Congenital aortic valve stenosis (AS) progresses as an obstructive narrowing of the aortic orifice due to deregulated extracellular matrix (ECM) production by aortic valve (AV) leaflets and leads to heart failure with no effective therapies. Changes in glycoprotein and proteoglycan distribution are a hallmark of AS, yet valvular carbohydrate content remains virtually uncharacterized at the molecular level. While almost all glycoproteins clinically linked to stenotic valvular modeling contain multiple sites for N-glycosylation, there are very few reports aimed at understanding how N-glycosylation contributes to the valve structure in disease. Here, we tested for spatial localization of N-glycan structures within pediatric congenital aortic valve stenosis. The study was done on valvular tissues 0–17 years of age with de-identified clinical data reporting pre-operative valve function spanning normal development, aortic valve insufficiency (AVI), and pediatric endstage AS. High mass accuracy imaging mass spectrometry (IMS) was used to localize N-glycan profiles in the AV structure. RNA-Seq was used to identify regulation of N-glycan related enzymes. The N-glycome was found to be spatially localized in the normal aortic valve, aligning with fibrosa, spongiosa or ventricularis. In AVI diagnosed tissue, N-glycans localized to hypertrophic commissures with increases in pauci-mannose structures. In all valve types, sialic acid (N-acetylneuraminic acid) N-glycans were the most abundant N-glycan group. Three sialylated N-glycans showed common elevation in AS independent of age. On-tissue chemical methods optimized for valvular tissue determined that aortic valve tissue sialylation shows both α2,6 and α2,3 linkages. Specialized enzymatic strategies demonstrated that core fucosylation is the primary fucose configuration and localizes to the normal fibrosa with disparate patterning in AS. This study identifies that the human aortic valve structure is spatially defined by N-glycomic signaling and may generate new research directions for the treatment of human aortic valve disease.
Bibliographical noteFunding Information:
Funding provided specifically for this work by the American Heart Association ( 16GRNT31380005 ) to PMA with additional support by the NIH/NIGMS ( P20 GM103542 ) and National Center for Advancing Translational Sciences UL1 TR000445 , which supported initial studies for the project. PMA is enormously grateful to HSB for early career mentoring on valve development and biology. CLC supported by HL007260 ( NIH/NHLBI ). Support to RRD provided NCI/IMAT ( 1R21CA207779 ) and by the South Carolina Centers of Economic Excellence SmartState program .
© 2021 Elsevier Ltd
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- Aortic valve
- Congenital aortic valve stenosis
- Extracellular matrix
- Imaging mass spectrometry
- MALDI imaging mass spectrometry
- Tissue imaging
- Valve development
ASJC Scopus subject areas
- Molecular Biology
- Cardiology and Cardiovascular Medicine