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IL-9 induces IL-8 production via STIM1 activation and ERK phosphorylation in epidermal keratinocytes: A plausible mechanism of IL-9R in atopic dermatitis
Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, TaiwanDepartment of Dermatology, Kaohsiung Veterans General Hospital, Kaohsiung, TaiwanDepartment of Dermatology, National Yang-Ming University College of Medicine, Taipei, Taiwan
Corresponding author at: National Environmental Health Research Center, National Health Research Institutes, National Environmental Health Research Center, Kaohsiung Medical University, No. 35, Keyan Road, Zhunan Town, Miaoli County 35053, Taiwan. Tel.: +886 37 246166x31010; fax: +886 37 582 946.
Department of Dermatology, Kaohsiung Medical University, Kaohsiung, TaiwanNational Environmental Health Research Center, National Health Research Institute, Miao-Li, Taiwan
Corresponding author at: Department of Dermatology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, 123 Dapi Rd, Kaohsiung 83301, Taiwan. Tel.: +886 7 3121101x2299; fax: +886 7 7337612.
Department of Dermatology, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, TaiwanDepartment of Dermatology, Chang Gung University College of Medicine, Taoyuan, Taiwan
IL-9R expression in epidermal keratinocytes is enhanced by IL-4.
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IL-9 induces IL-8 production from keratinocyte via STIM1 and ERK activation.
Abstract
Background
IL-9 and its receptor play important roles in the pathogenesis of asthma. Its role in atopic dermatitis (AD) was examined in just a few studies, including nucleotide polymorphisms, increased transcriptional levels of IL-9 and IL-9R in diseased skin, and an association of blood IL-9 levels with clinical severity.
Objective
Little was known about the pathophysiological regulation of IL-9/IL-9R in AD skin. We asked whether IL-9R was expressed in epidermal keratinocytes; if so, what the functional outcome, cytokine production, and signaling pathway of IL-9/IL-9R in keratinocytes are.
Methods
We measured and compared the expression of IL-9R in skin from AD patients and controls by immunofluorescence. We also performed in vitro studies on the IL-9-treated primary keratinocytes, including flow cytometry for IL-9R expressions, Western blotting for mTOR, S6K, ERK, p38, and STAT3 activations, ELISA for cytokine levels, and immunofluorescence for STIM1.
Results
We found that IL-9R was indeed expressed in keratinocytes but not in fibroblasts. Its expression in keratinocytes was enhanced by IL-4 but not by TGF-beta1. IL-9 induced a moderate production of IL-8 but not CXCL16, CCL22, TSLP, nor IL-33. IL-9 induced formation of STIM1-puncta. IL-9 induced ERK phosphorylation both dose- and time-dependently, but not mTOR, S6K, p38, or STAT3. Pretreatment with U0126 (ERK inhibitor) but not rapamycin (mTOR inhibitor) abrogated the IL-9-mediated IL-8 production. Blockage of STIM1 with BTP2 or SKF96265 abrogated ERK phosphorylation and IL-8 production induced by IL-9.
Conclusion
This study represents the first to show the regulation of the IL-9-STIM1-ERK-IL-8 axis in keratinocyte, and how the axis might play an important role in the pathophysiology of AD.
Atopic dermatitis (AD) is a common chronic inflammatory skin disease usually associated with personal or family history of allergic diseases, including AD, asthma, and allergic rhinitis [
Transepidermal water loss, serum IgE and beta-endorphin as important and independent biological markers for development of itch intensity in atopic dermatitis.
]. AD skin is characterized microscopically by spongiotic dermatitis with moderate dermal immune cell infiltrates. The immune abnormalities of AD have been found to involve aberrant T helper cell polarization, imbalances in cytokines and chemokines, and dysregulation of innate immunity. Filaggrin mutations [
] from epidermal keratinocytes are reported to mediate the development of asthma, suggesting that epidermal keratinocytes play a major role in the pathogenesis of AD and bronchial asthma. In fact, one of our previous studies found that IL-31, a pruritus-related cytokine, activated IL-31R, induced calcium propagation, activated STAT3, and released beta-endorphin in keratinocytes [
Mechanistic correlations between two itch biomarkers, cytokine interleukin-31 and neuropeptide beta-endorphin, via STAT3/calcium axis in atopic dermatitis.
In AD skin, a significant portion of T cells is polarized to Th2 subsets. IL-9 was previously thought to be a Th2 cytokine, but it is now known that TGF-beta1 is able to reprogram Th2 cells to produce IL-9 instead of Th2 cytokines [
]. The activation of IL-9R causes different physiological functions in different cells. One recent mouse study has described the biological role of IL-9 secreting cells in the mediation of tumor immunity to melanoma [
]. Only few studies examined the role of IL-9R of keratinocytes in AD. One recent study showed that K5.hTGF-β1 transgenic mice exhibiting a psoriasis-like phenotype with increased expressions of IL-9 and IL-9R in skin [
A calcium-activated chloride channel (HCLCA1) is strongly related to IL-9 expression and mucus production in bronchial epithelium of patients with asthma.
The synergistic effects of the IL-9 gene and environmental exposures on asthmatic Taiwanese families as determined by the transmission/disequilibrium test.
]. Compared with the large number studies addressing the role of IL-9/IL-9R in asthma, there are only a limited number of studies investigating its role in AD. One of these studies, reported that transcriptional level of IL-9 and IL-9 receptor is significantly increased in lesional skin areas of AD patients as compared to normal control skin [
]. Since keratinocytes make up the majority of cells in the skin, we sought to investigate whether IL-9R is expressed in keratinocytes and, if so, what functional outcomes and pathophysiological regulations are in AD.
2. Materials and methods
2.1 Reagents and ELISAs
IL-9 was purchased from R&D (Minneapolis, MN, USA). ELISA kits for IL-8, CXCL16, IL-33, CXCL1, and CCL22 were also purchased from R&D to measure their levels in conditioned media from IL-9-treated keratinocytes. ELISA kit for TSLP was obtained from BioLegend (San Diego, CA). Multiplex cytokine array kits, including Human cytokine array panel A (ARY005) and Human chemokine array kit (ARY017), were purchased from R&D (Minneapolis, MN, USA). The mTOR inhibitor rapamycin was obtained from Sigma–Aldrich (St. Louis, MO) and ERK inhibitor (U0126) from Promega (Madison, WI, USA).
2.2 Primary culture of epidermal keratinocytes and dermal fibroblasts
Normal human keratinocytes were obtained from adult foreskins through routine circumcision. The keratinocytes were harvested and cultured as described previously [
]. Briefly, skin specimens were washed with PBS (pH 7.2), cut into small pieces, and harvested in a medium containing 0.25% trypsin (Gibco, Grand Island, NY) overnight at 4 °C. The epidermal sheet was lifted from the dermis by a fine forceps. The epidermal cells were spun down by centrifugation (500 × g, 10 min) and then were dispersed into individual cells by repeated aspiration. The keratinocytes were gently resuspended in 5 ml of keratinocyte–serum-free medium (Gibco), which contained 25 μg/ml bovine pituitary extract and 5 ng/ml recombinant human epidermal growth factor. Keratinocytes at the third passage were then grown in a keratinocyte–serum-free medium without bovine pituitary extract and recombinant human epidermal growth factor for 24 h before experimentation.
For fibroblasts, the primary fibroblasts were harvested as described previously [
]. Briefly, dermal parts after lifting of epidermis were cut to 1–2 mm3 and incubated with Dulbecco's Modified Eagle Medium (DMEM; Invitrogen, Grand Island, NY) supplemented with 10% FBS (Invitrogen), 2 mM l-glutamine (Invitrogen) and 0.1 mM 2-mercaptoethanol (Sigma–Aldrich), along with 50 units/ml of penicillin and 50 g/ml of streptomycin (Invitrogen). The 3rd passage of human fibroblasts were used for the experiments.
2.3 Cytokine stimulations and blocking experiments
In preparation for the measurement of IL-9R, we treated cells with IL-4 (up to 10 ng/ml) and/or TGF-beta1 (up to 50 ng/ml) for 24 h and stained cells with 1:100 mouse anti-IL-9R (BioLegend, San Diego, CA) overnight at 4 °C. We then measured the expressions of IL-9R by flow cytometry (BD Biosciences, San Jose, CA, USA). To measure what cytokines/chemokines would be induced by IL-9 treatment, we treated keratinocytes with IL-9 at 0, 5, 10, and 20 ng/ml for 12 or 24 h and then measured the expressions of individual cytokines by ELISA. To determine the intracellular signaling pathways in keratinocytes by IL-9, we treated cells with IL-9 at 10 ng/ml for 0, 5, 10, 15, 20, and 30 min or IL-9 at 0, 1, 5, 10, and 20 ng/ml for 10 min and then evaluated the signaling pathways by Western blot. To determine whether IL-9 might induce the production of IL-8 through ERK or mTOR pathways, we pretreated keratinocytes with U0126 (an ERK inhibitor) or rapamycin (an mTOR inhibitor) at indicated concentrations for 2 h prior to their treatment with IL-9. Finally, for STIM1 blocking, we pretreated keratinocytes with STIM1 inhibitors (BTP-2 up to 0.1 nM or SKF96365 up to 50 nM, both from Sigma–Aldrich) for 24 h before IL-9 treatments.
2.4 Immunoflorescent study for IL-9R in skin
Immunofluorescent studies for IL-9R were performed on 5-μm serial tissue sections obtained from skin of AD patients (active and stable), patients with psoriasis, and controls (n = 3, 3, 2, and 5, respectively). The protocol for these studies were approved by IRB from the affiliated hospital. All participants provided written informed consent. To perform these studies, all sections were blocked with 3% bovine serum albumin at room temperature for 2 h. After the blocking, the sections were incubated with rabbit polyclonal antihuman IL-9R (1:200; GeneTex, GTX87356, Irvine, CA) at 4 °C overnight. Image analysis was performed using NIH IMAGEJ (http://rsbweb.nih.gov/ij/). Fluorescent intensity index (0–255) was calculated in five random mid-power fields above the dermoepidermal junction.
For animals, female C57BL/6JNarl mice (8–12 weeks old) were obtained from the National Laboratory Animal Center-Tainan Facility (Tainan, Taiwan). Mice were painted with benzopyrene at 0.5 ppm/mice/day for 5 days. Control mice received a similar treatment but patched with acetone, the solvent control. At day 8, mice were sacrificed and their samples of skin were incubated with the same IL-9R antibody, that crossly reacts with mouse tissue, at 4 °C overnight.
2.5 Immunofluorescent staining of IL-9R and STIM1
In preparation for the measurement of IL-9R, we stained keratinocytes with 1:100 mouse anti-IL-9R (BioLegend, San Diego, CA) overnight at 4 °C. For the measurement of STIM1, we incubated keratinocytes with mouse anti-STIM1 (1:100, Abnova, Walnut, CA) followed by Alexa Fluor® 568-rabbit anti-mouse IgG (Invitrogen, Carlsbad, CA). STIM1 puncta were analyzed using the feature of “Analyze Particles” in ImageJ. Briefly, following background subtraction, fluorescent images were converted into a binary mask and puncta were identified according to their relative intensity, compared with background, size, and circularity.
2.6 Western blotting
Methods for Western blotting have been described previously [
]. Antibodies for STAT3 (1:1000), ERK p38 (1:1000), mTOR (1:1000), and S6K (1:1000) were obtained from Cell Signaling Technology (Boston, MA, USA). Specific proteins were detected using an enhanced chemiluminescence detection system (Amersham Pharmacia Biotech, Piscataway, NJ, USA), and visualized films recorded on a digital imaging system (Alpha Imager 2000; Alpha Innotech Corp., San Leandro, CA, USA).
2.7 Statistical analyses
The numeric variables between two groups were compared by nonparametric Mann–Whitney U test, while ratio variables were compared by Chi-square test using SPSS ver 14 (Chicago, IL). A p-value less than 0.05 was considered significant.
3. Results
3.1 IL-9R was increased in atopic skin
We performed immunofluorescent studies to determine whether IL-9R would be more expressed in AD skin than control skin. IL-9R was barely expressed in control skin. In psoriatic skin, there were some dermal expressions of IL-9R in psoriatic skin, however, the epidermal expressions of IL-9R were limited. In AD skin, IL-9R expressions were highly increased in active AD epidermal skin and slightly increased in stable AD epidermal skin (Fig. 1A) . In animals, IL-9R was found to be localized in the epidermis and in the hair follicle. The expressions of IL-9R in the epidermis from benzopyrene-painted mice were higher than those from acetone-painted mice. Next, to find out whether normal epidermal keratinocytes and normal dermal fibroblasts, two major primary skin cells, expressed IL-9R, we performed flow cytometry to measure the surface expressions of IL-9R of normal primary keratinocytes and fibroblasts harvested from adult foreskin. We found a small but appreciable expression of IL-9R in epidermal keratinocytes but not in dermal fibroblasts (Fig. 1A).
Fig. 1Increased expressions of IL-9R in atopic skin and IL-4 induced IL-9R expressions in epidermal keratinocytes. (A) Skin from normal controls (n = 5), patients with active AD (n = 3), patients with stable AD (n = 3), and patients with psoriasis (n = 2), were stained by anti-IL-9R antibody for immunohistochemistry (200X). Skin from mice painted with benzopyrene or acetone was stained by the same antibody. Keratinocytes and fibroblasts were harvested from adult foreskin. The IL-9R expressions were measured on those cells by flow cytometry (n = 3 each). (B) Normal human primary keratinocytes were harvested from foreskin. Keratinocytes were treated with IL-4 at 5 or 10 ng/ml and/or TGF-beta 1 at 20 or 50 ng/ml for 24 h. The expressions of IL-9R in keratinocytes were measured by flow cytometry.
3.2 IL-4 treatment induced the expression of IL-9R in keratinocytes
We next asked what cytokine might induce the expression of IL-9R in keratinocytes. Because Th2 skewing is prominent in AD skin, we first added IL-4, a representative Th2 cytokine, to investigate its effect on expression of IL-9R. Furthermore, because IL-9R is increased in the skin of K5-TGF-β1 transgenic mice [
], we also investigated the effect of TGF-β1 on IL-9R expression. We found that IL-4 treatment (10 ng/ml for 24 h) significantly increased the expression of IL-9R in keratinocytes (Fig. 1B). However, while TGF-beta1 (50 ng/ml for 24 h) promoted the expression of IL-9R to some extent, it did not increase the expression of IL-9 expressions as much as IL-4 did. Combining both IL-4 and TGF-beta1 did not further increase the expression of IL-9R (Fig. 1B).
3.3 IL-9 treatment increased production of IL-8, but not CCL22, CXCL16, TSLP, CXCL1, nor IL-33, from primary keratinocytes
To the best of our knowledge, no study has investigated the immunological effect of IL-9R activation and its mechansitic regulations in keratinocytes. To screen for what cytokines and/or chemokines would be increased by IL-9 treatment, we measured a panel of cytokines and chemokines using a multiplex ELISA that profiles the expressions of several dozen cytokines and chemokines. Among these cytokines and chemokines, CCL22, CXCL16, and IL-8 levels were increased mostly (Fig. 2A) . Measuring the individual expressions of those cytokines by standard ELISAs, we found that IL-9 dose-dependently and significantly increased the expression of IL-8 in keratinocytes (Fig. 2B) but only minimally increased CCL22 and CXCL16. We also tested whether IL-9 treatment would increase TSLP, CXCL1, and IL-33, three important keratinocyte-derived cytokines in AD by standard ELISAs and found that it did not (Fig. 2B).
Fig. 2IL-9 induced production of IL-8 in a dose- and time-dependent manner. (A) The profiles of cytokines and chemokines from supernatants of IL-9-treated keratinocytes were measured by multiplex ELISA. The expressions of CXCL16, CCL22, and IL-8 were greatly enhanced by IL-9 treatment (n = 2). (B) To confirm the results from the multiplex ELISA, we measured the expressions of CXCL16, CCL22, IL-8, IL-33, CXCL1, as well as TSLP, in condition medium from IL-9-treated keratinocytes by standard ELISA. Keratinocytes were treated with IL-9 for 24 h at indicated concentrations. The experiments were repeated 3 times. *p < 0.05.
3.4 IL-9 activated ERK phosphorylation both dose-dependently and time-dependently
Next, we asked what signaling pathways were activated in keratinocytes treated with IL-9. To find out, we used Western blot to measure the expression of total and phosphorylated forms of mTOR, S6K, ERK, STAT3, and p38 in IL-9-treated keratinocytes. Kinetic analysis revealed that IL-9 (10 ng/ml) activated ERK phosphorylation at 5, 10, and 15 min (Fig. 3A) , but not mTOR, S6K, STAT3, or p38 (from 5 to 30 min). Ten-minute treatment with IL-9 at different concentrations (0, 1, 5, 10, and 20 ng/ml) induced phosphorylation of ERK but not mTOR, S6K, STAT3, or p38.
Fig. 3IL-9 induced IL-8 production through ERK in keratinocytes. (A) Human primary epidermal keratinocytes were treated with IL-9 for indicated time at 10 ng/ml (left panel). They were treated with IL-9 for 10 min at indicated concentrations (right panel). The total and phosphorylated forms of mTOR, S6K, ERK, STAT3, and p38 were measured by Western blot (n = 3, a representative blot is shown). (B) Keratinocytes were pretreated with U0126 or rapamycin for 2 h before treatment with IL-9. The IL-8 production was measured by ELISA after IL-9 treatment for 24 h (three repeated experiments). *p < 0.05.
3.5 IL-9 induced IL-8 production in keratinocytes through ERK phosphorylation
Since we have found that IL-9 induces the phosphorylation of ERK along with the production IL-8, we hypothesized that IL-9 might induce the production of IL-8 via phosphorylation of ERK. We investigated this possibility by pretreating keratinocytes with various concentrations of U0126 (an ERK inhibitor) or rapamycin (an mTOR inhibitor) for two hours prior to their treatment with IL-9. IL-8 production was measured by ELISA. IL-9 consistently induced approximately a 2-fold increase in IL-8 level. Pretreatment with U0126 (0.5, 1, and 5 ng/ml) abrogated increases of IL-8 in IL-9-treated keratinocytes but pretreatment with rapamycin has no such effect (Fig. 3B), indicating that indeed IL-9 induced the production of IL-8 production through its activation of ERK.
3.6 IL-9 induced ERK phosphorylation through STIM1 activation
Since the activation of several cytokine receptors requires the propagation of calcium, we next asked whether IL-9 activation of ERK required calcium propagation and whether that occurred through its activation of STIM1. STIM1 is a Ca2+ sensor that activates CRAC channels and migrates from the Ca2+ store to the plasma membrane (so called store-operated channel). We first measured the ERK activation by IL-9 with or without STIM1 inhibitors, either BTP2 or SKF96365 (Fig. 4A and B , respectively). The increases in the phosphorylation of ERK were abolished by pretreatment with both STIM1 inhibitors, indicating the IL-9-mediated ERK phosphorylation occurred through the activation of STIM1. We then wanted to determine whether IL-9 activated STIM1. To find out, we treated the keratinocytes with IL-9 (10 ng/ml) and measured the expression of STIM1 by immunofluorescent exam (Fig. 4C). STIM1 expressions were diffuse in the cytosol at baseline, while punctate aggregation of STIM1 was apparent in cells treated with IL-9 at 30 s and 2 min. At 30 min after IL-9 treatment, the punctate aggregation of STIM1 in the cytosol resumed to baseline diffuse distributions. Finally, we asked whether the IL-9 induced the phosphorylation of ERK and the production of IL-8 through activation of STIM1 in keratinocytes. We pretreated IL-9-incubated keratinocytes with the STIM1 inhibitors of BTP2 or SKF96365, and measured the expressions of IL-8 in the condition media and the phophorylation of ERK in keratinocytes (Fig. 4A and B). Both the production of IL-8 and phosphorylation of ERK by IL-9 in keratinocytes were inhibited by the STIM1 inhibitors, indicating IL-9 induced the production of IL-8 through its activation of STIM1 followed by phosphorylation of ERK.
Fig. 4IL-9 induced IL-8 production through STIM1 activation followed by ERK phosphorylation. (A) Keratinocytes were pre-treated with BTP2 using indicated concentrations for 24 h before IL-9 was added. Total and phosphorylated forms of mTOR, S6K, and ERK were measured by Western blot (n = 3, one representative blot was shown). IL-8 level in the condition media was measured by ELISA (n = 3). *p < 0.05. (B) Keratinocytes were pre-treated with SKF96365 using indicated concentrations for 24 h before IL-9 was added. Total and phosphorylated forms of mTOR, S6K, and ERK were measured by Western blot (n = 3, one representative blot was shown). IL-8 level in the condition media was measured by ELISA (n = 3). *p < 0.05. (C) Keratinocytes were treated with IL-9 (10 ng/ml) for 0, 0.5, 2, and 30 min. The expressions of STIM1 were measured by immunofluorescent exams (n = 3). The values inside (C) represent the STIM1 puncta fluorescent values as analyzed by the feature of “Analyze Particle” in Image J.
This study found IL-9R to be increased in AD skin and its expression in keratinocytes to be increased by IL-4. IL-9 treatment in keratinocytes leads to the production of IL-8 through its activation of STIM1 and subsequently phosphorylation of ERK. This is the first study to show how the regulatory role IL-9/IL-9R plays in epidermal keratinocytes.
The regulation of IL-9 activation has been investigated in different cells. For example, IL-9/IL-9R interactions could result in T cell activation and IL-9R could regulate the production of IgE from germinal center B cells [
]. The current study provides first evidence that IL-9R is expressed in normal human primary keratinocytes and that the expression of IL-9R expression is increased by IL-4, a Th2 cytokine. In the Th2 immunological milieu of AD, increased expressions of IL-9R by IL-4 may further reinforce the role of IL-9R in AD.
In AD, one study demonstrated that plasma levels of IL-8 were detectable in most cases of AD but not in controls, patients with allergic rhinitis or asthma [
]. In skin, IL-8 in the stratum corneum might act as an indicator of the severity of inflammation in AD lesions. Comparing IL-18, VEGF, and TGF-α, one study has shown IL-8 blood levels is associated with severity scores in AD [
Filaggrin loss-of-function mutations are associated with enhanced expression of IL-1 cytokines in the stratum corneum of patients with atopic dermatitis and in a murine model of filaggrin deficiency.
]. It was demonstrated that IL-8 also significantly enhances the generation of LTB4 and LTC4 of neutrophils from patients with AD than those from controls [
]. IL-13 and IL-4, two Th2 cytokines, convert IL-8 into monocyte chemotactic agonists, by up-regulating the expression of IL-8 receptor, contributing to the accumulation and positioning of mononuclear phagocytes in Th2-dominated responses [
]. In contrast to the multifaceted role of IL-8 in AD, the neutrophil migration and activation are impaired in AD, possibly due to the ligand-binding or ligand-signaling defects [
In this study, IL-9 induced IL-8 production through STIM1 activation followed by ERK phosphorylation in epidermal keratinocytes. Cell type specificity may affect the regulatory mechanisms of IL-9 activation. It has been shown in neuron cells that antiapoptotic effects of IL-9 effects were mediated by the JAK/STAT but not ERK pathway [
]. The signaling pathways of IL-8 production in keratinocytes have been reported in several studies. Cells from anaplastic large cell lymphoma induce HMGB-1-dependent IL-8 production by keratinocytes via NF-κB activation [
An environmental contaminant, benzo(a)pyrene, induces oxidative stress-mediated interleukin-8 production in human keratinocytes via the aryl hydrocarbon receptor signaling pathway.
]. Consistent with our results that showed the role of STIM1 in ERK phosphorylation and IL-8 production in keratinocytes, the ORAI1 complex is important in the production of IL-8 by human airway epithelial cells from cystic fibrosis [
]. The role of IL-9-ERK-IL-8 axis in epidermal keratinocytes found in the current study is consistent with a previous study of airway smooth muscle cells [
]. The current study is the first to reveal the role of STIM1 in the IL-9 mediated ERK phosphorylation and IL-8 production.
This study also found that IL-4, not TGF-beta1, induced the expression of IL-9R in keratinocytes. To the best of our knowledge, no study has shown how IL-9R expression is regulated, particularly in epidermal or epithelial cells. One recent study has, however, demonstrated that IL-9 acts on Th1 and promotes IL-4 secretion in allergic contact dermatitis [
], suggesting a reciprocal IL-4/IL-9 cycle in the proinflammatory conditions.
There remains no clinical application of IL-9 neutralizing in the treatment of AD to date. However, there are application of IL-9 neutralizing antibodies in mouse models of asthma and allergic contact dermatitis (ACD). For example, transgenic expression of TSLP in mouse lungs stimulated IL-9 production in vivo while the anti-IL-9 treatment attenuated TSLP-induced airway inflammation [
]. In a mouse model of ACD to nickel, in vivo allergen responses and allergen-specific IFN-γ production is enhanced in both WT mice with IL-9 neutralizing or in IL-9(−/−) mice [
In conclusion, we found that IL-9R is increased in AD skin and that the expressions of IL-9R in keratinocytes are enhanced by IL-4. IL-9 treatment of keratinocytes leads to the production of IL-8 through its activation STIM1 and the phosphorylation ERK, making it the first study to show the regulatory process of IL-9/IL-9R in epidermal keratinocytes. We hypothesize that IL-9-STIM1-ERK-IL-8 axis might play an important role in the pathogenesis of AD.
Funding sources
This study is supported by research funding provided by Ministry of Science and Technology (MOST-102-2314-B-010-005-MY2), Kaohsiung Veterans General Hospital (KSC104-050), and Kaohsiung Chang Gung Memorial Hospital (CMRPG8C0821 and CMRPG8D1541).
Acknowledgements
This study is supported by research funding provided by Ministry of Science and Technology (MOST102-2314-B-010-005-MY2), Kaohsiung Veterans General Hospital (KSC104-050), and Kaohsiung Chang Gung Memorial Hospital (CMRPG8C0821 and CMRPG8D1541).
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Chang C.H.
Yu H.S.
Transepidermal water loss, serum IgE and beta-endorphin as important and independent biological markers for development of itch intensity in atopic dermatitis.
Mechanistic correlations between two itch biomarkers, cytokine interleukin-31 and neuropeptide beta-endorphin, via STAT3/calcium axis in atopic dermatitis.
A calcium-activated chloride channel (HCLCA1) is strongly related to IL-9 expression and mucus production in bronchial epithelium of patients with asthma.
The synergistic effects of the IL-9 gene and environmental exposures on asthmatic Taiwanese families as determined by the transmission/disequilibrium test.
Filaggrin loss-of-function mutations are associated with enhanced expression of IL-1 cytokines in the stratum corneum of patients with atopic dermatitis and in a murine model of filaggrin deficiency.
An environmental contaminant, benzo(a)pyrene, induces oxidative stress-mediated interleukin-8 production in human keratinocytes via the aryl hydrocarbon receptor signaling pathway.
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