Concomitant suppression of TH2 and TH17 cell responses in allergic asthma by targeting retinoic acid receptor-related orphan receptor ?t.

ABSTRACT: BACKGROUND:Allergic asthma is a heterogeneous chronic inflammatory disease of the airways with a massive infiltration of eosinophils or neutrophils mediated by allergen-specific TH2 and TH17 cells, respectively. Therefore successful treatment of allergic asthma will require suppression of both TH2 and TH17 cells. OBJECTIVE:We sought to investigate the role of the TH17 cell pathway in regulating TH2 cell responses in allergic asthma. METHODS:Allergic asthma was induced by intranasal challenge with proteinase allergens in C57BL/6, Il17a-/-Il17f-/-, and retinoic acid receptor-related orphan receptor ?t (ROR?t)gfp/gfp mice. A pharmacologic ROR?t inhibitor was used to evaluate its preventive and therapeutic effects in allergic asthma. Characteristics of allergic airway inflammation were analyzed by using flow cytometry, histology, quantitative real-time PCR, and ELISA. Mixed bone marrow chimeric mice, fate mapping analysis, short hairpin RNA transduction, and in vitro T-cell differentiation were used for mechanistic studies. RESULTS:Mice deficient in IL-17A and IL-17F, as well as ROR?t, exhibited a significant reduction not only in TH17 cell responses but also in TH2 cell responses in an animal model of allergic asthma. Similarly, mice treated with an ROR?t inhibitor had significantly diminished TH17 and TH2 cell responses, leading to reduced neutrophil and eosinophil numbers in the airway. ROR?t-deficient T cells were intrinsically defective in differentiating into TH2 cells and expressed increased levels of B-cell lymphoma 6 (Bcl6). Bcl6 knockdown resulted in a remarkable restoration of TH2 cell differentiation in ROR?t-deficient T cells. Blockade of ROR?t also significantly hampered the differentiation of human TH2 and TH17 cells from naive CD4+ T cells. CONCLUSION:ROR?t in T cells is required for optimal TH2 cell differentiation by suppressing Bcl6 expression; this finding suggests that targeting ROR?t might be a promising approach for the treatment of allergic asthma by concomitantly suppressing TH17 and TH2 cell responses in the airway.

SUBMITTER: Na H 

PROVIDER: S-EPMC5862762 | biostudies-literature | 2018 Jun

REPOSITORIES: biostudies-literature