Antibiotics alter duodenal immune populations upon gluten exposure in mice: implications for non-coeliac gluten sensitivity

A growing proportion of the non-celiac population experiences adverse symptoms to gluten. The pathogenesis of non-celiac gluten sensitivity (NCGS) is unclear, but elevated duodenal eosinophils and altered mucosa-associated microbiota (MAM) populations have been reported. Given the microbiome's role in gluten digestion and its susceptibility to antibiotics, we hypothesized that altering the microbiome with antibiotics would modify immune responses to gluten in mice. BALB/C mice consuming gluten-free chow received amoxicillin/clavulanate (5 mg/kg) or PBS-vehicle daily for 5 days. Mice were then treated with a 3-mg wheat-gluten suspension, or vehicle, on <i>days 4</i> and <i>5</i> before euthanasia on <i>day 7</i>. Duodenal immune cells were analyzed by histology and flow cytometry, whereas the duodenal MAM and fecal microbiome were characterized via 16S rRNA and shotgun metagenomic sequencing, respectively. Antibiotic treatment followed by gluten reintroduction significantly reduced <i>Staphylococcus</i> in the duodenal MAM, enriched <i>Bacteroides</i> in feces, and resulted in altered microbial carbohydrate and lipid metabolism, compared with vehicle controls. Treatment with antibiotics and gluten also increased duodenal eosinophils, which positively correlated with the genus <i>Blautia.</i> Flow cytometry revealed that sequential antibiotic and gluten treatment resulted in a greater proportion of active eosinophils and epithelial γδ T-cells, compared with vehicle control mice. This study demonstrated that modulating the microbiome with antibiotics was sufficient to alter the immune response to gluten in mice, suggesting that the microbiome may determine the capacity for gluten to induce immune responses. These findings contribute valuable insights into possible microbial mechanisms underlying NCGS, such as altered gluten metabolism or production of immunomodulatory metabolites.<b>NEW & NOTEWORTHY</b> A mouse model examined how microbial modulation affects immune responses to gluten. Antibiotic treatment followed by gluten reintroduction reduced duodenal <i>Staphylococcus</i> and altered microbial carbohydrate and lipid metabolism pathways in the fecal microbiome. Antibiotics and gluten treatment resulted in increased abundance and activation of duodenal eosinophils and elevated γδ T-cells in the duodenal epithelium. These findings highlight the role the microbiome plays in gluten-induced immune responses, providing insights into mechanisms behind non-celiac gluten sensitivity.