Proteomic analysis of exosomes derived from detrimental and protective microglia

Microglia, the primary resident immune cells in the brain, exhibit two distinct functional states: The detrimental (M1) phenotype and the protective (M2) phenotype. Exosomes, which are released by various cell types, play crucial roles in intercellular communication. While existing studies have shown that exosomes from microglia with different activation states can affect neuronal survival following ischemic stroke, a comprehensive exploration of the differences between these microglial phenotypes is still lacking. In this study, we treated primary microglia with lipopolysaccharide(LPS) or interleukin-4 (IL-4) to induce the M1 or M2 phenotype, respectively, and investigated the characteristics of the resulting exosomes. These microglia-derived exosomes can be internalized by neurons. Specifically, exosomes derived from M1microglia (M1-EXOs) exacerbated ischemia-induced neuronal apoptosis both in vivo and in vitro, while exosomes from M2 microglia (M2-EXOs) exhibited a protective effect. Subsequently, we conducted a quantitative proteomic analysis of M1-EXOsand M2-EXOs, characterizing 1129 proteins. Notably, M1-EXO proteins were primarily associated with inflammatory responses, neutrophil chemotaxis, and complement activation. In contrast, M2-EXO proteins were predominantly involved in protein transport and cellular proliferation. In addition, we analyzed key proteins, includingIL-6, SAA3, CCL5, CCL9, C3, CFB, SRGN, and sphingosine-1-phosphate phosphatase 1,which play central roles in the protein-protein interaction network. Overall, this dataset provides valuable insights into the proteomic profiles of exosomes derived from microglia with distinct phenotypes, enhancing our understanding of the mechanisms underlying microglial involvement in central nervous system diseases.