Correlation analysis revealed that either TLR4 or MMP9 expression level in AAA tissues was statistically associated with circulating C-reactive protein (CRP) (r = 0.419 and 0.352, respectively; all P < 0.05), and a significant correlation was also observed between TLR4 and MMP9 expression level (r = 0.767, P < 0.001) (Table 4). Here, MMP9 is linked to triple-A syndrome.