The expression of nuclear factor-kappa B in lipopolysaccharide-induced keratitis of rats and the effect of pyrrolidine dithiocarbamate on its expression

Abstract

To investigate the expression of nuclear factor-kappa B (NF-kappaB) and cytokines in lipopolysaccharide (LPS)-induced keratitis of rats, and the effect of pyrrolidine dithiocarbamate (PDTC) on its expression. A LPS-induced keratitis model was established in Wistar rats. Thirty minutes before LPS exposure, PDTC and normal saline were injected into subconjunctival tissues separately. At 0.5, 1.0, 3.0, 6.0, 12.0, 24.0 and 72.0 h after LPS exposure, the rats were examined with slit-lamp microscope. Then they were sacrificed and the corneas were excised for routine histological analysis. Immunohistochemical staining with an antibody against activated NF-kappaB was performed to detect the expression of NF-kappaB. The change of TNF-alpha mRNA expression was identified by reverse transcriptase polymerase chain reaction (RT-PCR). Histology findings demonstrated that corneas exposed to LPS showed significant changes in corneal structure, edema and pronounced inflammatory cells infiltration were observed. Both symptoms and damages of the cornea were lesser in the rats of PDTC group than that of the control keratitis group. Compared with PDTC group, the activation of NF-kappaB and the expression of TNF-alpha mRNA were significantly upregulated after LPS challenge 0.5 - 24.0 h (P < 0.01), separately; peak expression of NF-kappaB and TNF-alpha mRNA were observed at 3.0 - 12.0 h after LPS exposure. The expression of NF-kappaB and TNF-alpha mRNA induced by NF-kappaB plays an important role in the pathogenesis of keratitis. The inhibitor of NF-kappaB, PDTC, can relieve the cornea from damages produced by keratitis.