Project description:Preterm birth is currently the leading cause of neonatal morbidity and mortality. Genetic, immunological and infectious causes are suspected. Preterm infants have a higher risk of severe bacterial neonatal infections, most of which are caused by Escherichia coli an in particular E. coli K1strains. Women with history of preterm delivery have a high risk of recurrence and therefore constitute a target population for the development of vaccine against E. coli neonatal infections. Here, we characterized the immunological, microbiological and protective properties of a live attenuated vaccine candidate in adult female mice and their pups against after a challenge by K1 and non-K1 strains of E. coli. Our results show that the E. coli K1 E11 aroA vaccine induces strong immunity, driven by polyclonal bactericidal antibodies. In our model of meningitis, pups born to mothers immunized before mating were well protected against various K1 and non-K1 strains of E. coli. Given the very high mortality rate and the neurological sequalae associated with neonatal E. coli K1 meningitis, our results constitute preclinical proof of concept for the development of a live attenuated vaccine against severe E. coli infections in women at risk of preterm delivery.
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: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.
Project description:Streptococcus pneumoniae (the pneumococcus) account for significant morbidity and mortality worldwide, causing life-threatening diseases such as pneumonia, bacteremia and meningitis. In this study, we used microarray analysis to compare gene expression patterns of either serotype 4 or serotype 6A pneumococci in the nasopharynx and blood of mice, as a model to identify genes involved in invasion of blood in the context of occult bacteremia in humans.
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.
2026-02-20 | GSE319556 | GEO
Project description:meningitis-causing E. coli strains infect microglia in vivo
Project description:The genus Cronobacter (formerly called Enterobacter sakazakii) is composed of five species; C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, and C. dublinensis. The genus includes opportunistic human pathogens, and the first three species have been associated with neonatal infections. The most severe diseases are caused in neonates and include fatal necrotizing enterocolitis and meningitis. The genetic basis of the diversity within the genus is unknown, and few virulence traits have been identified. We report here the first sequence of a member of this genus, C. sakazakii strain BAA-894. The genome of Cronobacter sakazakii strain BAA-894 comprises a 4.4 Mb chromosome (57% GC content) and two plasmids; 31 Kb (51% GC) and 131 Kb (56% GC). The genome was used to construct a 385,000 probe oligonucleotide tiling DNA microarray covering the whole genome. Comparative genomic hybridization (CGH) was undertaken on five other C. sakazakii strains, and representatives of the four other Cronobacter species. Among 4,382 annotated genes inspected in this study, about 55% of genes were common to all C. sakazakii strains and 43% were common to all Cronobacter strains, with 10 - 17% absence of genes. CGH highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units. Comparative genomic hybridization highlighted 15 clusters of genes in C. sakazakii BAA-894 that were divergent or absent in more than half of the tested strains; six of these are of probable prophage origin. Putative virulence factors were identified in these prophage and in other variable regions. A number of genes unique to Cronobacter species associated with neonatal infections (C. sakazakii, C. malonaticus and C. turicensis) were identified. These included a copper and silver resistance system known to be linked to invasion of the blood-brain barrier by neonatal meningitic strains of Escherichia coli. In addition, genes encoding for multidrug efflux pumps and adhesins were identified that were unique to C. sakazakii strains from outbreaks in neonatal intensive care units.