Medioresinol As a Novel PGC-1α Activator Prevents Pyroptosis of Endothelial Cells in Ischemic Stroke Through PPARα-GOT1 Axis.

Aim: Brain microvascular endothelial cells (BMVECs), as the important structure of blood-brain barrier (BBB), play a vital role in ischemic stroke. Pyroptosis of different cells in the brain may aggravate cerebral ischemic injury, and PGC-1 alpha plays a major role in pyroptosis. However, it is not known whether BMVECs undergo pyroptosis after ischemic stroke and whether PGC-1 alpha activator Medioresinol (MDN) we discovered may be useful against pyroptosis of endothelial cells and ischemic brain injury. Methods: For in vitro experiments, the bEnd.3 cells and BMVECs under oxygen and glucose-deprivation (OGD) were treated with or without MDN, and the LDH release, tight junction protein degradation, GSDMD-NT membrane location and pyroptosis-associated proteins were evaluated. For in vivo experiments, mice underwent transient middle cerebral artery occlusion (tMCAO) for ischemia model, and the neuroprotective effects of MDN were measured by infarct volume, the permeability of BBB and pyroptosis of BMVECs. For mechanistic study, effects of MDN on the accumulation of phenylalanine, mitochondrial reactive oxygen species (mtROS) were tested by untargeted metabolomics and MitoSOX Red probe, respectively. Results: BMVECs underwent pyroptosis after ischemia. MDN dose-dependently activated PGC-1 alpha, significantly reduced pyroptosis, mtROS and the expressions of pyroptosis-associated proteins (NLRP3, ASC, cleaved caspase1, IL-1 beta, GSDMD-NT), and increased ZO-1 and Occludin protein expressions in BMVECs. In tMCAO mice, MDN remarkably reduced brain infarct volume and the permeability of BBB, inhibited pyroptosis of BMVECs, and promoted long-term neurobehavioral functional recovery. Mechanistically, MDN promoted the interaction of PGC-1 alpha with PPARa to increase PPAR alpha nuclear translocation and transcription activity, further increased the expression of GOT1 and PAH, resulting in enhanced phenylalanine metabolism to reduce the ischemia-caused phenylalanine accumulation and mtROS and further ameliorate pyroptosis of BMVECs. Conclusion: In this study, we for the first time discovered that pyroptosis of BMVECs was involved in the pathogenesis of ischemic stroke and MDN as a novel PGC-1 alpha activator could ameliorate the pyroptosis of endothelial cells and ischemic brain injury, which might attribute to reduction of mtROS through PPAR alpha/GOT1 axis in BMVECs. Taken together, targeting endothelial pyroptosis by MDN may provide alternative therapeutics for brain ischemic stroke.