Contribution of phototesting in the diagnosis of photodermatoses: Retrospective study of 100 cases.

BACKGROUND: Photodermatoses are sun-related inflammatory skin diseases. They usually require phototesting in diagnosis. However, fewer and fewer medical centers in France are equipped with photobiological equipment. OBJECTIVES: The main purpose was to evaluate the relevance of phototesting in photodermatosis diagnosis. The second goal was to study the proportions of the different kinds of photodermatosis found in this particular study. METHODS: This study was descriptive, retrospective, and mono-centric. It was based on 100 consecutive patients, who have been phototested in a French University Hospital from 2014 to 2018. Phototesting included determination of the minimal erythematous dose (MED), UVA and UVB phototests, and photopatch testing. RESULTS: The use of phototesting led to 60% of photodermatosis diagnosis and formally eliminated the latter in 13% of the cases. The diagnosis remained undetermined in 27% of the cases. Nineteen cases of polymorphous light eruption (PLE), 14 cases of photocontact dermatitis (PCD), 10 cases of solar urticaria, 8 cases of photo-aggravated atopic eczema, 5 cases of chronic actinic dermatitis, and 2 cases of systemic photosensitization were diagnosed. The allergens involved in PCD were topical non-steroidal anti-inflammatory drug (NSAID) in 9 cases, sunscreens in 3 cases, and fragrance in 2 cases. The average amount of time between the first symptoms and actual phototesting was about 7,5 years. CONCLUSION: This study confirms phototesting is truly useful. PLE was the most common form of photodermatosis, followed by PCD and solar urticaria. As photodermatosis could imply severe diseases sometimes requiring hospitalization, it is critical to maintain this expertise.

[Ultraviolet A-induced DNA damage: role in skin cancer]. / Ultraviolets A et dommages de l'ADN ; leur place dans la cancérogenèse cutanée.

Skin cancer is the most common human malignancy, and sunlight exposure is known to play a role in its genesis. Ultraviolet B (UVB) (300-320 nm) has long been considered responsible for the skin damage underlying these cancers, whereas the toxicity of UVA (320-400 nm) has been largely overlooked The intimate mechanisms of photocarcinogenicity remain poorly understood, but UV-induced DNA damage appears to be a major initiating event. Cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) photoproducts (6-4PPs) are the main dimeric lesions induced by UVB, whereas the genotoxic effects of UVA have long been attributed to oxidative damage, the main lesion being the oxidized base 8-oxo-7,8dihydroguanine (8-oxoGua). However; powerful new techniques for analyzing DNA damage (the Comet assay, and especially HPLC-MSIMS) have demonstrated that UVA irradiation mainly triggers the formation of CPDs, especially CPD-TT both in cell models and in total human skin. A direct photochemical process is currently thought to account for CPD induction by UVA. The multilayer structure of the epidermis protects against UVB-induced dipyrimidine lesions in total skin but offers only weak protection against UVA. In addition, repair efficiency is undermined by UVA. CPDs, the main DNA lesions induced by UVA in total skin (which is more permeable to UVA), are inefficiently repaired CPDs have strong mutagenic potential, and recent studies clearly show that CPDs, rather than 8-Oxo-Gua, are the main mutagenic photoproducts induced by UVA. The UV signature of induced mutations is characterized by transitions from C to T or CC to TT in dipyrimidine sequences. These mutations target the p53, patched 1 and SMO genes in carcinomas, and the PTEN RAC1, PPP6C, STK19 and PPP6C genes in melanomas of exposed skin. UVA also mainly induces CPDs in melanocytes, in amounts similar to those observed in keratinocytes, demonstrating that melanin does not prevent CPD formation. In contrast, UVA induces far more abundant 8-oxo-Gua production in melanocytes than in keratinocytes. Thus, under UVA irradiation, oxidative stress contributes more to DNA damage in melanocytes than in keratinocytes. In addition, baseline oxidative damage (in the absence of UVA) is already higher in melanocytes. The photosensitizer may be melanin itself. This is supported by a recent study based on a murine model, in which melanoma induction was shown to require both UVA and the presence of melanin in melanocytes, and is associated with oxidative damage to DNA. Conversely, UVB was found to initiate melanoma through a direct, pigment-independent pathway. Thus, two wavelength-dependent pathways can induce melanoma, with melanin playing an unexpected role. Constitutive pigmentation is very effective in preventing UV-induced damage, and a clear correlation can thus be found between, on the one hand, the amount of CPD TT produced by both UVB and UVA and, on the other hand, the minimum erythematous dose and the phototype. Melanin is thus a two-facetted molecule, protecting the skin when its synthesis is complete and when melanosomes take on their nucleus-protective geometric configuration in keratinocytes, but having a pro-oxidant action when only partially polymerized and exposed to UV Repeated exposure of volunteer skin shows that a tan induced by UVB provides little protection against DNA damage caused by subsequent exposure, while tanning with UVA provides no protection at all. Yet both UVB and UVA provoke DNA damage. All these recent data highlight the potential role of UVA in skin carcinogenesis, and reinforce epidemiological studies showing an increased risk of melanoma among users of tanning lamps, particularly young women. The decision by the International Agency for Research on Cancer to classify UVA and tanning devices as group 1 carcinogens, and the opinion issued by the French National Academy of Medicine on tanning booths, therefore appear to be fully justified. The use of tanning salons should be permanently banned

Plasmacytoid dendritic cells and dermatological disorders: focus on their role in autoimmunity and cancer.

Dendritic cells (DC), considered as immunological sentinels of the organism since they are antigen presenting cells, create the link between innate and adaptive immunity. DC include myeloid dendritic cells (MDC) and plasmacytoid dendritic cells (PDC). The presence of PDC, cells capable of producing large quantities of interferon alpha (IFN-alpha) in response to pathogenic agents or danger signals, seems to be closely related to pathological conditions. PDC have been observed in inflammatory immunoallergic dermatological disorders, in malignant cutaneous tumours and in cutaneous lesions of infectious origin. They seem to play a crucial role in the initiation of the pathological processes of autoimmune diseases such as lupus or psoriasis. Their function within a tumour context is not as well known and is controversial. They could have a tolerogenic role towards tumour cells in the absence of an activator but they also have the capacity to become activated in response to Toll-like receptor (TLR) ligands and could therefore be useful for therapeutic purposes.

Age-dependent DNA repair and cell cycle distribution of human skin fibroblasts in response to UVA irradiation.

Ageing process in cells is associated with oxidative stress. Ultraviolet A produces reactive oxygen species responsible for accumulation of DNA and cellular damage. After the evaluation of antioxidant enzyme activities and oxidative stress markers at the basal state, we have studied the responses to UVA stress of coetaneous fibroblasts, isolated from different male donors (2-88 years, n=23) in terms of cytotoxicity, genotoxicity and DNA repair capacities. For this purpose, we have determined level of DNA damage using the comet assay (single strand breaks and alkali-labile sites) and the cell cycle distribution after a 5 J/cm2 irradiation. No differences with age were observed for antioxidant enzyme activities and oxidative stress markers. DNA strand breaks after UVA irradiation (5-20 J/cm2), was found to be age-dependent. DNA repair was slow and also significantly affected by ageing. The cell cycle distribution analysis showed that high repair correlated with high proliferative capacities at basal level. Twenty-four hours after the stress, fraction of young fibroblasts blocked in G1 phase was significantly increased whereas significant modifications concerned the G2-M phase for adult and older fibroblasts. These results indicate an age-dependent decline in the DNA repair capacities correlated with modifications of the cell cycle parameters.

Ageing effects on the expression of cell defence genes after UVA irradiation in human male cutaneous fibroblasts using cDNA arrays.

Ageing is a multifactorial process in which reactive oxygen species (ROS) are thought to be implicated. ROS cause oxidative alterations on cell constituents, and damage accumulation can lead to mutations in DNA. Modulation of gene expression during ageing is now quite documented but results are often controversial and/or incomplete. As ultraviolet A is one of the exogenous factors involved in skin ageing, by the production of ROS, we further document the modifications in gene expression during ageing process and response to an oxidative stress. For this purpose, we used a cDNA macroarray containing 82 genes related to cell defence, essentially represented by antioxidant and DNA repair proteins. Ageing-associated gene expression was assessed in normal skin human fibroblasts from three age groups: children (n=4), adults (n=4) and olders (n=3), at the basal state and after a 5J/cm2 UVA irradiation. Analysis revealed that 22 genes were never detected, whereas certain were always expressed such as those related to antioxidant defence, extracellular matrix (ECM) regulator and XPC. Transcripts related to ECM, MMP1 and MMP3 were increased with age and after UVA irradiation, independently of age. It appeared that transcripts involved in the redox status control (TXN and APEX) decreased as a function of age, at the basal state and after irradiation, respectively. Most of transcripts involved in DNA repair were not detected but repression of POLD1 in the adult group and induction of XRCC5 and LIG4 were observed after UVA irradiation, as a function of age. In the basal state, the transcript of GAS1, regulator of cell cycle arrest in G1 phase was found to be decreased with age. HMOX1 increased after UVA irradiation. In conclusion, the decrease in expression of some antioxidant system, cell cycle control gene and extracellular matrix enzymes, particularly after UV exposure can explain the occurrence of photoaging.

[Prescription of phototherapy in psoriasis]. / Prescrire une photothérapie dans le psoriasis.

Two types of phototherapy are used in the treatment of psoriasis. UVB phototherapy (so called TL01 excluding the most erythematogenic UVB) has acquired a position next to puvatherapy (associating co-administration of a psoralen either by oral intake or bath, with exposure to UVA) of which the efficacy has been clearly established for a long time. The use of UVB TL01 phototherapy presents less constraint but doesn't seem to be as efficient as puvatherapy in the more severe forms. The results of these two phototherapies are amplified by the addition of adjuvant treatments, in particular with the association of the oral intake of acitretin. The long-term risk of phototherapy is the induction of cutaneous cancers, essentially spinocellular carcinomas; this risk, qualified and quantified for puva, remains less clear for TL01; it imposes the need for a precise count of the number of sessions received and a prolonged follow-up of patients having received numerous phototherapy treatments. The indication for phototherapy is an extensive flare-up of psoriasis in its common form. Therapeutic rotation, during successions of flare-ups or when the phototherapy capital has been consumed, can be done with a retinoid or methotrexate, conversely it has to be much more careful with cyclosporin due to the increase of the carcinogenic risk.

Photodynamic therapy can improve warts' discomfort in renal transplant patients prospective multicenter study.

Many studies have been conducted showing that aminolevulinic acid (ALA)-photodynamic therapy (PDT) can be an alternative treatment for recalcitrant warts. Recently, we performed a study evaluating methyl-aminolevulinic acid (MAL)-PDT for the treatment of hand warts in a population of renal transplant patients. Two symmetrical targets were selected on each hand and randomly assigned to chemical keratolytic treatment followed by three cycles of ALA-PDT (75 J cm(-2) red light). Patients were evaluated after 3 months and a second run of PDT was performed if the total area and number of warts decreased less than 50%, with evaluation every 3 months for 1 year. Twenty patients were included and 16 were evaluable (9 M, 7 F). After 6 months the reduction of warts' area was 48.4% on the treated side versus 18.4% in the control area (P = 0.021). The decrease in the total number of warts was 41%versus 19.4% (P = NS). The global tolerance of the treatment was good with acceptable pain during irradiation. These results suggest that ALA-PDT is a safe and efficient treatment for transplanted patient warts. The improvement between treated and control zone is 20% due to the decrease in untreated warts' area and number.

Individual photosensitivity of human skin and UVA-induced pyrimidine dimers in DNA.

Delineation of the DNA-damaging properties of UVA radiation is a major issue in understanding solar carcinogenesis. Emphasis was placed in this study on the formation of cyclobutane pyrimidine dimers (CPDs), which are now well established as the most frequent UVA-induced DNA lesions in human skin. The yield of CPDs was determined by a chromatographic assay following ex vivo UVA and UVB irradiation of biopsies taken from either phototype II or IV volunteers. A clear correlation was found between the frequency of UVB-induced CPDs and both the phototype and the minimum erythemal dose (MED). Similar results were obtained for the induction of CPDs upon exposure to UVA. Moreover, an excellent correlation was observed for each donor between the yield of DNA damage induced by either UVB or UVA. These observations show that the key parameters driving UVA-induced formation of CPDs are attenuation of radiation in the skin and the number of photons reaching skin cells rather than the cellular content in photosensitizers. In addition, the results show that both MED and phototype are good predictors of the vulnerability of DNA toward UVB and UVA in the skin. This result is of importance for the identification of individuals to be extensively protected.

Differential p53-mediated responses to solar-simulated radiation in human papillomavirus type 16-infected keratinocytes.

In immunocompromised patients, cooperative effects of human papillomavirus (HPV) and ultraviolet (UV) radiation have been postulated in the development of non-melanoma skin cancers. The tumor suppressor p53 is a key component of the cellular response to genotoxic agents, such as UV radiation. We have previously demonstrated that in HPV16-infected cells, a higher E6* level was associated with a higher resistance to UV and oxidative stress. Using the two same SKv cell lines, the aim of the present study was to investigate p53 and p21 expression and cell death in HPV-infected keratinocytes in response to UV irradiation and to determine the role of HPV oncoprotein levels on the p53-mediated cellular response. We demonstrated that the weakly E6*-expressing level SKv-e cell line presented both higher cytotoxicity and apoptosis to UV. This high sensitivity was associated with both p53 and p21 nuclear accumulation, while a high E6* level and resistance were associated with no p53 accumulation and a p21 nuclear down-regulation after UV. Moreover, in SKv-e cell line, p21 promoter activation was p53 dependent. Our results suggest that an alteration and/or a modulation of the p53-p21 pathway in response to UV could be determinant for HPV-infected keratinocyte survival and HPV-associated carcinogenic process.

E6* oncoprotein expression of human papillomavirus type-16 determines different ultraviolet sensitivity related to glutathione and glutathione peroxidase antioxidant defence.

Clinical observations of non-melanoma skin cancer in immunocompromised patients, such as organ transplant recipients, suggest co-operative effects of human papillomavirus (HPV) and ultraviolet (UV) radiation. The aim of the present study is to evaluate UV sensitivity and DNA damage formation according to antioxidant status in HPV16-infected keratinocytes. We used SKv cell lines, infected with HPV16 and well characterized for their proliferative and tumorigenic capacities. We showed that SKv cell lines presented various E6* (a truncated form of E6) RNA levels. We demonstrated that the higher oncoprotein RNA expression level was associated with a higher resistance to solar-simulated radiation, more specifically to UVB radiation and to hydrogen peroxide. Moreover, this high resistance was associated with a low oxidative DNA damage formation after UV radiation and was related to high glutathione content and glutathione peroxidase activities. Therefore, the results of our study suggest that E6* levels could modulate the glutathione/glutathione peroxidase pathway providing a mechanism to protect HPV-infected keratinocytes against an environmental oxidative stress, such as UV radiation.

Effects of cadmium and zinc on solar-simulated light-irradiated cells: potential role of zinc-metallothionein in zinc-induced genoprotection.

Zinc is an essential oligoelement for cell growth and cell survival and has been demonstrated to protect cells from oxidative stress induced by UVA or from genotoxic stress due to UVB. In a recent work we demonstrated that the antioxidant role of zinc could be related to its ability to induce metallothioneins (MTs). In this study we identified the mechanism of zinc protection against solar-simulated light (SSL) injury. Cultured human keratinocytes (HaCaT) were used to examine MTs expression and localization in response to solar-simulated radiation. We found translocation to the nucleus, with overexpression of MTs in irradiated cells, a novel observation. The genoprotective effect of zinc was dependent on time and protein synthesis. DNA damage was significantly decreased after 48 h of ZnCl(2) (100 microM) treatment and is inhibited by actinomycin D. ZnCl(2) treatment (100 microM) led to an intense induction, redistribution, and accumulation of MT in the nucleus of irradiated cells. MT expression correlated with the time period of ZnCl(2) treatment. CdCl(2), a potent MT inducer, did not show any genoprotection, although the MTs were expressed in the nucleus. Overall our findings demonstrate that MTs could be a good candidate for explaining the genoprotection mediated by zinc on irradiated cells.