Elevated Expression of indoleamine 2,3-dioxygenase (IDO) and accumulation of kynurenic acid in the pathogenesis of STZ-induced diabetic cataract in Wistar rats.

Purpose: Glycated lens proteins are capable of producing reactive oxygen species (ROS), which, in turn, can oxidize tryptophan (Trp) into kynurenines. Indoleamine 2,3-dioxygenase (IDO), which is expressed in many tissues and which is inducible by interferon-gamma (IFN-gamma), is able to oxidize Trp into kynurenines. These kynurenines can modify lens proteins and, in fact, kynurenine adducts are markedly increased in lenses with age-related nuclear cataract.