Costunolide (Cos) is a naturally occurring sesquiterpene lactone that exhibits antioxidative properties. In this study, we demonstrate the protective mechanism of Cos against ischemia/reperfusion (I/R)-induced myocardial injury. Cos significantly decreased levels of reactive oxygen species and ameliorated apoptosis of I/R cardiomyocytes both in vitro and in vivo. Further investigation revealed that Cos increased expression of the antioxidant proteins HO-1 and NQO-1 and decreased the Bax/Bcl-2 ratio, thus protecting cardiac cells. NF-E2–related factor 2 (Nrf2) silencing significantly attenuated the protective effects of Cos in tert-butyl hydroperoxide (TBHP)-treated H9C2 cells. Additionally, Cos significantly intensified the I/R- or TBHP-induced dissociation of the Kelch-like ECH-associated protein 1 (Keap1)/Nrf2 complex both in vitro and in vivo. These results suggest that activation of Nrf2/Keap1 using Cos may be a therapeutic strategy for myocardial I/R injury.

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Atherosclerosis is a chronic inflammatory disease with high morbidity and mortality rates worldwide. Doublecortin-like kinase 1 (DCLK1), a microtubule-associated protein kinase, is involved in neurogenesis and human cancers. However, the role of DCLK1 in atherosclerosis remains undefined. In this study, we identified upregulated DCLK1 in macrophages in atherosclerotic lesions of ApoE −/− mice fed an HFD and determined that macrophagespecific DCLK1 deletion attenuates atherosclerosis by reducing inflammation in mice. Mechanistically, RNA sequencing analysis indicated that DCLK1 mediates oxLDL-induced inflammation via NF-κB signaling pathway in primary macrophages. Coimmunoprecipitation followed by LC-MS/MS analysis identified IKKβ as a binding protein of DCLK1. We confirmed that DCLK1 directly interacts with IKKβ and phosphorylates IKKβ at S177/181, thereby facilitating subsequent NF-κB activation and inflammatory gene expression in macrophages. Finally, a pharmacological inhibitor of DCLK1 prevents atherosclerotic progression and inflammation both in vitro and in vivo. Our findings demonstrated that macrophage DCLK1 promotes inflammatory atherosclerosis by binding to IKKβ and activating IKKβ/NF-κB. This study reports DCLK1 as a new IKKβ regulator in inflammation and a potential therapeutic target for inflammatory atherosclerosis.