알레르기성 폐 염증에서 STAT3를 통한 제2형 보조 T세포와 여포 보조 T세포 반응의 조절

학위논문 (석사)-- 서울대학교 융합과학기술대학원 : 분자의학및바이오제약학과, 2016. 8. 강창율.Understanding the developmental mechanisms of adoptive immunity against intranasal antigens is essential for the development of therapeutic approaches against air-borne pathogens as well as allergen-induced pulmonary inflammation. Allergic lung inflammation entails both humoral immunity and cell-mediated type 2 responses. T helper 2 (Th2) cells trigger the activation of IgE producing B cells, mast cells and eosinophils. Follicular helper T (Tfh) cells expressing CXCR5 are required for humoral immunity by producing IL-21 and ICOS costimulation to activated B cells. It has been established that signal transducer and activator of transcription 3 (STAT3) plays essential roles during the differentiation of the T helper 17 (Th17) cells from naïve helper T cells. However, its role on Th2 responses to allergens remains incompletely understood. By employing T cell-specific STAT3 deficient mice, we demonstrated that STAT3 in T cells plays diverse role on Th2 cells depending on their locations in animal models of allergic asthma. In mediastinal lymph nodes (mLNs), STAT3-deficient T cells produced significantly reduced levels of Th2 cytokines. The frequencies of Th2 cells among CD4+ T cells in the lung were comparable between STAT3-suficient and STAT3-deficient T cells. By contrast, STAT3-deficient T cells in the airway exhibited significantly enhanced production of Th2 cell cytokines compared to STAT3-sufficient T cells. STAT3 signal in T cells is known to mediate the generation of Tfh cells as well as Th17 cells. We found that administration of STAT3 inhibitor STA-21 suppressed the generation of Tfh cells and germinal center B cells in the mLNs against intranasal proteinase antigens. Compared with wild-type OT-II T cells, STAT3-deficient OT-II T cells transferred into recipients lacking T cells not only showed significantly reduced frequency Tfh cells, but also induced diminished IgG as well as IgE antibody production specific for the intranasal allergens. Co-transfer study of wild-type OT-II and STAT3-deficient OT-II T cells revealed that the latter failed to differentiate into Tfh cells. These findings demonstrate the dynamic and opposing roles of STAT3 during the development of Th2 cells from mLNs to the airway and requirement of STAT3 for the generation of Tfh cells to intranasal antigen in the mLNsthus, these results propose the need of careful consideration on STAT3-targeting approaches for the treatment of lung diseases.Introduction 8 Materials and Methods 11 Mice 11 Allergen-induced lung inflammation 11 Isolation of lymphoid cells from the lungs 12 Analysis of bronchoalveolar lavage (BAL) fluid 12 Flow cytometry 13 T cell differentiation in vitro 14 ELISA 14 Quantitative real-time RT-PCR 15 Adoptive transfer studies 16 Statistics 17 Results 18 Reduced expression of type 2 cytokines in STAT3-deficient T cells stimulated under Th2 cell differentiation condition 18 Decreased Th2 cell responses in STAT3-deficient T cells in the mediastinal lymph nodes upon intranasal allergens 18 Normal Th2 cell responses in STAT3-deficient T cells in the lung 19 Enhanced Th2 cell responses in STAT3-deficient T cells in the bronchoalveolar lavage 20 Cell-intrinsic role of STAT3 on pulmonary Th2 cells 21 Kinetic analysis of Tfh cell and germinal center B cell responses against intranasal allergens 22 Effects of TGF-β blockade on pulmonary Tfh cell responses against intranasal allergens 22 A STAT3 inhibitor STA-21 dampens pulmonary Tfh cell responses 23 Ablation of STAT3 in T cells blocks pulmonary Tfh cell responses and germinal center reactions 24 T cell intrinsic STAT3 is required for the differentiation of pulmonary Tfh cells in vivo 25 Discussion 38 References 41 국문 초록 45Maste