Project description:The ability to generate visceral sensory neurons (VSN) from induced pluripotent stem (iPS) cells may help to gain insights into how the gut-nerve-brain axis is involved in neurological disorders. We established a protocol to differentiate human iPS-cell-derived visceral sensory ganglion organoids (VSGOs). VSGOs exhibit canonical VSN markers, and single-cell RNA sequencing revealed heterogenous molecular signatures and developmental trajectories of VSGOs aligned with native VSN. We integrated VSGOs with human colon organoids on a microfluidic device and applied this axis-on-a-chip model to Alzheimer's disease. Our results suggest that VSN could be a potential mediator for propagating gut-derived amyloid and tau to the brain in an APOE4- and LRP1-dependent manner. Furthermore, our approach was extended to include patient-derived iPS cells, which demonstrated a strong correlation with clinical data.
Project description:The ability to generate visceral sensory neurons (VSN) from induced pluripotent stem (iPS) cells may help to gain insights into how the gut-nerve-brain axis is involved in neurological disorders. We established a protocol to differentiate human iPS-cell-derived visceral sensory ganglion organoids (VSGOs). VSGOs exhibit canonical VSN markers, and single-cell RNA sequencing revealed heterogenous molecular signatures and developmental trajectories of VSGOs aligned with native VSN. We integrated VSGOs with human colon organoids on a microfluidic device and applied this axis-on-a-chip model to Alzheimer's disease. Our results suggest that VSN could be a potential mediator for propagating gut-derived amyloid and tau to the brain in an APOE4- and LRP1-dependent manner. Furthermore, our approach was extended to include patient-derived iPS cells, which demonstrated a strong correlation with clinical data.
Project description:Visceral sensory neurons encode distinct sensations from healthy organs and initiate pain states that are resistant to common analgesics. Transcriptome analysis is transforming our understanding of sensory neuron subtypes but has generally focused on somatic sensory neurons or the total population of neurons in which visceral neurons form the minority. Our aim was to define transcripts specifically expressed by sacral visceral sensory neurons, as a step towards understanding the unique biology of these neurons and potentially lead to identification of new analgesic targets for pelvic visceral pain. Our strategy was to identify genes differentially expressed between sacral dorsal root ganglia (DRG) that include somatic neurons and sacral visceral neurons, and adjacent lumbar DRG that comprise exclusively somatic sensory neurons. This was performed in male and female mice (adult and E18.5). By developing a method to restrict analyses to nociceptive Trpv1 neurons, a larger group of genes were detected as differentially expressed between spinal level. We identified many novel genes not previously been associated with pelvic visceral sensation or nociception. Limited sex differences were detected across the transcriptome of sensory ganglia, but more were revealed in sacral levels and especially in Trpv1 nociceptive neurons. These data will facilitate development of new tools to modify mature and developing sensory neurons and nociceptive pathways.
Project description:Visceral sensory neurons encode distinct sensations from healthy organs and initiate pain states that are resistant to common analgesics. Transcriptome analysis is transforming our understanding of sensory neuron subtypes but has generally focused on somatic sensory neurons or the total population of neurons in which visceral neurons form the minority. Our aim was to define transcripts specifically expressed by sacral visceral sensory neurons, as a step towards understanding the unique biology of these neurons and potentially lead to identification of new analgesic targets for pelvic visceral pain. Our strategy was to identify genes differentially expressed between sacral dorsal root ganglia (DRG) that include somatic neurons and sacral visceral neurons, and adjacent lumbar DRG that comprise exclusively somatic sensory neurons. This was performed in male and female mice (adult and E18.5). By developing a method to restrict analyses to nociceptive Trpv1 neurons, a larger group of genes were detected as differentially expressed between spinal level. We identified many novel genes not previously been associated with pelvic visceral sensation or nociception. Limited sex differences were detected across the transcriptome of sensory ganglia, but more were revealed in sacral levels and especially in Trpv1 nociceptive neurons. These data will facilitate development of new tools to modify mature and developing sensory neurons and nociceptive pathways.
Project description:Visceral sensory neurons encode distinct sensations from healthy organs and initiate pain states that are resistant to common analgesics. Transcriptome analysis is transforming our understanding of sensory neuron subtypes but has generally focused on somatic sensory neurons or the total population of neurons in which visceral neurons form the minority. Our aim was to define transcripts specifically expressed by sacral visceral sensory neurons, as a step towards understanding the unique biology of these neurons and potentially lead to identification of new analgesic targets for pelvic visceral pain. Our strategy was to identify genes differentially expressed between sacral dorsal root ganglia (DRG) that include somatic neurons and sacral visceral neurons, and adjacent lumbar DRG that comprise exclusively somatic sensory neurons. This was performed in male and female mice (adult and E18.5). By developing a method to restrict analyses to nociceptive Trpv1 neurons, a larger group of genes were detected as differentially expressed between spinal level. We identified many novel genes not previously been associated with pelvic visceral sensation or nociception. Limited sex differences were detected across the transcriptome of sensory ganglia, but more were revealed in sacral levels and especially in Trpv1 nociceptive neurons. These data will facilitate development of new tools to modify mature and developing sensory neurons and nociceptive pathways.
Project description:Integration of nutritional, microbial and inflammatory events along the gut-brain axis can alter bowel physiology and organism behaviour. The principal neural unit in the bowel encoding these stimuli is the visceral sensory neuron with endings at the mucosa, intramurally and along mesenteric blood vessels. Sensory neurons activate reflex pathways and give rise to conscious sensation, however, the diversity and division of function within these neurons is poorly understood. The identification of signalling pathways contributing to visceral sensation is constrained by the current paucity of molecular markers. Here we overcome these limitations by comprehensive transcriptomic profiling and unsupervised clustering of single colonic sensory neurons revealing 7 classes characterised from both lumbar splanchnic (LSN) and pelvic nerves (PN). We identify and classify neurons based on novel marker genes, confirm translation of patterning to protein expression and show subtype-selective differential agonist activation, describing sensory diversity encompassing all modalities of colonic neuronal sensitivity.
Project description:Background & Aims: Visceral hypersensitivity, a hallmark of irritable bowel syndrome, is generally considered to be mechanosensitive in nature and mediated via spinal afferents. Both stress and inflammation are implicated in visceral hypersensitivity, but the underlying molecular mechanisms of visceral hypersensitivity are unknown. <br> Methods: Mice were infected with Nippostrongylus brasiliensis (Nb) larvae, exposed to environmental stress and the following separate studies performed 3-4 weeks later. Mesenteric afferent nerve activity was recorded in response to either ramp balloon distension (60 mmHg), or to an intraluminal perfusion of hydrochloric acid (50 mM), or to octreotide administration (2 µM). Intraperitoneal injection of cholera toxin B-488 identified neurons projecting to the abdominal viscera. Fluorescent neurons in dorsal root and nodose ganglia were isolated using laser-capture microdissection. RNA was hybridised to Affymetrix Mouse whole genome arrays for analysis to evaluate the effects of stress and infection. <br> Results: In mice previously infected with Nb, there was no change in intestinal afferent mechanosensitivity, but there was an increase in chemosensitive responses to intraluminal hydrochloric acid when compared to control animals. Gene expression profiles in vagal but not spinal visceral sensory neurons were significantly altered in stressed Nb-infected mice. Decreased afferent responses to somatostatin receptor 2 stimulation correlated with lower expression of vagal somatostatin receptor 2 in stressed Nb-infected mice, confirming a link between molecular data and functional sequelae. <br> Conclusions: Alterations in the intestinal brain-gut axis, in chemosensitivity but not mechanosensitivity, and through vagal rather than spinal pathways, are implicated in stress-induced post-inflammatory visceral hypersensitivity.
Project description:Sensory neurons of the dorsal root ganglion (DRG) play a crucial role in maintaining tissue homeostasis by sensing and initiating responses to stimuli. While most preclinical studies of DRGs are conducted in rodents, much less is known about the mechanisms of sensory perception in primates. We generated a transcriptome atlas for mouse, guinea pig, cynomolgus monkey, and human DRGs using a framework that implements a common laboratory workflow (i.e sequencing technologies, laboratory protocols, and sample archival methods) and multiple data-integration approaches to generate accurate cross-species mappings of sensory neuron subtypes.
Project description:Sensory neurons of the dorsal root ganglion (DRG) play a crucial role in maintaining tissue homeostasis by sensing and initiating responses to stimuli. While most preclinical studies of DRGs are conducted in rodents, much less is known about the mechanisms of sensory perception in primates. We generated a transcriptome atlas for mouse, guinea pig, cynomolgus monkey, and human DRGs using a framework that implements a common laboratory workflow (i.e sequencing technologies, laboratory protocols, and sample archival methods) and multiple data-integration approaches to generate accurate cross-species mappings of sensory neuron subtypes.