Use of immunosuppression in non-transplant hepatology

Human liver possesses a persistent and tightly regulated immune response. Maintaining this homeostatic state is the key to prevent pathological processes, as a failure in clearing dangerous stimuli, is associated with tissue damage. A dysregulation of the liver immune homeostasis is involved in many disease processes and the use of the immunosuppression aims to control the inflammatory response, where the physiologic mechanisms failed. The use of steroids which targets broadly the inflammatory cascade and the immune system activation have been extensively employed in both acute and chronic liver diseases. They currently are the backbone of the treatment of autoimmune diseases such as autoimmune hepatitis or IgG4 sclerosing cholangitis. The steroid use in acute liver injury, especially alcohol mediated and drug induced liver injury (DILI), have been debated, despite the biological rationale. The immunosuppression molecules currently employed in liver diseases target the immune system broadly, causing multiple side effects either intrinsic in the mechanisms of the drug or secondary to off-target toxicity. The future of immunosuppressant treatment is moving towards more selective strategies, targeting disease specific pathways. This review aims to explore the rationale of use of immunosuppression in non-transplant hepatology. A broad summary of the immune biology of liver immune mediated diseases will be provided to the readers in order to highlight the potential therapeutic targets. An extensive description of the molecules employed in liver diseases will follow and the clinical evidences in AIH, IgG4 related cholangitis, alcoholic hepatitis and DILI will be reviewed.