Interleukin-23 mediates the pathogenesis of LPS/GalN-induced liver injury in mice.

Background: Interleukin-23 (IL-23) is required for T helper 17 (Th17) cell responses and IL-17 production in hepatitis B virus infection. A previous study showed that the IL-23/IL-17 axis aggravates immune injury in patients with chronic hepatitis B virus infection. However, the role of IL-23 in acute liver injury remains unclear.

Objective: The purpose of this study was to determine the role of the inflammatory cytokine IL-23 in lipopolysaccharide/d-galactosamine (LPS/GalN)-induced acute liver injury in mice.

Methods: Serum IL-23 from patients with chronic hepatitis B virus (CHB), acute-on-chronic liver failure (ACLF) and healthy individuals who served as healthy controls (HCs) was measured by ELISA. An IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody was administered intravenously at the time of challenge with LPS (10μg/kg) and GalN (400mg/kg) in C57BL/6 mice. Hepatic pathology and the expression of Th17-related cytokines, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and the stabilization factor Csf3 were assessed in liver tissue.

Results: Serum IL-23 was significantly upregulated in ACLF patients compared with CHB patients and HCs (P<0.05 for both). Serum IL-23 was significantly upregulated in the non-survival group compared with the survival group of ACLF patients, which was consistent with LPS/GalN-induced acute hepatic injury in mice (P<0.05 for both). Moreover, after treatment, serum IL-23 was downregulated in the survival group of ACLF patients (P<0.001). Compared with LPS/GalN mice, mice treated with either an IL-23p19 neutralizing antibody or an IL-23p40 neutralizing antibody showed less severe liver tissue histopathology and significant reductions in the expression of Th17-related inflammatory cytokine, including IL-17 and TNF-α; neutrophil chemoattractants, including Cxcl1, Cxcl2, Cxcl9, and Cxcl10; and stabilization factors Csf3 within the liver tissue compared with LPS/GalN mice (P<0.05 for all).

Conclusion: High serum IL-23 was associated with mortality in ACLF patients and LPS/GalN-induced acute liver injury in mice. IL-23 neutralizing antibodies attenuated liver injury by reducing the expression of Th17-related inflammatory cytokines, neutrophil chemoattractants and stabilization factors within the liver tissue, which indicated that IL-23 likely functions upstream of Th17-related cytokine and chemokine expression to recruit inflammatory cells into the liver.