Role of leptin in allergic rhinitis during sublingual immunotherapy

Objective Increasing evidence suggests that leptin is upregulated during allergic reactions in the airway and related to the severity of disease in allergic rhinitis (AR). In this study, we aimed to investigate the expression of leptin during sublingual immunotherapy (SLIT) in AR patients. Methods Forty AR patients without obesity were recruited in this study. Twenty patients received house dust mite (HDM) allergen extract for SLIT and twenty patients received placebo randomly. Protein expression of leptin in serum and nasal lavage was tested by enzyme-linked immuno sorbent assay (ELISA) 1 and 2 years after SLIT treatment, respectively. Peripheral blood mononuclear cells (PBMCs) and human nasal epithelial cell were prepared and stimulated by recombinant leptin after 24 months’ SLIT treatment and the induction of Th2 cytokines (IL-4/IL-5/IL-13) were detected by ELISA. Results SLIT treatment decreased the expression of leptin protein in serum and nasal lavage significantly compared with placebo group 1 and 2 years after SLIT treatment. Nasal leptin level was correlated to decreased Th2 response (IL-4/IL-5/IL-13) and enhanced Treg (IL-10/TGF-beat) response after 2 years’ SLIT. We also found that SLIT decreased the ability of leptin in promoting Th2 cytokines expression by PBMCs and human nasal epithelial cell after 2 years’ SLIT treatment. Conclusion Changes of leptin expression in serum and nasal lavage may be correlated with Th2/Treg regulation during SLIT. Our results suggested that leptin served as an important biomarker during SLIT.