The Benzofluoranthrene Of The Atmospheric Fine Particulate Matter Induce Autophagy In Mouse Glomerular Podocytes

Background and Objective:Epidemiological investigations have shown that the incidence of chronic kidney disease(CKD)has been rising year by year,and has become one of the major issues that threaten human health.The contradiction between environmental pollution caused by the rapid increase in the level of social industrialization and the increase of the incidence of chronic diseases in human has also become increasingly prominent.Recent investigations have found that long-term high levels of exposure to atmospheric particulate matter(PM2.5)can lead to renal function decline,CKD disease and even progression to end-stage renal disease(ESRD)risks.Studies have shown that the long-term exposure to PM2.5 also increase the incidence of podocyte diseases,such as membranous nephropathy(MN).The PM2.5 composition is complex.Numerous studies have shown that the organic components of the PM2.5polycyclic aromatic hydrocarbons can generate a large amount of reactive oxygen species(ROS)by activating the oxidative stress(OS)reaction in vivo to reduce the exposed cell resistance,then causes cell damage and apoptosis.OS and autophagy have been shown to be closely related.Autophagy,as a highly conserved self-protection mechanism widely existing in eukaryotes,is normally at a physiologically basic level.When the cells are subjected to external stimuli,adaptive changes are made to maintain homeostasis,but excessive autophagy causes celldamage and apoptosis.At present,the studies involving specific pathogenesis between PM2.5 and glomerular disease are rarely repoted.This study intends to investigate the influencing factors of PM2.5 organic components on the degree of glomerular podocyte injury and to verify whether autophagy is one of the possible mechanisms of PM2.5-induced kidney disease.Method:Cultured conditionally immortalized mouse podocytes(MPC)in vitro.The benzofluoranthene with the highest organic content of PM2.5 in Zhengzhou City was selected as the cytotoxic substance.CCK-8 colorimetric assay was used to determine the proliferation of MPC at different concentrations and different time.The number of autophagy in each group was observed by transmission electron microscope.Western blot was used to detect the expression of protein.Cellular immunofluorescence was used to detect the expression of autophagy protein LC3 B.Result:1.The organic component benzofluoranthene in PM2.5 can cause MPC damage,and the degree of damage is dose-dependent and time-dependent.The greater the dose and time,the heavier the damage degree(P<0.05).2.With the increase of benzofluoranthene stimulation concentration and time,the number of autophagy in each group decreased by transmission electron microscope.3.With the increase of benzofluoranthene stimulation concentration and time,the expression of Nephrin,Beclin-1 and LC3 B protein decreased(P<0.05),the expression of Desmin increased(P<0.05),suggesting that the degree of podocyte injury have a closely relationship with the exposure dose and time,and the level of cellular autophagy gradually decreased.4.The results of immunofluorescence assay also showed that with the increase in the dose and time of benzofluoranthene exposure,the degree of expression ofautophagic protein LC3 B gradually weakened,suggesting that the level of autophagy decreased.Conclusion:1.The organic components in PM2.5 can cause damage to MPC,and the degree of damage is dose-dependent and time-dependent.2.With the increase of concentration and time of benzofluoranthene exposure,the number of autophagy in each group decreased by transmission electron microscope,the expression of autophagy proteins Beclin-1 and LC3 B was weakened,and the autophagy process was inhibited.3.The inhibition of autophagy pathway may be one of the mechanisms that lead to the damage of glomerular podocytes and the occurrence of kidney disease caused by benzofluoranthene in PM2.5.