Fargesin exerts anti-inflammatory effects in THP-1 monocytes by suppressing PKC-dependent AP-1 and NF-ĸB signaling

Background: Fargesin is a lignan from Magnolia fargesii, an oriental medicine used in the treatment of nasal congestion and sinusitis. The anti-inflammatory properties of this compound have not been fully elucidated yet.

Purpose: This study focused on assessing the anti-inflammatory effects of fargesin on phorbal ester (PMA)-stimulated THP-1 human monocytes, and the molecular mechanisms underlying them.

Methods: Cell viability was evaluated by MTS assay. Protein expression levels of inflammatory mediators were analyzed by Western blotting, ELISA, Immunofluorescence assay. mRNA levels were measured by Real-Time PCR. Promoter activities were elucidated by Luciferase assay.

Results: It was found that pre-treatment with fargesin attenuated significantly the expression of two major inflammatory mediators, cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS). Fargesin also inhibited the production of pro-inflammation cytokines (IL-1β, TNF-α) and chemokine (CCL-5). Besides, nuclear translocation of transcription factors nuclear factor-kappa B (NF-ĸB) and activator protein-1 (AP-1), which regulate multiple pro-inflammatory genes, was suppressed by fargesin in a PKC-dependent manner. Furthermore, among the mitogen-activated protein kinases (MAPKs), only c-Jun N-terminal kinase (JNK) was downregulated by fargesin in a PKC-dependent manner, and this reduction was involved in PMA-induced AP-1 and NF-ĸB nuclear translocation attenuation, demonstrated using a specific JNK Inhibitor.

Conclusion: Taken together, our results found that fargesin exhibits anti-inflammation effects on THP-1 cells via suppression of PKC pathway including downstream JNK, nuclear factors AP-1 and NF-ĸB. These results suggest that fargesin has anti-inflammatory properties with potential applications in drug development against inflammatory disorders.