The Effects of Twist-2 on Liver Endotoxin Tolerance Induced by a Low Dose of Lipopolysaccharide

Abstract

Endotoxin tolerance is an important mechanism for preventing uncontrolled inflammatory cytokine production in bacterial sepsis. However, its molecular mechanisms remain largely unknown. It was reported that Twist-2 protein was a negative regulator for cytokine signaling by repressing the nuclear factor (NF)-κB-dependent cytokine pathway. However, the relationship between Twist-2 and endotoxin tolerance is unclear. Endotoxin tolerance models of BABL/c mice and isolated Kupffer cells (KCs) were established to observe the changes of Twist-2 during endotoxin tolerance. Then, Twist-2 shRNA was used to specifically inhibit Twist-2 gene in KCs to further explore the role of Twist-2 in endotoxin tolerance. The expression of Twist-2 was analyzed by immunohistochemistry, reverse transcription polymerase chain reaction, and Western blotting, respectively. The responses to lipopolysaccharide were assessed by the activation of nuclear factor-κB and the production of tumor necrosis factor-α. The histopathologic changes in the liver of the non-endotoxin tolerance group were more serious than those of the endotoxin tolerance group. Endotoxin tolerance also led to less activation of nuclear factor-κB, lower expression levels of tumor necrosis factor-α mRNA, and more expression of Twist-2 than those of non-endotoxin tolerance group in liver and KCs. Moreover, the inhibitive effects partly weaken in KCs transfected with Twist-2 shRNA. Twist-2 was involved in endotoxin tolerance through inhibiting NF-κB trans-activation and cytokines transcriptional activities. It may be a new target for the clinical treatment of sepsis and other inflammatory diseases.