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

Abstract

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) or progressive (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), α1-antitrypsin (α1-AT) and Factor XII activity) showed strong correlation with D max. Size combined with either Factor XII activity or α1-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 α1-antitrypsin are found in increased amounts in the serum of patients with expanding AAA. However, combination of either Factor XII or α1-antitrypsin with aneurysm diameter had little effect on prediction of aneurysm progression versus diameter alone.