Genomic and proteomic approaches highlight phagocytosis of living and apoptotic human cells by the parasite Entamoeba histolytica

Phagocytosis plays a major role during the invasive process of the human intestine by the pathogenic amoeba E. histolytica. This parasite is the etiologic agent causing amoebic dysentery, a worldwide disease causing 50 million of clinical cases leading to about 100,000 deaths annually. The invasive process is characterized by a local acute inflammation and the destruction of the intestinal tissue at the invasion site. The recent sequencing of the E. histolytica genome has opened the way to large-scale approaches to study parasite virulence such as processes involved in human cell phagocytosis. In particular, two different studies have recently described the phagosome proteome, providing new insights into the process of phagocytosis by this pathogenic protozoan. It has been previously described that E. histolytica induces apoptosis and phagocytosis of the human target cells. Induction of apoptosis by the trophozoites is thought to be involved in the close regulation of the inflammatory response occurring during infection. Little is known about the molecular mechanisms responsible for induction of apoptosis or in the recognition of apoptotic cells by E. histolytica. In this review, we comment on the recent data we obtained after isolation of the early phagosomes and the identification of its associated proteins. We focus on the surface molecules potentially involved in human cell recognition. In particular, we propose several parasite molecules, potentially involved in the induction of apoptosis and/or the phagocytosis of human apoptotic cells.