Increased expression of
inducible nitric oxide synthase (NOS-2) in inflammatory diseases like
uveitis suggests that it contributes to the observed pathological state. The aim of this study was to evaluate corneal expression of NOS-2 and corneal
protein nitration in a rat model of
uveitis. A single injection of intravitreal
lipopolysaccharide was used to induce
uveitis. Corneal
proteins were separated by
sodium dodecyl sulfate-
polyacrylamide gel electrophoresis and visualized by
Coomassie blue staining. Expression of NOS-2 and
nitrotyrosine (
NO(2)Tyr) formation were determined via immunohistochemistry and Western blot analysis. Total
nitrate/
nitrite levels in the vitreous were measured by spectral analysis via the
Griess reagent. Immunohistochemical analysis revealed increased corneal NOS-2 and
NO(2)Tyr immunoreactivity in rats with
uveitis compared with controls. NOS-2 and
NO(2)Tyr immunoreactivity was observed in and around basal cells in the corneal epithelium. Western blot analysis of corneal lysates showed multiple nitrated
protein bands in uveitic rats. Spectrophotometric measurement of total
nitrate/
nitrite levels in the vitreous affirmed significantly increased levels of
nitric oxide generation in
uveitis (126 +/-2.63 microM/mg
protein) compared with controls (65 +/-6.57 microM/mg
protein). The presented data suggests that extensive formation of
protein nitration and
reactive nitrogen species in the cornea contributes to tissue destruction in
uveitis. Hence, selective inhibition of NOS-2 may prevent long-term complications and lead to an improvement in the management of
uveitis.