Inhibitory effect of a novel peptide, H-RN, on keratitis induced by LPS or poly(I: C) in vitro and in vivo via suppressing NF-ΚB and MAPK activation

Abstract

Background: Keratitis is a common cause of blindness. Current anti-inflammatory drugs used in keratitis have profound side effects. Small peptides derived from endogenous proteins potentially display both desired efficiency and safety. We identified an 11-amino-acid peptide, H-RN, from hepatocyte growth factor (HGF), an endogenous protein with anti-inflammatory properties. We evaluated the effects of H-RN in keratitis in vitro and in vivo. Methods: In vitro, corneal fibroblasts were stimulated with LPS or poly(I:C), surrogates for bacteria and viruses. Inflammatory cytokines, intercellular cell adhesion molecule-1 (ICAM-1), translocation of NF-ΚB p65, activation of IΚBα, NF-ΚB, and MAPKs were detected. In vivo, keratitis in rats was induced by LPS. Clinical, histological observation, and quantification of cytokines in the cornea were conducted. H-RN safety was measured by cell viability, clinical, histological, and microstructural observations. Results: H-RN inhibited IL-6, monocyte chemotactic protein-1(MCP-1), Interferon- γ(IFN-γ), and ICAM-1 expression triggered by LPS or poly(I:C), alleviated the clinical manifestation and reduced the clinical score in keratitis in vivo. The histological disorder and proinflammatory cytokines of the cornea were also reduced. The translocation of NF-ΚB and phosphorylation of IΚBα, NF-ΚB, p38, JNK, and ERK were significantly inhibited by H-RN. No sign of toxicity was observed. Conclusions: H-RN effectively attenuated keratitis in vivo and in vitro induced by LPS or poly(I:C) through blocking NF-ΚB and MAPK signaling pathways. It may be a promising and safe agent in treating keratitis.