Novel therapeutic targets in autoimmune hepatitis

Abstract

Autoimmune hepatitis (AIH) is an orphan disease characterized by an autoimmune attack against hepatocytes. The exact sequence of events that leads to a breach of tolerance is incompletely understood. Current hypotheses suggest that environmental agents such as toxins or infectious agents like viruses cause a tissue damage that initiates autoimmunity in genetically susceptible individuals. The growing knowledge of the multi-facetted immune dysregulation, which involves Th1/Th17 polarization and the suspected inability of regulatory T cells to revert autoimmunity in the otherwise tolerogenic milieu of the liver, offers multiple new therapeutic approaches and targets. Standard of care (SOC) is treatment with corticosteroids with or without azathioprine, which is sufficient to induce remission in the majority of patients. However, it rarely cures AIH or restores intrahepatic immune tolerance. Hence, life-long therapy is required in the majority of patients. In addition, several studies suggest a weakening of immune regulation mediated by intrahepatic T cells under current therapies. Furthermore, second line therapies for non-responders, intolerant or otherwise difficult to treat patients are urgently needed as this is relevant for at least one fifth of all patients with inefficacy or intolerance to SOC. Current second line therapies are mainly based on single center retrospective experiences and none of them have been approved by regulatory authorities for AIH, yet. This article highlights new therapeutic approaches based on our growing knowledge on the pathophysiology of AIH. It focuses on cell-based therapies that strengthen or restore immune tolerance. An additional focus lies on new therapeutic agents showing promising results in non-hepatic autoimmune diseases that have a potential for treating AIH. The dynamics in the whole field of innovative therapies for non-hepatic autoimmune diseases will hopefully improve the therapeutic armamentarium for AIH patients in the future.