Comparative Proteomic Investigation of Plasma Reveals Novel Potential Biomarker Groups for Acute Aortic Dissection

Abstract

Acute aortic dissection (AAD) is a catastrophic cardiovascular disease with high disability and mortality due to multiple fatal complications. However, the molecular changes of the serum proteome after AAD are not very clear. Here, we performed isobaric tags for relative and absolute quantitation- (iTRAQ-) based comparative proteomic analysis to investigate the proteome profile changes after AAD by collecting plasma samples from 20 AAD patients and 20 controls. Out of the 345 identified proteins, 266 were considered as high-quality quantified proteins (95%confident peptides ≥ 2), of which 25 proteins were accumulated and 12 were reduced in AAD samples. Gene ontology enrichment analysis showed that the 25 AAD-accumulated proteins were enriched in high-density lipoprotein particles for the cellular component category and protein homodimerization acidity for the molecular function category. Protein-protein interaction network analysis showed that serum amyloid A proteins (SAAs), complement component proteins, and carboxypeptidase N catalytic chain proteins (CPNs) possessed the key nodes of the network. The expression levels of six selected AAD-accumulated proteins, B2-GP1, CPN1, F9, LBP, SAA1, and SAA2, were validated by ELISA. Moreover, ROC analysis showed that the AUCs of B2-GP1 and CPN1 were 0.808 and 0.702, respectively. Our data provide insights into molecular change profiles in proteome levels after AAD and indicate that B2-GP1 and CPN1 are potential biomarkers for AAD.

Figure 1

Heatmap and gene ontology classification of 37 differentially abundant proteins between AAD and normal controls. (a) The expression pattern of each protein in 3 pooled AAD patient samples (AAD 1–3) and 3 pooled normal control samples (control 1–3). The ID of the protein groups is listed on the right and the hierarchy cluster tree is shown on the left. Red boxes indicate higher expression level, blue indicates lower expression level, and yellow indicates the same expression level compared with the control. The gene ontology categories of biological process (b), cellular component (c), and molecular function (d). The GO ID and term for each section is indicated.

Figure 2

Enrichment analysis of 25 induced proteins. Tree view of gene ontology cellular component (a) and molecular function (b) categories. GO terms are represented by boxes. Yellow boxes indicate significant GO terms. The FDR P values and numbers of DEPs for each GO term are also shown, and arrows are used to connect GO terms. Black dashed arrows indicate two nonsignificant GO terms; red arrows indicate two significant GO terms; black solid arrows indicate one significant and one nonsignificant GO term.

Figure 3

Protein-protein interaction network analysis of 37 differentially abundant proteins (a), 25 AAD-induced proteins (b), and 12 AAD-reduced proteins (c). Colored lines between the proteins indicate the various types of interaction evidence. Protein nodes which are enlarged indicate the availability of 3D protein structure information.

Figure 4

ELISA and receiver operating characteristic (ROC) curve analyses using the serum levels of B2-GP1, CPN1, F9, LBP, SAA1, and SAA2 in AAD patients and normal controls. (a) ELISA assays were performed to validate the serum levels of six DEPs in expanded samples of AAD patients and controls. ROC curves of B2-GP1, CPN1, and SAA1 are shown in panels (b), (c), and (d), respectively. The AUCs of B2-GP1, CPN1, and SAA1 are 0.808, 0.702, and 0.623, respectively.