Abstract Fri138: TET2 Drives Osteogenic Differentiation of Aortic Valve Interstitial Cells Through a Catalytic-Independent Mechanism

Introduction: Clonal hematopoiesis of indeterminate potential (CHIP) has emerged as an important contributor to cardiovascular disease, most commonly driven by mutations in the epigenetic regulators TET2 and DNMT3A. Clinical cohort studies show that approximately one-third of patients with severe aortic valve stenosis (AVS) undergoing transcatheter aortic valve replacement (TAVR) harbor CHIP mutations, and TET2-associated CHIP is linked to increased all-cause mortality. However, the role of TET2 in calcific aortic valve disease (CAVD) beyond the hematopoietic system remains unclear. Hypothesis: We hypothesized that TET2 directly promotes aortic valve calcification by regulating osteogenic differentiation of valve interstitial cells (VICs). Methods: Primary VICs from healthy donors and patients with calcified aortic valves were analyzed to assess the relationship between TET2 expression and osteogenic differentiation using Alizarin Red staining, alkaline phosphatase (ALP) staining, and immunofluorescence. Complementary CAVD models, including LDLR - / - mice, wire injury induced valve damage, TET2 knockout mice, and AAV9-mediated cardiac-specific TET2 overexpression, were used to interrogate the causal effects of TET2 loss- and gain-of-function on valve calcification. Integrated transcriptomic and proteomic analyses were performed to explore molecular pathways associated with TET2-mediated VIC osteogenic differentiation. Results: TET2 expression was significantly upregulated during CAVD progression and increased in a time-dependent manner during osteogenic induction in vitro. Valve tissues displayed an epigenetic imbalance characterized by increased 5-methylcytosine (5mC) and reduced 5-hydroxymethylcytosine (5hmC) levels, which was recapitulated in patient-derived VICs. Genetic suppression of TET2 by knockdown or deletion markedly attenuated valve calcification in both in vitro and in vivo models, establishing TET2 as a pro-calcific regulator in CAVD. Conclusions: TET2 promotes aortic valve calcification through a non-canonical, demethylation-independent mechanism in which its catalytic domain is dispensable. Targeting TET2 suppresses VIC osteogenic differentiation, suggesting a potential therapeutic strategy for calcific aortic valve disease.