Long non-coding RNA MIAT and MEG3 are crucial regulators of inflammation and calcification in aortic valve stenosis

Introduction Aortic valve stenosis (AVS) is the most prevalent valvular heart disease, characterized by chronic inflammation and progressive calcification. As transcatheter aortic valve replacement (TAVR) remains the only effective treatment, novel therapeutic targets are urgently needed. Long non-coding RNAs (lncRNAs) have emerged as key regulators of gene expression through epigenetics and post-transcriptional mechanisms, yet their roles in AVS remain largely unexplored. Our preliminary transcriptomic data from calcified human aortic valves identified a significant upregulation of MIAT and MEG3, lncRNAs implicated in fibrosis, atherosclerosis, and endothelial dysfunction. Purpose This study elucidates the functional roles and molecular pathways of MIAT and MEG3 in AVS pathogenesis to evaluate their potential as lncRNA-based therapeutic targets. Methods Primary human valvular interstitial (VICs) and endothelial cells (VECs) isolated from calcified and non-calcified valves were subjected to siRNA-mediated knockdown of MIAT and MEG3. To model AVS pathogenesis, endothelial-to-mesenchymal transition (EndMT) was induced in VECs using TGF-β and IL-1β stimulation. VICs calcification was induced using osteogenic medium, supplemented with dexamethasone, L-ascorbic acid, glycerol-2-phosphate, and separately by pro-calcifying NaH2PO4 treatment. Results Silencing either MIAT or MEG3 attenuated VEC migration and impaired angiogenic capacity, consistent with suppression of EndMT as shown by downregulation of mesenchymal marker ACTA2, while restoring endothelial marker CD31. In VICs, siMIAT and siMEG3 potently suppressed osteogenic drivers (BMP2, RUNX2) and reduced calcification, indicating an 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 diminished inflammatory signaling in recipient VICs as depicted by significant decrease of IL-6, TGF-β, ICAM-1, and VCAM-1 expressions. Bulk RNA sequencing on valvular cells following lncRNAs knockdown revealed significant dysregulation of pro-fibrotic genes COL1A1 and TAGLN. An integrated in silico and proteomic analyses identified caspase-3, p53, and HIF1α as potential downstream effectors mediating these lncRNA-driven inflammatory and calcification pathways. Conclusion MIAT and MEG3 are critical promoters of EndMT, inflammation, and calcification in AVS. Their silencing restores endothelial integrity and mitigates osteogenic differentiation, highlighting their potential as promising therapeutic targets. Ongoing mechanistic studies employing RNA immunoprecipitation sequencing (RIP-seq), pulldown assays, and validation in valvular organoid and murine models will further delineate the specific molecular mechanisms and translate these findings towards clinical application.