Interferon-gamma- and perforin-mediated immune responses for resistance against Toxoplasma gondii in the brain

Expert Rev Mol Med. 2011 Oct 4:13:e31. doi: 10.1017/S1462399411002018.

Abstract

Toxoplasma gondii is an obligate intracellular protozoan parasite that causes various diseases, including lymphadenitis, congenital infection of fetuses and life-threatening toxoplasmic encephalitis in immunocompromised individuals. Interferon-gamma (IFN-γ)-mediated immune responses are essential for controlling tachyzoite proliferation during both acute acquired infection and reactivation of infection in the brain. Both CD4+ and CD8+ T cells produce this cytokine in response to infection, although the latter has more potent protective activity. IFN-γ can activate microglia, astrocytes and macrophages, and these activated cells control the proliferation of tachyzoites using different molecules, depending on cell type and host species. IFN-γ also has a crucial role in the recruitment of T cells into the brain after infection by inducing expression of the adhesion molecule VCAM-1 on cerebrovascular endothelial cells, and chemokines such as CXCL9, CXCL10 and CCL5. A recent study showed that CD8+ T cells are able to remove T. gondii cysts, which represent the stage of the parasite in chronic infection, from the brain through their perforin-mediated activity. Thus, the resistance to cerebral infection with T. gondii requires a coordinated network using both IFN-γ- and perforin-mediated immune responses. Elucidating how these two protective mechanisms function and collaborate in the brain against T. gondii will be crucial in developing a new method to prevent and eradicate this parasitic infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • Brain / metabolism
  • Brain / parasitology*
  • CD8-Positive T-Lymphocytes / immunology
  • CD8-Positive T-Lymphocytes / metabolism
  • Disease Resistance / immunology
  • Humans
  • Immunity, Innate*
  • Interferon-gamma / immunology
  • Interferon-gamma / metabolism*
  • Perforin / immunology
  • Perforin / metabolism*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • Toxoplasma / physiology*
  • Toxoplasmosis, Cerebral / immunology*
  • Toxoplasmosis, Cerebral / parasitology
  • Vascular Cell Adhesion Molecule-1 / metabolism

Substances

  • Vascular Cell Adhesion Molecule-1
  • Perforin
  • Interferon-gamma