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

• Published in: Cellular microbiology Vol. 20; no. 5; pp. e12822 - n/a
• Main Authors: Sampaio, Natália G., Emery, Samantha J., Garnham, Alexandra L., Tan, Qiao Y., Sisquella, Xavier, Pimentel, Matthew A., Jex, Aaron R., Regev‐Rudzki, Neta, Schofield, Louis, Eriksson, Emily M.
• Format: Journal Article
• Language: English
• Published: England Hindawi Limited 01.05.2018
• Subjects: Animals; Cell Adhesion - genetics; Cell Communication - genetics; Cell interactions; Cell permeability; Cellular stress response; Cytokines; diseases; Drug resistance; Endothelial cells; Endothelial Cells - metabolism; Endothelial Cells - pathology; Erythrocytes; Erythrocytes - parasitology; Extracellular vesicles; Extracellular Vesicles - genetics; Extracellular Vesicles - metabolism; Gene expression; Host-Parasite Interactions - genetics; Humans; immunology; Immunostimulation; infection; Inflammation; Malaria; Malaria, Falciparum - blood; Malaria, Falciparum - genetics; Malaria, Falciparum - parasitology; Monocytes; Monocytes - metabolism; Monocytes - parasitology; Parasites; Pathogenesis; Plasmodium falciparum; Plasmodium falciparum - genetics; Plasmodium falciparum - pathogenicity; Proteins; Proteomics; Protozoan Proteins - genetics; Transcription; transcriptomics; Vector-borne diseases; Vesicles; Virulence; Virulence factors; transcriptomics; diseases; infection; extracellular vesicles; proteomics; immunology
• ISSN: 1462-5814; 1462-5822
• DOI: 10.1111/cmi.12822

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‐hr post‐RBC invasion. Furthermore, using PfEMP1 transport knockout 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 knockout parasites induced more gene expression changes and affected pathways involved in defence 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. Extracellular vesicles from Plasmodium falciparum‐infected red blood cells were found to contain PfEMP1, a key parasite virulence factor. PfEMP1 was only present in vesicles during the first 12 hours of infection. Vesicles induced transcriptional changes in human monocytes, which were partially dependent on PfEMP1, suggesting a novel mechanism of host modulation by the parasite.