Apamin inhibits TNF-a- and IFN-?-induced inflammatory cytokines and chemokines viasuppressions of NF-?B signaling pathway and STAT in human keratinocytes

Background: Atopic dermatitis (AD) is identified by an increase in infiltrations of several inflammatory cells including type 2 helper (Th2) lymphocytes. Th2-related chemokines such as thymus and activation-regulated chemokine (TARC/CCL17) and macrophage-derived chemokine (MDC/CCL22), and pro-inflammatory cytokines including interleukin (IL)-1ß and IL-6 are considered to play a crucial role in AD. Tumor necrosis factor (TNF)-a- and interferon (IFN)-? induce the inflammatory condition through production of TARC, MDC, IL-1ß and IL-6, and activations of related transcription factors, such as nuclear factor kappa-light-chain-enhancer of activated B cells (NF-?B) and signal transducer and activator of transcription (STAT) in keratinocytes. Apamin, a peptide component of bee venom, has been reported its beneficial activities in various diseases. However, anti-inflammatory effects of apamin on inflammatory condition in keratinocytes have not been explored. Therefore, the present study aimed to demonstrate the anti-inflammatory effect of apamin on TNF-a- and IFN-?-induced inflammatory condition in keratinocytes. Methods: HaCaT was used as human keratinocytes cell line. Cell Counting Kit-8 was performed to measure a cytotoxicity of apamin. The effects of apamin on TNF-a-/IFN-?-induced inflammatory condition were determined by real-time PCR and Western blot analysis. Further, NF-?B signaling pathways, STAT1, and STAT3 were analyzed by Western blot and immunofluorescence. Results: Apamin ameliorated the inflammatory condition through suppression of Th2-related chemokines and pro-inflammatory cytokines. Further, apamin down-regulated the activations of NF-?B signaling pathways and STATs in HaCaT cells. Conclusions: These results suggest that apamin has therapeutic effect on AD through improvement of inflammatory condition.