Selective suppression of the α isoform of p38 MAPK rescues late-stage tau pathology

BACKGROUND: Hyperphosphorylation and aggregation of tau protein are the pathological hallmarks of Alzheimer's disease and related tauopathies. We previously demonstrated that the microglial activation induces tau hyperphosphorylation and cognitive impairment via activation of p38 mitogen-activated protein kinase (p38 MAPK) in the hTau mouse model of tauopathy that was deficient for microglial fractalkine receptor CX3CR1. METHOD: We report an isoform-selective, brain-permeable, and orally bioavailable small molecule inhibitor of p38α MAPK (MW181) and its effects on tau phosphorylation in vitro and in hTau mice. RESULTS: First, pretreatment of mouse primary cortical neurons with MW181 completely blocked inflammation-induced p38α MAPK activation and AT8 (pS199/pS202) site tau phosphorylation, with the maximum effect peaking at 60-90 min after stimulation. Second, treatment of old (~20 months of age) hTau mice with MW181 (1 mg/kg body weight; 14 days via oral gavage) significantly reduced p38α MAPK activation compared with vehicle-administered hTau mice. This also resulted in a significant reduction in AT180 (pT231) site tau phosphorylation and Sarkosyl-insoluble tau aggregates. Third, MW181 treatment significantly increased synaptophysin protein expression and resulted in improved working memory. Fourth, MW181 administration reduced phosphorylated MAPK-activated protein kinase 2 (pMK2) and phosphorylated activating transcription factor 2 (pATF2), which are known substrates of p38α MAPK. Finally, MW181 reduced the expression of interferon-γ and interleukin-1β. CONCLUSIONS: Taken together, these studies support p38α MAPK as a valid therapeutic target for the treatment of tauopathies

Alcohol Consumption During Early Adulthood in a Preclinical Mouse Model of Alzheimer’s Disease Leads to Gait Impairments, Dysregulated Circadian Rhythm, Alterations in Tauopathy and Brain-Region-Specific Transcriptional Alterations

Alzheimer’s disease (AD) is a leading cause of cognitive dysfunction and death in the US attributable in part to the accumulation and spread of pathologically modified tau (pTau). Recently, excessive alcohol use, particularly binge drinking, has emerged as a risk factor for the development of AD. However, the neurobiological consequences underlying how excessive alcohol exposure might lead to the accumulation and/or progression of pTau and associated neurobehavioral deficits has not been fully explored. We used the binge-alcohol drinking paradigm, ‘drinking-in-the-dark’ (DID), in the P301S mouse model of tauopathy to test the hypothesis that excessive voluntary alcohol consumption during young adulthood would exacerbate pTau-induced alterations in behavioral decline as a consequence of the recruitment of unique neurobiological genes/gene networks. We found that excessive alcohol use in the P301S mice altered the presentation of pTau, shortened circadian rhythm, impaired right hind paw gait characteristics, and led to brain-region-specific transcriptional alterations. Of particular interest, we identified a well-characterized thyroid transport gene, Transthyretin (Ttr), recently found to regulate microtubule dynamics and has a strong connection to Alzheimer’s, that was downregulated in the hippocampus of alcohol consuming P301S males compared with alcohol consuming male nTg littermates. These findings support alcohol consumption as a factor that interacts with pTau and pTau-associated behavioral decline as well as reveals some potential targetable neurobiological mechanisms underlying these changes

The Development, but not Expression, of Alcohol Front-loading in C57BL/6J Mice Maintained on LabDiet 5001 is Abolished by Maintenance on Teklad 2920x Rodent Diet

AbstractExcessive alcohol (ethanol) consumption, such as binge-drinking, is extremely commonplace and represents a major health concern. Through modeling excessive drinking in rodents, we are beginning to uncover the neurobiological and neurobehavioral causes and consequences of this pattern of ethanol intake. One important factor for modeling binge drinking in mice is that subjects reliably drink to blood ethanol concentrations (BECs) of 80 mg/dl or higher. Drinking-in-the-dark (DID) is a commonly used mouse model of binge drinking, and we have shown these methods reliably result in robust ethanol front-loading and binge-level BECs in C57BL/6J (B6) mice as well as other ethanol-preferring mouse strains/lines. However, establishing the DID model in a new vivarium space forced us to consider the use of rodent diet formulations we had not previously used. The current set of experiments were designed to investigate the role of two standard rodent diet formulations on binge drinking and the development of ethanol front-loading using DID. We found that BECs in animals maintained on LabDiet 5001 (LD01) were double those found in mice maintained on Teklad 2920x (TL20). Interestingly, this effect was paralleled by differences in the degree of front-loading, such that LD01-fed mice consumed approximately twice as much ethanol in the first 15 minutes of the 2-hour DID sessions compared to TL20-fed mice. Surprisingly however, mice that developed front-loading during maintenance on the LD01 diet continued to display front-loading behavior after being switched to the TL20 diet. These data emphasize the importance of choosing and reporting diet formulations when conducting voluntary drinking studies and support the need for further investigation into the mechanisms behind diet-induced differences in binge drinking, particularly front-loading.</jats:p

pT181-Qß VLP-based vaccine against tau pathology shows robust immune response and functional efficacy in the P301S mouse model of tauopathy

Background: Tauopathies are progressive neurodegenerative disorders characterized by the hyperphosphorylation of tau and development of intracellular neurofibrillary tangles, collectively referred to as pathological tau (pTau). It is becoming increasingly recognized that the development and spread of pTau accurately predicts and correlates with clinical progression in human tauopathy patients, however there are no FDA-approved drugs that target and reduce pTau. Previously, our lab has developed a virus-like particle (VLP)-based vaccine using a Qß (RNA bacteriophage) platform to multivalently display a 13-mer pTau peptide, with phospho-Thr181 (pT181, a well-established CSF biomarker for tauopathies). pT181-Qß generates a robust and targeted immune response against pTau in a model of tauopathy, rTg4510, resulting in reduced insoluble tau, decreased neurodegeneration and improved delay-dependent and spatial memory. Here, we sought to expand the effects of this vaccine in an additional model of tauopathy, at a more clinically relevant intervention. Methods: We immunized P301S (and non transgenic) mice twice, at 3 and 4 months of age. Next, we assessed anti-pT181 antibody titers at 1-week after the first injection and 5-months following the last injection (9 months). Finally we performed magnetic resonance imaging (MRI) and behavioral analysis prior to biochemical analysis. Results: Anti-pT181 antibodies were significantly elevated in all mice treated with pT181-Qß, regardless of genotype, 1 week after the first dose and remained elevated five months after the second injection. In addition to a clear prevention of neurodegeneration in the cortex via T2 MRI, using diffusion tensor imaging, we observed increases in axonal integrity via axial diffusivity in the corpus callosum, a major white matter tract in the brain in the pT181-Qβ-vaccinated P301S mice vs. the control treated mice, hinting at an amelioration in tau-mediated axonal damage. Behavioral analysis suggest that pT1818-Qß-vaccinated P301S mice showed gait improvement (as assessed with Catwalk). Finally, P301S mice vaccinated with pT181-Qß had significantly downregulated gene expression of inflammasome components and significantly reduced tau hyperphopsphorylation in the hippocampus, hinting at an intimate connection between neuroinflammatiom and pathological tau accumulation. Conclusions: This vaccine represents an efficacious and cutting-edge tool to target and reduce tau pathology in multiple animal models of tauopathy which may have substantial effects on neuroinflammation and white matter integrity

Photoreceptor degeneration, azoospermia, leukoencephalopathy, and abnormal RPE cell function in mice expressing an early stop mutation in CLCN2.

PURPOSE: To determine the molecular basis and the pathologic consequences of a chemically induced mutation in a mouse model of photoreceptor degeneration, nmf240. METHODS: Mice from a G3 N-ethyl-N-nitrosourea mutagenesis program were screened by indirect ophthalmoscopy for abnormal fundi. A chromosomal position for the recessive nmf240 mutation was determined by a genome-wide linkage analysis by use of simple sequence length polymorphic markers in an F2 intercross. The critical region was refined, and candidate genes were screened by direct sequencing. The nmf240 phenotype was characterized by histologic analysis of the retina, brain, and male reproductive organs and by electroretinogram (ERG)-based studies of the retina and retinal pigment epithelium (RPE). RESULTS: Clinically, homozygous nmf240 mutants exhibit a grainy retina that progresses to panretinal patches of depigmentation. The mutation was localized to a region on chromosome 16 containing Clcn2, a gene associated with retinal degeneration. Sequencing identified a missense C-T mutation at nucleotide 1063 in Clcn2 that converts a glutamine to a stop codon. Mice homozygous for the Clcn2(nmf240) mutation experience a severe loss of photoreceptor cells at 14 days of age that is preceded by an elongation of RPE apical microvilli. Homozygous mutants also experience leukoencephalopathy in multiple brain areas and male sterility. Despite a normal retinal histology in nmf240 heterozygotes, the ERG light peak, generated by the RPE, is reduced. CONCLUSIONS: The nmf240 phenotype closely resembles that reported for Clcn2 knockout mice. The observation that heterozygous nmf240 mice present with a reduced ERG light peak component suggests that CLCN2 is necessary for the generation of this response component

Machine learning prediction and tau-based screening identifies potential Alzheimer's disease genes relevant to immunity

With increased research funding for Alzheimer's disease (AD) and related disorders across the globe, large amounts of data are being generated. Several studies employed machine learning methods to understand the ever-growing omics data to enhance early diagnosis, map complex disease networks, or uncover potential drug targets. We describe results based on a Target Central Resource Database protein knowledge graph and evidence paths transformed into vectors by metapath matching. We extracted features between specific genes and diseases, then trained and optimized our model using XGBoost, termed MPxgb(AD). To determine our MPxgb(AD) prediction performance, we examined the top twenty predicted genes through an experimental screening pipeline. Our analysis identified potential AD risk genes: FRRS1, CTRAM, SCGB3A1, FAM92B/CIBAR2, and TMEFF2. FRRS1 and FAM92B are considered dark genes, while CTRAM, SCGB3A1, and TMEFF2 are connected to TREM2-TYROBP, IL-1 beta-TNF alpha, and MTOR-APP AD-risk nodes, suggesting relevance to the pathogenesis of AD. Jessica Binder et al. developed a machine learning model to discover potential drug targets for Alzheimer's disease. They validated their 20 top candidates in several in vitro models, and highlight FRRS1, CTRAM, SCGB3A1, FAM92B/CIBAR2, and TMEFF2 as potential AD risk genes

Selective In Vitro and Ex Vivo Staining of Brain Neurofibrillary Tangles and Amyloid Plaques by Novel Ethylene Ethynylene-Based Optical Sensors

The identification of protein aggregates as biomarkers for neurodegeneration is an area of interest for disease diagnosis and treatment development. In this work, we present novel super luminescent conjugated polyelectrolyte molecules as ex vivo sensors for tau-paired helical filaments (PHFs) and amyloid-β (Aβ) plaques. We evaluated the use of two oligo-p-phenylene ethynylenes (OPEs), anionic OPE12− and cationic OPE24+, as stains for fibrillar protein pathology in brain sections of transgenic mouse (rTg4510) and rat (TgF344-AD) models of Alzheimer’s disease (AD) tauopathy, and post-mortem brain sections from human frontotemporal dementia (FTD). OPE12− displayed selectivity for PHFs in fluorimetry assays and strong staining of neurofibrillary tangles (NFTs) in mouse and human brain tissue sections, while OPE24+ stained both NFTs and Aβ plaques. Both OPEs stained the brain sections with limited background or non-specific staining. This novel family of sensors outperformed the gold-standard dye Thioflavin T in sensing capacities and co-stained with conventional phosphorylated tau (AT180) and Aβ (4G8) antibodies. As the OPEs readily bind protein amyloids in vitro and ex vivo, they are selective and rapid tools for identifying proteopathic inclusions relevant to AD. Such OPEs can be useful in understanding pathogenesis and in creating in vivo diagnostically relevant detection tools for neurodegenerative diseases.</jats:p