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.

Kong L ，Liu J ，Wang J ，Luo Q ，Zhang H ，Liu B ，Xu F ，Pang Q ，Liu Y ，Dong J ... -  《-》

Illicium verum extract inhibits TNF-α- and IFN-γ-induced expression of chemokines and cytokines in human keratinocytes.

Illicium verum Hook. f. (star anise) has been used in traditional medicine for treatment of skin inflammation, rheumatism, asthma, and bronchitis. This study investigated the anti-inflammatory effects of Illicium verum extract (IVE) in the human keratinocyte HaCaT cell line. We investigated the effectiveness of IVE in tumor necrosis factor-α (TNF-α)/interferon-γ (IFN-γ)-induced human keratinocytes. To measure the effects of IVE on chemokine and pro-inflammatory cytokine expression in HaCaT cells, we used the following methods: cell viability assay, reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, western blotting, and luciferase reporter assay. IVE inhibited the expression of TNF-α/IFN-γ-induced mRNA and protein expression of thymus and activation-regulated chemokine (TARC/CCL17), macrophage-derived chemokine (MDC/CCL22), interleukin (IL)-6, and IL-1β. Furthermore, IVE decreased TNF-α/IFN-γ-induced mRNA expression of intercellular adhesion molecule-1 (ICAM-1). IVE inhibited nuclear factor (NF)-κB translocation into the nucleus, as well as phosphorylation and degradation of IκBα. IVE inhibited TNF-α/IFN-γ-induced NF-κB and signal transducer and activator of transcription (STAT)1 activation in a dose-dependent manner. In addition, IVE significantly inhibited activation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and Akt. Furthermore, IVE contained 2.14% trans-anethole and possessed significant anti-inflammatory activities. IVE exerts anti-inflammatory effects by suppressing the expression of TNF-α/IFN-γ-induced chemokines, pro-inflammatory cytokines, and adhesion molecules via blockade of NF-κB, STAT1, MAPK, and Akt activation, suggesting that IVE may be a useful therapeutic candidate for inflammatory skin diseases, such as atopic dermatitis.

Sung YY ，Kim YS ，Kim HK 《-》

Cytokine regulation by MAPK activated kinase 2 in keratinocytes exposed to sulfur mustard.

Uncontrolled inflammation contributes to cutaneous damage following exposure to the warfare agent bis(2-chloroethyl) sulfide (sulfur mustard, SM). Activation of the p38 mitogen activated protein kinase (MAPK) precedes SM-induced cytokine secretion in normal human epidermal keratinocytes (NHEKs). This study examined the role of p38-regulated MAPK activated kinase 2 (MK2) during this process. Time course analysis studies using NHEK cells exposed to 200μM SM demonstrated rapid MK2 activation via phosphorylation that occurred within 15 min. p38 activation was necessary for MK2 phosphorylation as determined by studies using the p38 inhibitor SB203580. To compare the role of p38 and MK2 during SM-induced cytokine secretion, small interfering RNA (siRNA) targeting these proteins was utilized. TNF-α, IL-1β, IL-6 and IL-8 secretion was evaluated 24h postexposure, while mRNA changes were quantified after 8h. TNF-α, IL-6 and IL-8 up regulation at the protein and mRNA level was observed following SM exposure. IL-1β secretion was also elevated despite unchanged mRNA levels. p38 knockdown reduced SM-induced secretion of all the cytokines examined, whereas significant reduction in SM-induced cytokine secretion was only observed with TNF-α and IL-6 following MK2 knockdown. Our observations demonstrate potential activation of other p38 targets in addition to MK2 during SM-induced cytokine secretion.

Yego EC ，Dillman JF 3rd 《-》

Suppression of thymus- and activation-regulated chemokine (TARC/CCL17) production by 3-O-β-D-glucopyanosylspinasterol via blocking NF-κB and STAT1 signaling pathways in TNF-α and IFN-γ-induced HaCaT keratinocytes.

A phytosterol derivative, 3-O-β-D-glucopyanosylspinasterol (spinasterol-Glc) isolated from leaves of Stewartia koreana was reported to inhibit LPS-induced cytokine production in macrophage cells. Thymus and activation regulated chemokine (TARC/CCL17) is produced in response to pro-inflammatory cytokines in keratinocytes, which is implicated in the development of inflammatory skin diseases. In present study, we investigated the effect of spinasterol-Glc on production of TARC/CCL17 induced by TNF-α and IFN-γ in human HaCaT keratinocytes. Spinasterol-Glc inhibited the mRNA and protein expression of TARC/CCL17 induced by TNF-α/IFN-γ in a dose-dependent manner. Inhibitors of c-Raf-1, p38 MAPK, and JAK2, suppressed the TNF-α/IFN-γ-induced production of TARC/CCL17, and phosphorylation of these signaling molecules were attenuated by spinasterol-Glc. The compound also inhibited phosphorylation of IKKα/β and IκB-α, and reduced translocation of NF-κB to the nucleus. We demonstrated that spinasterol-Glc suppressed the NF-κB-driven and the GAS-driven expression of luciferase reporter gene induced by TNF-α and IFN-γ. In addition, spinasterol-Glc inhibited the DNA binding of NF-κB and STAT1 to its cognate binding site. These results suggest that spinasterol-Glc has effective inhibitory effects on production of TARC/CCL17 in keratinocytes via inhibition of NF-κB as well as STAT activation, and could be utilized for development of a potential therapeutic agent against skin inflammatory diseases.

Jung MR ，Lee TH ，Bang MH ，Kim H ，Son Y ，Chung DK ，Kim J ... -  《-》

Icariin ameliorates TNF-α/IFN-γ-induced oxidative stress, inflammatory response and apoptosis of human immortalized epidermal cells through the WTAP/SERPINB4 axis.

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by increased sensitivity to environmental allergens and irritants. Icariin, a natural compound extracted from the herb Epimedium, has been traditionally used for its potential anti-inflammatory and antioxidant properties. This study aimed to investigate the regulatory effects of icariin on AD-like symptoms and to elucidate its underlying mechanisms. The effects of icariin on TNF-α/IFN-γ-induced HaCaT cell injury were assessed using various assays, including cell counting kit-8 for cell viability, flow cytometry for reactive oxygen species (ROS) levels, and colorimetric assays for malondialdehyde (MDA) levels and superoxide dismutase (SOD) activity. In addition, the study performed enzyme-linked immunosorbent assays to assess cytokines (IL-1β, IL-6, and IL-8) and chemokines (MDC, TARC, and RANTES) levels. Flow cytometry was used to quantify apoptotic rate, while a wound-healing assay was conducted to assess cell migration. The expression of WT1 associated protein (WTAP) and serpin family B member 4 (SERPINB4) at the mRNA and protein levels was determined using qRT-PCR and western blotting, respectively. The associations between WTAP and SERPINB4 were analyzed using RNA immunoprecipitation assay and m6A RNA immunoprecipitation assay. Icariin treatment significantly mitigated TNF-α/IFN-γ-induced oxidative stress, inflammatory response, and apoptosis in HaCaT cells, while also reversing the inhibitory effect on cell migration. Icariin reduced the expression of WTAP in TNF-α/IFN-γ-stimulated HaCaT cells. Overexpression of WTAP reversed the effects of icariin in TNF-α/IFN-γ-stimulated HaCaT cells. WTAP silencing inhibited the mRNA stability of SERPINB4 through the m6A modification. SERPINB4 overexpression attenuated the effects of WTAP silencing on oxidative stress, inflammatory response, apoptosis, and migration of TNF-α/IFN-γ-stimulated HaCaT cells. Icariin treatment downregulated SERPINB4 expression by regulating WTAP in TNF-α/IFN-γ-stimulated HaCaT cells. Icariin ameliorated TNF-α/IFN-γ-induced human immortalized epidermal cell injury through the WTAP/SERPINB4 axis, highlighting the potential for targeted interventions in AD pathogenesis.

Wang X ，Wang J ，Tian L 《-》