The Role And Mechanism Of JAK2/STAT3 Signaling Pathway In PM_2.5 Affecting The Lipid Levels Of Macrophages

Objective:The aim of this research is to explore the effects of PM_2.5 on the lipid levels in macrophages and the expression of gene and protein related with JAK2/STAT3signaling pathway,and to discuss the role and mechanism of JAK2/STAT3 signaling pathway in lipid disorder on macrophages induced by PM_2.5.Method:THP-1 cell was cultured using 1640 medium containing 10%fetal bovine serum in vitro.THP-1 cell was induced into macrophages by 200ng/m L PMA.Macrophages was exposed respectively to blank control group（0μg/m L）、low dose group（100μg/m L）、middle dose group（200μg/m L）and high dose group（400μg/m L）atmospheric PM_2.5 for6h,12h and 24 h.The STAT3 gene were specifically activated by Colivelin TFA,and the efficiency of overexpression was detected by Q-PCR.The experiment were divided into four groups after STAT3 gene over expresstion for blank control group（RPMI 1640）、PM_2.5-tread group（200μg/m L）、STAT3 gene over expresstion group and PM_2.5+STAT3gene over expresstion group（200μg/m L）.The cell and culture supernatant were collected after exposing.The survival rate of macrophages was detected by CCK-8.The levels of TG、T-CHO、HDL-C and LDL-C in macrophages were detected by colorimetry.The levels of IL-4、IL-6、IL-17 secreted by macrophages were determined by ELISA.The expression levels of mRNA of JAK2、STAT3、ABCA1、LPL were determined by Q-PCR.The expression levels of protein releated to JAK2、STAT3、ABCA1、LPL were determined by Western Blot.Statistical analysis was performed by IBM SPSS 24.0.One way ANOVA was used to compare the differences of each index among the different groups.LSD was used for pairwise comparison between the groups.The test level was set asα=0.05Result:1.The survival rate of macrophages in each dose group were significantly lower than that in the control group,and decreased with the increase of exposure dose.The survival rate of macrophages after exposure to 400μg/m L PM_2.5 for 12h and 24h were significantly lower than that after exposure to 400μg/m L PM_2.5 for 6h（P<0.05）.2.The TG levels of macrophages in low,middle for 12h low dose groups for 24h were significantly higher than that in control group（P<0.05）;The levels of T-CHO in macrophages increased with the increase of exposure dose after 6h PM_2.5 exposure.The levels of T-CHO in macrophages in middle and high dose groups were significantly higher than control group and low dose group,and the middle dose group was significantly higher than low dose group 24 h after exposure（P<0.05）.The levels of HDL-C in macrophages increased with the increase of exposure time.After PM_2.5exposure for 24h,the level of HDL-C in macrophages was significantly higher than that exposure for 6 and 12h in all dose group（P<0.05）.The levels of LDL-C in macrophages were gradually increased with the increase of dose in 6h and 12h PM_2.5group.The levels of LDL-C in macrophages in low and high-dose for 6h and high-dose for 12h were significantly higher than those in the control group;The levels of LDL-C in macrophages of middle and high dose groups were significantly lower than that in control group and low dose group for 24h（P<0.05）.The levels of LDL-C in macrophages in all dose group for 24h were significantly higher than that for6h（P<0.05）.3.The expression levels of JAK2 mRNA in macrophages decreased with the increase of exposure dose at 12h and 24h PM_2.5 exposure.The expression levels of JAK2 mRNA in macrophages in high-dose group for 12h and 24h after were significantly lower than that of control group（P<0.05）.The expression of JAK2 mRNA in macrophages in low-dose group for 12h and 24h and middle-dose group for 24h were significantly lower than that for 6h（P<0.05）.The expression levels of STAT3 mRNA in macrophages for12h in low-dose group and 24h in each dose group were significantly lower than those of control group,and the expression levels of STAT3 mRNA in macrophages in each dose group after 24h exposure were lower than those in 6h group（P<0.05）.The expression levels of JAK2 protein in 6h high-dose group was significantly lower than that in each dose group,and the expression level of JAK2 protein in 24h low-dose and high-dose groups was significantly higher than that in the control group（P<0.05）.The expression level of STAT3 protein in macrophages decreased with the increase of exposure dose at 6h,and the expression level of STAT3 protein in macrophages at 12h and 24h in low dose group were significantly higher than that in control group（P<0.05）The expression levels of STAT3 protein in macrophages at 24h in middle and high dose groups were higher than that in 6h and 12h groups（P<0.05）.4.The expression levels of LPL mRNA in macrophages exposed to PM_2.5 were significantly decreased in all dose groups;And the expression levels of LPL mRNA in macrophages exposed to PM_2.5 for 24h was significantly lower than that in 6h and 12h groups（P<0.05）.The expression level of ABCA1 mRNA in high-dose group was significantly lower than control group at 24h,and that of macrophages of moddle-dose group was significantly lower than that of 12h group at 24h.The expression level of LPL protein in low-dose group was significantly higher than that in control group at12h;The expression levels of LPL protein in low-dose group at 12h and high-dose group at 24h were significantly higher than that in 6h PM_2.5 exposure group（P<0.05）.The expression levels of ABCA1 protein in each dose group were significantly higher than those in the control group after 6h exposure;the expression levels of ABCA1protein in medium and high dose groups were significantly higher than those in 6h group after 12h exposure（P<0.05）.5.The IL-4 levels of macrophages in each dose group were significantly lower than that in the control group（P<0.05）,except for the 24 h medium dose group.The IL-4levels of macrophages in each dose group were significantly lower than that in the 6 h group after 24h exposure（P<0.05）.The level of IL-17 in macrophages of low-dose group at 6h was significantly higher than that of control group（P<0.05）,and the level of IL-17 in macrophages of each dose group at 12h were significantly lower than that of control group（P<0.05）;The level of IL-17 in middle dose group at 12h was significantly higher than that of 6h group（P<0.05）.The IL-6 level of macrophages in6h middle dose group was significantly higher than that in control group and low dose group;after 12h exposure,the IL-6 secretion level of macrophages in each dose group was significantly higher than that in 6h group（P<0.05）.6.Colivelin TFA,a STAT3 agonist,inhibited the increase of TG,T-Cho and LDL-C levels in macrophages induced by PM_2.5（P<0.05）;STAT3 agonist significantly inhibited the decrease of IL-4 and IL-7 levels and the increasement of IL-7 levels in macrophages induced by PM_2.5（P<0.05）;The STAT3 agonist significantly inhibited the declinging the level of LPL mRNA in macrophages induced by PM_2.5（P<0.05）.Conclusion:1.PM_2.5 exposure could decrease the survival rate of macrophages and increase the level of lipid in macrophages,and there was a dose-dependent and time-dependent relationship2.The mRNA and protein expression levels of JAK2 and STAT3 decreased with the increase of PM_2.5 exposure dose and time.3.The mRNA of LPL and ABCA1 decreased with the increase of PM_2.5 exposure dose and time.4.PM_2.5 could reduce the levels of IL-17 and IL-4,promote the secretion of IL-6 and induce inflammatory reaction.5.STAT3 agonist could significantly inhibit the increase of lipid level and inflammatory reaction in macrophages induced by PM_2.5 by up regulating LPL expression.