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Background: Henoch-Schönlein purpura (HSP) is a multisystem disease believed to be a consequence of the entrapment of circulating IgA-containing immune complexes in blood vessel walls throughout the skin, kidneys, and gastrointestinal tract. The skin manifestations are characterized by nonthrombocytopenic palpable purpura over the lower extremities. Objective: We assessed adult patients with HSP who had nonthrombocytopenic palpable purpura on the extensor surfaces of their lower limbs, and had no associated connective tissue disease. Patient medical records, including clinical presentation, laboratory data, and direct immunofluorescence (DIF) reports, were reviewed retrospectively. Methods: We reviewed the records of 25 adult patients with HSP who presented at our department, between 2006 and 2008, with an initial cutaneous manifestation of palpable purpura on their lower extremities. Adult HSP was defined in all cases as documented leukocytoclastic vasculitis according to a skin biopsy specimen, with histopathologic evidence of IgA deposition by DIF. Statistical analyses were performed using a χ2 test to compare prevalence among each clinical manifestation. Results: There was a significant correlation between IgM deposition by DIF and renal involvement (χ2 = 5.23, P = .022). IgM deposition and complement 3 deposition by DIF showed a close relationship (χ2 = 5.11, P = .024). There was a significant positive correlation between serum IgA and C-reactive protein levels (Spearman''s rank correlation coefficient = 0.35, P = .044). Limitations: These findings should be validated in larger studies. Renal biopsies were not done to confirm the presence of nephritis. Conclusions: This study suggests that IgM deposition in palpable purpura based on DIF provides an indicator of nephritis in adult patients with HSP. We believe that IgM deposition could be related to the pathogenic factors that trigger the development of renal involvement. [Copyright &y& Elsevier]

Background: Cutaneous polyarteritis nodosa (CPN) is an uncommon disorder that can be difficult to manage effectively. We have previously suggested that CPN might be associated with the presence of anti-phosphatidylserine-prothrombin complex (anti-PS/PT) antibodies, members of the antiphospholipid antibody family. Objective: To evaluate clinical manifestations and effective treatments of CPN. Methods: We conducted a retrospective analysis of three patients with CPN who responded to warfarin therapy. IgG and IgM anti-PS/PT antibodies were measured with a specific enzyme-linked immunosorbent assay. Results: There was a dramatic improvement in our three CPN patients following warfarin therapy adjusted to a target international normalized ratio (INR) of about 3.0. Active disease progression was halted by sustained warfarin therapy during which the patients experienced resolution of their skin manifestations. Limitations: A small number of cases were studied and the study design was retrospective. Conclusion: We propose that warfarin therapy at a target INR of roughly 3.0 could be effective for treating patients with CPN. We further believe that treatment with warfarin led to the effective attenuation of anti-PS/PT antibodies related to prothrombin, and improved the symptoms in our CPN patients. [ABSTRACT FROM AUTHOR]

Granuloma annulare is characterized by noncaseating dermal granulomas with connective tissue changes. A relationship with hematologic and solid malignancies has been suggested in some cases. We describe a 70-year-old man who had erythematous annular plaques on his elbows, upper extremities, and wrists for a period of 3 months. Histologic examination revealed epithelioid cell granulomas associated with dense atypical lymphocytes in the dermis. Immunohistochemical staining of skin specimens showed a prominent infiltration of CD3+, CD4+, CD5+, and CD25+ cells. Human T-cell leukemia virus type I proviral DNA was detected in the blood and cerebrospinal fluid by Southern blot analysis and polymerase chain reaction assay. The patient was given the diagnosis of adult T-cell leukemia/lymphoma based on the initial cutaneous manifestations. His condition progressed rapidly and led to his death. The granuloma annulare–like skin lesions in our patient could be considered as a peculiar immunologic hypersensitivity reaction of the host against the tumor cells or persistent human T-cell leukemia virus type I viral antigens. Dermatologists should be aware that this skin condition may be an initial manifestation of adult T-cell leukemia/lymphoma. [Copyright &y& Elsevier]

Drug-induced hypersensitivity syndrome (DIHS), also known as drug reaction with eosinophilia and systemic symptoms (DRESS), is a severe multiple-organ condition caused by drug treatment. The current report describes a Japanese boy who underwent aspirin treatment for Kawasaki disease, and who subsequently presented with the manifestations of DIHS/DRESS syndrome. He had been treated with a single high dose of intravenous immunoglobulin and aspirin orally for Kawasaki disease. One month after the onset of Kawasaki disease, he developed a generalized maculopapular eruption, high-grade fever, leukocytosis with eosinophilia, and an increased number of atypical lymphocytes, severe liver dysfunction, lymphadenopathy, and prominent increases in antihuman herpesvirus-6 immunoglobulin G titer. The activity of 2′,5′-oligoadenylate synthetase was elevated at the onset stage. Hypersensitivity to aspirin was confirmed by skin patch test and by lymphocyte stimulation test. Based on these findings, the patient was diagnosed with DIHS/DRESS caused by aspirin. To our knowledge, there have been no previous reports of aspirin-induced hypersensitivity syndrome subsequent to Kawasaki disease. The activity of 2′,5′-oligoadenylate synthetase might be useful as a diagnostic marker of DIHS/DRESS syndrome and for exploring its pathogenesis. [Copyright &y& Elsevier]

Extramedullary hematopoiesis (EMH) is a relatively rare, but well-documented, manifestation of chronic myeloproliferative disorders. Microscopically, foci of EMH consist of erythroid and myeloid precursors intermixed with megakaryocytes. It typically occurs in the spleen and liver, but very occasionally manifests as cutaneous EMH. We report a 76-year-old Japanese man with cutaneous EMH arising from myelodysplastic syndrome associated with myelofibrosis. His cutaneous manifestations showed multiple skin-colored firm nodules over the head, trunk, and extremities. We detected high plasma levels of transforming growth factor (TGF)-β1 in our patient. Immunohistochemical analysis of the skin biopsy sample revealed TGF-β1 overexpression in immature hematopoietic cells and dermal fibroblasts within the cutaneous EMH mass of the dermis. These findings suggest that TGF-β could play some role in the onset of cutaneous EMH. Five months after his first visit to our dermatologic clinic, the patient developed bone-marrow failure and died. Based on our observations, accelerated malignancy in the bone marrow should be considered in any patient with cutaneous EMH. It is presumed that TGF-β released from hematopoietic cells within the cutaneous EMH play a critical role in the activation of hematologic malignancy. [Copyright &y& Elsevier]

Background: Microscopic polyangiitis (MPA) is a systemic antineutrophil cytoplasmic autoantibody–associated vasculitis associated with necrotizing and crescentic glomerulonephritis and pulmonary capillaritis. MPA generally has a rapidly progressive clinical course, but there have been recent reports of slowly progressive cases. Objective: To evaluate the typical cutaneous findings of MPA, we recorded the clinical and histopathologic features of the cutaneous manifestations. Methods: Eight patients with MPA, who had presented with cutaneous manifestations between 2001 and 2005 in our department, were retrospectively reviewed. They had necrotizing vasculitis in their cutaneous lesions as confirmed by skin biopsy specimens. Patients with other known connective tissue diseases were not included in the study. Results: All 8 patients with MPA presented cutaneously with erythematous macules on their extremities. Livedo reticularis (5/8, 68%) was also observed. Six of the 8 patients with MPA were given the diagnosis within 3 months of their initial manifestation. In skin biopsy specimens, necrotizing vasculitis was noted in the reticular dermis to the subcutaneous fat. In contrast, the other two patients with MPA were given the diagnosis about 10 years after their initial manifestation. Histopathologic findings demonstrated necrotizing vasculitis with moderate neutrophilic infiltrations in the papillary to middle dermis in the latter two patients. Serum myeloperoxidase-antineutrophil cytoplasmic autoantibody levels were only moderlately elevated in the latter two patients and they were given the diagnosis of slowly progressive MPA. Histopathologically, palisading granulomas were present on the elbow of one of them. Limitations: The study was based on histopathological analysis in a limited number of patients due to the rareness of the investigated disease. Conclusions: There appears to be a correlation between a slowly progressive clinical course of MPA and the depth of dermal involvement and the severity of neutrophilic infiltration in biopsy specimens. Based on these results, we believe that these characteristic patterns may help clinicians establish an earlier diagnosis of possible MPA with positive antineutrophil cytoplasmic autoantibody titers. [Copyright &y& Elsevier]

The effects of 1,25-dihydroxyvitamin D3 on the differentiation of immature melanocyte precursors were studied. The NCC-/melb4 cell line is an immature melanocyte cell line established from mouse neural crest cells. 1,25-dihydroxyvitamin D3 inhibited the growth of NCC-/melb4 cells at concentrations higher than 10-8 m. That growth inhibition was accompanied by the induction of tyrosinase and a change in L-3,4-dihydroxyphenylalanine reactivity from negative to positive. Electron microscopy demonstrated that melanosomes were in more advanced stages after 1,25-dihydroxyvitamin D3 treatment. In primary cultures of murine neural crest cells, L-3,4-dihydroxyphenylalanine-positive cells were increased after 1,25-dihydroxyvitamin D3 treatment. These findings indicate that 1,25-dihydroxyvitamin D3 stimulates the differentiation of immature melanocyte precursors. Moreover, immunostaining and reverse transcription–polymerase chain reaction analysis revealed that endothelin B receptor expression was induced in NCC-/melb4 cells following treatment with 1,25-dihydroxyvitamin D3 . The induction of endothelin B receptor by 1,25-dihydroxyvitamin D3 was also demonstrated in neural crest cell primary cultures, but not in mature melanocytes. The expression of microphthalmia-associated transcription factor was induced in NCC-/melb4 cells treated with 1,25-dihydroxyvitamin D3 and endothelin 3, but not by 1,25-dihydroxyvitamin D3 alone, suggesting that endothelin 3 may stimulate the expression of the microphthalmia-associated transcription factor gene after binding to the endothelin B receptor induced by 1,25-dihydroxyvitamin D3 . These findings suggest a regulatory role for vitamin D3 in melanocyte development and melanogenesis, and may also explain the working mechanism of vitamin D3 in the treatment of vitiligo. [ABSTRACT FROM AUTHOR]

Recent studies have shown increased T-helper (Th) 2 cytokine expression and decreased IFN-γ expression in peripheral blood from patients with atopic dermatitis (AD). In the present study, we examined the cytokine expression in peripheral blood mononuclear cells in patients with AD and tested how the cytokine profile correlated with the patients’ age, severity and laboratory findings. Peripheral blood mononuclear cells obtained from 20 patients with AD were stimulated with phorbol 12-myristate 13-acetate and ionomycin, and were examined for the frequencies of CD4+ cells expressing IL-4, IL-13 and IFN-γ at the single cell level using intracellular cytokine staining and flow cytometry. There was a significant positive correlation between IL-4 and IL-13 expression in CD4+ cells. Expression levels of both IL-4 and IL-13 in CD4+ cells were significantly correlated with peripheral blood eosinophilia. These findings suggest that CD4+ cells producing IL-4 and IL-13 play important roles in the pathogenesis of AD. IFN-γ expression did not correlate with either IL-4 or IL-13 expression, or with blood eosinophilia. We also measured serum levels of IL-13 in 144 patients with AD using enzyme-linked immunosorbent assay, and found 16 patients with detectable levels of serum IL-13. IL-13+ patients had significantly higher serum IgE levels than IL-13− patients, suggesting a direct association between serum levels of IL-13 and IgE. It was also shown that the IL-13+ group was significantly younger in age than the IL-13− group, although the implication of this finding is not clear at present. The sum of these findings suggested that the predominance of Th2 cells and the consequent overexpression of IL-4 and IL-13 in peripheral blood may be deeply involved in the pathogenetic process of AD. [Copyright &y& Elsevier]

Stem cell factor is essential to the migration and differentiation of melanocytes during embryogenesis based on the observation that mutations in either the stem cell factor gene, or its ligand, KIT, result in defects in coat pigmentation in mice. Stem cell factor is also required for the survival of melanocyte precursors while they are migrating towards the skin. Transforming growth factor β1 has been implicated in the regulation of both cellular proliferation and differentiation. NCC-melb4, an immortal cloned cell line, was cloned from a mouse neural crest cell. NCC-melb4 cells provide a model to study the specific stage of differentiation and proliferation of melanocytes. They also express KIT as a melanoblast marker. Using the NCC-melb4 cell line, we investigated the effect of transforming growth factor β1 on the differentiation and proliferation of immature melanocyte precursors. Immunohistochemically, NCC-melb4 cells showed transforming growth factor β1 expression. The anti-transforming growth factor β1 antibody inhibited the cell growth, and downregulated the KIT protein and mRNA expression. To investigate further the activation of autocrine transforming growth factor β1, NCC-melb4 cells were incubated in nonexogenous transforming growth factor β1 culture medium. KIT protein decreased with anti-transforming growth factor β1 antibody concentration in a concentration-dependent manner. We concluded that in NCC-melb4 cells, transforming growth factor β1 promotes melanocyte precursor proliferation in autocrine and/or paracrine regulation. We further investigated the influence of transforming growth factor β1 in vitro using a neural crest cell primary culture system from wild-type mice. Anti-transforming growth factor β1 antibody decreased the number of KIT positive neural crest cell. In addition, the anti-transforming growth factor β1 antibody supplied within the wild-type neural crest explants abolished... [ABSTRACT FROM AUTHOR]

The effects of all-trans retinoic acid on the differentiation and proliferation of immature melanocyte precursors were studied. NCC-melb4 cells are an immortal cloned cell line established from mouse neural crest cells using a single-cell cloning method. These cells were positive for tyrosinase-related protein 1, tyrosinase-related protein 2 and KIT, but were negative for tyrosinase and had no dihydroxyphenylalanine reaction. They contained only stage I melanosomes without any melanosomes in more advanced stages. After treatment with all-trans retinoic acid, many of the cells became tyrosinase- and dihydroxyphenylalanine-reaction-positive, changed from polygonal to dendritic in shape, and had stage III to IV melanosomes. These findings indicate that treatment with all-trans retinoic acid induced the differentiation of NCC-melb4 cells. Reverse transcription polymerase chain reaction analysis revealed a marked increase in expression of microphthalmia-associated transcription factor mRNA after all-trans retinoic acid treatment, suggesting that microphthalmia-associated transcription factor may be the key molecule in this event. Enhanced expression of protein kinase Cα following treatment with all-trans retinoic acid was also demonstrated. The proliferation of NCC-melb4 cells was inhibited by all-trans retinoic acid in a dose-dependent manner. Increased apoptosis after all-trans retinoic acid treatment was observed by electron microscopy, the TUNEL method, DNA fragmentation assay, and flow cytometry. All-trans retinoic acid upregulated caspase-3 and downregulated bcl-2. Electron microscopy showed that apoptotic cells contained melanosomes of advanced stages, suggesting that mature melanocytes may tend to undergo apoptosis after all-trans retinoic acid treatment. This study provides important clues towards understanding the roles and working mechanisms of retinoic acids in melanocyte development and melanogenesis. [ABSTRACT FROM AUTHOR]

Summary: Background: Atopic dermatitis (AD) is an allergic skin disease that follows a clinical course of ‘flare-up’ and remission. Histamine and tryptase are inducers of pruritus and non-sedating second-generation antihistamines, including fexofenadine, are widely used for treatment of allergic skin disorders. Objective: We assessed the efficacy of a second-generation antihistamine in AD patients and examined its pharmacological effects on chemical mediators. Methods: The scoring atopic dermatitis (SCORAD) instrument and visual analogue scale (VAS) for pruritus were used to assess disease severity in 349 AD patients. Twenty patients with moderate AD symptoms, who had not received any treatment for 2 weeks, were randomly assigned into two groups. Ten patients underwent fexofenadine and emollient treatment (Group 1) and 10 received fexofenadine and steroid treatment (Group 2) for 1 week. SCORAD and VAS for pruritus, and blood histamine and tryptase levels were evaluated before and after treatment. Results: SCORAD and VAS improved in both Group 1 (p =0.01 and p =0.006, respectively) and Group 2 (p <0.001 and p =0.001, respectively). The improvement in Group 1 showed a significant correlation with the diminution rate of blood tryptase levels (SCORAD: r =0.83 and p =0.013, respectively; VAS: r =0.81, p =0.015, respectively). End-point plasma tryptase levels were significantly lower than baseline levels in Group 2 (p =0.046). Histamine levels did not show any significant changes in either group. Conclusion: These results suggest that second-generation antihistamine therapy reduces AD pruritus, resulting in the effective clinical treatment for AD. In addition, monitoring tryptase levels during antihistamine therapy in moderate AD treatment may prove to be useful in establishing treatment effects. [Copyright &y& Elsevier]

Summary: Background:: Our previous study showed that T cells in skin lesions of human atopic dermatitis (AD) had oligoclonal accumulation, indicating the involvement of antigen-specific immune reactions at those sites. Recently, NC/Nga mice, which develop skin lesions similar to AD, have been proposed as a model for that disease. Objective:: To clarify whether NC/Nga mice are suitable as a model for human AD from the viewpoint of their antigen-specific immune responses. Methods:: Reverse transcription-polymerase chain reaction (RT-PCR) and single strand conformation polymorphism (SSCP) analyses were conducted to detect TCR BV genes of clonally expanded T cells derived from NC/Nga mice at an early phase of the AD-like dermatitis, at a late phase of the dermatitis, and with no AD-like dermatitis. Results:: (1) T cells with TCR BV 7, 10 and 17 reside in the skin of NC/Nga mice without the AD-like dermatitis. (2) T cells with these BV genes contain oligoclonal accumulations, however, expanded T cell clonotypes are also detected in the spleen and exist constantly during the course of the AD-like dermatitis. (3) Development of the AD-like dermatitis is associated with additional oligoclonal expansion/accumulation of T cells with TCR BV 2, 4 and 6 genes. (4) Progression of the AD-like dermatitis is associated with further oligoclonal expansion/accumulation of T cells with the TCR BV 14 gene. (5) Some of the expanded TCR clonotypes are common between the individual mice and between early and late phases. Conclusions:: Taking these data together with the previous human AD studies, NC/Nga mice seem to be an appropriate model for human AD. [Copyright &y& Elsevier]

Summary: Background: In congenital or acquired dermal melanocytosis, attachment of melanocyte with elastic fiber was shown in electron microscopy of unknown biological meaning. We hypothesize elastin-derived peptide may play a role in activating dermal melanocyte precursors. Objectives: This study was designed to determine: (i) whether melanocyte precursors express elastin binding protein (EBP); (ii) ontogenic expression of EBP and elastin in murine embryonic skin; (iii) the effects of elastin-derived peptide (VGVAPG) on melanocyte precursors. Methods: Using immunohistochemistry or Western blot to identify EBP on murine embryonic sections, neural crest cell (NCC) primary culture explants, or two melanocyte precursor cell lines, NCCmelb4 and NCCmelan5. NCC explants or cells were treated with VGVAPG to compare its effect on proliferation, dendrite formation, melanosome maturation and tyrosinase mRNA expression of melanocyte precursors. Results: EBP was immunostained on c-kit+ melanocyte precursors. 67kDa EBP protein was immunoblotted on NCCmelb4 and NCCmelan5 cells. EBP was expressed early at embryonic day (E) 9.5, but elastin appeared later at E12.5 skin. VGVAPG increased DOPA-positive cell number and enhanced their dendrite formation in NCC explants. Electron microscopy showed advanced melanosome maturation in NCC explants or cells treated with VGVAPG. VGVAPG enhanced tyrosinase mRNA expression in NCCmelan5 cells. Conclusions: Melanocyte precursors expressed EBP. VGVAPG stimulated their melanogenesis and dendrite formation. In the developmental journey interaction between elastin and EBP-expressed melanocyte precursors in embryos happened mainly since the stage of tertiary melanoblasts. These findings first provide biological evidences for the interaction between melanocyte and elastic fiber. [Copyright &y& Elsevier]

Genes encoding Kit and the Kit ligand (KL) play essential roles in the differentiation of melanoblasts. We previously established three immortal but distinct cell populations of mouse neural crest (NC) cells. NCCmelb4M5 cells do not express Kit and grow independently of KL; they have the potential to differentiate into NCCmelb4 cells, which are Kit-positive melanocyte precursors. NCCmelan5 cells show the characteristics of differentiated melanocytes. All three cell lines demonstrated bone morphogenetic protein (BMP) receptor expression. BMP-4 upregulated Kit protein and mRNA expression in most immature NCCmelb4M5 cells. Noggin, a BMP-4 antagonist, dramatically decreased the Kit expression induced by BMP-4. Western blot analysis revealed that extrinsic BMP-4 leads to the phosphorylation of Smads in NCCmelb4M5 cells. Using transfected Kit-promoter reporter, we showed BMP-4 could activate Kit promoter in transfected NCCmelb4M5 cells. We conclude that BMP-4 is active and is involved in the regulation of Kit expression on most immature melanocyte precursors. We further investigated the influence of BMP-4 in vitro using primary NC cells cultured from wild-type mice. Addition of BMP-4 to the medium increased the number of Kit-positive cells compared to diluent-treated controls. We have identified BMP-4 as an important factor for prenatal Kit-negative melanoblasts just prior to entering the Kit-dependent cycle of melanogenesis.Journal of Investigative Dermatology (2008) 128, 1220–1226; doi:10.1038/sj.jid.5701136; published online 25 October 2007 [ABSTRACT FROM AUTHOR]

Summary: Background: We have established two immature melanocyte cell lines from murine neural crest cells. NCC-E3 cells have Stage II melanosomes and express tyrosinase while in NCCmelb4 cells, the melanosomes remain at Stage I and tyrosinase is not expressed. These cell lines may be useful in studying the differentiation of melanocyte precursors. Objective: To perform proteomic analysis of the two cell lines to identify proteins related to and possibly responsible for their different maturation stages. Methods: Western blotting, two-dimensional differential image gel electrophoresis (2D-DIGE), liquid chromatography–tandem mass spectrometry (LC–MS/MS), real-time PCR analysis and RNA interference using siRNA were employed in this study. Results: Western blotting revealed that the processed form of gp100, which is specific for Stage II melanosomes, is expressed in NCC-E3 cells but not in NCCmelb4 cells. 2D-DIGE identified two protein spots showing 4.06- and 2.22-fold increases in NCC-E3 cells compared to NCCmelb4 cells. Analysis of those proteins by LC–MS/MS revealed that the former was calreticulin and the latter was BiP/GRP78. When calreticulin mRNA expression in NCC-E3 cells was blocked by siRNA, tyrosinase protein was abolished and DOPA-reactivity was decreased, although tyrosinase mRNA was abundantly expressed after the same treatment. Conclusion: Calreticulin, a lectin chaperone, is an essential molecule for the processing of tyrosinase in murine melanocytes. The role of molecular chaperones such as calreticulin should be considered when analyzing the mechanism(s) of melanocyte differentiation. [Copyright &y& Elsevier]

Summary: Background: Blood platelets store sphingosine 1-phosphate (S1P) abundantly and release this bioactive lipid extracellularly. S1P acts as an intercellular mediator through interaction with the endothelial differentiation gene (EDG)/S1P family of G protein-coupled receptors. Of the EDG family S1P receptors, EDG-5 (S1P2) is inhibited in migration induced by S1P. Diabetes impairs numerous aspects of tissue repair. Failure of wound angiogenesis is known to delay diabetic wound healing. Objectives: We examined whether S1P subcutaneous injection could improve the healing of full-thickness skin wounds in healthy and diabetic mice. We further determine if the combined S1P and EDG-5 (S1P2) antagonist injection in diabetic mice could affect wound healing. Finally, we examined the histopathological findings of the wound following S1P injection in diabetic mice. Methods: Eight- to 10-week-old BALA/c mice, diabetic db/db mice and Wister rats were used for the studies. A full-thickness wound was made on the dorsal skin of the healthy and diabetic mice. Either 10μM or 100μM of S1P or vehicle control (BSA/PBS) was injected into the wound bed every day. We calculated the wound area after each injection. EDG-5 (S1P2) antagonist (JTE-013) or vehicle (DMSO) was then injected in addition to the S1P around the dorsal wound of diabetic mice and the wound diameter was measured. Wound tissue samples were excised following injection for histopathological examination. Results: Wound area in normal BALA/c mice did not significantly decrease upon S1P injection compared to S1P-untreated controls. S1P injection alone showed significant promotion of wound healing in diabetic mice compared to no S1P treatment. The combination of S1P and EDG-5 (S1P2) receptor antagonist administration induced maximal wound healing in diabetic mice. Histopathological examination revealed that S1P induces neo-vascularization potential in rats and diabetic mice wound. Conclusions: S1P injection in diabetic mice significantly accelerated cutaneous wound healing in the neo-vascularization process. The results demonstrate that S1P affects and sustains all key cellular processes responsible for wound repair and point to a unique potential for this molecule in the therapy of diabetic wounds, particularly as an angiogenic agent in treatment of diabetic wounds. [Copyright &y& Elsevier]

Abstract: The murine recessive yellow (Mc1r e ) is a loss-of-function mutation in the receptor for α-melanocyte-stimulating hormone, melanocortin receptor 1 (Mc1r) and produces yellow coats by inducing pheomelanin synthesis in hair follicular melanocytes. However, it is not known whether the Mc1r e mutation affects the proliferation and differentiation of melanocytes. In this study, the proliferation and differentiation of recessive yellow epidermal melanocytes cultured in dibutyryl cyclic AMP-supplemented serum-free medium were investigated in detail. The melanocytes produced mainly eumelanin in this culture system. The proliferation of recessive yellow melanocytes was decreased compared with that of wild-type at the e-locus, black melanocytes. The differentiation of melanocytes was also delayed and inhibited in recessive yellow mice. Tyrosinase (TYR) activity and TYR-related protein 1 (TRP1) and TRP2 (dopachrome tautomerase, DCT) expressions were decreased and, in addition, the maturation of stage IV melanosomes was inhibited. Excess l-tyrosine (l-Tyr) added to the culture media rescued the reduced activity of proliferation of melanocytes. l-Tyr also stimulated TYR activity and TRP1 and TRP2 expressions as well as the maturation of stage IV melanosomes and pigmentation. These results suggest that the Mc1r e mutation affects the proliferation and differentiation of melanocytes and l-Tyr rescues the reduced proliferative and differentiative activities by stimulating TYR activity and TRP1 and TRP2 expressions as well as melanosome maturation. [Copyright &y& Elsevier]

Abstract: The slaty (Dct slt ) mutation is known to reduce the activity of dopachrome tautomerase (DCT) in melanocytes. However, it is unknown whether the reduced DCT activity leads to a defect in the proliferation and differentiation of mouse melanocytes. To address this point, the proliferation and differentiation of neonatal melanocytes from Dct slt /Dct slt congenic mice in serum-free primary culture were investigated in detail. The proliferation of slaty epidermal melanoblasts/melanocytes in culture did not differ from that of wild-type mice. However, the differentiation was greatly inhibited. Tyrosinase (TYR) activity detected by dopa reaction as well as staining of DCT in slaty melanocytes was greatly reduced. The content of eumelanin in cultured slaty melanocytes was reduced, whereas the content of pheomelanin in media derived from cultured 7.5-day-old slaty melanocytes was greatly increased. The contents of eumelanin and pheomelanin in the neonatal slaty epidermis and dermis were reduced, except that the pheomelanin content in 3.5-day-old dermis was increased. These results suggest that the slaty mutation affects both eumelanin and pheomelanin synthesis in developmental stage-specific and skin site-specific manners, and, in addition, the gene controls the differentiation of melanocytes via the regulation of activity of TYR in addition to its own DCT. [Copyright &y& Elsevier]

Stem cell factor (SCF) and its receptor, KIT, are essential to the migration and differentiation of melanocytes during embryogenesis. We previously demonstrated that apoptosis is induced by blocking survival function of the SCF/KIT interaction in a mouse neural crest cell (NCC) primary culture. Using the NCCmelb4 cell line, we investigated the occurrence of apoptosis in the cultured cells when KIT receptors were blocked by the monoclonal anti-KIT antibody (ACK2). Apoptosis following treatment with ACK2 was detected by DNA fragmentation assay,in situapoptosis detection, and electron microscopy. We noted a decrease in extracellular signal-related kinase (ERK) and ribosomal S6 kinase (RSK) protein expression following ACK2 incubation. Western blot analysis and real-time quantitative RT-PCR revealed an apparent time-dependent reduction in Bcl-2 protein levels with respect to ACK2 within the NCCmelb4 cells. In terms of Bax expression, a difference was not found. Fas and caspase8 proteins increased time-dependently in proportion to ACK2 incubation. We noted apoptotic cell death upon addition of ACK2, with evidence of possible involvement of Bcl-2 and Fas in the induction of apoptosis. In contrast, no significant correlation between Fas ligand (Fas-L) expression and ACK2 was found. Fas activation appears to occur independent of Fas-L during ACK2-induced cell death. Therefore, we propose that Fas-L expression in NCCmelb4 cells does not play a major role in facilitating apoptosis. Furthermore, we hypothesize that these molecules combined with SCF/KIT play an important role in regulating the induction of vertebrate NCC apoptosis during embryogenesis. [ABSTRACT FROM AUTHOR]

Background: Atopic dermatitis (AD) is a common chronic inflammatory and allergic skin disease that almost always begins in childhood and follows a course of remittance and flare-up. AD is characterized by intense pruritus and itchiness that can be triggered by an interplay of genetic, immunologic and environmental factors. Of the mediators, histamine is one of the most potent inducers of pruritus. Serum tryptase, which is also a mediator, may be used to examine allergic disease as well. The development of minimal sedation H1 antihistamines (second-generation antihistamines) has revolutionized treatment of allergic diseases. Objective: The present study examines the efficacy of second-generation antihistamines in relieving pruritus due to AD. In addition, the relationship between AD pruritus and antihistamine therapy was analyzed by measuring the blood histamine and tryptase levels. Methods: Thirty-two AD patients were recruited and underwent second-generation antihistamine therapy for 2 weeks. Seventeen received combined topical corticosteroid treatment (Group 1) and the other 15 did not receive steroid treatment (Group 2). The Severity Index and Pruritus Score were assessed as an AD clinical activity index and compared with baseline data. Results: Both the Severity Index and Pruritus Score improved significantly in Group 1 (P<0.001, P<0.05). Group 2 demonstrated a significant improvement in Pruritus Score (P<0.05), but not in the Severity Index. Plasma histamine levels were significantly higher in AD at baseline compared with healthy controls. Conclusion: Following antihistamine therapy, these levels decreased significantly in both AD groups (P<0.05). There was a significant correlation between baseline blood histamine and typtase levels. However, this correlation was not evident following treatment. This may reflect insufficient detection capabilities of the measuring assay. The present results suggest that second-generation antihistamine therapy provides an effective clinical treatment for AD, with a notable improvement in pruritus. Furthermore, antihistamine therapy reduced plasma histamine levels in AD patients. These findings further suggest that high blood histamine and tryptase levels in AD patients contribute to the pathogenesis of this disorder, including the onset of pruritus. [Copyright &y& Elsevier]