Rationale: Aortic valve stenosis (AVS), the most common valvular heart disease, is characterized by progressive calcification and inflammation. With transcatheter aortic valve replacement (TAVR) as the sole effective treatment, the urgent need for novel therapeutic targets is apparent. Long non-coding RNAs (lncRNAs) are crucial epigenetic regulators, yet their role in AVS remains largely unexplored. Our preliminary transcriptomic data from calcified human aortic valves identified a significant upregulation of MIAT and MEG3, lncRNAs implicated in fibrosis and endothelial dysfunction. This study investigates their specific contribution to AVS pathogenesis to identify new RNA-based diagnostic and therapeutic strategies.
Methods and Results: Using primary human valvular interstitial (VICs) and endothelial cells (VECs) from calcified and non-calcified valves, we performed siRNA-mediated knockdown of MIAT and MEG3. Silencing either lncRNA reduced cellular senescence and cytotoxicity without affecting viability. Functional assays revealed that knockdown attenuated VIC proliferation and migration, and impaired VEC angiogenic capacity. To model AVS pathogenesis, we induced endothelial-to-mesenchymal transition (EndMT) in VECs and calcification in VICs. siMIAT and siMEG3 potently suppressed key EndMT markers (ACTA2, TAGLN, COL1A1) in VECs and downregulated osteogenic drivers (BMP2, RUNX2, BGLAP) in VICs, indicating a profound amelioration of core disease phenotypes. Furthermore, intercellular communication studies via extracellular vesicles (EVs) and co-culture models demonstrated that silencing MIAT or MEG3 in donor VECs significantly reduced inflammatory markers (IL-6, TGF-β, ICAM-1, VCAM-1) in recipient VICs. An integrated in silico and proteomic approach identified caspase-3, p53, and HIF1α as potential downstream effectors mediating these lncRNA-driven inflammatory and calcification pathways.
Conclusion and Outlook: Our findings establish MIAT and MEG3 as critical promoters of calcification and EndMT in AVS. Their silencing restores endothelial integrity and mitigates osteogenic differentiation, positioning them as promising therapeutic targets. Future work will employ RNA immunoprecipitation sequencing (RIP-seq) and pulldown assays to delineate the precise molecular mechanisms, supported by validation in valvular organoids and murine models, to translate these findings towards clinical application.
