Small but mighty?: microRNAs as biomarkers for Acute Kidney Injury after Cardiac Surgery

ABSTRACT NUMBER: NESTAC_06

 

AUTHORS
Joseph Battle1, Lucy Bates1,2, Professor Neil Sheerin1,2, Professor John Dark1,2

AFFILIATIONS
1 Newcastle University, 2 Freeman Hospital

CORRESPONDING AUTHOR CONTACT EMAIL
ku.oc.liamtoh@elttabeoj

MAIN ABSTRACT TEXT

Introduction
Acute Kidney Injury (AKI) is common post-cardiac surgery, with up to 30% of cardiac surgery patients going on to develop an AKI. Currently clinicians use Serum Creatinine or oliguria for diagnosis; however, both have limitations. microRNAs provide a potential alternative. This study aims to compare more established biomarkers for AKI, NGAL and KIM-1, with microRNAs.

Method
15 patients undergoing cardiac surgery had blood and urine specimens collected prior to and 24-hours post-surgery. microRNA 21, 24 and 145 levels were determined by qRT-PCR and normalised to microRNA 39 from Caenorhabditis elegans. NGAL and KIM-1 levels were measured using a sandwich ELISA. Diagnosis of post-surgical AKI was made in accordance with the KDIGO guidelines. Patients were followed-up for 7 days post-surgery. Patients were divided into three groups: no AKI (nAKI), Cardiac surgery AKI (AKI) and Cardiac Transplant AKI (VADHTx). We established the association between biomarker levels and AKI by estimating the area under the curve (AUC) for receiver operating characteristic (ROC) curves.

Results
24-hour urinary NGAL levels (p=0.035) were significantly increased from baseline levels in the VADHTx group. There was no significant upregulation in the levels of miRNAs at 24-hours from baseline in any group. ROC curve analysis indicated that only 24-hour levels of plasma NGAL (AUC=0.92, p=0.01011) and plasma miRNA 145 (AUC=0.86, p=0.02749) had significant prognostic predictive power for AKI.

Conclusion
This study has shown that microRNAs were not a comparable biomarker for AKI to NGAL. Plasma microRNA 145 was the only microRNA that provided any indication for further research.