The role of hepatic immune regulation in systemic immunity to viral infection

Med Microbiol Immunol. 2015 Feb;204(1):21-7. doi: 10.1007/s00430-014-0371-0. Epub 2014 Dec 19.

Abstract

The liver has particular immune functions attributed by its unique microenvironment and its liver-resident cell populations. During autoimmunity and viral hepatitis, the liver serves as target for effector responses of immune cells. However, skewing of effector T cell functions through tolerogenic liver-resident antigen-presenting cells and through the immune regulatory hepatic microenvironment. Importantly, the liver also participates in shaping systemic antigen-specific immunity. Local antigen-presenting cell populations, in particular liver sinusoidal endothelial cells (LSECs), cross-present soluble, circulating or hepatocyte-derived antigens to naïve CD8 T cells. Upon priming by cross-presenting LSECs, naïve CD8 T cells develop into a unique population of antigen-experienced memory-like T cell population that can be reactivated in an inflammatory context to protect against infection with viruses or bacteria. Furthermore, upon prolonged inflammatory TNF-dependent signaling, the induction of intrahepatic myeloid cell aggregates for T cell population expansion (iMATEs) is observed in liver tissue. iMATEs are formed by inflammatory monocytes developing into dendritic cells and function to attract recently activated CD8 T cells. Those CD8 T cells located within the cocoon-like iMATE structure show strong proliferation initiated by co-stimulatory signaling. Locally expanded CD8 T cells are key to control acute and chronic viral infections. The mechanistic understanding of local hepatic T cell priming and local expansion of effector CD8 T cells will help to develop novel therapeutic vaccination strategies.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adaptive Immunity*
  • Bacteria / immunology
  • Bacterial Infections / immunology*
  • Humans
  • Immunity, Innate*
  • Liver / immunology*
  • Virus Diseases / immunology*
  • Viruses / immunology