Study On The Toxic Effect Of TBBPA And BDE209 On Human Respiratory System Cells And Related Proteins

Brominated flame retardants(BFR)is a kind very high dosage of chemicals,widely used in printed circuit boards and other polymer materials in the flame retardants.As an environmental pollutant,it is widespread in variety of non-biological and biological media.The most typical and frequently determined in environments BFRs are tetrabromobisphenol A(TBBPA)and decabromobiphenyl ether(PBDE).In this study,human bronchial cells Beas2 B,lung epithelial cells 16 HBE as well as human serum albumin(HSA)were mainly used as research objects,and the toxicity of TBBPA and BDE209 on human respiratory exposure was studied from both the cell and protein levels.Firstly,the toxic and damaging effects of TBBPA on human respiratory system were studied from the cellular level.The results showed that with increase of TBBPA exposure dosage from 0 to 50 M,the survival rate of both types of cells gradually decreased and the cell permeability continuously increased.This indicates that the higher the concentration of TBBPA,the more serious damage to the cell viability and structure.In addition,from the analysis of flow cytometry also found that partial apoptosis occurred after the exposure,and the apoptosis rate increased with the increase of concentration.However,under high levels of stimulation,most cells go straight to the stage of death without the process of apoptosis.Further gene expression analysis revealed that the expression levels of the apoptosis-related genes p53,survivin,bax,bcl-2,caspase-3 and caspase-9 were all up-regulated to different extent,among which the expression levels of the 24 hour exposure were more strongly upregulated than that of the 12 hour exposure.The caspase-3 and Survivin genes of the two respiratory system cells were significantly up-regulated(2-9 times)when exposed to different concentrations of TBBPA,while the caspase-9,bcl-2 and bax genes were slightly up-regulated(1-6 times),and the expression of p53 gene tended to be stable.According to the up-regulated expression of caspase-9,caspase-3,bcl-2 and bax,it can be speculated that the mitochondrial pathway of cell apoptosis may be activated.In addition,as a pair of antagonistic genes,both bcl-2 and bax showed the same expression trend.On the one hand,bcl-2 can inhibit the progress of cell apoptosis,while the expression of bax also antagonizes the effect of bcl-2.This suggests that apoptosis after stimulation is also the result of changes in the intracellular balance.In addition,the activities of reactive oxygen species(ROSs),antioxidant enzymes SOD and CAT were measured during the exposure process,and the results showed that the ROSs components and antioxidant enzymes in both cells were significantly increased,indicating that the cells received certain oxidative damage and oxidative stress during the TBBPA exposure.Furthermore,a comparative study showed that Beas2 B cells had a stronger tolerance to TBBPA than 16 HBE cells.Furthermore,the effects of BDE209 on the configuration and potential function of HSA was revealed from the protein level.Spectral experiments showed that both TBBPA and BDE209 could induce conformational changes of HSA,the content of HSA helix decreased,the secondary structure became unstable,and the hydrophobicity around Trp residues increased.TBBPA plays a more significant role than BDE209.In addition,the binding sites of TBBPA / BDE209 with HSA were also calculated and analyzed.The amino acids of TBBPA near the binding sites of HSA were residues of ARG484,LEU481,GLU450,VAL344,TRP214,LYS199,and LEU198.The amino acids of BDE209 near the binding sites of HSA were HIS288,ARG257,CYS245,HIS242,LYS199,GLN196,GLU153,and TYR150.Furthermore,the interaction between TBBPA / BDE209 and HSA were carried on the theoretical calculation,the results show consistent with the experimental results,that is BDE209 binding energy(-?G = 6.35 kcal/mol)than TBBPA(-?G = 6.78 kcal/mol).This might be explained that BDE209 HSA no H atoms for hydrogen bonding,while TBBPA contains multiple H atoms.In this thesis,a series of toxic and damaging effects of typical brominated flame retardants such as TBBPA and BDE209 on human respiratory system were studied from both cell and protein levels,revealing the respiratory exposure risk of typical BFRs in the environmental system.After being stimulated by TBBPA exposure,the cells related to human respiratory system will receive obvious toxic stimulation,leading to the peroxidation of cells,the occurrence of intracellular oxidative stress,and the induction of apoptosis.In addition,during the process of damage,cell permeability also increases,further leading to the exposure risk of intracellular substances and pollutants.Furthermore,typical brominated flame retardants will further interact with serum albumin in cells,directly affecting the changes of protein structure and function.This study revealed the respiratory exposure risk of typical brominated flame retardants to human body,and provided some reference for the research on the exposure of typical toxic pollutants to human respiratory tract and the toxic action mechanism.