The investigation of the role of IL-21 and IL-33 in the pathogenesis of allergic rhinitis

Allergic rhinitis is an inflammatory disease of nasal mucosa. Allergic rhinitis is resulted from Type I hypersensitivity reactions which are caused by allergen-derived immunoglobulin E (IgE). Allergic reactions are controlled by Th2 (T-helper cell). It was shown that many that several cytokines are involved in the pathogenesis of allergic rhinitis. Th2 cells produce cytokines such as; IL-4 (interleukin 4), IL- 5, IL -9, IL - 13, GM -CSF and (granulocyte-macrophage colony-stimulating factor). These cytokines allow IgE synthesis and the activation of cells such as mast cells and eosinophils. In this study, it was aimed to investigate some factors affecting the pathogenesis of allergic rhinitis: IgE, Ova sIgE, IL-33 and IL-21 by using a created rat model. In this study, serum samples and nasal tissue were acquired from an early confirmed study 64583101/2014/028 on March 20, 2014 named as "The Effect of Thymoquinone in Allergic Rhinitis Experimental Animal Model". The study was included two groups: the study group was consisted of animals with allergic rhinitis and adjuvant/saline (serum physiologic) treated was control group. The study was performed in Adnan Menderes University Medical Microbiology Department, IgE, OVA SIG, IL -21 and IL- 33 levels were investigated in serum samples; IL-21 and IL- 33 levels were investigated in tissue samples by Enzyme Immune Assay (EIA). It was found that tissue IL-33 level in both of allergic rhinitis (p=0,048) and corticosteroid+allergic rhinitis groups (p=0.035) were statistically higher than in control group. However there was no statistically significant difference in terms of serum IL-21 and IL-33 levels between groups. Despite finding no statistically significant difference in term of tissue IL-21 level, there was a statistically significant difference when the serum and tissue IL-21 levels were compared in allergic rhinitis group; IL-21 levels in tissue samples were higher than in serum samples. Serum IgE level of control group was found significantly higher in both allergic rhinitis group (p=0,009) and corticosteroid+allergic rhinitis group (p=0,011). This study concludes that IL-33 and IL-21 have a role in the pathogenesis of allergic rhinitis; they were synthesized in higher levels in allergic rhinitis tissue. Additionally, it was thought that IL-21 had a role in down regulation of serum IgE level. Keywords: Allergic rhinitis, Interleukin 21, Interleukin 33, IL-21, IL-33