Extracellular vesicles （EVs）, secreted in response to microbial infection, play a crucial role in modulating immune and infectious responses. Sepsis, a life-threatening multiple organ dys-function caused by a systemic dysregulated inflammatory response to infection, poses signif-icant challenges in therapeutic interventions. Despite extensive trials, achieving satisfactory therapeutic outcomes remain elusive. Our prior research unveiled the potential of LL-37, a human cathelicidin host-defense peptide, in improving the survival rates of septic mice subjected to cecal ligation and puncture （CLP）. We herein explored the capacity of LL-37 to modulate the functions of neutrophils, the primary defenders against pathogens, focusing on its ability to enhance the secretion of anti-inflammatory EVs and promote cell motility. In vitro stimulation of neutrophils with LL-37 led to elevated secretion of EVs （PMN-LL-37-EV） containing anti-microbial molecules such as lactoferrin and CRAMP, consistent with their observed antibac-terial activity. Injection of PMN-LL-37-EV into CLP mice significantly improved survival rates and reduced bacterial burdens. Notably, lung tissues from PMN-LL-37-EV-injected mice ex-hibited reduced inflammation. 3D imaging by a Lattice light-sheet microscopy with a time-lapse function revealed heightened neutrophil motility following LL-37 treatment. In addition, ad-ministration of LL-37 to CLP mice resulted in enhanced neutrophil infiltration and EV release at the site of inflammation, within the peritoneal cavity. Taken together, LL-37 orchestrates the motility of neutrophils to inflammatory sites and promotes the secretion of an-ti-bacterial/anti-inflammatory EVs in septic mice, thereby attenuating bacterial loads and con-ferring protection against lethal septic conditions.
