Relevance of inflammation and matrix remodeling in abdominal aortic aneurysm (AAA) and popliteal artery aneurysm (PAA) progression

Aneurysm is a multifactorial degenerative disease characterized by focal dilatation of blood vessels. Although abdominal aortic (AAA) and popliteal aneurysms (PAA) are the most common dilatative vascular diseases and share some features, a comparison between the different anatomical sites and the relative pathophysiological differences has not been established. In order to gain deeper insights to AAA and PAA, we have characterized the role of matrix remodelling, vascular cells phenotype depletion and the inflammatory process in both diseases. Results show a more extensive presence of T-cell, B-cell and monocyte-macrophage infiltration in AAA with respect to PAA. Concurring with this aspect, IL-6, IL-8 and MCP-1 are 10-fold increased in AAA. Moreover, MMP-9, and metalloproteinase inhibitor 3 (TIMP3) resulted up-regulated in AAA tissues. Regarding the catalytic activity, which is tightly related to the oxidative stress, we found an up-regulation of superoxide dismutase [Mn] mitochondrial (SODM), glutathione peroxidase 3 (GPX3) and peroxiredoxin-1 (PRDX1). Histological analyses clearly showed a massive elastin fragmentation in AAA. This may enhance the inflammatory response, which has a prevalent role in AAA, while PAA is mainly guided by a loss of the contractile phenotype. These findings suggest insight in these potentially devastating diseases in term of their progression, aiming to identify potential specific markers respectively for AAA and PAA treatment.