MMP1 and aortic aneurysm: For example IL-4, a cytokine classically produced by Th2 cells, has been proposed as protective in ATH, but IL-4 also increases the expression of P-selectin [24], VCAM-1, and matrix metalloprotease 1 and 12, which are implicated in aortic aneurysm formation and in acute coronary syndrome [25].