Abstract Body (Do not enter title and authors here): Background: Cardiovascular disease (CVD) causes more than 50% of deaths in patients with advanced chronic kidney disease (CKD). Clinical studies suggest that kidney-derived factors contribute to the development of CVD in CKD, independently of co-morbidities like hypertension and hyperglycemia. However, to date, no kidney-specific humoral risk factor that triggers direct cardiotoxicity has yet been identified, primarily due to the paucity of studies in patients with reno-cardiac disease. Here, we investigate how, in CKD patients, circulating extracellular vesicles (EVs) facilitate pathological kidney-heart communication, thereby causing cardiotoxicity, impairing cardiac function and contributing to heart failure (HF) progression.

Methods and results: EVs isolated from plasma of patients with CKD, but not healthy controls, were cardiotoxic, significantly inducing apoptosis both in vitro and in vivo and impairing contractility of adult primary CMs in vitro. Likewise, EVs isolated from both plasma and kidneys of adenine diet-induced CKD mice were also cardiotoxic. Pharmacologically depleting circulating EVs in CKD mice significantly recovered cardiac function and ameliorated HF, suggesting CKD-EVs play a causal role in HF pathogenesis. Small RNA sequencing and qPCR validation uncovered distinct miRNAs enriched in both human and mouse CKD-EVs, compared to Ctr-EVs. CKD-EV-miRNA mimics induced apoptosis of human AC16 myocytes and impaired contractility of iPSC- myocytes. Interestingly, levels of primary miRNAs corresponding to CKD-EV-miRNAs were significantly higher in CKD-kidney tissues, specifically in CD45-ve CD31-ve renal cells, but not in CKD-livers/lungs/PBMCs, a result that suggests that CKD-EV-miRNAs originate renally. Remarkably, CKD-EV-miRNA levels correlated with established markers of cardiac injury, uncovering the presence of sub-clinical heart disease and demonstrating heterogeneity in CKD patients not yet diagnosed with HF.

Conclusion: Collectively, human subject and mouse studies show that CKD-EVs, carrying distinct renal-derived miRNAs, mediate molecular crosstalk that contributes to the pathogenesis of HF in CKD. Consequently, CKD-EVs hold promise as diagnostic and prognostic biomarkers for early disease detection and as targets for novel therapeutic interventions in chronic reno-cardiac disease.