A significant decrease in the gene expression of interleukin‑17 following the administration of synbiotic in patients with allergic rhinitis who underwent immunotherapy: A placebo‑controlled clinical trial

Background: Allergic Rhinitis (AR) is the most common allergic disease worldwide. The present study, evaluated effects of synbiotic on gene expression of interferon-gamma (IFN-γ), interleukin-4 (IL-4), interleukin-10 (IL-10), interleukin-17 (IL-17), transforming growth factor beta (TGF-β), and forkhead box P3 (FoxP3) in AR patients who received concomitant immunotherapy in a placebo-controlled clinical trial. Materials and Methods: Twenty AR patients were randomized in synbiotic and placebo groups and received cluster immunotherapy for 2 months. RNA was extracted from peripheral PBMCs, then the cDNA synthesized. Subsequently, SYBR Green real-time Reverse transcription polymerase chain reaction technique was employed for studying the expression of mentioned genes. In addition, SNOT-22 and mini-Rhinoconjunctivitis Quality of Life Questionnaire questionnaires were completed by patients. Data were analyzed before and also 2 and 6 months after intervention. Results: Clinical symptoms and quality of life were improved with immunotherapy, but there was no significant difference between the placebo and synbiotic groups. Gene expression of IFN-γ, TGF-β, and FoxP3 was increased whereas the gene expression of IL-4 and IL-10 decreased, but not significant. Interestingly, the gene expression of IL-17 in the synbiotic group was significantly decreased versus placebo after 2 months (P = 0.001) and also at the end of intervention (P = 0.0001) comparing with the time zero. Conclusion: Significant reduction in the IL-17 gene expression following administration of synbiotic versus placebo shows the importance of synbiotic in control of the immunopathogenesis of AR. Further studies with more samples are recommended. In addition, evaluating the effects of synbiotic in patients who do not undergo immunotherapy is suggested to get a better conclusion.