Interactions of nitric oxide and superoxide dismutase in Behcet's disease

Objective Nitric oxide (NO) is produced in increased amounts in inflammator y conditions and may cause tissue injury by reacting with superoxide to yie ld peroxynitrite, a powerful toxin. Superoxide dismutase (SOD) scavenges su peroxide and inhibits the formation of peroxy-nitrite, thereby suppressing the resulting injury and regulating the bioavailability of NO. We conducted a study to assess serum NO and SOD in patients with Behcet's disease (BD) and correlate their levels with disease activity. Methods Serum NO concentrations and SOD activities were determined in 25 BD patients (mean age: 36 years; male/female: 13/12) and in 15 healthy contro ls. BD patients were allocated into two groups according to disease activit y (active/inactive: 11/14). Results In patients with active disease, NO levels were found to be signifi cantly elevated, while SOD activities were comparable to the control group. Conversely, patients with inactive disease exhibited markedly high SOD act ivities and normal NO levels. Moreover there was a positive correlation bet ween SOD activity and NO levels in patients with inactive BD (r = 0.562, p < 0.05). Conclusion We propose that NO-associated injury of tissues, particularly th e endothelium, may be important in the etiopathogenesis of vasculitis in BD , and SOD may play a protective role against inflammation.