Increased nitric oxide production in patients with systemic sclerosis

Nitric oxide (NO, nitrogen monoxide) is a messenger molecule whose synthesi s can be induced by proinflammatory cytokines, Increased production of NO h as been reported in various inflammatory and autoimmune diseases. We studie d serum nitrite and citrulline as surrogate markers for NO production in pa tients with systemic sclerosis (SSc) and looked for correlation with extent of disease, disease duration, age, and systemic involvement. Thirty-four p atients were studied against 20 controls. The nitrite levels were significa ntly higher in the disease group (1588.4 +/- 998.2 nmol/ml compared to 327. 8 +/- 137.7 nmol/ml; P < 0.001), The citrulline levels of the disease group were also significantly higher (5490.1 +/- 2518.3 nmol/ml compared to 3264 .5 +/- 2509.7 nmol/ml in the controls; P = 0.005). There was no significant difference among limited and diffuse subgroups. There was no significant d ifference in patients with or without arthritis or interstitial lung diseas e or with other systemic involvement. On multivariate analysis there was a trend toward a rising level of nitrite with worsening lung functions (P = 0 .07). Hence, there is evidence of increased NO production in patients with SSc, There is no difference between NO levels in disease subgroups or those with systemic involvement. (C) 2000 Academic Press.