Sphingolipids in infectious diseases.

Sphingolipids are ubiquitous constituents of membrane lipids in eukaryotes. Sphingolipid metabolites modulate various cellular events including proliferation, differentiation, and apoptosis. In addition, sphingolipids, along with cholesterol, form detergent-resistant membrane microdomains, so called 'lipid-rafts', which are implicated in signal transduction and membrane trafficking. Sphingolipids are also relevant to infectious diseases. Various types of pathogens exploit the sphingolipids of host cells as membrane receptors. Sphingolipid metabolites regulate pathogen infection and host defense: for instance, a specific glycosphingolipid acts as an endogenous ligand for activation of natural killer T cells. Lipid-rafts of host cells serve as platforms also for infection signaling and entry of intracellular parasites. Moreover, some post-infectious autoimmune diseases result from production of antibodies cross-reacting with mammalian sphingolipids. Differences in the pathways of sphingolipid metabolism between mammals and non-mammals are good clues for rational development of new anti-infectious disease drugs. This review summarizes recent advances in sphingolipid biology related to infectious diseases.