C/EBPβ-VCAM1 axis in Kupffer cells promotes hepatic inflammation in MASLD.

BACKGROUND & AIMS: Kupffer cells (KCs) can promote hepatic inflammation in metabolic dysfunction-associated steatotic liver disease (MASLD), but the underlying molecular mechanisms are not fully understood. C/EBPβ in macrophages can mediate metabolic and immune dysregulations. Therefore, we aimed to explore its role in KCs in MASLD pathogenesis.

METHODS

A 12-week high-fat and high-cholesterol diet (HFHCD) model was used in wild-type or KC-specific heterozygous knockout mice (n = 10 per group), followed by liver evaluation using histopathology, flow cytometry, and RNA-seq. RNA-seq of liver tissue (n = 3 per group) and C/EBPβ CUT&Tag-seq of sorted KCs were comprehensively analyzed to elucidate the transcriptional regulatory network. Flow cytometry and immunofluorescence were used to detect the expression or distribution of key proteins.

RESULTS

HFHCD induced prominent immune cell infiltration and a concomitant increase in C/EBPβ in KCs. KC-specific heterozygous knockout significantly reduced HFHCD-induced lobular inflammation ( <0.05) and inflammation-related gene expression ( <0.05) in the liver. Multi-omics analysis revealed increased C/EBPβ activity in KCs in MASLD, leading to a selective promotive effect on MASLD-induced genes. Further integrated analysis identified as a key direct downstream gene of C/EBPβ in KCs in MASLD, which involves C/EBPβ-mediated activation of the promoter. VCAM1 was predominantly expressed in KCs in the hepatic tissue of MASLD mice and patients. KC-expressed VCAM1 was significantly increased in MASLD compared with healthy controls ( <0.01), and it promoted immune cell infiltration into the liver.

CONCLUSIONS

Increased C/EBPβ in KCs promotes pathogenic transcriptional activation, leading to increased VCAM1 expression and inflammatory cell infiltration in MASLD. Inhibition of C/EBPβ in KCs might be a potential therapeutic strategy against hepatic inflammation in MASLD.

IMPACT AND IMPLICATIONS

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common chronic liver disease worldwide, but its pathogenesis remains elusive. In this study, we investigated the critical role of CCAAT/enhancer binding protein β (C/EBPβ) in Kupffer cells and its implications in MASLD pathogenesis. We found that an increased C/EBPβ level in Kupffer cells promotes hepatic inflammation in MASLD by upregulating VCAM1 expression. Our findings provide valuable insights into the molecular mechanisms driving MASLD and propose a potential novel therapeutic target to mitigate hepatic inflammation in MASLD.