The Oxidative Potential And Vascular Endothelial Injury Of Water Soluble Components Of Ambient Fine Particulate Matter

Ambient fine particulate matter(PM2.5)contributes significantly to the air pollution,arising public health concern.Epidemiological studies have revealed the association between PM2.5 and increasing morbidity and mortality from cardiovascular diseases.PM2.5 can penetrate alveoli into the blood circulation and cause vascular endothelial damage in the process.The mechanism of PM2.5 on vascular endothelial cell injury remains to be further investigated.We collected ambient PM2.5 samples in Hangzhou city for four consecutive quarters in 2017 and analyzed its mass concentration.The temporal variation of the exposure-relevant level and intrinsic properties of PM2.5 were investigated via the DTT assay.The human umbilical vein endothelial cells(HUVEC)model was used to investigate the effects of water-soluble PM2.5 components exposure on nitric oxide(NO)production and angiogenesis.The mechanism of PM2.5 on vascular endothelial cell injury was further explored from the perspective of catalyzing NO by endothelial nitric oxide synthase(eNOS)and vascular endothelial growth factor(VEGF).The main results are summarized as followings:(1)The annual mean of ambient PM2.5 mass concentration collected at Zhejiang University(30°31' N,120°08' E)is 63,05 ?g m-3 with the significant seasonal variations ranking as Winter>Spring>Summer>Autumn.(2)The annual mean volume-normalized DTT activities(DTTv)is 0.62 nmol/min/m3,and the annual mean mass-normalized DTT activities(DTTm)is 6.39 pmol/min/?g.The oxidative potential of PM2.5 has a high exposure level but low oxidative toxicity throughout the year,and the active component has significant seasonal variation.It is positively correlated between DTTv and PM2.5 mass concentration with stronger correlation appearing at daytime(summer:rs=0.834,p<0.01;autumn:rs=0.6915,p<0.01)compared to nighttime(summer:rs=0.334,p>0.05;autumn:rs=0.274,p>0.05).There is no significant correlation between DTTm and PM2.5 mass concentration.The mass concentration is usually related to the exposure levels but not the intrinsic properties of components.(3)After treated with water-soluble PM2.5 components at 150 ?g/mL,NO production of HUVEC cells was significantly elevated.Two-factor ANOVA shows that the effects of water-soluble PM2.5 components on NO production is related to the exposure dose and composition(p<0.01).(4)The number of loops and total tube length are inhibited in a dose-dependent manner,showing vascular rupture and ring resistence.Two-factor ANOVA shows that the effects of water-soluble PM2.5 components on the tube formation of HUVEC are related to the exposure dose and composition(p<0.01).(5)The expression level of eNOS and VEGF in HUEVC cells is analyzed.There are no significant effects of water-soluble PM2.5 components on the mRNA expression of eNOS and VEGF.After treated with water-soluble PM2.5 components at 150 ?g/mL,PM2.5 significantly inhibits the protein expression of eNOS and VEGF in a dose-dependent manner.Our study evaluates the oxidative potential of PM2.5 and its effects on vascular endothelial injury,and preliminarily discusses the mechanism of endothelial injury caused by PM2.5 interfering with the catalytic synthesis of NO.The obtained results may facilitate risk assessment of PM2.5 toward human health.