Elastase-2 Knockout Is Associated With Less Susceptible Aorta Dilation in Response to Angiotensin Ii Stimulation in the Mice Model

Objective: Elastase-2 (ELA-2), a chymotrypsyn-serine protease elastase family member 2A, is expressed in several tissues such as the lungs, heart, liver, kidneys, brain, and vessels. ELA-2 was found to generate angiotensin II (AngII) in arteries and contribute to resistance arteries and vascular remodeling in animal models. It has also been shown that continuous infusion of AngII induces abdominal aortic aneurysm (AAA) in mice. Therefore, we sought to investigate the role of ELA-2 in an aortic dilation, which is a risk factor to AAA development, in a mouse model. Design and method: Male wild type (C57bl/6, WT) and ELA-2 knockout (CELA-2aTm1Bdr; ELA-2 KO) mice were treated with saline or angiotensin II (AngII, 2.28 g/g/min) for twenty-eight days by subcutaneously mini-pumps infusion. To evaluate the role of elastase-2 in a AAA development, mice were divided into four groups: WT treated with saline (WT+SAL), ELA-2KO treated with saline (ELA-2KO+SAL), WT treated with AngII (WT+AngII), and ELA-2KO treated with Ang II (ELA-2KO+AngII). The vascular ultrasound (US) was done before treatment and once a week during 28 days of treatment. The abdominal aorta measurements such as maximum aortic diameter, aortic para-renal diameter, aortic infra-renal diameter, and aortic supra-renal diameter were collected. A dilated aorta is a risk factor aortic rupture/aneurysm. Statistical analyses were performed by the Shapiro Wilk Normality test, two-way ANOVA with Sidak's multiple comparisons test. This study is approved by the Ethics Committee (CEUA-131/2019). Results: The most dilated aorta as measured by the maximum aorta diameter was detected in WT+AngII group and was 60% higher than in the WT+Saline (p = 0.01). There was no significant difference in the maximum aorta diameter between ELA-KO+SAL vs. ELA-2KO+AngII (p = 0.8). The measurement of dilation in aortic para-renal and aortic infra-renal showed that AngII induced a dilation in WT+AngII (p < 0.05), while not modified these parameters in ELA-2KO+AngII group. The aortic supra-renal diameter parameters and weight showed no differences between groups. Conclusions: These results suggest that ELA-2KO mice might be less susceptible to develop an aorta dilation. Therefore, Elastase-2 is a candidate factor that contributes to the formation and/or development of abdominal aortic aneurysm.