Function In Mouse Model Research Articles

Histamine receptor 2 blockade reduces breast tumor development and metastasis (TUM9P.1010)

Abstract Histamine has multiple immunomodulatory roles that impact innate and acquired immunity. Histamine receptor antagonists are widely used clinically to treat allergic disease and gastrointestinal disorders, but their ability to alter effective immune function to breast tumors is unknown. We hypothesized that histamine receptor antagonist treatment could alter immune function in mouse models of breast cancer, therefore altering the growth and spread of breast cancer. Two injectable breast tumor models (the 4T1-BALB/c and E0771-C57BL/6 model) and a spontaneous breast cancer model (STK-/-/NIC model) were utilized. Histamine receptor antagonists were administered in the drinking water prior to tumor cell injection or at time of weaning, respectively. The immune cell populations in the spleen and bone marrow of tumor-bearing mice were analyzed. Ranitidine and famotidine (Hrh2 antagonists) but not selective Hrh1 or Hrh4 antagonists significantly inhibited metastasis in the 4T1 model. Ranitidine treatment also caused significant primary tumor regression in the E0771 breast cancer model. In the STK-/-/NIC model, ranitidine increased latency and decreased the number of tumors per mouse at week 26. Bone marrow and spleen analysis revealed that oral ranitidine treatment significantly and selectively decreased monocyte populations. These studies suggest that HRH2 antagonists may have potential as a beneficial immunomodulatory agent in the prevention or treatment of breast cancer.

Combined treatment with atorvastatin and imipenem improves survival and vascular functions in mouse model of sepsis

We have recently reported that pre-treatment, but not the post-treatment with atorvastatin showed survival benefit and improved hemodynamic functions in cecal ligation and puncture (CLP) model of sepsis in mice. Here we examined whether combined treatment with atorvastatin and imipenem after onset of sepsis can prolong survival and improve vascular functions. At 6 and 18h after sepsis induction, treatment with atorvastatin plus imipenem, atorvastatin or imipenem alone or placebo was initiated. Ex vivo experiments were done on mouse aorta to examine the vascular reactivity to nor-adrenaline and acetylcholine and mRNA expressions of α1D AR, GRK2 and eNOS. Atorvastatin plus imipenem extended the survival time to 56.00±4.62h from 20.00±1.66h observed in CLP mice. The survival time with atorvastatin or imipenem alone was 20.50±1.89h and 27.00±4.09h, respectively. The combined treatment reversed the hyporeactivity to nor-adrenaline through preservation of α1D AR mRNA/protein expression and reversal of α1D AR desensitization mediated by GRK2/Gβγ pathway. The treatment also restored endothelium-dependent relaxation to ACh through restoration of aortic eNOS mRNA expression and NO availability. In conclusion, combined treatment with atorvastatin and imipenem exhibited survival benefit and improved vascular functions in septic mice.

Opposite phenotypes of muscle strength and locomotor function in mouse models of partial trisomy and monosomy 21 for the proximal Hspa13-App region.

The trisomy of human chromosome 21 (Hsa21), which causes Down syndrome (DS), is the most common viable human aneuploidy. In contrast to trisomy, the complete monosomy (M21) of Hsa21 is lethal, and only partial monosomy or mosaic monosomy of Hsa21 is seen. Both conditions lead to variable physiological abnormalities with constant intellectual disability, locomotor deficits, and altered muscle tone. To search for dosage-sensitive genes involved in DS and M21 phenotypes, we created two new mouse models: the Ts3Yah carrying a tandem duplication and the Ms3Yah carrying a deletion of the Hspa13-App interval syntenic with 21q11.2-q21.3. Here we report that the trisomy and the monosomy of this region alter locomotion, muscle strength, mass, and energetic balance. The expression profiling of skeletal muscles revealed global changes in the regulation of genes implicated in energetic metabolism, mitochondrial activity, and biogenesis. These genes are downregulated in Ts3Yah mice and upregulated in Ms3Yah mice. The shift in skeletal muscle metabolism correlates with a change in mitochondrial proliferation without an alteration in the respiratory function. However, the reactive oxygen species (ROS) production from mitochondrial complex I decreased in Ms3Yah mice, while the membrane permeability of Ts3Yah mitochondria slightly increased. Thus, we demonstrated how the Hspa13-App interval controls metabolic and mitochondrial phenotypes in muscles certainly as a consequence of change in dose of Gabpa, Nrip1, and Atp5j. Our results indicate that the copy number variation in the Hspa13-App region has a peripheral impact on locomotor activity by altering muscle function.

The Effects of Unpredictable Stress on the LHR Expression and Reproductive Functions in Mouse Models

Sung-Young Choi, Jin-Heum Park, Yuxia Zhu, Young-Jong kim, Jae-Ok Park, Changjong Moon, Taekyun Shin, Meejung Ahn, Suk-Soo Kim, Young-Sik Park, Hyung-Bok Chae, Tae-Kyun Kim and Seung-Joon Kim. J Vet Clin 2014;31:394-402. https://doi.org/10.17555/ksvc.2014.10.31.5.394

Assessment of ventricular function in mouse models of muscular dystrophy: A comparison of MRI with conductance catheter

Outcomes of clinical trials depend on the quality of preceding preclinical research, yet functional assays and outcome measures for mouse models of disease are often poorly standardized or inappropriate. Muscular dystrophies are associated with cardiomyopathy so preclinical research requires reliable measures of cardiac function in animal models of the disease. MRI and conductance catheter were compared as preclinical tools to detect cardiomyopathy in two mouse models of muscular dystrophy. Sgcd−/−, mdx and C57Bl10 mice (n = 7/group) were assessed by catheter following MRI at an early stage of cardiomyopathy. Volumetric measurements were higher from MRI compared to catheter. In particular, by catheter, the measurement of end-systolic volume (and its related measures) was disproportionately lower in dystrophic mice compared to controls. This was related to greater calculated parallel conductance in dystrophic mice. Catheter highlighted differences in pressure generation between the two models while MRI detected differences in left ventricular hypertrophy and right ventricular function. Although MRI and conductance catheter provide unique but complimentary information regarding the nature of cardiomyopathy in dystrophic mice, we present the possibility that pathology itself may affect the accuracy of the catheter technique and that particular caution must be taken when interpreting catheter volume data in dystrophic mice.

Impact of mineralocorticoid receptor blockade on vascular function in atherosclerotic mouse models under high-fat diet

Objectives: Endothelial dysfunction is an important step in the pathogenesis of atherosclerosis. One risk factor of endothelial dysfunction is consumption of high amounts of saturated fat. Recent studies reveal an endothelium-protective effect of blockade of the aldosterone-binding mineralocorticoid receptor (MR). In this study, we analysed the effects of high-fat diet (HFD) and MR-blockade on metabolic parameters and endothelial function in mouse models of atherosclerosis.

Laminin-111 improves skeletal muscle stem cell quantity and function following eccentric exercise.

Laminin-111 (α1, β1, γ1; LM-111) is an important component of the extracellular matrix that is required for formation of skeletal muscle during embryonic development. Recent studies suggest that LM-111 supplementation can enhance satellite cell proliferation and muscle function in mouse models of muscular dystrophy. The purpose of this study was to determine the extent to which LM-111 can alter satellite and nonsatellite stem cell quantity following eccentric exercise-induced damage in young adult, healthy mice. One week following injection of LM-111 or saline, mice either remained sedentary or were subjected to a single bout of downhill running (EX). While one muscle was preserved for evaluation of satellite cell number, the other muscle was processed for isolation of mesenchymal stem cells (MSCs; Sca-1+CD45-) via FACS at 24 hours postexercise. Satellite cell number was approximately twofold higher in LM-111/EX compared with all other groups (p<.05), and the number of satellite cells expressing the proliferation marker Ki67 was 50% to threefold higher in LM-111/EX compared with all other groups (p<.05). LM-111 also increased the quantity of embryonic myosin heavy chain-positive (eMHC+) fibers in young mice after eccentric exercise (p<.05). Although MSC percentage and number were not altered, MSC proinflammatory gene expression was decreased, and hepatocyte growth factor gene expression was increased in the presence of LM-111 (p<.05). Together, these data suggest that LM-111 supplementation provides a viable solution for increasing skeletal muscle stem cell number and/or function, ultimately allowing for improvements in the regenerative response to eccentric exercise.

Sildenafil does not improve cardiomyopathy in Duchenne/Becker muscular dystrophy.

Duchenne and Becker muscular dystrophies (DBMD) are allelic disorders caused by mutations in dystrophin. Adults with DBMD develop life-threatening cardiomyopathy. Inhibition of phosphodiesterase 5 (PDE5) improves cardiac function in mouse models of DBMD. To determine whether the PDE5-inhibitor sildenafil benefits human dystrophinopathy, we conducted a randomized, double-blind, placebo-controlled trial (ClinicalTrials.gov, number NCT01168908). Adults with DBMD and cardiomyopathy (ejection fraction ≤ 50%) were randomized to receive sildenafil (20mg 3× daily) or placebo for 6 months. All subjects received an additional 6 months of open-label sildenafil. The primary endpoint was change in left ventricular end-systolic volume (LVESV) on cardiac magnetic resonance imaging. Secondary cardiac endpoints, skeletal muscle function, and quality of life were also assessed. An interim analysis (performed after 15 subjects completed the blinded phase) revealed that 29% (4 of 14) of subjects had a ≥10% increase in LVESV after 6 months of sildenafil compared to 13% (1 of 8) of subjects receiving placebo. Subjects with LVESV > 120ml at baseline were more likely to worsen at 12 months regardless of treatment assignment (p = 0.035). Due to the higher number of subjects worsening on sildenafil, the data and safety monitoring board recommended early termination of the study. There were no statistically significant differences in outcome measures between treatment arms. Due to the small sample size, comparisons between groups must be interpreted with caution. However, this trial suggests that sildenafil is unlikely to improve cardiac function in adults with DBMD.

Levels of liver X receptors in testicular biopsies of patients with azoospermia

To determine whether the transcription factors liver X receptors (LXRs) and their downstream genes, which are involved in the regulation of several testicular functions in mouse models, are differentially expressed in testes of men with nonobstructive azoospermia (NOA) or obstructive azoospermia (OA). Prospective study. University hospital. Patients with various types of NOA (n=22) and with OA (n=5). Human testicular biopsies. Transcript levels were measured in testicular biopsies with the use of quantitative polymerase chain reaction. Correlations of LXR mRNA levels with the number of germ cells, the expression of proliferation and apoptosis markers, and the amount of intratesticular lipids and testosterone were evaluated. The localization of LXRα was analyzed by immunofluorescence. LXR mRNA levels were decreased by 49%-98% in NOA specimens and positively correlated with germ cell number. Accumulations of IDOL and SREBP1c (LXR targets involved in lipid homeostasis) were 1.8-2.1 times lower in NOA samples and mRNA levels of the SREBP1c target gene ELOVL6 were increased 1.9-2.4-fold. Interestingly, the amount of triglycerides and free fatty acids were higher in NOA testes (3.4-12.2-fold). LXRα was present in Leydig cells. Accumulations of LXR downstream genes encoding the steroidogenic proteins StAR and 3βHSD2 were higher in NOA testes (5.9-12.8-fold). Knowledge of changes in the transcript levels of LXRs and some of their downstream genes during altered spermatogenesis may help us to better understand the physiopathology of testicular failure in azoospermic patients.

In vivo endothelial siRNA delivery using polymeric nanoparticles with low molecular weight.

Dysfunctional endothelium contributes to more diseases than any other tissue in the body. Small interfering RNAs (siRNAs) can help in the study and treatment of endothelial cells in vivo by durably silencing multiple genes simultaneously, but efficient siRNA delivery has so far remained challenging. Here, we show that polymeric nanoparticles made of low-molecular-weight polyamines and lipids can deliver siRNA to endothelial cells with high efficiency, thereby facilitating the simultaneous silencing of multiple endothelial genes in vivo. Unlike lipid or lipid-like nanoparticles, this formulation does not significantly reduce gene expression in hepatocytes or immune cells even at the dosage necessary for endothelial gene silencing. These nanoparticles mediate the most durable non-liver silencing reported so far and facilitate the delivery of siRNAs that modify endothelial function in mouse models of vascular permeability, emphysema, primary tumour growth and metastasis.

Phenotypic and functional characterization of neutrophils from lupus-prone mice (BA4P.223)

Abstract Neutrophils constitute a critical component of cellular immunity that eliminate infectious organisms through oxidative burst, phagocytosis and the formation of neutrophil extracellular traps (NETs). Recently it has been reported that neutrophils contribute to autoimmunity through NET formation and interactions with auto-reactive immune cells. Our goal is to characterize phenotypic and functional properties of neutrophils in mouse models of systemic lupus (SLE) to determine if and how neutrophil dysregulation occurs. Using flow cytometry we have measured neutrophil populations in healthy control and diseased SLE mouse models. We found neutrophils are consistently increased in the spleen of MRL-Faslpr, C57BL/6-Faslpr and NZBWF1 lupus mice compared to controls. Further characterization of neutrophil functions including phagocytosis, reactive oxygen production, NET formation, protease activity and histone citrullination indicate increased DNA release, increased citrullination and alterations in serine protease activity in lupus neutrophils. Differences in the results between the NZBWF1 and MRL-Faslpr models suggest the background genetics play a role in neutrophil dysregulation in these two models. Ultimately we hope to understand the cause of altered neutrophil function in mouse models of SLE, whether they contribute to lupus disease progression, and hopefully develop newer targeted therapies for lupus.

Adoptive transfer method to study platelet function in mouse models of disease

Platelets play an important role in many physiological and pathological situations. However, the molecular mechanisms by which platelets contribute to health and disease are often ill-defined. One of the limiting factors to these studies is a fast but reliable method to generate animals with platelet-specific signaling defects. We here review recent approaches to establish an adoptive platelet transfer model in mice.

Bexarotene reduces network excitability in models of Alzheimer's disease and epilepsy

The nuclear retinoid X receptor agonist, bexarotene, has been implicated in recovery of cognitive function in mouse models of Alzheimer's disease (AD). Since AD genetic mouse models also show abnormal neural hyperexcitability, which may play a destructive role in memory storage and retrieval, we studied whether bexarotene exerted dynamic network effects on electroencephalography cortical spike discharge rate and spectral frequency in an AD (hAPP J20 model) and non-AD (Kv1.1 null) mouse models of epilepsy. We find that oral treatment with bexarotene over 1 week acutely reduced spike discharges in both models and seizures in the Kv1.1 null mouse model without major alterations in the background frequency of brain rhythms. The effect was reversible and exhibited a similar rapid onset in hippocampal slices. While the exact mechanisms are unknown, bexarotene counteracts both amyloid-β-induced and amyloid-β-independent increases in cortical network hyperexcitability.

0331: Left ventricular systolic function assessment in a mouse model of cardiac hypertrophy using an 11.7T MRI scanner and comparison with ex-vivo measurements

In cardiovascular research, there has recently been an interest in ultra-high field MRI to characterize cardiac anatomy and function in rodents. However, reports on the accuracy of the method are scarce. The purpose of our work was to evaluate left ventricular (LV) systolic function in a mouse model of cardiac hypertrophy using an 11.7T MRI machine and to assess the validity of our results by comparing them with ex vivo measurements. 24 C57Bl/6J mice were studied, including 11 animals having undergone a surgical transverse aortic constriction (TAC) and 13 sham animals. Imaging was performed on a 11.7 Tesla Bruker MR scanner. The LV systolic function was assessed from a stack of 1mm thick short-axis views obtained with a FLASH-cine sequence covering the entire ventricles. Using a dedicated software (SegmentTM, Medviso, Sweden), the following volumes (μl) were determined: end-diastolic, end-systolic and stroke volumes. LV ejection fraction (in %) and LV mass (mg) were subsequently deduced. One week after, mice were sacrificed and their LV mass and tibial length (TL) were measured. As expected, LV mass was significantly higher in the TAC group. When using the previously validated LV mass/tibial length ratio (LV/TL), sham mice showed a ratio of 4.65±0.09 mg/mm and 3.83±0.11 mg/mm for morphometric and MRI measurements respectively, and TAC mice showed a ratio of 6.50±0.40 and 5.39±0.28 respectively (p<0.05). Systolic dysfunction was highlighted in the TAC group, with a reduced LVEF of 40,64±4,37% (p<0.05). We demonstrated an excellent correlation between LV mass measurements by weighing or imaging, with a Pearson correlation (r) of 0.92 for both LV mass and LV/TL ratio (p<0.05, Fig.). High-field cardiac MRI is a promising tool to assess and follow LV systolic function and hypertrophy in mouse models of cardiovascular diseases. In this study, compared with ex vivo measurements, MRI showed similar differences between our experimental groups. Abstract 0331 – Figure

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Assessment of Right Ventricular Structure and Function in Mouse Model of Pulmonary Artery Constriction by Transthoracic Echocardiography

Emerging clinical data support the notion that RV dysfunction is critical to the pathogenesis of cardiovascular disease and heart failure(1-3). Moreover, the RV is significantly affected in pulmonary diseases such as pulmonary artery hypertension (PAH). In addition, the RV is remarkably sensitive to cardiac pathologies, including left ventricular (LV) dysfunction, valvular disease or RV infarction(4). To understand the role of RV in the pathogenesis of cardiac diseases, a reliable and noninvasive method to access the RV structurally and functionally is essential. A noninvasive trans-thoracic echocardiography (TTE) based methodology was established and validated for monitoring dynamic changes in RV structure and function in adult mice. To impose RV stress, we employed a surgical model of pulmonary artery constriction (PAC) and measured the RV response over a 7-day period using a high-frequency ultrasound microimaging system. Sham operated mice were used as controls. Images were acquired in lightly anesthetized mice at baseline (before surgery), day 0 (immediately post-surgery), day 3, and day 7 (post-surgery). Data was analyzed offline using software. Several acoustic windows (B, M, and Color Doppler modes), which can be consistently obtained in mice, allowed for reliable and reproducible measurement of RV structure (including RV wall thickness, end-diastolic and end-systolic dimensions), and function (fractional area change, fractional shortening, PA peak velocity, and peak pressure gradient) in normal mice and following PAC. Using this method, the pressure-gradient resulting from PAC was accurately measured in real-time using Color Doppler mode and was comparable to direct pressure measurements performed with a Millar high-fidelity microtip catheter. Taken together, these data demonstrate that RV measurements obtained from various complimentary views using echocardiography are reliable, reproducible and can provide insights regarding RV structure and function. This method will enable a better understanding of the role of RV cardiac dysfunction.

Adoptive transfer method to study platelet function in mouse models of disease

Adoptive transfer method to study platelet function in mouse models of disease

Lipopolysaccharide-induced cross-tolerance against renal ischemia–reperfusion injury is mediated by hypoxia-inducible factor-2α-regulated nitric oxide production

Although the protective effect of lipopolysaccharide (LPS) pretreatment on renal ischemia/reperfusion injury is known, a link to hypoxia-inducible factors (HIFs) has not been established. Here we show that LPS treatment led to HIF-2α accumulation in mouse kidneys and endothelial cells, a result of nuclear factor-κB activation. Inactivation of HIF-2α, rather than HIF-1α, completely negated LPS-mediated protection against renal ischemia/reperfusion injury. LPS-stimulated renoprotection was related to inducible/endothelial nitric oxide synthase (iNOS/eNOS) expression, increased production of nitric oxide, and enhanced postischemic microcirculatory recovery. All these effects were lost in HIF-2α knockout mice. Preischemic administration of a nitric oxide donor, rather than erythropoietin, restored the lost preconditioning effect of LPS in HIF-2α knockout mice. In vitro and in vivo studies demonstrated that HIF-2α in endothelial cells, rather than myeloid cells or hepatocytes, was responsible for the LPS-mediated effects. Thus, our results demonstrated that LPS preconditioning protected against renal ischemia/reperfusion injury by HIF-2α activation in endothelial cells that subsequently improved renal microvascular perfusion and reduced ischemic tubular damage.

A tetra(ethylene glycol) derivative of benzothiazole aniline ameliorates dendritic spine density and cognitive function in a mouse model of Alzheimer's disease

We recently reported that the tetra(ethylene glycol) derivative of benzothiazole aniline, BTA-EG4, acts as an amyloid-binding small molecule that promotes dendritic spine density and cognitive function in wild-type mice. This raised the possibility that BTA-EG4 may benefit the functional decline seen in Alzheimer's disease (AD). In the present study, we directly tested whether BTA-EG4 improves dendritic spine density and cognitive function in a well-established mouse model of AD carrying mutations in APP, PS1 and tau (APPswe;PS1M146V;tauP301L, 3xTg AD mice). We found that daily injections of BTA-EG4 for 2weeks improved dendritic spine density and cognitive function of 3xTg AD mice in an age-dependent manner. Specifically, BTA-EG4 promoted both dendritic spine density and morphology alterations in cortical layers II/III and in the hippocampus at 6–10months of age compared to vehicle-injected mice. However, at 13–16months of age, only cortical spine density was improved without changes in spine morphology. The changes in dendritic spine density correlated with Ras activity, such that 6–10month old BTA-EG4 injected 3xTg AD mice had increased Ras activity in the cortex and hippocampus, while 13–16month old mice only trended toward an increase in Ras activity in the cortex. Finally, BTA-EG4 injected 3xTg AD mice at 6–10months of age showed improved learning and memory; however, only minimal improvement was observed at 13–16months of age. This behavioral improvement corresponds to a decrease in soluble Aβ 40 levels. Taken together, these findings suggest that BTA-EG4 may be beneficial in ameliorating the synaptic loss seen in early AD.

Beneficial Effects of Schisandrin B on the Cardiac Function in Mice Model of Myocardial Infarction

The fruit of Schisandra chinensis has been used in the traditional Chinese medicine for thousands of years. Accumulating evidence suggests that Schisandrin B (Sch B) has cardioprotection effect on myocardial ischemia in vitro. However, it is unclear whether Sch B has beneficial effects on continuous myocardial ischemia in vivo. The aim of the present study was to investigate whether Sch B could improve cardiac function and attenuate myocardial remodeling after myocardial infarction (MI) in mice. Mice model of MI was established by permanent ligation of the left anterior descending (LAD) coronary artery. Then the MI mice were randomly treated with Sch B or vehicle alone. After treatment for 3 weeks, Sch B could increase survival rate, improve heart function and decrease infarct size compared with vehicle. Moreover, Sch B could down-regulate some inflammatory cytokines, activate eNOS pathway, inhibit cell apoptosis, and enhance cell proliferation. Further in vitro study on H9c2 cells showed similar effects of Sch B on prevention of hypoxia-induced inflammation and cell apoptosis. Taken together, our results demonstrate that Sch B can reduce inflammation, inhibit apoptosis, and improve cardiac function after ischemic injury. It represents a potential novel therapeutic approach for treatment of ischemic heart disease.