13-Ethylberberine reduces HMGB1 release through AMPK activation in LPS-activated RAW264.7 cells and protects endotoxemic mice from organ damage

Abstract

High mobility group box 1 (HMGB1), a highly conserved non-histone DNA-binding protein, plays an important role in the pathogenesis of sepsis. Previously, the authors reported 13-ethylberberine (13-EBR) has anti-inflammatory and antibacterial effects. However, the effect of 13-EBR on HMGB1 release was not investigated. In the present study, it was hypothesized 13-EBR might reduce HMGB1 release by activating AMPK under septic conditions. The results obtained showed 13-EBR significantly reduced HMGB1 release from LPS-activated RAW264.7 cells, and that this reduction was reversed by silencing p38, or AMPK, or by co-treating cells with p38 MAPKinase inhibitor. 13-EBR increased the phosphorylations of p38 and AMPK, and the phosphorylation of p38 by 13-EBR was inhibited by AMPK-siRNA, indicating AMPK acted upstream of p38. In the lung tissues of LPS-treated mice, 13-EBR administration significantly increased p-AMPK but reduced inducible nitric oxide synthase (iNOS) protein levels. Hematoxylin and eosin staining revealed 13-EBR significantly reduced LPS-induced lung and liver damage. In addition, 13-EBR inhibited NF-kB in LPS-activated RAW264.7 cells, and in LPS-treated mice, 13-EBR administration significantly increased survival. Furthermore, co-administration of 13-EBR plus LPS prevented LPS-induced aortic rings hypocontractile response to phenylephrine in vitro. Taken together, these results indicate 13-EBR might offer a means of treating sepsis through AMPK activation.