Abstract: Microglia-mediated neuroinflammation plays a crucial role in ischemic stroke; consequently, understanding its regulation could facilitate the development of therapies for ischemic stroke. Chemerin 15, a 15-amino acid peptide derived from chemerin, exerts powerful anti-inflammatory effects through ChemR23, modulates macrophage polarization, and diminishes inflammatory cytokine expression in peripheral inflammation models. However, its effects on microglia and stroke remain unclear. In this study, we used an in vitro oxygen/glucose deprivation BV2 cell model and a mouse model of ischemia-reperfusion injury to investigate the role of chemerin 15 in stroke and the underlying mechanisms. We co-cultured BV2 microglial cells with HT-22 hippocampal neurons and observed that chemerin 15 reduced apoptosis in HT-22 cells. Furthermore, we found that chemerin 15 binds to the ChemR23 receptor on the cell surface, inducing its internalization. This process regulated the activity of adenosine 5ʹ-monophosphate-activated protein kinase and inhibited its downstream target nuclear factor kappa B. These effects could be reversed by treatment with α-NETA, a ChemR23 inhibitor. In mice with ischemia-reperfusion injury, chemerin 15 modulated microglial polarization, reduced infarct volume and neuronal apoptosis, and facilitated cognitive and neurological function recovery. Our findings suggest that chemerin 15 suppresses the microglia-mediated inflammatory response, decreases neuronal apoptosis, and enhances long-term neurological function recovery by inducing ChemR23 internalization and regulating the adenosine 5ʹ-monophosphate-activated protein kinase/nuclear factor kappa B signaling pathway.

Key words: 5?-monophosphate-activated protein kinase (AMPK), chemerin 15, chemerin, ChemR23, ischemia–reperfusion injury, microglia, neuroinflammation, neuronal apoptosis, stroke, nuclear factor kappa B (NF-κB)