RHEUMASEARCH

Expression and function of junctional adhesion molecule-C in human and experimental arthritis.

Arthritis Res Ther. 2007 Jul 5;9(4):R65
 
ABSTRACT: Junctional adhesion molecule-C (JAM-C) is an adhesion molecule involved in transendothelial migration of leukocytes. In this study, we examined JAM-C expression in the synovium and investigated the role of this molecule in two experimental mouse models of arthritis. JAM-C expression was investigated by reverse transcriptase-polymerase chain reaction and immunohistochemistry. The effects of a monoclonal anti-JAM-C antibody were assessed in antigen-induced arthritis (AIA) and K/BxN serum transfer-induced arthritis. JAM-C was expressed by synovial fibroblasts in the lining layer and associated with vessels in the sublining layer in human and mouse arthritic synovial tissue. In human tissue, JAM-C expression was increased in rheumatoid arthritis (RA) as compared to osteoarthritis synovial samples (12.7 +/- 1.3 arbitrary units in RA versus 3.3 +/- 1.1 in OA; p < 0.05). Treatment of mice with a monoclonal anti-JAM-C antibody decreased the severity of AIA. Neutrophil infiltration into inflamed joints was selectively reduced as compared to T-lymphocyte and macrophage infiltration (0.8 +/- 0.3 arbitrary units in anti-JAM-C-treated versus 2.3 +/- 0.6 in isotype-matched control antibody-treated mice; p < 0.05). Circulating levels of the acute-phase protein serum amyloid A as well as antigen-specific and concanavalin A-induced spleen T-cell responses were significantly decreased in anti-JAM-C antibody-treated mice. In the serum transfer-induced arthritis model, treatment with the anti-JAM-C antibody delayed the onset of arthritis. JAM-C is highly expressed by synovial fibroblasts in RA. Treatment of mice with an anti-JAM-C antibody significantly reduced the severity of AIA and delayed the onset of serum transfer-induced arthritis, suggesting a role for JAM-C in the pathogenesis of arthritis.
 

B cell depletion may be more effective than switching to an alternative anti-tumor necrosis factor agent in rheumatoid arthritis patients with inadequate response to anti-tumor necrosis factor agents.

Arthritis Rheum. 2007 May;56(5):1417-23.
 
OBJECTIVE: Patients with rheumatoid arthritis (RA) in whom the response to anti-tumor necrosis factor (anti-TNF) therapy is inadequate have several therapeutic options, such as switching to an alternative anti-TNF agent or initiating B cell-depleting therapy with rituximab (RTX). Although both therapeutic options have been proven effective in trials, no head-to-head comparisons are available. The aim of this study was to compare the effectiveness of RTX with that of an alternative anti-TNF agent in the management of patients with RA who had an inadequate response to anti-TNF therapy.
 
METHODS: This prospective cohort study was nested within the Swiss Clinical Quality Management RA cohort and included all patients who had an inadequate response to at least 1 anti-TNF agent and subsequently received either 1 cycle of RTX or an alternative anti-TNF agent. The primary outcome was the evolution of RA disease activity (as measured on the Disease Activity Score in 28 joints [DAS28]), which was analyzed using multivariate regression models for longitudinal data. RESULTS: One hundred sixteen patients with RA were included; 50 patients received 1 cycle of RTX, and 66 patients were treated with a second or a third alternative anti-TNF agent. At baseline, there were no significant differences between the 2 groups in age, sex, disease duration, and disease activity. Evolution of the DAS28 was more favorable in the group that received RTX compared with the group that received an alternative anti-TNF agent (P = 0.01). At 6 months, the mean decrease in the DAS28 was -1.61 (95% confidence interval [95% CI] -1.97, -1.25) among patients receiving RTX and -0.98 (95% CI -1.33, -0.62) among those receiving subsequent anti-TNF therapy.
 
CONCLUSION: The results of this observational study suggest that treatment with RTX may be more effective than switching to an alternative anti-TNF agent in patients with RA in whom active disease persists despite anti-TNF therapy.
 

Molecular characterization and subcellular localization of macrophage infectivity potentiator, a Chlamydia trachomatis lipoprotein.

J Bacteriol. 2007 Jul;189(13):4739-48.
 
Macrophage infectivity potentiator (MIP) was originally reported to be a chlamydial lipoprotein from experiments showing incorporation of radiolabeled palmitic acid into native and recombinant MIP; inhibition of posttranslational processing of recombinant MIP by globomycin, known to inhibit signal peptidase II; and solubility of native MIP in Triton X-114. However, the detailed structural characterization of the lipid moiety on MIP has never been fully elucidated. In this study, bioinformatics and mass spectrometry analysis, as well as radiolabeling and immunochemical experiments, were conducted to further characterize MIP structure and subcellular localization. In silico analysis showed that the amino acid sequence of MIP is conserved across chlamydial species. A potential signal sequence with a contained lipobox was identified, and a recombinant C20A variant was prepared by replacing the probable lipobox cysteine with an alanine. Both incorporation of U-(14)C-esterified glycerol and [U-(14)C]palmitic acid and posttranslational processing that was inhibitable by globomycin were observed for recombinant wild-type MIP but not for the recombinant C20A MIP variant. The fatty acid contents of native and recombinant MIP were analyzed by gas chromatography-mass spectrometry, and the presence of amide-linked fatty acids in recombinant MIP was investigated by alkaline methanolysis. These results demonstrated a lipid modification in MIP similar to that of other prokaryotic lipoproteins. In addition, MIP was detected in an outer membrane preparation of Chlamydia trachomatis elementary bodies and was shown to be present at the surfaces of elementary bodies by surface biotinylation and surface immunoprecipitation experiments.
 

Cigarette smoking and radiographic progression in rheumatoid arthritis.

Ann Rheum Dis. 2007 Aug;66(8):1066-71.
 
BACKGROUND: Smoking is a well-established environmental risk factor for the development of rheumatoid arthritis (RA). However, it remains unclear whether smoking influences RA disease progression and whether smokers have more radiographic damage progression than non-smokers over time.
 
OBJECTIVE: To compare the rates of radiographic damage progression in current smokers and non-smokers in a large prospective RA cohort.
 
METHODS: The SCQM-RA is a population-based registry monitoring disease activity, radiographic damage and symptoms at regular intervals. All patients in the SCQM-RA database with sequential plain radiographs were included. Joint erosions were assessed in 38 hand and foot joints with a validated scoring method. The rate of erosion progression was analysed using multivariate longitudinal regression models and adjusted for potential confounders.
 
RESULTS: 2004 RA patients with a mean of 3.6 sequential radiographs and 3.1 years of follow-up were included. The 545 (27%) current smokers smoked on average 16 cigarettes per day and had a mean past smoking exposure of 20.6 pack-years. Radiographic joint damage progressed at a similar rate in current smokers and non-smokers (p = 0.26). However, smoking intensity was associated with a significant inverse dose-response; heavy smokers (>1 pack-day) progressed significantly less than non-smokers or moderate smokers (p<0.001).
 
CONCLUSION: Radiographic joint damage progressed at an equivalent rate in smokers and non-smokers. Furthermore, a significant trend was observed for reduced radiographic progression and generally more favourable functional scores among heavy smokers, suggesting that cigarette smoke does not accelerate RA disease progression.
 

Discrimination of C57BL/6J Rj and 129S2/SvPasCrl inbred mouse strains by use of simple sequence length polymorphisms.

J Am Assoc Lab Anim Sci. 2007 Mar;46(2):21-4.
 
We present a list of simple sequence length polymorphisms (SSLPs) that was used in a polymerase chain reaction (PCR)-based marker-assisted selection protocol to facilitate the generation of a C57BL/6J Rj congenic strain from a mixed 129S2/SvPasCrlxC57BL/6J Rj background. We chose informative SSLP markers that would permit evaluation of the PCR products on NuSieve agarose or nondenaturing polyacrylamide gels. This list of oligonucleotide pairs is useful for analyzing and backcrossing knockout or transgenic strains derived from 129S2/SvPasCrl or C57BL/6J Rj backgrounds.
 

Tolerance and effectiveness of anti-tumor necrosis factor alpha therapies in elderly patients with rheumatoid arthritis: a population-based cohort study.

Arthritis Rheum. 2007 May 15;57(4):679-85.
 
OBJECTIVE: Limited data have been published on tolerance to and efficacy of classic or biologic disease-modifying antirheumatic drugs in elderly patients with rheumatoid arthritis (RA). The goal of the present study was to evaluate the tolerance to and effectiveness of anti-tumor necrosis factor (anti-TNF) agents in elderly patients (> or =65 years old) with RA (ERA) in comparison with younger patients (YRA).
 
METHODS: The Swiss Clinical Quality Management program for RA is a longitudinal population-based cohort. All patients who had received at least 1 dose of anti-TNF agents between January 1997 and November 2005 were included and categorized according to their age. Tolerance was assessed by analyzing discontinuation rates of anti-TNF agents. Effectiveness of these agents was assessed by analyzing RA disease activity (Disease Activity Score in 28 joints [DAS28]) and functional disability (Health Assessment Questionnaire [HAQ]) after anti-TNF initiation. RESULTS: Among 1,571 patients with RA treated with anti-TNF agents, 344 were > or =65 years of age at treatment initiation. Drug discontinuation rates (median time 3 years) and mean change in DAS28 scores at 2 years (-0.65 versus -0.58) were identical in ERA and YRA. However, HAQ score improved significantly less in ERA (-0.02) than in YRA (-0.1) and a subsequent analysis revealed that this finding was essentially due to patients >75 years of age.
 
CONCLUSION: Age in itself should not interfere with the decision to treat elderly patients with RA with anti-TNF agents. In a subset of patients ages >75 years, no functional improvement according to HAQ should be expected despite improvements in disease activity.
 

Evidence-based review of biologic markers as indicators of disease progression and remission in rheumatoid arthritis.

Rheumatol Int. 2007 Jul;27(9):793-806.
 
Rheumatoid arthritis (RA) is a chronic, immune-mediated inflammatory disease characterised by inflammation resulting in structural joint damage and functional disability. Tumour necrosis factor-alpha (TNFalpha) is a pivotal mediator and driver of inflammation in RA. Inflammation is closely related to the production of C-reactive protein (CRP), and a close correlation exists between serum CRP and TNFalpha levels. CRP levels are therefore a convenient, objective biomarker of disease activity. CRP correlates closely with changes in inflammation/disease activity, radiological damage and progression and functional disability. Identification of TNFalpha as a driver of RA progression has led to the introduction of TNFalpha-blocking agents and, subsequently, improvement of disease management. TNFalpha-blocking agents provide rapid, profound and sustained suppression of disease activity in correspondence with a marked reduction in CRP levels. A reduction in CRP level correlates closely with the positive clinical response to TNFalpha-blocking therapy. Thus, CRP levels can be used to predict, assess and monitor response to treatment with TNFalpha-blocking agents, and may be helpful in determining the optimal TNFalpha-blocker dosage. Given the close correlation between inflammation and disease progression and the relation between inflammation and CRP, the latter, if used effectively in clinical practice, may be means to identify patients likely to progress rapidly and who require intensive anti-TNFalpha therapy. The purpose of this review is to identify how CRP levels may be useful for monitoring the effect of therapy on halting disease progression and why monitoring CRP levels at baseline and after treatment should become a routine part of clinical practice.
 

Interleukin (IL)-33 induces the release of pro-inflammatory mediators by mast cells.

Cytokine. 2007 Dec;40(3):216-25.
 
IL-33 (or IL-1F11) was recently identified as a ligand for the previously orphaned IL-1 family receptor T1/ST2. Previous studies have established that IL-33 and T1/ST2 exert key functions in Th2 responses. In this study, we demonstrate that IL-33 induces the production of pro-inflammatory mediators in mast cells. IL-33 dose and time-dependently stimulated IL-6 secretion by P815 mastocytoma cells and primary mouse bone marrow-derived mast cells (BMMC). This effect was dependent on T1/ST2 binding. In addition, IL-33 also induced IL-1beta, TNF-alpha, MCP-1, and PGD2 production in BMMC. By RNase protection assay, we demonstrated that IL-33 increased IL-6 and IL-1beta mRNA expression. These effects of IL-33 appeared to occur independently of mast cell degranulation, The results of this study show for the first time that IL-33, a novel member of the IL-1 family of cytokines, stimulates the production of pro-inflammatory mediators by mast cells in addition to its effect on T helper 2 responses. These findings open new perspectives for the treatment of inflammatory diseases by targeting IL-33.