ROLE OF METALLOPROTEINASES AND ROS GENERATION IN THE AORTA OF ELASTASE-2 KNOCKOUT MICE IN ABDOMINAL AORTIC ANEURYSM MODEL

Abstract

Objective: Elastase-2 (ELA-2) enzyme generates angiotensin-II (AngII) in arteries and is implicated in abnormal vascular remodeling in animal models. Our group demonstrated previously that ELA-2 knockout (ELA-2KO) mice were less susceptible to developing an aorta dilation in response to AngII infusion. This study hypothesizes that metalloproteinases and ROS generation in ELA-2KO mice mediate less susceptibility to aorta dilation and abdominal aortic aneurysm (AAA). Design and method: Male wild type (C57bl/6, WT) and ELA-2KO (CELA-2aTm1Bdr) mice were treated with either saline or AngII (2.28g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. Mice were divided into four groups: WT treated with saline (WT+SAL, n = 5), ELA-2KO treated with saline (ELA-2KO+SAL, n = 5), WT treated with AngII (WT+AngII,n = 5), and ELA-2KO treated with AngII (ELA-2KO+AngII, n = 5). The vascular ultrasound (US) was done before treatment and once a week during 28 days of treatment. The MMP- 2 and MMP-9 analyzes were done by zymography, ROS generation by DHE analyses, and alfa-actin expression by immunofluorescence in all aorta mice groups. ANOVA and Kruskal Wallis tests were used to compare the average between groups. This study is approved by CEUA (n.131/2019). Results: AngII treatment was associated with increased MMPs expression in the WT group aorta (WT+AngII vs. WT+SAL p<0.05). The aorta ELA-2KO group showed no difference in MMPs in response to AngII infusion compared to ELA-2KO+SAL group (p = 0.81). The ROS generation had upregulated in aorta ELA-2KO+Ang II mice compared to ELA-2KO+SAL (p<0.001) and aorta WT+AngII compared with WT+SAL (p<0.0001). AngII treatment was associated with decreased ROS generation in the aorta ELA-2KO+AngII group compared with WT+AngII (p = 0.0051). The alfa-actin expression was similar in all groups. Our data demonstrate that AngII treatment did not increase the expression of MMPs in aorta ELA-2KO but was associated with an upregulation for ROS generation. Conclusions: Taken together, this suggests that ELA-2KO mice's resistance to developing an aorta dilation/AAA is related to MMPs and ROX generation. Our results also highlight the importance of the local/tissue response in the pathophysiology of AAA.