Diversity of murine norovirus strains isolated from asymptomatic mice of different genetic backgrounds within a single U.S. research institute

Antibody prevalence studies in laboratory mice indicate that murine norovirus (MNV) infections are common, but the natural history of these viruses has not been fully established. This study examined the extent of genetic diversity of murine noroviruses isolated from healthy laboratory mice housed in multiple animal facilities within a single, large research institute- the National Institute of Allergy and Infectious Diseases of the National Institutes of Health (NIAID-NIH) in Bethesda, Maryland, U.S. Ten distinct murine norovirus strains were isolated from various tissues and feces of asymptomatic wild type sentinel mice as well as asymptomatic immunodeficient (RAG 2(-/-)) mice. The NIH MNV isolates showed little cytopathic effect in permissive RAW264.7 cells in early passages, but all isolates examined could be adapted to efficient growth in cell culture by serial passage. The viruses, although closely related in genome sequence, were distinguishable from each other according to facility location, likely due to the introduction of new viruses into each facility from separate sources or vendors at different times. Our study indicates that the murine noroviruses are widespread in these animal facilities, despite rigorous guidelines for animal care and maintenance.

Secretoglobin 3A2 suppresses bleomycin-induced pulmonary fibrosis by transforming growth factor beta signaling down-regulation

With increasing worldwide rates of morbidity and mortality of pulmonary fibrosis, the development of effective therapeutics for this disease is of great interest. Secretoglobin (SCGB) 3A2, a novel cytokine-like molecule predominantly expressed in pulmonary airways epithelium, exhibits anti-inflammatory and growth factor activities. In the current study SCGB3A2 was found to inhibit TGFβ-induced differentiation of fibroblasts to myofibroblasts, a hallmark of the fibrogenic process, using pulmonary fibroblasts isolated from adult mice. This induction was through increased phosphorylation of STAT1 and expression of SMAD7 and decreased phosphorylation of SMAD2 and SMAD3. To demonstrate the effect of SCGB3A2 on the TGFβ signaling in vivo, a bleomycin-induced pulmonary fibrosis mouse model was used. Mice were administered bleomycin intratracheally followed by intravenous injection of recombinant SCGB3A2. Histological examination in conjunction with inflammatory cell counts in bronchoalveolar lavage fluids demonstrated that SCGB3A2 suppressed bleomycin-induced pulmonary fibrosis. Microarray analysis was carried out using RNAs from lungs of bleomycin-treated mice with or without SCGB3A2 and normal mice treated with SCGB3A2. The results demonstrated that SCGB3A2 affects TGFβ signaling and reduces the expression of genes involved in fibrosis. This study suggests the potential utility of SCGB3A2 for targeting TGFβ signaling in the treatment of pulmonary fibrosis.

Proliferative and nonproliferative lesions of the rat and mouse hepatobiliary system

The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a joint initiative of the Societies of Toxicologic Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally-accepted nomenclature for proliferative and non-proliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature and differential diagnosis for classifying microscopic lesions observed in the hepatobiliary system of laboratory rats and mice, with color microphotographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available for society members electronically on the internet (http://goreni.org). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. A widely accepted and utilized international harmonization of nomenclature for lesions of the hepatobiliary system in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Pathology of the laboratory mouse: an International Workshop on Challenges for High Throughput Phenotyping

The fifth in a series of European workshops for veterinary and human pathologists, "Pathology of the Laboratory Mouse: An International Workshop on Challenges for High Throughput Phenotyping," was held in Bordeaux, France, from September 30 to October 1, 2010. In this report we outline the rationale for setting up this workshop series, summarize our experience, and suggest approaches for optimizing histopathology phenotyping for gene function discovery.

Immunogenicity and protective efficacy in mice and hamsters of a β-propiolactone inactivated whole virus SARS-CoV vaccine

The immunogenicity and efficacy of β-propiolactone (BPL) inactivated whole virion SARS-CoV (WI-SARS) vaccine was evaluated in BALB/c mice and golden Syrian hamsters. The vaccine preparation was tested with or without adjuvants. Adjuvant Systems AS01(B) and AS03(A) were selected and tested for their capacity to elicit high humoral and cellular immune responses to WI-SARS vaccine. We evaluated the effect of vaccine dose and each adjuvant on immunogenicity and efficacy in mice, and the effect of vaccine dose with or without the AS01(B) adjuvant on the immunogenicity and efficacy in hamsters. Efficacy was evaluated by challenge with wild-type virus at early and late time points (4 and 18 wk post-vaccination). A single dose of vaccine with or without adjuvant was poorly immunogenic in mice; a second dose resulted in a significant boost in antibody levels, even in the absence of adjuvant. The use of adjuvants resulted in higher antibody titers, with the AS01(B)-adjuvanted vaccine being slightly more immunogenic than the AS03(A)-adjuvanted vaccine. Two doses of WI-SARS with and without Adjuvant Systems were highly efficacious in mice. In hamsters, two doses of WI-SARS with and without AS01(B) were immunogenic, and two doses of 2 μg of WI-SARS with and without the adjuvant provided complete protection from early challenge. Although antibody titers had declined in all groups of vaccinated hamsters 18 wk after the second dose, the vaccinated hamsters were still partially protected from wild-type virus challenge. Vaccine with adjuvant provided better protection than non-adjuvanted WI-SARS vaccine at this later time point. Enhanced disease was not observed in the lungs or liver of hamsters following SARS-CoV challenge, regardless of the level of serum neutralizing antibodies.

Carcinogenic effects of "whole-life" exposure to inorganic arsenic in CD1 mice

In a previously developed mouse model, arsenic exposure in utero induces tumors at multiple sites in the offspring as adults, often duplicating human targets. However, human environmental inorganic arsenic exposure occurs during the entire life span, not just part of gestation. Thus, "whole-life" inorganic arsenic carcinogenesis in mice was studied. CD1 mice were exposed to 0, 6, 12, or 24 ppm arsenic in the drinking water 2 weeks prior to breeding, during pregnancy, lactation, and after weaning through adulthood. Tumors were assessed in offspring until 2 years of age. Arsenic induced dose-related increases in lung adenocarcinoma (both sexes), hepatocellular carcinoma (both sexes), gallbladder tumors (males), and uterine carcinomas. Arsenic induced dose-related increases in ovarian tumors (including carcinomas) starting with the lowest dose. Adrenal tumors increased at all doses (both sexes). Arsenic-induced lung and liver cancers were highly enriched for cancer stem cells, consistent with prior work with skin cancers stimulated by prenatal arsenic. Reproductive tract tumors overexpressed cyclooxygenase-2 and estrogen receptor-α. Arsenic target sites were remarkably similar to prior transplacental studies, although tumors from whole-life exposure were generally more aggressive and frequent. This may indicate that arsenic-induced events in utero dictate target site in some tissues, whereas other exposure periods of arsenic enhance incidence or progression, though other factors could be at play, like cumulative dose. Whole-life arsenic exposure induced tumors at dramatically lower external doses than in utero arsenic only while more realistically duplicating human exposure.

Transient disruption of liver gap junctional intercellular communication and induction of apoptosis after administration of 1,4-bis[2-(3,5 dichloropyridyloxy)]benzene in mice

Gap junctional intercellular communication (GJIC) and connexin expression (Cx26 and Cx32) in mouse liver were studied after administration of 4-bis[2-(3,5 dichloropyridyloxy)]benzene (TCPOBOP), a phenobarbital-like enzyme inducer. Female C57Bl/6 mice were administered TCPOBOP (5.8 mg/kg BW) and euthanized 0, 24, 48 and 72 hours later. Liver samples were snap frozen, or fixed in formalin, or submitted to GJIC analysis. The proliferating cell nuclear antigen (PCNA) immunohistochemistry and the Western blotting for Cx26 and Cx32 were performed. After 48 and 72 h of drug administration the liver-to-body weight ratio was increased 70% and 117% (p<0.0001), respectively. There were temporal-dependent alterations in liver histopathology and a significant increase in cell proliferation was noted after 48 h and sustained after 72 h, though to a lesser extent (p<0.0001). In addition, TCPOBOP administration induced apoptosis, which appeared to be time-dependent showing statistical significance only after 72 h (p<0.0001). Interestingly, a transient disruption by nearly 50% of GJIC capacity was detected after 48 h of drug ingestion, which recovered after 72 h (p=0.003). These GJIC changes were due to altered levels of Cx26 and Cx32 in the livers of TCPOBOP-treated mice. We concluded that a single administration of TCPOBOP transiently disrupted the levels of GJIC due to decreased expression of connexins and increased apoptotic cell death in mouse liver.

The histopathologic and molecular basis for the diagnosis of histiocytic sarcoma and histiocyte-associated lymphoma of mice

Histiocytic sarcoma (HS) and histiocyte-associated lymphoma (HAL) of mice are difficult to distinguish histologically. Studies of multiple cases initially diagnosed as HS or HAL allowed us to define HS as round, fusiform, or mixed cell types that were F4/80+, Mac-2+, and PAX5-; that lacked markers for other sarcomas; and that had immune receptor genes in germline configuration. Two other subsets had clonal populations of lymphocytes. The first, HAL, featured malignant lymphocytes admixed with large populations of normal-appearing histiocytes. The second appeared to be composites of lymphoma and HS. Several cases suggestive of B myeloid-lineage plasticity were also observed.

Hepatic Enzyme Induction

Hepatic enzyme induction is generally an adaptive response associated with increases in liver weight, induction of gene expression, and morphological changes in hepatocytes. The additive growth and functional demands that initiated the response to hepatic enzyme induction cover a wide range of stimuli including pregnancy and lactation, hormonal fluctuations, dietary constituents, infections associated with acute-phase proteins, as well as responses to exposure to xenobiotics. Common xenobiotic enzyme inducers trigger pathways involving the constitutive androstane receptor (CAR), the peroxisome proliferator-activated receptor (PPAR), the aryl hydrocarbon receptor (AhR), and the pregnane-X-receptor (PXR). Liver enlargement in response to hepatic enzyme induction is typically associated with hepatocellular hypertrophy and often, transient hepatocyte hyperplasia. The hypertrophy may show a lobular distribution, with the pattern of lobular zonation and severity reflecting species, strain, and sex differences in addition to effects from specific xenobiotics. Toxicity and hepatocarcinogenicity may occur when liver responses exceed adaptive changes or induced enzymes generate toxic metabolites. These undesirable consequences are influenced by the type and dose of xenobiotic and show considerable species differences in susceptibility and severity that need to be understood for assessing the potential effects on human health from similar exposures to specific xenobiotics.

Secretoglobin 3A2/uteroglobin-related protein 1 is a novel marker for pulmonary carcinoma in mice and humans

Secretoglobin (SCGB) 3A2, also called uteroglobin-related protein (UGRP) 1, is a downstream target for a homeodomain transcription factor NKX2-1, which is critical for the development of lung, thyroid and ventral forebrain. Both SCGB3A2 and NKX2-1 are expressed in airway epithelial cells and the latter also in alveolar Type II cells. NKX2-1 has been used clinically for diagnosis of human pulmonary tumors. Recently, the expression of SCGB3A2 was reported in human carcinomas, suggesting the use of this protein as a tumor marker. In this study, 28 lung tumors from aging B6;129 mice and nine lung adenocarcinomas from CC10TAg transgenic mice that express SV40 large T antigen under the mouse Scgb1a1 (CC10) gene promoter, were subjected to histopathological and immunohistochemical analyses for the expression of NKX2-1 and SCGB3A2. NKX2-1 was expressed in all types of tumors albeit more focally in carcinomas. In contrast, SCGB3A2 normally expressed in Clara cells, was negative in Type II cell hyperplasias and adenomas. However, it was expressed in alveolar Type II cell carcinomas and Clara cell adenocarcinomas. In these carcinomas, SCGB3A2 expression was observed in the portion of the tumor where NKX2-1 expression was reduced or almost abolished. As a comparison, the expression of SCGB3A2 and NKX2-1 from 23 human non-small cell lung carcinoma specimens was also examined. The results demonstrate that SCGB3A2 is a useful marker for diagnosis of pulmonary tumors both in mice and humans.

SARS-CoV pathogenesis is regulated by a STAT1 dependent but a type I, II and III interferon receptor independent mechanism

Severe acute respiratory syndrome coronavirus (SARS-CoV) infection often caused severe end stage lung disease and organizing phase diffuse alveolar damage, especially in the elderly. The virus-host interactions that governed development of these acute end stage lung diseases and death are unknown. To address this question, we evaluated the role of innate immune signaling in protection from human (Urbani) and a recombinant mouse adapted SARS-CoV, designated rMA15. In contrast to most models of viral pathogenesis, infection of type I, type II or type III interferon knockout mice (129 background) with either Urbani or MA15 viruses resulted in clinical disease outcomes, including transient weight loss, denuding bronchiolitis and alveolar inflammation and recovery, identical to that seen in infection of wildtype mice. This suggests that type I, II and III interferon signaling play minor roles in regulating SARS pathogenesis in mouse models. In contrast, infection of STAT1-/- mice resulted in severe disease, high virus titer, extensive pulmonary lesions and 100% mortality by day 9 and 30 post-infection with rMA15 or Urbani viruses, respectively. Non-lethal in BALB/c mice, Urbani SARS-CoV infection in STAT1-/- mice caused disseminated infection involving the liver, spleen and other tissues after day 9. These findings demonstrated that SARS-CoV pathogenesis is regulated by a STAT1 dependent but type I, II and III interferon receptor independent, mechanism. In contrast to a well documented role in innate immunity, we propose that STAT1 also protects mice via its role as an antagonist of unrestrained cell proliferation.

Evolution of the uses of rats and mice for assessing carcinogenic risk from chemicals in humans

With developments in the philosophy behind animal testing for carcinogenicity and toxicity, with increasing emphasis on Mode of Action analysis, the future usefulness of the 2 year rodent carcinogenesis bioassay is in doubt.

The Roles of the Toxicologic Pathologist in Cancer Research

Cancer in an important disease throughout the world and a major cause of death in both humans and animals. Pathologists play a critical role in cancer research and in the diagnosis, treatment, and prevention of human and animal cancers. They participate in basic and translational research in laboratories of colleges and universities, other research institutes, government research and regulatory agencies, and in the biotech, chemical, and pharmaceutical industries. This introductory review to the 2009 STP Symposium on Cancer will identify and discuss the major roles of pathologists in cancer research.

Step change in the efficiency of centrifugation through cell engineering: co-expression of Staphylococcal nuclease to reduce the viscosity of the bioprocess feedstock

Cell engineering to enable step change improvements in bioprocessing can be directed at targets other than increasing product titer. The physical properties of the process suspension such as viscosity, for example, have a major impact on various downstream processing unit operations. The release of chromosomal DNA during homogenization of Escherichia coli and its influence on viscosity is well-recognized. In this current article we demonstrate co-expression of Staphylococcus aureus nuclease in E. coli to reduce viscosity through auto-hydrolysis of nucleic acids. Viscosity reduction of up to 75% was achieved while the particle size distribution of cell debris was maintained approximately constant (d(50) = 0.5-0.6 microm). Critically, resultant step change improvements to the clarification performance under disc-stack centrifugation conditions are shown. The cell-engineered nuclease matched or exceeded the viscosity reduction performance seen with the addition of exogenous nuclease removing the expense and validation issues associated with such additions to a bioprocess. The resultant material dramatically altered performance in scale-down mimics of continuous disc-stack centrifugation. Laboratory scale data indicated that a fourfold reduction in the settling area of a disc-stack centrifuge can be expected due to a less viscous process stream achieved through nuclease co-expression with a recombinant protein.

Cellular inflammatory response to flaviviruses in the central nervous system of a primate host

Flaviviruses such as tick-borne encephalitis virus, Japanese encephalitis virus, West Nile virus, and St. Louis encephalitis virus are important neurotropic human pathogens, typically causing a devastating and often fatal neuroinfection. Flaviviruses induce neuroinflammation with typical features of viral encephalitides, including inflammatory cell infiltration, activation of microglia, and neuronal degeneration. Development of safe and effective live-virus vaccines against neurotropic flavivirus infections demands a detailed knowledge of their neuropathogenesis in a primate host that is evolutionarily close to humans. Here, we used computerized morphometric analysis to quantitatively assess the cellular inflammatory responses in the central nervous system (CNS) of rhesus monkeys infected with three antigenically divergent attenuated flaviviruses. The kinetics, spatial pattern, and magnitude of microglial activation, trafficking of T and B cells, and changes in T cell subsets within the CNS define unique phenotypic signatures for each of the three viruses. Our results provide a benchmark for investigation of cellular inflammatory responses induced by attenuated flaviviruses in the CNS of primate hosts and provide insight into the neuropathogenesis of flavivirus encephalitis that might guide the development of safe and effective live-virus vaccines.

Role of NKX2-1 in N-bis(2-hydroxypropyl)-nitrosamine-induced thyroid adenoma in mice

NKX2-1 is a homeodomain transcription factor that is critical for genesis of the thyroid and transcription of the thyroid-specific genes. Nkx2-1-thyroid-conditional hypomorphic mice were previously developed in which Nkx2-1 gene expression is lost in 50% of the thyroid cells. Using this mouse line as compared with wild-type and Nkx2-1 heterozygous mice, a thyroid carcinogenesis study was carried out using the genotoxic carcinogen N-bis(2-hydroxypropyl)-nitrosamine (DHPN), followed by sulfadimethoxine (SDM) or the non-genotoxic carcinogen amitrole (3-amino-1,2,4-triazole). A significantly higher incidence of adenomas was obtained in Nkx2-1-thyroid-conditional hypomorphic mice as compared with the other two groups of mice only when they were treated with DHPN + SDM, but not amitrole. A bromodeoxyuridine incorporation study revealed that thyroids of the Nkx2-1-thyroid-conditional hypomorphic mice had >2-fold higher constitutive cell proliferation rate than the other two groups of mice, suggesting that this may be at least partially responsible for the increased incidence of adenoma in this mouse line after genotoxic carcinogen exposure. Thus, NKX2-1 may function to control the proliferation of thyroid follicular cells following damage by a genotoxic carcinogen.

Sand fly salivary proteins induce strong cellular immunity in a natural reservoir of visceral leishmaniasis with adverse consequences for Leishmania

Immunity to a sand fly salivary protein protects against visceral leishmaniasis (VL) in hamsters. This protection was associated with the development of cellular immunity in the form of a delayed-type hypersensitivity response and the presence of IFN-gamma at the site of sand fly bites. To date, there are no data available regarding the cellular immune response to sand fly saliva in dogs, the main reservoirs of VL in Latin America, and its role in protection from this fatal disease. Two of 35 salivary proteins from the vector sand fly Lutzomyia longipalpis, identified using a novel approach termed reverse antigen screening, elicited strong cellular immunity in dogs. Immunization with either molecule induced high IgG(2) antibody levels and significant IFN-gamma production following in vitro stimulation of PBMC with salivary gland homogenate (SGH). Upon challenge with uninfected or infected flies, immunized dogs developed a cellular response at the bite site characterized by lymphocytic infiltration and IFN-gamma and IL-12 expression. Additionally, SGH-stimulated lymphocytes from immunized dogs efficiently killed Leishmania infantum chagasi within autologous macrophages. Certain sand fly salivary proteins are potent immunogens obligatorily co-deposited with Leishmania parasites during transmission. Their inclusion in an anti-Leishmania vaccine would exploit anti-saliva immunity following an infective sand fly bite and set the stage for a protective anti-Leishmania immune response.

The heart is an early target of anthrax lethal toxin in mice: a protective role for neuronal nitric oxide synthase (nNOS)

Anthrax lethal toxin (LT) induces vascular insufficiency in experimental animals through unknown mechanisms. In this study, we show that neuronal nitric oxide synthase (nNOS) deficiency in mice causes strikingly increased sensitivity to LT, while deficiencies in the two other NOS enzymes (iNOS and eNOS) have no effect on LT-mediated mortality. The increased sensitivity of nNOS-/- mice was independent of macrophage sensitivity to toxin, or cytokine responses, and could be replicated in nNOS-sufficient wild-type (WT) mice through pharmacological inhibition of the enzyme with 7-nitroindazole. Histopathological analyses showed that LT induced architectural changes in heart morphology of nNOS-/- mice, with rapid appearance of novel inter-fiber spaces but no associated apoptosis of cardiomyocytes. LT-treated WT mice had no histopathology observed at the light microscopy level. Electron microscopic analyses of LT-treated mice, however, revealed striking pathological changes in the hearts of both nNOS-/- and WT mice, varying only in severity and timing. Endothelial/capillary necrosis and degeneration, inter-myocyte edema, myofilament and mitochondrial degeneration, and altered sarcoplasmic reticulum cisternae were observed in both LT-treated WT and nNOS-/- mice. Furthermore, multiple biomarkers of cardiac injury (myoglobin, cardiac troponin-I, and heart fatty acid binding protein) were elevated in LT-treated mice very rapidly (by 6 h after LT injection) and reached concentrations rarely reported in mice. Cardiac protective nitrite therapy and allopurinol therapy did not have beneficial effects in LT-treated mice. Surprisingly, the potent nitric oxide scavenger, carboxy-PTIO, showed some protective effect against LT. Echocardiography on LT-treated mice indicated an average reduction in ejection fraction following LT treatment in both nNOS-/- and WT mice, indicative of decreased contractile function in the heart. We report the heart as an early target of LT in mice and discuss a protective role for nNOS against LT-mediated cardiac damage.