Rheumatoid Arthritis: Kantor S

Kremer J, Genovese M, Cannon GW, Caldwell J, Cush J, Furst DE, Luggen M, Keystone E, Bathon J, Kavanaugh A, Ruderman E, Coleman P, Curtis D, Kopp E, Kantor S, Weisman M, Waltuck J, Lindsley HB, Markenson J, Crawford B, Fernando I, Simpson K, Strand V. · Center for Rheumatology, Albany, New York 12206, USA. · J Rheumatol. · Pubmed #15290730 No free full text.

Abstract: OBJECTIVE: To obtain additional safety and efficacy data on leflunomide (LEF) treatment in combination with methotrexate (MTX) therapy in an open-label extension study in patients with rheumatoid arthritis (RA). METHODS: Following a 24 week, randomized, double-blind trial of adding placebo (PLA) or LEF to stable MTX therapy, patients could enter a 24 week extension. Subjects randomized to LEF and MTX continued treatment [(LEF/LEF) + MTX]. Subjects randomized to PLA and MTX switched to LEF (10 mg/day, no loading dose) and MTX [(PLA/LEF) + MTX]. The double-blind regarding initial randomization was maintained. RESULTS: For subjects in the extension phase, American College of Rheumatology 20% (ACR20) responder rates for the (LEF/LEF) + MTX group were maintained from Week 24 (57/96, 59.4%) to Week 48 (53/96, 55.2%). ACR20 responder rates improved in patients switched to LEF from PLA at Week 24 [(PLA/LEF) + MTX] from 25.0% (24/96) at Week 24 to 57.3% (55/96) at Week 48. Patients in the extension who switched from PLA to LEF without a loading dose exhibited a lower incidence of elevated transaminases compared to patients initially randomized to LEF. Diarrhea and nausea were less frequent during the open-label extension in patients who did not receive a LEF loading dose. CONCLUSION: Response to therapy was maintained to 48 weeks of treatment in patients who continued to receive LEF and MTX during the extension. Importantly, ACR20 response rates after 24 weeks of LEF therapy were similar between patients switched from PLA to LEF without loading dose, and those who received a loading does of LEF (100 mg/day x 2 days) at randomization. Fewer adverse events were reported in patients switched to LEF without a loading dose.

Raymond L, Eck S, Mollmark J, Hays E, Tomek I, Kantor S, Elliott S, Vincenti M. · Department of Medicine, Dartmouth Medical School, Lebanon, New Hampshire, USA. · J Cell Physiol. · Pubmed #16453302 No free full text.

Abstract: Interleukin-1 beta (IL-1beta) is a central mediator of inflammation and connective tissue destruction in rheumatoid arthritis. IL-1beta activates articular chondrocytes to produce matrix metalloproteinase-1 (MMP-1), an enzyme capable of dismantling the collagen scaffold of articular cartilage. To define the transcription factors and signaling intermediates that activate MMP-1 transcription in chondrocytes, we performed transient transfection of MMP-1 promoter constructs followed by reporter assays. These studies identified an IL-1beta-responsive region of the human MMP-1 promoter that contains a consensus CCAAT enhancer-binding protein (C/EBP) binding site. Deletion of this site reduced overall transcriptional activity of the MMP-1 promoter, as well as decreased fold induction by IL-1beta. IL-1beta stimulation of chondrocytes increased binding of C/EBP-beta to the MMP-1 C/EBP site. Extracellular signal regulated kinase (ERK) pathway-dependent phosphorylation of C/EBP-beta on threonine 235 activates this transcription factor. Here we show that IL-1beta stimulation of chondrocytes induced phosphorylation of C/EBP-beta on threonine 235, and that the ERK pathway inhibitor PD98059 reduced this phosphorylation. We further show that PD98059 reduces IL-1beta-induced MMP-1 mRNA expression in chondrocytes. Moreover, inhibition of the ERK pathway by expression of dominant-negative forms of ERK1 and ERK2 impaired the ability of IL-1beta to transactivate the MMP-1 promoter. Our findings demonstrate a novel role for C/EBP-beta in IL-1beta-induced connective tissue disease and define a new nuclear target for the ERK pathway in MMP-1 gene activation.