Extracellular vesicles from early ‐stage P. falciparum‐infected red blood cells contain PfEMP1 and induce transcriptional changes in human monocytes

Abstract Pathogens can release extracellular vesicles (EVs) for cell‐cell communication and host modulation. EVs from Plasmodium falciparum, the deadliest malaria parasite species, can transfer drug resistance genes between parasites. EVs from late‐stage parasite‐infected RBC (iRBC‐EVs) are immunostimulatory and affect endothelial cell permeability, but little is known about EVs from early‐stage iRBC. We detected the parasite virulence factor PfEMP1, which is responsible for iRBC adherence and a major contributor to disease severity, in EVs only up to 12 hours‐post RBC invasion. Furthermore, using PfEMP1 transport knock‐out parasites, we determined that EVs originated from inside the iRBC rather than the iRBC surface. Proteomic analysis detected 101 parasite and 178 human proteins in iRBC‐EVs. Primary human monocytes stimulated with iRBC‐EVs released low levels of inflammatory cytokines, and showed transcriptomic changes. Stimulation with iRBC‐EVs from PfEMP1 knock‐out parasites induced more gene expression changes, and affected pathways involved in defense response, stress response, and response to cytokines, suggesting a novel function of PfEMP1 when present in EVs. We show for the first time the presence of PfEMP1 in early‐stage P. falciparum iRBC‐EVs, and the effects of these EVs on primary human monocytes, uncovering a new mechanism of potential parasite pathogenesis and host interaction.
Source: Cellular Microbiology - Category: Microbiology Authors: Tags: RESEARCH ARTICLE Source Type: research