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

ObjectiveThe 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 (Dmax) and progression.MethodsTwo-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 (Dmax 30–54 mm) AAA, either stable (increase Dmax <5 mm year−1; n = 8) or progressive (increase Dmax ≥5 mm year−1; n = 8), and large (Dmax ≥55 mm; n = 8) AAA. The identified proteins were quantitatively validated in a larger population (n = 80).ResultsSeveral 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 Dmax. 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).ConclusionThe 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.