Anti-inflammatory mechanisms of neutrophil membrane-coated nanoparticles without drug loading.

Neutrophil membrane-coated nanoparticles (NM-NPs) are nanomedicines with traits of mimicking the surface properties and functions of neutrophils, which are the most abundant type of white blood cells in the human body. NM-NPs have been widely used as targeted drug delivery systems for various inflammatory diseases, but their intrinsic effects on inflammation are not fully characterized yet. This study found that NM-NPs could modulate inflammation by multiple mechanisms without drug loading. NM-NPs could inhibit the recruitment of neutrophils and macrophages to the inflamed site by capturing chemokines and blocking their adhesion to inflamed endothelial cells. After internalized by macrophages and other phagocytic cells, NM-NPs could alter their phenotype by phosphatidylserine and simultaneously degrade the sequestered and neutralized cytokines and chemokines by lysosomal degradation. Under these effects, NM-NPs exhibited significant anti-inflammatory effects on LPS-induced inflammatory liver injury in vivo without drug loading. Our study unveiled the anti-inflammatory effects and mechanisms of NM-NPs without drug loading, and provided new insights and evidence for understanding their biological effects and safety, as well as developing more effective and safe targeted drug delivery systems.