The Intervention Effect Of CSD Peptide On Bleomycin-induced Pulmonary Fibrosis In Mouse And The Research Of Its Related

ObjectiveTo provide the basis of treatment for pulmonary fibrosis by caveolin-1(Cav-1) as amolecular target, we established a mouse pulmonary fibrosis model induced bybleomycin (BLM), investigated the intervention effect of caveolin-1scaffoldingdomain peptide in pulomoary fibrosis and further explored the potential mechanismsof its preventive role in the formation of idiopathic pulmonary fibrosis.MethodsAccording to the random number table,18mouse were divided into3groups: normalcontrol group(Cont group), BLM model group(BLM group) and CSD peptideintervention group (CSD group), each group of which contains6mouse. The mousepulmonary fibrosis model was established by single intratracheal injection ofbleomycin (3.5mg/kg,0.05ml) in BLM group and CSD group. Cont group wasinjected with the same volume saline (0.05m1) in trachea. CSD group was treatedwith CSD peptide (0.15mM,0.1ml) by intraperitoneal injection, while BLM groupand Cont group were administered with intraperitoneal injection of normal saline (0.1ml) once daily. At the14th day after the model was established,3groups mouse weresacrificed for lung tissue. The histopathological change of the lung tissue wasdetermined to understand the degree of alveolitis and lung fibrosis. Hydroxyproline(HYP) content was observed to determine the degree of pulmonary fibrosis.Immunohistochemistry was used to detect the level of Cav-1. The expression ofCav-1, membrane phosphatase and tensin homolog deleted on chromosome ten（PTEN）, collagen1alpha1(Col1α1), alpha smooth muscle actin (α-SMA) andE-cadherin(E-cad) was detected by Werstern Blot.Results1. Histopathological examination in lung tissue.Histopathological examination showed that pulmonary fibrosis happened in mouselung tissue of BLM group. Compared with those in Cont group, alveolitis andpulmonary fibrosis value of mouse lung tissue was significantly increased in BLMgroup (P <0.01, P <0.01). Compared with those in BLM group, the value wasobviously reduced in CSD group (P <0.01, P <0.05).2. HPY content observation in lung tissue.Compared with those in Cont group, HPY content of mouse lung tissue wassignificantly increased in BLM group (P <0.01). Compared with those in BLM group,the content was decreased in CSD group (P <0.05).3. Immunohistochemistry detection in lung tissue.Compared with those in Cont group lung tissue, the expression of Cav-1wassignificantly decreased in BLM group (P <0.01). Compared with those in BLMgroup, the level was slightly increased in CSD group, but there was no significantdifference (P>0.05).4. Werstern Blot determination in lung tissue.Compared with those in Cont group lung tissue, the level of Cav-1expressed wassignificantly decreased in BLM group (P <0.01). Compared with those in BLMgroup, the expression was slightly increased in CSD group, but there was nosignificant difference (P>0.05). Compared with those in Cont group, the level ofmembrane PTEN and E-cad was significantly decreased in BLM group (P <0.05, P <0.01). Compared with those in BLM group, the expression was increased in CSDgroup (P <0.01, P <0.05). Compared with those in Cont group lung tissue, the expression of Col1α1、α-SMA was significantly increased in BLM group(P <0.01, P<0.01). Compared with those in BLM group, the level was significantly decreased inCont group (P <0.01, P <0.01).Conclusion1. The pulmonary fibrosis model of mouse was successfully made by a singleintracheal injection of BLM (3.5mg/kg).2. The intraperitoneal injection with CSD indeed inversed the pulmonary fibrosisinduced by BLM.3. CSD peptide had an interventional effect on the formation of pulmonary fibrosisand its related mechanisms may be in the following ways:(1) The CSD peptide increased the level of membrane PTEN by restoring the functionof Cav-1.(2) The rise in the expression of membrane PTEN might inhibit its downstreamsignaling pathways such as PI3K/Akt, further suppressed the epithelial-mesenchymaltransition and reduced the excessive deposition of extracellular matrix, which have aninterventional effect on the formation of pulmonary fibrosis.