Acquired disorders with hypopigmentation: A clinical approach to diagnosis and treatment

Melanin Biopolymers in Pharmacology and Medicine-Skin Pigmentation Disorders, Implications for Drug Action, Adverse Effects and Therapy

Melanins are biopolymeric pigments formed by a multi-step oxidation process of tyrosine in highly specialized cells called melanocytes. Melanin pigments are mainly found in the skin, iris, hair follicles, and inner ear. The photoprotective properties of melanin biopolymers have been linked to their perinuclear localization to protect DNA, but their ability to scavenge metal ions and antioxidant properties has also been noted. Interactions between drugs and melanins are of clinical relevance. The formation of drug-melanin complexes can affect both the efficacy of pharmacotherapy and the occurrence of adverse effects such as phototoxic reactions and discoloration. Because the amount and type of melanin synthesized in the body is subject to multifactorial regulation-determined by both internal factors such as genetic predisposition, inflammation, and hormonal balance and external factors such as contact with allergens or exposure to UV radiation-different effects on the melanogenesis process can be observed. These factors can directly influence skin pigmentation disorders, resulting in hypopigmentation or hyperpigmentation of a genetic or acquired nature. In this review, we will present information on melanocyte biology, melanogenesis, and the multifactorial influence of melanin on pharmacological parameters during pharmacotherapy. In addition, the types of skin color disorders, with special emphasis on the process of their development, symptoms, and methods of treatment, are presented in this article.

Diagnosing Disorders of Hypopigmentation and Depigmentation in Patients with Skin of Color

Skin hypopigmentation and depigmentation disorders are a top concern for patients with skin of color seeking care from a dermatologist. The visual contrast between involved and uninvolved skin in these disorders makes them particularly burdensome for patients with skin of color. These disorders may have a wide differential of diagnosis, as patients with skin of color may present differently or more frequently than White patients for certain conditions. Clues from a comprehensive history and physical examination with standard lighting and a Wood's light are essential for clinching the diagnosis, although a biopsy may be warranted in special cases.

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.

Variations in genetics, biology, and phenotype of cutaneous disorders in skin of color. Part II: Differences in clinical presentation and disparities in cutaneous disorders in skin of color

Skin of color (SOC) patients are projected to comprise the majority of the population by 2044, yet knowledge gaps in the clinical presentation and treatment of both common and uncommon dermatologic conditions in skin of color persist. Improved awareness of disparities that disproportionately impact SOC patients is necessary to address health inequity in the field of dermatology. The first part of this CME discussed structural, genetic, and immunophenotypic differences in SOC in common inflammatory disorders as well as cutaneous malignancies. The second part of this CME highlights clinical differences in the phenotypic presentation of the inflammatory disorders of atopic dermatitis, psoriasis, and hidradenitis suppurativa as well as the cutaneous malignancies of melanoma, basal cell carcinoma, and cutaneous T-cell lymphoma. Health disparities associated with each of these conditions are also discussed.

BCI-215, a Dual-Specificity Phosphatase Inhibitor, Reduces UVB-Induced Pigmentation in Human Skin by Activating Mitogen-Activated Protein Kinase Pathways

Background: The dysregulation of melanin production causes skin-disfiguring ultraviolet (UV)-associated hyperpigmented spots. Previously, we found that the activation of c-Jun N-terminal kinase (JNK), a mitogen-activated protein kinase (MAPK), inhibited melanogenesis. Methods: We selected BCI-215 as it may modify MAPK expression via a known function of a dual-specificity phosphatase (DUSP) 1/6 inhibitor. B16F10 melanoma cells, Mel-ab cells, human melanocytes, and a coculture were used to assess the anti-melanogenic activity of BCI-215. The molecular mechanisms were deciphered by assaying the melanin content and cellular tyrosinase activity via immunoblotting and RT-PCR. Results: BCI-215 was found to suppress basal and cAMP-stimulated melanin production and cellular tyrosinase activity in vitro through the downregulation of microphthalmia-associated transcription factor (MITF) protein and its downstream enzymes. The reduction in MITF expression caused by BCI-215 was found to be due to all three types of MAPK activation, including extracellular signal-regulated kinase (ERK), JNK, and p38. The degree of activation was greater in ERK. A phosphorylation of the β-catenin pathway was also demonstrated. The melanin index, expression of MITF, and downstream enzymes were well-reduced in UVB-irradiated ex vivo human skin by BCI-215. Conclusions: As BCI-215 potently inhibits UV-stimulated melanogenesis, small molecules of DUSP-related signaling modulators may provide therapeutic benefits against pigmentation disorders.

Selenium alleviates heart remodeling through Sirt1/AKT/GSK-3β pathway

Selenium, reported as an important medium for maintaining the body's homeostasis, acts to have multiple bioeffects including anti-inflammatory, anti-oxidant and anti-apoptosis effects. However, its role in heart failure still remains unclear. In this study, we explored the effects of selenium on heart failure and its possible mechanism. The heart failure models were induced by aortic banding and isoproterenol. H&E, TUNEL and PSR staining were performed to detect the degree of cardiomyocyte hypertrophy, apoptosis rates and heart fibrosis, respectively. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to detect different mRNA levels, and western blot was applied to assess the expressions of relative proteins. Immunofluorescence staining was used to evaluate α-SMA density. We first found that treatment of selenium alleviated heart fibrosis and the development of heart failure but not cardiomyocyte cross sectional areas. Besides, selenium improved heart levels of superoxide dismutase2 (SOD2), glutathione peroxidase (Gpx) and glutathione (GSH) and the activity of SOD, accompanied by decreased apoptosis rate. In addition, our in vitro study has shown that selenium reduced mRNA levels of collagen Ⅰ and collagen III, expressions of a-SMA, p-AKT/AKT and p-GSK-3β/ GSK-3β, apoptosis rates and reactive oxygen species (ROS) levels in H9C2 cardio-myoblasts treated with TGF-β1. Moreover, the level of Sirt1 was found to be up-regulated by selenium which effects were weakened after the administration of small interfering RNA (siRNA)-Sirt1 or EX527 (inhibitor of Sirt1). Our current results have demonstrated that the protective effects of selenium on heart hypertrophy is through the regulation of Sirt1 and AKT/GSK-3β pathway.

The Epidemiology, Impact, and Diagnosis of Micronutrient Nutritional Dermatoses Part 1: Zinc, Selenium, Copper, Vitamin A, and Vitamin C

Dermatologists play a critical role in diagnosing and managing nutritional deficiencies as they often present with cutaneous findings. Traditionally, nutritional dermatoses are taught in the context of developing countries, famine, population displacement, and poor healthcare access; however, in the United States, common risk factors include chronic liver disease, alcoholism, psychiatric disease, bariatric surgery, inflammatory bowel disease, and hemodialysis. Additionally, nutritional dermatoses may be underdiagnosed in the United States and result in increased morbidity and utilization of hospital resources. There is a need for providers in developed nations to identify these deficiencies, and this review aims to meet that practice gap and provide relevant context to these diseases for dermatologists. This two-part review series will focus on the epidemiology, impact, appearance, and diagnostic modalities for micronutrient deficiencies, including zinc, selenium, copper, and vitamins A and C in part one. The companion review will focus on the B-complex vitamins.

Review article: Emerging issues in pediatric skin of color, part 1

Dermatology for the pediatric skin of color population is the application of dermatology to the genetically diverse and distinctive segment of the pediatric population that includes children of non-White racial and ethnic groups with increased pigmentation including individuals of Asian, LatinX, African, Native American, Pacific Island descent, Indigenous Peoples, among others, with overlap in particular individuals, and mixtures thereof. Treating children of color is a unique skill set within the field of pediatric dermatology, requiring knowledge and sensitivity. The discipline of pediatric skin of color can be challenging. Difficulty in diagnosis of common conditions stems from underlying pigmentation, variations in common hairstyling practices, and differences in demographics of cutaneous disease, whereas some conditions are more common in children of color, other conditions have nuances in clinical appearance and/or therapeutics with regard to skin color. This article is the first in a series of two articles looking at recently published skin-related issues of high concern in children of color. Conditions reviewed in Part 1 include (1) hairstyling hair-related concerns (traction alopecia, central centrifugal cicatricial alopecia, endocrine disruption), (2) autoimmune concerns (cutaneous lupus, vitiligo), and (3) infections (tinea capitis, progressive macular hypomelanosis).

A practical guide to vitiligo differential diagnoses in primary care

ABSTRACT

Primary care providers often encounter different types of pigmentary disorders such as vitiligo. This article arms the provider with the most common vitiligo differential diagnoses, with key findings and tips to identify specific hypopigmentary diseases. Readers will be better-prepared to provide safe and effective care and recommend referrals to appropriate specialties.

Role of Amine Neurotransmitters and Their Receptors in Skin Pigmentation: Therapeutic Implication

Skin pigmentation can occur due to increased melanin, including melanocyte proliferation, melanin biosynthesis, or melanocyte migration. There are many factors that influence the melanin production process, but the role of neurotransmitters in this process is still unclear. We found that histamine and serotonin influence the different stages of melanogenesis and melanogenesis, which increase melanogenesis. Since then, several related papers have been published, and from these papers, it has been recognised that the role of neurotransmitters in skin-pigment-related diseases needs to be summarised. By introducing the role of neurotransmitters in the regulation of various pigment disorders, including vitiligo and melasma, through this review, many researchers can be expected to try to apply neurotransmitter-related agonists and antagonists as treatments for skin pigment disorders.

Clinical Features, Immunopathogenesis, and Therapeutic Strategies in Vitiligo

Vitiligo is an autoimmune disease of the skin characterized by epidermal melanocyte loss resulting in white patches, with an approximate prevalence of 0.5-2% worldwide. Several precipitating factors by chemical exposure and skin injury present commonly in patients with vitiligo. Although the diagnosis appears to be straightforward for the distinct clinical phenotype and specific histological features, vitiligo provides many challenges including chronicity, treatment resistance, frequent relapse, associated profound psychosocial effect, and negative impact on quality of life. Multiple mechanisms are involved in melanocyte disappearance, including genetics, environmental factors, and immune-mediated inflammation. Compelling evidence supports the melanocyte intrinsic abnormalities with poor adaptation to stressors leading to instability and release of danger signals, which will activate dendritic cells, natural killer cells, and innate lymphoid cells to initiate innate immunity, ultimately resulting in T-cell mediated adaptive immune response and melanocyte destruction. Importantly, the cross- talk between keratinocytes, melanocytes, and immune cells, such as interferon (IFN)-γ signaling pathway, builds inflammatory loops that give rise to the disease deterioration. Improved understanding of the immune pathogenesis of vitiligo has led to the development of new therapeutic options including Janus kinase (JAK) inhibitors targeting IFN-γ signaling pathways, which can effectively reverse depigmentation. Furthermore, definition of treatment goals and integration of comorbid diseases into vitiligo management have revolutionized the way vitiligo is treated. In this review, we highlight recent developments in vitiligo clinical aspects and immune pathogenesis. Our key objective is to raise awareness of the complexity of this disease, the potential of prospective therapy strategies, and the need for early and comprehensive management.

Overexpression of NRF1-742 or NRF1-772 Reduces Arsenic-Induced Cytotoxicity and Apoptosis in Human HaCaT Keratinocytes

Increasing evidence indicates that human exposure to inorganic arsenic causes cutaneous diseases and skin cancers. Nuclear factor erythroid 2-like 1 (NRF1) belongs to the cap “n” collar (CNC) basic-region leucine zipper (bZIP) transcription factor family and regulates antioxidant response element (ARE) genes. The human NRF1 gene is transcribed into multiple isoforms, which contain 584, 616, 742, 761, or 772 amino acids. We previously demonstrated that the long isoforms of NRF1 (i.e., NRF1-742, NRF1-761 and NRF1-772) are involved in the protection of human keratinocytes from acute arsenic cytotoxicity by enhancing the cellular antioxidant response. The aim of the current study was to investigate the roles of NRF1-742 and NRF1-772 in the arsenic-induced antioxidant response and cytotoxicity. We found that overexpression of NRF1-742 or NRF1-772 in human HaCaT keratinocytes decreased susceptibility to arsenic-induced apoptosis and cytotoxicity. In addition, we characterized the different protein bands observed for NRF1-742 and NRF1-772 by western blotting. The posttranslational modifications and nuclear translocation of these isoforms differed and were partially affected by arsenic exposure. Antioxidant protein levels were increased in the NRF1-742 and NRF1-772-overexpressing cell lines. The upregulation of antioxidant protein levels was partly due to the translation of nuclear factor erythroid 2-like 2 (NRF2) and its increased nuclear transport. Overall, overexpression of NRF1-742 and NRF1-772 protected HaCaT cells from arsenic-induced cytotoxicity, mainly through translational modifications and the promotion of antioxidant gene expression.

Tinea InVersicolor: A Rare Distribution of a Common Eruption

Tinea versicolor (TV), or pityriasis versicolor, is one of the most commonly occurring superficial mycoses. Typically, this condition is characterized by fine scaly hyper or hypopigmented macules and patches distributed on the trunk and upper extremities. Diagnosis is often based on clinical presentation. A Wood's lamp examination or potassium hydroxide (KOH) preparation test is performed for confirmation. To date, numerous morphologic variants of this condition have been described. Here we present an inverse papular variant that, to our knowledge, has only been previously reported once. This case represents another unique presentation of TV and serves to highlight the clinical variety of this common mycosis.

The color of skin: white diseases of the skin, nails, and mucosa

White diseases are a heterogenous group characterized by hypopigmentation or depigmentation. Skin and eye color are determined by the number and size of melanosomes present. Melanin is produced by melanosomes in the melanocytes present within the epidermis of the skin, uvea, and retinal pigmented epithelium (RPE). Conditions altering the number of melanocytes or concentration of melanin result in a lack of pigmentation, appearing as "white diseases" ranging from the well-known albinism and vitiligo to more esoteric white hand syndrome and Degos disease.