1. The natural sesquiterpene lactone inulicin suppresses the production of pro-inflammatory mediators via inhibiting NF-κB and AP-1 pathways in LPS-activated macrophages.
- Author
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Yan, Jingjing, Cai, Min, Zang, Chenchen, Li, Wenjing, Liu, Zhuangzhuang, Li, Ximeng, Gao, Yuan, and Qi, Yun
- Subjects
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PERITONEAL macrophages , *NITRIC-oxide synthases , *THERAPEUTICS , *ASCITIC fluids , *PERITONEAL dialysis - Abstract
Objective: Inulicin is a sesquiterpene lactone in Inulae Flos which is clinically used for the treatment of inflammatory diseases, such as cough, sputum production, and vomiting. This study aimed to demonstrate the anti-inflammatory activity and the underlying mechanism of inulicin by using lipopolysaccharide (LPS)-induced in vitro and in vivo models. Methods: LPS-stimulated RAW264.7 macrophages and mouse peritoneal macrophages (MPMs) were used for evaluating the in vitro anti-inflammatory activity of inulicin, while endotoxemia mice were used for evaluating its in vivo action. Cytokines' levels were determined by ELISA. RT-qPCR and western blot were used for assaying the mRNA and protein levels of target genes. RAW264.7 macrophages transfected with reporter plasmid pNFκB-TA-luc or pAP1-TA-luc were used for assaying the activation of NF-κB or AP-1 signaling. Results: Inulicin significantly inhibited LPS-induced production of NO, IL-6, c-c motif chemokine ligand 2 (CCL2), and IL-1β in both RAW264.7 cells and MPMs. Mechanism study indicated that it could suppress inducible nitric oxide synthase, IL-6, CCL2, and IL-1β mRNA levels in LPS-stimulated RAW264.7 cells. Moreover, inulicin inhibited IκBα phosphorylation and prevented the nuclear translocation of p65, thereby inactivating NF-κB signaling. Concurrently, it also inhibited AP-1 signaling by reducing the phosphorylation of C-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK). In endotoxemia mice, a single intraperitoneal administration of inulicin could decrease the production of pro-inflammatory cytokines in serum and peritoneal lavage fluid. Conclusions: The present study demonstrates that inulicin possesses anti-inflammatory effects in vitro and in vivo, which suggests that inulicin might be a promising candidate for the treatment of inflammatory diseases. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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