Högskolan i Skövde

Celiac disease is an autoimmune intestinal disorder affecting approximately 1% of the global population and is characterised by chronic inflammation of the small intestine following gluten exposure. Probiotic dietary supplements have been proposed as potential modulators of disease activity through enhanced gluten metabolism or alteration of the gut microenvironment. This study investigated transcriptional responses to gluten and probiotic supplementation in Drosophila melanogaster larvae as a model for examining strain-specific microbial effects on stress-related pathways. Larvae were raised on diets containing gluten alone or in combination with selected bacterial strains (Corynebacterium variabile, Corynebacterium casei, Microbacterium gubbeenense, or a blend of Lactobacillus plantarum, Lactobacillus paracasei, and Lactobacillus bulgaricus). Total RNA was extracted from homogenised soft tissue, reverse transcribed to cDNA, and analysed by PCR to assess differential expression of genes associated with immune signalling (Rel), DNA repair (mre11, XRCC1), metabolic stress (SlgA), and developmental regulation (egr). Gluten supplementation was associated with directional changes in all five genes examined, including downregulation of egr and upregulation of Rel, mre11, XRCC1, and SlgA. Although not all differences reached statistical significance, the overall pattern was consistent with modest immune engagement, activation of oxidative stress–associated repair pathways, and suppression of growth-related signalling. Probiotic supplementation modified these responses in a strain-dependent manner rather than uniformly restoring baseline expression. Comparison with human orthologues revealed both parallels and divergence, highlighting species-specific differences in immune and stress regulation. These findings suggest that gluten exposure in larval Drosophila melanogaster induces coordinated transcriptional rebalancing influenced by the presence of gut microbiota.