Salivary Extracellular Vesicle- associated LncRNAs As Novel Non-invasive Biomarkers For Acute Decompensated Heart Failure: The Pioneering SEAL-HF Study

Acute Decompensated Heart Failure (ADHF) is a major global health concern, and early diagnosis is critical for effective management. Non-invasive biomarkers have the potential to improve patient outcomes substantially. In this study, we investigated the presence of extracellular vesicle (EV)-associated long non-coding RNAs (lncRNAs) in plasma of ADHF patients and explored their non-invasive detection in saliva as the foundation of the SEAL-HF study. We performed RNA-sequencing on plasma-derived EVs from ADHF patients at admission and discharge and healthy controls to identify differentially expressed lncRNAs and mRNAs, using a fold change cutoff of ±1.5 and an adjusted p-value of <0.05. Subsequent validation was carried out via qRT-PCR on plasma EV RNA samples from 182 patients. Salivary EVs were isolated and enriched, and their EV RNA content was profiled. Transcriptomic analysis unveiled several dysregulated EV-derived mRNAs and lncRNAs in ADHF patients compared to controls. Importantly, four lncRNAs (LINC00989, lnc-CALML5, AC092656.1, and RMRP) exhibited significant changes between the acute congestive phase and decongestion after diuresis and were found to circulate mainly within the EV compartment. Salivary EVs contained EV protein markers ALIX, CD81, and heart-derived protein marker Troponin T. qRT-PCR assay demonstrated the presence of LINC00989, lnc-CALML5, AC092656.1, and RMRP in salivary EVs, as well as cardiac-specific genes such as PLN. Our results highlight the potential of salivary EV-associated lncRNAs as non-invasive biomarkers for ADHF diagnosis, laying the groundwork for the SEAL-HF study and future clinical applications.