A Preliminary Study On The Mechanism Of Inhibition Of Nucleic Acid Oxidation And Aging Markers In Lung During Aging

Background: At present,the aging situation of China’s population is severe,and the prevalence of age-related diseases has increased significantly.In-depth exploration of various molecular mechanisms of the aging process,revealing the aging mechanism of biological individuals,tissue organs and cells,and screening biomarkers of aging is an urgent work.According to the theory of free radicals of aging,organisms can produce a large number of free radicals and reactive oxygen species(ROS)under the stimulation of various factors,causing oxidative damage to nucleic acids,proteins and lipids.The lung is one of the few internal organs that is constantly exposed to the external environment.The effect of the environment on the structure and function of the lung largely determines the health of the lung,which also makes the lung one of the organs with the highest level of oxidative stress.In this study,mice aged from natural aging to20 months of age were sacrificed at different time periods and specimens were collected.A 4-month-old mouse was used as a control to detect the level of oxidative stress in the lungs of mice at different months of age,and to explore its change pattern and its inhibitory mechanism during aging.In addition,the expressions of various proteins in serum and lungs of mice at different months of age were examined to find suitable lungspecific aging biomarkers.Methods: In this study,C57 BL / 6 mice aged 4 months,5 months,8 months,and 20 months were used to detect the expression of nucleic acid oxidation levels in lung tissue of mice at different months by immunohistochemistry.Western blotting was used to detect the expression of MTH2,OGG1,NUDT5 and AUF1 in the lung tissue of mice at different months of age.At the same time,the immunohistochemical method was used to further verify the expression of nucleic acid oxidation inhibitor protein.Cytokine levels in lung tissue and serum of mice were detected by protein chip,and cytokines with increasing age were selected in mouse lung tissue and serum.Immunohistochemical detection was used to verify the expression of LOX-1 in mouse lung tissue during aging.Finally,the mouse liver,kidney,spleen and small intestine tissues were immunohistochemically stained with cytokine LOX-1 antibody to obtain specific aging biomarkers of lung tissue during aging.Results: Nucleic acid oxidation level immunohistochemical staining results showed that the expression of nucleic acid oxidation level in the lung tissue of mice aged 4months,5 months,8 months,and 20 months was increasing.Western Blotting results showed that the expression of the nucleic acid oxidation inhibitor protein AUF1 in the lung tissue of 4-month-old,8-month-old,and 20-month-old mice decreased with increasing age.The expressions of MTH2 and NUDT5 increased with age,and the changes were statistically significant(P <0.05).Although OGG1 expression increased with age,the difference was not statistically significant(P> 0.05).Further verification by immunohistochemistry method was found to be consistent with the results of Western Blotting.The protein chip test results showed that the cytokine LOX-1 in the lung tissue and serum of mice increased with age,and was statistically significant.The results of immunohistochemical verification showed that the expression of LOX-1 in the lung tissue of mice aged 4 months,5 months,8 months and 20 months increased with age,and the staining results were consistent with the results of protein chip detection.Using immunohistochemistry to detect the expression of cytokine LOX-1 in mouse liver,kidney,spleen and small intestine tissues,we did not find a significant increase with age(P> 0.05).Conclusion: 1)The level of 8-oxo G is increasing during the ageing process of mice,suggesting that the level of oxidative stress in mice increases with age.2)MTH2 and NUDT5 increase with age in the lungs of mice,and AUF1 decreases with age.Although MTH2 and NUDT5 showed a significant increase with age,the gradual increase in oxidation levels was not suppressed.It is considered that AUF1 may play a dominant role in the regulation of oxidative stress in the aging process of lungs.3)During the aging process of mice,LOX-1 protein showed an aging trend in serum and lungs,and the changes were statistically significant.At the same time,there is no significant aging change in other organs(liver,spleen,kidney,small intestine),and it can be considered as a lung-specific biomarker of aging in mice.