Toxicity Mechanism Of In Vitro Exposure Of Typical Organophosphorus Flame Retardants To Human Respiratory System Cells

Organophosphate flame retardants（OPFRs）have recently been used in a variety of commercial vessels.First,they can be used as flame retardants,such as plastics,textiles and building materials.Second,they play an important role in extreme pressure additives and antiwear wetting agents in plasticizers,stabilizers,defoaming agents,paints,hydraulic oils,lubricating oils,transmission fluids and motor oils,and as additives in lubricants and hydraulic oils.In the 19 th century,the worldwide use of OPFRs was estimated at 102,000 tons per year,and by the beginning of the 20 th century,the global consumption of OPFRs increased to 186,000 tons per year.Like polybrominated diphenyl ethers（PBDEs）,OPFRs is also manufactured simply by mixing with a polymer matrix rather than through a chemical skeleton,which results in an unstable structure and free emission in a variety of ways.Reported OPFRs levels in the indoor environment,however,are generally higher than those in outdoor conditions.OPFRs in the indoor environment,can distributed in the air,dust,object surface and other places,and can lead to dust inhalation and skin contact of the residents.More and more studies have found the effects of OPFRs on physiological toxicity,genetic toxicity,metabolic disorders and endocrine disorders of biological samples.Triphenyl phosphate（TPHP）is a widely used flame retardant,which were defined as a plasticizer in consumption goods and as a lubricant in lubricating oil.In this thesis,by expose of TPHP,we mainly studied the cytophysiological toxicity and transcriptome expression changes of cells in five different parts of human respiratory tract（from top to bottom）,and analyzed the health risks of TPHP to human respiratory system.The cells were human nasal epithelium（HNEp C）cells,human normal nasopharyngeal epithelium（NP69）cells,human bronchial epithelium（16HBE）cells,human lung epithelium（Beas-2B）cells,human lung fibroblast（HFL1）cells.To investigate the toxic effects of TPHP on cell viability,cell membrane damage micronucleus induction,endoplasmic reticulum stress,oxidative stress,intracellular calcium level and mitochondrial membrane potential（MMP）levels,Glutathione detoxifying enzyme system and Nrf2 signaling pathway of 5 different respiratory tract cells were investigated both under short-term and long-term exposure.Also,single-cell transcriptome sequencing was carried out for the most damaged and sensitive cells to analyze signal pathways and related mechanisms.The main conclusions are as follows:HNEpC and HFL1 cells were found to cause irreversible damage,while the other three cell types were able to achieve homeostasis through self-rescue mechanisms.The downstream gene expression of Nrf2 signaling pathway was up-regulated by 1.3-7.0fold,and glutathione detoxification enzyme activity was changed by 2-10（U/mg· Protien）.In addition,after TPHP treatment,HNEp C cells suffered the most serious damage,ROS level increased,CAT,SOD,GR,GSH-Px and other antioxidant enzymes and gene expression levels increased the most significantly.The content of vascular endothelial growth factor（VEGF）associated with chronic sinusitis increased from 759.9 ng/m L to 3278.3 ng/m L,which increased 1.0 – 4.3 times in HNEp C cells,suggesting that TPHP can aggravate chronic sinusitis of HNEp C cells and damage the function of airway epithelial barrier.Lead to the destruction of airway immune tolerance.RNA sequencing results of HNEpC cells showed that KEGG enrichment analysis showed that more than 538 genes related to PI3K/AKT,MAPK and m TOR signaling pathways were enriched and regulated in HNEp C cells.C-jun amino-terminal kinase（JNK）,external regulated protein kinase（ERK）and p53 in HNEp C cells were up-regulated by 3.4,2.7,4.8 times,respectively.Indicating that TPHP has an impact on HNEp C protein linkage recombination,molecular function regulation and autophagy signaling pathway.This study is the first report to systematically compare the respiratory cytotoxicity of the entire human respiratory tract under OPFRs exposure and found that HNEp C cells are the most sensitive target cells for TPHP.The molecular mechanism revealed that TPHP exposure to HNEp C induces the activation of MAPK signaling pathway and shows potential respiratory growth differentiation and stress disorder in human nasal cells after TPHP exposure.OPFRs exposure in this study to the indoor environment of human respiratory tract cells under deposit,enrichment,toxicity,metabolism of comprehensive research into gene expression,to help understand TPHP and HNEp C pathological factor and the relationship between its upstream regulation,and help to further reveal TPHP related to the pathogenesis of chronic sinusitis mechanism of signaling pathways,Provide important prevention and management basis for environmental exposure,risk control and human health.