Elevated levels of nitrate in rheumatoid arthritis

Abstract

Nitric oxide (NO) is a free radical that plays important roles in many physiological and pathological processes. Evidence suggests that NO participates in the pathogenesis of inflammatory reactions in many autoimmune and inflammatory diseases such as rheumatoid arthritis (RA). The purpose of this study was to evaluate serum concentrations of NO in patients with RA and to determine whether they correlate with clinical and laboratory parameters of RA disease activity. Twenty-seven RA patients were recruited for the study and compared with 20 healthy subjects. Serum NO concentrations were measured indirectly in terms of nitrate using colorimetric assay. Disease activity was determined by laboratory and clinical findings. Mean serum concentrations of nitrate were significantly higher than those of healthy controls (P < 0.05). Among the disease activity parameters, C-reactive protein, number of swollen and tender joints, Ritchie articular index, and disease activity scores correlated significantly with serum NO levels. Our results suggest that these levels can serve as a reliable parameter of disease activity in patients with RA. Further knowledge about the precise role of NO may lead to better understanding of the pathogenesis of RA. Furthermore, modulation of NO synthesis may represent a new approach to the treatment of inflammatory and autoimmune conditions.

Nitric oxide, chronic inflammation and autoimmunity

“…A number of cells within the joint, including endothelial cells of synovial capillaries, mesenchymal cells, neutrophils, fibroblasts, lymphocytes, mast cells and macrophages are able to generate substantial quantities of NO [5]. Some investigators found a significant correlation between serum nitrate concentrations and number of tender joints, number of swollen joints, Ritchie articular index and DAS score [19]. Others also found increased NO production, without any correlation between RA activity and nitrate levels [20].…”

LC–DAD–ESI-MS analysis of nitric oxide inhibitory fractions of tenggek burung (Melicope ptelefolia Champ. ex Benth.)

“…It has been reported that excess production of NO by macrophages is thought to promote a number of chronic inflammatory diseases such as arthritis, hepatitis, septic and haemorrhagic shock, and certain autoimmune disorders (Boveris et al, 2002;Koulentaki et al, 2004;McDonald et al, 2003;Onur et al, 2001;Zehntner et al, 2004). Increased expression of iNOS Solvent-solvent fractionation of the methanolic extract of the popular Malay traditional vegetable ''tenggek burung'' (Melicope ptelefolia), followed by nitric oxide inhibition assay on RAW 264.7 cells revealed that the most active components reside mainly in hexane and dichloromethane fractions.…”

Nitric oxide and superoxide in rat mesangial cells: modulation by C-reactive protein

“…For example, in patients with rheumatoid arthritis, disease activity correlated with plasma CRP and nitrite levels [36]. CRP levels in the synovial fluid of patients with rheumatoid arthritis were elevated in parallel with the number of iNOS-positive mononuclear cells [37].…”