ZD 7288,an HCN channel blocker,attenuates chronic visceral pain in irritable bowel syndrome-like rats

AIM: To investigate the effects of ZD 7288, a hyperpolarization-activated cyclic nucleotide-gated (HCN) channel blocker, on rats with chronic visceral pain.

Serotonin receptor 2B induces visceral hyperalgesia in rat model and patients with diarrhea-predominant irritable bowel syndrome

BACKGROUND Serotonin receptor 2B(5-HT2B receptor)plays a critical role in many chronic pain conditions.The possible involvement of the 5-HT2B receptor in the altered gut sensation of irritable bowel syndrome with diarrhea(IBS-D)was investigated in the present study.AIM To investigate the possible involvement of 5-HT2B receptor in the altered gut sensation in rat model and patients with IBS-D.METHODS Rectosigmoid biopsies were collected from 18 patients with IBS-D and 10 patients with irritable bowel syndrome with constipation who fulfilled the Rome IV criteria and 15 healthy controls.The expression level of the 5-HT2B receptor in colon tissue was measured using an enzyme-linked immunosorbent assay and correlated with abdominal pain scores.The IBS-D rat model was induced by intracolonic instillation of acetic acid and wrap restraint.Alterations in visceral sensitivity and 5-HT2B receptor and transient receptor potential vanilloid type 1(TRPV1)expression were examined following 5-HT2B receptor antagonist adminis-tration.Changes in visceral sensitivity after administration of the TRPV1 antago-INTRODUCTION Irritable bowel syndrome(IBS)is a chronic functional bowel disorder characterized by recurrent abdominal pain with altered bowel habits that affects approximately 15%of the population worldwide[1].IBS significantly impacts the quality of life of patients.Although the pathogenesis of IBS is not completely understood,the role of abnormal visceral sensitivity in IBS has recently emerged[2,3].5-Hydroxytryptamine(5-HT)is known to play a key role in the physiological states of the gastrointestinal tract.Plasma 5-HT levels in IBS with diarrhea(IBS-D)patients were greater than those in healthy controls[4],suggesting a possible role of 5-HT in the pathogenesis of IBS-D.The serotonin receptor 2(5-HT2 receptor)family comprises three subtypes:5-HT2A,5-HT2B,and 5-HT2c.All 5-HT2 receptors exhibit 46%-50%overall sequence identity,and all of these receptors preferentially bind to Gq/11 to increase inositol phosphates and intracellular calcium mobilization[5].5-HT2B receptors are widely expressed throughout the gut,and experimental evidence suggests that the primary function of 5-HT2B receptors is to mediate contractile responses to 5-HT through its action on smooth muscle[6].The 5-HT2B receptor is localized to both neurons of the myenteric nerve plexus and smooth muscle in the human colon.The 5-HT2B receptor mediates 5-HT-evoked contraction of longitudinal smooth muscle[6].These findings suggest that the 5-HT2B receptor could play an important role in modulating colonic motility,which could affect sensory signaling in the gut.Other laboratories have shown that the 5-HT2B receptor participates in the development of mechanical and formalin-induced hyperalgesia[7,8].A 5-HT2B receptor antagonist reduced 2,4,6-trinitrobenzene sulfonic acid(TNBS)and stress-induced visceral hyperalgesia in rats[9,10].However,the role of the 5-HT2B receptor in IBS-D patients and in acetic acid-and wrap restraint-induced IBS-D rat models was not investigated.

Chitin-glucan improves important pathophysiological features of irritable bowel syndrome

BACKGROUND Irritable bowel syndrome(IBS)is one of the most frequent and debilitating conditions leading to gastroenterological referrals.However,recommended treatments remain limited,yielding only limited therapeutic gains.Chitin-glucan(CG)is a novel dietary prebiotic classically used in humans at a dosage of 1.5-3.0 g/d and is considered a safe food ingredient by the European Food Safety Authority.To provide an alternative approach to managing patients with IBS,we performed preclinical molecular,cellular,and animal studies to evaluate the role of chitin-glucan in the main pathophysiological mechanisms involved in IBS.AIM To evaluate the roles of CG in visceral analgesia,intestinal inflammation,barrier function,and to develop computational molecular models.METHODS Visceral pain was recorded through colorectal distension(CRD)in a model of long-lasting colon hypersensitivity induced by an intra-rectal administration of TNBS[15 milligrams(mg)/kilogram(kg)]in 33 Sprague-Dawley rats.Intracolonic pressure was regularly assessed during the 9 wk-experiment(weeks 0,3,5,and 7)in animals receiving CG(n=14)at a human equivalent dose(HED)of 1.5 g/d or 3.0 g/d and compared to negative control(tap water,n=11)and positive control(phloroglucinol at 1.5 g/d HED,n=8)groups.The anti-inflammatory effect of CG was evaluated using clinical and histological scores in 30 C57bl6 male mice with colitis induced by dextran sodium sulfate(DSS)administered in their drinking water during 14 d.HT-29 cells under basal conditions and after stimulation with lipopolysaccharide(LPS)were treated with CG to evaluate changes in pathways related to analgesia μ-opioid receptor(MOR),cannabinoid receptor 2(CB2),peroxisome proliferator-activated receptor alpha,inflammation[interleukin(IL)-10,IL-1b,and IL-8]and barrier function[mucin 2-5AC,claudin-2,zonula occludens(ZO)-1,ZO-2]using the real-time PCR method.Molecular modelling of CG,LPS,lipoteichoic acid(LTA),and phospholipomannan(PLM)was developed,and the ability of CG to chelate microbial pathogenic lipids was evaluated by docking and molecular dynamics simulations.Data were expressed as the mean±SEM.RESULTS Daily CG orally-administered to rats or mice was well tolerated without including diarrhea,visceral hypersensitivity,or inflammation,as evaluated at histological and molecular levels.In a model of CRD,CG at a dosage of 3 g/d HED significantly decreased visceral pain perception by 14%after 2 wk of administration(P<0.01)and reduced inflammation intensity by 50%,resulting in complete regeneration of the colonic mucosa in mice with DSS-induced colitis.To better reproduce the characteristics of visceral pain in patients with IBS,we then measured the therapeutic impact of CG in rats with TNBS-induced inflammation to long-lasting visceral hypersensitivity.CG at a dosage of 1.5 g/d HED decreased visceral pain perception by 20%five weeks after colitis induction(P<0.01).When the CG dosage was increased to 3.0 g/d HED,this analgesic effect surpassed that of the spasmolytic agent phloroglucinol,manifesting more rapidly within 3 wk and leading to a 50%inhibition of pain perception(P<0.0001).The underlying molecular mechanisms contributing to these analgesic and anti-inflammatory effects of CG involved,at least in part,a significant induction of MOR,CB2 receptor,and IL-10,as well as a significant decrease in pro-inflammatory cytokines IL-1b and IL-8.CG also significantly upregulated barrier-related genes including muc5AC,claudin-2,and ZO-2.Molecular modelling of CG revealed a new property of the molecule as a chelator of microbial pathogenic lipids,sequestering gram-negative LPS and gram-positive LTA bacterial toxins,as well as PLM in fungi at the lowesr energy conformations.CONCLUSION CG decreased visceral perception and intestinal inflammation through master gene regulation and direct binding of microbial products,suggesting that CG may constitute a new therapeutic strategy for patients with IBS or IBSlike symptoms.

Lactobacillus plantarum AR495 improves stress-induced irritable bowel syndrome in rats by targeting gut microbiota and Mast cell-PAR2-TRPV1 signaling pathway

Probiotics have great potential in regulating intestinal pain.In this study,the effects of Lactobacillus plantarum AR495 on the visceral sensitivity and gut microbiota of irritable bowel syndrome(IBS)rats were studied.The results showed that tryptase released after mast cell activation and degranulation plays a key role in visceral pain,and L.plantarum AR495 reduced the stimulation of colonic mast cells and the expression of protease-activated receptor 2(PAR2)and TRPV1 in dorsal root ganglia.Research further showed that supplementation with L.plantarum AR495 increased the level of short-chain fatty acids(SCFAs)and enhanced the barrier function of the colon.In addition,the microbiota analysis of the colon indicated that L.plantarum AR495 promoted the proliferation of Bifidobacterium and inhibited the proliferation of Lachnospiraceae,which alleviated the imbalance of the intestinal microbiota caused by IBS to a certain extent.In total,L.plantarum AR495 might reduce visceral sensitivity through the Mast cell-PAR2-TRPV1 signaling pathway by maintaining the homeostasis of the intestinal barrier.

Efficacy and tolerability of chitin-glucan combined with simethicone(GASTRAP^(■)DIRECT)in irritable bowel syndrome:A prospective,open-label,multicenter study

BACKGROUND Irritable bowel syndrome(IBS),defined according to the Rome IV diagnostic criteria,is a chronic functional gastrointestinal disorder characterized by recurrent abdominal pain related to altered bowel habits.First-line recommended treatments are limited to combining drugs targeting predominant symptoms,particularly pain(antispasmodics),constipation(laxatives),and diarrhea(loperamide),yielding only a limited therapeutic gain.GASTRAP^(■)DIRECT is a class IIa medical formulation composed of a combination of chitin-glucan and simethicone indicated for the symptomatic treatment of gas-related gastrointestinal disorders by combining different mechanisms of action.AIM To evaluate the efficacy,tolerability,and safety of 4-week GASTRAP^(■)DIRECT treatment in patients with IBS.METHODS In this prospective,multicenter,open-label trial,120 patients with IBS received three sticks of GASTRAP^(■)DIRECT(1.5 g/d of chitin-glucan and 0.75 mg/d of simethicone)per day for 4 weeks.The primary endpoint was the responder rate,defined as the number of patients whose abdominal pain score decreased by≥30%from baseline to week(W)4.The analysis was performed using the per-protocol set.Cardinal symptoms,impact of global symptoms on daily life,change in stool consistency,and improvement in defecatory disorders were evaluated.RESULTS Overall,100 patients were evaluated.At W4,67%(95%CI:57-75)showed improvement in abdominal pain(score:5.8±2.4 vs 2.9±2.0,P<0.0001).Similar improvements were observed for bloating[8.0±1.7 vs 4.7±2.9,P<0.0001;60%(95%CI:50-70)responders],abdominal distension[7.2±2.1 vs 4.4±3.1,P<0.0001;53%(95%CI:43-63)responders],and impact of global symptoms on daily life[7.1±2.0 vs 4.6±2.9,P<0.0001;54%(95%CI:44-64)responders].Stool consistency improved in most patients(90%and 57%for patients with liquid and hard stools,respectively).Overall,42%of patients with defecatory disorders reported very much/considerable improvements by W2.No severe adverse event occurred,and tolerability was rated“good”or“very good”by 93%of patients.CONCLUSION GASTRAP^(■)DIRECT is safe and well tolerated,alleviating IBS symptoms rapidly in 2 weeks.This open-label study suggests that the combination of chitin-glucan and simethicone could be beneficial in patients with IBS.

Abnormal endogenous pain modulation and somatic and visceral hypersensitivity in female patients with irritable bowel syndrome

AIM： To investigate the role of endogenous pain modulatory mechanisms in the central sensitization implicated by the visceral hypersensitivity demonstrated in patients with irritable bowel syndrome （IBS）. Dysfunction of modulatory mechanisms would be expected to also result in changes of somatic sensory function. METHODS： Endogenous pain modulatory mechanisms were assessed using heterotopic stimulation and somatic and visceral sensory testing in IBS. Pain intensities （visual analogue scale, VAS 0-100） during suprathreshold rectal distension with a barostat, cold pressor stimulation of the foot and during both stimuli simultaneously （heterotopic stimulation） were recorded in 40 female patients with IBS and 20 female healthy controls. RESULTS： Rectal hypersensitivity （defined by 95% Cl of controls） was seen in 21 （53%）, somatic hypersensitivity in 22 （55%） and both rectal and somatic hypersensitivity in 14 of these IBS patients. Heterotopic stimulation decreased rectal pain intensity by 6 （-11 to -1） in controls, but increased rectal pain by 2 （-3 to ＋6） in all IBS patients （P 〈 0.05） and by 8 （-2 to ＋19） in IBS patients with somatic and visceral hypersensitivity （P 〈 0.02）. CONCLUSION： A majority of IBS patients had abnormal endogenous pain modulation and somatic hypersensitivity as evidence of central sensitization.

Serotonin transporter and cholecystokinin in diarrhea-predominant irritable bowel syndrome: Associations with abdominal pain, visceral hypersensitivity and psychological performance

BACKGROUND Visceral hypersensitivity and psychological performance are the main pathophysiological mechanisms of irritable bowel syndrome(IBS).Previous studies have found that cholecystokinin(CCK)can enhance colon movement and that serotonin transporter(SERT)is a transmembrane transport protein with high affinity for 5-hydroxytryptamine,which can rapidly reuptake 5-hydroxytryptamine and then regulate its action time and intensity.We speculate that SERT and CCK might play a role in the pathogenesis of diarrheapredominant IBS(IBS-D)by affecting visceral sensitivity and the brain-gut axis.AIM To determine SERT and CCK levels in IBS-D patients diagnosed using Rome IV criteria and to analyze their associations with abdominal pain,visceral hypersensitivity and psychological performance.METHODS This study collected data from 40 patients with IBS-D at the China-Japan Friendship Hospital from September 2017 to April 2018 and 18 healthy controls.The severity of abdominal pain,visceral sensitivity and psychological performance were evaluated in IBS-D patients and healthy controls,the levels of SERT and CCK in plasma and colonic mucosa were evaluated,and the correlations between them were analyzed.RESULTS There were significant differences in the initial sensation threshold(31.00±8.41 mL vs 52.22±8.09 mL,P<0.001),defecating sensation threshold(51.75±13.57 mL vs 89.44±8.73 mL,P<0.001)and maximum tolerable threshold(97.25±23.64 mL vs 171.11±20.83 mL,P<0.001)between the two groups.IBS-D patients had more severe anxiety(7.78±2.62 vs 2.89±1.02,P<0.001)and depressive(6.38±2.43 vs 2.06±0.73,P<0.001)symptoms than healthy controls.Significant differences were also found in mucosal CCK(2.29±0.30 vs 1.66±0.17,P<0.001)and SERT(1.90±0.51 vs 3.03±0.23,P<0.001)between the two groups.There was a significant positive correlation between pain scores and mucosal CCK(r=0.96,0.93,0.94,P<0.001).Significant negative correlations between anxiety(r=-0.98;P<0.001),depression(r=-0.99;P<0.001),pain evaluation(r=-0.96,-0.93,-0.95,P<0.001)and mucosal SERT were observed.CONCLUSION IBS-D patients had psychosomatic disorders and visceral hypersensitivity.SERT and CCK might be involved in the pathogenesis of IBS-D by regulating the braingut axis and affecting visceral sensitivity.This provides a new potential method for identifying a more specific and effective therapeutic target.

Increased expression of brain-derived neurotrophic factor is correlated with visceral hypersensitivity in patients with diarrheapredominant irritable bowel syndrome

BACKGROUND Visceral hypersensitivity is considered to play a vital role in the pathogenesis of irritable bowel syndrome(IBS). Neurotrophins have drawn much attention in IBS recently. Brain-derived neurotrophic factor(BDNF) was found to mediate visceral hypersensitivity via facilitating sensory nerve growth in pre-clinical studies. We hypothesized that BDNF might play a role in the pathogenesis of diarrhea-predominant IBS(IBS-D).AIM To investigate BDNF levels in IBS-D patients and its role in IBS-D pathophysiology.METHODS Thirty-one IBS-D patients meeting the Rome IV diagnostic criteria and 20 ageand sex-matched healthy controls were recruited. Clinical and psychological assessments were first conducted using standardized questionnaires. Visceral sensitivity to rectal distension was tested using a high-resolution manometry system. Colonoscopic examination was performed and four mucosal pinch biopsies were taken from the rectosigmoid junction. Mucosal BDNF expression and nerve fiber density were analyzed using immunohistochemistry. Mucosal BDNF mRNA levels were quantified by quantitative real-time polymerase chain reaction. Correlations between these parameters were examined.RESULTS The patients had a higher anxiety score [median(interquartile range), 6.0(2.0-10.0) vs 3.0(1.0-4.0), P = 0.003] and visceral sensitivity index score [54.0(44.0-61.0)vs 21.0(17.3-30.0), P < 0.001] than controls. The defecating sensation threshold[60.0(44.0-80.0) vs 80.0(61.0-100.0), P = 0.009], maximum tolerable threshold[103.0(90.0-128.0) vs 182.0(142.5-209.3), P < 0.001] and rectoanal inhibitory reflex threshold [30.0(20.0-30.0) vs 30.0(30.0-47.5), P = 0.032] were significantly lower in IBS-D patients. Intestinal mucosal BDNF protein [3.46 E-2(3.06 E-2-4.44 E-2) vs3.07 E-2(2.91 E-2-3.48 E-2), P = 0.031] and mRNA [1.57(1.31-2.61) vs 1.09(0.74-1.42), P = 0.001] expression and nerve fiber density [4.12 E-2(3.07 E-2-7.46 E-2) vs1.98 E-2(1.21 E-2-4.25 E-2), P = 0.002] were significantly elevated in the patients.Increased BDNF expression was positively correlated with abdominal pain and disease severity and negatively correlated with visceral sensitivity parameters.CONCLUSION Elevated mucosal BDNF may participate in the pathogenesis of IBS-D via facilitating mucosal nerve growth and increasing visceral sensitivity.

TLR4 upregulates CBS expression through NF-κB activation in a rat model of irritable bowel syndrome with chronic visceral hypersensitivity

AIM:To investigate the roles of toll-like receptor 4(TLR4) and nuclear factor(NF)-κB on cystathionine βsynthetase(CBS) expression and visceral hypersensitivity in rats.METHODS:This study used 1-7-wk-old male SpragueDawley rats.Western blot analysis was employed to measure the expression of TLR4,NF-kB and the endogenous hydrogen sulfide-producing enzyme CBS in colon dorsal root ganglia(DRG) from control and "irritable bowel syndrome" rats induced by neonatal colonic inflammation(NCI).Colon-specific DRG neurons were labeled with Dil and acutely dissociated to measure excitability with patch-clamp techniques.Immunofluorescence was employed to determine the co-expression of TLR4,NF-kB and CBS in Dil-labeled DRG neurons.RESULTS:NCI significantly upregulated the expression of TLR4 in colon-related DRGs(0.34 ± 0.12 vs 0.72 ±0.02 for the control and NCI groups,respectively,P <0.05).Intrathecal administration of the TLR4-selective inhibitor CLI-095 significantly enhanced the colorectal distention threshold of NCI rats.CLI-095 treatment also markedly reversed the hyperexcitability of colonspecific DRG neurons and reduced the expression of CBS(1.7 ± 0.1 vs 1.1 ± 0.04,p < 0.05) and of the NF-kB subunit p65(0.8 ± 0.1 vs 0.5 ± 0.1,P< 0.05).Furthermore,the NF-KB-selective inhibitor pyrrolidine dithiocarbamate(PDTC) significantly reduced the upregulation of CBS(1.0 ± 0.1 vs 0.6 ± 0.1,P< 0.05)and attenuated visceral hypersensitivity in the NCI rats.In vitro,incubation of cultured DRG neurons with the TLR4 agonist lipopolysaccharide significantly enhanced the expression of p65(control vs 8 h:0.9 ± 0.1 vs1.3 ± 0.1;control vs 12 h:0.9 ± 0.1 vs 1.3 ± 0.1,P< 0.05;control vs 24 h:0.9 ± 0.1 vs 1.6 ± 0.1,P <0.01) and CBS(control vs 12 h:1.0 ± 0.1 vs 2.2 ±0.4;control vs 24 h:1.0 ± 0.1 vs 2.6 ± 0.1,P< 0.05),whereas the inhibition of p65 via pre-incubation with PDTC significantly reversed the upregulation of CBS expression(1.2 ± 0.1 vs 0.6 ± 0.0,P< 0.01).CONCLUSION:Our results suggest that the activation of TLR4 by NCI upregulates CBS expression,which is mediated by the NF-kB signaling pathway,thus contributing to visceral hypersensitivity.

Altered profiles of fecal metabolites correlate with visceral hypersensitivity and may contribute to symptom severity of diarrhea-predominant irritable bowel syndrome

BACKGROUND Fecal metabolites are associated with gut visceral sensitivity,mucosal immune function and intestinal barrier function,all of which have critical roles in the pathogenesis of irritable bowel syndrome(IBS).However,the metabolic profile and pathophysiology of IBS are still unclear.We hypothesized that altered profiles of fecal metabolites might be involved in the pathogenesis of IBS with predominant diarrhea(IBS-D).AIM To investigate the fecal metabolite composition and the role of metabolites in IBSD pathophysiology.METHODS Thirty IBS-D patients and 15 age-and sex-matched healthy controls(HCs)underwent clinical and psychological assessments,including the IBS Symptom Severity System(IBS-SSS),an Italian modified version of the Bowel Disease Questionnaire,the Bristol Stool Form Scale(BSFS),the Hospital Anxiety and Depression Scale,and the Visceral Sensitivity Index.Visceral sensitivity to rectal distension was tested using high-resolution manometry system by the same investigator.Fecal metabolites,including amino acids and organic acids,were measured by targeted metabolomics approaches.Correlation analyses between these parameters were performed.RESULTS The patients presented with increased stool water content,more psychological symptoms and increased visceral hypersensitivity compared with the controls.In fecal metabolites,His[IBS-D:0.0642(0.0388,0.1484),HC:0.2636(0.0780,0.3966),P=0.012],Ala[IBS-D:0.5095(0.2826,0.9183),HC:1.0118(0.6135,1.4335),P=0.041],Tyr[IBS-D:0.1024(0.0173,0.4527),HC:0.5665(0.2436,1.3447),P=0.018],Phe[IBS-D:0.1511(0.0775,0.3248),HC:0.3967(0.1388,0.7550),P=0.028],and Trp[IBS-D:0.0323(0.0001,0.0826),HC:0.0834(0.0170,0.1759),P=0.046]were decreased in IBS-D patients,but isohexanoate[IBS-D:0.0127(0.0060,0.0246),HC:0.0070(0.0023,0.0106),P=0.028]was significantly increased.Only Tyr was mildly correlated with BSFS scores in all subjects(r=-0.347,P=0.019).A possible potential biomarker panel was identified to correlate with IBS-SSS score(R2 Adjusted=0.693,P<0.001).In this regression model,the levels of Tyr,Val,hexanoate,fumarate,and pyruvate were significantly associated with the symptom severity of IBS-D.Furthermore,visceral sensation,including abdominal pain and visceral hypersensitivity,was correlated with isovalerate,valerate and isohexanoate.CONCLUSION Altered profiles of fecal metabolites may be one of the origins or exacerbating factors of symptoms in IBS-D via increasing visceral sensitivity.

Visceral hypersensitivity in inflammatory bowel diseases and irritable bowel syndrome: The role of proteases

Proteases, enzymes catalyzing the hydrolysis of peptide bonds, are present at high concentrations in the gastrointestinal tract. Besides their well-known role in the digestive process, they also function as signaling molecules through the activation of protease-activated receptors(PARs). Based on their chemical mechanism for catalysis, proteases can be classified into several classes: serine, cysteine, aspartic, metallo- and threonine proteases represent the mammalian protease families. In particular, the class of serine proteases will play a significant role in this review. In the last decades, proteases have been suggested to play a key role in the pathogenesis of visceral hypersensitivity, which is a major factor contributing to abdominal pain in patients with inflammatory bowel diseases and/or irritable bowel syndrome. So far, only a few preclinical animal studies have investigated the effect of protease inhibitors specifically on visceral sensitivity while their effect on inflammation is described in more detail. In our accompanying review we describe their effect on gastrointestinal permeability. On account of their promising results in the field of visceral hypersensitivity, further research is warranted. The aim of this review is to give an overview on the concept of visceral hypersensitivity as well as on the physiological and pathophysiological functions of proteases herein.

Fructo-oligosaccharide intensifies visceral hypersensitivity and intestinal inflammation in a stress-induced irritable bowel syndrome mouse model

AIM To determine whether fructo-oligosaccharide(FOS) affects visceral sensitivity, inflammation, and production of intestinal short-chain fatty acids(SCFA) in an irritable bowel syndrome(IBS) mouse model.METHODS Mice were randomly assigned to daily oral gavage of saline solution with or without FOS(8 g/kg body weight) for 14 d. Mice were further assigned to receive either daily one-hour water avoidance stress(WAS) or sham-WAS for the first 10 d. After 2 wk, visceral sensitivity was measured by abdominal withdrawal reflex in response to colorectal distension and mucosal inflammation was evaluated. Gas chromatography, real-time reverse transcription PCR, and immunohistochemistry assays were used to quantify cecal concentrations of SCFA, intestinal cytokine expression, and number of intestinal mast cells per high-power field(HPF), respectively.RESULTS Mice subjected to WAS exhibited visceral hypersensitivity and low-grade inflammation. Among mice subjected to WAS, FOS increased visceral hypersensitivity and led to higher cecal concentrations of acetic acid(2.49 ± 0.63 mmol/L vs 1.49 ± 0.72 mmol/L, P < 0.05), propionic acid(0.48 ± 0.09 mmol/L vs 0.36 ± 0.05 mmol/L, P < 0.01), butyric acid(0.28 ± 0.09 mmol/L vs 0.19 ± 0.003 mmol/L, P < 0.05), as well as total SCFA(3.62 ± 0.87 mmol/L vs 2.27 ± 0.75 mmol/L, P < 0.01) compared to saline administration. FOS also increased ileal interleukin(IL)-23 mR NA(4.71 ± 4.16 vs 1.00 ± 0.99, P < 0.05) and colonic IL-1β mR NA(2.15 ± 1.68 vs 0.88 ± 0.53, P < 0.05) expressions as well as increased mean mast cell counts in the ileum(12.3 ± 2.6 per HPF vs 8.3 ± 3.6 per HPF, P < 0.05) and colon(6.3 ± 3.2 per HPF vs 3.4 ± 1.2 per HPF, P < 0.05) compared to saline administration in mice subjected to WAS. No difference in visceral sensitivity, intestinal inflammation, or cecal SCFA levels was detected with or without FOS administration in mice subjected to sham-WAS.CONCLUSION FOS administration intensifies visceral hypersensitivity and gut inflammation in stress-induced IBS mice, but not in the control mice, and is also associated with increased intestinal SCFA production.

Epidermal growth factor upregulates serotonin transporter and its association with visceral hypersensitivity in irritable bowel syndrome

AIM: To investigate the role of epidermal growth factor (EGF) in visceral hypersensitivity and its effect on the serotonin transporter (SERT).

P2Y1R is involved in visceral hypersensitivity in rats with experimental irritable bowel syndrome

AIM To evaluate the role of P2Y1 R in visceral hypersensitivity in rats with experimental irritable bowel syndrome.METHODS A rat model of irritable bowel syndrome was generated by intra-colonic administration of acetic acid(AA) and assessed by histology and myeloperoxidase(m PO) activity assay. Then P2Y1 R expression in the colonic tissue was detected by Western blot. In order to explore the regulatory role of P2Y1 R in visceral hypersensitivity, an agonist(m RS2365) and an antagonist(m RS2179) of P2Y1 R were intra-colonically administered and effects were tested through a colorectal distension test. The abdominal withdrawal reflex and abdominal electromyography were tested during the course. RESULTS model assessment tests showed an obvious inflammatoryreaction that appeared on the 2^(nd) d after the AA injection, and the inflammatory reaction gradually recovered and almost disappeared on the 7^(th) d. The model finished on day 8 and showed a clear feature of IBS that had no organic lesion. The average expression of P2Y1 R was significantly higher in the AA group than in the na?ve group(0.319 ± 0.02 vs 0.094 ± 0.016, P < 0.001). m RS2365 could effectively raise the colonic hypersensitivity status at intervention doses of 10(AUC value from 0.30 ± 0.089 to 1.973 ± 0.127 mv?s, P < 0.01) and 100 μmol/L(AUC value from 0.290 ± 0.079 to 1.983 ± 0.195 mv?s, P < 0.01); m RS2179 could effectively reduce the hypersensitivity status at intervention dose of 100 μmol/L(from a mean baseline AUC value of 1.587 ± 0.099 mv?s to 0.140 ± 0.089 mv?s, P < 0.0001). Differences between the m RS2179 group(1.88 ± 1.45) and either the m RS2365 group(3.96 ± 0.19) or the combined treatment(m RS2179 and m RS2365) group(3.28 ± 0.11) were significant(P < 0.01).CONCLUSION P2Y1 R plays a regulatory role in visceral hypersensitivity in rats with experimental IBS. Specific antagonists of P2Y1 R may have potential therapeutic value in treating abdominal pain in IBS.

Family history of irritable bowel syndrome is the major determinant of persistent abdominal complaints in young adults with a history of pediatric recurrent abdominal pain

AIM： To assess the late outcome of teen-agers with a previous history of recurrent abdominal pain （RAP） or irritable bowel syndrome （IBS）. METHODS： A group of 67 children with RAP referred to the department from January 1986 to December 1995 was followed up between 5 and 13 years after the initial diagnosis by means of a structured telephone interview. We hypothesized that those patients with persistent adult IBS-like symptoms would be significantly more likely to report a family history oflBS in comparison with adults with no persistent abdominal complaint. RESULTS： Out of the 52 trackable subjects, 15 were found to present IBS-like symptoms at follow-up （29%） whereas the majority （37 subjects） did not. Subjects with IBS-like symptoms were almost three times more likely to present at least one sibling with similar symptoms compared to subjects not complaining （40.0% vs 16.0%）, respectively （P 〈 0.05 at Student t test）. Subjects with IBS-like symptoms also reported a higher prevalence of extra-intestinal symptoms, such as back pain, fibromyalgia, headache, fatigue and sleep disturbances. CONCLUSION： The study confirms previous observations indicating that pediatric RAP can predict later development of IBS. The latter appears to be greatly influenced by intrafamilial aggregation of symptoms, possibly through the learning of a specific illness behavior.

YINDARA-4 relieves visceral hypersensitivity in irritable bowel syndrome rats via regulation of gut microbiota and serotonin levels

Objective:The present study aims to evaluate the in vivo efficacy of YINDARA-4 in improving the symptoms of irritable bowel syndrome(IBS)in a rat model and investigate the impact of YINDARA-4 on potential targets of IBS management,such as the serotonin level in intestinal tissues and the structure and composition of the gut microbiota.Methods:We developed an IBS rat model by combining stress from maternal separation,acetic acid administration,and restraint.We administered YINDARA-4 water extract to the IBS rat model for 10 consecutive days.The fecal water content,visceral sensitivity,gut microbiota,and serotonin levels in the colonic tissue were then analyzed and compared between the control group,IBS model group,and YINDARA-4–treated groups.Results:Treatment with YINDARA-4 reversed visceral hypersensitivity in a dose-dependent manner in the experimental rat model of IBS.The relief of visceral hypersensitivity upon treatment with YINDARA-4 involved regulation of the gut microbiota structure and composition,and normalization of elevated serotonin levels in the colon.The decrease in colonic serotonin levels with YINDARA-4 treatment might be associated with a reduction in the abundance of Helicobacter and enrichment of Butyricimonas.Conclusions:Treatment with YINDARA-4 was beneficial against visceral hypersensitivity in a rat model of IBS.The improved symptoms exhibited in IBS rats were associated with favorably altered gut microbiota and normalization of serotonin levels in the colon.

Are bowel symptoms and psychosocial features different in irritable bowel syndrome patients with abdominal discomfort compared to abdominal pain?

BACKGROUND The Rome IV criteria eliminated abdominal discomfort for irritable bowel syndrome(IBS), which was previously included in Rome III. There are questions as to whether IBS patients with abdominal discomfort(seen in Rome III but not Rome IV) are different from those with abdominal pain(Rome IV).AIM To compare bowel symptoms and psychosocial features in IBS patients diagnosed with Rome III criteria with abdominal discomfort, abdominal pain, and pain &discomfort.METHODS We studied IBS patients meeting Rome III criteria. We administered the IBS symptom questionnaire, psychological status, and IBS quality of life. Patients were classified according to the predominant abdominal symptom associated with defecation into an only pain group, only discomfort group, and pain & discomfort group. We compared bowel symptoms, extraintestinal symptoms, IBS quality of life, psychological status and healthcare-seeking behaviors, and efficacy among the three groups. Finally, we tested risk factors for symptom reporting in IBS patients.RESULTS Of the 367 Rome III IBS patients enrolled, 33.8%(124 cases) failed to meet Rome IV criteria for an IBS diagnosis. There were no meaningful differences between the pain group(n = 233) and the discomfort group(n = 83) for the following:(1) Frequency of defecatory abdominal pain or discomfort;(2) Bowel habits;(3) Coexisting extragastrointestinal pain;(4) Comorbid anxiety and depression;and(5) IBS quality of life scores except more patients in the discomfort group reported mild symptom than the pain group(22.9% vs 9.0%). There is a significant tendency for patients to report their defecatory and non-defecatory abdominal symptom as pain alone, or discomfort alone, or pain & discomfort(all P < 0.001).CONCLUSION IBS patients with abdominal discomfort have similar bowel symptoms and psychosocial features to those with abdominal pain. IBS symptoms manifesting abdominal pain or discomfort may primarily be due to different sensation and reporting experience.

Effect of mild moxibustion on intestinal microbiota and NLRP6 inflammasome signaling in rats with post-inflammatory irritable bowel syndrome

BACKGROUND About one-third of refractory irritable bowel syndrome(IBS)cases are caused by gastrointestinal(GI)infection/inflammation,known as post-infectious/postinflammatory IBS(PI-IBS).Although it is known that intestinal microbiota and host NOD-like receptor family pyrin domain containing 6(NLRP6)inflammsome signaling are closely related to PI-IBS and moxibustion has a therapeutic effect on PI-IBS,whether moxibustion regulates the intestinal flora and host NLRP6 events in PI-IBS remains unclear.AIM To examine the regulatory effect of moxibustion on intestinal microbiota and host NLRP6 inflammatory signaling in PI-IBS.METHODS Sprague-Dawley rats were divided into a normal control group,a model control group,a mild moxibustion group,and a sham mild moxibustion group.PI-IBS rats in the mild moxibustion group were treated with moxibusiton at bilateral Tianshu(ST 25)and Zusanli(ST36)for 7 consecutive days for 10 min each time.The sham group rats were given the same treatment as the mild moxibustion group except the moxa stick was not ignited.Abdominal withdrawal reflex(AWR)score was measured to assess the visceral sensitivity,and colon histopathology and ultrastructure,colonic myeloperoxidase(MPO)activity,and serum C-reactive protein(CRP)level were measured to evaluate low-grade colonic inflammation in rats.The relative abundance of selected intestinal bacteria in rat feces was detected by 16S rDNA PCR and the NLRP6 inflammsome signaling in the colon was detected by immunofluorescence,qRTPCR,and Western blot.RESULTS The AWR score was significantly decreased and the low-grade intestinal inflammation reflected by serum CRP and colonic MPO levels was inhibited in the mild moxibustion group compared with the sham group.Mild moxibustion remarkably increased the relative DNA abundances of Lactobacillus,Bifidobacterium,and Faecalibacterium prausnitzii but decreased that of Escherichia coli in the gut of PI-IBS rats.Additionally,mild moxibustion induced mRNA and protein expression of intestine lectin 1 but inhibited the expression of IL-1β,IL-18,and resistance-like moleculeβby promoting the NLRP6 and reducing the mRNA and protein expression of apoptosis-associated speck-like protein containing CARD(ASC)and cysteinyl-aspartate-specific proteinase 1(Caspase-1).The relative DNA abundances of Lactobacillus,Bifidobacteria,Faecalibacterium prausnitzii,and Escherichia coli in each group were correlated with the mRNA and protein expression of NLRP6,ASC,and Caspase-1 in the colon.CONCLUSION These findings indicated that mild moxibustion can relieve low-grade GI inflammation and alleviate visceral hypersensitivity in PI-IBS by regulating intestinal microbes and controlling NLRP6 inflammasome signaling.

Irritable bowel syndrome in children:Current knowledge, challenges and opportunities

Irritable bowel syndrome(IBS) is a common and troublesome disorder in children with an increasing prevalence noted during the past two decades. It has a significant effect on the lives of affected children and their families and poses a significant burden on healthcare systems. Standard symptom-based criteria for diagnosis of pediatric IBS have changed several times during the past two decades and there are some differences in interpreting symptoms between different cultures. This has posed a problem when using them to diagnose IBS in clinical practice. A number of potential patho-physiological mechanisms have been described, but so far the exact underlying etiology of IBS is unclear. A few potential therapeutic modalities have been tested in children and only a small number of them have shown some benefit. In addition, most of the described patho-physiological mechanisms and treatment options are based on adult studies. These have surfaced as challenges when dealing with pediatric IBS and they need to be overcome for effective management of children with IBS. Recently suggested top-down and bottom-up models help integrating reported patho-physiological mechanisms and will provide an opportunity for better understanding of the diseases process. Treatment trials targeting single treatment modalities are unlikely to have clinically meaningful therapeutic effects on IBS with multiple integrating patho-physiologies. Trials focusing on multiple combined pharmacological and non-pharmacological therapies are likely to yield more benefit. In addition to treatment, in the future, attention should be paid for possible prevention strategies for IBS.

Acupuncture-moxibustion in treating irritable bowel syndrome: How does it work?

Irritable bowel syndrome (IBS) is a functional intestinal disease characterized by abdominal pain or discomfort and altered bowel habits. It has drawn great attention because of its high prevalence, reoccurring symptoms, and severe influence on patients&#x02019; lives. Many clinical studies have demonstrated the efficacy of acupuncture-moxibustion in treating IBS. Increasing attention has been paid to research regarding the action mechanisms of acupuncture-moxibustion for IBS, and the adoption of modern techniques has achieved some progress. This article reviews the latest advances among action mechanism studies from the perspectives of gastrointestinal motility, visceral hypersensitivity, the brain-gut axis, the neuroendocrine system, and the immune system. It is shown that acupuncture-moxibustion can effectively regulate the above items, and thus, this treatment should have a high efficacy in the treatment of IBS. This article also identifies existing problems in current mechanism research and raises several ideas for future studies. Further revelations regarding these action mechanisms will promote the application of acupuncture-moxibustion in treating IBS.