Project description:Neonatal meningitis caused by Escherichia coli (NMEC) is a leading cause of morbidity and mortality in newborns, and its pathogenesis relies on the ability of the bacterium to adapt and survive in diverse host environments. Despite advances in neonatal care, significant gaps remain in our understanding of how NMEC reprogram their transcriptome to survive in physiologically relevant niches. This study investigated the transcriptomic profiles of E. coli strain RS218 (O18:H7:K1) in four under host-relevant environment —colonic fluid (CF), serum (S), human brain endothelial cells (HBECs) and cerebrospinal fluid (CSF)—to mimic the infection landscape of neonatal meningitis. High-throughput RNA sequencing (RNA-seq) was performed to profile NMEC’s transcriptomic responses in each niche, and differential gene expression analyses were conducted to identify enriched pathways.
Project description:Cronobacter (C.) is an important emerging opportunistic foodborne pathogen representing significant cause of mortality in neonatal patients with bacteremia and meningitis. Knowledge on the pathobiology of Cronobacter mediated meningitis has to a large extend been explored using in vitro models. To explore the innate immune response against the neonatal sepsis/meningitis causing isolate C. turicensis z3032 in vivo, zebrafish larvae (Danio rerio) were used as infection model. Following establishment of infection in zebrafish larvae with z3032, dual RNA-sequencing of host-pathogen was undertaken to profile RNA expression simultaneously in the pathogen and the head region of the zebrafish host.
Project description:Neonatal bacterial meningitis is a leading cause of infant morbidity and mortality, yet the molecular and cellular basis of the leptomeningeal response to infection remains poorly defined. Here, we study a mouse model of neonatal E. coli meningitis, combining conditional gene knockouts, leptomeningeal single-nucleus RNA sequencing, and endothelial cell culture to explore the role of Toll-like receptor 4 (TLR4) signaling in the host response to infection. Deletion of Tlr4 in non-myeloid cells dramatically reduced the inflammatory response in all leptomeningeal cell types and abrogated the infection-associated increase in vascular permeability. In a brain endothelial cell line (bEnd.3 cells), exposure to E. coli triggered NF-κB activation, selective internalization of Claudin-5, and increased monolayer permeability, responses that were eliminated by Tlr4 knockout. RNA-seq showed that TLR4 controls an NF-κB–driven transcriptional program that orchestrates the endothelial response to E. coli. These findings reveal multiple TLR4-dependent host responses to neonatal Gram-negative bacterial meningitis.
Project description:The blood-brain barrier (BBB) serves as a physiological and functional protective barrier between the brain parenchyma and the peripheral circulatory system, which protects the brain from bloodborne agents, including pathogens and toxins. Bacterial meningitis, a devastating disease occurring worldwide, remains a major cause of high mortality and morbidity, which can trigger BBB disruption and intense intracerebral inflammatory responses. Using single-cell RNA sequencing (scRNA-seq), we show that during neonatal meningitis Escherichia coli (NMEC) challenges, brain endothelial cells undergo pyroptosis and trigger the pyroptotic cascade through intercellular interactions, leading to inflammatory disruption of BBB and strong immune response within the brain. Analyses of the scRNA-seq dataset demonstrate that brian endothelial cells and microglia display the most sensitive to bacterial responses, and the crosstalk between brain vascular cells and immune cells remodels the central nervous system immune microenvironment. We employed a single-cell sequencing approach using 10x Genomics scRNAseq to study neonatal meningitis caused by Escherichia coli (NMEC) infection in mice. This study reveals that NMEC triggers pyroptosis in cerebral cortex cells, leading to inflammatory disruption of the BBB, activation of the apoptotic cascade, and triggering a strong immune response within the brain, disrupting the central nervous system's immune microenvironment. It helps us understand the immunopathological mechanisms of NMEC-induced meningitis and provides a theoretical basis for developing innovative therapeutic strategies targeting the function regulation of cortical cells or microglia and the apoptotic process, thus opening up new avenues for the prevention and treatment of neonatal meningitis.
