Differential expression of inflammatory cytokines and chemokines in lipopolysaccharide‐stimulated melanocytes from lightly and darkly pigmented skin

Increasing evidence suggests that human epidermal melanocytes play an important role in the skin immune system; however, a role of their pigmentation in immune and inflammatory responses is poorly examined. In the study, the expression of Toll‐like receptor 4 (TLR4) and inflammatory cytokines and chemokines by cultured normal melanocytes derived from lightly and darkly pigmented skin was investigated after cell stimulation with lipopolysaccharide (LPS). The basal TLR4 mRNA level in heavily pigmented cells was higher as compared to their lightly pigmented counterparts. Melanocyte exposure to LPS upregulated the expression of TLR4 mRNA and enhanced the DNA‐binding activity of NF‐κB p50 and p65. We found substantial differences in the LPS‐stimulated expression of numerous genes encoding inflammatory cytokines and chemokines between the cells with various melanin contents. In lightly pigmented melanocytes, the most significantly upregulated genes were nicotinamide phosphoribosyltransferase (NAMPT/visfatin), the chemokines CCL2 and CCL20, and IL6, while the genes for CXCL12, IL‐16 and the chemokine receptor CCR4 were the most significantly upregulated in heavily pigmented cells. Moreover, the lightly pigmented melanocytes secreted much more NAMPT, CCL2 and IL‐6. The results of our study suggest modulatory effect of melanogenesis on the immune properties of normal epidermal melanocytes.     

bFGF对人毛囊黑素细胞增殖、活化和黑素合成作用的研究

目的　研究碱性成纤维细胞生长因子 (bFGF)对人毛囊黑素细胞 (Hairfolloclemelanocyte ,HFM )增殖活化和黑素合成的影响。方法　体外培养正常人HFM ,观察不同浓度bFGF(0 3～ 1 2ng ml)对HFM形态、增殖、酪氨酸酶活性和黑素含量的影响。结果　bFGF处理HFM 7d后 ,HFM树突增多延长 ,酪氨酸酶活性和黑素含量增加显著高于对照组 (P <0 0 1) ,以 0 6ng ml组为著。结论　bFGF能诱导HFM增殖、酪氨酸酶活性和黑素合成增加     

Preliminary evaluation of vitiligo using in vivo reflectance confocal microscopy

BACKGROUND: Vitiligo is the most common pigmentary disorder with a global incidence from 0.1% to 2% in different geographical areas. Histopathology and histochemistry have shown the reduction of melanocytes in achromic patches, but microscopic changes of lesional and non-lesional skin are still not completely understood. Reflectance confocal microscopy (RCM), based on the different light reflectance index of cutaneous structures, allowed in vivo, en face microscopic evaluation of superficial skin layers with a resolution similar to skin histology. AIM: The purpose of this study was to evaluate RCM features of lesional and non-lesional skin of vitiligo patients. Moreover, re-pigmented areas were taken into consideration in order to evaluate melanocyte response to ultraviolet B (UVB) radiation. SUBJECTS AND METHODS: Sixteen patients of different phototypes affected by active non-segmental vitiligo and 10 controls were enrolled in the study. In vivo skin imaging was done using a commercially available RCM (Lucid, Vivascope 1500. Re-pigmented areas from 6 to 16 patients (after UVB narrow-band therapy) were also examined. RESULTS: Vitiligo lesions showed the disappearance of the bright rings normally seen at the dermo-epidermal junction. Moreover, non-lesional skin of vitiligo patients showed unexpected changes as the presence of half-rings or scalloped border-like features of the bright papillary rings. In re-pigmented areas after UVB narrow band therapy, the presence of activated, dendritic melanocytes was seen. CONCLUSIONS: Considering our results, and following further studies, RCM clinical applications could be used in the therapeutic monitoring and evaluation of the evolution of vitiligo.     

Extensive Aberrant Mongolian Spot

A 9-month-old male infant had generalized diffuse blue-gray pigmentation over most of his body, sparing the scalp, face, neck, palms, soles, periumbilical area, genital area, and nipples. Within the lesion, there were several conspicuous macules of considerably darker hue. Histologic examination revealed numerous dermal melanocytes. By 16 months of age, the child's blue-gray pigmentation had decreased substantially.     

Cytokines: the yin and yang of vitiligo pathogenesis

Introduction: Dysregulation of melanocyte function is associated with vitiligo, an idiopathic autoimmune hypopigmentary skin disorder, caused by the selective destruction of melanocytes. Cytokines, the key mediators of immune response, which are pivotal in maintaining immune homeostasis, are crucial in vitiligo pathogenesis. Several studies indicate that there is an imbalance between pro- and anti-inflammatory cytokines in the skin and serum of vitiligo patients.

Areas covered: In this comprehensive review, we have summarized the correlation of cytokine imbalance and vitiligo pathogenesis, its role in melanocyte biology, and its impact on vitiligo treatment. We have integrated various published reports on the levels of major cytokines from skin and serum samples of vitiligo patients. We have also discussed the role of endoplasmic reticulum and oxidative stress on cytokine imbalance and vice versa leading to destruction of melanocytes.

Expert commentary: The review reflects that dysregulation of cytokines is multifactorial, ranging from genetic predisposition to altered protein expression relevant to vitiligo pathogenesis. We emphasize that cytokine imbalance in systemic and skin microenvironment plays a crucial role in vitiligo pathogenesis and has promising potential as therapeutic targets for vitiligo.     

白癜风临床分析及实验研究

目的：了解白癜风的临床特点,探讨其发病机制。方法：回顾分析2008例白癜风患的临床资料;以酶联免疫吸附法检测283例白癜风患血清中的抗黑素细胞IgG抗体;以免疫组织化学染色法检测45例白癜风患血清中的抗黑素细胞IgG抗体和IgM抗体;观察25例活动期白癜风血清对补体介导的黑素细胞损伤的作用。结果：①2008例白癜风患中,男女患之比为1．06,平均就诊年龄23．2岁,平均发病年龄为20岁,6例出生时即患病,头面及颈部为最易受累部位。临床分型以双侧型最多见,82．2％的患就诊时处于进展期,303例（15．0％）患伴发其他疾病,其中有110例（5．5％）合并晕痣,156例（7．8％）患有家族史,337例（16．4％）有明确的促发因素。②25例活动期白癜风患血清中有19例（76％）检出IgG型抗体,21例（84％）检出IgM型抗体,明显高于非活动期白癜风患（35％,10％）和正常对照（10％,0）（P＜0．01）。③25例活动期白癜风患血清9例（36％）出现对黑素细胞的明显细胞毒作用,正常人血清及对照的成纤维细胞未出现明显的细胞毒作用。结论：白癜风可出生即患;自身抗体在白癜风的发病中起重要作用。     

UVA1 impairs the repair of UVB‐induced DNA damage in normal human melanocytes

The exact correlation between melanoma and sun‐light is still a controversially debated issue. Although natural sunlight contains various ratios of UVA and UVB, most investigators so far focused on the effects of single solar wavebands and neglected possible interactions. Therefore, in this study primary human melanocytes of three donors were simultaneously exposed to physiologic doses of UVA1 and UVB. Effects on apoptosis were analysed using annexin V assays and cell death ELISAs, and effects on DNA damage were investigated using southwestern slot blots. While UVA1 did not influence UVB‐induced apoptosis, UVA1 impaired the repair of UVB‐induced cyclobutane pyrimidine dimers (CPD) as the amount of CPD was 1.8 times higher in UVA1 + UVB than in UVB only exposed melanocytes six hours after irradiation. We conclude that UVA1 might contribute to melanomagenesis as it partially inhibits the repair of UVB‐induced CPD in human melanocytes while it does not affect UVB‐mediated apoptosis.     

Characterization of pigmented dermo‐epidermal skin substitutes in a long‐term in vivo assay

In our laboratory, we have been using human pigmented dermo‐epidermal skin substitutes for short‐term experiments since several years. Little is known, however, about the long‐term biology of such constructs after transplantation. We constructed human, melanocyte‐containing dermo‐epidermal skin substitutes of different (light and dark) pigmentation types and studied them in a long‐term animal experiment. Developmental and maturational stages of the epidermal and dermal compartment as well as signs of homoeostasis were analysed 15 weeks after transplantation. Keratinocytes, melanocytes and fibroblasts from human skin biopsies were isolated and assembled into dermo‐epidermal skin substitutes. These were transplanted onto immuno‐incompetent rats and investigated 15 weeks after transplantation. Chromameter evaluation showed a consistent skin colour between 3 and 4 months after transplantation. Melanocytes resided in the epidermal basal layer in physiological numbers and melanin accumulated in keratinocytes in a supranuclear position. Skin substitutes showed a mature epidermis in a homoeostatic state and the presence of dermal components such as Fibrillin and Tropoelastin suggested advanced maturation. Overall, pigmented dermo‐epidermal skin substitutes show a promising development towards achieving near‐normal skin characteristics and epidermal and dermal tissue homoeostasis. In particular, melanocytes function correctly over several months whilst remaining in a physiological, epidermal position and yield a pigmentation resembling original donor skin colour.