Cellular mechanism for severe viral hepatitis identified

It is known that activated immune cells of patients with viral hepatitis destroy hepatocyte, but its regulatory mechanism has not yet been described.

Regulatory T cells inhibit activation of other immune cells and thus are important for homeostasis of the immune system. However, recent studies contradictorily show that immune inhibitory functions of regulatory T cells weaken in inflammatory conditions and the cells secrete inflammatory cytokines in response. Meanwhile, such a phenomenon was not observed in viral hepatitis including types A, B and C.

The team focused on changes in regulatory T cells in patients with viral hepatitis and discovered that regulatory T cells undergo inflammatory changes to secrete inflammatory cytokines (protein secreted by immune cells) called TNF. They also proved regulatory T cells that secrete TNF contribute to the progression of viral hepatitis.

The team confirmed that regulatory T cells of acute hepatitis A patients have reduced immune-inhibitory functions. Instead, their regulatory T cells secrete TNF. Through this research, the team identified a molecular mechanism for changes in regulatory T cells and identified the transcription factor regulating the process. Furthermore, the team found similar changes to be also present in hepatitis B and C patients.

A KAIST immunology research team led by Professors Eui-Cheol Shin and Min Kyung Jung at the Graduate School of Medical Science & Engineering conducted this translational research with teams from Chungnam National University and Yonsei University to identify the mechanism in humans, instead of using animal models. The research was described in Gastroenterology last December.

Professor Shin said, "This is the first research on regulatory T cells that contributes to hepatocyte damage in viral hepatitis." He continued, "It is significant for identifying the cells and the molecules that can be used as effective treatment targets for viral hepatitis in the future. This research was funded by the Samsung Science and Technology Foundation.