Interferon-γ and nitric oxide production during Behçet uveitis: immunomodulatory effect of interleukin-10

Uveitis is one of the major manifestations of Behçet Disease, a systemic inflammatory vasculitis. Our aim is to investigate in vivo and in vitro production of interferon (IFN)-γ and nitric oxide (NO) during Behçet uveitis (BU). Moreover, we evaluated the implication of IFN-γ and interleukin (IL)-10 in the regulation of NO production in vitro. Cytokines' concentrations were measured by ELISA, and NO levels were assessed by modified Griess's method. Our results showed that patients with active disease had significant elevation of IFN-γ and NO concentrations in both plasma and peripheral blood mononuclear cell culture supernatants compared with controls (P<0.01) or to patients with inactive disease (P<0.05). Further, IFN-γ induced significantly higher production of NO in cell culture supernatants, whereas IL-10 significantly reduced it (P<0.05). In conclusion, the elevated levels of IFN-γ in vivo and in vitro in patients with BU reflect the implication of this cytokine in the disease physiopathology. These results suggest that IFN-γ, through the induction of NO synthase 2 and the production of NO, is implicated in the genesis of the inflammatory process during active BU; whereas IL-10 seems to have protective properties.