AUTHOR=Barbero Angela María , Hernández Del Pino Rodrigo Emanuel , Fuentes Federico , Barrionuevo Paula , Pasquinelli Virginia 

TITLE=Platelets promote human macrophages-mediated macropinocytosis of Clostridioides difficile

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=13

YEAR=2024

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2023.1252509

DOI=10.3389/fcimb.2023.1252509

ISSN=2235-2988

ABSTRACT=<p><italic>Clostridioides difficile</italic> is the main causative agent of hospital-acquired diarrhea and the potentially lethal disease, <italic>C. difficile</italic> infection. The cornerstone of the current therapy is the use of antibiotics, which is not fully effective. The molecular mechanisms, inflammatory conditions and host-immune responses that could benefit the persistence or elimination of <italic>C. difficile</italic> remain unclear. Macrophages perform different ways of endocytosis as part of their immune surveillance functions and platelets, classically known for their coagulatory role, are also important modulators of the immune system. The aim of this study was to evaluate the endocytosis of vegetative <italic>C. difficile</italic> by human macrophages and the involvement of platelets in this process. Our results showed that both macrophages and platelets interact with live and heat-killed <italic>C. difficile</italic>. Furthermore, platelets form complexes with human monocytes in healthy donor’s fresh blood and the presence of <italic>C. difficile</italic> increased these cell-cell interactions. Using flow cytometry and confocal microscopy, we show that macrophages can internalize <italic>C. difficile</italic> and that platelets improve this uptake. By using inhibitors of different endocytic pathways, we demonstrate that macropinocytosis is the route of entry of <italic>C. difficile</italic> into the cell. Taken together, our findings are the first evidence for the internalization of vegetative non-toxigenic and hypervirulent <italic>C. difficile</italic> by human macrophages and highlight the role of platelets in innate immunity during <italic>C. difficile</italic> infection. Deciphering the crosstalk of <italic>C. difficile</italic> with immune cells could provide new tools for understanding the pathogenesis of <italic>C. difficile</italic> infection and for the development of host-directed therapies.</p>