Preliminary study on the dynamic positron emission tomography imaging with 11C-ER176 to delineate macrophage activation in diabetic gastroparesis

BACKGROUND

Animal models and human data have suggested macrophage-driven immune dysregulation in diabetic gastroparesis (DG). Translocator protein (TSPO) upregulation has been suggested to indicate activated state of macrophages and ER176 is a high affinity third generation TSPO-specific radioligand. The aim of this study was to determine feasibility of dynamic 11C-ER 176 PET to identify macrophage activation in DG.

METHODS

Twelve patients, all females, were recruited (4 DG, 4 diabetics, and 4 healthy volunteers) for 11C-ER 176 PET/CT scanning. The standardized uptake value (SUVmax) in the gastric fundus, body, pylorus, and descending part of the duodenum were compared between three groups using Kruskal-Wallis test to perform the comparisons, and a p-value of 0.05 was considered statistically significant.

KEY RESULTS

Age was comparable among the three groups with a median of 53 years. The uptake was higher in pylorus in diabetics compared to DG and healthy (SUVmax healthy 4.6 ± 0.2, diabetics 8.4 ± 4.1, DG 5.5 ± 1.0, p = 0.04). The uptake was similar in gastric fundus (9.0 ± 1.6, 13.1 ± 8.3, 7.8 ± 1.9 respectively, p = 0.3), body (7.7 ± 1.9, 13 ± 9.2, 7.8 ± 1.9 respectively, p = 0.8), and duodenum (6.2 ± 2.1, 9.5 ± 6.8, 7.0 ± 1.8 respectively, p = 0.6). No correlation was observed between SUVmax uptake and either HbA1C or fasting blood glucose.

CONCLUSIONS AND INFERENCES

Female diabetic gastroparesis patients did not demonstrate increased TSPO ligand 11C-ER 176 uptake in the stomach. Possible explanations include lack of specificity of ligand for specific macrophage phenotypes in DG, sex effect, or small sample size. Further studies investigating non-invasive ways of analyzing immune dysregulation in neurogastrointestinal disorders are warranted.

Single cell atlas of human gastric muscle immune cells and macrophage-driven changes in idiopathic gastroparesis

Gastrointestinal immune cells, particularly muscularis macrophages (MM) interact with the enteric nervous system and influence gastrointestinal motility. Here we determine the human gastric muscle immunome and its changes in patients with idiopathic gastroparesis (IG). Single cell sequencing was performed on 26,000 CD45+ cells obtained from the gastric tissue of 20 subjects. We demonstrate 11 immune cell clusters with T cells being most abundant followed by myeloid cells. The proportions of cells belonging to the 11 clusters were similar between IG and controls. However, 9/11 clusters showed 578-11,429 differentially expressed genes. In IG, MM had decreased expression of tissue-protective and microglial genes and increased the expression of monocyte trafficking and stromal activating genes. Furthermore, in IG, IL12 mediated JAK-STAT signaling involved in the activation of tissue-resident macrophages and Eph-ephrin signaling involved in monocyte chemotaxis were upregulated. Patients with IG had a greater abundance of monocyte-like cells. These data further link immune dysregulation to the pathophysiology of gastroparesis.

High-Dimensional Clustering of 4000 Irritable Bowel Syndrome Patients Reveals Seven Distinct Disease Subsets

BACKGROUND AND AIMS

Irritable bowel syndrome (IBS) is a pain disorder classified by bowel habits, disregarding other factors that may influence the clinical course. The aim of this study was to determine if IBS patients can be clustered based on clinical, dietary, lifestyle, and psychosocial factors.

METHODS

Between 2013 and 2020, the Mayo Clinic Biobank surveyed and received 40,291 responses to a questionnaire incorporating Rome III criteria. Factors associated with IBS were determined and latent class analysis, a model-based clustering, was performed on IBS cases.

RESULTS

We identified 4021 IBS patients (mean 64 years; 75% women) and 12,063 controls. Using 26 variables separating cases from controls, the optimal clustering revealed 7 latent clusters. These were characterized by perceived health impairment (moderate or severe), psychoneurological factors, and bowel dysfunction (diarrhea or constipation predominance). Health impairment clusters demonstrated more pain, with the severe cluster also having more psychiatric comorbidities. The next 3 clusters had unique enrichment of psychiatric, neurological, or both comorbidities. The bowel dysfunction clusters demonstrated less abdominal pain, with diarrhea cluster most likely to report pain improvement with defecation. The constipation cluster had the highest exercise score and consumption of fruits, vegetables, and alcohol. The distribution of clusters remained similar when Rome IV criteria were applied. Physiologic tests were available on a limited subset (6%), and there were no significant differences between clusters.

CONCLUSIONS

In this cohort of older IBS patients, 7 distinct clusters were identified demonstrating varying degrees of gastrointestinal symptoms, comorbidities, dietary, and lifestyle factors. Further research is required to assess whether these unique clusters could be used to direct clinical trials and individualize patient management.

Editorial: Faecal microbiota transplantation in IBS-Moving closer or away from success?

This article is linked to Yau et al papers. To view these articles, visit https://doi.org/10.1111/apt.17703 and https://doi.org/10.1111/apt.17729

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.

Adeno-associated virus-9 reverses delayed gastric emptying of solids in diabetic mice

BACKGROUND

Gastroparesis is defined by delayed gastric emptying (GE) without obstruction. Studies suggest targeting heme oxygenase-1 (HO1) may ameliorate diabetic gastroparesis. Upregulation of HO1 expression via interleukin-10 (IL-10) in the gastric muscularis propria is associated with reversal of delayed GE in diabetic NOD mice. IL-10 activates the M2 cytoprotective phenotype of macrophages and induces expression of HO1 protein. Here, we assess delivery of HO1 by recombinant adeno-associated viruses (AAVs) in diabetic mice with delayed GE.

METHODS

C57BL6 diabetic delayed GE mice were injected with 1 × 1012 vg scAAV9-cre, scAAV9-GFP, or scAAV9-HO1 particles. Changes to GE were assessed weekly utilizing our [13 C]-octanoic acid breath test. Stomach tissue was collected to assess the effect of scAAV9 treatment on Kit, NOS1, and HO1 expression.

KEY RESULTS

Delayed GE returned to normal within 2 weeks of treatment in 7/12 mice receiving scAAV9-cre and in 4/5 mice that received the scAAV9-GFP, whereas mice that received scAAV9-HO1 did not respond in the same manner and had GE that took significantly longer to return to normal (6/7 mice at 4-6 weeks). Kit, NOS1, and HO1 protein expression in scAAV9-GFP-treated mice with normal GE were not significantly different compared with diabetic mice with delayed GE.

CONCLUSIONS AND INFERENCES

Injection of scAAV9 into diabetic C57BL6 mice produced a biological response that resulted in acceleration of GE independently of the cargo delivered by the AAV9 vector. Further research is needed to determine whether use of AAV mediated gene transduction in the gastric muscularis propria is beneficial and warranted.

Intestinal proteases

PURPOSE OF REVIEW

Proteases constitute a group of enzymes that hydrolyze peptide bonds. Intestinal proteases are an integral part of gut homeostasis and digestion. This review discusses the broader classification of proteases, regulation of proteolytic activity (PA) in the intestinal tract, and how dysregulation of intestinal proteases contributes to the pathophysiology of conditions such as irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and celiac disease. We also discuss recent advancements in therapeutic modulation that directly or indirectly target intestinal proteases and can be utilized to treat these illnesses.

RECENT FINDINGS

Host and microbiota derived proteases have been associated with symptoms in subsets of patients with IBS, IBD and celiac disease. Elevated PA mediates barrier dysfunction, visceral hypersensitivity as well as immune activation and inflammation. Recent mechanistic studies have revealed the nature of disease-associated proteases and mechanisms regulating their activity, particularly those driven by the microbiota. Advancements in activity-based probes have allowed novel ways of in vivo imaging of PA. Newer strategies targeting proteases include monoclonal antibodies, engineered microbiota as well as specific protease inhibitors.

SUMMARY

Significant progresses made in the detection as well as regulation of PA is likely to provide therapeutic advancements for gastrointestinal diseases.

A pilot genome-wide association study meta-analysis of gastroparesis

BACKGROUND

Gastroparesis (GP) is characterized by delayed gastric emptying in the absence of mechanical obstruction.

OBJECTIVE

Genetic predisposition may play a role; however, investigation at the genome-wide level has not been performed.

METHODS

We carried out a genome-wide association study (GWAS) meta-analysis on (i) 478 GP patients from the National Institute of Diabetes and Digestive and Kidney Diseases Gastroparesis Clinical Research Consortium (GpCRC) compared to 9931 population-based controls from the University of Michigan Health and Retirement Study; and (ii) 402 GP cases compared to 48,340 non-gastroparesis controls from the Michigan Genomics Initiative. Associations for 5,811,784 high-quality SNPs were tested on a total of 880 GP patients and 58,271 controls, using logistic mixed models adjusted for age, sex, and principal components. Gene mapping was obtained based on genomic position and expression quantitative trait loci, and a gene-set network enrichment analysis was performed. Genetic associations with clinical data were tested in GpCRC patients. Protein expression of selected candidate genes was determined in full thickness gastric biopsies from GpCRC patients and controls.

RESULTS

While no SNP associations were detected at strict significance (p ≤ 5 × 10-8 ), nine independent genomic loci were associated at suggestive significance (p ≤ 1 × 10-5 ), with the strongest signal (rs9273363, odds ratio = 1.4, p = 1 × 10-7 ) mapped to the human leukocyte antigen region. Computational annotation of suggestive risk loci identified 14 protein-coding candidate genes. Gene-set network enrichment analysis revealed pathways potentially involved in immune and motor dysregulation (pFDR ≤ 0.05). The GP risk allele rs6984536A (Peroxidasin-Like; PXDNL) was associated with increased abdominal pain severity scores (Beta = 0.13, p = 0.03). Gastric muscularis expression of PXDNL also positively correlated with abdominal pain in GP patients (r = 0.8, p = 0.02). Dickkopf WNT Signaling Pathway Inhibitor 1 showed decreased expression in diabetic GP patients (p = 0.005 vs. controls).

CONCLUSION

We report preliminary GWAS findings for GP, which highlight candidate genes and pathways related to immune and sensory-motor dysregulation. Larger studies are needed to validate and expand these findings in independent datasets.

Buspirone for early satiety and symptoms of gastroparesis: A multi-centre, randomised, placebo-controlled, double-masked trial (BESST)

BACKGROUND

Patients with gastroparesis and related disorders have symptoms including early satiety, postprandial fullness and bloating. Buspirone, a 5-HT1 receptor agonist, may improve fundic accommodation.

AIM

To determine if buspirone treatment improves early satiety and postprandial fullness in patients with symptoms of gastroparesis.

METHODS

This 4-week multi-centre clinical trial randomised patients with symptoms of gastroparesis and moderate-to-severe symptoms of fullness (Gastroparesis Cardinal Symptom Index [GCSI] early satiety/postprandial fullness subscore [ES/PPF]) to buspirone (10 mg orally) or placebo three times per day. The primary outcome was a change in the ES/PPF from baseline to 4 weeks. The primary analysis was per protocol intention-to-treat ANCOVA of between-group baseline vs. 4-week differences (DoD) in ES/PPF adjusted for baseline ES/PPF. Results are reported using both nominal and Bonferroni (BF) p values.

RESULTS AND CONCLUSIONS

Ninety-six patients (47 buspirone, 49 placeboes; 92% female, 50% delayed gastric emptying, 39% diabetic) were enrolled. There was no between-groups difference in the 4-week ES/PPF primary outcome: -1.16 ± 1.25 (SD) on buspirone vs -1.03 ± 1.29 (SD) on placebo (mean DoD: -0.11 [95% CI: -0.68, 0.45]; p = 0.69). Buspirone performed better than placebo in patients with severe-to-very severe bloating at baseline compared to patients with none to moderate: (ES/PPF DoD = -0.65 vs. 1.58, pTX*GROUP  = 0.003; pBF  = 0.07). Among individual GCSI symptoms, only bloating appeared to improve with buspirone vs. placebo.

CONCLUSIONS

Patients with moderate-to-severe early satiety/postprandial fullness and other symptoms of gastroparesis did not benefit from buspirone treatment to improve the ES/PPF primary outcome compared with placebo. There was a suggestion of the benefit of buspirone in patients with more severe bloating.

TRIAL REGISTRATION

ClinicalTrials.gov NCT0358714285.

Characteristics and outcomes of patients with gastroparesis using enteral and/or exclusive parenteral nutrition

BACKGROUND

Patients with gastroparesis (Gp) may need enteral nutrition (EN) or exclusive parenteral nutrition (PN). Among patients with Gp, we aimed to (1) identify the frequency of EN and exclusive PN use and (2) explore characteristics of patients using EN and/or exclusive PN compared with those using oral nutrition (ON), including changes over 48 weeks.

METHODS

Patients with Gp underwent history and physical examination, gastric emptying scintigraphy, water load satiety testing (WLST), and questionnaires assessing gastrointestinal symptoms and quality of life (QOL). Patients were observed 48 weeks.

RESULTS

Of 971 patients with Gp (idiopathic, 579; diabetic, 336; post-Nissen fundoplication, 51), 939 (96.7%) were using ON only, 14 (1.4%) using exclusive PN, and 18 (1.9%) using EN. Compared with patients receiving ON, patients receiving exclusive PN and/or EN were younger, had lower body mass index, and had greater symptom severity. Patients receiving exclusive PN and/or EN had lower physical QOL but not mental QOL or Gp-related QOL scores. Patients receiving exclusive PN and/or EN ingested less water during WLST but did not have worse gastric emptying. Of those who had been receiving exclusive PN and/or EN, 50% and 25%, respectively, resumed ON at 48-week follow-up.

CONCLUSIONS

This study describes patients with Gp requiring exclusive PN and/or EN for nutrition support, who represent a small (3.3%) but important subset of patients with Gp. Unique clinical and physiological parameters are associated with this subset and provide insight into the use of nutrition support in Gp.

Effect of liquid and solid test meals on symptoms and gastric myoelectrical activity in patients with gastroparesis and functional dyspepsia

BACKGROUND

Patients with gastroparesis (GP) and functional dyspepsia (FD) have similar symptoms, but the pathophysiology of postprandial symptoms remains uncertain.

AIMS

To compare symptoms and gastric myoelectrical activity (GMA) after liquid and solid test meals in patients with GP and FD.

METHODS

Patients enrolled in the Gastroparesis Clinical Research Consortium Registry were studied. Clinical characteristics were measured with standard questionnaires. GP was determined by 4-h solid-phase gastric scintigraphy. GMA was measured using electrogastrography before and after ingestion of a water load or nutrient bar on separate days. Symptoms were measured on visual analog scales. GMA responses to the water load for individual patients were also determined.

RESULTS

284 patients with GP and 113 with FD were identified who ingested both test meals. Patients with GP and FD had similar maximal tolerated volumes of water [mean (SD) 378 (218) ml vs. 402 (226) ml, p = 0.23] and reported similar intensity of fullness, nausea, bloating, and abdominal discomfort after the test meals. Twenty-six percent and 19% of the patients with GP and FD, respectively, ingested subthreshold (<238 ml) volumes of water (p = 0.15). Gastric dysrhythmias were recorded in 66% of the GP and 65% of the FD patients after the water load. Symptoms and GMA were similar in both groups after ingestion of the nutrient bar.

CONCLUSION

The similarity in GMA responses and symptoms after ingestion of solid or liquid test meals suggests GP and FD are closely related gastric neuromuscular disorders.

Impact of Rome IV criteria on the prevalence of post-infection irritable bowel syndrome

BACKGROUND

The Rome IV irritable bowel syndrome (IBS) criteria include changes to the description and frequency of abdominal pain. Existing studies have demonstrated a lower prevalence and greater severity in IBS patients identified using Rome IV than Rome III criteria. Our aim was to investigate the prevalence of post-infection IBS (PI-IBS) using Rome IV criteria in a population-based cohort of laboratory-confirmed C. jejuni infection cases.

METHODS

The Minnesota Department of Health (MDH) requires notification of Campylobacter cases and interviews patients to gather information on clinical symptoms. For this study, the Rome IV diagnostic questionnaire was utilized 6-9 months after infection to determine the development of PI-IBS. The survey responses were analyzed for the prevalence of IBS and symptom severity.

KEY RESULTS

Surveys were completed by 391 participants (31% response rate). Twenty-three patients had pre-existing IBS, and 18 did not complete enough questions to categorize their case status. Of the 350 remaining participants, 58 (17%) met Rome IV criteria. An additional 47 patients would have met the Rome III IBS criteria for pain frequency, driving the cumulative prevalence to 30%. The mean IBS Symptom Severity Score (IBS-SSS) in Rome IV patients was significantly higher than in Rome III (p < 0.05). With Rome IV, IBS-diarrhea was the most common subtype.

CONCLUSIONS & INFERENCES

Rome IV criteria resulted in a 19% lower prevalence of PI-IBS than earlier reported Rome III-based prevalence in a similar population. Rome IV defined PI-IBS patients have greater symptom severity but similar distribution of IBS subtypes.

Gastroparesis and Functional Dyspepsia: Spectrum of Gastroduodenal Neuromuscular Disorders or Unique Entities?

Gastroparesis is defined by delayed gastric emptying in the absence of mechanical obstruction of the stomach. Patients experience symptoms of nausea, vomiting, abdominal pain, fullness, and early satiety. The recognition of the disorder has progressed due to availability of gastric emptying scintigraphy and advancements made in understanding its pathophysiology and treatment options. The clinical presentation and treatment of gastroparesis overlap with a more commonly recognized disorder of gut-brain interaction, functional dyspepsia. Recent studies have reenergized the discussion whether these two are separate entities or perhaps reflect a spectrum of gastroduodenal neuromuscular disorders. The societal guidelines conflict on the utility of gastric emptying scintigraphy in assessment of patients with upper gastrointestinal symptoms. A better appraisal of similarities and differences between gastroparesis and functional dyspepsia will allow targeted treatment for these disorders. This is particularly important as specific pharmacological and endoscopic treatment options are being developed for gastroparesis which are unlikely to be helpful for functional dyspepsia. This review makes the case for considering these disorders in a spectrum where identification of both would most ideally position us toward providing the optimal clinical care.

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.

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.

Prevalence and clinical correlates of antinuclear antibody in patients with gastroparesis

BACKGROUND

Autoimmunity may play a role in the pathogenesis of gastroparesis in a subset of patients. Antinuclear antibody (ANA) testing is often used to screen for autoimmune disorders.

AIMS

1) Determine prevalence of a positive ANA in patients with gastroparesis; 2) Describe characteristics of idiopathic gastroparesis patients with positive ANA.

METHODS

Patients were assessed with gastric emptying scintigraphy (GES), symptom assessment via Patient Assessment of Upper GI Symptoms [PAGI-SYM], and blood tests-ANA, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP).

RESULTS

Positive ANA was seen in 148 of 893 (17%) patients with gastroparesis, being similar in idiopathic (16% of 536 patients), T1DM (16% of 162), T2DM (18% of 147), and postfundoplication (19% of 48 patients) gastroparesis. Among 536 patients with idiopathic gastroparesis, ANA titer 1:40-1:80 was seen in 33 (6%) patients, 1:160-1:320 in 36 (7%) patients, and ≥1:640 in 17 (3%) patients. Increasing ANA titer was associated with female gender (p = 0.05), Hispanic ethnicity (p = 0.02), comorbid rheumatoid arthritis (p = 0.02), systemic sclerosis (p = 0.004), and elevated ESR (p = 0.007). ANA positivity was associated with lower total GCSI (p = 0.007) and lower nausea/vomiting subscale (p = 0.0005), but not related to gastric emptying.

CONCLUSIONS

The prevalence of a positive ANA in patients with gastroparesis was high at ~17% and did not differ significantly based on etiology. In idiopathic patients, ANA positivity was associated with rheumatoid arthritis, systemic sclerosis, and elevated ESR. ANA-positive gastroparesis represents a subset who often have other autoimmune symptoms or disorders, but less severe nausea and vomiting.

Gut microbial β-glucuronidases regulate host luminal proteases and are depleted in irritable bowel syndrome

Intestinal proteases mediate digestion and immune signaling, while increased gut proteolytic activity disrupts the intestinal barrier and generates visceral hypersensitivity, which in common in irritable bowel syndrome (IBS). However, the mechanisms controlling protease function are unclear. Here we show that members of the gut microbiota suppress intestinal proteolytic activity through production of unconjugated bilirubin. This occurs via microbial β-glucuronidase-mediated conversion of bilirubin conjugates. Metagenomic analysis of fecal samples from patients with post-infection IBS (n=52) revealed an altered gut microbiota composition, in particular a reduction in Alistipes taxa, and high gut proteolytic activity driven by specific host serine proteases compared to controls. Germ-free mice showed 10-fold higher proteolytic activity compared with conventional mice. Colonization with microbiota from high proteolytic activity IBS patients failed to suppress proteolytic activity in germ-free mice, but suppression of proteolytic activity was achieved with colonization using microbiota from healthy donors. High proteolytic activity mice had higher intestinal permeability, a higher relative abundance of Bacteroides and a reduction in Alistipes taxa compared with low proteolytic activity mice. High proteolytic activity IBS patients had lower fecal β-glucuronidase activity and end-products of bilirubin deconjugation. Mice treated with unconjugated bilirubin and β-glucuronidase overexpressing E. coli, which significantly reduced proteolytic activity, while inhibitors of microbial β-glucuronidases increased proteolytic activity. Together, these data define a disease-relevant mechanism of host-microbial interaction that maintains protease homeostasis in the gut.

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.

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.

Postinfection Irritable Bowel Syndrome Following Clostridioides difficile Infection: A Systematic-review and Meta-analysis

BACKGROUND

Postinfection irritable bowel syndrome (PI-IBS) affects ~14% patients after acute bacterial enterocolitis.

AIM

The aim of this study was to conduct a systematic review and meta-analysis to find the prevalence of PI-IBS following Clostridioides difficile infection (CDI).

METHODS

We systematically searched Medline, Embase, and Web of Science from inception through January 20, 2020 for cohort studies assessing PI-IBS following CDI. Primary outcome was pooled prevalence calculated using inverse variance heterogeneity model [MetaXL (v. 5.3)]. A priori subgroup analyses were done [by irritable bowel syndrome (IBS) diagnostic criteria-Rome vs. others, time of IBS diagnosis-<6 or >6 mo, exclusion or inclusion of pre-existing IBS and CDI treatment-antibiotic with fecal microbiota transplantation vs. antibiotic only]. Heterogeneity was considered substantial if I2>50%.

RESULTS

From 2007 to 2019, 15 studies were included (10 prospective, 5 retrospective; 9 full-text, 6 abstracts). Data from 1218 patients were included in the quantitative analysis. Risk of bias was low in 7, medium in 4 and high in 4 studies. Pooled prevalence of PI-IBS was 21.1% (95% confidence interval, 8.2%-35.7%), I2=96%. Common PI-IBS subtypes were diarrhea-predominant in 46.3% (50) patients, and mixed in 33.3% (36) patients. Subgroup analyses by IBS diagnostic criteria, time of IBS diagnosis or CDI treatment did not significantly change the primary outcome (all P>0.05), nor decrease heterogeneity. Funnel plot analysis revealed publication bias.

CONCLUSIONS

Over 20% of patients develop PI-IBS after CDI. Factors such as diagnostic criteria for IBS and CDI treatment did not affect prevalence, though small numbers limit the confidence in these conclusions. Larger, well conducted studies are needed to study PI-IBS in CDI.

Specialized Mechanosensory Epithelial Cells in Mouse Gut Intrinsic Tactile Sensitivity

BACKGROUND AND AIMS

The gastrointestinal (GI) tract extracts nutrients from ingested meals while protecting the organism from infectious agents frequently present in meals. Consequently, most animals conduct the entire digestive process within the GI tract while keeping the luminal contents entirely outside the body, separated by the tightly sealed GI epithelium. Therefore, like the skin and oral cavity, the GI tract must sense the chemical and physical properties of the its external interface to optimize its function. Specialized sensory enteroendocrine cells (EECs) in GI epithelium interact intimately with luminal contents. A subpopulation of EECs express the mechanically gated ion channel Piezo2 and are developmentally and functionally like the skin's touch sensor- the Merkel cell. We hypothesized that Piezo2+ EECs endow the gut with intrinsic tactile sensitivity.

METHODS

We generated transgenic mouse models with optogenetic activators in EECs and Piezo2 conditional knockouts. We used a range of reference standard and novel techniques from single cells to living animals, including single-cell RNA sequencing and opto-electrophysiology, opto-organ baths with luminal shear forces, and in vivo studies that assayed GI transit while manipulating the physical properties of luminal contents.

RESULTS

Piezo2+ EECs have transcriptomic features of synaptically connected, mechanosensory epithelial cells. EEC activation by optogenetics and forces led to Piezo2-dependent alterations in colonic propagating contractions driven by intrinsic circuitry, with Piezo2+ EECs detecting the small luminal forces and physical properties of the luminal contents to regulate transit times in the small and large bowel.

CONCLUSIONS

The GI tract has intrinsic tactile sensitivity that depends on Piezo2+ EECs and allows it to detect luminal forces and physical properties of luminal contents to modulate physiology.

Intestinal chemosensitivity in irritable bowel syndrome associates with small intestinal TRPV channel expression

BACKGROUND

Irritable bowel syndrome (IBS) patients often experience meal-associated symptoms. However, the underlying mechanisms are unclear.

AIM

To determine small intestinal mechanisms of lipid-induced symptoms and rectal hypersensitivity in IBS METHODS: We recruited 26 IBS patients (12 IBS-C, 14 IBS-D) and 15 healthy volunteers (HV). In vivo permeability was assessed using saccharide excretion assay. Rectal sensitivity was assessed using a barostat before and after small bowel lipid infusion; symptoms were assessed throughout. Next, an extended upper endoscopy with probe-based confocal laser endomicroscopy (pCLE) was performed with changes induced by lipids. Duodenal and jejunal mucosal biopsies were obtained for transcriptomics.

RESULTS

Following lipid infusion, a higher proportion of HV than IBS patients reported no pain, no nausea, no fullness and no urgency (P < 0.05 for all). In a model adjusted for sex and anxiety, IBS-C and IBS-D patients had lower thresholds for first rectal sensation (P = 0.0007) and pain (P = 0.004) than HV. In vivo small intestinal permeability and mean pCLE scores were similar between IBS patients and HV. Post-lipid, pCLE scores were higher than pre-lipid but were not different between groups. Baseline duodenal transient receptor potential vanilloid (TRPV) 1 and 3 expression was increased in IBS-D, and TRPV3 in IBS-C. Duodenal TRPV1 expression correlated with abdominal pain (r = 0.51, FDR = 0.01), and inversely with first rectal sensation (r = -0.48, FDR = 0.01) and pain (r = -0.41, FDR = 0.02) thresholds.

CONCLUSION

Lipid infusion elicits a greater symptom response in IBS patients than HV, which is associated with small intestinal expression of TRPV channels. TRPV-mediated small intestinal chemosensitivity may mediate post-meal symptoms in IBS.

Colonic expression of Ace2, the SARS-CoV-2 entry receptor, is suppressed by commensal human microbiota

Infection with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is responsible for the COVID-19 pandemic. Angiotensin-converting enzyme 2 (Ace2) is expressed in the gastrointestinal (GI) tract and a receptor for SARS-CoV-2, making the GI tract a potential infection site. This study investigated the effects of commensal intestinal microbiota on colonic Ace2 expression using a humanized mouse model. We found that colonic Ace2 expression decreased significantly upon microbial colonization. Humanization with healthy volunteer or dysbiotic microbiota from irritable bowel syndrome (IBS) patients resulted in similar Ace2 expression. Despite the differences in microbiota, no associations between α-diversity, β-diversity or individual taxa, and Ace2 were noted post-humanization. These results highlight that commensal microbiota play a key role in regulating intestinal Ace2 expression and the need to further examine the underlying mechanisms of this regulation.

Characteristics and Risk Factors of Post-Infection Irritable Bowel Syndrome After Campylobacter Enteritis

BACKGROUND & AIMS

Campylobacter is the leading cause of bacterial gastroenteritis in the United States. We investigated the prevalence of postinfection irritable bowel syndrome (PI-IBS) in a cohort with culture-confirmed Campylobacter cases; risk factors for PI-IBS based on clinical factors; and shifts in IBS patterns postinfection in patients with pre-existing IBS.

METHODS

The Minnesota Department of Health collects data on symptoms and exposures upon notification of Campylobacter cases. From 2011 through 2019, we sent surveys (the Rome III and IBS symptom severity surveys) to 3586 patients 6 to 9 months after Campylobacter infection. The prevalence of PI-IBS was estimated and risk factors were assessed using multivariable logistic regression.

RESULTS

There were 1667 responders to the survey, 249 of whom had pre-existing IBS. Of the 1418 responders without pre-existing IBS, 301 (21%) subsequently developed IBS. Most of these individuals had IBS-mixed (54%), followed by IBS-diarrhea (38%), and IBS-constipation (6%). The mean IBS symptom severity score was 218 (indicating moderate severity). Female sex, younger age, bloody stools, abdominal cramps, and hospitalization during acute enteritis were associated with increased risk, whereas fever was protective for the development of PI-IBS. Antibiotic use and exposure patterns were similar between PI-IBS and control groups. Among patients with IBS-mixed or IBS-diarrhea before infection, 78% retained their subtypes after infection. In contrast, only 50% of patients with IBS-constipation retained that subtype after infection, whereas 40% transitioned to IBS-mixed. Of patients with pre-existing IBS, 38% had increased frequency of abdominal pain after Campylobacter infection.

CONCLUSIONS

In a cohort of patients with Campylobacter infection in Minnesota, 21% developed PI-IBS; most cases reported mixed IBS or diarrhea of moderate severity. Demographic and clinical factors during acute enterocolitis are associated with PI-IBS development. Campylobacter infection also can result in a switch of a pre-existing IBS phenotype.

Campylobacter jejuni genotypes are associated with post-infection irritable bowel syndrome in humans

Campylobacter enterocolitis may lead to post-infection irritable bowel syndrome (PI-IBS) and while some C. jejuni strains are more likely than others to cause human disease, genomic and virulence characteristics promoting PI-IBS development remain uncharacterized. We combined pangenome-wide association studies and phenotypic assays to compare C. jejuni isolates from patients who developed PI-IBS with those who did not. We show that variation in bacterial stress response (Cj0145_phoX), adhesion protein (Cj0628_CapA), and core biosynthetic pathway genes (biotin: Cj0308_bioD; purine: Cj0514_purQ; isoprenoid: Cj0894c_ispH) were associated with PI-IBS development. In vitro assays demonstrated greater adhesion, invasion, IL-8 and TNFα secretion on colonocytes with PI-IBS compared to PI-no-IBS strains. A risk-score for PI-IBS development was generated using 22 genomic markers, four of which were from Cj1631c, a putative heme oxidase gene linked to virulence. Our finding that specific Campylobacter genotypes confer greater in vitro virulence and increased risk of PI-IBS has potential to improve understanding of the complex host-pathogen interactions underlying this condition.

Stephanie Peters, Ben Pascoe, et al. use whole-genome sequencing and phenotypic analysis of clinical strains from patients to identify potential genetic factors involved in irritable bowel syndrome resulting from Campylobacter jejuni infection. Their data suggest that genes involved in the bacterial stress response and biosynthetic pathways may contribute toward irritable bowel syndrome, providing further insight into links between Campylobacter genotypes and risk of disease.

Factors that contribute to the impairment of quality of life in gastroparesis

BACKGROUND

Understanding factors that impair quality of life (QOL) in gastroparesis is important for clinical management.

AIMS

(a) Determine QOL in patients with gastroparesis; (b) Determine factors that impair QOL.

METHODS

Gastroparetic patientsAQ6 underwent history and questionnaires assessing symptoms (PAGI-SYM and Rome III), QOL (SF-36v2 and PAGI-QOL), depression (Beck Depression Inventory [BDI]), and anxiety (State Trait Anxiety InventoryAQ7).

KEY RESULTS

715 gastroparesis patients (256 diabetic (DG), 459 idiopathic (IG)) were evaluated. SF-36 physical component (PC) score averaged 33.3 ± 10.5; 41% had impaired score <30. SF-36 PC scores were similar between diabetic and idiopathic gastroparesis. Impaired SF-36 PC associated with increased nausea/vomiting and upper abdominal pain subscores, acute onset of symptoms, higher number of comorbidities, use of narcotic pain medications, and irritable bowel syndrome (IBS). SF-36 mental component (MC) score averaged 38.9 ± 13.0; 26% had impaired score <30. Poor SF-36 MC associated with diabetic etiology, higher Beck depression inventory, and state anxiety scores. PAGI-QOL score averaged 2.6 ± 1.1; 50% had a score of <2.6. Low PAGI-QOL associated with higher fullness, bloating, and upper abdominal pain subscores, more depression and Trait anxiety, smoking cigarettes, need for nutritional support, progressively worsening symptoms and periodic exacerbations.

CONCLUSIONS & INFERENCES

Multiple measures show poor QOL present in gastroparesis. Several areas impacted on reduced QOL: (a) Symptoms of nausea, vomiting, and abdominal pain, as well as IBS; (b) Etiology and acute onset and progressively worsening symptoms; (c) Comorbidities and psychological factors such as anxiety and depression; (d) Patient-related factors such as smoking. Targeting the modifiable factors may improve patient outcomes in gastroparesis.

Post-infection Irritable Bowel Syndrome

Epidemiologic data support that acute gastrointestinal infection is one of the strongest risk factors for development of irritable bowel syndrome (IBS). Risk of post-infection IBS (PI-IBS) seems to be greater with bacterial and protozoal than viral enterocolitis. Younger individuals, women, and those with severe enterocolitis are more likely to develop PI-IBS. Disease mechanisms in animal models and humans involve chronic perturbation of intestinal microbiome, epithelial and neuronal remodeling, and immune activation. These mechanisms can lead to luminal (increased proteolytic activity, altered bile acid composition) and physiologic (increased permeability, transit changes, and visceral hypersensitivity) alterations that can mediate PI-IBS symptoms.

Post coronavirus disease mucormycosis: a deadly addition to the pandemic spectrum

OBJECTIVE

To study the possible association between invasive fungal sinusitis (mucormycosis) and coronavirus disease.

METHODS

A prospective observational study was conducted at a tertiary care centre over four months, involving all patients with mucormycosis of the paranasal sinuses suffering from or having a history of coronavirus disease infection.

RESULTS

Twenty-three patients presented with mucormycosis, all had an association with coronavirus disease 2019. The ethmoids (100 per cent) were the most common sinuses affected. Intra-orbital extension was seen in 43.47 per cent of cases, while intracranial extension was only seen in 8.69 per cent. Diabetes mellitus was present in 21 of 23 cases, and was uncontrolled in 12 cases. All patients had a history of steroid use during their coronavirus treatment.

CONCLUSION

New manifestations of coronavirus disease 2019 are appearing over time. The association between coronavirus and mucormycosis of the paranasal sinuses must be given serious consideration. Uncontrolled diabetes and over-zealous use of steroids are two main factors aggravating the illness, and both of these must be properly checked.

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 barrier dysfunction in irritable bowel syndrome: a systematic review

BACKGROUND AND AIM

Irritable bowel syndrome (IBS) is a complex and heterogeneous disorder. Sensory, motor and barrier dysfunctions are the key physiological endophenotypes of IBS. Our aim is to review studies evaluating barrier dysfunction in adults and children with IBS, as well as to link those changes with IBS symptomatology and quality of life.

METHODS

A comprehensive and systematic review of multiple databases was performed up to March 2020 to identify studies comparing intestinal permeability in IBS patients with healthy controls. Both in vivo and in vitro studies were considered.

RESULTS

We identified 66 studies, of which 27 used intestinal probes to quantify barrier function. The prevalence of barrier dysfunction differed between PI-IBS (17-50%), IBS-D (37-62%) and IBS-C (4-25%). At a group level, permeability was increased compared with healthy controls in IBS-D (9/13 studies) and PI-IBS (4/4 studies), but only a minority of IBS-C (2/7 studies) and not in the only IBS-M study. All four studies in children with IBS demonstrated loss of barrier function. A heterogeneous set of tight junction genes were found to be altered in small and large intestines of adults with IBS, but these have not been evaluated in children. Positive associations were identified between barrier dysfunction and bowel disturbances (6/9 studies), abdominal pain (9/13 studies), overall symptom severity (1/6 studies), depression and anxiety (1/1 study) and quality of life (1/4 studies). Fecal slurry or supernatants of IBS patients were found to induce barrier disruption in animal models (5/6 studies).

CONCLUSIONS

Barrier dysfunction is present in a significant proportion of adult and all pediatric IBS studies, especially in the IBS-D and PI-IBS subtype. The majority of studies indicated a positive association between loss of barrier function and symptoms such as abdominal pain and changes in the bowel function.

Body weight in patients with idiopathic gastroparesis

BACKGROUND

The classic clinical picture of gastroparesis is a symptomatic patient losing weight. In addition, a number of patients with delayed gastric emptying are obese and/or gaining weight. Our aim was to investigate the factors impacting body weight in patients with idiopathic gastroparesis.

METHODS

In patients with idiopathic gastroparesis, detailed history and weight were acquired at enrollment and after 48 weeks. Questionnaires assessed symptoms, food intake, physical activity, and quality of life. Patients underwent laboratory testing, gastric emptying scintigraphy, and water load testing.

RESULTS

Of 138 patients with idiopathic gastroparesis, 10% were underweight (BMI < 18.5), 39% were normal weight (BMI 18.5-25), 20% were overweight with BMI 25 to 30 kg/m² , and 29% were obese with BMI > 30 kg/m² . Body weight at enrollment was positively associated with oral caloric consumption (P < .001), following a gastroparesis diet (P = .04), nutrition consultation (P = .001), upper abdominal pain (P = .01); and negatively associated with energy expenditure (P = .05), alcohol use (P = .003) and severity of bloating (P < .001). When followed over 48 weeks, 53% patients stayed stable (within 5% of baseline weight), 30% gained, and 17% lost weight. Weight gain over 48 weeks was positively associated with oral caloric consumption (P = .003) and constipation severity (P = .005) at enrollment, and negatively associated with lower abdominal pain severity (P = .007) at enrollment, and associated with improvement in inability to finish meal score (P < .001) at 48 weeks.

CONCLUSIONS

In this series of patients with idiopathic gastroparesis, 10% were underweight whereas 29% were obese. Over 48 weeks, 30% of patients increased their body weight ≥ 5%. Diet, activity, and symptoms are important factors associated with body weight in patients with idiopathic gastroparesis.

Role of gut microbiota in regulating gastrointestinal dysfunction and motor symptoms in a mouse model of Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized primarily by motor and non-motor gastrointestinal (GI) deficits. GI symptoms' including compromised intestinal barrier function often accompanies altered gut microbiota composition and motor deficits in PD. Therefore, in this study, we set to investigate the role of gut microbiota and epithelial barrier dysfunction on motor symptom generation using a rotenone-induced mouse model of PD. We found that while six weeks of 10 mg/kg of chronic rotenone administration by oral gavage resulted in loss of tyrosine hydroxylase (TH) neurons in both germ-free (GF) and conventionally raised (CR) mice, the decrease in motor strength and coordination was observed only in CR mice. Chronic rotenone treatment did not disrupt intestinal permeability in GF mice but resulted in a significant change in gut microbiota composition and an increase in intestinal permeability in CR mice. These results highlight the potential role of gut microbiota in regulating barrier dysfunction and motor deficits in PD.

Longitudinal Multi-omics Reveals Subset-Specific Mechanisms Underlying Irritable Bowel Syndrome

The gut microbiome has been implicated in multiple human chronic gastrointestinal (GI) disorders. Determining its mechanistic role in disease has been difficult due to apparent disconnects between animal and human studies and lack of an integrated multi-omics view of disease-specific physiological changes. We integrated longitudinal multi-omics data from the gut microbiome, metabolome, host epigenome, and transcriptome in the context of irritable bowel syndrome (IBS) host physiology. We identified IBS subtype-specific and symptom-related variation in microbial composition and function. A subset of identified changes in microbial metabolites correspond to host physiological mechanisms that are relevant to IBS. By integrating multiple data layers, we identified purine metabolism as a novel host-microbial metabolic pathway in IBS with translational potential. Our study highlights the importance of longitudinal sampling and integrating complementary multi-omics data to identify functional mechanisms that can serve as therapeutic targets in a comprehensive treatment strategy for chronic GI diseases. VIDEO ABSTRACT.

Gastric Biopsies in Gastroparesis: Insights into Gastric Neuromuscular Disorders to Aid Treatment

The cellular and molecular understanding of human gastroparesis has markedly improved due to studies on full-thickness gastric biopsies. A decrease in the number of interstitial cells of Cajal (ICC) and functional changes in ICC constitutes the hallmark cellular feature of gastroparesis. More recently, in animal models, macrophages have also been identified to play a central role in development of delayed gastric emptying. Activation of macrophages leads to loss of ICC. In human gastroparesis, loss of anti-inflammatory macrophages in gastric muscle has been shown. Deeper molecular characterization using transcriptomics and proteomics has identified macrophage-based immune dysregulation in human gastroparesis.

New and alternative strategies for the prevention, control, and treatment of antibiotic-resistant Campylobacter

Campylobacter is an enteric pathogen and a leading bacterial cause of diarrhea worldwide. It is widely distributed in food animal species and is transmitted to humans primarily through the foodborne route. While generally causing self-limited diarrhea in humans, Campylobacter may induce severe or systemic infections in immunocompromised or young/elderly patients, which often requires antibiotic therapy with the first-line antibiotics including fluoroquinolones and macrolides. Over the past decades, Campylobacter has acquired resistance to these clinically significant antibiotics, compromising the effectiveness of antibiotic treatments. To address this concern, many studies have been conducted to advance novel and alternative measures to control antibiotic-resistant Campylobacter in animal reservoirs and in the human host. Although some of these undertakings have yielded promising results, efficacious and reliable alternative approaches are yet to be developed. In this review article, we will describe Campylobacter-associated disease spectrums and current treatment options, discuss the state of antibiotic resistance and alternative therapies, and provide an evaluation of various approaches that are being developed to control Campylobacter infections in animal reservoirs and the human host.

Duodenal mucosal secretory disturbances in functional dyspepsia

BACKGROUND

There is increased recognition of duodenal disturbances (inflammation, altered mucosal protein expression, and chemosensitivity) in functional dyspepsia (FD). Besides sensorimotor functions, enteric submucosal neurons also regulate epithelial ion transport. We hypothesized that duodenal mucosal ion transport and expression of associated genes are altered in FD.

METHODS

Duodenal mucosal ion transport (basal and acetylcholine- and glucose-evoked changes in short-circuit current [Isc]) and expression of associated genes and regulatory miRNAs were evaluated in 40 FD patients and 24 healthy controls.

RESULTS

Basal Isc (FD: 88.2 [52.6] μA/cm² vs healthy: 20.3 [50.2] μA/cm² ; P ≤ .0001), acetylcholine-evoked Isc (FD: Emax 50.4 [35.8] μA/cm² vs healthy: 16.6 [15] μA/cm² ; P ≤ .001), and glucose-evoked Isc responses (FD: E_max 69.8 [42.1] μA/cm² vs healthy: 40.3 [24.6] μA/cm² ; P = .02) were greater in FD than in controls. The Emax for glucose was greater in FD patients on selective serotonin reuptake inhibitors. In FD, the mRNA expression of SLC4A7 and SLC4A4, which transport bicarbonate into cells at the basolateral surface, and the apical anion exchanger SLC26A3 were reduced (false discovery rate <0.05), the serotonin receptor HTR4 was increased, and the serotonin transporter SLC6A4 was decreased. Selected miRNAs (hsa-miR-590-3p, hsa-miR-32-5p) that target genes associated with ionic transport were upregulated in FD.

CONCLUSIONS

Compared to controls, FD patients had greater baseline and agonist-evoked duodenal mucosal secretory responses. These findings may be explained by reduced gene expression, which would be anticipated to reduce luminal bicarbonate secretion. The upregulated miRNAs may partly explain the downregulation of these genes in FD.

Autonomic function in gastroparesis and chronic unexplained nausea and vomiting: Relationship with etiology, gastric emptying, and symptom severity

BACKGROUND

Autonomic dysfunction can be present in patients with idiopathic and diabetic gastroparesis. The role of autonomic dysfunction relating to gastric emptying and upper gastrointestinal symptoms in patients with gastroparesis and chronic unexplained nausea and vomiting (CUNV) remains unclear. The aim of our study is to evaluate autonomic function in patients with gastroparesis and CUNV with respect to etiology, gastric emptying and symptom severity.

METHODS

We studied 242 patients with chronic gastroparetic symptoms recruited at eight centers. All patients had a gastric emptying scintigraphy within 6 months of the study. Symptom severity was assessed using the gastroparesis cardinal symptom index. Autonomic function testing was performed at baseline enrollment using the ANX 3.0 autonomic monitoring system which measures heart rate variability and respiratory activity measurements.

KEY RESULTS

Low sympathetic response to challenge (Valsalva or standing) was the most common abnormality seen impacting 89% diabetic and 74% idiopathic patients. Diabetics compared to idiopathics, exhibited greater global hypofunction with sympathetic (OR = 4.7, 95% CI 2.2-10.3; P < .001) and parasympathetic (OR = 7.2, 95% CI 3.4-15.0; P < .001) dysfunction. Patients with delayed gastric emptying were more likely to have paradoxic parasympathetic excessive during sympathetic challenge [(Valsalva or standing) 40% vs. 26%, P = .05]. Patients with more severe symptoms exhibited greater parasympathetic dysfunction compared to those with mild-moderate symptoms: resting sympathovagal balance [LFa/RFa 1.8 (1.0-3.1) vs. 1.2 (0.6-2.3), P = .006)] and standing parasympathetic activity [0.4 (0.1-0.8) vs. 0.6 (0.2-1.7); P = .03].

CONCLUSIONS

Autonomic dysfunction was common in patients with gastroparesis and CUNV. Parasympathetic dysfunction was associated with delayed gastric emptying and more severe upper gastrointestinal symptoms. Conversely, sympathetic hypofunction was associated with milder symptoms.

INFERENCES

Gastroparesis and CUNV may be a manifestation of GI autonomic dysfunction or imbalance, such that sympathetic dysfunction occurs early on in the manifestation of chronic upper GI symptoms, while parasympathetic dysfunction results in more severe symptoms and delayed gastric emptying.

Serine proteases as luminal mediators of intestinal barrier dysfunction and symptom severity in IBS

OBJECTIVE

The intestinal lumen contains several proteases. Our aim was to determine the role of faecal proteases in mediating barrier dysfunction and symptoms in IBS.

DESIGN

39 patients with IBS and 25 healthy volunteers completed questionnaires, assessments of in vivo permeability, ex vivo colonic barrier function in Ussing chambers, tight junction (TJ) proteins, ultrastructural morphology and 16 s sequencing of faecal microbiota rRNA. A casein-based assay was used to measure proteolytic activity (PA) in faecal supernatants (FSNs). Colonic barrier function was determined in mice (ex-germ free) humanised with microbial communities associated with different human PA states.

RESULTS

Patients with IBS had higher faecal PA than healthy volunteers. 8/20 postinfection IBS (PI-IBS) and 3/19 constipation- predominant IBS had high PA (>95th percentile). High-PA patients had more and looser bowel movements, greater symptom severity and higher in vivo and ex vivo colonic permeability. High-PA FSNs increased paracellular permeability, decreased occludin and increased phosphorylated myosin light chain (pMLC) expression. Serine but not cysteine protease inhibitor significantly blocked high-PA FSN effects on barrier. The effects on barrier were diminished by pharmacological or siRNA inhibition of protease activated receptor-2 (PAR-2). Patients with high-PA IBS had lower occludin expression, wider TJs on biopsies and reduced microbial diversity than patients with low PA. Mice humanised with high-PA IBS microbiota had greater in vivo permeability than those with low-PA microbiota.

CONCLUSION

A subset of patients with IBS, especially in PI-IBS, has substantially high faecal PA, greater symptoms, impaired barrier and reduced microbial diversity. Commensal microbiota affects luminal PA that can influence host barrier function.

Satiety testing in diabetic gastroparesis: Effects of insulin pump therapy with continuous glucose monitoring on upper gastrointestinal symptoms and gastric myoelectrical activity

BACKGROUND

Symptoms induced by caloric or non-caloric satiety test meals and gastric myoelectrical activity (GMA) have not been studied in patients with diabetic gastroparesis (DGP) before and after intense glucose management.

AIMS

We determined the effects of continuous subcutaneous insulin infusion (CSII) with continuous glucose monitoring (CGM) on GI symptoms, volume consumed, and GMA induced by the caloric meal satiety test (CMST) and water load satiety test (WLST) in DGP.

METHODS

Forty-five patients with DGP underwent CMST and WLST at baseline and 24 weeks after CSII with CGM. Subjects ingested the test meals until they were completely full. Visual analog scales were used to quantify pre- and postmeal symptoms, and GMA was recorded with cutaneous electrodes and analyzed visually and by computer. KEY RESULTS: At baseline and 24-week visits, nausea, bloating, abdominal discomfort, and fullness were immediately increased after CMST and WLST (Ps < 0.01). The meal volumes ingested were significantly less than normal controls at both visits in almost one-third of the subjects. After the CMST, the percentage 3 cycle per minute GMA increased and bradygastria decreased compared with WLST (Ps < 0.05). After treatment for 24 weeks meal volumes ingested, postmeal symptoms and GMA were no different than baseline. CONCLUSIONS AND INFERENCES: (a) Satiety test meals elicited symptoms of nausea, bloating, and abdominal discomfort; (b) CMST stimulated more symptoms and changes in GMA than WLST; and (c) CSII with CGM for 24 weeks did not improve symptoms, volumes ingested, or GMA elicited by the two satiety test meals in these patients with diabetic GP. Satiety tests in diabetic gastropresis are useful to study acute postprandial symptoms and GMA, but these measures were not improved by intensive insulin therapy.