We next examined intra-aortic gene expression of MMPs and TIMPs, which are presumed to be involved in aortic aneurysm formation12,13,15,29,30 and observed that Ccl3−/− mice exhibited significantly enhanced intra-aortic Mmp9 mRNA expression compared with WT mice (Fig. 2e). This evidence concerns the gene CCL3 and aortic aneurysm.