The Protective Effect of Resveratrol on Concanavalin-A-Induced Acute Hepatic Injury in Mice

Abstract

Pharmacologic Relevance. Resveratrol, an antioxidant derived from grapes, has been reported to modulate the inflammatory process. In this study, we investigated the effects of resveratrol and its mechanism of protection on concanavalin-A- (ConA-) induced liver injury in mice. Materials and Methods. Acute autoimmune hepatitis was induced by ConA (20 mg/kg) in Balb/C mice; mice were treated with resveratrol (10, 20, and 30 mg/kg) daily by oral gavage for fourteen days prior to a single intravenous injection of ConA. Eight hours after injection, histologic grading, proinflammatory cytokine levels, and hedgehog pathway activity were determined. Results. After ConA injection, the cytokines IL-2, IL-6, and TNF-α were increased, and Sonic hedgehog (Shh), Glioblastoma- (Gli-) 1, and Patched (Ptc) levels significantly increased. Pretreatment with resveratrol ameliorated the pathologic effects of ConA-induced autoimmune hepatitis and significantly inhibited IL-2, IL-6, TNF-α, Shh, Gli-1, and Ptc. The effects of resveratrol on the hedgehog pathway were studied by western blotting and immunohistochemistry. Resveratrol decreased Shh expression, possibly by inhibiting Shh expression in order to reduce Gli-1 and Ptc expression. Conclusion. Resveratrol protects against ConA-induced autoimmune hepatitis by decreasing cytokines expression in mice. The decreases seen in Gli-1 and Ptc may correlate with the amelioration of hedgehog pathway activity.

Figure 1

Resveratrol pretreatment attenuates ConA-induced autoimmune hepatitis. Liver histopathology in ConA-induced liver injury. Liver samples were taken from mice treated with ConA (20 mg/kg) and mice treated with ConA and resveratrol (10, 20, and 30 mg/kg, resp., daily oral administration × 14 days). Sections were stained with H&E. (a) Saline group; (b) resveratrol-alone group; (c) ConA group: liver section from a mouse from the ConA-treated group showing extensive liver focal necrosis, portal infiltration, and interface hepatitis. H&E, magnification ×100; ((d)–(f)) ConA + Res (10 mg/kg); ConA + Res (20 mg/kg); ConA + Res (30 mg/kg): liver section from a mouse treated with ConA and resveratrol, and liver histology shows only a minimal grade of cellular infiltration and hepatocyte damage. H&E, magnification ×100. (g) The necrotic areas were analyzed with Image-pro Plus 6.0, indicating statistical significance among groups.

Figure 2

The western blot analysis of IL-2, IL-6, TNF-α, Shh, Gli-1, and Ptc after ConA injection in mice and the effects of low (10 mg/kg), medium (20 mg/kg), and high (30 mg/kg) dose resveratrol pretreatment groups at the same time.

Figure 3

Immunohistochemistry used to detect the expression level of Gli-1 and Ptc 8 hours in all five groups (saline group, ConA model group; ConA + 10 mg/kg Res; ConA + 20 mg/kg Res; ConA + 30 mg/kg Res). Gli-1 and Ptc showed a strong immunoreactivity in ConA sections, but it was weak after Res application in different dose groups.

Figure 4

Immunohistochemistry used to detect the expression level of CD4 and F4/80 8 hours in all five groups (saline group, ConA model group; ConA + 10 mg/kg Res; ConA + 20 mg/kg Res; ConA + 30 mg/kg Res). CD4 and F4/80 showed strong immunoreactivity in ConA sections, but it was weak after Res application in different dose groups.