Supplementation of tryptophan metabolite ITE could down-regulate ERK and NFκB dependent inflammation of microglia through AhR activation and thus alleviate retinal injury under IR in mice (Fig. 8), raising the possibility that intrinsic regulation of AhR signaling by supplementation of tryptophan metabolites can serve as a novel avenue for the treatment of glaucoma. The gene discussed is NFKB1; the disease is glaucoma.