Differential Effect of Extracellular Vesicles Derived from Plasmodium falciparum -Infected Red Blood Cells on Monocyte Polarization.

Malaria is a life-threatening tropical arthropod-borne disease caused by spp. Monocytes are the primary immune cells to eliminate malaria-infected red blood cells. Thus, the monocyte's functions are one of the crucial factors in controlling parasite growth. It is reasoned that the activation or modulation of monocyte function by parasite products might dictate the rate of disease progression. Extracellular vesicles (EVs), microvesicles, and exosomes, released from infected red blood cells, mediate intercellular communication and control the recipient cell function. This study aimed to investigate the physical characteristics of EVs derived from culture-adapted isolates (-EVs) from different clinical malaria outcomes and their impact on monocyte polarization. The results showed that all strains released similar amounts of EVs with some variation in size characteristics. The effect of -EV stimulation on M1/M2 monocyte polarization revealed a more pronounced effect on CD14CD16 intermediate monocytes than the CD14CD16 classical monocytes with a marked induction of -EVs from a severe malaria strain. However, no difference in the levels of microRNAs (miR), miR-451a, miR-486, and miR-92a among -EVs derived from virulent and nonvirulent strains was found, suggesting that miR in -EVs might not be a significant factor in driving M2-like monocyte polarization. Future studies on other biomolecules in -EVs derived from the strain with high virulence that induce M2-like polarization are therefore recommended.