角质形成细胞和成纤维细胞对白癜风发病和治疗的影响

黑素细胞在白癜风发病及治疗中是最关键的一环，但表皮、真皮间的沟通联系对皮损及非皮损皮肤的功能均具有重要影响，其中角质形成细胞、成纤维细胞及细胞外基质等非黑素细胞起了重要作用，并影响白癜风的发病。本文从细胞因子、氧化应激等角度总结了角质形成细胞、成纤维细胞对白癜风发病的影响及在临床治疗中的作用机制。     

寻常型进行期白癜风患者白斑区角质形成细胞凋亡的检测

目的探讨进行期白癜风患者白斑区角质形成细胞是否出现凋亡及其凋亡相关蛋白的表达。方法标本分别取自15例进行期白癜风患者白斑中心区及15例正常人对照，均取材于胸腹部。采用末端脱氧核苷酸转移酶介导的dUTP缺口末端标记技术（TUNEL）检测角质形成细胞的凋亡状况，同时采用免疫组化法检测角质形成细胞表达凋亡相关蛋白Bax、Bcl-2和Caspase3的情况。结果TUNEL结果显示：15例白癜风患者白斑区均可见角质形成细胞存在不同程度凋亡，主要位于表皮中层及下层，密集或散在分布；15例正常人对照中仅有1例表皮可见10％极为散在的凋亡的角质形成细胞，两组比较差异有统计学意义（P〈0．01）。免疫组化结果显示：7例白癜风患者白斑区可检测到部分角质形成细胞存在促凋亡相关蛋白Bax的弱表达，而对照组仅有1例TUNEL阳性者可检出Bax的弱表达，即白癜风皮损区角质形成细胞Bax表达较正常对照显著升高，差异有统计学意义（P〈0．01）。所有标本中角质形成细胞均未检测到Bcl-2和Caspase3的表达。结论进行期白癜风白斑区角质形成细胞促凋亡蛋白Bax表达升高，其凋亡增加。     

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.     

白癜风患者皮损NF-E2相关因子2的表达

目的 分析白癜风患者皮损处Nrf 2表达水平。方法 采用AEC免疫组化法检测4例表皮移植的寻常型白癜风患者皮损处Nrf 2的表达，蛋白印迹分析表皮移植的8例寻常型白癜风患者皮损组织和其正常供皮处组织细胞核和细胞质中Nrf 2的表达水平，并进行统计学差异分析。结果 与白癜风患者正常供皮处组织相比，皮损处Nrf 2的表达多数集中在角质形成细胞的胞质中，细胞核中表达量非常低。蛋白印迹结果表明，白癜风患者皮损处核蛋白中Nrf 2表达水平（0.10 ± 0.03）显著低于正常部位（0.26 ± 0.03，P < 0.01），胞质蛋白中皮损处Nrf 2表达水平（0.61 ± 0.03）与正常部位（0.60 ± 0.02）差异无统计学意义（P > 0.05）。结论 白癜风患者皮损处存在Nrf 2核转位异常。     

干细胞因子及其受体与白癜风

在皮肤表皮层，干细胞因子表达于角质形成细胞，其受体表达于黑素细胞，二者不但参与神经嵴细胞发育为黑素细胞进程中黑素细胞分化、增殖和迁移过程，而且在维持成熟黑素细胞正常功能中也发挥作用。阻断干细胞因子与其配体的结合可导致黑素细胞合成黑素功能受损，白癜风患者皮损中发现二者存在表达异常；因此，干细胞因子及其配体可能参与白癜风的发病过程。     

T细胞、角蛋白10、Ki-67在进展期银屑病皮损和皮损边缘皮肤的表达和意义

目的：探讨T细胞、增殖标记（Ki-67）、角蛋白10阳性细胞在进展期银屑病皮损和皮损边缘皮肤的水平。方法：采用免疫组化法检测19例寻常型银屑病进展期皮损中央、皮损边缘、皮损边缘正常皮肤和远离皮损5em正常皮肤的T细胞亚群、Ki-67和K10^＋的表达。结果：皮损边缘CD4^＋、CD25^＋T细胞数目明显增多，表皮增殖标记（Ki-67）明显增加，而K10^＋呈低表达。结论：CD4^＋、CD25^＋T细胞在银屑病发病的早期起着一定作用，Ki-67表达水平反映了角质形成细胞的增殖状态，K10^＋在银屑病皮损的低表达意味着角化过程普遍受损。     

干细胞因子及其受体在寻常型白癜风表皮中的表达

目的 探讨SCF/c-kit信号通路在白癜风发病中的作用。方法 采用免疫组化和RT-PCR法检测17例寻常型稳定期白癜风患者和10例正常对照标本中表皮角质形成细胞的干细胞因子表达及基底层黑素细胞c-kit的表达情况。结果 白癜风非皮损区干细胞因子、c-kit蛋白表达与正常对照无明显差异(P>0.05),皮损区干细胞因子表达显著高于正常对照皮肤(P<0.05),而c-kit表达显著低于正常对照皮肤(P<0.05)。白癜风非皮损区表皮干细胞因子、c-kit mRNA表达平均水平与正常对照近似(P>0.05);皮损区干细胞因子mRNA表达水平高于非皮损区及正常对照组差异有统计学意义(P<0.05);皮损区c-kit mRNA表达水平显著低于非皮损区及正常对照组(P<0.05)。结论 SCF/c-kit的异常表达可能与白癜风的发病有关。     

白癜风皮损组织中黑素细胞谱系特异性标记基因检测

目的针尖皮肤切削术结合逆转录聚合酶链式反应（RT—PCR）技术检9n,4白癜风皮损组织中黑素细胞谱系特异性标记基因的表达,旨在预测治疗后白癜风皮损出现毛囊复色的可能性。方法选取6例就诊于武汉大学人民医院皮肤科静止期白癜风患者和4例健康志愿者,用针尖皮肤切削术对受试者白斑的中心、近边缘和周边“正常皮肤”处活检,抽提组织总RNA,用RT—PCR技术测定标本中多巴色素异构酶（Dct）,酪氨酸酶（Tyr）和管家基因β-肌动蛋白（ACTB）mRNA的表达。结果（1）用针尖皮肤切削术获取不同大小（3mg和7mg）的组织标本并与负压吸疱法采集的表皮片进行比较,结果显示针头切削术获取7mg组织,经研磨异硫氰酸胍-苯flff（Triz01）法抽提总RNA,能在正常皮肤组织中检测到3种基因表达。同时对10例针尖皮肤切削术后的局部伤口愈合进行了追踪随访,1个月后10例均正常愈合,未见瘢痕形成。（2）白癜风皮损黑素细胞谱系特异性标记基因检测：皮损中心区检测出3种模式,即Dct＋Tvr-ACTB＋,Dct—Tyr-ACTB＋和Dct＋Tyr＋ACTB＋。对1例检测结果“Dct＋Tyr-ACTB＋”的患者施以308nm准分子光照射2次,皮损即出现毛囊复色。结论针尖皮肤切削术结合RT—PCR技术检测白癜风皮损组织中黑素细胞谱系标记基因表达,是一种有价值的预测白癜风皮损可能出现毛囊复色的微创准确方法。     

正常皮肤银屑病皮损和皮肤鳞癌组织酪氨酸蛋白激酶活性的研究

目的　探讨角质形成细胞异常增生的发病机理。方法　通过外源性底物磷酸化方法，测定了１６ 例正常皮肤、２２ 例银屑病皮损、５ 例皮肤鳞癌组织角质形成细胞膜酪氨酸蛋白激酶（ Ｔ Ｐ Ｋ） 的活性。结果　角质形成细胞膜 Ｔ Ｐ Ｋ 活性在银屑病和癌组织中显著增高，且癌组织又明显高于银屑病皮损。结论　提示 Ｔ Ｐ Ｋ 活性的异常可能在角质形成细胞的异常增生中起重要作用。     

白癜风皮损中NPY VIP和SP的研究

目的 探讨NPY（神经肽Y）、VIP（血管活性肠肽）、SP（神经肽P物质）在白癜风发病机制中的作用。方法 采用SABC免疫组化法对20例白癜风患者（活动期10例，稳定期10例）的皮损、非皮损区以及10例正常人皮肤中的NPY、VIP和SP进行研究，并测定各组皮肤标本中NPY、VIP及SP的免疫反应性。结果 活动期白癜风皮损中NPY、VIP及SP的免疫反应性明显增强，与正常对照及未受累皮肤比较差异有差异性，NPY与SP的反应在白癜风活动期皮损与稳定期皮损比较差异也有显著性。VIP的免疫反应性在白癜风活动期皮损与稳定期皮损中相比稍增强，但差异无统计学意义。结论 神经多肽与白癜风的发病有关，尤其与白癜风的活动性有关。NPY和SP可能在白癜风的发病机制中也起一定的作用。     

Flow cytometry for separation of keratinocyte subpopulations from the viable epidermis

Human epidermal cell suspensions were analyzed and sorted with flow cytometry. The desmosome and differentiation-related KM48 monoclonal antibody was used for indirect immunofluorescence and permitted staining of keratinocytes at various stages of the cell maturation. Intensity of the staining correlated with the degree of differentiation. Three sorting gates were chosen to obtain subpopulations which varied distinctly in KM48 expression. The flow cytometry-sorted cells were characterized by their ultrastructural appearance and by the bullous pemphigoid antigen expression. According to the ultrastructure criteria, about 50% of the cells obtained from the "IF negative" gate were basal layer keratinocytes (45.5% expressed bullous pemphigoid antigen); 90% of the "intermediate" gate cells were spinal layer keratinocytes, and over 80% of the cells sorted through the "strongly IF positive" gate were of the granular layer type. The method of keratinocyte separation proposed allows samples to be obtained for further biochemical and functional studies on keratinocyte subpopulations in normal and pathologic skin.     

Characterization of the ultraviolet B and X-ray response of primary cultured epidermal cells from patients with disseminated superficial actinic porokeratosis

BACKGROUND: Disseminated superficial actinic porokeratosis (DSAP) is the most common porokeratosis and is characterized by multiple keratotic lesions which tend to occur at sun-exposed sites. A mild hypersensitivity to X-rays has been reported for DSAP-derived fibroblasts and frequent over-expression of p53 has been found in lesional epidermis. OBJECTIVES: In order to clarify whether genome maintenance mechanisms might be compromised in this disease the following approaches were undertaken: (i) primary cultured keratinocytes and fibroblasts from DSAP patients were characterized for ultraviolet (UV) B and X-ray response; (ii) 15 lesions were studied for p53 mutations, and (iii) the differentiation status of DSAP-derived keratinocytes was evaluated. METHODS: Primary cultures of keratinocytes and fibroblasts were established from lesional and nonlesional skin biopsies of two subjects with DSAP. p53 mutations were analysed by DNA sequencing of the conserved region of the TP53 gene. Differentiation was evaluated both in stratified epithelial sheets from confluent keratinocyte cultures and in organotypic skin cultures. RESULTS: The cytotoxic and apoptotic response to UVB or X-irradiation was similar in DSAP-derived keratinocytes and fibroblasts when compared with normal cells. Two of 15 lesions examined presented p53 mutations located at nondipyrimidine sites. A strikingly decreased expression of filaggrin was observed both in reconstructed epidermis and in reconstructed skin. CONCLUSIONS: The UVB and X-ray response of DSAP-derived keratinocytes and fibroblasts indicates that the actinic character of this skin pathology is not due to radiation hypersensitivity. In agreement with this finding, mutations in the p53 gene, which are often associated with UV-related skin carcinogenesis, were rarely detected in DSAP lesions and were not UV-specific. Reconstructed epidermis and reconstructed skin models successfully reproduced the main features of this genodermatosis, showing that DSAP-derived keratinocytes bear an inherent defect in the terminal differentiation programme.     

T‐lymphocyte‐induced,fas‐mediated apoptosis is associated with early keratinocyte differentiation

Please cite this paper as: T‐lymphocyte‐induced, fas‐mediated apoptosis is associated with early keratinocyte differentiation. Experimental Dermatology 2009. Abstract: The development of eczematous lesions is thought to be due in part to a breakdown in skin barrier function as a result of T lymphocytes (T cells) invading the skin causing epidermal keratinocyte apoptosis. In this study, we investigated the interaction of T cells and keratinocytes on apoptosis and terminal differentiation using an in vitro co‐culture system. Experiments were performed using the HaCaT keratinocyte cell line or normal human epidermal keratinocytes. Activated human peripheral blood‐derived T cells were found to induce Fas‐dependent keratinocyte apoptosis by up to sixfold. Increased Fas was associated with increased IFN‐γ. The T‐cell apoptotic signal was found to target preferentially keratinocytes in the very early stages of terminal differentiation, such as those with low levels of α6‐integrin expression, and result in subsequent increased caspase 3 activity. This observation was accompanied by a marked increase in keratinocyte ICAM‐1 expression and its ligand LFA‐1 on T cells. Our data suggest that T cells may initiate the onset of keratinocyte terminal differentiation making them more susceptible to Fas‐dependent cell death signals delivered by the T cells.     

Consequences of depleted SERCA2-gated calcium stores in the skin

Sarco(endo)plasmic reticulum Ca2+-ATPase isoform 2 (SERCA2) pumps belong to the family of Ca2+-ATPases responsible for the maintenance of calcium in the endoplasmic reticulum. In epidermal keratinocytes, SERCA2-controlled calcium stores are involved in cell cycle exit and onset of terminal differentiation. Hence, their dysfunction was thought to provoke impaired keratinocyte cohesion and hampered terminal differentiation. Here, we assessed cultured keratinocytes and skin biopsies from a canine family with an inherited skin blistering disorder. Cells from lesional and phenotypically normal areas of one of these dogs revealed affected calcium homeostasis due to depleted SERCA2-gated stores. In phenotypically normal patient cells, this defect compromised upregulation of p21(WAF1) and delayed the exit from the cell cycle. Despite this abnormality it failed to impede the terminal differentiation process in the long term but instead coincided with enhanced apoptosis and appearance of chronic wounds, suggestive of secondary mutations. Collectively, these findings provide the first survey on phenotypic consequences of depleted SERCA-gated stores for epidermal homeostasis that explain how depleted SERCA2 calcium stores provoke focal lesions rather than generalized dermatoses, a phenotype highly reminiscent of the human genodermatosis Darier disease.     

Keratinocyte growth regulation in defined organotypic cultures through IL-1-induced keratinocyte growth factor expression in resting fibroblasts

Balanced keratinocyte proliferation and differentiation resulting in regular tissue organization strictly depend on dermal support. Organotypic cultures represent biologically relevant in vitro models to study the molecular mechanism of the underlying dermal-epidermal interactions. To mimic the state of resting fibroblasts in the dermis, postmitotic (irradiated) fibroblasts were incorporated in the collagen matrix, where they typically support epidermal proliferation and tissue organization. In coculture with keratinocytes, fibroblasts exhibit an enhanced expression of keratinocyte growth factor and the interleukin-1 receptor (type I), which further increase with culture time. In cocultured keratinocytes, keratinocyte growth factor receptor as well as RNA expression and protein release of interleukin-1alpha and interleukin-1beta are upregulated. We hypothesized that the modulated cytokine expression represents a basic mechanism for keratinocyte growth regulation. The functional significance of this double paracrine pathway, i.e., induction of keratinocyte growth factor expression in fibroblasts by keratinocytes via release of interleukin-1, was confirmed by interfering with both signaling elements: (i) interleukin-1-neutralizing antibodies and interleukin-1 receptor antagonist significantly inhibited keratinocyte growth factor release, keratinocyte proliferation, and tissue formation comparable to the effect produced by keratinocyte-growth-factor-blocking antibodies; (ii) addition of keratinocyte growth factor to cocultures with inactivated interleukin-1 pathway completely reverted growth inhibition; (iii) in organotypic cocultures with subthreshold fibroblast numbers both interleukin-1 and keratinocyte growth factor restored the impaired epidermal morphogenesis. Thus, epidermal tissue regeneration in organotypic cocultures is mainly regulated by keratinocyte-derived interleukin-1 signaling, which induces keratinocyte growth factor expression in cocultured fibroblasts. This demonstrates a novel role for interleukin-1 in skin homeostasis substantiating data from wound healing studies in vivo.     

Keratinocyte cytogenetics in 10 patients with pigmentary mosaicism: identification of one case of trisomy 20 mosaicism confined to keratinocytes

Background.  Hypomelanosis of Ito and linear and whorled hypermelanosis are pigmentary disorders that follow Blaschko's lines and are associated with cytogenetic mosaicism. However, mosaicism cannot always be shown using conventional karyotyping of blood lymphocytes or skin fibroblasts. This may be because these cell lines originate from mesoderm, whereas Blaschko's lines are an ectodermal phenomenon.
Objectives.  To investigate the diagnostic value of keratinocyte cytogenetics in patients with pigmentary mosaicism (PM).
Methods.  We undertook a prospective study of 10 patients with clinically suspected PM. Previous karyotyping of blood, and in some cases skin fibroblasts, was normal in all cases. Keratinocytes and fibroblasts were cultured from skin biopsies taken from light and dark skin, and examined for cytogenetic abnormalities.
Results.  In 9 of 10 cases both keratinocyte and fibroblast cytogenetic analyses were normal. The remaining patient showed trisomy 20 mosaicism confined to keratinocytes from hypopigmented skin. Fluorescent in situ hybridization using a probe for 20q confirmed trisomy 20 mosaicism in keratinocytes but not fibroblasts, with higher signal expression in hypopigmented compared with normal skin.
Conclusions.  In patients with clinically suspected PM but normal blood cytogenetics, keratinocytes may be more sensitive than skin fibroblasts in identifying cytogenetic mosaicism in selected patients. However, the additional diagnostic yield appears to be insufficient to justify routine keratinocyte cytogenetic investigation. Our findings indirectly support the hypothesis that Blaschko's lines delineate the embryonal migration paths taken by ectodermal cells including keratinocytes and melanocytes.     

Purification and in vitro growth of human epidermal basal keratinocytes using a monoclonal antibody

We have made a new monoclonal antibody, EL-2, and used it with an immunorosetting procedure combined with Ficoll-Hypaque gradient centrifugation to purify and culture basal keratinocytes. Immunofluorescence of cell suspensions and immunoperoxidase staining of tissue sections demonstrate that EL-2 reacts with malignant cell lines, activated lymphocytes and monocytes, and basal keratinocytes. Sequential immunoprecipitation studies demonstrate that monoclonal antibodies EL-2 and 4F2 detect the same membrane protein. However, we have extended previous studies by making the new observation that both EL-2 and 4F2 react with cultured melanocytes. Basal keratinocytes were purified from single-cell epidermal suspensions by incubation with EL-2 followed by rosetting with rabbit antimouse IgG antibodies covalently linked to bovine red blood cells. Rosetting (basal) keratinocytes were separated from EL-2 negative cells by Ficoll gradient centrifugation. We obtained basal keratinocyte populations of greater than 90% purity as assessed by reactivity with EL-2 and another basal keratinocyte-specific monoclonal antibody, HCl. Langerhans cell, fibroblast, and melanocyte contamination was negligible. Cultures of basal keratinocytes were enriched in EL-2-reactive cells throughout the entire 19 days of culture studied. EL-2 is being used to characterize disorders of keratinocyte proliferation; EL-2 reacted with both squamous and basal cell carcinomas. EL-2 stained only the basal layer of lesional skin from patients with psoriasis, pityriasis rubra pilaris, and Darier's disease. Purification of basal keratinocytes will be important in biochemical and functional studies of normal skin and in establishing long-term keratinocyte lines from normal cells.     

Complexity of VEGF responses in skin carcinogenesis revealed through ex vivo assays based on a VEGF-A null mouse keratinocyte cell line

Vascular endothelial growth factor (VEGF-A) is a critical player in cutaneous angiogenesis. However, the relative contribution of VEGF-A from different sources including epithelial and mesenchymal cells has not been fully characterized during skin repair and tumorigenesis. Moreover, the actual involvement of other vascular-specific acting molecules has remained elusive in part due to the masking and/or overlapping effects of VEGF-A. To shed light on these uncertainties we generated and characterized a clonal VEGF-null mouse keratinocyte cell line, through in vitro adenoviral gene transfer of Cre recombinase to VEGF-LoxP primary keratinocytes followed by repeated cell passaging under controlled conditions and cloning. In vitro and in vivo assays demonstrated that VEGF-null keratinocytes were nontumorigenic and expressed normal differentiation markers after calcium switch. Hras-induced tumorigenesis of immortalized VEGF-null keratinocytes upon subcutaneous injection was markedly reduced but not fully suppressed. However, the metastatic ability of Hras-transformed VEGF-null keratinocytes was abolished. These ex vivo approaches suggest the existence of VEGF-dependent and independent angiogenic stimuli in skin carcinogenesis. The VEGF-null mouse keratinocyte cell line arises as an important tool to assess the actual contribution of keratinocyte-derived VEGF with respect to other angiogenic factors in skin homeostasis and malignancy.     

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.