Table 1. Role of IDO/TDO in liver diseases.

Liver diseases	Roles of IDO/TDO
Viral hepatitis	Inhibition of HBV replication; Exacerbation of liver injury
Autoimmune liver diseases	Protection against immune overactivation
Non-alcoholic fatty liver disease	Protection against liver inflammation; Promotion of liver steatosis
Liver fibrosis and cirrhosis	Aggravation or attenuation of liver lesions
Liver tumors	Promotion of tumor progression
Hepatectomy and liver transplantation	Suppression of liver regeneration; Protection against immune rejection