RESUMO
BACKGROUND: Neonatal Escherichia coli (E coli) meningitis results in significant morbidity and mortality. We present a case of a premature infant with extensive central nervous system (CNS) injury from recurrent E coli infection and the non-traditional methods necessary to identify and clear the infection. CASE PRESENTATION: The infant was transferred to our institution's pediatric intensive care unit (PICU) after recurrence of E coli CNS infection requiring neurosurgical intervention. He had been treated for early onset sepsis (EOS) with ampicillin and gentamicin for 10 days followed by rapid development of ampicillin-resistant E coli septic shock and meningitis after discontinuation of antibiotics. Sterility of the CNS was not confirmed at the end of 21 days of cefepime therapy and was subsequently followed by recurrent ampicillin-resistant E coli septic shock and CNS infection. Despite 6 weeks of appropriate therapy with sterility of CSF by traditional methods, he suffered from intractable seizures with worsening hydrocephalus. Transferred to our institution, he underwent endoscopic 3rd ventriculostomy with cyst fenestration revealing purulent fluid and significant pleocytosis. An additional 3 weeks of systemic and intraventricular antibiotics with cefepime and tobramycin were given but a significant CNS neutrophil-predominant pleocytosis persisted (average of â¼ 21,000 cells/mm3). Repeated gram stains, cultures, polymerase chain reaction (PCR) testing, and metagenomic next generation sequencing (NGS) testing of CSF were negative for pathogens but acridine orange stain (AO) revealed numerous intact rod-shaped bacteria. After the addition of ciprofloxacin, sterility and resolution of CSF pleocytosis was finally achieved. CONCLUSION: Neonatal E coli meningitis is a well-known entity but unlike other bacterial infections, it has not proven amenable to shorter, more narrow-spectrum antibiotic courses or limiting invasive procedures such as lumbar punctures. Further, microbiologic techniques to determine CSF sterility suffer from poorly understood limitations leading to premature discontinuation of antibiotics risking further neurologic damage in vulnerable hosts.
Assuntos
Antibacterianos , Meningite devida a Escherichia coli , Humanos , Recém-Nascido , Antibacterianos/uso terapêutico , Recém-Nascido Prematuro , Doenças do Prematuro/tratamento farmacológico , Doenças do Prematuro/diagnóstico , Doenças do Prematuro/microbiologia , Meningite devida a Escherichia coli/tratamento farmacológicoAssuntos
Meningite devida a Escherichia coli , beta-Lactamases , Humanos , beta-Lactamases/genética , Meningite devida a Escherichia coli/microbiologia , Escherichia coli/isolamento & purificação , Escherichia coli/enzimologia , Escherichia coli/genética , Canal Medular/microbiologia , Masculino , Antibacterianos/uso terapêutico , Cistos/microbiologia , Criança , FemininoRESUMO
BACKGROUND: Meningitic Escherichia coli (E. coli) is the major etiological agent of bacterial meningitis, a life-threatening infectious disease with severe neurological sequelae and high mortality. The major cause of central nervous system (CNS) damage and sequelae is the bacterial-induced inflammatory storm, where the immune response of the blood-brain barrier (BBB) is crucial. METHODS: Western blot, real-time PCR, enzyme-linked immunosorbent assay, immunofluorescence, and dual-luciferase reporter assay were used to investigate the suppressor role of transforming growth factor beta 1 (TGFß1) in the immune response of brain microvascular endothelial cells elicited by meningitic E. coli. RESULT: In this work, we showed that exogenous TGFß1 and induced noncanonical Hedgehog (HH) signaling suppressed the endothelial immune response to meningitic E. coli infection via upregulation of intracellular miR-155. Consequently, the increased miR-155 suppressed ERK1/2 activation by negatively regulating KRAS, thereby decreasing IL-6, MIP-2, and E-selectin expression. In addition, the exogenous HH signaling agonist SAG demonstrated promising protection against meningitic E. coli-induced neuroinflammation. CONCLUSION: Our work revealed the effect of TGFß1 antagonism on E. coli-induced BBB immune response and suggested that activation of HH signaling may be a potential protective strategy for future bacterial meningitis therapy. Video Abstract.
Assuntos
Meningites Bacterianas , Meningite devida a Escherichia coli , MicroRNAs , Humanos , Escherichia coli/genética , Proteínas Hedgehog/metabolismo , Células Endoteliais/metabolismo , Meningite devida a Escherichia coli/metabolismo , Encéfalo/metabolismo , Barreira Hematoencefálica/microbiologia , Meningites Bacterianas/metabolismo , Imunidade , MicroRNAs/metabolismoRESUMO
Escherichia coli continues to be the predominant Gram-negative pathogen causing neonatal meningitis worldwide. Inflammatory mediators have been implicated in the pathogenesis of meningitis and are key therapeutic targets. The role of interleukin-22 (IL-22) in various diseases is diverse, with both protective and pathogenic effects. However, little is understood about the mechanisms underlying the damaging effects of IL-22 on the blood-brain barrier (BBB) in E. coli meningitis. We observed that meningitic E. coli infection induced IL-22 expression in the serum and brain of mice. The tight junction proteins (TJPs) components ZO-1, Occludin, and Claudin-5 were degraded in the mouse brain and human brain microvascular endothelial cells (hBMEC) following IL-22 administration. Moreover, the meningitic E. coli-caused increase in BBB permeability in wild-type mice was restored by knocking out IL-22. Mechanistically, IL-22 activated the STAT3-VEGFA signaling cascade in E. coli meningitis, thus eliciting the degradation of TJPs to induce BBB disruption. Our data indicated that IL-22 is an essential host accomplice during E. coli-caused BBB disruption and could be targeted for the therapy of bacterial meningitis.
Assuntos
Infecções por Escherichia coli , Meningites Bacterianas , Meningite devida a Escherichia coli , Humanos , Camundongos , Animais , Barreira Hematoencefálica , Meningite devida a Escherichia coli/metabolismo , Meningite devida a Escherichia coli/microbiologia , Meningite devida a Escherichia coli/patologia , Escherichia coli/metabolismo , Células Endoteliais , Interleucina 22 , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/farmacologia , Fator de Transcrição STAT3/genética , Fator de Transcrição STAT3/metabolismo , Fator de Transcrição STAT3/farmacologiaRESUMO
Numerous studies have shown that exosomes play a regulatory role in a variety of biological processes as well as in disease development and progression. However, exosome-mediated intercellular communication between brain microvascular endothelial cells (BMECs) and astrocytes during meningitic Escherichia coli (E. coli)-induced neuroinflammation remains largely unknown. Here, by using in vivo and in vitro models, we demonstrate that exosomes derived from meningitic E. coli-infected BMECs can activate the inflammatory response of astrocytes. A label-free quantitation approach coupled with LC-MS/MS was used to compare the exosome proteomic profiles of human BMECs (hBMECs) in response to meningitic E. coli infection. A total of 57 proteins exhibited significant differences in BMEC-derived exosomes during the infection. Among these proteins, growth differentiation factor 15 (GDF15) was significantly increased in BMEC-derived exosomes during the infection, which triggered the Erk1/2 signaling pathway and promoted the activation of astrocytes. The identification and characterization of exosome protein profiles in BMECs during meningitic E. coli infection will contribute to the understanding of the underlying pathogenic mechanisms from the perspective of intercellular communication between BMECs and astrocytes, and provide new insights for future prevention and treatment of E. coli meningitis.
Assuntos
Astrócitos , Encéfalo , Células Endoteliais , Escherichia coli , Exossomos , Exossomos/metabolismo , Astrócitos/metabolismo , Astrócitos/microbiologia , Astrócitos/patologia , Células Endoteliais/metabolismo , Células Endoteliais/microbiologia , Células Endoteliais/patologia , Encéfalo/metabolismo , Encéfalo/patologia , Humanos , Animais , Microvasos/patologia , Microvasos/metabolismo , Meningite devida a Escherichia coli/metabolismo , Meningite devida a Escherichia coli/microbiologia , Meningite devida a Escherichia coli/patologiaRESUMO
Bacterial meningitis remains a leading cause of infection-related mortality worldwide. Although Escherichia coli (E. coli) is the most common etiology of neonatal meningitis, the underlying mechanisms governing bacterial blood-brain barrier (BBB) disruption during infection remain elusive. We observed that infection of human brain microvascular endothelial cells with meningitic E. coli triggers the activation of early growth response 1 (Egr-1), a host transcriptional activator. Through integrated chromatin immunoprecipitation sequencing and transcriptome analysis, we identified Egr-1 as a crucial regulator for maintaining BBB integrity. Mechanistically, Egr-1 induced cytoskeletal changes and downregulated tight junction protein expression by directly targeting VEGFA, PDGFB, and ANGPTL4, resulting in increased BBB permeability. Meanwhile, Egr-1 also served as a master regulator in the initiation of neuroinflammatory response during meningitic E. coli infection. Our findings support an Egr-1-dependent mechanism of BBB disruption by meningitic E. coli, highlighting a promising therapeutic target for bacterial meningitis.
Assuntos
Meningites Bacterianas , Meningite devida a Escherichia coli , Humanos , Recém-Nascido , Barreira Hematoencefálica/microbiologia , Células Endoteliais/metabolismo , Escherichia coli , Meningites Bacterianas/metabolismo , Meningite devida a Escherichia coli/metabolismoRESUMO
Spontaneous community-acquired meningitis caused by E. coli is rare in the adult population. It is associated with a high risk of morbidity and mortality. We describe a case of a 72-year-old woman who presented with altered mental status and neck stiffness and was found to have E. coli meningitis. Urine cultures grew E. coli, representing a likely source. The E. coli strain was identified as sequence type 73 (E. coli ST73). Her symptoms and laboratory values improved following antibiotic initiation, and she was discharged from the hospital to a rehabilitation facility.
Assuntos
Infecções por Escherichia coli , Meningite devida a Escherichia coli , Meningite , Idoso , Feminino , Humanos , Antibacterianos/uso terapêutico , Escherichia coli , Infecções por Escherichia coli/diagnóstico , Infecções por Escherichia coli/tratamento farmacológico , Meningite/diagnóstico , Meningite/tratamento farmacológico , Meningite/etiologia , Meningite devida a Escherichia coli/diagnóstico , Meningite devida a Escherichia coli/complicações , Meningite devida a Escherichia coli/tratamento farmacológicoRESUMO
BACKGROUND: We aimed to build a prediction nomogram for early prediction of poor prognosis in children with Escherichia coli meningitis and analyzed the course of treatment and discharge criteria. METHODS: Eighty-seven pediatric patients with E coli meningitis were retrospectively recruited from the Children's Hospital of Chongqing Medical University between June 2012 and November 2021. Univariate analysis and binary logistic analysis were used to evaluate the risk factors, and the prediction model was built. RESULTS: E coli meningitis is more common in children <3 months old in our study (86.2%). Common complications were subdural effusion (39.1%), followed by hydrocephalus (13.8%) and repeated convulsions (12.6%). The mortality rate and sequelae rate of E coli meningitis in children was â¼10.9% and â¼6.3%, respectively. Univariate analysis showed that 13 clinical indicators were associated with poor prognosis of E coli meningitis in children. In binary logistic analysis, risk factors were seizures (P = .032) and the last cerebrospinal fluid glucose content before discharge (P = .002). A graphical nomogram was designed. The area under the receiver operating characteristic curve was 0.913. The Hosmer-Lemeshow test showed that the model was a good fit (P = .648). Internal validation proved the reliability of the prediction nomogram. CONCLUSIONS: E coli meningitis is more common in children <3 months old in our study. The rate of complications and sequelae are high. The prediction nomogram could be used to assess the risk of poor prognosis in children with E coli meningitis by clinicians.
Assuntos
Meningite devida a Escherichia coli , Meningite , Humanos , Criança , Lactente , Nomogramas , Meningite devida a Escherichia coli/complicações , Estudos Retrospectivos , Escherichia coli , Reprodutibilidade dos Testes , PrognósticoRESUMO
Strongyloidiasis, a helminth infection caused by Strongyloides stercoralis, can be complicated by hyperinfection, especially in the setting of immunosuppression; however, many patients go undiagnosed. One clue to diagnosis is unexplained gram-negative bacteraemia or meningitis in patients who are immunosuppressed. Serology can be helpful but may be negative in these patients who are immunocompromised.We present the case of a white cisgender man from Central America in his 40s, living with HIV, with a CD4 count of 77 cells/µL. He was diagnosed with Strongyloides hyperinfection after an increase in his steroid dose. He also had Escherichia coli meningitis and bacteraemia. Strongyloidiasis was diagnosed by stool microscopy despite a negative serology test.This case highlights the challenges in diagnosing strongyloidiasis in the setting of immunosuppression. A high index of clinical suspicion is warranted for patients living with HIV on high-dose corticosteroids. Up to three stool microscopy studies for Strongyloides should be sent in addition to serology.
Assuntos
Bacteriemia , Infecções por HIV , Meningite devida a Escherichia coli , Strongyloides stercoralis , Estrongiloidíase , Masculino , Animais , Humanos , Estrongiloidíase/complicações , Estrongiloidíase/diagnóstico , Estrongiloidíase/tratamento farmacológico , Bacteriemia/tratamento farmacológico , Infecções por HIV/complicaçõesRESUMO
Bacterial meningitis is a devastating disease occurring worldwide, with up to half of survivors left with permanent neurological sequelae. Neonatal meningitis-causing Escherichia coli (NMEC) is the most common Gram-negative bacillary organism that causes meningitis, particularly during the neonatal period. Here, RNA-seq transcriptional profiles of microglia in response to NMEC infection show that microglia are activated to produce inflammatory factors. In addition, we found that the secretion of inflammatory factors is a double-edged sword that promotes polymorphonuclear neutrophil (PMN) recruitment to the brain to clear the pathogens but, at the same time, induces neuronal damage, which may be related to the neurological sequelae. New neuroprotective therapeutic strategies must be developed for the treatment of acute bacterial meningitis. We found that transforming growth factor-ß (TGF-ß) may be a strong candidate in the treatment of acute bacterial meningitis, as it shows a therapeutic effect on bacterial-meningitis-induced brain damage. Prevention of disease and early initiation of the appropriate treatment in patients with suspected or proven bacterial meningitis are the key factors in reducing morbidity and mortality. Novel antibiotic and adjuvant treatment strategies must be developed, and the main goal for new therapies will be dampening the inflammatory response. Based on this view, our findings may help develop novel strategies for bacterial meningitis treatment.
Assuntos
Infecções por Escherichia coli , Meningites Bacterianas , Meningite devida a Escherichia coli , Recém-Nascido , Humanos , Microglia , Meningite devida a Escherichia coli/microbiologia , Meningites Bacterianas/microbiologia , Infecções por Escherichia coli/microbiologia , Escherichia coliAssuntos
Infecções Comunitárias Adquiridas , Infecções por Escherichia coli , Meningite devida a Escherichia coli , Meningite , Adulto , Infecções Comunitárias Adquiridas/epidemiologia , Infecções Comunitárias Adquiridas/microbiologia , Escherichia coli , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , França/epidemiologia , Humanos , Meningite/microbiologiaRESUMO
Neonatal meningitis-associated Escherichia coli (NMEC) is among the leading causes of bacterial meningitis and sepsis in newborn infants. Several virulence factors have been identified as common among NMEC, and have been shown to play an important role in the development of bacteremia and/or meningitis. However, there is significant variability in virulence factor expression between NMEC isolates, and relatively little research has been done to assess the impact of variable virulence factor expression on immune cell activation and the outcome of infection. Here, we investigated the role of NMEC strain-dependent P2X receptor (P2XR) signaling on the outcome of infection in neonatal mice. We found that alpha-hemolysin (HlyA)-expressing NMEC (HlyA+ ) induced robust P2XR-dependent macrophage cell death in vitro, while HlyA- NMEC did not. P2XR-dependent cell death was inflammasome independent, suggesting an uncoupling of P2XR and inflammasome activation in the context of NMEC infection. In vivo inhibition of P2XRs was associated with increased mortality in neonatal mice infected with HlyA+ NMEC, but had no effect on the survival of neonatal mice infected with HlyA- NMEC. Furthermore, we found that P2XR-dependent protection against HlyA+ NMEC in vivo required macrophages, but not neutrophils or NLRP3. Taken together, these data suggest that HlyA+ NMEC activates P2XRs which in turn confers macrophage-dependent protection against infection in neonates. In addition, our findings indicate that strain-dependent virulence factor expression should be taken into account when studying the immune response to NMEC.
Assuntos
Proteínas de Escherichia coli/toxicidade , Proteínas Hemolisinas/toxicidade , Inflamassomos/metabolismo , Meningite devida a Escherichia coli/metabolismo , Sepse Neonatal/metabolismo , Receptores Purinérgicos P2X/metabolismo , Animais , Células Cultivadas , Escherichia coli K12 , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Proteínas Hemolisinas/genética , Proteínas Hemolisinas/metabolismo , Macrófagos/metabolismo , Meningite devida a Escherichia coli/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Sepse Neonatal/microbiologia , Receptores Purinérgicos P2X/genéticaRESUMO
Avian meningitis Escherichia coli (E. coli) can cause acute bacterial meningitis which threatens poultry health, causes great economic losses in the poultry industry, and has recently been speculated as a potential zoonotic pathogen. Melatonin can counteract bacterial meningitis-induced disruption of the blood-brain barrier (BBB), neuroinflammation, and reduce mortality. There are increasing data showing that melatonin's beneficial effects on bacterial meningitis are associated with intestinal microbiota. In this study, our data showed that melatonin alleviated neurological symptoms, enhanced survival rate, protected the integrity of the BBB, reduced the bacterial load in various tissues and blood, and inhibited inflammation and neutrophil infiltration of brain tissue in an APEC TW-XM-meningitis mice model. The results of 16S rRNA showed that melatonin pretreatment significantly maintained the composition of intestinal microbiota in APEC-meningitis mice. The abundance and diversity of intestinal microbiota were disturbed in APEC TW-XM-meningitis mice, with a decreased ratio of Firmicutes to Bacteroides and an increased the abundance of Proteobacteria. Melatonin pretreatment could significantly improve the composition and abundance of harmful bacteria and alleviate the decreased abundance of beneficial bacteria. Importantly, melatonin failed to affect the meningitis neurologic symptoms caused by APEC TW-XM infection in antibiotic-pretreated mice. In conclusion, the results suggest that melatonin can effectively prevent meningitis induced by APEC TW-XM infection in mice, depending on the intestinal microbiota. This finding is helpful to further explore the specific target mechanism of melatonin-mediated intestinal microbiota in the prevention of and protection against Escherichia coli meningitis.
Assuntos
Infecções por Escherichia coli , Microbioma Gastrointestinal , Melatonina , Meningites Bacterianas , Meningite devida a Escherichia coli , Doenças das Aves Domésticas , Animais , Camundongos , Meningite devida a Escherichia coli/tratamento farmacológico , Escherichia coli/genética , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/microbiologia , Melatonina/farmacologia , Melatonina/uso terapêutico , RNA Ribossômico 16S/genética , Meningites Bacterianas/tratamento farmacológico , Doenças das Aves Domésticas/microbiologia , Galinhas/genéticaRESUMO
Alpha 7 nicotinic acetylcholine receptor (α7 nAChR) is critical for the pathogenesis of Escherichia coli (E. coli) K1 meningitis, a severe central nervous system infection of the neonates. However, little is known about how E. coli K1 manipulates α7 nAChR signaling. Here, through employing immortalized cell lines, animal models, and human transcriptional analysis, we showed that E. coli K1 infection triggers releasing of secreted Ly6/Plaur domain containing 1 (SLURP1), an endogenous α7 nAChR ligand. Exogenous supplement of SLURP1, combined with SLURP1 knockdown or overexpression cell lines, showed that SLURP1 is required for E. coli K1 invasion and neutrophils migrating across the blood-brain barrier (BBB). Furthermore, we found that SLURP1 is required for E. coli K1-induced α7 nAChR activation. Finally, the promoting effects of SLURP1 on the pathogenesis of E. coli K1 meningitis was significantly abolished in the α7 nAChR knockout mice. These results reveal that E. coli K1 exploits SLURP1 to activate α7 nAChR and facilitate its pathogenesis, and blocking SLURP1-α7 nAChR interaction might represent a novel therapeutic strategy for E. coli K1 meningitis.
Assuntos
Antígenos Ly/fisiologia , Barreira Hematoencefálica , Infecções por Escherichia coli/microbiologia , Escherichia coli/fisiologia , Meningite devida a Escherichia coli/fisiopatologia , Ativador de Plasminogênio Tipo Uroquinase/fisiologia , Receptor Nicotínico de Acetilcolina alfa7/agonistas , Animais , Antígenos Ly/genética , Linhagem Celular , Líquido Cefalorraquidiano/microbiologia , Células Endoteliais/microbiologia , Escherichia coli/isolamento & purificação , Hipocampo/metabolismo , Interações Hospedeiro-Patógeno , Humanos , Recém-Nascido , Memantina/farmacologia , Meningite devida a Escherichia coli/microbiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neutrófilos/fisiologia , Proteínas Recombinantes/metabolismo , Organismos Livres de Patógenos Específicos , Ativador de Plasminogênio Tipo Uroquinase/genética , Receptor Nicotínico de Acetilcolina alfa7/antagonistas & inibidores , Receptor Nicotínico de Acetilcolina alfa7/deficiênciaRESUMO
BACKGROUND: To examine the clinical characteristics and therapeutic outcome of Escherichia (E.) coli adult bacterial meningitis (ABM). METHODS: The demographic data, clinical and laboratory features and therapeutic outcome of 25 E. coli ABM patients were examined retrospectively. The clinical features of the reported E. coli ABM cases were also included for analysis. RESULTS: The 25 E. coli ABM patients included 12 women and 13 men, aged 33-78 years (mean= 59.9). Of these 25 patients, 13 had a postneurosurgical state as the underlying condition. As to the underlying medical conditions, diabetes mellitus was the most common, found in 9 of the 25 cases. Of the clinical manifestation, severe neurologic manifestations including altered consciousness (19), hydrocephalus (10), seizure (7) acute/subacute cerebral infarct (5), brain abscess (2), subdural empyema (1) and spinal abscess (1) were found, and the other clinical features included fever (21), septic shock (8), bacteremia (6) and hyponatremia (3). With treatment, the mortality rate was more than 44.0% and the presence of septic shock was a significant prognostic factor. With literature review, 29 community-acquired and 12 postneurosurgical E. coli ABM cases were enrolled, and severe neurologic manifestation and high mortality rate were also found. CONCLUSIONS: This preliminary overview of E. coli ABM revealed the underlying conditions, severe neurologic manifestation and high mortality rate. Further large-scale, prospective study is needed for a better delineation of this specific infectious syndrome of adult E. coli meningitis.
Assuntos
Meningites Bacterianas , Meningite devida a Escherichia coli , Adulto , Escherichia coli , Feminino , Humanos , Masculino , Meningites Bacterianas/terapia , Meningite devida a Escherichia coli/terapia , Estudos Retrospectivos , Resultado do TratamentoRESUMO
Appropriate interpretation of environmental signals facilitates niche specificity in pathogenic bacteria. However, the responses of niche-specific pathogens to common host signals are poorly understood. d-Serine (d-ser) is a toxic metabolite present in highly variable concentrations at different colonization sites within the human host that we previously found is capable of inducing changes in gene expression. In this study, we made the striking observation that the global transcriptional response of three Escherichia coli pathotypes - enterohaemorrhagic E. coli (EHEC), uropathogenic E. coli (UPEC) and neonatal meningitis-associated E. coli (NMEC) - to d-ser was highly distinct. In fact, we identified no single differentially expressed gene common to all three strains. We observed the induction of ribosome-associated genes in extraintestinal pathogens UPEC and NMEC only, and the induction of purine metabolism genes in gut-restricted EHEC, and UPEC indicating distinct transcriptional responses to a common signal. UPEC and NMEC encode dsdCXA - a genetic locus required for detoxification and hence normal growth in the presence of d-ser. Specific transcriptional responses were induced in strains accumulating d-ser (WT EHEC and UPEC/NMEC mutants lacking the d-ser-responsive transcriptional activator DsdC), corroborating the notion that d-ser is an unfavourable metabolite if not metabolized. Importantly, many of the UPEC-associated transcriptome alterations correlate with published data on the urinary transcriptome, supporting the hypothesis that d-ser sensing forms a key part of urinary niche adaptation in this pathotype. Collectively, our results demonstrate distinct pleiotropic responses to a common metabolite in diverse E. coli pathotypes, with important implications for niche selectivity.
Assuntos
Escherichia coli/genética , Serina/metabolismo , Transcriptoma , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/isolamento & purificação , Escherichia coli/metabolismo , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Regulação Bacteriana da Expressão Gênica , Humanos , Meningite devida a Escherichia coli/microbiologia , Especificidade da Espécie , Infecções Urinárias/microbiologiaRESUMO
Neonatal bacterial meningitis is a life-threatening disease in newborns, and neonatal meningitis Escherichia coli (NMEC) is the second most frequent bacteria causing this disease worldwide. In order to further understand the characteristics of this pathogen, an E. coli isolate W224 N from newborns with meningitis was sequenced for detailed genetic characterization and the virulence was tested by a series of phenotypic experiments. W224 N has a circular chromosome and three plasmids. It belongs to ST95 and the serotype is O18:H7. Comparative genomic analysis showed that W224 N was closely related to E. coli neonatal meningitis isolates RS218 and NMEC O18. There are 11 genomic islands in W224 N and most of the GIs are specific to W224 N. W224 N has most of the virulence factors other neonatal meningitis isolates have. The virulence genes located both on the genome and plasmid. At the same time, we found a virulence factor cdiA only present in W224 N but absent in the other five genomes analyzed. In vitro experiment showed that W224 N has strong serum resistance ability, low biofilm formation ability and high flagellar motility. It also has a very strong toxicity to mice and amoeba. The whole genome as well as in vitro and in vivo experiments showed that W224 N is a high virulent strain. The results can help us better learn about the pathogenicity of neonatal meningitis E. coli.
Assuntos
Proteínas de Escherichia coli , Escherichia coli/genética , Genoma Bacteriano , Meningite devida a Escherichia coli , Animais , Escherichia coli/patogenicidade , Proteínas de Membrana , Meningite devida a Escherichia coli/microbiologia , Camundongos , Virulência , Fatores de Virulência/genéticaRESUMO
BACKGROUND: Escherichia coli is the most common Gram-negative bacterium causing meningitis, and E. coli meningitis is associated with high mortality and morbidity throughout the world. Our previous study showed that E. coli can colonize the brain and cause neuroinflammation. Increasing evidence supports the involvement of miRNAs as key regulators of neuroinflammation. However, it is not clear whether these molecules participate in the regulation of meningitic E. coli-mediated neuroinflammation. METHODS: The levels of miR-155 and miR-146a, as well as their precursors, in E. coli-infected astrocytes were measured using quantitative real-time PCR (qPCR). Overexpression and knockdown studies of miR-155 and miR-146a were performed to observe the effects on bacterial loads, cytokines, chemokines, and NF-κB signaling pathways. Bioinformatics methods were utilized to predict the target genes, and these target genes were validated using qPCR, Western blotting, and luciferase reporter system. In vivo knockdown of miR-155 and miR-146a was carried out to observe the effects on bacterial loads, inflammatory genes, astrocyte activation, microglia activation, and survival in a mouse model. RESULTS: The levels of miR-155, miR-146a, and their precursors were significantly increased in astrocytes during E. coli infection. miR-155 and miR-146a were induced by the NF-κB-p65 signaling pathway upon infection. Overexpressing and inhibiting miR-155 and miR-146a in astrocytes did not affect the bacterial loads. Further, the in vitro overexpression of miR-155 and miR-146a suppressed the E. coli-induced inflammatory response, whereas the inhibition of miR-155 and miR-146a enhanced it. Mechanistically, miR-155 inhibited TAB2, and miR-146a targeted IRAK1 and TRAF6; therefore, they functioned collaboratively to modulate TLR-mediated NF-κB signaling. In addition, both miR-155 and miR-146a could regulate the EGFR-NF-κB signaling pathway. Finally, the in vivo suppression of E. coli-induced miR-155 and miR-146a further promoted the production of inflammatory cytokines, aggravated astrocyte and microglia activation, and decreased mouse survival time, without affecting the bacterial loads in the blood and brain. CONCLUSIONS: E. coli infection induced miR-155 and miR-146a, which collectively regulated bacteria-triggered neuroinflammatory responses through negative feedback regulation involving the TLR-mediated NF-κB and EGFR-NF-κB signaling pathways, thus protecting the central nervous system from further neuroinflammatory damage.
Assuntos
Inflamação/microbiologia , Meningite devida a Escherichia coli/imunologia , Meningite devida a Escherichia coli/metabolismo , MicroRNAs/imunologia , MicroRNAs/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Antagomirs , Astrócitos/imunologia , Astrócitos/microbiologia , Linhagem Celular , Escherichia coli/imunologia , Inflamação/metabolismo , Quinases Associadas a Receptores de Interleucina-1 , Camundongos , NF-kappa B/metabolismo , Transdução de Sinais , Fator 6 Associado a Receptor de TNF/metabolismoRESUMO
Escherichia coli (E. coli) is the most common Gram-negative bacteria causing neonatal meningitis. The occurrence of bacteremia and bacterial penetration through the blood-brain barrier are indispensable steps for the development of E. coli meningitis. Reactive oxygen species (ROS) represent the major bactericidal mechanisms of neutrophils to destroy the invaded pathogens. In this protocol, the time-dependent intracellular ROS production in neutrophils infected with meningitic E. coli was quantified using fluorescent ROS probes detected by a real-time fluorescence microplate reader. This method may also be applied to the assessment of ROS production in mammalian cells during pathogen-host interactions.