Objective:To investigate the protective effect of racanisodamine on lung injury in mice exposed to irradiation.Methods:C57BL/6 mice were randomly divided into control group, racanisodamine group, 18 Gy irradiation group (model group) and racanisodamine combined with 18 Gy irradiation group (treatment group), with 5 mice in each group. The mice in the treatment group received racanisodamine (5 mg/kg) intraperitoneally 3 d before irradiation and contained the whole experiments. Then, single chest irradiation of 18 Gy X-rays was performed both in the model and treatment groups. The racanisodamine group and treatment group received racanisodamine intraperitoneally once a day until 6 weeks after irradiation. The mice were killed at 6 weeks after irradiation. The lung histopathology was observed by HE staining. Serum and bronchial alveolar lavage fluid (BALF) inflammatory cytokines such as TNF-α, IL-1β and IL-6 were determined by ELISA method. Cell senescence was detected by SA-β-Gal staining. The expressions of Nrf2, p-Nrf2 and p62 in lung tissue were performed by immunehistochemistry and Western blot assays.Results:Compared with the model group, the scores of HE staining were decreased ( t=8.66, P<0.01), the number of infiltrated inflammatory cells in BALF were decreased ( t=10.70, P<0.01), and protein concentration in BALF had lower levels ( t=6.75, P<0.01), the serum TNF-α, IL-1β and IL-6 were decreased significantly ( t=8.17, 4.58, 6.54, P<0.01), the activity of SA-β-gal was decreased, and the expressions of Nrf2, p-Nrf2 were enhanced ( t=6.42, 7.30, P<0.01), while the expression of p62 was reduced ( t=4.62, P<0.01) in the treatment group. Conclusions:Racanisodamine plays the protective effect of radiation-induced lung injury by alleviating inflammation associating with the activating of Nrf2-related pathway, which reversed radiation-induced cell senescence.

Objective:To investigate the protective effect of racanisodamine (654-2) on lung epithelial cell injury induced by X-ray in mice and unravel the underlying mechanism.Methods:Mouse alveolar epithelial cells MLE-12 were used to establish radiation-induced lung injury (RILI) model in vitro and divided into 4 groups as follows: control (no irradiation), radiation (16 Gy radiation), treatment 1 (16 Gy radiation + 2 μmol/L 654-2), treatment 2 (16 Gy radiation + 10 μmol/L 654-2), and inhibitor (16 Gy radiation + 10 μmol/L 654-2 + 2 μmol/L ML385), respectively. Cells were sampled at different time points after radiation. Cell senescence was detected with senescence-associated β-galactosidase (SA-β-Gal) staining. Cell colony-forming ability was detected to observe the recovery capability of cells after treatment. The expression levels of p21, p16, phosphorylated histone H2AX(γH2AX), nuclear factor erythroid-2 related factor 2 (Nrf2), Nrf2 Ser40 site phosphorylation (p-Nrf2), p62, heme oxygenase-1 (HO-1) and NAD(P)H quinone oxidoreductase 1 (NQO1) proteins were measured by Western blot. Cell apoptosis and the production of intracellular reactive oxygen species (ROS) were determined by flow cytometry. The expression levels of glutathione (GSH) and superoxide dismutase (SOD) were detected according to the manufectuer instructions. The expression levels of glutamate-cysteine ligase catalytic subunit (GCLC) and glutamate-cysteine ligase modifier subunit (GCLM) mRNA were determined by real time reverse transcription PCR. Measurement data were expressed as Mean ±SD. Comparison between two groups was conducted by independent sample t-test, and comparison among multiple groups was performed by one-way ANOVA. Results:Compared with the radiation group, the proportion of cells with positive staining of SA-β-Gal was significantly lower and cell senescence were alleviated in the treatment 1 and 2 groups (all P<0.001). Compared with the radiation group, the expression level of γH2AX protein was significantly down-regulated ( P=0.037), cell apoptosis rate was significantly decreased ( P=0.026), the proliferation capacity of MLE-12 was enhanced ( P=0.004), GSH ( P=0.002) and SOD ( P<0.001) activity was enhanced and ROS production was declined ( P=0.001) in the treatment 2 group. The expression levels of Nrf2 and p-Nrf2 in total protein were up-regulated over the time of 654-2 intervention. Meanwhile, the expression levels of antioxidant proteins of NQO1 and HO-1 were up-regulated and that of GCLC and GCLM mRNA was also up-regulated. There were no significant differences in the number of cells with positive staining of SA-β-Gal ( P=0.145) and ROS production ( P=0.317) between the inhibitor and radiation groups after supplement of ML385, small-molecule inhibitor of Nrf2. Conclusion:654-2 can activate the Nrf2 pathway, enhance cell antioxidant capacity and inhibit cell senescence, thereby playing a protective role on radiation- induced lung injury.