-
Nature Medicine Jan 2017The enteric nervous system (ENS) of the gastrointestinal tract controls many diverse functions, including motility and epithelial permeability. Perturbations in ENS...
The enteric nervous system (ENS) of the gastrointestinal tract controls many diverse functions, including motility and epithelial permeability. Perturbations in ENS development or function are common, yet there is no human model for studying ENS-intestinal biology and disease. We used a tissue-engineering approach with embryonic and induced pluripotent stem cells (PSCs) to generate human intestinal tissue containing a functional ENS. We recapitulated normal intestinal ENS development by combining human-PSC-derived neural crest cells (NCCs) and developing human intestinal organoids (HIOs). NCCs recombined with HIOs in vitro migrated into the mesenchyme, differentiated into neurons and glial cells and showed neuronal activity, as measured by rhythmic waves of calcium transients. ENS-containing HIOs grown in vivo formed neuroglial structures similar to a myenteric and submucosal plexus, had functional interstitial cells of Cajal and had an electromechanical coupling that regulated waves of propagating contraction. Finally, we used this system to investigate the cellular and molecular basis for Hirschsprung's disease caused by a mutation in the gene PHOX2B. This is, to the best of our knowledge, the first demonstration of human-PSC-derived intestinal tissue with a functional ENS and how this system can be used to study motility disorders of the human gastrointestinal tract.
Topics: Animals; Calcium; Cell Line; Chick Embryo; Enteric Nervous System; Gastrointestinal Motility; Hirschsprung Disease; Homeodomain Proteins; Humans; Immunohistochemistry; In Vitro Techniques; Induced Pluripotent Stem Cells; Interstitial Cells of Cajal; Intestines; Mice; Mice, SCID; Microscopy, Confocal; Models, Biological; Mutation; Myenteric Plexus; Neural Crest; Neurogenesis; Neuroglia; Neurons; Organoids; Permeability; Real-Time Polymerase Chain Reaction; Submucous Plexus; Tissue Engineering; Transcription Factors
PubMed: 27869805
DOI: 10.1038/nm.4233 -
Gut Jul 2021Intestinal resident macrophages are at the front line of host defence at the mucosal barrier within the gastrointestinal tract and have long been known to play a crucial... (Review)
Review
Intestinal resident macrophages are at the front line of host defence at the mucosal barrier within the gastrointestinal tract and have long been known to play a crucial role in the response to food antigens and bacteria that are able to penetrate the mucosal barrier. However, recent advances in single-cell RNA sequencing technology have revealed that resident macrophages throughout the gut are functionally specialised to carry out specific roles in the niche they occupy, leading to an unprecedented understanding of the heterogeneity and potential biological functions of these cells. This review aims to integrate these novel findings with long-standing knowledge, to provide an updated overview on our understanding of macrophage function in the gastrointestinal tract and to speculate on the role of specialised subsets in the context of homoeostasis and disease.
Topics: Blood Vessels; Cellular Microenvironment; Humans; Intestinal Mucosa; Intestines; Macrophages; Muscle, Smooth; Neurons; Peyer's Patches; Phagocytosis; Submucous Plexus
PubMed: 33384336
DOI: 10.1136/gutjnl-2020-323121 -
PloS One 2015In the porcine colon, the submucous plexus is divided into an inner submucous plexus (ISP) on the epithelial side and an outer submucous plexus (OSP) on the circular... (Comparative Study)
Comparative Study
In the porcine colon, the submucous plexus is divided into an inner submucous plexus (ISP) on the epithelial side and an outer submucous plexus (OSP) on the circular muscle side. Although both plexuses are probably involved in the regulation of epithelial functions, they might differ in function and neurochemical coding according to their localization. Therefore, we examined expression and co-localization of different neurotransmitters and neuronal markers in both plexuses as well as in neuronal fibres. Immunohistochemical staining was performed on wholemount preparations of ISP and OSP and on cryostat sections. Antibodies against choline acetyltransferase (ChAT), substance P (SP), somatostatin (SOM), neuropeptide Y (NPY), vasoactive intestinal peptide (VIP), neuronal nitric oxide synthase (nNOS) and the pan-neuronal markers Hu C/D and neuron specific enolase (NSE) were used. The ISP contained 1,380 ± 131 ganglia per cm2 and 122 ± 12 neurons per ganglion. In contrast, the OSP showed a wider meshwork (215 ± 33 ganglia per cm2) and smaller ganglia (57 ± 3 neurons per ganglion). In the ISP, 42% of all neurons expressed ChAT. About 66% of ChAT-positive neurons co-localized SP. A small number of ISP neurons expressed SOM. Chemical coding in the OSP was more complex. Besides the ChAT/±SP subpopulation (32% of all neurons), a nNOS-immunoreactive population (31%) was detected. Most nitrergic neurons were only immunoreactive for nNOS; 10% co-localized with VIP. A small subpopulation of OSP neurons was immunoreactive for ChAT/nNOS/±VIP. All types of neurotransmitters found in the ISP or OSP were also detected in neuronal fibres within the mucosa. We suppose that the cholinergic population in the ISP is involved in the control of epithelial functions. Regarding neurochemical coding, the OSP shares some similarities with the myenteric plexus. Because of its location and neurochemical characteristics, the OSP may be involved in controlling both the mucosa and circular muscle.
Topics: Animals; Choline O-Acetyltransferase; Colchicine; Colon; Female; Humans; Immunohistochemistry; Male; Neurons; Neuropeptide Y; Neurotransmitter Agents; Nitric Oxide Synthase Type I; Somatostatin; Species Specificity; Submucous Plexus; Substance P; Sus scrofa; Vasoactive Intestinal Peptide
PubMed: 26230272
DOI: 10.1371/journal.pone.0133350 -
Anatomical Record (Hoboken, N.J. : 2007) Aug 2019The enteric nervous system (ENS) controls gastrointestinal key functions and is mainly characterized by two ganglionated plexus located in the gut wall: the myenteric... (Review)
Review
The enteric nervous system (ENS) controls gastrointestinal key functions and is mainly characterized by two ganglionated plexus located in the gut wall: the myenteric plexus and the submucous plexus. The ENS harbors a high number and diversity of enteric neurons and glial cells, which generate neuronal circuitry to regulate intestinal physiology. In the past few years, the pivotal role of enteric neurons in the underlying mechanism of several intestinal diseases was revealed. Intestinal diseases are associated with neuronal death that could in turn compromise intestinal functionality. Enteric neurogenesis and regeneration is therefore a crucial aspect within the ENS and could be revealed not only during embryogenesis and early postnatal periods, but also in the adulthood. Enteric glia and/or enteric neural precursor/progenitor cells differentiate into enteric neurons, both under homeostatic and pathologic conditions beyond the perinatal period. The unique role of the intestinal microbiota and serotonin signaling in postnatal and adult neurogenesis has been shown by several studies in health and disease. In this review article, we will mainly focus on different recent studies, which advanced the concept of postnatal and adult ENS neurogenesis. Moreover, we will discuss the key factors and underlying mechanisms, which promote enteric neurogenesis. Finally, we will shortly describe neurogenesis of transplanted enteric neural progenitor cells. Anat Rec, 302:1345-1353, 2019. © 2019 Wiley Periodicals, Inc.
Topics: Animals; Enteric Nervous System; Gastrointestinal Microbiome; Humans; Longevity; Neurodegenerative Diseases; Neurogenesis; Serotonin; Signal Transduction
PubMed: 30950581
DOI: 10.1002/ar.24124 -
Gastroenterology Apr 2013Close association between nerves and mast cells in the gut wall provides the microanatomic basis for functional interactions between these elements, supporting the... (Review)
Review
Close association between nerves and mast cells in the gut wall provides the microanatomic basis for functional interactions between these elements, supporting the hypothesis that a mast cell-nerve axis influences gut functions in health and disease. Advanced morphology and imaging techniques are now available to assess structural and functional relationships of the mast cell-nerve axis in human gut tissues. Morphologic techniques including co-labeling of mast cells and nerves serve to evaluate changes in their densities and anatomic proximity. Calcium (Ca(++)) and potentiometric dye imaging provide novel insights into functions such as mast cell-nerve signaling in the human gut tissues. Such imaging promises to reveal new ionic or molecular targets to normalize nerve sensitization induced by mast cell hyperactivity or mast cell sensitization by neurogenic inflammatory pathways. These targets include proteinase-activated receptor (PAR) 1 or histamine receptors. In patients, optical imaging in the gut in vivo has the potential to identify neural structures and inflammation in vivo. The latter has some risks and potential of sampling error with a single biopsy. Techniques that image nerve fibers in the retina without the need for contrast agents (optical coherence tomography and full-field optical coherence microscopy) may be applied to study submucous neural plexus. Moreover, the combination of submucosal dissection, use of a fluorescent marker, and endoscopic confocal microscopy provides detailed imaging of myenteric neurons and smooth muscle cells in the muscularis propria. Studies of motility and functional gastrointestinal disorders would be feasible without the need for full-thickness biopsy.
Topics: Cell Communication; Diagnostic Imaging; Female; Gastrointestinal Tract; Humans; Male; Mast Cells; Microscopy, Confocal; Nerve Fibers; Submucous Plexus; Tomography, X-Ray Computed
PubMed: 23354018
DOI: 10.1053/j.gastro.2013.01.040 -
STAR Protocols Mar 2022The myenteric plexus is located between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract. It contains a large network of enteric...
The myenteric plexus is located between the longitudinal and circular layers of muscularis externa in the gastrointestinal tract. It contains a large network of enteric neurons that form the enteric nervous system (ENS) and control intestinal functions, such as motility and nutrient sensing. This protocol describes the method for physical separation (peeling) of muscularis and submucosal layers of the mouse intestine. Subsequently, the intestinal layers are then processed for flow cytometry and/or immunofluorescence analysis. For complete details on the use and execution of this profile, please refer to Ahrends et al. (2021).
Topics: Animals; Flow Cytometry; Fluorescent Antibody Technique; Gastrointestinal Tract; Mice; Mice, Inbred C57BL; Myenteric Plexus; Submucous Plexus
PubMed: 35146454
DOI: 10.1016/j.xpro.2022.101157 -
Physiological Reports Feb 2021Obesity is associated with the development of insulin resistance (IR) and type-2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The... (Comparative Study)
Comparative Study
BACKGROUND
Obesity is associated with the development of insulin resistance (IR) and type-2 diabetes mellitus (T2DM); however, not all patients with T2DM are obese. The Goto-Kakizaki (GK) rat is an experimental model of spontaneous and non-obese T2DM. There is evidence that the intestine contributes to IR development in GK animals. This information prompted us to investigate small intestine remodeling in this animal model.
METHODS
Four-month-old male Wistar (control) and GK rats were utilized for the present study. After removing the small intestine, the duodenum, proximal jejunum, and distal ileum were separated. We then measured villi and muscular and mucosa layer histomorphometry, goblet cells abundance, total myenteric and submucosal neuron populations, and inflammatory marker expression in the small intestinal segments and intestinal transit of both groups of animals.
KEY RESULTS
We found that the GK rats exhibited decreased intestinal area (p < 0.0001), decreased crypt depth in the duodenum (p = 0.01) and ileum (p < 0.0001), increased crypt depth in the jejunum (p < 0.0001), longer villi in the jejunum and ileum (p < 0.0001), thicker villi in the duodenum (p < 0.01) and ileum (p < 0.0001), thicker muscular layers in the duodenum, jejunum, and ileum (p < 0.0001), increased IL-1β concentrations in the duodenum and jejunum (p < 0.05), and increased concentrations of NF-κB p65 in the duodenum (p < 0.01), jejunum and ileum (p < 0.05). We observed high IL-1β reactivity in the muscle layer, myenteric neurons, and glial cells of the experimental group. GK rats also exhibited a significant reduction in submucosal neuron density in the jejunum and ileum, ganglionic hypertrophy in all intestinal segments studied (p < 0.0001), and a slower intestinal transit (about 25%) compared to controls.
CONCLUSIONS
The development of IR and T2DM in GK rats is associated with small intestine remodeling that includes marked alterations in small intestine morphology, local inflammation, and reduced intestinal transit.
Topics: Animals; Blood Glucose; Cytokines; Diabetes Mellitus, Type 2; Disease Models, Animal; Duodenum; Gastrointestinal Transit; Ileum; Inflammation Mediators; Insulin Resistance; Intestine, Small; Jejunum; Male; Myenteric Plexus; Rats, Wistar; Submucous Plexus; Rats
PubMed: 33580916
DOI: 10.14814/phy2.14755 -
American Journal of Physiology.... Jan 2017We discuss the role of multiple cell types involved in rhythmic motor patterns in the large intestine that include tonic inhibition of the muscle layers interrupted by... (Review)
Review
We discuss the role of multiple cell types involved in rhythmic motor patterns in the large intestine that include tonic inhibition of the muscle layers interrupted by rhythmic colonic migrating motor complexes (CMMCs) and secretomotor activity. We propose a model that assumes these motor patterns are dependent on myenteric descending 5-hydroxytryptamine (5-HT, serotonin) interneurons. Asynchronous firing in 5-HT neurons excite inhibitory motor neurons (IMNs) to generate tonic inhibition occurring between CMMCs. IMNs release mainly nitric oxide (NO) to inhibit the muscle, intrinsic primary afferent neurons (IPANs), glial cells, and pacemaker myenteric pacemaker interstitial cells of Cajal (ICC-MY). Mucosal release of 5-HT from enterochromaffin (EC) cells excites the mucosal endings of IPANs that synapse with 5-HT descending interneurons and perhaps ascending interneurons, thereby coupling EC cell 5-HT to myenteric 5-HT neurons, synchronizing their activity. Synchronized 5-HT neurons generate a slow excitatory postsynaptic potential in IPANs via 5-HT receptors and excite glial cells and ascending excitatory nerve pathways that are normally inhibited by NO. Excited glial cells release prostaglandins to inhibit IMNs (disinhibition) to allow full excitation of ICC-MY and muscle by excitatory motor neurons (EMNs). EMNs release ACh and tachykinins to excite pacemaker ICC-MY and muscle, leading to the simultaneous contraction of both the longitudinal and circular muscle layers. Myenteric 5-HT neurons also project to the submucous plexus to couple motility with secretion, especially during a CMMC. Glial cells are necessary for switching between different colonic motor behaviors. This model emphasizes the importance of myenteric 5-HT neurons and the likely consequence of their coupling and uncoupling to mucosal 5-HT by IPANs during colonic motor behaviors.
Topics: Action Potentials; Animals; Colon; Enteric Nervous System; Interstitial Cells of Cajal; Models, Neurological; Nerve Net; Serotonergic Neurons; Serotonin
PubMed: 27789457
DOI: 10.1152/ajpgi.00337.2016 -
The Anatomical Record Jan 2001The architecture of the enteric nerve networks in the gastrointestinal tract appears to be more complex in large mammals, including humans, than in small laboratory... (Review)
Review
The architecture of the enteric nerve networks in the gastrointestinal tract appears to be more complex in large mammals, including humans, than in small laboratory animals. At least two distinct ganglionic nerve plexuses could be identified in the submucous layer in the digestive tract of large mammals. While functionally and morphologically similar neuron populations are found in the intestinal wall of both small and large mammals, significant differences in their topographical organization and neurochemical features may be present. This short review clearly illustrates that the close and exclusive association, which has been assumed so far between the efferent pathways of the submucous plexus and regulation of intestinal secretion/absorption on the one hand and between the myenteric plexus and regulation of intestinal motility on the other hand, cannot be interpreted that strictly. An attempt has been made to give a briefoverview of the current status of the identification of distinct functional enteric neuronal classes in the gastrointestinal tract of large mammals using the pig and human intestine as references, and to compare these data with the more extensive information gathered from the guinea-pig intestine.
Topics: Animals; Gastrointestinal Motility; Humans; Infant, Newborn; Intestine, Small; Nerve Net; Neural Pathways; Neurons; Species Specificity; Submucous Plexus; Swine
PubMed: 11146430
DOI: 10.1002/1097-0185(20010101)262:1<71::AID-AR1012>3.0.CO;2-A -
World Journal of Gastroenterology Dec 2021The enteric nervous system (ENS) consists of thousands of small ganglia arranged in the submucosal and myenteric plexuses, which can be negatively affected by Crohn's... (Review)
Review
The enteric nervous system (ENS) consists of thousands of small ganglia arranged in the submucosal and myenteric plexuses, which can be negatively affected by Crohn's disease and ulcerative colitis - inflammatory bowel diseases (IBDs). IBDs are complex and multifactorial disorders characterized by chronic and recurrent inflammation of the intestine, and the symptoms of IBDs may include abdominal pain, diarrhea, rectal bleeding, and weight loss. The P2X7 receptor has become a promising therapeutic target for IBDs, especially owing to its wide expression and, in the case of other purinergic receptors, in both human and model animal enteric cells. However, little is known about the actual involvement between the activation of the P2X7 receptor and the cascade of subsequent events and how all these activities associated with chemical signals interfere with the functionality of the affected or treated intestine. In this review, an integrated view is provided, correlating the structural organization of the ENS and the effects of IBDs, focusing on cellular constituents and how therapeutic approaches through the P2X7 receptor can assist in both protection from damage and tissue preservation.
Topics: Animals; Colitis, Ulcerative; Enteric Nervous System; Humans; Inflammatory Bowel Diseases; Receptors, Purinergic P2X7; Submucous Plexus
PubMed: 35046620
DOI: 10.3748/wjg.v27.i46.7909