Sphk1/S1P pathway promotes blood-brain barrier breakdown after intracerebral hemorrhage through inducing Nlrp3-mediated endothelial cell pyroptosis

Abstract

Intracerebral hemorrhage (ICH) is a severe stroke subtype with high mortality and limited therapeutic options. The blood-brain barrier (BBB) disruption post-ICH exacerbates secondary brain injury, highlighting the need for targeted therapies to preserve BBB integrity. This study aims to investigate the role of the Sphk1/S1P pathway in BBB breakdown following ICH and to evaluate the therapeutic potential of Sphk1 inhibition in mitigating this disruption. Using a combination of human patient samples, mouse models of ICH, and in vitro cellular assays, this study assesses the expression of Sphk1/S1P and its impact on BBB integrity. The Sphk1 inhibitor PF543 is utilized to explore the pathway's role in modulating Nlrp3-mediated endothelial cell pyroptosis. SiRNA targeting Sphk1 is utilized to examine the suppression of pyroptosis in brain endothelial cells (bEnd.3) following the knockdown of Sphk1. The results indicate significant upregulation of Sphk1/S1P in the peri-hematomal brain tissue after ICH, which correlates with increased BBB permeability. Pharmacological inhibition of Sphk1 with PF543 attenuates BBB leakage, reduces hematoma volume, and improves neurological outcomes in mice. Mechanistic insights reveals that Sphk1 inhibition preserves tight junction proteins and decreases endothelial transcytosis, stabilizing the BBB. Furthermore, Sphk1/S1P is shown to promote Nlrp3-mediated endothelial cell pyroptosis, with the protective effects of Sphk1 inhibition mediates through the ERK1/2 signaling pathway. The Sphk1/S1P pathway plays a critical role in ICH-induced BBB breakdown, and its inhibition presents a promising therapeutic strategy for ICH management. Targeting this pathway may offer a novel approach to reduce secondary brain injury and improve patient outcomes following ICH.