Wogonoside inhibits inflammatory cytokine production in lipopolysaccharide-stimulated macrophage by suppressing the activation of the JNK/c-Jun signaling pathway

Xiu Yu; Dandan Chen; Lingwei Wang; Jie Li; Khalid Khan; Haihui Chen; Yutian Liang; Huanmin Luo; Chen Qiu

doi:10.21037/atm.2020.04.22

Wogonoside inhibits inflammatory cytokine production in lipopolysaccharide-stimulated macrophage by suppressing the activation of the JNK/c-Jun signaling pathway

Ann Transl Med. 2020 Apr;8(8):532. doi: 10.21037/atm.2020.04.22.

Authors

Xiu Yu^{1

2}, Dandan Chen¹, Lingwei Wang¹, Jie Li¹, Khalid Khan^{1

2}, Haihui Chen¹, Yutian Liang¹, Huanmin Luo³, Chen Qiu¹

Affiliations

¹ Department of Respiratory and Critical Care Medicine, The Second Clinical Medical College (Shenzhen People's Hospital) of Jinan University, Shenzhen Institute of Respiratory Diseases, Shenzhen 518020, China.
² Integrated Chinese and Western Medicine Postdoctoral Research Station, Jinan University, Guangzhou 510632, China.
³ Department of Pharmacology, School of Medicine, Jinan University, Guangzhou 510632, China.

Abstract

Background: Mediated by innate immune cells, inflammation is an underlying presence in the pathogenesis of numerous pulmonary diseases. Macrophages play a critical role in mediating the initial response to infection in the lungs. When there is excessive activation of macrophages, hyper-production of inflammatory factors occurs, with inflammation as the ultimate result. Wogonoside, a bioactive flavonoid glycoside, has been reported to alleviate pulmonary inflammation. However, the mechanism underlying the anti-inflammatory effect of wogonoside has not yet been clarified.

Methods: The productions of nitric oxide (NO) and reactive oxygen species (ROS) were determined using a Griess reagent kit and a DAF-FM DA fluorescent probe, respectively. Moreover, the mRNA levels of inflammatory factors were quantified by qPCR, and the binding ability of c-Jun to promoters of inflammatory factors was performed by ChIP assay. Western blot was employed to detect the protein expression of inflammatory factors and signaling pathway.

Results: In this study, we found that pre-treatment with wogonoside dramatically suppressed lipopolysaccharide (LPS)-induced increase in the protein and mRNA levels of inflammatory factors in macrophages, such as cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6. Furthermore, wogonoside profoundly reduced the increase in NO and ROS production and significantly blocked phosphorylation of JNK in LPS-stimulated macrophages. As revealed by Western blot and qPCR analysis, wogonoside mediated the JNK-dependent inhibitory effect. Compared with wogonoside alone, a combination of wogonoside and JNK inhibitor SP600125 provided no extra benefit in suppressing the protein expression and mRNA levels of inflammatory factors in LPS-stimulated macrophages. Additionally, ChIP analysis demonstrated wogonoside to remarkably reduce c-Jun enrichment in COX-2, iNOS, IL-1β, TNF-α, and IL-6 promoters.

Conclusions: Collectively, our findings showed that wogonoside notably suppresses LPS-stimulated production of inflammatory factors by repressing the activation of the JNK/c-Jun signaling pathway in macrophages. This suggests that wogonoside could serve as a promising therapeutic agent for pulmonary diseases related to macrophage inflammation.

Keywords: Inflammation; JNK/c-Jun signaling pathway; macrophage; wogonoside.