Proteomic profiling reveals circulating biomarkers associated with aortic dilation in bicuspid aortic valve disease

Introduction Bicuspid aortic valve (BAV) is the most prevalent (1-2%) human congenital cardiac anomaly, predisposing to complications such as ascending aortic dilation (AAD). The progression of AAD is variable and challenging to predict, underscoring the need for reliable biomarkers to identify individuals at higher risk. Proteomic technologies allow the identification of protein expression patterns, providing potential avenues for non-invasive diagnostic and prognostic assessments, as well as insights into disease mechanisms. The hamster T inbred strain is the only spontaneous animal model of BAV disease. Animals show AAD associated with highly penetrant BAV in an isogenic background, what increases the stringency of proteomic analyses. A recent proteomic study of the aorta in this model proposed 27 potential candidate biomarkers pending to be tested in patients. Purpose We aimed to identify and test the viability of candidate diagnostic and/or prognostic biomarkers for AAD in BAV affected patients provided by the hamster model of BAV. Methods Mass spectrometry was performed on the serum and ascending aorta of hamsters (N=18), allowing the quantification of protein abundance in three groups of samples (T-BAV strain; T-TAV strain; TAV control strain). Subsequently, we integrated the proteomic datasets from both samples to identify a subset of differentially expressed proteins, which served as candidate markers. These candidates were then validated in the serum of a clinical cohort of patients (N=60) with BAV or TAV, both with and without AAD by targeted ELISA and multiplex assays. Results We identified 17 proteins exhibiting differential expression in both tissue samples of affected hamsters. From this, we prioritized seven proteins for further validation based on their potential relevance to aortic pathology. In the clinical cohort, five of these proteins demonstrated significant quantitative alterations in the serum of patients with BAV and AAD compared to BAV without AAD and TAV with or without AAD. These proteins are known to be involved in pathways related to extracellular matrix remodeling, inflammatory responses, and vascular smooth muscle cell function, all of which are critical processes in the pathogenesis of AAD. Conclusions Here we identified five differentially expressed proteins (Haptoglobin, Epidermal growth factor receptor, Immunoglobulin Lambda Constant, Immunoglobulin J chain and Hemoglobin beta) in the bloodstream of patients with BAV aortopathy with potential utility as non-invasive biomarkers for the diagnosis and risk stratification of aortic dilation in BAV patients. Early identification of individuals at elevated risk could facilitate timely clinical interventions, potentially mitigating the progression to severe aortic complications. Future studies are warranted to explore the mechanistic roles of these proteins in aortic pathology and to validate their clinical applicability in larger, diverse patient populations.