Lipids in Entamoeba histolytica: Host-Dependence and Virulence Factors
Silvia Castellanos‐Castro, Jeni Bolaños, Esther Orozco
Abstract
Lipids are essential players in the performance of processes related to parasites pathogenesis. In particular, the highly phagocytic trophozoites of Entamoeba histolytica, the causative agent of amoebiasis, exhibit a dynamic membrane fusion and fission, especially, during the overstated motility of the parasite to reach and attack the epithelia and ingest target cells. During these complex cellular events to achieve host invasion and phagocytosis, lipids are key players. Synthesis and metabolism of lipids in this protozoan present remarkable differences with those performed by other eukaryotes. Trophozoites synthesize phosphatidylcholine and phosphatidylethanolamine by the Kennedy pathway; and sphingolipids, phosphatidylserine and phosphatidylinositol, by processes similar to those used by other eukaryotes. However, trophozoites lack enzymes for cholesterol and fatty acids synthesis, which are scavenged from the host or culture medium. Cholesterol, a molecule described as fundamental for the expression of virulence, is transported from the medium into the trophozoites by EhNPC1 and EhNPC2 proteins. Lipids are distributed by different pathways, including the participation of the endosomal sorting complex required for transport (ESCRT), involved in vesicle fusion and fission. Inside trophozoites, cholesterol interacts with the lysobisphosphatidic acid phospholipid and EhADH, an ALIX family protein: all they involved in phagocytosis. In this review, we summarize the known information on phospholipids synthesis and cholesterol transport as well as their metabolic pathways in E. histolytica; highlighting the mechanisms used by trophozoites to dispose lipids involved in the virulence processes.