Research On The Mechanism Of Wnt/β-catenin Pathway Participating In Th17 Cell Response And Acute Lung Injury

Background and Objective:ALI,a term that has been widely used in experimental lung injury models,is categorized as a mild form of the human disorder,ARDS.ALI/ARDS are a spectrum of lung diseases characterised by acute hypoxemia and severe impairment in gas exchange and lung mechanics with a high case fatality rate and incidence.So,it is necessary to elucidate the pathogenesis of ALI in order to provide clues for clinical treatment.Pathologically ALI is characterised by an overwhelming inflammatory process leading to diffuse alveolar epithelial and vascular endothelial damage,alveolar capillary leakage,and protein rich pulmonary edema.It is generally believed that neutrophil-induced inflammatory response plays an important role in the development of ALI.Th17 cells play a potent pro-inflammatory role in the immune system by recruiting and activating neutrophils.It is confirmed that Wnt/β-catenin pathway is corelated with Th17 cells and ALI.However,whether Wnt/β-catenin pathway could regulate the differentiation and the function of Th17 cells in the development and progress of ALI is still unkown.To test this,we carried out this study to find a new target for the treatment of ALI/ARDS.Methods:1.C57BL/6 mice were used to establish the ALI animal model.Observe the pathological changes of lung tissue,inflammatory factors including neutrophils,IL-6 and TNF-α expression in BALF,and gene expression of β-catenin as the central effector of canonical Wnt signaling pathway at five points in time during the acute phase of ALI.2.To explor whether Wnt/β-catenin had pro-inflammatory effect and the potential mechanism of action of Wnt/β-catenin pathway in Th17,ALI-induced mice were treated with Wnt/β-catenin pathway activator LiCl or repressor Dkk-1.Th17 response related factors and inflammatory factors were detected.3.ALI animal model treated with Li Cl were intervented by p300 inhibitor C646.The regulation mechanism of Th17 mediated by Wnt/β-catenin pathway was examined by detecting Th17 response related factors.Results:1.In ALI mice,appearance of inflammatory lung tissue injury and increase of inflammatory cells and cytokines were observed after 6 hours.2.The gene expression of β-catenin elevated in lung tissue of ALI mice.3.Activation of Wnt/β-catenin pathway aggravated lung tissue damage,increased the proportion of neutrophils,activity of MPO and expression of inflammatory mediators in BALF.While,inhibtion of Wnt/β-catenin pathway alleviated lung tissue damage,reduced the proportion of neutrophils,activity of MPO and expression of inflammatory mediators in BALF.4.Activation of Wnt/β-catenin pathway increased the percentage of Th17 cells,up-regulated the gene expreesion of RORγt in lung tissue and elevated the concentration of IL-17 in BALF.While,inhibtion of Wnt/β-catenin pathway decreased the percentage of Th17 cells,down-regulated the gene expreesion of RORγt in lung tissue and reduced the concentration of IL-17 in BALF.5.Inhibition of p300 attenuated the enhanced gene expression of RORγt activated by Wnt/β-catenin pathway.Conclusions:1.Wnt/β-catenin pathway is important for the ALI inflammatory response.2.Wnt/β-catenin pathway promotes ALI induced by LPS through driving the Th17 differentiation.3.Wnt/β-catenin pathway induces Th17 cells differentiation by promoting the expression of RORγt through p300.