scholarly journals Glial activation is moderated by sex in response to amyloidosis but not to tau pathology in mouse models of neurodegenerative diseases

2020 ◽  
Vol 17 (1) ◽  
Author(s):  
Gloria Biechele ◽  
Nicolai Franzmeier ◽  
Tanja Blume ◽  
Michael Ewers ◽  
Jose Medina Luque ◽  
...  
Keyword(s):  
Mouse Models ◽  
Microglial Activation ◽  
Translocator Protein ◽  
Amyloid Pet ◽  
Wild Type ◽  
Tau Pathology ◽  
Female Mice ◽  
Β Amyloid ◽  
The Impact

Abstract Background In vivo assessment of neuroinflammation by 18-kDa translocator protein positron-emission-tomography (TSPO-PET) ligands receives growing interest in preclinical and clinical research of neurodegenerative disorders. Higher TSPO-PET binding as a surrogate for microglial activation in females has been reported for cognitively normal humans, but such effects have not yet been evaluated in rodent models of neurodegeneration and their controls. Thus, we aimed to investigate the impact of sex on microglial activation in amyloid and tau mouse models and wild-type controls. Methods TSPO-PET (18F-GE-180) data of C57Bl/6 (wild-type), AppNL-G-F (β-amyloid model), and P301S (tau model) mice was assessed longitudinally between 2 and 12 months of age. The AppNL-G-F group also underwent longitudinal β-amyloid-PET imaging (Aβ-PET; 18F-florbetaben). PET results were confirmed and validated by immunohistochemical investigation of microglial (Iba-1, CD68), astrocytic (GFAP), and tau (AT8) markers. Findings in cerebral cortex were compared by sex using linear mixed models for PET data and analysis of variance for immunohistochemistry. Results Wild-type mice showed an increased TSPO-PET signal over time (female +23%, male +4%), with a significant sex × age interaction (T = − 4.171, p < 0.001). The Aβ model AppNL-G-F mice also showed a significant sex × age interaction (T = − 2.953, p = 0.0048), where cortical TSPO-PET values increased by 31% in female AppNL-G-F mice, versus only 6% in the male mice group from 2.5 to 10 months of age. Immunohistochemistry for the microglial markers Iba-1 and CD68 confirmed the TSPO-PET findings in male and female mice aged 10 months. Aβ-PET in the same AppNL-G-F mice indicated no significant sex × age interaction (T = 0.425, p = 0.673). The P301S tau model showed strong cortical increases of TSPO-PET from 2 to 8.5 months of age (female + 32%, male + 36%), without any significant sex × age interaction (T = − 0.671, p = 0.504), and no sex differences in Iba-1, CD68, or AT8 immunohistochemistry. Conclusion Female mice indicate sex-dependent microglia activation in aging and in response to amyloidosis but not in response to tau pathology. This calls for consideration of sex difference in TSPO-PET studies of microglial activation in mouse models of neurodegeneration and by extension in human studies.

scholarly journals Comparison of the Amyloid Load in the Brains of Two Transgenic Alzheimer’s Disease Mouse Models Quantified by Florbetaben Positron Emission Tomography

2021 ◽  
Vol 15 ◽  
Author(s):  
Antje Willuweit ◽  
Michael Schöneck ◽  
Sarah Schemmert ◽  
Philipp Lohmann ◽  
Saskia Bremen ◽  
...  
Keyword(s):  
Mouse Models ◽  
Ex Vivo ◽  
Small Animal ◽  
Emission Tomography ◽  
Amyloid Pet ◽  
Wild Type ◽  
Positron Emission ◽  
Plaque Load ◽  
Amyloid Load

Alzheimer’s disease (AD) is characterized by formation of amyloid plaques and neurofibrillary tangles in the brain, which can be mimicked by transgenic mouse models. Here, we report on the characterization of amyloid load in the brains of two transgenic amyloidosis models using positron emission tomography (PET) with florbetaben (FBB), an 18F-labeled amyloid PET tracer routinely used in AD patients. Young, middle-aged, and old homozygous APP/PS1 mice (ARTE10), old hemizygous APPswe/PS1ΔE9, and old wild-type control mice were subjected to FBB PET using a small animal PET/computed tomography scanner. After PET, brains were excised, and ex vivo autoradiography was performed. Plaque pathology was verified on brain sections with histological methods. Amyloid plaque load increased progressively with age in the cortex and hippocampus of ARTE10 mice, which could be detected with both in vivo FBB PET and ex vivo autoradiography. FBB retention showed significant differences to wild-type controls already at 9 months of age by both in vivo and ex vivo analyses. An excellent correlation between data derived from PET and autoradiography could be obtained (rPearson = 0.947, p &lt; 0.0001). Although amyloid load detected by FBB in the brains of old APPswe/PS1ΔE9 mice was as low as values obtained with young ARTE10 mice, statistically significant discrimination to wild-type animals was reached (p &lt; 0.01). In comparison to amyloid burden quantified by histological analysis, FBB retention correlated best with total plaque load and number of congophilic plaques in the brains of both mouse models. In conclusion, the homozygous ARTE10 mouse model showed superior properties over APPswe/PS1ΔE9 mice for FBB small animal amyloid PET imaging. The absolute amount of congophilic dense-cored plaques seems to be the decisive factor for feasibility of amyloidosis models for amyloid PET analysis.

scholarly journals Microglial activation in vivo is moderated by sex in response to amyloidosis but not to tau pathology in mouse models of Alzheimer’s disease

2020 ◽  
Vol 16 (S4) ◽  
Author(s):  
Gloria Biechele ◽  
Nicolai Franzmeier ◽  
Michael Ewers ◽  
Tanja Blume ◽  
Florian Eckenweber ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Mouse Models ◽  
Microglial Activation ◽  
Tau Pathology

scholarly journals Longitudinal Microglial Activation in Tau Transgenic P301S Mice Predicts Increased Tau Accumulation and Deteriorated Spatial Learning

2020 ◽  
Author(s):  
Florian Eckenweber ◽  
Jose Medina Luque ◽  
Tanja Blume ◽  
Christian Sacher ◽  
Gloria Biechele ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Transgenic Mice ◽  
Mouse Models ◽  
Spatial Learning ◽  
Microglial Activation ◽  
Amyloid Β ◽  
Learning Performance ◽  
Wild Type ◽  
Tspo Expression

Abstract Background: P301S tau transgenic mice show age-dependent accumulation of neurofibrillary tangles in brainstem, hippocampus, and neocortex, leading to neuronal loss and cognitive deterioration. However, there is hitherto only sparse documentation of the role of neuroinflammation in tau mouse models. Thus, we analyzed longitudinal microglial activation by small animal 18kDa translocator protein positron-emission-tomography (TSPO µPET) imaging in vivo , in conjunction with terminal assessment of tau pathology, spatial learning, and cerebral glucose metabolism. Methods: Transgenic P301S (n=33) and wild-type (n=18) female mice were imaged by 18 F-GE-180 TSPO µPET at the ages of 1.9, 3.9 and 6.4 months. We conducted behavioral testing in the Morris water maze, 18 F-fluordesoxyglucose ( 18 F-FDG) µPET and AT8 tau immunohistochemistry at 6.3-6.7 months. Terminal microglial immunohistochemistry served for validation of TSPO µPET results in vivo, applying target regions in brainstem, cortex, cerebellum and hippocampus. We compared the results with our historical data in amyloid -β mouse models. Results: TSPO expression in all target regions of P301S mice increased exponentially from 1.9 to 6.4 months, leading to significant differences in the contrasts with wild-type mice at 6.4 months (+11-23%, all p<0.001), but the apparent microgliosis proceeded more slowly than in our experience in amyloid-β mouse models. Spatial learning and glucose metabolism of AT8-positive P301S mice were significantly impaired at 6.3/6.5 months compared to the wild-type group. Longitudinal increases in TSPO expression predicted greater tau accumulation and lesser spatial learning performance at 6.7/6.3 months. Conclusions: Monitoring of microglial activation in P301S tau transgenic mice by TSPO µPET indicates a delayed time course when compared to amyloid-β mouse models. Detrimental associations of microglial activation with outcome parameters are opposite to earlier data in amyloid-β mouse models. The contribution of microglial response to pathology accompanying amyloid-β and tau over-expression merits further investigation.

scholarly journals Production of Noncapped Genomic RNAs Is Critical to Sindbis Virus Disease and Pathogenicity

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Autumn T. LaPointe ◽  
V Douglas Landers ◽  
Claire E. Westcott ◽  
Kevin J. Sokoloski
Keyword(s):  
Sindbis Virus ◽  
Virus Disease ◽  
Severe Disease ◽  
Wild Type Virus ◽  
Wild Type ◽  
Genomic Rnas ◽  
Mortality And Morbidity ◽  
The Impact

ABSTRACT Alphaviruses are positive-sense RNA viruses that utilize a 5′ cap structure to facilitate translation of viral proteins and to protect the viral RNA genome. Nonetheless, significant quantities of viral genomic RNAs that lack a canonical 5′ cap structure are produced during alphaviral replication and packaged into viral particles. However, the role/impact of the noncapped genomic RNA (ncgRNA) during alphaviral infection in vivo has yet to be characterized. To determine the importance of the ncgRNA in vivo, the previously described D355A and N376A nsP1 mutations, which increase or decrease nsP1 capping activity, respectively, were incorporated into the neurovirulent AR86 strain of Sindbis virus to enable characterization of the impact of altered capping efficiency in a murine model of infection. Mice infected with the N376A nsP1 mutant exhibited slightly decreased rates of mortality and delayed weight loss and neurological symptoms, although levels of inflammation in the brain were similar to those of wild-type infection. Although the D355A mutation resulted in decreased antiviral gene expression and increased resistance to interferon in vitro, mice infected with the D355A mutant showed significantly reduced mortality and morbidity compared to mice infected with wild-type virus. Interestingly, expression of proinflammatory cytokines was found to be significantly decreased in mice infected with the D355A mutant, suggesting that capping efficiency and the production of ncgRNA are vital to eliciting pathogenic levels of inflammation. Collectively, these data indicate that the ncgRNA have important roles during alphaviral infection and suggest a novel mechanism by which noncapped viral RNAs aid in viral pathogenesis. IMPORTANCE Mosquito-transmitted alphaviruses have been the cause of widespread outbreaks of disease that can range from mild illness to lethal encephalitis or severe polyarthritis. There are currently no safe and effective vaccines or therapeutics with which to prevent or treat alphaviral disease, highlighting the need to better understand alphaviral pathogenesis to develop novel antiviral strategies. This report reveals production of noncapped genomic RNAs (ncgRNAs) to be a novel determinant of alphaviral virulence and offers insight into the importance of inflammation to pathogenesis. Taken together, the findings reported here suggest that the ncgRNAs contribute to alphaviral pathogenesis through the sensing of the ncgRNAs during alphaviral infection and are necessary for the development of severe disease.

scholarly journals Pre-therapeutic Microglia Activation and Sex Determine Therapy Effects of Chronic Immunomodulation

2021 ◽  
Author(s):  
Gloria Biechele ◽  
Tanja Blume ◽  
Maximilian Deussing ◽  
Benedikt Zott ◽  
Yuan Shi ◽  
...  
Keyword(s):  
Spatial Learning ◽  
Microglial Activation ◽  
Translocator Protein ◽  
Learning Performance ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Activated Microglia ◽  
Ppar Γ ◽  
Amyloid Accumulation ◽  
Β Amyloid

Modulation of the innate immune system is emerging as a promising therapeutic strategy against Alzheimer's disease (AD). However, determinants of a beneficial therapeutic effect are ill-understood. Thus, we investigated the potential of 18 kDa translocator protein positron-emission-tomography (TSPO-PET) for assessment of microglial activation in mouse brain before and during chronic immunomodulation. Serial TSPO-PET was performed during five months of chronic microglia modulation by stimulation of peroxisome proliferator-activated receptor (PPAR)-γ with pioglitazone in two different mouse models of AD (PS2APP, AppNL-G-F). Using mixed statistical models on longitudinal TSPO-PET data, we tested for effects of therapy and sex on treatment response. We tested correlations of baseline with longitudinal measures of TSPO-PET, and correlations between PET results with spatial learning performance and β-amyloid accumulation of individual mice. Immunohistochemistry was used to determine the molecular source of the TSPO-PET signal. Pioglitazone-treated female PS2APP and AppNL-G-F mice showed attenuation of the longitudinal increases in TSPO-PET signal when compared to vehicle controls, whereas treated male AppNL-G-F mice showed the opposite effect. Baseline TSPO-PET strongly predicted changes in microglial activation in treated mice (R=-0.874, p<0.0001) but not in vehicle controls (R=-0.356, p=0.081). Reduced TSPO-PET signal upon treatment was associated with better spatial learning and higher fibrillar β-amyloid accumulation. Immunohistochemistry confirmed activated microglia to be the source of the TSPO-PET signal (R=0.952, p<0.0001). TSPO-PET represents a sensitive biomarker for monitoring of immunomodulation and closely reflects activated microglia. Pre-therapeutic assessment of baseline microglial activation and sex are strong predictors of individual immunomodulation effects and could serve for responder stratification.

scholarly journals Soluble P-tau217 reflects amyloid and tau pathology and mediates the association of amyloid with tau

2021 ◽  
Author(s):  
Niklas Mattsson-Carlgren ◽  
Shorena Janelidze ◽  
Randall Bateman ◽  
Ruben Smith ◽  
Erik Stomrud ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Medial Temporal Lobe ◽  
Amyloid Plaques ◽  
Amyloid Plaque ◽  
Amyloid Pet ◽  
Tau Pathology ◽  
Β Amyloid ◽  
Tau Pet ◽  
Disease Stages

Abstract Alzheimer’s disease is characterized by β-amyloid plaques and tau tangles. Plasma levels of phospho-tau217 (P-tau217) accurately differentiate Alzheimer’s disease dementia from other dementias, but it is unclear to what degree this reflects β-amyloid plaque accumulation, tau tangle accumulation, or both. In a cohort with post-mortem neuropathological data (N=88), both plaque and tangle density contributed independently to higher P-tau217. Several findings were replicated in a cohort with PET imaging (“BioFINDER-2”, N=426), where β-amyloid and tau PET were independently associated to P-tau217. P-tau217 correlated with β-amyloid PET (but not tau PET) in early disease stages, and with both β-amyloid and (more strongly) tau PET in late disease stages. Finally, P-tau217 mediated the association between β-amyloid and tau in both cohorts, especially for tau outside of the medial temporal lobe. These findings support the hypothesis that plasma P-tau217 is increased by both β-amyloid plaques and tau tangles and is congruent with the hypothesis that P-tau is involved in β-amyloid-dependent formation of neocortical tau tangles.

scholarly journals Noncapped Genomic RNA Are Critical for Alphaviral Infection and Pathogenicity

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 44
Author(s):  
Autumn T. LaPointe ◽  
Kevin J Sokoloski
Keyword(s):  
Growth Kinetics ◽  
Particle Production ◽  
Immune Cell ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Genomic Rnas ◽  
Viral Rnas ◽  
The Impact

Alphaviruses are positive-sense RNA arthropod-borne viruses that represent a significant threat to public health. During alphaviral replication, significant quantities of viral genomic RNAs that lack a canonical 5’ cap structure are produced and packaged into viral particles, despite the fact that the noncapped genomes cannot be translated and are essentially noninfectious. Previously, we have reported that the capping efficiency of nsP1, the alphaviral capping enzyme, of Sindbis virus (SINV) could be modulated via point mutation. It was found that increasing RNA capping efficiency led to decreased viral growth kinetics via decreased particle production, despite increased innate immune evasion, whereas decreasing capping efficiency led to wild-type growth kinetics and particle production. This led to the conclusion that the noncapped viral RNAs meaningfully contribute to the biology of alphaviral infections at the molecular level. To determine the importance of the noncapped viral RNAs in vivo, we characterized the impact of altered capping efficiency in a murine model of infection utilizing a neurovirulent strain of SINV. Mice infected with the nsP1 mutant with decreased capping exhibited wild-type rates of mortality, weight loss, and neurological symptoms. Conversely, the mice infected with the increased capping nsP1 mutant showed significantly reduced mortality and morbidity compared to mice infected with the wild-type virus. Interestingly, viral titers in the ankle, serum, and brain were equivalent between the wild-type virus and the two mutant viruses. Importantly, examination of the brain tissue revealed that mice infected with the increased capping mutant had significantly reduced immune cell infiltration and expression of proinflammatory cytokines compared to the decreased capping mutant and wild-type virus. Collectively, these data indicate that the noncapped viral RNAs have important roles during the early and late stages of alphaviral infection and suggest a novel mechanism by which noncapped viral RNA aids in viral pathogenesis.

scholarly journals Association of APOE4 and clinical variability in Alzheimer disease with the pattern of tau- and amyloid-PET

Neurology ◽  
2020 ◽  
pp. 10.1212/WNL.0000000000011270
Author(s):  
Renaud La Joie ◽  
Adrienne V. Visani ◽  
Orit H. Lesman-Segev ◽  
Suzanne L. Baker ◽  
Lauren Edwards ◽  
...  
Keyword(s):  
Alzheimer Disease ◽  
Linear Models ◽  
Rating Scale ◽  
Standardized Uptake Value ◽  
Cortical Atrophy ◽  
Amyloid Pet ◽  
Clinical Dementia Rating ◽  
Clinical Variables ◽  
Β Amyloid

ObjectiveTo assess whether Alzheimer disease (AD) clinical presentation and APOE4 relate to the burden and topography of β-amyloid and tau pathologies using in vivo PET imaging.MethodsWe studied 119 β-amyloid-positive symptomatic patients aged 48–95 years, including 29 patients with logopenic variant primary progressive aphasia (lvPPA) and 21 with Posterior Cortical Atrophy (PCA). PIB- (β-amyloid) and Flortaucipir (tau)-PET standardized uptake value ratio (SUVR) images were created. General linear models assessed relationships between demographic/clinical variables (phenotype, age), APOE4, and PET (including global cortical and voxelwise SUVR values) while controlling for disease severity using the clinical dementia rating scale sum of boxes.ResultsPIB-PET binding showed a widespread cortical distribution with subtle differences across phenotypes and was unrelated to demographic/clinical variables or APOE4. Flortaucipir-PET was commonly elevated in temporo-parietal regions, but showed marked phenotype-associated differences, with higher binding observed in occipito-parietal areas for PCA, in left temporal and inferior frontal for lvPPA, and in medial temporal areas for other patients with AD. Cortical Flortaucipir-PET binding was higher in younger patients across phenotypes (r = −0.63, 95%CI [−0.72, −0.50)]), especially in parietal and dorsal prefrontal cortices. The presence of APOE4 was associated with a focal medial temporal Flortaucipir-SUVR increase, controlling for all other variables (entorhinal: + 0.310 SUVR 95%CI [0.091, 0.530]).ConclusionsClinical phenotypes are associated with differential patterns of tau but not amyloid pathology. Older age and APOE4 are not only risk factors for AD but also seem to affect disease expression by promoting a more MTL-predominant pattern of tau pathology.

scholarly journals Distinct Tumor Microenvironments Are a Defining Feature of Strain-Specific CRISPR/Cas9-Induced MPNSTs

Genes ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 583 ◽  
Author(s):  
Amanda Scherer ◽  
Victoria R. Stephens ◽  
Gavin R. McGivney ◽  
Wade R. Gutierrez ◽  
Emily A. Laverty ◽  
...  
Keyword(s):  
Tumor Microenvironment ◽  
Mouse Models ◽  
Cancer Biology ◽  
Myeloid Cell ◽  
Inbred Strains ◽  
Peripheral Nerve Sheath Tumors ◽  
Tumor Onset ◽  
The Impact ◽  
Strain Dependent

The tumor microenvironment plays important roles in cancer biology, but genetic backgrounds of mouse models can complicate interpretation of tumor phenotypes. A deeper understanding of strain-dependent influences on the tumor microenvironment of genetically-identical tumors is critical to exploring genotype–phenotype relationships, but these interactions can be difficult to identify using traditional Cre/loxP approaches. Here, we use somatic CRISPR/Cas9 tumorigenesis approaches to determine the impact of mouse background on the biology of genetically-identical malignant peripheral nerve sheath tumors (MPNSTs) in four commonly-used inbred strains. To our knowledge, this is the first study to systematically evaluate the impact of host strain on CRISPR/Cas9-generated mouse models. Our data identify multiple strain-dependent phenotypes, including changes in tumor onset and the immune microenvironment. While BALB/c mice develop MPNSTs earlier than other strains, similar tumor onset is observed in C57BL/6, 129X1 and 129/SvJae mice. Indel pattern analysis demonstrates that indel frequency, type and size are similar across all genetic backgrounds. Gene expression and IHC analysis identify multiple strain-dependent differences in CD4+ T cell infiltration and myeloid cell populations, including M2 macrophages and mast cells. These data highlight important strain-specific phenotypes of genomically-matched MPNSTs that have implications for the design of future studies using similar in vivo gene editing approaches.

scholarly journals Long Term Pharmacological Perturbation of Autophagy in Mice: Are HCQ Injections a Relevant Choice?

Biomedicines ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 47 ◽  
Author(s):  
Jean-Daniel Masson ◽  
Benoit Blanchet ◽  
Baptiste Periou ◽  
François-Jérôme Authier ◽  
Baharia Mograbi ◽  
...  
Keyword(s):  
Mouse Models ◽  
In Vivo Studies ◽  
Loss Of Function ◽  
Evolutionarily Conserved ◽  
Atg Genes ◽  
Conditional Inhibition ◽  
The Impact ◽  
Catabolic Process

Macroautophagy (hereafter referred to as autophagy) is an evolutionarily conserved catabolic process whose loss-of-function has been linked to a growing list of pathologies. Knockout mouse models of key autophagy genes have been instrumental in the demonstration of the critical functions of autophagy, but they display early lethality, neurotoxicity and unwanted autophagy-independent phenotypes, limiting their applications for in vivo studies. To avoid problems encountered with autophagy-null transgenic mice, we investigated the possibility of disturbing autophagy pharmacologically in the long term. Hydroxychloroquine (HCQ) ip injections were done in juvenile and adult C57bl/6j mice, at range doses adapted from the human malaria prophylactic treatment. The impact on autophagy was assessed by western-blotting, and juvenile neurodevelopment and adult behaviours were evaluated for four months. Quite surprisingly, our results showed that HCQ treatment in conditions used in this study neither impacted autophagy in the long term in several tissues and organs nor altered neurodevelopment, adult behaviour and motor capabilities. Therefore, we recommend for future long-term in vivo studies of autophagy, to use genetic mouse models allowing conditional inhibition of selected Atg genes in appropriate lineage cells instead of HCQ treatment, until it could be successfully revisited using higher HCQ doses and/or frequencies with acceptable toxicity.

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