Role for Galectin-3 in Calcific Aortic Valve Stenosis.

Background: Aortic stenosis (AS) is a chronic inflammatory disease, and calcification plays an important role in the progression of the disease. Galectin-3 (Gal-3) is a proinflammatory molecule involved in vascular osteogenesis in atherosclerosis. Therefore, we hypothesized that Gal-3 could mediate valve calcification in AS.
Methods and Results: Blood samples and aortic valves (AVs) from 77 patients undergoing AV replacement were analyzed. As controls, noncalcified human AVs were obtained at autopsy (n=11). Gal-3 was spontaneously expressed in valvular interstitial cells (VICs) from AVs and increased in AS as compared to control AVs. Positive correlations were found between circulating and valvular Gal-3 levels. Valvular Gal-3 colocalized with the VICs markers, alpha-smooth muscle actin and vimentin, and with the osteogenic markers, osteopontin, bone morphogenetic protein 2, runt-related transcription factor 2, and SRY (sex-determining region Y)-box 9. Gal-3 also colocalized with the inflammatory markers cd68, cd80 and tumor necrosis factor alpha. In vitro, in VICs isolated from AVs, Gal-3 induced expression of inflammatory, fibrotic, and osteogenic markers through the extracellular signal-regulated kinase 1 and 2 pathway. Gal-3 expression was blocked in VICs undergoing osteoblastic differentiation using its pharmacological inhibitor, modified citrus pectin, or the clustered regularly interspaced short palindromic repeats/Cas9 knockout system. Gal-3 blockade and knockdown decreased the expression of inflammatory, fibrotic, and osteogenic markers in differentiated VICs.
Conclusions: Gal-3, which is overexpressed in AVs from AS patients, appears to play a central role in calcification in AS. Gal-3 could be a new therapeutic approach to delay the progression of AV calcification in AS.
(© 2016 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)