MMP12 and achalasia-alacrima syndrome: Increased MMP-12 expression is observed in human atherosclerotic and AAA samples relative to healthy aortae [24], and recent evidence has demonstrated restricted MMP-12 expression within a macrophage subset involved in atherosclerosis [25], indicating that MMP-12 may represent a valid therapeutic target to retard the formation and progression of atherosclerotic AAAs.