Abstract
Turmeric is traditionally used as a spice and coloring in foods. Curcumin is the primary active ingredient in the turmeric, and compelling evidence has shown that it has the ability to inhibit inflammation. However, the mechanism mediating its anti-inflammatory effects are not fully understood. We report that curcumin inhibited caspase-1 activation and IL-1β secretion through suppressing LPS priming and the inflammasome activation pathway in mouse bone marrow–derived macrophages. The inhibitory effect of curcumin on inflammasome activation was specific to the NLRP3, not to the NLRC4 or the AIM2 inflammasomes. Curcumin inhibited the NLRP3 inflammasome by preventing K+ efflux and disturbing the downstream events, including the efficient spatial arrangement of mitochondria, ASC oligomerization, and speckle formation. Reactive oxygen species, autophagy, sirtuin-2, or acetylated α-tubulin was ruled out as the mechanism by which curcumin inhibits the inflammasome. Importantly, in vivo data show that curcumin attenuated IL-1β secretion and prevented high-fat diet–induced insulin resistance in wide-type C57BL/6 mice but not in Nlrp3-deficient mice. Curcumin also repressed monosodium urate crystal–induced peritoneal inflammation in vivo. Taken together, we identified curcumin as a common NLRP3 inflammasome activation inhibitor. Our findings reveal a mechanism through which curcumin represses inflammation and suggest the potential clinical use of curcumin in NLRP3-driven diseases.
Footnotes
This work was supported by National Natural Science Foundation of China Grants 81370623, 81401314, 91442204, 81125002, and 81321061, Natural Sciences Foundation of Shandong Province Grant ZR2010HQ005, the Innovation Project of the Shandong Academy of Medical Sciences, and by the Project for Laureate of Taishan Scholar (Grant ts201511075).
The online version of this article contains supplemental material.
- Received October 27, 2017.
- Accepted February 21, 2018.
- Copyright © 2018 by The American Association of Immunologists, Inc.