Aim of the study
To investigate the role of Th17/Treg imbalance in TP-induced hepatic excessive immune response to exogenous LPS. Materials and
Conclusion
Hepatic Th17/Treg imbalance not only exacerbates TP- and LPS-induced liver injury, but also serves as an indispensable part in the mechanisms of TP-induced hepatic intolerance to exogenous endotoxin.
Methods
Mice were administered with TP, LPS, neutralization antibody and small molecule inhibitor respectively. Serum transaminase level was measured to determine the severity of liver injury. Frequencies of liver Th17 and Treg cells were analyzed by flow cytometry. Serum cytokine levels were performed by ELSIA, and mRNA levels of liver cytokine were performed by qPCR. The status of neutrophil infiltration was performed by myeloperoxidase (MPO) IHC measurement. Morphological observation of liver was performed by hematoxylin and eosin (H&E) staining.
Results
Mice given a single intragastric dose of TP (500 μg/kg) developed lethal fulminant hepatitis following intraperitoneal injection of LPS (0.1 mg/kg), characterized by low survival rate, severe liver injury, high levels of inflammation and neutrophil infiltration. Hepatic Th17/Treg imbalance emerged together with liver injury in these mice. Neutralization of IL-17A attenuated the liver injury and ameliorated the neutrophil infiltration. The TP-induced alteration of hepatic Th17/Treg balance was closely related to the outcome of immune-mediated acute liver injury triggered by LPS. Pretreatment with the STAT3 inhibitor AG490 effectively restored Th17/Treg balance, significantly reducing the production of IL-17A and finally attenuating the degree of liver injury.