Upregulation of the 5-lipoxygenase pathway in human aortic valves correlated inversely with aortic valve area (r= -0.52; P=0.007), suggesting a role for inflammation in aortic stenosis.
Observational (n=68)
Upregulation of the leukotriene pathway correlates with aortic stenosis severity and induces calcification and oxidative stress in valvular myofibroblasts, suggesting an inflammatory mechanism in disease progression.
Effect estimate: r= -0.52
p-value: p=0.007
BACKGROUND: The development of aortic valve stenosis is not only associated with calcification and extracellular matrix remodeling, but also with inflammation. The aim of this study was to determine the role of proinflammatory signaling through the leukotriene (LT) pathway in aortic stenosis. METHODS AND RESULTS: After macroscopic dissection of surgically removed human aortic valves, RNA was extracted from 311 preparations derived from 68 patients to differentiate normal, thickened, and calcified areas from each cusp. Subsequently, quantitative polymerase chain reaction analysis was used to correlate gene expression patterns with preoperative echocardiographic parameters. The messenger RNA levels of the LT-forming enzyme 5-lipoxygenase increased 1.6- and 2.2-fold in thickened and calcified tissue, respectively, compared with normal areas of the same valves. In thickened tissues, messenger RNA levels for 5-lipoxygenase (r= -0.35; P=0.03), its activating protein (5-lipoxygenase activating protein; r= -0.39; P=0.02), and LTA(4) hydrolase (r= -0.48; P=0.01) correlated inversely with the velocity-time integral ratio. In addition, leukotriene A(4) hydrolase transcripts correlated inversely with aortic valve area, indexed for body surface area (r= -0.52; P=0.007). Immunohistochemical stainings revealed LT receptor expression on valvular myofibroblasts. In primary cultures of human myofibroblasts derived from stenotic aortic valves, Leukotriene C(4) (LTC(4)) increased intracellular calcium, enhanced reactive oxygen species production, reduced the mitochondrial membrane potential, and led to morphological cell cytoplasm changes and calcification. CONCLUSIONS: The upregulation of the LT pathway in human aortic valve stenosis and its correlation with clinical stenosis severity, taken together with the potentially detrimental LT-induced effects on valvular myofibroblasts, suggests one possible role of inflammation in the development of aortic stenosis.
Nagy et al. (Tue,) conducted a observational in Aortic valve stenosis (n=68). 5-lipoxygenase pathway upregulation vs. Normal valve tissue was evaluated on Correlation of 5-lipoxygenase pathway gene expression with preoperative echocardiographic parameters (r= -0.52, p=0.007). Upregulation of the 5-lipoxygenase pathway in human aortic valves correlated inversely with aortic valve area (r= -0.52; P=0.007), suggesting a role for inflammation in aortic stenosis.