Iron promotes Slc7a11-deficient valvular interstitial cell osteogenic differentiation: A possible mechanism by which ferroptosis participates in intraleaflet hemorrhage-induced calcification

Background Calcific aortic valve disease (CAVD) is the most frequent pathogeny of aortic valve replacement in developed countries. Iron deposits are found in the intraleaflet hemorrhage (IH) areas of calcific aortic valves. Ferroptosis is a form of regulated cell death that involves metabolic dysfunction resulting from iron overload-dependent excessive lipid peroxidation. In this research, we attempted to clarify the role of ferroptosis in CAVD. Methods The level of ferroptosis in tissue and valvular interstitial cells (VICs) was assessed by the contents of 4-HNE, NADPH, ROS, and GSH, lipid peroxidation and mitochondrial morphology. The levels of calcification, iron accumulation and Slc7a11 expression in surgical aortic valve specimens were detected by Alizarin red or Von Kossa, Perl’s blue and immunohistochemical staining. The osteogenic differentiation of VICs was assessed by PCR and western blot analyses. Furthermore, RNA sequencing was used to detect potential differentially expressed genes between normal and osteogenic medium-treated (OM-treated) VICs. Results Our experiments demonstrated that ferroptosis occurred in the IH areas of calcific aortic valves. We also found that Slc7a11 was expressed at low levels in OM-treated VICs and IH areas. Finally, we demonstrated that iron promoted Slc7a11-deficient VICs osteogenic differentiation by aggravating ferroptosis in vitro. Conclusion In conclusion, iron promotes Slc7a11-deficient VIC osteogenic differentiation by aggravating ferroptosis in vitro, thereby accelerating the progression of aortic valve calcification. Statement Statements and opinions expressed in the articles and communications herein are those of the author(s) and not necessarily those of the Editor(s), Society, or publisher, and the Editor(s), Society, and publisher disclaim any responsibility or liability for such material. Brief Summary In this work, two novel notions have been proposed. First, we reported that ferroptosis participated in the progression of CAVD. Second, this is the first cytology experiment of valvular interstitial cells (VICs) to clarify the mechanism by which intraleaflet hemorrhage aggravates calve calcification. This research provides new ideas and targets for alleviating the progression of CAVD, especially in patients who have calcified aortic valves without severe stenosis.