Plasma MERTK Is a Promising Biomarker for the Diagnosis and Prognosis of Hepatitis B Virus–Related Acute-on-Chronic Liver Failure

Abstract Background Hepatitis B virus–related acute-on-chronic liver failure (HBV-ACLF) has a high short-term mortality. This study aimed to determine the diagnostic and prognostic role of MER tyrosine kinase (MERTK) in patients with HBV-ACLF. Methods Transcriptomics analysis evaluated MERTK expression and function during disease progression. The diagnostic and prognostic significance of MERTK for patients with HBV-ACLF were verified by enzyme-linked immunosorbent assay, area under the receiver operating characteristic curve (AUROC) analysis, and immunohistochemistry (IHC) of liver tissues. Results MERTK mRNA was highly expressed in patients with HBV-ACLF compared to those with liver cirrhosis (LC), chronic hepatitis B (CHB), and normal controls (NC). Elevated MERTK mRNA predicted poor prognosis for HBV-ACLF at 28 and 90 days (AUROC = 0.814 and 0.731, respectively). Functional analysis showed MERTK was significantly associated with toll-like receptor and inflammatory signaling and several key biological processes. External validation with 285 plasma subjects confirmed the high diagnostic accuracy of plasma MERTK for HBV-ACLF (AUROC = 0.859) and potential prognostic value for 28- and 90-day mortality rates (AUROC = 0.673 and 0.644, respectively). Risk stratification analysis indicated higher mortality risk for patients with plasma MERTK level above the cutoff value. Moreover, IHC staining showed increasing MERTK expression from NC, CHB, and LC to HBV-ACLF. Conclusions MERTK shows promise as a candidate biomarker for early diagnosis and prognosis of HBV-ACLF.