Abstract Body: Introduction
Hypertensive nephropathy (HN) is the second most common cause of end-stage renal disease after diabetic nephropathy. miRNAs are small epigenetic modulators whose levels change in many diseases. This review summarizes the diagnostic and therapeutic potential of miRNAs in HN.

Methodology
We conducted a thorough literature review on PubMed, including both retrospective and prospective studies on animal and human subjects. Additional references were sourced through cross-referencing the bibliographies of the initial articles.

Results

Our literature review revealed that intra-renal levels of miR-200a, miR-141, miR-200b, miR-205, miR-429, and miR-192 were elevated in patients with HN. Conversely, intra-renal miR-204-5p levels were decreased, and further reductions in animal models using anti-miR-204-5p or miR-204 gene knockout exacerbated renal injury.

Exposure of renal tissue to exogenous albumin increased intra-renal miR-184 levels, prompting further investigation into whether albumin excretion from kidney injury alters miRNA expression or if miRNA dysregulation initiates kidney injury and subsequent albumin excretion.

Urinary miR-146a, miR-184, and miR-34a levels were lower in patients with albuminuria than those without, whereas urinary miR-200a levels were higher. Interestingly, urinary miR-21 levels increased before the onset of albuminuria in hypertensive mice.

A positive correlation was also observed between miR-208b and miR-133a levels in blood cells and urinary albumin excretion (UAE). Notably, plasma levels of miR-let-7g-5p and miR-191-5p correlated positively with eGFR but not with UAE. Since miRNA levels varied based on the sampling source, a pivotal study identified a consistent miRNA profile in HN patients, showing that miR-208a and miR-301a were upregulated in urine yet downregulated in plasma.

The therapeutic potential of miRNAs was highlighted by an animal study showing that the knockdown of miR-103a-3p can nullify albuminuria in hypertensive mice.

Conclusion
The role of miRNAs in HN is increasingly evident. Studies have linked varying miRNA expression profiles in patients with HN, and specific miRNAs were detectable earlier than albuminuria. Furthermore, certain miRNAs correlate with eGFR independently of UAE. Targeting specific miRNAs, using miRNA mimics and anti-miRNAs, could underpin preventive and therapeutic strategies. These findings advocate for further research into miRNAs as potential biomarkers and therapeutic targets for HN.