s-nitro-n-acetylpenicillamine and Arthritis--Rheumatoid

The aim of the present study was to investigate the effects of (i) the pro-inflammatory cytokines IL (interleukin)-1beta, TNF-alpha (tumour necrosis factor-alpha), IFN-gamma (interferon-gamma) and anti-inflammatory cytokines IL-4 and IL-13, and (ii) NO (nitric oxide) donors on HA (hyaluronic acid) production by synovial cells from patients with rheumatoid arthritis. Synovial cells obtained from five patients with rheumatoid arthritis were incubated for 24 h without or with IL-1beta, TNF-alpha, IFN-gamma, or with this mixture for 24 h plus IL-4 or IL-13 for the last 6 h. The same cells were also incubated for 3-24 h without or with SNP (sodium nitroprusside) or SNAP (S-nitroso-N-acetyl-DL-penicillamine). HA secretion was determined by an immunoenzymic assay based on HA-specific binding by proteoglycan isolated from bovine cartilage. IL-1beta, TNF-alpha and IFN-gamma alone or in combination stimulated HA synthesis, whereas IL-4 and IL-13 dose-dependently inhibited HA production induced by Th1 cytokines. HA production was significantly increased by the presence of 1 mM SNP after 6 and 12 h (maximal effect). HA production was significantly increased by the presence of 0.01 and 0.1 mM SNAP after 12 h of incubation, and cells treated with 1 mM SNAP showed a maximal HA production after 24 h of incubation. In conclusion, the present study provides data concerning the regulatory role of pro- and anti-inflammatory cytokines and NO donors on HA metabolism in rheumatoid synovial cells and may help in understanding the pathophysiology of rheumatoid arthritis.

Topics: Aged; Arthritis, Rheumatoid; Cells, Cultured; Cytokines; Dose-Response Relationship, Drug; Female; Humans; Hyaluronic Acid; Interferon-gamma; Interleukin-1; Interleukin-13; Interleukin-4; Male; Middle Aged; Nitric Oxide Donors; Nitroprusside; Penicillamine; Statistics, Nonparametric; Synovial Membrane; Tumor Necrosis Factor-alpha

Nitric oxide (NO) is elevated in the synovial fluids and sera of patients with rheumatoid arthritis (RA) and is thought to be an important proinflammatory mediator in the rheumatoid synovium. To test the hypothesis that NO might modulate the apoptosis-inducing signal pathway, we investigated the effects of NO on rheumatoid synovial-cell apoptosis induced by Fas ligation with anti-Fas antibody. Pretreatment of synovial cells with the NO donor S-nitro-N-acetylpenicillamine (SNAP) prevented the Fas-mediated induction of apoptosis. The activation of caspase-3 was required to mediate Fas-induced synovial cell apoptosis. The NO donor SNAP inhibited Fas-induced caspase-3 activation in rheumatoid synovial cells. However, NO did not interrupt Fas-induced caspase-8 cleavage or subsequent cytochrome c release into the cytosol in rheumatoid synovial cells. These data indicate that NO prevents apoptosis in rheumatoid synovial cells by directly inhibiting caspase-3 activation. Thus, we propose that NO interferes with cell death signal transduction and may contribute to rheumatoid synovial cell proliferation by inhibiting induction of apoptosis.

Topics: Apoptosis; Arthritis, Rheumatoid; Caspase 3; Caspase 8; Caspase 9; Caspase Inhibitors; Caspases; Cell Culture Techniques; Enzyme Activation; fas Receptor; Humans; Nitric Oxide; Nitric Oxide Donors; Penicillamine; Signal Transduction; Synovial Membrane

Prostaglandins formed by cyclooxygenase (COX) enzymes are important mediators of inflammation. The contribution of inducible COX-2 in the rheumatoid synovium is well documented. In this study, we evaluated the contribution of nitric oxide (NO) to COX-2 expression in rheumatoid synovial cells. Exposure of rheumatoid synovial cells to a NO donor, SNAP, induced COX-2 protein expression in a dose-dependent manner. RT-PCR analysis also demonstrated that COX-2 mRNA was induced in SNAP-treated synovial cells. Dexamethasone at therapeutic concentrations markedly inhibited this NO-mediated COX-2 expression in synovial cells. In contrast to its effect on COX-2 expression, SNAP did not affect the constitutive expression of COX-1 in rheumatoid synovial cells. Our findings suggest that NO is an important modulator of COX-2 expression and that glucocorticoids exert their anti-inflammatory action in rheumatoid synovium, at least in part, by suppression of COX-2 induction.

Topics: Arthritis, Rheumatoid; Base Sequence; Cells, Cultured; Cyclooxygenase 2; DNA Primers; Enzyme Induction; Gene Expression; Humans; Isoenzymes; Membrane Proteins; Nitric Oxide; Nitric Oxide Donors; Osteoarthritis; Penicillamine; Prostaglandin-Endoperoxide Synthases; RNA, Messenger; Synovial Membrane