The Effects And Mechanisms Of Mitochondrial Damage In Human SH-SY5Y Cells Under Fine Particulate Matter

Atmospheric fine particulate matter(PM_2.5)refers to solid and liquid particulate matter with a dynamic diameter of less than or equal to 2.5 ?m in the atmosphere.These particulate matters are mainly produced from coal combustion,biomass burning,and automobile exhaust emissions.In recent years,smog has occurred frequently in many parts of China,especially in most parts of the north.The content of PM_2.5 in the air often exceed the limit of National Ambient Air Quality Standards in China,seriously affecting air quality and people's health.The PM_2.5 compositions are complex,and PM_2.5 and its different components can cause different degrees of damage to the body.Many epidemiological studies have shown that exposure to PM_2.5 can not only lead to a significant increase in the incidence of respiratory diseases such as asthma,bronchitis,chronic obstructive pulmonary disease,and cardiovascular disease,but also cause brain damage,cognitive ability impairment,and even increase the risk of neurodegenerative diseases including Alzheimer's disease,Parkinson's disease,Huntington's disease,etc.The literatures suggest that PM_2.5 can cause nervous system damage through oxidative stress,but the detailed mechanism needs to be further improved.The mitochondria are key factor in brain degeneration,and they play an important role in the study of the effects of external stimuli on health effects.PM_2.5 enters human body and can cause pathological damage to tissues or cells,leading to the changes in mitochondrial morphology and function and oxidative damage.Therefore,the mechanism of action of PM_2.5 on mitochondrial damage has attracted increasing attention.Currently,the mitochondrial regulatory mechanism of PM_2.5-induced brain injury remains unclear.Based on this,PM_2.5 samples in winter heating period were collected in Taiyuan City in this paper,and the human neuroblastoma cells?SH-SY5Y?was used as a model in vitro to explore the effects of mitochondrial damage and oxidative damage induced by PM_2.5 in SH-SY5 Y cells,and their possible molecular mechanism.In this study,the different components of PM_2.5 were extracted firstly,and the human SH-SY5 Y cells were treated under different concentrations and different times to explore the effect of PM_2.5 components on cell viability.The results showed that the whole particles of PM_2.5,the water-soluble particles of PM_2.5,the non-water-soluble particles of PM_2.5 and the organic particles of PM_2.5 induced cytotoxicity and inhibited cell viability.At the same concentrations of PM_2.5 and its components,exposure to 48 h was more cytotoxic than 24 h,and the organic particles and non-water-soluble particles produced greater cytotoxicity.According to the results,human SH-SY5 Y cells were exposed to different concentrations of the whole particles of PM_2.5?0,25,100,250 ?g m L-1?,and the change of mitochondrial morphology and mitochondrial function indicators such as ATP,mitochondrial membrane permeability transition pores?m PTP?,membrane potential,mitochondrial DNA?mt DNA?copy number,calcium ion?Ca2+?concentration as well as the oxidative damage indicators including reactive oxygen species?ROS?,manganese superoxide dismutase?SOD2?,malondialdehyde?MDA?,reduced glutathione?GSH?,and amyloid beta peptide 42?A?-42?were determined by special detection kits and ELISA kits.The expression changes of mitochondrial fusion/ fusion genes?OPA1,Drp1?,mitochondrial related stress markers?Cyp D and COX ??and oxidative damage marker?SIRT3?were detected by the real-time quantitative PCR and Western-blot techniques to investigate the effects of PM_2.5 on mitochondrial structure and function and oxidative damage.Results found that:?1?PM_2.5 caused more mitochondrial swelling,alone with the opening of m PTP and ATP levels,MMP,mt DNA copy number and Ca2+ concentration decreased;?2?PM_2.5 enhanced the expression of mitochondrial fission/fusion gene?Drp1 and OPA1?,and affected the expression of Cyp D and COX ? in SH-SY5 Y cells;?3?PM_2.5 triggered the increase of cellular ROS,Ca2+ and A?-42 levels,the decrease of SOD2 activities,GSH levels and GSH/GSSG ratio,and elevation of MDA contents,and as well as down-regulated the expression of SIRT3 in SH-SY5 Y cells.The results of this study indicated that PM_2.5 exposure caused the abnormalities of mitochondrial structure and function in SH-SY5 Y cells and the imbalance of fusion/fission gene expression,while triggerd mitochondrial membrane lipid peroxidation and cellular oxidative stress.It means mitochondrial dysfunction and oxidative stress are potential mechanisms of PM_2.5-induced brain neuronal damage,which may be related to neurological diseases.It provides an experimental basis for preventing airborne particulate pollution from inducing nervous system diseases.