The Role Of STAT5/Foxp3 Geue Methylatiou In Regulation Of JAK2/STAT5/Foxp3 Sigual Pathway Iu Asthma Exacerbation Of Rats Induced By Different Compoueuts Of Traffic-Related PM_2.5

Objective:This study is to observe the effects of different components of traffic-related PM_2.5.5 on the lung inflammation and the role of STAT5/Foxp3 gene methylation in regulation of JAK2/STAT5/Foxp3 in asthma exacerbation,and to explore the mechanism of asthma exacerbation induced by different components of PM_2.5.Methods:Ninety male SD rats were randomly divided into nine groups:saline control group,OVA group,OVA+PM_2.5.5 group?3 mg/kg?,OVA+low dose of PM_2.5.5 water-soluble extracts group?1.8mg/kg?,OVA+high dose of PM_2.5.5 water-soluble extracts group?7.2mg/kg?,OVA+DMSO group,OVA+low dose of PM_2.5.5 organic extracts group?0.6mg/kg?,OVA+high dose of PM_2.5.5 organic extracts group?2.4mg/kg?,OVA+high dose of PM_2.5.5 organic extracts?2.4mg/kg?+5-Aza group.Rats were sensitized by intraperitoneal injections of ovalbumin and challenged by inhaling ovalbumin.After challenge,rats were administrated intratracheally with different doses of PM_2.5.5 and PM_2.5water soluble and organic components once every three days,five times in total,5-Aza was injected intraperitoneally 15 mins before each exposure.The rats were sacrificed after the last exposure,and bronchoalveolar lavage fluid?BALF?was collected.The pathological changes were observed by HE staining of lung tissue pathological sections.The methylation levels of CpG promoter loci of STAT5 and Foxp3 genes in lung tissue were detected by pyrosequencing method.The protein expressions of JAK2,STAT5,P-STAT5and Foxp3 in lung tissue were detected by Western Blot.The protein expression levels of P-STAT5 and Foxp3 in lung tissue were detected by immunohistochemistry.The ratio of Treg cells in peripheral blood were detected by flow cytometry.The levels of IL-10 and TGF-?1 in BALF were determined by ELISA.Results:?1?PM_2.5.5 and its water-soluble and organic components can cause obvious infiltration of inflammatory cells around the bronchioles and the increase of goblet cells in bronchocoel and mucus secretion.The inflammatory cells around the bronchioles were significantly reduced after 5-Aza treatment.?2?Compared with the saline control group and OVA group,the exposure of PM_2.5and the low and high doses of PM_2.5.5 water-soluble components significantly decreased the methylation levels of CpG promoter loci of STAT5 in lung tissue?P<0.05?.Compared with the OVA+DMSO group,the low and high doses of PM_2.5.5 organic components increased the methylation level of CpG promoter loci of Foxp3 in lung tissue?P<0.05?.The methylation level of Foxp3 gene was significantly lower after 5-Aza treatment?P<0.05?.?3?Compared with the saline control group and the OVA group,PM_2.5.5 exposure significantly increased the expression of JAK2 protein in lung tissue?P<0.05?,and the expression levels of STAT5 and P-STAT5 protein were significantly decreased?P<0.05?.The low and high dose of PM_2.5.5 water-soluble components exposure significantly decreased the expression of STAT5 and Foxp3 protein in lung tissue compared with OVA group?P<0.05?.Compared with the OVA+DMSO group,the low dose of organic components exposure increased the expression of JAK2 protein in lung tissue?P<0.05?,and the expression levels of STAT5,P-STAT5 and Foxp3 protein were significant decreased?P<0.05?.The expression levels of STAT5 and P-STAT5 protein in 5-Aza treatment group were significantly increased?P<0.05?.?4?Compared with the saline control group and OVA,the ratio of Treg cells in peripheral blood was significantly decreased after exposure to high-dose PM_2.5water-soluble components?P<0.05?.Compared with OVA+DMSO group,the low dose of organic components exposure decreased the ratio of Treg cells in peripheral blood?P<0.05?.?5?Compared with saline control group,OVA group and OVA+PM_2.5.5 group,the content of IL-10 in BALF was significantly increased after high dose of PM_2.5water-soluble components exposure?P<0.05?.PM_2.5.5 exposure significantly increased the expression of TGF-?1 in BALF by comparison with OVA group and OVA+PM_2.5water-soluble component group?P<0.05?.Compared with the OVA+DMSO group,the low and high doses of PM_2.5.5 organic components increased the expression of TGF-?1 in BALF?P<0.05?.Conclusions:?1?PM_2.5.5 and its water-soluble and organic extracts can aggravate asthma symptoms and lung inflammation of rats.?2?STAT5 and Foxp3 gene methylation are involved in the regulation of STAT5-Foxp3 protein expression in lungs of asthmatic rats induced by PM_2.5.5 and its water-soluble and organic components.?3?The JAK2-STAT5-Foxp3 signaling pathway is involved in the regulation mechanism of asthma exacerbation induced by PM_2.5.5 and its organic components.The STAT5-Foxp3 signaling pathway is involved in the regulation mechanism of asthma exacerbation induced by PM_2.5.5 and its water-soluble components.?4?PM_2.5.5 and its water-soluble components and organic components can suppress the proliferation and differentiation of Treg in peripheral blood and promote the release of IL-10 and TGF-?1 cytokines in bronchial alveolar lavage fluid.