in psoriatic arthritis: effects on joints and skin

Psoriatic arthritis (PsA) is a partly debilitating disease that may affect small and large joints and the spine. Patients with PsA are divided into different subgroups according to joint involvement and their disease may be classified as part of the spectrum of spondyloarthritides or seronegative rheumatoid arthritis. Traditional treatment comprises nonsteroidal anti-inflammatory drugs, systemic and intra-articular corticosteroids and disease-modifying antirheumatic drugs such as sulfasalazine, methotrexate and cyclosporin. On the basis of the very recent studies performed in the US and Germany, patients with severe disease can be treated with anti-tumour necrosis factor (TNF) therapy. Biologicals such as etanercept and infliximab have been used successfully to treat PsA. While etanercept is a 75kD TNF receptor fusion protein that binds to TNFalpha and TNFbeta, infliximab is a chimeric monoclonal antibody that binds to TNFalpha both in its soluble form in the serum and on the cell membrane. Adalimumab is a fully humanised antibody recognising TNFalpha that has not been tested in PsA to date. Another biological agent, alefacept, is directed against the adhesion molecule lymphocyte function-associated antigen (LFA)-2, which is known to interfere with T-cell activation. Alefacept has been shown to be efficacious in a limited number of patients with PsA. Taken together, there has been definite recent progress in the treatment of PsA. Severely affected patients may especially have substantial benefit from therapy with biologicals directed against TNFalpha and other targets.

Tumor necrosis factor receptor II gene polymorphism and severity of rheumatoid arthritis

OBJECTIVE

The gene encoding tumor necrosis factor receptor type II (TNFRII) is a strong candidate in the pathogenesis of rheumatoid arthritis (RA). An association between a single-nucleotide polymorphism (196M/R) in exon 6 of the TNFRII gene and familial RA was recently reported. The present study was undertaken to test the hypothesis that there is an association between this polymorphism and the severity of RA.

METHODS

One hundred two white patients with early RA were included in this prospective study. The French version of the Health Assessment Questionnaire (F-HAQ) and a radiographic damage score (modified Sharp/van der Heijde method) were used to quantify the functional and structural severity of RA at baseline and after 4 years of followup. TNFRII 196M/R polymorphism genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Among the 102 patients with RA, 63 (61.8%) were homozygous for the 196M allele, 36 (35.3%) were heterozygous for alleles 196M and 196R, and 3 (2.9%) were homozygous for the 196R allele. At baseline, the median radiographic and F-HAQ scores did not differ between RA patients who carried the 196R allele and those who did not. After 4 years of followup, the F-HAQ score was higher in RA patients carrying the 196R allele (median 1 [interquartile range (IQR) 0.125, 1.375]) than in noncarriers (0.375 [IQR 0, 1]) (P = 0.02), while the median radiographic score did not differ between RA patients who carried the 196R allele and those who did not.

CONCLUSION

The results of the present study support the hypothesis that there is an association between the TNFRII 196 M/R gene polymorphism and the functional severity of early RA.

Arthritis suppressor genes TIA-1 and TTP dampen the expression of tumor necrosis factor alpha, cyclooxygenase 2, and inflammatory arthritis

TIA-1 and TTP are AU-rich element-binding proteins that prevent the pathological overexpression of tumor necrosis factor alpha (TNF-alpha). TIA-1 inhibits the translation of TNF-alpha transcripts, whereas TTP promotes the degradation of TNF-alpha transcripts. Here we show that TIA-1 and TTP function as arthritis suppressor genes: TIA-1(-/-) mice develop mild arthritis, TTP(-/-) mice develop severe arthritis, and TIA-1(-/-)TTP(-/-) mice develop very severe arthritis. Peritoneal macrophages derived from all three genotypes overexpress cyclooxygenase 2 and TNF-alpha. Surprisingly, lipopolysaccharide-activated TIA-1(-/-)TTP(-/-) macrophages secrete less TNF-alpha protein than either TIA-1(-/-) or TTP(-/-) macrophages. In these mice, arthritogenic cytokine may be produced by neutrophils that accumulate in the bone marrow and peripheral blood. Our results suggest that TIA-1 and TTP are genetic modifiers of inflammatory arthritis that can alter the spectrum of cells that produce arthritogenic cytokines.

ATNFR1genotype with a protective role in familial rheumatoid arthritis

OBJECTIVE

Results of genome scans in rheumatoid arthritis (RA) have suggested that the tumor necrosis factor receptor I (TNFRI) and TNFRII loci (TNFR1 and TNFR2) are susceptibility loci. A TNFR2 polymorphism was found to be associated with familial RA. TNFR1 is mutated in TNFR-associated periodic syndrome (TRAPS). We undertook this study to test the TNFR1 exonic polymorphism closest to the TRAPS mutations site (+36 A/G) for association with RA.

METHODS

DNA samples were available from two groups of the French Caucasian population: 1) 100 families with 1 RA patient and both parents and 2) 86 RA index patients from families with at least 2 siblings with RA (affected sibpairs [ASPs]). The +36 A/G polymorphism of TNFR1 was genotyped by polymerase chain reaction-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, the genotype relative risk, and a linkage-based test previously described.

RESULTS

A negative association between RA and the +36 A/A genotype, suggested in the first sample (P = 0.084), was demonstrated in the second (ASP RA) sample (odds ratio [OR] 0.465; P = 0.012) and confirmed by the linkage-based test (OR 0.17; P = 0.008). The protective genotype, present in 41% of controls, was less frequent in RA patients: 33% in the first sample, 24% in the ASP RA sample, and 11% in the linkage-derived subgroup. Distribution of both TNFR2 196 R/R and TNFR1 +36 A/A genotypes in the ASP RA sample showed that both suspected genotypes were exclusive.

CONCLUSION

We found evidence for an association between RA and a TNFR1 protective genotype, restricted to familial RA. Distribution of the TNFR2 196 R/R and TNFR1 +36 A/A genotypes in familial RA could suggest an interaction between TNFR1 and TNFR2 in the genetic susceptibility for RA.

Progression of radiographic changes in the temporomandibular joints of patients with rheumatoid arthritis in relation to inflammatory markers and mediators in the blood

The aim of this study was to investigate longitudinal radiographic changes in the temporomandibular joint (TMJ) with clinical involvement of rheumatoid arthritis (RA) and its relation to the blood level of inflammatory mediators and markers. Sixteen patients were investigated by computed tomography on two occasions 25-46 months apart. The radiographs were assessed independently for changes in presence of erosions, sclerosis, flattening, osteophytes, and subchondral pseudocysts. The serum (S) or plasma (P) concentrations of C-reactive protein (CRP), thrombocyte particle concentration, scrotonin (S-5-HT and P-5-HT), tumor necrosis factor alpha, interleukin-1 receptor antagonist, tumor necrosis factor soluble receptor type II, interleukin-1 soluble receptor type II (P-IL-1sRII) and interleukin 6 as well as the erythrocyte sedimentation rate (ESR) were measured. The radiographic status showed no consistent or significant change during the observation period, but the individual variation was considerable. The radiographic signs of erosion and sclerosis varied most. Regression of erosions was associated with high S-5-HT and P-IL-1sRII, while progression of erosions was associated with high P-5-HT. Regression of sclerosis was associated with an increase in P-5-HT and high ESR. Progression of flattening was associated with high CRP. In conclusion, this study indicates that the progression of radiographic changes that occurs in the TMJ of patients with well-controlled RA during a period of 25-46 months seems to be related to the blood levels of CRP, 5-HT, and IL-1sRII. However, only minor progression can be expected to occur, and with considerable individual variation.

Moderate hyperhomocysteinaemia and immune activation in patients with rheumatoid arthritis

BACKGROUND

Moderate hyperhomocysteinaemia related to folate deficiency has been described in patients with cardiovascular risk and also in patients with autoimmune diseases including rheumatoid arthritis (RA).

METHODS

In 33 patients with RA, serum concentrations of homocysteine and cysteine, of B-vitamins folate and vitamin B(12), and of immune activation markers neopterin and soluble 75-kDa TNF-receptor (sTNF-R75) were measured.

RESULTS

A significant proportion of patients presented with elevated homocysteine and cysteine concentrations in comparison to reference ranges of healthy control persons. Moderate hyperhomocysteinaemia coincided with decreased serum folate and with higher concentrations of sTNF-R75 and neopterin, but it was rather independent from methotrexate (MTX) therapy.

CONCLUSIONS

The coincidence of higher homocysteine and lower folate concentrations with increased concentrations of immune activation markers in patients with RA suggests that immune activation could be involved in the development of hyperhomocysteinaemia.

Cytokine inhibitors: soluble tumor necrosis factor receptor 1 and interleukin-1 receptor antagonist in Behçet’s disease

Serum levels of proinflammatory cytokines, interleukin-1 beta (IL-1beta), tumor necrosis factor alpha, (TNF-alpha), and their inhibitors, IL-1 receptor antagonist (IL-1ra) and soluble TNF receptor 1 (sTNFR1), were determined by enzyme-linked immunosorbent assay in 104 patients with Behçet's disease (65 active, 39 inactive) and 40 healthy controls. The levels of IL-1beta and IL-1ra were significantly higher in both active and inactive patients than in control subjects (P<0.01 and P< 0.01, respectively). The concentrations of TNF-alpha and sTNFR1 were found to be higher in active patients than in controls (P< 0.01 and P< 0.001, respectively). There were no significant differences in the serum levels of these cytokines and their inhibitors between active and inactive patients. Significant increases in mean C-reactive protein level and erythrocyte sedimentation rate were found in patients with active vs inactive disease (P< 0.001 and P< 0.05, respectively). C-reactive protein values correlated with erythrocyte sedimentation rate but not with cytokines or their inhibitors. Our conclusion is that elevated serum TNF-alpha and sTNFR1 seem to be important inflammatory mediators in Behcet's disease. The statistically significant increase in these levels may arise from the severity of inflammation in the tissue or organ involved.

Osteoprotegerin protects against generalized bone loss in tumor necrosis factor-transgenic mice

OBJECTIVE

To investigate the role of tumor necrosis factor (TNF) in systemic bone loss of chronic inflammatory conditions, such as rheumatoid arthritis (RA), and to address the therapeutic potential of osteoclast blockade.

METHODS

We investigated systemic bone changes in human TNF transgenic (hTNFtg) mice, which spontaneously developed severe inflammatory arthritis.

RESULTS

Osteodensitometry revealed a significant decrease in trabecular bone mineral density (BMD) (-37%) in hTNFtg mice, and histomorphometry revealed a dramatic loss of bone volume (-85%) compared with wild-type controls. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly elevated, suggesting increased osteoclast-mediated bone resorption in hTNFtg mice. Osteoprotegerin (OPG) completely blocked TNF-mediated bone loss by increasing BMD (+89%) and bone volume (+647%). Most strikingly, formation of primary spongiosa was dramatically increased (+563%) in hTNFtg mice after OPG treatment. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly decreased by OPG, suggesting effective blockade of osteoclast-mediated bone resorption. OPG did not influence levels of hTNF, TNF receptor I (TNFRI), interleukin-1beta (IL-1beta), and IL-6. However, OPG decreased bone formation parameters (osteoblast-covered bone surface and serum osteocalcin levels), which were elevated in hTNFtg mice. In contrast to OPG, bisphosphonates and anti-TNF treatment did not affect generalized bone loss in hTNFtg mice. Anti-TNF, however, did not affect levels of TNF and TNFRI at the concentrations tested. These data indicate that generalized bone loss due to increased TNF can be blocked by OPG.

CONCLUSION

OPG may represent a potent tool for preventing generalized loss of bone mass in chronic inflammatory disorders, especially RA.

Etanercept: an updated review of its use in rheumatoid arthritis, psoriatic arthritis and juvenile rheumatoid arthritis

Etanercept is a subcutaneously administered biological response modifier that binds and inactivates tumour necrosis factor-alpha, a proinflammatory cytokine. In patients with early active rheumatoid arthritis, etanercept 25mg twice weekly was associated with a more rapid improvement in disease activity and a significantly greater cumulative response than methotrexate over 12 months of treatment in a randomised, double-blind trial. In addition, etanercept recipients showed a slower rate of radiographic progression and a more rapid improvement in quality of life than methotrexate recipients. The efficacy of etanercept was maintained at 3 years' follow-up. Etanercept was also significantly better than placebo at reducing disease activity in patients who had an inadequate response to previous treatment with disease-modifying antirheumatic drugs (DMARDs) in several well controlled trials. At study end (after 3 or 6 months' treatment), the percentage of patients achieving an American College of Rheumatology 20% (ACR20) response with etanercept (25mg or 16 mg/m(2) twice weekly) was 59 to 75% as monotherapy and 71% in combination with methotrexate; corresponding placebo response rates were 11 to 14% and 27%, respectively. Response has been maintained in patients who continued treatment for up to 5 years. In patients with psoriatic arthritis, etanercept 25mg twice weekly significantly reduced disease activity and improved skin lesions in two double-blind, placebo-controlled, 12- to 24-week trials. In the 24-week study, ACR20 response rates (50 vs 13%), psoriatic arthritis response rates (70 vs 23%) and the median improvement in skin lesions (33 vs 0%) were significantly greater in etanercept than in placebo recipients. In patients with polyarticular-course juvenile rheumatoid arthritis, etanercept resulted in improvements in all measures of disease activity and was significantly more effective than placebo at reducing disease flare. Eighty percent of patients receiving etanercept achieved a >or=30% reduction in disease activity over 7 months of treatment, and this was maintained for up to 2 years in a trial extension. Etanercept was generally well tolerated in children and adults in clinical trials; the most commonly occurring adverse effects included injection site reactions, infection, headache, rhinitis and dizziness. In conclusion, etanercept has emerged as an important new treatment option in inflammatory arthritis. Etanercept provides rapid and sustained improvements in disease activity in patients with early and DMARD-refractory rheumatoid arthritis and has been shown to inhibit radiographic progression in those with early disease. Well controlled studies have also demonstrated the efficacy of etanercept in patients with psoriatic arthritis or polyarticular-course juvenile rheumatoid arthritis.

Developing a service for biologic therapies: a personal experience

Tumour necrosis factor alpha (TNFalpha) has been identified in the pathogenesis of synovitis and joint destruction in rheumatoid arthritis (RA) and juvenile idiopathic arthritis (JIA). Therefore selected targeting of pathogenic elements of disease is possible (Chu et al., 1991). TNFalpha is a pro-inflammatory cytokine (mediator) and the over-expression of mediators is considered to be responsible for the damage to articular cartilage in bones. Elevated levels of TNFalpha, correlating with disease activity, have been measured in the serum and synovial fluid of patients with rheumatic diseases and are therefore an ideal target for therapy (Mangge et al., 1995; Cope et al., 1992). The National Institute for Clinical Excellence (NICE) approved the use of two therapies; entanercept (Enbrel) and infliximab (Remicade) for use in patients with active RA in 2002 (NICE, 2002). Other biologic treatments including adalimumab (D2E7) and anakinra (Kineret) will also be available for use in the future. This paper explores the development of a service to provide these therapies to patients.

Signaling to gene activation and cell death by tumor necrosis factor receptors and Fas

Tumor necrosis factor (TNF) receptors and Fas elicit a wide range of biological responses, including cell death, cell proliferation, inflammation, and differentiation. The pleiotropic character of these receptors is reflected at the level of signal transduction. The cytotoxic effects of TNF and Fas result from the activation of an apoptotic/necrotic program. On the other hand, TNF receptors, and under certain conditions also Fas, exert a proinflammatory function that results from the induction of several genes. In this context, the transcription factor nuclear factor-kappa B (NF-kappaB) plays an important role. NF-kappaB is also important for the induction of several antiapoptotic genes, which explains at least partially why several cell types can only be killed by TNF in the presence of transcription or translation inhibitors. It is the balance between proapoptotic and antiapoptotic pathways that determines whether a cell will finally die or proliferate. A third signal transduction pathway that is activated in response to TNF is the mitogen-activated protein kinase cascade, which plays an important role in the modulation of transcriptional gene activation.

Association between tumor necrosis factor receptor II and familial, but not sporadic, rheumatoid arthritis: evidence for genetic heterogeneity

OBJECTIVE

Tumor necrosis factor alpha (TNFalpha) binds the receptors TNFRI and TNFRII. Results of genome scans have suggested that TNFR2 is a candidate rheumatoid arthritis (RA) locus. A case-control study in a UK Caucasian population has shown an association between a TNFR2 genotype (196R/R in exon 6) and familial, but not sporadic, RA. The present study was undertaken to test this association in the French Caucasian population.

METHODS

To test for an association in sporadic RA, 100 families were genotyped for the 196M/R polymorphism and analyzed using the transmission disequilibrium test and haplotype relative risk. To test for an association in familial RA, RA index cases from 100 affected sibpair (ASP) families were genotyped for 196M/R. Linkage analysis was performed with 3 TNFR2 microsatellite markers.

RESULTS

The TNFR2 196R/R genotype was not associated with sporadic RA (odds ratio [OR] 0.59, P = 0.72), but was associated with familial RA (OR 4.0, P = 0.026). The association was most marked in the context of TNFR2 "twin-like" RA sibs (affected sibs sharing both TNFR2 haplotypes) (OR 9.2, P = 0.0017). Linkage analysis results were consistent with the association; most of the TNFR2 linkage evidence was found in the subgroup of families with 196R/R ASP index cases.

CONCLUSION

This study is the first to replicate evidence of the involvement of TNFR2 in RA genetic heterogeneity. Our data refine the initial hypothesis, to suggest that a TNFR2 recessive factor, in linkage disequilibrium with the 196R allele, plays a major role in a subset of families with multiple cases of RA.

Cytokines and anti-cytokine biologicals in autoimmunity: present and future

The increasing understanding of the role of cytokines in autoimmunity, and the observation that tumour necrosis factor alpha (TNFalpha) is central to the inflammatory and destructive process common to several human autoimmune diseases, has led to a new generation of therapeutics, the TNFalpha blocking agents. In this article, we review the current knowledge of the role of cytokines in autoimmunity as unravelled by studies both in the laboratory and the clinic. In addition, we discuss future prospects of the anti-TNFalpha therapy that may involve combination therapy with other anti-cytokine or anti-T cell biologicals, or the use of small chemicals targeting molecules involved in TNFalpha production such as NF-kappaB and p38 MAPK. The future developments of anti-TNFalpha and anti-cytokine therapy in general will be interesting.

Serum and synovial fluid concentration of vascular endothelial growth factor in juvenile idiopathic arthritides

OBJECTIVE

To evaluate the role of vascular endothelial growth factor (VEGF) in the pathogenesis of local joint inflammation in juvenile idiopathic arthritis (JIA).

METHODS

Sera from 50 patients affected with JIA and 10 age-matched healthy controls were tested with a commercial ELISA for VEGF. Corresponding synovial fluid (SF) concentrations of VEGF and p75 soluble tumour necrosis factor receptor (sTNFR) were evaluated in 20 active JIA patients.

RESULTS

Serum concentrations of VEGF were significantly higher in patients with active polyarticular disease than in patients with active and inactive oligoarticular disease and healthy controls. In JIA patients, serum concentrations of VEGF displayed a significant correlation with a number of clinical and laboratory parameters of disease activity. VEGF concentrations in SF were significantly higher than those detected in corresponding sera. Moreover, a clear correlation was found between corresponding SF and serum VEGF concentrations. In SF, VEGF showed a strong positive correlation with p75 sTNFR.

CONCLUSIONS

Concentrations of VEGF in SF in patients with JIA are higher than corresponding serum concentrations, suggesting that this pro-angiogenic factor may have a major role in the outgrowth of hyperplastic pannus and tissue damage at the site of tissue inflammation.

Tumour necrosis factor (TNF) in psoriatic arthritis: pathophysiology and treatment with TNF inhibitors

High levels of proinflammatory cytokines, including tumour necrosis factor (TNF), have been detected in psoriatic skin lesions and joints of patients with the inflammatory disease. Early results of treatment of psoriatic arthritis and psoriasis with TNF neutralising agents are encouraging, but whether these agents will be able to improve long term outcomes, such as disability, is not yet known.

Kallikrein cascade and cytokines in inflamed joints

Rheumatoid arthritis is a chronic multi-system disease of unknown aetiology. The current hypothesis is that an unknown antigen triggers an autoimmune response in a genetically susceptible individual. The predominant pathological change is that of an inflammatory synovitis, characterised by cellular infiltrates and angiogenesis, with subsequent bone and cartilage destruction. These pathological changes are as a result of the activation of a variety of cells, inflammatory mediators, and effector molecules. The pro-inflammatory kinins and cytokines appear to play a central role in the pathogenesis of rheumatoid arthritis. Sufficient evidence exists that establishes a key role for the kallikrein-kinin cascade in inflamed joints. In addition, there appears to be an inter-relationship between cytokines and kinins in the inflammatory process. Kinins induce the release of cytokines, and cytokines have been shown to augment the effects of kinins. This may lead to an enhancement and perpetuation of the inflammatory process. In this review, we report a first study, correlating markers of disease with the kallikrein-kinin cascade and with cytokines.

Clinical significance of cytokine determination in synovial fluid

Cytokines are a complex family of small regulatory proteins able to mediate intercellular communication and play a crucial role in immunologic and inflammatory reactions. Many reports have demonstrated that some cytokines, in particular tumor necrosis factor alpha (TNFalpha) and interleukin (IL)-1beta, IL-6, and IL-8, so-called proinflammatory, may have a major role in the pathogenesis of joint diseases. Thus, high levels of these substances have been found in inflammatory arthropathies, in particular in those characterized by a more aggressive and destructive outcome, such as rheumatoid arthritis, gout, and infectious arthritis. In keeping with their role, the determination of cytokines in synovial fluid may be proposed for clinical purposes, including diagnostic and prognostic assessments. Furthermore, as some of these cytokines may reflect disease activity, their determination may also be useful in the evaluation of therapy.

Studies of T-cell activation in chronic inflammation

The strong association between specific alleles encoded within the MHC class II region and the development of rheumatoid arthritis (RA) has provided the best evidence to date that CD4+ T cells play a role in the pathogenesis of this chronic inflammatory disease. However, the unusual phenotype of synovial T cells, including their profound proliferative hyporesponsiveness to TCR ligation, has challenged the notion that T-cell effector responses are driven by cognate cartilage antigens in inflamed synovial joints. The hierarchy of T-cell dysfunction from peripheral blood to inflamed joint suggests that these defects are acquired through prolonged exposure to proinflammatory cytokines such as tumour necrosis factor (TNF)-alpha. Indeed, there are now compelling data to suggest that chronic cytokine activation may contribute substantially to the phenotype and effector function of synovial T cells. Studies reveal that chronic exposure of T cells to TNF uncouples TCR signal transduction pathways by impairing the assembly and stability of the TCR/CD3 complex at the cell surface. Despite this membrane-proximal effect, TNF selectively uncouples downstream signalling pathways, as is shown by the dramatic suppression of calcium signalling responses, while Ras/ERK activation is spared. On the basis of these data, it is proposed that T-cell survival and effector responses are driven by antigen-independent, cytokine-dependent mechanisms, and that therapeutic strategies that seek to restore T-cell homeostasis rather than further depress T-cell function should be explored in the future.

Signal transduction in rheumatoid arthritis

Extracellular signals are transduced intracellularly by multiple pathways, resulting in alterations in the transcription and translation of specific proteins. The end result of some of these signalling pathways is the production of proteins, including cytokines and matrix metalloproteinases, that are implicated in the pathogenesis of rheumatoid arthritis. This chapter includes a discussion of these signal transduction pathways, including tumour necrosis factor receptor signalling, interleukin-1, -4, and -6 receptor signalling, stress- and mitogen-activated protein kinase pathways, CD14 and Toll-like receptor signalling, and T cell signal transduction. The known effects of currently available rheumatoid arthritis (RA) therapeutics on these signalling pathways are also reviewed. In addition, potential future targets for therapeutic intervention in RA are discussed.

Cytokine signalling and disease

Cytokines mediate their response via cell surface receptors that in turn activate intracellular signalling pathways and lead to gene activation, cell proliferation and differentiation. Many recent studies have shown that cytokine and cytokine receptor pathways are frequently mutated in disease, thus shedding light on the generation of the inflammatory response, specific immunity and mechanisms of haematopoiesis. Many approaches are being used to translate this basic research into successful therapies and although host immune responses involve many different cells and crucial pathways, modulation of therapeutic responses can be induced or inhibited by, targeting a single cytokine. This review summarises current knowledge of cytokine pathways in disease and the use of cytokine- or receptor-directed therapy to exploit the immune response to disease.

Rheumatoid arthritis

Rheumatoid arthritis is a systemic inflammatory disorder that mainly affects the diarthrodial joint. It is the most common form of inflammatory arthritis, and has a substantial societal effect in terms of cost, disability, and lost productivity. Although the pathogenesis of rheumatoid arthritis remains incompletely understood, much insight into the cellular and molecular mechanisms involved has been gained in the past decade. On the basis of these insights, new therapies have been developed, and clinical trials have shown the efficacy of aggressive treatment of patients with active disease. In this review, we discuss improvements in our understanding of the pathophysiology of inflammatory synovitis in rheumatoid arthritis, and improvements in therapy for patients with the disorder. The past decade has seen substantial advances in these areas. Future studies will be directed at improving methods for early diagnosis and identification of patients with progressive disease, and at improving methods to identify candidates for subclasses of disease-modifying antirheumatic drugs (DMARDs). Long-term safety and efficacy data for the new DMARD agents and combination regimens will also further delineate efficacy and toxicity and thus the appropriate clinical context for use of these therapeutic approaches. The continuing elucidation of pathophysiological pathways relevant in rheumatoid arthritis, coupled with continuing advances in biotechnology and rational drug design, offer substantial hope for the continued development of increasingly potent and specific pharmacotherapy for treatment of rheumatoid arthritis.

A second susceptibility gene for developing rheumatoid arthritis in the human MHC is localized within a 70-kb interval telomeric of the TNF genes in the HLA class III region

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease with a multifactorial genetic basis. However, pathogenic genes for RA other than the human leukocyte antigen (HLA)-DRB1 gene have yet to be identified. Here, we investigated whether there is a second susceptibility locus for RA within the human major histocompatibility complex using 18 microsatellite markers distributed from the centromeric (HSET) to the telomeric end (P5-15) of the 3.6-Mb HLA region. Statistical studies of associated alleles on each microsatellite locus showed that one pathogenic gene for RA in the HLA region is localized in the DRB1 gene, as expected. Further, a second susceptibility gene of RA was suggested to be present in the HLA class III region, narrowed to 70 kb, that is just telomeric of the TNF gene cluster (TNFA and LTA) and that is located between the microsatellites TNFa and C1-2-A. In this critical segment, four expressed genes have been thus far identified, NFKBIL1 (IkappaBL), ATP6G, BAT1, and MICB, all of which are candidate genes for determining susceptibility to RA. These results exclude the possibility of involvement of the TNFA genes (TNF-alpha) in the development of RA, which was suggested previously to be a strong candidate for RA in the class III region.

Overexpression of transcription factor Ets-1 in rheumatoid arthritis synovial membrane: regulation of expression and activation by interleukin-1 and tumor necrosis factor alpha

OBJECTIVE

To investigate the expression of the transcription factor Ets-1 in synovial tissue and cultured synovial fibroblasts from patients with rheumatoid arthritis (RA) and osteoarthritis (OA) and to study the regulation of Ets-1 expression and activation in synovial fibroblasts by proinflammatory cytokines.

METHODS

In situ expression of Ets-1 in synovial tissue from RA and OA patients was examined by double immunohistochemistry. The effects of interleukin-1 (IL-1) or tumor necrosis factor alpha (TNFalpha) on Ets-1 expression and activation (DNA binding) in cultured synovial fibroblasts were analyzed by Western blotting and DNA gel shift assay, respectively. In addition, the intracellular location of Ets-1 in synovial fibroblasts was determined by immunofluorescence.

RESULTS

Pronounced expression of Ets-1 was detected in synovial tissues from all RA patients evaluated, particularly in the synovial lining layer and the sublining areas. Ets-1 was expressed by both fibroblasts and macrophages as well as by endothelial cells, while only a few T cells stained positive for Ets-1. In synovial specimens from OA patients, Ets-1 expression was much less frequently observed and was largely restricted to vascular cells. Ets-1 was expressed to a similar degree in cultured synovial fibroblasts from RA and OA patients, as demonstrated by reverse transcriptase-polymerase chain reaction and Western blotting. Both IL-1 and TNFalpha induced pronounced up-regulation of Ets-1 in synovial fibroblasts. Moreover, binding of Ets-1 to its specific DNA binding site was induced by both cytokines, although with different time courses. Immunofluorescence staining revealed a dominant nuclear localization of Ets-1 in IL-1- or TNFalpha-stimulated synovial fibroblasts.

CONCLUSION

The overexpression of Ets-1 observed in RA synovial tissue appears to be caused by TNFalpha and IL-1, suggesting that Ets-1 may be an important factor in the cytokine-mediated inflammatory and destructive cascade characteristic of RA.

Physiology of cytokine pathways in rheumatoid arthritis

This review has summarized the physiology of some cytokine pathways in RA, emphasizing the redundant and synergistic nature of this network. However, it is important to understand that this system is self-regulating through the action of anti-inflammatory cytokines, opposing cytokines, cytokine receptor antagonists, and possibly naturally occurring antibodies to cytokines (Figure 1). Disease results when an imbalance in the cytokine network develops, either from excess production of pro-inflammatory cytokines or from inadequate presence of natural anti-inflammatory mechanisms. The current therapeutic approaches to RA that are aimed at restoring this balance include the use of monoclonal antibodies to TNFalpha, soluble TNFalpha receptors, and IL-1Ra. Other therapeutic agents that interfere with the cytokine network are in various stages of preclinical and clinical evaluation.

Tumor necrosis factor-alpha (TNF-alpha)-induced and interleukin-1 beta (IL-1 beta)-induced shedding of TNF receptors from gingival fibroblasts

Tumor necrosis factor-alpha (TNF-alpha) exerts its functions by binding two different receptors (TNFR55 and TNFR75). Both TNFR55 and TNFR75 exist in cell-associated and soluble forms. Soluble TNF receptors (sTNFR), sTNFR55 and sTNFR75, are proteolytically shed upon inflammatory stimuli and then modulate various TNF-alpha bioactivities. As human gingival fibroblasts (HGF) can be potential targets for TNF-alpha in inflamed gingiva, we hypothesized that HGF partially modulate the cellular responses to TNF-alpha by regulating their own TNFR. In this study, the kinetics of expression of cell-associated and soluble forms of both receptors from cultured HGF in response to proinflammatory cytokines TNF-alpha and interleukin-1 beta (IL-1 beta) were investigated in vitro. Both TNF-alpha and IL-1 beta upregulated the gene expression of TNFR75 and did not affect that of TNFR55. TNF-alpha and IL-1 beta decreased binding of [(125)I]TNF-alpha to HGF. Moreover, TNF-alpha and IL-1 beta upregulated the release of sTNFR75 from HGF but not that of sTNFR55. These results suggest that HGF under inflammatory conditions may contribute to the inactivation of circulating TNF-alpha through the preferential induction and shedding of TNFR75.

Synovial fluid matrix metalloproteinase-3 levels are increased in inflammatory arthritides whether erosive or not

OBJECTIVE

To study the levels of matrix metalloproteinase-3 (MMP-3) in the knee synovial fluid (SF) of inflammatory arthropathies (rheumatoid arthritis whether erosive or not, reactive arthritis, acute crystal arthritis) and degenerative arthropathies [chronic crystal disease, osteoarthritis and (control) meniscus pathology] and to correlate them with the degree of joint destruction, local inflammatory and immune parameters and systemic markers of inflammation.

METHODS

SF levels of MMP-3 (precursor, active and tissue inhibitor of MMP-bound forms), tumour necrosis factor (TNF) alpha, soluble TNF receptors I and II, interleukin (IL)-6 and soluble IL-6 receptor were measured by ELISA in 107 inflammatory and 53 degenerative arthropathies.

RESULTS

MMP-3 levels in SF were (i) significantly higher in inflammatory than in degenerative arthropathies; (ii) not related to the degree of joint destruction; (iii) significantly correlated with the levels of all SF markers tested and with erythrocyte sedimentation rate and serum levels of C-reactive protein and fibrinogen.

CONCLUSION

Increased MMP-3 levels in SF are found in inflammatory arthropathies and are not specific for erosive joint diseases. MMP-3 in SF is therefore a potential candidate for the assessment of the inflammatory process in joints. However, the exclusive determination of the active form could indicate the degree of joint destruction.

Treatment of rheumatoid arthritis: etanercept a recent advance

PURPOSE

To review the specific mechanism of action of biologic response modifiers and help clinicians place these new drugs in the context of established therapies for rheumatoid arthritis (RA).

DATA SOURCES

Review of scientific literature, including all the clinical trials for these drugs.

CONCLUSIONS

Biologic response modifiers target key inflammatory events involved in joint destruction. They have the potential to revolutionize the management of RA.

IMPLICATIONS FOR PRACTICE

Referral to a rheumatologist should be strongly considered as soon as the diagnosis of RA is made. Early referral to a specialist has been associated with improved health status for patients with RA due to early and aggressive therapy with these new agents.

Serum level of soluble tumor necrosis factor receptor II (sTNF-R75) is apparently an index of overall monocyte-related infectious and inflammatory activity

BACKGROUND

The serum level of soluble tumor necrosis factor receptor II (sTNF-R75) has been recently found to correlate with the activity and/or severity of several different infectious and inflammatory diseases. These results have led us to presume that the serum sTNF-R75 level reflects the active immune activity of all causes and may correlate well with nonspecific infectious and inflammatory markers such as peripheral leukocyte counts and serum C-reactive protein level.

METHODS

In total, 110 apparently healthy adults, 55 men and 55 women, were enrolled in the study. Serum levels of sTNF-R75, C-reactive protein, globulin, alkaline phosphatase, lactate dehydrogenase, creatinine, urea nitrogen, and counts of neutrophils, lymphocytes, monocytes, eosinophils, and basophils were checked. The relationships between the serum sTNF-R75 level and other parameters were analyzed using the SAS statistical program.

RESULTS

By various statistical methods, the serum sTNF-R75 level showed consistently significant positive links with peripheral monocyte count, serum C-reactive protein level, and two parameters of renal clearance function (serum urea nitrogen and creatinine levels). Serum levels of alkaline phosphatase and lactate dehydrogenase had significant positive links with the serum sTNF-R75 level by multivariate regression analysis. There was no significant link between the serum sTNF-R75 level and counts of neutrophils, lymphocytes, eosinophils, or basophils.

CONCLUSIONS

Our results, together with those of recent reports showing positive correlations between the serum sTNF-R75 level and activities/severities of different infectious and inflammatory diseases, and also that TNF-alpha is principally produced by monocytes and macrophages, suggest that the serum sTNF-R75 level is very probably an index of overall monocyte-related infectious and inflammatory activities.

Serum level of soluble tumour necrosis factor receptor II (75 kDa) indicates inflammatory activity of sarcoidosis

OBJECTIVES

Tumour necrosis factor alpha (TNFalpha) is a key cytokine involved in granuloma formation of sarcoidosis. Since soluble TNF receptors (sTNF-R) are known to inhibit TNF effects, we were interested in whether they are elevated in the serum of sarcoidosis patients.

METHODS

We determined serum levels of sTNF-R I (55 kDa) and sTNF-R II (75 kDa) in 49 patients with sarcoidosis and 22 controls. The clinical course of the disease was re-evaluated in a follow-up after (mean +/- SE) 6.8 +/- 6.6 months.

RESULTS

sTNF-R I (3.1 +/- 1.1 ng mL-1, P < 0.05) and sTNF-R II (5.5 +/- 2.7 ng mL-1, P < 0.0005) were significantly elevated in sarcoidosis compared with controls (2.4 +/- 0.7 and 3.0 +/- 1.3 ng mL-1, respectively). Interestingly, both sTNF receptors were significantly higher in the serum of patients with active compared with inactive sarcoidosis (P < 0.005 and P < 0.0005, respectively). Furthermore, serum sTNF-R II levels were significantly higher in sarcoidosis patients with advanced radiological types II and III. In 10 patients, serum sTNF-R levels were obtained before and after systemic corticosteroid therapy and we observed a significant decrease of sTNF-R II (P < 0.02), whereas sTNF-R I levels were not reduced significantly.

CONCLUSIONS

Both types of sTNF receptors are elevated in the serum of sarcoidosis patients with active disease, but only the sTNF-R II seems to be useful for monitoring the inflammatory activity of the disease.

Anti-cytokine therapy for rheumatoid arthritis

Tumor necrosis factor alpha (TNF alpha) and interleukin-1 (IL-1) are important in mediating inflammation in rheumatoid arthritis (RA). Randomized phase II and III clinical trials of anti-TNF reagents (infliximab and etanercept) have demonstrated an acceptable safety profile and marked clinical efficacy in cases of RA that have not responded adequately to conventional therapy. Combination therapy with methotrexate (MTX) appears to be particularly effective in patients whose disease activity persists despite prior disease-modifying antirheumatic drugs (DMARDs) and ongoing MTX monotherapy. DMARD-recalcitrant disease may become the main indication for the use of anti-TNF drugs in patients with RA. Trials of IL-1 receptor antagonist show a relatively modest anti-inflammatory effect and a possible retardation of joint damage. Whether anti-TNF therapy protects joints from structural damage is under investigation. One anti-TNF reagent has already been approved in the United States for the treatment of RA, and other cytokine antagonists or agonists are under development.

Tumor necrosis factor alpha can contribute to focal loss of cartilage in osteoarthritis

OBJECTIVE; To evaluate the potential for tumor necrosis factor alpha (TNFalpha)-induced focal loss of cartilage in osteoarthritic (OA) knee joints.

DESIGN

Fresh cartilage from specified regions of OA joints was immunostained for TNF-receptor (R) bearing chondrocytes. Cartilage explants from the same regions were cultured with or without small amounts of TNFalpha and cumulative GAG release into supernatants measured. Concentrations of TNFalpha, p55 and p75 soluble (s) TNF-R in supernatants from cultured OA and non-arthritic (NA) synovium were measured by ELISA.

RESULTS

TNF-R bearing chondrocytes were identified in OA cartilage; more specimens contained p55 TNF-R- than p75 TNF-R-bearing chondrocytes and differences in TNF-R distribution were apparent in cartilage from different regions of the same knees. TNFalpha at 5, 1, 0.5 and 0.25 ng/ml (but not 0.1 ng/ml) significantly increased glycosaminoglycans (GAG) release from cartilage explants in a dose-dependent manner. Variation in susceptibility to TNFalpha was observed in explants from different sites. TNFalpha and p75 sTNF-R, but not p55 sTNF-R, concentrations were significantly higher in OA, as compared with NA, supernatants. A significant correlation between TNFalpha and p75 sTNF-R measurements was apparent only in NA supernatants.

CONCLUSIONS

Variations in chondrocyte TNF-R expression occur in OA cartilage in vivo. TNFalpha at concentrations produced by OA synovium in vitro, can degrade cartilage matrix. In most OA supernatants sTNF-R concentrations were insufficient to abrogate the effects of TNFalpha. Thus conditions exist in some OA knees for TNFalpha to contribute to focal loss of cartilage.

Soluble tumor necrosis factor alpha receptors (sTNF-Rs) in HIV-1-infected intravenous drug users: change in circulating sTNF-R type II level and survival for AIDS patients

This study in intravenous drug users (IVDUs) investigated differences in serum soluble tumor necrosis factor types I and II (sTNFR-I and II) concentrations in HIV-1-infected IVDUs and controls. This study also investigated whether changes of sTNFRs concentration affect the risk of death among patients with AIDS. A cross-sectional study of 54 subjects with AIDS, 47 HIV-seropositive IVDUs, 47 HIV-seronegative IVDUs, and 21 healthy subjects showed that sTNFRs concentration increases from healthy controls to AIDS patients through HIV-seronegative and HIV-seropositive subjects (p < 0.01). sTNFR-I concentration, however, was shown to be similar in HIV-seronegative IVDUs and healthy controls. In the longitudinal study, serum concentration of sTNFRs was determined near AIDS diagnosis in 21 IVDUs and 1 year later (start for the survival study). Cox proportional hazards regression was performed to assess the prognostic value of percent change of sTNFR level alone and in combination with T lymphocyte subsets, HIV-p24 antigenemia and opportunistic infections for death within 240 days. Uni- and multivariate Cox modelling for dichotomised variables according to its median showed an increase of sTNFR-II by at least 30% to be single significant predictor of death: crude relative risk 3.69, p = 0.03; adjusted relative risk 5.67, p = 0.02. Mean survival was 126 days in 11 patients whose sTNFR-II level increased by at least 30%, and 176 days in 10 patients with less change in sTNFR-II (p = 0.02).

CONCLUSIONS

sTNFRs concentration is higher in IVDUs than in healthy controls and is highest in AIDS patients. Survival of patients with AIDS is associated with variation in the concentration of sTNFR-II.

The pharmacokinetics of etanercept in healthy volunteers

OBJECTIVE

To describe the pharmacokinetics of etanercept when administered by subcutaneous injection in single doses to healthy volunteers.

METHODS

Twenty-six healthy volunteers between 19 and 50 years of age received single doses of etanercept 25 mg by subcutaneous injection into the abdomen. Serial serum samples were collected for 21 days. An enzyme-linked immunosorbent assay with a quantitation limit of 0.3 ng/mL was used to measure the drug concentrations.

RESULTS

Etanercept was well tolerated by healthy volunteers. A one-compartment model was found to best describe the concentration-time data and was used to determine the pharmacokinetic parameters. Etanercept is slowly absorbed from the site of injection with a time of peak concentration (+/- SD) of 51 +/- 14 hours; peak concentration was 1.46 +/- 0.72 mg/L. The AUC was 235 +/-98 mg x h/L, apparent clearance was 132 +/- 85 mL/h, apparent volume of distribution was 12 +/- 6 L, and the half-life was 68 +/- 19 hours.

CONCLUSIONS

Etanercept was slowly absorbed and slowly eliminated after subcutaneous administration. Dosing at the recommended rate of 25 mg twice weekly would be expected to result in concentrations of approximately 3 mg/L. Intersubject variability for apparent clearance in healthy volunteers was 64%.

[Rheumatoid arthritis: new molecular and cellular aspects]

BACKGROUND

Rheumatoid arthritis is a chronic systemic disorder of unknown etiology, that is characterized by inflammation, synovial hyperplasia and destruction of the affected joints. Novel molecular biology techniques have identified important cellular and molecular pathways in the pathogenesis of rheumatoid arthritis during the last years.

RESULTS

The cellular activation of aggressively growing, matrix-degrading synovial fibroblasts is a key event in the pathogenesis of rheumatoid arthritis. The cellular activation results in an altered expression of apoptosis regulating molecules (for example CD 95 and Sentrin) as well as of protooncogenes (for example RAS and MYC). Important extracellular stimuli such as the pro-inflammatory cytokines interleukin-1 and TNF-alpha are overexpressed in the rheumatoid arthritis synovium. First clinical trials with cytokine inhibiting molecules (interleukin-1 receptor antagonist, recombinant soluble TNF-alpha receptor/Etanercept and monoclonal TNF-alpha antibodies/Remicade) revealed promising results. Etanercept is now available for the treatment of rheumatoid arthritis in the USA. In addition, gene transfer methods could help to overcome the problem of a continuous expression of therapeutic molecules in the affected joints; gene delivery of the interleukin-1 receptor antagonist is currently tested in a human trial. Finally, the inhibition of matrix degrading enzymes such as matrix metalloproteinases, that mediate the joint destructive features of the activated synovial fibroblasts, could be another therapeutic approach.

CONCLUSIONS

The elucidation of important molecular and cellular pathways in the pathogenesis resulted in novel concepts in the therapy of rheumatoid arthritis. Gene transfer methods are of importance in studying the pathogenesis of the disease, however, their clinical safety and usefulness have to be proven in additional studies.

Therapy of rheumatoid arthritis: new developments and trends

The medical therapy of rheumatoid arthritis (RA) has been influenced strongly during the past decade by the recognition that many patients develop joint damage within the first year of disease. This observation has motivated rheumatologists to initiate disease-modifying antirheumatic drugs (DMARDs) early in the disease course. This trend has been matched by the increased use of combination DMARD therapy, with the aim to maximize control of the signs and symptoms of RA and limit the development of joint damage. The results from controlled clinical trials generally have supported the concept that early, aggressive treatment with DMARDs is superior to less intensive strategies. In addition, certain DMARD combinations are more effective than the individual components of these regimens, but the evidence is strong for only a few DMARD combinations such as methotrexate and cyclosporine A. Three new drugs have been recently approved for the treatment of RA. Celecoxib, a selective cyclooxygenase-2 inhibitor, has similar clinical efficacy as conventional nonsteroidal anti-inflammatory drugs, and in short-term studies causes no more gastric and duodenal ulcers and erosions than patients treated with placebo. Treatment with leflunomide, an inhibitor of pyrimidine synthesis, has been shown in controlled clinical trials to produce significant clinical improvement in 50% to 60% of patients with RA and delay radiologic progression of disease. The era of biologic therapy has dawned with the apparent success of tumor necrosis factor (TNF)-alpha blockade using etanercept, a recombinant TNF receptor:Fc fusion protein, and infliximab, a chimeric anti-TNF monoclonal antibody. These new agents expand our treatment options in RA and should lead to innovative and more effective treatment approaches.

Interaction between tumor necrosis factor microsatellite polymorphisms and the HLA-DRB1 shared epitope in rheumatoid arthritis: influence on disease outcome

OBJECTIVE

To investigate whether interactions between tumor necrosis factor (TNF) microsatellite polymorphisms and the HLA-DRB1 shared epitope (SE) are associated with disease severity in rheumatoid arthritis (RA), and to determine if such associations are the same in male and female patients.

METHODS

Genotyping for the TNFa microsatellite and HLA-DRB1 was carried out on 157 RA patients with established disease (duration >5 years). Disease severity measures included radiographic damage (the Larsen method), functional assessment by the Health Assessment Questionnaire, history of joint surgery, and global appraisal of outcome by means of a visual analog scale score. The association of severity measures with TNFa microsatellite polymorphisms stratified by SE status, and the interaction between TNFa and the SE, were investigated using stratified analyses and multiple or logistic regression analyses.

RESULTS

No significant associations were observed between any single TNFa microsatellite polymorphism and disease severity, although preliminary evidence for an interaction between TNFa6 and TNFa11 was obtained. In the presence of the SE, a significantly worse outcome was associated with individuals carrying TNFa6, and a significant interaction (P = 0.04-0.006) was found between these alleles for all the outcome measures examined except history of joint surgery. In the absence of the SE, the TNFa6 allele was associated with significantly better outcome scores. When examined by sex, significant associations between the TNFa6/SE haplotype and disease outcome measures were found only in females. No statistically significant interactions were found in males, although the TNFa6/SE haplotype was still associated with the worst outcome scores.

CONCLUSION

The association of the SE with disease severity in RA is influenced by an interaction with the TNFa6 microsatellite polymorphism. This interaction appears to be acting predominantly in female patients, although the trend is similar in the smaller percentage of males carrying the TNFa6/SE haplotype.

Pathogenesis of joint damage in rheumatoid arthritis: evidence of a dominant role for interleukin-I

Chronic arthritis is characterised by persistent joint inflammation and concomitant joint destruction. Although joint swelling is a major clinical feature, destruction of bone and cartilage may be dissociated from inflammation. It is therefore important to understand fully all elements of the destructive process. Tumour necrosis factor (TNF) and interleukin-I (IL-I) are considered pivotal cytokines in the process of human rheumatoid arthritis (RA), with a claimed cascade of TNF inducing most of the IL-I production. Studies in experimental models have revealed that TNF is indeed a pivotal cytokine in acute joint swelling, yet IL-I beta is the dominant cartilage destructive cytokine and its production may occur independently of TNF alpha. This was found with anti-TNF/IL-I neutralising antibodies and the observations were recently supported by similar findings in arthritis models in TNF and IL-I knock-out mice. In RA, early clinical studies suggested a correlation between levels of IL-I beta and measures of joint damage. In vitro studies have also demonstrated regulatory effects of IL-I beta on both cartilage degradation and cartilage invasion by synoviocytes. A randomised clinical trial has suggested a significant reduction in the rate of joint damage following IL-I beta inhibition by IL-I receptor antagonist. Clinical trials of TNF alpha blockade have demonstrated a marked reduction in the clinical manifestations of inflammation but, to date, an effect on the rate of joint damage awaits confirmation.

Serum levels of soluble interferon Alfa/Beta receptor as an inhibitory factor of interferon in the patients with chronic hepatitis C

Human serum contains a soluble form of interferon alfa/beta (sIFN alpha/beta) receptors, the functional and clinical significance of which has not been investigated in patients with chronic hepatitis C. In the present study, serum levels of sIFN alpha/beta receptor were assessed in 81 patients with chronic hepatitis C and correlated with the effectiveness of IFN therapy in these patients. Serum levels of sIFN alpha/beta receptor were significantly higher in patients with chronic hepatitis C than in healthy control patients (P <.0001). In these patients, serum levels of sIFN alpha/beta receptor were correlated with those of alanine transaminase (ALT) (P <.05), (2'-5')serum oligo(A) synthetase (2-5AS) (P <.0001), and pathological stages of liver fibrosis (P <.01). In 55 patients with chronic hepatitis C who underwent IFN therapy, there was an inverse correlation between the pretherapeutic serum levels of sIFN alpha/beta receptor and the rate of increase in serum levels of 2-5AS after the start of IFN (P <.01). Pretherapeutic serum levels of sIFN alpha/beta receptor were significantly lower in patients who showed sustained response to IFN therapy compared with those who did not respond to the therapy (P <.05). Multivariate analysis showed that low levels of serum sIFN alpha/beta receptor (</=4.0 ng/mL) (P <.05) and serological hepatitis C virus genotype II (P <.05) were independent variables contributing to sustained response to IFN therapy. Thus, pretherapeutic serum levels of sIFN alpha/beta receptor were correlated with the effectiveness of IFN therapy, suggesting that sIFN alpha/beta receptor suppresses the effectiveness of IFN therapy in patients with chronic hepatitis C.