Rumiko Saito

Tohoku University, Miyagi, Japan

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Publications (10)28.64 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Notch signaling controls a number of cellular processes, including cell fate decisions, proliferation, differentiation, and survival/apoptosis, in multiple tissues. In the epidermis, Notch1 functions as a molecular switch that controls the transition of cells from an undifferentiated state into a differentiated state. To clarify the functions of Notch in the regenerated epidermis during wound healing. Wounds on mouse skin were immunostained. To investigate the functions of Notch, Notch was inhibited in primary keratinocytes by treatment with a γ-secretase inhibitor and by small interfering RNA-mediated knockdown, and was activated by a recombinant adenovirus approach. Notch1 and Notch2 were down-regulated in the regenerated epidermis during wound healing. To clarify the significance of this down-regulation, we examined its effect on expression of the interleukin (IL)-1 family of proinflammatory cytokines because wounds are exposed to pathogens from the outside world. Among the IL-1 family, IL-36α expression was induced by Notch inhibition. This was consistent with the decreased IL-36α expression in Notch-overexpressing keratinocytes. Notch down-regulation in the regenerated epidermis may reinforce defense against stress from the outside world by inducing IL-36α expression. Next, we examined the effects of Notch down-regulation on keratinocyte growth and differentiation. Notch down-regulation did not alter keratinocyte proliferation. On the other hand, Notch1 down-regulation suppressed induction of spinous layer-specific keratins (keratin1 and keratin10) in keratinocytes, which was consistent with the decreased expression of these keratins in the regenerated epidermis. The reduced levels of these keratins would increase cellular flexibility. Notch down-regulation in the epidermis appears to contribute to tissue regeneration during wound healing. Copyright © 2015 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.
    Journal of Dermatological Science 04/2015; 79(1). DOI:10.1016/j.jdermsci.2015.04.003 · 3.34 Impact Factor
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    ABSTRACT: The objective of the study was to investigate the influence of Asian dust storms (ADS) on pulmonary function of school children and the relationship of this effect with interleukin-8. Morning peak expiratory flow (PEF) was measured daily in 399 children from April to May 2012 and in 384 of these children from March to May 2013. The data were analyzed for an association between ADS events and PEF by linear mixed models. Interleukin-8 transcriptional activity was assessed in THP-G8 cells stimulated by airborne particles collected on ADS days. Seven ADS days were identified: April 23 and 24, 2012; March 8 to 10, 2013; and March 19 and 20, 2013. Changes in PEF after ADS exposure were −8.17 L/min (95% confidence interval, −11.40 to −4.93) in 2012 and −1.17 L/min (−4.07 to 1.74) in 2013, and there was a significant difference between 2012 and 2013. Interleukin-8 transcriptional activity was significantly higher in 2012 at -fold compared to in March 8 to 10, 2013, and in March 19 and 20, 2013. The influence of ADS events on pulmonary function of children differs with each ADS event and may be related to interleukin-8 production.
    01/2015; 2015:1-11. DOI:10.1155/2015/583293
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    ABSTRACT: Several dermatoses, including psoriasis, atopic dermatitis, and rosacea, alter the expression of the innate immune effector human cathelicidin antimicrobial peptide (CAMP). To elucidate the roles of aberrant CAMP in dermatoses, we performed cDNA array analysis in CAMP-stimulated human epidermal keratinocytes, the primary cells responding to innate immune stimuli and a major source of CAMP LL37 in skin. Among LL37-inducible genes, IL-1 cluster genes, particularly IL36G, are of interest because we observed coordinate increases in CAMP and IL-36γ in the lesional skin of psoriasis, whereas virtually no CAMP or IL-36γ was observed in nonlesional skin and normal skin. The production and release of IL-36γ were up to 20-30 ng/ml in differentiated keratinocytes cultured in high-calcium media. G-protein inhibitor pertussis toxin and p38 inhibitor suppressed IL-36γ induction by LL37. As an alarmin, LL37 induces chemokines, including CXCL1, CXCL8/IL8, CXCL10/IP-10, and CCL20/MIP3a, and IL-36 (10-100 ng/ml) augments the production of these chemokines by LL37. Pretreatment with small interfering RNA against IL36γ and IL-36R IL36R/IL1RL2 and IL1RAP suppressed LL37-dependent IL8, CXCL1, CXCL10/IP10, and CCL20 production in keratinocytes, suggesting that the alarmin function of LL37 was partially dependent on IL-36γ and its receptors. Counting on CAMP induction in innate stimuli, such as in infection and wounding, IL-36γ induction by cathelicidin would explain the mechanism of initiation of skin inflammation and occasional exacerbations of psoriasis and skin diseases by general infection.
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    ABSTRACT: Abstract Objective: Asian dust storms (ADS) contain various airborne particles that may augment airway inflammation by increasing the level of interleukin-8. The objective of the study was to investigate the association of exposure to an ADS with worsening of symptoms of adult asthma and the effect of ADS particles on interleukin-8 transcriptional activity. Methods: The subjects were 112 patients with mild to moderate asthma who recorded scores for their daily upper and lower respiratory tract symptoms and measured morning peak expiratory flow (PEF) from March to May 2011. Interleukin-8 transcriptional activity was assessed in THP-G8 cells that were exposed to airborne particles collected during days of ADS exposure. Results: Of the 112 patients, 31 had comorbid allergic rhinitis (AR) and/or chronic sinusitis (CS), and had worsened scores for upper respiratory tract symptoms on ADS days compared to non-ADS days. Scores for lower respiratory tract symptoms during ADS days were higher than non-ADS days in all patients. Three patients also had unscheduled hospital visits for exacerbation of asthma on ADS days. However, there was no significant difference in daily morning PEF between ADS and non-ADS days. Airborne particles collected on ADS days induced interleukin-8 transcriptional activity in THP-G8 cells compared to the original soil of the ADS. Conclusion: Exposure to an ADS aggravates upper and lower tract respiratory symptoms in patients with adult asthma. ADS airborne particles may increase airway inflammation through enhancement of interleukin-8 transcriptional activity.
    Journal of Asthma 03/2014; DOI:10.3109/02770903.2014.903965 · 1.83 Impact Factor
  • Journal of Dermatological Science 02/2013; 69(2):e60-e61. DOI:10.1016/j.jdermsci.2012.11.486 · 3.34 Impact Factor
  • Journal of Dermatological Science 02/2013; 69(2):e75-e76. DOI:10.1016/j.jdermsci.2012.11.533 · 3.34 Impact Factor
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    ABSTRACT: Several studies have suggested that interleukin (IL)-8 can serve as a biomarker for discrimination of skin sensitizers from nonsensitizers. We established a stable THP-1-derived IL-8 reporter cell line, THP-G8, which harbors SLO and SLR luciferase genes under the control of IL-8 and glyceraldehyde 3-phosphate dehydrogenase promoters, respectively. After 6 h treatment with chemicals, normalized SLO luciferase activity (nSLO-LA) was calculated by dividing SLO-LA by SLR-LA, and the fold induction of nSLO-LA (FInSLO-LA) was calculated by dividing nSLO-LA of chemically treated cells by that of nontreated cells. The nSLO-LA of THP-G8 cells increased in response to lipopolysaccharide (LPS) and several sensitizers. The FInSLO-LA in THP-G8 cells induced by LPS or sensitizers positively correlated with their induction of IL-8 messenger RNA in THP-1 cells. The nSLO-LA value of THP-G8 cells was significantly increased (FInSLO-LA ≥ 1.4) by 13 of the 15 sensitizers as well as by 5 of the 7 nonsensitizers. Interestingly, pretreatment with N-acetylcysteine suppressed the increase in FInSLO-LA induced by all sensitizers (inhibition index (II) ≤ 0.8) but did not suppress that induced by most of the nonsensitizers. We then evaluated the performance of this assay using values of FInSLO-LA ≥ 1.4 and II ≤ 0.8 in at least two of three independent experiments as the criteria of a sensitizer, which resulted in test accuracies of 82% for the 22 chemicals used and of 88% for the chemicals proposed by European Center for the Validation of Alternative Methods. This newly developed assay is a candidate replacement for animal tests of skin sensitization because of its accuracy, convenience, and high throughput performance.
    Toxicological Sciences 09/2011; 124(2):359-69. DOI:10.1093/toxsci/kfr237 · 4.48 Impact Factor
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    ABSTRACT: Nickel is a potent hapten that induces contact hypersensitivity in human skin. While nickel induces the maturation of dendritic cells via NF-κB and p38 MAPK activation, it also exerts immunosuppressive effects on T cells through an unknown mechanism. To elucidate the molecular mechanisms of its effects on T cells, we examined the effects of NiCl(2) on mRNA expression in human CD3+ T cells stimulated with CD3 and CD28 antibodies. Using a DNA microarray and Gene Ontology, we identified 70 up-regulated (including IL-1β, IL-6 and IL-8) and 61 down-regulated (including IL-2, IL-4, IL-10 and IFN-γ) immune responsive genes in NiCl(2)-treated T cells. The DNA microarray results were verified using real-time PCR and a Bio-Plex(TM) suspension protein array. Suppression of IL-2 and IFN-γ gene transcription by NiCl(2) was also confirmed using Jurkat T cells transfected with IL-2 or IFN-γ luciferase reporter genes. To explore the NiCl(2)-regulated signaling pathway, we examined the binding activity of nuclear proteins to NFAT, AP-1, and NF-κB consensus sequences. NiCl(2) significantly and dose-dependently suppressed NFAT- and AP-1-binding activity, but augmented NF-κB-binding activity. Moreover, NiCl(2) decreased nuclear NFAT expression in stimulated T cells. Using Jurkat T cells stimulated with PMA/ionomycin, we demonstrated that NiCl(2) significantly suppressed stimulation-evoked cytosolic Ca(2+) increases, suggesting that NiCl(2) regulates NFAT signals by acting as a blocker of Ca(2+) release-activated Ca(2+) (CRAC) channels. These data showed that NiCl(2) decreases NFAT and increases NF-κB signaling in T cells. These results shed light on the effects of nickel on the molecular regulation of T cell signaling.
    Toxicology and Applied Pharmacology 05/2011; 254(3):245-55. DOI:10.1016/j.taap.2011.04.017 · 3.63 Impact Factor
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    ABSTRACT: Although hydrogen peroxide (H(2)O(2)) is better known for its cytotoxic effects, in recent years it has been shown to play a crucial role in eukaryotic signal transduction. In respiratory tract epithelial cells, the dual oxidase (DUOX) proteins 1 and 2 has been identified as the cellular source of H(2)O(2). However, the expression of DUOX1 or DUOX2 has not yet been examined in keratinocytes. In this study, using a DNA microarray, we demonstrated that, of the seven NOX/DUOX family members in normal human epidermal keratinocytes (NHEK), IL-4/IL-13 treatment augments the expression of only DUOX1 mRNA. We next confirmed the IL-4/IL-13 induction of DUOX1 in NHEK at the mRNA and protein level using quantitative real-time PCR and Western blotting, respectively. In addition, we demonstrated that this augmented DUOX1 expression was accompanied by increased H(2)O(2) production, which was significantly suppressed both by diphenyleneiodonium, an inhibitor of NADPH oxidase, and by small interfering RNA against DUOX1. Finally, we demonstrated that the increased expression of DUOX1 in IL-4/IL-13-treated NHEK augments STAT6 phosphorylation via oxidative inactivation of protein tyrosine phosphatase 1B. These results revealed a novel role of IL-4/IL-13-induced DUOX1 expression in making a positive feedback loop for IL-4/IL-13 signaling in keratinocytes.
    The Journal of Immunology 03/2011; 186(8):4762-70. DOI:10.4049/jimmunol.1000791 · 5.36 Impact Factor
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    ABSTRACT: Various environmental stimuli, e.g., mechanical stress, osmolarity change, oxidative stress, and microbial products trigger ATP release from cells. It is well known that ATP regulates cell growth, differentiation, terminal differentiation, and cell-to-cell communication in keratinocytes. Moreover, extracellular ATP stimulates the expression and release of IL-6 and modulates the production several chemokines by keratinocytes. To investigate the role of ATP-stimulated keratinocytes in skin inflammation and immune response. We identified genes whose expression is augmented in ATP-stimulated human keratinocytes by DNA microarray. These microarray data were validated by quantitative real-time RT-PCR. Furthermore, we confirmed the observed mRNA change at protein level by ELISA and Western blotting. The statistical analysis of the microarray data revealed that, besides IL-6, the expression of several novel genes such as IL-20, CXCL1-3, and ATF3 was significantly augmented in ATP-stimulated keratinocytes. These data was validated by quantitative real-time RT-PCR. We also confirmed the augmented production of IL-6, IL-20, CXCL1 by ELISA and that of ATF3 by Western blotting. Since both IL-6 and IL-20 that can stimulate STAT3 were produced by the ATP-stimulated keratinocytes, we examined their phosphorylation of STAT3. The study demonstrated biphasic activation of STAT3 after ATP stimulation, which was composed of a first peak at 1-2 h and a second peak at 12-24 h. The latter peak was significantly suppressed by anti-IL-6 antibody. These studies characterized (1) STAT3 activation, (2) chemotaxis for neutrophils via CXCL1-3, and (3) ATF3 activation as possible roles of ATP-stimulated keratinocytes in skin inflammation and immune response.
    Journal of dermatological science 02/2010; 58(2):143-51. DOI:10.1016/j.jdermsci.2010.02.007 · 3.34 Impact Factor

Publication Stats

39 Citations
28.64 Total Impact Points

Institutions

  • 2010–2015
    • Tohoku University
      • • Tohoku Medical Megabank Organization
      • • Department of Dermatology
      Miyagi, Japan
  • 2013
    • Hatano Research Institute, Food and Drug Safety Center
      Hatano, Kanagawa, Japan
  • 2011
    • Pola Chemical Industries, Inc.
      Edo, Tōkyō, Japan