KAT5 knockdown alleviates microglial inflammatory injury following acute cerebral ischemia through enhanced STAT6 activity

In ischemic stroke (IS), microglia exhibit dynamic functional shifts, contributing to tissue damage during the acute phase and promoting repair in the chronic phase. The mechanisms underlying these transitions are poorly understood. We utilized a KAT5 knockdown rat model in conjunction with a BV2 cell model to investigate the negative regulatory mechanism of Lysine Acetyltransferase 5 (KAT5) on Signal Transducer and Activator of Transcription 6 (STAT6) and its effects in IS. We determined that STAT6 activation occurred following an increase in STAT6 protein levels and its acetylation, suggesting negative regulation of STAT6 during the early stages of IS. Given that acetylation inhibits STAT6 activity, KAT5 was identified as a potential acetyltransferase for STAT6 through an online acetyltransferase prediction tool combined with mass spectrometry analysis. We observed increased KAT5 protein levels and KAT5-positive microglia/macrophages at 12 h post-ischemic injury. Co-immunoprecipitation confirmed the interaction between STAT6 and KAT5. KAT5 knockdown in microglia in vitro significantly reduced the production of pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and increased anti-inflammatory cytokines IL-10 and transforming growth factor-β (TGF-β) levels by decreasing STAT6 acetylation and enhancing its transcriptional activity. KAT5 knockdown in vivo improved modified neurological severity scores (mNSS), food intake, and reduced infarct volumes, pathological damage, and microglial-mediated pro-inflammatory responses. These findings indicated that KAT5 is integral to the early suppression of STAT6 activity in microglia following cerebral ischemia. Therefore, targeting KAT5 to restore STAT6 activity represents a potential therapeutic approach to mitigate microglial inflammatory injury in the acute phase of IS.