MMP2 and triple-A syndrome: TNF-α deficiency also attenuates MMP-2 and MMP-9 expression by blocking macrophage activation.211,212 In AAA patients and in Ang-II-induced AA mice, TNF-α upregulated galectin-1 (Gal-1) in VSMCs and fibroblasts and subsequently induced MMP-9 expression.213 The use of klistatin inhibited TNF-α-induced oxidative stress and apoptosis, which in turn inhibited the development of AAA.214,215