Induction of Fas mediated caspase-8 independent apoptosis in immune cells byArmigeres subalbatussaliva

BackgroundIt is widely recognized that the introduction of saliva of bloodsucking arthropods at the site of pathogen transmission might play a central role in vector-borne infections. However, how the interaction between salivary components and the host immune system takes place and which physiological processes this leads to has yet to be investigated.Armigeres subalbatusis one of the prominent types of mosquitoes involved in the transmission of parasitic and viral diseases in humans and animals.Methodology/Principal FindingsUsing murine peritoneal macrophages and lymphocytes, and human peripheral mononuclear cells (PBMCs), this study shows that saliva of the femaleAr. subalbatusinduces apoptosis via interaction with the Fas receptor within a few hours but without activating caspase-8. The process further activates downstream p38 MAPK signaling, a cascade that leads to the induction of apoptosis in capase-3 dependent manner. We further illustrate thatAr. subalbatussaliva suppresses proinflammatory cytokines without changing IL-10 levels, which might happen as a result of apoptosis.ConclusionsOur study shows for the first time that saliva-induced apoptosis is the leading phenomenon exerted byAr. subalbatusthat impede immune cells leading to the suppression of their effecter mechanism.