Previous studies found that degradation of the extracellular matrix in AAA was attributed to upregulated MMPs, particularly MMP2 and MMP9.40 Macrophage infiltration and chronic inflammation of the aortic wall are other pathological features of AAA.41 Therefore, we examined the protein expression of MMPs and inflammatory cytokines by western blotting and immunohistochemistry (Fig. 7c, d), which were markedly and significantly reduced by the inhibitor (P < 0.01, one-way ANOVA; Supplementary Fig. S7b, c). This evidence concerns the gene MMP9 and triple-A syndrome.