Tanshinone IIA, a component of Salvia miltiorrhiza Bunge, attenuated sepsis-induced liver injury via the SIRT1/Sestrin2/HO-1 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE

As a traditional Chinese medicine, Salvia miltiorrhiza Bunge has been widely used to treat ischemic and inflammation-related diseases for more than 2000 years. S. miltiorrhiza Bunge has hepatoprotective effects, but the underlying mechanism is not fully understood.

OBJECTIVE

To verify the effect of tanshinone IIA (Tan IIA), the main fat-soluble component of S. miltiorrhiza Bunge, on liver damage induced by sepsis/LPS-induced inflammation and further explore the underlying mechanisms.

MATERIALS AND METHODS

Mice were administered Tan IIA 2 h before cecal ligation and puncture (CLP). Liver damage was evaluated by hematoxylin-eosin staining and changes in related serum factor levels. The expression of silent information regulator sirtuin 1 (SIRT1), Sestrin2, HO-1 and inflammatory cytokines was examined by immunohistochemistry or western blotting. LPS was used to induce the inflammatory response in vitro, and the activity of the related signaling pathway in response to Tan IIA was detected by western blotting. The SIRT1 inhibitor EX-527 and small interfering RNAs (siRNAs) were employed to determine the key roles of SIRT1 and Sestrin2 in Tan IIA's function.

RESULTS

We found that Tan IIA significantly improved the pathological changes and function of the liver, and alleviated liver damage in CLP mice. Additionally, SIRT1, Sestrin2, and HO-1 expression was significantly elevated after Tan IIA treatment compared with that in the CLP group both in vivo and in vitro, and Tan IIA treatment additionally suppressed pro-inflammatory cytokine release. However, inhibition of either SIRT1 or Sestrin2 remarkably abrogated the protective effects of Tan IIA. Most importantly, Sestrin2 appeared to function downstream of SIRT1 based on their expression changes after EX-527 or siRNA treatment.

CONCLUSION

Tan IIA inhibited sepsis/LPS-induced inflammation through the SIRT1/Sestrin2/HO-1 pathway, thereby protecting against sepsis-induced liver injury (SLI). This study suggests that Tan IIA has therapeutic potential against SLI and that the SIRT1/Sestrin2/HO-1 signaling pathway might be a viable target for SLI treatment.