Cytosol-living Trypanosoma cruzi amastigotes scavenge cholesterol from host ER and Golgi complex

Abstract

Chagas Disease, caused by the protozoan parasite Trypanosoma cruzi, stands as a prevalent neglected disease in Latin America. The amastigote stage, the replicant intracellular form of the parasite, is a crucial player in infection persistence within vertebrate hosts. The amastigotes exhibit remarkable adaptability regarding the cell type that they infect, being able to modulate their metabolism and growth based on the host cell resources availability. Lipid metabolism emerges as a key determinant of amastigote growth, with a dependency on the host cells lipid resources. While the parasite can synthesize some sterols and fatty acids, it also scavenges these essential components, particularly cholesterol, from the host. Alterations in the hosts cholesterol metabolism, potentially regulated by SREBPs, contribute to increased intracellular cholesterol levels, fostering parasite development. However, the mechanisms underlying cholesterol uptake by amastigotes remained elusive. Here, we investigate the cholesterol trafficking mechanism from host cells to amastigotes by employing a fluorescent cholesterol analog. Using advanced imaging techniques, such as confocal fluorescence microscopy and high-resolution volume electron microscopy we demonstrated that amastigotes internalize extracellular-derived cholesterol, defined the uptake kinetics for cholesterol by amastigotes, and demonstrated that cholesterol is important for amastigote development. Analysis of the interaction of host cell ER with the amastigotes revealed by the presence of membrane contact sites between this organelle and the amastigote plasma membrane. We also showed that amastigotes can take up host ER and Golgi proteins, probably by endocytosis, paving a new mechanism for host cell scavenging of molecules by the parasite. Author SummaryChagas Disease, a widespread yet often overlooked challenge in Latin America, is driven by the parasite Trypanosoma cruzi. Understanding the amastigote stage, the parasites replicative form, is crucial for grasping infection persistence. This study reveals a critical survival strategy - amastigotes adeptly scavenging cholesterol from host cells. We demonstrated that the amastigotes can take up cholesterol from the host and that cholesterol is important for parasite development. Analysis of host cell organelles involved with cholesterol traffic, ER and Golgi, suggested their involvement, establishing crucial conduits for cholesterol acquisition. Deciphering these mechanisms illuminates the intricate interplay between parasite and host, presenting a potential treatment target. The parasites reliance on host cholesterol underscores adaptable growth strategies. This breakthrough deepens Chagas Disease understanding, paving the way for targeted therapeutic interventions.