Effect of phosphatidylcholine–cholesterol liposomes on Entamoeba histolytica virulence

Abstract

Trophozoites of Entamoeba histolytica HM-1:IMSS become less virulent after long-term maintenance in axenic cultures. The factors responsible for the loss of virulence during in vitro cultivation remain unclear. However, it is known that in vitro cultivation of amoeba in culture medium supplemented with cholesterol restores their virulence. In this study, we analyzed the effect of adding phosphatidylcholine-cholesterol (PC-Chol) liposomes to the culture medium and evaluated the effect of this lipid on various biochemical and biological functions of E. histolytica HM-1:IMSS in terms of its virulence. The addition of PC-Chol liposomes to the culture medium maintained the virulence of these parasites against hamster liver at the same level as the original virulent E. histolytica strain, even though these amoebae were maintained without passage through hamster liver for 18 months. The trophozoites also showed increased endocytosis, erythrophagocytosis, and carbohydrate residue expression on the amoebic surface. Protease activities were also modified by the presence of cholesterol in the culture medium. These findings indicate the capacity of cholesterol to preserve amoeba virulence and provide an alternative method for the maintenance of virulent E. histolytica trophozoites without the need for in vivo procedures.

Overexpression of Differentially Expressed Genes Identified in Non-pathogenic and Pathogenic Entamoeba histolytica Clones Allow Identification of New Pathogenicity Factors Involved in Amoebic Liver Abscess Formation

“…Usually, trophozoites become less virulent after long-term culture and pathogenicity retainment requires regular animal passages or at least the addition of cholesterol to the culture medium [18–22]. …”

EhNPC1 and EhNPC2 Proteins Participate in Trafficking of Exogenous Cholesterol in Entamoeba histolytica Trophozoites: Relevance for Phagocytosis

“…histolytica trophozoites are highly dynamic cells with active movement and voracious phagocytosis. High cholesterol concentration in the medium enhances their virulence [2–4] and trophozoites loaded with cholesterol showed an enrichment of the Gal/GalNAc lectin in rafts and an increase of amoeba adherence to target cells [5]. Cholesterol is fundamental for vesicle formation and lipid rafts arrangements, and both are crucial events for movement and endocytosis [4].…”

Hypocholesterolemia in Patients with an Amebic Liver Abscess

“…In vitro , E. histolytica became avirulent after more than 2 years of maintenance in axenic culture, but regains its virulence if cholesterol or phosphatidylcholine-cholesterol (PC-Chol) liposomes are added to culture 9–14. Cholesterol-rich domain (lipid rafts) on the cell surface have been shown to control virulence in a variety of parasites, including E. histolytica 15,16…”