Local immune response to food antigens drives meal-induced abdominal pain.

Up to 20% of people worldwide develop gastrointestinal symptoms following a meal1, leading to decreased quality of life, substantial morbidity and high medical costs. Although the interest of both the scientific and lay communities in this issue has increased markedly in recent years, with the worldwide introduction of gluten-free and other diets, the underlying mechanisms of food-induced abdominal complaints remain largely unknown. Here we show that a bacterial infection and bacterial toxins can trigger an immune response that leads to the production of dietary-antigen-specific IgE antibodies in mice, which are limited to the intestine. Following subsequent oral ingestion of the respective dietary antigen, an IgE- and mast-cell-dependent mechanism induced increased visceral pain. This aberrant pain signalling resulted from histamine receptor H1-mediated sensitization of visceral afferents. Moreover, injection of food antigens (gluten, wheat, soy and milk) into the rectosigmoid mucosa of patients with irritable bowel syndrome induced local oedema and mast cell activation. Our results identify and characterize a peripheral mechanism that underlies food-induced abdominal pain, thereby creating new possibilities for the treatment of irritable bowel syndrome and related abdominal pain disorders.

A Randomized Controlled Phase 2 Dose-Finding Trial to Evaluate the Efficacy and Safety of Camostat in the Treatment of Painful Chronic Pancreatitis: The TACTIC Study.

BACKGROUND & AIMS: Chronic pancreatitis (CP) causes an abdominal pain syndrome associated with poor quality of life. We conducted a clinical trial to further investigate the efficacy and safety of camostat, an oral serine protease inhibitor that has been used to alleviate pain in CP. METHODS: This was a double-blind randomized controlled trial that enrolled adults with CP with a baseline average daily worst pain score ≥4 on a numeric rating system. Participants were randomized (1:1:1:1) to receive camostat at 100, 200, or 300 mg 3 times daily or placebo. The primary end point was a 4-week change from baseline in the mean daily worst pain intensity score (0-10 on a numeric rating system) using a mixed model repeated measure analysis. Secondary end points included changes in alternate pain end points, quality of life, and safety. RESULTS: A total of 264 participants with CP were randomized. Changes in pain from baseline were similar between the camostat groups and placebo, with differences of least squares means of -0.11 (95% CI, -0.90 to 0.68), -0.04 (95% CI, -0.85 to 0.78), and -0.11 (95% CI, -0.94 to 0.73) for the 100 mg, 200 mg, and 300 mg groups, respectively. Multiple subgroup analyses were similar for the primary end point, and no differences were observed in any of the secondary end points. Treatment-emergent adverse events attributed to the study drug were identified in 42 participants (16.0%). CONCLUSION: We were not able to reject the null hypothesis of no difference in improvements in pain or quality of life outcomes in participants with painful CP who received camostat compared with placebo. Studies are needed to further define mechanisms of pain in CP to guide future clinical trials, including minimizing placebo responses and selecting targeted therapies. CLINICALTRIALS: gov, Number: NCT02693093.

Sex-Dependent Efficacy of Dietary Fiber in Pediatric Functional Abdominal Pain.

BACKGROUND & AIMS: Functional abdominal pain disorders (FAPDs) are more prevalent in female patients. Dietary fiber may alleviate FAPD symptoms; however, whether this effect is sex dependent remains unclear. We investigated the sex dependency of dietary fiber benefit on abdominal pain in children with FAPDs and explored the potential involvement of the gut microbiome. METHODS: In 2 cross-sectional cohorts of children with FAPDs (n = 209) and healthy control individuals (n = 105), we correlated dietary fiber intake with abdominal pain symptoms after stratifying by sex. We also performed sex-stratified and sex-interaction analyses on data from a double-blind trial in children with irritable bowel syndrome randomized to psyllium fiber (n = 39) or placebo (n = 49) for 6 weeks. Shotgun metagenomics was used to investigate gut microbiome community changes potentially linking dietary fiber intake with abdominal pain. RESULTS: In the cross-sectional cohorts, fiber intake inversely correlated with pain symptoms in boys (pain episodes: r = -0.24, P = .005; pain days: r = -0.24, P = 0.004) but not in girls. Similarly, in the randomized trial, psyllium fiber reduced the number of pain episodes in boys (P = .012) but not in girls. Generalized linear regression models confirmed that boys treated with psyllium fiber had greater reduction in pain episodes than girls (P = .007 for fiber × sex × time interaction). Age, sexual development, irritable bowel syndrome subtype, stool form, and microbiome composition were not significant determinants in the dietary fiber effects on pain reduction. CONCLUSIONS: Dietary fiber preferentially reduces abdominal pain frequency in boys, highlighting the importance of considering sex in future dietary intervention studies for FAPDs. (ClincialTrials.gov, Number NCT00526903).

Extracorporeal Shock-Wave Lithotripsy and Endoscopy for the Treatment of Pain in Chronic Pancreatitis : A Sham-Controlled, Randomized Trial.

BACKGROUND: No randomized controlled trials have substantiated endoscopic decompression of the pancreatic duct in patients with painful chronic pancreatitis. OBJECTIVE: To investigate the pain-relieving effect of pancreatic duct decompression in patients with chronic pancreatitis and intraductal stones. DESIGN: 24-week, parallel-group, randomized controlled trial (ClinicalTrials.gov: NCT03966781). SETTING: Asian Institute of Gastroenterology in India from February 2021 to July 2022. PARTICIPANTS: 106 patients with chronic pancreatitis. INTERVENTION: Combined extracorporeal shock-wave lithotripsy (ESWL) and endoscopic retrograde pancreatography (ERP) compared with sham procedures. MEASUREMENTS: The primary end point was pain relief on a 0- to 10-point visual analog scale (VAS) at 12 weeks. Secondary outcomes were assessed after 12 and 24 weeks and included 30% pain relief, opioid use, pain-free days, questionaries, and complications to interventions. RESULTS: 52 patients in the ESWL/ERP group and 54 in the sham group were included. At 12 weeks, the ESWL/ERP group showed better pain relief compared with the sham group (mean difference in change, -0.7 [95% CI, -1.3 to 0] on the VAS; P = 0.039). The difference between groups was not sustained at the 24-week follow-up, and no differences were seen for 30% pain relief at 12- or 24-week follow-up. The number of pain-free days was increased (median difference, 16.2 days [CI, 3.9 to 28.5 days]), and the number of days using opioids was reduced (median difference, -5.4 days [CI, -9.9 to -0.9 days]) in the ESWL/ERP group compared with the sham group at 12-week follow-up. Safety outcomes were similar between groups. LIMITATION: Single-center study and limited duration of follow-up. CONCLUSION: In patients with chronic pancreatitis and intraductal stones, ESWL with ERP provided modest short-term pain relief. PRIMARY FUNDING SOURCE: Asian Institute of Gastroenterology and Aalborg University Hospital.

Acute Colonic Diverticulitis.

Acute colonic diverticulitis is a gastrointestinal condition that is frequently encountered by primary care and emergency department practitioners, hospitalists, surgeons, and gastroenterologists. Clinical presentation ranges from mild abdominal pain to peritonitis with sepsis. It is often diagnosed on the basis of clinical features alone, but imaging is necessary in more severe presentations to rule out such complications as abscess and perforation. Treatment depends on the severity of the presentation, the presence of complications, and underlying comorbid conditions. Medical and surgical treatment algorithms are evolving. This article provides an evidence-based, clinically relevant overview of the epidemiology, diagnosis, and treatment of acute diverticulitis.

Postprandial symptoms in disorders of gut-brain interaction and their potential as a treatment target.

Postprandial, or meal-related, symptoms, such as abdominal pain, early satiation, fullness or bloating, are often reported by patients with disorders of gut-brain interaction, including functional dyspepsia (FD) or irritable bowel syndrome (IBS). We propose that postprandial symptoms arise via a distinct pathophysiological process. A physiological or psychological insult, for example, acute enteric infection, leads to loss of tolerance to a previously tolerated oral food antigen. This enables interaction of both the microbiota and the food antigen itself with the immune system, causing a localised immunological response, with activation of eosinophils and mast cells, and release of inflammatory mediators, including histamine and cytokines. These have more widespread systemic effects, including triggering nociceptive nerves and altering mood. Dietary interventions, including a diet low in fermentable oligosaccharides, disaccharides, monosaccharides and polyols, elimination of potential food antigens or gluten, IgG food sensitivity diets or salicylate restriction may benefit some patients with IBS or FD. This could be because the restriction of these foods or dietary components modulates this pathophysiological process. Similarly, drugs including proton pump inhibitors, histamine-receptor antagonists, mast cell stabilisers or even tricyclic or tetracyclic antidepressants, which have anti-histaminergic actions, all of which are potential treatments for FD and IBS, act on one or more of these mechanisms. It seems unlikely that food antigens driving intestinal immune activation are the entire explanation for postprandial symptoms in FD and IBS. In others, fermentation of intestinal carbohydrates, with gas release altering reflex responses, adverse reactions to food chemicals, central mechanisms or nocebo effects may dominate. However, if the concept that postprandial symptoms arise from food antigens driving an immune response in the gastrointestinal tract in a subset of patients is correct, it is paradigm-shifting, because if the choice of treatment were based on one or more of these therapeutic targets, patient outcomes may be improved.

Treatment of non-constipated irritable bowel syndrome with the histamine 1 receptor antagonist ebastine: a randomised, double-blind, placebo-controlled trial.

OBJECTIVE: We evaluated the histamine 1 receptor antagonist ebastine as a potential treatment for patients with non-constipated irritable bowel syndrome (IBS) in a randomised, placebo-controlled phase 2 study. METHODS: Non-constipated patients with IBS fulfilling the Rome III criteria were randomly assigned to 20 mg ebastine or placebo for 12 weeks. Subjects scored global relief of symptoms (GRS) and abdominal pain intensity (API). A subject was considered a weekly responder for GRS if total or obvious relief was reported and a responder for API if the weekly average pain score was reduced by at least 30% vs baseline. The primary endpoints were the proportion of subjects who were weekly responders for at least 6 out of the 12 treatment weeks for both GRS and API ('GRS+API', composite endpoint) and for GRS and API separately. RESULTS: 202 participants (32±11 years, 68% female) were randomly allocated to receive ebastine (n=101) or placebo (n=101). Treatment with ebastine resulted in significantly more responders (12%, 12/92) for GRS+API compared with placebo (4%, 4/87, p=0.047) while the proportion of responders for GRS and API separately was higher for ebastine compared with placebo, although not statistically significant (placebo vs ebastine, GRS: 7% (6/87) vs 15% (14/91), p=0.072; API: 25% (20/85) vs 37% (34/92), p=0.081). CONCLUSIONS: Our study shows that ebastine is superior to placebo and should be further evaluated as novel treatment for patients with non-constipated IBS. TRIAL REGISTRATION NUMBER: The study protocol was approved by the local ethics committee of each study site (EudraCT number: 2013-001199-39; ClinicalTrials.gov identifier: NCT01908465).

Celiac plexus radiosurgery for pain management in advanced cancer: a multicentre, single-arm, phase 2 trial.

BACKGROUND: Refractory upper abdominal pain or lower back pain (retroperitoneal pain syndrome) related to celiac plexus involvement characterises pancreatic and other upper gastrointestinal malignancies and is an unmet need. We hypothesised that ablative radiation delivered to the celiac plexus would decrease pain. METHODS: This multicentre, single-arm, phase 2 study was done at eight hospitals in five countries (Israel, Poland, Canada, the USA, and Portugal). Eligible patients aged 18 years or older with an average pain level of 5-10 on the Brief Pain Inventory short form (BPI-SF), an Eastern Cooperative Oncology Group performance status score of 0-2, and either pancreatic cancer or other tumours involving the celiac axis, received a single fraction of 25 Gy of external-beam photons to the celiac plexus. The primary endpoint was complete or partial pain response based on a reduction of the BPI-SF average pain score of 2 points or more from baseline to 3 weeks after treatment. All evaluable patients with stable pain scores were included in response assessment. The trial is registered with ClinicalTrials.gov, NCT03323489, and is complete. FINDINGS: Between Jan 3, 2018, and Dec 28, 2021, 125 patients were treated, 90 of whom were evaluable. Patients were followed up until death. Median age was 65·5 years (IQR 58·3-71·8), 50 (56%) were female and 40 (44%) were male, 83 (92%) had pancreatic cancer, and 77 (86%) had metastatic disease. Median baseline BPI-SF average pain score was 6 (IQR 5-7). Of the 90 evaluable patients at 3 weeks, 48 (53%; 95% CI 42-64) had at least a partial pain response. The most common grade 3-4 adverse events, irrespective of attribution, were abdominal pain (35 [28%] of 125) and fatigue (23 [18%]). 11 serious adverse events of grade 3 or worse were recorded. Two grade 3 serious adverse events were probably attributed to treatment by the local investigators (abdominal pain [n=1] and nausea [n=1]), and nine were possibly attributed to treatment (seven were grade 3: blood bilirubin increased [n=1], duodenal haemorrhage [n=2], abdominal pain [n=2], and progressive disease [n=2]; and two were grade 5: gastrointestinal bleed from suspected varices 24 days after treatment [n=1] and progressive disease [advanced pancreatic cancer] 89 days after treatment [n=1]). INTERPRETATION: Celiac plexus radiosurgery could potentially be a non-invasive palliative option for patients with retroperitoneal pain syndrome. Further investigation by means of a randomised comparison with conventional celiac block or neurolysis is warranted. FUNDING: Gateway for Cancer Research and the Israel Cancer Association.

Predictive value of abnormal blood tests for detecting cancer in primary care patients with nonspecific abdominal symptoms: A population-based cohort study of 477,870 patients in England.

BACKGROUND: Identifying patients presenting with nonspecific abdominal symptoms who have underlying cancer is a challenge. Common blood tests are widely used to investigate these symptoms in primary care, but their predictive value for detecting cancer in this context is unknown. We quantify the predictive value of 19 abnormal blood test results for detecting underlying cancer in patients presenting with 2 nonspecific abdominal symptoms. METHODS AND FINDINGS: Using data from the UK Clinical Practice Research Datalink (CPRD) linked to the National Cancer Registry, Hospital Episode Statistics and Index of Multiple Deprivation, we conducted a population-based cohort study of patients aged ≥30 presenting to English general practice with abdominal pain or bloating between January 2007 and October 2016. Positive and negative predictive values (PPV and NPV), sensitivity, and specificity for cancer diagnosis (overall and by cancer site) were calculated for 19 abnormal blood test results co-occurring in primary care within 3 months of abdominal pain or bloating presentations. A total of 9,427/425,549 (2.2%) patients with abdominal pain and 1,148/52,321 (2.2%) with abdominal bloating were diagnosed with cancer within 12 months post-presentation. For both symptoms, in both males and females aged ≥60, the PPV for cancer exceeded the 3% risk threshold used by the UK National Institute for Health and Care Excellence for recommending urgent specialist cancer referral. Concurrent blood tests were performed in two thirds of all patients (64% with abdominal pain and 70% with bloating). In patients aged 30 to 59, several blood abnormalities updated a patient's cancer risk to above the 3% threshold: For example, in females aged 50 to 59 with abdominal bloating, pre-blood test cancer risk of 1.6% increased to: 10% with raised ferritin, 9% with low albumin, 8% with raised platelets, 6% with raised inflammatory markers, and 4% with anaemia. Compared to risk assessment solely based on presenting symptom, age and sex, for every 1,000 patients with abdominal bloating, assessment incorporating information from blood test results would result in 63 additional urgent suspected cancer referrals and would identify 3 extra cancer patients through this route (a 16% relative increase in cancer diagnosis yield). Study limitations include reliance on completeness of coding of symptoms in primary care records and possible variation in PPVs if extrapolated to healthcare settings with higher or lower rates of blood test use. CONCLUSIONS: In patients consulting with nonspecific abdominal symptoms, the assessment of cancer risk based on symptoms, age and sex alone can be substantially enhanced by considering additional information from common blood test results. Male and female patients aged ≥60 presenting to primary care with abdominal pain or bloating warrant consideration for urgent cancer referral or investigation. Further cancer assessment should also be considered in patients aged 30 to 59 with concurrent blood test abnormalities. This approach can detect additional patients with underlying cancer through expedited referral routes and can guide decisions on specialist referrals and investigation strategies for different cancer sites.

Expression and function of transient receptor potential melastatin 3 in the spinal afferent innervation of the mouse colon.

Abdominal pain is a cardinal symptom of inflammatory bowel disease (IBD). Transient receptor potential (TRP) channels contribute to abdominal pain in preclinical models of IBD, and TRP melastatin 3 (TRPM3) has recently been implicated in inflammatory bladder and joint pain in rodents. We hypothesized that TRPM3 is involved in colonic sensation and is sensitized during colitis. We used immunohistochemistry, ratiometric Ca2+ imaging, and colonic afferent nerve recordings in mice to evaluate TRPM3 protein expression in colon-projecting dorsal root ganglion (DRG) neurons, as well as functional activity in DRG neurons and colonic afferent nerves. Colitis was induced using dextran sulfate sodium (DSS) in drinking water. TRPM3 protein expression was observed in 76% of colon-projecting DRG neurons and was often colocalized with calcitonin gene-related peptide. The magnitudes of intracellular Ca2+ transients in DRG neurons in response to the TRPM3 agonists CIM-0216 and pregnenolone sulfate sodium were significantly greater in neurons from mice with colitis compared with controls. In addition, the percentage of DRG neurons from mice with colitis that responded to CIM-0216 was significantly increased. CIM-0216 also increased the firing rate of colonic afferent nerves from control and mice with colitis. The TRPM3 inhibitor isosakuranetin inhibited the mechanosensitive response to distension of wide dynamic range afferent nerve units from mice with colitis but had no effect in control mice. Thus, TRPM3 contributes to colonic sensory transduction and may be a potential target for treating pain in IBD.NEW & NOTEWORTHY This is the first study to characterize TRPM3 protein expression and function in colon-projecting DRG neurons. A TRPM3 agonist excited DRG neurons and colonic afferent nerves from healthy mice. TRPM3 agonist responses in DRG neurons were elevated during colitis. Inhibiting TRPM3 reduced the firing of wide dynamic range afferent nerves from mice with colitis but had no effect in control mice.

NHE3 inhibitor tenapanor maintains intestinal barrier function, decreases visceral hypersensitivity, and attenuates TRPV1 signaling in colonic sensory neurons.

The pathogenesis of irritable bowel syndrome (IBS) is multifactorial, characterized in part by increased intestinal permeability, and visceral hypersensitivity. Increased permeability is associated with IBS severity and abdominal pain. Tenapanor is FDA-approved for the treatment of IBS with constipation (IBS-C) and has demonstrated improvements in bowel motility and a reduction in IBS-related pain; however, the mechanism by which tenapanor mediates these functions remains unclear. Here, the effects of tenapanor on colonic pain signaling and intestinal permeability were assessed through behavioral, electrophysiological, and cell culture experiments. Intestinal motility studies in rats and humans demonstrated that tenapanor increased luminal sodium and water retention and gastrointestinal transit versus placebo. A significantly reduced visceral motor reflex (VMR) to colonic distension was observed with tenapanor treatment versus vehicle in two rat models of visceral hypersensitivity (neonatal acetic acid sensitization and partial restraint stress; both P < 0.05), returning VMR responses to that of nonsensitized controls. Whole cell voltage patch-clamp recordings of retrogradely labeled colonic dorsal root ganglia (DRG) neurons from sensitized rats found that tenapanor significantly reduced DRG neuron hyperexcitability to capsaicin versus vehicle (P < 0.05), an effect not mediated by epithelial cell secretions. Tenapanor also attenuated increases in intestinal permeability in human colon monolayer cultures caused by incubation with proinflammatory cytokines (P < 0.001) or fecal supernatants from patients with IBS-C (P < 0.005). These results support a model in which tenapanor reduces IBS-related pain by strengthening the intestinal barrier, thereby decreasing permeability to macromolecules and antigens and reducing DRG-mediated pain signaling.NEW & NOTEWORTHY A series of nonclinical experiments support the theory that tenapanor inhibits IBS-C-related pain by strengthening the intestinal barrier. Tenapanor treatment reduced visceral motor responses to nonsensitized levels in two rat models of hypersensitivity and reduced responses to capsaicin in sensitized colonic nociceptive dorsal root ganglia neurons. Intestinal permeability experiments in human colon monolayer cultures found that tenapanor attenuates increases in permeability induced by either inflammatory cytokines or fecal supernatants from patients with IBS-C.

Distinct Serum Immune Profiles Define the Spectrum of Acute and Chronic Pancreatitis From the Multicenter Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) Study.

BACKGROUND & AIMS: Pancreatitis is a disease continuum, starting with acute pancreatitis (AP) and progressing in some cases to recurrent acute pancreatitis (RAP) and chronic pancreatitis (CP). Currently, there are no approved therapies or early diagnostic or prognostic biomarkers for pancreatitis. The current study examined whether patient serum immune profiling could identify noninvasive biomarkers and provide mechanistic insight into the disease continuum of pancreatitis. METHODS: Using Olink immunoassay, we assessed the protein levels of 92 immune markers in serum samples from participants enrolled in the Prospective Evaluation of Chronic Pancreatitis for Epidemiologic and Translational Studies (PROCEED) study of the Chronic Pancreatitis, Diabetes, and Pancreatic Cancer (CPDPC) consortium. Samples (N = 231) were obtained from individuals without pancreatic disease (n = 56) and from those with chronic abdominal pain (CAP) (n = 24), AP (n = 38), RAP (n = 56), and CP (n = 57). RESULTS: A total of 33 immune markers differentiated the combined pancreatitis groups from controls. Immune markers related to interleukin (IL) 17 signaling distinguished CP from AP and RAP. Similarly, the serum level of IL17A and C-C motif chemokine ligand 20 differentiated CP from CAP, suggesting the involvement of T helper 17 cells in CP pathogenesis. The receiver operator characteristic curve with 2 immune markers (IL17A and sulfotransferase 1A1) could differentiate CP from CAP (optimistic area under the curve = 0.78). The macrophage classical activation pathway elevated along the continuum of pancreatitis, suggesting an accumulation of proinflammatory signals over disease progression. Several immune markers were associated with smoking, alcohol, and diabetes status. CONCLUSIONS: Immune profiling of serum samples from a large pancreatitis cohort led to identifying distinct immune markers that could serve as potential biomarkers to differentiate the varying pancreatitis disease states. In addition, the finding of IL17 signaling in CP could provide insight into the immune mechanisms underlying disease progression.

Prevalence and Associated Factors of Bloating: Results From the Rome Foundation Global Epidemiology Study.

BACKGROUND & AIMS: Bloating is a common symptom in the general population and among disorders of gut-brain interaction, although its prevalence has not been well characterized. The aim of this study was to report the prevalence of bloating as a symptom in the worldwide population and to identify factors associated with this symptom in the general population. METHODS: Rome Foundation Global Epidemiology Study internet survey data were analyzed. After excluding respondents with potential organic causes of bowel symptoms, the current analysis included 51,425 individuals in 26 countries. Data included diet, medical history, quality of life, and Rome IV diagnostic questions. Presence of bloating was defined as experiencing bloating at least once per week for the last 3 months. Descriptive statistics estimated prevalence by country, region, and disorder of gut-brain interaction diagnosis. Logistic regression evaluated predictors of bloating. RESULTS: Nearly 18% of the global study population reported bloating (ranging from 11% in East Asia to 20% in Latin America). Prevalence decreased with age and women were approximately twice as likely as men to report bloating. More than one-half of respondents who reported weekly epigastric pain (71.39%), nausea (59.7%), or abdominal pain (61.69%) also reported bloating at least once per week. In logistic regression, the strongest associations were with abdominal pain (odds ratio, 2.90) and epigastric pain (odds ratio, 2.07). CONCLUSIONS: Bloating is common throughout the world. Nearly 18% of the general population experience bloating at least once per week. Reported bloating prevalence is lower in older age groups, most common in women, and strongly associated with abdominal pain.

Catechol-O-Methyltransferase Loss Drives Cell-Specific Nociceptive Signaling via the Enteric Catechol-O-Methyltransferase/microRNA-155/Tumor Necrosis Factor α Axis.

BACKGROUND & AIMS: The etiology of abdominal pain in postinfectious, diarrhea-predominant irritable bowel syndrome (PI-IBS-D) is unknown, and few treatment options exist. Catechol-O-methyltransferase (COMT), an enzyme that inactivates and degrades biologically active catecholamines, plays an important role in numerous physiologic processes, including modulation of pain perception. Our objective was to determine the mechanism(s) of how decreased colonic COMT in PI-IBS-D patients contributes to the chronic abdominal pain phenotype after enteric infections. METHODS: Colon neurons, epithelial cells, and macrophages were procured with laser capture microdissection from PI-IBS-D patients to evaluate cell-specific colonic COMT, microRNA-155 (miR-155), and tumor necrosis factor (TNF) α expression levels compared to recovered patients (infection cleared: did not develop PI-IBS-D) and control individuals. COMT-/-, colon-specific COMT-/-, and miR-155-/- mice and human colonoids were used to model phenotypic expression of COMT in PI-IBS-D patients and to investigate signaling pathways linking abdominal pain. Citrobacter rodentium and trinitrobenzene sulfonic acid animal models were used to model postinflammatory changes seen in PI-IBS-D patients. RESULTS: Colonic COMT levels were significantly decreased and correlated with increased visual analog scale abdominal pain ratings in PI-IBS-D patients compared to recovered patients and control individuals. Colonic miR-155 and TNF-α were increased in PI-IBS-D patients with diminished colonic COMT. COMT-/- mice had significantly increased expression of miR-155 and TNF-α in both colon tissues and dorsal root ganglia. Introduction of cV1q antibody (anti-TNF-α) into mice reversed visceral hypersensitivity after C rodentium and trinitrobenzene sulfonic acid. CONCLUSIONS: Decreased colonic COMT in PI-IBS-D patients drives abdominal pain phenotypes via the COMT/miR-155/TNF-α axis. These important findings will allow new treatment paradigms and more targeted and personalized medicine approaches for gastrointestinal disorders after enteric infections.

AGA Clinical Practice Update on Diagnosis and Management of Acute Hepatic Porphyrias: Expert Review.

DESCRIPTION: The acute hepatic porphyrias (AHP) are rare, inborn errors of heme-metabolism and include acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and porphyria due to severe deficiency of 5-aminolevulinic acid dehydratase. Acute intermittent porphyria is the most common type of AHP, with an estimated prevalence of patients with symptoms of approximately 1 in 100,000. The major clinical presentation involves attacks of severe pain, usually abdominal and generalized, without peritoneal signs or abnormalities on cross-sectional imaging. Acute attacks occur mainly in women in their childbearing years. AHP should be considered in the evaluation of all patients, and especially women aged 15-50 years with recurrent severe abdominal pain not ascribable to common causes. The screening tests of choice include random urine porphobilinogen and δ-aminolevulinic acid corrected to creatinine. All patients with elevations in urinary porphobilinogen and/or δ-aminolevulinic acid should initially be presumed to have AHP. The cornerstones of management include discontinuation of porphyrinogenic drugs and chemicals, administration of oral or intravenous dextrose and intravenous hemin, and use of analgesics and antiemetics. Diagnosis of AHP type can be confirmed after initial treatment by genetic testing for pathogenic variants in HMBS, CPOX, PPOX, and ALAD genes. AHP is also associated with chronic symptoms and long-term risk of systemic arterial hypertension, chronic renal and liver disease, and hepatocellular carcinoma. Patients who have recurrent acute attacks (4 or more per year) should be considered for prophylactic therapy with intravenous hemin or subcutaneous givosiran. Liver transplantation is curative and reserved for patients with intractable symptoms who have failed other treatment options. METHODS: This expert review was commissioned and approved by the American Gastroenterological Association (AGA) Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. These Best Practice Advice (BPA) statements were drawn from a review of the published literature and from expert opinion. Because systematic reviews were not performed, these BPA statements do not carry formal ratings of the quality of evidence or strength of the presented considerations. Best Practice Advice Statements BEST PRACTICE ADVICE 1: Women aged 15-50 years with unexplained, recurrent severe abdominal pain without a clear etiology after an initial workup should be considered for screening for an AHP. BEST PRACTICE ADVICE 2: Initial diagnosis of AHP should be made by biochemical testing measuring δ-aminolevulinic acid, porphobilinogen, and creatinine on a random urine sample. BEST PRACTICE ADVICE 3: Genetic testing should be used to confirm the diagnosis of AHP in patients with positive biochemical testing. BEST PRACTICE ADVICE 4: Acute attacks of AHP that are severe enough to require hospital admission should be treated with intravenous hemin, given daily, preferably into a high-flow central vein. BEST PRACTICE ADVICE 5: In addition to intravenous hemin, management of acute attacks of AHP should include pain control, antiemetics, management of systemic arterial hypertension, tachycardia, and hyponatremia, and hypomagnesemia, if present. BEST PRACTICE ADVICE 6: Patients should be counseled to avoid identifiable triggers that may precipitate acute attacks, such as alcohol and porphyrinogenic medications. BEST PRACTICE ADVICE 7: Prophylactic heme therapy or givosiran, administered in an outpatient setting, should be considered in patients with recurrent attacks (4 or more per year). BEST PRACTICE ADVICE 8: Liver transplantation for AHP should be limited to patients with intractable symptoms and significantly decreased quality of life who are refractory to pharmacotherapy. BEST PRACTICE ADVICE 9: Patients with AHP should be monitored annually for liver disease. BEST PRACTICE ADVICE 10: Patients with AHP, regardless of the severity of symptoms, should undergo surveillance for hepatocellular carcinoma, beginning at age 50 years, with liver ultrasound every 6 months. BEST PRACTICE ADVICE 11: Patients with AHP on treatment should undergo surveillance for chronic kidney disease annually with serum creatinine and estimated glomerular filtration rate. BEST PRACTICE ADVICE 12: Patients should be counseled on the chronic and long-term complications of AHP, including neuropathy, chronic kidney disease, hypertension, and hepatocellular carcinoma, and need for long-term monitoring.

Systematic Review and Meta-analysis: Efficacy of Mesalamine in Irritable Bowel Syndrome.

BACKGROUND & AIMS: Some patients with irritable bowel syndrome (IBS) demonstrate low-grade inflammation in the intestine. Mesalamine, which has anti-inflammatory effects, may be an efficacious treatment for IBS, but studies are conflicting. We conducted a systematic review and meta-analysis to assess efficacy and safety of mesalamine in IBS. METHODS: We searched the medical literature up to September 14, 2022, to identify randomized controlled trials (RCTs) of mesalamine in IBS. We judged efficacy and safety using dichotomous assessments of effect on global IBS symptoms, abdominal pain, bowel habit or stool frequency, and occurrence of any adverse event. We pooled data using a random effects model, with efficacy and safety reported as pooled relative risks (RRs) with 95% confidence intervals (CIs). RESULTS: We identified 8 eligible RCTs (820 patients). Mesalamine was more efficacious than placebo for global IBS symptoms (RR of global symptoms not improving, 0.86; 95% CI, 0.79-0.95; number needed to treat = 10; 95% CI, 6-27), but not for abdominal pain or bowel habit or stool frequency. Subgroup analyses demonstrated efficacy of mesalamine in IBS with diarrhea for global IBS symptoms (RR, 0.88; 95% CI, 0.79-0.99), but not patients with other predominant bowel habits or those with post-infection IBS. Adverse event rates were no higher with mesalamine (RR, 1.20; 95% CI, 0.89-1.63) but were reported in only 5 trials. CONCLUSIONS: Mesalamine may be modestly efficacious for global symptoms in IBS, particularly IBS with diarrhea, but quality of evidence was low. Adequately powered high quality RCTs of mesalamine in IBS are needed.

Quality of Life and Bidirectional Gut-Brain Interactions in Irritable Bowel Syndrome From Adolescence to Adulthood.

BACKGROUNDS AND AIMS: Reports on cross-sectional and longitudinal associations between health-related quality of life (HRQoL), psychological distress, and irritable bowel syndrome (IBS) in the adolescent and young adult general population are few. We aimed to describe cross-sectional associations between HRQoL and IBS in adolescence and young adulthood, and examine bidirectional gut-brain interactions in the transition from childhood to adulthood. METHODS: We included 3391 subjects from a prospective birth cohort study, with data on IBS at 16 years of age and 24 years of age. IBS was assessed using the pediatric Rome III (16 years of age) and the adult Rome IV (24 years of age) diagnostic questionnaires. HRQoL and psychological distress were assessed through EQ-5D. Sex-adjusted logistic regression models were used to examine associations between overall HRQoL/psychological distress at 16 years of age and new-onset IBS at 24 years of age (brain-gut) and between IBS at 16 years of age and new-onset psychological distress at 24 years of age (gut-brain). RESULTS: In subjects with vs without IBS at 16 and 24 years of age, overall HRQoL (EQ visual analog scale, EQ-5D index value) was lower, and it was more common reporting problems in 4 of 5 EQ-5D dimensions (all P < .05). EQ-5D index value at 16 years of age was inversely associated (odds ratio [OR], 0.1, 95% confidence interval [CI], 0.01-0.6), and psychological distress at 16 years of age was positively associated (OR, 1.6; 95% CI, 1.2-2.3), with new-onset IBS at 24 years of age. Having any abdominal pain-related disorder of gut-brain interaction at 16 years of age was associated with new-onset psychological distress at 24 years of age (OR, 1.7; 95% CI, 1.2-2.5). CONCLUSIONS: Adolescents and young adults with IBS in the general population have impaired HRQoL. Bidirectional gut-brain interactions are relevant for symptom generation in abdominal pain-related disorders of gut-brain interaction, and for HRQoL impairment and psychological distress in the transition from childhood to adulthood.

Virtual Reality Improves Symptoms of Functional Dyspepsia: Results of a Randomized, Double-Blind, Sham-Controlled, Pilot Study.

INTRODUCTION: We investigated the efficacy and safety of virtual reality (VR) for functional dyspepsia. METHODS: Patients were randomized 2:1 between active vs sham VR. Symptoms were assessed using the Patient Assessment of Gastrointestinal Disorders-Symptom Severity Index (PAGI-SYM) over 2-week. RESULTS: Patients in the active VR group had greater numerical improvement in PAGI-SYM scores (mean difference -0.7; P < 0.001) compared with sham VR (mean difference -0.4; P = 0.032). Active VR led to significant improvements for all PAGI-SYM subscales, except lower abdominal pain, whereas sham only improved heartburn/regurgitation and nausea/vomiting. Half of the total patients reported nonserious adverse effects, although only 1 patient withdrew from the study because of adverse effects. DISCUSSION: VR is safe and results in significant symptom improvement in functional dyspepsia. Larger trials are warranted.

Abdominal Symptom Improvement During Clinical Trials of Tenapanor in Patients With Irritable Bowel Syndrome With Constipation: A Post Hoc Analysis.

INTRODUCTION: This post hoc analysis evaluated the efficacy of tenapanor on abdominal symptoms in patients with irritable bowel syndrome with constipation. Abdominal symptoms assessed included pain, discomfort, bloating, cramping, and fullness. METHODS: The abdominal symptom data were pooled from 3 randomized controlled trials (NCT01923428, T3MPO-1 [NCT02621892], and T3MPO-2 [NCT02686138]). Weekly scores were calculated for each abdominal symptom, and the Abdominal Score (AS) was derived as the average of weekly scores for abdominal pain, discomfort, and bloating. The overall change from baseline during the 12 weeks was assessed for each symptom weekly score and the AS. The AS 6/12-week and 9/12-week response rates (AS improvement of ≥2 points for ≥6/12- or ≥9/12-week) were also evaluated. The association of weekly AS response status (reduction of ≥30%) with weekly complete spontaneous bowel movement (CSBM) status (=0 and >0) was assessed. RESULTS: Among 1,372 patients (684 tenapanor [50 mg twice a day] and 688 placebo), the least squares mean change from baseline in AS was -2.66 for tenapanor vs -2.09 for placebo ( P < 0.0001). The 6/12-week AS response rate was 44.4% for tenapanor vs 32.4% for placebo ( P < 0.0001), and for 9/12-week AS, 30.6% for tenapanor vs 20.5% for placebo ( P < 0.0001). A significant association between weekly CSBM status and weekly AS response status was observed each week ( P < 0.0001), with a greater proportion achieving an AS reduction in patients with >0 CSBMs in a week. DISCUSSION: Tenapanor significantly reduced abdominal symptoms in patients with irritable bowel syndrome with constipation, particularly pain, discomfort, and bloating measured by AS, compared with placebo.

Episodic Abdominal Pain-An Unexpected Cause for a Common Clinical Problem.

A previously healthy 55-year-old male patient presented repeatedly to the emergency department with severe episodic periumbilical abdominal pain. After an extensive diagnostic work-up and subsequent clinical deterioration, appendiceal diverticulitis was diagnosed. We identified a correlation of white blood cell counts and possibly faecal calprotectin with the clinical presentation. We suggest that appendiceal diverticulitis should be considered in middle-aged patients with recurrent episodes of abdominal pain that correlate with laboratory markers of inflammation.