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.

Joint Hypermobility, Autonomic Dysfunction, Gastrointestinal Dysfunction and Autoimmune markers (JAG-A): Clinical Associations and Response to Intravenous Immunoglobulin Therapy.

INTRODUCTION: We examined autoimmunity markers (AIM) and autonomic dysfunction in patients with chronic neurogastroenterological symptoms and their relationship to joint hypermobility/hypermobility spectrum disorder (JH/HSD). METHODS: AIM positivity was defined as a diagnosis of known autoimmune/autoinflammatory disorder (AIDX) with at least one positive seromarker of autoimmunity or at least two positive seromarkers by themselves. Three cohorts were studied: (a) Retrospective (n = 300); (b) Prospective validation cohort (n =133); and (c) Treatment cohort (n=40), administered open-label intravenous immunoglobulin (IVIG). RESULTS: AIM positivity was found in 40% and 29% of the retrospective and prospective cohorts, the majority of whom (71% and 69%, respectively) had AIDX. Significantly more patients with AIM had elevations of C-reactive protein (31% versus 15%, p<0.001) along with an increased proportion of cardiovascular autonomic dysfunction (48% versus 29%; p<.001), small fiber neuropathy (20% versus 9%; p=.002).8) and HLADQ8 positivity (24% versus 13%, p=.01). JH/HSD patients were more likely to have AIM (43% versus 15%, p=.001) along with more severe autonomic and gastrointestinal symptom scores. IVIG treatment was associated with robust improvement in pain, gastrointestinal and autonomic symptoms but adverse events were experienced by 62% patients. CONCLUSIONS: Autoimmune markers and autonomic dysfunction are common in patients with unexplained gastrointestinal symptoms, especially in those with JH/HSD. Many patients seem to respond to IVIG treatment but this needs to be confirmed by controlled trials. These results highlight the need for vigilance for autoimmune and autonomic factors and JH/HSD in patients with neurogastroenterological disorders. Clinicaltrials.gov, NCT04859829.

Low Vitamin D Levels in Patients with Symptoms of Gastroparesis: Relationships with Nausea and Vomiting, Gastric Emptying and Gastric Myoelectrical Activity.

Patients with gastroparesis (Gp) often have diets deficient in calories, electrolytes, and vitamins. Vitamin D levels have been reported to be low in some patients with Gp but has not been systematically studied. AIMS: To determine vitamin D levels and relationships among symptoms, gastric emptying and gastric myoelectrical activity (GMA) in patients with symptoms of Gp. METHODS: 25-hydroxy-vitamin D was measured in patients at enrollment in the Gastroparesis Clinical Consortium Registry. Gastroparesis Cardinal Symptoms Index (GCSI), gastric emptying, and GMA before and after water load satiety test (WLST) were measured. GMA, expressed as percentage distribution of activity in normal and dysrhythmic ranges, was recorded using electrogastrography. RESULTS: Overall, vitamin D levels were low (< 30 ng/ml) in 288 of 513 (56.1%) patients with symptoms of Gp (206 of 376 (54.8%) patients with delayed gastric emptying (Gp) and 82 of 137 (59.9%) patients with symptoms of Gp and normal gastric emptying). Low vitamin D levels were associated with increased nausea and vomiting (P < 0.0001), but not with fullness or bloating subscores. Low vitamin D levels in patients with Gp were associated with greater meal retention at four hours (36% retention) compared with Gp patients with normal vitamin D levels (31% retention; P = 0.05). Low vitamin D in patients with normal gastric emptying was associated with decreased normal 3 cpm GMA before (P = 0.001) and increased tachygastria after WLST (P = 0.01). CONCLUSIONS: Low vitamin D levels are present in half the patients with symptoms of gastroparesis and are associated with nausea and vomiting and gastric neuromuscular dysfunction.

Relationships among intragastric meal distribution during gastric emptying scintigraphy, water consumption during water load satiety testing, and symptoms of gastroparesis.

Gastric emptying scintigraphy (GES) measures total gastric retention after a solid meal and can assess intragastric meal distribution (IMD). Water load satiety test (WLST) measures gastric capacity. Both IMD immediately after meal ingestion [ratio of proximal gastric counts after meal ingestion to total gastric counts at time 0 (IMD0)] and WLST (volume of water ingested over 5 min) are indirect measures of gastric accommodation. In this study, IMD0 and WLST were compared with each other and to symptoms of gastroparesis to gauge their clinical utility for assessing patients with symptoms of gastroparesis. Patients with symptoms of gastroparesis underwent GES to obtain gastric retention and IMD0, WLST, and filled out patient assessment of upper GI symptoms. A total of 234 patients with symptoms of gastroparesis were assessed (86 patients with diabetes, 130 idiopathic, 18 postfundoplication) and 175 (75%) delayed gastric emptying. Low IMD0 <0.568 suggesting initial rapid transit to the distal stomach was present in 8% and correlated with lower gastric retention, less heartburn, and lower volumes consumed during WLST. Low WLST volume (<238 mL) was present in 20% and associated with increased severity of early satiety, postprandial fullness, loss of appetite, and nausea. Low IMD0 is associated with less gastric retention and less heartburn. Volume of water consumed during WLST, while associated with IMD0, has associations with early satiety, postprandial fullness, loss of appetite, and nausea. Thus, IMD0 and WLST appear to overlap somewhat in their assessment of gastric physiology in adults with symptoms of gastroparesis but relate to different dyspeptic symptoms.NEW & NOTEWORTHY IMD0 and WLST were assessed for their clinical utility in assessing patients with symptoms of gastroparesis. Low IMD0 is associated with less gastric retention and less heartburn. Volume of water consumed during WLST, while associated with IMD0, has associations with early satiety, postprandial fullness, loss of appetite, and nausea. IMD0 and WLST appear to overlap somewhat in their assessment of gastric physiology in adults with symptoms of gastroparesis but relate to different dyspeptic symptoms.

Postprandial symptoms in patients with symptoms of gastroparesis: roles of gastric emptying and accommodation.

Patients often are evaluated for gastroparesis because of symptoms occurring with meals. Gastric emptying scintigraphy (GES) is used for gastroparesis diagnosis, although results are not well correlated with gastroparesis symptoms. The aim of this study is to assess relationships between gastroparesis symptoms, gastric emptying (GE), and gastric accommodation (GA). Patients with symptoms of gastroparesis completed the Patient Assessment of Upper GI Symptoms (PAGI-SYM) and recorded symptoms during GES and water load satiety test (WLST), an indirect assessment for GA. A total of 109 patients with gastroparesis symptoms were assessed. Symptom severity increased after GES meal for stomach fullness, belching, nausea, abdominal burning, and abdominal pain. There was no difference in symptoms after meal between patients with delayed (n = 66) and normal (n = 42) GE. Diabetic patients (n = 26) had greater gastric retention than idiopathic patients (n = 78), but idiopathic patients had greater postprandial nausea, stomach fullness, and abdominal pain. Water consumed during WLST averaged 421 ± 245 mL. Idiopathic patients had greater nausea scores during WLST than diabetic patients. In comparison to those with normal water consumption (≥238 mL; n = 80), patients with impaired water ingestion (<238 mL; n = 26) had increased stomach fullness, early satiety, postprandial fullness, and loss of appetite on PAGI-SYM. Patients with delayed and normal GE had similar symptom profiles during GES and WLST. Idiopathic patients had less gastric retention but more symptoms after GES meal and after WLST compared with diabetic patients. Patients with impaired water consumption during WLST had increased symptoms by PAGI-SYM. These data suggest that impaired GA, rather than GE, may be important in explaining postprandial symptoms in patients with symptoms of gastroparesis.NEW & NOTEWORTHY Patients with delayed and normal gastric emptying (GE) had similar symptom profiles during gastric emptying scintigraphy (GES). Idiopathic patients with symptoms of gastroparesis had less gastric retention by GES; but more symptoms after GES meal and after water load satiety test (WLST) compared with diabetic patients. In patients with symptoms of gastroparesis, symptoms after WLST increased with decreasing water consumption. Early satiety and loss of appetite were associated with decreased water consumption during WLST. Thus, impaired accommodation and perhaps visceral hypersensitivity are important in explaining postprandial symptoms in gastroparesis.

Progress in Gastroparesis - A Narrative Review of the Work of the Gastroparesis Clinical Research Consortium.

The Gastroparesis Clinical Research Consortium is a multicenter coalition created and funded by the National Institutes of Diabetes and Digestive and Kidney Disorders, with a mission to advance understanding of the pathophysiology of gastroparesis and develop an effective treatment for patients with symptomatic gastroparesis. In this review, we summarize the results of the published Gastroparesis Clinical Research Consortium studies as a ready and convenient resource for gastroenterologists and others to provide a clear understanding of the consortium's experience and perspective on gastroparesis and related disorders.

Constipation in Patients With Symptoms of Gastroparesis: Analysis of Symptoms and Gastrointestinal Transit.

BACKGROUND & AIMS: Constipation can be an important symptom in some patients with gastroparesis. The aims were to: 1) Determine prevalence of constipation and delayed colonic transit in patients with symptoms of gastroparesis; 2) Correlate severity of constipation to severity of symptoms of gastroparesis; and 3) Relate severity of constipation to GI transit delays assessed by gastric emptying scintigraphy (GES) and wireless motility capsule (WMC). METHODS: Patients with symptoms of gastroparesis underwent gastric emptying scintigraphy (GES), wireless motility capsule (WMC) assessing gastric emptying, small bowel transit, and colonic transit, and questionnaires assessing symptoms using a modified Patient Assessment of Upper GI Symptoms [PAGI-SYM] and Rome III functional GI disorder questionnaire. RESULTS: Of 338 patients with symptoms of gastroparesis, 242 (71.5%) had delayed gastric emptying by scintigraphy; 298 (88.2%) also met criteria for functional dyspepsia. Severity of constipation was severe/very severe in 34% patients, moderate in 24%, and none/very mild/mild in 42%. Increasing severity of constipation was associated with increasing symptoms of gastroparesis and presence of irritable bowel syndrome (IBS). Severity of constipation was not associated with gastric retention on GES or WMC. Delayed colonic transit was present in 108 patients (32% of patients). Increasing severity of constipation was associated with increasing small bowel transit time, colonic transit time, and whole gut transit time. CONCLUSIONS: Severe/very severe constipation and delayed colon transit occurs in a third of patients with symptoms of gastroparesis. The severity of constipation is associated with severity of gastroparesis symptoms, presence of IBS, small bowel and colon transit delay, but not delay in gastric emptying. ClinicalTrials.gov Identifier: NCT01696747.

Effect of Domperidone Therapy on Gastroparesis Symptoms: Results of a Dynamic Cohort Study by NIDDK Gastroparesis Consortium.

BACKGROUND & AIMS: The use of domperidone (DOM) for gastroparesis (GP) remains controversial and limited. We aimed to present outcomes of DOM therapy for treatment of patients participating in the multicenter National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC) Registries (GpR). METHODS: The GpCRC cohort consisted of patients with GP (75%) and with GP-like symptoms but with normal gastric emptying (25%). The DOM group initiated therapy during the 96 weeks of enrollment in GpR1 and GpR2. Patients who had previously taken or who were on DOM therapy at enrollment were excluded from this analysis. The control group did not use domperidone (non-DOM group) before or after enrollment. The following outcome measures were identified: change from baseline in Gastroparesis Cardinal Symptom Index total score, with 3 subscales, plus Gastroesophageal Reflux Disease and Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life scores. RESULTS: Overall, of 748 patients, 181 (24%) were in the DOM group, whereas 567 were in the non-DOM group. Sixty-three percent of participants had idiopathic GP. At baseline, DOM patients compared with non-DOM patients were significantly younger, had lower body mass index, non-Hispanic ethnicity, a higher annual household income, lower narcotic utilization, lower supplemental and complimentary medication use, and were more likely to have delayed gastric emptying time, as well as worse nausea and fullness scores. Compared with non-DOM patients, DOM patients experienced moderate but significantly more improvement in GP outcome measures: Gastroparesis Cardinal Symptom Index total score (P = .003), nausea (P = .003), and fullness subscales (P =.005), upper abdominal pain score (P = .04), Gastroesophageal Reflux Disease score (P = .05), and Patient Assessment of Upper Gastrointestinal Disorders-Quality of Life score (P = .05). CONCLUSIONS: Utilizing the method of pragmatic modeling to evaluate long-term treatment of GP in a large GpCRC database, DOM treatment resulted in moderately but significantly improved GP. NOTE: This project was based on data generated by 2 GpCRC Registry studies recognized under the Clinicaltrial.gov numbers: NCT00398801 and NCT01696747 symptoms compared with a group receiving standard-of-care but not DOM.

Functional Dyspepsia and Gastroparesis in Tertiary Care are Interchangeable Syndromes With Common Clinical and Pathologic Features.

BACKGROUND: The aim of this study was to clarify the pathophysiology of functional dyspepsia (FD), a highly prevalent gastrointestinal syndrome, and its relationship with the better-understood syndrome of gastroparesis. METHODS: Adult patients with chronic upper gastrointestinal symptoms were followed up prospectively for 48 weeks in multi-center registry studies. Patients were classified as having gastroparesis if gastric emptying was delayed; if not, they were labeled as having FD if they met Rome III criteria. Study analysis was conducted using analysis of covariance and regression models. RESULTS: Of 944 patients enrolled during a 12-year period, 720 (76%) were in the gastroparesis group and 224 (24%) in the FD group. Baseline clinical characteristics and severity of upper gastrointestinal symptoms were highly similar. The 48-week clinical outcome was also similar but at this time 42% of patients with an initial diagnosis of gastroparesis were reclassified as FD based on gastric-emptying results at this time point; conversely, 37% of patients with FD were reclassified as having gastroparesis. Change in either direction was not associated with any difference in symptom severity changes. Full-thickness biopsies of the stomach showed loss of interstitial cells of Cajal and CD206+ macrophages in both groups compared with obese controls. CONCLUSIONS: A year after initial classification, patients with FD and gastroparesis, as seen in tertiary referral centers at least, are not distinguishable based on clinical and pathologic features or based on assessment of gastric emptying. Gastric-emptying results are labile and do not reliably capture the pathophysiology of clinical symptoms in either condition. FD and gastroparesis are unified by characteristic pathologic features and should be considered as part of the same spectrum of truly "organic" gastric neuromuscular disorders. CLINICALTRIALS. GOV IDENTIFIER: NCT00398801, NCT01696747.

Intestinal Bacteria Maintain Adult Enteric Nervous System and Nitrergic Neurons via Toll-like Receptor 2-induced Neurogenesis in Mice.

BACKGROUND & AIMS: The enteric nervous system (ENS) exists in close proximity to luminal bacteria. Intestinal microbes regulate ENS development, but little is known about their effects on adult enteric neurons. We investigated whether intestinal bacteria or their products affect the adult ENS via toll-like receptors (TLRs) in mice. METHODS: We performed studies with conventional C57/BL6, germ-free C57/BL6, Nestin-creERT2:tdTomato, Nestin-GFP, and ChAT-cre:tdTomato. Mice were given drinking water with ampicillin or without (controls). Germ-free mice were given drinking water with TLR2 agonist or without (controls). Some mice were given a blocking antibody against TLR2 or a TLR4 inhibitor. We performed whole gut transit, bead latency, and geometric center studies. Feces were collected and analyzed by 16S ribosomal RNA gene sequencing. Longitudinal muscle myenteric plexus (LMMP) tissues were collected, analyzed by immunohistochemistry, and levels of nitric oxide were measured. Cells were isolated from colonic LMMP of Nestin-creERT2:tdTomato mice and incubated with agonists of TLR2 (receptor for gram-positive bacteria), TLR4 (receptor for gram-negative bacteria), or distilled water (control) and analyzed by flow cytometry. RESULTS: Stool from mice given ampicillin had altered composition of gut microbiota with reduced abundance of gram-positive bacteria and increased abundance of gram-negative bacteria, compared with mice given only water. Mice given ampicillin had reduced colon motility compared with mice given only water, and their colonic LMMP had reduced numbers of nitrergic neurons, reduced neuronal nitric oxide synthase production, and reduced colonic neurogenesis. Numbers of colonic myenteric neurons increased after mice were switched from ampicillin to plain water, with increased markers of neurogenesis. Nestin-positive enteric neural precursor cells expressed TLR2 and TLR4. In cells isolated from the colonic LMMP, incubation with the TLR2 agonist increased the percentage of neurons originating from enteric neural precursor cells to approximately 10%, compared with approximately 0.01% in cells incubated with the TLR4 agonist or distilled water. Mice given an antibody against TLR2 had prolonged whole gut transit times; their colonic LMMP had reduced total neurons and a smaller proportion of nitrergic neurons per ganglion, and reduced markers of neurogenesis compared with mice given saline. Colonic LMMP of mice given the TLR4 inhibitor did not have reduced markers of neurogenesis. Colonic LMMP of germ-free mice given TLR2 agonist had increased neuronal numbers compared with control germ-free mice. CONCLUSIONS: In the adult mouse colon, TLR2 promotes colonic neurogenesis, regulated by intestinal bacteria. Our findings indicate that colonic microbiota help maintain the adult ENS via a specific signaling pathway. Pharmacologic and probiotic approaches directed towards specific TLR2 signaling processes might be developed for treatment of colonic motility disorders related to use of antibiotics or other factors.

Novel and effective disposable device that provides 2-way protection to the duodenoscope from microbial contamination.

BACKGROUND AND AIMS: Duodenoscope contamination is associated with notable patient morbidity and mortality and can occur despite high-level disinfection protocols, requiring a solution that protects against contamination of the endoscope in the first place. METHODS: We assessed a newly cleared, single-use device to seal the distal end of duodenoscopes while preserving optics and other endoscope functionality and tested its ability to protect against contamination using dye immersion tests and microbial inoculation. RESULTS: Dye immersion tests revealed a complete seal with no leakage. Rigorous microbial challenge tests showed the device can both protect against contamination of the endoscope by external microbes ("outside-in" protection) and shield instruments from contact with pre-existing microbial biofilm on or around the elevator that may have survived reprocessing ("inside-out" protection). Optical and mechanical performance of the endoscope was not compromised by the addition of the device. CONCLUSIONS: The results show that this disposable device provides 2-way protection to the duodenoscope from microbial contamination, without the potential for disrupting current equipment, technique, and workflow.

Marijuana Use in Patients with Symptoms of Gastroparesis: Prevalence, Patient Characteristics, and Perceived Benefit.

BACKGROUND: Marijuana may be used by some patients with gastroparesis (Gp) for its potential antiemetic, orexigenic, and pain-relieving effects. AIMS: The aim of this study was to describe the use of marijuana by patients for symptoms of Gp, assessing prevalence of use, patient characteristics, and patients' perceived benefit on their symptoms of Gp. METHODS: Patients with symptoms of Gp underwent history and physical examination, gastric emptying scintigraphy, and questionnaires assessing symptoms. Patients were asked about the current use of medications and alternative medications including marijuana. RESULTS: Fifty-nine of 506 (11.7%) patients with symptoms of Gp reported current marijuana use, being similar among patients with delayed and normal gastric emptying and similar in idiopathic and diabetic patients. Patients using marijuana were younger, more often current tobacco smokers, less likely to be a college graduate, married or have income > $50,000. Patients using marijuana had higher nausea/vomiting subscore (2.7 vs 2.1; p = 0.002), higher upper abdominal pain subscore (3.5 vs 2.9; p = 0.003), more likely to be using promethazine (37 vs 25%; p = 0.05) and dronabinol (17 vs 3%; p < 0.0001). Of patients using marijuana, 51% had been using it for more than 2 years, 47% were using this once or more per day, and 81% of marijuana users rated their benefit from marijuana as better or much better. CONCLUSIONS: A subset of patients (12%) with symptoms of Gp use marijuana. Patients with severe nausea and abdominal pain were more likely to use marijuana and perceive it to be beneficial for their symptoms. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01696747.

Adult enteric nervous system in health is maintained by a dynamic balance between neuronal apoptosis and neurogenesis.

According to current dogma, there is little or no ongoing neurogenesis in the fully developed adult enteric nervous system. This lack of neurogenesis leaves unanswered the question of how enteric neuronal populations are maintained in adult guts, given previous reports of ongoing neuronal death. Here, we confirm that despite ongoing neuronal cell loss because of apoptosis in the myenteric ganglia of the adult small intestine, total myenteric neuronal numbers remain constant. This observed neuronal homeostasis is maintained by new neurons formed in vivo from dividing precursor cells that are located within myenteric ganglia and express both Nestin and p75NTR, but not the pan-glial marker Sox10. Mutation of the phosphatase and tensin homolog gene in this pool of adult precursors leads to an increase in enteric neuronal number, resulting in ganglioneuromatosis, modeling the corresponding disorder in humans. Taken together, our results show significant turnover and neurogenesis of adult enteric neurons and provide a paradigm for understanding the enteric nervous system in health and disease.

Proteomics in gastroparesis: unique and overlapping protein signatures in diabetic and idiopathic gastroparesis.

Macrophage-based immune dysregulation plays a critical role in development of delayed gastric emptying in diabetic mice. Loss of anti-inflammatory macrophages and increased expression of genes associated with pro-inflammatory macrophages has been reported in full-thickness gastric biopsies from gastroparesis patients. We aimed to determine broader protein expression (proteomics) and protein-based signaling pathways in gastric biopsies of diabetic (DG) and idiopathic gastroparesis (IG) patients. Additionally, we determined correlations between protein expressions, gastric emptying, and symptoms. Full-thickness gastric antrum biopsies were obtained from nine DG patients, seven IG patients, and five nondiabetic controls. Aptamer-based SomaLogic tissue scan that quantitatively identifies 1,305 human proteins was used. Protein fold changes were computed, and differential expressions were calculated using Limma. Ingenuity pathway analysis and correlations were carried out. Multiple-testing corrected P < 0.05 was considered statistically significant. Seventy-three proteins were differentially expressed in DG, 132 proteins were differentially expressed in IG, and 40 proteins were common to DG and IG. In both DG and IG, "Role of Macrophages, Fibroblasts and Endothelial Cells" was the most statistically significant altered pathway [DG false discovery rate (FDR) = 7.9 × 10-9; IG FDR = 6.3 × 10-12]. In DG, properdin expression correlated with GCSI bloating (r = -0.99, FDR = 0.02) and expressions of prostaglandin G/H synthase 2, protein kinase C-ζ type, and complement C2 correlated with 4 h gastric retention (r = -0.97, FDR = 0.03 for all). No correlations were found between proteins and symptoms or gastric emptying in IG. Protein expression changes suggest a central role of macrophage-driven immune dysregulation in gastroparesis, specifically, complement activation in diabetic gastroparesis.NEW & NOTEWORTHY This study uses SOMAscan, a novel proteomics assay for determination of altered proteins and associated molecular pathways in human gastroparesis. Seventy-three proteins were changed in diabetic gastroparesis, 132 in idiopathic gastroparesis compared with controls. Forty proteins were common in both. Macrophage-based immune dysregulation pathway was most significantly affected in both diabetic and idiopathic gastroparesis. Proteins involved in the complement and prostaglandin synthesis pathway were associated with symptoms and gastric emptying delay in diabetic gastroparesis.

Functional Bowel Disorders: A Roadmap to Guide the Next Generation of Research.

In June 2016, the National Institutes of Health hosted a workshop on functional bowel disorders (FBDs), particularly irritable bowel syndrome, with the objective of elucidating gaps in current knowledge and recommending strategies to address these gaps. The workshop aimed to provide a roadmap to help strategically guide research efforts during the next decade. Attendees were a diverse group of internationally recognized leaders in basic and clinical FBD research. This document summarizes the results of their deliberations, including the following general conclusions and recommendations. First, the high prevalence, economic burden, and impact on quality of life associated with FBDs necessitate an urgent need for improved understanding of FBDs. Second, preclinical discoveries are at a point that they can be realistically translated into novel diagnostic tests and treatments. Third, FBDs are broadly accepted as bidirectional disorders of the brain-gut axis, differentially affecting individuals throughout life. Research must integrate each component of the brain-gut axis and the influence of biological sex, early-life stressors, and genetic and epigenetic factors in individual patients. Fourth, research priorities to improve diagnostic and management paradigms include enhancement of the provider-patient relationship, longitudinal studies to identify risk and protective factors of FBDs, identification of biomarkers and endophenotypes in symptom severity and treatment response, and incorporation of emerging "-omics" discoveries. These paradigms can be applied by well-trained clinicians who are familiar with multimodal treatments. Fifth, essential components of a successful program will include the generation of a large, validated, broadly accessible database that is rigorously phenotyped; a parallel, linkable biorepository; dedicated resources to support peer-reviewed, hypothesis-driven research; access to dedicated bioinformatics expertise; and oversight by funding agencies to review priorities, progress, and potential synergies with relevant stakeholders.

Opioid Use and Potency Are Associated With Clinical Features, Quality of Life, and Use of Resources in Patients With Gastroparesis.

BACKGROUND & AIMS: Many patients with gastroparesis are prescribed opioids for pain control, but indications for opioid prescriptions and the relationship of opioid use to gastroparesis manifestations are undefined. We characterized associations of use of potent vs weaker opioids and presentations of diabetic and idiopathic gastroparesis. METHODS: We collected data on symptoms, gastric emptying, quality of life, and health care resource use from 583 patients with gastroparesis (>10% 4-h scintigraphic retention) from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Consortium, from January 2007 through November 2016. Patients completed medical questionnaires that included questions about opioid use. The opioid(s) were categorized for potency relative to oral morphine. Symptom severities were quantified by Patient Assessment of Upper Gastrointestinal Disorders Symptoms questionnaires. Subgroup analyses compared patients on potent vs weaker opioids and opioid effects in diabetic vs idiopathic etiologies. RESULTS: Forty-one percent of patients were taking opioids; 82% of these took potent agents (morphine, hydrocodone, oxycodone, methadone, hydromorphone, buprenorphine, or fentanyl). Abdominal pain was the reason for prescription for 61% of patients taking opioids. Mean scores for gastroparesis, nausea/vomiting, bloating/distention, abdominal pain, and constipation scores were higher in opioid users (P ≤ .05). Opioid use was associated with greater levels of gastric retention, worse quality of life, increased hospitalization, and increased use of antiemetic and pain modulator medications compared with nonusers (P ≤ .03). Use of potent opioids was associated with worse gastroparesis, nausea/vomiting, upper abdominal pain, and quality-of-life scores, and more hospitalizations compared with weaker opioids (tapentadol, tramadol, codeine, or propoxyphene) (P ≤ .05). Opioid use was associated with larger increases in gastric retention in patients with idiopathic vs diabetic gastroparesis (P = .008). CONCLUSIONS: Opioid use is prevalent among patients with diabetic or idiopathic gastroparesis, and is associated with worse symptoms, delays in gastric emptying, and lower quality of life, as well as greater use of resources. Potent opioids are associated with larger effects than weaker agents. These findings form a basis for studies to characterize adverse outcomes of opioid use in patients with gastroparesis and to help identify those who might benefit from interventions to prevent opioid overuse.

Aprepitant Has Mixed Effects on Nausea and Reduces Other Symptoms in Patients With Gastroparesis and Related Disorders.

BACKGROUND & AIMS: There are few effective treatments for nausea and other symptoms in patients with gastroparesis and related syndromes. We performed a randomized trial of the ability of the neurokinin-1 receptor antagonist aprepitant to reduce symptoms in patients with chronic nausea and vomiting caused by gastroparesis or gastroparesis-like syndrome. METHODS: We conducted a 4-week multicenter, double-masked trial of 126 patients with at least moderate symptoms of chronic nausea and vomiting of presumed gastric origin for a minimum of 6 months. Patients were randomly assigned to groups given oral aprepitant (125 mg/day, n = 63) or placebo (n = 63). The primary outcome from the intention-to-treat analysis was reduction in nausea, defined as a decrease of 25 mm or more, or absolute level below 25 mm, on a daily patient-reported 0-to-100 visual analog scale (VAS) of nausea severity. We calculated relative risks of nausea improvement using stratified Cochran-Mental-Haenszel analysis. RESULTS: Aprepitant did not reduce symptoms of nausea, based on the primary outcome measure (46% reduction in the VAS score in the aprepitant group vs 40% reduction in the placebo group; relative risk, 1.2; 95% CI, 0.8-1.7) (P = .43). However, patients in the aprepitant group had significant changes in secondary outcomes such as reduction in symptom severity (measured by the 0-5 Gastroparesis Clinical Symptom Index) for nausea (1.8 vs 1.0; P = .005), vomiting (1.6 vs 0.5; P = .001), and overall symptoms (1.3 vs 0.7; P = .001). Adverse events, predominantly mild or moderate in severity grade, were more common in aprepitant (22 of 63 patients, 35% vs 11 of 63, 17% in the placebo group) (P = .04). CONCLUSIONS: In a randomized trial of patients with chronic nausea and vomiting caused by gastroparesis or gastroparesis-like syndrome, aprepitant did not reduce the severity of nausea when reduction in VAS score was used as the primary outcome. However, aprepitant had varying effects on secondary outcomes of symptom improvement. These findings support the need to identify appropriate patient outcomes for trials of therapies for gastroparesis, including potential additional trials for aprepitant. ClinicalTrials.gov no: NCT01149369.

Ethnic, Racial, and Sex Differences in Etiology, Symptoms, Treatment, and Symptom Outcomes of Patients With Gastroparesis.

BACKGROUND & AIMS: Gastroparesis is a chronic disorder of the stomach characterized by nausea, vomiting, early satiety, postprandial fullness, and abdominal pain. There is limited information on gastroparesis in minority populations. We assessed ethnic, racial, and sex variations in the etiology, symptoms, quality of life, gastric emptying, treatments, and symptom outcomes of patients with gastroparesis. METHODS: We collected information from the National Institutes of Health Gastroparesis Consortium on 718 adult patients, from September 2007 through December 2017. Patients were followed every 4 or 6 months, when data were collected on medical histories, symptoms (based on answers to the PAGI-SYM questionnaires), and quality of life (based on SF-36). Follow-up information collected at 1 year (48 week) was used in this analysis. Comparisons were made between patients of self-reported non-Hispanic white, non-Hispanic black, and Hispanic ethnicities, as well as and between male and female patients. RESULTS: Our final analysis included 552 non-Hispanic whites (77%), 83 persons of Hispanic ethnicity (12%), 62 non-Hispanic blacks (9%), 603 women (84%), and 115 men (16%). A significantly higher proportion of non-Hispanic blacks (60%) had gastroparesis of diabetic etiology than of non-Hispanic whites (28%); non-Hispanic blacks also had more severe retching (2.5 vs 1.7 score) and vomiting (2.9 vs 1.8 score) and a higher percentage were hospitalized in the past year (66% vs 38%). A significantly higher proportion of Hispanics had gastroparesis of diabetic etiology (59%) than non-Hispanic whites (28%), but Hispanics had less-severe nausea (2.7 vs 3.3 score), less early satiety (3.0 vs 3.5 score), and a lower proportion used domperidone (8% vs 21%) or had a peripherally inserted central catheter (1% vs 7%). A higher proportion of women had gastroparesis of idiopathic etiology (69%) than men (46%); women had more severe symptoms of stomach fullness (3.6 vs 3.1 score), early satiety (3.5 vs 2.9 score), postprandial fullness (3.7 vs 3.1 score), bloating (3.3 vs 2.6 score), stomach visibly larger (3.0 vs 2.1 score), and upper abdominal pain (2.9 vs 2.4 score). A lower proportion of women were hospitalized in past year (39% vs 53% of men). CONCLUSIONS: In patients with gastroparesis, etiologies, symptom severity, and treatments vary among races and ethnicities and between sexes. ClinicalTrials.gov Identifier: NCT01696747.

Delayed Gastric Emptying Associates With Diabetic Complications in Diabetic Patients With Symptoms of Gastroparesis.

OBJECTIVES: Diabetic gastroparesis (Gp) occurs more often in type 1 diabetes mellitus (T1DM) than in type 2 diabetes mellitus (T2DM). Other diabetic end-organ complications include peripheral neuropathy, nephropathy, and retinopathy (together termed triopathy). This study determines the prevalence of diabetic complications (retinopathy, nephropathy, and peripheral neuropathy) in diabetic patients with symptoms of Gp, assessing the differences between T1DM and T2DM and delayed and normal gastric emptying (GE). METHODS: Diabetic patients with symptoms of Gp underwent history and physical examination, GE scintigraphy, electrogastrography with water load, autonomic function testing, and questionnaires assessing symptoms and peripheral neuropathy. RESULTS: One hundred thirty-three diabetic patients with symptoms of Gp were studied: 59 with T1DM and 74 with T2DM and 103 with delayed GE and 30 without delayed GE. The presence of retinopathy (37% vs 24%; P = 0.13), nephropathy (19% vs 11%; P = 0.22), and peripheral neuropathy (53% vs 39%; P = 0.16) was not significantly higher in T1DM than in T2DM; however, triopathies (all 3 complications together) were seen in 10% of T1DM and 3% of T2DM (P = 0.04). Diabetic patients with delayed GE had increased prevalence of retinopathy (36% vs 10%; P = 0.006) and number of diabetic complications (1.0 vs 0.5; P = 0.009); however, 39% of diabetic patients with delayed GE did not have any diabetic complications. DISCUSSION: In diabetic patients with symptoms of Gp, delayed GE was associated with the presence of retinopathy and the total number of diabetic complications. Only 10% of patients with T1DM and 3% of those with T2DM had triopathy of complications, and 39% of diabetic patients with Gp did not have any diabetic complications. Thus, the presence of diabetic complications should raise awareness for Gp in either T1DM or T2DM; however, diabetic Gp frequently occurs without other diabetic complications.

Endoscopic full-thickness muscle biopsy for rectal tissue sampling in patients with severe gut motility disorders: an initial experience (with video).

BACKGROUND AND AIMS: Diagnosis of GI neuromuscular diseases is mostly on the basis of symptomatology and is often unreliable. Pathologic analysis of affected tissue (eg, the myenteric plexus and muscle) is a potentially valuable method for both diagnosis and advancement of our knowledge about the biologic basis for these syndromes. However, until now access to the deeper layers of the GI tract has been limited, generally requiring invasive surgical techniques. METHODS: We report a "close-then-resect" endoscopic full-thickness biopsy sampling (EFTB) technique using an over-the-scope clip and telescope for rectal muscle biopsy sampling in patients with suspected severe neuromuscular gut disorders. The main outcome measures were technical success and adverse events. RESULTS: Thirteen patients (11 women; mean age 27 ± 5.4 years) with diffusely delayed colonic transit underwent EFTB. The mean (± standard deviation) procedure time was 30 ± 5.2 minutes. The mean size of the resected specimen was 18 ± 3.5 mm. Histologic full-thickness tissue samples were achieved for all patients. Postprocedural adverse events were reported in 2 patients, and both were graded as mild (1 self-limited bleeding and 1 with rectal pain). Hematoxylin and eosin staining of tissue samples confirmed adequate cross-sectional imaging of muscularis propria in all patients with excellent demonstration of the myenteric plexus and both layers of muscle. Two patients demonstrated a decrease in interstitial cells of Cajal as demonstrated by CD117 staining. No cases demonstrated appreciable inflammation involving myenteric ganglia. CONCLUSIONS: Diagnostic EFTB with modified over-the-scope clip for the close-then-resect method appears to be a safe and effective technique to obtain adequate full-thickness rectal specimens, allowing for both quantitative and qualitative analysis for the diagnosis of neuromuscular GI dysmotility.