Project description:The meninges are densely innervated by nociceptive sensory neurons that mediate pain and headache. How pain and neuro-immune interactions impact meningeal host defenses is unclear. Bacterial meningitis causes life-threatening infections of the meninges and central nervous system (CNS), affecting over one million people a year. Here we find that Nav1.8+ neuron signaling to immune cells in the meninges via the neuropeptide calcitonin gene-related peptide (CGRP) exacerbates bacterial meningitis. Nociceptor ablation reduced meningeal and brain invasion by two bacterial pathogens: Streptococcus pneumoniae and Streptococcus agalactiae. S. pneumoniae activated nociceptors via Pneumolysin to release CGRP, which acts through its receptor RAMP1 on meningeal macrophages to inhibit chemokine expression, neutrophil recruitment and antimicrobial defenses. Macrophage-specific RAMP1 deficiency or blockade of RAMP1 signaling enhanced immune responses and bacterial clearance in meninges and brain. Therefore, targeting a neuro-immune axis in the meninges can enhance host defenses and may be a potential treatment for bacterial meningitis.
Project description:Meningitis is a complex disease which can be caused by infection with either viral or bacterial pathogens. Viral meningitis is usually a sterile self-limiting disease with a good clinical prognosis, while bacterial meningitis is a potentially more serious disease with a higher mortality rate. Early diagnosis of bacterial meningitis is of paramount importance, as intervention with antimicrobial therapy increases the likelihood of a favourable clinical outcome. Routine diagnosis in many laboratories is still dependent to some degree on traditional methods e.g. culture, though molecular methods have been developed which can give a shorter time to diagnosis. However, there is not as yet a single test format that can detect all bacterial pathogens capable of causing meningitis. In addition, many tests e.g. real-time PCR have a finite limit for multiplexing and do not provide additional information such as strain or serogroup which is useful during outbreaks and for retrospective epidemiological surveillance. To this end we have developed a microarray probe set for detection of meningitis-associated bacterial pathogens including those in the N. meningitidis serogroups. Here we demonstrate utility of this array in specific detection of represented bacterial species and strains and in detection of pathogen signals in cerebrospinal fluid samples from patients with suspected bacterial meningitis. This method shows promise for development as a diagnostic tool; however, we discuss the technical issues encountered and suggest mechanisms to improve resolution of pathogen-specific signals in complex clinical samples.
Project description:Meningitis is a complex disease which can be caused by infection with either viral or bacterial pathogens. Viral meningitis is usually a sterile self-limiting disease with a good clinical prognosis, while bacterial meningitis is a potentially more serious disease with a higher mortality rate. Early diagnosis of bacterial meningitis is of paramount importance, as intervention with antimicrobial therapy increases the likelihood of a favourable clinical outcome. Routine diagnosis in many laboratories is still dependent to some degree on traditional methods e.g. culture, though molecular methods have been developed which can give a shorter time to diagnosis. However, there is not as yet a single test format that can detect all bacterial pathogens capable of causing meningitis. In addition, many tests e.g. real-time PCR have a finite limit for multiplexing and do not provide additional information such as strain or serogroup which is useful during outbreaks and for retrospective epidemiological surveillance. To this end we have developed a microarray probe set for detection of meningitis-associated bacterial pathogens including those in the N. meningitidis serogroups. Here we demonstrate utility of this array in specific detection of represented bacterial species and strains and in detection of pathogen signals in cerebrospinal fluid samples from patients with suspected bacterial meningitis. This method shows promise for development as a diagnostic tool; however, we discuss the technical issues encountered and suggest mechanisms to improve resolution of pathogen-specific signals in complex clinical samples. We designed as part of a larger pan-pathogen microarray a sub-set of probes to meningitis-associated bacterial pathogens. We present here data confirming the pathogen-specificity of many of these probes and their potential use in clinical diagnosis through testing on a small number of patient clinical samples using human DNA and no added nucleic acid controls. These data are from single channel Cy3-labelled nucleic acids. Four technical replicates for each feature are included on the array.
Project description:The human-specific, Gram-negative bacterium Neisseria meningitidis (Nm) is a leading cause of bacterial meningitis world-wide. It has been described that Nm can enter the central nervous system via the blood-cerebrospinal fluid barrier (BCSFB), which is constituted by the epithelial cells of the choroid plexus. Using a recently established in vitro model of the human BCSFB based on human malignant choroid plexus papilloma (HIBCPP) cells we investigated the cellular response of HIBCPP cells challenged with the meningitis-causing Nm strain MC58. In comparison we analysed the answer to the closely related unencapsulated carrier isolate Nm M-NM-114. Transcriptome analysis revealed a stronger transcriptional response after infection with strain MC58, in particular with its capsule deficient mutant MC58siaD-, which correlated with bacterial invasion levels. Expression evaluation and Gene Set Enrichment Analysis pointed to a NF-M-NM-:B-mediated pro-inflammatory immune response involving up-regulation of the transcription factor IM-NM-:BM-NM-6. Consistent with this, infected cells secreted significant levels of pro-inflammatory chemokines and cytokines, among others, IL8, CXCL1-3 and the IM-NM-:BM-NM-6 target gene product IL6. Expression profile of pattern recognition receptors in HIBCPP cells and the response to specific agonists indicates that TLR2 rather than TLR4 is involved in the cellular reaction following Nm infection. Human malignant choroid plexus papilloma (HIBCPP) cells were infected from the basolateral side with the meningitis-causing Neisseria meningitidis disease isolate MC58, its non-capsulated mutant MC58siaD- and the Neisseria meningitidis carrier isolate M-NM-114 for 4 h.The transcriptional response of HIBCPP cells to the different Neisseria meningitidis strains was evaluated by microarray analysis. Untreated HIBCPP cells served as control. Three replicates of each condition were analysed.
Project description:Background: Meningitis can be caused by several viruses and bacteria. Identifying the causative pathogen as quickly as possible is crucial to initiate the most optimal therapy, as acute bacterial meningitis is associated with a significant morbidity and mortality. Bacterial meningitis requires antibiotics, as opposed to enteroviral meningitis, which only requires supportive therapy. Clinical presentation is usually not sufficient to differentiate between viral and bacterial meningitis, thereby necessitating cerebrospinal fluid (CSF) analysis by PCR and/or time-consuming bacterial cultures. However, collecting CSF in children is not always feasible and a rather invasive procedure. Methods: In 12 Belgian hospitals, we obtained acute blood samples from children with signs of meningitis (49 viral and 7 bacterial cases). (aged between 3 months and 16 years). After pathogen confirmation on CSF, the patient was asked to give a convalescent sample after recovery. 3’mRNA sequencing was performed to determine differentially expressed genes (DEGs) to create a host transcriptomic profile. Results: Enteroviral meningitis cases displayed the largest upregulated fold change enrichment in type I interferon production, response and signaling pathways. Patients with bacterial meningitis showed a significant upregulation of genes related to macrophage and neutrophil activation. We found several significantly DEGs between enteroviral and bacterial meningitis. Random forest classification showed that we were able to differentiate enteroviral from bacterial meningitis with an AUC of 0.982 on held-out samples. Conclusions: Enteroviral meningitis has an innate immunity signature with type 1 interferons as key players. Our classifier, based on blood host transcriptomic profiles of different meningitis cases, is a possible strong alternative for diagnosing enteroviral meningitis.
Project description:The human-specific, Gram-negative bacterium Neisseria meningitidis (Nm) is a leading cause of bacterial meningitis world-wide. It has been described that Nm can enter the central nervous system via the blood-cerebrospinal fluid barrier (BCSFB), which is constituted by the epithelial cells of the choroid plexus. Using a recently established in vitro model of the human BCSFB based on human malignant choroid plexus papilloma (HIBCPP) cells we investigated the cellular response of HIBCPP cells challenged with the meningitis-causing Nm strain MC58. In comparison we analysed the answer to the closely related unencapsulated carrier isolate Nm α14. Transcriptome analysis revealed a stronger transcriptional response after infection with strain MC58, in particular with its capsule deficient mutant MC58siaD-, which correlated with bacterial invasion levels. Expression evaluation and Gene Set Enrichment Analysis pointed to a NF-κB-mediated pro-inflammatory immune response involving up-regulation of the transcription factor IκBζ. Consistent with this, infected cells secreted significant levels of pro-inflammatory chemokines and cytokines, among others, IL8, CXCL1-3 and the IκBζ target gene product IL6. Expression profile of pattern recognition receptors in HIBCPP cells and the response to specific agonists indicates that TLR2 rather than TLR4 is involved in the cellular reaction following Nm infection.
Project description:This study includes 1146 samples of host genotyping data (genotyped) from Illumina Omni arrays. Samples were collected from adults (>16 yrs) patients with CSF confirmed bacterial meningitis in the Netherlands between 2006 and 2015. Metadata includes patient outcome, species of bacteria, and for 467 samples a link to an ENA run with the associated bacterial genome (S. pneumoniae only).
Project description:Symbiotic bacteria inhabiting the distal human gut have evolved under intense pressure to utilize complex carbohydrates, predominantly plant cell wall glycans abundant in our diets. These substrates are recalcitrant to depolymerization by digestive enzymes encoded in the human genome, but are efficiently targeted by some of the ~103-104 bacterial species that inhabit this niche. These species augment our comparatively narrow carbohydrate digestive capacity by unlocking otherwise unusable sugars and fermenting them into host-absorbable forms, such as short-chain fatty acids. We used phenotype profiling, whole-genome transcriptional analysis and molecular genetic approaches to investigate complex glycan utilization by two fully sequenced and closely related human gut symbionts: Bacteroides thetaiotaomicron and Bacteroides ovatus. Together these species target all of the common glycosidic linkages found in the plant cell wall, as well as host polysaccharides, but each species exhibits a unique ‘glycan niche’: in vitro B. thetaiotaomicron targets plant cell wall pectins in addition to linkages contained in host N- and O-glycans; B. ovatus uniquely targets hemicellulosic polysaccharides along with several pectins, but is deficient in host glycan utilization.
Project description:Symbiotic bacteria inhabiting the distal human gut have evolved under intense pressure to utilize complex carbohydrates, predominantly plant cell wall glycans abundant in our diets. These substrates are recalcitrant to depolymerization by digestive enzymes encoded in the human genome, but are efficiently targeted by some of the ~103-104 bacterial species that inhabit this niche. These species augment our comparatively narrow carbohydrate digestive capacity by unlocking otherwise unusable sugars and fermenting them into host-absorbable forms, such as short-chain fatty acids. We used phenotype profiling, whole-genome transcriptional analysis and molecular genetic approaches to investigate complex glycan utilization by two fully sequenced and closely related human gut symbionts: Bacteroides thetaiotaomicron and Bacteroides ovatus. Together these species target all of the common glycosidic linkages found in the plant cell wall, as well as host polysaccharides, but each species exhibits a unique ‘glycan niche’: in vitro B. thetaiotaomicron targets plant cell wall pectins in addition to linkages contained in host N- and O-glycans; B. ovatus uniquely targets hemicellulosic polysaccharides along with several pectins, but is deficient in host glycan utilization.