RESUMEN
During regular health status monitoring of the colony of amphibian, Mycobacterium (M.) gordonae were isolated from granulomatous lesions of the tiptoes from the South African clawed frog (Xenopus laevis) maintained at the Tierforschungszentrum of the University of Ulm. During a period of three years a total of 21 animals of the colony, consisting of 350-400 frogs, showed granuloma of the tip of the toes and a loss of the claws. The general condition and the behavior of the frogs appeared to be unchanged. Using a selective medium one isolate was cultured and identified by sequencing of the 16S rRNA gene. To apply a rapid diagnostic method for detecting mycobacteria, in particular M. gordonae in the health monitoring programme of the Xenopus laevis colony, we established the rpoB gene PCR followed by HaeIII restriction analysis of the PCR product. We identified M. gordonae from granuloma of the tiptoes and from unaltered tissue samples of the lungs and skin by PCR restriction analysis. Since mycobacterial species apparently are widespread in granulomatous lesions of the tiptoes of Xenopus laevis, we hypothesize a pathogenic potential. This view is supported by an increasing number of reports in the literature on infections with nontuberculous, "non-pathogenic" mycobacteria in Xenopus laevis.
Asunto(s)
Granuloma/veterinaria , Pezuñas y Garras/patología , Infecciones por Mycobacterium no Tuberculosas/veterinaria , Micobacterias no Tuberculosas/patogenicidad , Xenopus laevis/microbiología , Animales , Animales de Zoológico , Secuencia de Bases , Granuloma/microbiología , Granuloma/patología , Inmunohistoquímica/veterinaria , Infecciones por Mycobacterium no Tuberculosas/microbiología , Infecciones por Mycobacterium no Tuberculosas/patología , Micobacterias no Tuberculosas/aislamiento & purificación , Reacción en Cadena de la Polimerasa/veterinaria , ARN Ribosómico 16S/genéticaRESUMEN
Chronic heart failure is associated with an activation of the immune system characterized among other factors by the cardiac synthesis and serum expression of proinflammatory cytokines. There is unequivocal clinical and experimental evidence that the cytokine tumor necrosis factor-alpha is involved in the development of chronic heart failure, but a putative cardiotoxic potential of the proinflammatory cytokine interferon (IFN)-gamma remains primarily unknown. To investigate this issue we analyzed the cardiac phenotype of SAP-IFN-gamma transgenic mice, which constitutively express IFN-gamma in their livers and hence exhibit high circulating serum levels of this cytokine. SAP-IFN-gamma mice spontaneously developed chronic active myocarditis, characterized by the infiltration of not only CD4(+) and CD8(+) T cells but also Mac2(+) (galectin 3(+)) macrophages and CD11c(+) dendritic cells, eventually culminating in cardiomyopathy. Echocardiographic analyses exhibited a left ventricular dilation and impaired systolic function induced by IFN-gamma overexpression. IFN-gamma-mediated cardiotoxicity was associated with high-level cardiac transcription of the proinflammatory cytokines tumor necrosis factor-alpha and interleukin-12 and the macrophage-attracting chemokines MCP1 and MIP1-alpha. Myotoxic IFN-gamma effects could not be detected in smooth or striated muscle tissue, suggesting cardiomyocellular specificity of the toxic IFN-gamma effect. The precise mechanism of IFN-gamma cardiotoxicity remains to be elucidated.
Asunto(s)
Cardiomiopatías/patología , Interferón gamma/genética , Miocarditis/patología , Animales , Cardiomiopatías/genética , Cardiomiopatías/metabolismo , Enfermedad Crónica , Células Dendríticas/metabolismo , Células Dendríticas/patología , Ecocardiografía , Femenino , Expresión Génica , Corazón/fisiopatología , Humanos , Interferón gamma/sangre , Interferón gamma/fisiología , Interleucina-12/genética , Interleucina-12/metabolismo , Mucosa Intestinal/metabolismo , Intestinos/patología , Macrófagos/metabolismo , Macrófagos/patología , Masculino , Ratones , Ratones Endogámicos C57BL , Ratones Endogámicos , Ratones Transgénicos , Miocarditis/genética , Miocarditis/metabolismo , Regiones Promotoras Genéticas/genética , Ratas , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Componente Amiloide P Sérico/genética , Linfocitos T/metabolismo , Linfocitos T/patología , Factor de Necrosis Tumoral alfa/genética , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
BACKGROUND/AIMS: Interferon gamma (IFNgamma) controls hepatitis B virus replication. As systemic application may cause severe adverse effects, approaches of liver-directed IFNgamma gene therapy may represent an attractive alternative for treatment of chronic viral hepatitis B and thus needs testing in vivo in suitable animal models. METHODS: We therefore crossbred Alb-1HBV transgenic mice overexpressing the large HBV surface protein (LHBs) in their livers and developing LHBs storage disease and ground glass hepatocyte appearance with SAP-IFNgamma transgenic animals previously shown to exhibit constitutive hepatic IFNgamma expression, and analyzed the resulting double-transgenic offspring. RESULTS: We found that IFNgamma coexpression significantly reduced hepatic LHBs expression and thereby inhibited hepatocellular LHBs storage disease and ground glass hepatocyte appearance. The beneficial antiviral IFNgamma effects as observed in Alb1-HBV SAP-IFNgamma double-transgenic livers were associated with significantly elevated serum ALT concentrations, massive mononuclear cell infiltrates, appearance of Councilman bodies, and increased alpha-PARP (poly(ADP-ribose) polymerase cleavage). CONCLUSIONS: Exacerbation of hepatic necroinflammation and increased hepatocellular apoptosis rate in IFNgamma-expressing Alb1-HBV transgenic livers suggest that special precautions be taken for testing approaches of liver-specific IFNgamma expression in patients with chronic hepatitis B.
Asunto(s)
Antígenos de Superficie de la Hepatitis B/metabolismo , Hepatitis B Crónica/genética , Hepatitis B Crónica/metabolismo , Interferón gamma/biosíntesis , Animales , Apoptosis/genética , Terapia Genética/métodos , Antígenos de Superficie de la Hepatitis B/biosíntesis , Antígenos de Superficie de la Hepatitis B/genética , Hepatitis B Crónica/patología , Hepatitis B Crónica/terapia , Hepatocitos/patología , Interferón gamma/genética , Hígado/metabolismo , Hígado/patología , Ratones , Ratones Endogámicos C57BL , Ratones TransgénicosRESUMEN
The function of the X protein (pX) in the replication cycle of mammalian hepadnaviruses is enigmatic. Using tissue culture experiments it has been shown that the X gene product is not central to hepatitis B virus (HBV) replication and virion export. However, at present it is still unclear whether this also applies to the in vivo situation. Using a terminally redundant X-deficient HBV DNA construct, transgenic mice were established that exhibited high-level expression of the viral core protein in liver and kidneys. Importantly, replicative DNA intermediates and mature viral genomes could be detected in the liver and serum of these mice, respectively. These findings indicate that, in the in vivo model of transgenic mice, the HBV X (HBx) gene product is not required for HBV replication and virion secretion.