IL‐38 treatment suppressed macrophage activities (Figure 4) and M1 macrophage accumulation in remodeling the aortic wall (Figure 2a–d) with lower MMP‐2 and ‐9 expression (Figure 2e–g), which reduced the AAA incidence (Figure 3) in angiotensin II‐induced AAA in C57BL6/J mice. Here, MMP2 is linked to triple-A syndrome.