Integrated transcriptomic and proteomic analysis reveals inflammatory activation and blood-brain barrier disruption...

Meningitis-associated extraintestinal pathogenic Escherichia coli (ExPEC) is a major cause of bacterial meningitis, yet the molecular mechanisms underlying blood-brain barrier (BBB) disruption during infection remain unclear. We employed integrated transcriptomic and proteomic analysis to investigate host responses of human cerebral microvascular endothelial cell line hCMEC/D3 to ExPEC strain RS218 infection. Multi-omics integration revealed coordinated immune activation, with upregulation of innate immune signaling pathways such as Toll-like receptor, NOD-like receptor, TNF, and IL-1 signaling, as well as antigen presentation pathways. In addition, we identified direct molecular evidence for BBB compromise, including concordant downregulation of tight junction protein ZO-1 at both transcriptomic and proteomic levels, validated by immunofluorescence showing reduced ZO-1 expression in infected cells. Several processes that may contribute to BBB breakdown were identified, such as glycosaminoglycan degradation, cytoskeletal reorganization, and suppression of TGF-β/SMAD signaling. Moreover, extensive metabolic dysregulation was evident, including downregulation of neural metabolic support functions and compromised protein homeostasis. Abundant discordance between transcriptomic and proteomic levels revealed complex post-transcriptional control mechanisms. In vitro experiments demonstrated RS218-induced cell death in brain endothelial cells, microglial cells, and peritoneal macrophages. Animal experiments confirmed systemic metabolic disruption, immune cell alteration, functional BBB disruption, and profound brain cytokine elevation. This integrated analysis advances our understanding of bacterial meningitis pathogenesis and identifies potential therapeutic targets.