ClC-3-depedent polarization of microglia protects against cerebral ischemic injury in mice

Polarization of microglia has attracted great attention in ischemic stroke. Emerging evidence suggests that chloride channel 3 (ClC-3) is involved in inflammatory responses and stroke. However, the link between ClC-3 and polarization of microglia in ischemic stroke remains unclear. Herein, we found both cerebral ischemia and oxygen-glucose deprivation (OGD) induced a significant upregulation of ClC-3 in microglia. While knockdown of ClC-3 markedly increased nuclear factor kappa B (NF-κB) and CD86, and decreased CD206 in BV-2 cells under OGD conditions, facilitating them to shift into a M1-like phenotype. Furthermore, ClC-3 knockout significantly aggravated infarct volume and neurological deficits, accompanied by increased activated microglia in the peri-infarct area 1 day after cerebral ischemia. By contrast, ClC-3 overexpression obviously suppressed nuclear translocation of NF-κB, decreased OGD-induced elevated mRNA levels of TNF-α, IL-1β and IL-10, and enhanced M2-like markers (Arg1, CD206, and TREM2) in microglia, leading to alleviated infarct volume and neurological deficits. While ClC-3 overexpression could not reverse a transformation from M1-like phenotype to M2-like polarization in presence of lipopolysaccharide (LPS) and interferon gamma (IFNγ) treatment for 24 h. Collectively, our findings indicate that ClC-3-dependent polarization of microglia is critically important for protecting against cerebral ischemia injury, suggesting ClC-3 is a promising therapeutic target for ischemic stroke.