# Poster Session I - Poster of Distinction I - A19 MICROBIOTA-MEDIATED IMPACT OF CHRONIC STRESS ON INTESTINAL CRYPT STEM-CELL CYCLING AND PANETH-CELL PROLIFERATION

## TL;DR

Chronic stress changes gut microbes, which affects intestinal stem cells and barrier function, with some effects linked to stress hormones.

## Contribution

The study identifies a microbiota-dependent pathway linking chronic stress to intestinal epithelial dysfunction and stem-cell changes.

## Key findings

- Chronic stress caused anxiety-like behavior and gut dysbiosis with increased Streptococcus and reduced Bifidobacterium.
- Antibiotics reduced stress-induced stem-cell marker downregulation but not Paneth-cell changes.
- Dexamethasone mimicked stress effects on stem cells and Paneth cells, while metyrapone reduced these effects.

## Abstract

Gut microbiota are key regulators of epithelial renewal and barrier defense. Chronic stress perturbs the gut–brain–microbiota axis (HPA, vagal, immune pathways), alters microbial communities, and can compromise epithelial integrity.

To determine how chronic stress–induced dysbiosis affects the small-intestinal crypt stem-cell niche and Paneth-cell function.

Six–eight-week-old mice underwent daily restraint stress (1 h/day, 7 days). Anxiety-like behavior was assessed with the dark/light transition test. Paracellular permeability was quantified in Ussing chambers. Middle-jejunum mucosa/submucosa (after muscle removal) was processed for RNA-seq; immunofluorescence probed OLFM4 (stem cells) and proliferation markers Ki-67 and p-H3. To model glucocorticoid signaling, dexamethasone (synthetic steroid) or metyrapone (11β-hydroxylation inhibitor) was administered. To test microbiota involvement, broad-spectrum antibiotics were given before and throughout stress exposure. Fecal communities were profiled by 16S rRNA analysis.

Chronic restraint stress produced anxiety-like behavior and dysbiosis, with increased Streptococcus and decreased Bifidobacterium. Barrier dysfunction was evident as increased small-intestinal epithelial permeability, accompanied by reduced villus and crypt length in the jejunum. RNA-seq demonstrated downregulation of Paneth-cell and stem-cell markers in jejunal mucosa. Immunofluorescence confirmed reduced OLFM4, Ki-67, and p-H3 within crypts. Ablation of gut microbiota with antibiotics attenuated the stress-induced downregulation of stem-cell markers but did not alter the Paneth-cell marker changes. Dexamethasone mimicked the effects of restraint stress on crypt stem cells and Paneth cells, whereas metyrapone attenuated both.

Chronic stress drives microbiota changes that accompany anxiety-like behavior and barrier dysfunction. Epithelial villus/crypt alterations occur in a microbiota-dependent manner, with glucocorticoid signaling contributing to these effects. These findings delineate a microbiota-linked pathway by which stress impairs epithelial renewal and differentiation, with implications for stress-related intestinal disorders.

McMaster Farcombe institute start-up grant for new faculty