Preliminary Study On Vascular Injury Induced By PM Exposure In Mice And Its Mechanism

Objective: Using Nrf2 knockout mice as model,the IVC system was used to simulate the real exposure of external PM to observe the damage and mechanism of PM exposure to blood vessels.Methods: Mice were exposed to PM for 42 days using an independent ventilation cage(IVC system).Mice were exposed to PM for 16 hours a day.80 Nrf2 gene knockout mice and 80 wild type mice were randomly divided into four groups,40 mice in each group(wild type control group(WTC),wild type exposure group(WTE),knockout control group(KOC),knockout exposure group(KOE)).The concentrations of particulate matter in cage and outside atmosphere were detected and recorded by TSI portable environmental dust detector three times a day in the morning,middle and late.At the end of the experiment,the mouse aorta was taken for pathological section observation.The levels of ABCA1?Dag1?BMP2?TGF??AKT1?MAPK?DDIT3?PRKCB?PPP2CB?ACE?AT1R and AGT m RNAs in vascular tissue of mice in each group were detected by RT-PCR method.The expression levels of Ang II and MCP-1 proteins in serum were detected by ELISA,the expression levels of ACE and AT1 R proteins in vascular tissue were detected by immunohistochemical method,and the expression levels of AT1 R protein in vascular tissue was detected by Western-blot method.The results were analyzed quantitatively.Results: The body weight of mice was measured during the experiment in each group.After statistical analysis,there was no significant difference in body weight between the groups(P>0.05).(1)The results of pathological section showed that the thickness of vascular wall in WTE group was significantly higher than that in WTC group(P<0.05).Compared with KOC group,the vessel wall of KOE group was significantly thickened(P<0.05).(2)The results of q RT-PCR showed that the m RNA expression level of AGT,ACE,AT1 R gene in WTE group was significantly higher than that in WTC group(P<0.05).Compared with KOC mice,the m RNA expression level of AGT,ACE,AT1 R gene in vascular tissue of KOE group was significantly increased(P<0.05).(3)The results of Elisa showed that compared with WTC group,the expression level of MCP-1 protein in serum of WTE group showed an increasing trend,but there was no statistical difference(P > 0.05).Compared with KOC group,the expression level of MCP-1 protein in serum of KOE group was significantly higher(P<0.05).The results of Elisa showed that the expression of Ang II in WTE group was significantly higher than that of WTC group(P <0.05).The expression of Ang II in serum of KOE group was significantly higher than that of KOC group(P<0.05).(4)The results of immunohistochemistry showed that the expression level of ACE protein in vascular tissue of WTE group was significantly higher than that of WTC group(P<0.05).Compared with KOC group,the expression level of ACE protein in vascular tissue of KOE group was significantly higher than that of KOC group(P < 0.05).Compared with WTC group,the expression level of AT1 R protein in vascular tissue of WTE group was lower than that of WTC group,and the expression of AT1 R protein of KOE group was lower than that of KOC group.(5)The expression of AT1 R protein in vascular tissue of WTE,KOC and KOE group was significantly lower than that in WTC group.Conclusion:(1)The vascular wall of mice exposed to PM was significantly thickened,and the thickening of vascular wall in KOE group was the most significant.The expression of Ang II protein in peripheral blood of mice exposed to PM was significantly increased,especially in KOE group,while the expression of MCP-1 protein in KOE group was significantly higher than that in KOC group.This suggests that Nrf2 gene knockout may promote vascular injury induced by PM exposure,and its further mechanism needs to be further studied.(2)The m RNA and protein expression of ACE gene in PM exposed group was significantly higher than that in control group,and the m RNA expression level of AGT gene in PM exposed group was significantly higher than that in control group.(3)However,the expression of AT1 R gene and protein expression of AT1 R gene in the exposed group of PM group are opposite,which may be related to the regulation of apparent level.