Shifting from pro-inflammatory to regulatory: L. reuteri postbiotics modulate IL-17/IL-10 axis in LPS-induced HT-29...

Chronic mucosal inflammation and decreased epithelial barrier function are hallmarks of inflammatory bowel disorders (IBDs), partially caused by dysregulated cytokine signaling. Researchers are looking into probiotics and their byproducts, called postbiotics, as safer options for broad immunosuppressants like cyclosporine. This study aimed on investigating the effect of metabolites derived from Lactobacillus reuteri (ATCC 23272) on lipopolysaccharide (LPS)-induced inflammation model of HT-29 epithelial cells. Cell viability (MTT), apoptosis (Annexin V-FITC flow cytometry), cytokine expression (IL-4, IL-10, IL-17), and gene transcription (IL-8, IL-10) were evaluated after treatment of in vitro induced model comparing metabolites with cyclosporine (conventional therapy used for IBD treatment) at different time points. Using a 50% postbiotic solution increased the viability of HT-29 cells (≈ 140%, p < 0.0001) showing no cytotoxicity. In inflamed conditions, IL-17⁺ cells decreased by almost 50% (0.48-fold compared to LPS+, p < 0.0001), although IL-10⁺ cells exhibited a little increase (1.1-fold compared to LPS+, p = 0.0023). By day 5, IL-8 expression was significantly downregulated at the transcriptional level (p = 0.0121), with effects that were stronger than those of cyclosporine (p = 0.0040). In general, L. reuteri metabolites brought back apoptosis, lowered IL-8 and IL-17 levels while sustaining IL-10 increased, thus affecting immunological milieu of the epithelium toward resolution. These results were comparable or even superior to those of cyclosporine, indicative of the stability and safety of postbiotics as good candidates for IBD treatment. Additional research utilizing intestinal organoids and animal models is advised to validate their therapeutic efficacy.