Vagal sensory neurons drive mucous cell metaplasia.
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ABSTRACT:
SUBMITTER: Talbot S
PROVIDER: S-EPMC8603302 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Background and aimsDestroying visceral sensory nerves impacts pancreatic islet function, glucose metabolism, and diabetes onset, but how islet endocrine cells interact with sensory neurons has not been studied.MethodsWe characterized the anatomical pattern of pancreatic sensory innervation by combining viral tracing, immunohistochemistry, and reporter mouse models. To assess the functional interactions of β-cells with vagal sensory neurons, we recorded Ca2+ responses in individual nodose neurons in vivo while selectively stimulating β-cells with chemogenetic and pharmacologic approaches.ResultsWe found that pancreatic islets are innervated by vagal sensory axons expressing Phox2b, substance P, calcitonin-gene related peptide, and the serotonin receptor 5-HT3R. Centrally, vagal neurons projecting to the pancreas terminate in the commissural nucleus of the solitary tract. Nodose neurons responded in vivo to chemogenetic stimulation of β-cells and to pancreas infusion with serotonin, but were not sensitive to insulin. Responses to chemogenetic and pharmacologic stimulation of β-cells were blocked by a 5-HT3R antagonist and were enhanced by increasing serotonin levels in β-cells. We further confirmed directly in living pancreas slices that sensory terminals in the islet were sensitive to serotonin.ConclusionsOur study establishes that pancreatic β-cells communicate with vagal sensory neurons, likely using serotonin signaling as a transduction mechanism. Serotonin is coreleased with insulin and may therefore convey information about the secretory state of β-cells via vagal afferent nerves.
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Project description:Energy homeostasis requires precise measurement of the quantity and quality of ingested food. The vagus nerve innervates the gut and can detect diverse interoceptive cues, but the identity of the key sensory neurons and corresponding signals that regulate food intake remains unknown. Here, we use an approach for target-specific, single-cell RNA sequencing to generate a map of the vagal cell types that innervate the gastrointestinal tract. We show that unique molecular markers identify vagal neurons with distinct innervation patterns, sensory endings, and function. Surprisingly, we find that food intake is most sensitive to stimulation of mechanoreceptors in the intestine, whereas nutrient-activated mucosal afferents have no effect. Peripheral manipulations combined with central recordings reveal that intestinal mechanoreceptors, but not other cell types, potently and durably inhibit hunger-promoting AgRP neurons in the hypothalamus. These findings identify a key role for intestinal mechanoreceptors in the regulation of feeding.
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Project description:In rats and guinea pigs, sensory innervation of the airways is derived largely from the vagus nerve, with the extrapulmonary airways innervated by Wnt1+ jugular neurons and the intrapulmonary airways and lungs by Phox2b+ nodose neurons; however, our knowledge of airway innervation in mice is limited. We used genetically targeted expression of enhanced yellow fluorescent protein-channelrhodopsin-2 (EYFP-ChR2) in Wnt1+ or Phox2b+ tissues to characterize jugular and nodose-mediated physiological responses and airway innervation in mice. With optical stimulation, Phox2b+ vagal fibers modulated cardiorespiratory function in a frequency-dependent manner while right Wnt1+ vagal fibers induced a small increase in respiratory rate. Mouse tracheae contained sparse Phox2b-EYFP fibers but dense networks of Wnt1-EYFP fibers. Retrograde tracing from the airways showed limited tracheal innervation by the jugular sensory neurons, distinct from other species. These differences in physiology and vagal sensory distribution have important implications when using mice for studying airway neurobiology.
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Project description:Proliferation and differentiation of the pulmonary epithelium after injury is a critical process in the defense against the external environment. Defects in this response can result in airway remodeling, such as mucus cell metaplasia (MCM), commonly seen in patients with chronic lung disease. We have previously shown that amphiregulin (AREG), a ligand to the epidermal growth factor receptor (EGFR), is induced during the repair/differentiation process elicited by naphthalene-induced lung injury. Thus, we hypothesized that AREG signaling plays an important role in epithelial proliferation and differentiation of the repairing airway. Mice deficient in AREG and lung epithelial EGFR were used to define roles for AREG-dependent EGFR signaling in airway repair and remodeling. We show that AREG and epithelial EGFR expression is dispensable to pulmonary epithelial repair after naphthalene-induced lung injury, but regulates secretory cell differentiation to a mucus-producing phenotype. We show that the pulmonary epithelium is the source of AREG, suggesting that naphthalene-induced MCM is mediated through an autocrine signaling mechanism. However, induction of MCM resulting from allergen exposure was independent of AREG. Our data demonstrate that AREG-dependent EGFR signaling in airway epithelial cells contributes to MCM in naphthalene-induced lung injury. We conclude that AREG may represent a determinant of nonallergic chronic lung diseases complicated by MCM.
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Project description:Sensory functions of the vagus nerve are critical for conscious perceptions and for monitoring visceral functions in the cardio-pulmonary and gastrointestinal systems. Here, we present a comprehensive identification, classification, and validation of the neuron types in the neural crest (jugular) and placode (nodose) derived vagal ganglia by single-cell RNA sequencing (scRNA-seq) transcriptomic analysis. Our results reveal major differences between neurons derived from different embryonic origins. Jugular neurons exhibit fundamental similarities to the somatosensory spinal neurons, including major types, such as C-low threshold mechanoreceptors (C-LTMRs), A-LTMRs, Aδ-nociceptors, and cold-, and mechano-heat C-nociceptors. In contrast, the nodose ganglion contains 18 distinct types dedicated to surveying the physiological state of the internal body. Our results reveal a vast diversity of vagal neuron types, including many previously unanticipated types, as well as proposed types that are consistent with chemoreceptors, nutrient detectors, baroreceptors, and stretch and volume mechanoreceptors of the respiratory, gastrointestinal, and cardiovascular systems.
| S-EPMC6533201 | biostudies-literature
Project description:Visceral sensory pathways mediate homeostatic reflexes, the dysfunction of which leads to many neurological disorders1. The Bezold-Jarisch reflex (BJR), first described2,3 in 1867, is a cardioinhibitory reflex that is speculated to be mediated by vagal sensory neurons (VSNs) that also triggers syncope. However, the molecular identity, anatomical organization, physiological characteristics and behavioural influence of cardiac VSNs remain mostly unknown. Here we leveraged single-cell RNA-sequencing data and HYBRiD tissue clearing4 to show that VSNs that express neuropeptide Y receptor Y2 (NPY2R) predominately connect the heart ventricular wall to the area postrema. Optogenetic activation of NPY2R VSNs elicits the classic triad of BJR responses-hypotension, bradycardia and suppressed respiration-and causes an animal to faint. Photostimulation during high-resolution echocardiography and laser Doppler flowmetry with behavioural observation revealed a range of phenotypes reflected in clinical syncope, including reduced cardiac output, cerebral hypoperfusion, pupil dilation and eye-roll. Large-scale Neuropixels brain recordings and machine-learning-based modelling showed that this manipulation causes the suppression of activity across a large distributed neuronal population that is not explained by changes in spontaneous behavioural movements. Additionally, bidirectional manipulation of the periventricular zone had a push-pull effect, with inhibition leading to longer syncope periods and activation inducing arousal. Finally, ablating NPY2R VSNs specifically abolished the BJR. Combined, these results demonstrate a genetically defined cardiac reflex that recapitulates characteristics of human syncope at physiological, behavioural and neural network levels.
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Project description:Background & aimsAcute and chronic gastric injury induces alterations in differentiation within the corpus of the stomach called pyloric metaplasia. Pyloric metaplasia is characterized by the death of parietal cells and reprogramming of mitotically quiescent zymogenic chief cells into proliferative, mucin-rich spasmolytic polypeptide-expressing metaplasia (SPEM) cells. Overall, pyloric metaplastic units show increased proliferation and specific expansion of mucous lineages, both by proliferation of normal mucous neck cells and recruitment of SPEM cells. Here, we identify Sox9 as a potential gene of interest in the regulation of mucous neck and SPEM cell identity in the stomach.MethodsWe used immunostaining and electron microscopy to characterize the expression pattern of SRY-box transcription factor 9 (SOX9) during murine gastric development, homeostasis, and injury in homeostasis, after genetic deletion of Sox9 and after targeted genetic misexpression of Sox9 in the gastric epithelium and chief cells.ResultsSOX9 is expressed in all early gastric progenitors and strongly expressed in mature mucous neck cells with minor expression in the other principal gastric lineages during adult homeostasis. After injury, strong SOX9 expression was induced in the neck and base of corpus units in SPEM cells. Adult corpus units derived from Sox9-deficient gastric progenitors lacked normal mucous neck cells. Misexpression of Sox9 during postnatal development and adult homeostasis expanded mucous gene expression throughout corpus units including within the chief cell zone in the base. Sox9 deletion specifically in chief cells blunts their reprogramming into SPEM.ConclusionsSox9 is a master regulator of mucous neck cell differentiation during gastric development. Sox9 also is required for chief cells to fully reprogram into SPEM after injury.
| S-EPMC10444955 | biostudies-literature
Project description:RationaleAirway mucous cell metaplasia and chronic inflammation are pathophysiological features that influence morbidity and mortality associated with asthma and other chronic pulmonary disorders. Elucidation of the molecular mechanisms regulating mucous metaplasia and hypersecretion provides the scientific basis for diagnostic and therapeutic opportunities to improve the care of chronic pulmonary diseases.ObjectivesTo determine the role of the airway epithelial–specific transcription factor NK2 homeobox 1 (NKX2-1, also known as thyroid transcription factor-1 [TTF-1]) in mucous cell metaplasia and lung inflammation.MethodsExpression of NKX2-1 in airway epithelial cells from patients with asthma was analyzed. NKX2-1 +/-gene targeted or transgenic mice expressing NKX2-1 in conducting airway epithelial cells were sensitized to the aeroallergen ovalbumin. In vitro studies were used to identify mechanisms by which NKX2-1 regulates mucous cell metaplasia and inflammation.Measurements and main resultsNKX2-1 was suppressed in airway epithelial cells from patients with asthma. Reduced expression of NKX2-1 in heterozygous NKX2-1 +/- gene targeted mice increased mucous metaplasia in the small airways after pulmonary sensitization to ovalbumin. Conversely, mucous cell metaplasia induced by aeroallergen was inhibited by expression of NKX2-1 in the respiratory epithelium in vivo. Genome-wide mRNA analysis of lung tissue from ovalbumin-treated mice demonstrated that NKX2-1 inhibited mRNAs associated with mucous metaplasia and Th2-regulated inflammation,including Spdef, Ccl17, and Il13. In vitro, NKX2-1 inhibited SPDEF, a critical regulator of airway mucous cell metaplasia,and the Th2 chemokine CCL26.ConclusionsThe present data demonstrate a novel function for NKX2-1 in a gene network regulating mucous cell metaplasia and allergic inflammation in the respiratory epithelium.
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Project description:Epithelial hyperplasia and metaplasia are common features of inflammatory and neoplastic disease, but the basis for the altered epithelial phenotype is often uncertain. Here we show that long-term ciliated cell hyperplasia coincides with mucous (goblet) cell metaplasia after respiratory viral clearance in mouse airways. This chronic switch in epithelial behavior exhibits genetic susceptibility and depends on persistent activation of EGFR signaling to PI3K that prevents apoptosis of ciliated cells and on IL-13 signaling that promotes transdifferentiation of ciliated to goblet cells. Thus, EGFR blockade (using an irreversible EGFR kinase inhibitor designated EKB-569) prevents virus-induced increases in ciliated and goblet cells whereas IL-13 blockade (using s-IL-13Ralpha2-Fc) exacerbates ciliated cell hyperplasia but still inhibits goblet cell metaplasia. The distinct effects of EGFR and IL-13 inhibitors after viral reprogramming suggest that these combined therapeutic strategies may also correct epithelial architecture in the setting of airway inflammatory disorders characterized by a similar pattern of chronic EGFR activation, IL-13 expression, and ciliated-to-goblet cell metaplasia.
| S-EPMC1359039 | biostudies-literature
Project description:Asthma, accompanied by lung inflammation, bronchoconstriction and airway hyper-responsiveness, is a significant public health burden. Here we report that Mas-related G protein-coupled receptors (Mrgprs) are expressed in a subset of vagal sensory neurons innervating the airway and mediates cholinergic bronchoconstriction and airway hyper-responsiveness. These findings provide insights into the neural mechanisms underlying the pathogenesis of asthma.
| S-EPMC5857222 | biostudies-literature