Assessment Of The Modifiable Effect Of Tanshinone ⅡA On Radiation Pulmonary Fibrosis

Objective: To investigate the radioprotective effect of tanshinone IIA on the rat model of radiation pulmonary fibrosis using fractionated doses of radiation.Methods: Female Wistar rats were randomized into 3 groups, respectively to receive (1) sham radiation; (2) radiation alone; (3) radiation + tanshinone IIA.The radiation alone group and radiation + tanshinone IIA group were irradiated to the right hemithorax using 6 MV photons and fractionated dose of 30 Gy/10 fractions/14 days. Sodium tanshinone IIA sulfonate (15 mg/kg) was given intraperitoneally 1 hour before each fraction of irradiation in the radiation + tanshinone IIA group. Five months after irradiation, animals were sacrificed and lung tissue was processed for definitive analysis, including histopathological analysis, hydroxyproline content analysis and the expression of TGF-betal by immunohistochemistry and real-time fluorescent quantitative reverse transcriptase polymerase chain reaction (RT-PCR). Results: In the irradiated alone rats, pulmonary damage progressed to severe pneumonitis and extensive pulmonary fibrosis with marked increase of hydroxyproline and TGF-betal (on mRNA and protein level) in the lungtissue. Additionally, tanshinone IIA reduced the TGF-betal mRNA and protein production and hydroxyproline content in the irradiated rats.The histopathological comparison also revealed the protective effect of tanshinone DA.Conclusions: This study shows the protective effect of tanshinone IIA in reducing radiation-induced pulmonary fibrosis with a reduction of TGF-betal .The possible mechanism is that tanshinone IIA down-regulates the TGF-betal protein production in the lung tissue in response to radiation.