Tissue and plasma proteomic profiling indicates AHSG as a potential biomarker for ascending thoracic aortic aneurysms.

Background: Thoracic Aortic Aneurysms (TAAs) develop asymptomatically and are characterized by dilatation of the aorta. This is considered a life-threatening vascular disorder due to the risk of aortic dissection and rupture. There is an urgent need to identify blood-borne biomarkers for the early detection of TAA. The goal of the present study was to identify potential protein biomarkers associated with TAAs, using proteomic analysis of aortic tissue and plasma samples.

Methods: Extracted proteins from 14 aneurysmal and 12 non-aneurysmal thoracic aortic tissue specimens as well as plasma samples from six TAA patients collected pre-and postoperatively and six healthy controls (HC), were analyzed by liquid chromatography-tandem mass spectrometry. Proteomic data were further processed and following filtering criteria, one protein was selected for verification and validation in a larger cohort of patients and controls using a targeted quantitative proteomic approach and enzyme-linked immunosorbent assay, respectively.

Results: A total of 1593 and 363 differentially expressed proteins were identified in tissue and plasma samples, respectively. Pathway enrichment analysis on the differentially expressed proteins revealed a number of dysregulated molecular pathways that might be implicated in aneurysm pathology including complement and coagulation cascades, focal adhesion, and extracellular matrix receptor interaction pathways. Alpha-2-HS glycoprotein (AHSG) was selected for further verification in 36 TAA and 21 HC plasma samples using targeted quantitative proteomic approach. The results showed a significantly decreased concentration of AHSG (p = 0.0002) in the preoperative plasma samples compared with HC samples. Further analyses using a larger validation dataset revealed that AHSG protein levels were significantly lower (p = 0.03) compared with HC. Logistic regression analysis on the validation dataset revealed males, advanced age, hypertension and hyperlipidaemia as significant risk factors for TAA.

Conclusion: AHSG concentrations distinguish plasma samples derived from TAA patients and controls. The findings of this study suggest that AHSG may be a potential biomarker for TAA that could lead to better diagnostic capabilities.