Cyclosporine Ameliorates Silica-Induced Autoimmune Hepatitis in Rat Model by Altering the Expression of Toll-Like Receptor-4, Interleukin-2, and Tumor Necrosis Factor-α.

Abstract

Autoimmune hepatitis (AIH) is an inflammatory liver disease that is characterized histologically by interface hepatitis, biochemically by elevated transaminase levels, and serologically by the presence of autoantibodies. Toll-like receptor (TLR)-4 is a TLR family member that, upon activation in hepatocytes, initiates a cascade of events. Interleukin-2 (IL-2) and tumour necrosis factor α (TNF-α) are potent inflammatory cytokines secreted in AIH, playing an important role in the early development of inflammation and hepatocyte damage. This study examined the role of cyclosporine in AIH and illustrated its actions on altered hepatic function in the silica-induced AIH model. AIH was induced in Wistar rats using sodium silicate. The rats were divided into four groups: the control group, silica-AIH group, cyclosporine-treated group, and prevention group. TLR-4 and IL-2 mRNA expressions in liver tissues were tested by RTPCR. AIH was associated with up-regulation of liver enzymes, IL-2 and TLR-4 gene expression, while cyclosporine significantly down-regulated the expression of both. The relative quantity of TLR-4 mRNA was 1±0, 13.57±1.91, 4±0.38, and 2±0 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Also, the relative quantity of IL-2 mRNA was 1±0, 14.79±1.42, 7.07±0.96, and 3.4±0.55 in control, AIH, cyclosporine, and prevention groups, respectively (p<0.001). Additionally, immunohistochemical staining for TNF-α in liver sections was increased in the silica-AIH group but was found to decrease in the cyclosporine-treated and prevention groups. This study advocates the therapeutic role of cyclosporine in treating immune-mediated hepatic diseases. Cyclosporine improves histological alterations in the liver and inhibits the production of proinflammatory cytokines.