FK506 increases pigmentation and migration of human melanocytes

Post-Inflammatory Hypopigmentation: Review of the Etiology, Clinical Manifestations, and Treatment Options

Post-inflammatory hypopigmentation is a common acquired pigmentary disorder that is more prominent in skin of color, leading to great cosmetic and psychosocial implications. Often, a diagnosis with a pigmentary disorder can negatively impact an individual's health-related quality of life and may result in stigma. Although most cases of post-inflammatory hypopigmentation resolve spontaneously over time, a systematic diagnostic approach can help with identifying the underlying etiology and informing treatment strategies. It can be due to cutaneous inflammation, sequelae of inflammatory or infectious dermatoses, or dermatologic procedures. Therefore, a thorough understanding of the epidemiology, patient history, physical exam findings, and clinical features of post-inflammatory hypopigmentation phenomenon can explain the primary cause to providers and allow for patient education. It is also important to understand the various therapeutic approaches available and the efficacy of these options, which will inform providers to choose the appropriate therapy for patients. Although algorithms exist for classifying acquired disorders of hypopigmentation, there are no established algorithms for the diagnosis and treatment of post-inflammatory hypopigmentation, which warrants further exploration and discourse.

Microneedling combined with pimecrolimus, 5-fluorouracil and trichloroacetic acid in the treatment of vitiligo: A comparative study

BACKGROUND

Treatment of vitiligo represents a highly therapeutic challenge in spite of the continuous development of new modalities. Combination therapies of vitiligo can help improve treatment response, and reduce recurrence potential.

OBJECTIVE

To compare the efficacy and adverse effects of microneedling combined with 5-fluorouracil, pimecrolimus, and TCA in the treatment of localized, stable vitiligo.

METHODS

The study included 75 patients with non-segmental, stable vitiligo who were randomly assigned to three equal groups: group 1 received a combination of microneedling and 5-FU, group 2 received microneedling and pimecrolimus, and group 3 received microneedling and TCA. The procedure was done every 2 weeks for a maximum of 6 sessions.

RESULTS

Combined microneedling and TCA was associated with the highest degree of repigmentation followed by combined microneedling + 5-fluorouracil, and lastly combined microneedling + pimecrolimus. The difference between the three groups was statistically significant in favor of the combined microneedling and TCA. Pain, erythema, post-inflammatory hyperpigmentation, infection, and scarring were variably reported adverse effects in the 3 groups.

CONCLUSION

Combination therapy seems to be a promising modality for the treatment of vitiligo. Combined microneedling and TCA is superior to combined microneedling with either 5-fluorouracil or pimecrolimus.

Odyssey toward an understanding of acquired postinflammatory lentiginosis

PURPOSE OF REVIEW

Acquired postinflammatory lentiginosis is a phenomenon that has been previously termed 'induction of lentiginosis in assorted dermatoses' or the ILIAD phenomenon.

RECENT FINDINGS

Although some cases have been described as arising exclusively in those who applied topical calcineurin inhibitors (TCIs), other patients have presented with similar findings in other nonatopic disorders (contact dermatitis, psoriasis, lichen planus, focal dermal hypoplasia), and without antecedent use of TCIs.

SUMMARY

Inflammatory skin disorders can produce localized areas of cutaneous lentiginosis, particularly as the inflammation retreats in response to treatment. This post-inflammatory lentiginosis or ILIAD phenomenon may be potentiated by use of topical and systemic anti-inflammatory medications, including TCIs, topical corticosteroids, methotrexate, and systemic biologic agents. Although this phenomenon has not been associated with melanocytic neoplasia, ongoing periodic monitoring for dysplastic changes is reasonable.

Idiopathic guttate hypomelanosis: Presentation and Management

Idiopathic guttate hypomelanosis (IGH) is a benign, typically asymptomatic, acquired leukoderma characteristically affecting mature individuals. Although the etiopathogenesis is unclear, chronic sun exposure and senile degeneration are important triggers. Researchers have been engaged in a continuous effort to unveil the gray areas encompassing different aspects of IGH pathogenesis. IGH is a clinical diagnosis; however, histopathology and dermoscopy may aid in quetionable cases. Patients often seek cosmetic treatment. There has been no standard therapy for this condition. Newer treatment modalities range from topical agents to procedure-based therapies and have enhanced the therapeutic armamentarium. Here we discuss the pathogenesis, presentation, and management of IGH.

Tacrolimus (FK506) ointment combined with Nb-UVB could activate both hair follicle (HF) and dermal melanocyte precursors in vitiligo: the first histopathological and clinical study

Topical Tacrolimus, especially when combined with Nb-UVB, has been proven clinically to be effective in the treatment of vitiligo. However, no histological study has evaluated the repigmentation mechanism of tacrolimus ointment in combination therapy with Nb-UVB. In this study, the histological findings in patients receiving Nb-UVB were compared with those receiving topical tacrolimus combined with Nb-UVB. Twenty patients were recruited and received Nb-UVB treatment. The first ten patients were selected for the combination therapy and instructed to apply tacrolimus 0.1% ointment twice daily on the specified lesion of interest. The remaining ten patients did not receive any other topical treatments. Skin biopsy was performed at baseline from the depigmented area and 2-3 months post-treatment from the repigmented area. Biopsy specimens were stained with haematoxylin-eosin-safran (HES), Fontana Masson, HMB45, Melan A, MITF, SOX10 and Nestin. Clinically, in the combination therapy group, interfollicular repigmentation in addition to the perifollicular and marginal pattern was observed. Histologically, in the combination therapy group, besides the migration of melanocytes from the bulge of the hair follicle seen in the monotherapy group, for the first time, we observed dermal melanocyte precursors located in mid- and superficial dermis.

Treatment Strategies for Hypopigmentation in the Context of Burn Hypertrophic Scars

Dyspigmentation in burn scars can contribute to the development of psychosocial complications after injury and can be detrimental to social reintegration and quality of life for burn survivors. Although treatments for skin lightening to treat hyperpigmentation have been well reviewed in the literature, skin-darkening strategies to treat hypopigmentation have not. The following potential treatment options in the context of burn hypertrophic scar will be discussed: use of the melanocyte-keratinocyte transplantation procedure, use of ectopic synthetic analogues of alpha-melanocyte stimulating hormone to initiate melanogenesis, and use of FK506 to induce melanogenesis. A proposed future direction of research in laser-assisted drug delivery of inducers of local melanin production, with the hope of developing a targeted, effective approach to dyspigmentation in hypertrophic scar is also discussed.

The early repigmentation pattern of vitiligo is related to the source of melanocytes and by the choice of therapy: a retrospective cohort study

BACKGROUND

Patients with vitiligo present with different repigmentation patterns in the early recovery stage.

OBJECTIVES

To analyze the relationships between early repigmentation patterns in vitiliginous patches, their clinical characteristics, and therapeutic choices.

METHODS

Patients with vitiligo seen in the Department of Dermatology, The First Affiliated Hospital of Nanjing Medical University from 2010 to 2015, were included, and their clinical records, especially photographs and medical treatments, were reviewed.

RESULTS

One hundred and sixteen patients were included in this study, and 326 lesions with different degrees of depigmentation, locations, stages, distributions, therapies, and repigmentation patterns were included and analyzed. Perifollicular repigmentation occurred more frequently in lesions with complete depigmentation (P = 0.005), in non-sun exposed areas (P < 0.001), a stable stage (P = 0.008), and lesions treated with narrow band ultraviolet B (NB-UVB) (P < 0.001, despite lesion distributions). Marginal repigmentation is more frequent in lesions with complete depigmentation (P = 0.016), lesions treated without NB-UVB (P = 0.002), and facial lesions treated with topical vitamin D analogs (TVDAs) monotherapy (P = 0.022). Diffuse repigmentation is the predominant pattern in lesions with incomplete depigmentation (P < 0.001), in sun-exposed areas (P < 0.001), progressive stage (P = 0.044), and truncal lesions treated with TVDAs (P < 0.001).

CONCLUSIONS

The different repigmentation patterns of vitiligo lesions depend on the different source and status of melanocytes and their abilities to produce melanin on the choice of therapy.

Pimecrolimus increases the melanogenesis and migration of melanocytes in vitro

Vitiligo is an intriguing depigmentary disorder and is notoriously difficult to be treated. The ultimate goal of vitiligo treatment is to replenish the lost melanocytes by immigration from hair follicle and to restore the normal function of melanogenesis by residual melanocytes. There are two types of topical calcineurin inhibitors called tacrolimus and pimecrolimus, and are recommended as the first-line treatments in vitiligo. Although pimecrolimus is efficacious for the repigmentation of vitiligo, its intrinsic mechanisms have never been investigated in vitro. This research aimed to study the ability of pimecrolimus on stimulating melanogenesis, melanocyte migration and MITF (microphthalmia associated transcription factor) protein expression. Results showed that pimecrolimus at the dosages of 1, 10, 10² nM were neither mitogenic nor cytotoxic to melanocytes. The addition of pimecrolimus at 10, 10² and 10³ nM significantly increased intracellular tyrosinase activity, which was consistent with the elevated content of melanin content at the same concentrations. The peak effect was seen at 72 h in response to 10² nM pimecrolimus. Results of the wound scratch assay and Transwell assays indicate that pimecrolimus is effective in facilitating melanocyte migration on a collagen IV-coated surface. In addition, MITF protein yield reached the highest by pimecrolimus at 10² nM. In brief, pimecrolimus enhances melanin synthesis as well as promotes migration of melanocytes directly, possibly via their effects on MITF protein expression.

Trends in Regenerative Medicine: Repigmentation in Vitiligo Through Melanocyte Stem Cell Mobilization

Vitiligo is the most frequent human pigmentary disorder, characterized by progressive autoimmune destruction of mature epidermal melanocytes. Of the current treatments offering partial and temporary relief, ultraviolet (UV) light is the most effective, coordinating an intricate network of keratinocyte and melanocyte factors that control numerous cellular and molecular signaling pathways. This UV-activated process is a classic example of regenerative medicine, inducing functional melanocyte stem cell populations in the hair follicle to divide, migrate, and differentiate into mature melanocytes that regenerate the epidermis through a complex process involving melanocytes and other cell lineages in the skin. Using an in-depth correlative analysis of multiple experimental and clinical data sets, we generated a modern molecular research platform that can be used as a working model for further research of vitiligo repigmentation. Our analysis emphasizes the active participation of defined molecular pathways that regulate the balance between stemness and differentiation states of melanocytes and keratinocytes: p53 and its downstream effectors controlling melanogenesis; Wnt/β-catenin with proliferative, migratory, and differentiation roles in different pigmentation systems; integrins, cadherins, tetraspanins, and metalloproteinases, with promigratory effects on melanocytes; TGF-β and its effector PAX3, which control differentiation. Our long-term goal is to design pharmacological compounds that can specifically activate melanocyte precursors in the hair follicle in order to obtain faster, better, and durable repigmentation.

Idiopathic Guttate Hypomelanosis: A Review of its Etiology, Pathogenesis, Findings, and Treatments

Idiopathic guttate hypomelanosis is a common acquired leukoderma characterized by multiple, discrete round or oval, porcelain-white macules on sun-exposed areas, especially on the extensor surface of forearms and pretibial areas. It usually affects individuals aged over 40 years and the likelihood of acquiring it increases with age. The exact pathogenesis remains controversial. However, there are several factors that are believed to be involved such as aging, ultraviolet exposure, trauma, genetic factors, autoimmunity, and local inhibition of melanogenesis. Despite the benign course of progression, many patients visit medical centers owing to cosmetic concerns and to confirm the natural course of idiopathic guttate hypomelanosis. Because there is no standard therapy for this condition, numerous medical and surgical treatments including intralesional corticosteroids, topical retinoids, topical calcineurin inhibitors, phenol peeling, cryotherapy, superficial dermabrasion, skin grafting, and ablative and non-ablative lasers have been tested with mixed results. This article will thoroughly review the etiology, pathogenesis, clinical presentations, histologic, dermoscopic, and ultrastructural findings, and the treatment of idiopathic guttate hypomelanosis.

FK506 positively regulates the migratory potential of melanocyte-derived cells by enhancing syndecan-2 expression

Although topical tacrolimus (FK506) is known to promote repigmentation by increasing the pigmentation and migration of melanocytes, the mechanism through which FK506 regulates cell migration remains unclear. Here, we report that FK506 treatment enhanced cell spreading on laminin-332 and increased migration in both melanocytes and melanoma cells. Interestingly, FK506 also increased the expression of syndecan-2, a transmembrane heparan sulfate proteoglycan through c-jun terminal kinase activation. Moreover, siRNA-mediated reduction of syndecan-2 expression decreased FK506-mediated cell spreading and migration in melanoma cells and decreased focal adhesion kinase phosphorylation in both melanocytes and melanoma cells. Consistent with these effects on syndecan-2 expression, FK506 enhanced the membrane and melanosome localizations of PKCβII, a regulator of tyrosinase activity. This suggests that FK506 may play a dual regulatory role by affecting both melanogenesis and migration in melanocyte-derived cells. Interestingly, however, FK506 failed to show any synergistic effect on the migration of UVB-treated melanocyte-derived cells. Taken together, these data indicate that FK506 regulates cell migration by enhancing syndecan-2 expression, further suggesting that syndecan-2 could be a potential target for the treatment of patients with vitiligo.

Pityriasis Alba--Common Disease, Enigmatic Entity: Up-to-Date Review of the Literature

Pityriasis alba (PA) is a skin disorder that affects children and adolescents. Although it is common worldwide, its incidence is markedly higher in darker skin phototypes. Its characteristic features include an extended, multistage course and spontaneous remissions and recurrences. Preceded by erythematous changes, patches of hypopigmented skin of up to a few centimeters in diameter appear on the upper body. Pruritus may accompany it. Even though its etiology is unknown, possible reported triggering factors include sunlight, beauty treatments, and microorganisms, among others. Calcineurin inhibitors play the most crucial role in PA pharmacotherapy. PA often coexists with atopic dermatitis and is considered one of its milder forms.

Combination therapy with 308-nm excimer laser, topical tacrolimus, and short-term systemic corticosteroids for segmental vitiligo: A retrospective study of 159 patients

BACKGROUND

Segmental vitiligo (SV) is characterized by a unilateral and localized distribution, early onset, and stable disease after rapid progression. And SV is often associated with poor response to various treatment modalities.

OBJECTIVE

We sought to evaluate the effectiveness of combination therapy with 308-nm excimer laser, topical tacrolimus, and short-term systemic corticosteroids for SV, and to search for factors associated with the treatment response.

METHODS

A retrospective interventional case-series study was performed on 159 patients with SV who were treated with the combination therapy for more than 3 months.

RESULTS

The rate of 75% or more repigmentation was 50.3% after a median treatment duration of 12.1 months; 36.5% and 13.8% of the patients showed nearly complete (75%-99%) and complete (100%) repigmentation, respectively. Multivariable analysis showed the following to be independent factors with poor response: disease duration longer than 12 months (odds ratio 0.372, 95% confidence interval 0.157-0.882, P = .025), poliosis (odds ratio 0.494, 95% confidence interval 0.247-0.988, P = .046), and plurisegmental subtype (odds ratio 0.175, 95% confidence interval 0.065-0.474, P = .001).

LIMITATIONS

This was a retrospective study.

CONCLUSION

The combination therapy is effective for SV. Prolonged disease duration, poliosis, and plurisegmental subtype were shown to be independent prognostic factors of poor response in patients with SV.

Hyperpigmentation in photo exposed patches of vitiligo following tacrolimus therapy

Vitiligo is an acquired pigmentary disorder, clinically characterized by depigmented macules caused by destruction of melanocytes in the affected skin. Half of all patients develop the disease in childhood and adolescence before the age of 20 years, making vitiligo an important skin disease of childhood. There are numerous studies in the literature that suggest the efficacy of topical tacrolimus in vitiligo, without serious adverse effects. We describe a case of vitiligo in a pediatric patient who developed hyperpigmentation in the periorbital lesions of vitiligo with the use of topical tacrolimus. To the best of our knowledge, this is only the second such reported occurrence in a patient with vitiligo.

Treatment of melasma in Caucasian patients using a novel 694-nm Q-switched ruby fractional laser

Background

Melasma is a common hypermelanosis of the face. The use of a classical Q-switched ruby laser (QSRL) to treat melasma is discussed controversially and is associated with frequent adverse effects, such as hyper- or hypopigmentation. Recently a fractional-mode (FRx) QSRL was developed to minimize the adverse effects of classical QSRL. The objective of this research was to evaluate the efficacy and safety of a novel FRx-QSRL in the treatment of melasma in Caucasian patients.

Methods

We performed a retrospective study of 25 Caucasian melasma patients (Fitzpatrick skin types I to III). Patients received one to three FRx-QSRL treatments (Tattoostar FRx, Asclepion Laser Technologies, Jena, Germany) at pulse energies of 4 to 8 J/cm². Three blinded investigators independently evaluated the melasma area and severity index (MASI) score before treatment and at the four- to six-week follow-ups. At additional three-month follow-ups, patients evaluated subjective improvement, pain and over-all satisfaction with the treatment according to a numeric analogue score (NAS). Side effects were documented.

Results

At four to six weeks post laser treatment for a mean of 1.4 sessions, we observed a significant (P = 0.0001) reduction of the MASI score from 6.54 to 1.98 (72.3%). Patients rated the pain of the intervention at a mean 2.46 points (0 = no pain; 10 = maximum pain), the improvement at a mean 5.55 points (0 = no improvement; 10 = maximum improvement) and the overall satisfaction at a mean 4.66 points (0 = not satisfied; 10 = maximum satisfaction). After three months, post-inflammatory hyperpigmentation (PIH) and/or recurring melasma were observed in 7 (28%) and 11 (44%) patients, respectively.

Conclusion

The 694-nm FRx-QSRL is a safe and effective option for treating melasma in Caucasian patients. Over periods of >3 months, PIH and/or recurring melasma may develop at significant rates and may reduce patient satisfaction. Multiple treatment sessions with lower pulse energies and/or a post-interventional therapy with hypopigmenting ointments and UV protection may help to minimize these complications.

A pilot study of 1% pimecrolimus cream for the treatment of childhood segmental vitiligo

Background

There is as yet no effective and safe treatment for vitiligo. One percent pimecrolimus cream, a topical calcineurin inhibitor, has been tried for the treatment of vitiligo, with its therapeutic efficacy having mostly been reported in non-segmental vitiligo. However, questions about the therapeutic efficacy of 1% pimecrolimus cream have remained unanswered regarding segmental vitiligo.

Objective

The aim of this study was to study the therapeutic efficacy and safety of 1% pimecrolimus cream for segmental childhood vitiligo.

Methods

Nine childhood patients with segmental vitiligo were treated with 1% pimecrolimus cream twice daily for three months, after which good responders were scheduled to continue with the 1% pimecrolimus cream monotherapy. The efficacy and safety of this treatment were determined by the levels of repigmentation, initial response time and the presence of adverse events including burning, dryness, stinging and itching.

Results

Four of nine patients achieved mild to moderate responses after three months of treatment and thus continued with treatment. Among these four patients, three achieved an excellent response and one patient achieved a moderate response, with a mean treatment duration of 7.3 months. Transient local burning sensation was the most common adverse event. In comparison with the patients with poor response, those patients with good response showed a shorter disease duration (8.5±10.5 mo vs. 13.4±10.1 mo), more frequent facial involvement (4/4 patients vs. 3/5 patients) and earlier initial response after treatment (1.0±0.0 mo vs. 2.0±1.0 mo).

Conclusion

This study suggests that 1% pimecrolimus cream is an effective and well-tolerated treatment for segmental childhood vitiligo.

CXCR7 mediates SDF1-induced melanocyte migration

Melanoblasts are derived from the neural crest and migrate to the dermal/epidermal border of skin and hair bulges. Although melanoblast migration during embryogenesis has been well investigated, there are only a few reports regarding the migration of mature melanocytes. Here, we demonstrate that a chemokine, stromal-derived factor-1 (SDF1, also known as CXCL12), and one of its receptor CXCR7 regulate normal human epidermal melanocyte (NHEM) migration. We found that SDF1 induces the directional migration of NHEMs. Interestingly, although both CXCR4 and CXCR7 are expressed in NHEMs, blockade of CXCR4 using a CXCR4-specific neutralizing antibody did not exert any influence on the SDF1-induced migration of NHEMs, whereas blockade of CXCR7 using a CXCR7-specific neutralizing antibody did influence migration. Furthermore, SDF1-induced NHEMs migration exhibited the early hallmark events of CXCR7 signaling associated with MAP kinase activation. It is known that the phosphorylation of ERK through CXCR7 signaling is mediated by β-arrestins. The treatment of NHEMs with SDF1 resulted in the phosphorylation of ERK in a β-arrestin 2-dependent manner. These results suggest that melanocytes may have a unique mechanism of migration via SDF1/CXCR7 signaling that is different from that of other cell types.

The effect of fractional carbon dioxide lasers on idiopathic guttate hypomelanosis: a preliminary study

BACKGROUND

Idiopathic guttate hypomelanosis (IGH) is a commonly acquired leucoderma that is characterized by discrete, round or oval porcelain-white macules ∼2-5 mm in diameter that increases in number with age. A variety of therapies with variable success rates, including cryotherapy, superficial abrasion and topical retinoids are currently being used.

OBJECTIVES

The effects of fractional CO(2) laser therapy on IGH were investigated in this pilot study.

PATIENTS AND METHODS

A total of 40 patients with IGH were enrolled. The hypopigmented lesions were treated using a 10 600-nm carbon dioxide fractional laser (CO(2) FL). Two months after a single treatment, physicians' clinical assessments were performed and the patients' overall satisfaction was evaluated.

RESULTS

The mean age of enrolled patients was 57.5 ± 10.9 years and the gender ratio was 7 : 33. The face was the most commonly treated area, although the extremities are epidemiologically the most frequently affected areas. Two months after treatment, objective assessments performed by two independent dermatologists indicated more than 50% improvement in 36 patients (90%), compared with baseline. In addition, 33 patients (82.5%) were very satisfied or satisfied with just one session of CO(2) FL treatment. Although a few patients complained of long-standing erythema and postinflammatory hyperpigmentation, these problems spontaneously resolved within 2 months after the assessments. No other noticeable side effects were observed.

CONCLUSION

CO(2) FL might be a very convenient and effective modality for treating IGH without significant side effects.

Double-blind, placebo-controlled, randomized study comparing 0.0003% calcitriol with 0.1% tacrolimus ointments for the treatment of endemic pityriasis alba

Background. Pityriasis alba (PA) is a frequent cause of consultation in tropical areas due to its chronic course, frequent relapses, and notorious hypopigmented lesions in pediatric dark skin populations. Currently, no treatment is widely accepted. Objective. To assess the efficacy of 0.0003% calcitriol and 0.1% tacrolimus ointments compared with placebo in the treatment of endemic PA. Methods. Twenty-eight children aged 3–17 years with 56 symmetrical lesions and phototype IV-V, were randomly assigned to receive the treatments on target lesions on the face. Improvement was evaluated at baseline and 8 weeks later clinically and by digital quantification of the affected area, colorimetry, and transepidermal water loss (TEWL). Results. Tacrolimus and calcitriol ointments induced a mean improvement of 68%, compared to 44% of placebo. We found an elevated TEWL in PA lesions. In the treated plaques, the reduction of the affected area was associated with improvement of pigmentation and TEWL. Conclusions. Calcitriol and tacrolimus induced similar repigmentation in endemic PA lesions. Melanogenic, anti-inflammatory, and barrier defect restoration properties of these drugs may explain these findings.

Endothelin-1 enhances the proliferation of normal human melanocytes in a paradoxical manner from the TNF-α-inhibited condition, but tacrolimus promotes exclusively the cellular migration without proliferation: a proposed action mechanism for combination therapy of phototherapy and topical tacrolimus in vitiligo treatment

BACKGROUND

Vitiligo is an acquired pigmentary disorder caused by the destruction of melanocytes. Two of the major theories regarding the pathogenesis of vitiligo are the autoimmune theory and autocytotoxicity theory, but, the precise pathogenetic mechanism is still not clarified.

OBJECTIVES

We investigated the effects of ET-1, tacrolimus and tumour necrosis factor-α (TNF-α) on proliferation and migration of cultured normal human melanocytes (NHMs). We also sought to clarify the theoretical rationale underlying the topical tacrolimus monotherapy or tacrolimus-UV combination therapy as tools for vitiligo treatment.

METHODS

The effects of ET-1, tacrolimus and TNF-α on proliferation/migration of cultured NHMs were investigated by MTT assay/Boyden chamber transwell migration assay. We also examined roles of CXC-chemokine receptor II (CXCR II) and matrix metalloproteinases (MMPs) in such conditions.

RESULTS

ET-1 exerted a stimulatory effect on melanocyte proliferation and migration, but, tacrolimus exerted a stimulatory effect only on melanocyte migration higher than ET-1. TNF-α inhibited melanocyte proliferation in a dose-dependent manner. Paradoxically, TNF-α-pretreated NHMs exhibited an enhanced proliferative efficiency after being switched to ET-1. We found CXCRII was highly expressed in TNF-α-incubated melanocytes than the agents-free control, and ET-1 treatment after TNF-α preincubation showed the higher levels of CXCRII expression than the condition incubated with TNF-α alone. Moreover, the greater activities of MMP-2 and MMP-9 induced by tacrolimus than ET-1, reflected tacrolimus would enhance migration stimulatory effect in cultured NHMs.

CONCLUSIONS

Topical tacrolimus can be used an effective agent for vitiligo treatment as monotherapy, maybe due to its migration stimulatory action or TNF-α inhibitory property, and also as a component in combination therapy with UV treatment, considering the more upregulated MMPs activities are induced and the more effective migrations are feasible by itself than ET-1.

Topical tacrolimus significantly promotes repigmentation in idiopathic guttate hypomelanosis: a double-blind, randomized, placebo-controlled study

BACKGROUND

Idiopathic guttate hypomelanosis (IGH) is an idiopathic disorder affecting a large number of people. Effective treatments are not yet available. Objectives To investigate the efficacy of topical 0.1% tacrolimus ointment compared with placebo in the treatment of IGH.

MATERIALS AND METHODS

Twenty-six patients were included in the study. Lesions on one side of the body were selected to have a treatment with 0.1% tacrolimus ointment, whereas those on the other side served as a control with placebo ointment that had the same physical appearance. Colorimeter was used to assess skin colour at baseline and at 1, 2, 3, 4 and 6 months of treatment.

RESULTS

Mean luminosity scale after adjusted for baseline from the treated side gradually decreased and reached statistical significance compared with the control group after 6 months of treatment (P = 0.019). Physicians' improvement grading score showed that 11% of the patients demonstrated improvement of their skin lesions on the treated side after 6 months' treatment.

CONCLUSION

Topical 0.1% tacrolimus ointment appeared to be an effective and safe treatment for IGH. The improvements were best observed by colorimetry, yet, they were not statistically significant upon clinical assessments.

Tacrolimus 0,1% ointment in the treatment of vitiligo: a series of cases

Vitiligo is a dermatosis of difficult treatment and significant psychosocial impact. The objective of this study was to evaluate the response to tacrolimus 0,1% ointment for vitiligo treatment. Ten patients took part in the present study: six patients with lesions on the cephalic and cervical regions had more than 75% of repigmentation. As for extremities and trunk results varied from good to excellent in 27% of the cases. The association with other therapeutic options could possibly increase the efficacy of the treatment.

FK506 (tacrolimus) and endothelin combined treatment induces mobility of melanoblasts: new insights into follicular vitiligo repigmentation induced by topical tacrolimus on sun-exposed skin

BACKGROUND

Topical tacrolimus (FK506) has been considered as a treatment option for treating vitiligo, a dermatosis characterized by disappearance of melanocytes (MCs). Previous reports have shown that a significant portion of treated patients demonstrated follicular repigmentation, indicating that the activation of MC precursor cells residing in the outer root sheath of hair follicles played an important role during the tacrolimus-induced repigmentation process.

OBJECTIVES

To investigate the mechanisms involved in follicular pigmentation induced by topical tacrolimus.

METHODS

As stem cells of MC lineage are identified in the lower portion of mouse hair follicles throughout the hair cycle, immature mouse melanoblasts (MBs) derived from neural crest cells (NCCmelb4) were used for this study. Relevant maturation parameters were evaluated.

RESULTS

Our results revealed that FK506 stimulated the expressions of protein kinase A, protein kinase C and phosphorylated p38 mitogen-activated protein kinase. However, cell motility, a parameter associated with MB differentiation, was not enhanced by FK506 treatment. Endothelin (ET)-3, a prodifferentiation factor of MBs, also failed to promote NCCmelb4 cell locomotion. Combining ET-3 and FK506, however, stimulated cell mobility. ET B receptor, which was not present in NCCmelb4 cells, was induced after FK506 treatment.

CONCLUSIONS

In summary, we have shown that FK506 is an efficient differentiation-stimulating agent, especially for cells of neural origin. The clinical efficacy of topical tacrolimus on vitiligo may be enhanced by combination with ET-3.

Immunosuppression and melanocyte proliferation

Melanocytes are pigmented cells derived from the neural crest; their proliferation is restrained by immune system. The eruption of nevi after an immunosuppressive condition is a peculiar phenomenon indicating that the immune system may play a major role in limiting proliferation of melanocytes. In this review, we analyze the role of immunosuppressive regimens on melanocyte proliferation. In particular, we discuss the eruptive nevi phenomenon, which is determined by the inability of the immune system to inhibit melanocyte proliferation. These clinical observations indicate that the immune system has a pivotal role in restraining melanocyte proliferation. However, although the role of the immune system in the development of nonmelanoma skin cancer has been shown clearly in several studies involving organ transplant patients, the role of immunosuppression in melanoma genesis has not yet been established. Further investigations are required to establish the real immunogenicity of melanoma, particularly in the light of the dichotomy between the eruptive nevi phenomenon in immunosuppressed patients and the low incidence of melanoma in transplanted patients.

Tacrolimus-induced hyperpigmentation in a patch of vitiligo

A 10-year-old boy had vitiligo vulgaris involving limited areas and was prescribed topical tacrolimus ointment (0.03%), as the lesions were present in the infraorbital area in addition to other areas including the arms, thighs, and around the knees and ankles. Within 2 months of starting treatment, he had evidence of diffuse repigmentation of all the patches of vitiligo. Two months later, all the lesions repigmented completely with excellent color matching except those in the infraorbital area. The parents were anxious due to brownish hyperpigmentation in the previous patch of vitiligo in infraorbital area (Figure). He had no irritation or burning sensation in the areas of application. There was no history of photosensitivity. The patient was applying tacrolimus once at night, and no photoprotection was advised. Due to location of the lesion in the infraorbital area, a cosmetically important site, the parents did not consent for punch biopsy. The hyperpigmentation was temporary, with reappearance of depigmentation within 1 month of discontinuing topical tacrolimus application.

Topical tacrolimus in combination with simulated solar radiation does not enhance photocarcinogenesis in hairless mice

Numerous studies have demonstrated the utility of topical tacrolimus ointment in atopic dermatitis. However, there is a concern that local immunosuppression by calcineurin inhibitors may enhance dermal photocarcinogenesis and carcinogenesis. Therefore, we investigated the influence of topical tacrolimus ointment on squamous cell carcinoma formation in hairless female C3.Cg/TifBomTac immunocompetent mice exposed to solar simulated radiation (SSR). In a first experiment, mice (n = 200) had tacrolimus applied on their dorsal skin three times weekly followed by SSR (2, 4 or 6 standard erythema doses, SED) 3-4 h later. Tacrolimus did not reduce the time to tumor development and in the group receiving 4 SED it even had a protective effect (156 days vs 170 days, P = 0.008). In a second experiment, mice (n = 50) were irradiated with 6 SED three times weekly for 3 months and subsequently treated five times weekly with topical tacrolimus to mimic the use of tacrolimus on sun-damaged skin. The median time to the first skin tumor was 234 days in SSR + tacrolimus group compared with 227 days in the only SSR-irradiated group (P = 0.160). In a third experiment, mice (n = 25) had tacrolimus applied on their dorsal skin every day for 1 month, thereafter the group was irradiated with 4 SED three times weekly. The median time to the first skin tumor was 142 days in tacrolimus + SSR group compared with 156 days in the only SSR-irradiated group from experiment 1 (P = 0.363). We conclude that tacrolimus ointment does not accelerate photocarcinogenesis or induce any dermal carcinogenicity in hairless mice.