MIRNA PROFILING OF URINARY EXOSOMES FOR PREDICTING RENAL OUTCOME AFTER ACUTE KIDNEY INJURY : A PILOT STUDY

Introduction:

Acute kidney injury (AKI) is a widespread burden of epidemic status. Patients who experienced delayed renal recovery from AKI are at higher risk of incident chronic kidney disease (CKD), progression to end-stage kidney disease (ESKD) and mortality. Urinary exosomal miRNA have gained important recognition as potential diagnostic biomarkers for AKI, however, there is no data on urinary exosomal miRNA and their association with renal outcome from AKI. We aim to study the urinary exosomal miRNA profiling and association of differentially expressed miRNA with renal outcome from AKI) at 4 months after hospital discharge.

Methods:

In this prospective observational study, stable patients of either sex, aged between 18-70 years, and diagnosed with community acquired AKI were enrolled at the time of hospital discharge. Patients with underlying CKD, obstructive uropathy, Glomerulonephritis, decompensated chronic liver failure, malignancy or heart failure were excluded. The patients were followed at 4th months after hospital discharge to assess the outcome (recovery and non-recovery). Renal non-recovery was defined as eGFR < 60 mL/min/1.73m2. Exosomes from urine samples at the time of discharge were isolated by ultracentrifugation method. Total RNA was extracted from urinary exosomes using Trizol method. QIAseq miRNA library kit was used for building miRNA sequencing libraries and small RNA were sequenced using NovaSeq Xplus. The data was aligned and analysed by using strand NGS V4.0. Differential expression analysis were performed using EdgeR. Identification of targets and pathway analysis were done by using ingenuity pathway analysis. 

Results:

A total of 200 patients were enrolled in this cohort. miRNA profiling was done in 10 recovered and 9 non-recovered patients. There was no significant difference in serum creatinine between renal recovery and renal non-recovery group at the time of discharge (4.7±2.9 mg/dl versus 5.8±1.3 mg/dl, p =0.29). At 4 month follow up, renal non-recovery group had higher serum creatinine value (6.3±3.6 mg/dl versus 0.9±0.2 mg/dl, p <0.001) and lower eGFR (30.0±6.3 ml/min/1.73m2 versus 97.5±11.7 ml/min/1.73m2, p <0.001 ) compared to renal recovery group. Total 1918 miRNA were identified out of which 54 miRNA were significant downregulated (fold change <=-2, p <0.05) and 6 significant upregulated miRNAs (fold change >=2, p <0.05) in renal non-recovery group. Figure 1 show the heat map of differentially expressed miRNAs. These differentially expressed miRNAs were analysed by IPA and identified 1768 mRNA targets. Core analysis of the plausible mRNA targets revealed that maximum number of mRNA (250 out of 1768) were associated with S100 family signalling pathway. 

Conclusions:

This study identifies significant differences in urinary exosomal miRNA expression between AKI patients with renal recovery and those with non-recovery. Validation of differentially expressed miRNAs are underway and it may lead to the identification of potential biomarkers in renal recovery after AKI. 

I have no potential conflict of interest to disclose.

I did not use generative AI and AI-assisted technologies in the writing process.