Oral Administration of Zataria multiflora Extract Decreases IL-17 Expression in Perennial Allergic Rhinitis

Background: Rhinitis, which occurs most commonly as allergic rhinitis and affects 20% of the world&rsquo;s population, is a major health care burden causing significant morbidity. Considering the high prevalence of allergic rhinitis and anti-inflammatory effects of thyme, a favorite condiment, we performed a randomized clinical trial to determine whether thyme can relieve allergic rhinitis symptoms and affect the expression of TH17- and T-regulatory cell- (Treg) related cytokines IL-17, TGF-&beta;, FOXP3, and IL-10. Methods: Thirty patients with allergic rhinitis symptoms and positive skin prick test for common aero allergens were randomly assigned to experimental or control groups. The experimental group received thyme or Zataria multiflora (ZM) extracts and the control group received placebo for two months. Expression of IL-17, TGF-b, FOXP3, and IL-10 was evaluated in all subjects by real-time PCR before and after intervention. Results: After treatment IL-17 expression was significantly less in the ZM group than in controls (p<0.05), while TGF-&beta;, FOXP3, and IL-10, expression were not significantly changed. Conclusions: Given the significant effect of thyme in reducing symptoms of allergic rhinitis and decrease IL-17 gene expression and because allergic rhinitis is a multifactorial disease, the administration of thyme extract along with conventional treatments may benefit allergic rhinitis sufferers.