O7 Toll-like receptor 3 mediates osteoblastic phenotype switch in calcific aortic valve disease

Abstract Introduction Calcific aortic valve disease (CAVD) is caused by an osteoblastic phenotype switch of valvular interstitial cells (VICs), the predominant cell type in heart valves. However, trigger for remains unknown. Toll-like receptor 3 (TLR3) part innate immune system activated viral and endogenous RNA released from injured cells. We hypothesized that mechanical strain leads to TLR3 activation leading VICs with subsequent initiation CAVD. Methods Aortic valves were obtained patients undergoing replacement or explanted hearts. isolated treated agonist poly (I: C) a TLR3/dsRNA complex inhibitor. Osteoblastic gene expression was evaluated via sequencing. Cells challenged medium analyzed alkaline phosphatase activity calcific nodule formation. Zebrafish A Flexcell used apply VICs. morphology function aged wild-type (WT) TLR3-/- mice transthoracic echocardiography, microCT histological evaluation. To confirm results second model, experiments repeated ApoE-/- ApoE-/-/TLR3-/- mice. Results showed abundant expression. Mechanical stimulation resulted activation. Stimulation lead TNF-a, IL-6, IFN-y, IL-10, Runx2 BMP2 and, towards osteoblasts as revealed sequencing enhanced production. Mice age-dependent well derived CAVD increased compared healthy control Inhibition prevention osteogenic conditioned exhibited decreased calcification after inhibition. Aged WT significantly mean gradients velocity echocardiographs. MicroCT analyses thickened leaflets commissural atherosclerotic plaques. These changes missing completely age-matched under high fat diet clear signs opening diameters leaflet thickness. these findings Conclusion VICs, whereas inhibition prevents activity. patients. show no could become effective target pharmacological