Murine Strains Research Articles

Rotavirus NSP1 Protein Inhibits Interferon-Mediated STAT1 Activation

Rotavirus (RV) replicates efficiently in intestinal epithelial cells (IECs) in vivo despite the activation of a local host interferon (IFN) response. Previously, we demonstrated that homologous RV efficiently inhibits IFN induction in single infected and bystander villous IECs in vivo. Paradoxically, RV also induces significant type I IFN expression in the intestinal hematopoietic cell compartment in a relatively replication-independent manner. This suggests that RV replication and spread in IECs must occur despite exogenous stimulation of the STAT1-mediated IFN signaling pathway. Here we report that RV inhibits IFN-mediated STAT1 tyrosine 701 phosphorylation in human IECs in vitro and identify RV NSP1 as a direct inhibitor of the pathway. Infection of human HT29 IECs with simian (RRV) or porcine (SB1A or OSU) RV strains, which inhibit IFN induction by targeting either IFN regulatory factor 3 (IRF3) or NF-κB, respectively, resulted in similar regulation of IFN secretion. By flow cytometric analysis at early times during infection, neither RRV nor SB1A effectively inhibited the activation of Y701-STAT1 in response to exogenously added IFN. However, at later times during infection, both RV strains efficiently inhibited IFN-mediated STAT1 activation within virus-infected cells, indicating that RV encodes inhibitors of IFN signaling targeting STAT1 phosphorylation. Expression of RV NSP1 in the absence of other viral proteins resulted in blockage of exogenous IFN-mediated STAT1 phosphorylation, and this function was conserved in NSP1 from simian, bovine, and murine RV strains. Analysis of NSP1 determinants responsible for the inhibition of IFN induction and signaling pathways revealed that these determinants are encoded on discrete domains of NSP1. Finally, we observed that at later times during infection with SB1A, there was almost complete inhibition of IFN-mediated Y701-STAT1 in bystander cells staining negative for viral antigen. This property segregated with the NSP1 gene and was observed in a simian SA11 monoreassortant that encoded porcine OSU NSP1 but not in wild-type SA11 or a reassortant encoding simian RRV NSP1.

Covering the Cover

Covering the Cover

Mobilizing Experimental Life: Spaces of Becoming with Mutant Mice

This paper uses the figure of the inbred laboratory mouse to reflect upon the management and mobilization of biological difference in the contemporary biosciences. Working through the concept of shifting experimental systems, the paper seeks to connect practices concerned with standardization and control in contemporary research with the emergent and stochastic qualities of biological life. Specifically, it reviews the importance of historical narratives of standardization in experimental systems based around model organisms, before identifying a tension in contemporary accounts of the reproduction and differentiation of inbred mouse strains within them. Firstly, narratives of new strain development, foregrounding personal biography and chance discovery, attest to the contingency and situatedness of apparently universal biotechnological production. Secondly, discoveries of unexpected animal litters challenge efforts to standardize mouse phenotypes and control the reproduction of murine strains over space. The co-existence of these two narratives draws attention to the importance of and interplay between both chance and control, determination and emergence, and the making and moving of experimental life in biomedical research. The reception or denial of such biological excess reflects the distribution of agencies and the emerging spatialities of the global infrastructures of biotechnological development, with implications for future relations between animal lives and human becomings in experimental practices.

Identification of Immune and Viral Correlates of Norovirus Protective Immunity through Comparative Study of Intra-Cluster Norovirus Strains

Whether or not primary norovirus infections induce protective immunity has become a controversial issue, potentially confounded by the comparison of data from genetically distinct norovirus strains. Early human volunteer studies performed with a norovirus-positive inoculum initially led to the conclusion that primary infection does not generate long-term, protective immunity. More recently though, the epidemiological pattern of norovirus pandemics has led to the extrapolation that primary norovirus infection induces herd immunity. While these are seemingly discordant observations, they may in fact reflect virus strain-, cluster-, or genogroup-specific differences in protective immunity induction. Here, we report that highly genetically related intra-cluster murine norovirus strains differ dramatically in their ability to induce a protective immune response: Primary MNV-3 infection induced robust and cross-reactive protection, whereas primary MNV-1 infection induced modest homotypic and no heterotypic protection. In addition to this fundamental observation that intra-cluster norovirus strains display remarkable differences in protective immunity induction, we report three additional important observations relevant to norovirus:host interactions. First, antibody and CD4+ T cells are essential to controlling secondary norovirus infections. Second, the viral minor structural protein VP2 regulates the maturation of antigen presenting cells and protective immunity induction in a virus strain-specific manner, pointing to a mechanism by which MNV-1 may prevent the stimulation of memory immune responses. Third, VF1-mediated regulation of cytokine induction also correlates with protective immunity induction. Thus, two highly genetically-related norovirus strains displayed striking differences in induction of protective immune responses, strongly suggesting that the interpretation of norovirus immunity and vaccine studies must consider potential virus strain-specific effects. Moreover, we have identified immune (antibody and CD4+ T cells) and viral (VP2 and possibly VF1) correlates of norovirus protective immunity. These findings have significant implications for our understanding of norovirus immunity during primary infections as well as the development of new norovirus vaccines.

English

The role of chemokines in virus-induced acute hepatic failure is not well defined. In this study, we investigated the role of CXC chemokine receptor 3 (CXCR3) and its ligands chemokine Mig/CXCL9 (monokine induced by IFN-gamma) and IP-10/CXCL10 (interferon-gamma-inducible protein 10) in the recruitment of intrahepatic lymphocytes and subsequent acute hepatic failure. Balb/cJ mice (6 to 8 weeks, female) were intraperitoneally injected with 100 PFU murine hepatitis virus strain 3 (MHV-3). The proportions and numbers of T cells and NK cells in liver, spleen, and blood as well as the expression of CXCR3 on T cells and NK cells post MHV-3 infection was analyzed by flow cytometry. The hepatic mRNA level of the CXCR3-associated chemokines (CXCL9 and CXCL10) was detected by realtime PCR. A transwell migration assay was used to assess the chemotactic effect of MHV-3-infected hepatocytes and CXCL10 on the splenic lymphocytes. Following MHV-3 infection, the number of hepatic NK cells and T cells and the frequencies of hepatic NK cells and T cells expressing CXCR3 increased markedly; however, in the spleen and peripheral blood, they both decreased significantly. Moreover, the hepatic mRNAs levels of CXCL9 and CXCL10 were significantly elevated post infection. The transwell migration assay demonstrated that MHV-3-infected hepatocytes have the capacity to attract and recruit the splenic NK cells and T cells, and CXCL10 plays a key role in lymphocyte mobilization from the spleen. These results indicate that interactions involving CXCR3 and its ligands (CXCL9 and CXCL10), especially CXCL10 may play a key role in the recruitment of intrahepatic lymphocytes and subsequent necroinflammation and acute hepatic failure.   Key words: Chemokine, interferon gamma-inducible protein 10 (CXCL10), hepatic failure, natural killer cell, T cell.

Candidate genes for limiting cholestatic intestinal injury identified by gene expression profiling

The lack of bile flow from the liver into the intestine can have devastating complications including hepatic failure, sepsis, and even death. This pathologic condition known as cholestasis can result from etiologies as diverse as total parenteral nutrition (TPN), hepatitis, and pancreatic cancer. The intestinal injury associated with cholestasis has been shown to result in decreased intestinal resistance, increased bacterial translocation, and increased endotoxemia. Anecdotal clinical evidence suggests a genetic predisposition to exaggerated injury. Recent animal research on two different strains of inbred mice demonstrating different rates of bacterial translocation with different mortality rates supports this premise. In this study, a microarray analysis of intestinal tissue following common bile duct ligation (CBDL) performed under general anesthesia on these same two strains of inbred mice was done with the goal of identifying the potential molecular mechanistic pathways responsible. Over 500 genes were increased more than 2.0-fold following CBDL. The most promising candidate genes included major urinary proteins (MUPs), serine protease-1-inhibitor (Serpina1a), and lipocalin-2 (LCN-2). Quantitative polymerase chain reaction (qPCR) validated the microarray results for these candidate genes. In an in vitro experiment using differentiated intestinal epithelial cells, inhibition of MUP-1 by siRNA resulted in increased intestinal epithelial cell permeability. Diverse novel mechanisms involving the growth hormone pathway, the acute phase response, and the innate immune response are thus potential avenues for limiting cholestatic intestinal injury. Changes in gene expression were at times found to be not only due to the CBDL but also due to the murine strain. Should further studies in cholestatic patients demonstrate interindividual variability similar to what we have shown in mice, then a “personalized medicine” approach to cholestatic patients may become possible.

New pigementation genes linked to iris illumination defects in BXD glaucoma murine strains using systems genetics and mathematical modeling

New pigementation genes linked to iris illumination defects in BXD glaucoma murine strains using systems genetics and mathematical modeling

CD69+NK cells contribute to the murine hepatitis virus strain 3-induced murine hepatitis

The role of hepatic CD69+ natural killer (NK) cells in virus-induced severe liver injury and subsequent hepatic failure is not well defined. In this study, a mouse model of fulminant liver failure (FHF) induced by murine hepatitis virus strain 3 (MHV-3) was used to study the role of hepatic CD69+NK cells in the development of FHF. The CD69 expression in NK cells in the liver, spleen, bone marrow and peripheral blood was detected by using flow cytometry. The correlation between the CD69 level in hepatic NK cells and liver injury was studied. The functional marker (CD107a), and activating and inhibitory receptor (NKG2D and NKG2A) expressed on CD69+NK cells and CD69-NK cells were detected by using flow cytometry. Pro-inflammatory cytokines (IL-9, IFN-γ and TNF-α) were also examined by using intracellular staining. After MHV-3 infection, the number of CD69+NK cells in the liver of BALB/cJ mice was increased markedly and peaked at 72 h post-infection. Similar changes were also observed in the spleen, bone marrow and peripheral blood. Meanwhile, the CD69 expression in hepatic NK cells was highly correlated with the serum level of ALT and AST. The expression of CD107a and NKG2D, as well as the production of TNF-α, IFN-γ and IL-9 in hepatic CD69+NK cells was all significantly up-regulated during 48-72 h post-infection. In contrast, the NKG2A expression was increased in hepatic CD69-NK cells but not in CD69+NK cells. These results suggested that hepatic CD69+NK cells play a pivotal role in the pathogenesis of FHF by enhancing degranulation and cytotoxic ability of NK cells and increasing the production of pro-inflammatory cytokines.

SAT0045 In inflammatory arthritis, chemokine CCL19/21 expression is regulated by nuclear factor of activated T cells (NFATC4) pathways

BackgroundNuclear factors of activated T cells (NFAT) is a family of transcription factors critical in regulating genes expression in development and disease. The pathway is an important target for cyclosporine...

Synergistic Activation of Innate and Adaptive Immune Mechanisms in the Treatment of Gonadotropin-Sensitive Tumors

Human chorionic gonadotropin (hCG) prolongs the secretion of progesterone from the corpus luteum, providing a critical stimulus for the sustenance of pregnancy. hCG (or individual subunits) is also secreted by a variety of trophoblastic and non-trophoblastic cancers and has been associated with poor prognosis. Early clinical studies have indicated merit in anti-hCG vaccination as potential immunotherapy, but anti-tumor efficacy is believed to be compromised by sub-optimal immunogenecity. In the present study, enhanced tumorigenesis was observed when SP2/O cells were subcutaneously injected in either male or female BALB/c x FVB/JβhCG/- F1 transgenic mice, establishing the growth-promoting effects of the gonadotropin for implanted tumors in vivo. The utility of Mycobacterium indicus pranii (MIP) was evaluated, as an innate anti-tumor immunomodulator as well as adjuvant in mice. MIP elicited the secretion of the inflammatory cytokines IFNγ, IL-6, IL-12p40, KC and TNFα from murine antigen presenting cells. When MIP was incorporated into an anti-hCG vaccine formulation previously employed in humans (a βhCG-TT conjugate adsorbed on alum), elevated T cell recall proliferative and cytokine responses to hCG, βhCG and TT were observed. MIP increased vaccine immunogenicity in mice of diverse genetic background (including in traditionally low-responder murine strains), leading to enhanced titres of bioneutralizing anti-hCG antibodies which exhibited cytotoxicity towards tumor cells. Individual administration of MIP and βhCG-TT to BALB/c mice subcutaneously implanted with SP2/O cells resulted in anti-tumor effects; significantly, immunization with βhCG-TT supplemented with MIP invoked synergistic benefits in terms of tumor volume, incidence and survival. The development of novel vaccine formulations stimulating both adaptive and innate anti-tumor immunity to induce collaborative beneficial effects may fill a niche in the adjunct treatment of hCG-sensitive tumors that are resistant to conventional therapy.

Selective B-cell expression of the MHV-68 latency-associated M2 protein regulates T-dependent antibody response and inhibits apoptosis upon viral infection

To better understand the role of the M2 protein of the murine herpes virus strain 68 (MHV-68) in vivo, B-lymphocyte-restricted, M2-transgenic mice were constructed. The transgenic mice contained normal B-cell subpopulations in bone marrow, lymph nodes and spleen. After immunization with sheep red blood cells, spleens from M2-transgenic mice had increased germinal centres. Transgenic mice responded to the T-cell-dependent antigen keyhole limpet haemocyanin (KLH) with higher levels of secondary IgM and IgG2a antibodies than WT mice. Normal and M2-transgenic mice were infected with WT and M2 frame-shift mutant (M2FS) MHV-68 viruses. The pathogenesis of M2-transgenic mice infected with the M2-deficient mutant virus did not revert to that observed upon infection of normal mice with WT virus. However, the higher reactivation levels late after M2-transgenic mice were infected with WT virus reflected the importance of M2 as a target for the immune response, and thus with an impact on the establishment of latency. Finally, there was markedly less apoptosis in B-cells from M2-transgenic mice infected with either WT or M2FS mutant than from similarly infected WT mice, consistent with the published inhibitory influence of M2 on apoptosis in vitro. Thus, M2 provides a strategy to increase the pool of germinal centre B-cells through inhibition of apoptosis in the infected cell.

Prion infectivity in the spleen of a PRNP heterozygous individual with subclinical variant Creutzfeldt–Jakob disease

Blood transfusion has been identified as a source of human-to-human transmission of variant Creutzfeldt–Jakob disease. Three cases of variant Creutzfeldt–Jakob disease have been identified following red cell transfusions from donors who subsequently developed variant Creutzfeldt–Jakob disease and an asymptomatic red cell transfusion recipient, who did not die of variant Creutzfeldt–Jakob disease, has been identified with prion protein deposition in the spleen and a lymph node, but not the brain. This individual was heterozygous (MV) at codon 129 of the prion protein gene (PRNP), whereas all previous definite and probable cases of variant Creutzfeldt–Jakob disease have been methionine homozygotes (MM). A critical question for public health is whether the prion protein deposition reported in peripheral tissues from this MV individual correlates with infectivity. Additionally it is important to establish whether the PRNP codon 129 genotype has influenced the transmission characteristics of the infectious agent. Brain and spleen from the MV blood recipient were inoculated into murine strains that have consistently demonstrated transmission of the variant Creutzfeldt–Jakob disease agent. Mice were assessed for clinical and pathological signs of disease and transmission data were compared with other transmission studies in variant Creutzfeldt–Jakob disease, including those on the spleen and brain of the donor to the index case. Transmission of variant Creutzfeldt–Jakob disease was observed from the MV blood recipient spleen, but not from the brain, whereas there was transmission from both spleen and brain tissues from the red blood cell donor. Longer incubation times were observed for the blood donor spleen inoculum compared with the blood donor brain inoculum, suggesting lower titres of infectivity in the spleen. The distribution of vacuolar pathology and abnormal prion protein in infected mice were similar following inoculation with both donor and recipient spleen homogenates, providing initial evidence of similar transmission properties after propagation in PRNP codon 129 MV and MM individuals. These studies demonstrate that spleen tissue from a PRNP MV genotype individual can propagate the variant Creutzfeldt–Jakob disease agent and that the infectious agent can be present in the spleen without CNS involvement.

Regulation of basement membrane-reactive B cells in BXSB, (NZBxNZW)F1, NZB, and MRL/lpr lupus mice

Autoantibodies to diverse antigens escape regulation in systemic lupus erythematosus under the influence of a multitude of predisposing genes. To gain insight into the differential impact of diverse genetic backgrounds on tolerance mechanisms controlling autoantibody production in lupus, we established a single lupus-derived nephritis associated anti-basement membrane Ig transgene on each of four inbred murine lupus strains, including BXSB, (NZBxNZW)F1, NZB, and MRL/lpr, as approved by the Duke University and the Durham Veterans Affairs Medical Centers' Animal Care and Use Committees. In nonautoimmune C57BL/6 mice, B cells bearing this anti-laminin Ig transgene are stringently regulated by central deletion, editing, and anergy. Here, we show that tolerance is generally intact in unmanipulated Ig transgenic BXSB, (NZBxNZW)F1, and NZB mice, based on absence of serum transgenic anti-laminin autoantibodies and failure to recover spontaneous anti-laminin monoclonal antibodies. Four- to six-fold depletion of splenic B cells in transgenic mice of these strains, as well as in MRL/lpr transgenic mice, and reduced frequency of IgM+ bone marrow B cells suggest that central deletion is grossly intact. Nonetheless the 4 strains demonstrate distinct transgenic B cell phenotypes, including endotoxin-stimulated production of anti-laminin antibodies by B cells from transgenic NZB mice, and in vitro hyperproliferation of both endotoxin- and BCR-stimulated B cells from transgenic BXSB mice, which are shown to have an enrichment of CD21-high marginal zone cells. Rare anti-laminin transgenic B cells spontaneously escape tolerance in MRL/lpr mice. Further study of the mechanisms underlying these strain-specific B cell fates will provide insight into genetic modification of humoral autoimmunity in lupus.

Role of Calsequestrin and Sorcin in the Regulation of Cardiac Excitation Contraction Coupling: A Transcriptional and Physiological Study

In the heart, Ca2+ release through the Ryanodine Receptors (RyR2) is a high integrated process that can be regulated by several accessory proteins. Sorcin (SOR) and Calsequestrin (CSQ2) are two Ca2+ binding proteins that can interact with RyR2 modulating the kinetic properties of this channel. However, at the cellular level the molecular mechanism that underlies this possible regulation is still unclear. In order to address this question we implemented an integrated experimental approach to assess the hypothesis that SOR and CSQ2 regulate the SR Ca2+ release process under physiological conditions. Specifically, we generated transgenic mice by breeding SOR-/- and CSQ2-/- animals. A completed qPCR transcriptional study was carried out in the entire population in order to address if the mRNA levels for other genes were altered during the generation of the murine strains. Interestingly, we found that the mRNA's level for RyR2 and Phospholamban were significantly decreased in CSQ-/- animals. Additionally, subcellular Ca2+ dynamics were evaluated by measuring Ca2+ sparks, Ca2+ transients and restitution experiments in isolated myocytes by means of confocal microscopy under physiological temperatures. Animals in which SOR and CSQ2 genes were simultaneously ablated presented a dramatic increase in the time to peak of Ca2+ sparks (41.2±0.30 vs. 18.9±0.30 ms) and Ca2+ transients (37.8±0.09 vs. 19.5±0.12 ms). Moreover, the double ablation of SOR and CSQ2 significantly changed the refractoriness of Ca2+ release. Summarizing, the data presented here indicates that although the SOR-/- itself cannot produce any changes in excitation contraction coupling, in combination with the CSQ2-/- can promote significant changes in the Ca2+. However, most of the alterations observed in the double KOs’ were not significantly different than those observed for the CSQ2-/- itself. Supported by R01-HL-084487 to AE.

Metabonomic investigations of age- and batch-related variations in female NMRI mice using proton nuclear magnetic resonance spectroscopy

The NMRI outbred mouse model is widely used for studying metabolic disease, toxicity, and infection, yet information regarding baseline metabolism of this murine strain is relatively sparse. Using different batches of female NMRI mice, we assessed the stability of the metabolic phenotype with increasing age and weight, and determined the influence of acclimatization on the metabolic profile of biofluids (urine, plasma, and faecal water). Differences in urinary concentrations of 3-ureidopropionate, 2-oxoisocaproate, trimethylamine, and glycine were detected between three batches of 9-week-old female NMRI mice using proton nuclear magnetic resonance ((1)H NMR) spectroscopy coupled with multivariate statistical analysis. An acclimatization period of 2 weeks was imposed after the mice entered the laboratory environment. Strong differences in the faecal metabolome pre- and post-acclimatization were found (reduction in amino acid concentrations), whilst the urine metabolome showed increased levels of trimethylamine-N-oxide, phenylacetyl glycine, and hippurate with decreased excretion of formate and betaine post-acclimatization. Temporal variation in the metabolite profiles over a 16-week study stabilized around 7-week-old animals. The results from this study strongly argue for inclusion of an acclimatization period prior to starting an investigative procedure, and suggest that the metabolic phenotypes of female NMRI mice are more stable at around 7 weeks of age. We have also identified a set of metabolites that are more susceptible to variation in concentration. This information can serve as a benchmark in order to establish confidence in systematic variation attributable to pathology or therapeutic intervention above the background metabolic variation in the NMRI mouse.

Protective effect of Tranilast on radiation-induced heart fibrosis in C57BL/6 mouse

ABSTRACT The heart is a major dose ‐ limiting organ for radiotherapy of cancer in the thoracic region. The purpose of this study was to examine the protective effect of tranilast on the radiation ‐ induced heart fibrosis model using the C57BL/6 murine strain. A significant reduction in the expression of TGF ‐β 1, collagen type Ⅰ and collagen type Ⅲ was observed in the radiation plus tranilast group. The authors also suggest the use of tranilast in a clinical trial for the prevention of radiation-induced heart fibrosis. Keywords : Heart Fibrosis, Radiation, Tranilast 1. INTRODUCTION interplay of cellular and mole 1.1 General Appearance The cardiac structures (heart and pericardium) are recognized as being sufficiently radiosensitive to be dose‐limiting structures during radiotherapy for cancers in the thoracic region. The term heart (RIHD) was coined in the 1960s [1],[2] and describes the conglomerate of structural alterations produced by radiation of the cardiac tissues and the clinical manifestations of these alterations RIHD may vary depending on the total dose of radiation administered, the fractionation schedule, the volume of the heart radiated, the existence of prior heart disease, and the use of chemotherapeutic medications in the management of the disease. Clinically evident RIHD has a characteristic morphology. The most common morphologic alterations occur in the pericardium [3]. The parietal pericardium develops variable degrees of fibrosis that replace the outer adipose tissue. The visceral pericardium also develops fibrosis, although not to the same degree as the parietal pericardium. The myocardium is involved less frequently than the pericardium, but it develops a more serious lesion [3],[4]. The valvular lesions induced by radiation are nonspecific and could be the result of conditions other than RIHD. The morphology of coronary artery disease after radiation is not different from that of spontaneous atherosclerosis. Therefore, these lesions cannot be diagnosed as specifically associated with radiation therapy. The underlying mechanisms of radiation‐induced fibrosis remain unresolved. Based on our present knowledge of

Association Analysis Reveals Genetic Variation Altering Bleomycin-Induced Pulmonary Fibrosis in Mice

Pulmonary fibrosis is a disease of significant morbidity, with an incompletely defined genetic basis. Here, we combine linkage and association studies to identify genetic variations associated with pulmonary fibrosis in mice. Mice were treated with bleomycin by osmotic minipump, and pulmonary fibrosis was histologically assessed 6 weeks later. Fibrosis was mapped in C57BL6/J (fibrosis-susceptible) × A/J (fibrosis-resistant) F2 mice, and the major identified linkage intervals were evaluated in consomic mice. Genome-wide and linkage-interval genes were assessed for their association with fibrosis, using phenotypic data from 23 inbred strains and the murine single-nucleotide polymorphism map. Susceptibility to pulmonary fibrosis mapped to a locus on chromosome 17, which was verified with consomic mice, and to three additional suggestive loci that may interact with alleles on chromosome 17 to affect the trait in F2 mice. Two of the loci, including the region on chromosome 17, are homologous to previously mapped loci of human idiopathic fibrosis. Of the 23 phenotyped murine strains, four developed significant fibrosis, and the majority presented minimal disease. Genome-wide and linkage region-specific association studies revealed 11 pulmonary expressed genes (including the autophagy gene Cep55, and Masp2, which is a complement component) to contain polymorphisms significantly associated with bleomycin-induced fibrotic lung disease. In conclusion, genomic approaches were used to identify linkage intervals and specific genetic variations associated with pulmonary fibrosis in mice. The common loci and similarities in phenotype suggest these findings to be of relevance to clinical pulmonary fibrosis.

Probing the Relationship Between Insulin Sensitivity and Longevity Using Genetically Modified Mice

Interference in insulin and/or insulin-like growth factor 1 (IGF-1) signaling can extend invertebrate life span, and interference in IGF-1 signaling can extend murine life span. Whether interference with murine insulin signaling, which can be diabetogenic and pathological, is also life-extending is controversial. We therefore measured life span in 3 murine strains genetically modified to reduce or increase insulin sensitivity. Mice with reduced insulin sensitivity were hemizygous for a null mutation in the insulin receptor (insulin receptor knockout mice; IRKO(+/-)). Mice with increased insulin sensitivity either had a null mutation of protein tyrosine phosphatase 1B (PTP-1B(-/-)) or overexpressed Peroxisome proliferator-activated receptor-α coactivator (PGC)-1α (PGC-1α(TG)). Life span of insulin insensitive IRKO(+/) mice was increased (males) or unaffected (females). Life spans of mice with increased insulin sensitivity were shortened overall (PTP-1B(-/-) mice) or partially (PGC-1α(TG): survival at the 25th percentile was reduced). These results show that insulin sensitivity in some murine genotypes is inversely related to longevity and provide further evidence for evolutionary conservation of this pathway as a modulator of longevity.

CD4–CD8-T cells contribute to the persistence of viral hepatitis by striking a delicate balance in immune modulation

Viral hepatitis remains the most common cause of liver disease and a major public health problem. Here, we focus on the role of CD4 CD8 double negative T (DN T) cells involved in the mechanisms of viral persistence in hepatitis. C3H/HeJ mice infected with murine hepatitis virus strain 3 (MHV-3) were used to display chronic viral hepatitis. DN T cells dramatically increased in MHV-3 infected mice. Adoptive transfer of DN T cells from MHV-3 infected mice led to a significant increase in mice survival. The DN T cells with production of IFN-γ and IL-2 are able to kill virus-specific CD8+ T cells via the Fas/FasL dependent pathway. The delicate balance of multiple effects of DN T cells may lead to viral persistence in MHV-3 induced hepatitis. In short, our study identified DN T cells contributing to viral persistence in MHV-3 induced hepatitis in C3H/HeJ mice, which provides a rationale for modulating DN T cells for the management of viral hepatitis.

The Antimicrobial Peptide Cathelicidin Protects Mice from Escherichia coli O157:H7-Mediated Disease

This study investigated the role of the antimicrobial peptide cathelicidin in Escherichia coli O157:H7 infection and subsequent renal damage. Mouse and human cathelicidin, CRAMP and LL-37, respectively, killed E. coli O157:H7 in vitro. Intestines from healthy wild-type (129/SvJ) and cathelicidin-knock-out (Camp−/−) mice were investigated, showing that cathelicidin-deficient mice had a thinner colonic mucus layer compared with wild-type mice. Wild-type (n = 11) and cathelicidin-knock-out (n = 11) mice were inoculated with E. coli O157:H7. Cathelicidin-deficient animals exhibited higher fecal counts of E. coli O157:H7 and bacteria penetrated the mucus forming attaching-and-effacing lesions to a much higher extent than in wild-type animals. Cathelicidin knock-out mice developed symptoms (9/11) as well as anemia, thrombocytopenia and extensive renal tubular damage while all cathelicidin-producing mice remained asymptomatic with normal laboratory findings. When injected with Shiga toxin intraperitoneally, both murine strains developed the same degree of renal tubular damage and clinical disease indicating that differences in sensitivity to infection between the murine strains were related to the initial intestinal response. In conclusion, cathelicidin substantially influenced the antimicrobial barrier in the mouse colon mucosa. Cathelicidin deficiency lead to increased susceptibility to E. coli O157:H7 infection and subsequent renal damage. Administration of cathelicidin or stimulation of endogenous production may prove to be novel treatments for E. coli O157:H7-induced hemolytic uremic syndrome.