Neuroendocrine signaling in the skin with a special focus on the epidermal neuropeptides

Cutaneous-immuno-neuro-endocrine (CINE) system: A complex enterprise transforming skin into a super organ

Skin is now emerging as a complex realm of three chief systems viz. immune system, nervous system, and endocrine system. The cells involved in their intricate crosstalk, namely native skin cells, intra-cutaneous immune cells and cutaneous sensory neurons have diverse origin and distinct functions. However, recent studies have explored their role beyond their pre-defined functional boundaries, such that the cells shun their traditional functions and adopt unconventional roles. For example, the native skin cells, apart from providing for basic structural framework of skin, also perform special immune functions and participate in extensive neuro-endocrine circuitry, which were traditionally designated as functions of cutaneous resident immune cells and sensory neurons respectively. At the cellular level, this unique collaboration is brought out by special molecules called neuromediators including neurotransmitters, neuropeptides, neurotrophins, neurohormones and cytokines/chemokines. While this intricate crosstalk is essential for maintaining cutaneous homeostasis, its disruption is seen in various cutaneous diseases. Recent study models have led to a paradigm shift in our understanding of pathophysiology of many such disorders. In this review, we have described in detail the interaction of immune cells with neurons and native skin cells, role of neuromediators, the endocrine aspect in skin and current understanding of cutaneous neuro-immuno-endocrine loop in one of the commonest skin diseases, psoriasis. An accurate knowledge of this unique crosstalk can prove crucial in understanding the pathophysiology of different skin diseases and allow for generation of targeted therapeutic modalities.

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.

Epidermal ET-1 signal induces activation of resting hair follicles by upregulating the PI3K/AKT pathway in the dermis

The prevalence of alopecia has increased recently. Hair loss is often accompanied by the resting phase of hair follicles (HFs). Dermal papilla (DP) plays a crucial role in HF development, growth, and regeneration. Activating DP can revive resting HFs. Augmenting WNT/β-catenin signaling stimulates HF growth. However, the factors responsible for activating resting HFs effectively are unclear. In this study, we investigated epidermal cytokines that can activate resting HFs effectively. We overexpressed β-catenin in both in vivo and in vitro models to observe its effects on resting HFs. Then, we screened potential epidermal cytokines from GEO DATASETs and assessed their functions using mice models and skin-derived precursors (SKPs). Finally, we explored the molecular mechanism underlying the action of the identified cytokine. The results showed that activation of WNT/β-catenin in the epidermis prompted telogen-anagen transition. Keratinocytes infected with Ctnnb1-overexpressing lentivirus enhanced SKP expansion. Subsequently, we identified endothelin 1 (ET-1) expressed higher in hair-growing epidermis and induced the proliferation of DP cells and activates telogen-phase HFs in vivo. Moreover, ET-1 promotes the proliferation and stemness of SKPs. Western blot analysis and in vivo experiments revealed that ET-1 induces the transition from telogen-to-anagen phase by upregulating the PI3K/AKT pathway. These findings highlight the potential of ET-1 as a promising cytokine for HF activation and the treatment of hair loss.

Understanding Type 3 Innate Lymphoid Cells and Crosstalk with the Microbiota: A Skin Connection

Innate lymphoid cells (ILCs) are a diverse population of lymphocytes classified into natural killer (NK) cells, ILC1s, ILC2s, ILC3s, and ILCregs, broadly following the cytokine secretion and transcription factor profiles of classical T cell subsets. Nonetheless, the ILC lineage does not have rearranged antigen-specific receptors and possesses distinct characteristics. ILCs are found in barrier tissues such as the skin, lungs, and intestines, where they play a role between acquired immune cells and myeloid cells. Within the skin, ILCs are activated by the microbiota and, in turn, may influence the microbiome composition and modulate immune function through cytokine secretion or direct cellular interactions. In particular, ILC3s provide epithelial protection against extracellular bacteria. However, the mechanism by which these cells modulate skin health and homeostasis in response to microbiome changes is unclear. To better understand how ILC3s function against microbiota perturbations in the skin, we propose a role for these cells in response to Cutibacterium acnes, a predominant commensal bacterium linked to the inflammatory skin condition, acne vulgaris. In this article, we review current evidence describing the role of ILC3s in the skin and suggest functional roles by drawing parallels with ILC3s from other organs. We emphasize the limited understanding and knowledge gaps of ILC3s in the skin and discuss the potential impact of ILC3-microbiota crosstalk in select skin diseases. Exploring the dialogue between the microbiota and ILC3s may lead to novel strategies to ameliorate skin immunity.

Case report: Exceptional disease progression in a 70-year-old patient: generalized melanosis and melanuria in the course of metastatic melanoma - a case study

This case study documents an extraordinary disease progression in a 70-year-old patient diagnosed with metastatic melanoma. The patient's condition advanced to an unusual manifestation characterized by generalized melanosis and melanuria, a rare and foreboding complication of metastatic melanoma. The clinical presentation involved rapid-onset skin darkening, primarily affecting the face and torso, along with darkened urine, marking the onset of melanuria. Despite extensive diagnostic evaluations, including abdominal ultrasound, neck ultrasound, thoracic CT scans, and endoscopic examinations, the exact metastatic sites remained elusive, demonstrating the diagnostic challenges associated with this condition. Laboratory tests revealed abnormal hematological and biochemical markers, along with elevated S100 protein levels, indicating disease progression. The patient underwent a surgical skin biopsy that confirmed the diagnosis of metastatic melanoma, leading to a multidisciplinary approach to treatment. Following this, the patient-initiated chemotherapy with dacarbazine (DTIC). Regrettably, this was necessitated by the absence of reimbursement for BRAF and MEK inhibitors as well as immunotherapy, and it subsequently led to rapid disease progression and a decline in the patient's clinical condition. The patient's condition further complicated with erysipelas and increased distress, ultimately leading to their unfortunate demise. This case highlights the aggressive nature of generalized melanosis, characterized by a rapid clinical course, substantial pigmentation, and limited response to conventional chemotherapy. Importantly, the patient had a BRAF mutation, emphasizing the urgency of exploring alternative treatment strategies. Patients with a BRAF mutation are excellent candidates for BRAF and MEK inhibitor treatment, potentially allowing them to extend their lifespan if this therapy were available. The challenges encountered in diagnosing, managing, and treating this aggressive form of metastatic melanoma underline the need for early detection, tailored therapeutic approaches, and ongoing research efforts to improve patient outcomes in such cases.

Evaluation of Melatonin and its Nanostructures Effects on Skin Disorders Focused on Wound Healing

Skin is the largest organ of the human body functioning as a great primitive defensive barrier against different harmful environmental factors. However, it is damaged through varying injuries such as different wounds, burns, and skin cancers that cause disruption in internal organs and essential mechanisms of the body through inflammation, oxidation, coagulation problems, infection, etc. Melatonin is the major hormone of the pineal gland that is also effective in skin disorders due to strong antioxidant and anti-inflammatory features with additional desirable antiapoptotic, anti-cancer, and antibiotic properties. However, melatonin characteristics require improvements due to its limited water solubility, halflife and stability. The application of nanocarrier systems can improve its solubility, permeability, and efficiency, as well as inhibit its degradation and promote photostability. Our main purpose in the current review is to explore the possible role of melatonin and melatonin-containing nanocarriers in skin disorders focused on wounds. Additionally, melatonin's effect in regenerative medicine and its structures as a wound dressing in skin damage has been considered.

The correlation analysis between alterations of serum vitamin D, IL-33 levels, and clinical improvement after narrow-band UVB treatment in vitiligo patients: A case-control study

BACKGROUND

The etiology of vitiligo has not been completely elucidated. Recently, 25-hydroxyvitamin D (25(OH)D) and IL-33 levels were found to be associated with the development of the vitiligo. The aim was to assess relationship between 25(OH)D, IL-33 levels, and clinical improvement after narrow-band UVB treatment in vitiligo.

METHOD

Patients with vitiligo who underwent at least 48 sessions of narrow-band UVB treatment were included in this study. Age, gender, smoking status, family history of vitiligo, type of vitiligo, body surface area affected by vitiligo, and vitiligo activity were recorded. 25(OH)D and IL-33 were measured and compared at baseline, second month, and fourth month.

RESULTS

Twenty patients with vitiligo and 20 healthy controls were included in this study. The mean baseline 25(OH)D level of vitiligo group was statistically significantly lower than the control group's (p < .05). The mean baseline IL-33 level was higher in vitiligo group with no statistically significantly difference (p > .05). The increase in 25(OH)D level and the decrease in vitiligo-affected body surface area were found to be statistically significant during treatment (p < .05). The mean IL-33 levels were found to be lower at the second and fourth month compared to baseline. However, there were no statistical significance (p > .05).

CONCLUSION

Low levels of 25(OH)D are thought to play a role in the etiopathogenesis of vitiligo. 25(OH)D increase due to phototherapy may have a role in repigmentation independently from the direct effect of narrow-band UVB.

Risk of Melanoma and Non-Melanoma Skin Cancer in Patients with Psoriasis and Psoriatic Arthritis Treated with Targeted Therapies: A Systematic Review and Meta-Analysis

Targeted therapies represent major advancements in the treatment of chronic skin conditions such as psoriasis. While previous studies have shown an increased risk of melanoma and non-melanoma skin cancer (NMSC) in patients receiving TNF-α inhibitors, the risks associated with newer biologics (IL-12/23 inhibitors, IL-23 inhibitors, IL-17 inhibitors) and Janus kinase (JAK) inhibitors remain less known. Using a systematic and meta-analytical approach, we aimed to summarize the currently available literature concerning skin cancer risk in patients treated with targeted therapies. The MEDLINE/PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched to find studies reporting the incidence rates (IR) of melanoma and NMSC in patients with psoriasis and psoriatic arthritis treated with biologics or JAK inhibitors. Nineteen studies were included in the analysis with a total of 13,739 patients. The overall IR of melanoma was 0.08 (95% CI, 0.05-0.15) events per 100 PYs and the overall IR of NMSC was 0.45 (95% CI, 0.33-0.61) events per 100 PYs. The IRs of melanoma were comparable across patients treated with IL-17 inhibitors, IL-23 inhibitors, and JAK inhibitors, while the IRs of NMSC were higher in patients treated with JAK inhibitors than in those treated with biologics. Prospective, long-term cohort studies are required to reliably assess the risks associated with novel targeted therapies.

A review of skin immune processes in acne

Acne vulgaris is one of the most prevalent skin conditions, affecting almost all teenagers worldwide. Multiple factors, including the excessive production of sebum, dysbiosis of the skin microbiome, disruption of keratinization within hair follicles, and local inflammation, are believed to trigger or aggravate acne. Immune activity plays a crucial role in the pathogenesis of acne. Recent research has improved our understanding of the immunostimulatory functions of microorganisms, lipid mediators, and neuropeptides. Additionally, significant advances have been made in elucidating the intricate mechanisms through which cutaneous innate and adaptive immune cells perceive and transmit stimulatory signals and initiate immune responses. However, our understanding of precise temporal and spatial patterns of immune activity throughout various stages of acne development remains limited. This review provides a comprehensive overview of the current knowledge concerning the immune processes involved in the initiation and progression of acne. Furthermore, we highlight the significance of detailed spatiotemporal analyses, including analyses of temporal dynamics of immune cell populations as well as single-cell and spatial RNA sequencing, for the development of targeted therapeutic and prevention strategies.

Pharmacological Effects of Shikonin and Its Potential in Skin Repair: A Review

Currently, skin injuries have a serious impact on people's lives and socio-economic stress. Shikonin, a naphthoquinone compound derived from the root of the traditional Chinese medicine Shikonin, has favorable biological activities such as anti-inflammatory, antibacterial, immunomodulatory, anticancer, and wound-healing-promoting pharmacological activities. It has been reported that Shikonin can be used for repairing skin diseases due to its wide range of pharmacological effects. Moreover, the antimicrobial activity of Shikonin can play a great role in food and can also reduce the number of pathogenic bacteria in food. This paper summarizes the research on the pharmacological effects of Shikonin in recent years, as well as research on the mechanism of action of Shikonin in the treatment of certain skin diseases, to provide certain theoretical references for the clinical application of Shikonin, and also to provides research ideas for the investigation of the mechanism of action of Shikonin in other skin diseases.

The potential role of ubiquitination and deubiquitination in melanogenesis

Melanogenesis is a critical biochemical process in which melanocytes produce melanin, a crucial element involved in the formation of coat colour in mammals. According to several earlier studies, melanocytes' post-translational modifications of proteins primarily control melanogenesis. Among the many post-translational changes that can affect melanin production, ubiquitination and deubiquitination can keep melanin production going by changing how proteins that are related to melanin are broken down or kept stable. Ubiquitination and deubiquitination maintain ubiquitin homeostasis, which is a highly dynamic process in balance under the action of E3 ubiquitin ligase and deubiquitinating enzymes. However, the regulatory mechanisms underlying ubiquitination and deubiquitination in melanogenesis are yet to be thoroughly investigated. As a result, there has been a growing focus on exploring the potential correlation between melanogenesis, ubiquitination and deubiquitination. This study discusses the mechanisms of ubiquitination and deubiquitination in the context of melanogenesis, a crucial process for enhancing mammalian coat coloration and addressing pigment-related diseases.

Comprehensive analysis of necroptotic patterns and associated immune landscapes in individualized treatment of skin cutaneous melanoma

Skin cutaneous melanoma (SKCM) constitutes a malignant cutaneous neoplasm characterized by an exceedingly unfavorable prognosis. Over the past years, necroptosis, a manifestation of inflammatory programmed cell demise, has gained substantial traction in its application. However, a conclusive correlation between the expression of necroptosis-related genes (NRGs) and SKCM patient's prognosis remains elusive. In this endeavor, we have undertaken an integrative analysis of genomic data, aiming to provide an exhaustive evaluation of the intricate interplay between melanoma necroptosis and immune-infiltration nuances within the tumor microenvironment. Through meticulous scrutiny, we have endeavored to discern the prognostic potency harbored by individual necroptosis-associated genes. Our efforts culminated in the establishment of a risk stratification framework, allowing for the appraisal of necroptosis irregularities within each afflicted cutaneous melanoma patient. Notably, those SKCM patients classified within the low-risk cohort exhibited a markedly elevated survival quotient, in stark contrast to their high-risk counterparts (p < 0.001). Remarkably, the low-risk cohort not only displayed a more favorable survival rate but also exhibited an enhanced responsiveness to immunotherapeutic interventions, relative to their high-risk counterparts. The outcomes of this investigation proffer insights into a conceivable mechanistic underpinning linking necroptosis-related attributes to the intricacies of the tumor microenvironment. This prompts a conjecture regarding the plausible association between necroptosis characteristics and the broader tumor microenvironmental milieu. However, it is imperative to emphasize that the pursuit of discerning whether the expression profiles of NRG genes can indeed be regarded as viable therapeutic targets necessitates further comprehensive exploration and scrutiny. In conclusion, our study sheds light on the intricate interrelationship between necroptosis-related factors and the tumor microenvironment, potentially opening avenues for therapeutic interventions. However, the prospect of translating these findings into clinical applications mandates rigorous investigation.

Stress aggravates imiquimod-induced psoriasiform inflammation by promoting M1 macrophage polarization

Psychological stress has long been considered to cause the aggravation and recurrence of psoriasis, but the underlying mechanism remains largely unknown. Here, we used a mouse model of restraint-induced stress and imiquimod (IMQ)-induced psoriasiform inflammation to investigate the crosstalk between stress and the skin immune system and their functions in the pathogenesis of psoriasis. We found that stress aggravated skin inflammation and elevated serum corticosterone (CORT) levels in mice. Stress also increased the number of macrophages and glucocorticoid receptor (GR) expression in IMQ-treated mouse skin. GR agonist CORT upregulated the phosphorylation of STAT1 to promote M1 macrophage polarization in vitro. Additionally, GR deletion in macrophages and pharmacologic inhibition of GR improved skin inflammation and reduced M1 macrophage polarization under stress. Taken together, these results indicate that stress aggravates psoriasiform inflammation by promoting CORT/GR signaling-induced M1 macrophage polarization, suggesting that blocking the GR signaling has great potential as an adjuvant treatment for psoriasis patients with chronic stress.

Environmental influences on induction of itching and scratching using immersive virtual reality

Chronic itching is a serious and uncomfortable condition. The scratch response might result in a vicious cycle of alternating itching and scratching. To develop psychological interventions for people suffering from chronic itching and to break the vicious itch-scratching-itch cycle, it is important to elucidate which environmental factors trigger itch sensations. Virtual reality (VR) techniques provide a useful tool to examine specific content characteristics in a three-dimensional (3D VR) environment and their influences on itch sensations and scratching behaviour. This article describes two experiments in which we focused on the effects of environmental information on itching and scratching behaviour. Additionally, in the second experiment, we examined the influence of having a chronic skin condition on sensitivity to itch induction. We found evidence for the importance of the content of audio-visual materials for the effectiveness in inducing feelings of itch in the observers. In both experiments, we observed significantly higher levels of perceived itch in the itch-inducing conditions than in the control condition. Moreover, the results showed that elevated levels of perceived itch were associated with an increase in scratching behaviours, which was especially salient in the contagious itch condition, in which perceived itch was accompanied by a significant increase in the number of scratches. Experiment 2 additionally showed increased perceived itch levels in participants who reported having a chronic skin condition, reflecting higher sensitivity to itch-inducing audio-visual stimuli in this group than in participants without a chronic skin condition. Based on the results we concluded that directing attention towards itch- or scratch aspects of related information in the environment and to the consequences for one's own skin are effective tools to induce itch sensations and scratching behaviour. This knowledge provides tools for developing novel strategies in advising and treating people suffering from chronic itching and breaking the vicious itch-scratching-itch cycle.

Modulation of Piezo1 influences human skin architecture and oxytocin expression

OBJECTIVE

Throughout our existence, the skin senses and analyses the mechanical forces imposed by the environment. In response to these environmental forces, skin can deform itself and achieve a biological response. The subsequent cutaneous plasticity emerges from mechanical properties arising from the collective action of the skin cells, particularly keratinocytes, that govern the tensile strength via cell-to-cell adhesions and via cell-matrix adhesion structures. In addition to serving as force-bearing entities, keratinocytes respond to forces by activating signalling pathways to control their own fate and function. To detect and adapt to mechanical signals, keratinocytes possess a panel of sensory receptors and junctional intercellular structures. Mechanically activated ion channel Piezo1 has been described as a force sensor and as being involved in pleasant touch perception. In this study, relationships between Piezo1 modulation and oxytocin synthesis were investigated.

METHODS

The expression of Piezo1 in the skin was studied and compared with the expression of TRPV1. Dooku1 antagonist and Jedi1 agonist were used to modulate Piezo1. The level of E-cadherin and oxytocin was monitored in ex vivo skin biopsies by immunodetection.

RESULTS

Taken together, our results illustrate the major role of mechanosensitive ion channel Piezo1 in skin barrier integrity, and in peripheral oxytocin synthesis in the skin.

CONCLUSION

In conclusion, this study highlights the relationships between pleasant touch, soft touch and local oxytocin synthesis.

Incidence of neurocutaneous melanosis in Japanese pediatric patients with congenital melanocytic nevi

Neurocutaneous melanosis (NCM) is a rare, non-hereditary neurocutaneous disorder characterized by excessive melanocytic proliferation in the skin and central nervous system. As no major studies have covered the incidence of NCM among Japanese patients with congenital melanocytic nevi (CMN), we prospectively investigated the incidence of NCM among Japanese patients who underwent initial treatment for CMN. The relationship of CMN and NCM was also investigated. Japanese pediatric patients with CMN under 1 year of age were included between January 2020 and November 2022, and all patients underwent brain MRI to check for NCM in this study. NCM lesions were most frequently seen in the amygdala, followed by the cerebellum, brainstem, and cerebral hemispheres. NCM was diagnosed on brain MRI in 31.6% of the 38 patients with CMN and in 25.0% of patients with no prior examination or treatment. Distribution and size of CMN, number of satellite nevi, rugosity and nodules were strongly associated with the existence of NCM, and these findings may guide a future registry study with a large cohort of CMN patients.

Anhydrous Alum Inhibits α-MSH-Induced Melanogenesis by Down-Regulating MITF via Dual Modulation of CREB and ERK

Melanogenesis, the intricate process of melanin synthesis, is central to skin pigmentation and photoprotection and is regulated by various signaling pathways and transcription factors. To develop potential skin-whitening agents, we used B16F1 melanoma cells to investigate the inhibitory effects of anhydrous alum on melanogenesis and its underlying molecular mechanisms. Anhydrous alum (KAl(SO4)2) with high purity (>99%), which is generated through the heat-treatment of hydrated alum (KAl(SO4)2·12H2O) at 400 °C, potentiates a significant reduction in melanin content without cytotoxicity. Anhydrous alum downregulates the master regulator of melanogenesis, microphthalmia-associated transcription factor (MITF), which targets key genes involved in melanogenesis, thereby inhibiting α-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis. Phosphorylation of the cAMP response element-binding protein, which acts as a co-activator of MITF gene expression, is attenuated by anhydrous alum, resulting in compromised MITF transcription. Notably, anhydrous alum promoted extracellular signal-regulated kinase phosphorylation, leading to the impaired nuclear localization of MITF. Overall, these results demonstrated the generation and mode of action of anhydrous alum in B16F1 cells, which constitutes a promising option for cosmetic or therapeutic use.

Dual Action of Curcumin as an Anti- and Pro-Oxidant from a Biophysical Perspective

Curcumin, a natural polyphenol widely used as a spice, colorant and food additive, has been shown to have therapeutic effects against different disorders, mostly due to its anti-oxidant properties. Curcumin also reduces the efficiency of melanin synthesis and affects cell membranes. However, curcumin can act as a pro-oxidant when blue light is applied, since upon illumination it can generate singlet oxygen. Our review aims to describe this dual role of curcumin from a biophysical perspective, bearing in mind its concentration, bioavailability-enhancing modifications and membrane interactions, as well as environmental conditions such as light. In low concentrations and without irradiation, curcumin shows positive effects and can be recommended as a beneficial food supplement. On the other hand, when used in excess or irradiated, curcumin can be toxic. Therefore, numerous attempts have been undertaken to test curcumin as a potential photosensitizer in photodynamic therapy (PDT). At that point, we underline that curcumin-based PDT is limited to the treatment of superficial tumors or skin and oral infections due to the weak penetration of blue light. Additionally, we conclude that an increase in curcumin bioavailability through the using nanocarriers, and therefore its concentration, as well as its topical use if skin is exposed to light, may be dangerous.

From gut to skin: exploring the potential of natural products targeting microorganisms for atopic dermatitis treatment

Atopic dermatitis (AD) is the most common chronic inflammatory skin disease. Recent studies have revealed that interactions between pathogenic microorganisms, which have a tendency to parasitize the skin of AD patients, play a significant role in the progression of the disease. Furthermore, specific species of commensal bacteria in the human intestinal tract can have a profound impact on the immune system by promoting inflammation and pruritogenesis in AD, while also regulating adaptive immunity. Natural products (NPs) have emerged as promising agents for the treatment of various diseases. Consequently, there is growing interest in utilizing natural products as a novel therapeutic approach for managing AD, with a focus on modulating both skin and gut microbiota. In this review, we discuss the mechanisms and interplay between the skin and gut microbiota in relation to AD. Additionally, we provide a comprehensive overview of recent clinical and fundamental research on NPs targeting the skin and gut microbiota for AD treatment. We anticipate that our work will contribute to the future development of NPs and facilitate research on microbial mechanisms, based on the efficacy of NPs in treating AD.

Therapeutic Potential of Minor Cannabinoids in Dermatological Diseases-A Synthetic Review

Dermatological diseases pose a significant burden on the quality of life of individuals and can be challenging to treat effectively. In this aspect, cannabinoids are gaining increasing importance due to their therapeutic potential in various disease entities including skin diseases. In this synthetic review, we comprehensively analyzed the existing literature in the field of potential dermatological applications of a lesser-known subgroup of cannabinoids, the so-called minor cannabinoids, such as cannabidivarin (CBDV), cannabidiforol (CBDP), cannabichromene (CBC), tetrahydrocannabivarin (THCV), cannabigerolic acid (CBGA), cannabigerol (CBG), cannabielsoin (CBE), cannabimovone (CBM) or cannabinol (CBN), while drawing attention to their unique pharmacological properties. We systematically searched the available databases for relevant studies and analyzed the data to provide an overview of current thematic knowledge. We looked through the full-text, bibliographic and factographic databases, especially Scopus, Web of Science, PubMed, Polish Scientific Journals Database, and selected the most relevant papers. Our review highlights that minor cannabinoids exhibit diverse pharmacological activities, including anti-inflammatory, analgesic, antimicrobial, and anti-itch properties. Several studies have reported their efficacy in mitigating symptoms associated with dermatological diseases such as psoriasis, eczema, acne, and pruritus. Furthermore, minor cannabinoids have shown potential in regulating sebum production, a crucial factor in acne pathogenesis. The findings of this review suggest that minor cannabinoids hold therapeutic promise in the management of dermatological diseases. Further preclinical and clinical investigations are warranted to elucidate their mechanisms of action, determine optimal dosage regimens, and assess long-term safety profiles. Incorporating minor cannabinoids into dermatological therapies could potentially offer novel treatment options of patients and improve their overall well-being.

Insights into Nutritional Strategies in Psoriasis

Psoriasis, an autoimmune chronic inflammatory skin condition, has a high incidence in the general population, reaching 2-4%. Its pathogenesis involves an interplay of genetic factors, immune disturbances, and environmental factors. Within the environmental factors that aid the appearance of this autoimmune skin disease, the Western lifestyle and overall diet play important roles in the steady growth in psoriasis prevalence. Furthermore, psoriasis is associated with comorbidities such as psoriatic arthritis, cardiovascular disease, metabolic syndrome, and obesity. Accumulating evidence suggests that obesity is an important risk factor for psoriasis. Moreover, obesity aggravates established psoriasis, and a reduction in the body mass index can improve the clinical outcomes of psoriasis and increase the efficacy of standard psoriasis therapies. The possible connection between this autoimmune disease and obesity relies on the fact that white adipose tissue is an essential endocrine organ that secretes an array of immune mediators and inflammatory and metabolic factors with pro-inflammatory action. Thus, immune-mediated mechanisms in both psoriasis and obesity conditions are common factors. This paper describes the factors that link obesity with skin autoimmune disease and highlights the importance of the stimulatory or regulatory effects of nutrients and food in psoriasis and the possible improvement of psoriasis through nutritional strategies.

Disrupting Hedgehog signaling in melanocytes by SUFU knockout leads to ocular melanocytosis and anterior segment malformation

Hedgehog (Hh) signaling is well known for its crucial role during development, but its specific role in individual cell lineages is less well characterized. Here, we disrupted Hh signaling specifically in melanocytes by using Cre-mediated cell-type-specific knockout of the Hh regulator suppressor of fused (Sufu). Interestingly, corresponding mice were fully pigmented and showed no developmental alterations in melanocyte numbers or distribution in skin and hair follicles. However, there were ectopic melanoblasts visible in the anterior chamber of the eye that eventually displayed severe malformation. Choroidal melanocytes remained unaltered. Surprisingly, the abnormal accumulation of anterior uveal melanoblasts was not the result of increased cell proliferation but of increased migration to ectopic locations such as the cornea. In melanoblasts in vitro, Sufu knockdown replicated the increase in cell migration without affecting proliferation and was mediated by an increased level of phosphorylated-ERK brought about by a reduction in the levels of the repressor form of GLI3. These results highlight the developmental divergence of distinct melanocyte subpopulations and may shed light on the pathogenesis of human ocular melanocytosis.

Research Progress on Skin Aging and Active Ingredients

With the advancement of living standards in modern society and the emergence of an aging population, an increasing number of people are becoming interested in the topic of aging and anti-aging. An important feature of aging is skin aging, and women are particularly concerned about skin aging. In the field of cosmetics, the market share of anti-aging products is increasing year by year. This article reviews the research and development progress of skin aging and related active compounds both domestically and internationally in recent years. The results show that, in terms of the research on skin aging, the popular theories mainly include free radicals and oxidative stress theory, inflammation theory, photoaging theory, and nonenzymatic glycosyl chemistry theory. In terms of research on the active ingredients with anti-aging activities in the skin, there are numerous reports on related products in clinical studies on human subjects, animal experiments, and experimental studies on cell cultures, with a variety of types. Most of the compounds against skin aging are sourced from natural products and their action mechanisms are mainly related to scavenging oxygen free radicals and enhancing antioxidant defenses. This review provides important references for the future research of skin aging and the development of related products. Although there is a great progress in skin aging including related active ingredients, ideal compounds or products are still lacking and need to be further validated. New mechanisms of skin aging, new active ingredients sourced from natural and artificial products, and new pharmaceutical forms including further clinical validations should be further investigated in the future.

Ultraviolet Radiation-Induced Mitochondrial Disturbances Are Attenuated by Metabolites of Melatonin in Human Epidermal Keratinocytes

Melatonin (N-acetyl-5-methoxytryptamine) is recognized as an effective antioxidant produced by the pineal gland, brain and peripheral organs, which also has anti-inflammatory, immunomodulatory, and anti-tumour capacities. Melatonin has been reported as a substance that counteracts ultraviolet radiation B (UVB)-induced intracellular disturbances. Nevertheless, the mechanistic actions of related molecules including its kynurenic derivatives (N1-acetyl-N2-formyl-5-methoxykynurenine (AFMK)), its indolic derivatives (6-hydroxymelatonin (6(OH)MEL) and 5-methoxytryptamine (5-MT)) and its precursor N-acetylserotonin (NAS) are only poorly understood. Herein, we treated human epidermal keratinocytes with UVB and assessed the protective effect of the studied substances in terms of the maintenance of mitochondrial function or their radical scavenging capacity. Our results show that UVB caused the significant elevation of catalase (CAT) and superoxide dismutase (Mn-SOD), the dissipation of mitochondrial transmembrane potential (mtΔΨ), a reduction in ATP synthesis, and the enhanced release of cytochrome c into cytosol, leading subsequently to UVB-mediated activation of the caspases and apoptosis (appearance of sub-G1 population). Our findings, combined with data reported so far, indicate the counteracting and beneficial actions of melatonin and its molecular derivatives against these deleterious changes within mitochondria. Therefore, they define a path to the development of novel strategies delaying mitochondrial aging and promoting the well-being of human skin.

Macrophage migration inhibitory factor (MIF) and its homolog D-dopachrome tautomerase (D-DT) are significant promotors of UVB- but not chemically induced non-melanoma skin cancer

Non-melanoma skin cancer (NMSC) is the most common cancer in Caucasians worldwide. We investigated the pathophysiological role of MIF and its homolog D-DT in UVB- and chemically induced NMSC using Mif-/-, D-dt-/- and Mif-/-/D-dt-/- mice on a hairless SKH1 background. Knockout of both cytokines showed similar attenuating effects on inflammation after acute UVB irradiation and tumor formation during chronic UVB irradiation, without additive protective effects noted in double knockout mice, indicating that both cytokines activate a similar signaling threshold. In contrast, genetic deletion of Mif and D-dt had no major effects on chemically induced skin tumors. To get insight into the contributing mechanisms, we used an in vitro 3D skin model with incorporated macrophages. Application of recombinant MIF and D-DT led to an accumulation of macrophages within the epidermal part that could be reversed by selective inhibitors of MIF and D-DT pathways. In summary, our data indicate that MIF and D-DT contribute to the development and progression of UVB- but not chemically induced NMSC, a role at least partially accounted by effects of both cytokines on epidermal macrophage accumulation. These data highlight that MIF and D-DT are both potential therapeutic targets for the prevention of photocarcinogenesis but not chemical carcinogenesis.

Anti-Fibrotic Effects of RF Electric Currents

Hypertrophic scars and keloids are two different manifestations of excessive dermal fibrosis and are caused by an alteration in the normal wound-healing process. Treatment with radiofrequency (RF)-based therapies has proven to be useful in reducing hypertrophic scars. In this study, the effect of one of these radiofrequency therapies, Capacitive Resistive Electrical Transfer Therapy (CRET) on biomarkers of skin fibrosis was investigated. For this, in cultures of human myofibroblasts treated with CRET therapy or sham-treated, proliferation (XTT Assay), apoptosis (TUNEL Assay), and cell migration (Wound Closure Assay) were analyzed. Furthermore, in these cultures the expression and/or localization of extracellular matrix proteins such as α-SMA, Col I, Col III (immunofluorescence), metalloproteinases MMP1 and MMP9, MAP kinase ERK1/2, and the transcription factor NFκB were also investigated (immunoblot). The results have revealed that CRET decreases the expression of extracellular matrix proteins, modifies the expression of the metalloproteinase MMP9, and reduces the activation of NFκB with respect to controls, suggesting that this therapy could be useful for the treatment of fibrotic pathologies.

Resistance training rejuvenates aging skin by reducing circulating inflammatory factors and enhancing dermal extracellular matrices

Aerobic training (AT) is suggested to be an effective anti-aging strategy for skin aging. However, the respective effects of resistance training (RT) have not been studied. Therefore, we compared the effects of AT and RT on skin aging in a 16-week intervention in 61 healthy sedentary middle-aged Japanese women. Data from 56 women were available for analysis. Both interventions significantly improved skin elasticity and upper dermal structure, and RT also improved dermal thickness. After the training intervention, expression of dermal extracellular matrix-related genes was increased in normal human primary dermal fibroblasts. AT and RT had different effects on circulating levels of factors, such as cytokines, hormones in serum, and metabolites, and RT increased dermal biglycan (BGN). To our knowledge, this is the first report to show different effects of AT and RT on skin aging and identify the key factors involved in RT-induced skin rejuvenation.

Environmental Air Pollutants Affecting Skin Functions with Systemic Implications

The increase in air pollution worldwide represents an environmental risk factor that has global implications for the health of humans worldwide. The skin of billions of people is exposed to a mixture of harmful air pollutants, which can affect its physiology and are responsible for cutaneous damage. Some polycyclic aromatic hydrocarbons are photoreactive and could be activated by ultraviolet radiation (UVR). Therefore, such UVR exposure would enhance their deleterious effects on the skin. Air pollution also affects vitamin D synthesis by reducing UVB radiation, which is essential for the production of vitamin D3, tachysterol, and lumisterol derivatives. Ambient air pollutants, photopollution, blue-light pollution, and cigarette smoke compromise cutaneous structural integrity, can interact with human skin microbiota, and trigger or exacerbate a range of skin diseases through various mechanisms. Generally, air pollution elicits an oxidative stress response on the skin that can activate the inflammatory responses. The aryl hydrocarbon receptor (AhR) can act as a sensor for small molecules such as air pollutants and plays a crucial role in responses to (photo)pollution. On the other hand, targeting AhR/Nrf2 is emerging as a novel treatment option for air pollutants that induce or exacerbate inflammatory skin diseases. Therefore, AhR with downstream regulatory pathways would represent a crucial signaling system regulating the skin phenotype in a Yin and Yang fashion defined by the chemical nature of the activating factor and the cellular and tissue context.

Hyperglycemia-activated 11β-hydroxysteroid dehydrogenase type 1 increases endoplasmic reticulum stress and skin barrier dysfunction

The diabetes mellitus (DM) skin shows skin barrier dysfunction and skin lipid abnormality, similar to conditions induced by systemic or local glucocorticoid excess and aged skin. Inactive glucocorticoid (GC) is converted into active glucocorticoid by 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1). Hyperglycemia in DM and excessive GC are known to increase endoplasmic reticulum (ER) stress. We hypothesized that hyperglycemia affects systemic GC homeostasis and that the action of skin 11β-HSD1 and GC contributes to increased ER stress and barrier defects in DM. We compared 11β-HSD1, active GC, and ER stress between hyperglycemic and normoglycemic conditions in normal human keratinocytes and db/db mice. 11β-HSD1 and cortisol increased with time in keratinocyte culture under hyperglycemic conditions. 11β-HSD1 siRNA-transfected cells did not induce cortisol elevation in hyperglycemic condition. The production of 11β-HSD1 and cortisol was suppressed in cell culture treated with an ER stress-inhibitor. The 14-week-old db/db mice showed higher stratum corneum (SC) corticosterone, and skin 11β-HSD1 levels than 8-week-old db/db mice. Topical 11β-HSD1 inhibitor application in db/db mice decreased SC corticosterone levels and improved skin barrier function. Hyperglycemia in DM may affect systemic GC homeostasis, activate skin 11β-HSD1, and induce local GC excess, which increases ER stress and adversely affects skin barrier function.

Melatonin and Kidney Health: From Fetal Stage to Later Life

Melatonin, an endogenous hormone mainly released at night by the pineal gland, has multifaceted biofunctions. Emerging evidence points to melatonin having a crucial role in kidney health and disease. As the prevalence of chronic kidney disease (CKD) is still rising, a superior strategy to advance global kidney health is needed to not just treat CKD, but prevent it early on. Adult kidney disease can have its origins in early life. This review aims to evaluate the recent literature regarding melatonin's effect on kidney development, its clinical uses in the early stage of life, animal models documenting preventive applications of melatonin on offspring's kidney-related disease, and a thorough summary of therapeutic considerations concerning melatonin supplementation.

The Melatonin-Mitochondrial Axis: Engaging the Repercussions of Ultraviolet Radiation Photoaging on the Skin's Circadian Rhythm

Sunlight is a vital element in modulating the central circadian rhythm, such as the regulation of the host's sleep-awake state. Sunlight is also considered to have a significant influence on the circadian rhythm of the skin. Over-exposure or prolonged exposure to sunlight can lead to skin photodamage, including hyperpigmentation, collagen degradation, fibrosis, and even skin cancer. Thus, this review will focus on the adverse effects of sunlight on the skin, not only in terms of photoaging but also its effect on the skin's circadian rhythm. Mitochondrial melatonin, regarded as a beneficial anti-aging substance for the skin, follows a circadian rhythm and exhibits a powerful anti-oxidative capacity, which has been shown to be associated with skin function. Thus, the review will focus on the influence of sunlight on skin status, not only in terms of ultraviolet radiation (UVR)-induced oxidative stress but also its mediation of circadian rhythms regulating skin homeostasis. In addition, this article will address issues regarding how best to unleash the biological potential of melatonin. These findings about the circadian rhythms of the skin have broadened the horizon of a whole new dimension in our comprehension of the molecular mechanisms of the skin and are likely to help pharmaceutical companies to develop more effective products that not only inhibit photoaging but keep valid and relevant throughout the day in future.

Hydrolyzed Conchiolin Protein (HCP) Extracted from Pearls Antagonizes both ET-1 and α-MSH for Skin Whitening

Pearl powder is a famous traditional Chinese medicine that has a long history in treating palpitations, insomnia, convulsions, epilepsy, ulcers, and skin lightining. Recently, several studies have demonstrated the effects of pearl extracts on protection of ultraviolet A (UVA) induced irritation on human skin fibroblasts and inhibition of melanin genesis on B16F10 mouse melanoma cells. To further explore the effect we focused on the whitening efficacy of pearl hydrolyzed conchiolin protein (HCP) on human melanoma MNT-1 cells under the irritation of alpha-melanocyte-stimulating hormone (α-MSH) or endothelin 1 (ET-1) to evaluate the intracellular tyrosinase and melanin contents, as well as the expression levels of tyrosinase (TYR), tyrosinase related protein 1 (TRP-1), and dopachrome tautomerase (DCT) genes and related proteins. We found that HCP could decrease the intracellular melanin content by reducing the activity of intracellular tyrosinase and inhibiting the expression of TYR, TRP-1, DCT genes and proteins. At the same time, the effect of HCP on melanosome transfer effect was also investigated in the co-culture system of immortalized human keratinocyte HaCaT cells with MNT-1. The result indicated that HCP could promote the transfer of melanosomes in MNT-1 melanocytes to HaCaT cells, which might accelerate the skin whitening process by quickly transferring and metabolizing melanosomes during keratinocyte differentiation. Further study is needed to explore the mechanism of melanosome transfer with depigmentation.

Melatonin inhibits senescence-associated melanin pigmentation through the p53-TYR pathway in human primary melanocytes and the skin of C57BL/6 J mice after UVB irradiation

UVB exposure accelerates skin aging and pigmentation. Melatonin effectively regulates tyrosinase (TYR) activity and aging. The purpose of this study was to determine the association between premature senescence and pigmentation, and the mechanism of melanin synthesis effected by melatonin. Primary melanocytes were extracted and identified from the male foreskin. To inhibit TYR expression, primary melanocytes were transduced with the lentivirus pLKD-CMV-EGFP-2A-Puro-U6-TYR. The wild-type TYR^(+/+) and TYR^(-/-) or TYR^(+/-) knockout C57BL/6 J mice were used to determine the role of TYR on melanin synthesis in vivo. Results showed that UVB-induced melanin synthesis is dependent on TYR in primary melanocytes and mice. Furthermore, in primary melanocytes pretreated with Nutlin-3 or PFT-α to up or downregulate p53, results showed that premature senescence and melanin synthesis increased in primary melanocytes after UVB irradiation at 80 mJ/cm², and further increased after being treated with Nutlin-3, while significantly decreased with PFT-α. In addition, melatonin inhibited UVB-induced premature senescence associated with inactivation of p53 and phosphorylation of p53 on Ser15 (ser-15), a decrease of melanin synthesis accompanied by reduced TYR expression. Moreover, skin erythema and pigmentation induced by UVB were reduced in the dorsal and ear skin of mice topically pretreated with 2.5% melatonin. These indicate that melatonin inhibits UVB-induced senescence-associated pigmentation via the p53-TYR pathway in primary melanocytes and prevents pigmentation obviously in the dorsal and ear skin of C57BL/6 J mice after UVB irradiation. KEY MESSAGES: P53 links UVB irradiation-induced senescence and senescence-associated pigmentation and regulates TYR in primary melanocytes after UVB irradiation. Melatonin inhibits senescence-associated pigmentation through the p53-TYR pathway in primary melanocytes. Melatonin prevents skin erythema and melanin pigmentation induced by UVB irradiation in the dorsal and ear skin of C57BL/6J mice.

How cancer hijacks the body's homeostasis through the neuroendocrine system

During oncogenesis, cancer not only escapes the body's regulatory mechanisms, but also gains the ability to affect local and systemic homeostasis. Specifically, tumors produce cytokines, immune mediators, classical neurotransmitters, hypothalamic and pituitary hormones, biogenic amines, melatonin, and glucocorticoids, as demonstrated in human and animal models of cancer. The tumor, through the release of these neurohormonal and immune mediators, can control the main neuroendocrine centers such as the hypothalamus, pituitary, adrenals, and thyroid to modulate body homeostasis through central regulatory axes. We hypothesize that the tumor-derived catecholamines, serotonin, melatonin, neuropeptides, and other neurotransmitters can affect body and brain functions. Bidirectional communication between local autonomic and sensory nerves and the tumor, with putative effects on the brain, is also envisioned. Overall, we propose that cancers can take control of the central neuroendocrine and immune systems to reset the body homeostasis in a mode favoring its expansion at the expense of the host.

Effect of Ultraviolet Radiation and Benzo[a]pyrene Co-Exposure on Skin Biology: Autophagy as a Potential Target

The skin is the outermost protective barrier of the human body. Its role is to protect against different physical, chemical, biological and environmental stressors. The vast majority of studies have focused on investigating the effects of single environmental stressors on skin homeostasis and the induction of several skin disorders, such as cancer or ageing. On the other hand, much fewer studies have explored the consequences of the co-exposure of skin cells to two or more stressors simultaneously, which is much more realistic. In the present study, we investigated, using mass-spectrometry-based proteomic analysis, the dysregulated biological functions in skin explants after their co-exposure to ultraviolet radiation (UV) and benzo[a]pyrene (BaP). We observed that several biological processes were dysregulated, among which autophagy appeared to be significantly downregulated. Furthermore, immunohistochemistry analysis was carried out to validate the downregulation of the autophagy process further. Altogether, the output of this study provides an insight into the biological responses of skin to combined exposure to UV + BaP and highlights autophagy as a potential target that might be considered in the future as a novel candidate for pharmacological intervention under such stress conditions.

Radiofrequency Irradiation Attenuated UVB-Induced Skin Pigmentation by Modulating ATP Release and CD39 Expression

Hyperpigmentation stimulated by ultraviolet (UV)-induced melanin overproduction causes various cosmetic problems. UV radiation’s activation of the cyclic adenosine monophosphate (cAMP)-mediated cAMP-dependent protein kinase (PKA)/cAMP response element-binding protein (CREB)/microphthalmia-associated transcription factor (MITF) pathway is the main pathway for melanogenesis. However, the secretion of adenosine triphosphate (ATP) from keratinocytes due to UV radiation also leads to melanogenesis. Adenosine, converted from ATP by CD39 and CD73, can activate adenylate cyclase (AC) activity and increase intracellular cAMP expression. cAMP-mediated PKA activation results in dynamic mitochondrial changes that affect melanogenesis via ERK. We evaluated whether radiofrequency (RF) irradiation could decrease ATP release from keratinocytes and suppress the expression of CD39, CD73, and A2A/A2B adenosine receptors (ARs) and the activity of AC and downregulate the PKA/CREB/MITF pathway, which would eventually decrease melanogenesis in vitro in UV-irradiated cells and animal skin. Our results indicate that RF decreased ATP release from UVB-irradiated keratinocytes. When conditioned media (CM) from UVB-irradiated keratinocytes (CM-UVB) were administered to melanocytes, the expressions of CD39, CD73, A2A/A2BARs, cAMP, and PKA increased. However, the expression of these factors decreased when CM from UVB and RF-irradiated keratinocytes (CM-UVB/RF) was administered to melanocytes. The phosphorylation of DRP1 at Ser637, which inhibits mitochondrial fission, increased in UVB-irradiated animal skin and was decreased by RF irradiation. The expression of ERK1/2, which can degrade MITF, was increased using RF treatment in UVB-irradiated animal skin. Tyrosinase activity and melanin levels in melanocytes increased following CM-UVB administration, and these increases were reversed after CD39 silencing. Tyrosinase activity and melanin levels in melanocytes were decreased by CM-UVB/RF irradiation. In conclusion, RF irradiation decreased ATP release from keratinocytes and the expressions of CD39, CD73, and A2A/A2BARs, which decreased AC activity in melanocytes. RF irradiation downregulated the cAMP-mediated PKA/CREB/MITF pathway and tyrosinase activity, and these inhibitory effects can be mediated via CD39 inhibition.

Molecular Mechanisms of Neurogenic Inflammation of the Skin

The skin, including the hypodermis, is the largest body organ and is in constant contact with the environment. Neurogenic inflammation is the result of the activity of nerve endings and mediators (neuropeptides secreted by nerve endings in the development of the inflammatory reaction in the skin), as well as interactions with other cells such as keratinocytes, Langerhans cells, endothelial cells and mast cells. The activation of TRPV-ion channels results in an increase in calcitonin gene-related peptide (CGRP) and substance P, induces the release of other pro-inflammatory mediators and contributes to the maintenance of cutaneous neurogenic inflammation (CNI) in diseases such as psoriasis, atopic dermatitis, prurigo and rosacea. Immune cells present in the skin (mononuclear cells, dendritic cells and mast cells) also express TRPV1, and their activation directly affects their function. The activation of TRPV1 channels mediates communication between sensory nerve endings and skin immune cells, increasing the release of inflammatory mediators (cytokines and neuropeptides). Understanding the molecular mechanisms underlying the generation, activation and modulation of neuropeptide and neurotransmitter receptors in cutaneous cells can aid in the development of effective treatments for inflammatory skin disorders.

Recent Advances and Progress on Melanin: From Source to Application

Melanin is a biological pigment formed by indoles and phenolic compounds. It is widely found in living organisms and has a variety of unique properties. Due to its diverse characteristics and good biocompatibility, melanin has become the focus in the fields of biomedicine, agriculture, the food industry, etc. However, due to the wide range of melanin sources, complex polymerization properties, and low solubility of specific solvents, the specific macromolecular structure and polymerization mechanism of melanin remain unclear, which significantly limits the further study and application of melanin. Its synthesis and degradation pathways are also controversial. In addition, new properties and applications of melanin are constantly being discovered. In this review, we focus on the recent advances in the research of melanin in all aspects. Firstly, the classification, source, and degradation of melanin are summarized. Secondly, a detailed description of the structure, characterization, and properties of melanin is followed. The novel biological activity of melanin and its application is described at the end.

A mechanistic evaluation of human beta defensin 2 mediated protection of human skin barrier in vitro

The human skin barrier, a biological imperative, is impaired in inflammatory skin diseases such as atopic dermatitis (AD). Staphylococcus aureus is associated with AD lesions and contributes to pathological inflammation and further barrier impairment. S. aureus secretes extracellular proteases, such as V8 (or 'SspA'), which cleave extracellular proteins to reduce skin barrier. Previous studies demonstrated that the host defence peptide human beta-defensin 2 (HBD2) prevented V8-mediated damage. Here, the mechanism of HBD2-mediated barrier protection in vitro is examined. Application of exogenous HBD2 provided protection against V8, irrespective of timeline of application or native peptide folding, raising the prospect of simple peptide analogues as therapeutics. HBD2 treatment, in context of V8-mediated damage, modulated the proteomic/secretomic profiles of HaCaT cells, altering levels of specific extracellular matrix proteins, potentially recovering V8 damage. However, HBD2 alone did not substantially modulate cellular proteomic/secretomics profiles in the absence of damage, suggesting possible therapeutic targeting of lesion damage sites only. HBD2 did not show any direct protease inhibition or induce expression of known antiproteases, did not alter keratinocyte migration or proliferation, or form protective nanonet structures. These data validate the barrier-protective properties of HBD2 in vitro and establish key protein datasets for further targeted mechanistic analyses.

From New Endocrine Entities Requiring New Approaches to New Approaches Leading to New Endocrine Entities

The dynamics pace of modern society is reflected by the medical community, the public health concerns, the quality of life, as well as the specific spectrum of various disorders [...].

The Role of Acetyl Zingerone and Its Derivatives in Inhibiting UV-Induced, Incident, and Delayed Cyclobutane Pyrimidine Dimers

Cyclobutane pyrimidine dimers (CPDs) are ultraviolet radiation (UV)-induced carcinogenic DNA photoproducts that lead to UV signature mutations in melanoma. Previously, we discovered that, in addition to their incident formation (iCPDs), UV exposure induces melanin chemiexcitation (MeCh), where UV generates peroxynitrite (ONOO^-), which oxidizes melanin into melanin-carbonyls (MCs) in their excited triplet state. Chronic MeCh and energy transfer by MCs to DNA generates CPDs for several hours after UV exposure ends (dark CPD, dCPDs). We hypothesized that MeCh and the resulting dCPDs can be inhibited using MeCh inhibitors, and MC and ONOO^- scavengers. Here, we investigated the efficacy of Acetyl Zingerone (AZ), a plant-based phenolic alkanone, and its chemical analogs in inhibiting iCPDs and dCPDs in skin fibroblasts, keratinocytes, and isogenic pigmented and albino melanocytes. While AZ and its methoxy analog, 3-(4-Methoxy-benzyl)-Pentane-2,4-dione (MBPD) completely inhibited the dCPDs, MBPD also inhibited ~50% of iCPDs. This suggests the inhibition of ~80% of total CPDs at any time point post UV exposure by MBPD, which is markedly significant. MBPD downregulated melanin synthesis, which is indispensable for dCPD generation, but this did not occur with AZ. Meanwhile, AZ and MBPD both upregulated the expression of nucleotide excision repair (NER) pathways genes including Xpa, Xpc, and Mitf. AZ and its analogs were non-toxic to the skin cells and did not act as photosensitizers. We propose that AZ and MBPD represent "next-generation skin care additives" that are safe and effective for use not only in sunscreens but also in other specialized clinical applications owing to their extremely high efficacy in blocking both iCPDs and dCPDs.

Low-Dose Blue Light (420 nm) Reduces Metabolic Activity and Inhibits Proliferation of Human Dermal Fibroblasts

Hypertrophic scarring in burn wounds is caused by overactive fibroblasts and myofibroblasts. Blue light reveals wavelength- and dose-dependent antibacterial and antiproliferative effects and may serve as a therapeutic option against wound infection and fibrotic conditions. Therefore, we evaluated in this study the effects of single and multiple irradiations with blue light at 420 nm (BL₄₂₀) on the intracellular ATP concentration, and on the viability and proliferation of the human skin fibroblast (HDFs). In addition, possible BL₄₂₀-induced effects on the catalase expression and differentiation were assessed by immunocytochemical staining and western blot analyses. Furthermore, we used RNA-seq analyses to identify BL₄₂₀-affected genes. We found that BL₄₂₀ induced toxicity in HDFs (up to 83%; 180 J/cm²). A low dose of 20 J/cm² reduced the ATP concentration by ~50%. Multiple irradiations (4 × 20 J/cm²) inhibited proliferation without visible toxicity and reduced catalase protein expression by ~37% without affecting differentiation. The expression of about 300 genes was significantly altered. Many downregulated genes have functions in cell division/mitosis. BL₄₂₀ can strongly influence the fibroblast physiology and has potential in wound therapy. However, it is important to consider the possible toxic and antiproliferative effects, which could potentially lead to impaired wound healing and reduced scar breaking strength.

Sympathetic System in Wound Healing: Multistage Control in Normal and Diabetic Skin

In this review, we discuss sympathetic regulation in normal and diabetic wound healing. Experimental denervation studies have confirmed that sympathetic nerve endings in skin have an important and complex role in wound healing. Vasoconstrictor neurons secrete norepinephrine (NE) and neuropeptide Y (NPY). Both mediators decrease blood flow and interact with inflammatory cells and keratinocytes. NE acts in an ambiguous way depending on receptor type. Beta2-adrenoceptors could be activated near sympathetic endings; they suppress inflammation and re-epithelialization. Alpha1- and alpha2-adrenoceptors induce inflammation and activate keratinocytes. Sudomotor neurons secrete acetylcholine (ACh) and vasoactive intestinal peptide (VIP). Both induce vasodilatation, angiogenesis, inflammation, keratinocytes proliferation and migration. In healthy skin, all effects are important for successful healing. In treatment of diabetic ulcers, mediator balance could be shifted in different ways. Beta2-adrenoceptors blockade and nicotinic ACh receptors activation are the most promising directions in treatment of diabetic ulcers with neuropathy, but they require further research.

Biochemical Pilot Study on Effects of Pomegranate Seed Oil Extract and Cosmetic Cream on Neurologically Mediated Skin Inflammation in Animals and Humans: A Comparative Observational Study

The presence of phenobarbital and formaldehyde in drugs, food, and beverages can lead to various health issues, including inflammation, oncogenesis, and neurological distress. Psychological stress leads to mood fluctuations and the onset of skin inflammation. Skin inflammation has a range of causes, including chemicals, heavy metals, infection, immune-related disorders, genetics, and stress. The various treatments for skin inflammation include medical and cosmetic creams, diet changes, and herbal therapy. In this study, we investigated the effects of Avocom-M and pomegranate seed oil extract (PSOE) against phenobarbital- and formaldehyde-induced skin biochemical changes in rats. We analyzed the constituents of PSOE using gas chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry. We also observed biochemical changes in the skin of human volunteers with and without TROSYD and PSOE as a skin cream. We compared the biochemical changes in human volunteers' skin before treatment and 21 days after the treatment stopped. The outcomes showed an improvement in the rats' biochemical status, due to PSOE and Avocom-M treatment. The human volunteers treated with TROSYD and PSOE showed substantial amelioration of skin inflammation. PSOE, Avocom-M, and TROSYD produced beneficial effects by reducing the levels of cyclooxygenase-2, lipid peroxidation, tyrosinase, hyaluronidase, elastase, collagenase, and nitric oxide in the animals tested on and in human volunteers.

Miglitol, an Oral Antidiabetic Drug, Downregulates Melanogenesis in B16F10 Melanoma Cells through the PKA, MAPK, and GSK3β/β-Catenin Signaling Pathways

Hyperpigmentation is a common condition that causes darker spots or patches on the skin, which often look brown, black, gray, red, or pink. This results in unresolved psychological impact due to high anxiety, depression, and somatoform disorder. We aimed to repurpose an antidiabetic drug, miglitol, as an effective compound against hyperpigmentation when applied as a cosmeceutical agent. The present study investigated the antimelanogenic effects of miglitol and the trehalase inhibitor validamycin A. Miglitol in isolation exhibited no cytotoxicity and significantly reduced the melanin production and intracellular tyrosinase activity in B16F10 melanoma cells. The Western blotting results showed that miglitol reduces the expression of melanogenic regulatory factors, including tyrosinase, tyrosinase-related protein (TRP)-1, TRP-2, and microphthalmia-associated transcription factor (MITF). Mechanistically, miglitol appears to suppress melanin synthesis through cAMP-dependent protein kinase (PKA)-dependent downregulation of MITF, a master transcription factor in melanogenesis. The antimelanogenic effects of miglitol was mediated by downregulation of the p38 signaling pathway and upregulation of extracellular signal-regulated kinase (ERK). Moreover, miglitol decreases P-GSK3β and β-catenin levels compared to those in the untreated group. However, miglitol activated P-β-catenin expression compared to that in the untreated group. Finally, we tested the potential of miglitol in topical application through primary human skin irritation tests on the normal skin (upper back) of 33 volunteers. In these assays, miglitol (125 and 250 μM) did not induce any adverse reactions. Taken together, these findings suggest that the regulation of melanogenesis by miglitol may be mediated by the PKA, MAPK, and GSK3β/β-Catenin signaling pathways and that miglitol might provide new insights into drug repurposing for the treatment of hyperpigmentation symptoms.