Signaling of immune system cells by glycosylphosphatidylinositol (GPI) anchor and related structures derived from parasitic protozoa

Glycosylphosphatidylinositol (GPI) anchor and glycoinositolphospholipid (GIPL) are abundant molecules present in the membrane of parasitic protozoa that are common etiologic agents of medical and veterinary diseases. Recent studies have documented the immunostimulatory/regulatory activity of protozoan-derived GPI-anchors and related structures. Among the bioactivity displayed by the protozoan-derived GPI-anchor is the ability to elicit the synthesis of pro-inflammatory cytokines as well as nitric oxide by host macrophages. In contrast, at high concentrations GIPL and lipophosphoglycan (LPG) derived from protozoan parasites suppress several functions of the host immune system. Additionally, the protozoan-derived GPI-anchor and GIPL have been shown to serve as targets for both specific B and NK-T lymphocyte responses. This information extends our knowledge about parasite molecules that stimulate/regulate the host immune system during protozoan infection. The identification of receptor(s) and signaling pathways triggered by these GPI-related glycolipids may provide new insights for the development of therapies that inhibit detrimental immune responses or potentiate beneficial immune responses observed during infection with protozoan parasites.