维生素D缺乏与肺间质纤维化之间的关联和机制

Previous studies demonstrated that vitamin D supplementation inhibited pulmonary fibrosis in mice. The present study hypothesizes that vitamin D deficiency attenuates VDR-mediated suppression of pulmonary Smad2/3 signaling and epithelial mesenchymal transition in mouse lungs. To reveal the association between vitamin D deficiency and pulmonary fibrosis, the present study will compare serum 25(OH)D levels between patients with pulmonary fibrosis and controls. To establish an animal model of vitamin D deficiency, mice is fed with vitamin D deficient feed. To determine active vitamin D deficiency on pulmonary fibrosis, Cyp27b1 knockout mice will be also used. In the present study, we will analyze the effects of vitamin D deficiency on pulmonary VDR signaling, inflammatory signaling, TGF-β/Smad2/3 and epithelial mesenchymal transition during the process of pulmonary fibrosis. To explore whether VDR is involved in epithelial mesenchymal transition, the present study will investigate the effects of active vitamin D3 on TGF-β-activated Smad2/3 signaling in VDR gene silenced A549 cells. To explore the mechanism through which VDR is involved in epithelial mesenchymal transition, we will measure the effects of active vitamin D3 on the interaction between VDR and Smad2/3 in A549 cell. The present study will provide the data for elucidating the association between vitamin D deficiency and pulmonary fibrosis and its mechanism.

前期研究证实，活性维生素D3拮抗小鼠肺间质纤维化。本课题假设：维生素D缺乏导致肺上皮VDR对Smad2/3抑制作用减弱并促进上皮-间质转化和肺间质纤维化。本课题比较肺间质纤维化患者与对照人群血清25（OH）D水平，揭示维生素D缺乏与肺间质纤维化之间的关联;用维生素D缺乏饲料构建维生素D缺乏动物模型，用Cyp27b1基因敲除小鼠构建活性型维生素D3缺乏动物模型，分析维生素D缺乏对小鼠肺间质纤维化各阶段肺上皮VDR信号、炎性信号、TGF-β/Smad2/3通路和上皮-间质转化的影响；比较VDR基因沉默与否条件下活性维生素D3对人肺上皮细胞TGF-β/Smad2/3通路的抑制效应，观察活性维生素D3促进人肺上皮细胞VDR与Smad2/3间相互作用，以阐明VDR调节肺上皮TGF-β/Smad2/3信号和上皮-间质转化的机制。本课题为阐明维生素D缺乏与肺间质纤维化之间的关联和机制提供理论依据。

本课题通过比较肺间质纤维化患者与对照人群血清25（OH）D水平，揭示维生素D缺乏与肺间质纤维化之间的关联；采用维生素D缺乏饲料构建维生素D缺乏动物模型，分析维生素D缺乏对小鼠肺间质纤维化各阶段肺上皮VDR信号、炎性信号、TGF-β/Smad2/3通路和上皮-间质转化（EMT）的调控作用；比较VDR基因沉默与否条件下活性维生素D3对人肺上皮细胞TGF-β/Smad2/3通路的抑制效应，观察活性维生素D3启动人肺上皮细胞VDR与Smad2/3间相互作用，以阐明VDR调节肺上皮TGF-β/Smad2/3信号和上皮-间质转化的机制。临床病例-对照观察发现，肺间质纤维化患者血清25(OH)D水平显著低于对照人群；动物实验结果显示，维生素D缺乏促进博莱霉素所致肺间质纤维化；机制性研究发现，维生素D缺乏加重博莱霉素诱导小鼠肺TGF-β/Smad3激活和EMT。用Cyp27b1基因敲除小鼠构建活性型维生素D3缺乏动物模型，进一步分析活性型维生素D3缺乏对肺间质纤维化的促进作用。结果显示，Cyp27b1基因敲除促进博莱霉素诱导肺TGF-β/Smad3激活和EMT；进一步观察发现，Cyp27b1基因敲除加重博莱霉素所致肺间质纤维化。课题为进一步认识维生素D缺乏与呼吸系统疾病之间的关联和机制提供理论依据。