Listeria monocytogenes Modulates Macrophage Inflammatory Responses to Facilitate Its Intracellular Survival by Manipulating Macrophage-Derived Exosomal ncRNAs

Exosomes are nanoscale vesicles secreted by cells that play vital regulatory roles in intercellular communication and immune responses. <i>Listeria monocytogenes</i> (<i>L. Monocytogenes</i>, <i>LM</i>) is a notable Gram-positive intracellular parasitic bacterium that infects humans and diverse animal species. However, the specific biological function of exosomes secreted by macrophages during <i>L. Monocytogenes</i> infection (hereafter EXO-LM) remains elusive. Here, we discovered that EXO-LM stimulated the secretion of inflammation-associated cytokines by macrophages, facilitating the intracellular survival of <i>L. monocytogenes</i> within macrophages. Transcriptomic analysis shows that EXO-LM significantly upregulates immune recognition and inflammation-related signaling pathways in macrophages. Furthermore, a ceRNA regulatory network comprising exosomal ncRNAs and macrophage RNAs was constructed through EXO-LM transcriptome sequencing. Utilizing bioinformatics and dual-luciferase reporter assays, we identified two potential binding sites between lncRNA Rpl13a-213 and miR-132-3p. Cell transfection experiments demonstrated that Rpl13a-213 overexpression augmented pro-inflammatory cytokine expression in macrophages, in contrast to the suppression by miR-132-3p overexpression. The decrease in Rpl13a-213 upon EXO-LM stimulation enhances miR-132-3p expression, dampening the inflammatory response in macrophages and aiding <i>L. monocytogenes</i> intracellular survival. This study unveils the immunomodulatory function of exosomal ncRNAs originating from macrophages, which provides fresh perspectives into the mechanisms underlying macrophage inflammatory response regulation by <i>L. monocytogenes</i>-infected cell-derived exosomes.