Concanavalin-A as a Model for Induction of Murine Autoimmune Hepatitis: Role of TNF-α and NF-κβ During The Acute Phase.

Abstract

Autoimmune hepatitis (AIH) is a heterogeneous immune-mediated chronic liver disease affecting children and adults. It is important to rely on a specific animal model to study the hepatic changes and to evaluate the roles played by pro-inflammatory cytokines such as tumor necrosis factor alpha "TNF-α" and transcription factors such as nuclear factor kappa-light-chain-enhancer of activated B cells "NF-κβ" in the pathogenesis and outcome of the disease. This will help to identify specific targets for treatment of AIH. This study aimed at evaluating Concanavalin-A (Con A) as a model for induction of AIH and assessing splenocytes' TNF-α and hepatocytes' NF-κβ levels at comparable durations after induction of hepatitis with Con A to evaluate the relationship between both factors. Materials and methods: A total of 130 outbreed CD1 mice were divided into group (1) which included 100 mice with induced AIH and group (2) included 30 normal mice as negative controls. Intra-peritoneal injection of Concanavalin-A was used to induce hepatitis. Hepatic injury was evaluated by the levels of liver enzymes, histopathological evidence for hepatic inflammatory infiltrate and/or apoptosis. Splenocytes and hepatocytes were cultured for assessment of TNF-α and NF-κβ levels, respectively. Results: Con A injection caused a significant elevation in ALT and AST levels, portal inflammatory infiltrate, remarkable hepatocytes degeneration and marked increase of TNF-α levels, particularly within 24 hours, but all returned to normal within 1 week. Administration of another dose of Con A resulted in sharp significant elevation of liver enzymes, inflammatory infiltrate and hepatocyte apoptosis after 24 hours and sustained till the end of the study. There was a significant increase in NF-κβ throughout most of the study duration following Con A injection as compared to that of normal mice. In conclusions, intra-peritoneal administration of Con A, particularly two doses, represents an efficient approach for induction of immune-mediated hepatitis. T-cells play a major role in AIH through release of TNF-α. Coincidently, hepatitis seems to be associated with elevation of NF-κβ to protect hepatocytes. Thus TNF-α and NF-κβ can represent targets for treatment of AIH either through inhibition or augmentation, respectively.