The enteric nervous system in gastrointestinal disease etiology

From blockage to biology: Unveiling the role of extracellular matrix dynamics in obstructive colorectal cancer pathogenesis

Colorectal cancer obstruction is a common problem with distinct symptomatic clues on CT/MR images even under incomplete conditions. The choice of management in the emergency setting has a significant effect on the prognosis of obstructive and nonobstructive colorectal cancer patients. Previous studies have demonstrated that obstruction in colorectal cancer is associated with significantly poorer outcomes, alongside distinct alterations in the composition of the extracellular matrix. Based on accumulating evidence, it is hypothesized that ECM remodeling plays a pivotal role in the development of colorectal cancer obstruction. This review explores the pathological features of obstructive colorectal cancer, emphasizing extracellular matrix remodeling as a central process. Key mechanisms include tumor-stromal cell interactions, tumor cell aggregation and migration mediated by the peripheral nervous system, vascular and lymphatic remodeling within the tumor microenvironment, and microbiota-mediated regulation of cancer progression. These findings demonstrate that further remodeling of the extracellular matrix may be a molecular biological feature of obstructive colorectal cancer with poor prognosis.

Gut-brain connection in schizophrenia: A narrative review

Schizophrenia is a complex neuropsychiatric disorder characterized by cognitive, emotional, and behavioral impairments. The microbiota-gut-brain axis is crucial in its pathophysiology, mediating communication between the gut and brain through neural, immune, endocrine, and metabolic pathways. Dysbiosis, or an imbalance in gut microbiota, is linked to neuroinflammation, systemic inflammation, and neurotransmitter disruptions, all of which contribute to the symptoms of schizophrenia. Gut microbiota-derived metabolites, such as short-chain fatty acids, influence brain function, including immune responses and neurotransmitter synthesis. These findings suggest that microbial imbalances exacerbate schizophrenia, providing a novel perspective on the disorder’s underlying mechanisms. Emerging microbiota-targeted therapies—such as probiotics, prebiotics, dietary interventions, and fecal microbiota transplantation—show promise as adjunctive treatments, aiming to restore microbial balance and improve clinical outcomes. While further research is needed, targeting the microbiota-gut-brain axis offers an innovative approach to schizophrenia management, with the potential to enhance patient outcomes and quality of life.

Flow Cytometric Analysis and Sorting of Murine Enteric Nervous System Cells: An Optimized Protocol

Isolation of neurons and glia from the enteric nervous system (ENS) enables ex vivo studies, including the analysis of genomic and transcriptomic profiles. While we previously reported a fluorescence-activated cell sorting (FACS)-based isolation protocol for human ENS cells, no equivalent exists for mice. As directly applying the human protocol to mouse tissue resulted in low recovery of live ENS cells, we optimized tissue dissociation using mouse colons. A 30 min Liberase-based digestion showed optimal recovery of viable ENS cells, with CD56 and CD24 emerging as the most reliable markers to select and subdivide these cells. ENS' identity was further validated by FACS, using neuronal (TUBB3) and glial (SOX10) markers and reverse transcriptase quantitative PCR on sorted fractions. Overall, the mouse ENS expression profile significantly overlapped with the human one, showing that current dissociation protocols yield a mixed population of enteric neurons and glia. Nonetheless, using the imaging flow cytometer BD S8 FACS Discover and ELAVL4 as a neuronal soma-associated marker, we observed enrichment of neurons in a CD56/CD24TIP population. In conclusion, we present here a protocol for high-purity FACS-based isolation of viable mouse ENS cells, suitable for downstream applications.

Interaction between nutritional factors and the enteric nervous system in inflammatory bowel diseases

The enteric nervous system (ENS) is a highly conserved, yet complicated network of neurons and glial cells located throughout the gut wall that controls digestive processes and gastrointestinal (GI) homeostasis. The intestinal epithelium, the immune system, and the gut microbiota are just a few examples of the cellular networks that the ENS interacts with on a variety of levels to maintain GI function. The presence or absence of nutrients in the intestinal lumen may cause short- and/or long-term changes in neurotransmitter expression, excitability, and neuronal survival, which ultimately affect gut motility, secretion, and permeability. Hence, the ENS should be identified as a key factor in initiating coordinated responses to nutrients. In this review we summarize current knowledge on nutrient-dependent ENS activity and how ENS secondary to nutrition may affect likelihood of developing inflammatory bowel disease. Our findings highlight that nutrients interact with enteroendocrine cells in the gut, triggering hormone secretion that plays a crucial role in signaling food-related information to the brain and regulating metabolic processes such as feeding behavior, insulin secretion, and energy balance; however, the complex interactions between nutrients, the ENS, and the immune system require further research to understand their contributions to GI disorders and potential therapeutic applications in treating obesity and metabolic diseases. Lay Summary: The enteric nervous system (ENS) controls digestion and interacts with nutrients in the gut to regulate processes like gut movement and hormone release, affecting metabolism and overall gut health. This review highlights the need for further research on how nutrient-ENS interactions contribute to conditions like inflammatory bowel disease, obesity, and metabolic disorders.

Microbiota dysbiosis impact on the immune system dysregulation in Huntington's disease (HD)

Huntington's disease (HD) is a neurodegenerative disorder characterized by motor, cognitive, and psychiatric impairments caused by Huntingtin (HTT) gene mutations, resulting in the mutant huntingtin (mHTT) protein. Both innate and adaptive immunities play crucial roles in the pathogenesis of HD. In this chapter, we explore the vital role of the gut microbiota in HD, emphasizing its impact on the immune response and brain health via the gut-brain axis. Dysbiosis influences immune responses and HD pathogenesis through microbial metabolites such as short-chain fatty acids (SCFAs) and pathogen-associated molecular patterns (PAMPs). We discuss advanced mathematical models, telemedicine, and biosensors for tracking HD progression and detecting gut dysbiosis. Nutritional interventions to restore microbiota balance and using artificial intelligence and machine learning to predict disease prognosis and personalized treatments have been highlighted. Based on their unique immune profiles and gut microbiota, personalized medicine has been proposed as a promising strategy for effective HD treatment.

Study on the Effect and Mechanism of Weichang'an Pill and Its Extract on Slow Transit Constipation

BACKGROUND

Weichang'an pill (WCA) possesses potential advantages in promoting gastrointestinal motility and treating constipation. Ethanol extract (EE) and aqueous extract (AE) of WCA were used to investigate its efficacy in treating slow transit constipation (STC) and the material basis for exerting this effect.

METHODS

The STC model was established in vivo by gavage of loperamide (Lop) in Sprague-Dawley rats, followed by gavage of WCA, EE, and AE. In vitro, norepinephrine (NE) was used to stimulate isolated ileal smooth muscle of rats to imitate the state of insufficient gastrointestinal motility during STC, and a model of excessive relaxation of isolated ileal smooth muscle was established. This model was used to observe and record the changes in contraction tension, amplitude, and frequency of ileal smooth muscle after treatment with WCA, EE, AE, and the active ingredients of WCA.

KEY RESULTS

In vivo, WCA, EE, and AE treatment increased fecal parameters, improved gastrointestinal transit time, and alleviated pathological damage to the colon in STC rats. Its mechanism might be closely related to c-kit/SCF, RhoA/ROCK/MYPT1/MLC signaling pathways. In vitro, WCA, EE, AE, and the active ingredients of WCA, including costunolide (Cos), dehydrocostus lactone (Deh), agarotetrol (Aga), muscone (Mus), gallic acid (GA), oleic acid (Oleic), linoleic acid (Lin), umbelliferone (Umb), synephrine (Syn), ferulic acid (FA), chlorogenic acid (ChA), betaine (Bet), and riboflavin (Rib), significantly inhibited the NE-induced excessive relaxation of ileal smooth muscles.

CONCLUSIONS

WCA, EE, and AE significantly improved constipation in STC rats. Moreover, the active ingredients in WCA, including Cos, Deh, Aga, Mus, GA, Oleic, Lin, Umb, Syn, FA, ChA, Bet, and Rib, might be the material basis for promoting intestinal motility.

The Oral-Gut Microbiome-Brain Axis in Cognition

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline and neuronal loss, affecting millions worldwide. Emerging evidence highlights the oral microbiome-a complex ecosystem of bacteria, fungi, viruses, and protozoa as a significant factor in cognitive health. Dysbiosis of the oral microbiome contributes to systemic inflammation, disrupts the blood-brain barrier, and promotes neuroinflammation, processes increasingly implicated in the pathogenesis of AD. This review examines the mechanisms linking oral microbiome dysbiosis to cognitive decline through the oral-brain and oral-gut-brain axis. These interconnected pathways enable bidirectional communication between the oral cavity, gut, and brain via neural, immune, and endocrine signaling. Oral pathogens, such as Porphyromonas gingivalis, along with virulence factors, including lipopolysaccharides (LPS) and gingipains, contribute to neuroinflammation, while metabolic byproducts, such as short-chain fatty acids (SCFAs) and peptidoglycans, further exacerbate systemic immune activation. Additionally, this review explores the influence of external factors, including diet, pH balance, medication use, smoking, alcohol consumption, and oral hygiene, on oral microbial diversity and stability, highlighting their role in shaping cognitive outcomes. The dynamic interplay between the oral and gut microbiomes reinforces the importance of microbial homeostasis in preserving systemic and neurological health. The interventions, including probiotics, prebiotics, and dietary modifications, offer promising strategies to support cognitive function and reduce the risk of neurodegenerative diseases, such as AD, by maintaining a diverse microbiome. Future longitudinal research is needed to identify the long-term impact of oral microbiome dysbiosis on cognition.

Effect of Anti-TNF Monoclonal Antibody on Enteric Neurons and Enteric Glial Cells in Experimental Colitis

BACKGROUND

Inflammatory bowel diseases (IBD) affect both enteric neurons and enteric glia, with tumor necrosis factor-alpha (TNF-α) playing a role as an inflammatory mediator.

AIMS

Analyze the effects of the anti-TNF monoclonal antibody on the myenteric plexus in an experimental model of colitis.

METHODS

C57BL/6 mice received 3% dextran sodium sulfate (DSS) in drinking water for 7 days in both the DSS and DSS + ADA groups. The Sham group received water. The DSS + ADA group received ADA anti-TNF-α on day 2 of DSS intake. The ADA group was given water throughout the period and received an anti-TNF-α injection on day 2. The study evaluated the number of neurons per ganglion, and the area of the neuronal nitric oxide synthase (nNOS), choline acetyltransferase (ChAT), pan-neuronal marker (PGP9.5), and tumor necrosis factor receptor 2 (TNFR2) immunoreactive (-ir). Double labeling of PGP9.5 with an enteric glial marker (GFAP) was also performed.

RESULTS

DSS successfully induced experimental colitis (EC). TNFR2 was detected in the myenteric neurons in all groups. EC affected the enteric neurons, showing a decrease in the number of TNFR2-ir, ChAT-ir, nNOS-ir, and PGP9.5-ir neurons, whereas enteric glial cells increased in both the DSS and DSS + ADA groups. The DSS + ADA group showed number of nNOS-ir, ChAT-ir, and PGP9.5-ir neurons per ganglion similar to Sham group. EC also affected the neuronal profile, resulting in smaller areas in the DSS and DSS + ADA groups.

CONCLUSION

Myenteric neurons are immunoreactive to the TNFR2. DSS altered the myenteric plexus, and anti-TNF monoclonal antibody treatment proved effective against EC due to preventing the pathology from developing.

Toll-like receptor 4 deficiency ameliorates experimental ileitis and enteric neuropathy: Involvement of nitrergic and 5-hydroxytryptaminergic neurotransmission

BACKGROUND AND PURPOSE

Inflammatory bowel disease (IBD) patients display genetic polymorphisms in toll-like receptor 4 (TLR4) genes, contributing to dysregulate enteric nervous system (ENS) circuits with increased levels of 5-HT and alteration of the neuroimmune crosstalk. In this study, we investigated the impact of TLR4 signalling on mouse ENS dysfunction caused by dextran sulphate sodium (DSS)-induced ileitis.

EXPERIMENTAL APPROACH

Male C57BL/6J (wild-type [WT]) and TLR4-/- mice (10 ± 2 weeks old) received 2% DSS in drinking water for 5 days and then were switched to 3-day regular drinking water. Histological analysis and proinflammatory cytokine mRNA levels were assessed in ileal samples. Gut motility was evaluated by changes in transit of a fluorescent-labelled marker and isometric neuromuscular responses of ileal full-thickness segments to receptor and non-receptor-mediated stimuli. Alterations in ENS architecture were assessed by confocal immunohistochemistry in longitudinal muscle-myenteric plexus whole-mount preparations.

KEY RESULTS

In WT mice, DSS treatment caused delayed gastrointestinal transit, ileal myenteric neurodegeneration, reactive gliosis and release of proinflammatory cytokines. Enhanced cholinergic and tachykinergic excitatory tone, increased inducible nitric oxide synthase (iNOS)-mediated relaxation, and changes in 5-HT2A and 5-HT3 receptor-mediated responses were observed during ileitis in WT mice. TLR4 deficiency reversed most of the functional and morphological abnormalities.

CONCLUSION AND IMPLICATIONS

Our results demonstrate that TLR4 activity influences the severity of ileitis, neuroglial plasticity, gut motility, and nitrergic and 5-HTergic neurotransmissions. The neuroimmune interaction between TLR4 and 5-HT observed in our study appears to be a potential pharmacological target to treat ENS dysfunction implicated in IBD onset/progression.

MicroRNA regulation of enteric nervous system development and disease

The enteric nervous system (ENS), an elaborate network of neurons and glia woven through the gastrointestinal tract, is integral for digestive physiology and broader human health. Commensurate with its importance, ENS dysfunction is linked to a range of debilitating gastrointestinal disorders. MicroRNAs (miRNAs), with their pleiotropic roles in post-transcriptional gene regulation, serve as key developmental effectors within the ENS. Herein, we review the regulatory dynamics of miRNAs in ENS ontogeny, showcasing specific miRNAs implicated in both congenital and acquired enteric neuropathies, such as Hirschsprung's disease (HSCR), achalasia, intestinal neuronal dysplasia (IND), chronic intestinal pseudo-obstruction (CIPO), and slow transit constipation (STC). By delineating miRNA-mediated mechanisms in these diseases, we underscore their importance for ENS homeostasis and highlight their potential as therapeutic targets.

Physical Exercise Alleviates Oxidative Stress and Autonomic Dysregulation in a Rat Model of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) induces immunological and autonomic imbalances. Exercise is a beneficial strategy for controlling IBD symptoms. We investigated the role of exercise on gastrointestinal (GI) motility changes and autonomic parameters in rats with ileitis. Rats were divided into control, ileitis, and exercise+ileitis groups. Ileitis was induced by TNBS (40 mM, intraileally). The exercise was swimming (1 h/day/4 weeks, 5%/bw). We assessed eating behaviour and oxidative stress. Body composition was assessed by bioimpedance. Autonomic balance and ECG parameters were measured by an electrocardiogram (ECG). Gastrointestinal motility was evaluated using the phenol red technique. In terms of body composition, total body water (TBW), body mass index (BMI), and fat-free mass (FFM) were higher in the ileitis group (216.80 ± 11.44 mL; 24.09 ± 2.15 g/cm2; 287.1 ± 14.66 g) (p < 0.05) vs. control rats (130.06 ± 28.23 mL; 16.38 ± 2.50 g/cm2; 193 ± 42.21 g) and exercise prevented (91.33 ± 12.33 mL; 11.73 ± 0.47 g/cm2; 133.8 ± 16.82 g) (p < 0.05) these changes. The exercise+ileitis group induces a reduction (p < 0.05) in gastric retention vs. ileitis and control (11.22 ± 1.91% vs. 35.17 ± 1.01% and 33.96 ± 1.77%). Ileitis increased intestinal retention in the duodenum (46.3 ± 2.56% vs. 24.98 ± 1.78%) and jejunum (34.22 ± 2.33% and 34.72 ± 2.83% vs. 47.32 ± 1.48%) (p < 0.05) and decreased intestinal retention in the ileum (p < 0.05) vs. the control group. Exercise+ileitis prevented (p < 0.05) changes in the duodenum (24.96 ± 1.66% vs. 46.3 ± 2.56%) and ileum (40.32 ± 3.75% vs. 14.08 ± 0.88%). Ileitis induces high MDA levels (p < 0.05) vs. control rats (4.43 ± 0.69 vs. 2.15 ± 0.12 nmol/mg of the tissue). This effect was prevented (p < 0.05) in the exercise+ileitis group (2.75 ± 0.21 vs. 4.43 ± 0.69 nmol/mg of the tissue). We observed a reduction in the LF component (p < 0.05) in the ileitis group vs. control group (31.32 ± 3.99 vs. 43.43 ± 3.86). The correlation indicated a stronger interrelationship between the autonomic parameter and intestinal retention in the ileum (r: 0.68; p: 0.04). The current study suggests intestinal ileitis alters GI motility and autonomic balance, and physical exercise can represent an essential non-pharmacological approach to IBD treatment.

Reassessing the role of nitric oxide in the pathogenesis of sphincter of Oddi dysfunction

The pathogenic mechanisms underlying sphincter of Oddi dysfunction (SOD) remain incompletely understood, and it often leads to severe symptoms encompassing nausea, vomiting, and abdominal pain. New evidence now suggests correlations between nitric oxide (NO) and SOD. In this review, we summarized the factors influencing SOD pathogenesis via NO and its derivative, the peroxynitrite anion. NO appears to enhance SOD progression by modulating sphincter of Oddi (SO) contractions via NO-sGC-cGMP signaling or inducing the apoptosis of enteric neurons, interstitial cells of Cajal, smooth muscle cells, and other cellular components via peroxynitrite anion-mediated organelle damage. Thus, a comprehensive understanding of SOD will provide a foundation for the identification of potential drugs and treatment approaches.

Macrophage-induced enteric neurodegeneration leads to motility impairment during gut inflammation

Current studies pictured the enteric nervous system and macrophages as modulators of neuroimmune processes in the inflamed gut. Expanding this view, we investigated the impact of enteric neuron-macrophage interactions on postoperative trauma and subsequent motility disturbances, i.e., postoperative ileus. In the early postsurgical phase, we detected strong neuronal activation, followed by transcriptional and translational signatures indicating neuronal death and synaptic damage. Simultaneously, our study revealed neurodegenerative profiles in macrophage-specific transcriptomes after postoperative trauma. Validating the role of resident and monocyte-derived macrophages, we depleted macrophages by CSF-1R-antibodies and used CCR2-/- mice, known for reduced monocyte infiltration, in POI studies. Only CSF-1R-antibody-treated animals showed decreased neuronal death and lessened synaptic decay, emphasizing the significance of resident macrophages. In human gut samples taken early and late during abdominal surgery, we substantiated the mouse model data and found reactive and apoptotic neurons and dysregulation in synaptic genes, indicating a species' overarching mechanism. Our study demonstrates that surgical trauma activates enteric neurons and induces neurodegeneration, mediated by resident macrophages, introducing neuroprotection as an option for faster recovery after surgery.

Gut Neuropathies and Intestinal Motility Disorders

BACKGROUND

The enteric nervous system plays a key role in the coordination of gastrointestinal motility together with sympathetic, parasympathetic, and extrinsic sensory pathways. In some cases, abnormalities in neural activity in these pathways contribute to disorders of gut motility. Where this is associated with damage or death of enteric neurons, usually detected by microscopy, this is considered a gut neuropathy.

PURPOSE

This review summarizes recent advances in the identification of neuropathies in a range of gastrointestinal motility disorders.

Nervous system in colorectal cancer

A malignant tumor is a complex systemic disease involving the nervous system, which regulates nerve signals. Cancer neuroscience is a field that explores the interactions between tumors and the nervous system. The gastrointestinal tract is a typical peripheral organ with abundant neuroregulation and is regulated by the peripheral, enteric, and central nervous systems (PNS, ENS, and CNS, respectively). The physiological functions of the gastrointestinal tract are maintained via complex neuromodulation. Neuroregulatory imbalance is the primary cause of gastrointestinal diseases, including colorectal cancer (CRC). In CRC, there is a direct interaction between the nervous system and tumor cells. Moreover, this tumor-nerve interaction can indirectly regulate the tumor microenvironment, including the microbiota, immunity, and metabolism. In addition to the lower nerve centers, the stress response, emotion, and cognition represented by the higher nerve centers also participate in the occurrence and progression of CRC. Herein, we review some basic knowledge regarding cancer neuroscience and elucidate the mechanism underlying tumor-nerve interactions in CRC.

Neuroscience in peripheral cancers: tumors hijacking nerves and neuroimmune crosstalk

Cancer neuroscience is an emerging field that investigates the intricate relationship between the nervous system and cancer, gaining increasing recognition for its importance. The central nervous system governs the development of the nervous system and directly affects brain tumors, and the peripheral nervous system (PNS) shapes the tumor microenvironment (TME) of peripheral tumors. Both systems are crucial in cancer initiation and progression, with recent studies revealing a more intricate role of the PNS within the TME. Tumors not only invade nerves but also persuade them through remodeling to further promote malignancy, creating a bidirectional interaction between nerves and cancers. Notably, immune cells also contribute to this communication, forming a triangular relationship that influences protumor inflammation and the effectiveness of immunotherapy. This review delves into the intricate mechanisms connecting the PNS and tumors, focusing on how various immune cell types influence nerve‒tumor interactions, emphasizing the clinical relevance of nerve‒tumor and nerve‒immune dynamics. By deepening our understanding of the interplay between nerves, cancer, and immune cells, this review has the potential to reshape tumor biology insights, inspire innovative therapies, and improve clinical outcomes for cancer patients.

Circadian rhythm disruption modulates enteric neural precursor cells differentiation leading to gastrointestinal motility dysfunction via the NR1D1/NF-κB axis

OBJECTIVES

Circadian rhythm disruption (CRD) is implicated with numerous gastrointestinal motility diseases, with the enteric nervous system (ENS) taking main responsibility for the coordination of gastrointestinal motility. The purpose of this study is to explore the role of circadian rhythms in ENS remodeling and to further elucidate the underlying mechanisms.

METHODS

First, we established a jet-lagged mice model by advancing the light/dark phase shift by six hours every three days for eight weeks. Subsequent changes in gastrointestinal motility and the ENS were then assessed. Additionally, a triple-transgenic mouse strain (Nestin-creERT2 × Ngfr-DreERT2: DTRGFP) was utilized to track the effects of CRD on the differentiation of enteric neural precursor cells (ENPCs). RNA sequencing was also performed to elucidate the underlying mechanism.

RESULTS

Compared to the control group, CRD significantly accelerated gastrointestinal motility, evidenced by faster intestinal peristalsis (P < 0.01), increased fecal output (P < 0.01), and elevated fecal water content (P < 0.05), as well as enhanced electrical field stimulation induced contractions (P < 0.05). These effects were associated with an increase in the number of glial cells and nitrergic neurons in the colonic myenteric plexus. Additionally, ENPCs in the colon showed a heightened differentiation into glial cells and nitrergic neurons. Notably, the NR1D1/nuclear factor-kappaB (NF-κB) axis played a crucial role in the CRD-mediated changes in ENPCs differentiation. Supplementation with NR1D1 agonist or NF-κB antagonist was able to restore gastrointestinal motility and normalize the ENS in jet-lagged mice.

CONCLUSIONS

CRD regulates the differentiation of ENPCs through the NR1D1/NF-κB axis, resulting in dysfunction of the ENS and impaired gastrointestinal motility in mice.

Regenerating enteric neurites navigate the adult intestine using a glial positioning system?

While the enteric nervous system (ENS) is highly dynamic during development, the extent to which it is capable of repair remains unclear. In this issue of Neuron, Stavely et al.1 show that enteric neurons can reinnervate damaged regions to regain functionality using a glial positioning system (GPS) as their guide.

Interindividual Variation in Gut Nitrergic Neuron Density Is Regulated By GDNF Levels and ETV1

BACKGROUND & AIMS

The size and function of the enteric nervous system (ENS) can vary substantially between individuals. Because ENS function is involved in the etiology of a growing number of common human diseases, understanding mechanisms that regulate ENS variation is important.

METHODS

We analyzed RNAseq data from 41 normal adult human colon biopsies and single-cell RNA-seq data from human and mouse developing gut. To establish cause-consequence relationship we used alleles in mice that allow levels change of the candidate effector molecule in the comparable range to human samples. We used siRNA and primary neuronal cultures to define downstream molecular events and characterized gut functional changes in mice where molecular phenotypes paralleled findings in humans.

RESULTS

We found that glial cell line-derived neurotrophic factor (GDNF) levels in the human colon vary about 5-fold and correlate strongly with nitrergic marker expression. In mice, we defined that GDNF levels are regulated via its 3' untranslated region (3' UTR) in the gastrointestinal tract and observed similar correlation between GDNF levels and nitrergic lineage development. We identified miR-9 and miR-133 as evolutionarily conserved candidates for negative regulation of GDNF expression in the gastrointestinal tract. Functionally, an increase in inhibitory nitrergic innervation results in an increase in gastrointestinal tract transit time, stool size, and water content accompanied with modestly reduced epithelial barrier function. Mechanistically, we found that GDNF levels regulate nitrergic lineage development via induction of transcription factor ETV1, corroborated by single-cell gene expression data in human and mouse developing enteric neurons.

CONCLUSIONS

Our results reveal how normal variation in GDNF levels influence ENS size, composition, and gut function, suggesting a mechanism for well-known interindividual variation among those parameters.

Novel Role of the ALPI Gene Associated with Constipation Caused by Complement Component 3 Deficiency

Complement component 3 (C3) deficiency has recently been reported as one of the novel causes of constipation. To identify a unique gene specific to constipation caused by C3 deficiency, the total RNA extracted from the mid colon of C3 knockout (C3 KO) mice was hybridized to oligonucleotide microarrays, and the function of the candidate gene was verified in in vitro and in vivo models. C3 KO mice used for microarrays showed definite phenotypes of constipation. Overall, compared to the wild type (WT), 1237 genes were upregulated, and 1292 genes were downregulated in the C3 KO mice. Of these, the major genes included were lysine (K)-specific demethylase 5D (KDM5D), olfactory receptor 870 (Olfr870), pancreatic lipase (PNLIP), and alkaline phosphatase intestinal (ALPI). Specifically, the ALPI gene was selected as a novel gene candidate based on alterations during loperamide (Lop)-induced constipation and intestinal bowel disease (IBD). The upregulation of ALPI expression treated with acetate recovered the expression level of mucin-related genes in primary epithelial cells of C3 KO mice as well as most phenotypes of constipation in C3 KO mice. These results indicate that ALPI plays an important role as the novel gene associated with C3 deficiency-induced constipation.

Schwann cells and enteric glial cells: Emerging stars in colorectal cancer

Cancer neuroscience, a promising field dedicated to exploring interactions between cancer and the nervous system, has attracted growing attention. The gastrointestinal tracts exhibit extensive innervation, notably characterized by intrinsic innervation. The gut harbors a substantial population of glial cells, including Schwann cells wrapping axons of neurons in the peripheral nervous system and enteric glial cells intricately associated with intrinsic innervation. Glial cells play a crucial role in maintaining the physiological functions of the intestine, encompassing nutrient absorption, barrier integrity, and immune modulation. Nevertheless, it has only been in recent times that the significance of glial cells within colorectal cancer (CRC) has begun to receive considerable attention. Emerging data suggests that glial cells in the gut contribute to the progression and metastasis of CRC, by interacting with cancer cells, influencing inflammation, and modulating the tumor microenvironment. Here, we summarize the significant roles of glial cells in the development and progression of CRC and discuss the latest technologies that can be integrated into this field for in-depth exploration, as well as potential specific targeted strategies for future exploration to benefit patients.

Identification of Arginine-Vasopressin Receptor 1a (Avpr1a/Avpr1a) as a Novel Candidate Gene for Chronic Visceral Pain Sheds Light on the Potential Role of Enteric Neurons in the Development of Visceral Hypersensitivity

Chronic abdominal pain in the absence of ongoing disease is the hallmark of disorders of gut-brain interaction (DGBIs), including irritable bowel syndrome (IBS). While the etiology of DGBIs remains poorly understood, there is evidence that both genetic and environmental factors play a role. In this study, we report the identification and validation of arginine-vasopressin receptor 1A (Avpr1a) as a novel candidate gene for visceral hypersensitivity (VH), a primary peripheral mechanism underlying abdominal pain in DGBI/IBS. Comparing 2 C57BL/6 (BL/6) substrains (C57BL/6NTac and C57BL/6J) revealed differential susceptibility to the development of chronic VH following intrarectal zymosan instillation, a validated preclinical model for postinflammatory IBS. Using whole-genome sequencing, we identified a single-nucleotide polymorphism differentiating the 2 strains in the 5' intergenic region upstream of Avpr1a, encoding the protein Avpr1a. We used behavioral, histological, and molecular approaches to identify distal colon-specific gene expression and neuronal hyperresponsiveness covarying with Avpr1a genotype and VH susceptibility. While the 2 BL/6 substrains did not differ across other gastrointestinal phenotypes (eg, fecal water retention), VH-susceptible BL/6NTac mice had higher colonic Avpr1a mRNA and protein expression. These results parallel findings that patients' colonic Avpr1a mRNA expression corresponded to higher pain ratings. Moreover, neurons of the enteric nervous system were hyperresponsive to the Avpr1a agonist arginine-vasopressin, suggesting a role for enteric neurons in the pathology underlying VH. Taken together, these findings implicate differential regulation of Avpr1a as a novel mechanism of VH susceptibility as well as a potential therapeutic target specific to VH. PERSPECTIVE: This article presents evidence of Avpr1a as a novel candidate gene for VH in a mouse model of IBS. Avpr1a genotype and/or tissue-specific expression represents a potential biomarker for chronic abdominal pain susceptibility.

Is the enteric nervous system a lost piece of the gut-kidney axis puzzle linked to chronic kidney disease?

The enteric nervous system (ENS) regulates numerous functional and immunological attributes of the gastrointestinal tract. Alterations in ENS cell function have been linked to intestinal outcomes in various metabolic, intestinal, and neurological disorders. Chronic kidney disease (CKD) is associated with a challenging intestinal environment due to gut dysbiosis, which further affects patient quality of life. Although the gut-related repercussions of CKD have been thoroughly investigated, the involvement of the ENS in this puzzle remains unclear. ENS cell dysfunction, such as glial reactivity and alterations in cholinergic signaling in the small intestine and colon, in CKD are associated with a wide range of intestinal pathways and responses in affected patients. This review discusses how the ENS is affected in CKD and how it is involved in gut-related outcomes, including intestinal permeability, inflammation, oxidative stress, and dysmotility.

Molecular mechanisms of enteric neuropathies in high-fat diet feeding and diabetes

BACKGROUND

Obesity and diabetes are associated with altered gastrointestinal function and with the development of abdominal pain, nausea, diarrhea, and constipation among other symptoms. The enteric nervous system (ENS) regulates gastrointestinal motility. Enteric neuropathies defined as damage or loss of enteric neurons can lead to motility disorders.

PURPOSE

Here, we review the molecular mechanisms that drive enteric neurodegeneration in diabetes and obesity, including signaling pathways leading to neuronal cell death, oxidative stress, and microbiota alteration. We also highlight potential approaches to treat enteric neuropathies including antioxidant therapy to prevent oxidative stress-induced damage and the use of stem cells.

Ex Vivo Study of Colon Health, Contractility and Innervation in Male and Female Rats after Regular Exposure to Instant Cascara Beverage

Instant Cascara (IC) is a sustainable beverage made from dried coffee cherry pulp, a by-product of coffee processing. It is rich in nutrients and bioactive compounds and has a high concentration of antioxidants. This study explored the impact of regular IC consumption on colonic motor function and innervation. Over a period of 4 weeks, male and female healthy rats were given drinking water containing 10 mg/mL of IC. Thereafter, colon samples were obtained to evaluate the longitudinal (LM) and circular (CM) smooth muscle contractile response to acetylcholine (ACh) and electrical field stimulation (EFS) in an organ bath, before and after atropine administration (10-6 M). Histological and immunohistochemical analyses assessed colon damage, muscle thickness, and immunoreactivity to substance P (SP) and neuronal nitric oxide synthase (nNOS). ACh and EFS induced similar responses across groups, but the CM response to EFS was greater in females compared with males, despite their lower body weight. Atropine completely blocked the response to ACh but only partially antagonized the neural response to EFS, particularly that of CM in females treated with IC, which had a greater liquid intake than those exposed to water. However, in the myenteric ganglia, no statistically significant differences were observed in SP or nNOS. Our results suggest that regular IC exposure may enhance specific neural pathway functions, particularly in females, possibly due to their increased IC consumption.

Genomic stress in diseases stemming from defects in the second brain

This review discusses the less-explored realm of DNA damage and repair within the enteric nervous system (ENS), often referred to as the "second brain." While the central nervous system has been extensively studied for its DNA repair mechanisms and associated neuropathologies, the ENS, which can autonomously coordinate gastrointestinal function, experiences unique challenges and vulnerabilities related to its genome integrity. The susceptibility of the ENS to DNA damage is exacerbated by its limited protective barriers, resulting in not only endogenous genotoxic exposures, such as oxidative stress, but also exogenous threats, such as ingested environmental contaminants, local inflammatory responses, and gut dysbiosis. Here, we discuss the evidence for DNA repair defects in enteric neuropathies, most notably, the reported relationship between inherited mutations in RAD21 and LIG3 with chronic intestinal pseudo-obstruction and mitochondrial gastrointestinal encephalomyopathy disorders, respectively. We also introduce the lesser-recognized gastrointestinal complications in DNA repair syndromes, including conditions like Cockayne syndrome. The review concludes by pointing out the potential role of DNA repair defects in not only congenital disorders but also aging-related gut dysfunction, as well as the crucial need for further research to establish direct causal links between DNA damage accumulation and ENS-specific pathologic phenotypes.

ZEB2 alleviates Hirschsprung's-associated enterocolitis by promoting the proliferation and differentiation of enteric neural precursor cells via the Notch-1/Jagged-2 pathway

BACKGROUND

Hirschsprung's-associated enterocolitis (HAEC) is a prevalent complication of Hirschsprung's disease (HSCR). Zinc finger E-box binding homeobox 2 (ZEB2) and Notch-1/Jagged-2 are dysregulated in HSCR, but their role in HAEC progression remains poorly understood. We aimed to explore the role and underlying mechanism of enteric neural precursor cells (ENPCs) and the ZEB2/Notch-1/Jagged-2 pathway in HAEC development.

METHODS

Colon tissues were collected from HSCR and HAEC patients. ENPCs were isolated from the HAEC group and stimulated by lipopolysaccharide (LPS). The expressions of ZEB2/Notch-1/Jagged-2 were measured using RT-qPCR and Western blot. Immunofluorescence and cell counting kit-8 assays were performed to assess the differentiation and proliferation of ENPCs. Inflammatory factors were measured by ELISA kits. Co-immunoprecipitation and bioinformatic analysis were used to explore the interaction between ZEB2 and Notch-1. Small interfering RNA and overexpression vectors were used to investigate the role and mechanism of ZEB2 and Notch-1 in regulating ENPCs' proliferation and differentiation during HAEC progression.

RESULTS

We observed increased LPS in the colon tissues of HAEC, with downregulated ZEB2 expression and upregulated Notch-1/Jagged-2 expression. ZEB2 interacts with Notch-1. LPS treatment downregulated ZEB2 expression, upregulated Notch-1/Jagged-2 expression, and induced proliferation and differentiation disorders in ENPCs, which were reversed by the knockdown of Notch-1. Furthermore, overexpression of ZEB2 inhibited Notch-1/Jagged-2 signaling and ameliorated inflammation and dysfunction in LPS-induced ENPCs. Notch-1 overexpression enhanced LPS-induced dysfunction, but this effect was antagonized by the overexpression of ZEB2.

CONCLUSION

Overexpression of ZEB2 ameliorates LPS-induced ENPCs' dysfunction via the Notch-1/Jagged-2 pathway, thus playing a role in HAEC.

Enteric neuropathy in diabetes: Implications for gastrointestinal function

Diabetes, commonly known for its metabolic effects, also critically affects the enteric nervous system (ENS), which is essential in regulating gastrointestinal (GI) motility, secretion, and absorption. The development of diabetes-induced enteric neuropathy can lead to various GI dysfunctions, such as gastroparesis and irregular bowel habits, primarily due to disruptions in the function of neuronal and glial cells within the ENS, as well as oxidative stress and inflammation. This editorial explores the pathophysiological mechanisms underlying the development of enteric neuropathy in diabetic patients. Additionally, it discusses the latest advances in diagnostic approaches, emphasizing the need for early detection and intervention to mitigate GI complications in diabetic individuals. The editorial also reviews current and emerging therapeutic strategies, focusing on pharmacological treatments, dietary management, and potential neuromodulatory interventions. Ultimately, this editorial highlights the necessity of a multidisciplinary approach in managing enteric neuropathy in diabetes, aiming to enhance patient quality of life and address a frequently overlooked complication of this widespread disease.

Enteric Nervous System Alterations in Inflammatory Bowel Disease: Perspectives and Implications

The enteric nervous system (ENS), consisting of neurons and glial cells, is situated along the gastrointestinal (GI) tract's wall and plays a crucial role in coordinating digestive processes. Recent research suggests that the optimal functioning of the GI system relies on intricate connections between the ENS, the intestinal epithelium, the immune system, the intestinal microbiome, and the central nervous system (CNS). Inflammatory bowel disease (IBD) encompasses a group of chronic inflammatory disorders, such as Crohn's disease (CD) and ulcerative colitis (UC), characterized by recurring inflammation and damage to the GI tract. This review explores emerging research in the dynamic field of IBD and sheds light on the potential role of ENS alterations in both the etiology and management of IBD. Specifically, we delve into IBD-induced enteric glial cell (EGC) activation and its implications for persistent enteric gliosis, elucidating how this activation disrupts GI function through alterations in the gut-brain axis (GBA). Additionally, we examine IBD-associated ENS alterations, focusing on EGC senescence and the acquisition of the senescence-associated secretory phenotype (SASP). We highlight the pivotal role of these changes in persistent GI inflammation and the recurrence of IBD. Finally, we discuss potential therapeutic interventions involving senotherapeutic agents, providing insights into potential avenues for managing IBD by targeting ENS-related mechanisms. This approach might represent a potential alternative to managing IBD and advance treatment of this multifaceted disease.

From Gut to Brain: Uncovering Potential Serum Biomarkers Connecting Inflammatory Bowel Diseases to Neurodegenerative Diseases

Inflammatory bowel diseases (IBDs) are characterized by chronic gastrointestinal inflammation due to abnormal immune responses to gut microflora. The gut-brain axis is disrupted in IBDs, leading to neurobiological imbalances and affective symptoms. Systemic inflammation in IBDs affects the brain's inflammatory response system, hormonal axis, and blood-brain barrier integrity, influencing the gut microbiota. This review aims to explore the association between dysregulations in the gut-brain axis, serum biomarkers, and the development of cognitive disorders. Studies suggest a potential association between IBDs and the development of neurodegeneration. The mechanisms include systemic inflammation, nutritional deficiency, GBA dysfunction, and the effect of genetics and comorbidities. The objective is to identify potential correlations and propose future research directions to understand the impact of altered microbiomes and intestinal barrier functions on neurodegeneration. Serum levels of vitamins, inflammatory and neuronal damage biomarkers, and neuronal growth factors have been investigated for their potential to predict the development of neurodegenerative diseases, but current results are inconclusive and require more studies.

Efficient enzyme-free method to assess the development and maturation of the innate and adaptive immune systems in the mouse colon

Researchers who aim to globally analyze the gastrointestinal immune system via flow cytometry have many protocol options to choose from, with specifics generally tied to gut wall layers of interest. To get a clearer idea of the approach we should use on full-thickness colon samples from mice, we first undertook a systematic comparison of three tissue dissociation techniques: two based on enzymatic cocktails and the other one based on manual crushing. Using flow cytometry panels of general markers of lymphoid and myeloid cells, we found that the presence of cell-surface markers and relative cell population frequencies were more stable with the mechanical method. Both enzymatic approaches were associated with a marked decrease of several cell-surface markers. Using mechanical dissociation, we then developed two minimally overlapping panels, consisting of a total of 26 antibodies, for serial profiling of lymphoid and myeloid lineages from the mouse colon in greater detail. Here, we highlight how we accurately delineate these populations by manual gating, as well as the reproducibility of our panels on mouse spleen and whole blood. As a proof-of-principle of the usefulness of our general approach, we also report segment- and life stage-specific patterns of immune cell profiles in the colon. Overall, our data indicate that mechanical dissociation is more suitable and efficient than enzymatic methods for recovering immune cells from all colon layers at once. Additionally, our panels will provide researchers with a relatively simple tool for detailed immune cell profiling in the murine gastrointestinal tract, regardless of life stage or experimental conditions.

The Imperative for Innovative Enteric Nervous System-Intestinal Organoid Co-Culture Models: Transforming GI Disease Modeling and Treatment

This review addresses the need for innovative co-culture systems integrating the enteric nervous system (ENS) with intestinal organoids. The breakthroughs achieved through these techniques will pave the way for a transformative era in gastrointestinal (GI) disease modeling and treatment strategies. This review serves as an introduction to the companion protocol paper featured in this journal. The protocol outlines the isolation and co-culture of myenteric and submucosal neurons with small intestinal organoids. This review provides an overview of the intestinal organoid culture field to establish a solid foundation for effective protocol application. Remarkably, the ENS surpasses the number of neurons in the spinal cord. Referred to as the "second brain", the ENS orchestrates pivotal roles in GI functions, including motility, blood flow, and secretion. The ENS is organized into myenteric and submucosal plexuses. These plexuses house diverse subtypes of neurons. Due to its proximity to the gut musculature and its cell type complexity, there are methodological intricacies in studying the ENS. Diverse approaches such as primary cell cultures, three-dimensional (3D) neurospheres, and induced ENS cells offer diverse insights into the multifaceted functionality of the ENS. The ENS exhibits dynamic interactions with the intestinal epithelium, the muscle layer, and the immune system, influencing epithelial physiology, motility, immune responses, and the microbiome. Neurotransmitters, including acetylcholine (ACh), serotonin (5-HT), and vasoactive intestinal peptide (VIP), play pivotal roles in these intricate interactions. Understanding these dynamics is imperative, as the ENS is implicated in various diseases, ranging from neuropathies to GI disorders and neurodegenerative diseases. The emergence of organoid technology presents an unprecedented opportunity to study ENS interactions within the complex milieu of the small and large intestines. This manuscript underscores the urgent need for standardized protocols and advanced techniques to unravel the complexities of the ENS and its dynamic relationship with the gut ecosystem. The insights gleaned from such endeavors hold the potential to revolutionize GI disease modeling and treatment paradigms.

Toll-like receptor 3 signaling drives enteric glial cells against dextran sulfate sodium-induced colitis in mice

The activation of toll-like receptor 3 (TLR3) has been reported to attenuate astrocytes injury in central nervous system, but its effect on enteric glial cells (EGCs) remains unknown. Here, we confirmed that the residence of EGCs was regulated by TLR3 agonist (polyinosinic-polycytidylic acid, PIC) or TLR3/dsRNA complex inhibitor in dextran sulfate sodium (DSS)-induced mice. In vitro, TLR3 signaling prevented apoptosis in EGCs and drove the secretion of EGCs-derived glial cell line-derived neurotrophic factor, 15-hydroxyeicosatetraenoic acid and S-nitrosoglutathione. PIC preconditioning enhanced the protective effects of EGCs against the dysfunction of intestinal epithelial barrier and the development of colitis in DSS-induced mice. Interestingly, PIC stimulation also promoted the effects of EGCs on converting macrophages to an M2-like phenotype and regulating the levels of inflammatory cytokines, including IL-1β, TNF-α and IL-10, in DSS-induced mice. These findings imply that TLR3 signaling in EGCs may provide a potential target for the prevention and treatment of colitis.

Age-dependent effects of acute stress on the behavior, blood parameters, immunity, and enteric nerves of mice

The impact of stress on mental and digestive health has been extensively studied, with chronic stress being associated with various disorders. However, age-related differences in the response to acute stress, both behaviorally and physiologically, remain poorly understood. Therefore, this study aimed to develop a model to detect transient stress in mice of different ages. The stressor employed in our experiments was a restraint stress procedure, where mice were subjected to brief periods of immobilization to induce an acute stress response. Male C3H/HeN mice aged 3, 6, 12, and 30 weeks were subjected to acute restrain stress (ARS) by being placed in a 50 ml conical centrifuge tube for 15 min. Subsequently, their behavior, organ tissues, hematological parameters, cortisol concentration, and immune responses were assessed. Following ARS, the increased in time and entries into the center by the 12-week-old mice following stress. In comparison to mice of other ages, those aged 6 weeks demonstrated notable elevations in erythrocytes, platelets, hemoglobin, and hematocrit, all of which were influenced by the time-dependent changes and the recovery process of ARS. Blood corticosterone levels were substantially elevated in all age groups after ARS. Furthermore, ARS induced a notable increase in leukocytes, basophils, residential macrophages, and CD4+ T cells in all age groups except for 3-week-old mice. However, the number of monocyte-derived macrophages and CD8+ T cells did not change significantly. Additionally, mice aged 3 and 6 weeks demonstrated an increase in GFAP+ cells following ARS, whereas NeuN+ cells decreased across all ages. These results suggest that ARS has varying effects on the behavior, cortisol concentration, and quantity of blood cells as well as hepatic immune cells in mice of different ages. These age-dependent responses shed light on the complex interplay between stress and physiological systems and contribute to the broader understanding of stress-related diseases.

EphB2 promotes enteric nitrergic hyperinnervation and neurogenic inflammation in DSS-induced chronic colitis in mice

BACKGROUND

Enteric nervous system (ENS) has been closely associated with the neuro-immune response and is currently considered a reliable target for intestinal inflammation. Neuronal nitric oxide synthase (nNOS) nerves are involved in inflammatory diseases by releasing nitric oxide (NO). EphB2 expression and density of innervation of the mucosal layer are positively correlated with the severity of intestinal inflammatory responses. In this study, we hypothesized that a EphB2-mediated mechanism may regulate enteric immunity through modulation of nNOS nerves.

METHODS

Firstly, the Western blot (WB) method was employed to quantify EphB2 expression in the intestinal mucosal layer of DSS mice and assess alterations in nerve fiber activation and density. Immunofluorescence (IF) double staining with nNOS and neuronal marker PGP9.5 was conducted to measure nNOS nerve fiber density within the intestinal mucosal layer of mice. Subsequently, in vivo experiments were performed to investigate the inhibitory or activatory effect of EphB2Fc or EphrinB2Fc on EphB2 expression and activation. Immunoprecipitation experiments confirmed the interaction between EphB2 and nNOS nerves. WB and IF experiments were carried out to evaluate both inflammatory conditions of mouse colonic mucosa following intervention with EphB2Fc/EphrinB2Fc as well as changes in nNOS nerve fibers expression. Finally, in vitro experiments, neurally-mediated inflammation was assessed in the organ bath system by activating intestinal mucosal innervation through Veratridine (VER) and electrical field stimulation (EFS) techniques for 3 h. The activation of nNOS nerves was inhibited by nitroindazole (7NI). WB was employed to detect changes in the expression of inflammatory factors in the intestinal mucosal layer in EphB2Fc/EphrinB2Fc treated mice and control group.

KEY RESULTS

We found that the expression of EphB2 and density nNOS nerve fibers in the intestinal mucosa were positively correlated with the colitis response. Blocking (EphB2Fc)/activating (EphrinB2Fc) EphB2 in vivo significantly reduced/increased the density of nNOS nerve fibers and expression of inflammatory factors in colonic mucosa of DSS treated mice. In vitro, blocking nNOS nerves activation attenuated the inflammatory reaction induced by either EFS or EphB2.

CONCLUSIONS

Our findings provided evidence that EphB2 mediated regulation of innate immunity-ENS crosstalk might represent an attractive target for novel therapeutic strategies in ulcerative colitis.

Comprehensive landscape-style investigation of the molecular mechanism of acupuncture at ST36 single acupoint on different systemic diseases

The principle of acupoint stimulation efficacy is based on traditional meridian theory. However, the molecular mechanisms underlying the therapeutic effects of acupoints in treating diseases remain unclear in modern scientific understanding. In this study, we selected the ST36 acupoint for investigation and summarized all relevant literature from the PubMed database over the past 10 years. The results indicate that stimulation of ST36 single acupoints has therapeutic effects mainly in models of respiratory, neurological, digestive, endocrine and immune system diseases. And it can affect the inflammatory state, oxidative stress, respiratory mucus secretion, intestinal flora, immune cell function, neurotransmitter transmission, hormone secretion, the network of Interstitial Cells of Cajal (ICC) and glucose metabolism of the organism in these pathological states. Among them, acupuncture at the ST36 single point has the most prominent function in regulating the inflammatory state, which can mainly affect the activation of MAPK signaling pathway and drive the "molecular-cellular" mode involving macrophages, T-lymphocytes, mast cells (MCs) and neuroglial cells as the core to trigger the molecular level changes of the acupuncture point locally or in the target organ tissues, thereby establishing a multi-system, multi-target, multi-level molecular regulating mechanism. This article provides a comprehensive summary and discussion of the molecular mechanisms and effects of acupuncture at the ST36 acupoint, laying the groundwork for future in-depth research on acupuncture point theory.

Between Dysbiosis, Maternal Immune Activation and Autism: Is There a Common Pathway?

Autism spectrum disorder (ASD) is a neuropsychiatric condition characterized by impaired social interactions and repetitive stereotyped behaviors. Growing evidence highlights an important role of the gut-brain-microbiome axis in the pathogenesis of ASD. Research indicates an abnormal composition of the gut microbiome and the potential involvement of bacterial molecules in neuroinflammation and brain development disruptions. Concurrently, attention is directed towards the role of short-chain fatty acids (SCFAs) and impaired intestinal tightness. This comprehensive review emphasizes the potential impact of maternal gut microbiota changes on the development of autism in children, especially considering maternal immune activation (MIA). The following paper evaluates the impact of the birth route on the colonization of the child with bacteria in the first weeks of life. Furthermore, it explores the role of pro-inflammatory cytokines, such as IL-6 and IL-17a and mother's obesity as potentially environmental factors of ASD. The purpose of this review is to advance our understanding of ASD pathogenesis, while also searching for the positive implications of the latest therapies, such as probiotics, prebiotics or fecal microbiota transplantation, targeting the gut microbiota and reducing inflammation. This review aims to provide valuable insights that could instruct future studies and treatments for individuals affected by ASD.

Differences in enteric neuronal density in the NSE-Noggin mouse model across institutes

The enteric nervous system (ENS) is a large and complex part of the peripheral nervous system, and it is vital for gut homeostasis. To study the ENS, different hyper- and hypo-innervated model systems have been developed. The NSE-Noggin mouse model was described as one of the few models with a higher enteric neuronal density in the colon. However, in our hands NSE-Noggin mice did not present with a hyperganglionic phenotype. NSE-Noggin mice were phenotyped based on fur appearance, genotyped and DNA sequenced to demonstrate transgene and intact NSE-Noggin-IRES-EGFP construct presence, and RNA expression of Noggin was shown to be upregulated. Positive EGFP staining in the plexus of NSE-Noggin mice also confirmed Noggin protein expression. Myenteric plexus preparations of the colon were examined to quantify both the overall density of enteric neurons and the proportions of enteric neurons expressing specific subtype markers. The total number of enteric neurons in the colonic myenteric plexus of transgenic mice did not differ significantly from wild types, nor did the proportion of calbindin, calretinin, or serotonin immunoreactive myenteric neurons. Possible reasons as to why the hyperinnervated phenotype could not be observed in contrast with original studies using this mouse model are discussed, including study design, influence of microbiota, and other environmental variables.

Effects of weaning on intestinal longitudinal muscle-myenteric plexus function in piglets

Weaning piglets usually suffer from severe diarrhea (commonly known as postweaning diarrhea, PWD) along with intestinal motility disorder. Intestinal peristalsis is mainly regulated by the longitudinal muscle-myenteric plexus (LM-MP). To understand the relationship between intestinal LM-MP function and the development of PWD, we compared the intestinal electrical activity, and the transcriptional profile of the LM-MP between 21-day-old piglets (just weaned, n=7) and 24-day-old piglets (suffered the most severe weaning stress, n=7). The results showed that 24-day-old piglets exhibited different degrees of diarrhea. A significant increase in the slow-wave frequency in the ileum and colon was observed in 24-day-old piglets, while c-kit expression in the intestinal LM-MPs was significantly decreased, indicating that PWD caused by elevated slow-wave frequency may be associated with loss of c-kit. The real-time quantitative PCR (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) showed that intestinal LM-MPs in 24-day-old piglets may undergo inflammation and oxidative stress. Significant increases in 8-hydroxy-2'-deoxyguanosine and decreases in thioredoxin suggest that weaning may lead to DNA damage in the LM-MP of 24-day-old piglets. In addition, activating transcription factor 3 was significantly upregulated, indicating nerve damage in the LM-MP of 24-day-old piglets. The transcriptomic results showed that most of the differentially expressed genes in the ileal LM-MP after weaning were downregulated and closely related to the cell cycle process. Subsequent RT-qPCR analysis showed that the relative expression of p21 was upregulated, while the expression of cyclin A2, cyclin B1, and proliferating cell nuclear antigen was downregulated in the ileal and colonic LM-MP of 24-day-old piglets, suggesting that weaning may inhibit cell proliferation and cause G1/S cell cycle arrest in ileal and colonic LM-MP. In conclusion, weaning may lead to cell cycle arrest by causing DNA damage in the LM-MP, impairing intestinal motility regulation, and ultimately leading to diarrhea in piglets.

From the Gut to the Brain: The Role of Enteric Glial Cells and Their Involvement in the Pathogenesis of Parkinson's Disease

The brain-gut axis has been identified as an important contributor to the physiopathology of Parkinson's disease. In this pathology, inflammation is thought to be driven by the damage caused by aggregation of α-synuclein in the brain. Interestingly, the Braak's theory proposes that α-synuclein misfolding may originate in the gut and spread in a "prion-like" manner through the vagus nerve into the central nervous system. In the enteric nervous system, enteric glial cells are the most abundant cellular component. Several studies have evaluated their role in Parkinson's disease. Using samples obtained from patients, cell cultures, or animal models, the studies with specific antibodies to label enteric glial cells (GFAP, Sox-10, and S100β) seem to indicate that activation and reactive gliosis are associated to the neurodegeneration produced by Parkinson's disease in the enteric nervous system. Of interest, Toll-like receptors, which are expressed on enteric glial cells, participate in the triggering of immune/inflammatory responses, in the maintenance of intestinal barrier integrity and in the configuration of gut microbiota; thus, these receptors might contribute to Parkinson's disease. External factors like stress also seem to be relevant in its pathogenesis. Some authors have studied ways to reverse changes in EGCs with interventions such as administration of Tryptophan-2,3-dioxygenase inhibitors, nutraceuticals, or physical exercise. Some researchers point out that beyond being activated during the disease, enteric glial cells may contribute to the development of synucleinopathies. Thus, it is still necessary to further study these cells and their role in Parkinson's disease.

A blend of Withania somnifera (L.) Dunal root and Abelmoschus esculentus (L.) Moench fruit extracts relieves constipation and improves bowel function: A proof-of-concept clinical investigation

ETHNOPHARMACOLOGICAL RELEVANCE

Withania somnifera (L.) Dunal (WS) and Abelmoschus esculentus (L.) Moench (AE) are known as Ashwagandha and Okra, respectively, important herbs in traditional medicine for their diverse therapeutic values. WS root is an adaptogen that relieves stress and anxiety and promotes sleep. AE fruit or Okra is widely consumed as a vegetable and is traditionally used to treat diabetes, gastric irritations, ulcers, and obesity.

AIM OF THE STUDY

The present randomized, double-blind, placebo-controlled study aimed to establish a proof-of-concept evaluating the efficacy and tolerability of a proprietary blend of standardized extracts of WS root and AE fruit, CL18100F4 in relieving constipation and improving quality of life in adults.

MATERIALS AND METHODS

Forty-eight male and female participants (age: 25-60 years) with functional constipation (following Rome-III criteria) were randomized into placebo, 300 or 500 mg of CL18100F4 groups, and supplemented for fourteen consecutive days.

RESULTS

CL18100F4 supplementation significantly (p < 0.0001) reduced the Patient Assessment of Constipation-Symptoms (PAC-SYM), Patient Assessment of Constipation-Quality of Life (PAC-QOL), and Gastrointestinal Symptom Rating Scale (GSRS) scores. CL18100F4 supplementation improved sleep quality and reduced stress (p < 0.0001). At the end of the study, CL18100F4-500 subjects showed significant increases in serum serotonin, gastrin, and interleukin-10 and decrease in interleukin-6 and cortisol levels. Participants' hematology, total blood chemistry, vital signs, and urinalysis parameters were within the normal ranges. No adverse events were reported.

CONCLUSIONS

This short-duration, single-site clinical investigation demonstrates that CL18100F4 supplementation is tolerable, helps relieve constipation, reduces stress, and improves gastrointestinal function, sleep quality, and general wellness in adults.

TRIAL REGISTRATION

Clinical Trials Registry- India (CTRI/2020/11/029320); Registered on 24/11/2020. Available at: http://ctri.nic.in/Clinicaltrials/showallp.php?mid1=49391&EncHid=&userName=CL18100F4.

The nerve cells in gastrointestinal cancers: from molecular mechanisms to clinical intervention

Gastrointestinal (GI) cancer is a formidable malignancy with significant morbidity and mortality rates. Recent studies have shed light on the complex interplay between the nervous system and the GI system, influencing various aspects of GI tumorigenesis, such as the malignance of cancer cells, the conformation of tumor microenvironment (TME), and the resistance to chemotherapies. The discussion in this review first focused on exploring the intricate details of the biological function of the nervous system in the development of the GI tract and the progression of tumors within it. Meanwhile, the cancer cell-originated feedback regulation on the nervous system is revealed to play a crucial role in the growth and development of nerve cells within tumor tissues. This interaction is vital for understanding the complex relationship between the nervous system and GI oncogenesis. Additionally, the study identified various components within the TME that possess a significant influence on the occurrence and progression of GI cancer, including microbiota, immune cells, and fibroblasts. Moreover, we highlighted the transformation relationship between non-neuronal cells and neuronal cells during GI cancer progression, inspiring the development of strategies for nervous system-guided anti-tumor drugs. By further elucidating the deep mechanism of various neuroregulatory signals and neuronal intervention, we underlined the potential of these targeted drugs translating into effective therapies for GI cancer treatment. In summary, this review provides an overview of the mechanisms of neuromodulation and explores potential therapeutic opportunities, providing insights into the understanding and management of GI cancers.

Long-Term Implicit Epigenetic Stress Information in the Enteric Nervous System and its Contribution to Developing and Perpetuating IBS

Psychiatric and mood disorders may play an important role in the development and persistence of irritable bowel syndrome (IBS). Previously, we hypothesized that stress-induced implicit memories may persist throughout life via epigenetic processes in the enteric nervous system (ENS), independent of the central nervous system (CNS). These epigenetic memories in the ENS may contribute to developing and perpetuating IBS. Here, we further elaborate on our earlier hypothesis. That is, during pregnancy, maternal prenatal stresses perturb the HPA axis and increase circulating cortisol levels, which can affect the maternal gut microbiota. Maternal cortisol can cross the placental barrier and increase cortisol-circulating levels in the fetus. This leads to dysregulation of the HPA axis, affecting the gut microbiota, microbial metabolites, and intestinal permeability in the fetus. Microbial metabolites, such as short-chain fatty acids (which also regulate the development of fetal ENS), can modulate a range of diseases by inducing epigenetic changes. These mentioned processes suggest that stress-related, implicit, long-term epigenetic memories may be programmed into the fetal ENS during pregnancy. Subsequently, this implicit epigenetic stress information from the fetal ENS could be conveyed to the CNS through the bidirectional microbiota-gut-brain axis (MGBA), leading to perturbed functional connectivity among various brain networks and the dysregulation of affective and pain processes.

Acute Mesenteric Ischemia: The Diagnostic Value of QT Parameters and their Relationship with CT Findings

BACKGROUND

One of the greatest challenges in the diagnosis of acute mesenteric ischemia (AMI) is the lack of specific laboratory tests that support multidetector computed tomography (CT). Our aim is to investigate the diagnostic value of electrocardiographic QT parameters in AMI and their relationship with CT findings.

MATERIALS AND METHODS

Patients who were admitted to the emergency department with abdominal pain were recruited retrospectively from the hospital information system. Grouping was carried out on the basis of AMI (n=78) and non-AMI (n=78). In both groups, the corrected QT (QTc) and QT dispersion (QTD) were measured on electrocardiographs, and the qualitative and quantitative CT findings were evaluated on CT examinations.

RESULTS

The QTc and QTD values were higher in the AMI group. The median QTc values were 456.16 (IQR: 422.88-483.16) for the AMI group and 388.83 (IQR: 359.74-415.83) for the control group (p<0.001), and the median QTD values were 58 (IQR: 50.3-68.25) for the AMI group and 46 (IQR: 42-50) for the control group (p<0.001). In the CT analysis, the QTc values were significantly higher among AMI patients, with images of paper-thin bowel walls and the absence of bowel wall enhancement (p=0.042 and p=0.042, respectively). Meanwhile, the QTD values were significantly higher among patients with venous pneumatosis findings on CT (p=0.005). In the regression analysis, a significant relationship was found between the QT parameters and AMI (p<0.001). For QTc, an AUC of 0.903 (95% CI: 0.857-0.950, p<0.001), a sensitivity of 80.8%, and a specificity of 82.3% were found. For QTD, an AUC of 0.821 (95% CI: 0.753-0.889, p<0.001), a sensitivity of 73.1%, and a specificity of 82.3% were found.

CONCLUSION

We found the QTc and QTD values to be significantly higher among AMI patients. Furthermore, we found a significant relationship between the CT findings and QTc and QTD and a significant relationship between survival and QTc in the AMI group.

Identification of arginine-vasopressin receptor 1a (Avpr1a/AVPR1A) as a novel candidate gene for chronic visceral pain

Chronic abdominal pain in the absence of ongoing disease is the hallmark of disorders of gut-brain interaction (DGBIs), including irritable bowel syndrome (IBS). While the etiology of DGBIs remains poorly understood, there is evidence that both genetic and environmental factors play a role. In this study, we report the identification and validation of Avpr1a as a novel candidate gene for visceral hypersensitivity (VH), a primary peripheral mechanism underlying abdominal pain in DGBI/IBS. Comparing two C57BL/6 (BL/6) substrains (C57BL/6NTac and C57BL/6J) revealed differential susceptibility to the development of chronic VH following intrarectal zymosan (ZYM) instillation, a validated preclinical model for post-inflammatory IBS. Using whole genome sequencing, we identified a SNP differentiating the two strains in the 5' intergenic region upstream of Avpr1a, encoding the protein arginine-vasopressin receptor 1A (AVPR1A). We used behavioral, histological, and molecular approaches to identify distal colon-specific gene expression differences and neuronal hyperresponsiveness covarying with Avpr1a genotype and VH susceptibility. While the two BL/6 substrains did not differ across other gastrointestinal (GI) phenotypes (e.g., GI motility), VH-susceptible BL/6NTac mice had higher colonic Avpr1a mRNA and protein expression. Moreover, neurons of the enteric nervous system were hyperresponsive to the AVPR1A agonist AVP, suggesting a role for enteric neurons in the pathology underlying VH. These results parallel our findings that patients' colonic Avpr1a mRNA expression was higher in patients with higher pain ratings. Taken together, these findings implicate differential regulation of Avpr1a as a novel mechanism of VH-susceptibility as well as a potential therapeutic target specific to VH.

Pharmacological Considerations in the Interpretation of Biochemical Results in Diabetic Patients with Cardiovascular Complications

Diabetes mellitus with cardiovascular diseases is often a multi-systemic disease that requires a multi-therapeutic approach which mostly poses a challenge to laboratory result interpretation. The non-availability of information on many patients due to poor referral, documentation and record keeping has resulted in isolated interpretation of laboratory result of diabetic patients with multisystemic complications. This has led to both analytical and post-analytical errors which has a negative impact on total quality of results. Therefore, this review showed the possible therapeutic treatment of a diabetic patient with cardiovascular disease and how their pharmacological role could affect laboratory result.

Evaluating the molecular and genetic mechanisms underlying gut motility disorders

INTRODUCTION

Gastrointestinal (GI) motility disorders comprise a wide range of different diseases affecting the structural or functional integrity of the GI neuromusculature. Their clinical presentation and burden of disease depends on the predominant location and extent of gut involvement as well as the component of the gut neuromusculature affected.

AREAS COVERED

A comprehensive literature review was conducted using the PubMed and Medline databases to identify articles related to GI motility and functional disorders, published between 2016 and 2023. In this article, we highlight the current knowledge of molecular and genetic mechanisms underlying GI dysmotility, including disorders of gut-brain interaction, which involve both GI motor and sensory disturbance.

EXPERT OPINION

Although the pathophysiology and molecular mechanisms underlying many such disorders remain unclear, recent advances in the assessment of intestinal tissue samples, genetic testing with the application of 'omics' technologies and the use of animal models will provide better insights into disease pathogenesis as well as opportunities to improve therapy.

Enteric glia as a player of gut-brain interactions during Parkinson's disease

The enteric glia has been shown as a potential component of neuroimmune interactions that signal in the gut-brain axis during Parkinson's disease (PD). Enteric glia are a peripheral glial type found in the enteric nervous system (ENS) that, associated with enteric neurons, command various gastrointestinal (GI) functions. They are a unique cell type, with distinct phenotypes and distribution in the gut layers, which establish relevant neuroimmune modulation and regulate neuronal function. Comprehension of enteric glial roles during prodromal and symptomatic phases of PD should be a priority in neurogastroenterology research, as the reactive enteric glial profile, gastrointestinal dysfunction, and colonic inflammation have been verified during the prodromal phase of PD-a moment that may be interesting for interventions. In this review, we explore the mechanisms that should govern enteric glial signaling through the gut-brain axis to understand pathological events and verify the possible windows and pathways for therapeutic intervention. Enteric glia directly modulate several functional aspects of the intestine, such as motility, visceral sensory signaling, and immune polarization, key GI processes found deregulated in patients with PD. The search for glial biomarkers, the investigation of temporal-spatial events involving glial reactivity/signaling, and the proposal of enteric glia-based therapies are clearly demanded for innovative and intestine-related management of PD.

The Gut-brain Connection and Episodic Migraine: an Update

PURPOSE OF REVIEW

Historical evidence suggests a shared underlying etiology for migraine and gastrointestinal (GI) disorders that involves the gut-brain axis. Here we provide narrative review of recent literature on the gut-brain connection and migraine to emphasize the importance of tailoring treatment plans for patients with episodic migraine who experience GI comorbidities and symptoms.

RECENT FINDINGS

Recent population-based studies report the prevalence of migraine and GI disorders as comorbidities as well as overlapping symptomology. American Headache Society (AHS) guidelines have integrated GI symptoms as part of migraine diagnostic criteria and recommend nonoral therapies for patients with GI symptoms or conditions. Nasal delivery is a recommended nonoral alternative; however, it is important to understand potential adverse events that may cause or worsen GI symptoms in some patients due to the site of drug deposition within the nasal cavity with some nasal therapies. Lastly, clinical perspectives emphasize the importance of identifying GI symptoms and comorbidities in patients with episodic migraine to best individualize migraine management. Support for an association between the gut-brain axis and migraine continues to prevail in recent literature; however, the relationship remains complex and not well elucidated. The presence of GI comorbidities and symptoms must be carefully considered when making treatment decisions for patients with episodic migraine.

Anti-Hyperalgesic Efficacy of Acetyl L-Carnitine (ALCAR) Against Visceral Pain Induced by Colitis: Involvement of Glia in the Enteric and Central Nervous System

The management of abdominal pain in patients affected by inflammatory bowel diseases (IBDs) still represents a problem because of the lack of effective treatments. Acetyl L-carnitine (ALCAR) has proved useful in the treatment of different types of chronic pain with excellent tolerability. The present work aimed at evaluating the anti-hyperalgesic efficacy of ALCAR in a model of persistent visceral pain associated with colitis induced by 2,4-dinitrobenzene sulfonic acid (DNBS) injection. Two different protocols were applied. In the preventive protocol, ALCAR was administered daily starting 14 days to 24 h before the delivery of DNBS. In the interventive protocol, ALCAR was daily administered starting the same day of DNBS injection, and the treatment was continued for 14 days. In both cases, ALCAR significantly reduced the establishment of visceral hyperalgesia in DNBS-treated animals, though the interventive protocol showed a greater efficacy than the preventive one. The interventive protocol partially reduced colon damage in rats, counteracting enteric glia and spinal astrocyte activation resulting from colitis, as analyzed by immunofluorescence. On the other hand, the preventive protocol effectively protected enteric neurons from the inflammatory insult. These findings suggest the putative usefulness of ALCAR as a food supplement for patients suffering from IBDs.