Nepetin, a natural compound from Inulae flos, suppresses degranulation and eicosanoid generation through PLCγ1 and Akt signaling pathways in mast cells
2020
Ji, Ning | Kim, Sun-Gun | Park, Hyo-Hyun | Lee, Eujin | Lee, Youn Ju | Jin, Meihua | Lee, Eunkyung
Nepetin derived from the flowers of Inula japonica, Inulae flos, has been reported to exert several biological activities, including anti-inflammatory responses. In this study, we evaluated the anti-allergic property of nepetin with its molecular mechanisms in bone marrow-derived mast cells (BMMC) and mice. In this in vitro study, we investigated the inhibitory effects of nepetin on degranulation and generation of leukotriene C₄ (LTC₄) and prostaglandin D₂ (PGD₂) in IgE/antigen (Ag)-stimulated BMMC. The effect of nepetin on passive cutaneous anaphylaxis (PCA) reaction was also studied in mice. Nepetin reduced degranulation and LTC₄ generation in BMMC. The IgE/Ag-mediated signaling pathway demonstrated that nepetin suppressed intracellular Ca²⁺ level and activation of PLCγ1 and cPLA₂. However, MAPKs were not affected by nepetin in BMMC. In addition, nepetin treatment reduced PGD₂ production and suppressed cyclooxygenase-2 protein expression via the inhibition of the Akt and nuclear factor-κB signaling pathways. With respect to the local allergic response in vivo, oral administration of nepetin suppressed mast cell-dependent PCA reaction in a dose-dependent manner. The results of this study suggest that nepetin might have an anti-allergic potential related to mast cell-mediated inflammatory diseases.
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