The Mechanism Of Sirt7 On Idiopathic Pulmonary Fibrosis

Objective: Idiopathic pulmonary fibrosis(IPF)is a chronic,progressive and fibrotic lung disease of unknown origin.The incidence rate is increasing year by year,and the prognosis is very poor,which seriously affects the quality of life of patients.IPF often occurs in the elderly.Some studies suggest that aging is one of the important risk factors of IPF.Therefore,it is particularly important to explore the pathogenesis of IPF related to aging.NAD(+)dependent deacetylase sirtuins are involved in the aging process and play an important role in fibrosis.However,the relationship between sirt7 and IPF is rarely reported at home and abroad.Studies have shown that the level of sirt7 in primary lung fibroblasts of IPF patients decreased significantly.Therefore,we speculate that sirt7 may be a new target for IPF.In addition,EMT process is closely involved in the occurrence and development of IPF.Therefore,we will observe the expression of sirt7 in the development of BLM induced pulmonary fibrosis;explore the effect of sirt7 overexpression on EMT in the development of pulmonary epithelial cell fibrosis;and further clarify whether sirt7 regulates the EMT of IPF through TGF-β1 / Smad signaling pathway.This study further revealed the molecular mechanism of IPF and provided new ideas for the prevention and treatment of IPF.Methods:1.Pulmonary fibrosis model of C57 BL / 6 mice was established by bleomycin.The mice were randomly divided into normal control group and BLM model group,including BLM treatment for 7 days,14 days and 28 days.Mice were anesthetized by intraperitoneal injection,and BLM(control group: normal saline)5mg / kg was injected into trachea.The recovery of mice was observed after 3-4 hours.The mice were killed on the 7th,14 th and 28 th day after modeling.The lung tissues of mice were collected.2.General state of mice: observe the general state of mice in each group,including weight,activity,hair gloss,mental state,eating and drinking,breathing,cyanosis.3.Pathological changes of mouse lung tissue: the right lung tissue of each group was stained with he and Masson,and the pathological changes and collagen deposition of the right lung were observed under light microscope.4.Determination of hydroxyproline(HYP)in lung tissue of mice.5.Western blot was used to detect the expression levels of sirt7,E-cadherin,α-SMA,TGF-β1,Smad3 and other proteins in the lung tissue of mice in each group.6.Beas-2b cell were cultured in complete medium in culture flask.Western blot was used to detect α-SMA to determine the optimal concentration of bleomycin.Then bleomycin with the optimal concentration was used to intervene the cells.The total protein was extracted to detect the changes of E-cadherin and α-SMA protein to determine the optimal action time.7.After the cells were digested and inoculated into 6-well plates,sirt7 plasmid was used to intervene the cells,and the total protein was extracted to detect the expression levels of E-cadherin,α-SMA,TGF-β1 and Smad3.Results:1.Compared with the normal control group,with the extension of modeling time,the diet and water intake of each BLM model group gradually became worse,the activity decreased,the hair gradually dried up,the weight decreased,and finally shortness of breath,even death.2.Compared with the normal control group,he and Masson staining results showed that the lung tissue of BLM model groups mainly showed inflammatory cell infiltration on the 7th day,collagen fiber deposition increased sharply on the 14 th day,and typical pulmonary interstitial fibrosis on the 28 th day.3.Compared with the normal control group,the expression of EMT phenotypeα-SMA increased and E-cadherin decreased in BLM model groups.And sirt7 protein expression decreased.The protein expression level of TGF-β1 / Smad3 signaling pathway increased.4.In cell experiment,the expression level of sirt7 in BLM induced lung epithelial cells decreased.Western blot results showed that sirt7 overexpression could antagonize EMT in lung epithelial cells.5.In cell experiments,overexpression of sirt7 plasmid was transfected into lung epithelial cells.After BLM induction,WB results showed that overexpression of sirt7 could antagonize TGF-β1/Smad3 signaling pathway to inhibit the occurrence of pulmonary fibrosis EMT.Conclusions:1.The expression of sirt7 decreased in BLM induced mouse pulmonary fibrosis model and cell model;2.Sirt7 is involved in the occurrence of EMT in BLM induced mouse pulmonary fibrosis model and cell model.3.Sirt7 inhibits EMT in pulmonary fibrosis induced by TGF-β1/ Smad3 signaling pathway.