Kan Torii

Langerhans cells are required for UVR-induced immunosuppression

Painting of haptens onto UVR-exposed skin does not result in sensitization but induces regulatory T cells (Treg). This was explained by UVR-mediated depletion of Langerhans cells (LCs). Furthermore, migration of UVR-damaged but still viable LCs into lymph nodes appears to be essential to induce Treg. Accordingly, the steroid mometasone, which kills LCs, inhibited sensitization but did not induce Treg. In Langerin-diphtheria toxin receptor knock-in (DTR) mice, LCs can be depleted by injection of diphtheria toxin (DT). LC-depleted mice could be sensitized though less pronounced than wild-type mice, but sensitization was not suppressed by UVR. Similarly, Treg did not develop. Langerin is not only expressed in LCs but also in some dermal dendritic cells (dDCs). Langerin-positive dDCs repopulate within 10 days after depletion, whereas LCs are still absent. Langerin-DTR mice treated with DT 10 days before UVR and sensitization were still resistant to UVR-induced inhibition of contact hypersensitivity (CHS). Similarly, Treg did not arise. As in this setting only LCs but not Langerin-positive dDCs are absent, LCs appear to be essential for both the suppression of CHS and the induction of Treg by UVR. This supports the concept that LCs are more important for the downregulation than the induction of immune responses in the skin.

Molecular Basis of Tobacco Smoke-Induced Premature Skin Aging

Although it is now widely recognized that tobacco smoke has negative effects on the skin, the molecular mechanisms underlying its skin-aging effects remain uncertain. Epidemiological studies indicate that tobacco smoking is a strong independent predictor of facial wrinkle formation and other aspects of premature skin aging. Recent in vivo studies in humans and mice provided the first direct evidence that tobacco smoke causes premature skin aging, and they have begun to reveal the molecular changes in the skin that occur in response to it. Water-soluble tobacco smoke extract, which predominantly produces oxidative stress when applied topically to cultured skin fibroblasts, impairs collagen biosynthesis. Matrix metalloproteinases, which degrade collagen, are induced dose-dependently by tobacco smoke extract as well as by other constituents that trigger the aryl hydrocarbon receptor (AhR), a ligand-dependent transcription factor that mediates the toxicity of several environmental contaminants, including photoproducts in the body generated by UVB radiation. Tobacco smoke also contains many non-water-soluble constituents that activate the AhR pathway. Our most recent studies using hexane-soluble tobacco extract indicate that activation of the AhR pathway may play a role in the premature skin-aging effects of tobacco smoke exposure.Journal of Investigative Dermatology Symposium Proceedings (2009) 14, 53-55; doi:10.1038/jidsymp.2009.13.

Photo(chemo)therapy Reduces Circulating Th17 Cells and Restores Circulating Regulatory T Cells in Psoriasis

Background Photo(chemo)therapy is widely used to treat psoriasis, the pathogenesis of which might be caused by an imbalance of Th17 cells/regulatory T cells (Treg). In the present study, we evaluated the effects of photo(chemo)therapy on the Th17/Treg balance and Treg function. Methods Peripheral blood was obtained from psoriasis patients treated with bath-psoralen ultraviolet A (UVA, n = 50) or narrowband ultraviolet B (UVB, n = 18), and age-matched healthy volunteers (n = 20). CD3+CD4+IL-17A+ or CD4+CD25+Foxp3+cells were analyzed to estimate Th17 or Treg number by fluorescence–activated cell sorting. Moreover, CD4+ CD25− T cells from patients treated with PUVA(n = 14) were incubated in CFSE and activated with or without CD4+ CD25+T cells, and the suppressive function of CD4+ CD25+T cells were analyzed. Results Photo(chemo)therapy significantly reduced Th17 levels from 5.66±3.15% to 2.96±2.89% in patients with increased Th17 (Th17/CD4>3.01% [mean+SD of controls]). In contrast, photo(chemo)therapy significantly increased Treg levels from 2.77±0.75 to 3.40±1.88% in patients with less than 4.07% Treg level, defined as the mean of controls. Furthermore, while Treg suppressed the CD4+CD25− T cell proliferation to a greater extent in controls (Treg Functional Ratio 94.4±4.28%) than in patients (70.3±25.1%), PUVA significantly increased Treg Functional Ratio to 88.1±6.47%. Th17 levels in severe patients (>30 PASI) were significantly higher as compared to controls. Th17 levels that were left after treatment in the patients not achieving PASI 50 (3.78±4.18%) were significantly higher than those in the patients achieving PASI 75 (1.83±1.87%). Treg levels in patients achieving PASI 90 (4.89±1.70%) were significantly higher than those in the patients not achieving PASI 90 (3.90±1.66%). Treg levels prior to treatment with Th17 high decreased group (5.16±2.20%) was significantly higher than that with Th17 high increased group (3.33±1.39%). Conclusion These findings indicate that Treg is dysfunctional in psoriasis patients, and photochemotherapy restores those dysfunctional Treg. Photo(chemo)therapy resolved the Th17/Treg imbalance in patients with psoriasis.

Effect and mechanism of a new photodynamic therapy with glycoconjugated fullerene.

When irradiated, fullerene efficiently generates reactive oxygen species (ROS) and is an attractive photosensitizer for photodynamic therapy (PDT). Ideally, photosensitizers for PDT should be water‐soluble and tumor‐specific. Because cancer cells endocytose glucose more effectively than normal cells, the characteristics of fullerene as a photosensitizer were improved by combining it with glucose. The cytotoxicity of PDT was studied in several cancer cell lines cultured with C60‐(Glc)1 (d‐glucose residue pendant fullerene) and C60‐(6Glc)1 (a maltohexaose residue pendant fullerene) subsequently irradiated with UVA1. PDT alone induced significant cytotoxicity. In contrast, PDT with the glycoconjugated fullerene exhibited no significant cytotoxicity against normal fibroblasts, indicating that PDT with these compounds targeted cancer cells. To investigate whether the effects of PDT with glycoconjugated fullerene were because of the generation of singlet oxygen (1O2), NaN3 was added to cancer cells during irradiation. NaN3 extensively blocked PDT‐induced apoptosis, suggesting that PDT‐induced cell death was a result of the generation of 1O2. Finally, to investigate the effect of PDT in vivo, melanoma‐bearing mice were injected intratumorally with C60‐(Glc)1 and irradiated with UVA1. PDT with C60‐(Glc)1 suppressed tumor growth. These findings indicate that PDT with glycoconjugated fullerene exhibits tumor‐specific cytotoxicity both in vivo and in vitro via the induction of 1O2.

Tobacco smoke is related to Th17 generation with clinical implications for psoriasis patients

Abstract:  Environmental factors contribute to the increased prevalence of autoimmune diseases via T helper type‐17 cell (Th17) activation. Tobacco smoking increases the risk of psoriasis, but the mechanisms are not clear. We evaluated the percentage of circulating Th17 among CD3+ cells in peripheral blood mononuclear cells (PBMC) obtained from 27 healthy volunteers (2.58 ± 0.80%), 33 smoker (3.55 ± 1.33%) and 21 non‐smoker (3.10 ± 1.14%) patients with psoriasis to elucidate the relation between smoking and psoriasis. More smokers (19/33) than non‐smokers (6/21) had high Th17 levels (Th17/CD3 > 3.38%, mean + 1 SD of healthy volunteers). Tobacco smoke extract (TSE, 7 μl/ml) induced Th17 generation from central memory T cells in vitro. TSE increased interleukin 17 and 22 expression. These findings demonstrate the relation between tobacco smoke and IL‐17 and IL‐22, which exacerbate psoriasis.

Role of the aryl hydrocarbon receptor in tobacco smoke extract–induced matrix metalloproteinase‐1 expression

Findings from large epidemiologic studies indicate that there is a link between smoking and extrinsic skin ageing. We previously reported that matrix metalloproteinases (MMPs) mediate connective tissue damage in skin exposed to tobacco smoke extracts. Tobacco smoke contains more than 3800 constituents, including numerous water‐insoluble polycyclic aromatic hydrocarbons (PAHs) that trigger aryl hydrocarbon receptor (AhR) signalling pathways. To analyse the molecular mechanisms involved in tobacco smoke–induced skin ageing, we exposed primary human fibroblasts and keratinocytes to tobacco smoke extracts. Hexane‐ and water‐soluble tobacco smoke extracts significantly induced MMP‐1 mRNA in both human cultured fibroblasts and keratinocytes in a dose‐dependent manner. To clarify the involvement of the AhR pathway, we used a stable AhR‐knockdown HaCaT cell line. AhR knockdown abolished the increased transcription of the AhR‐dependent genes CYP1A1/CYP1B1 and MMP‐1 induced by either of the tobacco smoke extracts. Furthermore, the tobacco smoke extracts induced 7‐ethoxyresorufin‐O‐deethylase activity, which was almost completely abolished by AhR knockdown. Likewise, treating fibroblasts with AhR pathway inhibitors, that is, the flavonoids 3‐methoxy‐4‐nitroflavone and α‐naphthoflavone, blocked the expression of CYP1B1 and MMP‐1. These findings suggest that the tobacco smoke extracts induce MMP‐1 expression in human fibroblasts and keratinocytes via activation of the AhR pathway. Thus, the AhR pathway may be pathogenetically involved in extrinsic skin ageing.

Phototherapy reduces serum resistin levels in psoriasis patients

This study investigated phototherapy‐induced changes in certain adipokine levels in patients with psoriasis. Patients with psoriasis (n=36) were recruited and body mass index (BMI) and disease severity (Psoriasis Area and Severity Index) were recorded. Serum resistin and leptin levels before and after bath‐psoralen and ultraviolet (UV) A or narrow‐band UVB therapy were examined by enzyme‐linked immunosorbent assay. Serum leptin levels correlated positively with BMI. Phototherapy induced no remarkable change in the leptin levels, but significantly decreased serum resistin levels from 9.02±8.83 to 4.86±3.30 ng/ml. Serum resistin levels might be involved in insulin resistance and inflammation, and correlate with disease severity in patients with psoriasis. The reduction in serum resistin induced by phototherapy might be related to the clinical efficacy of this treatment for psoriasis.

The Herbal Medicine Compound Falcarindiol from Notopterygii Rhizoma Suppresses Dendritic Cell Maturation

Dendritic cells (DCs) are important for regulating the immune response. We report an herbal medicine compound called falcarindiol that affects DC function. Ethanol extracts of 99 crude drugs that are the main components of 210 traditional Japanese medicines (Kampo medicine) approved by the Ministry of Health, Labor and Welfare in Japan were prepared and screened using the murine epidermal-derived Langerhans cell line XS106. Notopterygii Rhizoma strongly suppressed major histocompatibility complex (MHC) class II expression in XS106 cells. Activity-guided fractionation led to the isolation and identification of falcarindiol as a principal active compound in Notopterygii Rhizoma. Falcarindiol (1–5 μM) dose-dependently suppressed MHC II expression in XS106 cells. Fresh-isolated bone marrow-derived DCs were examined for the production of MHC II, CD80, CD86, interleukin (IL)-12p70, and IL-10. Treatment of bone marrow-derived DCs with 5 μM falcarindiol significantly inhibited lipopolysaccharide-induced phenotype activation and cytokine secretion and inhibited MHC II expression by CD40 ligation, but not phorbol 12-myristate 13-acetate + ionomycin or IL-12. Falcarindiol inhibited DC maturation by blocking the canonical pathway of nuclear factor-κB and phosphorylated p38. Topical application of 0.002 and 0.01% falcarindiol before sensitization dose-dependently suppressed delayed-type hypersensitivity to ovalbumin (p < 0.01). Falcarindiol induces immunosuppressive effects in vitro and in vivo and might be a novel therapy for autoimmune or allergic diseases.

Efficacy of excimer light therapy (308 nm) for palmoplantar pustulosis with the induction of circulating regulatory T cells

Abstract:  In this open‐label study, we investigated the efficacy of excimer light (308 nm) with a filter to cut off wavelengths below 297 nm for the treatment of palmoplantar pustulosis (PPP). Twenty patients with PPP were recruited and treated once a week for a total of 30 sessions. Patient response was assessed every 10 sessions based on the Palmoplantar Pustulosis Area and Severity Index (PPPASI) score. Levels of Th17 cells and regulatory T cells (Treg) in the peripheral blood in patients with PPP were also evaluated. Mean PPPASI score was 19.5 at baseline, 13.2 at 10 treatments, 10.9 at 20 treatments and 9.5 at 30 treatments. Th17 levels after excimer therapy were not significantly different from those at baseline. In contrast, Treg levels after excimer therapy were significantly higher than those at baseline.

NB-UVB irradiation increases filaggrin expression in a three-dimensional human skin model

Ultraviolet (UV) B irradiation affects the immune system and is ed for therapeutic purposes. The mechanisms underlying the fects of UVB phototherapy are thought to include the induction of NB-UVB, and broadband UVB (BB-UVB); both Toshiba Medical Supply, Tochigi, Japan) to irradiate the cells. At 24 h after UVB irradiation, total RNA was extracted using an RNeasy mini kit (Qiagen, Hilden, Germany), and examined FLG, IVL and LOR mRNA expression. At 72 h after UVB irradiation, the skin model was fixed in 20% buffered formalin and embedded in paraffin. Tissue sections were deparaffinized and rehydrated by sequential immersion in xylene followed by graded descending co in m bo an PB tis co w re co se