TNF-α/PAD4 axis drives hyperhomocysteine-induced white matter injury after acute ischemic stroke

Neural functional impairment following stroke is strongly linked to the loss of white matter (WM) integrity, a process critically dependent on the successful differentiation of oligodendrocyte precursor cells (OPCs). Given that hyperhomocysteine (HHcy) aggravates stroke prognosis, we hypothesized that it impairs OPCs differentiation during the recovery period. Using in vivo (MCAO) and in vitro (OGD/R) models, we showed that HHcy hinders functional recovery, impairs OPC differentiation, and compromises WM integrity. Mechanistically, HHcy acts by upregulating tumor necrosis factor-α (TNF-α), which subsequently promotes the nuclear translocation of protein arginine deiminase 4 (PAD4). This leads to the upregulation of nucleosomal citrullinated histone 3 (CitH3) and the subsequent downregulation of myelin regulatory factor (MyRF), resulting in the observed inhibition of OPCs differentiation. Crucially, pharmacological inhibition of PAD4 using the pharmacological inhibitor YW3-56 effectively promoted OPCs differentiation and enhanced WM repair after ischemic stroke. Therefore, our findings identify the TNF-α/PAD4 pathway as a novel therapeutic target for reversing HHcy-induced white matter impairment and improving neurological outcomes after stroke.