Metabolomic Analysis Of Lung Tissue And Serum In The Progression Of Radiation-induced Lung Injury

Objective:Radiation-induced lung injury is a complication caused by chest tumor radiotherapy,so to explore the molecular mechanism and biomarker of radiation-induced lung injury is of great significance for chest tumor radiotherapy(including nuclear radiation accidents and nuclear wars).The progression of radiation-induced lung injury is accompanied by changes in metabolism-related genes and metabolites.Metabolomic analysis provides comprehensive and systematic high-throughput qualitative and quantitative analysis of metabolites with a molecular weight of less than 1000 Da.However,the metabolomic profiles of radiation-induced lung injury have not been reported yet.The purpose of this study was to explore changes in metabolites in the lung tissues and serum of irradiated animal models to reveal new biomarkers and potential molecular mechanisms for their progression.With the purpose of studying changes of metabolites in the lung tissue and serum of irradiated animal models,this paper aims to reveal new biomarker and mechanism of lung tissue radiation damage,so as to analyze its potential as a new radiobiological dosimeter.Methods:(1)Establishment of unilateral radiation lung injury rat model.Male Sprague Dawley(SD)rats were randomly divided into the control group(unirradiated),10 Gy irradiation group,and 20 Gy irradiation group(n=6).After the rats were anesthetized,right lungs were irradiated with 10 Gy and 20 Gy under a linear accelerator(at a dose rate of 200 cGy/min).One week after irradiation,serum and lung tissue samples were collected and untargeted metabolomic analysis was performed using GC/MS.Obvious morphological changes of lung tissue after radiation were observed through the electron microscopy and HE staining.(2)By taking HELF as the research object at the cellular level,taurine and piperine were selected for experiments,and MTT method was applied to detect vitality.Besides,the cell proliferation ability after irradiation was detected via colony formation test,the apoptosis rate was detected by means of flow cytometry,and the cell necrosis was measured by a lactate dehydrogenase cytotoxicity test.Results:(1)Compared with the control group,a total of 229 data peaks(metabolites)were detected in the serum of the rats in the irradiated group,and there were 40 differential metabolites,among which 19 differential metabolites were common to the two irradiation groups,including:N-formyl-L-methionine,carbazole,taurine,oxalic acid,and p-benzoquinone.There were 20 metabolic pathways were detected,of which 13 were the same metabolic pathways in the two irradiation groups,including:taurine and hypotaurine metabolism,riboflavin metabolism,glyoxylate and dicarboxylate metabolism,and ABC transporters.(2)A total of 453 data peaks(metabolites)were detected in the lung tissue of irradiated rats,of which only one differential metabolite(cytidine)was common to both irradiation groups.Representative differential metabolites include:taurine,piperine,mucic acid,and methyl β-D-galactopyranoside.Total of 32 metabolic pathways were enriched,of which 7 metabolic pathways were common to the two irradiation groups,which were pyrimidine metabolism,propionate metabolism,nicotinate and nicotinamide metabolism,aminoacyl-tRNA biosynthesis,ABC transporters and valine,leucine and isoleucine biosynthesis and degradation.The taurine was shared by the serum of the two irradiation groups and the lung tissue of the 20 Gy irradiation group.It was up-regulated in the serum,but was down-regulated in the lung tissue.(3)Findings at the cellular level:1.10 mM taurine can significantly alleviate the degree of damage to HELF cells caused by ionizing radiation;2.20 mM taurine can significantly improve the colony survival rate of HELF cells after irradiation and enhance the cell proliferation ability;3.20μM piperine can significantly alleviate the degree of damage to HELF cells caused by irradiation;4.neither taurine nor piperine shows significant effect on the apoptosis rate of HELF cells.Conclusion:This study provides evidence that radiation induces metabolic alterations in lung and serum after thoracic irradiation of rats.Metabolomic analysis revealed commonness and specificity in the metabolites and the metabolic pathways in lung tissues and serum at different dose groups.This indicates that instead of being the result of a single pathological mechanism,the occurrence of radiation-induced lung injury is a comprehensive and complex damage caused by the imbalance of multiple metabolic pathways under radiation.In particular,taurine and piperine are involved in the radiosensitivity and radiation-induced death of lung fibroblasts.The changes in the metabolic response of irradiated lung tissues and serum,laid the foundation for further study of the progression mechanism and biomarkers of radiation-induced lung injury.These findings significantly advance our understanding about the pathophysiology of radiation-induced lung injury from the perspective of metabolism.