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

OBJECTIVE: 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. METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

The role of NF-kappaB activation in lipopolysaccharide induced keratitis in rats.

BACKGROUND: Nuclear factor-kappa B (NF-kappaB) is elevated in regulating transcription of many cytokines and inflammatory mediators. The purpose of this study was to investigate the activation and the significance NF-kappaB in lipopolysaccharide (LPS) induced keratitis. METHODS: LPS induced keratitis model was based on Wistar rats. At 0.5, 1, 3, 6, 12, 24 or 72 hours after LPS treatment, the rat corneas were observed with a slit lamp microscope, then the rats were sacrificed and their corneas were excised for routine histological analysis. The expression of NF-kappaB was detected with immunohistochemical staining. The change of tumour necrosis factors-alpha (TNF-alpha) mRNA expression was identified by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Histological findings demonstrated that LPS treated corneas showed significant changes in corneal structure. Corneal edema, pronounced inflammatory cells infiltration and inordinate collagen fibres were observed. Immunohistochemical results showed that the expression of NF-kappaB and its activation obviously increased after LPS treatment compared with the normal group and control group. Positive cells could be observed at 0.5 hour and peak expression of NF-kappaB was observed between 3 hours and 12 hours after infection, but returned to or approached normal level by 72 hours. RT-PCR showed that the level of TNF-alpha mRNA began to increase 0.5 hour after LPS treatment, peaked at 6 hours and then subsided by 72 hours. NF-kappaB had a positive correlation with the expression of TNF-alpha mRNA (r = 0.964, P < 0.01), both NF-kappaB and TNF-alpha had a strong positive correlation with the degree of inflammatory response in LPS treated corneas (r = 0.929, P < 0.01; r = 0.587, P < 0.05, respectively). CONCLUSIONS: The activation of NF-kappaB was increased in LPS treated corneas and was elevated in LPS induced keratitis by promoting overexpression of TNF-alpha mRNA. NF-kappaB may play an important role in the pathogenesis of LPS-associated keratitis in rats.