Parasitic diseases continue to afflict millions of people globally. Hence, revealing new mechanisms that parasites utilize to advance their growth is essential for fighting the transmission of infectious diseases, particularly malaria, which almost half the world’s human population is at high risk of contracting.
Extracellular vesicles (EVs) provide a central mechanism of cell–cell communication. While EVs are found in most organisms, their pathogenesis-promoting roles in parasites are of particular interest given the potential for medical insight and consequential therapeutic intervention. Yet, a key features of EVs in human parasitic protozoa remain elusive: their roles and mechanisms of biogenesis.
In this ERC project, we study the roles of malaria-secreted EVs in two main host systems: I) Their direct and most essential host cells, the human Red Blood Cells (RBCs); and
II) Human immune cells as monocytes.
I) Studying the role of EVs in RBC hosts: we purified vesicles from malaria-infected (i) RBCs and introduced them to naïve RBCs. We then explored how these EVs rewire human RBCs to make them more amenable to parasite invasion.
II) Immune defense systems have evolved to protect the host from microbial invasion by detecting pathogen-derived material and responding through signaling cascades. At the same time, pathogens have developed an arsenal of strategies, including EVs, to evade and manipulate the immune response. We have provided evidence that
EVs released by the malaria parasite Plasmodium falciparum contain RNA and parasitic gDNA. We have further found that the parasites while growing inside RBCs use these EVs to engage host cytosolic innate immune cell receptors from a distance. Upon internalization by monocytes, the EVs' genetic cargo is released within the cell cytosol, leading to molecular alterations of the immune system, most probably as a decoy mechanism to confuse the immune response. We are currently studying the underlying molecular mechanism of this immune alteration.
