Abstract 141: Lesion Site-specific Mass Spectrometry Analysis Of Human Carotid Plaques Reveals Strongest Association Of The Necrotic Core And Fibrous Cap Proteome With Plaque Stability

The spatial impact of the plaque proteome on atherosclerotic plaque stability remains largely unknown. In this study, we performed mass spectrometry-based proteomics of various carotid plaque subregions (media, necrotic core, fibrous cap), using guided laser capture micro-dissections (LCM) of FFPE tissue in a matched cohort of 112 patients undergoing carotid endarterectomy (CEA) to study the impact of the plaque proteome, not only on lesion stability, but also on subregional changes of expression. Further, we performed a histological analysis according to the AHA classification and combined the data with clinical information on risk factors, comorbidities, and patient symptoms. Our LCM mass spectrometry analysis yielded over 3000 proteins for each plaque subregion. Gene set enrichment analysis revealed a high abundance of extracellular proteins and vice versa for cellular proteins. Subregion analysis identified the necrotic core and the fibrous cap to display the most significant changes in proteins associated with the stability status, whereas the media proteome remained largely unaffected. Primary and secondary enrichment analysis revealed synthetic vascular smooth muscle cells as the major source of these proteins. In addition, we analyzed the serum proteome of more than 500 patients (including non-athero control patients) with overlap from the tissue cohort. We combined these with histological evaluation and a complete set of clinical data. We used these two datasets for developing tissue and serological markers associated with plaque stability. In summary, our approach utilized LCM mass spectrometry, histological evaluation, and clinical data to analyze the association of different lesion subregions on plaque stability. We are able to demonstrate a high through-put method to identify potential protein markers relevant to atherosclerotic plaque stability.