Characterization of AT2 and LIF Heterogeneity and Role of Fgf10/Fgfr2b Signaling in the Maintenance of Adult Lung Homeostasis - Importance of Reciprocal Lipofibroblast/AT2 Stem Cell Interactions

本研究将探讨脂肪成纤维细胞（LIFs）和肺泡2型细胞（AT2s）之间的相互作用。即将验证的假设是，由脂肪成纤维细胞的特定亚型（将被定义）产生的成纤维细胞生长因子10通过肺泡型上皮细胞中表达的Fgfr2b起作用。利用已经产生的和创新的基于重组酶的转基因动物进行谱系追踪，将研究LIFs和肺泡上皮细胞谱系的异质性（目的1）。Fgfr2b在衰老过程中在肺泡上皮谱系中的作用将使用Fgfr2bflox小鼠进行（细胞自主方法；目的2）。我们还将使用Fgf10flox小鼠灭活脂肪成纤维细胞中Fgf10的表达（Aim 3），并表征年轻（P81）和老年（P378）小鼠中LIF通过肺泡球维持年轻AT2细胞的能力。我们还将测试年轻和年老AT2细胞对年轻LIF的反应能力（Aim 4）。我们将最终研究重组FGF10在稳态和病变条件下（支气管肺发育不良小鼠模型）对新肺泡形成的再生作用（目的5）。我们的建议将在很大程度上依赖于吉森的人类生物库来验证小鼠上皮肺泡谱系的观察结果。我们还将利用从BPD患者肺吸出物中分离的成纤维细胞来测试不同化合物对沿LIF谱系的成纤维细胞分化的功能。总的来说，通过这项提议产生的结果将增强我们对参与肺内稳态和损伤后修复的细胞和分子机制的理解。

This proposal will investigate the interaction between Lipofibroblasts (LIFs) and Alveolar type 2 cells (AT2s). The hypothesis that will be tested is that Fibroblast growth factor 10, produced by a specific subtype of lipofibroblasts (which will be defined) acts via Fgfr2b expressed in alveolar type epithelial cells. The heterogeneity of the LIFs and the alveolar epithelial lineage will be investigated using lineage tracing with already generated and innovative recombinase-based transgenic animals (Aim 1). The role of Fgfr2b in the alveolar epithelial lineage during aging will be carried out using Fgfr2bflox mice (cell autonomous approach; Aim 2). We will also inactivate Fgf10 expression in the lipofibroblasts using Fgf10flox mice (Aim 3) and characterize the capacity of LIF in young (P81) and old (P378) mice to maintain young AT2 cells using alveolospheres. We will also test the capacity of young and old AT2 cell to respond to young LIF (Aim 4). We will finally investigate the regenerative role of recombinant FGF10 on new alveoli formation in homeostatic and diseased condition (mouse model of bronchopulmonary dysplasia) (Aim 5). Our proposal will abundantly rely on the human biobank in Giessen to validate observations made in mice for the epithelial alveolar lineage. We will also take advantage of fibroblasts isolated from the lung aspirates of BPD patients to test the function of different compounds on the differentiation of the fibroblasts along the LIF lineage. Overall, the results generated through this proposal will enhance our understanding of the cellular and molecular mechanisms involved in lung homeostasis and repair after injury.