Unraveling the Molecular Complexity of Myxomatous Mitral Valve Degeneration: Integrating Transcriptomic and miRNA Profiling Using Random Forests with Boruta Feature Selection

Background Myxomatous mitral valve disease (MMVD) is a degenerative disorder marked by excess tissue fibrosis and matrix remodeling, leading to leaflet prolapse. While recent studies linked transforming growth factor beta (TGF-β) activation to MMVD development and progression, upstream regulators of this and other modulatory/causal pathways remain largely unexplored. Objectives In this study, we utilized high-throughput sequencing to conduct unbiased analyses of mRNA and microRNA (miRNA) levels in myxomatous and healthy mitral valve tissues, aiming to uncover novel molecular mechanisms involved in MMVD. Methods We defined differentially expressed mRNAs and miRNAs transcripts displaying a fold-change > 1.5 and P < .05. Pathway analysis was performed using Ingenuity Pathway Analysis and DAVID, with key findings validated via qRT-PCR. A total of 2378 transcripts were differentially expressed between myxomatous and normal valves. Established pathways, including TGF-β signaling, were confirmed as major contributors to MMVD. Additionally, Random Forests with Boruta Feature Selection identified transcripts with a 95% likelihood of importance, and subsequent pathway analysis on this subset of genes revealed unique signaling pathways. Results Most notably, circadian rhythm disruption emerged as a novel, highly ranked pathway in MMVD. Key miRNAs, such as miR-1, miR-133a, and miR-217 were highlighted as highly relevant, with miRNA–mRNA interactions displaying distinct molecular signatures predictive of MMVD. Conclusions Collectively, this study represents the first comprehensive analysis of both miRNA and mRNA expression in MMVD, revealing both established and novel disease-associated pathways. The discovery of circadian rhythm disturbances and new regulatory miRNAs suggests promising directions for further research and potential therapeutic targets for nonsurgical treatment strategies in patients with MMVD.