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Updated: Aug 29, 2025
Isolation and Analysis of Aortic Arch and Root Lesions in an Atherosclerotic Mouse Model
Published on: February 14, 2025
Direct proteomic and high-resolution microscopy biopsy analysis identifies distinct ventricular fates in severe
Sören Brandenburg1, Lena Drews2, Hanne-Lea Schönberger2
1Clinic of Cardiology & Pneumology, University Medical Center Göttingen, Germany; Cellular Biophysics & Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Göttingen, Germany; Collaborative Research Center SFB1002 "Modulatory Units in Heart Failure", University of Göttingen, Germany.
Insights
This study reveals distinct molecular profiles in aortic valve stenosis (AS) subtypes using proteomic analysis. Specific protein changes correlate with different hemodynamic patterns and cardiomyocyte alterations in AS patients.
Area of Science:
- Cardiology
- Proteomics
- Molecular Biology
Background:
- Aortic valve stenosis (AS) incidence rises with age, leading to aortic valve replacement (AVR).
- AS presents diverse hemodynamic subtypes, from preserved to impaired left-ventricular function.
- The molecular basis for these AS subtypes and their impact on the heart muscle remains unclear.
Purpose of the Study:
- To identify unique protein expression profiles in different AS hemodynamic subtypes.
- To elucidate subtype-specific molecular mechanisms driving myocardial pathology in AS.
- To correlate proteomic findings with cardiomyocyte structure and function.
Main Methods:
- Direct proteomic analysis of left-ventricular endomyocardial biopsies from AS patients and controls using data-independent acquisition mass spectrometry (DIA-MS).
- Histomorphology and STimulated Emission Depletion (STED) superresolution microscopy of cardiomyocyte structure.
- Classification of AS subtypes based on echocardiographic parameters: normal ejection fraction (EF)/high-gradient, low EF/high-gradient, low EF/low-gradient, and paradoxical low-flow/low-gradient AS.
Main Results:
- DIA-MS identified 2273 proteins, with 160 showing significant abundance changes between AS subtypes and controls.
- Hierarchical clustering revealed distinct proteotypes defining three hemodynamic AS subtypes.
- Specific proteotypes correlated with cardiomyocyte hypertrophy, and superresolution microscopy showed RyR2-cluster fragmentation in patients with systolic dysfunction.
Conclusions:
- Proteomic analysis successfully differentiated AS hemodynamic subtypes based on unique molecular signatures.
- Disrupted RyR2 localization in cardiomyocytes is associated with systolic dysfunction in AS.
- These findings offer insights into subtype-specific AS pathogenesis and potential therapeutic targets.
Abstract:
The incidence of aortic valve stenosis (AS), the most common reason for aortic valve replacement (AVR), increases with population ageing. While untreated AS is associated with high mortality, different hemodynamic subtypes range from normal left-ventricular function to severe heart failure. However, the molecular nature underlying four different AS subclasses, suggesting vastly different myocardial fates, is unknown. Here, we used direct proteomic analysis of small left-ventricular biopsies to identify unique protein expression profiles and subtype-specific AS mechanisms. Left-ventricular endomyocardial biopsies were harvested from patients during transcatheter AVR, and inclusion criteria were based on echocardiographic diagnosis of severe AS and guideline-defined AS-subtype classification: 1) normal ejection fraction (EF)/high-gradient; 2) low EF/high-gradient; 3) low EF/low-gradient; and 4) paradoxical low-flow/low-gradient AS. Samples from non-failing donor hearts served as control. We analyzed 25 individual left-ventricular biopsies by data-independent acquisition mass spectrometry (DIA-MS), and 26 biopsies by histomorphology and cardiomyocytes by STimulated Emission Depletion (STED) superresolution microscopy. Notably, DIA-MS reliably detected 2273 proteins throughout each individual left-ventricular biopsy, of which 160 proteins showed significant abundance changes between AS-subtype and non-failing samples including the cardiac ryanodine receptor (RyR2). Hierarchical clustering segregated unique proteotypes that identified three hemodynamic AS-subtypes. Additionally, distinct proteotypes were linked with AS-subtype specific differences in cardiomyocyte hypertrophy. Furthermore, superresolution microscopy of immunolabeled biopsy sections showed subcellular RyR2-cluster fragmentation and disruption of the functionally important association with transverse tubules, which occurred specifically in patients with systolic dysfunction and may hence contribute to depressed left-ventricular function in AS.
