Differential Protein Expression in Serum of Abdominal Aortic Aneurysm Patients - A Proteomic Approach

Objective: The aim of the study is to investigate the differential expression of proteins in serum of abdominal aortic aneurysm (AAA) patients in relation to aneurysm size (D(max)) and progression. Methods: Two-dimensional differential in-gel electrophoresis (2D-DIGE) together with tandem mass spectrometry (MS/MS) was used to analyse the serum proteome from patients with small (D(max) 30-54 mm) AAA, either stable (increase D(max) = 5 mm year(-1); n = 8), and large (D(max) >= 55 mm; n = 8) AAA. The identified proteins were quantitatively validated in a larger population (n = 80). Results: Several proteins were differentially expressed in serum of small stable, small progressive and large AAA. Three validated proteins (immunoglobulin G (IgG), alpha 1-antitrypsin (alpha 1-AT) and Factor XII activity) showed strong correlation with D(max). Size combined with either Factor XII activity or alpha 1-antitrypsin had minimal effect on the prognostic value in predicting aneurysm progression compared with size alone (area under the curve (AUC), 0.85; 95% confidence interval (CI), 0.73-0.97; p <0.001 and AUC, 0.85; 95% CI, 0.72-0.98; p <0.001 vs. AUC, 0.83; 95% CI, 0.71-0.96; p <0.001, respectively). Conclusion: The present study indicates that both Factor XII and alpha 1-antitrypsin are found in increased amounts in the serum of patients with expanding AAA. However, combination of either Factor XII or alpha 1-antitrypsin with aneurysm diameter had little effect on prediction of aneurysm progression versus diameter alone.