Leukotriene C4 and TGF-alpha are stimulators of human melanocyte migration in vitro

Nigella sativa L. seed extract alleviates oxidative stress-induced cellular senescence and dysfunction in melanocytes

Nigella sativa L. seeds have been traditionally utilized in Chinese folk medicine for centuries to treat vitiligo. This study revealed that the ethanolic extract of Nigella sativa L. (HZC) enhances melanogenesis and mitigates oxidative stress-induced cellular senescence and dysfunction in melanocytes. In accordance with established protocols, the ethanol fraction from Nigella sativa L. seeds was extracted, concentrated, and lyophilized to evaluate its herbal effects via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, tyrosinase activity evaluation, measurement of cellular melanin contents, scratch assays, senescence-associated β-galactosidase (SA-β-gal) staining, enzyme-linked immunosorbent assay (ELISA), and Western blot analysis for expression profiling of experimentally relevant proteins. The results indicated that HZC significantly enhanced tyrosinase activity and melanin content while notably increasing the protein expression levels of Tyr, Mitf, and gp100 in B16F10 cells. Furthermore, HZC effectively mitigated oxidative stress-induced cellular senescence, improved melanocyte condition, and rectified various functional impairments associated with melanocyte dysfunction. These findings suggest that HZC increases melanin synthesis in melanocytes through the activation of the MAPK, PKA, and Wnt signaling pathways. In addition, HZC attenuates oxidative damage induced by H2O2 therapy by activating the nuclear factor E2-related factor 2-antioxidant response element (Nrf2-ARE) pathway and enhancing the activity of downstream antioxidant enzymes, thus preventing premature senescence and dysfunction in melanocytes.

The role of signaling pathways mediated by the GPCRs CysLTR1/2 in melanocyte proliferation and senescence

In contrast with sun exposure-induced melanoma, rarer melanocytic tumors and neoplasms with low mutational burden present opportunities to study isolated signaling mechanisms. These include uveal melanoma and blue nevi, which are often driven by mutations within the G protein-coupled signaling cascade downstream of cysteinyl leukotriene receptor 2. Here, we review how the same mutations within this pathway drive the growth of melanocytes in one tissue but can inhibit the growth of those in another, exemplifying the role of the tissue environment in the delicate balance between uncontrolled cell growth and senescence.

Urinary metabolomic investigations in vitiligo patients

Urinary metabolomics is a useful non-invasive tool for large-scale screening of disease-related metabolites. However, no comprehensive urinary metabolomic analysis of vitiligo is presently available. To investigate the urine metabolic pattern of vitiligo patients, we conducted a combined cross-sectional and prospective self-control cohort study and an untargeted urinary metabolomic analysis. In the cross-sectional study, 295 vitiligo patients and 192 age‐ and sex‐matched controls were enrolled, and 71 differential metabolites between two groups were identified. Pathway enrichment analysis revealed that drug metabolism-cytochrome P450, biopterin metabolism, vitamin B9 (folate) metabolism, selenoamino acid metabolism, and methionine and cysteine metabolism showed significant enrichment in vitiligo patients compared with the status in healthy controls. In the self-control cohort, 46 active vitiligo patients were recruited to analyse the urinary metabolic signatures after treatment. All of these patients were asked to undertake follow-up visits every 2 months three times after first consulting and the disease stage was evaluated compared with that at the last visit. Folate metabolism, linoleate metabolism, leukotriene metabolism, alkaloid biosynthesis, and tyrosine metabolism were predicted to be involved in vitiligo activity. Our study is the first attempt to reveal urinary metabolic signatures of vitiligo patients and provides new insights into the metabolic mechanisms of vitiligo.

Comparative efficacy between localized 308-nm excimer light and targeted 311-nm narrowband ultraviolet B phototherapy in vitiligo: A randomized, single-blind comparison study

BACKGROUND

There are limited data to compare efficacy between recent 308-nm excimer and conventional 311-nm narrowband ultraviolet B (NB-UVB) light in the treatment of vitiligo.

OBJECTIVE

To compare efficacy between 308-nm excimer light and 311-nm NB-UVB in patients with symmetrical vitiligo lesions.

METHODS

Thirty-six symmetrically paired vitiligo lesions on the same anatomical area were enrolled. One side of the symmetrical lesions was treated with localized 308-nm excimer light, and the opposite side was treated with targeted 311-nm NB-UVB assigned randomly by computer. All lesions were treated with the same protocol, for 48 sessions. Repigmentation was evaluated using Vitiligo Area Scoring Index (VASI) and grading the repigmentation was carried out with three independent investigators.

RESULTS

Thirty-six symmetrically vitiligo lesions were randomly treated, one side with 308-nm excimer light and the opposite side with 311-nm NB-UVB. After 48 sessions, a significantly lower VASI score and a higher grade of repigmentation were observed in 308-nm excimer light-treated side (P < .001). Nine lesions (25%) treated with 308-nm excimer light and only five lesions (13.89%) treated with 311-nm NB-UVB achieved excellent repigmentation. The 308-nm excimer light and 311-nm NB-UVB-treated sides rapidly obtained 25% repigmentation within a mean of 19.42 sessions and 26.25 sessions, respectively (P = .002). There was no significant difference in mean cumulative UV dosage (P = .065). Side effect as phototoxicity was similar in both sides (P = .08).

CONCLUSION

Localized 308-nm excimer light appears to be more effective and also more rapidly induces repigmentation than targeted 311-nm NB-UVB for treatment of vitiligo.

Therapeutic effects of iNOS inhibition against vitiligo in an animal model

Nitric oxide (NO) is involved in several biological processes, but its role in human melanogenesis and vitiligo need further studies. Previous studies revealed that exposure to UVA and UVB were capable of the inducing nitric oxide production in keratinocytes and melanocytes through the activation of constitutive nitric oxide synthase, whereas inducible nitric oxide synthase overexpression has been reported to play an important role in hyperpigmentary disorders. The aim of this study was to evaluate iNOS inhibitor aminoguanidine (AG) as a therapeutic agent in our mouse model of vitiligo. In this study, male C57BL/6J Ler-vit/vit mice were purchased to evaluate the effect of iNOS inhibitor (aminoguanidine) (50 and 100 mg/kg) and L-arginine (100 mg/kg) in a mouse model of vitiligo induced by monobenzone 40%. Moreover, we used phototherapy device to treat the mice with NBUVB as a gold standard.The findings revealed that monobenzone was capable of inducing depigmentation after 6 weeks. However, aminoguanidine in combination with monobenzone was decrease the effect of monobenzone, while L-arginine play a key role in promoting the effect of monobenzone (P<0.001). Based on the phototherapy, the efficacy of phototherapy significantly increased by adding L-arginine (P<0.05). Taken together, we suggest that iNOS inhibitor can be a novel treatment for the prevention and treatment of vitiligo by combination of NBUVB therapy, furthermore; NO agents like L-arginine could also increase the effectiveness of phototherapy. Taken together, this pilot study showed significant repigmentation of vitiligous lesions treated with iNOS inhibitor plus NBUVB therapy, where other aspect including expression of an inducible iNOS, NO and TNF levels remained to be evaluated in mice model.

Treatment of vitiligo with NB-UVB: A systematic review

OBJECTIVE

To assess the effect and safety of NB-UVB for vitiligo using an evidence-based approach.

METHODS

Randomized controlled trials (RCTs) on the treatment of vitiligo with NB-UVB were identified by searching PubMed and the Cochrane Library. The primary outcome was re-pigmentation degree.

RESULTS

A total of seven RCTs involving 232 participants with vitiligo were included in this systematic review. The methodological qualities of included studies were generally moderate. Two trials compared narrow-band ultraviolet B (NB-UVB) with UVA control, showing no significant differences between two methods on the number of patients who achieved >60% re-pigmentation [relative risk (RR) = 2.50, 95% confidence interval (CI): 0.11-56.97, p > 0.05]. Two trials compared NB-UVB with psoralens plus UVA (PUVA) control, and no difference was seen between the two treatments on the number of patients who achieved >50 re-pigmentation (RR = 1.16, 95% CI: 0.64-2.11, p > 0.05) or >75% re-pigmentation (RR = 2.00, 95% CI: 0.89-4.48, p > 0.05). Three trials compared NB-UVB with 308-nm excimer light/laser (EL) control, and again no significant difference was found between the two methods (p > 0.05). The adverse events of NB-UVB in the included studies were slight and tolerated.

CONCLUSION

NB-UVB showed equivalent efficacies to UVA, PUVA or 308-nm EL control in the treatment of vitiligo. Side effects of NB-UVB were acceptable. More RCTs were needed to validate the results.

Comparison of the 308-nm excimer laser with the 308-nm excimer lamp in the treatment of vitiligo--a randomized bilateral comparison study

BACKGROUND

Vitiligo is an acquired pigment disorder characterized by areas of depigmented skin resulting from the loss of epidermal melanocytes. Recently, several investigations have documented the benefits of excimer phototherapy (e.g., using the 308-nm excimer laser or the 308-nm excimer lamp) for the treatment of vitiligo.

AIM

To compare the effectiveness of the 308-nm excimer laser with the 308-nm excimer lamp in the treatment of vitiligo patients.

METHODS

This intervention study was designed as a randomized self-control trial. Fourteen subjects with 48 symmetrical vitiligo lesions were enrolled in this study. One lesion was treated with the 308-nm excimer laser, and its counterpart was treated with the 308-nm excimer lamp. Lesions were treated three times a week with the same dose on both sides for a total of 20 sessions.

RESULTS

All of the patients completed the study, and 48 lesions were treated. The two treatments exhibited similar results in terms of repigmentation.

CONCLUSIONS

The 308-nm excimer lamp and the 308-nm excimer laser exhibited similar efficacies in treating vitiligo.

WITHDRAWN: Comparision between 308-nm excimer laser and 308-nm excimer lamp in the treatment of vitiligo - a randomized self control study

Ahead of Print article withdrawn by publisher.

The association between melasma and postinflammatory hyperpigmentation in acne patients

Background

Although, melasma is most prevalent among Asian young women, and also darkly pigmented individuals are particularly prone to developing post inflammatory hyperpigmentation, to the best of our knowledge, there are rare or no studies about the association of melasma and Post inflammatory hyperpigmentation.

Objectives

The aim of this study was to investigate how likely is a melasma patient to developed post inflammatory hyperpigmentation when compared to patients with inflammatory acne lesions who do not have melasma.

Patients and Methods

This comparative study was conducted on 400 participants, 200 subjects involved with pigmented lesions of melasma and inflammatory acne lesions and200 involved only with inflammatory Acne lesions without melasma. Melasma, acne and post inflammatory hyper pigmentation, if existed, were assessed by a dermatologist, and pigmentation depth was assessed by wood's lamp. Multivariate logistic regression analysis suitable for study design was used to assess the association between melasma and post-acne pigmentation.

Results

We found out that 24.1% of patients without melasma had post-acne pigmentation compared to 66.8% in melasma group (P < 0.001). The likelihood of observing post-acne pigmentation was found to be nearly six times more in melasma patients versus those without melasma. Association existed after controlling for possible confounders such as melanin score and time length of self-reported sun exposure, and acne severity score.

Conclusions

Melasma appears to increase the likelihood of post-acne pigmentation.

Vitiligo road map

Vitiligo is a depigmenting disorder stemming from melanocyte loss or dysfunction. It has a complex, multifaceted etiology. We constructed a "vitiligo road map," consisting of basic science, clinical, and treatment components, in order to better portray our current understanding of vitiligo pathogenesis and reflect upon novel biomarkers and therapeutic targets for future research. The melanocyte map elaborates on the molecular processes and intracellular signaling pathways initiated by various external autocrine/paracrine factors in representing normal melanocyte homeostatic functions modulating its viability, proliferation, differentiation, dendricity, migration, and melanogenic processes. This vitiligo map identifies known inducers/triggers of vitiligo onset and progression that cultivate a microenvironment for melanocyte disappearance, real or functional. This map describes the molecular mechanisms of currently utilized clinical and experimental treatments of vitiligo that facilitate repigmentation.

Possible mechanisms by which topical 5-Fluorouracil and dermabrasion could induce pigment spread in vitiligo skin: an experimental study

The combination of skin ablation and 5-Fluorouracil (5-FU) ointment was previously tried in the treatment of vitiligo, and good results were specifically reported in glabrous skin without follicular melanocyte reservoirs. Methods. This study was carried out on the skins of seven guinea pigs: three were treated with mechanical dermabrasion plus topical 5-FU in an achromic area contiguous to a pigmented area; two were treated by only dermabrasion in a similar area; and two were treated by topical 5-FU alone. Clinical, histological, and ultrastructural studies were performed over two months. Results. In guinea pigs treated with dermabrasion plus 5-FU, we observed firstly a delay of wound healing with an obvious inflammatory reaction, and, after two months, evident pigment spread from the pigmented into the achromic area. After six months, we noticed black hair regrowing in the achromic area. Pigment spread was not seen in the guinea pigs skin treated by either dermabrasion or topical 5-FU. We suggest that the inflammatory mediators and enzymes (metalloproteinases), which are locally released over a long time, could stimulate and facilitate melanocyte proliferation and migration through the enlarged intercellular spaces of the epidermis. This sequence of events may be applied to vitiligo patients treated with 5-FU on ablated lesions.

Aesthetic and technical refinements in latissimus dorsi implant breast reconstruction: a 15-year experience

BACKGROUND

The latissimus dorsi myocutaneous flap and implant breast reconstruction procedure has undergone many refinements over its lifetime. In fact, the authors have made many aesthetic and technical refinements to their own approach to breast reconstruction.

OBJECTIVES

The authors review the historical progression of latissimus flap and breast reconstruction techniques and compare these to their own 15-year experience.

METHODS

A retrospective chart review was conducted for all latissimus and implant breast reconstructions performed by the senior author (MAC) from July 1994 to June 2009, for a total of 52 procedures in 31 patients. Surgical and oncological data, complications, and outcomes data were recorded.

RESULTS

The mean age of the patients at time of surgery was 47.6 years. Average mastectomy weight was 283 grams and average final implant volume was 364 cc. Average follow-up was three years, four months. Of the 52 total procedures, 34.6% were immediate breast reconstructions utilizing skin-sparing mastectomy (SSM); 13.5% of the reconstructed breasts also had preservation of the areola (areolar-sparing mastectomy [ASM]). The most common complication was donor site seroma (40.4%). Aesthetic and surgical refinements identified over the time period included the adoption of SSM and ASM techniques, immediate nipple reconstruction, the placement of an adjustable saline implant to allow for postoperative size adjustment, and implant placement in the prepectoral position. The overall latissimus dorsi implant reconstruction success rate was 94.2% (49/52).

CONCLUSIONS

The data demonstrated a successful outcome for latissimus dorsi and implant breast reconstruction for patients with a low or normal body mass index and a small (A to C cup) breast size. The aesthetic outcome of latissimus dorsi breast reconstruction has been improved over the past 15 years by the adoption of SSM and ASM techniques. Immediate nipple reconstruction and the placement of an adjustable saline implant potentially render this procedure a true single-stage reconstruction. Prepectoral implant position provides good aesthetics while preserving the subpectoral space for future management of capsular contracture if required.

Vitiligo and the melanocyte reservoir

Repigmentation of vitiligo depends on available melanocytes from three possible sources: from the hair follicle unit which is the main provider of pigment cells, from the border of vitiligo lesions, and from unaffected melanocytes within depigmented areas; pigment cells at these locations originate a perifollicular, border spreading and a diffuse repigmentation pattern. In order for repigmentation to take place under stimulation with diverse therapies, melanocytes should be present in appropriate numbers. Melanocyte tissue stem cells located in the niche at the bulge region of the hair follicle are the most important sources for providing immature pigment cells that undergo terminal differentiation and originate repigmentation, but cytokines, UVR and other molecules acting in melanogenesis with adequate regulation mechanisms contribute to successful recovery in vitiligo. The presence of keratinocyte stem cells in the interfollicular epidermis raises the question on the possibility of melanocyte stem cells in a similar location and the development of future strategies for therapeutic purposes.

Dermatologia na pele negra

Este estudo aborda a dermatologia na pele negra. Inicialmente, discute os conceitos de raça e etnia, assim como os critérios de classificação da população brasileira, indicando as regiões em que a população negra se concentra. A seguir, faz breve explanação sobre os sistemas de classificação da cor da pele e descreve particularidades estruturais, biológicas e funcionais da epiderme, derme e anexos cutâneos que diferenciam as peles clara e escura. Posteriormente, mostra algumas alterações fisiológicas comumente observadas na pele, nas unhas e nas mucosas dos indivíduos negros. Aponta, também, alguns padrões de reações e modificações da cor das lesões, decorrentes da hiperpigmentação cutânea, que determinam aspectos inusitados às dermatoses, dificultando seu reconhecimento. Finalmente, destaca algumas doenças em especial, enfatizando particularidades inerentes ao padrão das lesões e à freqüência de algumas dermatoses na pele negra. Nesse contexto, a intenção foi fornecer dados para auxiliar o dermatologista a se familiarizar com as diferentes nuanças que as doenças podem adquirir na pele mais pigmentada.

Comparison between 308-nm monochromatic excimer light and narrowband UVB phototherapy (311-313 nm) in the treatment of vitiligo--a multicentre controlled study

BACKGROUND

Vitiligo is an acquired pigmentary disorder characterized by areas of depigmented skin resulting from loss of epidermal melanocytes. Recently, it has been shown that narrowband ultraviolet B (NB-UVB) phototherapy may be more effective than psoralen and ultraviolet A (PUVA) photochemotherapy in treating vitiligo, and that 308-nm monochromatic excimer light (MEL) may present some advantages as compared to NB-UVB for the treatment of vitiligo. AIM The aim of this study was to compare the effectiveness of NB-UVB phototherapy and 308-nm MEL in vitiligo patients.

METHODS

The study was done in a randomized, investigator-blinded and half-side comparison design. Twenty-one subjects with symmetrical vitiligo lesions were enrolled in this study. Vitiligo lesions on one body side were treated twice weekly for 6 months with 308-nm MEL, while NB-UVB phototherapy was used to treat lesions on the opposite side.

RESULTS

At the end of the study six lesions (37.5%) treated with 308-nm MEL and only one lesion (6%) treated with NB-UVB achieved an excellent repigmentation (score 4) while four lesions (25%) treated with 308-nm MEL and five lesions (31%) treated with NB-UVB showed a good repigmentation (score 3).

CONCLUSIONS

It appears that 308-nm MEL is more effective than NB-UVB in treating vitiligo lesions and it induces repigmentation more rapidly.

Effects of psoralen plus ultraviolet A irradiation on cultured epidermal cells in vitro and patients with vitiligo in vivo

BACKGROUND

Both psoralen plus ultraviolet (UV) A (PUVA) and narrowband UVB (NB-UVB) irradiation are effective treatments for vitiligo vulgaris. However, the mechanisms of PUVA and NB-UVB in repigmentation are not thoroughly clarified. Our previous results showed that NB-UVB irradiation directly promotes melanocyte (MC) migration and stimulates MC proliferation via keratinocytes (KCs).

OBJECTIVES

In the present study, we used NB-UVB as a reference for comparison to investigate the immediate effects of PUVA on MC proliferation and migration.

METHODS

Cultured MCs and KCs were treated with PUVA or irradiated with NB-UVB. The direct impact of PUVA treatment on MCs was assessed in terms of its effect on MC proliferation and migration. The indirect effect of PUVA treatment and NB-UVB irradiation on MC proliferation via KCs was also investigated. The activities of matrix metalloproteinase (MMP)-2 and MMP-9, known for their influence on cell migration, were evaluated in the PUVA-treated MC and KC supernatants. The concentrations of MC mitogens/growth factors in the PUVA-treated KC supernatants were also determined. In addition, the serum levels of MC mitogens/growth factors in healthy controls, in patients with active vitiligo and in patients with repigmenting vitiligo after PUVA treatment were determined to elucidate the mechanisms of how PUVA induces vitiligo repigmentation in vivo.

RESULTS

Our results demonstrated that PUVA treatment did not significantly stimulate the release of MC mitogens/growth factors from KCs. The migration of MCs was also not enhanced after PUVA treatment. The expression of MMP-2 activity in supernatants derived from PUVA-treated MCs was significantly increased as compared with the control group. However, neither MMP-2 nor MMP-9 activity in KC supernatants was stimulated by PUVA treatment. In contrast to NB-UVB, immediate effects of PUVA on MC proliferation and migration were not observed in this study. Sera from patients with repigmenting vitiligo after PUVA treatment contained higher levels of basic fibroblast growth factor, stem cell factor and hepatocyte growth factor as compared with healthy controls and patients with active vitiligo.

CONCLUSIONS

Our results indicate that in addition to immune suppression, PUVA treatment creates a favourable milieu for promoting the growth of MCs in patients with vitiligo instead of directly stimulating the regrowth of MCs. Based on our results, we propose that in the active stage of vitiligo, PUVA treatment is the therapy of choice to slow down the destruction of MCs and to create a favourable environment for MCs to survive. In the stable stage of vitiligo, NB-UVB irradiation should be used to stimulate the proliferation and migration of MCs directly.

Polarity Regulators and the Control of Epithelial Architecture, Cell Migration, and Tumorigenesis

A large body of work on Drosophila melanogaster has identified and characterized a number of key polarity regulators, many of which are required for the regulation of multiple other processes including proliferation, migration, invasion, and tumorigenesis. Humans possess either single or multiple homologues of each of the Drosophila polarity proteins, and in most cases, these are highly conserved between species, implying an important and conserved function for each of the polarity complexes. Recent studies in cultured mammalian epithelial cells have shed some light on the requirement for the polarity complexes in the regulation of epithelial cell function, including an unexpected link to the regulation of directed cell migration. However, many questions still remain regarding the molecular mechanisms of polarity regulation and whether disruption of polarity protein function is an important step in the development of human cancers. Here we will review what is currently understood about the regulation of cell polarity, migration, and invasion and the level of functional conservation between Drosophila and mammalian tissues. Particular reference will be made as to how the Scribble and Par polarity complexes may be involved in the regulation of apical-basal polarity, migration, and tumorigenesis.

Surgical approaches for stable vitiligo

BACKGROUND

Vitiligo therapy is difficult. Depending on its clinical presentation, unilateral or bilateral vitiligo lesions respond well with different repigmentation rates, according to age, affected anatomic area, extension of lesions, time at onset, timing of depigmentation spread, and other associated factors. When stable and refractory to medical treatment, vitiligo lesions may be treated by implanting pigment cells on depigmented areas.

OBJECTIVE

To describe the main events of depigmentation and the fundamentals of surgical techniques for repigmenting vitiligo by implanting noncultured cellular or tissue grafts, in vitro cultured epidermis-bearing pigment cells, or melanocyte suspensions.

METHODS

A description of the available techniques for repigmentation of vitiligo is done, emphasizing the most important details of each procedure to obtain the best repigmentation and minimize side effects.

RESULTS

With most of these techniques, adequate repigmentation is obtained, although there are limitations when applying some methods to clinical practice.

CONCLUSIONS

Restoration of pigmentation may be accomplished with all available surgical procedures in most anatomic locations, but they are of little value for acral areas. Unilateral vitiligo responds well in a high proportion of patients, and bilateral disease may also respond when stable. Appropriate patient selection is important to achieve the best results.

Narrow-band ultraviolet-B stimulates proliferation and migration of cultured melanocytes

Narrow-band ultraviolet-B (UVB) radiation is an effective treatment for vitiligo vulgaris. However, the mechanisms of narrow-band UVB in inducing repigmentation of vitiligo lesions are not thoroughly clarified. The purpose of our study was to investigate the effects of narrow-band UVB irradiation on melanocyte proliferation and migration in vitro. Our results showed that the cell counts as well as [3H]thymidine uptake of melanocytes were significantly enhanced by narrow-band UVB-irradiated keratinocyte supernatants. In these supernatants, a significant increase in basic fibroblast growth factor (bFGF) and in endothelin-1 (ET-1) release was observed. bFGF is a natural mitogen for melanocytes, whereas ET-1 can stimulate DNA synthesis in melanocytes. This stimulatory effect of melanocyte proliferation by supernatants derived from narrow-band UVB-irradiated keratinocytes was significantly reduced by a selective endothelin-B (ET-B) receptor antagonist (BQ788), suggesting an essential role of ET-1 on melanocyte proliferation. Our results of time-lapse microphotography revealed a stimulatory effect of narrow-band UVB irradiation on melanocyte migration. Focal adhesion kinase (FAK) plays a pivotal role in cell migration. Phosphorylated FAK (p125(FAK)) expression on melanocyte was enhanced by narrow-band UVB irradiation. In this study, narrow-band UVB irradiation stimulated a significant increase in matrix metalloproteinase-2 (MMP-2) activity in melanocyte supernatants. Narrow-band UVB-irradiation-induced migration of melanocytes was significantly annihilated by the addition of p125(FAK) inhibitor (herbimycin-A) or MMP-2 inhibitor (GM6001). These results suggest that p125(FAK) and MMP-2 activity play important roles in narrow-band UVB-induced migration of melanocytes. Our results provide a theoretical basis for the effectiveness of narrow-band UVB irradiation in treating vitiligo.

Heat shock protein 27 is expressed in normal and malignant human melanocytes in vivo

BACKGROUND

Heat shock proteins (HSPs) are a family of highly conserved proteins found ubiquitously in mammalian cells, believed to be regulators of normal cell physiology and the cellular stress response. In addition, the small 27-kDa heat shock protein (HSP27) has previously been found to be a differentiation marker for keratinocytes and a prognostic marker associated with increased survival in certain cancerous tumors.

METHODS

Using immunohistochemistry on routinely processed paraffin sections, we examined skin biopsies from 15 invasive melanomas, 13 intradermal nevi, and two compound nevi immunostained with a mouse monoclonal antibody to HSP27. In addition, cultured melanocytes were heat stressed at 45 degrees C for 1 h and then fixed and immunostained in order to localize HSP27 expression intracellularly.

RESULTS

We found cytoplasmic and strong perinuclear staining of HSP27 in melanocytes in normal skin, in melanomas, and in nevi. Nuclear reactivity was absent. In addition, in cultured non-malignant melanocytes, HSP27 expression relocated from the cytoplasm to the nucleus with heat stress.

CONCLUSIONS

To our knowledge, this investigation is the first to demonstrate that HSP27 is expressed in melanocytes in normal skin, in nevi, and in non-malignant cultured melanocytes.

Melanin pigmentation in mammalian skin and its hormonal regulation

Cutaneous melanin pigment plays a critical role in camouflage, mimicry, social communication, and protection against harmful effects of solar radiation. Melanogenesis is under complex regulatory control by multiple agents interacting via pathways activated by receptor-dependent and -independent mechanisms, in hormonal, auto-, para-, or intracrine fashion. Because of the multidirectional nature and heterogeneous character of the melanogenesis modifying agents, its controlling factors are not organized into simple linear sequences, but they interphase instead in a multidimensional network, with extensive functional overlapping with connections arranged both in series and in parallel. The most important positive regulator of melanogenesis is the MC1 receptor with its ligands melanocortins and ACTH, whereas among the negative regulators agouti protein stands out, determining intensity of melanogenesis and also the type of melanin synthesized. Within the context of the skin as a stress organ, melanogenic activity serves as a unique molecular sensor and transducer of noxious signals and as regulator of local homeostasis. In keeping with these multiple roles, melanogenesis is controlled by a highly structured system, active since early embryogenesis and capable of superselective functional regulation that may reach down to the cellular level represented by single melanocytes. Indeed, the significance of melanogenesis extends beyond the mere assignment of a color trait.

Pigmentary disorders in ethnic skin

Pigmentary disorders are commonly seen in ethnic skin. They are psychologically problematic in darker skin. Treatment of many of these disorders remains difficult.

Ethnic skin disorders overview

With the changing demographics of the US population, there is a need to understand the variety of dermatologic disorders that manifest in ethnic groups of non-Caucasian skin types. This article provides a review of presentations and current treatments of several common dermatologic diagnoses in black, Hispanic, and Asian racial groups and compares them with the presentations in Caucasian skin. The specific diagnoses discussed in the different racial groups include acne; pigmentary disorders such as postinflammatory hyperpigmentation and hypopigmentation, vitiligo, and melasma; and photoaging. Because the majority of the world's population already consists of people with pigmented skin and the population within the United States is approximately one-third non-Caucasian, physicians who practice in the field of dermatology today need a thorough understanding of non-Caucasian dermatoses.

Melanocytes do not migrate directionally in physiological DC electric fields

Wounding skin generates an endogenous electric field of 100-200 mV/mm in the immediate vicinity of the wound. When keratinocytes are exposed to direct current electric fields of this magnitude, they exhibit galvanotaxis, or directional migration toward the cathode, suggesting that wound-generated electric fields provide migrational cues that contribute to wound healing. Because melanocytes must also migrate into the healing wound to repigment it, their motility in response to electric fields of physiologic magnitude was examined. Human skin-derived melanocytes, either exposed to 100 mV/mm direct current electric fields or nonexposed controls, both exhibited motility rates of 9 micro m/hour, significantly (three- to five-fold) lower than the motility rates of keratinocytes under identical conditions. However, in sharp contrast to keratinocytes, melanocytes exhibited no directional migration in the electric field. Additionally, neither the number of primary dendrites per cell, nor the orientation of the dendrites with respect to the field vector, nor the average length of the dendrites was significantly different in melanocytes exposed to the electric field as compared to nonexposed controls. Thus, in marked contrast to keratinocytes, human skin-derived melanocytes do not respond to direct current electric fields of physiologic magnitude with either directional migration or reorientation of dendrites. This may account for the delay in repigmentation that often accompanies wound reepithelialization.

New and emerging therapies for vitiligo

Vitiligo is a common skin disease; however, it still remains a difficult disease to treat. Not all patients respond to current forms of treatment. There are several new treatments, surgical and nonsurgical, and immunologic, that appear to either have higher success rates than past therapies or have potential as future developments for therapy of vitiligo.

Horizontal and vertical pigment spread into surrounding piebald epidermis and hair follicles after suction blister epidermal grafting

Following the earlier description of Carnot and Deflandre in 1896, pigment spread phenomenon in mammals was investigated using immunogenetically marked melanocytes (Billingham and Silver, Quart. Rev. Biol. 1960 35: 1-40; Billingham and Silver, Ann. N.Y. Acad. Sci. 1963 100: 348-363). In spite of a number of similar studies on vitiligo lesions, detailed evaluation of pigment spread in piebald lesions has not been reported. To gain further insight into the pigment spread phenomenon in human skin, five piebald patients were studied, on whom suction blister epidermal grafting therapy onto piebald patches was performed. In the present study, pigmentation of all epidermal grafts from normally pigmented areas spread horizontally. It was also found that pre-existing white hairs in recipient sites became pigmented within 1 year after epidermal grafting. Immunofluorescence studies using melanocyte-specific antibody NKI/beteb revealed the newly induced presence of melanocytes in the newly pigmented hair follicles. Further, to study the possible mechanisms inhibiting melanocyte migration from normal skin into piebald lesions, epidermis was grafted from border zones (containing both normal and piebald skin) into the center of hypopigmented lesions. Melanocytes clearly migrated through the border zone of grafted epidermis into surrounding recipient hypopigmented sites.

Numbers and differentiation status of melanocytes in idiopathic guttate hypomelanosis

The etiology and pathogenesis of idiopathic guttate hypomelanosis (IGH) are largely unknown. To investigate whether the pathologic alteration in IGH involves changes in melanocytic differentiation, cell number, or both, we studied nine lesions of IGH by immunoperoxidase, using monoclonal antibodies against the KIT receptor and a panel of melanocyte differentiation antigens (tyrosinase-related protein-1, tyrosinase, and gp100/pme117). In each case, compared with grossly normal non-lesional skin, IGH lesions showed markedly reduced numbers both of KIT+ cells and of cells expressing melanocyte differentiation antigens (p < 0.0001). Double immunofluorescence labeling of lesions revealed only scattered cells with a less-differentiated phenotype, i.e. cells positive for KIT but having low or undetectable TRP-1. These results indicate that the pathogenesis of IGH involves an absolute decrease in the number of melanocytes; a block in melanocyte differentiation does not appear to be a major component of the process.

Vitiligo

The destruction of melanocytes is the cause of depigmented maculae that clinically represent the disease vitiligo. Although the cause is unknown, various theories such as the autoimmune, autocytotoxic, and neural hypotheses have been proposed. Extensive research has provided numerous answers regarding the pathogenesis, histopathologic evidence, and treatment of vitiligo. This discussion of vitiligo summarizes the varied clinical presentations of the disease, theories attempting to explain the mechanism of melanocyte destruction, histopathologic findings, and different treatment modalities currently available.

Comparison of migration and invasiveness of epithelial tumor and melanoma cells in vitro

Tumor invasion of basement membranes is a complex multi-step process. Altered adhesion, as well as increased cell locomotion contribute to tumor cell invasion and metastasis. A variety of in vitro models have been used to measure cell invasiveness. The invasion of basement membranes can be simulated in vitro in blind well Boyden Chambers using the reconstituted basement membrane matrigel or collagen type I as the invasion barrier. The aim of our study was to compare the migration and invasive capacity of epidermal tumor cells (TR 131, TR 146, SCL II, FaDu, HLaC 79) and melanoma cells derived from primary tumors (Mel Ei, Mel Ho, Mel Juso, Mel Wei) or their metastases (Mel Ju, Mel Im, Sk Mel 1, Sk Mel 28). Chemotactic response of epidermal tumor cells was increased toward fibroblast conditioned medium and fibronectin (20 micrograms/ml), while laminin (100 micrograms/ml) stimulated chemotaxis in only 3 epidermal tumor cell lines (HLaC 79, FaDu, TR 146), EGF (10 ng/ml) in only 4 cases (SCL II, FaDu, TR 131, TR 146), and interleukin-1 (IL-1) in only 1 case (FaDu). Epithelial tumor cell conditioned medium had no chemotactic influence on epithelial tumor cells. Fibroblast conditioned medium, fibronectin, EGF and PDGF were potent chemoattractants for all melanoma tumor cells, whereas IL-1 did not induce a significant chemotactic response. While two epithelial tumor cell lines (FaDu, TR 146) were able to penetrate collagen type I, matrigel was an impenetrable barrier for all epithelial tumor cells. Two cell lines from melanoma primary tumors (Mel Ho, Mel Ei) and two cell lines from melanoma metastases (Sk Mel 1, Sk Mel 28) showed no invasion through collagen type I and matrigel, whereas invasion through both barriers could be observed for the metastatic cell lines Mel Ju and Mel Im and in the primary tumor cell line Mel Wei. Therefore, the clinical observation of late and rare metastasis in epithelial tumors and early metastasis in melanoma correlate with our in vitro investigation of invasive behavior in tumor cells. No significant correlation between the invasiveness of melanoma cell lines and their clinical origin could be demonstrated suggesting the existence of subpopulations with varying invasive potential.

Keratinocyte extracellular matrix-mediated regulation of normal human melanocyte functions

Active roles of cell-cell interaction between melanocytes and neighboring keratinocytes for the regulation of melanocyte functions in the skin have been suggested. We examined substantial regulatory mechanisms of keratinocyte extracellular matrix (kECMs) for normal human melanocyte functions without direct cell-cell contact. We specially devised kECMs from proliferating or differentiating keratinocytes and further treated them with environmental stimulus ultraviolet B (UVB) for skin pigmentary system. Normal human melanocytes (NHM) were cultured on the various keratinocyte ECMs and initially the effects of the kECMs upon melanocyte morphology (dendrite formation and extension), growth, melanin production and expressions of pigmentation-associated protein (MEL-5) and proliferation-associated protein (proliferating cell nuclear antigen; PCNA/cyclin) were studied. Then we compared the effects of these cell-matrix interactions with those of direct melanocyte-keratinocyte, cell-cell contact in co-culture on melanocyte functions. Melanocytes cultured on any types of the kECMs that were tested significantly extended dendrites more than that on plastic cell culture dish without kECM (control). Melanocytes cultured on any types of the kECMs that were tested significantly extended dendrites more than that on plastic cell culture dish without kECM (control). Melanocytes cultured on the kECM prepared from UVB irradiated differentiating keratinocytes resulted in 219% increase in the number of dendrites. The growth of melanocytes on kECMs was also stimulated up to 280% of control. The kECM produced by proliferating keratinocytes had a more significant effect on the growth than kECM from differentiating keratinocytes. This melanocyte growth stimulating effect was decreased with kECM from UVB treated differentiating keratinocytes. The melanin content per melanocyte was constant on any of the kECMs.(ABSTRACT TRUNCATED AT 250 WORDS)

Melanocyte mitogens induce both melanocyte chemokinesis and chemotaxis

It is believed that during repigmentation of vitiligo, inactive melanocytes in the outer root sheath of the hair follicle become activated, proliferate, and migrate into the depigmented skin. However, the mechanisms controlling melanocyte migration remain to be elucidated. In this study, we investigated the effects of well-described melanocyte growth factors on melanocyte migration. Using time-lapse photography, we demonstrated that melanocyte chemokinetic movement was induced by basic fibroblast growth factor, stem cell factor, and endothelin-1, with the greatest effect noted using 100 nM endothelin-1. Similar results were reported previously with leukotriene C4. When surrounded by these stimuli, melanocytes moved in a random, nonlinear fashion and showed no desensitization at the concentrations studied. In Boyden chamber checkerboard analysis, basic fibroblast growth factor, leukotriene C4 and endothelin-1 were chemotactic. They produced directional migration and showed desensitization at higher concentrations. The greatest effect again was seen with 100 nM endothelin-1. Stem cell factor showed no effect in this assay system at the concentrations tested. The four melanocyte mitogens--leukotriene C4, endothelin-1, basic fibroblast growth factor, and stem cell factor--stimulate melanocyte migration, and this migration may be either chemokinetic (activated random movement) or chemotactic (requiring a gradient, directional, and showing desensitization), depending on the conditions used. We believe that these factors may be effective in stimulating vitiligo repigmentation by inducing proliferation and migration of hair-follicle outer-root-sheath melanocytes into the depigmented epidermis.

Quantitative assessment of melanoma single-cell motility in vitro

Cell motility is a crucial property of tumor cells during invasion and metastasis. In this study we developed a computer assisted system to measure translocation and stationary motility of single cells and used this procedure to evaluate the influence of cytochalasin A (CA) on single-cell motility parameters of K1735-M2 mouse melanoma cells. The cells were seeded at low density into a microincubator. Time lapse microcinematography was performed every 20 seconds from a high power field to assess stationary motility and every 10 minutes with a screening objective to measure translocation. 1 muMol CA was added to the medium 48 hours before measurement. Calculation of stationary motility was performed by subtraction of subsequent images and the resulting image difference was used for quantitative evaluation. Three different measuring windows were drawn to discriminate between membrane ruffling, intracellular organelle transport and overall stationary motility. For each cell we measured change of density (CD), area of change (AC), perimeter of area of change (PC), area of ruffling (AR), number of ruffling sites (NR), change of intracellular organelles (CIO) and number of changing intracellular organelles (NIO). In order to quantify translocation, the center of gravity of each cell was assessed subsequently and the velocity was calculated by connecting the centers of gravity. CA-treated cells showed a significantly lower stationary motility and membrane ruffling compared to the untreated cells (U-test: p < = 0.01), but there was not significant difference concerning the intracellular organelle transport.(ABSTRACT TRUNCATED AT 250 WORDS)

Organotypic culture of human skin to study melanocyte migration

An ex vivo model system was developed to investigate melanocyte migration. Within this model system, melanocytes migrate among other epidermal cells in the epibolic outgrowth of skin explants. This process is initiated by loss of contact inhibition of epidermal cells at the rim of the explants and by locally produced chemotactic factors. Punch biopsies provided explants of reproducible diameter. Optimal culture conditions include medium consisting of Dulbecco's Minimal Essential Medium containing 10% inactivated normal human serum and placement of explants epidermal side up at the air-liquid interphase. Within 7 days, epidermal cells completely surround the explant. Approximately 3 days after the onset of keratinocyte migration, melanocytes distribute themselves within the newly formed epidermis. Throughout the 7-day culture period, melanocytes and keratinocytes show maintenance of subcellular morphology, and the dermo-epidermal junction remains intact. Melanocyte migration was quantified using immunoperoxidase staining in combination with light microscopy and computer-aided image analysis. Preliminary results using the model system to compare migration in control and nonlesional vitiligo skin indicate that no inherent migration defect is responsible for impaired repigmentation of vitiligo lesions. The organotypic culture model system allows for investigations on melanocytes within their environment of autologous epidermal and dermal components, closely resembling in vivo circumstances in human skin.

Modulation of normal human melanocyte dendricity by growth-promoting agents

Dendrite formation and extension, which comprise a characteristic morphology of human normal melanocytes in the skin, represent one of the functional activities of melanocytes, the ability to transfer melanosomes into neighboring keratinocytes. However, the morphology of the melanocyte in vitro is usually quite different from that observed in vivo. it is probably due to the hyperproliferative condition of the melanocytes in culture. No studies have ever compared the effects of a single factor on both dendricity and proliferation at the same time. Therefore, we have compared the effects of six growth-promoting agents commonly used for melanocyte cultures on dendrite formation and proliferation. The addition of agents that increase the intracellular levels of cyclic adenosine monophosphate (cAMP)--dibutyryl cyclic adenosine monophosphate (db cAMP; 1 mM) or isobutylmethyl xanthine (IBMX; 0.1 mM)--had a strong effect on dendrite formation and a negative effect on proliferation. This was especially true with db cAMP. In the presence of 2% or 5% of heat-inactivated fetal bovine serum (FBS), dendrite formation was significantly increased as was proliferation. The number of dendrites was decreased in the culture with 12-o-tetradecanoylphorbol-13-acetate (TPA), but cell growth was slightly increased. With human recombinant basic fibroblast growth factor (bFGF) (0.5, 1.0 ng/ml) in the presence of bovine pituitary extract (BPE) (60 micrograms/ml), cell growth was increased. With 2 ng/ml of bFGF, however, a strong inhibitory effect on proliferation was observed. However, dendrite formation was constant at all concentrations of bFGF tested (0.5, 1.0 or 2.0 ng/ml) with BPE (30 or 60 micrograms/ml). In this study, we have demonstrated that dendrite formation was suppressed by the reagents that stimulate melanocyte proliferation, and vice versa, with the only exception being heat-inactivated FBS. Both dendrite formation and proliferation were induced by the heat-inactivated FBS. This approach is crucial to the development of an adequate culture system for proliferation and/or dendrite formation of normal human melanocytes. It is necessary to keep these aspects in mind as we further investigate the biology of melanocytes, especially the cell-to-cell interactions between melanocytes and keratinocytes, involved in melanogenesis and melanin pigmentation in vivo. This study also provides practical and important information for a future reconstitutive skin system composed of melanocytes, keratinocytes, and fibroblasts in a single culture medium.

Melanocyte movement in vitro: role of matrix proteins and integrin receptors

During the repigmentation of vitiliginous skin, melanocytes migrate from the outer root sheath of the hair follicle into the depigmented skin. We hypothesize that this requires changes in the local microenvironment that are conductive to melanocyte migration. One important change in the microenvironment could be the localized production of matrix proteins. We have previously employed time-lapse photography to evaluate the effect of inflammatory mediators and cytokines on melanocyte movement. We have adapted this system to study the effect of matrix proteins on melanocyte movement in vitro. Type IV collagen significantly increases melanocyte migration, whereas laminin and fibronectin have no effect. Cell/matrix interactions are in part controlled by cell-surface integrins. Integrins have been demonstrated to be important in controlling the migration of many cell types. We demonstrate that melanocytes express cell-membrane alpha 2, alpha 3, and alpha 5 integrins and that the enhanced melanocyte migration on type IV collagen is inhibited by specific function-blocking antibodies to integrins alpha 2 and alpha 3, but not to alpha 5 integrins.

Review of the etiopathomechanism of vitiligo: a convergence theory

Vitiligo is an acquired melanin pigmentary disorder manifesting itself by expanding depigmented lesions of the skin. To date, the etiopathomechanism of vitiligo has not been convincingly elucidated and a number of seemingly mutually opposed hypotheses with equal likelihood still coexist. Concurrent theories on vitiligo etiology, together with supportive evidence, are reviewed here. Due to the observed variation in clinical manifestations of the disease, it seems likely that the etiology of vitiligo may differ among patients. Therefore several theories on vitiligo etiopathogenesis have been combined to formulate a convergence theory for vitiligo, also presented in this article. This theory states that stress, accumulation of toxic compounds, infection, autoimmunity, mutations, altered cellular environment and impaired melanocyte migration and/or proliferation can all contribute to vitiligo etiopathogenesis in varying proportions.