RESUMO
Candida albicans resides on epithelial surfaces as part of the physiological microflora. However, under certain conditions, it may cause life-threatening infections, including Candida sepsis. We have recently shown that human ß-defensins (hBDs) hBD-2 and hBD-3 are upregulated in Candida esophagitis and that this antifungal host response is distinctly regulated by NF-κB and MAPK/activator protein-1 (AP-1) pathways. Here, we show that C. albicans induces hBD-2 through an autocrine IL-1ß loop and that activation of the epidermal growth factor receptor (EGFR) by endogenous transforming growth factor-α (TGF-α) is a crucial event in the induction of hBD-3. To further dissect upstream signaling events, we investigated expression of the central sheddases for EGFR ligands ADAM10 and ADAM17 in the healthy and infected esophagus. Next, we used pharmaceutical inhibitors and small-interfering RNA-mediated knock down of ADAM10 and ADAM17 to reveal that ADAM17-induced shedding of TGF-α is a crucial step in the induction of hBD-3 expression in response to Candida infection. In conclusion, we describe for the first time an autocrine IL-1ß loop responsible for the induction of hBD-2 expression and an ADAM17-TGF-α-EGFR-MAPK/AP-1 pathway leading to hBD-3 upregulation in the course of a Candida infection of the esophagus.
Assuntos
Proteínas ADAM/metabolismo , Candidíase/metabolismo , Esofagite/metabolismo , Esôfago/metabolismo , Interleucina-1beta/metabolismo , beta-Defensinas/metabolismo , Proteína ADAM17 , Candida/genética , Candida/metabolismo , Candidíase/genética , Candidíase/microbiologia , Células Cultivadas , Ensaio de Desvio de Mobilidade Eletroforética , Esofagite/genética , Esofagite/microbiologia , Humanos , Imuno-Histoquímica , Interleucina-1beta/genética , NF-kappa B/genética , NF-kappa B/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transdução de Sinais/fisiologia , beta-Defensinas/genéticaRESUMO
BACKGROUND: Candida albicans resides on epithelial surfaces as part of the physiological microflora. However, under certain conditions it may cause life-threatening infections like Candida sepsis. Human beta-defensins (hBDs) are critical components of host defense at mucosal surfaces and we have recently shown that hBD-2 and hBD-3 are upregulated in Candida esophagitis. We therefore studied the role of Candidate signalling pathways in order to understand the mechanisms involved in regulation of hBD-expression by C. albicans. We used the esophageal cell line OE21 and analysed the role of paracrine signals from polymorphonuclear leukocytes (PMN) in an in vitro model of esophageal candidiasis. RESULTS: Supernatants of C. albicans or indirect coculture with C. albicans induces upregulation of hBD-2 and hBD-3 expression. PMNs strongly amplifies C. albicans-mediated induction of hBDs. By EMSA we demonstrate that C. albicans activates NF-kappaB and AP-1 in OE21 cells. Inhibition of these pathways revealed that hBD-2 expression is synergistically regulated by both NF-kappaB and AP-1. In contrast hBD-3 expression is independent of NF-kappaB and relies solely on an EGFR/MAPK/AP-1-dependent pathway. CONCLUSION: Our analysis of signal transduction events demonstrate a functional interaction of epithelial cells with PMNs in response to Candida infection involving divergent signalling events that differentially govern hBD-2 and hBD-3 expression.
Assuntos
Candida albicans/imunologia , Candidíase/imunologia , Esôfago/metabolismo , beta-Defensinas/metabolismo , Candida albicans/patogenicidade , Candidíase/patologia , Candidíase/fisiopatologia , Linhagem Celular , Técnicas de Cocultura , Ensaio de Desvio de Mobilidade Eletroforética , Receptores ErbB/metabolismo , Esofagite , Esôfago/imunologia , Esôfago/microbiologia , Esôfago/patologia , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Regulação da Expressão Gênica , Humanos , Imunidade nas Mucosas , Leucócitos Mononucleares/imunologia , Leucócitos Mononucleares/metabolismo , NF-kappa B/metabolismo , Comunicação Parácrina , Transdução de Sinais/imunologia , Fator de Transcrição AP-1/metabolismo , Virulência , beta-Defensinas/genética , beta-Defensinas/imunologiaRESUMO
Our aim was to determine the spectrum and accumulation of mutations in surveillance biopsies from Barrett's mucosa of individual patients during follow-up. We performed loss of heterozygosity (LOH) analysis of six recently described tumor suppressor genes relevant for the carcinogenesis of Barrett's adenocarcinoma from laser-microdissected, paraffin-embedded biopsy samples of Barrett's mucosa without or with low-grade dysplastic change. 118 biopsy samples from 26 patients were taken during surveillance programs in time intervals ranging between 6 and 51 months. We found no significant increase in LOH events at least in a 51-month interval. In two patients, Barrett's adenocarcinoma was diagnosed 6 months after the first diagnosis of Barrett's mucosa. Six of 26 patients did not show LOH. The remaining patients exhibited a striking variation of LOH patterns and accumulations in biopsy samples during follow-up. From our microsatellite marker panel, we were not able to define a single surrogate marker that could serve as a potential biomarker, indicating an increased risk of progression to Barrett's adenocarcinoma. However, LOH combinations, especially APC/p16(INK4) or APC/p53, deserve attention as putative biomarkers in future studies. Our results raise important questions regarding the biological dynamics of mutations in Barrett's mucosa in addition to the influence of sampling, especially with regard to the number of biopsies taken from Barrett's mucosa.
Assuntos
Adenocarcinoma/genética , Esôfago de Barrett/genética , Neoplasias Esofágicas/genética , Esôfago/patologia , Genes Supressores de Tumor , Mutação , Lesões Pré-Cancerosas/genética , Adenocarcinoma/patologia , Idoso , Idoso de 80 Anos ou mais , Esôfago de Barrett/patologia , Biópsia/métodos , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/patologia , Progressão da Doença , Neoplasias Esofágicas/patologia , Esofagoscopia , Feminino , Seguimentos , Regulação Neoplásica da Expressão Gênica , Genes APC , Genes p16 , Genes p53 , Alemanha , Humanos , Perda de Heterozigosidade , Masculino , Pessoa de Meia-Idade , Mucosa/patologia , Reação em Cadeia da Polimerase , Lesões Pré-Cancerosas/patologia , Reprodutibilidade dos Testes , Fatores de TempoRESUMO
Radiotherapy is an important component in the multidisciplinary treatment of breast cancer. In recent years, the cardiac risks of radiation have been discussed several times. This problem has long been known and resolved from the radiotherapeutic point of view. The current data is briefly described here.