Serum miR-378d is associated with liver stiffness and fibrosis risk in patients with metabolic dysfunction-associated steatotic liver disease

Tissue biopsy is the gold standard for diagnosing metabolic dysfunction-associated steatohepatitis (MASH), but it is invasive and time-consuming to analyze. This paper aimed to explore the association between serum miR-378d and liver stiffness and fibrosis risk in patients with metabolic dysfunction-associated steatotic liver disease (MASLD), and to preliminarily investigate its biological plausibility using cell and animal experiments. Venous blood was collected from healthy and MASLD individuals for the detection of miR-378d. Liver stiffness was assessed by transient elastography (FibroScan), and patients were stratified by fibrosis risk. The discriminatory ability of miR-378d for elevated liver stiffness was evaluated by ROC analysis. Prognostic association was assessed by Kaplan–Meier analysis and Cox regression. A MASH mouse model was established and the levels of serum enzymes, lipid markers and fibrosis markers in the model were evaluated. The effect of down-regulation of miR-378d on the MASH mouse model was evaluated by tail vein injection of miR-378d antagomir. In silico target prediction, GO/KEGG enrichment, and PPI network analysis were conducted using bioinformatics databases. Compared to the control group, serum miR-378d was upregulated in MASLD patients with elevated LSM. ROC analysis showed moderate discriminative ability for identifying elevated LSM (AUC = 0.876). Elevated miR-378d was associated with higher risk of LSM progression (log-rank P = 0.027). At 18 weeks of HFHS diet, the expressions of body weight, liver index, serum enzymes, lipid markers and fibrosis markers in the HFHS group of mice were markedly higher than those in the control group, while injection of miR-378d antagomir could significantly down-regulate the levels of the above indicators. Serum miR-378d was up-regulated in MASLD patients with increased liver stiffness and showed association with fibrosis severity. These exploratory findings suggest that circulating miR-378d may serve as a candidate non‑invasive biomarker for fibrosis risk stratification in MASLD, but further validation in biopsy‑proven cohorts is warranted.