Correlation Analysis Between PM2.5 And Lung Cancer And Its Effect On Respiratory Microflora In Mice

ObjectiveSince airborne particulate matter(PM)is a heterogeneous mixture,a large number of epidemiological studies currently associate particulate matter(PM2.5)with an aerodynamic diameter of less than 2.5 ?m with the negative effects of the human body,particularly the respiratory system.And found that PM2.5 can promote the development of malignant tumors,especially lung cancer.Microecological studies have also shown that PM2.5 can alter the distribution of upper respiratory flora and cause damage to the health of the body.Due to the heterogeneity of PM2.5 composition and the actual damage to residents' lives,we analyzed the effects of atmospheric PM2.5 on respiratory flora in mice and the effects of air pollutants in Shenyang on the death of malignant tumor residents.Further research to evaluate the process of PM2.5 may lead to respiratory diseases by changing the respiratory micro-ecology,and provide a theoretical basis for controlling air pollution to improve the living environment of residents and related diseases.Methods(1)Atmospheric pollutant data,meteorological data,and daily death data of malignant tumors were collected in Shenyang City,Liaoning Province from January 1,2012 to December 31,2017,using Poisson generalized additive model to analyze and discuss atmospheric major pollutants.Correlation analysis and lag effects between deaths from malignant tumor residents.(2)PM2.5 dust was collected from the main traffic trunks in Shenyang and made into a suspension.Using the oral and nasal exposure system,18 BALB/c mice were divided into experimental group and control group.exposing BALB/c mice to PM2.5 environment for 4 hours a day,5 days a week for 4 weeks,control animals were treated with similar conditions;mouse bronchial lavage fluid and bronchoalveolar lavage fluid samples were collected and 16S rDNA sequencing was performed according to the protocol in the Illumina Hiseq 2500 sequencing system.The respiratory group flora Operational taxonomic units(OTU)and the changes in abundance and diversity of the experimental and control mice were obtained.The evaluated to investigate the effects of major atmospheric pollutants on respiratory flora.Results(1)Through the analysis of the collected data,from January 1,2012 to December 31,2017 it is found that particles with aerodynamic diameter<10 ?m(PM 10)and particles with aerodynamic diameter<2.5 ?m(PM2.5),and SO2,NO2 the average year concentration exceeded the national first-class standard,which were 108.20?g/m3,67.18?g/m3 64.92 ?g/m3 and 43.78?g/m3,respectively.In the analysis of the correlation between different air pollutants(PM10,PM2.5,SO2,NO2)and meteorological factors(air temperature,humidity),it was found that there was a significant correlation between the four main air pollutants,especially PM2.5 and PM10 have the highest correlation and the research is also the most representative.During the study period,a total of 49,855 residents died of malignant tumors in Shenyang,with an average mortality rate of 220.97/100,000.The top three malignant tumors of male residents were lung cancer,liver cancer and intesltinal cancer,with an average annual mortality rate of 36.73/100,000,12.14/100,000,10.9/100,000.the top three malignant tumors of female residents are lung cancer,colon cancer,breast cancer,and the average annual mortality rate is 31.61/100,000,12.39/100,000,8.7/100,OOO.During the period from 2012 to 2016,the death rate of malignant tumors in Shenyang residents increased year by year,and more men than women,the death situation in 2017 decreased slightly.The death rate in the age group showed that the mortality rate increased with age,and the death peak occurred in the 75?80 age group,with the highest value of 6211 people.The lung cancer was the cause of death in this city.The first disease is the primary risk factor threatening the health of residents.By establishing a model to control the confounding factors,it was found that PM2.5 increased the RR of each tumor by 10?g/m3 in the warm season(May-October)by 0.024(95%confidence interval:0.005?0.043).The delayed effect of malignant tumor death was not significant.PM 10 had a greater impact on malignant tumor mortality after 2 days of lag,and increased after 3 days of lag.The PM2.5 lag has a weaker impact,but it has a greater impact than the same period.(2)After modeling BALB/c mice by using PM2.5,according to the high-throughput sequencing analysis of 16S rDNA gene,it was found that the experimental group clustered the common sequence from the SILVA bacterial 16S sequence library by using the OTU method.The study found that a total of 1419 OTUs were analyzed in the upper and lower respiratory tract in the control group,527 OTUs were found in the upper respiratory tract,and 258 specific OTUs were found in the lower respiratory tract.In PM2.5 exposed mice,a total of 1136 OTUs were analyzed in both regions,and the number of OTUs found in the upper and lower respiratory tract was less than that in the control group.It was found that the number of OTUs in the respiratory tract decreased after PM2.5 exposure.According to the results of the species classification tree,at the genus level,The dominant OTUs in the lower respiratory tract include the genus Trichophytonaceae(10.7%),Lactobacillus(9.68%),Staphylococcus(3.02%),Enterococcus(1.11%),and Plasmodium in the Bacteroides 1.37%),Bacteroides(1.47%);the dominant flora in the upper respiratory tract includes Pseudomonas(1.92%),Serratia(1.84%)and Roche(1.41%)in Proteobacteria.Conclusion(1)The results show that the increase in air pollution is related to the number of deaths from Lung cancer in Shenyang,and the seasonality,gender,and age are also influencing factors.(2)Exposure to PM2.5 can affect changes in respiratory microecology in BALB/c mice.