ABSTRACT: Expression of receptors for inflammatory mediators in murine vagal nodose versus jugular capsaicin-sensitive (Trpv1-positive) C-fiber neurons
Project description:Capsaicin-sensitive (Trpv1-positive) sensory C-fibers derived from vagal ganglia innervate the visceral organs, and respond to inflammatory mediators and noxious stimuli. These neurons play an important role in maintenance of visceral homeostasis, and contribute to the symptoms of visceral inflammatory diseases. Vagal sensory neurons are located in two ganglia, the jugular ganglia (derived from the neural crest), and the nodose ganglia (from the epibranchial placodes). The functional difference, especially in response to immune mediators, between jugular and nodose neurons is not fully understood. In this study, we microscopically isolated murine nodose and jugular capsaicin-sensitive / Trpv1-expressing C-fiber neurons and performed transcriptome profiling using ultra-low input RNA sequencing.
Project description:Given the inaccessibility of human sensory neurons (SNs), it is yet to be established whether the signalling pathway between histamine 1 receptor (H1R) and transient receptor potential cation channel subfamily V member 1 (TRPV1) is conserved between humans and mammalian models. Accessible human SNs are vital for identifying TRPV1 antagonists with higher potential for success in clinical trials targeting histaminergic itch, especially given TRPV1's species specificity concerns. Hence to build a humanized histamine-dependent itch model, we derived peripheral sensory neurons from human pluripotent stem cells (hiPSC-SNs) and validated channel functionality using immunostaining, calcium imaging and multielectrode array (MEA) recordings. Here, we demonstrated that a subset of hiPSC-SNs exhibits co-expression of H1R and TRPV1, responding to both histamine and capsaicin agonists. We found that inhibiting TRPV1 prevented histamine activation. Moreover, we show that silencing histamine-sensitive neurons reduces capsaicin response, and silencing capsaicin-sensitive neurons diminishes histamine response. To assess the ability of hiPSC-SNs in TRPV1 antagonist drug screening, we evaluated two well-established hyperthermic and three thermal-neutral TRPV1 antagonists. Our finding identifies SB366791, a thermal-neutral antagonist, as a potent inhibitor of H1R activation. The use of hiPSC-SNs may therefore provide a physiologically relevant means to perform large-scale screening to discover anti-pruritic agents predictive of actual efficacy in human clinical trials.
Project description:Guided by gut sensory cues, humans and animals prefer nutritive sugars over non-caloric sweeteners. But how the gut differentiates such stimuli to rapidly guide preferences remains unknown. In the intestine, innervated enteroendocrine cells synapse with the vagus nerve to convey luminal sugar stimuli to the brain within seconds. Here, we sequenced individual vagal nodose neuron cells from the left and right nodose to assess their relative contribution to sugar signaling from the gut. The neurons lack expression of sugar receptors and transporters, but do express receptors for neurotransmitters and neuropeptides secreted by intestinal sensory epithelial cells.
Project description:Vagal afferent neurons are thought to convey primarily physiological information, whereas spinal afferents transmit noxious signals from the viscera to the central nervous system. In order to elucidate molecular identities for these different properties, we compared gene expression profiles of neurons located in nodose ganglia (NG) and dorsal root ganglia (DRG) in mice. Intraperitoneal administration of Alexa Fluor-488 conjugated Cholera toxin B allowed identification of neurons projecting to the viscera. Fluorescent neurons in DRG (from T10 to T13) and NG were isolated using laser capture microdissection. Gene expression profiles of visceral afferent neurons, obtained by microarray hybridization, were analysed using multivariate spectral map analysis, SAM algorithm (Significance Analysis of Microarray data) and fold-difference filtering. A total of 1996 genes were found to be differentially expressed in DRG versus NG, including 41 G-protein coupled receptors and 60 ion channels. Expression profiles obtained on laser-captured neurons were contrasted to those obtained on whole ganglia demonstrating striking differences and the need for microdissection when studying visceral sensory neurons because of dilution of the signal by somatic sensory neurons. Furthermore, a detailed catalogue of all adrenergic and cholinergic, GABA, glutamate, serotonin and dopamine receptors, voltage-gated potassium, sodium and calcium channels and transient receptor potential cation channels present in visceral afferents is provided. Our genome-wide expression profiling data provide novel insight into molecular signatures that underlie both functional differences and similarities between NG and DRG visceral sensory neurons. Moreover, these findings will offer novel insight into mode of action of pharmacologic agents modulating visceral sensation. Experiment Overall Design: Three separate experiments were performed. First, 5 whole dorsal root ganglia were compared to 7 whole nodose ganglia. Second, Laser captured visceral neurons derived from 5 dorsal root ganglia and 5 nodose ganglia were compared on MG-U74Av2. Third, Laser captured visceral neurons derived from 9 dorsal root ganglia and 11 nodose ganglia were compared on Mouse430_2.
Project description:In order to explain the molecular mechanisms of capsaicin-induced proliferation of gingival epithelial cells (GECs), a microarray analysis was performed. Several cell proliferation related genes were significantly up-regulated. These data suggest that TRPV1 signaling in GEC may induce transcriptional upregulation of growth factors, which results in an increased proliferation rate. Simian virus 40 (SV40) T-antigen-immortalized human gingival epithelial cell line, epi4, were stimulated with 1 M-NM-<M capsaicin for 4 hours. Total RNA was isolated and subjected to gene expression analysis using Agilent whole human genome oligo microarray.
Project description:We developed an approach to rapidly eliminate the subgroup of sensory neurons expressing the heat-gated cation channel TRPV1 from dissociated rat sensory ganglia using agonist treatment followed by density centrifugation. To identify transcripts predominantly expressed in TRPV1-positive neurons, we compared the transcriptome of all cells within sensory ganglia versus all cells without TRPV1 expressing neurons using RNA-Seq.
Project description:We developed an approach to rapidly eliminate the subgroup of sensory neurons expressing the heat-gated cation channel TRPV1 from dissociated rat sensory ganglia using agonist treatment followed by density centrifugation. To identify transcripts predomintly expressed in TRPV1-positive neurons, we compared the transcriptome of all cells within sensory ganglia versus all cells without TRPV1 expressing neurons using RNA-Seq.
Project description:We developed an approach to rapidly eliminate the subgroup of sensory neurons expressing the heat-gated cation channel TRPV1 from dissociated rat sensory ganglia using agonist treatment followed by density centrifugation. To identify transcripts predomintly expressed in TRPV1-positive neurons, we compared the transcriptome of all cells within sensory ganglia versus all cells without TRPV1 expressing neurons using RNA-Seq. Four replicate experiments with RNA from DRG neurons of one rat per experiment were performed. Dissociated neurons were split up in three parts, treated with solvent DMSO (0.1%), casaicin (10 µM), or RTX (100 nM) for 30 min followed by gradient centrifugation. RNA was extracted from the remaining pellet containing either all cells or all cells without TRPV1-positive neurons.
Project description:In order to explain the molecular mechanisms of capsaicin-induced proliferation of gingival epithelial cells (GECs), a microarray analysis was performed. Several cell proliferation related genes were significantly up-regulated. These data suggest that TRPV1 signaling in GEC may induce transcriptional upregulation of growth factors, which results in an increased proliferation rate.
Project description:Mammalian airways and lungs are richly innervated by bronchopulmonary sensory neurons, the vast majority of which are derived from the vagal sensory ganglia. In the present study we set out to perform high coverage single cell RNA sequencing on a population of identified murine bronchopulmonary sensory neurons collected from the vagal sensory ganglia to better define the molecular expression profiles of these cell types. Given the importance of P2X2 in differentiating nodose from jugular sensory neurons, we further aimed to investigate the relationship between transcriptional expression of identified genes and P2X2 expression.