Function In Mouse Model Research Articles

Active immunization with the peptide epitope vaccine Aβ3-10-KLH induces a Th2-polarized anti-Aβ antibody response and decreases amyloid plaques in APP/PS1 transgenic mice

Active amyloid-β (Aβ) immunotherapy is effective in preventing Aβ deposition, facilitating plaque clearance, and improving cognitive functions in mouse models of Alzheimer's disease (AD). Developing a safe and effective AD vaccine requires a delicate balance between inducing adequate humoral immune responses and avoiding T cell-mediated autoimmune responses. In this study, we designed 2 peptide epitope vaccines, Aβ3-10-KLH and 5Aβ3-10, prepared respectively by coupling Aβ3-10 to the immunogenic carrier protein keyhole limpet hemocyanin (KLH) or by joining 5 Aβ3-10 epitopes linearly in tandem. Young APP/PS1 mice were immunized subcutaneously with Aβ3-10-KLH or 5Aβ3-10 mixed with Freund's adjuvant, and the immunopotencies of these Aβ3-10 peptide vaccines were tested. Aβ3-10-KLH elicited a robust Th2-polarized anti-Aβ antibody response and inhibited Aβ deposition in APP/PS1 mice. However, 5Aβ3-10 did not induce an effective humoral immune response. These results indicated that Aβ3-10-KLH may be a safe and efficient vaccine for AD and that conjugating the antigen to a carrier protein may be more effective than linking multiple peptide antigens in tandem in applications for antibody production and vaccine preparation.

Bone marrow transplantations to study gene function in hematopoietic cells.

Immune cells are derived from hematopoietic stem cells in the bone marrow. Experimental replacement of bone marrow offers the unique possibility to replace immune cells, to study gene function in mouse models of disease. Over the past decades, this technique has been used extensively to study, for instance, macrophage function in atherosclerosis. In this chapter, we describe the methods for both full bone marrow transplantations and T cell-specific transfers.

Assessment of Cardiac Morphological and Functional Changes in Mouse Model of Transverse Aortic Constriction by Echocardiographic Imaging.

Transverse aortic constriction (TAC) in mice has been used as a valuable model to study mechanisms of cardiac hypertrophy and heart failure(1). A reliable noninvasive method is essential to assess real-time cardiac morphological and functional changes in animal models of heart disease. Transthoracic echocardiography represents an important tool for noninvasive assessment of cardiac structure and function(2). Here we used a high-resolution ultrasound imaging system to monitor myocardial remodeling and heart failure progression over time in a mouse model of TAC. B-mode, M-mode, and Doppler imaging were used to precisely assess cardiac hypertrophy, ventricular dilatation, and functional deterioration in mice following TAC. Color and pulse wave (PW) Doppler imaging was used to noninvasively measure pressure gradient across the aortic constriction created by TAC and to assess transmitral blood flow in mice. Thus transthoracic echocardiographic imaging provides comprehensive noninvasive measurements of cardiac dimensions and function in mouse models of heart disease.

DYRK1A, a Dosage-Sensitive Gene Involved in Neurodevelopmental Disorders, Is a Target for Drug Development in Down Syndrome.

Down syndrome (DS) is one of the leading causes of intellectual disability, and patients with DS face various health issues, including learning and memory deficits, congenital heart disease, Alzheimer’s disease (AD), leukemia, and cancer, leading to huge medical and social costs. Remarkable advances on DS research have been made in improving cognitive function in mouse models for future therapeutic approaches in patients. Among the different approaches, DYRK1A inhibitors have emerged as promising therapeutics to reduce DS cognitive deficits. DYRK1A is a dual-specificity kinase that is overexpressed in DS and plays a key role in neurogenesis, outgrowth of axons and dendrites, neuronal trafficking and aging. Its pivotal role in the DS phenotype makes it a prime target for the development of therapeutics. Recently, disruption of DYRK1A has been found in Autosomal Dominant Mental Retardation 7 (MRD7), resulting in severe mental deficiency. Recent advances in the development of kinase inhibitors are expected, in the near future, to remove DS from the list of incurable diseases, providing certain conditions such as drug dosage and correct timing for the optimum long-term treatment. In addition the exact molecular and cellular mechanisms that are targeted by the inhibition of DYRK1A are still to be discovered.

Modified Bfat-1 gene and its biological verification in mice by hydrodynamic tail vein injection

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are essential components required for normal cellular function and have been shown to have important therapeutic and nutritional benefits in humans. But humans or mammals cannot naturally produce ω-3 PUFAs, due to the lack of the ω-3 fatty acid desaturase gene (fat-1 gene). Previously, fat-1 gene has been cloned from Caenorhabditis elegans and transferred into mice, pigs and sheep, but not yet into beef cattle. We attempt to transfer it into beef cattle. The object of this paper is to edit the fat-1 gene from C. elegans to express more efficiently in beef cattle and verify its biological function in mice model. As a result, the fat-1 gene from C. elegans was modified by synonymous codon usage and named it Bfat-1. We have demonstrated that degree of codon bias of Bfat-1 gene was increased in beef cattle. Moreover, Bfat-1 gene could be transiently expressed in mouse liver and muscle, the ω-6/ω-3 PUFAs ratio of 18 and 20 carbon was decreased significantly in liver (P<0.05), and the ratio of 20 carbon decreased significantly in muscle 24 and 72 h after injection (P<0.05). This confirms that the Bfat-1 gene modification was successful, and the protein encoded was able to catalyze the conversion of ω-6 PUFAs to ω-3 PUFAs.

Aging and Autophagy in the Heart.

The aging population is increasing in developed countries. Because the incidence of cardiac disease increases dramatically with age, it is important to understand the molecular mechanisms through which the heart becomes either more or less susceptible to stress. Cardiac aging is characterized by the presence of hypertrophy, fibrosis, and accumulation of misfolded proteins and dysfunctional mitochondria. Macroautophagy (hereafter referred to as autophagy) is a lysosome-dependent bulk degradation mechanism that is essential for intracellular protein and organelle quality control. Autophagy and autophagic flux are generally decreased in aging hearts, and murine autophagy loss-of-function models develop exacerbated cardiac dysfunction that is accompanied by the accumulation of misfolded proteins and dysfunctional organelles. On the contrary, stimulation of autophagy generally improves cardiac function in mouse models of protein aggregation by removing accumulated misfolded proteins, dysfunctional mitochondria, and damaged DNA, thereby improving the overall cellular environment and alleviating aging-associated pathology in the heart. Increasing lines of evidence suggest that autophagy is required for many mechanisms that mediate lifespan extension, such as caloric restriction, in various organisms. These results raise the exciting possibility that autophagy may play an important role in combating the adverse effects of aging in the heart. In this review, we discuss the role of autophagy in the heart during aging, how autophagy alleviates age-dependent changes in the heart, and how the level of autophagy in the aging heart can be restored.

Neuroprotective and Cognition-Enhancing Effects of Compound K Isolated from Red Ginseng.

The present study was aimed at elucidating the effect of compound K derived from red ginseng on memory function in mouse model and glutamate-induced cytotoxicity in mouse hippocampal HT22 cells. Compound K induced antioxidant enzymes in nuclear factor (erythroid-derived 2)-like 2 (Nrf2)-mediated manner, and effectively attenuated cytotoxicity and mitochondrial damage induced by glutamate in HT22 cells. However, the cytoprotective effect by compound K was abolished by heme oxygenase-1 inhibitor, tin protophorphyrin IX, suggesting that neuroprotective effect of compound K was caused by its Nrf2-mediated induction of antioxidant enzymes. Further, memory deficit induced by scopolamine was restored by compound K, which did not inhibit acetylcholine esterase, in C57BL/6 mice but not in Nrf2 knockout mice as assessed by passive avoidance test, Y-maze and water maze tests, suggesting that scopolamine-induced memory impairment was overcome by the induction of Nrf2-mediated antioxidant enzymes by the compound K. Overall, our data indicate that compound K could be useful in prevention and treatment of reactive oxygen species-induced neurological disorders such as Alzheimer's disease.

Depletion of nucleus accumbens dopamine leads to impaired reward and aversion processing in mice: Relevance to motivation pathologies

Dopamine (DA) neurotransmission, particularly the ventral tegmental area-nucleus accumbens (VTA-NAcc) projection, underlies reward and aversion processing, and deficient DA function could underlie motivational impairments in psychiatric disorders. 6-hydroxydopamine (6-OHDA) injection is an established method for chronic DA depletion, principally applied in rat to study NAcc DA regulation of reward motivation. Given the increasing focus on studying environmental and genetic regulation of DA function in mouse models, it is important to establish the effects of 6-OHDA DA depletion in mice, in terms of reward and aversion processing. This mouse study investigated effects of 6-OHDA-induced NAcc DA depletion using the operant behavioural test battery of progressive ratio schedule (PRS), learned non-reward (LNR), learned helplessness (LH), treadmill, and in addition Pavlovian fear conditioning. 6-OHDA NAcc DA depletion, confirmed by ex vivo HPLC-ED, reduced operant responding: for gustatory reward under effortful conditions in the PRS test; to a stimulus recently associated with gustatory non-reward in the LNR test; to escape footshock recently experienced as uncontrollable in the LH test; and to avoid footshock by physical effort in the treadmill test. Evidence for specificity of effects to NAcc DA was provided by lack of effect of medial prefrontal cortex DA depletion in the LNR and LH tests. These findings add significantly to the evidence that NAcc DA is a major regulator of behavioural responding, particularly at the motivational level, to both reward and aversion. They demonstrate the suitability of mouse models for translational study of causation and reversal of pathophysiological DA function underlying motivation psychopathologies.

Temporal Properties of Cone ERGs of Pikachurin Null Mutant Mouse.

Pikachurin is an extracellular matrix-like protein located in the synaptic cleft of photoreceptors. Pikachurin null mutant (Pika-/-) mice have abnormal ON bipolar cell function. This study aimed to determine the contribution of the ON bipolar cell pathway (ON pathway) of Pika-/- mice to the flicker ERG response and, using vector analysis, identify how the contribution varies with the stimulus frequency. Flicker ERGs were recorded from wild-type (WT), Pika-/-, and mGluR6 null mutant (mGluR6-/-) mice. The frequency of stimulation was 3.906 to 31.250 Hz. The amplitude and phase of the fundamental components were obtained by harmonic and vector model analysis. The mGluR6-/- mice were used as a model wherein the ON pathway is known to be absent. The amplitudes of the fundamental components of the Pika-/- mice were significantly smaller than those of WT mice for stimulation frequencies between 3.906 and 17.578 Hz. The phase of the fundamental components of the Pika-/- mice was between those of the WT and mGluR6-/- mice. Vector analyses showed that the functioning of the ON pathway of Pika-/- mice was 12% to 25% of that of the WT mice at low frequencies (i.e., <15.625 Hz); however, it was reduced to noise level at frequencies >17.578 Hz. Vector model analysis can determine the degree of contribution of the ON pathway of Pika-/- mice to flicker ERG response and may be useful for determining the retinal function in mice models with abnormalities of the ON pathway.

Cone-Specific Promoters for Gene Therapy of Achromatopsia and Other Retinal Diseases.

Adeno-associated viral (AAV) vectors containing cone-specific promoters have rescued cone photoreceptor function in mouse and dog models of achromatopsia, but cone-specific promoters have not been optimized for use in primates. Using AAV vectors administered by subretinal injection, we evaluated a series of promoters based on the human L-opsin promoter, or a chimeric human cone transducin promoter, for their ability to drive gene expression of green fluorescent protein (GFP) in mice and nonhuman primates. Each of these promoters directed high-level GFP expression in mouse photoreceptors. In primates, subretinal injection of an AAV-GFP vector containing a 1.7-kb L-opsin promoter (PR1.7) achieved strong and specific GFP expression in all cone photoreceptors and was more efficient than a vector containing the 2.1-kb L-opsin promoter that was used in AAV vectors that rescued cone function in mouse and dog models of achromatopsia. A chimeric cone transducin promoter that directed strong GFP expression in mouse and dog cone photoreceptors was unable to drive GFP expression in primate cones. An AAV vector expressing a human CNGB3 gene driven by the PR1.7 promoter rescued cone function in the mouse model of achromatopsia. These results have informed the design of an AAV vector for treatment of patients with achromatopsia.

Toll-like receptor-4 antagonism mediates benefits during neuroinflammation.

Neuroinflammation following immune activation in the central nervous system (CNS) leads to neuronal loss in specific areas of the CNS resulting in neurodegenerative disorders. Thus, fine tuning the immune responses within the brain is essential, because most of the brain diseases are associated with chronic inflammation, aberrant microglia activation that follows inappropriate T cell activation and polarization. Brain's immune cells, microglia, are sensitized to extrinsic and intrinsic stimuli mediating neuroinflammation contributing to the removal of pathogen/injurious stimuli and initiate healing process in the CNS. However, dysregulation of the inflammatory response leads to bystander tissue damage. During sterile and infectious acute brain injuries chronic inflammation exacerbates neurodegeneration and contributes to pathogenesis of Alzheimer's disease, Parkinson's disease, Huntington's disease, multiple sclerosis, depression, sickness behaviour, diminished cognition and memory. Neuroinflammation in the CNS can be mediated by many of the factors including pattern/danger-associated molecular patterns (PAMPs and DAMPs) are recognised by the various classes of pattern recognition receptors (PRRs). Among the group of PRRs, the toll-like receptor-4 (TLR4) is crucially involved in neuropathology. Microglia are the only cell type in resting CNS that express TLR4 mediating neuronal damage (Lehnardt et al., 2003). Its upregulation is reported in neuronal injuries and neurodegenerative diseases while the deficiency protects against neurodegeneration and shows increased survival of neurons. Mutation in the TLR4 decreases microglial activation and preserves cognitive functions in mouse model of Alzheimer's disease.

Ibuprofen targets neuronal pentraxins expresion and improves cognitive function in mouse model of AlCl3-induced neurotoxicity.

Aluminum is known to exert neurotoxic effects associated with various neurodegenerative disorders, including Alzheimer's disease (AD). Ibuprofen is a well-known non-steroidal anti-inflammatory drug, which has demonstrated potential efficacy in the treatment of numerous inflammatory and neurodegenerative disorders, including AD. The present study aimed to investigate the protective effects of ibuprofen on cognitive function, and the expression levels of neuronal pentraxins (NPs) and interleukin (IL)-1β in an aluminum chloride (AlCl3)-induced mouse model of neurotoxicity. The effects of ibuprofen (100 mg/kg/day for 12 days) on learning and memory were evaluated in the AlCl3-induced neurotoxic mice using a Morris water maze and open field tests. In addition, ibuprofen was assessed for its effects on the expression levels of NPs and IL-1β in the hippocampus, cortex and amygdala of the brain. Treatment of the AlCl3-treated mice with ibuprofen decreased anxiety levels (6.90±0.34 min) compared with the AlCl3-treated group (1.80±0.29 min), as indicated by the time spent in the central area in an open field test. Furthermore, the expression levels of NP1 (1.32±0.47) and IL-1β (0.99±0.21) were significantly decreased in the hippocampus of mice following ibuprofen treatment, as compared with the AlCl3-treated mice (8.62±1.54 and 7.47±0.53, respectively). In the present study, ibuprofen was able to target novel structures in order to attenuate the inflammation associated with an AlCl3-induced mouse model of neurotoxicity; thus suggesting that ibuprofen may be considered a potential therapeutic option for the treatment of neurodegenerative diseases, including AD.

BIP induces mice CD19(hi) regulatory B cells producing IL-10 and highly expressing PD-L1, FasL.

Many studies have shown that B cells possess a regulatory function in mouse models of autoimmune diseases. Regulatory B cells can modulate immune response through many types of molecular mechanisms, including the production of IL-10 and the expression of PD-1 Ligand and Fas Ligand, but the microenvironmental factors and mechanisms that induce regulatory B cells have not been fully identified. BIP (binding immunoglobulin protein), a member of the heat shock protein 70 family, is a type of evolutionarily highly conserved protein. In this article, we have found that IL-10(+), PD-L1(hi) and FasL(hi) B cells are discrete cell populations, but enriched in CD19(hi) cells. BIP can induce IL-10-producing splenic B cells, IL-10 secretion and B cells highly expressing PD-L1 and FasL. CD40 signaling acts in synergy with BIP to induce regulatory B cells. BIP increased surface CD19 molecule expression intensity and IL-10(+), PD-L1(hi) and FasL(hi) B cells induced by BIP share the CD19(hi) phenotype. Furthermore, B cells treated with BIP and anti-CD40 can lead to suppression of T cell proliferation and the effect is partially IL-10-dependent and mainly BIP-induced. Taken together, our findings identify a novel function of BIP in the induction of regulatory B cells and add a new reason for the therapy of autoimmune disorders or other inflammatory conditions.

Using the GEMM-ESC strategy to study gene function in mouse models.

Preclinical in vivo validation of target genes for therapeutic intervention requires careful selection and characterization of the most suitable animal model in order to assess the role of these genes in a particular process or disease. To this end, genetically engineered mouse models (GEMMs) are typically used. However, the appropriate engineering of these models is often cumbersome and time consuming. Recently, we and others described a modular approach for fast-track modification of existing GEMMs by re-derivation of embryonic stem cells (ESCs) that can be modified by recombinase-mediated transgene insertion and subsequently used for the production of chimeric mice. This 'GEMM-ESC strategy' allows for rapid in vivo analysis of gene function in the chimeras and their offspring. Moreover, this strategy is compatible with CRISPR/Cas9-mediated genome editing. This protocol describes when and how to use the GEMM-ESC strategy effectively, and it provides a detailed procedure for re-deriving and manipulating GEMM-ESCs under feeder- and serum-free conditions. This strategy produces transgenic mice with the desired complex genotype faster than traditional methods: generation of validated GEMM-ESC clones for controlled transgene integration takes 9-12 months, and recombinase-mediated transgene integration and chimeric cohort production takes 2-3 months. The protocol requires skills in embryology, stem cell biology and molecular biology, and it is ideally performed within, or in close collaboration with, a transgenic facility.

Pirfenidone decreases fibrosis and improves lymphatic function in mouse models of lymphedema

Pirfenidone decreases fibrosis and improves lymphatic function in mouse models of lymphedema

Lesion of the locus coeruleus aggravates dopaminergic neuron degeneration by modulating microglial function in mouse models of Parkinson׳s disease

The degeneration of noradrenergic neurons in the locus coeruleus (LC) commonly occurs in patients with Parkinson׳s disease (PD), which is characterized by a selective injury of dopaminergic neurons in the substantia nigra (SN). The pathological impact of the LC on the SN in the disease is unknown. In the present study, we used a noradrenergic toxin, N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4), to deplete noradrenaline (NA) derived from the LC to explore its influence on degeneration or injury of dopaminergic neurons in the SN in mouse model produced by intraperitoneal injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or lipopolysaccharide (LPS). Our results demonstrated that lesion of the LC could change microglial function in the brain, which led to enhanced or prolonged expression of pro-inflammatory cytokines, diminished neurotrophic factors, and weakened ability of anti-oxidation in the SN. The in vitro experiments further confirmed that NA could reduce the inflammatory reaction of microglia. The selective injury of dopaminergic neurons by inflammation, however, was due to the inflammation in different brain regions rather than the depletion of NA. Our results indicate that the lesion in the LC is an important factor in promoting dopaminergic neuron degeneration by impacting the function of microglia in the midbrain.

Effect of Modified Baizhu Powder on Gastrointestinal Functions in Mouse Models with Stomach-cold Functional Dyspepsia

To explore the effect of modified Baizhu (Rhizoma Atractylodis Macrocephalae) powder on the gastrointestinal function in mouse models with stomach-cold functional dyspepsia. Meanwhile,the mouse models were administered with Shihu (dendrobium), a traditional Chinese drug with cold nature and flavour, to explore the way via which it exert its effect on specific symptoms. Methods: Mouse models with stomach-cold functional dyspepsia were established by ice water and ice NaOH. The effects of modified Baizhu powder and dendrobium on mice were observed in terms of water intake, weight change,small intestine propulsion rate, intestinal absorption function, and effects on ghrelin and motilin. The modified Baizhu powder effectively increased food intake, water intake, body weight (P<0.05) and swimming time (P<0.01), increased the small intestine propulsion rate and serum D-xylose content (P<0.05), and up-regulated ghrelin (P<0.05). Also, it showed a trend to down-regulate the motilin, although the change was not statistically significant (P>0.05). In contrast,the use of Shihu aggravated symptoms in the mouse models. Conclusion: The changes in ghrelin and motilin levels may be the neuro-endocrine mechanisms via which the modified Baizhu powder and Shihu exert their effects on mouse models.

Spatiotemporal dynamics of effector CD8+ T cell responses within the liver.

CD8(+) T cells play a critical role in controlling hepatotropic viral infections, such as those caused by hepatitis B and hepatitis C viruses. The capacity of these cells to protect against such pathogens is mediated by antigen-experienced effector cells and relies on their ability to home to the liver, recognize pathogen-derived antigens, and deploy effector functions. Here, we review how dynamic imaging of hepatic effector CD8(+) T cell migration and function in mouse models of hepatitis B virus pathogenesis has recently revealed a unique and novel mode of adaptive immune surveillance. Circulating effector CD8(+) T cells initially arrest within liver sinusoids by docking onto adherent platelets and then actively crawl along the liver vasculature, probing hepatocytes for the presence of antigens by extending protrusions through the fenestrated sinusoidal endothelial cells. Hepatocellular antigen recognition and effector functions occur while CD8(+) T cells are still confined to the intravascular space and are inhibited by the pathologic processes that characterize liver fibrosis. A detailed understanding of the spatiotemporal dynamics of effector CD8(+) T cells within the liver is important for the rational design of targeted immunotherapeutic approaches for chronic liver infections.

Tmc gene therapy restores auditory function in deaf mice.

Genetic hearing loss accounts for up to 50% of prelingual deafness worldwide, yet there are no biologic treatments currently available. To investigate gene therapy as a potential biologic strategy for restoration of auditory function in patients with genetic hearing loss, we tested a gene augmentation approach in mouse models of genetic deafness. We focused on DFNB7/11 and DFNA36, which are autosomal recessive and dominant deafnesses, respectively, caused by mutations in transmembrane channel-like 1 (TMC1). Mice that carry targeted deletion of Tmc1 or a dominant Tmc1 point mutation, known as Beethoven, are good models for human DFNB7/11 and DFNA36. We screened several adeno-associated viral (AAV) serotypes and promoters and identified AAV2/1 and the chicken β-actin (Cba) promoter as an efficient combination for driving the expression of exogenous Tmc1 in inner hair cells in vivo. Exogenous Tmc1 or its closely related ortholog, Tmc2, were capable of restoring sensory transduction, auditory brainstem responses, and acoustic startle reflexes in otherwise deaf mice, suggesting that gene augmentation with Tmc1 or Tmc2 is well suited for further development as a strategy for restoration of auditory function in deaf patients who carry TMC1 mutations.

Ginsenoside Rg1 Ameliorates Motor Function in an Animal Model of Parkinson's Disease

Aims: Parkinson's disease (PD) is a neurodegenerative disorder characterized by loss of dopaminergic neurons in the substantia nigra (SN) and diminished dopamine levels in the striatum. Accumulating evidence supported that ginsenoside Rg1, the major pharmacologically active compound of ginseng, has a wide range of neurotrophic and neuroprotective effects under physiological and pathological conditions. Although Rg1 administration protects dopaminergic neurons in a rat model of PD, it is unclear if Rg1 treatment ameliorates motor function in PD. Methods: Using the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) that causes dopaminergic neurodegeneration, we investigated the effect of Rg1 on 3 tests of motor behaviors in mice: the accelerating rotarod, wire suspension and pole tests. Results: The results showed that Rg1 treatment (10 mg/kg, i.p.) succeeded in restoring motor functions to physiological level in MPTP-treated mice. Importantly, these behavioral ameliorations were accompanied by an attenuation of the MPTP-induced loss of dopaminergic neurons in the SN and striatum. Conclusions: These findings indicate that Rg1 can significantly rescue the deficit of motor function in mice model of PD, and suggest that Rg1 may be a potential therapeutic agent against PD and related disorders.