RESUMEN
Psoriasis is a chronic systemic inflammatory cutaneous disease. Where the immune system plays an important role in its pathogenesis, with key inflammatory intercellular signalling peptides and proteins including IL-17 and IL-23. The psychoneurological system also figures prominently in development of psoriasis. There is a high prevalence of comorbidity between psoriasis and mental health disorders such as depression, anxiety and mania. Patients with psoriasis often suffer from pathological pain in the lesions, and their neurological accidents could improve the lesions in innervated areas. The immune system and the psychoneurological system interact closely in the pathogenesis of psoriasis. Patients with psoriasis exhibit abnormal levels of neuropeptides both in circulating and localized lesion, acting as immunomodulators involved in the inflammatory response. Moreover, receptors for inflammatory factors are expressed in both peripheral and central nervous systems (CNSs), suggesting that nervous system can receive and be influenced by signals from immune system. Key inflammatory intercellular signalling peptides and proteins in psoriasis, such as IL-17 and IL-23, can be involved in sensory signalling and may affect synaptic plasticity and the blood-brain barrier of CNS through the circulation. This review provides an overview of the multiple effects on the peripheral and CNS under conditions of systemic inflammation in psoriasis, providing a framework and inspiration for in-depth studies of neuroimmunomodulation in psoriasis.
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Sistema Nervioso Central , Interleucina-17 , Interleucina-23 , Psoriasis , Psoriasis/metabolismo , Psoriasis/inmunología , Humanos , Sistema Nervioso Central/metabolismo , Interleucina-23/metabolismo , Interleucina-17/metabolismo , Neuroinmunomodulación , Neuropéptidos/metabolismo , Inflamación/metabolismo , Sistema Nervioso Periférico/metabolismo , Animales , Transducción de SeñalAsunto(s)
Queratinocitos , Xantomatosis , Humanos , Xantomatosis/patología , Queratinocitos/patología , Masculino , Femenino , Metabolismo de los LípidosRESUMEN
BACKGROUND: Lupus erythematosus (LE) is a spectrum of autoimmune diseases. Due to the complexity of cutaneous LE (CLE), clinical skin image-based artificial intelligence is still experiencing difficulties in distinguishing subtypes of LE. OBJECTIVES: We aim to develop a multimodal deep learning system (MMDLS) for human-AI collaboration in diagnosis of LE subtypes. METHODS: This is a multi-centre study based on 25 institutions across China to assist in diagnosis of LE subtypes, other eight similar skin diseases and healthy subjects. In total, 446 cases with 800 clinical skin images, 3786 multicolor-immunohistochemistry (multi-IHC) images and clinical data were collected, and EfficientNet-B3 and ResNet-18 were utilized in this study. RESULTS: In the multi-classification task, the overall performance of MMDLS on 13 skin conditions is much higher than single or dual modals (Sen = 0.8288, Spe = 0.9852, Pre = 0.8518, AUC = 0.9844). Further, the MMDLS-based diagnostic-support help improves the accuracy of dermatologists from 66.88% ± 6.94% to 81.25% ± 4.23% (p = 0.0004). CONCLUSIONS: These results highlight the benefit of human-MMDLS collaborated framework in telemedicine by assisting dermatologists and rheumatologists in the differential diagnosis of LE subtypes and similar skin diseases.
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A 76-year-old male developed a maculopapular rash on his trunk and extremities. The rash appeared 2 months after Finasteride administration for his prostatic hyperplasia. Clinical suspicion was of drug exanthema due to Finasteride. The clinical and histologic data were compatible with pharmacologic eruption by Finasteride.
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An 81-year-old woman presented with purpura, petechiae, ecchymoses, flesh or brown-colored waxy, smooth, papules, warty plaque, nail dystrophy and palmodigital erythematous swelling for more than 6 years. She was diagnosed as multiple myeloma-associated systemic amyloidosis after skin subcutaneous histopathological examinations and relevant examinations such as blood and bone marrow. Systemic amyloidosis is closely related with multiple myeloma (MM). Multiple and pleomorphic skin lesions are not usual among patients with multiple myeloma or systemic amyloidosis.
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Neoplasias Cutáneas , Células Dendríticas , Humanos , Piel , Neoplasias Cutáneas/diagnósticoRESUMEN
We present an unusual case of unilateral and localized subcorneal pustular dermatosis, which has not been described previously.
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Enfermedades Cutáneas Vesiculoampollosas , Humanos , Enfermedades Cutáneas Vesiculoampollosas/diagnósticoRESUMEN
AIMS: Clear cells formed due to depositions of glycogen or lipids in the cytoplasm commonly occur in various tissues. Adipophilin (ADP), a lipid regulatory protein, is closely related to lipid droplets. This study aims to examine adipophilin expression in clear cells of various skin lesions. METHODS: ADP expression was examined using immunohistochemistry in 108 sections from 15 skin lesion types with clear cell histology, namely, sebaceoma (n=16), sebaceous adenoma (n=3), sebaceous carcinoma (n=12), xanthomata cutis (n=10), xanthogranuloma (n=8), Paget's disease (n=10), Bowen disease (n=10), hidradenoma (n=9), atypical lipoma (n=5), superficial lipomatous nevus (n=5), metastatic renal cell carcinoma (n=5), squamous cell carcinoma (n=4), seborrheic keratosis (n=4), dermatofibroma (n=4) and clear cell sarcoma (n=3). RESULTS: ADP was not expressed in Bowen disease, hidradenoma or seborrheic keratosis. Four expression patterns, foamy, reticular, granular and punctate, were summarised based on their expression in clear cells. Different expression patterns were related to tissue origin and differentiation degree. Foamy expression was commonly observed in lesions with mature sebaceous glands and xanthomas; reticular expression in adipocytes; granular expression in xanthoma, xanthogranuloma and metastatic renal carcinoma and punctate expression in sebaceoma, sebaceous carcinoma, Paget's disease, squamous cell carcinoma and clear cell sarcoma. Furthermore, stronger staining with focal vesicular labelling was noted in sebaceoma than in sebaceous carcinoma. Characteristic labelling was noted, including the circular distribution in Touton giant cells of xanthogranulomas and focal distribution in the clear cells along the edge of necrotic tissue in clear cell sarcoma. CONCLUSIONS: ADP is useful in identifying intracytoplasmic lipids and can be used to diagnose skin lesions with clear cell histology, especially in some lesions with characteristic labelling.
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Acrospiroma , Adenocarcinoma Sebáceo , Enfermedad de Bowen , Carcinoma de Células Renales , Carcinoma de Células Escamosas , Queratosis Seborreica , Neoplasias Renales , Sarcoma de Células Claras , Neoplasias de las Glándulas Sebáceas , Neoplasias Cutáneas , Neoplasias de las Glándulas Sudoríparas , Adenocarcinoma Sebáceo/diagnóstico , Adenocarcinoma Sebáceo/metabolismo , Adenocarcinoma Sebáceo/patología , Carcinoma de Células Escamosas/metabolismo , Humanos , Inmunohistoquímica , Lípidos , Perilipina-2 , Neoplasias de las Glándulas Sebáceas/patología , Neoplasias Cutáneas/patología , Neoplasias de las Glándulas Sudoríparas/diagnósticoRESUMEN
BACKGROUND: Signal transducer and activator of transcription 3 (STAT3) was strongly expressed and activated in psoriatic keratinocytes (KCs) and correlated with the severity of psoriasis. The study aimed to investigate the effects of STAT3 small interfering RNA (siRNA) combined with ultrasonic irradiation and SonoVue microbubbles on the proliferation and apoptosis in KCs of psoriatic lesions and the relative mechanisms. METHODS: Psoriatic KCs were transfected under four experimental conditions: (1) STAT3 siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group); (2) STAT3 siRNA only carried by Lipofectamine 3000 (L group); (3) the negative control of siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (siRNA-NC); (4) not treated as Blank. Cell Counting Kit-8 assay was used to evaluate the cell proliferation. Cell cycle analysis was detected with cycle test Plus DNA reagent kit associated with flow cytometer. FITC Annexin V apoptosis detection kit associated with flow cytometer was applied for apoptosis analysis. Fluo calcium indicator associated with flow cytometer was used to analyze intracellular free calcium concentration ([Ca2+]i). The expressions of cyclin D1 and Bcl-xL were detected both at the mRNA level by real-time reverse transcription-polymerase chain reaction (RT-PCR) and at the protein level by Western blotting. The obtained data were statistically evaluated by two-way analysis of variance. RESULTS: STAT3 siRNA inhibited the growth of KCs in a time-dependent manner showing the highest proliferation inhibition in LUS group with proliferation ratio of 45.38% ± 5.85% at 72h (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced an altered cell cycle distribution of KCs showing the highest increases in G2/M-phase population up to 18.06% ± 0.36% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced late apoptosis of KCs with the highest late apoptosis percentage of 22.87% ± 1.28% in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the elevation of [Ca2+]iof KCs with the highest calcium fluorescence intensity mean of 1213.67 ± 60.51 in LUS group (P < 0.05 vs. L group, siRNA-NC, or Blank). STAT3 siRNA induced the downregulation of cyclin D1 and Bcl-xL expressions of KCs at mRNA and protein levels with the lowest expressions in LUS group with cyclin D1 expression of 51.81% ± 9.58% and 70.17% ± 4.22% at mRNA level and at protein level, respectively, and with Bcl-xL expression of 37.58% ± 4.92% and 64.06% ± 7.78% at mRNA level and at protein level, respectively (P < 0.05 vs. L group, siRNA-NC, or Blank). CONCLUSIONS: STAT3 siRNA inhibited the growth and induced the apoptosis in psoriatic KCs likely partly through altering cell cycle distribution, elevating [Ca2+]i, and downregulating cyclin D1 and Bcl-xL expressions. Silencing the target gene STAT3 in psoriatic KCs with siRNA combined with ultrasonic irradiation and microbubbles would contribute to a significant innovation as a new clinical therapy for psoriasis.
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Queratinocitos , Microburbujas , Fosfolípidos , Psoriasis/terapia , Interferencia de ARN , Factor de Transcripción STAT3/metabolismo , Hexafluoruro de Azufre , Apoptosis , Línea Celular Tumoral , Proliferación Celular , Humanos , ARN Interferente Pequeño , UltrasonidoRESUMEN
Objective To investigate the expressions of the inhibitor of apoptosis protein survivin and signal transducer and activator of transcription 2 (STAT2) in the tissues of the plaque-like lesions of patients with psoriasis vulgaris (PV) in the progressive stage and discuss their correlation. Methods We collected the plaque-like lesion samples and non-lesion samples from 22 PV patients and the normal skin sample from 18 healthy controls. Real-time quantitative PCR was used to evaluate the mRNA levels of survivin and STAT2 in these samples. Western blot analysis was performed to determine the protein expressions of survivin and STAT2. Immunohistochemical staining was also used to detect the expressions of survivin and STAT2. The correlation between survivin and STAT2 in the PV lesions was determined by Pearson's correlation analysis. Results Compared with healthy control skin and PV non-lesion tissues, the mRNA and protein expressions of survivin and STAT2 were significantly elevated in PV lesion tissues, and the mRNA expression of survivin was positively correlated with STAT2 mRNA in PV lesion tissues (r=0.5282). Conclusion The expressions of survivin and STAT2 are up-regulated in skin lesions of PV patients, and their mRNA expressions are positively correlated.
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Proteínas Inhibidoras de la Apoptosis/genética , Psoriasis/metabolismo , Factor de Transcripción STAT2/genética , Piel/metabolismo , Adulto , Femenino , Regulación de la Expresión Génica , Humanos , Proteínas Inhibidoras de la Apoptosis/análisis , Masculino , Persona de Mediana Edad , ARN Mensajero/análisis , Factor de Transcripción STAT2/análisis , SurvivinRESUMEN
OBJECTIVE: To explore the role of survivin and PI3K/AKT pathway in the pathogenesis of psoriasis vulgaris (PV). METHODS: Plaque-like lesions collected from 22 patients with PV in progressive stage and 18 normal control skin specimens were examined using immunohistochemical staining, Western blotting and real-time quantitative PCR for expressions of survivin, PI3K and AKT in the keratinocytes, and their correlation was analyzed. A small interfering RNA (siRNA) was used to knock down AKT in cultured HaCaT cells, and Western blotting was used to detect the changes in the expression of survivin. RESULTS Compared with normal skin, PV lesions showed obviously up-regulated expressions of survivin, PI3K and AKT in the keratinocytes. Survivin expression was positively correlated with PI3K (r=0.4510, P=0.0351) and AKT (r=0.4423, P=0.0393) in the keratinocytes in PV lesions. In cultured HaCaT cells, siRNA-mediated knockdown of AKT caused down-regulation of survivin expression. CONCLUSION: Survivin and PI3K/AKT signaling pathway may participate in the occurrence and progression of PV.
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Queratinocitos/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Psoriasis/metabolismo , Survivin/metabolismo , Línea Celular , Técnicas de Silenciamiento del Gen , Humanos , ARN Interferente Pequeño , Transducción de SeñalRESUMEN
The most effective sequence of small interfering RNA (siRNA) silencing STAT3 of psoriatic keratinocytes (KCs) was screened out, and the effects of the most effective siRNA combined with ultrasonic irradiation and SonoVue microbubbles on the expression of STAT3 of KCs and the dose- and time-response were investigated. Three chemically-synthetic siRNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs, and the effects on STAT3 expression were detected, then the most effective siRNA was selected for the subsequent experiments. The negative controls of siRNA (siRNA-NC) labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles were transfected into KCs, then the optimal parameters of ultrasonic irradiation were determined. The most effective siRNA carried by Li-pofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and SonoVue microbubbles was transfected into KCs, and the dose- and time-response of RNA interference was determined. The effect of RNA interference by the most effective siRNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group) was compared with that only carried by Li-pofectamine 3000 (L group). The results showed that siRNA-3 achieved the highest silencing efficacy. 0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation. The siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression at mRNA and protein levels in dose- and time-dependent manners determined at 100 nmol/L with maximum downregulation on mRNA at 48 h, and on protein at 72 h after transfection. The LUS group achieved the highest silencing efficacy. It was concluded that siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs, and the optimized transfection condition and the sequence of siRNA-3 could serve for further research on gene therapy of psoriasis.
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Queratinocitos/citología , Psoriasis/metabolismo , ARN Interferente Pequeño/síntesis química , Factor de Transcripción STAT3/genética , Factor de Transcripción STAT3/metabolismo , Células Cultivadas , Relación Dosis-Respuesta a Droga , Regulación hacia Abajo , Portadores de Fármacos/química , Regulación de la Expresión Génica/efectos de los fármacos , Regulación de la Expresión Génica/efectos de la radiación , Humanos , Queratinocitos/efectos de los fármacos , Queratinocitos/metabolismo , Queratinocitos/efectos de la radiación , Lípidos/química , Fosfolípidos/farmacología , Psoriasis/genética , Psoriasis/patología , ARN Interferente Pequeño/química , ARN Interferente Pequeño/farmacología , Hexafluoruro de Azufre/farmacología , Ondas UltrasónicasRESUMEN
The most effective sequence of small interfering RNA (siRNA) silencing STAT3 of psoriatic keratinocytes (KCs) was screened out,and the effects of the most effective siRNA combined with ultrasonic irradiation and SonoVue microbubbles on the expression of STAT3 of KCs and the dose-and time-response were investigated.Three chemically-synthetic siRNAs targeting STAT3 carried by Lipofectamine 3000 were transfected into KCs,and the effects on STAT3 expression were detected,then the most effective siRNA was selected for the subsequent experiments.The negative controls of siRNA (siRNA-NC) labeled with Cy3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles were transfected into KCs,then the optimal parameters of ultrasonic irradiation were determined.The most effective siRNA carried by Lipofectamine 3000 combined with ultrasonic irradiation at the optimal parameters and SonoVue microbubbles was transfected into KCs,and the dose-and time-response of RNA interference was determined.The effect of RNA interference by the most effective siRNA at the optimal time and dose carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles (LUS group) was compared with that only carried by Lipofectamine 3000 (L group).The results showed that siRNA-3 achieved the highest silencing efficacy.0.5 W/cm2 and 30 s were selected as the parameters of ultrasonic irradiation.The siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue mierobubbles could effectively knock down the STAT3 expression at mRNA and protein levels in dose-and time-dependent manners determined at 100 nmol/L with maximum downregulation on mRNA at 48 h,and on protein at 72 h after transfection.The LUS group achieved the highest silencing efficacy.It was concluded that siRNA-3 carried by Lipofectamine 3000 combined with ultrasonic irradiation and SonoVue microbubbles could effectively knock down the STAT3 expression in psoriatic KCs,and the optimized transfection condition and the sequence of siRNA-3 could serve for further research on gene therapy of psoriasis.
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Objective To observe the clinical efficacy of Guishen Zhiyang Recipe (GZR) in trea- ting senile pruritus patients with blood deficiency and hyperactivity of Gan-yang syndrome (BDHGYS) and to study the mechanism in nervous-endocrine-immune systems. Methods Ninety senile pruritus pa- tients were assigned to the treatment group and the control group by complete randomized lot, 45 in each group. Totally 41 patients in the treatment group and 38 patients in the control group completed the trial. Patients in the treatment group took GZR, while those in the control group took Fuyang Granule (FG). Ex- ternal application of Binghuang Fule Soft Ointment was performed to all patients. The therapeutic course for all was 8 weeks. Symptoms and efficacy changes in skin lesion were observed in the two groups. Lev- els of stem cell factor (SCF) , dynorphin (DYN) , testosterone (T) , estradiol (E2) , and IL-4 were detec- ted in the two groups using double antibody sandwich ELISA. Results Compared with before treatment, pruritus degree, scratching area, scaling, lichenoid lesion, irritability and restlessness, dysphoria, dry pharynx, dizziness, and tinnitus all decreased in the two groups after 8 weeks of treatment (P <0. 05). Scores of Chinese medical syndromes all decreased after 4 and 8 weeks of treatment (P <0. 05). Levels of SCF and DYN obviously decreased in the two groups after 4 and 8 weeks of treatment (P <0. 05,P < 0. 01). Compared with the control group, obvious improvement was seen in pruritus degree, scratching number, scaling, irritability and restlessness , dysphoria, dizziness , and tinnitus(P <0. 05) ; total scores of Chinese medical syndromes decreased (P <0. 05) ; SCF also decreased (P <0. 05) in the treatment group after 8 weeks of treatment. Conclusions Based on external application of Binghuang Fule Soft Ointment, GZR showed better efficacy than that of the control. It had certain roles in regulating related mediator levels that might affect nervous-endocrine-immune systems.
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Medicamentos Herbarios Chinos , Fitoterapia , Prurito , Medicamentos Herbarios Chinos/uso terapéutico , Estradiol , Humanos , Prurito/tratamiento farmacológico , SíndromeAsunto(s)
Poroma/patología , Neoplasias de las Glándulas Sudoríparas/patología , Acantoma/metabolismo , Acantoma/patología , Acantoma/cirugía , Adenoma/metabolismo , Adenoma/patología , Adulto , Anciano , Diagnóstico Diferencial , Femenino , Humanos , Queratina-14/metabolismo , Queratina-5/metabolismo , Queratina-6/metabolismo , Queratosis/metabolismo , Queratosis/patología , Queratosis/cirugía , Masculino , Poroma/clasificación , Poroma/metabolismo , Poroma/cirugía , Neoplasias de las Glándulas Sudoríparas/clasificación , Neoplasias de las Glándulas Sudoríparas/metabolismo , Neoplasias de las Glándulas Sudoríparas/cirugíaRESUMEN
To investigate the effects of ATRA, acitretin and tazarotene on the growth and apoptosis of human tongue squamous cell carcinoma cell line Tca8113. The effect of retinoids on growth of Tca8113 cells in vitro was examined by MTT assay and Trypan blue exclusion assay. Cell cycle analysis, early apoptosis analysis with double staining with Annexin V-FITC and PI, and active caspase-3 analysis with the staining of FITC-conjugated monoclonal rabbit anti-active caspase-3 antibody were made by flow cytometer. Streptavidin-biotin complex (SABC) immunocytochemical assays were employed for the detections of Bax/Bcl-2 proteins expressions. Our results showed that the retinoids inhibited growth of Tca8113 cells in a dose- and time-dependent manner with maximal inhibition 24 h after treatment of 10(-5) mol/L. 10(-5) mol/L retinoids altered cell cycle distribution of Tca8113 cells, revealing an increase in G0/G1-phase population, a decrease in S-phase population and the inhibition of G1/S switching. 10(-5) mol/L retinoids significantly induced apoptosis of Tca8113 cells (all P < 0.05), elevated the cells population with detectable active caspase-3 (P < 0.05 for all), increased the number of cells forming Bax and decreased the number of cells forming Bcl-2 significantly (all P < 0.05). Acitretin played a most prominent role among the retinoids. It is concluded that the inhibition of cell cycle progress of Tca8113 cells by ATRA, acitretin and tazarotene is one of the possible mechanisms for proliferation arrest of Tca8113 cells elicited by the retinoids. The retinoids mediate apoptosis in Tca8113 cells that may be caspase-dependent through mitochondria pathway. High concentration retinoids inhibit growth of Tca8113 cells in vitro by interfering with proliferation and inducing apoptosis of cells. Acitretin may be an alternative medicine for the prevention and treatment of tongue squamous cell carcinoma.
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Acitretina/farmacología , Apoptosis/efectos de los fármacos , Carcinoma de Células Escamosas/patología , Ácidos Nicotínicos/farmacología , Neoplasias de la Lengua/patología , Tretinoina/farmacología , Antineoplásicos/farmacología , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , HumanosRESUMEN
OBJECTIVE: To study the effect of deoxycholate in inducing apoptosis of human normal esophageal mucosal epithelial cells in vitro and investigate the molecular mechanism. METHODS: Cultured normal human esophageal mucosal epithelial cells were treated with deoxycholate, and the cell apoptosis were evaluated with TUNEL, DNA ladder, flow cytometry with PI-staining, Annexin V-FITC conjugated with PI staining, and Western blotting. RESULTS: Flow cytometry, TUNEL and DNA ladder demonstrated that deoxycholate could induce apoptosis in normal human esophageal mucosal epithelial cells in a dose- and time-dependent manner. A percentage of 21.3% of the cell population treated with deoxycholate at 500 micromol/L for 30 min exhibited detectable caspase-3 activity shown by flow cytometry, which was significantly higher than the control level (1.5%, P<0.01). Western blotting suggested that deoxycholate down-regulated Bcl-2 protein expression and up-regulated Bax expression, but Fas was negative in the cells before and after deoxycholate treatment. CONCLUSIONS: Deoxycholate could induce apoptosis in cultured human esophageal mucosal epithelial cells. Aaspase-3 activation, Bcl-2 protein down-regulation and Bax up-regulation are involved in deoxycholate-induced apoptosis, which does not involve Fas-L/Fas.
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Apoptosis/efectos de los fármacos , Ácido Desoxicólico/farmacología , Células Epiteliales/citología , Esófago/citología , Caspasa 3/metabolismo , Células Cultivadas , Humanos , Proteínas Proto-Oncogénicas c-bcl-2/biosíntesis , Proteínas Proto-Oncogénicas c-bcl-2/genéticaRESUMEN
OBJECTIVE: To investigate the effects of histamine on the proliferation, apoptosis and differentiation of human keratinocytes (HKC) and the mechanisms. METHODS: The effect of histamine on the growth of HKC in vitro was examined by MTT assay and trypan blue exclusion assay. Cell cycle analysis and early apoptosis analysis by double staining with Annexin V-FITC and PI were carried out by flow cytometry. DNA ladder assay was performed for the detection of cell apoptosis. HKC free calcium concentration ([Ca(2+)](i)) was measured by laser scanning confocal microscopy in combination with calcium fluorescence probe Fluo-3/AM. HKC differentiation markers keratin 10 (K10) and involucrin was detected by streptavidinbiotin complex immunocytochemical assay. RESULTS: Histamine at high concentration inhibited the proliferation of HKC with cell viability ratio of 65.6% at 1 x 10(-4) mol/L, while histamine at low concentrations promoted proliferation of HKC with the cell viability ratio of 130.7% at 1 x 10(-8) mol/L. Histamine at 1 x 10(-4) mol/L altered cell cycle distribution of HKC with an increase in G0/G1-phase cell population to 30.97%, a decrease in S-phase population to 73.81% and inhibition of G1/S switching. Histamine at 1 x 10(-4) mol/L induced obvious apoptosis of HKC with early apoptosis ratio of 18.64% as compared with the control (5.60%, P<0.05). Histamine 1 x 10(-4) mol/L induced an increase of HKC [Ca(2+)](i) up to 58.9% and cimetidine (an H(2) receptor antagonist) decreased HKC [Ca(2+)](i) down to 25.4%. Histamine at this concentration down-regulated the expressions of K10 and involucrin of HKC but these changes were not significantly different from those of the control (P>0.05). CONCLUSIONS: Histamine at high concentrations inhibits cell cycle progress of HKC, mediates cell apoptosis and induces the increase of [Ca(2+)](i), which might be a partial explanation for growth arrest of HKC elicited by histamine. Histamine may regulate epidermal tissue turnover under physiological conditions, whereas under pathological circumstances of the skin as in trauma and inflammation, histamine at high concentrations may inhibit the regeneration of epidermis and the differentiation of HKC.