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A mouse model of chronic pulmonary infection with Pseudomonas aeruginosa and Pseudomonas cepacia.

A mouse model of chronic pulmonary infection with either Pseudomonas aeruginosa or Pseudomonas cepacia was developed to compare bacteriologic and pathologic features of these infections. Experimental pneumonia was established in Swiss mice by transoral intratracheal inoculation of 10(3)-10(4) colony-forming units of mucoid P. aeruginosa or P. cepacia enmeshed in agarose beads. Unilateral infection with either strain was tolerated without morbidity. By 10 days postinoculation, the mean colony-forming units per infected lung was 3.8 X 10(5) for P. aeruginosa and 1.0 X 10(5) for P. cepacia. Bacterial counts remained stable through 21 days with no significant difference between organisms. Acute and chronic inflammatory histopathologic changes similar to many found in the lungs of cystic fibrosis patients were present in 95% of lung specimens. The changes occurred with both organisms but were more extensive with mucoid P. aeruginosa. This model represents an important tool for study of the contribution of complement, antibody, and adoptive transfer of T cell-mediated immunity to the pathogenesis of chronic pneumonia with Pseudomonas species, and represents the first successful model of chronic pulmonary infection with P. cepacia.

Animals↗

Hepatic lipid abnormalities in a chemical/viral mouse model for Reye's syndrome.

We have examined hepatic lipid profiles in a mouse model for Reye's Syndrome (RS) in which young animals are exposed to nontoxic doses of an industrial pesticide emulsifier and subsequently are infected with sublethal doses of mouse-adapted human Influenza B (Lee) virus (FluB). The purpose of this study was to determine whether liver lipid content was altered in the mice, the time course of any changes, and whether lipid changes were consistent with liver pathology. Neonatal mice exposed dermally to the emulsifier, Toximul MP8 (Tox), had significantly elevated levels of hepatic cholesterol, with otherwise normal lipid composition. Subsequent inoculation of the mice with FluB significantly increased mortality rate. The combined Tox + FluB treatment had several significant effects on liver lipids, including a transient increase in phospholipid (PL) content, a reduction in neutral glycerides and persistently high cholesterol levels. Abnormalities in fatty acid profiles included an apparent elevation in medium chain fatty acids and increased ratios of PL arachidonic to docosahexaenoic acids. Histologically, there was no evidence of fat accumulation in the liver; however, hepatic mitochondria had severe structural abnormalities characteristic of RS. These studies demonstrate that chemical-dependent enhancement of viral virulence is associated with significant alterations of hepatic lipids. We believe that these abnormalities are related to mitochondrial structural damage in RS despite the absence of hepatic steatosis.

Animals↗

Mutant mouse models of depression: candidate genes and current mouse lines.

Depression is a multifactorial and multigenetic disease. At present, three main theories try to conceptualize its molecular and biochemical mechanisms, namely the monoamine-, the hypothalamus-pituitary-adrenal- (HPA-) system- and the neurotrophin-hypotheses. One way to explore, validate or falsify these hypotheses is to alter the expression of genes that are involved in these systems and study their respective role in animal behavior and neuroendocrinological parameters. Following an introduction in which we briefly describe each hypothesis, we review here the different mouse lines generated to study the respective molecular pathways. Among the many mutant lines generated, only a few can be regarded as genetic depression models or as models of predisposition for a depressive syndrome after stress exposure. However, this is likely to reflect the human situation where depressive syndromes are complex, can vary to a great extent with respect to their symptomatology, and may be influenced by a variety of environmental factors. Mice with mutations of candidate genes showing depression-like features on behavioral or neurochemical levels may help to define a complex molecular framework underlying depressive syndromes. Because it is conceivable that manipulation of one single genetic function may be necessary but not sufficient to cause complex behavioral alterations, strategies for improving genetic modeling of depression-like syndromes in animals possibly require a simultaneous targeted dysregulation of several genes involved in the pathogenesis of depression. This approach would correspond to the new concept of 'endophenotypes' in human depression research trying to identify behavioral traits which are thought to be encoded by a limited set of genes.

Animals↗

Atherosclerosis mouse model induced by a high-cholesterol diet supplemented with beta-aminopropionitrile: effects of various anti-atherosclerotic agents on the biochemical parameters.

A mouse model of atherosclerosis was produced by feeding a 1.5% cholesterol diet with 0.4% beta-aminopropionitrile (BAPN) fumarate, a chemical lathyrogen, for 10 weeks, and the pharmacological sensitivity and specificity of this model were evaluated biochemically with various hypolipidemic drugs and calcium antagonists. Histological findings on this model showed typical angiolathyrism with foam cells in the media of the thoracic aorta. Uniform and marked accumulation of cholesterol, notably esterified cholesterol, in the aorta was observed, although it was much less in mice receiving a high-cholesterol diet or BAPN alone. The reduction in elastin contents in the aorta was a characteristic feature of this model. Clofibrate, cetaben and elastase tended to prevent the increase of cholesterol contents in the aorta, together with their significant hypocholesterolemic effects. Nifedipine, diltiazem and verapamil showed a slight preventive effect on the cholesterol accumulation and on the reduction of elastin content in the aorta without a cholesterol lowering effect in the serum. MgCl2 was more effective than other calcium antagonists and even had a hypocholesterolemic effect. The results indicate that this mouse atherosclerosis model may be usable for primary drug evaluation.

4-Aminobenzoic Acid↗

Propagation of human papillomavirus type 11 in human xenografts using the severe combined immunodeficiency (SCID) mouse and comparison to the nude mouse model.

We report propagation of human papillomavirus (HPV) type 11 in human xenografts in the severe combined immunodeficiency (SCID) mouse and compare this new animal model for HPV infection to the previously established athymic nude mouse model. HPV-11-infected foreskin fragments grafted under the renal capsule of SCID mice formed large epithelial cysts that had the histologic and immunocytochemical features of HPV infection. This infection was successfully passaged to nude mice. Viral particles that reacted to an antibody directed to HPV-11 virions were identified from samples recovered from the SCID and nude mice. Viral DNA sequence analysis confirmed that the passaged virus was HPV-11. In a comparative experiment of the nude mouse and SCID mouse models, the latter produced HPV-11-infected xenografts that were larger and more often positive for HPV by immunocytochemistry and presence of viral mRNA than those propagated in the former model. Finally, we observed that growth of HPV-11-infected foreskin fragments in the SCID mouse model is not restricted to the kidney as in the nude mouse, but also can occur in the subcutis and the peritoneum.

Animals↗

Rapamycin inhibits growth of premalignant and malignant mammary lesions in a mouse model of ductal carcinoma in situ.

PURPOSE: Rapamycin has been shown to have antitumor effects in various tumor models. To study the effect of rapamycin at different stages of breast cancer development, we used two unique mouse models of breast cancer with activated phosphatidylinositol 3-kinase (PI3K) pathway. Met-1 tumors are highly invasive and metastatic, and mammary intraepithelial neoplasia-outgrowths (MIN-O), a model for human ductal carcinoma in situ, are transplantable premalignant mammary lesions that develop invasive carcinoma with predictable latencies. Both of these models were derived from mammary lesions in Tg(MMTV-PyV-mT) mice. EXPERIMENTAL DESIGN: Met-1 tumors were used to study the effect of rapamycin treatment on invasive disease. Transplanted MIN-O model was used to study the effect of rapamycin on premalignant mammary lesions. Animals were in vivo micro-positron emission tomography imaged to follow the lesion growth and transformation to tumor during the treatment. Cell proliferation, angiogenesis, and apoptosis was assayed by immunohistochemistry. RESULTS: Rapamycin inhibited in vitro tumor cell proliferation and in vivo Met-1 tumor growth. The growth inhibition was correlated with dephosphorylation of mammalian target of rapamycin (mTOR) targets. Rapamycin treatment significantly reduced the growth of the premalignant MIN-O lesion, as well as tumor incidence and tumor burden. Growth inhibition was associated with reduced cell proliferation and angiogenesis and increased apoptosis. CONCLUSIONS: In PyV-mT mouse mammary models, rapamycin inhibits the growth of premalignant lesions and invasive tumors. Although the inhibitory effect of rapamycin was striking, rapamycin treatment did not completely obliterate the lesions.

Animals↗

[Transgenic mouse models. Their interest in thyroid tumors].

Mouse transgenic models that develop thyroid diseases were generated. All transgenes were driven by the thyroid specific promoter of the thyroglobulin gene. The tissue specificity of the promoter was investigated by using the bacterial chloramphenicol acetyltransferase gene as reporter. The expression of the adenosine A2a receptor resulted in the permanent activation of the cAMP cascade. As a consequence, transgenic mice developed severe hyperthyroidism and a large goiter, demonstrating in vivo the role of the cAMP cascade in the promotion of both function and proliferation of the thyroid cell. These mice constitute a model for autonomous hyperfunctional adenoma and non autoimmune familial hyperthyroidism, where mutant of thyrotropin receptors stimulate the cAMP cascade constitutively. The expression of a mutant of the alpha 1B adrenergic receptor resulted in the constitutive activation of both the cAMP and IP3-CA++ cascades, growth stimulation, hyperfunction, cell degeneracy attributed to the overproduction of free radicals, and development of malignancies. The expression of the SV40 large T antigen promoted the development of aggressive undifferentiated tumors mimicking the phenotype of human anaplastic carcinomas and embryonal tumors. In another transgenic model, the function of the retinoblastoma susceptibility gene product RB1 (and of related proteins) was inhibited by expressing the E7 oncoprotein of human papillomavirus type 16. The result was the development of a differentiated and normofunctional colloid goiter, with progressive development of differentiated malignant lesions. This model suggests the essential role of RB1 and related proteins in the negative control of proliferation that characterizes thyroid cells in the adult. Other transgenic models of thyroid diseases are discussed.

Adenoma↗

Towards a transgenic mouse model of sickle cell disease: hemoglobin SAD.

In order to obtain a transgenic mouse model of sickle cell disease, we have synthesized a novel human beta-globin gene, beta SAD, designed to increase the polymerization of the transgenic human hemoglobin S (Hb S) in vivo. beta SAD (beta S-Antilles-D Punjab) includes the beta 6Val substitution of the beta S chain, as well as two other mutations, Antilles (beta 23Ile) and D Punjab (beta 121Gln) each of which promotes the polymerization of Hb S in human. The beta SAD gene and the human alpha 2-globin gene, each linked to the beta-globin locus control region (LCR) were co-introduced into the mouse germ line. In one of the five transgenic lines obtained, SAD-1, red blood cells contained 19% human Hb SAD (alpha 2 human 1 beta 2SAD) and mouse-human hybrids in addition to mouse hemoglobin. Adult SAD-1 transgenic mice were not anemic but had some abnormal features of erythrocytes and slightly enlarged spleens. Their erythrocytes displayed sickling upon deoxygenation in vitro. SAD-1 neonates were anemic and many did not survive. In order to generate adult mice with a more severe sickle cell syndrome, crosses between the SAD progeny and homozygous for beta-thalassemic mice were performed. Hemoglobin SAD was increased to 26% in beta-thal/SAD-1 mice which exhibited: (i) abnormal erythrocytes with regard to shape and density; (ii) an enlarged spleen and a high reticulocyte count indicating an increased erythropoiesis; (iii) mortality upon hypoxia; (iv) polymerization of hemolysate similar to that obtained in human homozygous sickle cell disease; and (v) anemia and mortality during development.

Anemia, Sickle Cell↗

Steroid receptors and human endometrial carcinoma: studies in a nude mouse model.

An experimental nude mouse system where human endometrial carcinomas of different histologic grade and steroid receptor characteristics can be grown and maintained under defined hormonal milieu by serial transplantation has been developed. Biologically and clinically important information on the role of steroid receptors in eliciting hormonal responses in these tumors has been obtained using this model. These results form the basis for designing and testing various treatment strategies for endometrial carcinomas of different histologic grade and receptor content.

Animals↗

A mouse model for varicella-zoster virus latency.

Following primary infection with varicella-zoster virus (VZV), the virus establishes a latent infection in humans. The molecular pathogenesis of VZV latency is not well understood, mainly due to the lack of an adequate animal model. We report here that we have developed a mouse model for VZV infection that involves corneal inoculation of mice. Although infected animals showed no signs of disease, most of the animals could not eliminate the virus early after infection. By PCR, we demonstrated that at 33 days post-infection (p.i.), viral DNA was still present in more than 60% of the animals (14/21). VZV DNA was most frequently detected in the trigeminal ganglia (7/14) followed by the brain stem (10/21), kidneys (4/21), spleen (3/20), liver (2/21) and brain (1/21). By in situ hybridization, a few cells positive for VZV mRNA were detected in the trigeminal ganglia, brain stem, cerebellum and spleen of a small number of the infected animals as late as 33 days p.i. No viral proteins were detected at the site of inoculation or in any other tissue by immunostaining. Our results suggest that VZV spreads in mice by both viraemia and axonal transport and establishes a non-productive (latent) infection.

Animals↗

A mouse model to study immunity against pseudorabies virus infection: significance of CD4+ and CD8+ cells in protective immunity.

In this study we firstly established a vaccination/challenge model to study pseudorabies virus infection in mice. The mouse model was used to investigate the significance of CD4+ and CD8+ cells and of IFN gamma production in protective immunity. Functional depletion of CD4+ and CD8+ and IFN gamma was obtained in vivo by intraperitoneal injection of alginate-encapsulated anti-CD4, -CD8 or -IFN gamma producing hybridoma's before and at the moment of vaccination. The observed protective immunity was correlated with underlying immunologic responses such as PRV-specific DTH reactivity, lymphoproliferation and cytotoxicity. The significance of CD4+ and CD8+ cells and of IFN gamma production was also investigated for these immunological responses by the same in vivo depletion technique. The results demonstrated that protective vaccination of mice, that could be induced by immunization with 10(7) plaque forming units of the avirulent PRV mutant NIA3 TK-, was characterized by a typical anti-viral Th1 type immune response. A clear PRV-specific, CD4-dependent DTH reactivity and a classical CD8-dependent, MHC-restricted cytotoxicity was induced after protective immunization and the humoral immune response had a bias towards PRV-specific IgG2a formation. In vivo treatment with anti-CD8 and anti-IFN gamma demonstrated that the cytotoxic response and humoral IgG2a response, respectively, were strongly reduced, whereas protection against lethal challenge was unaffected. On the other hand anti-CD4 treatment reduced the induced protection so that 30% of the mice died after lethal challenge. The results of our study demonstrated that CD4+, DTH like effector cells are a crucial effector mechanism for protective immunity against PRV.

Animals↗

Building 'validated' mouse models of human cancer.

As a model system for the understanding of human cancer, the mouse has proved immensely valuable. Indeed, studies of mouse models have helped to define the nature of cancer as a genetic disease and demonstrated the causal role of genetic events found in tumors. As the scientific and medical community's understanding of human cancer becomes more sophisticated, however, limitations and potential weaknesses of existing models are revealed. How valid are these murine models for the understanding and treatment of human cancer? The answer, it appears, depends on the nature of the research requirement. Certain models are better suited for particular applications. Using novel molecular tools and genetic strategies, improved models have recently been described that accurately mimic many aspects of human cancer.

Animals↗

Tracking HIV persistence across T cell lineages during early ART-treated HIV-1-infection using a reservoir-marking humanized mouse model.

Human immunodeficiency virus (HIV) infection depletes CD4 T-cells, and long-term persistence of latent virus prevents full clearance of HIV even in the presence of effective antiretroviral therapy (ART), Here we present the HIV-1-induced lineage tracing (HILT) system, a model that irreversibly marks infected cells within a humanized mouse model, which detects rare latently infected cells. Immunodeficient mice transplanted with genetically modified hematopoietic stem cells develop a human immune system, in which CD4 T-cells contain a genetic switch that permanently labels cells infected by HIV-1 expressing cre-recombinase. Through single-cell RNA sequencing of HILT-marked cells during acute infection and post-ART treatment, we identify distinct CD4+ T-cell transcriptional lineages enriched in either active or latent infections. Comparative gene expression analysis highlights common pathways modulated in both states, including EIF2, Sirtuin, and protein ubiquitination. Critical regulators of these pathways, including JUN, BCL2, and MDM2, change to opposite directions in the two states, highlighting gene expression programs that may support HIV persistence across T-cell lineages and states.

Animals↗

A mouse model for latent tuberculosis.

The aim of the study was to establish a reproducible murine model for latent tuberculosis. We propose an operational definition of latent murine tuberculosis as a stable Mycobacterium-tuberculosis count in lungs and spleens without clinical signs or obvious histopathological changes in the lungs over a long period of time and without spontaneous reactivation of disease. B6D2F1Bom mice were inoculated with a wide range of Mycobacterium tuberculosis doses intraperitoneally or intravenously and followed for a long period to determine suitable conditions to produce latent infection. No anti-tuberculosis drug treatment was used. Microbiological and histopathological studies were carried out. Corticosterone challenge was used to reactivate the latent infection. Mice infected with 4 x 10(4) and 4 x 10(5) bacilli i.p. were followed up to 107 weeks without spontaneous reactivation. The present model is discussed in comparison with previous latent tuberculosis mouse models as well as the possible mechanisms of shift to stationary phase from multiplying bacilli.

Animals↗

Novel mouse models for the investigation of experimental drugs with activity against human varicella-zoster virus.

Suitable small animal models for the testing of antiviral agents with activity against human varicella-zoster virus (VZV) have so far been lacking. Mice and other animals have been found to not be susceptible to VZV infection. The model of choice for drug development has been the infection of monkeys using simian varicella virus (SVV). However, while primates offer potential as models of human varicella disease, their use is limited as experimental models in antiviral research. We have developed two simple mouse models that support replication of human VZV in vivo. In the first, SCID mice were transplanted with human umbilical cord (umbilical cord cushion model) and subsequently infected with VZV. After infection, we were able to demonstrate increasing titres of viral DNA over a 9-day period. In the second model, biocompatible hollow fibres were used for encapsulation of VZV-infected cells. The hollow fibres were then transplanted into immunodeficient and immunocompetent mice and infectious virions were re-isolated. In addition, we demonstrated that both the umbilical cord cushion and the hollow fibre models are suitable tools to test antiviral compounds. Administration of BVDU ibrivudine, Helpin, (E)-5-(2-bromovinyl)-2'-deoxyuridine] significantly reduced the VZV titres in both models.

Animals↗

Mouse models of hyperlipidemia and atherosclerosis.

The mouse is the most utilized model to study lipids and atherosclerosis. Before the advent of the techniques of genetic manipulation it was well known that different inbred strains had varying degrees of susceptibility to diet-induced atherosclerosis. The C57BL/6 mouse was adopted as the standard even though the arterial lesions induced by even extreme diets were limited in size, complexity, and distribution. This changed with the production of several gene knockout and transgenic mice, which in many cases produced remarkable effects on plasma lipoproteins and arterial lesions even without dietary manipulations. The most typical example remains the apoE deficient model, in which a massive hyperlipidemia is accompanied with the development of severe atherosclerotic plaques at the aortic root and throughout the aortic tree. With the creation of the LDL receptor knockout, and the different knockout and transgenic mice with changes in apoB, apoE, and the HDL system, a solid body of new information has emerged on the mechanisms regulating plasma lipoprotein levels and controlling the initial stages of atherogenesis. This paper presents an overview of the most utilized mouse models and a summary of the results obtained with the technique of bone marrow transplantation, an approach to study macrophages in atherosclerosis.

Animals↗

A mouse model of autosomal dominant spastic ataxia and myopathy caused by a mutation in Tuba4a.

Hereditary ataxias are a heterogeneous group of neurodegenerative disorders characterized by impaired balance and coordination, often due to cerebellar dysfunction. Despite advances in identifying genetic causes, animal models remain essential for dissecting underlying mechanisms and testing therapeutic strategies. Here we describe a mouse model of spastic ataxia and myopathy caused by a missense mutation in Tuba4a (n.A626C, p.Gln176Pro). In an ENU mutagenesis screen, a male C57BL/6 J mouse exhibiting muscle wasting and an intention tremor starting at approximately 4 weeks-of-age was identified. The male was bred by in vitro fertilization to BALB/cByJ oocyte donors. Genetic mapping determined dominant inheritance and localized the mutation to Chromosome 1. Genome sequencing revealed single nucleotide polymorphisms (SNPs) in serine threonine kinase 36 (Stk36Y1003N) and alpha-tubulin 4A (Tuba4aQ176P) in the mapping interval. These SNPs were CRISPR-engineered into C57BL/6 J mice, which confirmed the Tuba4aQ176P variant as the causative mutation. Mutant mice are normal at 3 weeks, except for decrement in muscle response following repetitive nerve stimulation. However, by 30 days these mice have overt ataxia, Purkinje neuron degeneration, and extensive skeletal muscle defects, which contribute to a decreased lifespan. Dominant TUBA4A mutations in humans are associated with spastic ataxia type 11 (SPAX11), congenital myopathy type 26 (CMYO26), and frontotemporal dementia/amyotrophic lateral sclerosis type 9 (FTDALS9). Our mice exhibit hallmark features of SPAX11 and CMYO26, but do not show motor neuron degeneration. This specificity makes this model a valuable tool for studying cell-type selective effects of TUBA4A mutations in neurodegeneration and myopathy.

Animals↗

rim2 (recombination-induced mutation 2) is a new allele of pearl and a mouse model of human Hermansky-Pudlak syndrome (HPS): genetic and physical mapping.

A mouse mutation, rim2, is one of a series of spontaneous mutations that arose from the intra-MHC recombinants between Japanese wild mouse-derived wm7 and laboratory MHC haplotypes. This mutation is single recessive and characterized by diluted coat color and hypo-pigmentation of the eyes. We mapped the rim2 gene close to an old coat color mutation, pearl (pe), on Chromosome (Chr) 13 by the high-density linkage analysis. The pearl mutant is known to have abnormalities similar to Hermansky-Pudlak syndrome (HPS), a human hemorrhagic disorder, characterized by albinism and storage pool deficiency (SPD) of dense granules in platelets. A mating cross of C57BL10/Slc-rim2/rim2 and C57BL/6J-pe/pe showed no complementation of coat color. Additionally, characteristics similar to SPD were also observed in rim2. Thus, rim2 appeared to be a new allele of the pe locus and serves as a mouse model for human HPS. We have made a YAC contig covering the rim2/pe locus toward positional cloning of the causative gene.

Albinism, Oculocutaneous↗