Development of skin diseases following systemic exposure: example of dioxins.

Most skin manifestations of exposure to toxic compounds are a consequence of a direct contact with the toxicants. However, some toxicants may reach the skin following systemic exposure, and promote skin diseases. Good examples of such chemicals are dioxin-like compounds. This family of lipophilic molecules comprises polychlorinated (dibenzodioxins, dibenzofurans and biphenyls). The most potent member of this family is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Following oral ingestion of as little as a few mg TCDD, skin lesions appear in a couple of weeks, starting from the face and diffuse then on the trunk and limbs. This syndrome was historically called "chloracne" and the skin lesions have now been shown to be skin hamartoma induced by TCDD. Sweat glands release their lipid content on the surface of the skin by a holocrine secretion, and so any lost sebocyte should be transmitted to progenitor cells to differentiate and migrate to the sebaceous gland to replace the lost sebocyte. TCDD acts by inducing a switch in this signal and skin hamartoma develop in place of new sebocytes.

Cytochrome P450 1A2 activity and incidence of thyroid disease and cancer after chronic or acute exposure to dioxins.

BACKGROUND: Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin; TCDD) is the most toxic congener of a family of structurally and mechanistically related persistent organic pollutants whose effects are mediated through the aryl hydrocarbon receptor (AhR). Induction of CYP1A1/2 by TCDD through the AhR depends on the magnitude and the duration of exposure. We aimed to assess CYP1A2 activity after acute and chronic exposure to TCDD. The Maincy cohort is a sample population from Melun in the Val-de-Seine region in France that lived for at least 5 years close to a waste incinerator emitting polluted vapours (1974-2002) with high concentrations of dioxins (up to 2000 times the maximal recommended values). Acute exposure to TCDD (Viktor Yushchenko) has been described elsewhere by Sorg et al (Toxicol. Sci. 2012; 125:310-317). Both are rare cases of well-identified source of chronic and acute exposure to TCDD. METHODS: All subjects underwent a full medical history and physical examination and had a cutaneous examination, and a retro-auricular skin biopsy was taken. A questionnaire was designed and used regarding demographic, personal, environmental and occupational characteristics. CYP1A2 activity was assessed 2 hours after the ingestion of a drink containing caffeine through measurement of the metabolic ratio of paraxanthine (17X) over caffeine (137X) by LC-MS/MS or LC-UV. CYP1A1 expression in skin biopsies was determined by immunohistochemical analysis. RESULTS: Forty-seven exposed subjects (age 11-78) and 31 controls were included in the study. Eleven exposed subjects had a history of thyroid disease (23.4%), and 7 (14.8%) had a cancer vs none and 1, respectively, in controls. Nodular skin lesions were found in 13 exposed subjects (27.7%) vs none in controls. Mean CYP1A2 activity of the exposed population was modestly elevated as compared to controls (17X/137X metabolic ratio of 0.475 vs 0.374, P = .051). CYP1A2 was, however, induced (17X/137X, metabolic ratio >0.5) in 27.6% of the exposed cases vs 6.4% of the controls. In contrast, acute dioxin exposure was associated with a strong induction (mean 17X/137X, metabolic ratio of 1.9) still present 29 months after the acute exposure. CYP1A1 was expressed in 59.6% of the skin biopsies (highly expressed in 31.9%) of the Maincy cohort. No correlation between CYP1A2 activity, CYP1A1 expression and clinical manifestations (thyroid disease, cancer, skin lesions) could be demonstrated. CONCLUSION: Higher frequencies of dysthyroidism and cancer were detected in the population exposed chronically to dioxins from a waste incinerator. CYP1A2 was induced in 27.6% of the exposed population, while the magnitude of induction was fourfold higher after acute exposure in the case of Yushchenko.

Cutaneous Adnexal Cysts Revisited: What We Know and What We Think We Know.

Cutaneous cysts have been classified by dermatopathologists in many different ways. Here, we propose a novel classification of cutaneous adnexal cysts according to their origin in the folliculosebaceous unit and the sweat glands. By examining the lining of the cystic structure, its origin can be easily identified. Epidermal cysts have an epithelial wall containing a granular layer with lamellar keratinization, indicating an infundibular origin. Tricholemmal cysts have an undulating epithelial wall with no granular layer and a compact keratinization, showing an isthmic origin. In steatocystoma, dermoid cyst, and folliculosebaceous hamartoma, the epithelial lining shows a crenulated appearance which is seen in the sebaceous duct. Hidrocystoma shows the characteristic cuboidal epithelial lining of sweat glands with decapitation secretion in its apocrine forms. The hair matrix cyst wall is composed of basaloid cells maturing to squamoid cells, as seen in the normal hair matrix and shadow cells in the lumen. Metabolizing acquired dioxin-induced skin hamartoma (MADISH) is a cystic lesion with lamellar keratinization, and no sebaceous glands. The classification proposed here aims to simplify the complexity of cutaneous adnexal cysts, and to facilitate a better understanding of the origin of cystic lesions of the skin.

Senescent Atrophic Epidermis Retains Lrig1+ Stem Cells and Loses Wnt Signaling, a Phenotype Shared with CD44KO Mice.

Lrig1 is known to repress the epidermal growth through its inhibitory activity on EGFR, while CD44 promotes it. We analyzed the expression of these molecules in senescent atrophic human epidermis and in the epidermis of CD44KO mice. In normal human epidermis, Lrig1+ cells form clusters located in the basal layer in which CD44 expression is downregulated and Lef1 expression reflects an active Wnt signaling. In senescent atrophic human epidermis, we found retention of Lrig1high+ cells all along the basal layer, forming no clusters, with decrease of CD44 and lef1 expression. In vitro silencing of CD44 indicated that CD44 may be required for Wnt signaling. However, if looking at the ear epidermis of CD44KO mice, we only found a limited interfollicular epidermal atrophy and unchanged Lrig1high+ cells in the hair follicle. Cell lineage tracing further revealed that interfollicular epidermis did lost its self-renewing capacity but that its homeostasis relied on Lrig1-derived keratinocytes migrating from the hair follicle. Therefore, we conclude that CD44 downregulation is part of the phenotype of senescent atrophic human epidermis, and contributes to reduce Wnt signaling and to alter Lrig1high+ stem cell distribution.

Aryl Hydrocarbon Receptor Activation in Acne Vulgaris Skin: A Case Series from the Region of Naples, Italy.

BACKGROUND: Dioxins are persistent organic pollutants present in the environment. They exert their biological effects by binding to an intracellular receptor, the aryl hydrocarbon receptor (AhR). Activation of AhR leads to the induction of cytochrome p450 1A1 (CYP1A1). Expression of CYP1A1 in human skin is a key marker for AhR activation, and it may induce comedogenesis resulting in acne-like lesions known as chloracne/metabolising acquired dioxin-induced skin hamartomas (MADISH). The contribution of this pathway in patients seen in a busy acne clinic is unknown. MATERIALS AND METHODS: We explored the expression of CYP1A1 by immunohistochemistry in the acne lesions of 16 patients living in the region of Naples, Italy, where epidemiological studies have suggested a possibly increased exposure to environmental dioxins. A composite score to outline potential components of the chloracne/MADISH histological pattern was used. RESULTS: CYP1A1 expression was observed in 11 lesions (69%) and was distributed in sebaceous glands, follicular epithelium, cystic wall and endothelial cells. The histological score for chloracne/MADISH was 'likely' in 3 cases and 'possible' in 11 cases. Compared to current data on CYP1A1 expression in the skin of 67 patients with proven exposure to AhR agonists, these data indicate a high incidence of AhR activation in this series. CONCLUSION: This is the first study analysing AhR activation in skin in a series of patients from a hospital-based acne clinic. It provides information for future controlled prospective studies. The significance of CYP1A1 expression in terms of AhR ligand exposure is discussed.

Hyalurosome gene regulation and dose-dependent restoration of skin atrophy by retinaldehyde and defined-size hyaluronate fragments in dermatoporosis.

BACKGROUND: Dermatoporosis is an emerging clinical condition caused by chronological skin aging, long-term sun exposure and chronic use of corticosteroids; however, genomic expression in dermatoporosis and the efficacy of different therapeutic approaches to prevent and treat dermatoporosis have not been investigated so far. OBJECTIVE: We examined the possible effect of topical retinaldehyde (RAL) and defined-size hyaluronate fragments (HAFi) on the expression of hyalurosome genes potentially involved in the pathogenesis of dermatoporosis. We also explored the effect of different concentrations of HAFi on skin thickness. METHODS: 13 persons were separated into a young control group (n = 8) and a dermatoporosis group (n = 5). Topical treatment of both groups with a combination of 0.05% RAL and 1 or 0.2% HAFi was applied on the forearm twice daily for 30 days. Forearm skin biopsies of both groups were performed before and after application. Hyalurosome genes CD44, heparin-binding epidermal growth factor (HB-EGF), ErbB1, hyaluronate synthase 3 (HAS3) and Hyal2 were chosen as potential markers of dermatoporosis. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed for quantification of mRNA expression of the target hyalurosome genes. Measurement of forearm skin thickness before and after treatment was performed by ultrasonography. Analysis of the results was done by Student's t test. A p value <0.05 was considered statistically significant. RESULTS: In qRT-PCR analysis the relative expression of hyalurosome (CD44, HAS3, HB-EGF) genes was found to be reduced in patients prior to topical treatment and to be notably increased following treatment. The reduced expression of CD44 and HAS3 in patients was specifically restored in dermatoporotic patients after treatment. No difference in skin thickness was observed in controls after treatment. The treatment caused a significant increase in skin thickness in dermatoporotic patients. This increase was more significant with 1% HAFi when compared to 0.2% HAFi. RAL and HAFi also caused a significant reduction in purpuric lesions in patients with dermatoporosis. CONCLUSION: Our results indicate that topically applied RAL and HAFi regulate hyalurosome gene expression in dermatoporosis and that they show a dose-dependent effect on the correction of skin atrophy in dermatoporotic patients.

Topical retinoids in skin ageing: a focused update with reference to sun-induced epidermal vitamin A deficiency.

Vitamin A is an important constituent of the epidermis, where it plays a crucial role in epidermal turnover. A deficiency of epidermal vitamin A may be the consequence of nutritional vitamin A deficiency, exposure to sunlight or any UV source, oxidative stress or chronological ageing. As a consequence, any treatment aiming at increasing epidermal vitamin A would exert a protective effect against these deleterious conditions. Retinoids may counteract some deleterious actions of UV radiation by physical and biological mechanisms. Topical natural retinoic acid precursors such as retinaldehyde or retinol are less irritant than acidic retinoids and may prevent epidermal vitamin A deficiency due to nutritional deficiency, exposure to sunlight or any condition leading to free radical production. Retinoids may be combined with other compounds with complementary actions against ageing, nutritional deficiency and cancer, such as antioxidants, to potentiate their beneficial effects in the skin.

Activation of Nrf2 in keratinocytes causes chloracne (MADISH)-like skin disease in mice.

The transcription factor Nrf2 is a key regulator of the cellular stress response, and pharmacological Nrf2 activation is a promising strategy for skin protection and cancer prevention. We show here that prolonged Nrf2 activation in keratinocytes causes sebaceous gland enlargement and seborrhea in mice due to upregulation of the growth factor epigen, which we identified as a novel Nrf2 target. This was accompanied by thickening and hyperkeratosis of hair follicle infundibula. These abnormalities caused dilatation of infundibula, hair loss, and cyst development upon aging. Upregulation of epigen, secretory leukocyte peptidase inhibitor (Slpi), and small proline-rich protein 2d (Sprr2d) in hair follicles was identified as the likely cause of infundibular acanthosis, hyperkeratosis, and cyst formation. These alterations were highly reminiscent to the phenotype of chloracne/"metabolizing acquired dioxin-induced skin hamartomas" (MADISH) patients. Indeed, SLPI, SPRR2, and epigen were strongly expressed in cysts of MADISH patients and upregulated by dioxin in human keratinocytes in an NRF2-dependent manner. These results identify novel Nrf2 activities in the pilosebaceous unit and point to a role of NRF2 in MADISH pathogenesis.

Inhibition of putative hyalurosome platform in keratinocytes as a mechanism for corticosteroid-induced epidermal atrophy.

The main limitation of using topical corticosteroids in dermatology is their atrophic effects on the skin. We have previously proposed a molecular platform composed of CD44, EGFR, and hyaluronate synthase (HAS) that is functionally defective in dermatoporosis, a chronic cutaneous insufficiency/fragility syndrome. In this study, we explored the molecular mechanisms of the skin atrophy induced by corticosteroids. We observed an important skin atrophy and a significant decrease of hyaluronic acid (HA), its main cell surface receptor CD44, and F-actin in mouse skin treated with topical clobetasol propionate (CP). Human keratinocytes exposed to CP showed an impaired HA secretion and diminished expression of CD44 and HAS3. CP also abolished filopodia of keratinocytes exposed to CP together with a redistribution of CD44 and F-actin depolymerization. We also show that HA fragments of intermediary size (HAFi) induced keratinocyte filopodia and protected them against CP. Topical HAFi induced hyperplasia in mouse epidermis and prevented CP-induced atrophy. Our results suggest that a CD44/EGFR/HAS platform associated with F-actin and filopodia of keratinocytes is the target of corticosteroids for their atrophogenic effects. These observations may lead to the development of new treatment and prevention strategies for corticosteroid-induced skin atrophy.

The cutaneous lesions of dioxin exposure: lessons from the poisoning of Victor Yushchenko.

Several million people are exposed to dioxin and dioxin-like compounds, primarily through food consumption. Skin lesions historically called "chloracne" are the most specific sign of abnormal dioxin exposure and classically used as a key marker in humans. We followed for 5 years a man who had been exposed to the most toxic dioxin, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), at a single oral dose of 5 million-fold more than the accepted daily exposure in the general population. We adopted a molecular medicine approach, aimed at identifying appropriate therapy. Skin lesions, which progressively covered up to 40% of the body surface, were found to be hamartomas, which developed parallel to a complete and sustained involution of sebaceous glands, with concurrent transcriptomic alterations pointing to the inhibition of lipid metabolism and the involvement of bone morphogenetic proteins signaling. Hamartomas created a new compartment that concentrated TCDD up to 10-fold compared with serum and strongly expressed the TCDD-metabolizing enzyme cytochrome P450 1A1, thus representing a potentially significant source of enzymatic activity, which may add to the xenobiotic metabolism potential of the classical organs such as the liver. This historical case provides a unique set of data on the human tissue response to dioxin for the identification of new markers of exposure in human populations. The herein discovered adaptive cutaneous response to TCDD also points to the potential role of the skin in the metabolism of food xenobiotics.

A new spectrophotometric method for simple quantification of melanosomal transfer from melanocytes to keratinocytes.

Three major difficulties must be overcome to establish a quantitative method for melanosomal transfer analysis: (i) establishing a three-dimensional co-culture reassuring direct melanocyte to keratinocyte transfer, (ii) separation of melanocytes and keratinocytes following co-culture and (iii) melanosome quantification in each cell population. Melanocytes and keratinocytes are cultured on the opposite sides of the porous membrane of hanging cell inserts (1µm pores, 2×10(6) pores/cm(2) ). Cell separation is performed after 3days of co-culture by simple trypsinisation. Melanosome quantification in separated cell populations was accomplished by an ELISA-like method using gp-100 as the antigen. Melanocytes and keratinocytes come into 'direct' contact through the pores, and melanosomal transfer is accomplished without cell passage through the membrane. Cell separation by simple trypsinisation results in pure melanocyte and keratinocyte populations. Melanosome quantification by the ELISA-like method proved to be sensitive and specific to distinguish the known inhibitors and inducers of melanosomal transfer.

Synergistic effect of hyaluronate fragments in retinaldehyde-induced skin hyperplasia which is a Cd44-dependent phenomenon.

BACKGROUND: CD44 is a polymorphic proteoglycan and functions as the principal cell-surface receptor for hyaluronate (HA). Heparin-binding epidermal growth factor (HB-EGF) activation of keratinocyte erbB receptors has been proposed to mediate retinoid-induced epidermal hyperplasia. We have recently shown that intermediate size HA fragments (HAFi) reverse skin atrophy by a CD44-dependent mechanism. METHODOLOGY AND PRINCIPAL FINDINGS: Treatment of primary mouse keratinocyte cultures with retinaldehyde (RAL) resulted in the most significant increase in keratinocyte proliferation when compared with other retinoids, retinoic acid, retinol or retinoyl palmitate. RAL and HAFi showed a more significant increase in keratinocyte proliferation than RAL or HAFi alone. No proliferation with RAL was observed in CD44-/- keratinocytes. HA synthesis inhibitor, 4-methylumbelliferone inhibited the proliferative effect of RAL. HB-EGF, erbB1, and tissue inhibitor of MMP-3 blocking antibodies abrogated the RAL- or RAL- and HAFi-induced keratinocyte proliferation. Topical application of RAL or RAL and HAFi for 3 days caused a significant epidermal hyperplasia in the back skin of wild-type mice but not in CD44-/- mice. Topical RAL and HAFi increased epidermal CD44 expression, and the epidermal and dermal HA. RAL induced the expression of active HB-EGF and erbB1. However, treatment with RAL and HAFi showed a more significant increase in pro-HB-EGF when compared to RAL or HAFi treatments alone. We then topically applied RAL and HAFi twice a day to the forearm skin of elderly dermatoporosis patients. After 1 month of treatment, we observed a significant clinical improvement. CONCLUSIONS AND SIGNIFICANCE: Our results indicate that (i) RAL-induced in vitro and in vivo keratinocyte proliferation is a CD44-dependent phenomenon and requires the presence of HA, HB-EGF, erbB1 and MMPs, (ii) RAL and HAFi show a synergy in vitro and in vivo in mouse skin, and (iii) the combination of RAL and HAFi seems to have an important therapeutic effect in dermatoporosis.

High prevalence of potential drug-drug interactions for psoriasis patients prescribed methotrexate or cyclosporine for psoriasis: associated clinical and economic outcomes in real-world practice.

BACKGROUND: Methotrexate (MTX) and cyclosporine (CYC) may adversely interact with common medications in patients with psoriasis. OBJECTIVE: Our purpose was to investigate the prevalence and outcomes of MTX/CYC polypharmacy. METHODS: We evaluated rates of events that may be associated with drug-related toxicity, health care resource utilization and costs for patients with psoriasis in the Ingenix(R) Impact National Managed Care Database (1999-2007) who were exposed or not exposed to potential drug-drug interactions. RESULTS: Among 4,583 (57.6%) exposed and 3,372 (42.4%) nonexposed patients, nonsteroidal anti-inflammatory drugs and antibiotics were the most common drugs with potential interactions. The exposed patients had significantly greater risks of developing renal [adjusted odds ratio (OR): 2.58; p = 0.0145], gastrointestinal (OR: 1.36; p = 0.0197) and pulmonary events (OR: 1.20; p = 0.0470), and significantly greater health care resource utilization (e.g. OR for inpatient and emergency department visits: 1.47; p < 0.0001) and costs (adjusted incremental cost: USD 1,722; p < 0.0001). CONCLUSIONS: MTX/CYC polypharmacy is prevalent in patients with psoriasis and associated with significant risks.

Relationship between clinical response to therapy and health-related quality of life outcomes in patients with moderate to severe plaque psoriasis.

BACKGROUND: Health-related quality of life (HRQOL) outcomes are associated with clinical response to treatment in psoriasis. However, the association between HRQOL outcomes and more substantial degrees of Psoriasis Area and Severity Index (PASI) response and physician and patient global ratings remains ill defined. OBJECTIVE: This study examined the relationship between achieving a 75% or > or =90% improvement in PASI and HRQOL outcome measures. METHODS: Secondary analyses were completed using data for 1,469 patients with moderate to severe plaque psoriasis from two adalimumab clinical trials. HRQOL was measured via the Dermatology Life Quality Index (DLQI) and the Short Form 36 (SF 36) Health Survey. Clinical response was assessed by the PASI, physician's global assessment and patient's global assessment status scores. Clinical response was categorized into 6 groups based on PASI response: <25% (n = 332); 25 to <50% (n = 137); 50 to <75% (n = 170); 75 to <90% (n = 288); 90 to <100% (n = 255), and 100% (n = 192). Analysis of covariance models compared baseline measures and 16-week changes in HRQOL scores. RESULTS: Statistically significant differences were observed between PASI response groups in DLQI total scores and in SF 36 summary and scale scores (p < 0.0001). The PASI 100 and PASI 90 to <100 groups demonstrated a >10-point decrease in DLQI total scores. Moreover, these changes were statistically significantly greater than those observed for the PASI 75 to <90 group (p < 0.001) and the other PASI response groups (p < 0.001). For the SF 36, the greatest changes were observed in the PASI 75 to <90, PASI 90 to <100 and PASI 100 groups, which all had improvements of >4 points in the Mental Component and Physical Component Summary (MCS and PCS) scores. Statistically significantly greater differences in DLQI total and SF 36 summary and scale scores were also observed between patient's global assessment categories (p < 0.0001) and between physician's global assessment categories (p < 0.0001). CONCLUSION: Improvement in PASI response of >75% corresponded to improvements in HRQOL outcome measures for patients with moderate to severe psoriasis. PASI 90 or 100 responders had greater improvements in DLQI total score than PASI 75 responders.

Metabolism and biological activities of topical 4-oxoretinoids in mouse skin.

Retinoic acid mediates most of the biological actions of vitamin A. It is oxidized by CYP26A1 to 4-oxoretinoic acid, considered as an inactive catabolite of retinoic acid. However, in the light of studies reporting the presence of 4-oxoretinal or 4-oxoretinol as the predominant retinoids during morphogenesis, we analyzed the retinoid-like biological activity of these oxoretinoids in mouse skin in vivo. Topical 4-oxoretinal and 4-oxoretinol promoted significant epidermal hyperplasia and metaplasia in mouse tail. They induced a moderate response for epidermal inflammation, compared with retinal, whereas neither 4-oxoretinal nor 4-oxoretinol prevented menadione-induced epidermal lipid peroxidation, unlike retinal and retinol. As analyzed by quantitative PCR, 4-oxoretinal and 4-oxoretinol did not reproduce the significant increased expression of genes coding for keratin 4, amphiregulin, heparin-EGF and CYP26A1, that did induce retinal and retinol. However, both retinal and 4-oxoretinal significantly inhibited the lipopolysaccharide-induced maturation of human dendritic cells in vitro. As analyzed in vivo and in vitro, 4-oxoretinal and 4-oxoretinol were not converted into retinoic acid. We conclude that 4-oxoretinal and 4-oxoretinol exert a moderate direct retinoid-like activity in vivo, thus confirming previous in vitro studies in amphibians showing 4-oxometabolites of vitamin A as bioactive agents rather than inactive catabolites.

Effect of intense pulsed-light exposure on lipid peroxides and thymine dimers in human skin in vivo.

BACKGROUND: Intense pulsed light (IPL) generates high-intensity short flashes of visible light and has been used for about 10 years to improve dermatological conditions such as telangiectasia, pigmented lesions, and skin aging. Although these systems deliver a moderate dose (10-30 J/cm(2)) of visible light, this dose is delivered during a short pulse (2-5 milliseconds), which implies a very high fluence rate (approximately 4000 W/cm(2)). For this reason, we speculated whether the Bunsen-Roscoe law of reciprocity could still be valid in these conditions. OBSERVATIONS: Nine healthy volunteers were exposed to IPL or UV-A or simulated solar UV radiation, and then thymine dimer and lipid peroxide concentrations were determined in skin biopsy specimens of the exposed sites. Only exposure to solar UV radiation (7-J/cm(2) UV-A + 80-mJ/cm(2) UV-B) produced measurable amounts of thymine dimers in DNA from skin biopsy specimens, whereas UV-A radiation (40 J/cm(2)) and IPL (9 J/cm(2)) induced 3-fold and 6-fold increases of cutaneous lipid peroxides, respectively. CONCLUSIONS: These preliminary results indicate that IPL, although filtered for wavelengths shorter than 500 nm, can generate oxidative stress, a typical hallmark of UV-A, but does not induce thymine dimers. This emphasizes the need for long-term studies involving IPL before using this technique in a recurrent manner.