Interplay between cholesterol, Bis(monoacylglycerol)phosphate, and parasitophorous vacuole dynamics in Leishmania infantum infection of macrophages

Leishmania spp., the causative agents of leishmaniasis, are protozoan parasites displaying two life stages: promastigote in the insect vector and amastigote in host macrophages. After inoculation, the promastigote differentiates into the amastigote which multiplies within a parasitophorous vacuole formed by the fusion of the phagosome with the macrophage endolysosome. This compartment is characterized by a specific enrichment in bis(monoacylglycerol)phosphate (BMP), an atypical phospholipid that regulates endosomal dynamics and cholesterol trafficking. Host cell cholesterol is essential for parasite intracellular development. In this study, we examined the relationships between cholesterol, BMP, and the parasitophorous vacuole during the infection of J774 murine macrophages with L. infantum. Our results showed that cholesterol is redistributed in the vicinity of the parasite within infected cells. BMP is redistributed along with the same pattern and colocalizes with markers of the parasitophorous vacuole. Transcriptomic analyses revealed an upregulation of key genes governing cholesterol uptake and synthesis (HMGCR, SREBP2, LDLR) during infection and conversely a downregulation of ABCA1 involved in cholesterol efflux. Noteworthy, the overexpressions of HMGCR, SREBP2, LDLR were significantly attenuated by macrophage BMP enrichment. As for functional impact, BMP enrichment was associated with a significant increase of the parasite infectivity toward macrophages, assessed by infection rate and parasite load. Together, our results confirm the essentiality of macrophage cholesterol and demonstrate the involvement of BMP during Leishmania infection likely by facilitating parasitophorous vacuole remodeling and cholesterol trafficking.