Lineage Commitment of Mesenchymal Stem Cell in Allergen-induced Airway Remodeling

描述（由申请人提供）：哮喘是一种常见的慢性疾病，影响全世界许多儿童和成人。预防和治疗哮喘的主要障碍是其多种病因和我们对其生物学机制的了解不足。最近的研究改变了我们对哮喘作为一种纯粹的炎症性疾病的理解，使其成为一种炎症和结构成分同等参与的疾病。过敏原引起的早期上皮损伤允许环境过敏原进入气道组织，并可能导致慢性气道重塑的发展。因此，早期修复受损上皮的治疗可以预防病理性气道重塑，改善哮喘控制。间充质干细胞（MSCs）是成体结缔组织祖细胞，具有多系分化潜能和潜在的旁分泌免疫调节特性。在过敏原攻击后，MSCs在肺部显著增加，并可能参与气道修复/重塑。转化生长因子- 1 （TGF - 1）在募集干细胞/祖细胞进行组织修复、再生和各种器官的重塑中发挥重要作用。我们之前的研究已经提供了初步证据，表明在过敏原诱导的哮喘模型中，气道中MSCs和活跃的TGF - 1信号通路增加。此外，蟑螂提取物激发上皮的条件培养基（ECM）可诱导间充质干细胞迁移，而TGF - 1中和抗体可拮抗这种迁移。最近的体外研究表明，MSCs在TGF - 1存在下可以分化为上皮细胞。因此，该阶段将严格评估TGF - 1信号在哮喘中对MSCs的功能影响。假设：活性TGF - 1是一种过敏原激活的内源性信使，它将骨髓来源的MSCs招募到受损气道，在早期分化为上皮细胞修复受损上皮，或在慢性哮喘阶段分化为成纤维细胞/肌成纤维细胞，参与纤维化气道重塑。Aim 1提出通过实验来确定TGF - 1在哮喘中向肺募集MSCs中的作用。我们将利用我们基于气液界面(ALI)- ecm的细胞迁移系统来确定TGF - 1在MSCs迁移中的作用。我们将使用Nes-GFP小鼠进一步研究内源性nestin+MSCs在哮喘不同阶段向过敏原挑战气道募集的情况，随后使用TGF- 1中和抗体或TGF- 1受体I型（T - RI）抑制剂检测TGF- 1在MSCs募集中的作用。[目的2提出了在哮喘急性和慢性阶段通过TGF - 1信号通路在肺中募集MSC的谱系承诺/分化的实验]。我们已经建立了一个可诱导的MSC谱系追踪小鼠模型（nesting - creert2; ROSA26-EGFP），我们将使用该模型来追踪急性和慢性过敏原诱导的哮喘模型气道中募集的MSC的谱系承诺。这将为TGF- 1信号和MSCs在过敏性哮喘中的作用提供新的见解，并为新疗法提供机会。

DESCRIPTION (provided by applicant): Asthma is a common chronic illness that affects many children and adults worldwide. A major obstacle to prevention and treatment of asthma has been its diverse etiologies and our inadequate understanding of the biological mechanisms. Recent studies have changed our understanding of asthma as a purely inflammatory disease to a disease in which both inflammatory and structural components are equally involved. Allergen caused epithelial damage in early stages allows environmental allergens access to the airway tissue and may lead to the development of airway remodeling in chronic stages. Therefore, therapies that target the repair of the damaged epithelium in early stages could prevent the pathological airway remodeling and improve asthma control. Mesenchymal stem cells (MSCs) are adult connective tissue progenitor cells with multi-lineage differentiation potential and poten paracrine immunomodulatory properties. MSCs are significantly increased in the lungs after allergen challenge and may participate in airway repair/remodeling. Transforming growth factor �1 (TGF�1) plays an important role in the recruitment of stem/progenitor cells for tissue repair, regeneration, and remodeling in various organs. Our previous studies have provided initial evidence that MSCs and active TGF�1 signaling are increased in airway in an allergen induced asthma model. Furthermore, conditioned medium (ECM) from cockroach extract challenged epithelium induces the migration of MSCs, while TGF�1 neutralizing antibody antagonized this migration. Recent studies in vitro have shown that MSCs can differentiate into epithelial cells in the presence of TGF�1. The stage is thus set to critically evaluate the functional effect on MSCs of TGF�1signaling in asthma. HYPOTHESIS: Active TGF�1 is an allergen-activated endogenous messenger that recruits bone marrow-derived MSCs to the injured airways, which differentiate into epithelial cells to repair the damaged epithelium in early stages or into fibroblasts/myofibroblasts contributing to fibrotic airway remodeling in chronic stage of asthma. Aim 1 proposes experiments to determine the role of active TGF�1 in the recruitment of MSCs to the lung in asthma. We will determine the role of TGF�1 in migration of MSCs using our Air-Liquid Interface (ALI)-ECM-based cell migration system. We will further examine the recruitment of endogenous nestin+MSCs to the allergen-challenged airways during different stages of asthma using Nes-GFP mice, followed by the examination of the role of TGF�1 in the recruitment of MSCs using a TGF�1 neutralizing antibody or TGF-� receptor type I (T�RI) inhibitor. [Aim 2 proposes experiments to track the lineage commitment/differentiation of MSC recruited in lungs through TGF�1 signaling during acute and chronic stages of asthma]. We have established an inducible MSC lineage tracing mouse model (nestin-CreERT2; ROSA26-EGFP) that we will use to track the lineage commitment of recruited MSCs in airway of acute and chronic allergen-induced models of asthma. This will provide novel insights into the role of TGF-�1 signaling and MSCs in allergic asthma and offer an opportunity for novel therapies.