Dietary fiber is a critical determinant of pathologic ILC2 responses and intestinal inflammation

Innate lymphoid cells (ILCs) can promote host defense, chronic inflammation, or tissue protection and are regulated by cytokines and neuropeptides. However, their regulation by diet and microbiota-derived signals remains unclear. We show that an inulin fiber diet promotes Tph1-expressing inflammatory ILC2s (ILC2INFLAM) in the colon, which produce IL-5 but not tissue-protective amphiregulin (AREG), resulting in the accumulation of eosinophils. This exacerbates inflammation in a murine model of intestinal damage and inflammation in an ILC2- and eosinophil-dependent manner. Mechanistically, the inulin fiber diet elevated microbiota-derived bile acids, including cholic acid (CA) that induced expression of ILC2-activating IL-33. In IBD patients, bile acids, their receptor farnesoid X receptor (FXR), IL-33, and eosinophils were all upregulated compared with controls, implicating this diet-microbiota-ILC2 axis in human IBD pathogenesis. Together, these data reveal that dietary fiber-induced changes in microbial metabolites operate as a rheostat that governs protective versus pathologic ILC2 responses with relevance to precision nutrition for inflammatory diseases.

Relationship between gluten availability and celiac disease prevalence: A geo-epidemiologic systematic review

Celiac disease is a global disease requiring genetic susceptibility and gluten exposure to trigger immune-mediated enteropathy. The effect of the degree of gluten-containing grain availability on celiac disease prevalence is unknown. Our objective was to compare country-based gluten availability to celiac prevalence using a systematic literature review. We searched MEDLINE, Embase, Cochrane, and Scopus until May 2021. We included population-based serum screening with confirmatory testing (second serological study or small intestine biopsy) and excluded specific, high-risk, or referral populations. We determined country-specific gluten availability using the United Nations food balance for wheat, barley, and rye. Human leukocyte antigen (HLA) frequencies were obtained from allelefrequencies.net. The primary outcome was association between gluten-containing grain availability and celiac disease prevalence. Generalized linear mixed models method with Poisson's link was used for analysis. We identified 5641 articles and included 120 studies on 427 146 subjects from 41 countries. Celiac disease prevalence was 0-3.1%, median 0.75% (interquartile range 0.35, 1.22). Median wheat supply was 246 g/capita/day (interquartile range 214.8, 360.7). The risk ratio (RR) for wheat availability on celiac disease was 1.002 (95% confidence interval [CI]: 1.0001, 1.004, P = 0.036). A protective association was seen with barley, RR 0.973 (95% CI: 0.956, 0.99, P = 0.003), and rye, RR 0.989 (95% CI: 0.982, 0.997, P = 0.006). The RR for gross domestic product on celiac disease prevalence was 1.009 (95% CI: 1.005, 1.014, P < 0.001). The RR for HLA-DQ2 was 0.982 (95% CI: 0.979, 0.986, P < 0.001), and that for HLA-DQ8 was 0.957 (95% CI: 0.950, 0.964, P < 0.001). In this geo-epidemiologic study, gluten-containing grain availability showed mixed associations with celiac disease prevalence.

cloneRate: fast estimation of single-cell clonal dynamics using coalescent theory

MOTIVATION

While evolutionary approaches to medicine show promise, measuring evolution itself is difficult due to experimental constraints and the dynamic nature of body systems. In cancer evolution, continuous observation of clonal architecture is impossible, and longitudinal samples from multiple timepoints are rare. Increasingly available DNA sequencing datasets at single-cell resolution enable the reconstruction of past evolution using mutational history, allowing for a better understanding of dynamics prior to detectable disease. There is an unmet need for an accurate, fast, and easy-to-use method to quantify clone growth dynamics from these datasets.

RESULTS

We derived methods based on coalescent theory for estimating the net growth rate of clones using either reconstructed phylogenies or the number of shared mutations. We applied and validated our analytical methods for estimating the net growth rate of clones, eliminating the need for complex simulations used in previous methods. When applied to hematopoietic data, we show that our estimates may have broad applications to improve mechanistic understanding and prognostic ability. Compared to clones with a single or unknown driver mutation, clones with multiple drivers have significantly increased growth rates (median 0.94 versus 0.25 per year; P = 1.6×10-6). Further, stratifying patients with a myeloproliferative neoplasm (MPN) by the growth rate of their fittest clone shows that higher growth rates are associated with shorter time to MPN diagnosis (median 13.9 versus 26.4 months; P = 0.0026).

AVAILABILITY AND IMPLEMENTATION

We developed a publicly available R package, cloneRate, to implement our methods (Package website: https://bdj34.github.io/cloneRate/). Source code: https://github.com/bdj34/cloneRate/.

Developing a Novel Case-Based Gastroenterology/Hepatology Online Resource for Enhanced Education During and After the COVID-19 Pandemic

BACKGROUND

The COVID-19 pandemic reshaped the delivery of medical education, necessitating novel modes of instruction to facilitate distance learning. Online medical education resources provide opportunities for self-directed and asynchronous learning. GISIM is a free, open access educational website dedicated to gastroenterology (GI)/hepatology, which teaches pathophysiology and disease management, and supports clinical reasoning skill development through interactive, dynamic, case presentation-based journeys.

AIMS

(1) To describe the creation of a mobile-optimized, GI/hepatology educational resource for medical trainees, and (2) to report on trainee feedback on completing and authoring GISIM cases.

METHODS

GISIM was created on WordPress and modeled after NephSIM, an e-learning platform dedicated to Nephrology. Content was developed by internal medicine residents and GI/hepatology fellows and attendings. Cases are interactive, prompting users to select differential diagnoses and management plans, with immediate feedback provided on response. Self-reported user demographics and website feedback were collected with an embedded survey. A separate survey evaluated case authors' experiences.

RESULTS

GISIM launched in February 2021 and received 12,184 website views and 2003 unique visitors between February 1 2021 and February 28 2022. New cases are disseminated bimonthly. Sixty-one user surveys were collected, with a majority completed by fellows (38%) and residents (26%). All users found the website easy to use and most reported enhanced understanding of case topic areas. Nine author surveys were collected. Authors reported significant learning on chosen topics and improved clinical knowledge through their participation.

CONCLUSIONS

We developed a novel GI/hepatology case-based resource that enables distance learning and was perceived as a valuable educational tool by users and authors.

Self-reported gastrointestinal disorders among veterans with gulf war illness with and without posttraumatic stress disorder

BACKGROUND

Gulf War Illness (GWI) is a chronic, multi-symptom disorder affecting 25%-32% of Gulf War veterans. Veterans with GWI disproportionately suffer from gastrointestinal (GI) disorders. Given the increasing evidence supporting a gut-brain axis, we explore the relationship between post-traumatic stress disorder (PTSD), GWI, and self-reported GI disorders among GW veterans.

METHODS

Veterans from the Gulf War Era Cohort and Biorepository responded to a mail-based survey (N = 1058). They were stratified by GWI (Centers for Disease Control definition) and PTSD status. This yielded three groups: GWI-, GWI+/PTSD-, and GWI+/PTSD+. Multivariable logistic regression adjusting for demographic and military characteristics examined associations between GWI/PTSD groups and GI disorders. Results were expressed as adjusted odds ratios (aOR) with 95% confidence intervals (95% CI).

KEY RESULTS

The most frequently reported GI disorders were irritable bowel syndrome (IBS), gastroesophageal reflux disease (GERD), and colon polyps (CP). The GWI+/PTSD+ group had a higher odds of these disorders than the GWI+/PTSD- group (aOR_IBS  = 3.12, 95% CI: 1.93-5.05; aOR_GERD  = 2.04, 95% CI: 1.44-2.90; aOR_CP  = 1.85, 95% CI: 1.23-2.80), which had a higher odds of these disorders than the GWI- group (aOR_IBS  = 4.38, 95% CI: 1.55-12.36; aOR_GERD  = 2.51 95% CI: 1.63-3.87; aOR_CP  = 2.57, 95% CI: 1.53-4.32).

CONCLUSIONS & INFERENCES

GW veterans with GWI and PTSD have significantly higher odds of specific self-reported GI disorders than the other groups. Given the known bidirectional influences of the gut and brain, these veterans may benefit from a holistic healthcare approach that considers biopsychosocial contributors to the assessment and management of disease.

Pharmacologic, Dietary, and Psychological Treatments for Irritable Bowel Syndrome With Constipation: Cost Utility Analysis

Introduction. Irritable bowel syndrome (IBS) is the most common gastroenterology referral and one of the most common gastrointestinal complaints in primary care. We performed a cost-utility analysis of the most common treatments available in general practice for IBS with constipation (IBS-C), the most expensive IBS subtype. Methods. We developed a decision analytic model evaluating guideline-recommended and Food and Drug Administration-approved drugs, supplements, and dietary/psychological interventions. Model inputs were derived from "global symptom improvement" outcomes in systematic reviews of clinical trials. Costs were derived from national datasets. Analysis was performed with a 1-year time horizon from patient and payer perspectives. We analyzed a prototypical managed-care health plan with no cost-sharing to the patient. Results. From a payer perspective, global IBS treatments (including low FODMAP, cognitive behavioral therapy [CBT], neuromodulators), which are not specific to the IBS-C bowel subtype were less expensive than on-label prescription drug treatments. From a patient perspective, on-label prescription drug treatment with linaclotide was the least expensive treatment strategy. Drug prices and costs to manage untreated IBS-C were most important determinants of payer treatment preferences. Effects of treatment on missed work-days and need for repeated appointments to complete treatment were the most important determinants of treatment preference to patients. Discussion. Due mostly to prescription drug prices, neuromodulators, low FODMAP, and CBT appear cost-effective compared to on-label drug treatments from a payer perspective in cost-utility analysis. These findings may explain common treatment barriers in clinical practice.