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2.
Mol Metab ; 85: 101959, 2024 Jul.
Article in English | MEDLINE | ID: mdl-38763496

ABSTRACT

OBJECTIVES: Aggregation and misfolding of amyloid beta (Aß) and tau proteins, suggested to arise from post-translational modification processes, are thought to be the main cause of Alzheimer's disease (AD). Additionally, a plethora of evidence exists that links metabolic dysfunctions such as obesity, type 2 diabetes (T2D), and dyslipidemia to the pathogenesis of AD. We thus investigated the combinatory effect of T2D and human glutaminyl cyclase activity (pyroglutamylation), on the pathology of AD and whether astaxanthin (ASX) treatment ameliorates accompanying pathophysiological manifestations. METHODS: Male transgenic AD mice, APPxhQC, expressing human APP751 with the Swedish and the London mutation and human glutaminyl cyclase (hQC) enzyme and their non-transgenic (NTG) littermates were used. Both APPxhQC and NTG mice were allocated to 3 groups, control, T2D-control, and T2D-ASX. Mice were fed control or high fat diet ± ASX for 13 weeks starting at an age of 11-12 months. High fat diet fed mice were further treated with streptozocin for T2D induction. Effects of genotype, T2D induction, and ASX treatment were evaluated by analysing glycemic readouts, lipid concentration, Aß deposition, hippocampus-dependent cognitive function and nutrient sensing using immunosorbent assay, ELISA-based assays, western blotting, immunofluorescence staining, and behavioral testing via Morris water maze (MWM), respectively. RESULTS: APPxhQC mice presented a higher glucose sensitivity compared to NTG mice. T2D-induced brain dysfunction was more severe in NTG compared to the APPxhQC mice. T2D induction impaired memory functions while increasing hepatic LC3B, ABCA1, and p65 levels in NTG mice. T2D induction resulted in a progressive shift of Aß from the soluble to insoluble form in APPxhQC mice. ASX treatment reversed T2D-induced memory dysfunction in NTG mice and in parallel increased hepatic pAKT while decreasing p65 and increasing cerebral p-S6rp and p65 levels. ASX treatment reduced soluble Aß38 and Aß40 and insoluble Aß40 levels in T2D-induced APPxhQC mice. CONCLUSIONS: We demonstrate that T2D induction in APPxhQC mice poses additional risk for AD pathology as seen by increased Aß deposition. Although ASX treatment reduced Aß expression in T2D-induced APPxhQC mice and rescued T2D-induced memory impairment in NTG mice, ASX treatment alone may not be effective in cases of T2D comorbidity and AD.


Subject(s)
Alzheimer Disease , Diabetes Mellitus, Type 2 , Mice, Transgenic , Xanthophylls , Animals , Diabetes Mellitus, Type 2/metabolism , Diabetes Mellitus, Type 2/drug therapy , Mice , Xanthophylls/pharmacology , Xanthophylls/metabolism , Male , Alzheimer Disease/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/genetics , Humans , Amyloid beta-Peptides/metabolism , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Diet, High-Fat/adverse effects , Mice, Inbred C57BL
3.
Brain Res ; 1819: 148518, 2023 11 15.
Article in English | MEDLINE | ID: mdl-37579986

ABSTRACT

Defective degradation and clearance of amyloid-ß as well as inflammation per se are crucial players in the pathology of Alzheimer's disease (AD). A defective transport across the blood-brain barrier is causative for amyloid-ß (Aß) accumulation in the brain, provoking amyloid plaque formation. Using primary porcine brain capillary endothelial cells and murine organotypic hippocampal slice cultures as in vitro models of AD, we investigated the effects of the antioxidant astaxanthin (ASX) on Aß clearance and neuroinflammation. We report that ASX enhanced the clearance of misfolded proteins in primary porcine brain capillary endothelial cells by inducing autophagy and altered the Aß processing pathway. We observed a reduction in the expression levels of intracellular and secreted amyloid precursor protein/Aß accompanied by an increase in ABC transporters ABCA1, ABCG1 as well as low density lipoprotein receptor-related protein 1 mRNA levels. Furthermore, ASX treatment increased autophagic flux as evidenced by increased lipidation of LC3B-II as well as reduced protein expression of phosphorylated S6 ribosomal protein and mTOR. In LPS-stimulated brain slices, ASX exerted anti-inflammatory effects by reducing the secretion of inflammatory cytokines while shifting microglia polarization from M1 to M2 phenotype. Our data suggest ASX as potential therapeutic compound ameliorating AD-related blood brain barrier impairment and inflammation.


Subject(s)
Alzheimer Disease , Mice , Animals , Swine , Alzheimer Disease/metabolism , Blood-Brain Barrier/metabolism , Amyloid beta-Peptides/metabolism , Endothelial Cells/metabolism , Amyloid beta-Protein Precursor/metabolism , Inflammation/drug therapy , Inflammation/metabolism , Autophagy , Anti-Inflammatory Agents/pharmacology , Anti-Inflammatory Agents/therapeutic use , Mice, Transgenic , Disease Models, Animal
4.
Front Neurosci ; 17: 1087788, 2023.
Article in English | MEDLINE | ID: mdl-37065917

ABSTRACT

Introduction: Autism spectrum disorder (ASD) is a persistent neurodevelopmental condition characterized by two core behavioral symptoms: impaired social communication and interaction, as well as stereotypic, repetitive behavior. No distinct cause of ASD is known so far; however, excitatory/inhibitory imbalance and a disturbed serotoninergic transmission have been identified as prominent candidates responsible for ASD etiology. Methods: The GABA B receptor agonist R-Baclofen and the selective agonist for the 5HT7 serotonin receptor LP-211 have been reported to correct social deficits and repetitive behaviors in mouse models of ASD. To evaluate the efficacy of these compounds in more details, we treated BTBR T+ Itpr3 tf /J and B6.129P2-Fmr1 tm1Cgr /J mice acutely with R-Baclofen or LP-211 and evaluated the behavior of animals in a series of tests. Results: BTBR mice showed motor deficits, elevated anxiety, and highly repetitive behavior of self-grooming. Fmr1-KO mice exhibited decreased anxiety and hyperactivity. Additionally, Fmr1-KO mice's ultrasonic vocalizations were impaired suggesting a reduced social interest and communication of this strain. Acute LP-211 administration did not affect the behavioral abnormalities observed in BTBR mice but improved repetitive behavior in Fmr1-KO mice and showed a trend to change anxiety of this strain. Acute R-Baclofen treatment improved repetitive behavior only in Fmr1-KO mice. Conclusion: Our results add value to the current available data on these mouse models and the respective compounds. Yet, additional studies are needed to further test R-Baclofen and LP-211 as potential treatments for ASD therapy.

6.
Biomolecules ; 12(3)2022 02 23.
Article in English | MEDLINE | ID: mdl-35327537

ABSTRACT

Parkinson's disease (PD) and dementia with Lewy bodies (DLB) are two common types of α-synucleinopathies and represent a high unmet medical need. Despite diverging clinical manifestations, both neurodegenerative diseases share several facets of their complex pathophysiology. Apart from α-synuclein aggregation, an impairment of mitochondrial functions, defective protein clearance systems and excessive inflammatory responses are consistently observed in the brains of PD as well as DLB patients. Leukotrienes are lipid mediators of inflammatory signaling traditionally known for their role in asthma. However, recent research advances highlight a possible contribution of leukotrienes, along with their rate-limiting synthesis enzyme 5-lipoxygenase, in the pathogenesis of central nervous system disorders. This review provides an overview of in vitro as well as in vivo studies, in summary suggesting that dysregulated leukotriene signaling is involved in the pathological processes underlying PD and DLB. In addition, we discuss how the leukotriene signaling pathway could serve as a future drug target for the therapy of PD and DLB.


Subject(s)
Lewy Body Disease , Parkinson Disease , Synucleinopathies , Brain/metabolism , Humans , Leukotrienes , Parkinson Disease/pathology , Signal Transduction , alpha-Synuclein/metabolism
7.
Int J Mol Sci ; 22(24)2021 Dec 09.
Article in English | MEDLINE | ID: mdl-34948052

ABSTRACT

Niemann-Pick type C disease (NPC) is a rare inherited neurodegenerative disorder characterized by an accumulation of intracellular cholesterol within late endosomes and lysosomes due to NPC1 or NPC2 dysfunction. In this work, we tested the hypothesis that retromer impairment may be involved in the pathogenesis of NPC and may contribute to increased amyloidogenic processing of APP and enhanced BACE1-mediated proteolysis observed in NPC disease. Using NPC1-null cells, primary mouse NPC1-deficient neurons and NPC1-deficient mice (BALB/cNctr-Npc1m1N), we show that retromer function is impaired in NPC. This is manifested by altered transport of the retromer core components Vps26, Vps35 and/or retromer receptor sorLA and by retromer accumulation in neuronal processes, such as within axonal swellings. Changes in retromer distribution in NPC1 mouse brains were observed already at the presymptomatic stage (at 4-weeks of age), indicating that the retromer defect occurs early in the course of NPC disease and may contribute to downstream pathological processes. Furthermore, we show that cholesterol depletion in NPC1-null cells and in NPC1 mouse brains reverts retromer dysfunction, suggesting that retromer impairment in NPC is mechanistically dependent on cholesterol accumulation. Thus, we characterized retromer dysfunction in NPC and propose that the rescue of retromer impairment may represent a novel therapeutic approach against NPC.


Subject(s)
Cholesterol/metabolism , Loss of Function Mutation , Neurons/metabolism , Niemann-Pick C1 Protein/genetics , Niemann-Pick Disease, Type C/genetics , Animals , CHO Cells , Cells, Cultured , Cricetulus , Disease Models, Animal , Female , Humans , Male , Membrane Transport Proteins/metabolism , Mice , Neurons/cytology , Niemann-Pick Disease, Type C/metabolism , Primary Cell Culture , Receptors, LDL/metabolism , Vesicular Transport Proteins/metabolism
8.
Int J Mol Sci ; 22(21)2021 Oct 30.
Article in English | MEDLINE | ID: mdl-34769222

ABSTRACT

Compelling evidence suggests that pyroglutamate-modified Aß (pGlu3-Aß; AßN3pG) peptides play a pivotal role in the development and progression of Alzheimer's disease (AD). Approaches targeting pGlu3-Aß by glutaminyl cyclase (QC) inhibition (Varoglutamstat) or monoclonal antibodies (Donanemab) are currently in clinical development. Here, we aimed at an assessment of combination therapy of Varoglutamstat (PQ912) and a pGlu3-Aß-specific antibody (m6) in transgenic mice. Whereas the single treatments at subtherapeutic doses show moderate (16-41%) but statistically insignificant reduction of Aß42 and pGlu-Aß42 in mice brain, the combination of both treatments resulted in significant reductions of Aß by 45-65%. Evaluation of these data using the Bliss independence model revealed a combination index of ≈1, which is indicative for an additive effect of the compounds. The data are interpreted in terms of different pathways, in which the two drugs act. While PQ912 prevents the formation of pGlu3-Aß in different compartments, the antibody is able to clear existing pGlu3-Aß deposits. The results suggest that combination of the small molecule Varoglutamstat and a pE3Aß-directed monoclonal antibody may allow a reduction of the individual compound doses while maintaining the therapeutic effect.


Subject(s)
Alzheimer Disease , Aminoacyltransferases/antagonists & inhibitors , Amyloid beta-Peptides/metabolism , Antibodies, Monoclonal, Murine-Derived/pharmacology , Benzimidazoles/pharmacology , Imidazolines/pharmacology , Peptide Fragments/metabolism , Alzheimer Disease/drug therapy , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/genetics , Animals , Humans , Mice , Mice, Transgenic , Peptide Fragments/genetics
9.
Alzheimers Res Ther ; 13(1): 175, 2021 10 16.
Article in English | MEDLINE | ID: mdl-34656177

ABSTRACT

BACKGROUND: To better understand the etiology and pathomechanisms of Alzheimer's disease, several transgenic animal models that overexpress human tau or human amyloid-beta (Aß) have been developed. In the present study, we generated a novel transgenic rat model by cross-breeding amyloid precursor protein (APP) rats with tau rats. We characterized this model by performing positron emission tomography scans combined with immunofluorescent labeling and cerebrospinal fluid analyses. METHODS: APP/Tau rats were generated by cross-breeding male McGill-R-Thy1-APP transgenic rats with female hTau-40/P301L transgenic rats. APP/Tau double transgenic rats and non-transgenic (ntg) littermates aged 7, 13, and 21 months were subjected to dynamic [11C] PiB scan and dynamic [18F]THK-5317 scans. For regional brain analysis, a template was generated from anatomical MR images of selected animals, which was co-registered with the PET images. Regional analysis was performed by application of the simplified reference tissue model ([11C]PiB data), whereas [18F]THK-5317 data were analyzed using a 2-tissue compartment model and Logan graphical analysis. In addition, immunofluorescent labeling (tau, amyloid) and cerebrospinal fluid analyses were performed. RESULTS: [11C]PiB binding potential (BPND) and [18F]THK-5317 volume of distribution (VT) showed an increase with age in several brain regions in the APP/Tau group but not in the ntg control group. Immunohistochemical analysis of brain slices of PET-scanned animals revealed a positive correlation between Aß labeling and [11C]PiB regional BPND. Tau staining yielded a trend towards higher levels in the cortex and hippocampus of APP/Tau rats compared with ntg littermates, but without reaching statistical significance. No correlation was found between tau immunofluorescence labeling results and the respective [18F]THK-5317 VT values. CONCLUSIONS: We thoroughly characterized a novel APP/Tau rat model using combined PET imaging and immunofluorescence analysis. We observed an age-related increase in [11C]PiB and [18F]THK-5317 binding in several brain regions in the APP/Tau group but not in the ntg group. Although we were able to reveal a positive correlation between amyloid labeling and [11C]PiB regional brain uptake, we observed relatively low human tau and amyloid fibril expression levels and a somewhat unstable brain pathology which questions the utility of this animal model for further studies.


Subject(s)
Alzheimer Disease , Alzheimer Disease/diagnostic imaging , Alzheimer Disease/genetics , Amyloid beta-Peptides , Amyloid beta-Protein Precursor/genetics , Animals , Female , Male , Positron-Emission Tomography , Rats , Rats, Transgenic
10.
Front Mol Neurosci ; 14: 681868, 2021.
Article in English | MEDLINE | ID: mdl-34248499

ABSTRACT

Amyotrophic lateral sclerosis (ALS) still depicts an incurable and devastating disease. Drug development efforts are mostly based on superoxide dismutase 1 gene (SOD1)-G93A mice that present a very strong and early phenotype, allowing only a short time window for intervention. An alternative mouse model is available, that is based on the same founder line but has a reduced SOD1-G93A copy number, resulting in a weaker and delayed phenotype. To be able to use these SOD1-G93A/low mice for drug testing, we performed a characterization of ALS-typical pathologies. All analyses were performed compared to non-transgenic (ntg) littermates of the same sex and age. In vivo analysis of SOD1-G93A/low mice was performed by weekly body weight measurements, analysis of the survival rate, and measurement of the muscle strength of 24-30 weeks old female and male SOD1-G93A/low mice. Immunofluorescent labeling of SOD1, glial fibrillary acidic protein (GFAP), and ionized calcium-binding adaptor molecule 1 (Iba1) protein was performed in the cervical, thoracic, and lumbar ventral horn of the spinal cord of 24-30 weeks old male and female SOD1-G93A/low mice. The musculus gastrocnemius of male SOD1-G93A/low mice was labeled with fluorophore-conjugated α-bungarotoxin and antibodies against phosphorylated neurofilaments. Fluorescent labeling was detected and quantified by macro-based image analysis. Although SOD1 protein levels were highly increased in both sexes and all age groups, levels strongly peaked in 30 weeks old male SOD1-G93A/low mice. Astrocytosis and activated microglia in the spinal cord ventral horn and phosphorylated neurofilaments in the motor unit of the musculus gastrocnemius progressively increased, while muscle strength progressively decreased in male SOD1-G93A/low mice. In female SOD1-G93A/low mice, only activated microglia increased progressively, while muscle strength was constantly reduced starting at 26 weeks. These differences result in a shorter survival time of male SOD1-G93A/low mice of about 3 weeks compared to female animals. The results suggest that male SOD1-G93A/low mice present a stronger pathology and are, therefore, better suitable to evaluate the efficacy of new drugs against ALS as most pathological features are developing progressively paralleled by a survival time that allows treatment to start before symptom onset.

11.
Int J Mol Sci ; 22(5)2021 Mar 09.
Article in English | MEDLINE | ID: mdl-33803482

ABSTRACT

Alzheimer's disease (AD) is the most common form of dementia. In particular, neuroinflammation, mediated by microglia cells but also through CD8+ T-cells, actively contributes to disease pathology. Leukotrienes are involved in neuroinflammation and in the pathological hallmarks of AD. In consequence, leukotriene signaling-more specifically, the leukotriene receptors-has been recognized as a potential drug target to ameliorate AD pathology. Here, we analyzed the effects of the leukotriene receptor antagonist montelukast (MTK) on hippocampal gene expression in 5xFAD mice, a commonly used transgenic AD mouse model. We identified glial activation and neuroinflammation as the main pathways modulated by MTK. The treatment increased the number of Tmem119+ microglia and downregulated genes related to AD-associated microglia and to lipid droplet-accumulating microglia, suggesting that the MTK treatment targets and modulates microglia phenotypes in the disease model compared to the vehicle. MTK treatment further reduced infiltration of CD8+T-cells into the brain parenchyma. Finally, MTK treatment resulted in improved cognitive functions. In summary, we provide a proof of concept for MTK to be a potential drug candidate for AD and provide novel modes of action via modulation of microglia and CD8+ T-cells. Of note, 5xFAD females showed a more severe pathology, and in consequence, MTK treatment had a more pronounced effect in the females compared to the males. The effects on neuroinflammation, i.e., microglia and CD8+ T-cells, as well as the effects on cognitive outcome, were dose-dependent, therefore arguing for the use of higher doses of MTK in AD clinical trials compared to the approved asthma dose.


Subject(s)
Acetates/pharmacology , Alzheimer Disease/drug therapy , Brain/metabolism , CD8-Positive T-Lymphocytes/metabolism , Cognition/drug effects , Cyclopropanes/pharmacology , Leukotriene Antagonists/pharmacology , Quinolines/pharmacology , Sulfides/pharmacology , Alzheimer Disease/genetics , Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Animals , Brain/pathology , CD8-Positive T-Lymphocytes/pathology , Inflammation/drug therapy , Inflammation/metabolism , Inflammation/pathology , Mice , Mice, Transgenic
12.
J Alzheimers Dis ; 80(3): 1151-1168, 2021.
Article in English | MEDLINE | ID: mdl-33646155

ABSTRACT

BACKGROUND: Preclinical Alzheimer's disease (AD) research strongly depends on transgenic mouse models that display major symptoms of the disease. Although several AD mouse models have been developed representing relevant pathologies, only a fraction of available mouse models, like the Tg4-42 mouse model, display hippocampal atrophy caused by the death of neurons as the key feature of AD. The Tg4-42 mouse model is therefore very valuable for use in preclinical research. Furthermore, metabolic biomarkers which have the potential to detect biochemical changes, are crucial to gain deeper insights into the pathways, the underlying pathological mechanisms and disease progression. OBJECTIVE: We thus performed an in-depth characterization of Tg4-42 mice by using an integrated approach to analyze alterations of complex biological networks in this AD in vivo model. METHODS: Therefore, untargeted NMR-based metabolomic phenotyping was combined with behavioral tests and immunohistological and biochemical analyses. RESULTS: Our in vivo experiments demonstrate a loss of body weight increase in homozygous Tg4-42 mice over time as well as severe impaired learning behavior and memory deficits in the Morris water maze behavioral test. Furthermore, we found significantly altered metabolites in two different brain regions and metabolic changes of the glutamate/4-aminobutyrate-glutamine axis. Based on these results, downstream effects were analyzed showing increased Aß42 levels, increased neuroinflammation as indicated by increased astro- and microgliosis as well as neuronal degeneration and neuronal loss in homozygous Tg4-42 mice. CONCLUSION: Our study provides a comprehensive characterization of the Tg4-42 mouse model which could lead to a deeper understanding of pathological features of AD. Additionally this study reveals changes in metabolic biomarker which set the base for future preclinical studies or drug development.


Subject(s)
Alzheimer Disease/metabolism , Alzheimer Disease/pathology , Amyloid beta-Peptides/genetics , Disease Models, Animal , Animals , Humans , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Phenotype
13.
Brain Res ; 1761: 147396, 2021 Mar 02.
Article in English | MEDLINE | ID: mdl-33662341

ABSTRACT

Huntington's disease is known to be a purely genetic disease based on an expansion of a CAG base triplet repeat in the coding region of the Huntingtin gene. Some years ago, researchers were able to introduce the extensive full-length gene sequence of the mutant huntingtin gene into a rodent model. The resulting BACHD rat is already well characterized for behavioral deficits. So far, all analyses in this preclinical rat model were performed in male hemizygous animals. As homozygosity of transgenic models often causes an amplification of the phenotype and female HD patients present a stronger phenotype compared to men, we established a homozygous breeding colony and tested 2 and 5 months old homozygous male and female BACHD rats in a behavioral test battery. The tests included the grip strength test, Rota Rod, elevated plus maze, passive avoidance, and Barnes maze test. Our results show strong deficits in young female homozygous BACHD rats including increased body weight, motor deficits, muscle weakness, reduced anxiety and hypoactivity, as well as learning and memory deficits. Analysis of male homozygous BACHD rats showed only weak disease symptoms, similar compared to male hemizygous BACHD rats of already published studies. Evaluation of the breeding success showed that homozygous BACHD have a reduced number of pups at the time of birth that even decreases until weaning. Our results suggest that the phenotype of homozygous male BACHD rats barely differs from already published results of hemizygous BACHD rats while female homozygous BACHD rats display strong and early alterations.

14.
Pharmaceutics ; 13(1)2020 Dec 23.
Article in English | MEDLINE | ID: mdl-33374646

ABSTRACT

The leukotriene receptor antagonist Montelukast (MTK) is an approved medication for the treatment of asthma and allergic rhinitis. The existing marketed tablet forms of MTK exhibit inconsistent uptake and bioavailability, which partially explains the presence of a significant proportion of MTK low- and non-responders in the population. Besides that, tablets are suboptimal formulations for patients suffering from dysphagia, for example, seen in patients with neurodegenerative diseases such as Alzheimer's disease, a disease with increasing interest in repurposing of MTK. This, and the need for an improved bioavailability, triggered us to reformulate MTK. Our aim was to develop a mucoadhesive MTK film with good safety and improved pharmacological features, i.e., an improved bioavailability profile in humans as well as in a mouse model of Alzheimer's disease. We tested dissolution of the MTK mucoadhesive film and assessed pharmacoexposure and kinetics after acute and chronic oral application in mice. Furthermore, we performed a Phase I analysis in humans, which included a comparison with the marketed tablet form as well as a quantitative analysis of the MTK levels in the cerebrospinal fluid. The novel MTK film demonstrated significantly improved bioavailability compared to the marketed tablet in the clinical Phase 1a study. Furthermore, there were measurable amounts of MTK present in the cerebrospinal fluid (CSF). In mice, MTK was detected in serum and CSF after acute and chronic exposure in a dose-dependent manner. The mucoadhesive film of MTK represents a promising alternative for the tablet delivery. The oral film might lower the non-responder rate in patients with asthma and might be an interesting product for repurposing of MTK in other diseases. As we demonstrate Blood-Brain-Barrier (BBB) penetrance in a preclinical model, as well as in a clinical study, the oral film of MTK might find its use as a therapeutic for acute and chronic neurodegenerative diseases such as dementias and stroke.

15.
Front Mol Neurosci ; 13: 136, 2020.
Article in English | MEDLINE | ID: mdl-32982685

ABSTRACT

Excessive tau phosphorylation is the hallmark of tauopathies. Today's research thus focusses on the development of drugs targeting this pathological feature. To test new drugs in preclinical studies, animal models are needed that properly mimic this pathological hallmark. The htau mouse is a well-known model expressing human but lacking murine tau, allowing to evaluate the efficacy of tau modifying compounds without interference from murine tau. Htau mice are well-characterized for tau pathology at older age, although it is often not specified on which genetic background analyzed animals were bred. Since it was shown that the genetic background can influence the pathology, we evaluated the phosphorylation status of young and adult htau mice on a C57BL/6J background by analyzing ptau Ser202 and ptau Ser396 levels in the cortex and hippocampus of 3 and 12 month old animals by immunofluorescent labelling. Additionally, we evaluated total tau, ptau Thr231 and ptau Thr181 in the soluble and insoluble brain fraction of 3-15 month old htau mice by immunosorbent assay. Our results show that ptau levels of all analyzed residues and age groups are similar without strong increases over age. These data show that tau is already phosphorylated at the age of 3 months suggesting that phosphorylation starts even earlier. The early start of tau phosphorylation in htau mice enables the use of these mice for efficacy studies already at very young age.

16.
PLoS One ; 15(7): e0235543, 2020.
Article in English | MEDLINE | ID: mdl-32645028

ABSTRACT

Senile plaques frequently contain Aß-pE(3), a N-terminally truncated Aß species that is more closely linked to AD compared to other Aß species. Tau protein is highly phosphorylated at several residues in AD, and specifically phosphorylation at Ser202/Thr205 is known to be increased in AD. Several studies suggest that formation of plaques and tau phosphorylation might be linked to each other. To evaluate if Aß-pE(3) and ptau Ser202/Thr205 levels correlate in human and transgenic AD mouse models, we analyzed human cortical and hippocampal brain tissue of different Braak stages as well as murine brain tissue of two transgenic mouse models for levels of Aß-pE(3) and ptau Ser202/Thr205 and correlated the data. Our results show that Aß-pE(3) formation is increased at early Braak stages while ptau Ser202/Thr205 mostly increases at later stages. Further analyses revealed strongest correlations between the two pathologies in the temporal, frontal, cingulate, and occipital cortex, however correlation in the hippocampus was weaker. Evaluation of murine transgenic brain tissue demonstrated a slow but steady increase of Aß-pE(3) from 6 to 12 months of age in the cortex and hippocampus of APPSL mice, and a very early and strong Aß-pE(3) increase in 5xFAD mice. ptau Ser202/Thr205 levels increased at the age of 9 months in APPSL mice and at 6 months in 5xFAD mice. Our results show that Aß-pE(3) and ptau Ser202/Thr205 levels strongly correlate in human as well as murine tissues, suggesting that tau phosphorylation might be amplified by Aß-pE(3).


Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/metabolism , Brain/metabolism , tau Proteins/metabolism , Aged , Aged, 80 and over , Alzheimer Disease/genetics , Alzheimer Disease/pathology , Amyloid beta-Peptides/chemistry , Amyloid beta-Peptides/genetics , Animals , Brain/pathology , Disease Models, Animal , Female , Humans , Male , Mice , Middle Aged , Phosphorylation , Pyrrolidonecarboxylic Acid/chemistry , Species Specificity , tau Proteins/genetics
17.
Front Neurosci ; 14: 579, 2020.
Article in English | MEDLINE | ID: mdl-32595447

ABSTRACT

Neurofilament-light chain (NF-L) is a well-known clinical biomarker of many neurodegenerative diseases. By analyzing amyotrophic lateral sclerosis (ALS) patients cerebrospinal fluid (CSF) or plasma, progression of NF-L levels can forecast conversion from the presymptomatic to symptomatic stage and time of survival. The use of plasma for NF-L measurement makes this biomarker exceptionally valuable for clinical studies since sample collection can be performed repeatedly without causing much harm. Detailed analyses of NF-L expression in neurodegenerative disease patient's samples were already performed, while NF-L levels of preclinical models of ALS, Alzheimer's and Parkinson's disease as well as lysosomal storage diseases are still widely unknown. We therefore evaluated NF-L levels in the plasma of the ALS models SOD1-G93A low expressor and TAR6/6 mice, the Alzheimer's disease (AD) model 5xFAD, the Parkinson's disease model Line 61 and the Gaucher disease (GD) model 4L/PS-NA and the CSF of selected models. Our results show that NF-L levels are highly increased in the plasma of ALS, Alzheimer's and GD models, while in the analyzed Parkinson's disease model NF-L plasma levels barely changed. Most analyzed models show a progressive increase of NF-L levels. NF-L measurements in the plasma of the neurodegenerative disease mouse models of ALS and AD are thus a good tool to evaluate disease progression. Compared to analyses in human tissues, our results suggest a high translation value of murine NF-L levels and their progression. Furthermore, our data indicate that NF-L might also be a good biomarker for disorders with a neuronal component like some lysosomal storage diseases.

18.
Sci Rep ; 10(1): 6377, 2020 04 14.
Article in English | MEDLINE | ID: mdl-32286473

ABSTRACT

Alzheimer's disease can be modelled by different transgenic mouse strains. To gain deeper insight into disease model mechanisms, the previously described Tg4-42 mouse was analysed for transgene integration. On RNA/DNA level the transgene integration resulted in more than 20 copy numbers and further caused a deletion of exon 2 of the retinoic acid receptor beta. These findings were also confirmed on protein level with highly decreased retinoic acid receptor beta protein levels in homozygous Tg4-42 mice and may have an impact on the previously described phenotype of homozygous Tg4-42 mice to be solely dependent on amyloid-ß 4-42 expression. Since hemizygous mice show no changes in RARB protein levels it can be concluded that the previously described phenotype of these mice should not be affected by the retinoic acid receptor beta gene knockout. In order to fully understand the results of transgenesis, it is extremely advisable to determine the genome integration site and the basic structure of the inserted transgenes. This can be carried out for instance by next-generation sequencing techniques. Our results thus suggest that a detailed characterization of new disease models using the latest genomics technologies prior to functional studies could be a valuable tool to avoid an unexpected genetic influence on the animals' phenotype that is not only based on the inserted transgene. This would also significantly improve the selection of mouse models that are best suited for therapeutic development and basic research.


Subject(s)
Alzheimer Disease/genetics , Brain/metabolism , Disease Models, Animal , Receptors, Retinoic Acid/metabolism , Transgenes , Animals , Down-Regulation , Homozygote , Mice , Mice, Transgenic , Phenotype
19.
Neurotherapeutics ; 17(3): 1061-1074, 2020 07.
Article in English | MEDLINE | ID: mdl-32072462

ABSTRACT

Dementia with Lewy bodies (DLB) represents a huge medical need as it accounts for up to 30% of all dementia cases, and there is no cure available. The underyling spectrum of pathology is complex and creates a challenge for targeted molecular therapies. We here tested the hypothesis that leukotrienes are involved in the pathology of DLB and that blocking leukotrienes through Montelukast, a leukotriene receptor antagonist and approved anti-asthmatic drug, might alleviate pathology and restore cognitive functions. Expression of 5-lipoxygenase, the rate-limiting enzyme for leukotriene production, was indeed elevated in brains with DLB. Treatment of cognitively deficient human alpha-synuclein overexpressing transgenic mice with Montelukast restored memory. Montelukast treatment resulted in modulation of beclin-1 expression, a marker for autophagy, and in a reduction in the human alpha-synulcein load in the transgenic mice. Reducing the protein aggregation load in neurodegenerative diseases might be a novel model of action of Montelukast. Moreover, this work presents leukotriene signaling as a potential drug target for DLB and shows that Montelukast might be a promising drug candidate for future DLB therapy development.


Subject(s)
Acetates/therapeutic use , Cyclopropanes/therapeutic use , Leukotriene Antagonists/therapeutic use , Lewy Body Disease/drug therapy , Memory/drug effects , Quinolines/therapeutic use , Receptors, Leukotriene , Sulfides/therapeutic use , alpha-Synuclein/antagonists & inhibitors , Acetates/pharmacology , Animals , Cyclopropanes/pharmacology , Disease Models, Animal , Female , Humans , Leukotriene Antagonists/pharmacology , Lewy Body Disease/genetics , Lewy Body Disease/metabolism , Memory/physiology , Memory Disorders/drug therapy , Memory Disorders/genetics , Memory Disorders/metabolism , Mice , Mice, Transgenic , Quinolines/pharmacology , Receptors, Leukotriene/genetics , Receptors, Leukotriene/metabolism , Sulfides/pharmacology , alpha-Synuclein/genetics , alpha-Synuclein/metabolism
20.
Nucl Med Biol ; 84-85: 28-32, 2020.
Article in English | MEDLINE | ID: mdl-31981857

ABSTRACT

INTRODUCTION: Tau deposition is one of the hallmarks of Alzheimer's disease (AD) and can be visualized and quantified using [18F]THK-5317 together with kinetic modeling. To determine the feasibility of this approach, we measured blood/plasma pharmacokinetics and radiotracer metabolism in female and male rats. METHODS: Female and male rats (n = 11-12) were cannulated via the femoral artery for continuous blood sampling. Blood sampling was performed at regular intervals after intravenous injection of [18F]THK-5317. After collection of the last blood sample, animals were sacrificed, and organs were excised. Blood from minute 5, 20 and 60 was centrifuged to obtain plasma. Radiolabeled metabolites in plasma, brain, liver and urine were analyzed by radio-thin-layer chromatography (radio-TLC). RESULTS: Plasma pharmacokinetics and metabolism were significantly different between female and male rats. [18F]THK-5317 plasma clearance was faster in female (0.66 ± 0.08 mL/h/kg BW) than in male (0.52 ± 0.11 mL/h/kg BW) rats (p = .005). The percentage of unmetabolized parent was significantly different between both sexes at 20 min and 60 min p.i. In the liver, a 1.6-fold higher radioactivity concentration was found in male versus female animals and in addition also the percentage of unmetabolized parent was different. CONCLUSION: Our results show pronounced sex differences in blood/plasma pharmacokinetics and metabolism of [18F]THK-5317 in rats. Female animals showed a faster plasma clearance compared to males. These results underline the importance of investigating both sexes and also support the notion that individual input functions or sex-specific population-based input functions are needed for kinetic modeling analyses. ADVANCES IN KNOWLEDGE: First preclinical study in rats showing pronounced sex differences in blood/plasma pharmacokinetics and metabolism of [18F]THK-5317. IMPLICATIONS FOR PATIENT CARE: Sex-specific differences might also be present in humans and thus clinical trials should have adequate sample size to account for effects in men and women separately.


Subject(s)
Aniline Compounds/pharmacokinetics , Quinolines/pharmacokinetics , Sex Characteristics , Alzheimer Disease/metabolism , Aniline Compounds/blood , Aniline Compounds/metabolism , Animals , Female , Male , Quinolines/blood , Quinolines/metabolism , Radioactive Tracers , Rats , Tissue Distribution , tau Proteins/metabolism
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