IL-23 from Langerhans cells is required for the development of imiquimod-induced psoriasis-like dermatitis by induction of IL-17A-producing γδ T cells.

Psoriasis is a common chronic inflammatory skin disease that involves dysregulated interplay between immune cells and keratinocytes. Recently, it has been reported that IL-23 induces CCR6+ γδ T cells, which have the pivotal role in psoriasis-like skin inflammation in mice of producing IL-17A and IL-22. Langerhans cells (LCs) are a subset of dendritic cells that reside in the epidermis and regulate immune responses. The role of LCs has been extensively investigated in contact hypersensitivity, but their role in psoriasis remains to be clarified. In this study, we focused on Th17-related factors and assessed the role of LCs and γδ T cells in the development of psoriasis using a mouse psoriasis model triggered by topical application of imiquimod (IMQ). LC depletion by means of diphtheria toxin (DT) in Langerin DT receptor-knocked-in mice suppressed hyperkeratosis, parakeratosis, and ear swelling in the IMQ-treated regions. In addition, LC-depleted mice showed decreased levels of Th17-related cytokines in IMQ-treated skin lesions. Moreover, the IMQ-treated skin of LC-depleted mice showed a decreased number of IL-17A-producing CCR6+ γδ T cells. These results suggest that LCs are required for the development of psoriasis-like lesions induced by IMQ in mice.

Combination of skin-directed therapy and oral etoposide for smoldering adult T-cell leukemia/lymphoma with skin involvement.

Approximately 50% of patients with adult T-cell leukemia/lymphoma (ATLL) have skin involvement, and the smoldering, skin lesion-bearing cases are often treated with various skin-directed therapies, such as phototherapy and radiation therapy. Daily oral administration of etoposide plus prednisolone (EP) is also used for smoldering-type ATLL. However, it remains unclear whether these therapies improve patients' survival. We retrospectively analyzed the prognosis of patients with smoldering, skin lesion-bearing ATLL (n = 62), who were treated, as first therapy, with one skin-directed therapy (n = 29), oral EP alone (n = 14) or a combination of skin-directed therapy and oral EP (n = 19). Multivariate analysis revealed that the hazard ratios (HRs) for the overall survival (OS) and progression-free survival (PFS) with the combination therapy were significantly lower than those with the skin-directed therapy (HR 0.1, p = 0.001; HR 0.2, p = 0.002, respectively). These results suggest that the combination of skin-directed therapy and oral EP improves the clinical outcome of patients with smoldering, skin lesion-bearing ATLL.

[The biological role of UVB-induced cutaneous immunosuppression].

Skin is a large organ which protects our inner body from external stresses. Skin serves not only as a physical barrier but also as an important immune system. Ultraviolet rays B (UVB) activate melanin synthesis by melanocytes in the skin. Melanin, in turn, absorbs UVB and protects the skin from overexposure to UVB. In addition, it is generally known that UVB suppresses immune reaction in the skin. This phenomenon is applied to the treatment of cutaneous diseases such as psoriasis and vitiligo. UVB-induced immunosuppression is mediated by regulatory T cells (Tregs). We and other groups have figured out the mechanism of UVB-induced antigen specific immunosuppression. Here we propose that the role of UVB-mediated immunosuppression is the inhibition of self-destruction against external stresses.

Type of skin eruption is an independent prognostic indicator for adult T-cell leukemia/lymphoma.

Cutaneous involvement is seen in ~ 50% of adult T-cell leukemia/lymphoma (ATLL) patients. We investigated the association between skin eruption type and prognosis in 119 ATLL patients. ATLL eruptions were categorized into patch (6.7%), plaque (26.9%), multipapular (19.3%), nodulotumoral (38.7%), erythrodermic (4.2%), and purpuric (4.2%) types. When the T stage of the tumor-node-metastasis-blood (TNMB) classification of mycosis fungoides/Sézary syndrome was applied to ATLL staging, 16.0% were T1, 17.7% T2, 38.7% T3, and 4.2% T4, and the remaining 23.5% were of the multipapular and purpuric types. For the patch type, the mean survival time (median survival time could not be estimated) was 188.4 months. The median survival times (in months) for the remaining types were as follows: plaque, 114.9; multipapular, 17.3; nodulotumoral, 17.3; erythrodermic, 3.0; and purpuric, 4.4. Kaplan-Meier curves of overall survival showed that the erythrodermic type had the poorest prognosis, followed by the nodulotumoral and multipapular types. The patch and plaque types were associated with better survival rates. Multivariate analysis demonstrated that the hazard ratios of the erythrodermic and nodulotumoral types were significantly higher than that of the patch type, and that the eruption type is an independent prognostic factor for ATLL. The overall survival was worse as the T stage became more advanced: the multipapular type and T2 were comparable, and the purpuric type had a significantly poorer prognosis than T1.

Ectopic extramammary Paget's disease: case report and literature review.

Extramammary Paget's disease that occurs in non-apocrine-bearing regions is referred to as ectopic and has been rarely reported. A 62-year-old man presented with a slowly progressive, asymptomatic light-brown plaque on his back. Histopathological examination revealed the presence of large pale cells with prominent nuclei, which proliferated diffusely and focally in the epidermis. Immuno-histochemically the tumour cells were positive for CK7, GCDFP-15, CEA, and p63. Based on these findings, we diagnosed the tumour as ectopic extramammary Paget's disease. We reviewed the English and Japanese literature and found 29 previously reported cases of ectopic extramammary Paget's disease, including our case, with a predominance of occurrence in the Asian population. The germinative milk line is known to be a possible site where extramammary Paget's disease occurs. Like-wise, some germinative apocrine-differentiating cells might exist on the trunk preferentially in Asians. Attention should be paid to the development of ectopic as well as triple or quadruple EMPD in Asians.

FTY720 regulates bone marrow egress of eosinophils and modulates late-phase skin reaction in mice.

Eosinophilia in the blood and skin is frequently observed in patients with certain inflammatory skin diseases, such as atopic dermatitis. However, the mechanism underlying eosinophil circulation and the role of eosinophils in cutaneous immune responses remain unclear. In repeated hapten application-induced cutaneous responses in BALB/c mice, the administration of FTY720 before the last challenge decreased the number of skin-infiltrating eosinophils and reduced the late-phase reaction. A similar reduction of the late-phase reaction was observed by a sphingosine-1-phosphate G protein-coupled receptor (S1P1)-selective agonist, SEW2871. We monitored numerous alterations of eosinophils in the blood, spleen, bone marrow, and lymph nodes of interleukin-5 transgenic mice, used as an eosinophilia model, following FTY720 administration. The number of circulating eosinophils was significantly decreased after treatment with FTY720, and eosinophils accumulated in the bone marrow. In addition, eosinophils expressed S1P1, S1P3, and S1P4 mRNAs, and their chemotactic response to S1P was abolished by FTY720 as well as by SEW2871. These findings suggest that FTY720 affects the number of eosinophils in both the blood and skin by inhibiting the egress of eosinophils from the bone marrow and thus downmodulating the late-phase reaction.

Ultraviolet light induces Stat3 activation in human keratinocytes and fibroblasts through reactive oxygen species and DNA damage.

Stat3 is activated by the outer stressors, such as ultraviolet (UV) exposure. In this study, we investigated the Stat3 response to UV irradiation in human epidermal keratinocytes and dermal fibroblasts. Results indicated that UVB and UVC differentially activate Stat3 in these cells. The UV-induced Stat3 activation was mediated by both reactive oxygen species (ROS) and DNA damage, and the dominancy of ROS and DNA damage to activate Stat3 depended on the wavelength of UV. By using fibroblasts from a patient with xeroderma pigmentosum A (XP-A) and those transfected with human XPA gene, we found that UVB activates Stat3 via both ROS and DNA damage, while UVC does so mainly via DNA damage. The present data suggest that Stat3 activation in UV-exposed human skin is one of the initial events where DNA damage and ROS are involved.

The mandatory role of IL-10-producing and OX40 ligand-expressing mature Langerhans cells in local UVB-induced immunosuppression.

The mechanism underlying the local UVB-induced immunosuppression is a central issue to be clarified in photoimmunology. There have been reported a considerable number of cells and factors that participate in the sensitization phase-dependent suppression, including Langerhans cells (LCs), regulatory T cells, IL-10, and TNF-alpha. The recent important finding that LC-depleted mice rather exhibit enhanced contact hypersensitivity responses urged us to re-evaluate the role of LCs along with dermal dendritic cells (dDCs) in the mechanism of UVB-induced immunosuppression. We studied the surface expression of OX40 ligand (OX40L) and the intracellular expression of IL-10 in LCs and dDCs from UVB-irradiated (300 mJ/cm(2)) skin of BALB/c mice and those migrating to the regional lymph nodes from UVB-irradiated, hapten-painted mice. In epidermal and dermal cell suspensions prepared from the UVB-irradiated skin, LCs expressed OX40L as well as CD86 and produced IL-10 at a higher level than Langerin(-) dDCs. The UVB-induced immunosuppression was attenuated by the administration of IL-10-neutralizing or OX40L-blocking Abs. In mice whose UVB-irradiated, hapten-painted skin was dissected 1 d after hapten application, the contact hypersensitivity response was restored, because this treatment allowed dDCs but not LCs to migrate to the draining lymph nodes. Moreover, LC-depleted mice by using Langerin-diphtheria toxin receptor-knocked-in mice showed impaired UVB-induced immunosuppression. These results suggest that IL-10-producing and OX40L-expressing LCs in the UVB-exposed skin are mandatory for the induction of Ag-specific regulatory T cells.

Involvement of Wnt signaling in dermal fibroblasts.

Pachydermoperiostosis (PDP) is a rare disease characterized by unique phenotypes of the skin and bone, such as thick skin, implying that it may be caused by dysregulation of mesenchymal cells. The aim of this study is to examine the roles of dermal fibroblasts in the pathogenesis of pachydermia in association with Wnt signaling. The numbers of cultured fibroblasts were compared between healthy donors and PDP patients, and mRNA expression profiles in cultured dermal fibroblasts were examined by DNA microarray analysis and real-time reverse transcription-PCR. DKK1 and beta-catenin protein expressions were also evaluated by immunohistochemistry in the skin. To evaluate the in vivo roles of DKK1 in mice, DKK1 small interfering RNA was injected to the ears. We found that PDP fibroblasts proliferated more than control fibroblasts and that mRNA expression of a Wnt signaling antagonist, DKK1, was much lower in PDP fibroblasts than in normal ones. Consistently, decreased expression of DKK1 in fibroblasts and enhanced expression of beta-catenin were noted in PDP patients. Moreover, recombinant human DKK1 protein decreased the proliferation of dermal fibroblasts. In accord with the above human studies, intradermal injections of DKK1 small interfering RNA into mouse ears increased ear thickness as seen in PDP. Our findings suggest that enhanced Wnt signaling contributes to the development of pachydermia by enhancing dermal fibroblast functions.

Inducible nitric oxide synthase downmodulates contact hypersensitivity by suppressing dendritic cell migration and survival.

Nitric oxide (NO) has several important roles in various physiological settings; one of the NO synthases, inducible NO synthase (iNOS), is induced by external stimulation of the skin. A prototypic example of external stimulation is hapten exposure, which induces the T-cell-mediated immune response known as contact hypersensitivity (CHS). We herein report on cutaneous dendritic cell (DC) function in the presence of an iNOS-specific inhibitor during the sensitization phase of CHS. First, we examined epidermal cell (EC) suspensions using flow cytometry with an iNOS antibody and confirmed that iNOS was expressed in the cytoplasm of Langerhans cells (LCs). We then studied the role of iNOS in CHS, and found that responses to DNFB were enhanced by the addition of an iNOS inhibitor during sensitization. Similarly, the iNOS inhibitor augmented FITC-induced migration of cutaneous DCs, including Langerin(+) LCs and Langerin(-) dermal DCs, to draining lymph nodes. Finally, we showed that iNOS inhibitor enhanced LC survival in vitro. We concluded that NO suppresses migration and survival of cutaneous DCs, resulting in a downmodulation of CHS.

[Seborrheic keratosis on the umbilicus: case report and review of Japanese literature].

A 78-year-old man was seen for a tumor on his umbilicus. Clinically, there was a dark brown nodule with thick scales. The excised tumor showed the acanthotic type of seborrheic keratosis. Six cases of seborrheic keratosis arising on the umbilicus have been reported. All of them were of the histologically hyperkeratotic type. Our case is the first report of an acanthotic type of seborrheic keratosis on the umbilicus. Seborrheic keratosis is one of the common skin tumors, but we hesitated in this diagnosis because of its abnormal location.

Skin application of ketoprofen systemically suppresses contact hypersensitivity by inducing CD4(+) CD25(+) regulatory T cells.

BACKGROUND: Ketoprofen (KP) is a widely used nonsteroidal anti-inflammatory drug that inhibits prostaglandin biosynthesis. We have previously shown that topical KP treatment at the sensitizing site inhibits the development of contact hypersensitivity (CHS) to picryl chloride (PCl). OBJECTIVE: We investigated the mechanism underlying the KP-induced immunosuppression of CHS by application of KP. METHODS: We analyzed the CHS responses to the non-sensitizing site and subsequent sensitization with PCl, and by transfer of the draining lymph node cells (LNCs) from KP-tolerated mice to recipient mice. Changes in the Foxp3 expression of LNCs from KP-phototreated skin were also examined by real-time PCR. RESULTS: Topical application of KP to not only the sensitizing but also non-sensitizing site suppressed CHS response. The immunosuppression was transferred with LNCs from mice treated with PCl plus KP, but not from mice treated oxazolone plus KP. In this transfer study, the CD4(+) CD25(+) subset of LNCs exerted the suppressive effect, while CD25(+) cell-depleted LNCs lost the inhibitory ability. CTLA-4 blocking with a specific antibody, but not IL-10 blocking, abrogated the activity of CD4(+) CD25(+) cells. Moreover, Foxp3 mRNA expression was remarkably increased in LNCs from PCl and KP-treated mice. CONCLUSION: The immunosuppression of CHS by topical application of KP is systemic and haptein-specific. Treg cells play an important role in the suppressive effect by KP.

IL-10-producing Langerhans cells and regulatory T cells are responsible for depressed contact hypersensitivity in grafted skin.

Although skin grafting is a common surgical technique, the immunological state of grafted skin remains unelucidated. An experimental model has shown that the development of murine contact hypersensitivity (CHS) is depressed when mice are sensitized with a hapten through full-thickness grafted skin. We explored the immunological mechanisms underlying this hyposensitization, focusing on the fate of Langerhans cells (LCs). When FITC was applied to grafted skin, FITC-bearing LCs were capable of migrating to the draining lymph nodes. Epidermal cell suspensions isolated from the grafted skin produced a high amount of IL-10 as assessed by real-time PCR. Adoptive transfer of immune lymph node cells from the sensitized mice suppressed the CHS response of recipients in an antigen-specific manner. CD4(+)CD25(+) but not CD4(+)CD25(-) T cells purified from lymph node cells were responsible for this suppression. Finally, we detected high expression of receptor activators of nuclear factor kappa-B ligand (RANKL) in the grafted skin, and found that recombinant RANKL stimulated LCs to produce IL-10. These findings suggest that the hyposensitization of CHS through the grafted skin is not attributable merely to the reduction of LC number but that IL-10-producing LCs exert a downmodulatory effect by inducing regulatory T cells.

Impaired initiation of contact hypersensitivity by FTY720.

FTY720 inhibits lymphocyte emigration from lymphoid organs to peripheral blood by binding one of the sphingosine-1-phosphate (S1P) receptors, S1P(1). We investigated the effects of FTY720 in relation to murine contact hypersensitivity (CHS). CHS was impaired by FTY720 when administered during the sensitization but not the elicitation phase. Consistently, adoptive transfer of immunized lymph node cells from mice treated with FTY720 during the sensitization phase was virtually incapable of inducing CHS response in recipients. FTY720 decreased the number of blood CD44(-)-naive T cells markedly and that of CD44(+) memory T cells modestly. Among memory T cells, the CD62L(-) effector memory subset was more resistant to FTY720 than the CD62L(+) central memory subset. Accordingly, the level of S1P chemotactic response was high in naive T cells, marginal in effector memory T cells, and very low in central memory T cells. Consistently, the S1P(1) mRNA expression level was much lower in memory T cells than in naive T cells. These findings demonstrate that S1P-S1P(1) signaling is essential for recirculation of naive T cells. FTY720 seems to decrease the incidence of interactions between antigen-loaded dendritic cells and circulating naive T-cell clones in the lymph nodes, thereby depressing the sensitization of naive T cells in CHS.

Cutaneous hypersensitivities to hapten are controlled by IFN-gamma-upregulated keratinocyte Th1 chemokines and IFN-gamma-downregulated langerhans cell Th2 chemokines.

There are immediate, late-phase, and delayed-type reactions to exogenous agents. In IFN-gamma-knockout (IFN-gamma(-/-)) and wild-type B6 mice, we examined the response to picryl chloride (PCl) for assessing delayed-type reactions, and the responses to repeatedly challenged FITC for immediate and late-phase reactions. The delayed-type hypersensitivity was depressed in IFN-gamma(-/-) mice, and the immediate and late-phase reactions were enhanced in IFN-gamma(-/-) mice. As skin-infiltrating lymphocytes were scarce at the PCl-challenged site of IFN-gamma(-/-) mice, we investigated chemokine production by keratinocytes and Langerhans cells (LCs). A real-time PCR analysis demonstrated that Th1 chemokines (CXCL9 and CXCL10) and Th2 chemokines (CCL17 and CCL22) were derived mainly from keratinocytes and LCs, respectively. Challenge with PCl or FITC augmented keratinocyte expression of Th1 chemokines in wild-type but not in IFN-gamma(-/-) mice, and Th2 chemokine production by LCs was induced by repeated FITC in IFN-gamma(-/-) mice. Finally, transfer of carboxyfluorescein diacetate succinimidyl ester (CFSE)-labeled draining lymph node cells from hapten-sensitized B6 mice or lymph node cells from sensitized green fluorescent protein (GFP) mice to naive IFN-gamma(-/-) mice revealed less infiltration of CFSE(+) or GFP(+) lymphocytes at the challenged site. Our study suggests that one of the crucial actions of IFN-gamma is upregulation of keratinocyte production of Th1 chemokines and downregulation of LC production of Th2 chemokines.

CXCL12-CXCR4 engagement is required for migration of cutaneous dendritic cells.

CCR7 is regarded as an essential chemokine receptor for cutaneous dendritic cell (DC) migration into the regional lymph nodes. However, complete migratory inhibition cannot be obtained in CCR7-deficient mice, suggesting that there exist other chemokine receptors involved in this process. Initially, we found that CXCR4 was highly expressed on migrated cutaneous DCs and that its ligand, CXCL12, was detected in the LYVE-1(+) lymphatic vessels in the skin. FITC-induced cutaneous DC migration into the draining lymph nodes was impaired by the specific CXCR4 antagonist 4-F-Benzoyl-TN14003. Among FITC(+) cells, Langerin(+) Langerhans cells and Langerin(-) (dermal) dDC subsets were detected as CD11c(high+)CD11b(int+) cells and CD11c(high+)CD11b(high+) plus CD11c(low+)CD11b(int+) cells, respectively, both of which were suppressed by CXCR4 antagonist. Moreover, in vivo contact hypersensitivity response was impaired by CXCR4 antagonist administered during the sensitization phase. The in vitro proliferative response to dinitrobenzene sulfonic acid of sensitized lymph node cells was inhibited by CXCR4 antagonist treatment. These findings demonstrated that CXCL12-CXCR4 engagement on cutaneous DCs plays a crucial role in the initiation of skin immune response by enhancing cutaneous DC migration.