#3095 Pinpointing specific circulating microRNAs as putative biomarkers for chronic kidney disease and cardiovascular outcomes
Authors: Gómez Olalla Ramil , Carvalho Eduarda , Cerqueira Ana , Paulo Núria , Santos Janete , Moura Sara , Brandão Isabel , Almeida Maria Inês , Vasconcelos Manuel Pestana , Alencastre Ines 
Published: May 2024

Abstract

Background and Aims
Chronic kidney disease (CKD) affects over 10% of the worldwide population and entails a significant risk for cardiovascular disease (CVD), leading to an up to 500-fold increase in cardiovascular mortality in advanced stages. However, the pathophysiological mechanisms underlying kidney-heart intercommunication remain unknown. In recent years, microRNAs (miRNAs) emerged as critical regulators of gene expression and numerous miRNAs that have been implicated in both CKD and CVD pathogenesis. Still, so far, their role in kidney-heart crosstalk has not been addressed. In this study, we evaluated the expression of a panel of miRNAs in plasma from pre-dialysis CKD patients and explored their association with main comorbidities and significant outcomes in a 5-year follow up.

Method
The expression levels of miR-30c-5p, miR-132-3p, miR-199a-5p, and miR-324-3p was assessed by real time qRT-PCR in plasma samples from two cohorts of pre-dialysis CKD patients followed up at the Nephrology Department of Centro Hospitalar Universitário de São João (CHSJ, Porto, Portugal).The discovery cohort was established between November 2014 and August 2018 and comprises 52 CKD patients while the validation cohort comprises samples from 43 CKD patients who underwent a kidney biopsy for diagnostic purposes from November 2019 to December 2022. Patients with acute kidney injury, neoplasia diagnosis, recent infections (&lt;1 week), or known psychiatric disorders were excluded from the study. Plasma samples from 38 healthy blood donors, recruited at the Immunohemotherapy Department of CHSJ, in which creatinine values were measured and considered normal were used as controls. Participants with a history of cancer, inflammatory, or infectious diseases and who were being treated with anti-inflammatory or anti-depressive drugs, were excluded. MiRs expression in comparison with the controls was validated in both cohorts and its expression in the Discovery cohort was correlated with the patients clinical data in a 5 year follow up.

Results
Results show that miR-30c-5p and miR-132-3p were downregulated in CKD patients compared with healthy controls, presenting a significant power to discriminate the disease condition. Still, considering the stratification of CKD in early/moderate (1-3) and advanced stages (4-5), only miR-30c-5p presented a decreased expression in the initial stages of the disease, showing a significant diagnostic value as an early biomarker for CKD, independently of eGFR. When analyzing the major disease outcomes in a 5 year time, miR-199a-5p was associated with increased frequency of CVD and mortality while miR-324-3p was downregulated in CKD patients that progressed to worse stages.

Conclusion
These findings highlight miR-30c-5p as a potential biomarker for the diagnosis of CKD in early stages of the disease and identify, for the first time, the enrollment of miR-199a-5p and miR-324-3p in kidney-heart pathophysiological crosstalk, paving the way for the putative establishment of new biomarkers and therapeutic targets for CKD and its outcomes.