Update on Melasma-Part I: Pathogenesis

An Update on New and Existing Treatments for the Management of Melasma

Melasma is a chronic, acquired disorder of focal hypermelanosis that carries significant psychosocial impact and is challenging for both the patient and the treating practitioner to manage in the medium to long term. Multiple treatments have been explored, often in combination given the many aetiological factors involved in its pathogenesis. Therapeutic discoveries to treat melasma are a focal topic in the literature and include a range of modalities, with recent developments including updates on visible light photoprotection, non-hydroquinone depigmenting agents, oral tranexamic acid, chemical peels, and laser and energy-based device therapy for melasma. It is increasingly important yet challenging to remain up-to-date on the arsenal of treatments available for melasma to find an efficacious and well-tolerated option for our patients.

Efficacy and safety of mesotherapy with tranexamic acid versus vitamin C in the treatment of melasma: A meta-analysis and systemic review

BACKGROUND

The exact pathogenesis of melasma is not yet known, and its treatment remains challenging. Mesotherapy with tranexamic acid (TXA) and vitamin C was both reported to have certain effects on melasma. In spite of that several articles have compared the efficacy and safety of the two drugs on melasma, most of them were clinical study with small sample size.

AIMS

To evaluate the efficacy and safety of mesotherapy with TXA versus vitamin C in treating melasma through meta-analysis and systemic review.

METHODS

The authors searched PubMed, Web of Science, Springer, and ScienceDirect for studies that compared mesotherapy with TXA versus vitamin C as a treatment for melasma. Primary outcomes were change in melasma area and severity index (MASI) before and after the treatment.

RESULTS

Finally, five studies with a total of 127 patients were included in the systematic review. There was no statistic difference in the change in MASI score between the TXA and vitamin C groups (mean difference, 0.16; 95% CI, -0.79 to 1.11).

CONCLUSIONS

Mesotherapy with both TXA and vitamin C is safe and effective in the treatment of melasma.

Combining large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers for promoting protective melanosome autophagy via the PI3K/Akt/mTOR signalling pathway for the treatment of melasma

Melasma is a common condition of hyperpigmented facial skin. Picosecond lasers are reported to be effective for the treatment of melasma. We aimed to identify the most effective therapeutic mode and elucidate the potential molecular mechanisms of picosecond lasers for the treatment of melasma. Female Kunming mice with melasma-like conditions were treated using four different picosecond laser modes. Concurrently, in vitro experiments were conducted to assess changes in melanin and autophagy in mouse melanoma B16-F10 cells treated with these laser modes. Changes in melanin in mouse skin were detected via Fontana-Masson staining, and melanin particles were evaluated in B16-F10 cells. Real-time polymerase chain reaction and western blotting were used to analyse the expression levels of melanosome and autophagy-related messenger ribonucleic acid (mRNA) and proteins. A combination of large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers resulted insignificant decreases in melanin as well as in mRNA and protein expression of melanin-synthesizing enzymes (TYR, TRP-1 and MITF). This combination also led to increased expression of the autophagy-related proteins, Beclin1 and ATG5, with a marked decrease in p62 expression. Intervention with the PI3K activator, 740 Y-P, increased TYR, TRP-1, MITF, p-PI3K, p-AKT, p-mTOR and p62 expression but decreased the expression of LC3, ATG5 and Beclin1. A combination of large-spot low-fluence 1064-nm and fractional 1064-nm picosecond lasers proved more effective and safer. It inhibits melanin production, downregulates the PI3K/AKT/mTOR pathway, enhances melanocyte autophagy and accelerates melanin metabolism, thereby reducing melanin content.

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.

Comparison of 755-nm picosecond alexandrite laser versus 1064-nm Q-switched Nd:YAG laser for melasma: A randomized, split-face controlled, 2-year follow-up study

OBJECTIVES

Pulsed laser treatment of melasma has shown some promising results. To compare the effectiveness and safety of 755-nm picosecond alexandrite laser (PSAL) fitted with diffractive lens array (DLA) versus 1064-nm Q-switched neodynimum:yttrium aluminum garnet laser (QSNYL) for the treatment of melasma.

METHODS

We conducted a randomized, split face controlled, 2-year follow-up study. Each face was divided into two parts, each side receiving three treatments with either PSAL or QSNYL at 1 month intervals. Modified Melasma Area Severity Index scores (mMASI), pain scores, patient satisfaction and adverse events were recorded. In vivo reflectance confocal microscopy (RCM) images were acquired.

RESULTS

Twenty subjects were enrolled and three dropped out. At 6 months, mMASI scores were significantly lower than baseline for QSNYL sides (p = 0.022), with no statistically significant difference between PSAL sides before and after treatment, PSAL sides versus QSNYL sides, or patient satisfaction scores. QSNYL treatment was associated with less pain (p = 0.014). No serious adverse events were reported. In the PSAL sides RCM showed a large number of dendritic melanocytes infiltrated in the dermis at 2 weeks and 4 weeks after treatment. Ten patients (58.82%) reported recurrence or exacerbation at 2-year follow-up with no statistically significant difference between the two lasers.

CONCLUSIONS

QSNYL demonstrated short term clinical efficacy for melasma, but did not provide any additional benefit compared to PSAL with DLA. QSNYL was associated with less pain. There was a high recurrence rate at 2-year follow-up. RCM allowed the detection of cellular changes in melasma lesions.

Carotenoids in red fruit (Pandanus conoideus Lam.) have a potential role as an anti‑pigmentation agent (Review)

Melasma is a persistent condition characterized by excessive melanin production in the skin. The management of melasma necessitates a protracted treatment duration, which is associated with diminished levels of patient satisfaction. One effective strategy for mitigating occurrence of melasma is consumption of nutricosmetics with depigmentation properties. The present review aimed to investigate the potential of red fruit as a depigmentation agent. Carotenoids serve a crucial role in human nutrition as a precursor to vitamin A. Carotenoids serve as scavengers of reactive oxygen species generated by ultraviolet radiation. Carotenoids promote skin health. Red fruit, a fruit originating from Papua (Indonesia) has anti-pigmentation properties associated with its ability to block melanogenesis through various protein pathways such as PKA, ERK, and AKT signaling pathways. The consumption of food rich in carotenoids, such as red fruit, has advantageous properties to reduce hyperpigmentation and skin brightening.

Efficacy and Safety of Ablative Fractional Laser in Melasma: A Meta-analysis and Systematic Review

Melasma is a common acquired skin pigmentation disorder. The treatment is urgent but challenging. Ablative fractional laser (AFL) can improve pigmentation, but the efficacy and potential side effects are still debatable. This study aimed to evaluate the efficacy and safety of ablative fractional lasers in the treatment of melasma. A comprehensive systematic search of literature published before June 20, 2023, was conducted on online databases, including PubMed, Embase, Cochrane Library, and Web of Science. The data obtained were analyzed using Review Manager 5.4 software. Fourteen randomized controlled trials, comprising 527 patients, were included. Compared to the drug alone, the combination of AFL and the drug showed improved therapeutic efficacy in the melasma area and severity index (MASI) (MD = 1.54, 95% CI [0.16, 2.92], P = 0.03) and physician global assessment (RR = 1.61, 95% CI [1.08, 2.41], P = 0.02). However, no statistically significant results were found in patient self-assessment (RR = 1.56, 95% CI [0.88, 2.76], P = 0.12). As an individual therapy, AFL is not superior to any other lasers in terms of MASI (MD = 2.66, 95% CI [-1.32, 6.64], P = 0.19) or melanin index (MD = -7.06, 95% CI [-45.09, 30.97], P = 0.72). Common adverse events included transient erythema, burning, edema, and superficial crusting. Only a few patients experienced reversible post-inflammatory hyperpigmentation, herpes labialis, and acne breakouts. These results support the application of AFL as a viable treatment option for melasma, particularly in refractory and severe cases. Rational parameterization or combination therapy may lead to significant clinical improvement with fewer complications.

Prevalence of depression in melasma: a systematic review and meta-analysis

Background

Due to cosmetic disfigurement, melasma can negatively affect the quality of life and emotional and mental health, further leading to depression.

Objective

Prevalence rates of depression in patients with melasma vary widely across studies. The aim of this systematic review and meta-analysis was to estimate the prevalence of depression among melasma patients.

Methods

The PubMed, Embase, Web of Science, and Scopus databases were searched to identify articles evaluating the prevalence of depression in melasma patients from their inception to 12 July 2023. Studies were reviewed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and a meta-analysis was performed using the Stata 14.0 software.

Results

Sixteen studies met the eligibility criteria out of the 859 studies, containing a total of 2,963 melasma patients for this systematic review and meta-analysis. Meta-analyses revealed that the pooled prevalence of depression among patients with melasma was 43.4% (95% CI 30.5-56.2%, Q-value = 808.859, d.f. = 15, p < 0.001, tau2 = 0.065, I2 = 98.1%). The meta-regression found that the publication year, sample size, and study quality were not significant moderators for the observed heterogeneity in prevalence. A subgroup analysis according to depression assessment methods showed that the prevalence of depressive disorders was 24.2% (95% CI 16.8-31.6%), and the prevalence of depressive symptoms was 45.1% (95% CI 31.2-59.0%). A subgroup analysis by geographic regions showed that patients in Asia had the highest prevalence of depression at 48.5% (95% CI 26.0-71.0%), compared to other regions. A subgroup analysis by study design showed that the prevalence of depression in case-control studies was almost identical to cross-sectional studies. In the case of OR, the pooled OR of depression between patients with melasma and health controls was 1.677 (95% CI 1.163-2.420, p = 0.606, I2 = 0.0%).

Conclusion

The prevalence of depression was relatively high in patients with melasma, and there was a correlation between melasma and depression, encouraging clinicians to screen for depression in their patients and providing a combination of physical and psychosocial support. If necessary, they should be referred to formal mental health services to seek professional psychological intervention.

Systematic review registration

https://www.crd.york.ac.uk/PROSPERO/, CRD42022381378.

Role of interleukin-6 and endothelin-1 receptors in enhanced melanocyte dendricity of facial spots and suppression of their ligands by niacinamide and tranexamic acid

BACKGROUND

Hyperpigmented spots are common issues in all ethnicities with a hallmark characteristic of increased melanocyte dendricity.

OBJECTIVES

To determine (1) potential receptors and/or cytokines that are involved in increased melanocyte dendricity in multiple facial spot types; (2) treatment effects of skin-lightening compounds on identified cytokine release from keratinocytes and on dendricity in melanocytes.

METHODS

Facial spots (melasma, solar lentigo, acne-induced post-inflammatory hyperpigmentation) and adjacent non-spot skin biopsies were collected from Chinese women (age 20-70). The epidermal supra and basal layers were laser dissected to enrich keratinocyte or melanocyte biology respectively for transcriptome analysis. Melanocyte dendricity was assessed histologically by immunofluorescent staining. Effect of interleukin-6 (IL-6) and endothelin-1 (ET-1) on melanocyte dendricity and melanosome transfer were assessed in human melanocytes or melanocyte-keratinocyte co-culture models. Treatment effects of skin-lightening compounds (niacinamide, tranexamic acid [TxA], sucrose laurate/dilaurate mixture [SDL]) were assessed on IL-6 or ET-1 release from keratinocytes and on dendricity in melanocytes.

RESULTS

Transcriptome analysis revealed IL-6 receptor and ET-1 receptor were significantly upregulated compared to the adjacent normal skin, visually confirmed at the protein level through immunostaining. Melanocytes in spot areas are more dendritic than melanocytes in adjacent non-spot skin. The addition of IL-6 and ET-1 to cell culture models increased melanocyte dendricity and melanosome transfer. IL-6 release was significantly suppressed by niacinamide and its combination, while ET-1 release was significantly reduced by both niacinamide and TxA. In contrast, SDL acted directly upon melanocytes to reduce dendricity.

CONCLUSION

Interleukin-6 and ET-1 receptors are significantly upregulated in multiple facial spot types. The in vitro testing demonstrated their respective ligands increased melanocyte dendricity. Tested skin-lightening compounds showed reduction in release of IL-6/ET-1 from epidermal keratinocytes and/or inhibition of melanocyte dendricity. This work sheds light on pathophysiological mechanism of facial spots and potential new mechanisms of these skin-lightening compounds which warrant further human clinical validation.

Efficacy and safety of metformin for melasma treatment: a systematic review and meta-analysis

Objective: Metformin has recently been demonstrated to have an anti-melanogenic activity. Nevertheless, clinical evidence of the effectiveness of metformin in melasma is lacking. The objective of this study was to assess the efficacy and safety of metformin in the treatment of melasma. Methods: MEDLINE, Embase, PubMed, Cochrane Library (CENTRAL), Scopus, CINAHL, and grey literature databases were searched to 4 October 2022 and updated on 26 February 2023. Randomized controlled trials (RCTs), quasi-RCTs, observational studies, case series, and case reports investigating the efficacy and safety of metformin for melasma were included. The Melasma Area Severity Index (MASI) scores that changed from baseline were pooled using fixed-effects model and expressed as standardized mean differences (SMDs) and 95% confidence intervals (CIs). Results: Three RCTs including 140 patients with melasma were included. The results demonstrated that after 8 weeks, 15% topical metformin significantly reduced the Melasma Area Severity Index (MASI) score compared to placebo (1 trial; n = 60; MD, -0.56; 95% CI, -1.07 to -0.04; p = 0.034). Furthermore, when compared to triple combination cream (TCC), 30% topical metformin demonstrated similar efficacy in reducing the MASI score after 8 weeks (2 trials; n = 80; MD, 0.19, 95% CI, -0.25 to 0.63; p = 0.390). Patients using 30% topical metformin had fewer adverse events compared to TCC users, although no statistical difference was found. Conclusion: Topical metformin was as effective as triple combination cream (TCC) in decreasing changes in the MASI score in patients with melasma, with minimum adverse events. Further studies with larger sample sizes, longer follow-up times, and well-designed trials are required. Systematic Review Registration: Identifier PROSPERO (CRD42022351966).

Analysis of the antimelanogenic activity of zinc and selenium in vitro

Melasma is an acquired chronic condition characterized by hyperchromic patches in photo-exposed areas. The search for new compounds for the treatment of melasma without side effects is constant. In this context, the aim of this study was to investigate the in vitro cytotoxic and antimelanogenic effects of the trace elements Zinc (Zn) and Selenium (Se). In this study, we evaluated the effects of 30 µM hydroquinone, this concentration did not alter mitochondrial function (MTT assay), but increased the percentage of necrotic cells and levels of reactive species. Furthermore, it showed no influence on tyrosinase activity and melanin content. Unlike hydroquinone, exposure for 48 h to 100 µM Zn and 1 and 5 µM Se had no significant influence on the analysis of reactive species, as well as on the percentage of necrotic cells. Still, specifically in relation to 100 µM Zn, it decreased the melanin content. Given the above, the trace elements Zn and Se did not show toxicity at the concentrations tested and Zn showed a promising effect, however, the mechanism needs to be better explored in order to contribute to new and updated research in the fight against melasma with a perspective of therapeutic use.

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.

Adaptability of melanocytes post ultraviolet stimulation in patients with melasma

BACKGROUND

Dynamic in vivo changes in melanin in melasma lesions after exposure to ultraviolet (UV) irradiation have not been described.

OBJECTIVES

To determine whether melasma lesions and nearby perilesions demonstrated different adaptive responses to UV irradiation and whether the tanning responses were different among different locations on face.

METHODS

We collected sequential images from real-time cellular resolution full-field optical coherence tomography (CRFF-OCT) at melasma lesions and perilesions among 20 Asian patients. Quantitative and layer distribution analyses for melanin were performed using a computer-aided detection (CADe) system that utilizes spatial compounding-based denoising convolutional neural networks.

RESULTS

The detected melanin (D) is melanin with a diameter >0.5 µm, among which confetti melanin (C) has a diameter of >3.3 µm and corresponds to a melanosome-rich package. The calculated C/D ratio is proportional to active melanin transportation. Before UV exposure, melasma lesions had more detected melanin (p = 0.0271), confetti melanin (p = 0.0163), and increased C/D ratio (p = 0.0152) in the basal layer compared to those of perilesions. After exposure to UV irradiation, perilesions have both increased confetti melanin (p = 0.0452) and the C/D ratio (p = 0.0369) in basal layer, and this effect was most prominent in right cheek (p = 0.030). There were however no significant differences in the detected, confetti, or granular melanin areas before and after exposure to UV irradiation in melasma lesions in all the skin layers.

CONCLUSIONS

Hyperactive melanocytes with a higher baseline C/D ratio were noted in the melasma lesions. They were "fixed" on the plateau and were not responsive to UV irradiation regardless of the location on face. Perilesions retained adaptability with a dynamic response to UV irradiation, in which more confetti melanin was shed, mainly in the basal layer. Therefore, aggravating effect of UV on melasma was mainly due to UV-responsive perilesions rather than lesions.

Azelaic Acid Versus Hydroquinone for Managing Patients With Melasma: Systematic Review and Meta-Analysis of Randomized Controlled Trials

Melasma, a commonly acquired hyperpigmentation skin condition, is usually treated with topical agents as the first line of management. This systematic review and meta-analysis aimed to assess the efficacy and safety of azelaic acid versus hydroquinone in treating melasma patients. We conducted a comprehensive search across four online databases (PubMed, Scopus, Web of Science, and Cochrane Library) from the time of their creation until May 28, 2023. We considered randomized controlled studies comparing hydroquinone with azelaic acid for the treatment of melasma patients. We used the Cochrane Risk of Bias tool 2 to evaluate the risk of bias. The mean difference (MD) for continuous variables and the risk ratio (RR) for categorical variables, with a 95% confidence interval (CI) were pooled. Six studies were included, with a total of 673 patients with melasma. The azelaic acid had a lower mean change in melasma area severity index (MASI) than the hydroquinone group [MD= -1.23, 95% CI (-2.05, -0.40), P=0.004]. No difference was observed regarding the improvement via the objective response scale, the reduction in pigmentation, or the adverse events reported. However, despite not being statistically significantly different, there was a trend towards having more good responses in the azelaic acid group. Azelaic acid may be better than hydroquinone in reducing melasma severity (measured by MASI). However, larger studies with long-term follow-up are needed to validate these findings.

New Mechanistic Insights of Melasma

Melasma is a common acquired disorder of pigmentation that negatively impacts quality of life. Present treatments show poor therapeutic effect with frequent recurrence. This in large part is due to the currently limited understanding of the disease's etiology. It is urgent to elucidate the pathogenesis of melasma to further the discovery of new therapeutic strategies. Recent studies show that melasma is triggered or aggravated by a variety of factors, including genetic susceptibility, ultraviolet radiation, and sex hormone dysregulation. Ultraviolet B radiation upregulates the expression of several melanocyte-specific genes and stimulates the release of key factors that participate in the synthesis of melanin. There is a significant increase in melanin in both the epidermal and dermal layers of affected skin, possibly due to abnormalities in crosstalk between the melanocytes and other cells. Melanogenesis is regulated through various signaling networks including the Wnt/β-catenin, PI3K/Akt, cAMP/PKA, and SCF/c-kit-mediated signaling pathways. In addition, inflammatory mediators, oxidative stress, neuroactive molecules, sebocytes, etc, have also been proved to be related to the pathogenesis of melasma. This review provides a comprehensive update on the current understanding of the pathogenesis of melasma.