Abstract:

MethodsCell viability insensitive to emodin on cultured human corneal fibroblasts was assessed using the MTT assay. Human corneal fibroblasts were randomly divided into three groups：the control group(group 0?h), the lipopolysaccharide(LPS) group and the emodin pretreatment group. Cells in the emodin pretreatment group were incubated with emodin for 30?min before being LPS challenged. Before and after 1,2,4 and 8?h treatment with LPS, expression of inhibitor of κBα（IκBα）was assayed by Western blot， and secretion of IL6 induced by LPS from cultured corneal fibroblasts was determined with enzymelinked immunosorbent assays(ELISA). Effects of emodin, an active component from the rhizome of Rheum palmatum, on expressions of IκBα and IL6 were also assessed in these cells. ResultsThe concentration of emodin used in this study was safe for cultured human corneal fibroblasts. Compared with the 0h group, expression of IκBα protein level was significantly decreased after being LPS challenged 18?h(P<0.01), the lowest expression of IκBα was observed at 4h after LPS challenged. Compared with cells in the 0h group, IκBα level was significantly decreased in each group after treated with LPS, and degeneration of IκBα induced by LPS was markedly inhibited by emodin（P<0.01）.　At the same time, the protein release of IL6 in corneal fibroblasts was significantly increased at each point after being challenged with LPS, which was significantly inhibited by pretreatment with emodin（P<0.01）. ConclusionThese results suggest that LPS takes part in the degeneration of IκBα in cultured human corneal fibroblasts in vitro, and emodin can partly inhibit this degeneration. By inhibiting IκBα degeneration, emodin may suppress LPSinduced cytokine release from these cells, which is one of the signal transduction mechanisms of emodin to prevent the occurrence of inflammation.

Key words: Emodin, Interleukin6, Cornea 核因子