Utilising the elastase-induced mouse AAA model and examining the infrarenal abdominal aorta, Mmp9 and Mmp4 were identified as enriched genes across multiple monocyte/macrophage subpopulations, with Mmp9 highly expressed in a specific subpopulation termed “aortic-resident” and characterised through expression of Cx3cr1 and Flt3, which decreased proportionally in elastase-treated mice (163). Here, MMP9 is linked to triple-A syndrome.