RESUMEN
BACKGROUND: Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease of the skin and mucous membranes. This disease typically affects the elderly and presents with itch and localized or, most frequently, generalized bullous lesions. A subset of patients only develops excoriations, prurigo-like lesions, and eczematous and/or urticarial erythematous lesions. The disease, which is significantly associated with neurological disorders, has high morbidity and severely impacts the quality of life. OBJECTIVES AND METHODOLOGY: The Autoimmune blistering diseases Task Force of the European Academy of Dermatology and Venereology sought to update the guidelines for the management of BP based on new clinical information, and new evidence on diagnostic tools and interventions. The recommendations are either evidence-based or rely on expert opinion. The degree of consent among all task force members was included. RESULTS: Treatment depends on the severity of BP and patients' comorbidities. High-potency topical corticosteroids are recommended as the mainstay of treatment whenever possible. Oral prednisone at a dose of 0.5 mg/kg/day is a recommended alternative. In case of contraindications or resistance to corticosteroids, immunosuppressive therapies, such as methotrexate, azathioprine, mycophenolate mofetil or mycophenolate acid, may be recommended. The use of doxycycline and dapsone is controversial. They may be recommended, in particular, in patients with contraindications to oral corticosteroids. B-cell-depleting therapy and intravenous immunoglobulins may be considered in treatment-resistant cases. Omalizumab and dupilumab have recently shown promising results. The final version of the guideline was consented to by several patient organizations. CONCLUSIONS: The guidelines for the management of BP were updated. They summarize evidence- and expert-based recommendations useful in clinical practice.
Asunto(s)
Dermatología , Penfigoide Ampolloso , Venereología , Corticoesteroides/uso terapéutico , Anciano , Vesícula/tratamiento farmacológico , Humanos , Penfigoide Ampolloso/diagnóstico , Penfigoide Ampolloso/tratamiento farmacológico , Calidad de VidaRESUMEN
BACKGROUND: The incidence of skin cancers has been increasing steadily over the last decades. Although there have been significant breakthroughs in the management of skin cancers with the introduction of novel diagnostic tools and innovative therapies, skin cancer mortality, morbidity and costs heavily burden the society. OBJECTIVE: Members of the European Association of Dermato-Oncology, European Academy of Dermatology and Venereology, International Dermoscopy Society, European Dermatology Forum, European Board of Dermatovenereology of the European Union of Medical Specialists and EORTC Cutaneous Lymphoma Task Force have joined this effort to emphasize the fundamental role that the specialist in Dermatology-Venereology has in the diagnosis and management of different types of skin cancer. We review the role of dermatologists in the prevention, diagnosis, treatment and follow-up of patients with melanoma, non-melanoma skin cancers and cutaneous lymphomas, and discuss approaches to optimize their involvement in effectively addressing the current needs and priorities of dermato-oncology. DISCUSSION: Dermatologists play a crucial role in virtually all aspects of skin cancer management including the implementation of primary and secondary prevention, the formation of standardized pathways of care for patients, the establishment of specialized skin cancer treatment centres, the coordination of an efficient multidisciplinary team and the setting up of specific follow-up plans for patients. CONCLUSION: Skin cancers represent an important health issue for modern societies. The role of dermatologists is central to improving patient care and outcomes. In view of the emerging diagnostic methods and treatments for early and advanced skin cancer, and considering the increasingly diverse skills, knowledge and expertise needed for managing this heterogeneous group of diseases, dermato-oncology should be considered as a specific subspecialty of Dermatology-Venereology.
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Dermatología , Melanoma , Enfermedades de la Piel , Neoplasias Cutáneas , Venereología , Dermatólogos , Humanos , Neoplasias Cutáneas/diagnóstico , Neoplasias Cutáneas/terapiaRESUMEN
BACKGROUND: Pemphigus encompasses a group of life-threatening autoimmune bullous diseases characterized by blisters and erosions of the mucous membranes and skin. Before the era of immunosuppressive treatment, pemphigus was almost always fatal. Due to its rarity, only few randomized controlled therapeutic trials are available. Recently, rituximab has been approved as first-line treatment for moderate and severe pemphigus vulgaris in Europe and the United States. OBJECTIVES: The Autoimmune blistering diseases Task Force of the European Academy of Dermatology and Venereology (EADV) has initiated a throughout update of the guideline for the management of patients with pemphigus. RESULTS: The guidelines for the management of pemphigus were updated, and the degree of consent among all task force members was included. The final version of the guideline was consented by the European Dermatology Forum (EDF) and several patient organizations.
Asunto(s)
Dermatología , Guías como Asunto , Pénfigo , Venereología , Academias e Institutos , Europa (Continente) , Humanos , Pénfigo/diagnóstico , Pénfigo/tratamiento farmacológicoRESUMEN
BACKGROUND: Survivin is detected in few adult normal cells and it is highly expressed in cancer. Nuclear survivin facilitates cell cycle entry, whereas the mitochondrial pool protects cells from apoptosis. Survivin is overexpressed in keratinocyte stem cells (KSCs) and protects them from apoptosis. METHODS: As KSCs are at the origin of squamous cell carcinoma (SCC), we evaluated survivin expression in normal and cancerous skin in vivo by immunohistochemistry and western blotting. HaCaT cells overexpressing survivin and wound-healing assay are used. Analysis of variance and Student's T-tests are used for statistical analysis. RESULTS: Survivin is localised in both the cytoplasm and nucleus of normal adult and young keratinocytes. Nuclear survivin is detected in one every 10 of 11 basal keratinocytes. When present in suprabasal cells, nuclear survivin is coexpressed with K10 but not with K15 or p75-neurotrophin receptor (p75NTR), a transit amplifying cell marker. Nuclear, but not cytoplasmic, survivin expression markedly increases in actinic keratosis and in SCC in situ, as compared with normal epidermis, and it is highest in poorly differentiated SCC. In SCC tumours, nuclear survivin-positive cells are mainly K10/p75NTR-negative and K15-positive. In poorly differentiated tumours, survivin mostly localises in the deep infiltrating areas. When overexpressed in keratinocytes, survivin increases cell migration. CONCLUSION: High survivin expression and the subcellular localisation of survivin correlate with keratinocyte differentiation and are associated with undifferentiated and more invasive SCC phenotype.
Asunto(s)
Carcinoma de Células Escamosas/metabolismo , Proteínas Inhibidoras de la Apoptosis/biosíntesis , Neoplasias Cutáneas/metabolismo , Piel/metabolismo , Adolescente , Adulto , Factores de Edad , Anciano , Anciano de 80 o más Años , Carcinoma de Células Escamosas/patología , Linaje de la Célula , Núcleo Celular/metabolismo , Niño , Preescolar , Humanos , Lactante , Recién Nacido , Queratinocitos/metabolismo , Persona de Mediana Edad , Invasividad Neoplásica , Proteínas de Neoplasias/biosíntesis , Neoplasias Cutáneas/patología , Survivin , Adulto JovenRESUMEN
Transplantation of epithelia derived from keratinocyte stem cells transduced by retroviral vectors is a potential therapy for epidermolysis bullosa (EB), a family of inherited skin adhesion defects. The biosafety characteristics of retroviral vectors in keratinocytes are, however, poorly defined. We developed self-inactivating (SIN) vectors derived from the Moloney murine leukemia (MLV) and the human immunodeficiency (HIV) viruses expressing therapeutic levels of LAMB3, a transgene defective in junctional EB, and tested their integration profile in human primary keratinocytes. The SIN-HIV vector showed the expected preference for transcribed genes while the SIN-MLV vector integrated preferentially in regulatory elements, but showed a significantly lower tendency to target cell growth-related genes, transcription start sites and epigenetically defined promoters compared with a wild-type MLV vector in an epithelial cell context. A quantitative gene expression assay in individual keratinocyte clones showed that MLV-derived vectors deregulate expression of targeted genes at a lower frequency than in hematopoietic cells, and that the SIN-MLV design has the lowest activity compared to both MLV and SIN-HIV vectors. This study indicates that SIN-MLV vectors may have a better safety profile in keratinocyte than in hematopoietic cells, and be a reasonable alternative to lentiviral vectors for gene therapy of inherited skin disorders.
Asunto(s)
Moléculas de Adhesión Celular/genética , Epidermólisis Ampollosa/genética , Epidermólisis Ampollosa/terapia , Vectores Genéticos , Queratinocitos/metabolismo , Virus de la Leucemia Murina de Moloney/genética , Integración Viral , Animales , Moléculas de Adhesión Celular/metabolismo , Epidermólisis Ampollosa/metabolismo , Regulación de la Expresión Génica , Terapia Genética , VIH-1/genética , Células HeLa , Humanos , Ratones , Virus de la Leucemia Murina de Moloney/fisiología , Regiones Promotoras Genéticas , Células 3T3 Swiss , Transducción Genética , Transgenes , Inactivación de Virus , KalininaRESUMEN
p75 neurotrophin receptor (p75NTR) belongs to the TNF-receptor superfamily and signals apoptosis in many cell settings. In human epidermis, p75NTR is mostly confined to the transit-amplifying (TA) sub-population of basal keratinocytes. Brain-derived neurotrophic factor (BDNF) or neurotrophin-4 (NT-4), which signals through p75NTR, induces keratinocyte apoptosis, whereas ß-amyloid, a ligand for p75NTR, triggers caspase-3 activation to a greater extent in p75NTR transfected cells. Moreover, p75NTR co-immunoprecipitates with NRAGE, induces the phosphorylation of c-Jun N-terminal kinase (JNK) and reduces nuclear factor kappa B (NF-κB) DNA-binding activity. p75NTR also mediates pro-NGF-induced keratinocyte apoptosis through its co-receptor sortilin. Furthermore, BDNF or ß-amyloid cause cell death in TA, but not in keratinocyte stem cells (KSCs) or in p75NTR silenced TA cells. p75NTR is absent in lesional psoriatic skin and p75NTR levels are significantly lower in psoriatic than in normal TA keratinocytes. The rate of apoptosis in psoriatic TA cells is significantly lower than in normal TA cells. BDNF or ß-amyloid fail to induce apoptosis in psoriatic TA cells, and p75NTR retroviral infection restores BDNF- or ß-amyloid-induced apoptosis in psoriatic keratinocytes. These results demonstrate that p75NTR has a pro-apoptotic role in keratinocytes and is involved in the maintenance of epidermal homeostasis.
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Apoptosis , Queratinocitos/metabolismo , Psoriasis/metabolismo , Receptor de Factor de Crecimiento Nervioso/metabolismo , Transducción de Señal , Proteínas Adaptadoras del Transporte Vesicular/genética , Proteínas Adaptadoras del Transporte Vesicular/metabolismo , Péptidos beta-Amiloides , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Caspasa 3/genética , Caspasa 3/metabolismo , Línea Celular , Activación Enzimática/genética , Humanos , Queratinocitos/patología , FN-kappa B/genética , FN-kappa B/metabolismo , Psoriasis/genética , Receptor de Factor de Crecimiento Nervioso/genéticaRESUMEN
Neurotrophins (NTs) belong to a family of structurally and functionally related proteins that, depending on the tissue context and the receptors involved, promote neuronal cell survival and differentiation or cell death. NTs also exert important functions in other organs besides the nervous system, including the skin. The presence in the skin of diverse cell types which are able to secrete and/or to respond to stimulation by NTs creates a unique network of molecular signaling in the cutaneous microenvironment. This review summarizes currently available data on the expression and function of NTs and their receptors in several cell types in the skin (namely, keratinocytes, melanocytes and fibroblasts). The role of the skin NT network in the development and maintenance of some relevant skin diseases is presented and the potential implications for therapeutic intervention are discussed.
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Factores de Crecimiento Nervioso/fisiología , Enfermedades de la Piel/etiología , Fenómenos Fisiológicos de la Piel , HumanosRESUMEN
Neurotrophins regulate cutaneous innervation, act as growth and motility factors on structural skin cells such as keratinocytes and fibroblasts, modulate cutaneous immune function and even serve as stress mediators in skin biology. The multilayered neurotrophin interaction with skin biology through high affinity specific tyrosinekinase receptors and the Janus-faced p75 receptor, which depending on ligand and co-receptor expression can serve as a low-affinity pan-neurotrophin receptor or a high affinity proneurotrophin receptor, guaranties this neuroendocrine peptide family a central position in the control of skin homeostasis in health and disease. It is a challenging task for future research efforts to integrate our knowledge on differential neurotrophin expression patterns and signaling pathways into complex concepts of neuroendocrine tissue remodeling and pathogenetic processes. In addition, we need to improve our understanding of the role of neurotrophin processing enzymes, associated co-receptors and intracellular adaptor molecules in specific cutaneous cell populations to design precise interaction tools for research and treatment. Such tools will allow us to utilize this ancient growth factor family in the management of neurotrophin responsive pathogenetic pathways and cutaneous diseases such as neurogenic inflammation, peripheral nerve degeneration, wound healing, atopic dermatitis or psoriasis.
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Homeostasis , Factores de Crecimiento Nervioso/fisiología , Enfermedades de la Piel/etiología , Fenómenos Fisiológicos de la Piel , Presentación de Antígeno/fisiología , Muerte Celular , Humanos , Activación de Linfocitos/fisiología , Enfermedades Metabólicas/etiología , Modelos Biológicos , Proteínas del Tejido Nervioso/fisiología , Infiltración Neutrófila/fisiología , Proteínas Oncogénicas/fisiología , Receptores de Factor de Crecimiento Nervioso/fisiología , Transducción de Señal , Cicatrización de Heridas/fisiologíaRESUMEN
Pemphigus vulgaris (PV) is fascinating to dermatologists, epithelial biologists and immunologists alike, as its pathogenesis has been clarified to a much greater extent than that of most other organ-specific autoimmune diseases, and as it has provided abundant novel insights into desmoglein biology and pathology along the way. Historically, the most influential PV pathogenesis concept is that of Stanley and Amagai. This concept holds that autoantibodies against desmogleins are both essential and sufficient for epidermal blister formation (acantholysis) by impeding the normal functioning of these major adhesion proteins. However, as with most good theories, this landmark concept has left a number of intriguing and important questions open (or at least has not managed to answer these to everyone's satisfaction). Moreover, selected dissenting voices in the literature have increasingly called attention to what may or may not be construed as inconsistencies in this dominant PV pathogenesis paradigm of the recent past. The present debate feature therefore bravely rises to the challenge of re-examining the entire currently available evidence, as rationally and as undogmatically as possible, by provocatively asking a carefully selected congregation of experts (who have never before jointly published on this controversial topic!) to discuss how essential anti-desmoglein autoantibodies really are in the immunopathogenesis of PV. Not surprisingly, some of our expert "witnesses" in this animated debate propose diametrically opposed answers to this question. While doing so, incisive additional questions are raised that relate to the central one posed, and our attention is called to facts that may deserve more careful consideration than they have received so far. Together with the intriguing (often still very speculative) complementary or alternative pathogenesis scenarios proposed in the following pages, this offers welcome "food for thought" as well as very specific suggestions for important future research directions--within and beyond the camp of PV aficionados. The editors trust that this attempt at a rational public debate of the full evidence that is currently at hand will constructively contribute to further dissecting the exciting--and clinically very relevant!--immunopathogenesis of PV in all its complexity.
Asunto(s)
Autoanticuerpos/inmunología , Desmogleína 1/inmunología , Desmogleína 3/inmunología , Pénfigo/inmunología , Animales , Autoanticuerpos/fisiología , Desmogleína 1/fisiología , Desmogleína 3/fisiología , Desmosomas/fisiología , Modelos Animales de Enfermedad , Humanos , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Queratinocitos/inmunología , Queratinocitos/patología , Ratones , Pénfigo/patología , Pénfigo/fisiopatología , Índice de Severidad de la EnfermedadRESUMEN
Melanocytes and cells of the nervous system are of common ectodermal origin and neurotrophins (NT) have been shown to be released by human keratinocytes. We investigated the expression and function of NT [nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), NT-3, NT-4/-5] and their receptors in human melanocytes. Human melanocytes produce all NT in different amounts, whereas they only release NT-4. NT-4 release is downregulated, whereas NT-3 is upregulated by ultraviolet (UVB) irradiation. Melanocytes treated with phorbol 12-myristate 13-acetate (PMA) express TrkA and TrkB, but not TrkC. NT fail to stimulate melanocyte proliferation, whereas they stimulate the synthesis of tyrosinase and tyrosinase-related protein-1 (TRP-1). Finally, NT-3, NT-4 and NGF increase melanin production. Taken together, these results demonstrate an intriguing interaction between melanocytes and the nervous system. We speculate that NT could be considered the target of therapy for disorders of skin pigmentation.
RESUMEN
Whereas nerve growth factor has been extensively studied in human keratinocytes, little is known on the role of other members of the neurotrophin family. We investigated the expression and function of neurotrophins and neurotrophin receptors in cultured human keratinocytes. We demonstrated by reverse transcription-polymerase chain reaction that keratinocytes synthesize neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5. These cells also express tyrosinase kinase A and C, the nerve growth factor and neuro-trophin-3 high-affinity receptors, respectively. On the other hand, only the truncated extracellular isoform of tyrosinase kinase B, the high-affinity brain-derived neurotrophic factor and neurotrophin-4/5 receptor, is detected in keratinocytes. Moreover, neurotrophin-3, brain-derived neurotrophic factor, and neurotrophin-4/5 proteins are secreted by human keratinocytes at low levels. Keratinocyte stem cells synthesize the highest amounts of nerve growth factor, while they secrete higher levels of nerve growth factor as compared with transit amplifying cells. Neurotrophin-3 stimulates keratinocyte proliferation, where brain-derived neurotrophic factor or neurotrophin-4/5 does not exert any effect on keratinocyte proliferation. Addition of neurotrophin-3 slightly upregulates the secretion of nerve growth factor, whereas nerve growth factor strongly augments neurotrophin-3 release. Ultraviolet B irradiation downregulates nerve growth factor, whereas it augments neurotrophin-3 and neurotrophin-4/5 protein levels. Ultraviolet A irradiation increases the level of neurotrophin-3, whereas it does not exert any effect on the other neurotrophins. Finally, neurotrophins other than nerve growth factor fail to protect human keratinocytes from ultraviolet B-induced apoptosis. This work delineates a functional neurotrophin network, which may contribute to epidermal homeostasis.
Asunto(s)
Queratinocitos/fisiología , Factores de Crecimiento Nervioso/genética , Receptores de Factor de Crecimiento Nervioso/genética , Apoptosis/fisiología , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , División Celular/fisiología , Células Cultivadas , Expresión Génica/fisiología , Expresión Génica/efectos de la radiación , Humanos , Queratinocitos/citología , Queratinocitos/metabolismo , Factores de Crecimiento Nervioso/metabolismo , Neurotrofina 3/genética , Neurotrofina 3/metabolismo , ARN Mensajero/análisis , Receptor trkB/genética , Receptor trkB/metabolismo , Receptor trkC/genética , Receptor trkC/metabolismo , Receptores de Factor de Crecimiento Nervioso/metabolismo , Rayos UltravioletaRESUMEN
The skin is the most densely innervated organ in the body and there is a close relationship between the skin and the nervous system. Most skin cells express receptors for neuromediators (NM) and skin cells themselves are an important source of NM. In particular, human keratinocytes synthesize neurotrophins and endorphins and express their receptors. In addition to neurotrophic activity, NM are involved in skin homeostasis, trophism and stress responses. NM released from keratinocytes also function in a paracrine fashion on other skin cells, such as Langerhans cells, melanocytes and fibroblasts. We discuss the influence of NM on these cells, which may be involved in major cosmetic problems like ageing, baldness and dyspigmentation. Based on this correlation, it seems reasonable to target neural factors for cosmetic purposes.
RESUMEN
Carboxyfullerene, a water-soluble carboxylic acid derivative of a fullerene, which acts as a free-radical scavenger, was investigated as a protective agent against ultraviolet-light-induced damage in human keratinocytes. First, we demonstrate that carboxyfullerene is not cytotoxic for these cells. In addition, this compound significantly reduces the ultraviolet-B-induced inhibition of keratinocyte proliferation and protects keratinocytes from apoptosis caused by ultraviolet B irradiation in a time- and dose-dependent fashion. Furthermore, the percentage of cells with depolarized mitochondria is significantly lower in ultraviolet-B-irradiated keratinocytes pretreated with carboxyfullerene than in cells provided with diluent alone. Carboxyfullerene also protects human keratinocytes from apoptosis induced by exposure to deoxy-D-ribose, a sugar that causes cell death through a pathway involving oxidative stress. On the other hand, ultraviolet B downregulates bcl-2 levels in human keratinocytes, and carboxyfullerene fails to prevent this effect. These results suggest that carboxy- fullerene protects human keratinocytes from ultraviolet B damage possibly via a mechanism interfering with the generation of reactive oxygen species from depolarized mitochondria without the involvement of bcl-2.
Asunto(s)
Carbono/farmacología , Ácidos Carboxílicos/farmacología , Fulerenos , Queratinocitos/citología , Protectores contra Radiación/farmacología , Rayos Ultravioleta , Apoptosis/efectos de los fármacos , Apoptosis/efectos de la radiación , Desoxirribosa/farmacología , Citometría de Flujo , Humanos , Membranas Intracelulares/fisiología , Potenciales de la Membrana , Mitocondrias , Proteínas Proto-Oncogénicas c-bcl-2/metabolismoRESUMEN
C60 carboxyfullerene is a novel buckminsterfullerene-derived compound that behaves as a free-radical scavenger. In the present report, we investigated whether this drug exerts a protective activity against oxidative stress-induced apoptosis. Human peripheral blood mononuclear cells (PBMCs) were challenged by 2-deoxy-d-ribose (dRib) or TNF-alpha plus cycloheximide as agents that trigger apoptosis by interfering with the redox status of cell and mitochondrial membrane potential. We found that carboxyfullerene was able to protect quiescent PBMCs from apoptosis caused either by 2-deoxy-d-ribose or TNF-alpha plus cycloheximide by a mechanism partially involving the mitochondrial membrane potential integrity, known to be associated with early stages of apoptosis. These results represent the first indication for a target activity of buckminsterfullerenes on cells of the immune system and their mitochondria.
Asunto(s)
Apoptosis , Ácidos Carboxílicos/farmacología , Leucocitos Mononucleares/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Sustancias Protectoras/farmacología , Adulto , Fulerenos , Humanos , Técnicas In Vitro , Leucocitos Mononucleares/citologíaRESUMEN
Biologically active nerve growth factor (NGF) is synthesised and released by proliferating normal human keratinocytes. NGF up-regulates the expression of NGF mRNA in keratinocytes. Keratinocytes express both the low (p75)- and the high-affinity (TrkA) NGF-receptors, which are located in the basal layer of the epidermis. K252, a specific inhibitor of trk phosphorylation, blocks NGF-induced keratinocyte proliferation, in absence of exogenous NGF. Normal keratinocytes over-expressing TrkA proliferate better than control transfectants, while the NGF mimicking anti-Trk antibody induces an increased keratinocyte proliferation in Trk over-expressing cells as compared to mock transfected keratinocytes. In addition, NGF over-expressing keratinocytes proliferate better than mock transfected cells. K252, by blocking TrkA phosphorylation, induces apoptosis in normal keratinocytes, but not in keratinocytes over-expressing bcl-2. Furthermore, NGF transfected keratinocytes are protected from UV-B-induced keratinocyte apoptosis, by maintaining constant levels of Bcl-2 and Bcl-xL . Taken together these results support the concept of an autocrine survival system sustained by NGF and its high-affinity receptor in human keratinocytes. Because NGF and Trk levels are highly expressed in psoriasis. one could speculate that NGF autocrine system plays a role in the mechanisms associated with this and other hyperproliferative skin conditions, including cancer.
Asunto(s)
Queratinocitos/fisiología , Factor de Crecimiento Nervioso/fisiología , Apoptosis/fisiología , Comunicación Autocrina/fisiología , Humanos , Queratinocitos/patologíaRESUMEN
Nerve growth factor (NGF) is synthesized and released by human keratinocytes. NGF acts as a neurotrophic molecule at the skin level, as it stimulates the sprouting of nerve fibers and regulates the synthesis and expression of neuropeptides. NGF can thus take part in neurogenic inflammation which in turn is involved in the pathogenesis of several inflammatory dermatoses. Human keratinocytes also synthesize and express the low (p75)-and the high-affinity (trk) NGF-receptor (NGF-R). NGF stimulates keratinocyte proliferation which is blocked by the natural alcaloid K252, a specific inhibitor of trk phosphorylation. K252 inhibits keratinocyte proliferation and induces keratinocyte apoptosis, in the absence of exogenous NGF, indicating the existence of an autocrine loop where NGF and trk act as key players. Finally, NGF protein levels are increased in psoriatic as compared to non-lesional and normal skin, and psoriatic keratinocytes express higher amounts of NGF than normal keratinocytes. This review will discuss the above findings in view of a possible involvement of NGF in the pathomechanisms associated with the development of the psoriatic lesion.
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Queratinocitos/fisiología , Factores de Crecimiento Nervioso/fisiología , Psoriasis/etiología , Apoptosis , División Celular , Humanos , Fibras Nerviosas/fisiología , Neuropéptidos/fisiología , Psoriasis/fisiopatología , Receptores de Factor de Crecimiento Nervioso/fisiología , Piel/inervaciónRESUMEN
Ultraviolet radiation is a potent inducer of apoptosis, whereas autocrine nerve growth factor protects human keratinocytes from programmed cell death. To evaluate the role of nerve growth factor in the mechanisms of ultraviolet B-induced apoptosis, cultured human keratinocytes were ultraviolet B irradiated following pretreatment with K252, a specific inhibitor of the tyrosine kinase high-affinity nerve growth factor receptor. Here we report that the addition of K252 significantly enhanced keratinocyte apoptosis. We then transfected normal human keratinocytes with pNUT-hNGF. Nerve growth factor overexpressing keratinocytes secreted the highest amounts of nerve growth factor in culture supernatants, were more viable, and had a higher rate of proliferation than mock-transfected cells. Whereas ultraviolet B radiation downregulated nerve growth factor mRNA and protein as well as the tyrosine kinase high-affinity nerve growth factor receptor in normal keratinocytes, it failed to do so in nerve growth factor-transfected cells. Moreover, nerve growth factor overexpressing keratinocytes were partially resistant to apoptosis induced by increasing doses of ultraviolet B at 24 and 48 h. These results indicate that downregulation of nerve growth factor function plays an important part in the mechanisms of ultraviolet B-induced apoptosis in human keratinocytes. In addition, ultraviolet B caused a decrease in BCL-2 and BCL-xL expression in mock-transfected keratinocytes, but not in nerve growth factor overexpressing cells. Finally, nerve growth factor prevented the cleavage of the enzyme poly(ADP-ribose) polymerase induced in human keratinocytes by ultraviolet B. These results are consistent with a model whereby the autocrine nerve growth factor protects human keratinocytes from ultraviolet B-induced apoptosis by maintaining constant levels of BCL-2 and BCL-xL, which in turn might block caspase activation.
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Apoptosis/efectos de la radiación , Queratinocitos/efectos de la radiación , Factor de Crecimiento Nervioso/fisiología , Rayos Ultravioleta , División Celular/efectos de la radiación , Humanos , Factor de Crecimiento Nervioso/análisis , Proteínas Proto-Oncogénicas c-bcl-2/análisis , Receptor trkA/análisis , Transfección , Proteína bcl-XRESUMEN
Apoptosis plays a fundamental part in epidermal homeostasis, and apoptotic cells have been detected in normal and diseased skin. Little is known, however, on the inhibitory mechanisms of apoptosis at the skin level. In addition to bcl-2, a novel inhibitor of apoptosis designated survivin and structurally analogous to IAP apoptosis inhibitors has been recently identified. The expression of survivin in normal and pathologic skin was investigated. Immunohistochemical studies revealed that survivin is expressed in basal keratinocytes, but not in suprabasal epidermal layers, with a pattern similar to bcl-2. In western blots, the anti-survivin antibody recognized a single band of 16.5 kDa in protein extracts from normal human keratinocytes in culture, in agreement with the predicted size of survivin. In addition, survivin immunoreactivity was detected in benign and malignant melanocytic lesions, with strong expression in invasive lesions of melanomas. Whereas survivin staining was undetectable in benign epithelial tumors, such as seborrheic keratoses, it was observed in all epidermal layers in Bowen's disease. Interestingly, at variance with bcl-2, survivin was markedly expressed in squamous cell carcinoma, but virtually lacking in basal cell carcinoma, suggesting that these two apoptosis inhibitors may act through different anti-apoptotic pathways. Deregulation of survivin may influence both epidermal homeostasis and the development of melanoma and nonmelanoma skin cancer.
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Apoptosis/efectos de los fármacos , Proteínas Asociadas a Microtúbulos , Proteínas/análisis , Neoplasias Cutáneas/química , Piel/química , Adulto , Humanos , Immunoblotting , Inmunohistoquímica , Proteínas Inhibidoras de la Apoptosis , Proteínas de Neoplasias , SurvivinRESUMEN
Anoikia is a type of apoptotic cell death that occurs in cells that are substrate-restricted in their growth. Buckminsterfullerenes represent a new class of chemical compounds with wide potential pharmacological antioxidant activity. In this report we provide the first demonstration that a water-soluble fullerene derivative, C3-fullero-tris-methanodicarboxylic acid, synthesized in our laboratories, is capable of inducing anoikia resistance in epithelial cells by a mechanism involving a 'trophic' effect on cell spreading-associated cytoskeletal components, i.e. on actin microfilaments.
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Antioxidantes/farmacología , Apoptosis/efectos de los fármacos , Carbono/farmacología , Ácidos Dicarboxílicos/farmacología , Células Epiteliales/patología , Fulerenos , Apoptosis/efectos de la radiación , Carbono/química , Adhesión Celular/efectos de los fármacos , Línea Celular , Células Epiteliales/efectos de los fármacos , Células Epiteliales/efectos de la radiación , Humanos , Microscopía Electrónica de RastreoRESUMEN
A 37-year-old patient with systemic lupus erythematosus, who had been treated with oral corticosteroids for 10 years, developed primary cutaneous nocardiosis. Brown-violaceous, suppurative nodules and plaques arose on her right leg. Cultures of multiple biopsies on blood agar medium grew Nocardia. The patient received 500 mg of imipenem three times a day which resulted in complete regression of the lesions within two months. No relapse was observed 6 months later.