Co-localization of inducible nitric oxide synthase and phosphorylated Akt in the lesional skins of patients with melasma

Different therapeutic approaches in melasma: advances and limitations

Melasma is a chronic hyperpigmentation skin disorder that is more common in the female gender. Although melasma is a multifactorial skin disorder, however, sun-exposure and genetic predisposition are considered as the main etiologic factors in melasma occurrence. Although numerous topical and systemic therapeutic agents and also non-pharmacologic procedural treatments have been considered in melasma management, however, the commonly available therapeutic options have several limitations including the lack of sufficient clinical effectiveness, risk of relapse, and high rate of unwanted adverse drug reactions. Recruitment of nanotechnology for topical drug delivery in melasma management can lead to enhanced skin penetration, targeted drug delivery to the site of action, longer deposition at the targeted area, and limit systemic absorption and therefore systemic availability and adverse drug reactions. In the current review, first of all, the etiology, pathophysiology, and severity classification of melasma have been considered. Then, various pharmacologic and procedural therapeutic options in melasma treatment have been discussed. Afterward, the usage of various types of nanoparticles for the purpose of topical drug delivery for melasma management was considered. In the end, numerous clinical studies and controlled clinical trials on the assessment of the effectiveness of these novel topical formulations in melasma management are summarized.

Best practices in the treatment of melasma with a focus on patients with skin of color

BACKGROUND

Melasma is a chronic hypermelanosis of the skin that affects approximately 1% of the global population, predominantly affects women, and is more prevalent in skin of color. Melasma is a common driver for patients with skin of color to seek out a dermatologist for treatment, and ensuring the right approach for these patients is important because some treatments may be associated with adverse side effects. Because of the chronicity of the disease and established psychosocial and emotional impacts, there is a large need to ensure care follows the best available evidence on the treatment of patients with melasma.

OBJECTIVE

Here, we summarized current available topical treatments for melasma with considerations dermatologists should have for their patients with skin of color.

METHODS

Steering committee consensus on clinical best practices.

RESULTS

We describe a flexible and focused treatment algorithm that reflects both treatment and maintenance periods that is a consensus of our extensive clinical experience.

LIMITATIONS

Use of real-world evidence and potential for individual practice bias.

CONCLUSION

Melasma can be challenging to treat, particularly in patients with skin of color, and our recommendations for best practices for patients in the United States are an important step toward standardizing care.

Expression of Endothelin-1, Endothelin Receptor-A, and Endothelin Receptor-B in facial melasma compared to adjacent skin

Background/Objectives

Although melasma is highly prevalent, its pathogenesis is not yet fully understood. In the skin, endothelin-1 (ET-1) is primarily produced by keratinocytes in response to UVB exposure, which is mediated by an increase in IL-1α or reactive oxygen species. ET-1 plays a role in melanogenesis by binding to specific receptor B (ERB) or receptor A (ERA). However, the expression of ET-1, ERA, and ERB in melasma has not been systematically investigated. The objective of this study was to evaluate the expression of ET-1, ERA, and ERB in facial melasma compared to the adjacent unaffected skin.

Methods

Cross-sectional study, with 40 skin samples (20: facial melasma; 20: adjacent unaffected skin) from women with facial melasma without treatment for 30 days except for sunscreen. A triple staining immunofluorescence technique was performed for anti-vimentin, DAPI, plus one of the following antibodies: (a) anti-ET1, (b) anti-ERA; (c) anti-ERB. Interfollicular areas on the slides of each topography (melasma; unaffected skin) were photographed in triplicate under confocal laser microscopy. The mean staining intensities of the image histograms (0-255 pixels intensity) were estimated for different types of cells (suprabasal keratinocytes, basal layer, and upper dermis) and were blindly compared between topographies.

Results

The mean (SD) age of the participants was 44.9 (9.2). The expression of ET-1 was increased in the whole epidermis with melasma when compared to the adjacent skin, being 32.8% (CI95% 14.7%-52.6%) higher in the spinous layer (p=0.013), 30.4% (CI95% 13.7%-47.9%) higher in the basal layer (p=0.014), and 29.7% (CI95% 11.4%-49.7%) higher in the melanocytes (p=0.006). There was no noticeable expression of ET-1 within the cells on the upper dermis. Neither ERA nor ERB resulted in differential epidermal expression between melasma and unaffected skin (p≥0.1).

Conclusion

ET-1 is expressed more intensely on the epidermis from the skin with facial melasma compared to the unaffected adjacent skin.

Update on Melasma-Part I: Pathogenesis

Melasma is a multifactorial dyschromia that results from exposure to external factors (such as solar radiation) and hormonal factors (such as sex hormones and pregnancy), as well as skin inflammation (such as contact dermatitis and esthetic procedures), in genetically predisposed individuals. Beyond hyperfunctional melanocytes, skin with melasma exhibits a series of structural and functional alterations in the epidermis, basement membrane, and upper dermis that interact to elicit and sustain a focal hypermelanogenic phenotype. Evolution in the knowledge of the genetic basis of melasma and the cutaneous response to solar radiation, as well as the roles of endocrine factors, antioxidant system, endothelium proliferation, fibroblast senescence, mast cell degranulation, autophagy deficits of the melanocyte, and the paracrine regulation of melanogenesis, will lead to the development of new treatments and preventive strategies. This review presents current knowledge on these aspects of the pathogenesis of melasma and discusses the effects of specific treatments and future research on these issues.

Implications of Oxidative Stress in the Pathogenesis and Treatment of Hyperpigmentation Disorders

Oxidative stress represents an imbalance between the generation of reactive oxygen and nitrogen species and the ability of antioxidant systems to decompose those products. Oxidative stress is implicated in the pathogenesis of hyperpigmentation, hypopigmentation, melanoma, and other skin diseases. Regulatory networks involving oxidative stress and related pathways are widely represented in hypopigmentation diseases, particularly vitiligo. However, there is no complete review into the role of oxidative stress in the pathogenesis of hyperpigmentation disorders, especially regarding associations involving oxidative stress and cellular signaling pathways. Here, we review oxidative and antioxidant systems, oxidative stress-induced signal transduction mechanisms, and effects of antioxidant drugs used in preclinical and clinical settings in hyperpigmentation disorders.

Treatment of melasma with a low-fluence 1064 nm Q-switched Nd:YAG laser: Laser toning in Caucasian women

BACKGROUND AND OBJECTIVES

Melasma is a common, therapeutically challenging, and very often relapsing disorder of hyperpigmentation most often observed in women. Low-fluence, multipass technique with Q-switched-mode laser-"laser toning" is broadly used to treat melasma, especially in Asia. The study aimed to evaluate the effects of a series of laser treatments with very short, nanosecond pulses in the treatment of melasma in Caucasian women.

MATERIAL AND METHODS

Forty polish females with Fitzpatrick skin phototype II-III and melasma were treated with 1064 nm Q-switched neodymium:yttrium-aluminum-garnet (QSNY) laser (pulse with 5 ns; spot size, 6-8 mm; fluence, 1.7-3.2 J/cm² ; 2-8 passes; nine treatments). Melanin index (MI), erythema index (EI) by Mexameter MX18®, the modified Melasma Area Severity Index (mMASI), and the participant's self-assessment were used to evaluate the treatment results. Twenty-one patients were subjected to a 1-year follow-up.

RESULTS

Significant improvement in melasma pigmentation was observed in the mean MI and mMASI score; both were significantly reduced (p < 0.0001). Significant erythema reduction was achieved (p < 0.001). In total, 70% of participants rated the laser as a method that met their expectations for treating melasma. Clinical follow-up after one year showed that the reduced melasma effect was still maintained. Patients also noticed improved skin conditions (radiance, smoothness, brightness, hydration, regeneration). No serious adverse effects were observed.

CONCLUSIONS

Low-fluence 1064 nm QSNY laser is an effective, safe, and noninvasive method with long-term results in melasma treatment. QSNY (1064 nm) improves the condition of melasma patients with erythema.

Alterations of the pigmentation system in the aging process

Human skin aging is a natural phenomenon that results from continuous exposure to intrinsic (time, genetic factors, hormones) as well as extrinsic factors (UV exposure, pollution, tobacco). In areas that are frequently exposed to the sun, photoaging blends with the process of intrinsic aging, resulting in an increased senescent cells number and consequently accelerating the aging process. The severity of photodamage depends on constitutional factors, including skin phototype (skin color, tanning capacity), intensity, and duration of sunlight/UV exposure. Aging affects nearly every aspect of cutaneous biology, including pigmentation. Clinically, the phenotype of age pigmented skin has a mottled, uneven color, primarily due to age spots, with or without hypopigmentation. Uneven pigmentation might be attributed to the hyperactivation of melanocytes, altered distribution of pigment, and turnover. In addition to direct damage to pigment-producing cells, photodamage alters the physiological crosstalk between keratinocytes, fibroblasts, endothelial cells, and melanocytes responsible for natural pigmentation homeostasis. Interestingly, age-independent diffuse expression of senescence-associated markers in the dermal and epidermal compartment is also associated with vitiligo, suggesting that premature senescence plays an important role in the pathology.

Participation of keratinocyte- and fibroblast-derived factors in melanocyte homeostasis, the response to UV, and pigmentary disorders

Human epidermal melanocytes play a central role in sensing the environment and protecting the skin from the drastic effects of solar ultraviolet radiation and other environmental toxins or inflammatory agents. Melanocytes survive in the epidermis for decades, which subjects them to chronic environmental insults. Melanocytes have a poor self-renewal capacity; therefore, it is critical to ensure their survival with genomic stability. The function and survival of melanocytes is regulated by an elaborate network of paracrine factors synthesized mainly by epidermal keratinocytes and dermal fibroblasts. A symbiotic relationship exists between epidermal melanocytes and keratinocytes on the one hand, and between melanocytes and dermal fibroblasts on the other hand. Melanocytes protect epidermal keratinocytes and dermal fibroblasts from the damaging effects of solar radiation, and the latter cells synthesize biochemical mediators that maintain the homeostasis, and regulate the stress response of melanocytes. Disruption of the paracrine network results in pigmentary disorders, due to abnormal regulation of melanin synthesis, and compromise of melanocyte survival or genomic stability. This review provides an update of the current knowledge of keratinocyte- and fibroblast-derived paracrine factors and their contribution to melanocyte physiology, and how their abnormal production is involved in the pathogenesis of common pigmentary disorders.

Efficacy and safety of 0.15% isobutylamido thiazolyl resorcinol combined with hyaluronic acid vs 0.15% isobutylamido thiazolyl resorcinol or hyaluronic acid alone in melasma treatment: A randomized evaluator-blind trial

BACKGROUND

Melasma has a complex pathogenesis, and various aggravating factors contribute to its recalcitrance to treatments. A combination of isobutylamido thiazolyl resorcinol (ITR) and hyaluronic acid (HA) could increase melasma treatment efficacy.

AIMS

To compare the efficacy and safety of 0.15% ITR plus HA vs 0.15% ITR or HA alone in melasma treatment.

METHODS

Ninety-two patients received ITR 0.15% plus HA (n = 30), 0.15% ITR (n = 31), or HA (n = 31) along with broad-spectrum sunscreen application for 12 weeks. Treatment efficacy was determined using modified Melasma Area Severity Index (mMASI), average melanin and melanin variation with Antera3D^® , and safety based on transepidermal water loss.

RESULTS

Compared with the HA group, the ITR+HA group showed significantly reduced mMASI at weeks 4, 8, and 12 (p = 0.026, 0.015, and 0.001, respectively), whereas the ITR group showed a significant reduction at week 12 (p = 0.027). There was no significant difference in the mMASI or average melanin level between the ITR+HA and ITR groups. Melanin variation was significantly lower in the ITR+HA group than in the ITR group at weeks 4, 8, and 12 (p = 0.027, 0.019, and 0.023, respectively).

CONCLUSIONS

The combination of 0.15% ITR and 0.15% ITR+HA effectively reduced melasma severity. HA could synergistically improve melasma homogeneity.

The Vascular Component of Melasma: A Systematic Review of Laboratory, Diagnostic, and Therapeutic Evidence

BACKGROUND

Melasma is a common acquired disorder of hyperpigmentation, classically manifesting as symmetric brown patches on the face. Although the exact pathogenesis is not fully understood, vascular abnormalities have been implicated in melasma.

OBJECTIVE

To evaluate the laboratory and clinical evidence regarding the safety and efficacy of antivascular agents for the treatment of melasma.

METHODS

A systematic review of PubMed, EMBASE, and Cochrane was conducted on May 13, 2020, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Original research articles investigating the role of vascularity and/or evaluating the use of antivascular therapeutics in melasma were included. Clinical recommendations were based on the American College of Physicians guidelines.

RESULTS

A total of 34 original research articles as follows were identified: 4 laboratory studies, 15 diagnostic studies, and 15 therapeutic studies.

CONCLUSION

There is promising evidence supporting the use of tranexamic acid and laser/light therapies to treat the vascular component of melasma, and more rigorous clinical trials are needed to validate their efficacy. Clinicians may consider treatment with one or more antivascular therapeutics in patients with melasma. Further research is warranted to characterize the role of cutaneous vascularization in melasma and may provide insights for novel therapies.

How hormones may modulate human skin pigmentation in melasma: An in vitro perspective

Melasma is a common acquired hyperpigmentary disorder occurring primarily in photo-exposed areas and mainly affecting women of childbearing age. To decipher the role of sex hormones in melasma, this viewpoint reviews the effects of sex hormones on cutaneous cells cultured in monolayers, in coculture, in 3D models and explants in the presence or the absence of UV. The data show that sex steroid hormones, especially oestrogen, can modulate in vitro pigmentation by stimulating melanocytes and keratinocyte pro-pigmentary factors, but not via fibroblast or mast cell activation. In vitro data suggest that oestrogen acts on endothelial cell count, which may in turn increase endothelin-1 concentrations. However, data on explants revealed that sex steroid even at doses observed during pregnancy cannot induce melanogenesis alone nor melanosome transfer but that it acts in synergy with UVB. In conclusion, we hypothesize that in predisposed persons, sex steroid hormones initiate hyperpigmentation in melasma by amplifying the effects of UV on melanogenesis via direct effects on melanocytes or indirect effects via keratinocytes and on the transfer of melanosomes. They also help to sustain hyperpigmentation by increasing the number of blood vessels and, in turn, the level of endothelin-1.

Melasma: Updates and perspectives

Management of melasma is highly challenging due to inconsistent treatment results and frequent relapses. However, recent studies revealed that melasma may not only be a disease of melanocytes, but also a photoaging skin disorder. Herein, we attempt to validate that melasma is indeed a photoaging disorder by presenting the histopathologic findings of melasma: solar elastosis, altered basement membrane, increased vascularization and increased mast cell count. We also provide some therapeutic implications based on these findings and a discussion on the latest updates and perspectives regarding treatment.

Serine racemase deficiency attenuates choroidal neovascularization and reduces nitric oxide and VEGF levels by retinal pigment epithelial cells

Choroidal neovascularization (CNV) is a leading cause of blindness in age-related macular degeneration. Production of vascular endothelial growth factor (VEGF) and macrophage recruitment by retinal pigment epithelial cells (RPE) significantly contributes to the process of CNV in an experimental CNV model. Serine racemase (SR) is expressed in retinal neurons and glial cells, and its product, d-serine, is an endogenous co-agonist of N-methyl-d-aspartate receptor. Activation of the receptor results in production of nitric oxide (^. NO), a molecule that promotes retinal and choroidal neovascularization. These observations suggest possible roles of SR in CNV. With laser-injured CNV mice, we found that inactivation of SR-coding gene (Srr_null ) significantly reduced CNV volume, neovascular density, and invading macrophages. We exploited the underlying mechanism in vivo and ex vivo. RPE from wild-type (WT) mice expressed SR. To explore the possible downstream target of SR inactivation, we showed that choroid/RPE homogenates extracted from laser-injured Srr_null mice contained less inducible nitric oxide synthase and decreased phospho-VEGFR2 compared to amounts in WT mice. In vitro, inflammation-primed WT RPEs expressed more inducible NOS, produced more^. NO and VEGF than did inflammation-primed Srr_null RPEs. When co-cultured with inflammation-primed Srr_null RPE, significantly fewer RF/6A-a cell line of choroidal endothelial cell, migrated to the opposite side of the insert membrane than did cells co-cultured with pre-treated WT RPE. Altogether, SR deficiency reduces RPE response to laser-induced inflammatory stimuli, resulting in decreased production of a cascade of pro-angiogenic cytokines, including^. NO and VEGF, and reduced macrophage recruitment, which contribute synergistically to attenuated angiogenesis.

Melasma: an Up-to-Date Comprehensive Review

Melasma is a common acquired condition of symmetric hyperpigmentation, typically occurring on the face, with higher prevalence in females and darker skin types. Multiple etiologies, including light exposure, hormonal influences, and family history, have been implicated in the pathogenesis of this disorder. Overall prevalence ranges widely at 1-50%, since values are typically calculated within a specific ethnic population within a geographic region. Histologically, melasma can display increased epidermal and/or dermal pigmentation, enlarged melanocytes, increased melanosomes, solar elastosis, dermal blood vessels, and, occasionally, perivascular lymphohistiocytic infiltrates. Various topical, oral, and procedural therapies have been successfully used to treat melasma. Traditional topical therapies including hydroquinone, tretinoin, corticosteroids, and triple combination creams; however, other synthetic and natural topical compounds have also shown varying efficacies. Promising oral therapies for melasma include tranexamic acid, Polypodium leucotomos, and glutathione. Procedures, including chemical peels, microneedling, radiofrequency, and lasers, are also often used as primary or adjunctive treatments for melasma. Notably, combination therapies within or across treatment modalities generally result in better efficacies than monotherapies. This review serves as a comprehensive update on the current understanding of the epidemiology, pathogenesis, clinical and histologic features of melasma, as well as treatments for this common, yet therapeutically challenging, condition.

Role of oxidative stress in melasma: a prospective study on serum and blood markers of oxidative stress in melasma patients

BACKGROUND

Melasma is a common pigmentary disorder presenting in the dermatological clinic. Many factors have been implicated in the pathogenesis, however, the cause still remains elusive. Recently the effect of oxidative damage has been proposed in the etiopathogenesis of melasma. This study was undertaken to evaluate the role of oxidative stress in patients with melasma.

MATERIAL AND METHODS

Fifty patients with melasma, age 18 years of age and older, and an equal number of age and sex-matched controls were included in the study. Baseline severity assessment using the modified Melasma Area and Severity Index (modified MASI score) was done in all patients. Serum malondialdehyde, blood superoxide dismutase, and blood glutathione peroxidase levels were measured in cases and controls group and results were compared.

RESULT

The serum levels of malondialdehyde, superoxide dismutase, and blood glutathione were significantly higher among the cases compared to controls. The difference in the serum concentrations was significant between the two groups (P < 0.01). A positive correlation was found between these enzyme levels and severity of melasma (modified MASI score); however, this correlation was statistically significant with serum malondialdehyde only. The level of oxidative stress among the male and female melasma patients was not statistically different.

CONCLUSION

Oxidative stress was found to be increased in cases of melasma compared to the control group in this study. This substantiates the role of oxidative stress in etiopathogenesis of melasma; however, further studies are required to reach a definitive conclusion.

Heterogeneous Pathology of Melasma and Its Clinical Implications

Melasma is a commonly acquired hypermelanosis that affects sun-exposed areas of the skin, with frequent facial involvement. Its histologic manifestations are evident in the epidermis, extracellular matrix, and dermis. In addition to epidermal pigmentation, pathologic findings of melasma include extracellular matrix abnormality, especially solar elastosis. The disrupted basement membrane has been described in melasma with variable incidences. In the dermis, an increase in vascularity and an increase in the number of mast cells were observed, indicating that dermal factors have critical roles in the pathogenesis of melasma, despite the fact that melasma is characterized by epidermal hyperpigmentation. This review discusses such histologic characteristics of melasma, with consideration to their implications for melasma treatment.

Recent progress in melasma pathogenesis

Melasma is a common skin pigmentation condition. Given therapeutic difficulty as one of the biggest concerns, understanding of the etiology and pathogenesis of melasma becomes essential. UV irradiation, female sex hormones, and inflammatory processes are addressed as triggering factors with genetic predisposition. The mechanism of UV-induced melanogenesis has been extensively investigated as a model system to study melasma pathogenesis. Hitherto, treatment modalities for melasma are similar to other hyperpigmentation disorders. However, individual triggering factors induce a separate pigmentation disease, whose pathogenic mechanisms and clinical phenotypes are different from the ones encountered in melasma. Fortunately, there have been ongoing updates on melasma pathogenesis with regard to major triggering factors. Presence of certain factors working independently of UV exposure and role of dermal factors and microRNAs are being identified as novel discoveries about melasma pathogenesis. In this review, the melasma pathogenesis is reviewed in association with updated and new findings.

Melasma update

Melasma is an acquired pigmentary disorder characterized by symmetrical hyperpigmented macules on the face. Its pathogenesis is complex and involves the interplay of various factors such as genetic predisposition, ultraviolet radiation, hormonal factors, and drugs. An insight into the pathogenesis is important to devise treatment modalities that accurately target the disease process and prevent relapses. Hydroquinone remains the gold standard of treatment though many newer drugs, especially plant extracts, have been developed in the last few years. In this article, we review the pathogenetic factors involved in melasma. We also describe the newer treatment options available and their efficacy. We carried out a PubMed search using the following terms “melasma, pathogenesis, etiology, diagnosis, treatment” and have included data of the last few years.

A novel upregulation of glutathione peroxidase 1 by knockout of liver-regenerating protein Reg3β aggravates acetaminophen-induced hepatic protein nitration

Murine regenerating islet-derived 3β (Reg3β) represents a homologue of human hepatocarcinoma-intestine-pancreas/pancreatic-associated protein and enhances mouse susceptibility to acetaminophen (APAP)-induced hepatotoxicity. Our objective was to determine if and how knockout of Reg3β (KO) affects APAP (300 mg/kg, ip)-mediated protein nitration in mouse liver. APAP injection produced greater levels of hepatic protein nitration in the KO than in the wild-type mice. Their elevated protein nitration was alleviated by a prior injection of recombinant mouse Reg3β protein and was associated with an accelerated depletion of the peroxynitrite (ONOO(-)) scavenger glutathione by an upregulated hepatic glutathione peroxidase-1 (GPX1) activity. The enhanced GPX1 production in the KO mice was mediated by an 85% rise (p<0.05) in the activity of selenocysteine lyase (Scly), a key enzyme that mobilizes Se for selenoprotein biosynthesis. Knockout of Reg3β enhanced AP-1 protein and its binding activity to the Scly gene promoter, upregulating its gene transcription. However, knockout of Reg3β did not affect gene expression of other key factors for selenoprotein biosynthesis. In conclusion, our findings unveil a new metabolic role for Reg3β in protein nitration and a new biosynthesis control of GPX1 by a completely "unrelated" regenerating protein, Reg3β, via transcriptional activation of Scly in coping with hepatic protein nitration. Linking selenoproteins to tissue regeneration will have profound implications in understanding the mechanism of Se functions and physiological coordination of tissue regeneration with intracellular redox control.

Melasma pathogenesis and influencing factors - an overview of the latest research

Melasma is an acquired, symmetrical hypermelanosis of the face. The pathogenesis of melasma is complex and the treatment is often challenging with frequent relapses. Genetic background, exposure to ultraviolet radiation, and female sex hormones are classical influencing factors. To the light of the recent literature, other factors could promote melasma lesions. Moreover, there are increasing evidences showing that melanocytes are not the only cells involved, and that other players probably have a key role in the development and the relapses of melasma. Identifying those associated factors should provide new targets for a more efficient treatment of melasma and a better prevention of the relapses.

What should be considered in treatment of melasma

Melasma is a common acquired hyperpigmentary skin disorder characterized by light to dark brown macules and patches occurring in the sun-exposed areas of the face. Melasma lesional skin is characterized by epidermal hyperpigmentation through increased melanogenesis in epidermal melanocytes. Some patients have dermal melanin but its amount is not significant and its distribution is very heterogeneous in the whole melasma lesional skin. Melasma is not homogeneous disease and there are personal characteristics of patients with melasma. The pathogenesis of melasma is not fully understood, but several hypotheses have been suggested. Increased vascularity in melasma lesions has suggested the role of increased number of enlarged vessels in the development of melasma. Endogeneous and exogeneous stimuli such as sex hormones and ultraviolet irradiation respectively may stimulate the microenvironment leading to the release of various mediators that cause activation of melanocytes and/or these stimuli may directly activate the melanocytes. Melasma patients may have specialized melanocytes with an intrinsic sensitivity to these stimuli.