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Superoxide dismutase protects against effects of eNOS uncoupling in early‐stage aortic valve disease (278.6)
Author(s) -
Farrar Emily,
Huntley Geoffrey,
Butcher Jonathan
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.278.6
Subject(s) - enos , superoxide dismutase , medicine , endocrinology , oxidative stress , nitric oxide , endothelium , superoxide , chemistry , nitric oxide synthase , biochemistry , enzyme
Objective: Oxidative stress (OxS) is known to contribute to late stages of aortic valve disease (AVD), but its role in early‐stage valve inflammation and as a driver of valve pathology has not been investigated. Here we show that inflammation drives increased OxS via eNOS uncoupling. Using an ex vivo model of AVD, we show that superoxide dismutase can block the downstream effects of eNOS uncoupling and mitigate later‐stage valve degeneration. Methods and Results: We first observed evidence of eNOS uncoupling in the endothelium of calcified human aortic valve leaflets, which had elevated dihydroethidium staining for superoxide in endothelial cells both near and distal to the primary nodule. We then used a 3‐D in vitro system to show that inflammatory cytokine TNF‐α caused increased superoxide, free radicals, and hydrogen peroxide in aortic valve endothelial cells, as soon as 15 minutes after treatment. The excess oxidative stress due to TNF‐α decreased VEC nitric oxide secretion, lowered eNOS and VE‐cadherin protein levels, and increased expression of inflammatory adhesion molecules (VCAM1, ICAM1). Addition of eNOS co‐factor tetrahydrobiopterin (BH4) mitigated the increases in OxS caused by TNF‐α, demonstrating the eNOS uncoupling was the primary pathophysiological mechanism at play. Using an ex vivo system of porcine aortic valve leaflets cultured for 21 days, we screened the ability of BH4, catalase, and superoxide dismutase (SOD) to decrease the endothelial OxS effects caused by TNF‐α. We found that all three antioxidants mitigated the effects of TNF‐α and improved endothelial function, but SOD showed the most significant reduction in protein levels of myofibroblastic protein α‐smooth muscle actin and VCAM1. Conclusions: These results present endothelial inflammatory oxidative stress as a new mechanism that connects early valve pathology with later stages of degeneration. Targeting these mechanisms via tailored antioxidant therapy could provide new avenues for treatment of CAVD. Grant Funding Source : Supported by NIH HL110328, NSF CBET‐0955172