Background/Aims: Dysregulation of T cell response is thought to play an important role in the immunopathogenesis of autoimmune hepatitis. However, no consensus has yet been reached regarding the implications of a distinct T cell subset in the pathogenesis of this progressive liver disease. Therefore, T-bet and GATA-3 expression was examined in patients with autoimmune hepatitis (AIH) and in healthy controls. Moreover, the profile of Th1 (IFN-γ) and Th2 (IL-4) cytokine gene expression was analyzed. Materials and Methods: Levels of mRNA transcripts were measured in peripheral blood mononuclear cells (PBMCs) using a two-step reverse transcription quantitative real-time polymerase chain reaction with SYBR Green. Results: T-bet and IFN-γ mRNA expression was significantly higher in AIH patients compared to healthy controls (p<0.05), whereas no differences were observed for either GATA-3 or IL-4 mRNA expression (p>0.05). Conclusion: Alterations in the Th1/Th2 cell balance may be responsible for both disease progression and the resulting complications.

Background: Autoimmune hepatitis (AIH) is an inflammatory liver disorder that commonly affects women. The T cells and one of their major products, IFN-γ, are critically involved in the pathogenesis of AIH. Therefore, targeting of IFN-γ can probably be therapeutically useful while avoiding the long-term side effects of conventional immunosuppressive therapy. RNA interference, provides an ideal way to achieve this purpose. Thus, the aim of this study was to investigate the effect of IFN-γ-siRNA on IFN-γ expression in human peripheral blood mononuclear cells of patients with AIH. Methods: In order to evaluate the anti-cytokine therapy with IFN-γ-siRNA, the PBMCs of AIH patients were cultured and transfected with IFN-γ-siRNA. After validation of transfection efficiency, the effects of gene silencing were tested with quantitative real-time polymerase chain reaction and intracellular flow cytometry. Results:The efficiently transfected cells, with the targeted IFN-γ-siRNA, without affecting cell viability showed a strong gene knockdown. The IFN-γ gene expression was significantly decreased in transfected cells (P < 0.05). Moreover, flow cytometric analysis confirmed the decrease of the intracellular IFN-γ protein level after siRNA transfection. Conclusions: Collectively, the results of the present study suggested that modifying the cytokine profile without inducing apoptosis using siRNA-based technology could be a promising tool for therapeutic intervention in T cells-dependent inflammatory diseases like AIH.