The Intervention Effect Of Baricitinib On Bleomycin-induced Pulmonary Fibrosis In Mice

Objective: To investigate the effect of JAK inhibitor Baricitinib on idiopathic pulmonary fibrosis(IPF)and its molecular mechanism.Methods: In this study,35 C57BL/6J mice were selected and randomly divided into five groups,including blank group(Control),model group(BLM),Bar(10 mg/kg)treatment group,Bar(5 mg/kg)treatment group and Bar(2.5 mg/kg)treatment group.The model group and treatment group were established by intratracheal instillation of bleomycin(BLM)to establish a mouse pulmonary fibrosis model.The blank group was dripped with the same volume of normal saline.The induction time was 3 days,and the intervention of Baricitinib was 14 days.Body weight was measured on day 0,day 4,and day 14 of drug intervention.After the experiment,the required lung tissue samples and mouse plasma were retained,and then the experimental animal model was evaluated by observing the lung coefficient and lung morphology of the mice.The effect of Baricitinib on collagen fibers in the lungs of mice was evaluated by analyzing HE sections,MASSON staining sections and hydroxyproline(HYP)content of lung tissue.The degree of lung oxidative damage in mice was evaluated by detecting malondialdehyde(MDA)content and superoxide dismutase(SOD)content.The level of plasma inflammatory factors in mice was detected by flow cytometry to evaluate the effect of drugs on lung inflammation in mice.The expression of α-SMA,TGF-β1,pSMAD(2/3)and STAT3 signaling pathway in lung tissue of mice was detected by immunohistochemistry and Western blot.Results: On the 0 th day of modeling,there was no difference in body weight change of mice;on the 4th day of modeling,the body weight of BLM group and treatment group decreased significantly,while that of Control group increased slowly.On the 14 th day of drug intervention,the weight of the BLM group continued to decline or maintain the weight at the time of modeling,the weight of the treatment group increased to varying degrees,and the weight of the Control group continued to rise.The results of lung coefficient and lung morphology showed that the model of pulmonary fibrosis could be successfully established by intratracheal instillation of BLM,and the degree of pulmonary fibrosis in mice decreased after intervention with Baricitinib.The results of HE staining,MASSON staining and HYP content showed that Baricitinib reduced the deposition of collagen fibers in the lungs of mice.MDA and SOD content analysis showed that Baricitinib reduced the degree of lipid peroxidation in mice and reduced cell damage.The results of flow cytometry showed that Baricitinib intervention reduced the level of inflammatory factors in mice.The results of immunohistochemistry showed that the expression of α-SMA,TGF-β1 and pSMAD(2/3)was down-regulated after drug intervention.Western blot results showed that the expression of p-STAT3 and α-SMA was down-regulated in the treatment group compared with the model group.Conclusion : 1.Baricitinib can reduce the content of MDA and SOD,and reduce the degree of oxidative damage in the lungs of mice induced by BLM.2.Baricitinib can reduce the levels of plasma IL-4 and TNF-α,and reduce the degree of BLM-induced lung inflammatory injury in mice.3.Baricitinib can down-regulate the expression of α-SMA,TGF-β1,p-SMAD(2/3),reduce the content of HYP,and alleviate the degree of pulmonary fibrosis induced by BLM in mice.4.Baricitinib exerts a therapeutic effect on BLM-induced pulmonary fibrosis in mice by inhibiting STAT3 phosphorylation.