2773 - Ginsenoside Rg5 affects irradiation-induced lung fibrosis in mice via macrophage-mediated phagocytosis involving MERTK and PTX3

H. Bai^1,2, and T. Li³; ¹Department of Radiation Oncology, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, Sichuan, China, ²Georgetown University Hospital, Washington DC, DC, ³Department of Radiation Oncology, Sichuan Clinical Research Center for Cancer, Sichuan Cancer Hospital & Institute, Sichuan Cancer Center, Affiliated Cancer Hospital of University of Electronic Science and Technology of China, Chengdu, China

Purpose/Objective(s): This study is expected to elucidate the molecular mechanism of the protective effect of Gensinoside Rg5 on radiation-induced lung injury and provide a new basis and method for its protection. Materials/

Methods: In this study, we firstly construct animal model for radiation therapy and take lung tissue for HE staining, Masson staining, and immunohistochemistry to evaluate the effect of Rg5 on pulmonary edema and inflammatory cell infiltration after radiation-induced myocardial injury. The immunohistochemical indicators mainly include mitochondrial related indicators such as SIRT1, GPX4, PINK1, Parkin, and MFN2 to clarify their relationship with Rg5. At the same time, dual fluorescence staining was performed to clarify the spatial relationship. Secondly, we use Western blotting technology and immunoprecipitation to determine HSP90a Interaction with HDAC3 and study of Rg5 on lung specific HSP90a. The impact of activity and exploration of its regulatory mechanism on HDAC3 levels includes analyzing the distribution of HDAC3 in the nucleus and cytoplasm, as well as studying the selective effect of Rg5 on HDAC3 substrates. Lastly, we explore the interaction between GDF11 and HDAC3, as well as their potential association in Rg5 mediated lung protection mechanisms to verify whether Rg5 regulates the expression of SIRT1 through the HDAC3/GDF11 pathway.
Results: Previous studies have shown that radiation-induced lung injury is associated with oxidative stress of mitochondrial dysfunction and pulmonary fibrosis. In our work, we have found that Rg5 can reduce the fibrosis and inflammatory cell infiltration of mouse pneumonocytes after radiotherapy, and has a potential lung radiation protection effect; Immunohistochemistry results from animal experiments showed significant differences in SIRT1, HDAC3, PINK1, PARKIN, MFN2, and GDF11 between Rg5 group and control group after radiation. To clarify the expression relationship between SIRT1 and other biomarkers, we selected SIRT1 as a fixed biomarker and conducted immunofluorescence double staining experiments with DRP1, MFN2, and HDAC3. The results showed that there were similar expression trends and spatial positions among the biomarkers in each group, suggesting a potential synergistic relationship between the biomarkers in each group. We induced pulmonary peripheral vascular endothelial cells using iPSCs and performed CD31 immunofluorescence double staining of mitochondrial markers and vascular endothelial markers. The results showed that radiation therapy can cause damage to vascular endothelial cells, decrease vascular integrity, decrease mitochondrial length, and impair function, while ginsenoside Rg5 can reduce this trend.

 
Conclusion:  Gensinoside Rg5 can reduce radiation-induced lung injury by alleviating lung fibrosis and inflammatory cell infiltration via regulating HSP90a-HDAC3-GDF11-MFN2 Pathway.