Evaluation of Metabolism-Associated Proteins in Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) development is inversely associated with diabetes mellitus. Targeting glucose metabolism seems to be a beneficial strategy for preventing AAA growth. Several metabolism-related factors are associated with AAA development. This study aimed to analyse the expression of the so far unstudied proteins irisin, follistatin, activin A, and ghrelin (ligand and receptor) in human and murine aneurysmal tissue, to assess the involvement of these pathways in AAA.

Gene and protein expression was evaluated in aneurysmal and control tissue samples, by qPCR and immunohistochemistry. Vascular smooth muscle cells (VSMCs) were studied in vitro for expression. Circulating levels of the proteins of interest in human plasma samples were evaluated by ELISA.

In human aneurysmal tissue, the proteins of interest were predominantly expressed by VSMCs in neovessels. Expression by human VSMCs was confirmed in vitro. In human plasma, the concentration of irisin was higher in AAA (+/- diabetes) compared to controls. Patients with AAA and type 2 diabetes treated with metformin had lower levels of follistatin and ghrelin.

This study demonstrates irisin, follistatin, and ghrelin as interesting proteins to be studied in the context of the observed negative association between AAA development and type 2 diabetes.