Anti-inflammatory effects of aromatic-turmerone through blocking of NF-κB, JNK, and p38 MAPK signaling pathways in amyloid β-stimulated microglia

Abstract

Amyloid β (Aβ) induces the production of neuroinflammatory molecules, which may contribute to the pathogenesis of numerous neurodegenerative diseases. Therefore, suppression of neuroinflammatory molecules could be developed as a therapeutic method. Aromatic (ar)-turmerone, turmeric oil isolated from Curcuma longa, has long been used in Southeast Asia as both a remedy and a food. In this study, we investigated the anti-inflammatory effects of ar-turmerone in BV2 microglial cells. Aβ-stimulated microglial cells were tested for the expression and activation of MMP-9, iNOS, and COX-2, the production of proinflammatory cytokines, chemokines, and ROS, as well as the underlying signaling pathways. Ar-turmerone significantly suppressed Aβ-induced expression and activation of MMP-9, iNOS, and COX-2, but not MMP-2. Ar-turmerone also reduced TNF-α, IL-1β, IL-6, and MCP-1 production in Aβ-stimulated microglial cells. Further, ar-turmerone markedly inhibited the production of ROS. Impaired translocation and activation of NF-κB were observed in Aβ-stimulated microglial cells exposed to ar-turmerone. Furthermore, ar-turmerone inhibited the phosphorylation and degradation of IκB-α as well as the phosphorylation of JNK and p38 MAPK. These results suggest that ar-turmerone impaired the Aβ-induced inflammatory response of microglial cells by inhibiting the NF-κB, JNK, and p38 MAPK signaling pathways. Lastly, ar-turmerone protected hippocampal HT-22 cells from indirect neuronal toxicity induced by activated microglial cells. These novel findings provide new insights into the development of ar-turmerone as a therapeutic agent for the treatment of neurodegenerative disorders.