Neuroplasticity and dysfunction after gastrointestinal inflammation

Enteric nervous system regeneration and functional cure of experimental digestive Chagas disease with trypanocidal chemotherapy

Digestive Chagas disease (DCD) is an enteric neuropathy caused by Trypanosoma cruzi infection. There is a lack of evidence on the mechanism of pathogenesis and rationales for treatment. We used a female C3H/HeN mouse model that recapitulates key clinical manifestations to study how infection dynamics shape DCD pathology and the impact of treatment with the front-line, anti-parasitic drug benznidazole. Curative treatment 6 weeks post-infection resulted in sustained recovery of gastrointestinal transit function, whereas treatment failure led to infection relapse and gradual return of DCD symptoms. Neuro/immune gene expression patterns shifted from chronic inflammation to a tissue repair profile after cure, accompanied by increased cellular proliferation, glial cell marker expression and recovery of neuronal density in the myenteric plexus. Delaying treatment until 24 weeks post-infection led to partial reversal of DCD, suggesting the accumulation of permanent tissue damage over the course of chronic infection. Our study shows that murine DCD pathogenesis is sustained by chronic T. cruzi infection and is not an inevitable consequence of acute stage denervation. The risk of irreversible enteric neuromuscular tissue damage and dysfunction developing highlights the importance of prompt diagnosis and treatment. These findings support the concept of treating asymptomatic, T. cruzi-infected individuals with benznidazole to prevent DCD development.

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.

Paraventricular thalamus-insular cortex circuit mediates colorectal visceral pain induced by neonatal colonic inflammation in mice

AIMS

Irritable bowel syndrome (IBS) is a common functional gastrointestinal disorder, but its pathogenesis remains incompletely understood, particularly the involvements of central nervous system sensitization in colorectal visceral pain. Our study was to investigate whether the paraventricular thalamus (PVT) projected to the insular cortex (IC) to regulate colorectal visceral pain in neonatal colonic inflammation (NCI) mice and underlying mechanisms.

METHODS

We applied optogenetic, chemogenetic, or pharmacological approaches to manipulate the glutamatergicPVT-IC pathway. Fiber photometry was used to assess neuronal activity. Electromyography activities in response to colorectal distension (CRD) were measured to evaluate the colorectal visceral pain.

RESULTS

NCI enhanced c-Fos expression and calcium activity upon CRD in the ICGlu, and optogenetic manipulation of them altered colorectal visceral pain responses accordingly. Viral tracing indicated that the PVTGlu projected to the ICGlu. Optogenetic manipulation of PVTGlu changed colorectal visceral pain responses. Furthermore, selective optogenetic modulation of PVT projections in the IC influenced colorectal visceral pain, which was reversed by chemogenetic manipulation of downstream ICGlu.

CONCLUSIONS

This study identified a novel PVT-IC neural circuit playing a critical role in colorectal visceral pain in a mouse model of IBS.

Structural alterations of brain in different disease states of Crohn's disease: Results of a cross-sectional study in a Chinese hospital

Rationale and objectives

To investigate alterations in the brain structure in patients with Crohn's disease in activity (CD-A) and in remission (CD-R) compared to healthy controls (HCs) and explore the relationship between gray matter volume (GMV) and psychological disorders.

Materials and methods

A total of 127 CD patients (62 CD-A, 65 CD-R) and 92 healthy controls (HCs) were enrolled and analyzed in this study. The Crohn's disease activity index (CDAI) was used as the grouping criteria. Voxel-based morphometry (VBM) was applied to investigate gray matter volume (GMV), white matter volume (WMV) and global cerebrospinal fluid (CSF) volume alterations. Pearson correlation analysis was used to evaluate the relationships.

Results

The CSF volume was negatively correlated with the disease duration in CD-R. Increased GMV of CD was observed in the parahippocampal gyrus, precentral gyrus, precuneous cortex, and subcallosal cortex, decreased was located in the occipital pole, precentral gyrus, inferior temporal gyrus, middle frontal gyrus, angular gyrus, frontal pole, lateral occipital cortex, and lingual gyrus. The GMV in the right temporal pole, left precuneous cortex, and left cingulate gyrus had a positive correlation with erythrocyte and hemoglobin in CD groups. The GMV in the right frontal pole, right postcentral gyrus, and left cingulate gyrus had a negative correlation with somatization in the CD groups. The GMV in the right temporal pole had a negative correlation with psychoticism and other in the CD groups. The GMV in the left cingulate gyrus was positive with bowel symptoms and systemic symptoms in the CD groups.

Conclusion

Alterations of GMV in CD-A and CD-R and associated correlation with psychological disorders may provide evidence for possible neuro-mechanisms of CD with psychological disorders.

A comparison of interferential current efficacy in elderly intervertebral disc degeneration patients with or without sarcopenia: a retrospective study

BACKGROUND

Intervertebral disc degeneration and sarcopenia are both age-related diseases without effective treatments. Their comorbidities may worsen the prognosis, and further studies on interaction and therapy are needed. The purpose of the study was to investigate the prevalence of sarcopenia in intervertebral disc degeneration, and to compare the characteristics of intervertebral disc degeneration with and without sarcopenia and effects of interferential current.

METHODS

One hundred twenty disc degeneration patients were included from 2021 to 2022 in a single institute. Medical records, examination results and radiological reports were reviewed. Patients with sarcopenia were screened and grouped according to Asian Working Group for Sarcopenia 2019. VAS, ODI, SARC-F, SMI, gait speed (GS), grip strength, disc Pfirrmann grading, standard cross-sectional area (SCSA), degree of fatty infiltration (DFF), and nerve conduction velocity (NCV) were assessed before and after treatment.

RESULTS

The prevalence of sarcopenia in intervertebral disc degeneration was 28.3%. The difference of VAS, ODI, disc Pfirrmann grading, SCSA, DFF and NCV between two groups were significant before intervention (P < 0.05), SCSA and DFF were related to the degree of disc degeneration. The improvement of SMI, GS, grip strength, VAS, SARC-F and ODI in intervertebral disc degeneration with sarcopenia group was significant after intervention, as well as SMI, GS, grip strength, VAS and ODI in those without sarcopenia (P < 0.05). The improvement of grip strength, GS, ODI and SARC-F in intervertebral disc degeneration with sarcopenia group were greater than the one without sarcopenia (P < 0.05), whereas there was no significance in improvement degree of other indicators between the two groups (P > 0.05).

CONCLUSION

The prevalence of sarcopenia was high in intervertebral disc degeneration, and paravertebral muscles degeneration correlated with the degree of disc degeneration. Compared to those without sarcopenia, intervertebral disc degeneration patients with sarcopenia have more severe pain, poorer mobility and neurological function. Interferential current is effective in intervertebral disc degeneration patients and sarcopenia patients.

Stroke Alters the Function of Enteric Neurons to Impair Smooth Muscle Relaxation and Dysregulates Gut Transit

BACKGROUND

Gut dysmotility is common after ischemic stroke, but the mechanism underlying this response is unknown. Under homeostasis, gut motility is regulated by the neurons of the enteric nervous system that control contractile/relaxation activity of muscle cells in the gut wall. More recently, studies of gut inflammation revealed interactions of macrophages with enteric neurons are also involved in modulating gut motility. However, whether poststroke gut dysmotility is mediated by direct signaling to the enteric nervous system or indirectly via inflammatory macrophages is unknown.

METHODS AND RESULTS

We examined these hypotheses by using a clinically relevant permanent intraluminal midcerebral artery occlusion experimental model of stroke. At 24 hours after stroke, we performed in vivo and ex vivo gut motility assays, flow cytometry, immunofluorescence, and transcriptomic analysis. Stroke-induced gut dysmotility was associated with recruitment of muscularis macrophages into the gastrointestinal tract and redistribution of muscularis macrophages away from myenteric ganglia. The permanent intraluminal midcerebral artery occlusion model caused changes in gene expression in muscularis macrophages consistent with an altered phenotype. While the size of myenteric ganglia after stroke was not altered, myenteric neurons from post-permanent intraluminal midcerebral artery occlusion mice showed a reduction in neuronal nitric oxide synthase expression, and this response was associated with enhanced intestinal smooth muscle contraction ex vivo. Finally, chemical sympathectomy with 6-hydroxydopamine prevented the loss of myenteric neuronal nitric oxide synthase expression and stroke-induced slowed gut transit.

CONCLUSIONS

Our findings demonstrate that activation of the sympathetic nervous system after stroke is associated with reduced neuronal nitric oxide synthase expression in myenteric neurons, resulting in impaired smooth muscle relaxation and dysregulation of gut transit.

The Sympathetic-Immune Milieu in Metabolic Health and Diseases: Insights from Pancreas, Liver, Intestine, and Adipose Tissues

Sympathetic innervation plays a crucial role in maintaining energy balance and contributes to metabolic pathophysiology. Recent evidence has begun to uncover the innervation landscape of sympathetic projections and sheds light on their important functions in metabolic activities. Additionally, the immune system has long been studied for its essential roles in metabolic health and diseases. In this review, the aim is to provide an overview of the current research progress on the sympathetic regulation of key metabolic organs, including the pancreas, liver, intestine, and adipose tissues. In particular, efforts are made to highlight the critical roles of the peripheral nervous system and its potential interplay with immune components. Overall, it is hoped to underscore the importance of studying metabolic organs from a comprehensive and interconnected perspective, which will provide valuable insights into the complex mechanisms underlying metabolic regulation and may lead to novel therapeutic strategies for metabolic diseases.

Myenteric Plexus Immune Cell Infiltrations and Neurotransmitter Expression in Crohn's Disease and Ulcerative Colitis

BACKGROUND AND AIMS

Pain is a cardinal symptom in inflammatory bowel disease [IBD]. An important structure in the transduction of pain signalling is the myenteric plexus [MP]. Nevertheless, IBD-associated infiltration of the MP by immune cells lacks in-depth characterisation. Herein, we decipher intra- and periganglionic immune cell infiltrations in Crohn´s disease [CD] and ulcerative colitis [UC] and provide a comparison with murine models of colitis.

METHODS

Full wall specimens of surgical colon resections served to examine immune cell populations by either conventional immuno-histochemistry or immunofluorescence followed by either bright field or confocal microscopy. Results were compared with equivalent examinations in various murine models of intestinal inflammation.

RESULTS

Whereas the MP morphology was not significantly altered in IBD, we identified intraganglionic IBD-specific B cell- and monocyte-dominant cell infiltrations in CD. In contrast, UC-MPs were infiltrated by CD8+ T cells and revealed a higher extent of ganglionic cell apoptosis. With regard to the murine models of intestinal inflammation, the chronic dextran sulphate sodium [DSS]-induced colitis model reflected CD [and to a lesser extent UC] best, as it also showed increased monocytic infiltration as well as a modest B cell and CD8+ T cell infiltration.

CONCLUSIONS

In CD, MPs were infiltrated by B cells and monocytes. In UC, mostly CD8+ cytotoxic T cells were found. The chronic DSS-induced colitis in the mouse model reflected best the MP-immune cell infiltrations representative for IBD.

Potential effects of sodium hyaluronate on constipation-predominant irritable bowel syndrome

Treatment strategies for constipation-predominant irritable bowel syndrome (IBS-C) continue to improve. However, effective drugs are still lacking. Herein, we explored whether sodium hyaluronate (SH) could be used to treat IBS-C. The effects of SH with different molecular weights were compared in a rat model of IBS-C. Low-molecular-weight SH (LMW-SH, 5 ∼ 10 kDa), medium-molecular-weight SH (MMW-SH, 200 ∼ 400 kDa), and high-molecular-weight SH (HMW-SH, 1300 ∼ 1500 kDa) were screened for efficacy in IBS-C using the following indicators: body weight, number of fecal pellets, fecal moisture, visceral hypersensitivity, and gastrointestinal transit rate. H-HMW-SH was the most effective in improving IBS-C symptoms. The ELISA kits indicated that H-HMW-SH reduced the levels of pro-inflammatory cytokines IL-1β, IL-18, and TNF-α in IBS-C rats. In addition, both western blot and immunofluorescence analyses showed that H-HMW-SH increased the protein expressions of claudin-1, occludin and zonula occludens-1. Furthermore, H-HMW-SH restored the balance of intestinal flora in different intestinal contents (duodenum, jejunum, ileum, and colon) and feces of rats with IBS-C. Overall, our study illustrates the therapeutic potential of H-HMW-SH in the treatment of IBS-C.

Neuroimmune communication in allergic rhinitis

The prevalence rate of allergic rhinitis (AR) is high worldwide. The inhalation of allergens induces AR, which is an immunoglobulin E-mediated and type 2 inflammation-driven disease. Recently, the role of neuroimmune communication in AR pathogenesis has piqued the interest of the scientific community. Various neuropeptides, such as substance P (SP), vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU), released via "axon reflexes" or "central sensitization" exert regulatory effects on immune cells to elicit "neurogenic inflammation," which contributes to nasal hyperresponsiveness (NHR) in AR. Additionally, neuropeptides can be produced in immune cells. The frequent colocalization of immune and neuronal cells at certain anatomical regions promotes the establishment of neuroimmune cell units, such as nerve-mast cells, nerve-type 2 innate lymphoid cells (ILC2s), nerve-eosinophils and nerve-basophils units. Receptors expressed both on immune cells and neurons, such as TRPV1, TRPA1, and Mas-related G protein-coupled receptor X2 (MRGPRX2) mediate AR pathogenesis. This review focused on elucidating the mechanisms underlying neuroimmune communication in AR.

Sexually Dimorphic Effects of Histamine Degradation by Enteric Glial Histamine N-Methyltransferase (HNMT) on Visceral Hypersensitivity

Histamine is a neuromodulator that affects gut motility and visceral sensitivity through intrinsic and extrinsic neural pathways, yet the mechanisms regulating histamine availability in these pathways remain poorly understood. Here, we show that enteric glia contribute to histamine clearance in the enteric nervous system (ENS) through their expression of the enzyme histamine N-methyltransferase (HNMT). Glial HNMT expression was initially assessed using immunolabeling and gene expression, and functionally tested using CRISPR-Cas9 to create a Cre-dependent conditional Hnmt ablation model targeting glia. Immunolabeling, calcium imaging, and visceromotor reflex recordings were used to assess the effects on ENS structure and visceral hypersensitivity. Immunolabeling and gene expression data show that enteric neurons and glia express HNMT. Deleting Hnmt in Sox10+ enteric glia increased glial histamine levels and altered visceromotor responses to colorectal distension in male mice, with no effect in females. Interestingly, deleting glial Hnmt protected males from histamine-driven visceral hypersensitivity. These data uncover a significant role for glial HNMT in histamine degradation in the gut, which impacts histamine-driven visceral hypersensitivity in a sex-dependent manner. Changes in the capacity of glia to clear histamines could play a role in the susceptibility to developing visceral pain in disorders of the gut-brain interaction.

The Eph/ephrin system symphony of gut inflammation

The extent of gut inflammation depends largely on the gut barrier's integrity and enteric neuroimmune interactions. However, the factors and molecular mechanisms that regulate inflammation-related changes in the enteric nervous system (ENS) remain largely unexplored. Eph/ephrin signaling is critical for inflammatory response, neuronal activation, and synaptic plasticity in the brain, but its presence and function in the ENS have been largely unknown to date. This review discusses the critical role of Eph/ephrin in regulating gut homeostasis, inflammation, neuroimmune interactions, and pain pathways. Targeting the Eph/ephrin system offers innovative treatments for gut inflammation disorders, offering hope for enhanced patient prognosis, pain management, and overall quality of life.

Enteric neuro-immune interactions in intestinal health and disease

The enteric nervous system is an autonomous neuronal circuit that regulates many processes far beyond the peristalsis in the gastro-intestinal tract. This circuit, consisting of enteric neurons and enteric glial cells, can engage in many intercellular interactions shaping the homeostatic microenvironment in the gut. Perhaps the most well documented interactions taking place, are the intestinal neuro-immune interactions which are essential for the fine-tuning of oral tolerance. In the context of intestinal disease, compelling evidence demonstrates both protective and detrimental roles for this bidirectional neuro-immune signaling. This review discusses the different immune cell types that are recognized to engage in neuronal crosstalk during intestinal health and disease. Highlighting the molecular pathways involved in the neuro-immune interactions might inspire novel strategies to target intestinal disease.

New insights into intestinal macrophages in necrotizing enterocolitis: the multi-functional role and promising therapeutic application

Necrotizing enterocolitis (NEC) is an inflammatory intestinal disease that profoundly affects preterm infants. Currently, the pathogenesis of NEC remains controversial, resulting in limited treatment strategies. The preterm infants are thought to be susceptible to gut inflammatory disorders because of their immature immune system. In early life, intestinal macrophages (IMφs), crucial components of innate immunity, demonstrate functional plasticity and diversity in intestinal development, resistance to pathogens, maintenance of the intestinal barrier, and regulation of gut microbiota. When the stimulations of environmental, dietary, and bacterial factors interrupt the homeostatic processes of IMφs, they will lead to intestinal disease, such as NEC. This review focuses on the IMφs related pathogenesis in NEC, discusses the multi-functional roles and relevant molecular mechanisms of IMφs in preterm infants, and explores promising therapeutic application for NEC.

Gut Dysbiosis in Irritable Bowel Syndrome: A Narrative Review on Correlation with Disease Subtypes and Novel Therapeutic Implications

Irritable bowel syndrome (IBS) is a prevalent functional gastrointestinal disorder characterized by chronic abdominal pain and altered bowel habits. It can be subclassified in different subtypes according to the main clinical manifestation: constipation, diarrhea, mixed, and unclassified. Over the past decade, the role of gut microbiota in IBS has garnered significant attention in the scientific community. Emerging research spotlights the intricate involvement of microbiota dysbiosis in IBS pathogenesis. Studies have demonstrated reduced microbial diversity and stability and specific microbial alterations for each disease subgroup. Microbiota-targeted treatments, such as antibiotics, probiotics, prebiotics, synbiotics, fecal microbiota transplantation, and even diet, offer exciting prospects for managing IBS. However, definitive conclusions are hindered by the heterogeneity of these studies. Further research should focus on elucidating the mechanisms, developing microbiome-based diagnostics, and enabling personalized therapies tailored to an individual's microbiome profile. This review takes a deep dive into the microscopic world inhabiting our guts, and its implications for IBS. Our aim is to elucidate the complex interplay between gut microbiota and each IBS subtype, exploring novel microbiota-targeted treatments and providing a comprehensive overview of the current state of knowledge.

Current optimal pharmacologic therapies for overactive bladder

INTRODUCTION

Overactive bladder (OAB) is a common syndrome in adults. Current pharmacologic treatment includes antimuscarinic agents and β-3 adrenoceptor agonists. For non-responders to oral medication, intravesical injection of botulinum toxin A (BoNT-A) is an effective option. However, these treatments have potential adverse events and should be cautiously selected for appropriate patients. This review presents the recently published results of clinical trials and studies for patients with OAB and the underlying pathophysiology of OAB. Appropriate medical therapy based on pathophysiology of OAB is also presented.

AREAS COVERED

Literature search from Pubmed from 2001 to 2023 including clinical background, pharmacology, and clinical studies for OAB medications.

EXPERT OPINION

Treatment of OAB syndrome with any antimuscarinic or β-3 adrenoceptor agonist is feasible as a first-line approach. For patients with suboptimal therapeutic effect to full-dose antimuscarinics or mirabegron, combination with both drugs can improve efficacy. Intravesical BoNT-A 100-U injection provides therapeutic effects for refractory OAB. Patients who are refractory to initial pharmacotherapies should be investigated for the underlying pathophysiology; then an appropriate medication can be added, such as an α1-blocker or anti-inflammatory agents. Patient education about behavioral modification and therapies should always be provided with oral medication or BoNT-A injection for OAB patients.

Emerging role of the gut microbiome in post-infectious irritable bowel syndrome: A literature review

Post-infectious irritable bowel syndrome (PI-IBS) is a particular type of IBS, with symptom onset after an acute episode of infectious gastroenteritis. Despite infectious disease resolution and clearance of the inciting pathogen agent, 10% of patients will develop PI-IBS. In susceptible individuals, the exposure to pathogenic organisms leads to a marked shift in the gut microbiota with prolonged changes in host-microbiota interactions. These changes can affect the gut-brain axis and the visceral sensitivity, disrupting the intestinal barrier, altering neuromuscular function, triggering persistent low inflammation, and sustaining the onset of IBS symptoms. There is no specific treatment strategy for PI-IBS. Different drug classes can be used to treat PI-IBS similar to patients with IBS in general, guided by their clinical symptoms. This review summarizes the current evidence for microbial dysbiosis in PI-IBS and analyzes the available data regarding the role of the microbiome in mediating the central and peripheral dysfunctions that lead to IBS symptoms. It also discusses the current state of evidence on therapies targeting the microbiome in the management of PI-IBS. The results of microbial modulation strategies used in relieving IBS symptomatology are encouraging. Several studies on PI-IBS animal models reported promising results. However, published data that describe the efficacy and safety of microbial targeted therapy in PI-IBS patients are scarce. Future research is required.

Piezo2 regulates colonic mechanical sensitivity in a sex specific manner in mice

The mechanosensitive ion channel Piezo2 in mucosa and primary afferents transduces colonic mechanical sensation. Here we show that chemogenetic activation or nociceptor-targeted deletion of Piezo2 is sufficient to regulate colonic mechanical sensitivity in a sex dependent manner. Clozapine N-oxide-induced activation of Piezo2;hM3Dq-expressing sensory neurons evokes colonic hypersensitivity in male mice, and causes dyspnea in female mice likely due to effects on lung sensory neurons. Activation of Piezo2-expressing colonic afferent neurons also induces colonic hypersensitivity in male but not female mice. Piezo2 levels in nociceptive neurons are higher in female than in male mice. We also show that Piezo2 conditional deletion from nociceptive neurons increases body weight growth, slows colonic transits, and reduces colonic mechanosensing in female but not male mice. Piezo2 deletion blocks colonic hypersensitivity in male but not female mice. These results suggest that Piezo2 in nociceptive neurons mediates innocuous colonic mechanosensing in female mice and painful sensation in male mice, suggesting a sexual dimorphism of Piezo2 function in the colonic sensory system.

[Neuroimmunology of allergic rhinitis : Part 1: Cellular and humoral basic principles]

Allergic rhinitis (AR) is a very common disease with a high prevalence worldwide. It is an IgE-mediated type 2 inflammatory disease following exposure to inhalant allergens. A multitude of different neuropeptides including substance P, vasoactive intestinal peptide (VIP), calcitonin gene-related peptide (CGRP), nerve growth factor (NGF), and neuromedin U (NMU) can be released via peripheral axon or central reflexes, interact with immune cells, and thus contribute to neurogenic inflammation which causes the nasal hyperreactivity (NHR) characteristic of AR. Independent production of neuroendocrine hormones and neuropeptides by immune cells has also been demonstrated. Neuro-immune cell units arise when immune and neuronal cells colocalize, for which typical anatomic regions are, e.g., the mast cell-nerve functional unit. The focus of this review is the elucidation of neuroimmune communication mechanisms in AR.

Understanding neuroimmune interactions in disorders of gut-brain interaction: from functional to immune-mediated disorders

Functional gastrointestinal disorders-recently renamed into disorders of gut-brain interaction-such as irritable bowel syndrome and functional dyspepsia are highly prevalent conditions with bothersome abdominal symptoms in the absence of structural abnormalities. While traditionally considered as motility disorders or even psychosomatic conditions, our understanding of the pathophysiology has evolved significantly over the last two decades. Initial observations of subtle mucosal infiltration with immune cells, especially mast cells and eosinophils, are since recently being backed up by mechanistic evidence demonstrating increased release of nociceptive mediators by immune cells and the intestinal epithelium. These mediators can activate sensitised neurons leading to visceral hypersensitivity with bothersome symptoms. The interaction between immune activation and an impaired barrier function of the gut is most likely a bidirectional one with alterations in the microbiota, psychological stress and food components as upstream players in the pathophysiology. Only few immune-targeting treatments are currently available, but an improved understanding through a multidisciplinary scientific approach will hopefully identify novel, more precise treatment targets with ultimately better outcomes.

Involvement of acid sensing ion channel (ASIC)-3 in an acute urinary bladder-colon cross sensitization model in rodent

Introduction

Irritable bowel syndrome and bladder pain syndrome are both characterized by pain in response to organ distension. Epidemiologic studies showed that these two syndromes are often overlapped. Such overlap may be due to sharing of common extrinsic innervations between the colorectum and the urinary bladder, where cross-sensitization of the urinary bladder and the colon would occur in response to mechanical distension of either organ. The aim of this project was to develop and characterize a rodent model of urinary bladder-colon sensitization and to assess the role of the acid sensing ion channel (ASIC)-3.

Methods

Double retrograde labelling was performed to identify extrinsic primary afferent neurons innervating both the colon (Fluororuby) and urinary bladder (Fluorogold) in the L6-S1 dorsal root ganglia (DRG) in Sprague Dawley rats. The phenotype of the colon/urinary bladder co-innervating primary afferent neurons was assessed using immunohistochemistry directed against ASIC-3. Cross-organ sensitization was induced in Sprague Dawley rats by using an echography-guided intravesical administration of acetic acid (0.75%) under brief isoflurane anesthesia. Colonic sensitivity was assessed in conscious rats by measuring abdominal contraction during isobaric colorectal distension (CRD). Measurement of urinary bladder and colonic paracellular permeabilities and tissue myeloperoxidase assay were performed. The involvement of ASIC-3 was assessed by use of S1 intrathecal administration of the ASIC-3 blocker, APETx2 (2.2 µM).

Results

Immunohistochemistry showed that 73.1% of extrinsic primary afferent neurons co-innervating the colon and the urinary bladder express ASIC-3. By contrast, extrinsic primary afferent neurons innervating the colon only or the urinary bladder only were positive for ASIC-3 in 39.3% and 42.6%, respectively. Echography-guided intravesical administration of acetic acid resulted in colonic hypersensitivity to colorectal distension. This effect started 1 h post-injection and lasted up to 24 h, and was not longer seen after 3 days after injection. No colonic hyperpermeability and no difference in urinary bladder and colon MPO activity was observed between control and acetic acid-treated rats. Colonic sensitization by intravesical acetic acid administration was prevented by S1 intrathecal administration of APETx2.

Conclusion

We developed an acute pelvic cross-organ sensitization model in conscious rat. In this model, cross-organ sensitization is likely to involve S1-L6 extrinsic primary afferents co-innervating the colon and urinary bladder through an ASIC-3 pathway.

Biomimetic cell membrane-coated poly(lactic-co-glycolic acid) nanoparticles for biomedical applications

Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) are commonly used for drug delivery because of their favored biocompatibility and suitability for sustained and controlled drug release. To prolong NP circulation time, enable target-specific drug delivery and overcome physiological barriers, NPs camouflaged in cell membranes have been developed and evaluated to improve drug delivery. Here, we discuss recent advances in cell membrane-coated PLGA NPs, their preparation methods, and their application to cancer therapy, management of inflammation, treatment of cardiovascular disease and control of infection. We address the current challenges and highlight future research directions needed for effective use of cell membrane-camouflaged NPs.

Colonic motility adjustments in acute and chronic DSS-induced colitis

AIMS

Inflammatory bowel disease is recurrent inflammation that affects the gastrointestinal tract causing changes in intestinal motility. The evolution of these changes is not completely understood. The aim of this study was to evaluate anatomical and functional changes in the colon during the development of acute and chronic DSS-induced ulcerative colitis (UC) in C57Bl/6 mice.

MATERIALS AND METHODS

Mice were relocated into 5 groups: control (GC) and groups exposed to DSS 3 % for 2 (DSS2d), 5 (DSS5d) and 7 DSS7d) days (acute UC) or 3 cycles (DSS3C; Chronic UC). Mice were monitored daily. After euthanasia, colonic tissue was assessed with histological, immunofluorescence and colon manometry methods.

KEY FINDINGS

Ulcerative Colitis is a chronic disease characterized by overt inflammation of the colon. Here we investigate whether the morphological changes caused by UC in the colonic wall, in tuft cells and in enteric neurons also promote any alteration in colonic motility patterns. UC Promotes thickening in the colonic wall, fibrosis, reduction in the number of tuft cells and consequently goblet cells also, without promoting neuronal death however there is a change in the chemical code of myenteric neurons. All of these morphological changes were responsible for causing a change in colonic contractions, colonic migration motor complex, total time of gastrointestinal transit and therefore promoting dysmotility. Further studies stimulating a hyperplasia of tuft cells may be the way to try to keep the colonic epithelium healthy, reducing the damage caused by UC.

SIGNIFICANCE

Increasing disease pathology of DSS-induced UC induces structural and neuroanatomical changes and driven damage to cholinergic neurons causes colonic dysmotility, including increase of cholinergic myenteric neurons, followed by variations in the motility pattern of different regions of the colon that taking together characterize colonic dysmotility.

The Prevalence of Irritable Bowel Syndrome after Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Their Association: A Systematic Review and Meta-Analysis of Observational Studies

AIM

Investigate the prevalence of irritable bowel syndrome (IBS) after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and assess the association between IBS and SARS-CoV-2 infection.

METHODS

A systematic literature search for PubMed, Web of Science, Embase, Scopus, and the Cochrane Library was performed to identify all reports published before 31 December 2022. The confidence interval (CI), estimation effect (ES) of prevalence, and risk ratios (RR) were calculated to evaluate the prevalence of IBS after SARS-CoV-2 infection and their association. Individual results were pooled by the random-effects (RE) model. Subgroup analyses conducted a further investigation of the results. We employed funnel plots, Egger's test, and Begg's test to evaluate publication bias. Sensitivity analysis was performed for the assessment of the robustness of the result.

RESULTS

The data on IBS prevalence after SARS-CoV-2 infection were extracted from two cross-sectional studies and ten longitudinal studies from nineteen countries with 3950 individuals. The IBS prevalence after SARS-CoV-2 infection ranges from 3% to 91% in different countries, and the overall pooled prevalence of IBS following SARS-CoV-2 infection is 15% (ES: 0.15; 95% CI, 0.11-0.20; p = 0.000). The data on the association between IBS and SARS-CoV-2 infection were extracted from six cohort studies from fifteen countries with 3595 individuals. The risk of IBS increased following SARS-CoV-2 infection but was not significant (RR: 1.82; 95% CI, 0.90-3.69; p = 0.096).

CONCLUSIONS

In conclusion, the overall pooled prevalence of IBS following SARS-CoV-2 infection was 15%, and SARS-CoV-2 infection increased the overall risk of IBS but was not statistically significant. Further extra high-quality epidemiological evidence and studies to clarify the underlying mechanism of IBS following SARS-CoV-2 infection are needed.

Twin-bioengine self-adaptive micro/nanorobots using enzyme actuation and macrophage relay for gastrointestinal inflammation therapy

A wide array of biocompatible micro/nanorobots are designed for targeted drug delivery and precision therapy largely depending on their self-adaptive ability overcoming complex barriers in vivo. Here, we report a twin-bioengine yeast micro/nanorobot (TBY-robot) with self-propelling and self-adaptive capabilities that can autonomously navigate to inflamed sites for gastrointestinal inflammation therapy via enzyme-macrophage switching (EMS). Asymmetrical TBY-robots effectively penetrated the mucus barrier and notably enhanced their intestinal retention using a dual enzyme-driven engine toward enteral glucose gradient. Thereafter, the TBY-robot was transferred to Peyer's patch, where the enzyme-driven engine switched in situ to macrophage bioengine and was subsequently relayed to inflamed sites along a chemokine gradient. Encouragingly, EMS-based delivery increased drug accumulation at the diseased site by approximately 1000-fold, markedly attenuating inflammation and ameliorating disease pathology in mouse models of colitis and gastric ulcers. These self-adaptive TBY-robots represent a safe and promising strategy for the precision treatment of gastrointestinal inflammation and other inflammatory diseases.

Inhibition of Canonical Transient Receptor Potential Channels 4/5 with Highly Selective and Potent Small-Molecule HC-070 Alleviates Mechanical Hypersensitivity in Rat Models of Visceral and Neuropathic Pain

Transient receptor potential channels C4/C5 are widely expressed in the pain pathway. Here, we studied the putative analgesic efficacy of the highly selective and potent TRPC4/C5 antagonist HC-070 in rats. Inhibitory potency on human TRPC4 was assessed by using the whole-cell manual patch-clamp technique. Visceral pain sensitivity was assessed by the colonic distension test after intra-colonic trinitrobenzene sulfonic acid injection and partial restraint stress. Mechanical pain sensitivity was assessed by the paw pressure test in the chronic constriction injury (CCI) neuropathic pain model. We confirm that HC-070 is a low nanomolar antagonist. Following single oral doses (3-30 mg/kg in male or female rats), colonic hypersensitivity was significantly and dose-dependently attenuated, even fully reversed to baseline. HC-070 also had a significant anti-hypersensitivity effect in the established phase of the CCI model. HC-070 did not have an effect on the mechanical withdrawal threshold of the non-injured paw, whereas the reference compound morphine significantly increased it. Analgesic effects are observed at unbound brain concentrations near the 50% inhibitory concentration (IC₅₀) recorded in vitro. This suggests that analgesic effects reported here are brought about by TRPC4/C5 blocking in vivo. The results strengthen the idea that TRPC4/C5 antagonism is a novel, safe non-opioid treatment for chronic pain.

Evaluation of the toxicity of di-iso-pentyl-phthalate (DiPeP) using the fish Danio rerio as an experimental model

The presence of phthalates constitutes a risk to the health of aquatic environments and organisms. This work aimed to evaluate the toxic effects of di-iso-pentyl-phthalate (DiPeP) at environmentally relevant concentrations of 5, 25, and 125 µg/L in Danio rerio after subchronic exposure for 14 days. DiPeP altered the antioxidant system in the liver (125 μg/L), intestine (25 μg/L), brain, and gills in all concentrations tested. In animals exposed to 125 μg/L, DNA damage was identified in the gills. In addition, loss of cell boundary of hepatocytes, vascular congestion, necrosis in the liver, and presence of immune cells in the intestinal lumen were observed. Erythrocytic nuclear alterations in the blood occurred in animals exposed to 25 μg/L. DiPeP was quantified in muscle tissue at all exposure concentrations, appearing in a concentration-dependent manner. Contaminants such as DiPeP will still be used for a long time, mainly by industries, being a challenge for industry versus environmental health.

Identification of Potential Visceral Pain Biomarkers in Colon Exudates from Mice with Experimental Colitis: An Exploratory In Vitro Study

Chronic visceral pain (CVP) is extremely difficult to diagnose, and available analgesic treatment options are quite limited. Identifying the proteins secreted from the colonic nociceptors, or their neighbor cells within the tube walls, in the context of disorders that course with visceral pain, might be useful to decipher the mechanism involved in the establishment of CVP. Addressing this question in human with gastrointestinal disorders entails multiple difficulties, as there is not a clear classification of disease severity, and colonic secretion is not easy to manage. We propose using of a murine model of colitis to identify new algesic molecules and pathways that could be explored as pain biomarkers or analgesia targets. Descending colons from naïve and colitis mice with visceral hyperalgesia were excised and maintained ex vivo. The proteins secreted in the perfusion fluid before and during acute noxious distension were evaluated using high-resolution mass spectrometry (MS). Haptoglobin (Hp), PZD and LIM domain protein 3 (Pdlim3), NADP-dependent malic enzyme (Me1), and Apolipoprotein A-I (Apoa1) were increased during visceral insult, whilst Triosephosphate isomerase (Tpi1), Glucose-6-phosphate isomerase (Gpi1), Alpha-enolase (Eno1), and Isoform 2 of Tropomyosin alpha-1 chain (Tpm1) were decreased. Most identified proteins have been described in the context of different chronic pain conditions and, according to gene ontology analysis, they are also involved in diverse biological processes of relevance. Thus, animal models that mimic human conditions in combination with unbiased omics approaches will ultimately help to identify new pathophysiological mechanisms underlying pain that might be useful in diagnosing and treating pain. PERSPECTIVE: Our study utilizes an unbiased proteomic approach to determine, first, the clinical relevance of a murine model of colitis and, second, to identify novel molecules/pathways involved in nociception that would be potential biomarkers or targets for chronic visceral pain.

Targeting the endocannabinoid system for the treatment of abdominal pain in irritable bowel syndrome

The management of visceral pain in patients with disorders of gut-brain interaction, notably irritable bowel syndrome, presents a considerable clinical challenge, with few available treatment options. Patients are increasingly using cannabis and cannabinoids to control abdominal pain. Cannabis acts on receptors of the endocannabinoid system, an endogenous system of lipid mediators that regulates gastrointestinal function and pain processing pathways in health and disease. The endocannabinoid system represents a logical molecular therapeutic target for the treatment of pain in irritable bowel syndrome. Here, we review the physiological and pathophysiological functions of the endocannabinoid system with a focus on the peripheral and central regulation of gastrointestinal function and visceral nociception. We address the use of cannabinoids in pain management, comparing them to other treatment modalities, including opioids and neuromodulators. Finally, we discuss emerging therapeutic candidates targeting the endocannabinoid system for the treatment of pain in irritable bowel syndrome.

Astragalus Polysaccharide Alleviates Constipation in the Elderly Via Modification of Gut Microbiota and Fecal Metabolism

Constipation is one of the most common gastrointestinal disorders, whose incidence increasing with age. As one of the main components, Astragalus polysaccharide (APS) has been used to treat a variety of diseases. This study aimed to explore the effects of APS on the improvement of gastrointestinal functions and learning memory in elderly rats with constipation. In this study, both 16S rRNA sequencing-based microbiome and ¹H NMR-based metabolomics were applied to demonstrate the effects of APS on host metabolism and gut microbiota of the elderly rats with constipation. On top of this, we constructed both inter- and inner-layer networks, intuitively showing the correlations among behavioral indicators, intestinal bacteria, and differential metabolites. Our results showed that APS significantly ameliorated the constipation and the cognitive dysfunctions of rats. Microbiome analysis revealed that APS raised the relative abundance of Blautia, whereas decreased the relative abundance of Lactobacillus in the elderly rats with constipation. In addition, APS decreased the levels of acetate, butyrate, and propionate in the fecal samples, correspondingly regulating glycolysis/gluconeogenesis metabolism and pyruvate metabolism. These findings lay solid foundations for understanding the pathogenesis of constipation in the elderly, and also offer a promising new treatment strategy for constipation in the elderly.

Neonatal development of intestinal neuroimmune interactions

Interactions between the enteric nervous system (ENS), immune system, and gut microbiota regulate intestinal homeostasis in adults, but their development and role(s) in early life are relatively underexplored. In early life, these interactions are dynamic, because the mucosal immune system, microbiota, and the ENS are developing and influencing each other. Moreover, disrupting gut microbiota and gut immune system development, and potentially ENS development, by early-life antibiotic exposure increases the risk of diseases affecting the gut. Here, we review the development of the ENS and immune/epithelial cells, and identify potential critical periods for their interactions and development. We also highlight knowledge gaps that, when addressed, may help promote intestinal homeostasis, including in the settings of early-life antibiotic exposure.

Nerves in gastrointestinal cancer: from mechanism to modulations

Maintenance of gastrointestinal health is challenging as it requires balancing multifaceted processes within the highly complex and dynamic ecosystem of the gastrointestinal tract. Disturbances within this vibrant environment can have detrimental consequences, including the onset of gastrointestinal cancers. Globally, gastrointestinal cancers account for ~19% of all cancer cases and ~22.5% of all cancer-related deaths. Developing new ways to more readily detect and more efficiently target these malignancies are urgently needed. Whereas members of the tumour microenvironment, such as immune cells and fibroblasts, have already been in the spotlight as key players of cancer initiation and progression, the importance of the nervous system in gastrointestinal cancers has only been highlighted in the past few years. Although extrinsic innervations modulate gastrointestinal cancers, cells and signals from the gut's intrinsic innervation also have the ability to do so. Here, we shed light on this thriving field and discuss neural influences during gastrointestinal carcinogenesis. We focus on the interactions between neurons and components of the gastrointestinal tract and tumour microenvironment, on the neural signalling pathways involved, and how these factors affect the cancer hallmarks, and discuss the neural signatures in gastrointestinal cancers. Finally, we highlight neural-related therapies that have potential for the management of gastrointestinal cancers.

Distinctions Between Fecal and Intestinal Mucosal Microbiota in Subgroups of Irritable Bowel Syndrome

BACKGROUND AND AIMS

Recent studies have shown that changes in the intestinal microbiota contribute to the pathogenesis of irritable bowel syndrome (IBS). This study aimed to investigate the characteristics of the fecal and intestinal mucosal microbiota in IBS patients, and the correlation between microbiota and clinical manifestations.

METHODS

Fecal and intestinal mucosal samples were collected from 14 constipation-predominant IBS (IBS-C) patients, 20 diarrhea-predominant IBS (IBS-D) patients, and 20 healthy controls (HCs). 16S rRNA gene sequencing and fluorescence in situ hybridization were used for the analysis of samples.

RESULTS

Community richness and diversity of the fecal microbiota in IBS patients were significantly reduced compared with the HCs. The mucosal samples in IBS patients showed decreased Bifidobacterium and increased Bacteroides caccae compared with HCs; Eubacterium and Roseburia were decreased in IBS-C patients and increased in IBS-D patients. A comparison of the fecal and mucosal microbiota in IBS patients showed significantly increased Bifidobacterium in fecal samples and a decrease in mucosal samples in IBS-C patients; Bacteroides caccae and Roseburia were significantly reduced in fecal samples and increased in mucosal samples of IBS patients. A correlation between microbiota and clinical manifestations in IBS patients showed that Bacteroides caccae and Roseburia in fecal samples and Bifidobacterium and Eubacterium in mucosal samples were associated with abdominal pain and distention.

CONCLUSIONS

Distinct differences exist between the fecal and intestinal mucosal microbiota in IBS patients, with the changes in the latter appearing more consistent with the pathophysiology of IBS. Changes in intestinal microbiota were associated with the clinical manifestations in IBS.

Gut reactions: emerging mechanisms of abdominal pain from food intake

Abdominal pain, which is a form of visceral pain, is a highly prevalent symptom worldwide frequently occurring following food ingestion. Its pathophysiology is complex, and many factors, including intestinal environmental cues, the immune system, or the molecular composition of foods, can influence the development of postprandial abdominal pain. Because of the poor efficacy of drug treatments, current strategies are often limited to the exclusion of culprit food(s) from the diet. However, there are two important limitations to this approach. First, patients suffering from food-induced abdominal pain usually recognize several food items as the cause of their gastrointestinal symptoms. Second, not all offending foods can always be identified by these patients. Newly identified mechanisms involving neuroimmune interactions and their communication with the intestinal microbiota shed light on the development of new therapeutic strategies. In this Mini-Review, these novel mechanisms and relevance of such findings are highlighted.

Neonatal antibiotics have long term sex-dependent effects on the enteric nervous system

Infants and young children receive the highest exposures to antibiotics globally. Although there is building evidence that early life exposure to antibiotics increases susceptibility to various diseases including gut disorders later in life, the lasting impact of early life antibiotics on the physiology of the gut and its enteric nervous system (ENS) remains unclear. We treated neonatal mice with the antibiotic vancomycin during their first 10 postnatal days, then examined potential lasting effects of the antibiotic treatment on their colons during young adulthood (6 weeks old). We found that neonatal vancomycin treatment disrupted the gut functions of young adult female and male mice differently. Antibiotic-exposed females had significantly longer whole gut transit while antibiotic-treated males had significantly lower faecal weights compared to controls. Both male and female antibiotic-treated mice had greater percentages of faecal water content. Neonatal vancomycin treatment also had sexually dimorphic impacts on the neurochemistry and Ca2+ activity of young adult myenteric and submucosal neurons. Myenteric neurons of male mice were more disrupted than those of females, while opposing changes in submucosal neurons were seen in each sex. Neonatal vancomycin also induced sustained changes in colonic microbiota and lasting depletion of mucosal serotonin (5-HT) levels. Antibiotic impacts on microbiota and mucosal 5-HT were not sex-dependent, but we propose that the responses of the host to these changes are sex-specific. This first demonstration of long-term impacts of neonatal antibiotics on the ENS, gut microbiota and mucosal 5-HT has important implications for gut function and other physiological systems of the host. KEY POINTS: Early life exposure to antibiotics can increase susceptibility to diseases including functional gastrointestinal (GI) disorders later in life. Yet, the lasting impact of this common therapy on the gut and its enteric nervous system (ENS) remains unclear. We investigated the long-term impact of neonatal antibiotic treatment by treating mice with the antibiotic vancomycin during their neonatal period, then examining their colons during young adulthood. Adolescent female mice given neonatal vancomycin treatment had significantly longer whole gut transit times, while adolescent male and female mice treated with neonatal antibiotics had significantly wetter stools. Effects of neonatal vancomycin treatment on the neurochemistry and Ca2+ activity of myenteric and submucosal neurons were sexually dimorphic. Neonatal vancomycin also had lasting effects on the colonic microbiome and mucosal serotonin biosynthesis that were not sex-dependent. Different male and female responses to antibiotic-induced disruptions of the ENS, microbiota and mucosal serotonin biosynthesis can lead to sex-specific impacts on gut function.

Brief Maternal Separation Promotes Resilience to Anxiety-like and Depressive-like Behaviors in Female C57BL/6J Offspring with Imiquimod-Induced Psoriasis

Background: Psoriasis is a common chronic inflammatory skin disease that often causes depression. Early life experience affects brain development and relates to depression. Whether the effect of different MS protocols in early life on anxiety-like and depressive-like behaviors in female offspring with imiquimod (IMQ)-induced psoriasis is unknown. Methods: C57BL/6J mice were subjected to no separation (NMS), brief MS (15 min/day, MS15) or long MS (180 min/day, MS180) from postpartum days (PPD) 1 to PPD21. Then, 5% imiquimod cream was applied for 8 days in adults. Behavioral tests, skin lesions and hippocampal protein expression were also assessed. Results: We found significant psoriasis-like skin lesions in female mice following IMQ application, and mice showed anxiety-like and depressive-like behaviors. Further, increased microglial activation and decreased expression of neuroplasticity were detected in mice following IMQ application. However, after MS15 in early life, mice showed decreased anxiety-like and depressive-like behaviors, indicating resilience. Further, inhibited hippocampal neuroinflammation and increased neuroplasticity were detected. Conclusions: Collectively, this study confirms that brief MS confers resilience to the behavior deficits in female offspring with IMQ-induced psoriasis and reverses the activation of neuroinflammation and the damage of neuroplasticity injury.

A syngeneic inoculation mouse model of endometriosis that develops multiple comorbid visceral and cutaneous pain like behaviours

ABSTRACT

Endometriosis is a chronic and debilitating condition, commonly characterised by chronic pelvic pain (CPP) and infertility. Chronic pelvic pain can be experienced across multiple pelvic organs, with comorbidities commonly effecting the bowel, bladder, and vagina. Despite research efforts into endometriosis pathophysiology, little is known about how endometriosis induces CPP, and as such, therapeutic interventions are lacking. The aim of this study was to characterise a syngeneic mouse model of endometriosis that mimics naturally occurring retrograde menstruation, thought to precede endometriosis development in patients, and determine whether these mice exhibit signs of CPP and altered behaviour. We characterised the development of endometriosis over 10 weeks following uterine tissue inoculation, measured in vivo and ex vivo hypersensitivity to mechanical stimuli across multiple visceral organs, and assessed alterations in animal spontaneous behaviour. We confirmed that inoculated uterine horn tissue formed into endometriosis lesions throughout the peritoneal cavity, with significant growth by 8 to 10 weeks post inoculation. Additionally, we found that mice with fully developed endometriosis displayed hypersensitivity evoked by (1) vaginal distension, (2) colorectal distension, (3) bladder distension, and (4) cutaneous thermal stimulation, compared to their sham counterparts. Moreover, endometriosis mice displayed alterations in spontaneous behaviour indicative of (5) altered bladder function and (6) anxiety. This model creates a foundation for mechanistical studies into the diffuse CPP associated with endometriosis and the development of targeted therapeutic interventions to improve the quality of life of women with endometriosis.

Circulating Pro-inflammatory Cytokines Do Not Explain Interindividual Variability in Visceral Sensitivity in Healthy Individuals

A role of the immune system in the pathophysiology of pain and hyperalgesia has received growing attention, especially in the context of visceral pain and the gut-brain axis. While acute experimental inflammation can induce visceral hyperalgesia as part of sickness behavior in healthy individuals, it remains unclear if normal plasma levels of circulating pro-inflammatory cytokines contribute to interindividual variability in visceral sensitivity. We herein compiled data from a tightly screened and well-characterized sample of healthy volunteers (N = 98) allowing us to assess associations between visceral sensitivity and gastrointestinal symptoms, and plasma concentrations of three selected pro-inflammatory cytokines (i.e., TNF-α, IL-6, and IL-8), along with cortisol and stress-related psychological variables. For analyses, we compared subgroups created to have distinct pro-inflammatory cytokine profiles, modelling healthy individuals at putative risk or resilience, respectively, for symptoms of the gut-brain axis, and compared them with respect to rectal sensory and pain thresholds and subclinical GI symptoms. Secondly, we computed multiple regression analyses to test if circulating pro-inflammatory markers predict visceral sensitivity in the whole sample. Despite pronounced subgroup differences in pro-inflammatory cytokine and cortisol concentrations, we observed no differences in measures of visceroception. In regression analyses, cytokines did not emerge as predictors. The pain threshold was predicted by emotional state and trait variables, especially state anxiety, together explaining 10.9% of the variance. These negative results do not support the hypothesis that systemic cytokine levels contribute to normal interindividual variability in visceroception in healthy individuals. Trajectories to visceral hyperalgesia as key marker in disorders of gut-brain interactions likely involve complex interactions of biological and psychological factors in keeping with a psychosocial model. Normal variations in systemic cytokines do not appear to constitute a vulnerability factor in otherwise healthy individuals, calling for prospective studies in at risk populations.

Bifidobacterium lactis TY-S01 Prevents Loperamide-Induced Constipation by Modulating Gut Microbiota and Its Metabolites in Mice

Probiotics have received widespread attention as a healthy ingredient. The preventive effect of Bifidobacterium lactis TY-S01 on loperamide-induced constipation in mice was investigated in this study. TY-S01 accelerated the peristalsis of intestine, maintained the humidity of faeces, and prevented the destruction of gut barrier. TY-S01 also maintained the 5-HT, MTL and SP at normal levels in constipated mice. Simultaneously, TY-S01 up-regulated the mRNA expressions of 5-HT4R, SERT, and MUC-2, while down-regulated the mRNA expressions of pro-inflammatory genes remarkably. The levels of short-chain fatty acids in the feces of constipated mice were also increased because of the intervention with TY-S01. Moreover, TY-S01 prevented gut microbiological dysbiosis in constipated mice. Spearman’s correlation analysis revealed that there was an obvious association between metabolic biomarkers and gut microbiota. In summary, TY-S01 regulated gut microbiota and the production of intestinal metabolites to prevent loperamide-induced constipation.

The Risk of Developing Alzheimer's Disease and Parkinson's Disease in Patients with Inflammatory Bowel Disease: A Meta-Analysis

Recently, a growing body of research has linked gut microbiota dysbiosis to central nervous system diseases, such as Alzheimer’s disease (AD) and Parkinson’s disease (PD), and has suggested that AD and PD pathology may take its origin from chronic inflammation in the gastrointestinal tract. Thus, this study aimed to elucidate whether inflammatory bowel disease (IBD) is associated with a higher risk of developing AD and PD as compared to the non-IBD population by conducting a meta-analysis. A thorough search of Pubmed and Embase databases was performed to identify all relevant articles. The quality of included studies was assessed using the Newcastle-Ottawa Scale. The odds ratios (ORs) with 95% confidence intervals (CIs) were analyzed using a fixed-effect model. To assess publication bias and heterogeneity among the studies, Egger’s test and L’Abbé plots were used, respectively. A total of eight eligible studies were included in this meta-analysis. No significant heterogeneity or significant publication bias was detected. The risk of developing AD in IBD patients was higher than in non-IBD patients (OR = 0.37; 95% CI = 0.14−1.00; p = 0.05), and there was a relationship between the occurrence of AD and Crohn’s disease or ulcerative colitis (OR = 0.11; 95% CI = 0.04−0.30; p < 0.0001, OR = 0.14; 95% CI = 0.04−0.49; p = 0.0024, respectively). The risk of developing both of the most common neurodegenerative diseases, AD and PD, was also significantly higher in patients diagnosed with Crohn’s disease or ulcerative colitis (OR = 0.21; 95% CI = 0.09−0.49; p = 0.0003, OR = 0.25; 95% CI = 0.13−0.51; p = 0.0001, respectively). This meta-analysis revealed a higher risk of AD and PD among CD and UC patients compared to the general population. It may suggest a key role for the gut microbiota in the pathogenesis of not only Crohn’s disease and ulcerative colitis but also AD and PD. The identification of this potential risk may provide earlier preventive measures to be implemented to reduce comorbidity and mortality rate.

Metabolomics: The Key to Unraveling the Role of the Microbiome in Visceral Pain Neurotransmission

Inflammatory bowel disease (IBD), comprising Crohn’s disease and Ulcerative colitis, is a relapsing and remitting disease of the gastrointestinal tract, presenting with chronic inflammation, ulceration, gastrointestinal bleeding, and abdominal pain. Up to 80% of patients suffering from IBD experience acute pain, which dissipates when the underlying inflammation and tissue damage resolves. However, despite achieving endoscopic remission with no signs of ongoing intestinal inflammation or damage, 30–50% of IBD patients in remission experience chronic abdominal pain, suggesting altered sensory neuronal processing in this disorder. Furthermore, effective treatment for chronic pain is limited such that 5–25% of IBD outpatients are treated with narcotics, with associated morbidity and mortality. IBD patients commonly present with substantial alterations to the microbial community structure within the gastrointestinal tract, known as dysbiosis. The same is also true in irritable bowel syndrome (IBS), a chronic disorder characterized by altered bowel habits and abdominal pain, in the absence of inflammation. An emerging body of literature suggests that the gut microbiome plays an important role in visceral hypersensitivity. Specific microbial metabolites have an intimate relationship with host receptors that are highly expressed on host cell and neurons, suggesting that microbial metabolites play a key role in visceral hypersensitivity. In this review, we will discuss the techniques used to analysis the metabolome, current potential metabolite targets for visceral hypersensitivity, and discuss the current literature that evaluates the role of the post-inflammatory microbiota and metabolites in visceral hypersensitivity.

Expression of TRP Channels in Colonic Mucosa of IBS-D Patients and Its Correlation with the Severity of the Disease

Aim

Lots of researches have endeavored to elucidate the pathogenetic mechanism of visceral hypersensitivity in order to guide the therapy of diarrhea predominant-irritable bowel syndrome (IBS-D). Transient receptor potential (TRP) channels and their role in visceral nociception have been vastly investigated. We investigated the expression of TRP channels in IBS-D colonic biopsies and its correlation with the severity of the disease.

Methods

Sigmoid biopsies were obtained from 34 IBS-D patients and 28 healthy controls (HCs). IBS-D was diagnosed according to Rome IV criteria. Their clinical parameters were assessed through questionnaires. Expression of TRPV1, TRPV4, TRPA1, TRPM2, and TRPM8 was evaluated with immunohistology staining.

Results

Expression levels of TRPV1, TRPV4, and TRPA1 in the colonic mucosa of IBS-D patients were significantly higher than those in HCs (p < 0.05), while there was no obvious difference of TRPM2 and TRPM8 expression between IBS-D patients and HCs. In addition, the expression levels of TRPV1 and TRPA1, but TRPV4, in the colonic mucosa correlated positively with the severity of diseases (r = 0.6303 and 0.4506, respectively, p < 0.05).

Conclusions

Expression of TRPV1, TRPA1, and TRPV4 in the colonic mucosa was enhanced in IBS-D patients compared with HCs with the former two correlated with the severity of the disease. TRP channels might be promising biomarkers in the diagnosis and estimate of the severity in IBS-D.

Eosinophils in the Gastrointestinal Tract: Key Contributors to Neuro-Immune Crosstalk and Potential Implications in Disorders of Brain-Gut Interaction

Eosinophils are innate immune granulocytes actively involved in defensive responses and in local and systemic inflammatory processes. Beyond these effector roles, eosinophils are fundamental to maintaining homeostasis in the tissues they reside. Gastrointestinal eosinophils modulate barrier function and mucosal immunity and promote tissue development through their direct communication with almost every cellular component. This is possible thanks to the variety of receptors they express and the bioactive molecules they store and release, including cytotoxic proteins, cytokines, growth factors, and neuropeptides and neurotrophines. A growing body of evidence points to the eosinophil as a key neuro-immune player in the regulation of gastrointestinal function, with potential implications in pathophysiological processes. Eosinophil–neuron interactions are facilitated by chemotaxis and adhesion molecules, and the mediators released may have excitatory or inhibitory effects on each cell type, with physiological consequences dependent on the type of innervation involved. Of special interest are the disorders of the brain–gut interaction (DBGIs), mainly functional dyspepsia (FD) and irritable bowel syndrome (IBS), in which mucosal eosinophilia and eosinophil activation have been identified. In this review, we summarize the main roles of gastrointestinal eosinophils in supporting gut homeostasis and the evidence available on eosinophil–neuron interactions to bring new insights that support the fundamental role of this neuro-immune crosstalk in maintaining gut health and contributing to the pathophysiology of DBGIs.

Integrated analysis of fish intestine biomarkers: Complementary tools for pollution assessment

The gastrointestinal tract and its enteric nervous system are the first routes of food and xenobiotics uptake. Considering the importance of this organ, this study evaluated intestinal biomarkers of Sphoeroides testudineus integrating the data to generate tools for pollution assessment. The fish were collected in three sites of São Paulo Coast and their intestines were analyzed for biochemical, histology, and neuronal density and morphometry biomarkers. To evaluate the differences among the data, a PERMANOVA was applied, followed by a FA/PCA. The PERMANOVA indicated differences (P < 0.001) between the regions (RA, A1, and A2). Four factors were extracted from the FA/PCA (62% cumulative), showing that the animals from A2 presented severe alterations, mainly in intestinal morphometry and neuronal density. A1 alterations refer mainly to the increase of neuronal metabolism. Our results also evidence a gradient of environmental quality related to the protection level (AR > A1 > A2).

Neuro-immune crosstalk and food allergy: Focus on enteric neurons and mucosal mast cells

The nervous system and the immune system individually play important roles in regulating the processes necessary to maintain physiological homeostasis, respond to acute stress and protect against external threats. These two regulating systems for maintaining the living body had often been assumed to function independently. Allergies develop as a result of an overreaction of the immune system to substances that are relatively harmless to the body, such as food, pollen and dust mites. Therefore, it has been generally supposed that the development and pathogenesis of allergies can be explained through an immunological interpretation. Recently, however, neuro-immune crosstalk has attracted increasing attention. Consequently, it is becoming clear that there is close morphological proximity and physiological and pathophysiological interactions between neurons and immune cells in various peripheral tissues. Thus, researchers are now beginning to appreciate that neuro-immune interactions may play a role in tissue homeostasis and the pathophysiology of immune-mediated disease, but very little information is available on the molecular basis of these interactions. Mast cells are a part of the innate immune system implicated in allergic reactions and the regulation of host-pathogen interactions. Mast cells are ubiquitous in the body, and these cells are often found in close proximity to nerve fibers in various tissues, including the lamina propria of the intestine. Mast cells and neurons are thought to communicate bidirectionally to modulate neurophysiological effects and mast cell functions, which suggests that neuro-immune interactions may be involved in the pathology of allergic diseases.

Regional Gray Matter Volume Changes in Brains of Patients With Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) and Crohn's disease (CD) are 2 subtypes of inflammatory bowel disease (IBD). Several studies have reported brain abnormalities in IBD patients. This study aims to identify differences of gray matter volume (GMV) between patients with UC and healthy controls (HCs).

METHODS

Fifty-seven patients with UC and 40 HCs underwent structural magnetic resonance imaging. Voxel-based morphometry method was used to detect GMV differences. Receiver operating characteristic (ROC) curve was applied to investigate reliable biomarkers for identifying patients with UC from HCs. Regression analysis was used to examine relationships between the structure alternations and clinical symptoms.

RESULTS

Compared with HCs, patients with UC showed decreased GMV in the insula, thalamus, pregenual anterior cingulate cortex, hippocampus/parahippocampus, amygdala, and temporal pole; they showed increased GMV in the putamen, supplementary motor area, periaqueductal gray, hypothalamus, and precentral gyrus. Receiver operating characteristic analysis showed the highest classification power of thalamus. The inclusion of anxiety and depression as covariates eliminated the differences in the right insula, pregenual anterior cingulate cortex, supplementary motor area, and precentral gyrus. Most of the GMV changes were found in active patients with UC, with few changes in patients with UC in remission. We also found significantly negative correlation between UC duration and GMV in several regions.

CONCLUSION

The current neuroimaging findings were involved in visceral sensory pathways and were partially associated with the levels of anxiety and depression and clinical stage of patients with UC. This study might provide evidence for possible neuromechanisms of UC.