Hepatic Macrophages are the Cell Source of Hepatic Procalcitonin in Acute Liver Failure

Background/Aims: Serum procalcitonin (PCT) is elevated in acute liver failure (ALF), but the expression of PCT in the liver has not been elucidated. We aimed to clarify the regulation of hepatic PCT expression and the cell sources in ALF. Methods: Human monocytic leukemia line U937 cells were treated with 12-O-tetradecanoylphorbol-l3-acetate (PMA) (100 ng/ mL) for 24 h to induce activated macrophages. In the presence of lipopolysaccharide (LPS, 1 μg/mL), activated macrophages and human hepatocyte line L02 cells were incubated with LPS or co-cultured for 0, 2, 6, and 24 h. In an in vivo experiment, male C57BL/6 mice were challenged with intraperitoneal LPS/D-galactosamine (LPS/D-GalN). Serum liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured using an automatic chemical analyzer. Inflammatory mediators were measured by real-time PCR and liver histology was examined by hematoxylin-eosin (HE) staining and immunohistochemistry (IHC). Results: LPS induced the upregulation of PCT mRNA in U937-activated macrophages but not in L02 cells. When co-cultured with L02 cells, the expression of PCT mRNA of activated macrophages was upregulated compared to controls; however, the activated macrophages did not induce the expression of PCT mRNA in L02 cells in the presence of LPS. Moreover, serum liver enzymes (ALT, AST), inflammation, necrosis, and hepatic expression of PCT were significantly elevated in the LPS/D-GalN-challenged ALF mouse model. IHC revealed that PCT expression was co-localized with hepatic macrophages. Conclusions: Hepatic PCT expression is upregulated in ALF. Hepatic macrophages but not hepatocytes are the cell source of hepatic PCT expression