Hepatic expression of tumor necrosis factor-α and evaluation of MAPK-p38 and NFκB signaling pathways in autoimmune hepatitis.

OBJECTIVES:Autoimmune hepatitis (AIH) is a necroinflammatory disease that occurs when genetically susceptible individuals are exposed to an environmental trigger. It is a rare disease, and its epidemiological aspects are nearly unknown in Northeast Brazil. In the literature, the activation of components of the inflammatory cascade pathways, including interleukins such as TNF-α and signaling factors like MAPK-p38 and NFκB, in the pathogenesis of AIH is well described in animal models. This study evaluated, for the first time, the immunostaining of TNF-α, MAPK-p38, and NFκB in immunohistochemical analysis of liver biopsies from AIH patients. The activation of the MAPK-p38 pathway was also studied through immunoassay analysis in the peripheral blood of AIH patients. METHODS AND RESULTS:Data from medical records of 25 AIH patients were analyzed. Histological and immunohistochemical analysis of liver tissue obtained from biopsies was performed to detect NFκB, MAPK-p38, and TNF-α. Immunoassay analysis of the MAPK-p38 pathway was performed in peripheral blood from 18 AIH patients and 8 healthy volunteers. Medical record analysis showed an average age of 33.3 years, with a female predominance in a ratio of 7.3:1. Concomitance with other autoimmune diseases was observed in 36 % of patients, with thyroid disorders being the most prominent among them, and an 8 % indication for liver transplantation. In the evaluation of autoantibodies, ANA was detected in 52 %, followed by SMA at 20 %, and Anti-LKM-1 at 16 %. Liver biopsy findings were like the global literature, with interface hepatitis and lymphoplasmacytic infiltration observed. Immunohistochemical analysis showed immunostaining for NFκB, MAPK-p38, and TNF-α, corroborating the inflammatory and immunological characteristics of the disease. Immunoassay analysis in peripheral blood confirmed the activation of the MAPK-p38 signaling pathway, with a statistically significant difference between AIH patients and healthy controls. CONCLUSIONS:The epidemiological and histological findings of AIH in this study in Northeast Brazil were like global population data. Immunohistochemical analysis of liver tissue and immunoassay analysis in peripheral blood confirmed the activation of TNF-α and the NFκB and MAPK-p38 signaling pathways in AIH patients.