β-caryophyllene to relieve inflammation by inhibiting HMGB1 signaling in ischemic stroke mice

Background: Characterized by high mortality and high disability rate, ischemic stroke accounts for the vast majority of current stroke patients. Reperfusion after surgical treatment will cause serious secondary damage to the ischemic stroke patient, but there is still no specific drug for the clinical treatment of ischemic stroke. Anti-inflammatory disease is an important part of ischemia and reperfusion injury, and it is urgent to find new anti-inflammatory targets and drugs. High-mobility group box-1(HMGB1) is abundant in both neuronal cell bodies and axons, and has been found to have late pro-inflammatory effects, becoming one of the hot research topics in critical care medicine recently. The increase of HMGB1 expression leads to the aggravation of inflammatory reaction after ischemia stroke. B-caryophyllene (BCP) is a natural drug with anti-inflammatory effects. Whether the anti-inflammatory mechanism of BCP is related to HMGB1 is still unknown. We aimed to investigate the relationship and potential signaling mechanisms between HMGB1 and BCP in ischemia stroke model in vivo and in vitro. Methods: Establishment of middle cerebral artery embolism model in mice by thread thrombus and primary neurons were exposed to oxygen-glucose deprivation and re-oxygenation (OGD/R) in vitro. In vitro, transfection of HMGB1 DNA overexpression virus（GV-HMGB1）the same time, transfectionHMGB1 DNA silencing virus（RNAi-HMGB1）the same, in vivo , injection of GV-HMGB1 into the lateral ventricle of mice , injection of RNAi-HMGB1 into another group of mice. Results: It was found that HMGB1 increased after ischemic stroke, and further affected the expression of TLR4, RAGE and other related inflammatory factors, thus reducing the inflammatory response and finally protecting the injury. The results confirmed the effect of HMGB1 in effecting TLR4/RAGE signaling and subsequently regulating inflammation, oxidative stress and apoptosis. Furthermore, BCP alleviates ischemic brain damage potentially by suppressing HMGB1/ TLR4/RAGE signaling, reducing expression of IL-1β/IL-6/TNF-α，inhibiting neuronal death and inflammatory response. Conclusion: These data indicated that BCP exerted a protective effect against ischemia stroke inflammatory injury by adjusting the HMGB1/TLR4/RAGE signaling pathway, which provided new insights into the mechanisms of this therapeutic candidate for the treatment of ischemia stroke.