Toxic Effects Of Vascular Induced By Acute Exposure To Atmospheric Ultrafine Particles

Ultrafine particles?UFPs?are airbone particulates of less than 100nm in aerodynamitic diameter,which can deposit in the bronchioles and alveoli through inhalation.In addition,UFPs can penetrate air-blood barrier into blood circulation.A large number of epidemiological investigations have confirmed that UFPs is a unique and important factor of cardiovascular diseases caused by air pollution.The purpose of this study is to clarify the pollution concentrations of UFPs on monitoring points,and explore the detrimental effects of vascular atherosclerosis caused by UFPs,so as to provide reference for prevention our country regional air pollution and cardiovascular disease.Objective1.To monit and collect the UFPs and then clarify the pollution concentrations of UFPs on the monitoring point during heating period in Tianjin.2.To establish ApoE^-/-mouse and MAFs model and exposed to UFPs respectively by acute endotracheal instillation,to explore the promotion effect on vascular atherosclerosis induced by UFPs.Methods1.To detect number concentrations,surface area concentrations and mass concentrations of UFPs all day using WPS-1000XP wide-range particle spectrometer in central area of Tianjin;to collect UFPs by using Nano-MOUDI 125A micropore uniform deposit impactor;to analysis the surface morphology and the composition of chemical element of UFPs with the JSM-7500F and energy dispersive X-ray spectrum.2.ApoE^-/-mouse were exposure to UFPs suspension for 6d continuously by trachea,the UFPs concentration pollution are equal to the monitoring value of UFPs number concentrations.The mouse were killed at 3,5,7,10d after the end of UFPs exposure,to detect differential Small RNA of aorta vascular using BGISEQ-500sequencing technology,to analyse of the pathological changes of thoracic aortaobserve,detect the levels of the nitrative stress index and key proteins of mouse by immunohistochemistry and ELISA.3.To culture primary mouse aortic adventitial fibroblasts?MAFs?and exposed UFPs suspension to MAFs for 72h,the UFPs concentration pollution are equal to the monitoring value of UFPs number concentrations.To detect the level of differential Small RNA,nitrative stress indicators and key proteins.Results1.The average number concentration of UFPs were 11720/cm³,while the highest number concentration of UFPs were up to 23317/cm³ during heating period;the analysis of microstructure and elements composition of UFPs showed that the shape are irregular,approximate spherical part,UFPs mainly came from sulfate minerals and soot particles formed by atmospheric chemical reaction.The elements of UFPs and PM were similar,and C,N,O were rich.2.Compared to the control group,atherosclerosis appeared at 3,7,10 d after the end of UFPs exposure,and the expression of IL-6,MCP-1,p47phox and 3-NT in thoracic aorta of ApoE^-/-mouse in UFPs exposure groups.increased significantly.Compared with the control group,target genes of differential Small RNA were highly enriched in cell transformation and adhesion function in UFPs-exposured groups;miRNA qPCR showed that miR-301b-3p and let-7c-1-3p increased significantly and Smad2 and TGF?1 that the key proteins were increased in UFPs exposured MAFs.3.Compared to the control group,the level of 3-NT increased,and TGF?1,Smad2 and Smad3 increased in UFPs exposured MAFs.ConclusionUFPs monitoring and pollution characterization showed that,the pollution level of UFPs at monitoring site was higher in composition with European and American areas;the daily peaks of UFPs pollution levels appear mostly in the morning and evening.The elements C,N,O were rich in UFPs.UFPs mainly from vehicle exhaust,dust and road dust and atmospheric emissions of PM degradation and depolymerization may contribute partly to the formation of UFPs.UFPs induced nitrative stress and inflammatory cell infiltration in the thoracic aorta,and fatty plaques and plaques appeared on the arterial wall,which accelerated the change of vascular atherosclerosis in ApoE^-/-mouse exposured to UFPs,9 miRNAs were differentially expressed,among which the expression of mi R-301b-3p and let-7c-1-3p were up-regulated,which may regulate the key proteins Smad2 and TGF?1 of TGF?/Smads signaling pathway to promote vascular remodeling and together with nitrification stress contribute to atherosclerosis.