Effect Of Saikosaponin D On Pulmonary Fibrosis By Inhibiting Angiogenesis Through Ang/Tie2 Pathway

ObjectiveA pulmonary disease with persistent progression and poor prognosis is called-Idiopathic Pulmonary Fibrosis,which is shortened to IPF.Gradual decline in lung function and inevitable respiratory failure is a key feature of IPF.Currently,the underlying mechanism of IPF is still not clear,and there is no proven treatment to reverse pulmonary fibrosis.treatment to reverse pulmonary fibrosis.Bupleurum falcatum is a common natural herbal medicine in China,which has anti-bacterial,anti-tumor,antiinflammatory and other pharmacological effects.As the main active monomer,Although the role of saikosaponin?d(SSd)in pulmonary fibrosis is not completely clear,its potential to inhibit the growth of liver fibroblasts has been explored,and new discoveries have been made in the anti-pulmonary fibrosis.Therefore,this work sought to assess possible mechanistic role of SSd in the regulation of angiogenesis in PF through Ang/Tie2 pathway,amid potentially alleviating IPF.MethodRandomly,we allocated C57BL/6 mice(male)of SPF level into control,BLM,SSd and dexamethasone(DXM)groups(n=24 in each group).Afterwards,establishment of PF model was accomplished via intratracheal administration of bleomycin(BLM,5mg/kg),whiles corresponding drug intervention was given respectively.Five mice in each group were sacrificed randomly on the following days(3rd,7th,14 th and 28th)after modeling.Then MASSON and HE were used to check the degree of inflammation and fibrosis.Three fibrosis-related markers were then measured.Moreover,We use ELISA,IHC and Western Blot to examine the effect of SSd on the angiogenesis related proteins in pulmonary fibrosis through Ang/Tie2 pathway.Results(1)In MASSON staining,there were obvious alveolar structure destruction and collagen fiber deposition in the BLM group compared with the Cont group at each time point,and the fibrosis degree in the SSd and DXM groups was less than that in the BLM group at each time point,but the fibrosis degree was still aggravated with time delay.(2)In HE staining,there was obvious alveolar inflammatory infiltration in the BLM group compared with the Cont group at each time point,and the inflammation degree in the two treatment groups was less than that in the BLM group at the same period.However,no obvious difference between the SSd group and the DXM group can be seen.(3)ELISA and Western Blot showed that the content of HYP,Col-I and α-SMA in the pulmonary tissue homogenate of BLM group showed an increasing trend from day 3 to day 28.Compared with BLM group,the contents of above indexes showed a sharp decline in SSd group and DXM group at each period,and the otherness has statistical significance(p<0.05).(4)By ELISA,Western Blot and IHC,the contents of Ang-1,Ang-2 and Tie2 in lung tissue of BLM group were significantly increased at the 3rd,7th,14 th and 28 th days compared to the blank one(P < 0.01).The contents of three angiogenesis related indexes in SSd group were significantly decreased(P<0.05).And no marked difference can be found between the two treatment groups(P>0.05).conclusionThe results revealed that SSd could decrease the content of Ang-1,Ang-2 and Tie2 in the Ang/Tie2 pathway.Moreover,SSd may alleviate lung inflammation and PF that caused by BLM in mice by inhibiting angiogenesis.