Icariin inhibits TNF-α/IFN-γ induced inflammatory response via inhibition of the substance P and p38-MAPK signaling pathway in human keratinocytes.
Pro-inflammatory cytokines play a crucial role in the etiology of atopic dermatitis. We demonstrated that Herba Epimedii has anti-inflammatory potential in an atopic dermatitis mouse model; however, limited research has been conducted on the anti-inflammatory effects and mechanism of icariin, the major active ingredient in Herba Epimedii, in human keratinocytes. In this study, we evaluated the anti-inflammatory potential and mechanisms of icariin in the tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ)-induced inflammatory response in human keratinocytes (HaCaT cells) by observing these cells in the presence or absence of icariin. We measured IL-6, IL-8, IL-1β, MCP-1 and GRO-α production by ELISA; IL-6, IL-8, IL-1β, intercellular adhesion molecule-1 (ICAM-1) and tachykinin receptor 1 (TACR1) mRNA expression by real-time PCR; and P38-MAPK, P-ERK and P-JNK signaling expression by western blot in TNF-α/IFN-γ-stimulated HaCaT cells before and after icariin treatment. The expression of TNF-α-R1 and IFN-γ-R1 during the stimulation of the cell models was also evaluated before and after icariin treatment. We investigated the effect of icariin on these pro-inflammatory cytokines and detected whether this effect occurred via the mitogen-activated protein kinase (MAPK) signal transduction pathways. We further specifically inhibited the activity of two kinases with 20μM SB203580 (a p38 kinase inhibitor) and 50μM PD98059 (an ERK1/2 kinase inhibitor) to determine the roles of the two signal pathways involved in the inflammatory response. We found that icariin inhibited TNF-α/IFN-γ-induced IL-6, IL-8, IL-1β, and MCP-1 production in a dose-dependent manner; meanwhile, the icariin treatment inhibited the gene expression of IL-8, IL-1β, ICAM-1 and TACR1 in HaCaT cells in a time- and dose-dependent manner. Icariin treatment resulted in a reduced expression of p-P38 and p-ERK signal activation induced by TNF-α/IFN-γ; however, only SB203580, the p38 alpha/beta inhibitor, inhibited the secretion of inflammatory cytokines induced by TNF-α/IFN-γ in cultured HaCaT cells. The differential expression of TNF-α-R1 and IFN-γ-R1 was also observed after the stimulation of TNF-α/IFN-γ, which was significantly normalized after the icariin treatment. Collectively, we illustrated the anti-inflammatory property of icariin in human keratinocytes. These effects were mediated, at least partially, via the inhibition of substance P and the p38-MAPK signaling pathway, as well as by the regulation of the TNF-α-R1 and IFN-γ-R1 signals.
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China. Electronic address: jcdong2004@126.com.
Lingwen
L
Kong
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Jiaqi
J
Liu
Henan University of TCM, Zhengzhou, PR China.
Jia
J
Wang
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Qingli
Q
Luo
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Hongying
H
Zhang
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Baojun
B
Liu
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Fei
F
Xu
Department of Neurosurgery, Provincial Hospital Affiliated to Shandong University, Jinan, PR China.
Qi
Q
Pang
Department of Neurosurgery, Provincial Hospital Affiliated to Shandong University, Jinan, PR China.
Yingchao
Y
Liu
Department of Integrated Traditional Chinese and Western Medicine, Huashan Hospital, Fudan University, Shanghai, PR China; Institute of Integrated Traditional Chinese and Western Medicine of Fudan University, Shanghai, PR China.
Jingcheng
J
Dong
D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D002460:Cell Line; D016207:Cytokines / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000517:prevention & control*; D007371:Interferon-gamma / Q000037:antagonists & inhibitors*; D015603:Keratinocytes / Q000187:drug effects*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D017471:Receptors, Interferon / Q000037:antagonists & inhibitors; D018124:Receptors, Tumor Necrosis Factor / Q000037:antagonists & inhibitors; D015398:Signal Transduction / Q000187:drug effects; D013373:Substance P / Q000037:antagonists & inhibitors*; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors*; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*
D000894:Anti-Inflammatory Agents, Non-Steroidal; D016207:Cytokines; D005419:Flavonoids; D017471:Receptors, Interferon; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D013373:Substance P; D007371:Interferon-gamma; D048051:p38 Mitogen-Activated Protein Kinases; C056599:icariin
Cytokines; Icariin; Inflammation; P38MAPK; Substance P