Targeting HSF1-TLR9 Axis: Celastrol as a Potential Therapeutic for Liver Injury in Traumatic Hemorrhagic Shock

Abstract

Background: One of the pharmacological effects of celastrol (Cel) is the amelioration of acute liver injury. In this study, we explored the mechanism of Cel underlying the alleviation of liver injury induced by traumatic hemorrhagic shock (THS).

Methods: The THS model was developed from Sprague-Dawley rats through transverse fractures, blood loss and fluid infusion. Then, the THS rats were intraperitoneally injected with 0.5, 1, and 1.5 mg/kg Cel. The rats were injected in the tail vein with lentivirus-mediated small interfering RNA (siRNA) negative control (siNC), siRNA targeting heat shock transcription factor 1 (siHSF1), and siRNA targeting toll-like receptor 9 (siTLR9) 72 hours before the establishment of THS model. Hematoxylin-eosin (HE) staining was performed to highlight the pathological alterations in the rat liver tissue. Enzyme-linked immunosorbent Assay (ELISA) was utilized to determine the expression levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and total bilirubin (TB). The expression levels of B-cell lymphoma 2 (Bcl2) and B-cell lymphoma 2 associated X protein (Bax) were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR). The expression levels of reactive oxygen species (ROS), malondialdehyde (MDA), glutathione (GSH), and superoxide dismutase (SOD) were determined to assess the extent of oxidative stress. Western blotting was used to evaluate the expression levels of heat shock transcription factor 1 (HSF1), toll-like receptor 9 (TLR9) and myeloid differentiation factor 88 (MyD88).

Results: Cel was shown to therapeutically alleviate liver injury, decrease ALT and AST levels, and simultaneously downregulate inflammation factors levels (TNF-α, IL-1β), alleviated apoptosis, and decreased oxidative stress in the THS model in a concentration-dependent manner. Moreover, Cel increased the expression of HSF1 and decreased the expression of TLR9 and MyD88 in the THS model. And silencing HSF1 increased TLR9 and MyD88 expression. Further, the silencing of HSF1 resulted in liver injury, inflammation and apoptosis, which could be reversed by TLR9 silencing.

Conclusions: This study demonstrates that Cel attenuates THS-induced liver injury by positively regulating HSF1 so as to inhibit the expression of TLR9.

Keywords: celastrol; heat shock transcription factor 1; liver injury; myeloid differentiation factor 88; toll-like receptor 9; traumatic hemorrhagic shock.