Abstract
BACKGROUND AND AIMS: Acute-on-chronic liver failure (ACLF) is a life-threatening syndrome characterized by systemic inflammation and immune dysregulation, in which macrophages play a key role in organ injury. This study aimed to investigate the role and mechanism of pyruvate dehydrogenase kinase 4 (PDK4) in ACLF to identify therapeutic targets that modulate macrophage function and mitigate ACLF progression. METHODS: Single-cell RNA sequencing data from healthy and ACLF liver tissues were analyzed from the Sequence Read Archive database. Transcriptomic data of peripheral blood mononuclear cells from ACLF patients (GSE168048) were also examined. In vitro experiments assessed PDK4 expression and macrophage polarization, and conditioned-medium studies evaluated effects on LO2 hepatocytes. In vivo validation was performed in ACLF mouse models treated with a PDK4 inhibitor. RESULTS: Single-cell analysis revealed a predominance of M1-polarized hepatic macrophages in ACLF with marked upregulation of PDK4. Peripheral blood mononuclear cell transcriptomics showed that higher PDK4 expression correlated with 28-day mortality. In vitro, PDK4 expression increased in M1 macrophages; PDK4 inhibition attenuated M1 polarization and reduced cytotoxic effects on LO2 cells. In vivo, pharmacologic inhibition of PDK4 suppressed M1 polarization in macrophages, alleviated liver inflammation, and reduced tissue injury. Mechanistically, PDK4 promoted M1 polarization via activation of signal transducer and activator of transcription 1 signaling. CONCLUSIONS: PDK4 is a key pro-inflammatory regulator in ACLF by promoting M1 macrophage polarization. Targeting PDK4 may be a promising strategy to attenuate inflammation and improve clinical outcomes in ACLF.