The Effect And Mechanism Of Total Flavonoids Of Scutellaria Baicalensis On Bleomycin-induced Pulmonary Fibrosis In Rats

Objective:To observe the effects of Total Flavonoids of Scutellaria Baicalensis on Bleomycin induced pulmonary fibrosis in an animal model of rats and explore anti-pulmonary fibrosis mechanism associated with TGF-β/Smad signaling pathway.Methods:Sixty Sprague-Dawley rats were randomly divided into five groups, include control group, model group, prednisolone group (3.34mg/kg), TFSB high-dose and low-dose group (50,25mg/kg), were12rats each group. Except control group, model group were reproduced by intratracheal injection of bleomycin (4.5mg/kg). On the second day, the animals in each curing group were intragastric administrated corresponding dose of TFSB, control group and model group were intragastric administrated the equal volume distilled water. Rats were sacrificed after28days to observe the state of the overall behavior, body weight, lung weight, lung index, forelimb grip strength, serum total antioxidant capacity (T-AOC), reduced glutathione (GSH), myeloperoxidase (MPO) levels; lung tissue hydroxyproline (HYP), total antioxidant capacity (T-AOC) and myeloperoxidase (MPO) content; treatment by ELISA for detecting of TFSB in rat IL-6and TNF-alpha levels in alveolar lavage fluid; fixed parts of the lung tissue was obtained for HE and Masson stain for histopathological examination. The effects of TFSB on the expression of transforming growth factor-β1(TGF-β1), Smad2, Smad7, a-SMA, Collagen1mRNA in lung tissue of rats with bleomycin-induce pulmonary fibrosis were assayed by Reverse Transcription PCR; The effects of TFSB on the expression of miRNA-21in lung tissue of rats with bleomycin-induce pulmonary fibrosis were assayed by Real time PCR. The effects of TFSB on the expression of transforming growth factor-β1(TGF-β1), Smad2, Smad7, a-SMA protein in lung tissue of rats with bleomycin-induce pulmonary fibrosis were assayed by Western blot.Results:After28days later, compared with control group, the bleomycin administered rats have lighter body weight, weaker forelimb grip strength, more increase lung index (P<0.05, P<0.01). Compared with model group, the intragastric administrated of TFSB rats could increase weight and forelimb grip strength significantly, decrease lung index (P<0.05, P<0.01); increase T-AOC and GSH levels (P<0.05, P<0.01), decrease MPO levels in serum (P<0.05); reduce HYP and MPO levels(P<0.05, P<0.01), enhance T-AOC in tissue (P<0.05). Detecting of IL-6and TNF-a in bronchoalveolar lavage fluid were significantly lower by ELISA (P<0.01); HE and Masson staining showed that the degree of alveolitis and pulmonary fibrosis extent were significantly reduced (P<0.01). The Reverse Transcription PCR detecting of TGF-(31, Smad2, a-SMA and Collagen1mRNA expression were significantly reduced and Smad7mRNA expression were significantly increased (P<0.05, P<0.01); Real Time PCR detecting miRNA-21expression was significantly lower (P<0.05, P<0.01); Western blot detecting of TGF-β1, Smad2, and a-SMA protein expression were significant decreased, the negative regulater Smad7expression was significant higher (P<0.05, P<0.01).Conclusion:The TFSB have a therapeutic effect on bleomycin-induced pulmonary fibrosis, which may relate to oxidative damage, inhibit inflammatory response, the formation and deposition of collagen and intervent with TGF-β1/Smad signaling pathway.