Effects of synbiotic supplementation on regulatory T cells' response in patients with axial spondyloarthritis: a randomized double-masked placebo-controlled trial.

This study was conducted on samples from patients enrolled in a randomized double-masked placebo-controlled trial on the effect of synbiotic supplementation on the IL-17/IL-23 pathway and disease activity in patients with axial spondyloarthritis (axSpA) to investigate the effects of synbiotic supplementation on regulatory T (Treg) cells' response in these patients. Forty-eight axSpA patients were randomized to take one synbiotic capsule or placebo daily for 12 weeks. Treg cell proportion, gene expression of forkhead box protein P3 (Foxp3), microRNA (miRNA)-25, miRNA-106b, miRNA-146a, interleukin (IL)-10, and transforming growth factor (TGF)-β as well as serum IL-10 and TGF-β levels were assessed before and after the trial. Thirty-eight patients (19 in each group) completed the trial. The proportion of Treg cells ( P < 0.001), the gene expression of FoxP3 ( P < 0.001), IL-10 ( P = 0.001), TGF-β ( P < 0.001), and miRNA-146a ( P < 0.001) and serum IL-10 ( P = 0.003) and TGF-β ( P = 0.002) levels significantly increased compared to the baseline in the synbiotic group. Additionally, a significant reduction in the gene expression of miRNA-25 ( P < 0.001) and miRNA-106b ( P < 0.001) was observed in the synbiotic group. Significant between-group differences were observed in the proportion of Treg cells ( P = 0.024) and the gene expression of FoxP3 ( P = 0.010), IL-10 ( P = 0.002), TGF-β ( P = 0.016), miRNA-25 ( P = 0.008), miRNA-106b ( P = 0.001), and miRNA-146a ( P = 0.010). Differences in the serum levels of IL-10 and TGF-β between the groups were not significant. As a conclusion, synbiotic supplementation could modulate Treg cells' response in axSpA patients and thus can be promising as an adjunctive therapy. Additional investigations would help in further clarifying the subject.