Trained Immunity Confers Prolonged Protection From Listeriosis

• DOI: 10.3389/fimmu.2021.723393
• Publication Date: 2021-09-17
• Authors: Charlotte Théroude; Marta Reverte; Tytti Heinonen; Eleonora Ciarlo; Irene T. Schrijver; Nikolaos Antonakos; Nicolas Maillard; F.P. Pralong; Didier Le Roy; Thierry Roger
• Keywords: Myelopoiesis; Monocytosis

Trained immunity refers to the ability of innate immune system exposed a first challenge provide an enhanced response secondary homologous or heterologous challenge. We reported that training induced with β-glucan one week before infection confers protection against broad-spectrum lethal bacterial infections. Whether this persists over time is unknown. To tackle question, we analyzed status and Listeria monocytogenes (L. monocytogenes) mice trained 9 weeks analysis. The induction increased bone marrow myelopoiesis blood counts Ly6Chigh inflammatory monocytes polymorphonuclear neutrophils (PMNs). Ex vivo, whole blood, PMNs from produced levels cytokines in microbial products limited growth L. monocytogenes. In following monocytogenes, peripheral leukocytes were massively depleted control but largely preserved mice. reduced also spleen mice, transwell experiments, showed spontaneous migration CXCL2/MIP2α-induced chemotaxis, suggesting promotes organs targeted by had higher glycolytic activity mitochondrial respiration than cells when Bacterial burden dissemination liver as well systemic inflammation (multiplex bead assay bioluminescence imaging) full agreement these results, powerfully protected listeriosis. Altogether, data suggest increases generation antimicrobial monocytes, which may confer prolonged infection.