Circulating microRNAs as novel biomarkers for chronic kidney disease: insights from the South African community-based diabetes prevention study

The burden of chronic kidney disease (CKD) is growing rapidly, with a disproportionate burden seen in low- to middle-income countries (LMICs), including those in Africa, yet there are limitations in currently used diagnostic tools in the African populations. There is a need for improved strategies for primary and secondary prevention of CKD to reduce the risk or facilitate early detection. MicroRNAs (miRNAs), small non-coding RNAs involved in gene regulation, are increasingly showing potential as disease biomarkers; however, African populations remain underrepresented in these studies. This study aimed to investigate the association between selected circulating miRNAs and CKD status in adults of South Africa (SA).

The Diabetes Prevention Programme was implemented in communities across the Eastern Cape and Western Cape provinces of South Africa from 2022 to 2024. Adults aged 25 to 65 years were recruited through self-selection. The study included all samples from participants with chronic kidney disease (CKD) (40%) and additional samples from those without CKD (60%). CKD was defined as an estimated glomerular filtration rate (eGFR) of less than 60 ml/min/1.73 m² and/or an albumin-to-creatinine ratio (ACR) exceeding 3 mg/mmol, while albuminuria was defined as an ACR greater than 3 mg/mmol. MiRNA expression profiling was performed for miR-16-5p, miR-126-3p, miR-223-3p, and miR-21-5p. Firstly, total RNA was extracted from whole blood followed by reverse transcription to complementary DNA. Then, quantification of miRNA expression was conducted using TaqMan assays on a quantitative real-time PCR platform. Relative expression levels and fold changes were calculated using the ΔΔCT method, with miR-16-5p as the endogenous control. Multivariable regression analysis was employed to evaluate the relationships between miRNAs, CKD, and albuminuria.

This study included 294 participants, comprising individuals of mixed (40.6%) and black (59.4%) ancestries, with the majority being female (81.0%). Racial differences in miRNA expression were observed, with significantly higher levels of miR-126-3p in black individuals compared to those of mixed ancestry (p=0.0008). After adjusting for race, increased expression levels of miR-21-5p were associated with higher odds of CKD (p=0.038) and albuminuria (p=0.036). These associations remained significant after further adjustment for age and sex (p=0.037 and p=0.036, respectively), as well as for body mass index and waist-to-hip ratio (p=0.029 and p=0.032, respectively). A significant interaction between miR-21-5p and race in relation to CKD was also identified (All p<0.032). Neither miR-126-3p or miR-223-3p demonstrated an independent association with CKD or albuminuria, although miR-126-3p was positively correlated with eGFR (rho=0.12, p=0.0426).

This study provides evidence that circulating miRNAs are associated with CKD in a South African population. These findings highlight miR-21-5p as a promising biomarker for CKD risk stratification in African populations and underscore the importance of considering racial differences in biomarker research. Although this miRNA shows potential as a biomarker for CKD and albuminuria, further prospective studies are warranted to validate these associations and explore their potential clinical utility for early detection and prevention of CKD.