Quercetagetin alleviates ischemic stroke injury by preserving macrophage/microglia homeostasis via inhibiting ACP5

The proinflammatory response triggered by macrophages/microglia plays a crucial role in the prognosis of acute ischemic stroke (AIS). Identifying novel targets to regulate the homeostasis of these cells is essential. Developing therapeutic strategies based on these targets could significantly improve AIS treatment outcomes. This study aims to identify new regulatory targets for macrophages/microglia homeostasis and to develop effective therapeutic strategies for AIS. Macrophage infiltration in AIS patients from GSE58294 and transient middle cerebral artery occlusion (tMCAO) mouse brain was observed using ssGSEA and immunofluorescence (IF). Integrating the MSigDB database, differentially expressed macrophage/microglia-associated genes (DEMAGs) were identified and further screened using machine learning. The protein level of the critical DEMAG in PBMCs, BV2 cells, and mouse brain tissues was detected with ELISA, western blot, IHC, and IF. siRNA was applied to investigate the effect of the critical DEMAG. A natural product library was screened to find a compound that targets the protein. The binding of compounds and proteins was analyzed through molecular docking, molecular dynamics simulations, CETSA, and MST analysis. This experiment observed increased macrophage infiltration in AIS patients. The upregulated critical DEMAG, ACP5, was more frequently detected in AIS patients' PBMCs, oxygen-glucose deprivation and reoxygenation (OGD/R)-treated BV2 cells and tMCAO mouse brain. Targeting the ACP5 protein, quercetagetin (QG) was identified as an inhibitor. QG could ameliorate systemic imbalance, brain injury, and cognitive impairment in tMCAO mice, partly by maintaining macrophage/microglia homeostasis and inhibiting ACP5. This study shows that ACP5 is a new promoter of macrophages/microglia proinflammatory responses, playing a critical role in regulating the excessive inflammation and oxidative stress associated with AIS. Furthermore, QG mitigates AIS-induced brain damage by inhibiting ACP5.