Neuronal stimulation with 5-hydroxytryptamine 4 receptor induces anti-inflammatory actions via α7nACh receptors on muscularis macrophages associated with postoperative ileus

Prokinetics-safety and efficacy: The European Society of Neurogastroenterology and Motility/The American Neurogastroenterology and Motility Society expert review

BACKGROUND

Prokinetics are a class of pharmacological drugs designed to improve gastrointestinal (GI) motility, either regionally or across the whole gut. Each drug has its merits and drawbacks, and based on current evidence as high-quality studies are limited, we have no clear recommendation on one class or other. However, there remains a large unmet need for both regionally selective and/or globally acting prokinetic drugs that work primarily intraluminally and are safe and without systemic side effects.

PURPOSE

Here, we describe the strengths and weaknesses of six classes of prokinetic drugs, including their pharmacokinetic properties, efficacy, safety and tolerability and potential indications.

Electroacupuncture alleviates intestinal inflammation via a distinct neuro-immune signal pathway in the treatment of postoperative ileus

BACKGROUND

The induction of intestinal inflammation as a result of abdominal surgery is an essential factor in postoperative ileus (POI) development. Electroacupuncture (EA) at ST36 has been demonstrated to relieve intestinal inflammation and restore gastrointestinal dysmotility in POI. This study aims to elucidate the neuroimmune pathway involved in the anti-inflammatory properties of EA in POI.

METHODS

After intestinal manipulation (IM) was performed to induce POI, intestinal inflammation and motility were assessed 24 h post-IM, by evaluating gastrointestinal transit (GIT), cytokines expression, and leukocyte infiltration. Experimental surgery, pharmacological intervention, and genetic knockout mice were used to elucidate the neuroimmune mechanisms of EA.

RESULTS

EA at ST36 significantly improved GIT and reduced the expression of pro-inflammatory cytokines and leukocyte infiltration in the intestinal muscularis following IM in mice. The anti-inflammatory effectiveness of EA treatment was abolished by sub-diaphragmatic vagotomy, whereas splenectomy did not hinder the anti-inflammatory benefits of EA treatment. The hexamethonium chloride (HEX) administration contributes to a notable reduction in the EA capacity to suppress inflammation and enhance motility dysfunction, and EA is ineffective in α7 nicotinic acetylcholine receptor (α7nAChR) knockout mice.

CONCLUSIONS

EA at ST36 prevents intestinal inflammation and dysmotility through a neural circuit that requires vagal innervation but is independent of the spleen. Further findings revealed that the process involves enteric neurons mediating the vagal signal and requires the presence of α7nAChR. These findings suggest that utilizing EA at ST36 may represent a possible therapeutic approach for POI and other immune-related gastrointestinal diseases.

A randomized controlled study to assess the effect of mosapride citrate on intestinal recovery following gastrectomy

The enhanced recovery after surgery (ERAS) protocol, including prokinetic medications, is commonly used to prevent postoperative ileus. Prospective studies evaluating the effectiveness of mosapride citrate, a prokinetic 5-hydroxytryptamine 4 receptor agonist, in patients undergoing gastrectomy within the ERAS framework are lacking. This double-blind randomized trial included patients who were scheduled for laparoscopic or robotic gastrectomy for gastric cancer. Participants were randomly assigned to either a control (placebo) or experimental (mosapride citrate) group, with drugs administered on postoperative days 1-5. Bowel motility was evaluated based on bowel transit time measured using radiopaque markers, first-flatus time, and amount of food intake. No significant differences were observed in baseline characteristics between the two groups. On postoperative day 3, no significant difference was observed in the number of radiopaque markers visible in the colon between the groups. All factors associated with bowel recovery, including the time of first flatus, length of hospital stay, amount of food intake, and severity of abdominal discomfort, were similar between the two groups. Mosapride citrate does not benefit the recovery of intestinal motility after minimally invasive gastrectomy in patients with gastric cancer. Therefore, routine postoperative use of mosapride citrate is not recommended in such patients.

Bone marrow-derived mesenchymal stem cells mitigate chronic colitis and enteric neuropathy via anti-inflammatory and anti-oxidative mechanisms

Current treatments for inflammatory bowel disease (IBD) are often inadequate due to limited efficacy and toxicity, leading to surgical resection in refractory cases. IBD's broad and complex pathogenesis involving the immune system, enteric nervous system, microbiome, and oxidative stress requires more effective therapeutic strategies. In this study, we investigated the therapeutic potential of bone marrow-derived mesenchymal stem cell (BM-MSC) treatments in spontaneous chronic colitis using the Winnie mouse model which closely replicates the presentation and inflammatory profile of ulcerative colitis. The 14-day BM-MSC treatment regimen reduced the severity of colitis, leading to the attenuation of diarrheal symptoms and recovery in body mass. Morphological and histological abnormalities in the colon were also alleviated. Transcriptomic analysis demonstrated that BM-MSC treatment led to alterations in gene expression profiles primarily downregulating genes related to inflammation, including pro-inflammatory cytokines, chemokines and other biomarkers of inflammation. Further evaluation of immune cell populations using immunohistochemistry revealed a reduction in leukocyte infiltration upon BM-MSC treatment. Notably, enteric neuronal gene signatures were the most impacted by BM-MSC treatment, which correlated with the restoration of neuronal density in the myenteric ganglia. Moreover, BM-MSCs exhibited neuroprotective effects against oxidative stress-induced neuronal loss through antioxidant mechanisms, including the reduction of mitochondrial-derived superoxide and attenuation of oxidative stress-induced HMGB1 translocation, potentially relying on MSC-derived SOD1. These findings suggest that BM-MSCs hold promise as a therapeutic intervention to mitigate chronic colitis by exerting anti-inflammatory effects and protecting the enteric nervous system from oxidative stress-induced damage.

Colitis-Induced Small Intestinal Hypomotility Is Dependent on Enteroendocrine Cell Loss in Mice

BACKGROUND & AIMS

The abdominal discomfort experienced by patients with colitis may be attributable in part to the presence of small intestinal dysmotility, yet mechanisms linking colonic inflammation with small-bowel motility remain largely unexplored. We hypothesize that colitis results in small intestinal hypomotility owing to a loss of enteroendocrine cells (EECs) within the small intestine that can be rescued using serotonergic-modulating agents.

METHODS

Male C57BL/6J mice, as well as mice that overexpress (EECOVER) or lack (EECDEL) NeuroD1+ enteroendocrine cells, were exposed to dextran sulfate sodium (DSS) colitis (2.5% or 5% for 7 days) and small intestinal motility was assessed by 70-kilodalton fluorescein isothiocyanate-dextran fluorescence transit. EEC number and differentiation were evaluated by immunohistochemistry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling staining, and quantitative reverse-transcriptase polymerase chain reaction. Mice were treated with the 5-hydroxytryptamine receptor 4 agonist prucalopride (5 mg/kg orally, daily) to restore serotonin signaling.

RESULTS

DSS-induced colitis was associated with a significant small-bowel hypomotility that developed in the absence of significant inflammation in the small intestine and was associated with a significant reduction in EEC density. EEC loss occurred in conjunction with alterations in the expression of key serotonin synthesis and transporter genes, including Tph1, Ddc, and Slc6a4. Importantly, mice overexpressing EECs revealed improved small intestinal motility, whereas mice lacking EECs had worse intestinal motility when exposed to DSS. Finally, treatment of DSS-exposed mice with the 5-hydroxytryptamine receptor 4 agonist prucalopride restored small intestinal motility and attenuated colitis.

CONCLUSIONS

Experimental DSS colitis induces significant small-bowel dysmotility in mice owing to enteroendocrine loss that can be reversed by genetic modulation of EEC or administering serotonin analogs, suggesting novel therapeutic approaches for patients with symptomatic colitis.

Exploring the chemical components of Kuanchang-Shu granule and its protective effects of postoperative ileus in rats by regulating AKT/HSP90AA1/eNOS pathway

BACKGROUND

Postoperative ileus (POI) is a common obstruction of intestinal content passage caused by almost all abdominal operations that seriously strokes the quality of life of patients. Kuanchang-Shu granule (KCSG), a classic modified prescription based on "Da-Cheng-Qi Decoction", has obtained satisfactory efficacy in the clinical therapeutics of POI. However, its material basis and holistic molecular mechanism against POI have not been revealed.

METHODS

The chemical ingredients of KCSG were first characterized by ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS). Subsequently, an integration strategy of the network pharmacology and molecular docking based on above identified ingredients was performed to unveil the potential targets involved in the treatment of KCSG on POI. Finally, intestinal manipulation induced rat POI model was constructed to verify the efficacy and predicted mechanism of KCSG against POI.

RESULTS

In total, 246 ingredients mainly including organic acids, flavonoids, quinones, alkaloids, terpenoids, phenylpropanoids and phenols were identified. 41 essential ingredients, 24 crucial targets as well as 15 relevant signaling pathways were acquired based on network pharmacology analysis. Pharmacodynamic research showed that KCSG treatment could protect intestinal histological damage, promote the recovery of measurement of gastrointestinal transit disorder and inhibit the secretion of myeloperoxidase in the distal ileum tissues. The up-regulated expression of p-AKT and down-regulated expression of p-eNOS and HSP9OAA1 predicted by molecular docking and validated by western blotting showed that AKT/eNOS/HSP90AA1 pathway may be one of the crucial mechanisms that mediates the protective effect of KCSG.

Optogenetic Activation of Cholinergic Enteric Neurons Reduces Inflammation in Experimental Colitis

BACKGROUND & AIMS

Intestinal inflammation is associated with loss of enteric cholinergic neurons. Given the systemic anti-inflammatory role of cholinergic innervation, we hypothesized that enteric cholinergic neurons similarly possess anti-inflammatory properties and may represent a novel target to treat inflammatory bowel disease.

METHODS

Mice were fed 2.5% dextran sodium sulfate (DSS) for 7 days to induce colitis. Cholinergic enteric neurons, which express choline acetyltransferase (ChAT), were focally ablated in the midcolon of ChAT::Cre;R26-iDTR mice by local injection of diphtheria toxin before colitis induction. Activation of enteric cholinergic neurons was achieved using ChAT::Cre;R26-ChR2 mice, in which ChAT+ neurons express channelrhodopsin-2, with daily blue light stimulation delivered via an intracolonic probe during the 7 days of DSS treatment. Colitis severity, ENS structure, and smooth muscle contractility were assessed by histology, immunohistochemistry, quantitative polymerase chain reaction, organ bath, and electromyography. In vitro studies assessed the anti-inflammatory role of enteric cholinergic neurons on cultured muscularis macrophages.

RESULTS

Ablation of ChAT+ neurons in DSS-treated mice exacerbated colitis, as measured by weight loss, colon shortening, histologic inflammation, and CD45+ cell infiltration, and led to colonic dysmotility. Conversely, optogenetic activation of enteric cholinergic neurons improved colitis, preserved smooth muscle contractility, protected against loss of cholinergic neurons, and reduced proinflammatory cytokine production. Both acetylcholine and optogenetic cholinergic neuron activation in vitro reduced proinflammatory cytokine expression in lipopolysaccharide-stimulated muscularis macrophages.

CONCLUSIONS

These findings show that enteric cholinergic neurons have an anti-inflammatory role in the colon and should be explored as a potential inflammatory bowel disease treatment.

New insights into muscularis macrophages in the gut: from their origin to therapeutic targeting

Muscularis macrophages, as the most abundant immune cells in the intestinal muscularis externa, exhibit tissue protective phenotype in the steady state. Owing to tremendous advances in technology, we now know the fact that muscularis macrophages are a heterogeneous population of cells which could be divided into different functional subsets depending on their anatomic niches. There is emerging evidence showing that these subsets, through molecular interactions with their neighbours, take part in a wide range of physiological and pathophysiological processes in the gut. In this review, we summarize recent progress (particularly over the past 4 years) on distribution, morphology, origin and functions of muscularis macrophages and, where possible, the characteristics of specific subsets in response to the microenvironment they occupy, with particular emphasis on their role in muscular inflammation. Furthermore, we also integrate their role in inflammation-related gastrointestinal disorders, such as post-operative ileus and diabetic gastroparesis, in order to propose future therapeutic strategies.

Assessing the Efficacy of Fenugreek Saponin Nanoparticles in Attenuating Nicotine-Induced Hepatotoxicity in Male Rats

During smoking, nicotine, the most bountiful compound in cigarettes, is absorbed into the body by the lungs and quickly metabolized in the liver, causing three major adverse impacts such as toxic, neoplastic, and immunomodulatory effects. Saponins extracted from several plants are reported to exhibit various biological actions, such as anticancer effects. So, the potential protective effect of fenugreek saponin and nanofenugreek saponin against toxicity induced by nicotine in male rats was investigated in this study. Animals were exposed to nicotine (1.5 mg/kg/day) and/or treated with fenugreek saponin (25, 50, and 100 mg/kg/day) and nanofenugreek saponin (20, 40, and 80 mg/kg/day). Comet assays, histopathological examination, and analyses for the expression levels of glutamate aspartate transporter (GLAST) and glutamate transporter-1 (GLT-1) genes in liver tissues as well as the activity of glutathione peroxidase (GPx) and glutathione-S-transferase (GST) were conducted. The results revealed that nicotine treatment induced a significant increase in DNA damage, decrease in the expression levels of (GLAST) and (GLT-1) genes, and increase in histopathological alterations in liver tissues. Moreover, nicotine treatment induced a significant reduction in the activity of antioxidant enzymes GPx and GST. On the other hand, administration of fenugreek saponin or nanofenugreek saponin with nicotine significantly decreased the DNA damage, increased the expression levels of (GLAST) and (GLT-1) genes, and decreased histopathological alterations in liver tissues. Additionally, a significant increase in the activities of GPx and GST was observed. The results suggested that DNA damage and histological injuries induced by nicotine were decreased by the administration of fenugreek saponin or nanofenugreek saponin; thus, fenugreek saponin and nanofenugreek saponin can be used as ameliorative agents against nicotine toxicity.

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.

Effect of the gut microbiota and their metabolites on postoperative intestinal motility and its underlying mechanisms

Gut microbiota is closely related to human health and disease because, together with their metabolites, gut microbiota maintain normal intestinal peristalsis. The use of antibiotics or opioid anesthetics, or both, during surgical procedures can lead to dysbiosis and affect intestinal motility; however, the underlying mechanisms are not fully known. This review aims to discuss the effect of gut microbiota and their metabolites on postoperative intestinal motility, focusing on regulating the enteric nervous system, 5-hydroxytryptamine neurotransmitter, and aryl hydrocarbon receptor.

Ion channel regulation of gut immunity

Mounting evidence indicates that gastrointestinal (GI) homeostasis hinges on communications among many cellular networks including the intestinal epithelium, the immune system, and both intrinsic and extrinsic nerves innervating the gut. The GI tract, especially the colon, is the home base for gut microbiome which dynamically regulates immune function. The gut's immune system also provides an effective defense against harmful pathogens entering the GI tract while maintaining immune homeostasis to avoid exaggerated immune reaction to innocuous food and commensal antigens which are important causes of inflammatory disorders such as coeliac disease and inflammatory bowel diseases (IBD). Various ion channels have been detected in multiple cell types throughout the GI tract. By regulating membrane properties and intracellular biochemical signaling, ion channels play a critical role in synchronized signaling among diverse cellular components in the gut that orchestrates the GI immune response. This work focuses on the role of ion channels in immune cells, non-immune resident cells, and neuroimmune interactions in the gut at the steady state and pathological conditions. Understanding the cellular and molecular basis of ion channel signaling in these immune-related pathways and initial testing of pharmacological intervention will facilitate the development of ion channel-based therapeutic approaches for the treatment of intestinal inflammation.

Inflammation and Impaired Gut Physiology in Post-operative Ileus: Mechanisms and the Treatment Options

Post-operative ileus (POI) is the transient cessation of coordinated gastrointestinal motility after abdominal surgical intervention. It decreases quality of life, prolongs length of hospital stay, and increases socioeconomic costs. The mechanism of POI is complex and multifactorial, and has been broadly categorized into neurogenic and inflammatory phase. Neurogenic phase mediated release of corticotropin-releasing factor (CRF) plays a central role in neuroinflammation, and affects both central autonomic response as well hypothalamic-pituitary-adrenal (HPA) axis. HPA-stress axis associated cortisol release adversely affects gut microbiota and permeability. Peripheral CRF (pCRF) is a key player in stress induced gastric emptying and colonic transit. It functions as a local effector and interacts with the CRF receptors on the mast cell to release chemical mediators of inflammation. Mast cells proteases disrupt epithelial barrier via protease activated receptor-2 (PAR-2). PAR-2 facilitates cytoskeleton contraction to reorient tight junction proteins such as occludin, claudins, junctional adhesion molecule, and zonula occludens-1 to open epithelial barrier junctions. Barrier opening affects the selectivity, and hence permeation of luminal antigens and solutes in the gastrointestinal tract. Translocation of luminal antigens perturbs mucosal immune system to further exacerbate inflammation. Stress induced dysbiosis and decrease in production of short chain fatty acids add to the inflammatory response and barrier disintegration. This review discusses potential mechanisms and factors involved in the pathophysiology of POI with special reference to inflammation and interlinked events such as epithelial barrier dysfunction and dysbiosis. Based on this review, we recommend CRF, mast cells, macrophages, and microbiota could be targeted concurrently for efficient POI management.

Selective serotonin reuptake inhibitors and inflammatory bowel disease; Beneficial or malpractice

IBD, a chronic inflammatory disease, has been manifested as a growing health problem. No Crohn’s and Colitis councils have officially ratified anti-depressants as a routine regimen for IBD patients. However, some physicians empirically prescribe them to rectify functional bowel consequences such as pain and alleviate psychiatric comorbidities. On the other side, SSRIs’ prescription is accompanied by adverse effects such as sleep disturbances. Prolonged intermittent hypoxia throughout sleep disturbance such as sleep apnea provokes periodic reductions in the partial oxygen pressure gradient in the gut lumen. It promotes gut microbiota to dysbiosis, which induces intestinal inflammation. This phenomenon and evidence representing the higher amount of serotonin associated with Crohn’s disease challenged our previous knowledge. Can SSRIs worsen the IBD course? Evidence answered the question with the claim on anti-inflammatory properties (central and peripheral) of SSRIs and illuminated the other substantial elements (compared to serotonin elevation) responsible for IBD pathogenesis. However, later clinical evidence was not all in favor of the benefits of SSRIs. Hence, in this review, the molecular mechanisms and clinical evidence are scrutinized and integrated to clarify the interfering molecular mechanism justifying both supporting and disproving clinical evidence. Biphasic dose-dependent serotonin behavior accompanying SSRI shifting function when used up for the long-term can be assumed as the parameters leading to IBD patients’ adverse outcomes. Despite more research being needed to elucidate the effect of SSRI consumption in IBD patients, periodic prescriptions of SSRIs at monthly intervals can be recommended.

Acid external and internal environment exchange the Oreochromis niloticus tissue immune gene expression compared to the mouse macrophage polarization model

The water environment plays an important role in animal physiology. In this study, we sought to evaluate the effect of the acid environment on the Oreochromis niloticus (Nile tilapia) internal microenvironment immune response compare to the mouse macrophage model (J77A.1). The acid environment treated mouse macrophage J774A.1 model have shown that acidic treatment is able to polarize macrophages into M2-like macrophages via an increase in Ym1, Tgm2, Arg1, Fizz1, and IL-10 expression. Metabolic analysis of mouse macrophages (J774A.1) at pH 2 vs. pH 7 and pH 4 vs. pH 7 have been shown to promote the expression of intracellular acetylcholine, choline, prochlorperazine, L-leucine, and bisphenol A,2-amino-3-methylimidazo[4,5-f] quinolone metabolites in the M2-like macrophage. Immune gene expression of the O. niloticus spleen and liver treated at pH 2, 4, and 7 was shown to reduce TNF-α, IL-1 β, IL-8, and IL-12 expression compared to pH 7 treatment. Immune gene was induced in O. niloticus following culture at pH 5, 6, and 7 fresh water environment. Taken together, we found that the acid internal environment polarizes tissues into an M2 macrophage developmental microenvironment. However, if the external environment is acid, tissues are exposed to an M1 macrophage developmental microenvironment.

Molecular and cellular mechanisms underlying postoperative paralytic ileus by various immune cell types

Postoperative ileus (POI) is a well-known complication following gut manipulation or surgical trauma, leading to an impaired gut motility and prolonged postoperative recovery time. Few current therapeutic strategies can prevent POI, and this disorder remains to be a major clinical challenge for patients undergoing surgery. Comprehensive understanding of cellular and molecular mechanisms related to the pathogenesis of POI stimulates the discovery of more promising targets for treatment. POI is closely associated with a series of inflammatory events within the bowel wall, and as key components of inflammatory mechanisms, different types of immune cells, including macrophages, dendritic cells, and T lymphocytes, play significant roles during the development of POI. A variety of immune cells are recruited into the manipulation sites after surgery, contributing to early inflammatory events or impaired gut motility. Our review intends to summarize the specific relationship between different immune cells and POI, mainly focusing on the relevant mechanisms underlying this disorder.

Enterochromaffin Cells-Gut Microbiota Crosstalk: Underpinning the Symptoms, Pathogenesis, and Pharmacotherapy in Disorders of Gut-Brain Interaction

Disorders of gut-brain interaction (DGBIs) are common conditions in community and clinical practice. As specialized enteroendocrine cells, enterochromaffin (EC) cells produce up to 95% of total body serotonin and coordinate luminal and basolateral communication in the gastrointestinal (GI) tract. EC cells affect a broad range of gut physiological processes, such as motility, absorption, secretion, chemo/mechanosensation, and pathologies, including visceral hypersensitivity, immune dysfunction, and impaired gastrointestinal barrier function. We aim to review EC cell and serotonin-mediated physiology and pathophysiology with particular emphasis on DGBIs. We explored the knowledge gap and attempted to suggest new perspectives of physiological and pathophysiological insights of DGBIs, such as (1) functional heterogeneity of regionally distributed EC cells throughout the entire GI tract; (2) potential pathophysiological mechanisms mediated by EC cell defect in DGBIs; (3) cellular and molecular mechanisms characterizing EC cells and gut microbiota bidirectional communication; (4) differential modulation of EC cells through GI segment-specific gut microbiota; (5) uncover whether crosstalk between EC cells and (i) luminal contents; (ii) enteric nervous system; and (iii) central nervous system are core mechanisms modulating gut-brain homeostasis; and (6) explore the therapeutic modalities for physiological and pathophysiological mechanisms mediated through EC cells. Insights discussed in this review will fuel the conception and realization of pathophysiological mechanisms and therapeutic clues to improve the management and clinical care of DGBIs.

Cholinergic immunomodulation in inflammatory bowel diseases

Inflammatory bowel diseases (IBD) are chronic intestinal disorders characterized by dysregulated immune responses to resident microbiota in genetically susceptible hosts. The activation of the cholinergic system has been proposed for the treatment of IBD patients according to its potential anti-inflammatory effect in vivo. The α-7-nicotinic-acetylcholine receptor (α7nAChR) is involved in the inhibition of inflammatory processes, modulating the production of cytokines, suppressing dendritic cells and macrophage activity, leading to the suppression of T cells. In this review, we address the most recent studies and clinical trials concerning cholinergic signaling and its therapeutic potential for inflammatory bowel diseases.

Postoperative Ileus: a Pharmacological Perspective

Post-operative ileus (POI) is a frequent complication after abdominal surgery. The consequences of POI can be potentially serious such as bronchial inhalation or acute functional renal failure. Numerous advances in peri-operative management, particularly early rehabilitation, have made it possible to decrease POI. Despite this, the rate of prolonged POI ileus remains high and can be as high as 25% of patients in colorectal surgery. From a pathophysiological point of view, POI has two phases, an early neurological phase and a later inflammatory phase, to which we could add a "pharmacological" phase during which analgesic drugs, particularly opiates, play a central role. The aim of this review article is to describe the phases of the pathophysiology of POI, to analyse the pharmacological treatments currently available through published clinical trials and finally to discuss the different research areas for potential pharmacological targets.

Hangekobokuto, a traditional Japanese herbal medicine, ameliorates postoperative ileus through its anti-inflammatory action

Background/Aims: Gastroprokinetic agents are used for patients with postoperative ileus (POI), and the Japanese traditional herbal medicine daikenchuto (DKT) is one such agent used in the clinical setting. POI is caused by inflammation. DKT and rikkunshito have anti-inflammatory abilities in addition to their gastroprokinetic effects. The efficacy of Kampo formulations, including hangekobokuto (HKT), in patients with POI has been reported recently. Several authors have described the efficacy of honokiol, the primary component of Magnoliae Cortex, in HKT in mouse models of POI. We therefore analyzed the effect of HKT on POI model mice to determine the similarities in the mechanism of action between HKT and DKT.

Methods: HKT was administered orally to each mouse before and after intestinal manipulation was performed on the distal ileum. The gastrointestinal transit in vivo, leukocyte infiltration, and levels of inflammatory mediators, such as cytokines and chemokines, were analyzed.

Results: HKT significantly inhibited the infiltration of neutrophils and macrophages and led to the recovery of delayed intestinal transit. In addition, it significantly decreased inducible nitric oxide synthase (iNOS) as well as honokiol levels, suggesting anti-inflammatory activity. However, it did not inhibit the increase in levels of interleukin (IL)-1beta and IL-6, which are related to iNOS induction. In contrast, HKT increased levels of nerve growth factor (NGF) and suppressed those of nuclear factor-κB (NFκB), which are related to iNOS induction, suggesting the possibility of a neuronal anti-inflammatory mechanism.

Conclusions: HKT exerted a POI-relieving effect similar to DKT in a murine POI model, and findings suggest that it may exert its anti-inflammatory activity through NGF.

Activation of α7nAChR Protects Against Gastric Inflammation and Dysmotility in Parkinson's Disease Rats

The cholinergic anti-inflammatory pathway (CAIP) has been proposed to regulate gastrointestinal inflammation via acetylcholine released from the vagus nerve activating α7 nicotinic receptor (α7nAChR) on macrophages. Parkinson’s disease (PD) patients and PD rats with substantia nigra (SN) lesions exhibit gastroparesis and a decayed vagal pathway. To investigate whether activating α7nAChR could ameliorate inflammation and gastric dysmotility in PD rats, ELISA, western blot analysis, and real-time PCR were used to detect gastric inflammation. In vitro and in vivo gastric motility was investigated. Proinflammatory mediator levels and macrophage numbers were increased in the gastric muscularis of PD rats. α7nAChR was located on the gastric muscular macrophages of PD rats. The α7nAChR agonists PNU-282987 and GTS-21 decreased nuclear factor κB (NF-κB) activation and monocyte chemotactic protein-1 mRNA expression in the ex vivo gastric muscularis of PD rats, and these effects were abolished by an α7nAChR antagonist. After treatment with PNU-282987 in vivo, the PD rats showed decreased NF-κB activation, inflammatory mediator production, and contractile protein expression and improved gastric motility. The present study reveals that α7nAChR is involved in the development of gastroparesis in PD rats and provides novel insight for the treatment of gastric dysmotility in PD patients.

Effect of multimodal preemptive analgesia on postoperative gastrointestinal function and clinical outcome in patients undergoing laparoscopic colorectal surgery

OBJECTIVE

This study aimed to investigate the effects of multimodal preemptive analgesia on postoperative gastrointestinal function and clinical outcomes in patients undergoing laparoscopic colorectal surgery.

METHODS

This prospective study included a total of 108 patients undergoing elective laparoscopic colorectal surgery from June 2019 to June 2020. The patients were divided into the control group and the study group according to the random number table method. Patients in the study group were given flurbiprofen axetil and oxycodone before skin incision combined with bilateral transverse abdominis plane block (TAPB) before anaesthesia induction. In the control group, patients were given sufentanil and flurbiprofen axetil combined with bilateral TAPB in postanaesthesia care unit (PACU). The incidence of postoperative gastrointestinal dysfunction (POGD), I-FEED score, inflammatory factor levels, rehabilitation indicators, postoperative pain assessment and other organ complications were observed and compared between the two groups.

RESULTS

The incidence of POGD in the study group was lower compared to the control group, and the difference was statistically significant (P < .05). The study group had lower total and mean scores of I-FEED at 24, 48, 72 and 96 hours after surgery; however, the differences were not statistically significant (P > .05). On the first and third day after operation, Lipopolysaccharide (LPS), C-reactive protein (CRP), Tumour necrosis factor (TNF-α) and Interleukins6 (IL-6) levels of the study group decreased significantly (P < .05). The reduction in inflammation factor levels from 1d to 3d was significantly greater than that of the control group (P < .05).

CONCLUSION

The strategy of multimodal preemptive analgesia can effectively prevent the onset of POGD and may accelerate rehabilitation. In short, multimodal preemptive analgesia provides a novel prevention strategy for patients undergoing laparoscopic colorectal surgery.

Improved motility in the gastrointestinal tract of a postoperative ileus rat model with ilaprazole

Postoperative ileus (POI), a symptom that occurs after abdominal surgery, reduces gastrointestinal motility. Although its mechanism is unclear, POI symptoms are known to be caused by inflammation 6 to 72 h after surgery. As proton pump inhibitors exhibit protective effect against acute inflammation, the purpose of this study was to determine the effect of ilaprazole on a POI rat model. POI was induced in rats by abdominal surgery. Rats were divided into six groups: control: normal rat + 0.5% CMC-Na, vehicle: POI rat + 0.5% CMC-Na, mosapride: POI rat + mosapride 2 mg/kg, ilaprazole 1 mg/kg: POI rat + ilaprazole 1 mg/kg, ilaprazole 3 mg/kg: POI rat + ilaprazole 3 mg/kg, and ilaprazole 10 mg/kg: POI rat + ilaprazole 10 mg/kg. Gastrointestinal motility was confirmed by measuring gastric emptying (GE) and gastrointestinal transit (GIT). In the small intestine, inflammation was confirmed by measuring TNF-α and IL-1β; oxidative stress was confirmed by SOD, GSH, and MDA levels; and histological changes were observed by H&E staining. Based on the findings, GE and GIT were decreased in the vehicle group and improved in the ilaprazole 10 mg/kg group. In the ilaprazole 10 mg/kg group, TNF-α and IL-1β levels were decreased, SOD and GSH levels were increased, and MDA levels were decreased. Histological damage was also reduced in the ilaprazole-treated groups. These findings suggest that ilaprazole prevents the decrease in gastrointestinal motility, a major symptom of postoperative ileus, and reduces inflammation and oxidative stress.

Altered Intestinal Permeability and Drug Repositioning in a Post-operative Ileus Guinea Pig Model

Background/Aims

The aim of this study is to identify the alteration in intestinal permeability with regard to the development of post-operative ileus (POI). Moreover, we investigated drug repositioning in the treatment of POI.

Methods

An experimental POI model was developed using guinea pigs. To measure intestinal permeability, harvested intestinal membranes of the ileum and proximal colon was used in an Ussing chamber. To identify the mechanisms associated with altered permeability, we measured leukocyte count and expression of calprotectin, claudin-1, claudin-2, and mast cell tryptase. We compared control, POI, and drug groups (mosapride [0.3 mg/kg and 1 mg/kg, orally], glutamine [500 mg/kg, orally], or ketotifen [1 mg/kg, orally] with regard to these parameters.

Results

Increased permeability after surgery significantly decreased after administration of mosapride, glutamine, or ketotifen. Leukocyte counts increased in the POI group and decreased significantly after administration of mosapride (0.3 mg/kg) in the ileum, and mosapride (0.3 mg/kg and 1 mg/kg), glutamine, or ketotifen in the proximal colon. Increased expression of calprotectin after surgery decreased after administration of mosapride (0.3 mg/kg), glutamine, or ketotifen in the ileum and proximal colon, and mosapride (1 mg/kg) in the ileum. The expression of claudin-1 decreased significantly and that of claudin-2 increased after operation. After administration of glutamine, the expression of both proteins was restored. Finally, mast cell tryptase levels increased in the POI group and decreased significantly after administration of ketotifen.

Conclusions

The alteration in intestinal permeability is one of the factors involved in the pathogenesis of POI. We repositioned 3 drugs (mosapride, glutamine, and ketotifen) as novel therapeutic agents for POI.

Post-operative ileus: definitions, mechanisms and controversies

Post-operative ileus (POI) is a syndrome of impaired gastrointestinal transit which occurs following abdominal surgery. There are few effective targeted therapies for ileus, and research has been limited by inconsistent definitions and an incomplete understanding of the underlying pathophysiology. Despite considerable effort, there remains no widely-adopted definition of ileus, and recent work has identified variation in outcome reporting is a major source of heterogeneity in clinical trials. Outcomes should be clearly-defined, clinically-relevant, and reflective of the underlying biology, impacts on hospital resources and quality of life. Further collaborative efforts will be needed to develop consensus definitions and a core outcome set for postoperative gastrointestinal recovery. Investigation into the pathophysiology of POI has been hindered by use of low-resolution techniques and difficulties linking cellular mechanisms to dysmotility patterns and clinical symptoms. Recent evidence has suggested the common assumption of post-operative GI paralysis is incorrect, and that the distal colon becomes hyperactive following surgery. The post-operative inflammatory response is important in the pathophysiology of ileus, but the time course of this in humans remains unclear, with the majority of evidence coming from animal models. Future work should investigate dysmotility patterns underlying ileus, and identify biomarkers which may be used to diagnose, monitor and stratify patients with ileus.

Targeting Enteric Neurons and Plexitis for the Management of Inflammatory Bowel Disease

Ulcerative colitis (UC) and Crohn's disease (CD) are pathological conditions with an unknown aetiology that are characterised by severe inflammation of the intestinal tract and collectively referred to as inflammatory bowel disease (IBD). Current treatments are mostly ineffective due to their limited efficacy or toxicity, necessitating surgical resection of the affected bowel. The management of IBD is hindered by a lack of prognostic markers for clinical inflammatory relapse. Intestinal inflammation associates with the infiltration of immune cells (leukocytes) into, or surrounding the neuronal ganglia of the enteric nervous system (ENS) termed plexitis or ganglionitis. Histological observation of plexitis in unaffected intestinal regions is emerging as a vital predictive marker for IBD relapses. Plexitis associates with alterations to the structure, cellular composition, molecular expression and electrophysiological function of enteric neurons. Moreover, plexitis often occurs before the onset of gross clinical inflammation, which may indicate that plexitis can contribute to the progression of intestinal inflammation. In this review, the bilateral relationships between the ENS and inflammation are discussed. These include the effects and mechanisms of inflammation-induced enteric neuronal loss and plasticity. Additionally, the role of enteric neurons in preventing antigenic/pathogenic insult and immunomodulation is explored. While all current treatments target the inflammatory pathology of IBD, interventions that protect the ENS may offer an alternative avenue for therapeutic intervention.

The immunological influence of physical exercise on TBI-induced pathophysiology: Crosstalk between the spleen, gut, and brain

Traumatic brain injury (TBI) is a non-degenerative and non-congenital insult to the brain and is recognized as a global public health problem, with a high incidence of neurological disorders. Despite the causal relationship not being entirely known, it has been suggested that multiorgan inflammatory response involving the autonomic nervous system and the spleen-gut brain axis dysfunction exacerbate the TBI pathogenesis in the brain. Thus, applying new therapeutic tools, such as physical exercise, have been described in the literature to act on the immune modulation induced by brain injuries. However, there are caveats to consider when interpreting the effects of physical exercise on this neurological injury. Given the above, this review will highlight the main findings of the literature involving peripheral immune responses in TBI-induced neurological damage and how changes in the cellular metabolism of the spleen-gut brain axis elicited by different protocols of physical exercise alter the pathophysiology induced by this neurological injury.

Regulation of the Autonomic Nervous System on Intestine

Intestine is composed of various types of cells including absorptive epithelial cells, goblet cells, endocrine cells, Paneth cells, immunological cells, and so on, which play digestion, absorption, neuroendocrine, immunological function. Intestine is innervated with extrinsic autonomic nerves and intrinsic enteric nerves. The neurotransmitters and counterpart receptors are widely distributed in the different intestinal cells. Intestinal autonomic nerve system includes sympathetic and parasympathetic nervous systems, which regulate cellular proliferation and function in intestine under physiological and pathophysiological conditions. Presently, distribution and functional characteristics of autonomic nervous system in intestine were reviewed. How autonomic nervous system regulates intestinal cell proliferation was discussed. Function of autonomic nervous system on intestinal diseases was extensively reviewed. It might be helpful to properly manipulate autonomic nervous system during treating different intestinal diseases.

Targeting the gut to treat multiple sclerosis

The gut-brain axis (GBA) refers to the complex interactions between the gut microbiota and the nervous, immune, and endocrine systems, together linking brain and gut functions. Perturbations of the GBA have been reported in people with multiple sclerosis (pwMS), suggesting a possible role in disease pathogenesis and making it a potential therapeutic target. While research in the area is still in its infancy, a number of studies revealed that pwMS are more likely to exhibit altered microbiota, altered levels of short chain fatty acids and secondary bile products, and increased intestinal permeability. However, specific microbes and metabolites identified across studies and cohorts vary greatly. Small clinical and preclinical trials in pwMS and mouse models, in which microbial composition was manipulated through the use of antibiotics, fecal microbiota transplantation, and probiotic supplements, have provided promising outcomes in preventing CNS inflammation. However, results are not always consistent, and large-scale randomized controlled trials are lacking. Herein, we give an overview of how the GBA could contribute to MS pathogenesis, examine the different approaches tested to modulate the GBA, and discuss how they may impact neuroinflammation and demyelination in the CNS.

Protective effects of prucalopride in MPTP-induced Parkinson's disease mice: Neurochemistry, motor function and gut barrier

Evidence suggests constipation precedes motor dysfunction and is the most common gastrointestinal symptom in Parkinson's disease (PD). 5-HT4 receptor (5-HT4R) agonist prucalopride has been approved to treat chronic constipation. Here, we reported intraperitoneal injection of prucalopride for 7 days increased dopamine and decreased dopamine turnover. Prucalopride administration improved motor deficits in 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP)-induced PD mouse models. Prucalopride treatment also ameliorated intestinal barrier impairment and increased IL-6 release in PD model mice. However, prucalopride treatment exerted no impact on JAK2/STAT3 pathway, suggesting that prucalopride may stimulate IL-6 via JAK2/STAT3-independent pathway. In conclusion, prucalopride exerted beneficial effects in MPTP-induced Parkinson's disease mice by attenuating the loss of dopamine, improving motor dysfunction and intestinal barrier.

Efficacy and Safety of DWJ1252 Compared With Gasmotin in the Treatment of Functional Dyspepsia: A Multicenter, Randomized, Double-blind, Active-controlled Study

Background/Aims

Prokinetics such as mosapride citrate CR (conventional-release; Gasmotin) are commonly used in functional dyspepsia (FD). This study aims to evaluate the efficacy and safety of once-a-day mosapride citrate SR (DWJ1252), a sustained-release formulation of mosapride citrate, compared with mosapride citrate CR 3 times a day, in patients with FD.

Methods

In this multicenter, randomized, double-blind, active-controlled, non-inferiority study, 119 patients with FD (by the Rome III criteria, 60 for mosapride citrate SR and 59 for mosapride citrate CR) were randomly allocated to mosapride citrate SR once daily or mosapride citrate CR thrice daily for 4 weeks in 16 medical institutions. Primary end point was the change in gastrointestinal symptom (GIS) score from baseline, assessed by GIS questionnaires on 5-point Likert scale after 4-week treatment. Secondary end points and safety profiles were also analyzed.

Results

The study included 51 and 49 subjects in the mosapride citrate SR and mosapride citrate CR groups, respectively. GIS scores at week 4 were significantly reduced in both groups (mean ± SD: -10.04 ± 4.45 and -10.86 ± 5.53 in the mosapride citrate SR and mosapride citrate CR groups, respectively; P < 0.001), and the GIS changes from baseline did not differ between the 2 groups (difference, 0.82 point; 95% CI, -1.17, 2.81; P = 0.643). Changes in GIS at weeks 2 and 4 and quality of life at week 4, and the improvement rates of global assessments at weeks 2 and 4, did not differ between the groups. Adverse events were similar in the 2 groups, and there were no serious adverse events.

Conclusion

In patients with FD, mosapride citrate SR once daily is as effective as mosapride citrate CR thrice daily, with a similar safety profile.

Biological characteristics of IL-6 and related intestinal diseases

The intestine serves as an important digestive and the largest immune organ in the body. Interleukin-6(IL-6), an important mediator of various pathways, participates in the interactions between different kinds of cells and closely correlates with intestinal physiological and pathological condition. In this review we summarize the signaling pathways of IL-6 and its functions in maintaining intestinal homeostasis. We also explored its relation with nervous system and highlight its potential role in Parkinson's disease. Based on its specialty of the double-side influences on intestinal tumors and inflammation, we summarize how they are done through distinctive process.

Traditional Chinese Medicine Da-Cheng-Qi-Tang Ameliorates Impaired Gastrointestinal Motility and Intestinal Inflammatory Response in a Mouse Model of Postoperative Ileus

This study was to explore the therapeutic effect and mechanism of the traditional Chinese medicine with the formula Da-Cheng-Qi-Tang (T-DCQT) and a modified Da-Cheng-Qi-Tang (M-DCQT) in a postoperative ileus (POI) mouse model. POI was induced via small bowel manipulation, and T-DCQT or M-DCQT was given by enema. The intestinal motility was measured with a charcoal mixture gavage. The intestinal tissues were collected for further studies by histopathological, qPCR, immunohistochemical staining, and Western blotting. Levels of inflammatory cytokines in blood were determined using a high-throughput liquid chip. We found that gastrointestinal dysfunction was alleviated after administration of either a T-DCQT or M-DCQT enema. Increased expression of NF-κB, p38 MAPK, and TLR4 in the intestinal tissues of POI mice were reversed following treatment. IL-1α, IL-6, MIP-1β, and IL-17 levels were significantly reduced at 24 h and 48 h following treatment, while the MCP-1 level was only observed to be reduced at 24 h after the treatment. Furthermore, compared with the T-DCQT effect, M-DCQT treatment was more effective in alleviating the increased IL-6, MIP-1β, and IL-1α levels. So, we draw a conclusion that T-DCQT or M-DCOT could ameliorate the POI-associated inflammatory response and improve GI motility in a POI mouse model.

Physical Exercise Affects Serotoninergic System in Horse Leukocytes

Serotonin (5-hydroxytryptamine [5-HT]) may induce metabolic effects in different cell types, including leukocytes. In horses, 5-HT is involved in physiological and behavioral functions. Physical exercise is known to increase the amounts of 5-HT both in brain and periphery, but so far, the signal mechanism in response to exercise is not known. The aim of the study was to investigate the effect of a racehorse intensive training session on plasma 5-HT levels, serotonin transporter (SERT), 5HT_1A, 5-HT_2A, 5-HT_1B, 5-HT₇ receptor, interleukin-1 beta, and tumor necrosis factor-alpha expression in horse peripheral blood mononuclear cells (PBMC). In particular, the research was carried out on 12 trained horses performing daily training. Plasma 5-HT levels were analyzed in platelet-poor plasma fraction by enzyme-linked immunosorbent assay at T0, T1, and T2 (pretraining, 30 minutes post-training, and 2 hours post-training session), respectively. Peripheral blood mononuclear cells were isolated to perform real-time polymerase chain reaction for the evaluation of SERT, 5-HT receptor, and cytokine mRNA levels. The results showed significantly increased levels of plasma 5-HT, 5HT_1A, and 5-HT_2A and significantly decreased levels of SERT, 5-HT_1B, 5-HT₇, and both cytokine mRNAs in PBMC at T1, compared with T0 and T2. The results were confirmed by in vitro experiment. Training may induce a lower degree of 5-HT storage and, therefore, a higher plasma 5-HT concentrations. Leukocyte 5-HT receptor mRNAs seem strongly influenced by the exercise. Observed changes suggest a transient neuroendocrinological response to the exercise. A better understanding of the influence of physical exercise on serotoninergic system could have potential application for the implementation of training protocols in racing horses.

Therapeutic potential of serotonin 4 receptor for chronic depression and its associated comorbidity in the gut

The latest estimates from world health organization suggest that more than 450 million people are suffering from depression and other psychiatric conditions. Of these, 50-60% have been reported to have progression of gut diseases. In the last two decades, researchers introduced incipient physiological roles for serotonin (5-HT) receptors (5-HTRs), suggesting their importance as a potential pharmacological target in various psychiatric and gut diseases. A growing body of evidence suggests that 5-HT systems affect the brain-gut axis in depressive patients, which leads to gut comorbidity. Recently, preclinical trials of 5-HT4R agonists and antagonists were promising as antipsychotic and prokinetic agents. In the current review, we address the possible pharmacological role and contribution of 5-HT4R in the pathophysiology of chronic depression and associated gut abnormalities. Physiologically, during depression episodes, centers of the sympathetic and parasympathetic nervous system couple together with neuroendocrine systems to alter the function of hypothalamic-pituitary-adrenal (HPA) axis and enteric nervous system (ENS), which in turn leads to onset of gastrointestinal tract (GIT) disorders. Consecutively, the ENS governs a broad spectrum of physiological activities of gut, such as visceral pain and motility. During the stages of emotional stress, hyperactivity of the HPA axis alters the ENS response to physiological and noxious stimuli. Consecutively, stress-induced flare, swelling, hyperalgesia and altered reflexes in gut eventually lead to GIT disorders. In summary, the current review provides prospective information about the role and mechanism of 5-HT4R-based therapeutics for the treatment of depressive disorder and possible consequences for the gut via brain-gut axis interactions. This article is part of the special issue entitled 'Serotonin Research: Crossing Scales and Boundaries'.

A new zinc chelator, IPZ-010 ameliorates postoperative ileus

Zinc was discovered to be a novel second messenger in immunoreactive cells. We synthesized a novel free zinc chelator, IPZ-010. Here, we investigated the effects of IPZ-010 in a mouse postoperative ileus model and determined the effects of zinc signal inhibition as a new therapeutic strategy against postoperative ileus. Zinc waves were measured in bone marrow-derived mast cells (BMMCs) loaded with a zinc indicator, Newport green. Degranulation and cytokine expression were measured in BMMCs and bone marrow-derived macrophages (BMDMs). Postoperative ileus model mice were established with intestinal manipulation. Mice were treated with IPZ-010 (30 mg/kg, s.c. or p.o.) 1 h before and 2 h and 4 h after intestinal manipulation. Gastrointestinal transit, inflammatory cell infiltration, and expression of inflammatory mediators were measured. Free zinc waves occurred following antigen stimulation in BMMCs and were blocked by IPZ-010. IPZ-010 inhibited interleukin-6 secretion and degranulation in BMMCs. IPZ-010 inhibited tumor necrosis factor-α mRNA expression in BMMCs stimulated with lipopolysaccharide or adenosine triphosphate, whereas IPZ-010 had no effects on tumor necrosis factor-α mRNA expression in BMDMs stimulated with lipopolysaccharide or adenosine triphosphate. In postoperative ileus model mice, IPZ-010 inhibited leukocyte infiltration and cytokine expression, which ameliorated gastrointestinal transit. Furthermore, ketotifen (1 mg/kg) induced similar effects as IPZ-010. These effects were not amplified by co-administration of IPZ-010 and ketotifen. IPZ-010 inhibited zinc waves, resulting in inhibition of inflammatory responses in activated BMMCs in vitro. Targeting zinc waves in inflammatory cells may be a novel therapeutic strategy for treating postoperative ileus.

Nicotine reverses the enhanced renal vasodilator capacity in endotoxic rats: Role of α7/α4β2 nAChRs and HSP70

BACKGROUND

Nicotine alleviates renal inflammation and injury induced by endotoxemia. This study investigated (i) the nicotine modulation of hemodynamic and renal vasodilatory responses to endotoxemia in rats, and (ii) roles of α7 or α4β2-nAChRs and related HSP70/TNFα/iNOS signaling in the interaction.

METHODS

Endotoxemia was induced by ip lipopolysaccharide (5 mg/kg/day, for 2 days) and changes in systolic blood pressure and vasodilator responsiveness of isolated perfused kidney to acetylcholine or 5'-N-ethylcarboxamidoadenosine (NECA, adenosine receptor agonist) were evaluated.

RESULTS

Lipopolysaccharide had no effect on serum creatinine, reduced blood pressure, and increased renal vasodilations induced by acetylcholine or NECA in male and female preparations. Immunohistochemical analyses showed that lipopolysaccharide reduced renal HSP70 expression, but increased α7-nAChRs, α4β2-nAChRs and iNOS expressions. The co-administration of aminoguanidine (iNOS inhibitor), pentoxifylline (TNFα inhibitor), or nicotine attenuated lipopolysaccharide mediation of renal vasodilations and elevations in α7/α4β2-nAChR and iNOS expressions. Nicotine also reversed the downregulating effect of lipopolysaccharide on HSP70 expression. α7-nAChRs (methyllycaconitine citrate, MLA) or α4β2-nAChRs (dihydro-β-erythroidine, DHβE) blockade potentiated the lipopolysaccharide enhancement of renal vasodilations, and abolished the depressant effect of nicotine on lipopolysaccharide responses. A similar abolition of nicotine effects was seen after HSP70 inhibition by quercetin. Alternatively, lipopolysaccharide hypotension was eliminated in rats treated with DHβE/nicotine or quercetin/nicotine regimen in contrast to no effect for nicotine alone or combined with MLA.

CONCLUSIONS

These findings establish that nicotine offsets lipopolysaccharide facilitation of renal vasodilations possibly through a crosstalk between HSP70 and nAChRs of the α7 and α4β2 types.

Preoperative administration of the 5-HT4 receptor agonist prucalopride reduces intestinal inflammation and shortens postoperative ileus via cholinergic enteric neurons

OBJECTIVES

Vagus nerve stimulation (VNS), most likely via enteric neurons, prevents postoperative ileus (POI) by reducing activation of alpha7 nicotinic receptor (α7nAChR) positive muscularis macrophages (mMφ) and dampening surgery-induced intestinal inflammation. Here, we evaluated if 5-HT4 receptor (5-HT4R) agonist prucalopride can mimic this effect in mice and human.

DESIGN

Using Ca²⁺ imaging, the effect of electrical field stimulation (EFS) and prucalopride was evaluated in situ on mMφ activation evoked by ATP in jejunal muscularis tissue. Next, preoperative and postoperative administration of prucalopride (1-5 mg/kg) was compared with that of preoperative VNS in a model of POI in wild-type and α7nAChR knockout mice. Finally, in a pilot study, patients undergoing a Whipple procedure were preoperatively treated with prucalopride (n=10), abdominal VNS (n=10) or sham/placebo (n=10) to evaluate the effect on intestinal inflammation and clinical recovery of POI.

RESULTS

EFS reduced the ATP-induced Ca²⁺ response of mMφ, an effect that was dampened by neurotoxins tetrodotoxin and ω-conotoxin and mimicked by prucalopride. In vivo, prucalopride administered before, but not after abdominal surgery reduced intestinal inflammation and prevented POI in wild-type, but not in α7nAChR knockout mice. In humans, preoperative administration of prucalopride, but not of VNS, decreased Il6 and Il8 expression in the muscularis externa and improved clinical recovery.

CONCLUSION

Enteric neurons dampen mMφ activation, an effect mimicked by prucalopride. Preoperative, but not postoperative treatment with prucalopride prevents intestinal inflammation and shortens POI in both mice and human, indicating that preoperative administration of 5-HT4R agonists should be further evaluated as a treatment of POI.

TRIAL REGISTRATION NUMBER

NCT02425774.

Therapeutic ultrasound attenuates DSS-induced colitis through the cholinergic anti-inflammatory pathway

BACKGROUND

Ulcerative Colitis (UC) is an Inflammatory Bowel Disease (IBD) characterized by uncontrolled immune response, diarrhoea, weight loss and bloody stools, where sustained remission is not currently achievable. Dextran Sulphate Sodium (DSS)-induced colitis is an animal model that closely mimics human UC. Ultrasound (US) has been shown to prevent experimental acute kidney injury through vagus nerve (VN) stimulation and activation of the cholinergic anti-inflammatory pathway (CAIP). Since IBD patients may present dysfunctional VN activity, our aim was to determine the effects of therapeutic ultrasound (TUS) in DSS-induced colitis.

METHODS

Acute colitis was induced by 2% DSS in drinking water for 7 days and TUS was administered to the abdominal area for 7 min/day from days 4-10. Clinical symptoms were analysed, and biological samples were collected for proteomics, macroscopic and microscopic analysis, flow cytometry and immunohistochemistry.

FINDINGS

TUS attenuated colitis by reducing clinical scores, colon shortening and histological damage, inducing proteomic tolerogenic response in the gut during the injury phase and early recovery of experimental colitis. TUS did not improve clinical and pathological outcomes in splenectomised mice, while α7nAChR (α7 nicotinic acetylcholine receptor - indicator of CAIP involvement) knockout animals presented with disease worsening. Increased levels of colonic F4/80+α7nAChR+ macrophages in wild type mice suggest CAIP activation.

INTERPRETATION

These results indicate TUS improved DSS-induced colitis through stimulation of the splenic nerve along with possible contribution by VN with CAIP activation. FUND: Intramural Research Programs of the Clinical Centre, the National Institute of Biomedical Imaging and Bioengineering at the NIH and CAPES/Brazil.

The antipsychotic medication, risperidone, causes global immunosuppression in healthy mice

Atypical antipsychotic medications such as risperidone are widely prescribed for diverse psychiatric indications including schizophrenia, bipolar disorder and depression. These medications have complex pharmacology and are associated with significant endocrine and metabolic side effects. This class of medications also carries FDA black box warnings due to increased risk of death in elderly patients. Clinical reports indicate that patients treated with these medications are more susceptible to infections; however, the underlying mechanisms/pharmacology are unclear. We have previously reported that risperidone and it’s active metabolite distributes to the bone marrow in clinically relevant concentrations in preclinical species, leading us to hypothesize that the hematopoietic system may be impacted by these medications. To test this hypothesis, using proteomic and cytokine array technology, we evaluated the expression of genes involved in inflammatory and immune function following short term (5 days) and longer term (4 weeks) treatment in healthy animals. We report that low-dose risperidone treatment results in global immunosuppression in mice, observed following 5 days of dosing and exacerbated with longer term drug treatment (4 weeks). These data are consistent with increased susceptibility to infection in patients administered these medications and have profound implications for the increasing off-label prescribing to vulnerable patient populations including children and the elderly.

Neural anti-inflammatory action mediated by two types of acetylcholine receptors in the small intestine

Gastrointestinal prokinetic agents function as serotonin-4 receptor (5-HT₄R) agonists to activate myenteric plexus neurons to release acetylcholine (ACh), which then induce anti-inflammatory action. Details of this pathway, however, remain unknown. The aim of this study is to clarify the anti-inflammatory mechanism underlying the 5-HT₄R agonist, mosapride citrate (MOS)-induced anti-inflammatory action on postoperative ileus (POI). POI models were generated from wild-type C57BL6/J (WT), 5-HT₄R knock-out (S4R KO), α7 nicotinic AChR KO (α7 R KO), and M2 muscarinic ACh receptor KO (M2R KO) mice. MOS attenuated leukocyte infiltration in WT. MOS-induced anti-inflammatory action was completely abolished in both S4R KO and S4R KO mice upon wild-type bone marrow transplantation. MOS-induced anti-inflammatory action against macrophage infiltration, but not neutrophil infiltration, was attenuated in α7 R KO mice. Selective α7nAChR agonists (PNU-282987 and AR-R17779) also inhibited only macrophage infiltration in POI. MOS-mediated inhibition of neutrophil infiltration was diminished by atropine, M2AChR antagonist, methoctramine, and in M2R KO mice. Stimulation with 5-HT₄R inhibits leukocyte infiltration in POI, possibly through myenteric plexus activation. Released ACh inhibited macrophage and neutrophil infiltration likely by activation of α7nAChR on macrophages and M2AChR. Thus, macrophage and neutrophil recruitment into inflamed sites is regulated by different types of AChR in the small intestine.

The effect of Toxoplasma gondii on plasma serotonin concentration in sheep

Background and Aim

Toxoplasma gondii is an intracellular parasite that commonly infects warm-blooded animals, including humans. Virtually all species can be infected, but a species-specific variability is evident, in terms of both type and severity of the symptoms encountered. As serotonin (5-hydroxytryptamine [5-HT]) plays an important regulatory role in both physiological and immune responses, the aim of this research was to assess whether toxoplasmosis disease could affect plasma 5-HT concentration and/or hematochemical parameters in a particularly susceptible species to infection as sheep.

Materials and Methods

5-HT plasma levels were analyzed in platelet-poor plasma fraction by enzyme-linked immunosorbent assay. Blood count and hematochemical parameters were evaluated. Total proteins (TPs), glucose (Glu), and lactate dehydrogenase were determined by a spectrophotometer.

Results

Results showed significantly higher levels in plasma 5-HT, monocytes, and TP and significantly lower levels of Glu, in infected sheep compared to the control group.

Conclusion

Results could support the hypothesis of an effect of toxoplasmosis infection on plasma 5-HT concentrations in sheep. More research is needed to assess the function of 5-HT in the regulation of infected sheep's immune responses.

Neuronal regulation of intestinal immune functions in health and disease

BACKGROUND

Nerve-mucosa interactions control various elements of gastrointestinal functions, including mucosal host defense, gut barrier function, and epithelial cell growth and differentiation. In both intestinal and extra-intestinal diseases, alterations of autonomic nerve activity have been observed to be concurrent with the disease course, such as in inflammatory and functional bowel diseases, and neurodegenerative diseases. This is relevant as the extrinsic autonomic nervous system is increasingly recognized to modulate gut inflammatory responses. The molecular and cellular mechanisms through which the extrinsic and intrinsic nerve pathways may regulate digestive mucosal functions have been investigated in several pre-clinical and clinical studies.

PURPOSE

The present review focuses on the involvement of neural pathways in gastrointestinal disease, and addresses the current strategies to intervene with neuronal pathway as a means of treatment.

Possible anti-inflammatory role of Zingiberis processum rhizoma, one component of the Kampo formula daikenchuto, against neutrophil infiltration through muscarinic acetylcholine receptor activation

Zingiberis processum rhizoma (ZPR) is a major active component of daikenchuto (DKT), which induces anti-inflammatory action by inhibiting macrophage infiltration. However, it is unclear whether ZPR is related to DKT-induced anti-inflammatory action via a reduction of neutrophil infiltration against postoperative ileus (POI). In this study, we orally administered individual herbal components of DKT to mice four times before and after intestinal manipulation (IM). The anti-inflammatory action of each crude drug was evaluated by histochemical analysis of relevant molecules. The results showed that treatment with all herbal components of DKT significantly inhibits neutrophil infiltration. This inhibition of neutrophil infiltration by ZPR was significantly reduced in 5-hydroxytryptamine receptor 4 (5-HT₄R) knockout (KO) mice but not in alpha-7 nicotinic acetylcholine receptor (α7nAChR) KO mice. Also, transient receptor potential ankyrin 1 (TRPA1) and muscarinic acetylcholine receptor (mAChR) antagonists partly and significantly inhibited the amelioration of neutrophil infiltration by ZPR. Therefore, DKT-induced anti-inflammatory action, mediated by inhibition of neutrophil infiltration in POI, depends, in part, on the effects of ZPR. ZPR activates TRPA1 channels, possibly in enterochromaffin (EC) cells, to release 5-HT. This 5-HT stimulates 5-HT₄R in the myenteric plexus neurons to release acetylcholine, which, in turn, activates mAChR to inhibit inflammation in POI.

Role of transient receptor potential melastatin 2 in surgical inflammation and dysmotility in a mouse model of postoperative ileus

In this study, we investigated the role of transient receptor potential melastatin 2 (TRPM2), a nonselective cation channel abundantly expressed in inflammatory cells such as macrophages, in the development of postoperative ileus, a complication of abdominal surgery characterized by gastrointestinal dysmotility. In wild-type mice, we found that intestinal manipulation, a maneuver that elicits symptoms typical of postoperative ileus, delays the transit of fluorescein-labeled dextran, promotes the infiltration of CD68⁺ macrophages, Ly6B.2⁺ neutrophils, and MPO⁺ cells into intestinal muscles, boosts expression of IL-1β, IL-6, TNF-α, iNOS, and CXCL2 in intestinal muscles and peritoneal macrophages, enhances phosphorylation of ERK and p38 MAPK in intestinal muscles, and amplifies IL-1β, IL-6, TNF-α, iNOS, and CXCL2 expression in resident and thioglycolate-elicited peritoneal macrophages following exposure to lipopolysaccharide. Remarkably, TRPM2 deficiency completely blocks or diminishes these effects. Indeed, intestinal manipulation appears to activate TRPM2 in resident muscularis macrophages and elicits release of inflammatory cytokines and chemokines, which, in turn, promote infiltration of macrophages and neutrophils into the muscle, ultimately resulting in dysmotility. NEW & NOTEWORTHY Activation of transient receptor potential melastatin 2 (TRPM2) releases inflammatory cytokines and chemokines, which, in turn, promote the infiltration of inflammatory cells and macrophages into intestinal muscles, ultimately resulting in dysmotility. Thus TRPM2 is a promising target in treating dysmotility due to postoperative ileus, a complication of abdominal surgery.

α7 Nicotinic acetylcholine receptor contributes to the alleviation of lung ischemia-reperfusion injury by transient receptor potential vanilloid type 1 stimulation

BACKGROUND

Activation of transient receptor potential vanilloid type 1 (TRPV1) decreases lung ischemia-reperfusion injury (LIRI) in rabbits and rats. Stimulation of α7 nicotinic acetylcholine receptors (α7nAChRs) protects against lung injury. Here we examined whether α7nAChRs contribute to TRPV1-mediated protection against LIRI.

METHODS

Wild-type (WT) and TRPV1-knockout (KO) mice were subjected to 1-h lung ischemia by clamping left hilum, followed by 2-h reperfusion. WT or KO mice were pretreated with vehicle, TRPV1 agonist capsaicin, TRPV1 antagonist capsazepine, α7nAChR antagonist methyllycaconitine, or α7nAChR agonist PNU-282987. Arterial blood and lung tissues were obtained for blood gas, lung wet-to-dry weight ratio, interleukin (IL)1β, IL6, tumor necrosis factor-α (TNF-α), apoptosis-related proteins (caspases, Bax, Fas), and pathologic scoring.

RESULTS

Capsaicin pretreatment reduced wet-to-dry ratio, pathologic score, alveolar-arterial oxygen gradient (A-aDO₂), and IL1β, IL6, and TNFα levels in WT mice, with no effects in KO mice. This reduction was reversed by TRPV1 blockade. Furthermore, α7nAChR blockade before capsaicin exacerbated LIRI as evidenced by enhanced alveolar-arterial oxygen gradient, pathologic score, and IL1β, IL6, and TNFα levels, while α7nAChR agonist pretreatment under TRPV1 blockade showed opposite changes. Capsaicin also decreased cleaved caspase-3, caspase-3/9, and Bax protein expression, effects abolished by TRPV1 blockade. Similarly, α7nAChR blockade diminished capsaicin-induced downregulation of apoptotic proteins, and α7nAChR activation decreased expression levels even under TRPV1 blockade.

CONCLUSIONS

TRPV1 activation alleviates LIRI, partially dependent on α7nAChR activity. The α7nAChR stimulation with or without existence of TRPV1 alleviates LIRI. Thus, α7nAChR is involved in the pathway of TRPV1-mediated protection against LIRI and the specific mechanism remains to be revealed.

Disruption of the pacemaker activity of interstitial cells of Cajal via nitric oxide contributes to postoperative ileus

BACKGROUND

Interstitial cells of Cajal (ICC) serve as intestinal pacemakers. Postoperative ileus (POI) is a gastrointestinal motility disorder that occurs following abdominal surgery, which is caused by inflammation-induced dysfunction of smooth muscles and enteric neurons. However, the participation of ICC in POI is not well understood. In this study, we investigated the functional changes of ICC in a mouse model of POI.

METHODS

Intestinal manipulation (IM) was performed to induce POI. At 24 h or 48 h after IM, the field potential of the intestinal tunica muscularis was investigated. Tissues were also examined by immunohistochemistry and electron microscopic analysis.

KEY RESULTS

Gastrointestinal transit was significantly decreased with intestinal tunica muscularis inflammation at 24 h after IM, which was ameliorated at 48 h after IM. The generation and propagation of pacemaker potentials were disrupted at 24 h after IM and recovered to the control level at 48 h after IM. ICC networks, detected by c-Kit immunoreactivity, were remarkably disrupted at 24 h after IM. Electron microscopic analysis revealed abnormal vacuoles in the ICC cytoplasm. Interestingly, the ICC networks recovered at 48 h after IM. Administration of aminoguanidine, an inducible nitric oxide synthase inhibitor, suppressed the disruption of ICC networks. Ileal smooth muscle tissue cultured in the presence of nitric oxide donor, showed disrupted ICC networks.

CONCLUSIONS AND INFERENCES

The generation and propagation of pacemaker potentials by ICC are disrupted via nitric oxide after IM, and this disruption may contribute to POI. When inflammation is ameliorated, ICC can recover their pacemaker function.

Orally administered nicotine effects on rat urinary bladder proliferation and carcinogenesis

Tobacco smoking is a major risk factor for human cancers including urinary bladder carcinoma. Cigarette smoke inhalation in mice and orally administered nicotine in rats and mice increased urothelial cell proliferation. Nicotine, a major component of smoke, induced cell proliferation in multiple cell types in vitro. In the present study, the enhancing effects of nicotine on F344 rat bladder carcinogenesis induced by N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) were examined. Nicotine administered in drinking water for 32 weeks following 4 weeks of BBN treatment significantly increased the incidence and number of urothelial carcinomas dose-dependently. Ki67 and pSTAT3 labeling indices and expression of nicotinic acetylcholine receptor alpha 7 (nAChRα7) in non-tumor bladder urothelial lesions were significantly increased by nicotine, but the TUNEL assay for apoptosis showed no increase. In a 4 week study, inhibitors of nicotinic acetylcholine receptor decreased nicotine-induced urothelial simple hyperplasia and Ki67 labeling index in the bladder and kidney pelvis at a single cytotoxic dose of nicotine (40 ppm). Urothelial cytotoxicity with regenerative proliferation was observed by light and scanning electron microscopy. In vitro, nicotine was not cytotoxic to rat or human immortalized urothelial cells (do not express nicotine receptors) below millimolar concentrations, nor in human RT4, T24 or UMUC3 urothelial carcinoma cells (express nicotine receptors). However, nicotine slightly, but statistically significantly, increased cell proliferation at micromolar concentrations in human urothelial carcinoma cells. These data suggest that nicotine enhances urinary bladder carcinogenesis by inducing cytotoxicity with regenerative proliferation. The possible role of direct mitogenesis, involving nAChR and STAT3 signaling and of nicotine receptors requires further investigation at non-cytotoxic doses of nicotine.

Postoperative ileus following major colorectal surgery

BACKGROUND

Postoperative ileus (POI) is characterized by delayed gastrointestinal recovery following surgery. Current knowledge of pathophysiology, clinical interventions and methodological challenges was reviewed to inform modern practice and future research.

METHODS

A systematic search of MEDLINE and Embase databases was performed using search terms related to ileus and colorectal surgery. All RCTs involving an intervention to prevent or reduce POI published between 1990 and 2016 were identified. Grey literature, non-full-text manuscripts, and reanalyses of previous RCTs were excluded. Eligible articles were assessed using the Cochrane tool for assessing risk of bias.

RESULTS

Of 5614 studies screened, 86 eligible articles describing 88 RCTs were identified. Current knowledge of pathophysiology acknowledges neurogenic, inflammatory and pharmacological mechanisms, but much of the evidence arises from animal studies. The most common interventions tested were chewing gum (11 trials) and early enteral feeding (11), which are safe but of unclear benefit for actively reducing POI. Others, including thoracic epidural analgesia (8), systemic lidocaine (8) and peripheral μ antagonists (5), show benefit but require further investigation for safety and cost-effectiveness.

CONCLUSION

POI is a common condition with no established definition, aetiology or treatment. According to current literature, minimally invasive surgery, protocol-driven recovery (including early feeding and opioid avoidance strategies) and measures to avoid major inflammatory events (such as anastomotic leak) offer the best chances of reducing POI.