Evaluation of the minimal erythema dose for UVB and UVA in context of skin phototype and nature of photodermatosis

Skin Cancer Microenvironment: What We Can Learn from Skin Aging?

Aging is a natural intrinsic process associated with the loss of fibrous tissue, a slower cell turnover, and a reduction in immune system competence. In the skin, the continuous exposition of environmental factors superimposes extrinsic damage, mainly due to ultraviolet radiation causing photoaging. Although not usually considered a pathogenic event, photoaging affects cutaneous biology, increasing the risk of skin carcinogenesis. At the cellular level, aging is typified by the rise of senescence cells a condition characterized by reduced or absent capacity to proliferate and aberrant hyper-secretory activity. Senescence has a double-edged sword in cancer biology given that senescence prevents the uncontrolled proliferation of damaged cells and favors their clearance by paracrine secretion. Nevertheless, the cumulative insults and the poor clearance of injured cells in the elderly increase cancer incidence. However, there are not conclusive data proving that aged skin represents a permissive milieu for tumor onset. On the other hand, tumor cells are capable of activating resident fibroblasts onto a pro-tumorigenic phenotype resembling those of senescent fibroblasts suggesting that aged fibroblasts might facilitate cancer progression. This review discusses changes that occur during aging that can prime neoplasm or increase the aggressiveness of melanoma and non-melanoma skin cancer.

UVA-induced metabolic changes in non-malignant skin cells and the potential role of pyruvate as antioxidant

The exposure to UVA (320-400 nm) irradiation is a major threat to human skin concerning photoaging and carcinogenesis. It has been shown that UVA irradiation can induce reactive oxygen species (ROS) and DNA mutations, such as 8-hydroxydeoxyguanosine. Furthermore, UVA induces the expression of photoaging-associated matrix metalloproteases (MMPs), especially of matrix metalloprotease 1 (MMP 1) and matrix metalloprotease 3 (MMP 3). In addition to this, it was recently shown that UVA-induced ROS also increase glucose metabolism of melanoma cells, however, the influence of UVA on the glucose metabolism of non-malignant cells of the human skin has, so far, not been investigated in detail. Here, we investigated the UVA-induced changes in glucose metabolism and the functional relevance of these changes in primary fibroblasts-normal non-malignant cells of the skin. These cells showed an UVA-induced enhanced glucose consumption and lactate production and changes in pyruvate production. As it has been proposed that pyruvate could have antioxidant properties we tested the functional relevance of pyruvate as protective agent against UVA-induced ROS. Our initial experiments support earlier publications, demonstrating that pyruvate treated with H2O2 is non-enzymatically transformed to acetate. Furthermore, we show that this decarboxylation of pyruvate to acetate also occurs upon UVA irradiation. In addition to this, we could show that in fibroblasts pyruvate has antioxidant properties as enhanced levels of pyruvate protect cells from UVA-induced ROS and partially from a DNA mutation by the modified base 8-hydroxydeoxyguanosine. Furthermore, we describe for the first time, that the interaction of UVA with pyruvate is relevant for the regulation of photoaging-associated MMP 1 and MMP 3 expression.

The role and safety of UVA and UVB in UV-induced skin erythema

Background

Different wavelengths of ultraviolet (UV) light cause skin damage through different mechanisms. Minimal erythema dose (MED) is usually used to clinically evaluate skin sensitivity to ultraviolet radiation by inducing skin erythema using ultraviolet B (UVB) or ultraviolet A (UVA) + UVB.

Aims

In this study, we detected changes in the blood flow at the MED erythema caused by UVB and UVA + UVB radiation through optical coherence tomography (OCT) to explain the role of different bands of ultraviolet rays in erythema induction.

Methods

Two MED irradiation areas on the subjects' back were irradiated with UVB alone or UVA + UVB (UVA: UVB = 8:1). The absolute energy of UVB remained the same in UVB and UVA+UVB. At 24 h after the irradiation, the changes in the blood flow in the MED area were detected using OCT.

Results

Compared with the blank control, the maximum blood flow depth, blood flow peak, and total blood flow of UVB-MED and UVA+UVB-MED were significantly increased. Notably, the maximum blood flow depth and blood flow peak of UVB-MED were higher than UVA+UVB-MED. There was no significant difference in total blood perfusion between UVA+UVB-MED and UVB-MED. Under the same UVB energy, the skin erythema caused by UVA + UVB was weaker than UVB alone.

Conclusions

The analysis of local blood flow by OCT showed that the peak and maximum depth of local blood flow caused by UVB alone were significantly higher than UVA + UVB.

Efficacy and safety of micro-needling combined with topical 5-fluorouracil and excimer light vs. excimer light alone in treatment of non-segmental vitiligo: A comparative study

BACKGROUND/PURPOSE

Vitiligo is one of the most challenging dermatological diseases with little improvement promises. Various modalities of treatment both medical and surgical have been used in the treatment of vitiligo. Some proved to be effective, others with controversial results and the rest were effective less. The aim of the present study was to evaluate the additional effect of topical 5-fluorouracil after micro-needling to excimer light (308 nm) in treatment of non-segmental vitiligo.

METHODS

Fifty patients were included in the present study, only 33 patients continued the treatment for 6 months. Two patches were selected in every patient to be treated, one patch with micro-needling then application of 5 FU and excimer (Group A), and the other with excimer only (Group B).

RESULTS

The treatment with the combination of micro-needling then application of 5 FU and excimer showed significant earlier response versus excimer alone. Also, the percentage of re-pigmentation was higher in the patches treated with the combination especially in the face and trunk. The combination of 5 FU after micro-needling and Excimer is more suitable for localized and focal vitiligo.

CONCLUSION

Topical 5 FU after micro-needling is a promising, rapid, and cost-effective therapeutic strategy for treatment of non-segmental vitiligo It had limited side effects, and the best response was reported for lesions affecting face and trunk.

Adult-Onset Neurodegeneration in Nucleotide Excision Repair Disorders (NERDND ): Time to Move Beyond the Skin

BACKGROUND

Variants in genes of the nucleotide excision repair (NER) pathway have been associated with heterogeneous clinical presentations ranging from xeroderma pigmentosum to Cockayne syndrome and trichothiodystrophy. NER deficiencies manifest with photosensitivity and skin cancer, but also developmental delay and early-onset neurological degeneration. Adult-onset neurological features have been reported in only a few xeroderma pigmentosum cases, all showing at least mild skin manifestations.

OBJECTIVE

The aim of this multicenter study was to investigate the frequency and clinical features of patients with biallelic variants in NER genes who are predominantly presenting with neurological signs.

METHODS

In-house exome and genome datasets of 14,303 patients, including 3543 neurological cases, were screened for deleterious variants in NER-related genes. Clinical workup included in-depth neurological and dermatological assessments.

RESULTS

We identified 13 patients with variants in ERCC4 (n = 8), ERCC2 (n = 4), or XPA (n = 1), mostly proven biallelic, including five different recurrent and six novel variants. All individuals had adult-onset progressive neurological deterioration with ataxia, dementia, and frequently chorea, neuropathy, and spasticity. Brain magnetic resonance imaging showed profound global brain atrophy in all patients. Dermatological examination did not show any skin cancer or pronounced ultraviolet damage.

CONCLUSIONS

We introduce NERD_ND as adult-onset neurodegeneration (_ND ) within the spectrum of autosomal recessive NER disorders (NERD). Our study demonstrates that NERD_ND is probably an underdiagnosed cause of neurodegeneration in adulthood and should be considered in patients with overlapping cognitive and movement abnormalities. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Genome-Wide RNA Sequencing Analysis in Human Dermal Fibroblasts Exposed to Low-Dose Ultraviolet A Radiation

Ultraviolet A (UVA) radiation can pass through the epidermis and reach the dermal skin layer, contributing to photoaging, DNA damage, and photocarcinogenesis in dermal fibroblasts. High-dose UVA exposure induces erythema, whereas low-dose, long-term UVA exposure causes skin damage and cell senescence. Biomarkers for evaluating damage caused by low-dose UVA in fibroblasts are lacking, making it difficult to develop therapeutic agents for skin aging and aging-associated diseases. We performed RNA-sequencing to investigate gene and pathway alterations in low-dose UVA-irradiated human skin-derived NB1RGB primary fibroblasts. Differentially expressed genes were identified and subjected to Gene Ontology and reactome pathway analysis, which revealed enrichment in genes in the senescence-associated secretory phenotype, apoptosis, respiratory electron transport, and transcriptional regulation by tumor suppressor p53 pathways. Insulin-like growth factor binding protein 7 (IGFBP7) showed the lowest p-value in RNA-sequencing analysis and was associated with the senescence-associated secretory phenotype. Protein–protein interaction analysis revealed that Fos proto-oncogene had a high-confidence network with IGFBP7 as transcription factor of the IGFBP7 gene among SASP hit genes, which were validated using RT-qPCR. Because of their high sensitivity to low-dose UVA radiation, Fos and IGFBP7 show potential as biomarkers for evaluating the effect of low-dose UVA radiation on dermal fibroblasts.

Skin biophysical properties including impaired skin barrier function determine ultraviolet sensitivity

BACKGROUND

The levels of burning susceptibility to ultraviolet (UV) radiations are affected by various factors, including Fitzpatrick skin types, skin color, sex, and ethnicity. However, studies on the relationship between skin biophysical properties and erythemal responses to UV radiations are rare.

OBJECTIVE

This study aimed to investigate biophysical properties of the skin that determined individual skin sensitivity to UV radiation.

METHODS

As an indicator of skin sensitivity to UV radiation, Korean women were subjected to minimal erythema dose (MED) testing. The skin biophysical properties, such as skin hydration, transepidermal water loss (TEWL) were measured. MED were also evaluated in further variations in the skin, including barrier disruption.

RESULTS

A significant negative correlation was observed between TEWL and MED. With an increase in TEWL, that represents reduced skin barrier function, skin UV sensitivity also increased. Artificial alteration of skin conditions also changed erythemal response to UV radiation. When the skin barrier was disrupted, MED significantly decreased, indicating increased skin UV sensitivity. It is hypothesized that the altered penetration of UV radiation into the stratum corneum under the respective skin conditions caused different erythema reactions.

CONCLUSION

For the first time in a clinical study, the skin biophysical properties, including skin barrier function, were found to have significant effects on skin sensitivity to UV radiation. This finding could help predict individual susceptibility to UV damage. Therefore, skincare products that improve skin conditions associated with UV sensitivity, as well as sunscreen are important for protection against the hazards of UV radiation.

Chinese women with melasma exhibit a low minimal erythema dose to both UVA and UVB

BACKGROUND

Melasma is a common disorder manifested by symmetric hyperpigmentation of sun-exposed skin. Although ultraviolet (UV) radiation is a known risk factor of melasma, whether skin sensitivities to UVA and/or UVB differ between healthy controls and female patients with melasma is unknown.

METHODS

Minimal erythema dose (MED)-UVA and MED-UVB results were compared between female patients with melasma and healthy controls. Additionally, relationships between MED values and Melasma Area and Severity Index (MASI) scores, and skin color were assessed.

RESULTS

The melasma and control groups included 142 and 137 subjects, respectively. Compared with healthy control group, our melasma group had lower MED-UVA (P < .001) and MED-UVB (P < .05). MASI scores were negatively correlated with MED-UVA and MED-UVB (P < .001). Additionally, Skin a* values in melasma-involved skin were negatively correlated with MED-UVA (P < .05). Skin b* values in melasma-involved skin were negatively correlated with MED-UVB and MED-UVA (P < .05).

CONCLUSIONS

Patients with melasma exhibit a low MED to both UVA and UVB, rendering them have a predisposition to an increased UV sensitivity. Because of the association between melasma and UV sensitivity, sun exposure should be avoided to alleviate or prevent melasma.

Long-wavelength ultraviolet A (UVA-1) phototherapy for the treatment of patients with atopic dermatitis

One of the methods of therapy for atopic dermatitis is long-wavelength ultraviolet therapy A (UVA-1- therapy). This review aims to provide the mechanisms of action of UVA-1-therapy an overview about the effectiveness of UVA-1-therapy in patients with atopic dermatitis taking into account factors that can affect the effectiveness of treatment radiation dose, skin phototype of patients, concomitant drug therapy. The available data on a decrease in the severity of atopic dermatitis as a result of the course of UVA-1-therapy and on a decrease in the severity of itching in patients are presented. The data on the rate of onset of the therapeutic effect of UVA-1-therapy and the duration of its maintenance are considered. The safety of UVA-1-therapy is discussed, and the most frequent undesirable effects a feeling of warmth, fever, itching, hyperpigmentation, are given. The possibility of developing side effects requiring discontinuation of treatment is assessed. The data obtained indicate the effectiveness and safety of the UFA-1-radiation in the treatment of patients with moderate-to-severe atopic dermatitis.

Hydrochlorothiazide Use and Risk of Nonmelanoma Skin Cancers: A Biological Plausibility Study

Recent studies reported the association between increased risk of nonmelanoma skin cancers (NMSCs) and the use of hydrochlorothiazide (HCTZ), one of the most commonly prescribed diuretic, antihypertensive drug, over the world. Although HCTZ is known to be photosensitizing, the mechanisms involved in its potential prophotocarcinogenic effects remain unclear. Under acute exposure, therapeutically relevant concentrations of HCTZ (70, 140, and 370 ng/mL) amplified UVA-induced double-strand breaks, oxidative DNA, and protein damage in HaCaT human keratinocytes, and this effect was associated to a defective activity of the DNA repair enzyme, OGG1. Oxidative damage to DNA, but not that to proteins, was reversible within few hours. After chronic, combined exposure to HCTZ (70 ng/mL) and UVA (10 J/cm2), for 9 weeks, keratinocytes acquired a dysplastic-like phenotype characterized by a multilayered morphology and alterations in cell size, shape, and contacts. At the ultrastructural level, several atypical and enlarged nuclei and evident nucleoli were also observed. These transformed keratinocytes were apoptosis resistant, exhibited enhanced clonogenicity capacity, increased DNA damage and inflammation, defective DNA repair ability, and increased expression of the oncogene ΔNp63α and intranuclear β-catenin accumulation (a hallmark of Wnt pathway activation), compared to those treated with UVA alone. None of these molecular, morphological, or functional effects were observed in cells treated with HCTZ alone. All these features resemble in part those of preneoplastic lesions and NMSCs and provide evidence of a biological plausibility for the association among exposure to UVA, use of HCTZ, and increased risk of NMSCs. These results are of translational relevance since we used environmentally relevant UVA doses and tested HCTZ at concentrations that reflect the plasma levels of doses used in clinical practice. This study also highlights that drug safety data should be followed by experimental evaluations to clarify the mechanistic aspects of adverse events.