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Background: Ionizing radiation can induce bystander effects (RIBE), and Astragalus polysaccharides (APS) have a protective effect against RIBE. It has been proved that RIBE occurred and APS played the inhibitory effects on the RIBE when radiation was carried out only one time. However, whether RIBE happened by multiple irradiations and the effects of APS on the RIBE are unclear. This study aimed to investigate whether APS suppress RIBE damage induced by multiple irradiations. Materials and Methods: A549 cells were irradiated with 2 Gy X-rays to obtain a conditioned medium. Bone mesenchymal stem cells (BMSCs) was incubated with the conditioned medium 5 times every 3 days or APS. Cell proliferation was detected by CCK-8 and colony formation assay, and genomic instability and DNA damages were detected by the micronucleus and immunofluorescence assay. The protein associated with methylation and cancer-associated proteins in BMSCs were detected by western blot. Results: After five stimulations with a conditioned medium, the proliferative capacity of BMSCs decreased; APS pre-intervention promoted the proliferation of BMSCs. And conditional medium intervention increased the micronucleus rate and a number of 53BP1 foci; APS pre-intervention reduced the micronucleus rate and number of 53BP1 foci. In addition, the conditional medium intervention reduced the expression of methylation-related proteins and increased the expression of cancer-related proteins, while APS pre-intervention reversed this trend. Conclusion: Irradiated A549 conditioned medium can induce RIBE of BMSCs, which might be related to methylation and cancer-associated proteins and APS may block RIBE by multiple irradiations in BMSCs. [ABSTRACT FROM AUTHOR]

Background: Guiqi Baizhu Decoction (GQBZD) has a good protective effect on radiation-induced intestinal edema (RIIE). However, the underlying molecular mechanisms need further elucidation.Purpose: To reveal the potential mechanism of RIIE and GQBZD treatment.Methods: SD rats were irradiated with 6Gy X-ray to establish RIIE model. The general condition of the rats was observed; the dry/wet weight ratio of colon tissue was detected; the morphological changes of colon tissue were observed by HE staining; the expressions of ROS, HIF-1α and AQP4 in colon tissue were detected by confocal laser scanning; the expression of edema-related proteins was detected by Western blot. In addition, human colon epithelial cells (NCM460) was irradiated with 2Gy X-ray, and HIF-1α expression in NCM460 was knocked down by small interfering RNA (siRNA) transfection, and the activity of Na+/K+-ATPase was detected by enzyme activity kit; the ROS expression was detected by flow cytometer; the AQP4 expression was detected by laser confocal microscopy; and the expression of edema-related proteins were detected by Western blot.Results: We found that after irradiation, the colon tissue of rats was significantly edema, mainly manifested as mucosal and submucosal edema, and the ultrastructure was reflected in the structural damage of nucleus and mitochondria. ROS, HIF-1α and AQP4 were significantly expressed, and Na+/K+-ATPase expression/activity was decreased. After the intervention of GQBZD, the edema of the colon tissue of the rats was improved, the expressions of ROS, HIF-1α and AQP4 were decreased, and the expression/activity of Na+/K+-ATPase was increased.Conclusion: Ionizing radiation (IR) can cause significant intestinal edema. AQP4 and Na+/K+-ATPase are the key factors of RIIE, which are regulated by ROS and HIF-1α. GQBZD can improve hypoxia and oxidative stress, regulate the expression of AQP4 and Na+/K+-ATPase, and achieve a protective effect on RIIE. This study is the first to reveal the mechanism of RIIE. [ABSTRACT FROM AUTHOR]

Background: Guiqi Baizhu Decoction (GQBZD) has a good protective effect on radiation-induced intestinal edema (RIIE). However, the underlying molecular mechanisms need further elucidation., Purpose: To reveal the potential mechanism of RIIE and GQBZD treatment., Methods: SD rats were irradiated with 6Gy X-ray to establish RIIE model. The general condition of the rats was observed; the dry/wet weight ratio of colon tissue was detected; the morphological changes of colon tissue were observed by HE staining; the expressions of ROS, HIF-1α and AQP4 in colon tissue were detected by confocal laser scanning; the expression of edema-related proteins was detected by Western blot. In addition, human colon epithelial cells (NCM460) was irradiated with 2Gy X-ray, and HIF-1α expression in NCM460 was knocked down by small interfering RNA (siRNA) transfection, and the activity of Na + /K + -ATPase was detected by enzyme activity kit; the ROS expression was detected by flow cytometer; the AQP4 expression was detected by laser confocal microscopy; and the expression of edema-related proteins were detected by Western blot., Results: We found that after irradiation, the colon tissue of rats was significantly edema, mainly manifested as mucosal and submucosal edema, and the ultrastructure was reflected in the structural damage of nucleus and mitochondria. ROS, HIF-1α and AQP4 were significantly expressed, and Na + /K + -ATPase expression/activity was decreased. After the intervention of GQBZD, the edema of the colon tissue of the rats was improved, the expressions of ROS, HIF-1α and AQP4 were decreased, and the expression/activity of Na + /K + -ATPase was increased., Conclusion: Ionizing radiation (IR) can cause significant intestinal edema. AQP4 and Na + /K + -ATPase are the key factors of RIIE, which are regulated by ROS and HIF-1α. GQBZD can improve hypoxia and oxidative stress, regulate the expression of AQP4 and Na + /K + -ATPase, and achieve a protective effect on RIIE. This study is the first to reveal the mechanism of RIIE., Competing Interests: Conflicts of interest statement The authors declare no conflicts of interest., (Copyright © 2022. Published by Elsevier GmbH.)