Cordycepin negatively modulates lipopolysaccharide-induced cytokine production by up-regulation of heme oxygenase-1

Aims: The present study is to investigate the effect of cordycepin on the expression of heme oxygenase-1 (HO-1) in lipopolysaccharide (LPS)-activated microphages, as well as its mechanism of action. Methods: Mouse RAW264.7 cells were treated with different concentrations of cordycepin for 0-16 h. Western blotting was used to determine the expression of HO-1 and the phosphorylation of c-Src and the p47(Phox) subunit of NADPH oxidase. Intracellular reactive oxygen species (ROS) level was determined using H(2)DCFDA as fluorescent probe. Laser-scanning confocal microscopy was used to visualize the nuclear translocation of NF-E2-related factor 2 (Nrf2). Enzyme-linked immunosorbent assay was performed to measure the inhibitory effect of cordycepin on LPS-induced secretion of tumor necrosis factor-alpha and interleukin-6. Results: Cordycepin induced the phosphorylation of c-Src and p47(Phox) subunit of NADPH oxidase in RAW264.7 cells. Cordycepin increased the secretion of ROS by activating NADPH oxidase. In addition, cordycepin enhanced the expression of HO-1 in RAW264.7 cells in both dose-and time-dependent manners. Of note, elevated HO-1 expression induced by cordycepin treatment was regulated by c-Src/NADPH oxidase/ROS pathway. HO-1 expression induced by cordycepin was dependent on the activation of Nrf2, which was regulated by c-Src/NADPH oxidase/ROS. Cordycepin reduced LPS-induced secretion of proinflammatory cytokines through up-regulation of HO-1. Conclusion: The present study demonstrates that cordycepin induces the expression of HO-1 in RAW264.7 cells via c-Src/NADPH oxidase/ROS/Nrf2 pathway, and plays an anti-inflammatory role by inhibiting the secretion of cytokines from macrophages. (C) 2017 Elsevier B.V. All rights reserved.