Intrahepatic TH17/TReg Cells in Homeostasis and Disease—It’s All About the Balance

Both acute and chronic hepatic inflammation likely result from an imbalance in the T H 1/T H 2 cell response and can lead to liver fibrosis and end-stage liver disease. More recently, a novel CD4+ T helper cell subset was described, characterized by the production of IL-17 and IL-22. These T H 17 cells 50were predominantly implicated in host defense against infections and in autoimmune diseases. Interestingly, studies over the last 10 years revealed that the development of T H 17 cells favors pro-inflammatory responses in almost all tissues and there is a reciprocal relationship between T H 17 and T Reg cells. The balance between T H 17and T Reg cells is critical for immune reactions, especially in injured liver tissue and the return to immune homeostasis. The pathogenic contribution of T H 17 and T Reg cells in autoimmunity, acute infection, and chronic liver injury is diverse and varies among disease etiologies. Understanding the mechanisms underlying T H 17 cell development, recruitment, and maintenance, along with the suppression of T Reg cells, will inform the development of new therapeutic strategies in liver diseases. Active manipulation of the balance between pathogenic and regulatory processes in the liver may assist in the restoration of homeostasis, especially in hepatic inflammation.