To investigate the relationship between the expression of miR-122 in HBV-related acute-on-chronic liver failure (HBV-ACLF) and clinical indicators, and to analyze the role of miR-122 in evaluating the severity and diagnosis of HBV-ACLF.

Serum samples from 49 patients with HBV-ACLF, 30 patients with chronic hepatitis B (CHB) and 30 healthy volunteers were collected from the First Affiated Hospital of Shanxi Medical University. The relative expression of miR-122 in each sample was detected by fluorescence real-time quantitative PCR. With the u6 as endogenous control, the relative expression of miR-122 was expressed as 2^-ΔCT. Patients with HBV-ACLF were divided into early stage, middle stage and late stage groups according to the severity of clinical manifestations. The levels of miR-122 expression between different groups were compared, and the correlation between the expression of miR-122 and biochemical markers were analyzed, respectively. Furthermore, the role of miR-122 in the progression of HBV-ACLF was analyzed by Unconditional Logistic regression model, thus reflecting the association between miR-122 and disease severity. Receiver operating characteristic curve (ROC) was used to evaluate the value of serum miR-122 in the diagnosis of HBV-ACLF.

The expression level of miR-122 in serum of patients with HBV-ACLF was significantly higher than those of healthy subjects and patients with CHB (P < 0.001), and the level of miR-122 expression in advanced HBV-ACLF was significantly higher than those of the early and middle stages (P < 0.001, P = 0.048). The serum level of miR-122 in patients with HBV-ACLF was positively correlated with the level of serum total bilirubin (TBil) (r = 0.508, P < 0.001) and negatively correlated with PTA (r =-0.797, P < 0.001). Unconditional Logistic regression model showed that an increase of one unit of relative expression of miR-122 (2^-ΔCT) was associated with 5.8% (95%CI: 1.013-1.104) increase in the risk of progression from HBV-ACLF early stage to middle stage and 13.0% (95%CI: 1.034-1.235) increase in the risk from early stage to late stage. The ROC analysis showed that the area under the curve (AUC) of disease diagnosis was 0.942 (95%CI: 0.903-0.982), the sensitivity and the specificity were 83.7% and 86.7%.

The expression level of miR-122 in serum could be used as a biomarker for the diagnosis and the severity of HBV-ACLF.