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

Nitric oxide (NO) is produced in increased amounts in inflammatory conditions and may cause tissue injury by reacting with superoxide to yield peroxynitrite, a powerful toxin. Superoxide dismutase (SOD) scavenges superoxide and inhibits the formation of peroxynitrite, thereby suppressing the resulting injury and regulating the bioavailability of NO. We conducted a study to assess serum NO and SOD in patients with Behçet's disease (BD) and correlate their levels with disease activity.

Serum NO concentrations and SOD activities were determined in 25 BD patients (mean age: 36 years; male/female: 13/12) and in 15 healthy controls. BD patients were allocated into two groups according to disease activity (active/inactive: 11/14).

In patients with active disease, NO levels were found to be significantly elevated, while SOD activities were comparable to the control group. Conversely, patients with inactive disease exhibited markedly high SOD activities and normal NO levels. Moreover, there was a positive correlation between SOD activity and NO levels in patients with inactive BD (r = 0.562, p < 0.05).

We propose that NO-associated injury of tissues, particularly the endothelium, may be important in the etiopathogenesis of vasculitis in BD, and SOD may play a protective role against inflammation.