HMGB1 neutralization is associated with bacterial translocation during acetaminophen hepatotoxicity

Runkuan Yang,Marja-Leena Koskinen,Shengtao Zhu,Jyrki Tenhunen,Henri Kajander,Xiaoping Zou,Tor Inge Tonnessen

doi:10.1186/1471-230x-14-66

Abstract

BackgroundAcetaminophen (APAP) hepatotoxicity is associated with a high rate of gram-negative enteric bacterial infection; however, the underlying mechanism is still unknown. APAP overdose induces massive hepatocyte necrosis, necrotic tissue releases high mobility group B1 (HMGB1) and exogenous HMGB1 is able to induce gut bacterial translocation (BT) in normal mice; therefore, it is possible that HMGB1 mediates gut BT in APAP hepatotoxicity. This study aims to test this hypothesis by using anti-HMGB1 neutralizing antibody to treat APAP overdose for 24-48 hours.MethodsMale C57BL/6 mice were intraperitoneally (i.p.) injected with a single dose of APAP (350 mg/kg dissolved in 1 mL sterile saline). 2 hrs after APAP injection, the APAP challenged mice were randomized to receive treatment with either anti-HMGB1 antibody (400 μg per dose) or non-immune (sham) IgG every 24 h for a total of 2 doses.Results24 and 48 hrs after APAP challenge, anti-HMGB1 treatment instead of sham IgG therapy significantly decreased serum HMGB1 concentrations and reduced BT by 85%; serum HMGB1 levels were positively correlated with the amount of BT; anti-HMGB1 therapy decreased hepatic BT at 48 h, which was associated with better recovered liver structure and better restored hepatic immune system that was shown by enhanced hepatic mRNA expression of TNF-α, IL-6 and extensive proliferation of inflammatory and reticuloendothelial cells; however, anti-HMGB1 treatment did not decrease gut mucosal permeability as compared to the sham IgG therapy at either 24 or 48 hrs.ConclusionHMGB1 neutralization is associated with bacterial translocation during APAP hepatotoxicity.

Highlights

Acetaminophen (APAP) hepatotoxicity is associated with a high rate of gram-negative enteric bacterial infection; the underlying mechanism is still unknown
Mice treated only with saline had 5.9 ± 0.4 μmol of glutathione/g liver tissue. 6 hours after APAP injection, glutathione concentrations were 0.69 ± 0.066 and 0.73 ± 0.08 μmol of glutathione/g liver in mice treated with sham IgG and anti-high mobility group B1 (HMGB1) neutralizing antibody, respectively
Serum HMGB1 concentrations 24 hours and 48 hours after APAP challenge, serum HMGB1 concentrations in the sham IgG groups and the anti-HMGB1 groups were significantly increased as compared to the control groups; the 24 h serum HMGB1 level in the sham IgG group was significantly higher than the 48 h serum HMGB1 level in the sham IgG group; 24 h after APAP injection, serum HMGB1 concentration in the antiHMGB1 group was significantly lower than that in the sham IgG groups, and at 48 h time point, serum HMGB1 concentration in the anti-HMGB1 group was statistically lower than that in the sham IgG group (Figure 1)

Summary

Introduction

Acetaminophen (APAP) hepatotoxicity is associated with a high rate of gram-negative enteric bacterial infection; the underlying mechanism is still unknown. APAP overdose induces massive hepatocyte necrosis, necrotic tissue releases high mobility group B1 (HMGB1) and exogenous HMGB1 is able to induce gut bacterial translocation (BT) in normal mice; it is possible that HMGB1 mediates gut BT in APAP hepatotoxicity. ALF is associated with a high rate of infectious complications, most of these infections are produced by gram negative enteric bacteria [2]; the underlying mechanism is still not clear. APAP overdose induces massive hepatocyte necrosis [3,4,5,6] and necrotic tissue passively releases HMGB1 [7,8,9], a ubiquitous nuclear protein secreted by immunocompetent cells, including monocytes, macrophages and

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