Plasma-derived extracellular vesicles from Plasmodium vivax patients signal spleen fibroblasts via NF-kB facilitating parasite cytoadherence

Extracellular vesicles are major components of circulating plasma holding insights into pathological processes. Here, we demonstrate high levels of EVs in plasma from patients with Plasmodium vivax (PvEVs), the most widely distributed human malaria parasite. Moreover, mass spectrometry analysis identified parasite proteins in PvEVs and their in vivo distribution demonstrated major spleen tropism. PvEVs were preferentially taken up by human spleen fibroblasts (hSFs) and this uptake induced specific and dose-dependent upregulation of ICAM-1 associated with the translocation of NF-kB to the nucleus. After activation of hSFs by PvEVs, P. vivax-infected reticulocytes from patients showed specific adhesion properties reversed by inhibiting NF-kB translocation to the nucleus. Together, these data provide novel physiological EV-based insights into the mechanisms of human malaria pathology and support the existence of P. vivax-adherent parasite subpopulations in the microvasculature of the human spleen