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The skin is the outermost layer of the body and is exposed to many environmental stimuli, which cause various inflammatory immune responses in the skin. Among them, fungi are common microorganisms that colonize the skin and cause cutaneous fungal diseases such as candidiasis and dermatophytosis. The skin exerts inflammatory responses to eliminate these fungi through the cooperation of skin-component immune cells. IL-17 producing cells are representative immune cells that play a vital role in anti-fungal action in the skin by producing antimicrobial peptides and facilitating neutrophil infiltration. However, the actual impact of IL-17-producing cells in cutaneous fungal infections remains unclear. In this review, we focused on the role of IL-17-producing cells in a series of cutaneous fungal infections, the characteristics of skin infectious fungi, and the recognition of cell components that drive cutaneous immune cells.

Background: Atopic dermatitis (AD) is a common and chronic inflammatory skin disease of type 2 immunity. Keratinocyte-derived cytokines, including thymic stromal lymphopoietin (TSLP) and IL-33, are considered to induce the development of AD. Production of prostanoids, a family of lipid mediators, is increased in AD lesions. However, their physiologic functions remain to be clarified., Objectives: We sought to elucidate the functions of prostanoids in the development of AD., Methods: The roles of prostanoids were investigated in a mouse model of AD induced by repeated application of hapten and PAM212, a keratinocyte cell line., Results: Application of indomethacin, which blocks prostanoid synthesis, leads to enhanced TSLP and IL-33 production in the skin, increased serum IgE levels, and exacerbation of skin inflammation in this AD model. The skin inflammation was attenuated in TSLP receptor-deficient mice but not in IL-33-deficient mice, and the indomethacin-enhanced type 2 immune responses were abolished in TSLP receptor-deficient mice. Indomethacin increased protease-activated receptor 2-mediated TSLP production in keratinocytes in vitro, and prostaglandin E 2 reversed the increase in TSLP levels through its receptor, the prostaglandin E 2 receptor (EP2), by downregulating surface expression of protease-activated receptor 2. Administration of an EP2 agonist canceled indomethacin-enhanced TSLP production and type 2 immune responses in the skin, whereas an EP2 antagonist caused an enhancement of TSLP production and type 2 immune responses in the skin., Conclusion: Prostaglandin E 2 -EP2 signaling negatively regulates murine AD-like skin inflammation by suppressing TSLP expression., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

The anti-inflammatory effect of omega 3 polyunsaturated fatty acids has been confirmed in various inflammatory disease models. Maresin-1 (MaR1) is a lipid mediator derived from the omega-3 fatty acid docosahexaenoic acid (DHA) that has displayed strong anti-inflammatory effects in various inflammatory disease models. However, the effect of topical MaR1 on cutaneous inflammation remains unclear. Therefore, we initially examined the anti-inflammatory effects of topical Maresin-1 using an imiquimod (IMQ)-induced psoriasis-like mouse model of inflammation. Topical MaR1 reduced the ear swelling response as seen in histological findings. RT-PCR and flow cytometry analyses revealed MaR1 had no inhibitory effect on IL-23, but MaR1 suppressed IL-17A production by γδTCR mid+ and CD4 + cells in the skin. These inhibitory effects were also observed in a subcutaneous IL-23-injected psoriasis model. MaR1 downmodulated IL-23 receptor (IL-23R) expression by suppressing retinoic acid-related orphan receptor γt (RORγt) expression and internalization in a clathrin-dependent manner in γδTCR mid+ and CD4 + cells. These results lead to assumptions that topical MaR1 may be a new therapeutic agent for psoriasis and other IL-17-mediated cutaneous inflammatory diseases.

Most skin cancers develop as the result of UV light-induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations. Furthermore, genetic deletion of Aicda reduced tumor incidence in a murine model of chemical-induced skin carcinogenesis. AID was expressed in human primary keratinocytes in an inflammatory stimulus-dependent manner and was detectable in human skin cancers. Together, the results of this study indicate that inflammation-induced AID expression promotes skin cancer development independently of UV damage and suggest AID as a potential target for skin cancer therapeutics.

Resolvin E1 (RvE1) is a lipid mediator derived from ω3 polyunsaturated fatty acids that exerts potent antiinflammatory roles in several murine models. The antiinflammatory mechanism of RvE1 in acquired immune responses has been attributed to attenuation of cytokine production by dendritic cells (DCs). In this study, we newly investigated the effect of RvE1 on DC motility using two-photon microscopy in a contact hypersensitivity (CHS) model and found that RvE1 impaired DC motility in the skin. In addition, RvE1 attenuated T cell priming in the draining lymph nodes and effector T cell activation in the skin, which led to the reduced skin inflammation in CHS. In contrast, leukotriene B4 (LTB4) induced actin filament reorganization in DCs and increased DC motility by activating Cdc42 and Rac1 via BLT1, which was abrogated by RvE1. Collectively, our results suggest that RvE1 attenuates cutaneous acquired immune responses by inhibiting cutaneous DC motility, possibly through LTB4-BLT1 signaling blockade., (© 2015 Sawada et al.)

Background: Dopamine transduces signals via five subtypes of G protein-coupled receptors. Among these subtypes, the D1 and D5 receptors belong to the D1-like group. Although dopamine is known to mediate immune responses, its involvement in cutaneous immunity remains unclear., Objective: The aim of this study is to determine the role of dopamine and its D1-like receptors in cutaneous immune responses., Methods: By using the D1-like receptor antagonist SCH 23390, we examined the role of D1-like receptors in murine models of Th1-type contact hypersensitivity and Th2-type atopic dermatitis in vivo, and in mast cells and Th2 cell differentiation in vitro., Results: Administration of SCH 23390 did not affect Th1-type contact hypersensitivity but suppressed the immediate-type reaction (ITR) and the late phase reaction (LPR) in the atopic dermatitis model. In addition, SCH 23390-treated mice showed higher IFN-γ and lower IL-4 mRNA levels in the ear skin of challenged mice than did non-treated mice as analyzed by real-time RT PCR. Consistently, the passive cutaneous anaphylaxis reaction was significantly reduced in SCH 23390-treated mice. Moreover, dopamine enhanced mast cell degranulation and Th2 cell differentiation, and both activities were abrogated by SCH 23390., Conclusion: These findings suggest that the D1-like receptors mediate immediate and late phase skin reactions by promoting Th2 induction and mast cell degranulation., (Copyright © 2013 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

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.

Background: Atopic dermatitis (AD) can be classified into the major extrinsic type with high serum IgE levels and impaired barrier, and the minor intrinsic type with normal IgE levels and unimpaired barrier., Objective: To characterize the intrinsic type of Japanese AD patients in the T helper cell polarization in relation to the barrier condition., Methods: Enrolled in this study were 21 AD patients with IgE<200kU/L (IgE-low group; 82.5±59.6kU/L) having unimpaired barrier, and 48 AD patients with IgE>500kU/L (IgE-high group; 8.050±10.400kU/L). We investigated filaggrin gene (FLG) mutations evaluated in the eight loci common to Japanese patients, circulating Th1, Th2 and Th17 cells by intracellular cytokine staining and flow cytometry, and blood levels of CCL17/TARC, IL-18, and substance P by ELISA., Results: The incidence of FLG mutations was significantly lower in the IgE-low group (10.5%) than the IgE-high group (44.4%) (normal individuals, 3.7%). The percentage of IFN-γ-producing Th1, but not Th2 or Th17, was significantly higher in the IgE-low than IgE-high group. Accordingly, Th2-attracting chemokine CCL17/TARC, was significantly lower in the IgE-low than the IgE-high group. There were no differences between them in serum IL-18 levels, or the plasma substance P levels or its correlation with pruritus., Conclusion: The IgE-low group differed from the IgE-high group in that it had much less FLG mutations, increased frequency of Th1 cells, and lower levels of CCL17. In the intrinsic type, non-protein antigens capable of penetrating the unimpaired barrier may induce a Th1 eczematous response., (Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

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.

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.

Epithelial-mesenchymal transition (EMT) plays important roles not only in the morphogenesis but also in wound repair, tissue fibrosis and cancer progression. Recently, regulatory mechanism of this process has been elaborately elucidated. EMT can be a new therapeutic target for treating skin ulcer, fibrosing alopecia, and malignant cutaneous cancers, including squamous cell carcinoma and melanoma., (Copyright © 2010 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.)

Benign lymphangioendothelioma (BL) represents a very rare lymphatic vascular proliferation. Our aim is to be aware that owing to its characteristic features, pathologists can easily misinterpret it as cutaneous low-grade angiosarcoma when examining only small specimens. In the present case, multiple small and yellowish to reddish soft nodules were noticed in the edematous left arm of a 54-year-old Japanese female 4 years after the radical mastectomy with axillary lymph nodes dissection and following radiotherapy to the chest for the left breast carcinoma. The biopsy specimen showed an ill-defined lesion composed of a proliferation of irregular and sometimes anastomosing vascular structures in the dermis, lined by endothelial cells having mildly hyperchromatic and pleomorphic nuclei, but no mitotic figures. As the lesion grew within deeper dermis, these proliferating vessels dissected dermal collagenous bands, occasionally arranged in low-papillary projections and/or characteristic hobnail cytomorphology. We first interpreted it as low-grade angiosarcoma following chronic lymphedema due to the operation, i.e., the so-called Stewart-Treves syndrome. Although additional treatments were performed for 7 years, she had neither local invasion nor metastases of these tumors, respectively, and was alive and well. Retrospective immunohistochemical findings demonstrated that these mildly atypical endothelial cells were strongly positive for lymphatic vessel endothelial hyaluronan receptor (LYVE)-1 as well, and MIB-1 labeling index was less than 1%. Therefore, we finally made a diagnosis of BL of the skin. MIB-1 labeling index might be useful and adjunctive aids for reaching the correct diagnosis of cutaneous BL, especially in case of small or inadequate specimens. [ABSTRACT FROM AUTHOR]

Cell adhesion ability is one of the components to establish cell organization and shows a great contribution to human body construction consisting of various types of cells mixture to orchestrate tissue specific function. The cell adhesion molecule 1 (CADM1) is a molecule of cell adhesion with multiple functions and has been identified as a tumor suppressor gene. CADM1 has multifunctions on the pathogenesis of malignancies, and other normal cells such as immune cells. However, little is known about the function of CADM1 on cutaneous cells and cutaneous malignancies. CADM1 plays an important role in connecting cells with each other, contacting cells to deliver their signal, and acting as a scaffolding molecule for other immune cells to develop their immune responses. A limited number of studies reveal the contribution of CADM1 on the development of cutaneous malignancies. Solid cutaneous malignancies, such as cutaneous squamous cell carcinoma and malignant melanoma, reduce their CADM1 expression to promote the invasion and metastasis of the tumor. On the contrary to these cutaneous solid tumors except for Merkel cell carcinoma, cutaneous lymphomas, such as adult-T cell leukemia/lymphoma, mycosis fungoides, and Sézary syndrome, increase their CADM1 expression for the development of tumor environment. Based on the role of CADM1 in the etiology of tumor development, the theory of CADM1 contribution will desirably be applied to skin tumors according to other organ malignancies, however, the characteristics of skin as a multicomponent peripheral organ should be kept in mind to conclude their prognoses. [ABSTRACT FROM AUTHOR]

Presents a clinical case of occupational hand dermatitis from acrylic monomer in paint. Presenting signs and symptoms; Results of diagnostic examinations; Therapeutic options.

Presents a clinical case of airborne photocontact dermatitis due to the pesticides maneb and fenitrothion. Presenting signs and symptoms; Results of diagnostic examinations; Clinical course.

Presents a clinical case of nickel skin allergy in a trumpet player. Presenting signs and symptoms; Results of diagnostic examinations; Preventive measures undertaken.

Most skin cancers develop as the result of UV light-induced DNA damage; however, a substantial number of cases appear to occur independently of UV damage. A causal link between UV-independent skin cancers and chronic inflammation has been suspected, although the precise mechanism underlying this association is unclear. Here, we have proposed that activation-induced cytidine deaminase (AID, encoded by AICDA) links chronic inflammation and skin cancer. We demonstrated that Tg mice expressing AID in the skin spontaneously developed skin squamous cell carcinoma with Hras and Trp53 mutations. Furthermore, genetic deletion of Aicda reduced tumor incidence in a murine model of chemical-induced skin carcinogenesis. AID was expressed in human primary keratinocytes in an inflammatory stimulus-dependent manner and was detectable in human skin cancers. Together, the results of this study indicate that inflammation-induced AID expression promotes skin cancer development independently of UV damage and suggest AID as a potential target for skin cancer therapeutics. [ABSTRACT FROM AUTHOR]