Urine miR-340-5p predicts the adverse prognosis of sepsis-associated acute kidney injury and regulates renal tubular epithelial cell injury by targeting KDM4C.

Introduction: Sepsis-associated acute kidney injury (SA-AKI) is a common complication of sepsis. miR-340-5p has been identified as an effective biomarker of various human diseases. As the downstream target, the involvement of Lysine (K)-specific demethylase 4C (KDM4C) in SA-AKI would help interpret the regulatory mechanism of miR-340-5p. The significance of miR-340-5p in the onset and progression of SA-AKI was evaluated to provide a potential therapeutic target for SA-AKI.

Methods: This study enrolled 64 healthy individuals (control) and 159 sepsis patients (92 SA-AKI and 67 non-AKI) and collected urine samples. The urine level of miR-340-5p was analyzed by PCR, and a series of statistical analyses were conducted to assess the clinical significance of miR-340-5p in the occurrence and development of SA-AKI. The injured renal tubular epithelial cells were established with LPS induction. The roles of miR-340-5p in cellular processes were evaluated.

Results: Increasing urine miR-340-5p discriminated SA-AKI patients from healthy individuals (AUC = 0.934) and non-AKI sepsis patients (AUC = 0.806) sensitively. Additionally, elevated miR-340-5p could predict the adverse prognosis (HR = 5.128, 95% CI = 1.259-20.892) and malignant development of SA-AKI patients. In vitro, lipopolysaccharide (LPS) also induced an increased level of miR-340-5p and significant cell injury in the renal tubular epithelial cell, silencing miR-340-5p could alleviate the suppressed proliferation, migration, and invasion caused by LPS. In mechanism, miR-340-5p negatively regulated KDM4C, which mediated the function of miR-340-5p.

Conclusion: miR-340-5p served as a diagnostic and prognostic biomarker of SA-AKI and regulated renal tubular epithelial cell injury via modulating KDM4C.