Transgenic overexpression of neuroglobin attenuates formation of smoke-inhalation-induced oxidative DNA damage, in vivo, in the mouse brain

Acute inhalation of combustion smoke causes neurological deficits in survivors. Inhaled smoke includes carbon monoxide, noxious gases, and a hypoxic environment, which disrupt oxygenation and generate free radicals. To replicate a smoke-inhalation scenario, we developed an experimental model of acute exposure to smoke for the awake mouse/rat and detected induction of biomarkers of oxidative stress. These include inhibition of mitochondrial respiratory complexes and formation of oxidative DNA damage in the brain. DNA damage is likely to contribute to neuronal dysfunction and progression of brain injury. In the search for strategies to attenuate the smoke-initiated brain injury, we produced a transgenic mouse overexpressing the neuronal globin protein neuroglobin. Neuroglobin was neuroprotective in diverse models of ischemic/hypoxic/toxic brain injuries. Here, we report lesser inhibition of respiratory complex I and reduced formation of smoke-induced DNA damage in neuroglobin transgenic compared to wild-type mouse brain. DNA damage was assessed using the standard comet assay, as well as a modified comet assay done in conjunction with an enzyme that excises oxidized guanines that form readily under conditions of oxidative stress. Both comet assays revealed that overexpressed neuroglobin attenuates the formation of oxidative DNA damage, in vivo, in the brain. These findings suggest that elevated neuroglobin exerts neuroprotection, in part, by decreasing the impact of acute smoke inhalation on the integrity of neuronal DNA.     

Brain Prolyl Endopeptidase Expression in Aging, APP Transgenic Mice and Alzheimer’s Disease

Prolyl endopeptidase (PEP) is believed to inactivate neuropeptides that are present in the extracellular space. However, the intracellular localization of PEP suggests additional, yet unidentified physiological functions for this enzyme. Here we studied the expression, enzymatic activity and subcellular localization of PEP in adult and aged mouse brain as well as in brains of age-matched APP transgenic Tg2576 mice and in brains of Alzheimer’s disease patients. In mouse brain PEP was exclusively expressed by neurons and displayed region- and age-specific differences in expression levels, with the highest PEP activity being present in cerebellum and a significant increase in hippocampal but not cortical or cerebellar PEP activity in aged mouse brain. In brains of young APP transgenic Tg2576 mice, hippocampal PEP activity was increased compared to wild-type littermates in the pre-plaque phase but not in aged mice with β-amyloid plaque pathology. This “accelerated aging” with regard to hippocampal PEP expression in young APP transgenic mice might be one factor contributing to the observed cognitive deficits in these mice in the pre-plaque phase and could also explain in part the cognition-enhancing effects of PEP inhibitors in serveral experimental paradigms.     

Reduced basal and novelty-induced levels of activity-regulated cytoskeleton associated protein (Arc) and c-Fos mRNA in the cerebral cortex and hippocampus of APPswe/PS1ΔE9 transgenic mice

Activity-regulated cytoskeletal-associated protein (Arc) and c-Fos are immediate early gene (IEG) products induced by novelty in the hippocampus and involved in the consolidation of synaptic plasticity and long-term memory. We investigated whether induction of arc and c-fos after exposure to a novel open field environment was compromised in different neocortical areas and the hippocampal formation in APP/PS1ΔE9 transgenic mice characterized by pronounced accumulation and deposition of beta amyloid (Aβ). Notably, the basal level of Arc and c-fos mRNA in the neocortex was significantly lower in APP/PS1ΔE9 compared to wild-type mice. Novelty exposure induced an increase in Arc and c-Fos mRNA in the medial prefrontal cortex (mPFC), parietal cortex, and hippocampal formation in both APP/PS1ΔE9 transgenic and wild-type mice. However, novelty-induced IEG expression did not reach the same levels in APP/PS1ΔE9 as in the wild-type mice. In contrast, synaptophysin levels did not differ between mutant and wild type mice, suggesting that the observed effect was not due to a general decrease in the number of presynapses. These data suggest a reduction in basal and novelty-induced neuronal activity in a transgenic mouse model of Alzheimer’s disease, which is most pronounced in cortical regions, indicating that a decreased functional response in IEG expression could be partly responsible for the cognitive deficits observed in patients with Alzheimer’s disease.     

Accumulation of oxidatively generated DNA damage in the brain: a mechanism of neurotoxicity

Unrepaired or erroneously repaired DNA lesions drive genomic instability and contribute to cellular and organ decline. Since delayed neuropathologies are common in survivors of smoke inhalation injuries, we asked whether the integrity of brain DNA might be compromised by acute exposure to combustion smoke. Although many studies demonstrate that the brain is equipped to repair oxidatively damaged DNA, to date, the capacity for accurate DNA repair under conditions of disrupted oxygenation and oxidative stress has not been defined. We show that DNA adducts detectable by their ability to block PCR amplification form in the rat hippocampus after acute exposure to smoke. To identify the different types of adducts and to dissect their temporal formation and repair profiles in vivo in the brain, we used DNA-modifying enzymes to convert specific adducts into strand breaks prior to PCR amplification. Using this strategy, we detected formation of oxidative DNA adducts early on after smoke inhalation, while mismatched bases emerged at the later recovery times, potentially due to an erroneous DNA repair process. Erroneous repair can be mutagenic and because the initial smoke-induced oxidative damage to DNA is extensive, compromised fidelity of DNA repair may underlie neurotoxicity and contribute to delayed death of hippocampal neurons.     

Role of hippocalcin in mediating Aβ toxicity

Alzheimer's disease (AD) is the most common cause of dementia, and amyloid-β (Aβ) plaques and tau-containing tangles are its histopathological hallmark lesions. These do not occur at random; rather, the neurodegenerative process is stereotyped in that it is initiated in the entorhinal cortex and hippocampal formation. Interestingly, it is the latter brain area where the calcium-sensing enzyme hippocalcin is highly expressed. Because calcium deregulation is a well-established pathomechanism in AD, we aimed to address the putative role of hippocalcin in human AD brain and transgenic mouse models. We found that hippocalcin levels are increased in human AD brain and in Aβ plaque-forming APP23 transgenic mice compared to controls. To determine the role of hippocalcin in Aβ toxicity, we treated primary cultures derived from hippocalcin knockout (HC KO) mice with Aβ and found them to be more susceptible to Aβ toxicity than controls. Likewise, treatment with either thapsigargin or ionomycin, both known to deregulate intracellular calcium levels, caused an increased toxicity in hippocampal neurons from HC KO mice compared to wild-type. We found further that mitochondrial complex I activity increased from 3 to 6months in hippocampal mitochondria from wild-type and HC KO mice, but that the latter exhibited a significantly stronger aging phenotype than wild-type. Aβ treatment induced significant toxicity on hippocampal mitochondria from HC KO mice already at 3months of age, while wild-type mitochondria were spared. Our data suggest that hippocalcin has a neuroprotective role in AD, presenting it as a putative biomarker.     

Mice transgenic for human angiotensin-converting enzyme 2 provide a model for SARS coronavirus infection

To establish a small animal model of severe acute respiratory syndrome (SARS), we developed a mouse model of human severe acute respiratory syndrome coronavirus (SARS-CoV) infection by introducing the human gene for angiotensin-converting enzyme 2 (hACE2) (the cellular receptor of SARS-CoV), driven by the mouse ACE2 promoter, into the mouse genome. The hACE2 gene was expressed in lung, heart, kidney, and intestine. We also evaluated the responses of wild-type and transgenic mice to SARS-CoV inoculation. At days 3 and 7 postinoculation, SARS-CoV replicated more efficiently in the lungs of transgenic mice than in those of wild-type mice. In addition, transgenic mice had more severe pulmonary lesions, including interstitial hyperemia and hemorrhage, monocytic and lymphocytic infiltration, protein exudation, and alveolar epithelial cell proliferation and desquamation. Other pathologic changes, including vasculitis, degeneration, and necrosis, were found in the extrapulmonary organs of transgenic mice, and viral antigen was found in brain. Therefore, transgenic mice were more susceptible to SARS-CoV than were wild-type mice, and susceptibility was associated with severe pathologic changes that resembled human SARS infection. These mice will be valuable for testing potential vaccine and antiviral drug therapies and for furthering our understanding of SARS pathogenesis.     

Resting State fMRI Reveals Diminished Functional Connectivity in a Mouse Model of Amyloidosis

Introduction

Functional connectivity (FC) studies have gained immense popularity in the evaluation of several neurological disorders, such as Alzheimer’s disease (AD). AD is a complex disorder, characterised by several pathological features. The problem with FC studies in patients is that it is not straightforward to focus on a specific aspect of pathology. In the current study, resting state functional magnetic resonance imaging (rsfMRI) is applied in a mouse model of amyloidosis to assess the effects of amyloid pathology on FC in the mouse brain.

Methods

Nine APP/PS1 transgenic and nine wild-type mice (average age 18.9 months) were imaged on a 7T MRI system. The mice were anesthetized with medetomidine and rsfMRI data were acquired using a gradient echo EPI sequence. The data were analysed using a whole brain seed correlation analysis and interhemispheric FC was evaluated using a pairwise seed analysis. Qualitative histological analyses were performed to assess amyloid pathology, inflammation and synaptic deficits.

Results

The whole brain seed analysis revealed an overall decrease in FC in the brains of transgenic mice compared to wild-type mice. The results showed that interhemispheric FC was relatively preserved in the motor cortex of the transgenic mice, but decreased in the somatosensory cortex and the hippocampus when compared to the wild-type mice. The pairwise seed analysis confirmed these results. Histological analyses confirmed the presence of amyloid pathology, inflammation and synaptic deficits in the transgenic mice.

Conclusions

In the current study, rsfMRI demonstrated decreased FC in APP/PS1 transgenic mice compared to wild-type mice in several brain regions. The APP/PS1 transgenic mice had advanced amyloid pathology across the brain, as well as inflammation and synaptic deficits surrounding the amyloid plaques. Future studies should longitudinally evaluate APP/PS1 transgenic mice and correlate the rsfMRI findings to specific stages of amyloid pathology.     

Neurocan is dispensable for brain development

Neurocan is a component of the extracellular matrix in brain. Due to its inhibition of neuronal adhesion and outgrowth in vitro and its expression pattern in vivo it was suggested to play an important role in axon guidance and neurite growth. To study the role of neurocan in brain development we generated neurocan-deficient mice by targeted disruption of the neurocan gene. These mice are viable and fertile and have no obvious deficits in reproduction and general performance. Brain anatomy, morphology, and ultrastructure are similar to those of wild-type mice. Perineuronal nets surrounding neurons appear largely normal. Mild deficits in synaptic plasticity may exist, as maintenance of late-phase hippocampal long-term potentiation is reduced. These data indicate that neurocan has either a redundant or a more subtle function in the development of the brain.     

Reduction in neuronal L-type calcium channel activity in a double knock-in mouse model of Alzheimer's disease

Increased function of neuronal L-type voltage-sensitive Ca(2+) channels (L-VSCCs) is strongly linked to impaired memory and altered hippocampal synaptic plasticity in aged rats. However, no studies have directly assessed L-VSCC function in any of the common mouse models of Alzheimer's disease where neurologic deficits are typically more robust. Here, we used cell-attached patch-clamp recording techniques to measure L-VSCC activity in CA1 pyramidal neurons of partially dissociated hippocampal "zipper" slices prepared from 14-month-old wild-type mice and memory-impaired APP/PS1 double knock-in mice. Surprisingly, the functional channel density of L-VSCCs was significantly reduced in the APP/PS1 group. No differences in voltage dependency and unitary conductance of L-VSCCs were observed. The results suggest that mechanisms for Ca(2+) dysregulation can differ substantially between animal models of normal aging and models of pathological aging.     

HIV-1-induced pulmonary oxidative and nitrosative stress: exacerbated response to endotoxin administration in HIV-1 transgenic mouse model

Human immunodeficiency virus (HIV)-1 causes lung disease by increasing the host's susceptibility to pathogens. HIV-1 also causes an increase in systemic oxidative/nitrosative stress, perhaps enhancing the deleterious effects of secondary infections. Here we examined the ability of HIV-1 proteins to increase lung oxidative/nitrosative stress after lipopolysaccharide (LPS) (endotoxin) administration in an HIV-1 transgenic mouse model. Lung oxidative/nitrosative stress biomarkers studied 3 and 6 h after LPS administration were as follows: lung edema, tissue superoxide, NO metabolites, nitrotyrosine, hydrogen peroxide, and bronchoalveolar lavage fluid (BALF) glutathione (GSH). Blood serum cytokine levels were quantified to verify immune function of our nonimmunocompromised animal model. Results indicate that 3 h after LPS administration, HIV-1 transgenic mouse lung tissue has significantly greater edema and superoxide. Furthermore, NO metabolites are significantly elevated in HIV-1 transgenic mouse BALF, lung tissue, and blood plasma compared with those of wild-type mice. HIV-1 transgenic mice also produce significantly greater lung nitrotyrosine and hydrogen peroxide than wild-type mice. In addition, HIV-1 transgenic mice produce significantly less BALF GSH than wild-type mice 3 h after LPS treatment. Without treatment, serum cytokine levels are similar for HIV-1 transgenic and wild-type mice. After treatment, serum cytokine levels are significantly elevated in both HIV-1 transgenic and wild-type mice. Therefore, HIV-1 transgenic mice have significantly greater lung oxidative/nitrosative stress after endotoxin administration than wild-type mice, independent of immune function. These results indicate that HIV-1 proteins may increase pulmonary complications subsequent to a secondary infection by altering the lung redox potential.     

Brevican-deficient mice display impaired hippocampal CA1 long-term potentiation but show no obvious deficits in learning and memory

Brevican is a brain-specific proteoglycan which is found in specialized extracellular matrix structures called perineuronal nets. Brevican increases the invasiveness of glioma cells in vivo and has been suggested to play a role in central nervous system fiber tract development. To study the role of brevican in the development and function of the brain, we generated mice lacking a functional brevican gene. These mice are viable and fertile and have a normal life span. Brain anatomy was normal, although alterations in the expression of neurocan were detected. Perineuronal nets formed but appeared to be less prominent in mutant than in wild-type mice. Brevican-deficient mice showed significant deficits in the maintenance of hippocampal long-term potentiation (LTP). However, no obvious impairment of excitatory and inhibitory synaptic transmission was found, suggesting a complex cause for the LTP defect. Detailed behavioral analysis revealed no statistically significant deficits in learning and memory. These data indicate that brevican is not crucial for brain development but has restricted structural and functional roles.     

Cyclin D1 overexpression in mouse epidermis increases cyclin-dependent kinase activity and cell proliferation in vivo but does not affect skin tumor development.

In a previous study, we showed that synchronized proliferation of mouse epidermis was induced by topical application of 12-O-tetradecanoyl-phorbol 13-acetate. Here, we used this system to study modifications in the cell cycle regulation and kinetics of proliferation in transgenic mice that overexpress cyclin D1 (K5D1 mice). Overexpression of cyclin D1 corresponded with an increase of proliferation in the epidermis of these transgenic mice. After proliferation reached its peak, the labeling index remained high in the transgenics, but not in the wild-type animals. In addition, cyclin D1/cyclin-dependent kinase (CDK) complex formation increased in the transgenic mice and was correlated with elevated CDK4 and CDK6 kinase activities. However, the increased CDK activities were not sufficient to effect mouse skin tumor development. In summary, these results show that cyclin D1 has a unique growth-promoting role in tumor development, but does not act as an oncogene independent of ras activity.     

Deletion of Selenoprotein M Leads to Obesity without Cognitive Deficits

Selenium is an essential trace element that is co-translationally incorporated into selenoproteins in the form of the 21st amino acid, selenocysteine. This class of proteins largely functions in oxidation-reduction reactions and is critically involved in maintaining proper redox balance essential to health. Selenoprotein M (SelM) is a thioredoxin-like endoplasmic reticulum-resident protein that is highly expressed in the brain and possesses neuroprotective properties. In this study, we first assessed the regional pattern of SelM expression in the mouse brain to provide insights into the potential functional implications of this protein in physiology and behavior. Next, we generated transgenic mice with a targeted deletion of the SelM gene and subjected them to a battery of neurobehavioral tests to evaluate motor coordination, locomotion, and cognitive function in comparison with wild-type controls. Finally, these mice were tested for several measures of metabolic function and body composition. Our results show that SelM knock-out (KO) mice display no deficits in measures of motor coordination and cognitive function but exhibit increased weight gain, elevated white adipose tissue deposition, and diminished hypothalamic leptin sensitivity. These findings suggest that SelM plays an important role in the regulation of body weight and energy metabolism.     

Presence of DNA fragmentation and lack of neuroprotective effect in DFF45 knockout mice subjected to traumatic brain injury

BACKGROUND: Apoptosis plays an important pathophysiologic role in neuronal cell loss and associated neurologic deficits following traumatic brain injury (TBI). DNA fragmentation represents one of the characteristic biochemical features of neuronal apoptosis and is observed after experimental TBI. DFF45 and DFF40 are essential for DNA fragmentation in various models of apoptosis. MATERIALS AND METHODS: We used mice deficient in DFF45 and wild-type controls. Oligonucleosomal DNA fragmentation induced by TBI was analyzed using in vivo and in vitro assays. Expression and integrity of DFF45 and DFF40 proteins was assessed by Western analysis. Other outcome measurements included neurologic scoring, learning/memory tests, lesion volume measurements (MRI), and assessment of cell viability in vitro among others. RESULTS: We compared the effects of controlled cortical impact (CCI) trauma in DFF45 knockout mice and wild-type controls. Analysis of TBI-induced DNA fragmentation in brain cortex from wild-type and DFF45 knockout mice indicates that, although somewhat delayed, oligonucleosomal cleavage of DNA occurs after TBI in DFF45 knockout mice. DFF45 knockouts showed no significant differences in behavioral outcomes or lesion volumes after TBI as compared to wild-type controls. Using an in vitro reconstitution system, we also demonstrated that cleavage of DFF45 by caspase-3 is not sufficient for DNA fragmentation induced by protein extracts from rat brain cortex. We found that endonuclease activity induced in rat brain cortex following TBI depends on the presence of Mg2+ and Ca2+, but is not inhibited by Zn2+. Primary neuronal cultures from DFF45 knockouts failed to show DNA laddering in response to staurosporine, but did show prominent, albeit delayed, DNA fragmentation following treatment with etoposide. In contrast, primary neurons from wild-type animals demonstrated marked DNA fragmentation following treatment with staurosporine or etoposide. CONCLUSIONS: The results of this study suggest that, in addition to DFF45/40, other endonucleases may be essential for chromatin degradation during neuronal apoptosis in adult brain after TBI.     

Limited accumulation of damaged proteins in l-isoaspartyl (D-aspartyl) O-methyltransferase-deficient mice

l-Isoaspartyl (d-aspartyl) O-methyltransferase (PCMT1) can initiate the conversion of damaged aspartyl and asparaginyl residues to normal l-aspartyl residues. Mice lacking this enzyme (Pcmt1-/- mice) have elevated levels of damaged residues and die at a mean age of 42 days from massive tonic-clonic seizures. To extend the lives of the knockout mice so that the long term effects of damaged residue accumulation could be investigated, we produced transgenic mice with a mouse Pcmt1 cDNA under the control of a neuron-specific promoter. Pcmt1 transgenic mice that were homozygous for the endogenous Pcmt1 knockout mutation ("transgenic Pcmt1-/- mice") had brain PCMT1 activity levels that were 6.5-13% those of wild-type mice but had little or no activity in other tissues. The transgenic Pcmt1-/- mice lived, on average, 5-fold longer than nontransgenic Pcmt1-/- mice and accumulated only half as many damaged aspartyl residues in their brain proteins. The concentration of damaged residues in heart, testis, and brain proteins in transgenic Pcmt1-/- mice initially increased with age but unexpectedly reached a plateau by 100 days of age. Urine from Pcmt1-/- mice contained increased amounts of peptides with damaged aspartyl residues, apparently enough to account for proteins that were not repaired intracellularly. In the absence of PCMT1, proteolysis may limit the intracellular accumulation of damaged proteins but less efficiently than in wild-type mice having PCMT1-mediated repair.     

Long-Lasting Cerebral Vasospasm,Microthrombosis, Apoptosis and Paravascular Alterations Associated with Neurological Deficits in a Mouse Model of Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating disease with high mortality and morbidity. Long-term cognitive and sensorimotor deficits are serious complications following SAH but still not well explained and described in mouse preclinical models. The aim of our study is to characterize a well-mastered SAH murine model and to establish developing pathological mechanisms leading to cognitive and motor deficits, allowing identification of specific targets involved in these long-term troubles. We hereby demonstrate that the double blood injection model of SAH induced long-lasting large cerebral artery vasospasm (CVS), microthrombosis formation and cerebral brain damage including defect in potential paravascular diffusion. These neurobiological alterations appear to be associated with sensorimotor and cognitive dysfunctions mainly detected 10 days after the bleeding episode. In conclusion, this characterized model of SAH in mice, stressing prolonged neurobiological pathological mechanisms and associated sensitivomotor deficits, will constitute a validated preclinical model to better decipher the link between CVS, long-term cerebral apoptosis and cognitive disorders occurring during SAH and to allow investigating novel therapeutic approaches in transgenic mice.     

Immunohistochemical Visualization of Hippocampal Neuron Activity After Spatial Learning in a Mouse Model of Neurodevelopmental Disorders

Induction of phosphorylated extracellular-regulated kinase (pERK) is a reliable molecular readout of learning-dependent neuronal activation. Here, we describe a pERK immunohistochemistry protocol to study the profile of hippocampal neuron activation following exposure to a spatial learning task in a mouse model characterized by cognitive deficits of neurodevelopmental origin. Specifically, we used pERK immunostaining to study neuronal activation following Morris water maze (MWM, a classical hippocampal-dependent learning task) in Engrailed-2 knockout (En2^-/-) mice, a model of autism spectrum disorders (ASD). As compared to wild-type (WT) controls, En2^-/- mice showed significant spatial learning deficits in the MWM. After MWM, significant differences in the number of pERK-positive neurons were detected in specific hippocampal subfields of En2^-/- mice, as compared to WT animals. Thus, our protocol can robustly detect differences in pERK-positive neurons associated to hippocampal-dependent learning impairment in a mouse model of ASD. More generally, our protocol can be applied to investigate the profile of hippocampal neuron activation in both genetic or pharmacological mouse models characterized by cognitive deficits.     

Age‐related decline in BubR1 impairs adult hippocampal neurogenesis

Aging causes significant declines in adult hippocampal neurogenesis and leads to cognitive disability. Emerging evidence demonstrates that decline in the mitotic checkpoint kinase BubR1 level occurs with natural aging and induces progeroid features in both mice and children with mosaic variegated aneuploidy syndrome. Whether BubR1 contributes to age‐related deficits in hippocampal neurogenesis is yet to be determined. Here we report that BubR1 expression is significantly reduced with natural aging in the mouse brain. Using established progeroid mice expressing low amounts of BubR1, we demonstrate these mice exhibit deficits in neural progenitor proliferation and maturation, leading to reduction in new neuron production. Collectively, our identification of BubR1 as a new and critical factor controlling sequential steps across neurogenesis raises the possibility that BubR1 may be a key mediator regulating aging‐related hippocampal pathology. Targeting BubR1 may represent a novel therapeutic strategy for age‐related cognitive deficits.     

Conditional depletion of neurogenesis inhibits long-term recovery after experimental stroke in mice

We reported previously that ablation of doublecortin (DCX)-immunopositive newborn neurons in mice worsens anatomical and functional outcome measured 1 day after experimental stroke, but whether this effect persists is unknown. We generated transgenic mice that express herpes simplex virus thymidine kinase under control of the DCX promoter (DCX-TK transgenic mice). DCX-expressing and recently divided cells in the rostral subventricular zone (SVZ) and hippocampus of DCX-TK transgenic mice, but not wild-type mice, were specifically depleted after ganciclovir (GCV) treatment for 14 days. Focal cerebral ischemia was induced by permanent distal middle cerebral artery occlusion (MCAO) on day 14 of vehicle or GCV treatment, and mice were killed 12 weeks after MCAO. Infarct volume was significantly increased and neurologic deficits were more severe in GCV- compared to vehicle-treated DCX-TK transgenic mice at first 8 weeks, after depletion of DCX- and bromodeoxyuridine-immunoreactive cells in the SVZ and dentate gyrus following focal ischemia. Our results indicate that endogenous neurogenesis in a critical period following experimental stroke influences the course of long-term recovery.     

人ACE2转基因小鼠对SARS-CoV的易感性

目的建立敏感的SARS小动物模型。方法通过显微注射技术,将编码SARS-CoV细胞受体的人血管紧张素转换酶(hACE2)基因导入小鼠的基因组中制备了hACE2转基因小鼠,在小鼠ACE2(mACE2)启动子的调控下,hACE2蛋白在转基因小鼠的肺脏、心脏、肾脏和小肠表达。我们观察了野生型和转基因小鼠在SARS冠状病毒接种后病原学和病理学方面的反应。结果在接种后第3天和第7天,病毒能够更有效地在转基因小鼠的肺脏复制,而且转基因小鼠出现更严重的肺损伤。肺组织的损伤包括肺间质充血、出血,单核细胞、淋巴细胞浸润及血浆蛋白的渗出,肺泡上皮细胞增生、脱落,此外,在转基因小鼠的某些器官还发现了血管炎、变性和坏死等病理变化。在转基因小鼠的肺上皮细胞、血管内皮细胞和脑神经细胞检测到病毒抗原。结论转基因小鼠比野生型小鼠对SARS病毒更易感,而且表现出更接近SARS患者的病理变化。