Autoimmune Hepatitis and Drug-Induced Liver Injury in Japan

Autoimmune hepatitis (AIH) is the most common liver disease caused by autoimmunity. In Japan, the number of patients with AIH has been increasing in recent years. AIH develops as a result of the loss of immune tolerance to autoantigens in the liver. Drug-induced liver injury (DILI) is an extremely important cause of liver injury in clinical practice and should always be kept in mind in the differential diagnosis. Recently, DILI caused by immune checkpoint inhibitors has been attracting attention. For the diagnosis of DILI, it is important to carefully exclude other possible causes of liver injury and obtain a detailed history of medications and the timing of their use. On the other hand, drug-induced AIH, like hepatitis, also exists and is clinically important because it is often difficult to differentiate from idiopathic AIH. A solid understanding of the pathogenesis of both AIH and DILI is essential for clinicians. This article provides an overview of AIH and DILI in Japan, including the latest findings.