Showing papers in "Experimental Dermatology in 2003"
TL;DR: The present role of MMPs in the development and progression of cancer, focusing on non‐melanoma skin cancers basal (BCC) and squamous (SCC) cell carcinoma, and the possible influence of M MPs in their differences is discussed.
Abstract: Many normal biological processes, such as reproduction, fetal development and wound healing, are critically dependent on controlled degradation of extracellular matrix (ECM) macromolecules. However, excessive degradation of matrix components occurs in pathologic tissue destruction, e.g. in atherosclerosis, rheumatoid arthritis, and cancer. Matrix metalloproteinases (MMPs) are degradative enzymes that play an important role in all aspects of tumor progression by enhancing tumor-induced angiogenesis and destroying local tissue architecture and basement membranes to allow tumor invasion and metastasis. Efficient breakdown of the ECM surrounding invasive cancer islands involves interplay between tumor cells, stromal cells, and inflammatory cells, all of which express a distinct set of MMPs. Besides the classical role of MMPs in degradation of ECM, MMPs may also indirectly influence the tumor microenvironment through the release of growth factors, cryptic sites or angiogenic factors, or through the generation of matrix fragments that inhibit tumor cell proliferation, migration and angiogenesis. This makes the contribution of MMPs to tumorigenesis much more complex than initially thought. Currently, a number of clinical studies have focused on testing MMP inhibitors as potential antineoplastic agents. In this review we discuss the present role of MMPs in the development and progression of cancer, focusing on non-melanoma skin cancers basal (BCC) and squamous (SCC) cell carcinoma, and the possible influence of MMPs in their differences.
334 citations
TL;DR: It is demonstrated that cultured papilla and sheath cell lines were capable of being directed to lipid and bone differentiation and for the first time, clonal DP and DS lines that had extended proliferative capabilities were produced.
Abstract: The adult hair follicle dermal papilla (DP) and dermal sheath (DS) cells are developmentally active cell populations with a proven role in adult hair follicle-cycling activity and unique inductive powers. In stem cell biology, the hair follicle epithelium has recently been the subject of a great deal of investigation, but up to now, the follicle dermis has been largely overlooked as a source of stem cells. Following the sporadic appearance of muscle, lipid and bone-type cells in discretely isolated follicle DP and DS cell primary cultures, we demonstrated that cultured papilla and sheath cell lines were capable of being directed to lipid and bone differentiation. Subsequently, for the first time, we produced clonal DP and DS lines that had extended proliferative capabilities. Dye exclusion has been reported to be an identifying feature of stem cells; therefore, clonal papilla and sheath lines with differing capacity to exclude rhodamine 123 were cultured in medium known to induce adipocyte and osteocyte differentiation. Both DS- and DP-derived clones showed the capacity to make lipid and to produce calcified material; however, different clones had varied behaviour and there was no obvious correlation between their stem cell capabilities and dye exclusion or selected gene expression markers. As a highly accessible source, capable of being discretely isolated, the follicle has important potentially as a stem cell source for tissue engineering and cell therapy purposes. It will also be interesting to compare follicle dermal stem cell properties with the broader stem cell capabilities discovered in skin dermis and investigate whether, as we believe, the follicle is a key dermal stem cell niche. Finally, the discovery of stem cells in the dermis may have implications for certain pathologies in which abnormal differentiation occurs in the skin.
276 citations
TL;DR: Ultraviolet irradiation (UVR) can modulate the process of melanosome transfer from the melanocytes to the keratinocytes and UVR can upregulate expression of PAR‐2 and lectin‐binding receptors and increase phagocytic activity of cultured keratinocyte.
Abstract: Complexion coloration in humans is primarily regulated by the amount and type of melanin synthesized by the epidermal melanocyte. However, additional and equally contributing factors consist of (1) efficient transfer of melanin from the melanocytes to the neighboring keratinocytes and (2) distribution and degradation of the transferred melanosomes by the recipient keratinocytes. Once synthesized in the cell body of the epidermal melanocyte, pigmented melanosomes are translocated down the dendrites and captured at the dendritic tips via various cytoskeletal elements. Molecules recently identified that participate in this process consist of Rab27a, myosin-Va and melanophilin. Eventually, these peripherally localized melanosomes are transferred to keratinocytes by a presently undefined mechanism. The protease-activated receptor-2 (PAR-2) and unidentified surface lectins and glycoproteins facilitate this transfer process. Once incorporated into the keratinocytes, melanosomes are distributed individually or as clusters, aggregated towards the apical pole of the nucleus, and degraded as the keratinocytes undergo terminal differentiation and desquamation. Ultraviolet irradiation (UVR) can modulate the process of melanosome transfer from the melanocytes to the keratinocytes. UVR can upregulate expression of PAR-2 and lectin-binding receptors and increase phagocytic activity of cultured keratinocytes. Therefore, many cellular and molecular events that occur after melanogenesis contribute to skin color.
237 citations
TL;DR: Vitamin C is known for its antioxidant potential and activity in the collagen biosynthetic pathway and Photoprotective properties of topically applied vitamin C have also been demonstrated, placing it as a potential candidate for use in the prevention and treatment of skin ageing.
Abstract: Vitamin C is known for its antioxidant potential and activity in the collagen biosynthetic pathway. Photoprotective properties of topically applied vitamin C have also been demonstrated, placing this molecule as a potential candidate for use in the prevention and treatment of skin ageing. A topically applied cream containing 5% vitamin C and its excipient were tested on healthy female volunteers presenting with photoaged skin on their low-neck and arms in view to evaluate efficacy and safety of such treatment. A double-blind, randomized trial was performed over a 6-month period, comparing the action of the vitamin C cream vs. excipient on photoaged skin. Clinical assessments included evaluation at the beginning and after 3 and 6 months of daily treatment. They were performed by the investigator and compared with the volunteer self assessment. Skin relief parameters were determined on silicone rubber replicas performed at the same time-points. Cutaneous biopsies were obtained at the end of the trial and investigated using immunohistochemistry and electron microscopy. Clinical examination by a dermatologist as well as self-assessment by the volunteers disclosed a significant improvement, in terms of the 'global score', on the vitamin C-treated side compared with the control. A highly significant increase in the density of skin microrelief and a decrease of the deep furrows were demonstrated. Ultrastructural evidence of the elastic tissue repair was also obtained and well corroborated the favorable results of the clinical and skin surface examinations. Topical application of 5% vitamin C cream was an effective and well-tolerated treatment. It led to a clinically apparent improvement of the photodamaged skin and induced modifications of skin relief and ultrastructure, suggesting a positive influence of topical vitamin C on parameters characteristic for sun-induced skin ageing.
208 citations
TL;DR: Under physiological conditions, skin mast cells preferentially localize around nerves, blood vessels and hair follicles, suggesting that these enigmatic, multifacetted protagonists of natural immunity are functionally relevant to many more aspects of tissue physiology than just to the generation of inflammatory and vasodilatory responses to IgE‐dependent environmental antigens.
Abstract: Under physiological conditions, skin mast cells preferentially localize around nerves, blood vessels and hair follicles. This observation, which dates back to Paul Ehrlich, intuitively suggests that these enigmatic, multifacetted protagonists of natural immunity are functionally relevant to many more aspects of tissue physiology than just to the generation of inflammatory and vasodilatory responses to IgE-dependent environmental antigens. And yet, for decades, mainstream-mast cell research has been dominated by a focus on the -undisputedly prominent and important - mast cell functions in type I immune responses and in the pathogenesis and management of allergic diseases. Certainly, it is hard to believe that the very large and rather selectively distributed number of mast cells in normal, uninflamed, non-infected, non-traumatized mammalian skin or mucosal tissue simply hanging around there lazily day and night, just wait for the odd allergen or parasite-associated antigen to come by so the mast cell can finally swing into action. Indeed, the past decade has witnessed a renaissance of mast cell research 'beyond allergy', along with a more systematic exploration of the surprisingly wide range of physiological functions that mast cells may be involved in. The current debate sketches many exciting horizons that have recently come into our vision during this intriguing, ongoing search.
203 citations
TL;DR: The capacity of adult hair follicle dermal cells to participate in new follicle induction and regeneration, and to elicit responses from diverse epithelial partners, demonstrates a level of developmental promiscuity and influence far exceeding that of interfollicular fibroblasts.
Abstract: The capacity of adult hair follicle dermal cells to participate in new follicle induction and regeneration, and to elicit responses from diverse epithelial partners, demonstrates a level of developmental promiscuity and influence far exceeding that of interfollicular fibroblasts. We have recently suggested that adult follicle dermal cells have extensive stem or progenitor cell activities, including an important role in skin dermal wound healing. Given that up to now tissue engineered skin equivalents have several deficiencies, including the absence of hair follicles, we investigated the capacity of follicle dermal cells to be incorporated into skin wounds; to form hair follicles in wound environments; and to create a hair follicle-derived skin equivalent. In our study, we implanted rat follicle dermal cells labelled with a vital dye into ear and body skin wounds. We found that they were incorporated into the new dermis in a manner similar to skin fibroblasts, but that lower follicle dermal sheath also assimilated into hair follicles. Using different combinations of follicle dermal cells and outer root sheath epithelial cells in punch biopsy wounds, we showed that new hair follicles were formed only with the inclusion of intact dermal papillae. Finally by combining follicle dermal sheath and outer root sheath cells in organotypic chambers, we created a skin equivalent with characteristic dermal and epidermal architecture and a normal basement membrane - the first skin to be produced entirely from hair follicle cells. These data support the hypothesis that follicle dermal cells may be important in wound healing and demonstrate their potential usefulness in human skin equivalents and skin substitutes. While we have made progress towards producing skin equivalents that contain follicles, we suggest that the failure of cultured dermal papilla cells to induce follicle formation in wounds illustrates the complex role the follicle dermis may play in skin. We believe that it demonstrates a genuine dichotomy of activity for follicle cells within skin.
195 citations
TL;DR: The differential expression of ERα, ERβ and AR in human skin suggests that the mechanisms by which steroid hormones mediate their effects may be more complex than previously thought and provides further evidence for oestrogen action in non‐classic target tissues.
Abstract: Oestrogens play a major role in non-classic target tissues in both sexes, yet there have been few studies on estrogens and skin. Recently a second oestrogen receptor (ERbeta) has been discovered. Therefore, we have compared the expression of oestrogen receptor alpha (ERalpha), beta (ERbeta), the androgen receptor (AR) and a cell proliferation marker in male and female non-balding scalp skin. ERbeta was the major steroid receptor expressed in human skin. It was highly expressed in epidermis, blood vessels and dermal fibroblasts, in contrast to ERalpha and AR. In the hair follicle, ERbeta expression was localized to nuclei of outer root sheath, epithelial matrix and dermal papilla cells, in contrast to ERalpha, and the AR, which was only expressed in dermal papilla cells. Serial sections also showed strong nuclear expression of ERbeta in the cells of the bulge, while neither ERalpha nor AR was expressed. In the sebaceous gland, ERbeta was expressed in both basal and partially differentiated sebocytes. ERalpha exhibited a similar pattern of expression, while the AR was expressed in the basal and very early differentiated sebocytes. There was no obvious difference in the expression of either oestrogen receptor in male or female skin. The wide distribution of ERbeta in human skin suggests that oestrogens may play an important role in the maintenance of skin and in the regulation of the pilosebaceous unit, and provides further evidence for oestrogen action in non-classic target tissues. The differential expression of ERalpha, ERbeta and AR in human skin suggests that the mechanisms by which steroid hormones mediate their effects may be more complex than previously thought.
137 citations
TL;DR: GA and LA might work on pigmentary lesions not only by accelerating the turnover of the epidermis but also by directly inhibiting melanin formation in melanocytes, an effect independent of their acidic nature.
Abstract: α-Hydroxy acids (AHAs) such as glycolic acid (GA) and lactic acid (LA) have been reported to be effective in treating pigmentary lesions such as melasma, solar lentigines, and postinflammatory hyperpigmentation. The mechanism of this effect might be due to epidermal remodeling and accelerated desquamation, which would result in quick pigment dispersion. However, the direct effect of AHAs on melanin synthesis has not yet been well studied. To elucidate such a direct effect of AHAs on melanogenesis, we performed melanin assays, growth curve determinations, Northern and Western blotting for melanogenic proteins [tyrosinase, tyrosinase related protein (TRP)-1 and TRP-2], and tyrosinase and, 4-dihydroxyphenylalaninechrome tautomerase enzyme activity assays using mouse B16 and human melanoma cells. GA or LA (at doses of 300 or 500 μg/ml) inhibited melanin formation in similar dose-dependent manner, without affecting cell growth. Although the mRNA and protein expression or molecular size of tyrosinase, TRP-1 and TRP-2 were not affected, tyrosinase activity was inhibited. To see whether GA and/or LA directly inhibit tyrosinase catalytic function, the effect of GA and LA on human tyrosinase purified from the melanosome-rich large granule fraction of human melanoma cells was performed. GA or LA were shown to inhibit tyrosinase enzyme activity directly, but this effect was not due to the acidity of GA or LA, because adjusting the pH to 5.6 (the pH of GA and LA at concentrations of 2500 μg/ml), did not affect tyrosinase activity. Taken together, these results show that GA and LA suppress melanin formation by directly inhibiting tyrosinase activity, an effect independent of their acidic nature. GA and LA might work on pigmentary lesions not only by accelerating the turnover of the epidermis but also by directly inhibiting melanin formation in melanocytes.
106 citations
TL;DR: The results suggest that the antioxidative ability against ROS generation in the skin, possessed by antioxidant enzymes and low molecular weight antioxidants, is lowered age dependently.
Abstract: Aging proceeds by highly complicated biochemical processes, in which the involvement of the reactive oxygen species (ROS) and free radicals has been implicated. Although the relationship between UV- induced photoaging and ROS generation has been proposed, it has been difficult to establish direct proof of the generation of ROS in the skin under UV exposure. Recently, we reported finding endogenously generated ROS in the skin of live mice after UVA light exposure by a method of in vivo chemiluminescent detection, in which superoxide anion radical ( � O2 ) and singlet oxygen species ( 1 O2) are contributed. In light of the results, we tried to understand the age-dependent changes in ROS generation in the skin of hairless rats under UVA exposure. Chemiluminescent levels due to ROS in the untreated and UVA-exposed skin decreased age dependently, and the signal intensities in old rats were significantly lower than those in young rats. However, the ratios of chemiluminescent intensities in the UVA-exposed skin to those in the untreated skin were significantly enhanced in an age-dependent manner. These results suggest that the antioxidative ability against ROS generation in the skin, possessed by antioxidant enzymes and low molecular weight antioxidants, is lowered age dependently.
81 citations
TL;DR: Identification of POLH as the XPV gene provides an important instrument for improving molecular diagnostics in XPV families, confirming the autosomal recessive nature of the condition.
Abstract: Xeroderma pigmentosum (XP) is an autosomal recessive disease characterized by sun sensitivity, early onset of freckling and subsequent neoplastic changes on sun-exposed skin. Skin abnormalities result from an inability to repair UV-damaged DNA because of defects in the nucleotide excision repair (NER) machinery. Xeroderma pigmentosum is genetically heterogeneous and is classified into seven complementation groups (XPA-XPG) that correspond to genetic alterations in one of seven genes involved in NER. The variant type of XP (XPV), first described in 1970 by Ernst G. Jung as 'pigmented xerodermoid', is caused by defects in the post replication repair machinery while NER is not impaired. Identification of the XPV gene was only achieved in 1999 by biochemical purification and sequencing of a protein from HeLa cell extracts complementing the PRR defect in XPV cells. The XPV protein, polymerase (pol)eta, represents a novel member of the Y family of bypass DNA polymerases that facilitate DNA translesion synthesis. The major function of (pol)eta is to allow DNA translesion synthesis of UV-induced TT-dimers in an error-free manner; it also possesses the capability to bypass other DNA lesions in an error-prone manner. Xeroderma pigmentosum V is caused by molecular alterations in the POLH gene, located on chromosome 6p21.1-6p12. Affected individuals are homozygous or compound heterozygous for a spectrum of genetic lesions, including nonsense mutations, deletions or insertions, confirming the autosomal recessive nature of the condition. Identification of POLH as the XPV gene provides an important instrument for improving molecular diagnostics in XPV families.
79 citations
TL;DR: It is demonstrated for the first time that in sebaceous glands, in vivo, androgen regulates the synthesis of sebum lipids through the SREBP pathway.
Abstract: Androgens have profound effects on the physiology of the sebaceous gland. Using the hamster ear sebaceous gland model, we performed a detailed kinetic study to clarify the mechanism of androgen action on sebaceous gland function. We demonstrated that the growth of sebaceous glands observed after androgen treatment was due to both an increase in sebocyte proliferation and a parallel induction of sebocyte terminal differentiation, as evidenced by the induction of the synthesis of specific sebaceous lipids such as cholesterol esters, triglycerides, and squalene. Accordingly, the effect of androgen treatment on the mRNA expression of several key enzymes involved in the synthesis of sebaceous lipids has been studied using semi-quantitative RT-PCR. Up-regulation by androgens of mRNA expression of HMG coenzyme A synthase and reductase, acetyl coenzyme A carboxylase (ACC), glycerol 3-phosphate acyl transferase (GPAT), and FAR-17c (stearoyl coenzyme A desaturase homologous), was demonstrated. Because sterol-response element(s) (SREs) are known to be present in the promoters of these genes, we analyzed the expression by RT-PCR and the activation of the transcription factor sterol regulatory element binding protein (SREBP) using immunoblotting experiments. Our results showed that SREBP-1 was up-regulated and rapidly activated after androgen treatment. Altogether, these results demonstrate for the first time that in sebaceous glands, in vivo, androgen regulates the synthesis of sebum lipids through the SREBP pathway.
TL;DR: A reduced amount of total ceramides could be responsible for functional abnormalities of the skin of atopic dermatitis (AD) patients, and the effects of the topical administration of a S.’thermophilus‐containing cream on ceramide levels of stratum corneum from AD patients were investigated.
Abstract: A reduced amount of total ceramides could be responsible for functional abnormalities of the skin of atopic dermatitis (AD) patients. The ability of an experimental cream containing sonicated Streptococcus thermophilus to increase skin ceramide levels in healthy subjects has been previously reported. The aim of the present work was to investigate the effects of the topical administration of a S. thermophilus-containing cream on ceramide levels of stratum corneum from AD patients. A 2-week application of the cream, containing a sonicated preparation of the lactic acid bacterium S. thermophilus, in the forearm skin of 11 patients led to a significant and relevant increase of skin ceramide amounts, which could have resulted from the sphingomyelin hydrolysis through the bacterial sphingomyelinase. Moreover, in all patients the topical application of our experimental cream also resulted in the improvement of the signs and symptoms characteristic of AD skin (i.e. erythema, scaling, pruritus).
TL;DR: This study shows that GA not only directly accelerates collagen synthesis by fibroblasts, but it also modulates matrix degradation and collagen synthesis through keratinocyte‐released cytokines, and confirms that IL‐1α is one of the primary mediators for matrix degradation released from keratinocytes after GA treatment.
Abstract: Glycolic acid (GA), one of the alpha-hydroxy acids, is widely used as an agent for chemical peeling. Although there are several reports about the clinical effects of GA in the literature, its biological mechanism remains mostly unclear, and there are only a few reports about its effects on skin rejuvenation mediated by keratinocytes. The aim of this study was to investigate the effect of GA on the dermal matrix metabolism of keratinocytes and fibroblasts using in vitro and ex vivo systems. Our study shows that GA not only directly accelerates collagen synthesis by fibroblasts, but it also modulates matrix degradation and collagen synthesis through keratinocyte-released cytokines. We confirm that IL-1alpha is one of the primary mediators for matrix degradation released from keratinocytes after GA treatment. These results suggest that GA contributes to the recovery of photodamaged skin through various actions, depending on the skin cell type.
TL;DR: SMaRT™ was used in the context of the 4003delTC mutation in the collagen XVII gene (COL17A1) causing generalized atrophic benign junctional epidermolysis bullosa to demonstrate that SMaRT is feasible in a keratinocyte‐specific context and therefore may be applied in skin gene therapy.
Abstract: Gene therapy of large genes (e.g. plectin and collagen genes) is hampered by size limitations for insertions of the currently used viral vectors. To reduce the size of these insertions spliceosome-mediated RNA trans-splicing (SMaRT), which provides intron-specific gene-correction at the pre-RNA level, can be an alternative approach. To test its applicability in skin gene therapy, SMaRT was used in the context of the 4003delTC mutation in the collagen XVII gene (COL17A1) causing generalized atrophic benign junctional epidermolysis bullosa. A beta-galactosidase (beta-gal) trans-splicing assay system was established using intron 51 of COL17A1 as the target for trans-splicing. In this system, intron 51 is flanked by the 5'exon and the 3'exon of the beta-gal gene, the latter containing two in-frame stop codons. Cotransfection of a pre-trans-splicing molecule consisting of the binding domain of intron 51 and the 3'exon of beta-gal without the stop codons resulted in a 300-fold increase of beta-gal activity compared to controls. A 2-3-fold increase in efficiency was obtained through an elongation of the binding domains. Replacement of the complete 3'end of the COL17A1 gene was shown using a collagen XVII mini-gene construct. The beta-gal assay was used in human keratinocytes to evaluate the influence of a keratinocyte-specific spliceosome background. Reverse transcription polymerase chain reaction and beta-gal activity assay showed functional correction of the stop-codons in cultured human keratinocytes and in an immortalized GABEB cell line harbouring the 4003delTC mutation. These results demonstrate that SMaRT is feasible in a keratinocyte-specific context and therefore may be applied in skin gene therapy.
TL;DR: High‐performance liquid chromatography analysis of pure melanosomal extracts from the human melanoma cell line, FM94, confirmed the production of L‐dopa within these organelles and support a direct function for tyrosine hydroxylase in the melanosome via a concerted action with tyrosinase to promote pigmentation.
Abstract: Both human epidermal melanocytes and keratinocytes have the full capacity for de novo synthesis of 6(R) L-erythro 5,6,7,8, tetrahydrobiopterin, the essential cofactor for the rate limiting step in catecholamine synthesis, via tyrosine hydroxylase. Catecholamine synthesis has been demonstrated in proliferating keratinocytes of the epidermis in human skin. This study presented herein identified for the first time the expression of tyrosine hydroxylase isozyme I mRNA within the melanocyte. The location of the enzyme was demonstrated in both the cytosol and melanosomes of human epidermal melanocytes, using immunohistochemistry and immunofluorescence double staining as well as immunogold electron microscopy. High-performance liquid chromatography (HPLC) analysis of pure melanosomal extracts from the human melanoma cell line, FM94, confirmed the production of L-dopa within these organelles. In addition, enzyme activities for both tyrosine hydroxylase and tyrosinase were measured in the same preparations, by following the catalytic release of tritiated water from L-[3,5-3H]tyrosine. The melanosomal membrane location of tyrosine hydroxylase together with tyrosinase implies a coupled interaction, where L-dopa production facilitates the activation of tyrosinase. Our results support a direct function for tyrosine hydroxylase in the melanosome via a concerted action with tyrosinase to promote pigmentation.
TL;DR: Elafin is a skin‐derived serine‐protease inhibitor thought to be important to prevent human leukocyte elastase‐mediated tissue damage and might play an important role in maintaining the integrity of the human epidermis.
Abstract: Elafin is a skin-derived serine-protease inhibitor It is thought to be important to prevent human leukocyte elastase-mediated tissue damage and might play an important role in maintaining the integrity of the human epidermis Recent studies have provided evidence for an antimicrobial activity of elafin against P aeruginosa As gram-negative infections typically occur in barrier-disrupted skin we were interested to determine whether supernatants of the gram-negative bacteria P aeruginosa and Escherichia coli were capable of inducing elafin expression Supernatants of various P aeruginosa strains stimulated elafin mRNA-expression and protein release, whereas supernatants of E coli did not induce elafin expression In non-differentiated cells the relative increase of elafin mRNA was much higher (100-fold) than in differentiated cells (sixfold), although the latter exhibited higher constitutive mRNA-expression (150-fold) However, concentrations of secreted elafin were similar in differentiated and non-differentiated cells after stimulation We could not confirm a bactericidal effect against P aeruginosa as described previously but observed that its growth was inhibited as demonstrated for different strains in liquid cultures Growth of E coli was not affected by elafin In conclusion, the data presented in this paper suggest that elafin represents an innate immune response factor induced by secreted products of P aeruginosa Besides its elastase inhibitory potency elafin is an antimicrobial agent against P aeruginosa
TL;DR: Freeze‐fracture and immunoreplica electron microscopy on primary‐cultured human dermal endothelial cells showed that claudin‐5 was localized at tight junctions, and confirmed that TJs in dermal vascular endothelia cells are composed of claudIn‐5.
Abstract: Claudins and occludin are integral membrane proteins at tight junctions (TJs). We examined subcellular localization of claudin-5 and occludin in dermal vascular endothelia. Immunofluorescence staining showed that claudin-5 was expressed at the cell-cell border of dermal vascular endothelia in mouse skin. However, in some dermal vessels, claudin-5 expression was markedly decreased or absent in amount by double-immunofluorescence stainings with PECAM-1 and PAL-E. In contrast, occludin was not detected in dermal vessels. Freeze-fracture and immunoreplica electron microscopy on primary-cultured human dermal endothelial cells showed that claudin-5 was localized at tight junctions. These findings confirmed that TJs in dermal vascular endothelial cells are composed of claudin-5.
TL;DR: It is now proposed that multiplication of sensory protohairs caused by mutations in patterning genes initially protected the delicate barrier tissues and eventually produced the minimal morphology necessary for an insulatory pelage.
Abstract: A 1972 model for the evolutionary origin of hair suggested a primary mechanoreceptor role improving behavioral thermoregulation contributed to the success of late Paleozoic mammal-like reptiles. An insulatory role appeared secondarily subsequent to protohair multiplication. That model is updated in light of new data on (a) palaeoecology of mammalian ancestors; (b) involvement of HRPs in keratinization; (c) lipogenic lamellar bodies that form the barrier to cutaneous water loss; and (d) growth factors involved in hair follicle embryogenesis and turnover. It is now proposed that multiplication of sensory protohairs caused by mutations in patterning genes initially protected the delicate barrier tissues and eventually produced the minimal morphology necessary for an insulatory pelage. The latter permitted Mesozoic mammals to occupy the nocturnal niche ‘in the shadow of dinosaurs’. When the giant reptiles became extinct, mammals underwent rapid radiation and reemerged as the dominant terrestrial vertebrates.
TL;DR: Using several human in vitro three‐dimensional models in order to assess both the photodamage and the photoprotection afforded by sunscreens, the results showed that appropriateSunscreens could efficiently prevent the damage described above.
Abstract: Biological and clinical effects of sun exposures are characterized by short-term reactions, i.e. sunburn reaction and suntan, as well as long-term consequences corresponding to photoaging and photocancers. We have developed several human in vitro three-dimensional models in order to assess both the photodamage and the photoprotection afforded by sunscreens. Using a full thickness reconstructed skin comprising a differentiated epidermis and a living dermal equivalent, UVB- and UVA-induced biological markers could be found at both the keratinocyte and the fibroblast level. Typical markers of the sunburn reaction could be reproduced in that model as well as dermal damages related to the photoaging process. Another model of reconstructed epidermis, comprising keratinocytes but also melanocytes and Langerhans cells, has been developed. The study of the UV-induced pigmentation as possible using the pigmented reconstructed epidermis and allowing to reproduce the epidermal melanin unit. The assessment of cellular parameters related to UV-induced immunosuppression could be performed using the reconstructed epidermis containing Langerhans cells. Exposure to solar-simulated radiation provokes morphological alterations and the reduction in numbers of Langerhans cells within the exposed epidermis. Using all these models, the efficiency of sunscreens could be envisaged after topical application. The results showed that appropriate sunscreens could efficiently prevent the damage described above.
TL;DR: It is shown that the selection of MM cells for increased ECM‐independent local growth was accompanied by overexpression of macrophage migration inhibiting factor (MIF), an important modulator of both cell cycle progression and angiogenesis, and cathepsin Z, a novel member of the family of matrix degrading proteinases.
Abstract: Currently, the scale and consistency of changes of gene expression profiles in models of melanoma progression are largely unknown. Therefore, we investigated siblings of cell lines of malignant melanomas (MM), which have been selected by nude mouse passages for (a) increased tumorigenicity (local ECM-independent growth), (b) metastatic potential, or (c) selected for increased invasiveness using the Boyden chamber. cDNA array analysis surveying more than 27.000 transcripts per cell line showed that 1.5–2.8% of all detectable transcripts were consistently differentially regulated during the selection processes in those models. Using array analysis, we identified 33 individual transcripts that exhibited significant differential hybridization paralleling the increased aggressiveness of the selected progeny. Because some of those genes could play a significant functional role in the progression of MM, we additionally proved their regulative pattern using Northern blotting. Among others, progressive overexpression of osteonectin/SPARC, a molecule that is known to be involved in tissue remodeling and angiogenesis, was found in the selected offspring from all three experimental models and may therefore be considered as a potential marker for aggressive MM as well as a promising therapeutic target. We further show that the selection of MM cells for increased ECM-independent local growth was accompanied by overexpression of macrophage migration inhibiting factor (MIF), an important modulator of both cell cycle progression and angiogenesis, and cathepsin Z, a novel member of the family of matrix degrading proteinases.
TL;DR: Two overlapping genes, SEEK1 and SPR1, are characterized and the cloning of its orthologs in mouse and pig is reported, both of which are expressed in normal and psoriasis skin.
Abstract: Psoriasis is a chronic skin disease that results in red and scaly lesions. Several psoriasis susceptibility loci have been identified across the genome, of which PSORS1 on 6p21.3 is predominant. There is an ongoing debate regarding whether the HLA-C allele, Cw*0602, can be considered the major predisposing factor in this region. Investigation of other genes in the PSORS1 region with regard to psoriasis may provide alternate candidates to HLA-C. We have characterized two overlapping genes, SEEK1 and SPR1. SEEK1 encodes two putative protein isoforms: the first being one of 152 amino acids from the full-length splice-isoform (exon 1-6), and the second being one of 100 amino acids from an alternate splice-isoform (exon 1 and 6). SPR1 encodes a highly conserved protein of 134 amino acids, and in addition to characterization of human SPR1 we report the cloning of its orthologs in mouse and pig. Both SEEK1 and SPR1 are expressed in normal and psoriasis skin. In a case-control study, five of the nine single nucleotide polymorphisms (SNPs) found in SEEK1 were associated with psoriasis, while one of the four SNPs found in SPR1 showed association. Testing the Cw*0602 confounding status revealed that two of the SEEK1 SNPs showed Cw*0602-independent association, while the SPR1 SNP showed Cw*0602-dependent association. The second exon of SEEK1, containing the two Cw*0602-independent SNPs, showed the highest concentration of the psoriasis-associating SNPs, but did not appear to be translated.
TL;DR: Comparative hybridization by means of cDNA arrays assisted in identifying a series of novel progression‐associated changes in gene expression, confirming, at the same time, a number of previously described results.
Abstract: In order to identify genes relevant for melanoma development, we carried out cDNA array experiments employing an in vitro model of human melanoma progression, consisting of two cell lines: one, LP, derived from a primary melanoma and the other, LM, from its metastatic supraclavicular lymph node Basic cDNA array data identified 26 genes as down-regulated in the LM cell line Northern blot analysis confirmed an effective transcriptional down-regulation for five out of 13 genes analyzed The products of these five genes belong to different functional protein types, such as transcription and translation regulators (Edg-2, eIF-3 p110, and RNPL/RBM3), extracellular communicators (PRSS11) and members of the major histocompatibility complex (β2-microglobulin) Some previously described differences in expression patterns, such as loss of HLA I, were confirmed by our array data In addition, we identified and validated for the first time the reduced expression level of several genes during melanoma progression In particular, reduced Edg-2 gene product expression was also confirmed in a group of 50 primary melanomas and unrelated metastases In conclusion, comparative hybridization by means of cDNA arrays assisted in identifying a series of novel progression-associated changes in gene expression, confirming, at the same time, a number of previously described results
TL;DR: In this article, the authors studied the mechanism of UVB-induced expression of COX-2 focusing on the signal transduction pathway involved, and showed that oxidative stress in association with activation of EGFR, ERK, p38 MAP kinase, and PI3-kinase plays crucial roles in the UVB induction of expression.
Abstract: Because selective inhibition of cyclooxygenase-2 (COX-2) suppressed the induction of skin tumors in mice by UV and as UV has been shown to induce expression of COX-2 in skin and cells, COX-2 may be crucial for photocarcinogenesis of the skin. We studied the mechanism of UVB-induced expression of COX-2 focusing on the signal transduction pathway involved. Hydrogen peroxide (H2O2) treatment of HaCaT cells induced expression of COX-2 and pretreatment with the antioxidant N-acetylcysteine (NAC) partly inhibited the UVB-induced expression of COX-2 protein in HaCaT cells, suggesting that oxidative stress contributes to COX-2 induction. To examine the signaling pathways involved in the UVB-induced expression of COX-2 in HaCaT cells, we analysed the expression of COX-2 protein after treatment with various inhibitors of signaling molecules. Inhibition of EGFR by a specific inhibitor and by a neutralizing antibody suppressed the induction of COX-2 expression by UV. Although a neutralizing antibody to transforming growth factor-alpha (TGF-alpha) suppressed COX-2 expression induced by TGF-alpha, it did not suppress COX-2 expression by UV, indicating that a direct activation of EGFR is involved. Treatment of cells at low temperature (4 degrees C) inhibited UVB-induced JNK activation, but it did not inhibit COX-2 expression by UV. Inhibitors of MEK, p38 MAP kinase and PI3-kinase, suppressed the induction of COX-2 expression by UV. In contrast, an erbB-2 inhibitor augmented the UVB-induced increase of COX-2 protein. These data indicate that oxidative stress in association with activation of EGFR, ERK, p38 MAP kinase, and PI3-kinase plays crucial roles in the UVB induction of expression of COX-2.
TL;DR: Dairy soy (soya) oil content and the soy‐derived phytoestrogen genistein as potential modifying agents for C3H/HeJ mouse AA were considered and no significant association was observed between the extent of hair loss and diet orgenistein injection.
Abstract: Alopecia areata (AA) is a complex, multi-factorial disease where genes and the environment may affect susceptibility and severity Diet is an environmental factor with the potential to influence disease susceptibility We considered dietary soy (soya) oil content and the soy-derived phytoestrogen genistein as potential modifying agents for C3H/HeJ mouse AA Normal haired C3H/HeJ mice were grafted with skin from spontaneous AA affected mice, a method previously shown to induce AA Grafted mice were given one of three diets containing 1%, 5% or 20% soy oil and observed for AA development In a separate study, mice on a 1% soy oil diet were injected with 1 mg of genistein three times per week for 10 weeks or received the vehicle as a control Of mice on 1%, 5%, and 20% soy oil diets, 43 of 50 mice (86%), 11 of 28 mice (39%), and 2 of 11 mice (18%) developed AA, respectively Four of 10 mice injected with genistein and 9 of 10 controls developed AA Mice with AA had hair follicle inflammation consistent with observations for spontaneous mouse AA, but no significant association was observed between the extent of hair loss and diet or genistein injection Mice that failed to develop AA typically experience white hair regrowth from their skin grafts associated with a moderate macrophage and dendritic cell infiltration Soy oil and derivatives have previously been reported to modify inflammatory conditions Hypothetically, soy oil compounds may act on C3H/HeJ mice through modulating estrogen-dependent mechanisms and/or inflammatory activity to modify AA susceptibility
TL;DR: It is suggested that there are defects in the regulation of the transcription factors: signal transducer and activator of transcription (STAT‐1α), interferon regulated factor‐1 (IRF‐1) and NFκB which lead to loss of growth and differentiation control when the cells are subjected to physico‐chemical and immunological stress.
Abstract: Psoriasis is a chronic inflammatory skin disease characterized by the accumulation of red, scaly plaques on the skin. The plaques result from hyperproliferation and incomplete differentiation of keratinocytes (KC) in a process that seems to be driven, in part by skin-infiltrating leucocytes. We believe that the KC have inherent defects in intracellular signalling which could be usefully targeted to allow the development of more effective therapies. We suggest that there are defects in the regulation of the transcription factors: signal transducer and activator of transcription (STAT-1alpha), interferon regulated factor-1 (IRF-1) and NFkappaB which lead to loss of growth and differentiation control when the cells are subjected to physico-chemical and immunological stress. We also highlight recent studies that suggest that peroxisome proliferator-activated receptors, the notch receptor and defects in calcium and other ion transporting proteins may contribute to impairment in the ability of psoriatic KC to differentiate. The role of these systems in the development of the psoriatic phenotype and tests of these hypotheses are proposed.
TL;DR: Platelet‐derived growth factor is a potent mitogenic factor for many cell types and has been shown to be important in follicular development and vasculogenesis, and by examining the expression of PDGF ligands, it is shown that cultured FKs synthesize both PDGF‐A andPDGF‐B, whereas, DPCs only express PDGF‑A.
Abstract: Platelet-derived growth factor (PDGF) is a potent mitogenic factor for many cell types and has been shown to be important in follicular development and vasculogenesis. In this study, we examined the expression pattern of both PDGF factors and their corresponding receptors in mesenchyme-derived dermal papilla cells (DPCs) and epithelial follicular keratinocytes (FKs). Both types of PDGF receptors are expressed in FKs, whereas DPCs only express PDGF receptor beta on the protein level, a finding also seen in whole organ cultures. By examining the expression of PDGF ligands, we were able to show that cultured FKs synthesize both PDGF-A and PDGF-B, whereas, DPCs only express PDGF-A. As immunomodulatory cytokines were shown to affect hair growth, we investigated the effects of IL-1beta, IL-4, TNF-alpha, TGF-beta and IFN-gamma on the expression levels of PDGF factors in cultured DPCs and FKs. Interestingly, we could show a significant down-regulatory effect by catagen-inducing cytokines like IL-1beta or IFN-gamma, suggesting a possible involvement of PDGF signaling in the induction of catagen. The question concerning the latter hypothesis remains to be elucidated in further studies on whole organ cultures.
TL;DR: The pathophysiology of photoaging of the skin caused by chronic inflammation after UVR is reviewed and discussed, with a focus on oxidative stress.
Abstract: Photoaging is significantly different from chronological aging in both clinical and histological appearance. It has been suggested that oxidative stress, generated by ultraviolet radiation (UVR), leads to photoaging over a long period. The presence of 8-OHdG, and oxidatively modified proteins such as 4-hydroxy-2-nonenal-modified protein, 3-L-nitro-tyrosine and N -e (carboxymethyl)lysine in UV-exposed skin specimens, supports this theory. The pathophysiology of photoaging of the skin caused by chronic inflammation after UVR is reviewed and discussed, with a focus on oxidative stress.
TL;DR: It is reported that tobacco smoke extract blocks cellular responsiveness to TGF‐β1 through the induction of a non‐functional latent form of TGFβ1, and downregulation of the TGF•β1 receptor.
Abstract: We have recently shown that tobacco smoking, like ultraviolet A radiation, is an important factor contributing to premature skin aging. We found that tobacco smoke extract decreased type I and III procollagen, increased tropoelastin mRNA, and induced abnormal accumulation of proteoglycans and matrix metalloproteinase (MMP)-1 and MMP-3 in cultured skin fibroblasts. This indicated that common molecular features might underlie the premature aging of the skin induced by tobacco smoke extract, including abnormal regulation of extracellular matrix deposition through elevated MMPs, reduced collagen production, abnormal tropoelastin accumulation, and altered proteoglycans. With the exception that reactive oxygen species were mediated in the aging process, transforming growth factor (TGF)-β1 was found to play a crucial role in the age-related alterations induced by tobacco smoke extract. Here we report that tobacco smoke extract blocks cellular responsiveness to TGF-β1 through the induction of a non-functional latent form of TGF-β1, and downregulation of the TGF-β1 receptor. This paper shows the evidence for the role of tobacco smoking in skin aging and describes how modulation of TGF-β1 levels might retard premature skin aging.
TL;DR: Investigation of the participation of the PKC system in the proliferation and high cell density‐induced differentiation of the human immortalized keratinocyte line HaCaT shows that the endogenous activation of PKC regulates the expressions of the late differentiation markers, and that the exogenous activation ofPKC by PMA results in the induction of terminal differentiation.
Abstract: Protein kinase C (PKC) isoforms play pivotal roles in the regulation of differentiation of normal human epidermal keratinocytes (NHEK) In this study, we investigated the participation of the PKC system in the proliferation and high cell density-induced differentiation of the human immortalized keratinocyte line HaCaT HaCaT keratinocytes possessed a characteristic PKC isoform pattern (PKC alpha, beta, gamma, delta, epsilon, eta, theta, zeta), which altered during proliferation and differentiation The GF109203X compound, a selective PKC inhibitor, suppressed the expressions of the lat (granular cell) differentiation markers involucrin (INV) and filaggrin (FIL), and the terminal marker keratinocyte-specific transglutaminase-1 (TG), but did not affect the level of the early (spinous cell) marker keratin 10 (K10) and cellular proliferation Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, inhibited proliferation, elevated intracellular calcium concentration, decreased the expression of K10, and increased the expressions of INV, FIL, and TG These data indicate that the endogenous activation of PKC regulates the expressions of the late differentiation markers, and that the exogenous activation of PKC by PMA results in the induction of terminal differentiation Because the cellular effects of PMA were accompanied by differential down-regulations of the sensitive PKC isoforms in proliferating and differentiating cultures, our findings argue for the differential roles of the existing PKC isoforms in the regulation of cellular proliferation and high cell density-induced differentiation of HaCaT cells
TL;DR: The inflammatory response observed in the subgroup of CIU patients with positive ASST and serum‐evoked histamine‐release in vitro from basophils is characterized in comparison with unaffected skin and healthy donors.
Abstract: In approximately one-third of patients with chronic idiopathic urticaria (CIU), autoantibodies against the high-affinity IgE receptor and/ or against IgE can be detected and a wheal-and-flare response can be provoked by the intradermal injection of autologous serum (ASST). In this study we aimed to further characterize the inflammatory response observed in the subgroup of CIU patients with positive ASST and serum-evoked histamine-release in vitro from basophils in comparison with unaffected skin and healthy donors. An immunohistochemical analysis of infiltrating cells (CD4, MPO, EG1, EG2, tryptase), cytokines (IL-4, IL-5, IFN-gamma), chemokines and chemokine receptors (IL-8, CCR3, CXCR3), and adhesion molecules (ICAM-1, VCAM-1, ELAM-1) was performed on seven selected patients (four males and three females; median age: 45 years; range: 22-57) and five healthy donors. Cytokine evaluation was also performed in five psoriatic patients to obtain an additional control. In spontaneous wheals we observed an increased number of CD4+ T lymphocytes when compared with the controls, and an increased number of neutrophils and eosinophils, whereas mast cells did not show a significant variation. A significant expression for IL-4 and IL-5 could only be observed in lesional skin, while IFN-gamma showed a slight expression in the same site. Chemokine receptors CCR3 and CXCR3 did not show a defined polarized response in either lesional or unaffected skin. An increased expression of all cellular adhesion molecules (CAMs) studied was detected in spontaneous wheals. The lack of a significant difference in the expression of tryptase + mast cells, T lymphocytes, IL-8, CXCR3 and CCR3, a few CAMs between the lesional and unaffected skin of CIU patients suggests a wide immunological activation that involves not only lesional tissues, but possibly extends to the whole of the skin's immune system.