Caspase-4/11-mediated non-canonical pyroptosis disrupts blood-brain barrier integrity via VEGFA/VEGFR2 signaling in Escherichia coli meningitis.

Bacterial meningitis is a severe inflammatory disease of the central nervous system (CNS) that involves blood-brain barrier (BBB) disruption. However, the underlying mechanisms remain incompletely understood. We previously reported that meningitis-associated extraintestinal pathogenic Escherichia coli (ExPEC) induces BBB dysfunction through endothelial pyroptosis and tight junction degradation, but the role of caspase-4/11 in these processes remains unclear. Here, we demonstrate that infection with the ExPEC strain RS218 activates caspase-4/11 and triggers GSDMD-mediated pyroptosis accompanied by IL-1β release, while simultaneously causing degradation of the tight junction proteins ZO-1 and Occludin in brain endothelial cells. Inhibition of caspase-4/11 effectively attenuated pyroptosis and IL-1β secretion, and alleviated BBB disruption as evidenced by reduced tight junction degradation and improved transendothelial electrical resistance. We further demonstrated that caspase-4/11 activation induces VEGFA production and VEGFR2 phosphorylation. Inhibition of VEGFR2 suppressed both GSDMD-mediated pyroptosis and tight junction degradation, and improved transendothelial electrical resistance, indicating that VEGFA/VEGFR2 signaling is required for caspase-4/11-mediated BBB disruption. Additionally, NLRP3 also contributed to caspase-4/11 activation, and ROS inhibition reduced pyroptotic cell death. In vivo experiments showed that caspase-11 inhibition significantly improved mouse survival, reduced bacterial burden in multiple organs including the brain, suppressed GSDMD cleavage, alleviated tight junction protein disruption, and decreased neuroinflammation as evidenced by reduced cytokine levels and diminished inflammatory cell infiltration, and attenuated BBB leakage as demonstrated by Evans blue extravasation. Our findings reveal a critical role of caspase-4/11 in BBB disruption and identify VEGFA/VEGFR2 signaling as a key mediator of this process. This study provides new insights into bacterial meningitis pathogenesis and highlights caspase-4/11 and VEGFA/VEGFR2 as potential therapeutic targets.