黑素细胞功能相关性细胞因子的研究进展

色素性皮肤病与黑素细胞的发育、分化、增殖及活性密切相关。表皮细胞产生自分泌及旁分泌的细胞因子网络对黑素细胞的功能起到重要的调节作用。本文综述了碱性成纤维细胞生长因子、干细胞因子、内皮素、白细胞介素-1对黑素细胞功能的影响,进一步探讨了上述细胞因子在色素性皮肤病发病机制中的作用,为色素病的治疗提供新思路。     

白癜风皮损中非黑素细胞进展

白癜风的发病机制尚未完全明了.其发病除黑素细胞异常外,还涉及非黑素细胞的变化,近年来非黑素细胞在白癜风中的研究逐渐增多.研究表明,一些皮肤非黑素细胞如角质形成细胞、朗格汉斯细胞、成纤维细胞等与黑素细胞关系密切,这些细胞影响黑素细胞的迁移、增殖、分化等功能.白癜风皮损中非黑素细胞超微结构的异常和分泌细胞因子的变化可影响黑素细胞的活性及凋亡,影响皮肤色素生成,从而参与白癜风发病.     

白癜风患者转化生长因子β1蛋白和mRNA的表达

白癜风白斑处黑素细胞消失的原因至今未明。角质形成细胞可通过合成和分泌多种细胞因子来实现对黑素细胞的调控。角质形成细胞除了分泌促进黑素细胞增殖的一些因子外,还能产生抑制黑素细胞增殖的细胞因子。转化生长因子β(transforming growth factors β,TGFβ)是黑素细胞生长的抑制剂,能抑制正常人黑素细胞的增殖和DNA的合成。我们采用免疫组化及原位杂交的方法检测TGFβ₁在白癜风皮损中的表达,以探讨TGFβ₁在白癜风发病中的可能作用。     

黑素细胞痣的形成机制

黑素细胞痣临床常见,通过对发疹性黑素细胞痣与免疫抑制剂的关系分析,认为黑素细胞痣的产生与免疫抑制有关.促黑素细胞激素-α能促进黑素细胞的增殖,在黑素细胞痣形成中发挥作用.其可通过环磷腺苷途径上调小眼畸形相关转录因子的表达,促进黑素细胞的增殖.促黑素细胞激素-α和免疫抑制剂影响朗格汉斯细胞、T细胞及IL-10、IL-12等细胞因子,可能作用于促分裂原激活蛋白激酶信号通路,上调小眼畸形相关转录因子的表达,从而导致黑素细胞痣的形成.     

干细胞因子对黑素细胞调控的研究进展

表皮中的干细胞因子主要来源于角质形成细胞 ,黑素细胞在其分化的一些阶段中表达干细胞因子的配体 ,干细胞因子通过与其配体作用对黑素细胞的存活、分化、移行、增生等起到调节作用。     

干细胞因子对黑素细胞调控的研究进展

表皮中的干细胞因子主要来源于角质形成细胞，黑素细胞在其分化的一些阶段中表达干细胞因子的配体，干细胞因子通过与其配体作用对黑素细胞的存活、分化、移行、增生等起到调节作用。     

细胞因子对黑素细胞生物学特性的影响

多种细胞因子具有改变黑素细胞的形态、抑制其增殖及黑素合成,并对黑素细胞表达细胞间粘连分子、HLA-Ⅱ类抗原、黑素瘤相关抗原,以及分泌纤维联结蛋白产生影响作了介绍。阐述了在皮肤色素减退过程中细胞因子所起的作用。     

真皮黑素细胞的研究进展

真皮干细胞具有增殖和多向分化的潜能,角质形成细胞通过表达Wnt3a和E钙黏素来诱导真皮干细胞移行和分化为黑素细胞.研究表明,在黑素细胞形成过程中,真皮黑素细胞与表皮黑素细胞依赖的信号通路明显不同,表皮黑素细胞高度依赖干细胞因子信号通路,而真皮黑素细胞高度依赖内皮素3和肝细胞生长因子信号通路.目前关于色素痣痣细胞的来源尚不清楚,有研究认为,痣细胞来源于能分化为黑素细胞的干细胞,真皮干细胞能分化为黑素细胞,是否是痣细胞的来源尚需进一步研究.     

Th17细胞与白癜风的发病机制

白癜风是一种常见的皮肤病,其原因是皮肤黑素细胞的缺失。黑素细胞缺失的确切机制尚不清楚,研究指出,细胞免疫在白癜风发病机制中起到重要作用。在某些特定细胞因子的作用下,CD4＋T细胞分化为Th17细胞,Th17细胞可参与多种疾病的发病。在白癜风发病过程中,Thl7细胞和树突细胞数量增多,功能活跃。Th17细胞除主要分泌IL-17外,还分泌IL-6、IL-21、IL-22和肿瘤坏死因子d等细胞因子,他们参与白癜风发病,导致黑素细胞生成减少、萎缩、消失,黑素生成减少,最终形成白癜风。     

角朊细胞对黑素细胞生物学性状影响的研究现状

近年体外研究发现,角朊细胞在一定条件下能释放多种细胞因子,这些因子对黑素细胞的增殖、形态及黑素合成有着一定的影响,提示表皮内角朊细胞可能会通过产生各种细胞因子影响黑素细胞的生物学性状。此外,黑素细胞与角朊细胞的接触也为相互影响的重要途径之一。     

Life cycle of human melanocytes is regulated by endothelin-1 and stem cell factor in synergy with cyclic AMP and basic fibroblast growth factor

BackgroundAlthough the function of human melanocytes is well characterized at cellular and molecular levels, the mechanism of the regulation of the life cycle (proliferation, differentiation, and cell death) of human melanocytes is not fully understood.ObjectiveThis study aims to clarify what factors are involved in regulating the life cycle of human melanocytes using serum-free culture system.MethodsHuman epidermal melanocytes were cultured in a serum-free growth medium supplemented with several kinds of growth factors, cytokines, and hormones and the effects of these factors on the life cycle of melanocytes were investigated in detail.ResultsOf the factors tested, endothelin-1 (ET-1) stimulated the proliferation of melanoblasts and melanocytes in the presence of cyclic AMP (cAMP)-elevating factor such as dibutyryl cAMP (DBcAMP) and of basic fibroblast growth factor (bFGF). ET-1 also stimulated the proliferation and differentiation of human melanocytes in the presence of DBcAMP. Moreover, stem cell factor (SCF) stimulated the proliferation of melanoblasts and melanocytes synergistically with ET-1. The removal of ET-1 and SCF from the culture medium greatly inhibited the proliferation of melanocytes followed by apoptotic cell death.ConclusionThese results suggest that the life cycle of human melanocytes is regulated by ET-1 and SCF in synergy with cAMP and bFGF.     

Co-culture of melanocytes with adipose-derived stem cells as a potential substitute for co-culture with keratinocytes

Cell-to-cell interactions between melanocytes and keratinocytes increase the proliferation and migration of melanocytes. In fact, mixed keratinocyte and melanocyte cultures have been used for autologous cell transplantation for treatment of vitiligo. However, this may require taking an amount of skin tissue large enough to leave scars. In this study, the in vitro effect of adipose-derived stem cells (ADSCs) on proliferation, differentiation and migration of melanocytes was compared with that of keratinocytes using immunohistochemistry and a Boyden chamber migration assay. The proliferation and migration of melanocytes was significantly stimulated by co-culture with ADSCs compared with melanocyte monocultures, al-though the effect of ADSCs was less powerful than that of keratinocytes. This may be related to increases in stem cell factor and basic fibroblast growth factor, growth factors for melanocytes, produced by the ADSCs. The ratios of melanocytes stained with antibodies against Trp-2, E-cadherin and N-cadherin were significantly increased by co-culturing with ADSCs compared with co-culturing with keratinocytes as well as melanocyte monocultures. The proportion of less-pigmented melanocytes was also increased and sustained for a longer duration in the presence of ADSCs. Our data show that co-culturing with ADSCs results in increased melanocyte proliferation and migration while reducing differentiation, and could provide a means to treat disorders such as vitiligo.     

Transforming growth factor beta1 regulates melanocyte proliferation and differentiation in mouse neural crest cells via stem cell factor/KIT signaling

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 beta1 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 beta1 on the differentiation and proliferation of immature melanocyte precursors. Immunohistochemically, NCC-melb4 cells showed transforming growth factor beta1 expression. The anti-transforming growth factor beta1 antibody inhibited the cell growth, and downregulated the KIT protein and mRNA expression. To investigate further the activation of autocrine transforming growth factor beta1, NCC-melb4 cells were incubated in nonexogenous transforming growth factor beta1 culture medium. KIT protein decreased with anti-transforming growth factor beta1 antibody concentration in a concentration-dependent manner. We concluded that in NCC-melb4 cells, transforming growth factor beta1 promotes melanocyte precursor proliferation in autocrine and/or paracrine regulation. We further investigated the influence of transforming growth factor beta1 in vitro using a neural crest cell primary culture system from wild-type mice. Anti-transforming growth factor beta1 antibody decreased the number of KIT positive neural crest cell. In addition, the anti-transforming growth factor beta1 antibody supplied within the wild-type neural crest explants abolished the growth of the neural crest cell. These results indicate that transforming growth factor beta1 affect melanocyte precursor proliferation and differentiation in the presence of stem cell factor/KIT in an autocrine/paracrine manner.     

Protective effect of Kit signaling for melanocyte stem cells against radiation-induced genotoxic stress

Radiation-induced hair graying is caused by irreversible defects in the self-renewal and/or development of follicular melanocyte stem cells in the hair follicles. Kit signaling is an essential growth and differentiation signaling pathway for various cell lineages including melanocytes, and its radioprotective effects have been shown in hematopoietic cells. However, it is uncertain whether Kit signaling exerts a radioprotective effect for melanocytes. In this study, we found that various loss-of-function mutations of Kit facilitate radiation-induced hair graying. In contrast, transgenic mice expressing the ligand for Kit (Kitl) in the epidermis have significantly reduced levels of radiation-induced hair graying. The X-ray doses used did not show a systemic lethal effect, indicating that the in vivo radiosensitivity of Kit mutants is mainly caused by the damaged melanocyte stem cell population. X-ray-damaged melanocyte stem cells seemed to take the fate of ectopically pigmented melanocytes in the bulge regions of hair follicles in vivo. Endothelin 3, another growth and differentiation factor for melanocytes, showed a lesser radioprotective effect compared with Kitl. These results indicate the prevention of radiation-induced hair graying by Kit signaling.     

体外诱导小鼠骨髓间充质干细胞分化为黑素细胞的观察

【摘要】 目的 探讨骨髓间充质干细胞体外诱导成为黑素细胞的可能性。方法　6周龄雄性C57BL/6小鼠股骨基质细胞行原代培养,6次传代后以氢化可的松、重组人胰岛素、转铁蛋白和成纤维细胞生长因子诱导黑素细胞。倒置光学显微镜观察细胞分化;透射电镜观察黑素小体成熟;免疫荧光染色观察黑素细胞相关表位表达;流式细胞仪检测黑素细胞的细胞周期及获得率。结果　6次传代间充质干细胞数量近109,免疫荧光检测CD44阳性率94.3%和CD105阳性率82.3%。培养180 d,细胞形态接近于黑素细胞,树突增多,胞质内出现黑素小体样结构,生长周期加快为3 ~ 4 d,肉眼可见棕黑色细胞沉淀。电镜观察显示Ⅳ期为主的黑素小体。免疫荧光显示酪氨酸酶相关蛋白-1,酪氨酸酶相关蛋白-2和小眼畸形相关转录因子阳性。流式细胞仪分析显示细胞基本处于G1和S期。酪氨酸酶相关蛋白-1阳性的黑素细胞获得率约为80%。结论　骨髓间充质干细胞可以被大量诱导分化为黑素细胞;诱导黑素细胞的形态学、超微结构、特异性表位等皆接近于正常黑素细胞,具有一定的增殖活性,获得率较高。 【关键词】 间质干细胞; 骨髓; 黑素细胞; 体外研究     

Transforming growth factor beta1 induces apoptosis in normal melanocytes but not in nevus cells grown in type I collagen gel

We used type I collagen gel cultures to compare the growth requirements of melanocytes and dermal nevus cells. Melanocytes but not nevus cells undergo apoptosis in collagen unless supplied with growth stimulators such as fibroblast growth factor 2. To characterize the mechanism of melanocyte apoptosis in collagen, we tested the effects of transforming growth factor beta1, known to be functionally active in the skin. When picomolar amounts of transforming growth factor beta1 were added to normal melanocytes grown in type I collagen gel, their apoptosis was dramatically accelerated. In contrast, the apoptotic rate of nevus cells and melanoma cells grown under similar conditions was not affected by transforming growth factor beta1. The increased apoptosis of normal melanocytes was effectively counteracted by addition of either neutralizing transforming growth factor beta1 antibodies or fibroblast growth factor 2 to the collagen gel. Interestingly, the background apoptosis of normal melanocytes was also inhibited by transforming growth factor beta1 antibodies. By Western blotting we detected transforming growth factor beta-like immunoreactivity in melanocyte, nevus cell, and melanoma cell lysates. A sensitive bioassay confirmed that their medium contained considerable amounts of heat-activatable growth inhibitory activity that could partly be neutralized by transforming growth factor beta1 antibodies. It is evident that apoptosis of melanocytes grown in type I collagen gel can be mediated by both endogenous and exogenous transforming growth factor beta. We suggest that the balance between inhibitory growth factors such as transforming growth factor beta and stimulatory growth factors like fibroblast growth factor 2 has the potential to regulate the growth, localization, and survival of normal melanocytes also in vivo. The resistance of nevus cells to transforming-growth-factor-beta-mediated apoptosis may facilitate their ability to grow in the dermal compartment of the skin.     

Keratinocytes regulate the function of melanocytes

Mammalian keratinocytes compose the bulk of the epithelium, undergo keratinization, and form the dead superficial layer of the skin. These superficial keratinized cells are continuously replaced by cells derived from mitotic cells in the lowest layer of the epidermis (i.e., the basal layer). Melanocytes locate in the basal layer and do not keratinize; however, they can produce melanin pigments. Melanin is accumulated in small granules called melanosomes. The melanosomes are transported to dendrites from which the melanosomes are transferred to keratinocytes. Epidermal invaginations such as keratinocytes and melanocytes extend to the dermis to form hair follicles. In addition to these two cells, dermal fibroblasts are also required for the formation of hair follicles. The homeostasis of the epidermis and hair follicle is primarily regulated by the cellular interaction between keratinocytes and melanocytes. Keratinocytes stimulate melanocyte functions such as proliferation, differentiation, melanogenesis, and dendritogenesis. Using the techniques of tissue culture, biochemistry, and molecular biology, factors that have been derived from keratinocytes are hormones, growth factors, and cytokines such as α-melanocyte-stimulating hormone, adrenocorticotrophic hormone, basic fibroblast growth factor, nerve growth factor, endothelins, granulocyte-macrophage colony-stimulating factor, stem cell factor, leukemia inhibitory factor, and hepatocyte growth factor. These keratinocyte-derived paracrine factors have a key role in regulating melanocyte function through receptor-mediated signaling pathways, followed by maintaining epidermal and hair follicular homeostasis.