Abstract DP091: Enhanced Lactylation of Methyltransferase-Like 3 (METTL3) Drives Maladaptive Autophagy and Ineffective Reperfusion in Ischemic Stroke

Objectives: Reperfusion remains the cornerstone of ischemic stroke treatment, but a significant proportion of patients experience ineffective reperfusion, where vessel recanalization fails to salvage tissue. The molecular basis of this paradox is unclear. We investigated whether lactate-driven histone and protein lactylation contribute to maladaptive autophagy via METTL3, thereby promoting ineffective reperfusion injury. Methods: Rat middle cerebral artery occlusion (MCAO,2 h vs 6 h) and SH-SY5Y oxygen–glucose deprivation/reoxygenation (OGD/R) models were used to study epigenetic-metabolic regulation of autophagy. Infarct size (TTC), neurological function (mNSS), and ultrastructure (TEM) were assessed. Autophagy flux was quantified by LC3-II/I ratio and p62. Multi-omics (RNA-seq, proteomics) and mass spectrometry identified lactylation targets. Chromatin immunoprecipitation (ChIP-qPCR) verified promoter occupancy. Interventions included lactate supplementation, lactylation inhibition (C646, oxamate), and AAV-mediated delivery of METTL3 K215R mutants. Results: Ineffective reperfusion determined by delayed reperfusion (after 6 h MCAO) led to larger infarcts (p