The role and mechanism of neutrophil extracellular traps in the formation of thoracic aortic aneurysm and dissection in mice

Zhang Bin; Zhu Hanzhao; Sun He; Jiang Liqing; Song Fan; Jiang Pengcheng; Jin Zhenxiao; Duan Weixun; Yu Shiqiang

doi:10.13498/j.cnki.chin.j.ecc.2025.02.13

Abstract：Objective To investigate the role and mechanism of neutrophil extracellular traps(NETs)in the formation of thoracic aortic aneurysm and dissection(TAAD)in mice.Methods A mouse TAAD model was induced by β-aminopropionitrile(BAPN)administration(orally,diluted in drinking water,1 g/kg/day),and DNase Ⅰ(20 mg/kg/day)was intraperitoneal injected to remove the generated NETs in vivo.Eighty 3-week-old male C57BL/6 mice were randomly divided into Con+V group,Con+DNase Ⅰ group,BAPN+V group and BAPN+DNase Ⅰ group.After 4 weeks,the incidence and rupture rate of TAAD were recorded.The maximum internal diameter of thoracic aorta was measured by the aortic ultrasonography.H&E and EVG staining were used to describe the aortic histological changes and elastin degradation.Serum levels of citH3,cfDNA and nucleosome were detected by special kits.citH3,MPO and α-SMA fluorescence intensity were detected by immunofluorescence staining.Apoptosis was observed by TUNEL staining.The mRNA expressions of IL-1β,IL-6 and TNF-α were detected by qRT-PCR.The protein expressions of citH3,PAD4,MMP2,MMP9,SIRT1,Ac-foxo1 and Ac-p53 were detected by Western Blot.Results The incidence and rupture rate of TAAD in Con+V group and Con+DNase Ⅰ group were 0,the incidence and rupture rate of TAAD in BAPN+V group were 90.0%and 55.0%,and the incidence and rupture rate of TAAD in BAPN+DNase Ⅰ group were 50.0%and 30.0%.Compared with Con+V group,the maximum internal diameter of thoracic aorta in BAPN+V group was increased,the vascular wall became dilated,and the elastic fibers broken obviously.Besides,the serum levels of citH3,cfDNA and nucleosome were increased,and the formation of NETs in aorta in BAPN+V group was increased.Additionally,the inflammation of aorta tissue and apoptosis of smooth muscle cell were significantly enhanced,while the expression of SIRT1 signaling pathway was significantly down-regulated in BAPN+V group(P<0.01).Compared with BAPN+V group,the maximum internal diameter of thoracic aorta in BAPN+DNase Ⅰ group was decreased,the damage of vascular wall and the breakage of elastic fibers were relieved.Besides,the serum levels of citH3,cfDNA and nucleosome were decreased,and the formation of NETs in aorta in BAPN+DNase Ⅰ group was decreased.Additionally,the inflammation of aorta tissue and apoptosis of smooth muscle cell were significantly reduced,while the expression of SIRT1 signaling pathway was significantly up-regulated in BAPN+DNase Ⅰ group(P<0.01).Conclusion The occurrence of TAAD in mice is associated with the inhibition of SIRT1 signaling pathway by NETs,which subsequently upregulates inflammation in the thoracic aorta and promotes apoptosis of smooth muscle cell.Notably,the NETs scavenger DNase I can reduce the formation of TAAD and has a significant vascular protective effect.