Publications

The cellular prion protein (PrPC) plays many roles in the developing and adult brain. In addition, PrPC binds to several amyloids in oligomeric and prefibrillar forms and may act as a putative receptor of abnormal misfolded protein species. The role of PrPC in tau seeding and spreading is not known. In the present study, we have inoculated well-characterized sarkosyl-insoluble fractions of sporadic Alzheimer's disease (sAD) into the brain of adult wild-type mice (Prnp(+/+)), Prnp(0/0) (ZH3 strain) mice, and mice over-expressing the secreted form of PrPC lacking their GPI anchor (Tg44 strain). Phospho-tau (ptau) seeding and spreading involving neurons and oligodendrocytes were observed three and six months after inoculation. 3Rtau and 4Rtau deposits from the host tau, as revealed by inoculating Mapt(0/0) mice and by using specific anti-mouse and anti-human tau antibodies suggest modulation of exon 10 splicing of the host mouse Mapt gene elicited by exogenous sAD-tau. However, no tau seeding and spreading differences were observed among Prnp genotypes. Our results show that PrPC does not affect tau seeding and spreading in vivo.

JTD Keywords: Alpha-synuclein, Alzheimer's disease, Amyloid-beta oligomers, Expression, Impairmen, Mapt, Mice, Paired helical filaments, Pathological tau, Prnp, Propagation, Prpc, Seeding, Spreadin, Synaptic plasticity, Tau, Tauopathies

Clinical relevance of miRNAs as biomarkers is growing due to their stability and detection in biofluids. In this, diagnosis at asymptomatic stages of Alzheimer ' s disease (AD) remains a challenge since it can only be made at autopsy according to Braak NFT staging. Achieving the objective of detecting AD at early stages would allow possible therapies to be addressed before the onset of cognitive impairment. Many studies have determined that the expression pattern of some miRNAs is dysregulated in AD patients, but to date, none has been correlated with downregulated expression of cellular prion protein (PrP C ) during disease progression. That is why, by means of cross studies of miRNAs up -regulated in AD with in silico identification of potential miRNAs-binding to 3 ' UTR of human PRNP gene, we selected miR-519a-3p for our study. Then, in vitro experiments were carried out in two ways. First, we validated miR-519a-3p target on 3 ' UTR- PRNP , and second, we analyzed the levels of PrP C expression after using of mimic technology on cell culture. In addition, RT-qPCR was performed to analyzed miR519a-3p expression in human cerebral samples of AD at different stages of disease evolution. Additionally, samples of other neurodegenerative diseases such as other non -AD tauopathies and several synucleinopathies were included in the study. Our results showed that miR-519a-3p overlaps with PRNP 3 ' UTR in vitro and promotes downregulation of PrP C . Moreover, miR-519a-3p was found to be up -regulated exclusively in AD samples from stage I to VI, suggesting its potential use as a novel label of preclinical stages of the disease.

JTD Keywords: Activation, Alzheimer's disease, Biomarke, Brain, Cellular prion protein, Developmental expression, Gen, Micrornas, Plasma, Prpc, Tau-aggregation

Steroid myopathy is a clinically challenging condition exacerbated by prolonged corticosteroid use or adrenal tumors. In this study, we engineered a functional three-dimensional (3D) in vitro skeletal muscle model to investigate steroid myopathy. By subjecting our bioengineered muscle tissues to dexamethasone treatment, we reproduced the molecular and functional aspects of this disease. Dexamethasone caused a substantial reduction in muscle force, myotube diameter and induced fatigue. We observed nuclear translocation of the glucocorticoid receptor (GCR) and activation of the ubiquitin-proteasome system within our model, suggesting their coordinated role in muscle atrophy. We then examined the therapeutic potential of taurine in our 3D model for steroid myopathy. Our findings revealed an upregulation of phosphorylated AKT by taurine, effectively countering the hyperactivation of the ubiquitin- proteasomal pathway. Importantly, we demonstrate that discontinuing corticosteroid treatment was insufficient to restore muscle mass and function. Taurine treatment, when administered concurrently with corticosteroids, notably enhanced contractile strength and protein turnover by upregulating the AKT-mTOR axis. Our model not only identifies a promising therapeutic target, but also suggests combinatorial treatment that may benefit individuals undergoing corticosteroid treatment or those diagnosed with adrenal tumors.

JTD Keywords: 3d bioengineered skeletal muscle tissues, Adrenal cortex hormones, Atroph, Colocalization, Corticosteroids, Dexamethasone, Glucocorticoid-receptor, Humans, Mechanisms, Models, biological, Mtor protein, human, Muscle contraction, Muscle fibers, skeletal, Muscle strength, Muscle, skeletal, Muscular diseases, Organ size, Phosphorylation, Proteasome endopeptidase complex, Proto-oncogene proteins c-akt, Receptors, glucocorticoid, Signal transduction, Skeletal-muscle, Steroid myopathy, Steroids, Supplementation, Taurin, Taurine, Tor serine-threonine kinases, Ubiquitin

In Alzheimer's disease, fibrillar tau pathology accumulates and spreads through the brain and synapses are lost. Evidence from mouse models indicates that tau spreads trans-synaptically from pre- to postsynapses and that oligomeric tau is synaptotoxic, but data on synaptic tau in human brain are scarce. Here we used sub-diffraction-limit microscopy to study synaptic tau accumulation in postmortem temporal and occipital cortices of human Alzheimer's and control donors. Oligomeric tau is present in pre- and postsynaptic terminals, even in areas without abundant fibrillar tau deposition. Furthermore, there is a higher proportion of oligomeric tau compared with phosphorylated or misfolded tau found at synaptic terminals. These data suggest that accumulation of oligomeric tau in synapses is an early event in pathogenesis and that tau pathology may progress through the brain via trans-synaptic spread in human disease. Thus, specifically reducing oligomeric tau at synapses may be a promising therapeutic strategy for Alzheimer's disease.Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.

JTD Keywords: accumulation, alpha-synuclein, array tomography, cognitive impairment, dendritic spines, mouse model, neurodegeneration, neurons, synapses, Alzheimer, Amyloid-beta, Synapse, Tau

(Phospho)proteomics of old-aged subjects without cognitive or behavioral symptoms, and without AD-neuropathological changes and lacking any other neurodegenerative alteration will increase understanding about the physiological state of human brain aging without associate neurological deficits and neuropathological lesions.(Phospho)proteomics using conventional label-free- and SWATH-MS (Sequential window acquisition of all theoretical fragment ion spectra mass spectrometry) has been assessed in the frontal cortex (FC) of individuals without NFTs, senile plaques (SPs) and age-related co-morbidities classified by age (years) in four groups; group 1 (young, 30-44); group 2 (middle-aged: MA, 45-52); group 3 (early-elderly, 64-70); and group 4 (late-elderly, 75-85).Protein levels and deregulated protein phosphorylation linked to similar biological terms/functions, but involving different individual proteins, are found in FC with age. The modified expression occurs in cytoskeleton proteins, membranes, synapses, vesicles, myelin, membrane transport and ion channels, DNA and RNA metabolism, ubiquitin-proteasome-system (UPS), kinases and phosphatases, fatty acid metabolism, and mitochondria. Dysregulated phosphoproteins are associated with the cytoskeleton, including microfilaments, actin-binding proteins, intermediate filaments of neurons and glial cells, and microtubules; membrane proteins, synapses, and dense core vesicles; kinases and phosphatases; proteins linked to DNA and RNA; members of the UPS; GTPase regulation; inflammation; and lipid metabolism. Noteworthy, protein levels of large clusters of hierarchically-related protein expression levels are stable until 70. However, protein levels of components of cell membranes, vesicles and synapses, RNA modulation, and cellular structures (including tau and tubulin filaments) are markedly altered from the age of 75. Similarly, marked modifications occur in the larger phosphoprotein clusters involving cytoskeleton and neuronal structures, membrane stabilization, and kinase regulation in the late elderly.Present findings may increase understanding of human brain proteostasis modifications in the elderly in the subpopulation of individuals not having AD neuropathological change and any other neurodegenerative change in any telencephalon region.

JTD Keywords: (phospho)proteomics, cortex, cytoskeleton, hippocampus, kinases, membranes, mitochondria, mitochondrial-function, pathological process, phosphoproteome analysis, phosphorylation, proteome, quantitative proteomics, synapsis, tau-protein, therapeutic target, (phospho)proteomics, Brain aging, Cytoskeleton, Kinases, Membranes, Mitochondria, Neurodegenerative diseases, Proteome, Synapsis

The hippocampus of cases with neurofibrillary tangles (NFT) pathology classified as stages I–II, III–IV, and V–VI without comorbidities, and middle-aged (MA) individuals with no NFT pathology, were examined to learn about the composition of granulovacuolar degeneration (GVD). Our results confirm the presence of CK1-?, p38-P Thr180/Tyr182, SAPK/JNK-P Thr183/Thr185, GSK-3?/?-P Tyr279/Tyr216, and GSK-3? Ser9 in the cytoplasmic granules in a subset of neurons of the CA1 and CA2 subfields of the hippocampus. Also, we identify the presence of PKA ?/?-P Thr197, SRC-P Tyr416, PAK1-P Ser199/Ser204, CAMK2A-P Tyr197, and PKCG-P Thr655 in cytoplasmic granules in cases with NFT pathology, but not in MA cases. Our results also confirm the presence of ?-catenin-P Ser45/Thr41, IRE?-P Ser274, eIF2?-P Ser51, TDP-43-P Ser403-404 (but absent TDP-43), and ubiquitin in cytoplasmic granules. Other components of the cytoplasmic granules are MAP2-P Thr1620/1623, MAP1B-P Thr1265, ADD1-P Ser726, and ADD1/ADD1-P Ser726/Ser713, in addition to several tau species including 3Rtau, 4Rtau, and tau-P Ser262. The analysis of GVD at progressive stages of NFT pathology reveals the early appearance of phosphorylated kinases and proteins in cytoplasmic granules at stages I–II, before the appearance of pre-tangles and NFTs. Most of these granules are not surrounded by LAMP1-positive membranes. Markers of impaired ubiquitin-protesome system, abnormal reticulum stress response, and altered endocytic and autophagic pathways occur in a subpopulation of neurons containing cytoplasmic granules, and they appear later. These observations suggest early phosphorylation of kinases leading to their activation, and resulting in the abnormal phosphorylation of various substrates, including tau, as a main alteration at the first stages of GVD. © 2021 The Author(s)

JTD Keywords: alzheimer's disease, alzheimers association guidelines, alzheimer’s disease, brain aging, cyclin-dependent kinase-5, granulovacuolar degeneration, kinases, national institute, neuropathologic assessment, p38 kinase, progressive supranuclear palsy, protein phosphorylation, tau, tau pathology, up-regulation, upstream activator, Alzheimer's disease, Brain aging, Glycogen-synthase kinase-3, Granulovacuolar degeneration, Kinases, Protein phosphorylation, Tau

Here we revisit tau protein aggregation at primary, secondary, tertiary and quaternary structures. In addition, the presence of non-aggregated tau protein, which has been recently discovered, is also commented on.Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.

JTD Keywords: alpha-helix, alzheimer-disease, antigenic determinants, binding, isomerase pin1, microtubule-binding repeats, neurofibrillary tangles, paired helical filaments, repeat domain, structural-characterization, tau conformations, w-tau isoform, Microtubule-associated protein, Microtubule-binding repeats, Tau, Tau conformations, W-tau isoform

Transcriptomics and phosphoproteomics were carried out in the cerebral cortex of B6.Cg-Mapttm1(EGFP)Klt (tau knockout: tau-KO) and wild-type (WT) 12 month-old mice to learn about the effects of tau ablation. Compared with WT mice, tau-KO mice displayed reduced anxiety-like behavior and lower fear expression induced by aversive conditioning, whereas recognition memory remained unaltered. Cortical transcriptomic analysis revealed 69 downregulated and 105 upregulated genes in tau-KO mice, corresponding to synaptic structures, neuron cytoskeleton and transport, and extracellular matrix components. RT-qPCR validated increased mRNA levels of col6a4, gabrq, gad1, grm5, grip2, map2, rab8a, tubb3, wnt16, and an absence of map1a in tau-KO mice compared with WT mice. A few proteins were assessed with Western blotting to compare mRNA expression with corresponding protein levels. Map1a mRNA and protein levels decreased. However, β-tubulin III and GAD1 protein levels were reduced in tau-KO mice. Cortical phosphoproteomics revealed 121 hypophosphorylated and 98 hyperphosphorylated proteins in tau-KO mice. Deregulated phosphoproteins were categorized into cytoskeletal (n = 45) and membrane proteins, including proteins of the synapses and vesicles, myelin proteins, and proteins linked to membrane transport and ion channels (n = 84), proteins related to DNA and RNA metabolism (n = 36), proteins connected to the ubiquitin-proteasome system (UPS) (n = 7), proteins with kinase or phosphatase activity (n = 21), and 22 other proteins related to variegated pathways such as metabolic pathways, growth factors, or mitochondrial function or structure. The present observations reveal a complex altered brain transcriptome and phosphoproteome in tau-KO mice with only mild behavioral alterations.

JTD Keywords: computational platform, conformational-changes, cytoskeleton, disease, expression, isoforms, mechanisms, mice, phosphoproteomics, phosphorylation, synapse, tau-ko, tauopathies, transcriptomics, Tau-ko, Tau-protein, Transcriptomics

A set of twenty-five thioxanthene-9-one and xanthene-9-one derivatives, that were previously shown to inhibit cholinesterases (ChEs) and amyloid β (Aβ40) aggregation, were evaluated for the inhibition of tau protein aggregation. All compounds exhibited a good activity, and eight of them (5-8, 10, 14, 15 and 20) shared comparable low micromolar inhibitory potency versus Aβ40 aggregation and human acetylcholinesterase (AChE), while inhibiting human butyrylcholinesterase (BChE) even at submicromolar concentration. Compound 20 showed outstanding biological data, inhibiting tau protein and Aβ40 aggregation with IC50 = 1.8 and 1.3 μM, respectively. Moreover, at 0.1-10 μM it also exhibited neuroprotective activity against tau toxicity induced by okadoic acid in human neuroblastoma SH-SY5Y cells, that was comparable to that of estradiol and PD38. In preliminary toxicity studies, these interesting results for compound 20 are somewhat conflicting with a narrow safety window. However, compound 10, although endowed with a little lower potency for tau and Aβ aggregation inhibition additionally demonstrated good inhibition of ChEs and rather low cytotoxicity. Compound 4 is also worth of note for its high potency as hBChE inhibitor (IC50 = 7 nM) and for the three order of magnitude selectivity versus hAChE. Molecular modelling studies were performed to explain the different behavior of compounds 4 and 20 towards hBChE. The observed balance of the inhibitory potencies versus the relevant targets indicates the thioxanthene-9-one derivatives as potential MTDLs for AD therapy, provided that the safety window will be improved by further structural variations, currently under investigation.Copyright © 2023 Elsevier Masson SAS. All rights reserved.

JTD Keywords: a? and tau aggregation inhibition, ache and bche inhibition, aggregation, alzheimer?s disease, butyrylcholinesterase, design, drugs, dual inhibitors, fibrillization, multitarget-directed ligands (mtdls), peptide, polyphenols, potent, rivatives, Ache and bche inhibition, Alzheimer's disease, Amyloid-beta, Aβ and tau aggregation inhibition, Multitarget-directed ligands (mtdls), Thioxanthene-9-one and xanthen-9-one de, Thioxanthene-9-one and xanthen-9-one derivatives

Heterozygous hTau mice were used for the study of tau seeding. These mice express the six human tau isoforms, with a high predominance of 3Rtau over 4Rtau. The following groups were assessed: (i) non-inoculated mice aged 9 months (n = 4); (ii) Alzheimer's Disease (AD)-inoculated mice (n = 4); (iii) Globular Glial Tauopathy (GGT)-inoculated mice (n = 4); (iv) Pick's disease (PiD)-inoculated mice (n = 4); (v) control-inoculated mice (n = 4); and (vi) inoculated with vehicle alone (n = 2). AD-inoculated mice showed AT8-immunoreactive neuronal pre-tangles, granular aggregates, and dots in the CA1 region of the hippocampus, dentate gyrus (DG), and hilus, and threads and dots in the ipsilateral corpus callosum. GGT-inoculated mice showed unique or multiple AT8-immunoreactive globular deposits in neurons, occasionally extended to the proximal dendrites. PiD-inoculated mice showed a few loose pre-tangles in the CA1 region, DG, and cerebral cortex near the injection site. Coiled bodies were formed in the corpus callosum in AD-inoculated mice, but GGT-inoculated mice lacked globular glial inclusions. Tau deposits in inoculated mice co-localized active kinases p38-P and SAPK/JNK-P, thus suggesting active phosphorylation of the host tau. Tau deposits were absent in hTau mice inoculated with control homogenates and vehicle alone. Deposits in AD-inoculated hTau mice contained 3Rtau and 4Rtau; those in GGT-inoculated mice were mainly stained with anti-4Rtau antibodies, but a small number of deposits contained 3Rtau. Deposits in PiD-inoculated mice were stained with anti-3Rtau antibodies, but rare neuronal, thread-like, and dot-like deposits showed 4Rtau immunoreactivity. These findings show that tau strains produce different patterns of active neuronal seeding, which also depend on the host tau. Unexpected 3Rtau and 4Rtau deposits after inoculation of homogenates from 4R and 3R tauopathies, respectively, suggests the regulation of exon 10 splicing of the host tau during the process of seeding, thus modulating the plasticity of the cytoskeleton.

JTD Keywords: alzheimer's disease (ad), alzheimers-disease, brain, corticobasal degeneration, globular glial tauopathy (ggt), htau, isoforms, pathological tau, pick's disease (pid), picks-disease, propagation, protein, seeding, tau splicing, tauopathy, Alzheimer’s disease (ad), Globular glial tauopathy (ggt), Htau, Paired helical filaments, Pick’s disease (pid), Seeding, Tau, Tau splicing

Tauopathies are a group of neurodegenerative diseases characterized by the hyperphosphorylation and deposition of tau proteins in the brain. In Alzheimer's disease, and other related tauopathies, the pattern of tau deposition follows a stereotypical progression between anatomically connected brain regions. Increasing evidence suggests that tau behaves in a "prion-like" manner, and that seeding and spreading of pathological tau drive progressive neurodegeneration. Although several advances have been made in recent years, the exact cellular and molecular mechanisms involved remain largely unknown. Since there are no effective therapies for any tauopathy, there is a growing need for reliable experimental models that would provide us with better knowledge and understanding of their etiology and identify novel molecular targets. In this review, we will summarize the development of cellular models for modeling tau pathology. We will discuss their different applications and contributions to our current understanding of the "prion-like" nature of pathological tau.

JTD Keywords: neurodegeneration, seeding, spreading, Culture model, Efficient generation, Extracellular tau, Familial alzheimers-disease, Microtubule-associated protein, Mouse model, Neurodegeneration, Neurofibrillary tangles, Paired helical filaments, Pathogenic tau, Pluripotent stem-cells, Seeding, Spreading, Tauopathies

The neocortex of P301S mice, used as a model of fronto-temporal lobar degeneration linked to tau mutation (FTLD-tau), and wild-type mice, both aged 9 months, were analyzed with conventional label-free phosphoproteomics and SWATH-MS (sequential window acquisition of all theoretical fragment ion spectra mass spectrometry) to assess the (phospho)proteomes. The total number of identified dysregulated phosphoproteins was 328 corresponding to 524 phosphorylation sites. The majority of dysregulated phosphoproteins, most of them hyperphosphorylated, were proteins of the membranes, synapses, membrane trafficking, membrane vesicles linked to endo- and exocytosis, cytoplasmic vesicles, and cytoskeleton. Another group was composed of kinases. In contrast, proteins linked to DNA, RNA metabolism, RNA splicing, and protein synthesis were hypophosphorylated. Other pathways modulating energy metabolism, cell signaling, Golgi apparatus, carbohydrates, and lipids are also targets of dysregulated protein phosphorylation in P301S mice. The present results, together with accompanying immunohistochemical and Western-blotting studies, show widespread abnormal phosphorylation of proteins, in addition to protein tau, in P301S mice. These observations point to dysregulated protein phosphorylation as a relevant contributory pathogenic component of tauopathies.

JTD Keywords: (phospho)proteomics, cytoskeleton, kinases, membranes, tau, (phospho)proteomics, Cytoskeleton, Kinases, Membranes, Networks, Oxidative stress, Pathology, Phosphoproteome analysis, Tau, Tauopathy

Altered protein phosphorylation is a major pathologic modification in tauopathies and Alzheimer's disease (AD) linked to abnormal tau fibrillar deposits in neurofibrillary tangles (NFTs) and pre-tangles and beta-amyloid deposits in AD. hTau transgenic mice, which express 3R and less 4R human tau with no mutations in a murine knock-out background, show increased tau deposition in neurons but not NFTs and pre-tangles at the age of nine months. Label-free (phospho)proteomics and SWATH-MS identified 2065 proteins in hTau and wild-type (WT) mice. Only six proteins showed increased levels in hTau; no proteins were down-regulated. Increased tau phosphorylation in hTau was detected at Ser199, Ser202, Ser214, Ser396, Ser400, Thr403, Ser404, Ser413, Ser416, Ser422, Ser491, and Ser494, in addition to Thr181, Thr231, Ser396/Ser404, but not at Ser202/Thr205. In addition, 4578 phosphopeptides (corresponding to 1622 phosphoproteins) were identified in hTau and WT mice; 64 proteins were differentially phosphorylated in hTau. Sixty proteins were grouped into components of membranes, membrane signaling, synapses, vesicles, cytoskeleton, DNA/RNA/protein metabolism, ubiquitin/proteasome system, cholesterol and lipid metabolism, and cell signaling. These results showed that over-expression of human tau without pre-tangle and NFT formation preferentially triggers an imbalance in the phosphorylation profile of specific proteins involved in the cytoskeletal-membrane-signaling axis.

JTD Keywords: cytoskeleton, htau, membrane, phosphorylation, synapsis, tau, Aggregation, Alzheimers-disease, Animal-models, Cytoskeleton, Htau, Membrane, Mice, Networks, Pathology, Phosphoproteome analysis, Phosphorylation, Synapsis, Tau, Tauopathies, Tauopathy

Alzheimer’s disease (AD) and other tauopathies are common neurodegenerative diseases in older adults; in contrast, abnormal tau deposition in neurons and glial cells occurs only exceptionally in children. Sarkosyl-insoluble fractions from sporadic AD (sAD) containing paired helical filaments (PHFs) were inoculated unilaterally into the thalamus in newborn and three-month-old wild-type C57BL/6 mice, which were killed at different intervals from 24 h to six months after inoculation. Tau-positive cells were scanty and practically disappeared at three months in mice inoculated at the age of a newborn. In contrast, large numbers of tau-positive cells, including neurons and oligodendrocytes, were found in the thalamus of mice inoculated at three months and killed at the ages of six months and nine months. Mice inoculated at the age of newborn and re-inoculated at the age of three months showed similar numbers and distribution of positive cells in the thalamus at six months and nine months. This study shows that (a) differences in tau seeding between newborn and young adults may be related to the ratios between 3Rtau and 4Rtau, and the shift to 4Rtau predominance in adults, together with the immaturity of connections in newborn mice, and (b) intracerebral inoculation of sAD PHFs in newborn mice does not protect from tau seeding following intracerebral inoculation of sAD PHFs in young/adult mice.

JTD Keywords: alzheimer's disease, alzheimer-disease, alzheimer’s disease, expression, mouse tau, neurofibrillary tangles, newborn, pathological tau, propagation, protein-tau, spread, tau seeding and spreading, thalamus, transgenic mice, Paired helical filaments, Tau seeding and spreading, Thalamus

Several studies have demonstrated the different characteristics of tau seeding and spreading following intracerebral inoculation in murine models of tau-enriched fractions of brain homogenates from AD and other tauopathies. The present study is centered on the importance of host tau in tau seeding and the molecular changes associated with the transformation of host tau into abnormal tau. The brains of three adult murine genotypes expressing different forms of tau—WT (murine 4Rtau), hTau (homozygous transgenic mice knock-out for murine tau protein and heterozygous expressing human forms of 3Rtau and 4Rtau proteins), and mtWT (homozygous transgenic mice knock-out for murine tau protein)—were analyzed following unilateral hippocampal inoculation of sarkosyl-insoluble tau fractions from the same AD and control cases. The present study reveals that (a) host tau is mandatory for tau seeding and spreading following tau inoculation from sarkosyl-insoluble fractions obtained from AD brains; (b) tau seeding does not occur following intracerebral inoculation of sarkosyl-insoluble fractions from controls; (c) tau seeding and spreading are characterized by variable genotype-dependent tau phosphorylation and tau nitration, MAP2 phosphorylation, and variable activation of kinases that co-localize with abnormal tau deposits; (d) transformation of host tau into abnormal tau is an active process associated with the activation of specific kinases; (e) tau seeding is accompanied by modifications in tau splicing, resulting in the expression of new 3Rtau and 4Rtau isoforms, thus indicating that inoculated tau seeds have the capacity to model exon 10 splicing of the host mapt or MAPT with a genotype-dependent pattern; (e) selective regional and cellular vulnerabilities, and different molecular compositions of the deposits, are dependent on the host tau of mice injected with identical AD tau inocula.

JTD Keywords: 3rtau and 4rtau, alzheimer's disease, alzheimer’s disease, brains, granulovacuolar degeneration, host tau, htau, intranuclear distribution, messenger-rna, pathological tau, propagation, protein-kinases, seeding and spreading, tauopathies, transmission, 3rtau and 4rtau, Alzheimers-disease, Alzheimer’s disease, Host tau, Htau, Seeding and spreading, Tauopathies

Tau hyperphosphorylation is the first step of neurofibrillary tangle (NFT) formation. In the present study, samples of the entorhinal cortex (EC) and frontal cortex area 8 (FC) of cases with NFT pathology classified as stages I–II, III–IV, and V–VI without comorbidities, and of middle-aged (MA) individuals with no NFT pathology, were analyzed by conventional label-free and SWATH-MS (sequential window acquisition of all theoretical fragment ion spectra mass spectrometry) to assess the (phospho)proteomes. The total number of identified dysregulated phosphoproteins was 214 in the EC, 65 of which were dysregulated at the first stages (I–II) of NFT pathology; 167 phosphoproteins were dysregulated in the FC, 81 of them at stages I–II of NFT pathology. A large percentage of dysregulated phosphoproteins were identified in the two regions and at different stages of NFT progression. The main group of dysregulated phosphoproteins was made up of components of the membranes, cytoskeleton, synapses, proteins linked to membrane transport and ion channels, and kinases. The present results show abnormal phosphorylation of proteins at the first stages of NFT pathology in the elderly (in individuals clinically considered representative of normal aging) and sporadic Alzheimer's disease (sAD). Dysregulated protein phosphorylation in the FC precedes the formation of NFTs and SPs. The most active period of dysregulated phosphorylation is at stages III–IV when a subpopulation of individuals might be clinically categorized as suffering from mild cognitive impairment which is a preceding determinant stage in the progression to dementia. Altered phosphorylation of selected proteins, carried out by activation of several kinases, may alter membrane and cytoskeletal functions, among them synaptic transmission and membrane/cytoskeleton signaling. Besides their implications in sAD, the present observations suggest a molecular substrate for “benign” cognitive deterioration in “normal” brain aging.

JTD Keywords: (phospho)proteomics, alzheimer's disease, amyloid-beta, association guidelines, brain aging, cytoskeleton, frontal-cortex, kinases, lipid rafts, membranes, national institute, neuropathologic assessment, pathological process, protein phosphorylation, synapse pathology, synapses, tau, tau pathology, (phospho)proteomics, Age-related tauopathy, Alzheimer's disease, Brain aging, Cytoskeleton, Kinases, Membranes, Protein phosphorylation, Synapses, Tau

Cell therapy has emerged as an attractive therapeutic option in organ transplantation. During the last decade, the therapeutic potency of Treg immunotherapy has been shown in various preclinical animal models and safety was demonstrated in first clinical trials. However, there are still critical open questions regarding specificity, survival, and migration to the target tissue so the best Treg population for infusion into patients is still under debate. Recent advances in CAR technology hold the promise for Treg-functional superiority. Another exciting strategy is the generation of B-cell antibody receptor (BAR) Treg/cytotoxic T cells to specifically regulate or deplete alloreactive memory B cells. Finally, B cells are also capable of immune regulation, making them promising candidates for immunomodulatory therapeutic strategies. This article summarizes available literature on cell-based innovative therapeutic approaches aiming at modulating alloimmune response for transplantation. Crucial areas of investigation that need a joined effort of the transplant community for moving the field toward successful achievement of tolerance are highlighted.

JTD Keywords: allograft, autoimmune, b-cell antibody receptor t cells, chimeric antigen receptor tregs, expansion, expression, identification, infectious tolerance, mouse, prevention, regulatory b cells, regulatory t cells, signature, B-cell antibody receptor t cells, Chimeric antigen receptor tregs, Kidney-transplantation, Regulatory b cells, Regulatory t cells

Background: In recent decades, gold nanoparticle (Au NP)-based cancer therapy has been heavily debated. The physico-chemical properties of AuNPs can be exploited in photothermal therapy, making them a powerful tool for selectively killing cancer cells. However, the synthetic side products and capping agents often induce a strong activation of the inflammatory pathways of macrophages, thus limiting their further applications in vivo. Methods: Here, we described a green method to obtain stable polyphenol-capped AuNPs (Au NPs@polyphenols), as polyphenols are known for their anti-inflammatory and anticancer properties. These NPs were used in human macrophages to test key inflammation-related markers, such as NF-κB, TNF-α, and interleukins-6 and 8. The results were compared with similar NPs obtained by a traditional chemical route (without the polyphenol coating), proving the potential of Au NPs@polyphenols to strongly promote the shutdown of inflammation. This was useful in developing them for use as heat-synergized tools in the thermal treatment of two types of cancer cells, namely, breast cancer (MCF-7) and neuroblastoma (SH-SY5Y) cells. The cell viability, calcium release, oxidative stress, HSP-70 expression, mitochondrial, and DNA damage, as well as cytoskeleton alteration, were evaluated. Results: Our results clearly demonstrate that the combined strategy markedly exerts anticancer effects against the tested cancer cell, while neither of the single treatments (only heat or only NPs) induced significant changes. Conclusions: Au NP@polyphenols may be powerful agents in cancer treatment.

JTD Keywords: antioxidant, aunps, biocompatibility, biology, calcium, cancer, green synthesis, inflammation response, inhibition, interleukin-6, mechanisms, natural polyphenols, physico-chemical properties, polyphenols, size, thermal treatment, Aunps, Cancer, Green synthesis, Inflammation response, Nobilis l. leaves, Physico-chemical properties, Polyphenols, Thermal treatment

Tau protein is largely responsible for tauopathies, including Alzheimer’s disease (AD), where it accumulates in the brain as insoluble aggregates. Tau mRNA is regulated by alternative splicing, and inclusion or exclusion of exon 10 gives rise to the 3R and 4R isoforms respectively, whose balance is physiologically regulated. In this sense, one of the several factors that regulate alternative splicing of tau is GSK3?, whose activity is inhibited by the cellular prion protein (PrPC), which has different physiological functions in neuroprotection and neuronal differentiation. Moreover, a relationship between PrPC and tau expression levels has been reported during AD evolution. For this reason, in this study we aimed to analyze the role of PrPC and the implication of GSK3? in the regulation of tau exon 10 alternative splicing. We used AD human samples and mouse models of PrPC ablation and tau overexpression. In addition, we used primary neuronal cultures to develop functional studies. Our results revealed a paralleled association between PrPC expression and tau 4R isoforms in all models analyzed. In this sense, reduction or ablation of PrPC levels induces an increase in tau 3R/4R balance. More relevantly, our data points to GSK3? activity downstream from PrPC in this phenomenon. Our results indicate that PrPC plays a role in tau exon 10 inclusion through the inhibitory capacity of GSK3?. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

JTD Keywords: alternative splicing, alzheimer's disease, alzheimers-disease, alzheimer’s disease, amyloid-beta, cellular prion protein, frontotemporal dementia, glycogen-synthase kinase-3, gsk3 beta, gsk3?, gsk3β, messenger-rna, microtubule-associated protein tau, neurofibrillary tangles, progressive supranuclear palsy, promotes neuronal differentiation, stem-cells, tauopathies, Alternative splicing, Alzheimer’s disease, Cellular prion protein, Gsk3?, Microtubule-associated protein tau, Tauopathies

Argyrophilic grain disease (AGD) is a common 4R-tauopathy, causing or contributing to cognitive impairment in the elderly. AGD is characterized neuropathologically by pre-tangles in neurons, dendritic swellings called grains, threads, thorn-shaped astrocytes, and coiled bodies in oligodendrocytes in the limbic system. AGD has a characteristic pattern progressively involving the entorhinal cortex, amygdala, hippocampus, dentate gyrus, presubiculum, subiculum, hypothalamic nuclei, temporal cortex, and neocortex and brainstem, thus suggesting that argyrophilic grain pathology is a natural model of tau propagation. One series of WT mice was unilaterally inoculated in the hippocampus with sarkosyl-insoluble and sarkosyl-soluble fractions from “pure” AGD at the age of 3 or 7/12 months and killed 3 or 7 months later. Abnormal hyper-phosphorylated tau deposits were found in ipsilateral hippocampal neurons, grains (dots) in the hippocampus, and threads, dots and coiled bodies in the fimbria, as well as the ipsilateral and contralateral corpus callosum. The extension of lesions was wider in animals surviving 7 months compared with those surviving 3 months. Astrocytic inclusions were not observed at any time. Tau deposits were mainly composed of 4Rtau, but also 3Rtau. For comparative purposes, another series of WT mice was inoculated with sarkosyl-insoluble fractions from primary age-related tauopathy (PART), a pure neuronal neurofibrillary tangle 3Rtau + 4Rtau tauopathy involving the deep temporal cortex and limbic system. Abnormal hyper-phosphorylated tau deposits were found in neurons in the ipsilateral hippocampus, coiled bodies and threads in the fimbria, and the ipsilateral and contralateral corpus callosum, which extended with time along the anterior-posterior axis and distant regions such as hypothalamic nuclei and nuclei of the septum when comparing mice surviving 7 months with mice surviving 3 months. Astrocytic inclusions were not observed. Tau deposits were mainly composed of 4Rtau and 3Rtau. These results show the capacity for seeding and spreading of AGD tau and PART tau in the brain of WT mouse, and suggest that characteristics of host tau, in addition to those of inoculated tau, are key to identifying commonalities and differences between human tauopathies and corresponding murine models.

JTD Keywords: Argyrophilic grain disease, Tauopathies, Tau, Seeding, Progression, Coiled Bodies, Primary age-related tauopathy

Globular glial tauopathy (GGT) is a progressive neurodegenerative disease involving the grey matter and white matter (WM) and characterized by neuronal deposition of hyper-phosphorylated, abnormally conformed, truncated, oligomeric 4Rtau in neurons and in glial cells forming typical globular astrocyte and oligodendrocyte inclusions (GAIs and GOIs, respectively) and coiled bodies. Present studies centre on four genetic GGT cases from two unrelated families bearing the P301T mutation in MAPT and one case of sporadic GGT (sGGT) and one case of GGT linked to MAPT K317M mutation, for comparative purposes. Clinical and neuropathological manifestations and biochemical profiles of phospho-tau are subjected to individual variations in patients carrying the same mutation, even in carriers of the same family, independently of the age of onset, gender, and duration of the disease. Immunohistochemistry, western blotting, transcriptomic, proteomics and phosphoproteomics, and intra-cerebral inoculation of brain homogenates to wild-type (WT) mice were the methods employed. In GGT cases linked to MAPT P301T mutation, astrocyte markers GFAP, ALDH1L1, YKL40 mRNA and protein, GJA1 mRNA, and AQ4 protein are significantly increased; glutamate transporter GLT1 (EAAT2) and glucose transporter (SLC2A1) decreased; mitochondrial pyruvate carrier 1 (MPC1) increased, and mitochondrial uncoupling protein 5 (UCP5) almost absent in GAIs in frontal cortex (FC). Expression of oligodendrocyte markers OLIG1 and OLIG2mRNA, and myelin-related genes MBP, PLP1, CNP, MAG, MAL, MOG, and MOBP are significantly decreased in WM; CNPase, PLP1, and MBP antibodies reveal reduction and disruption of myelinated fibres; and SMI31 antibodies mark axonal damage in the WM. Altered expression of AQ4, GLUC-t, and GLT-1 is also observed in sGGT and in GGT linked to MAPT K317M mutation. These alterations point to primary astrogliopathy and oligodendrogliopathy in GGT. In addition, GGT linked to MAPT P301T mutation proteotypes unveil a proteostatic imbalance due to widespread (phospho)proteomic dearrangement in the FC and WM, triggering a disruption of neuron projection morphogenesis and synaptic transmission. Identification of hyper-phosphorylation of variegated proteins calls into question the concept of phospho-tau-only alteration in the pathogenesis of GGT. Finally, unilateral inoculation of sarkosyl-insoluble fractions of GGT homogenates from GGT linked to MAPT P301T, sGGT, and GGT linked to MAPT K317M mutation in the hippocampus, corpus callosum, or caudate/putamen in wild-type mice produces seeding, and time- and region-dependent spreading of phosphorylated, non-oligomeric, and non-truncated 4Rtau and 3Rtau, without GAIs and GOIs but only of coiled bodies. These experiments prove that host tau strains are important in the modulation of cellular vulnerability and phenotypes of phospho-tau aggregates.

JTD Keywords: Globular glial tauopathy, Tau, Astrogliopathy, Oligodendrogliopathy, Phosphoproteome, Seeding and spreading

Background: Differential diagnosis of neurodegenerative dementia is currently supported by biomarkers including cerebrospinal fluid (CSF) tests. Among them, CSF total-tau (t-tau), phosphorylated tau (p-tau) and β-amyloid42 (Aβ42) are considered core biomarkers of neurodegeneration. In the present work, we hypothesize that simultaneous assessment of these biomarkers together with CSF α-synuclein (α-syn) will significantly improve the differential diagnostic of Alzheimer's disease and other dementias. To that aim, we characterized the analytical and clinical performance of a new tetra-plex immunoassay that simultaneously quantifies CSF Aβ42, t-tau, p-tau and α-syn in the differential diagnosis of neurodegenerative dementia. Methods: Biomarkers' concentrations were measured in neurological controls (n = 38), Alzheimer's disease (n = 35), Creutzfeldt-Jakob disease (n = 37), vascular dementia (n = 28), dementia with Lewy bodies/Parkinson's disease dementia (n = 27) and frontotemporal dementia (n = 34) using the new tetra-plex assay and established single-plex assays. Biomarker's performance was evaluated and diagnostic accuracy in the discrimination of diagnostic groups was determined using partial least squares discriminant analysis. Results: The tetra-plex assay presented accuracies similar to individual single-plex assays with acceptable analytical performance. Significant correlations were observed between tetra-plex and single-plex assays. Using partial least squares discriminant analysis, Alzheimer's disease and Creutzfeldt-Jakob disease were well differentiated, reaching high accuracies in the discrimination from the rest of diagnostic groups. Conclusions: The new tetra-plex assay coupled with multivariate analytical approaches becomes a valuable asset for the differential diagnosis of neurodegenerative dementia and related applications.

JTD Keywords: Neurodegenerative dementia, Cerebrospinal fluid, Biomarker, Amyloid beta, Total-tau, Phospho-tau, α-Synuclein, Multiplexing

Cellular (also termed ‘natural’) prion protein has been extensively studied for many years for its pathogenic role in prionopathies after misfolding. However, neuroprotective properties of the protein have been demonstrated under various scenarios. In this line, the involvement of the cellular prion protein in neurodegenerative diseases other than prionopathies continues to be widely debated by the scientific community. In fact, studies on knock-out mice show a vast range of physiological functions for the protein that can be supported by its ability as a cell surface scaffold protein. In this review, we first summarize the most commonly described roles of cellular prion protein in neuroprotection, including antioxidant and antiapoptotic activities and modulation of glutamate receptors. Second, in light of recently described interaction between cellular prion protein and some amyloid misfolded proteins, we will also discuss the molecular mechanisms potentially involved in protection against neurodegeneration in pathologies such as Alzheimer’s, Parkinson’s, and Huntington’s diseases.

JTD Keywords: Prion, Tau, Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, Neuroprotection

Human tau seeding and spreading occur following intracerebral inoculation of brain homogenates obtained from tauopathies in transgenic mice expressing natural or mutant tau, and in wild-type (WT) mice. The present study was geared to learning about the patterns of tau seeding, the cells involved and the characteristics of tau following intracerebral inoculation of homogenates from primary age-related tauopathy (PART: neuronal 4Rtau and 3Rtau), aging-related tau astrogliopathy (ARTAG: astrocytic 4Rtau) and globular glial tauopathy (GGT: 4Rtau with neuronal deposits and specific tau inclusions in astrocytes and oligodendrocytes). For this purpose, young and adult WT mice were inoculated unilaterally in the hippocampus or in the lateral corpus callosum with sarkosyl-insoluble fractions from PART, ARTAG and GGT cases, and were killed at variable periods of three to seven months. Brains were processed for immunohistochemistry in paraffin sections. Tau seeding occurred in the ipsilateral hippocampus and corpus callosum and spread to the septal nuclei, periventricular hypothalamus and contralateral corpus callosum, respectively. Tau deposits were mainly found in neurons, oligodendrocytes and threads; the deposits were diffuse or granular, composed of phosphorylated tau, tau with abnormal conformation and 3Rtau and 4Rtau independently of the type of tauopathy. Truncated tau at the aspartic acid 421 and ubiquitination were absent. Tau deposits had the characteristics of pre-tangles. A percentage of intracellular tau deposits co-localized with active (phosphorylated) tau kinases p38 and ERK 1/2. Present study shows that seeding and spreading of human tau into the brain of WT mice involves neurons and glial cells, mainly oligodendrocytes, thereby supporting the idea of a primary role of oligodendrogliopathy, together with neuronopathy, in the progression of tauopathies. In addition, it suggests that human tau inoculation modifies murine tau metabolism with the production and deposition of 3Rtau and 4Rtau, and by activation of specific tau kinases in affected cells.

JTD Keywords: Aging-related tau astrogliopathy, Globular glial tauopathy, Primary age-related tauopathy, Seeding, Spreading, Tau, Tauopathies

Cellular prion protein (PrPC) is largely responsible for transmissible spongiform encephalopathies (TSEs) when it becomes the abnormally processed and protease resistant form PrPSC. Physiological functions of PrPC include protective roles against oxidative stress and excitotoxicity. Relevantly, PrPC downregulates tau levels, whose accumulation and modification are a hallmark in the advance of Alzheimer's disease (AD). In addition to the accumulation of misfolded proteins, in the initial stages of AD-affected brains display both increased reactive oxygen species (ROS) markers and levels of PrPC. However, the factors responsible for the upregulation of PrPC are unknown. Thus, the aim of this study was to uncover the different molecular actors promoting PrPC overexpression. In order to mimic early stages of AD, we used β-amyloid-derived diffusible ligands (ADDLs) and tau cellular treatments, as well as ROS generation, to elucidate their particular roles in human PRNP promoter activity. In addition, we used specific chemical inhibitors and site-specific mutations of the PRNP promoter sequence to analyze the contribution of the main transcription factors involved in PRNP transcription under the analyzed conditions. Our results revealed that tau is a new modulator of PrPC expression independently of ADDL treatment and ROS levels. Lastly, we discovered that the JNK/c-jun-AP-1 pathway is involved in increased PRNP transcription activity by tau but not in the promoter response to ROS.

JTD Keywords: Alzheimer’s disease, Cellular prion protein, Promoter, Tau, Tauopathies

Introduction: Human tau seeding and spreading occur following intracerebral inoculation into different gray matter regions of brain homogenates obtained from tauopathies in transgenic mice expressing wild or mutant tau, and in wild-type (WT) mice. However, little is known about tau propagation following inoculation in the white matter. Objectives: The present study is geared to learning about the patterns of tau seeding and cells involved following unilateral inoculation in the corpus callosum of homogenates from sporadic Alzheimer's disease (AD), primary age-related tauopathy (PART: neuronal 4Rtau and 3Rtau), pure aging-related tau astrogliopathy (ARTAG: astroglial 4Rtau with thorn-shaped astrocytes TSAs), globular glial tauopathy (GGT: 4Rtau with neuronal tau and specific tau inclusions in astrocytes and oligodendrocytes, GAIs and GOIs, respectively), progressive supranuclear palsy (PSP: 4Rtau with neuronal inclusions, tufted astrocytes and coiled bodies), Pick's disease (PiD: 3Rtau with characteristic Pick bodies in neurons and tau containing fibrillar astrocytes), and frontotemporal lobar degeneration linked to P301L mutation (FTLD-P301L: 4Rtau familial tauopathy). Methods: Adult WT mice were inoculated unilaterally in the lateral corpus callosum with sarkosyl-insoluble fractions or with sarkosyl-soluble fractions from the mentioned tauopathies; mice were killed from 4 to 7 months after inoculation. Brains were fixed in paraformaldehyde, embedded in paraffin and processed for immunohistochemistry. Results: Tau seeding occurred in the ipsilateral corpus callosum and was also detected in the contralateral corpus callosum. Phospho-tau deposits were found in oligodendrocytes similar to coiled bodies and in threads. Moreover, tau deposits co-localized with active (phosphorylated) tau kinases p38 and ERK 1/2, suggesting active tau phosphorylation of murine tau. TSAs, GAIs, GOIs, tufted astrocytes, and tau-containing fibrillar astrocytes were not seen in any case. Tau deposits were often associated with slight myelin disruption and the presence of small PLP1-immunoreactive globules and dots in the ipsilateral corpus callosum 6 months after inoculation of sarkosyl-insoluble fractions from every tauopathy. Conclusions: Seeding and spreading of human tau in the corpus callosum of WT mice occurs in oligodendrocytes, thereby supporting the idea of a role of oligodendrogliopathy in tau seeding and spreading in the white matter in tauopathies. Slight differences in the predominance of threads or oligodendroglial deposits suggest disease differences in the capacity of tau seeding and spreading among tauopathies.

JTD Keywords: AD, ARTAG, GGT, PiD, Seeding and spreading, Tau, Tauopathies

Human tau seeding and spreading occur following intracerebral inoculation of brain homogenates obtained from tauopathies in transgenic mice expressing natural or mutant tau, and in wild-type (WT) mice. The present study was geared to learning about the patterns of tau seeding, the cells involved and the characteristics of tau following intracerebral inoculation of homogenates from primary age-related tauopathy (PART: neuronal 4Rtau and 3Rtau), aging-related tau astrogliopathy (ARTAG: astrocytic 4Rtau) and globular glial tauopathy (GGT: 4Rtau with neuronal deposits and specific tau inclusions in astrocytes and oligodendrocytes). For this purpose, young and adult WT mice were inoculated unilaterally in the hippocampus or in the lateral corpus callosum with sarkosyl-insoluble fractions from PART, ARTAG and GGT cases, and were killed at variable periods of three to seven months. Brains were processed for immunohistochemistry in paraffin sections. Tau seeding occurred in the ipsilateral hippocampus and corpus callosum and spread to the septal nuclei, periventricular hypothalamus and contralateral corpus callosum, respectively. Tau deposits were mainly found in neurons, oligodendrocytes and threads; the deposits were diffuse or granular, composed of phosphorylated tau, tau with abnormal conformation and 3Rtau and 4Rtau independently of the type of tauopathy. Truncated tau at the aspartic acid 421 and ubiquitination were absent. Tau deposits had the characteristics of pre-tangles. A percentage of intracellular tau deposits co-localized with active (phosphorylated) tau kinases p38 and ERK 1/2. Present study shows that seeding and spreading of human tau into the brain of WT mice involves neurons and glial cells, mainly oligodendrocytes, thereby supporting the idea of a primary role of oligodendrogliopathy, together with neuronopathy, in the progression of tauopathies. In addition, it suggests that human tau inoculation modifies murine tau metabolism with the production and deposition of 3Rtau and 4Rtau, and by activation of specific tau kinases in affected cells.

JTD Keywords: Aging-related tau astrogliopathy, Globular glial tauopathy, Primary age-related tauopathy, Seeding, Spreading, Tau, Tauopathies

Aging-related tau astrogliopathy (ARTAG) is defined by the presence of two types of tau-bearing astrocytes: thorn-shaped astrocytes (TSAs) and granular/fuzzy astrocytes in the brain of old-aged individuals. The present study is focused on TSAs in rare forms of ARTAG with no neuronal tau pathology or restricted to entorhinal and transentorhinal cortices, to avoid bias from associated tauopathies. TSAs show 4Rtau phosphorylation at several specific sites and abnormal tau conformation, but they lack ubiquitin and they are not immunostained with tau-C3 antibodies which recognize truncated tau at Asp421. Astrocytes in ARTAG have atrophic processes, reduced glial fibrillary acidic protein (GFAP) and increased superoxide dismutase 2 (SOD2) immunoreactivity. Gel electrophoresis and western blotting of sarkosyl-insoluble fractions reveal a pattern of phospho-tau in ARTAG characterized by two bands of 68 and 64 kDa, and several middle bands between 35 and 50 kDa which differ from what is seen in AD. Phosphoproteomics of dissected vulnerable regions identifies an increase of phosphorylation marks in a large number of proteins in ARTAG compared with controls. GFAP, aquaporin 4, several serine-threonine kinases, microtubule associated proteins and other neuronal proteins are among the differentially phosphorylated proteins in ARTAG thus suggesting a hyper-phosphorylation background that affects several molecules, including many kinases and proteins from several cell compartments and various cell types. Finally, present results show for the first time that tau seeding is produced in neurons of the hippocampal complex, astrocytes, oligodendroglia and along fibers of the corpus callosum, fimbria and fornix following inoculation into the hippocampus of wild type mice of sarkosyl-insoluble fractions enriched in hyper-phosphorylated tau from selected ARTAG cases. These findings show astrocytes as crucial players of tau seeding in tauopathies.

JTD Keywords: ARTAG, Kinases, Phosphorylation, Seeding, Tau, Thorn-shaped astrocytes

Gerstmann-Sträussler-Scheinker (GSS) syndrome is a fatal autosomal dominant neurodegenerative prionopathy clinically characterized by ataxia, spastic paraparesis, extrapyramidal signs and dementia. In some GSS familiar cases carrying point mutations in the PRNP gene, patients also showed comorbid tauopathy leading to mixed pathologies. In this study we developed an induced pluripotent stem (iPS) cell model derived from fibroblasts of a GSS patient harboring the Y218N PRNP mutation, as well as an age-matched healthy control. This particular PRNP mutation is unique with very few described cases. One of the cases presented neurofibrillary degeneration with relevant Tau hyperphosphorylation. Y218N iPS-derived cultures showed relevant astrogliosis, increased phospho-Tau, altered microtubule-associated transport and cell death. However, they failed to generate proteinase K-resistant prion. In this study we set out to test, for the first time, whether iPS cell-derived neurons could be used to investigate the appearance of disease-related phenotypes (i.e, tauopathy) identified in the GSS patient.

JTD Keywords: Cellular prion protein, Gerstmann-Sträussler-Scheinker, Induced pluripotent stem cells, Tau

Alzheimer's disease (AD) is characterized by the presence of amyloid plaques mainly consisting of hydrophobic β-amyloid peptide (Aβ) aggregates and neurofibrillary tangles (NFTs) composed principally of hyperphosphorylated tau. Aβ oligomers have been described as the earliest effectors to negatively affect synaptic structure and plasticity in the affected brains, and cellular prion protein (PrPC) has been proposed as receptor for these oligomers. The most widely accepted theory holds that the toxic effects of Aβ are upstream of change in tau, a neuronal microtubule-associated protein that promotes the polymerization and stabilization of microtubules. However, tau is considered decisive for the progression of neurodegeneration, and, indeed, tau pathology correlates well with clinical symptoms such as dementia. Different pathways can lead to abnormal phosphorylation, and, as a consequence, tau aggregates into paired helical filaments (PHF) and later on into NFTs. Reported data suggest a regulatory tendency of PrPC expression in the development of AD, and a putative relationship between PrPC and tau processing is emerging. However, the role of tau/PrPC interaction in AD is poorly understood. In this study, we show increased susceptibility to Aβ-derived diffusible ligands (ADDLs) in neuronal primary cultures from PrPC knockout mice, compared to wild-type, which correlates with increased tau expression. Moreover, we found increased PrPC expression that paralleled with tau at early ages in an AD murine model and in early Braak stages of AD in affected individuals. Taken together, these results suggest a protective role for PrPC in AD by downregulating tau expression, and they point to this protein as being crucial in the molecular events that lead to neurodegeneration in AD.

JTD Keywords: Aβ oligomers, Alzheimer's disease, Cellular prion protein, Microtubule-associated protein tau

One of the most challenging problems in intensive care is still the process of discontinuing mechanical ventilation, called weaning process. Both an unnecessary delay in the discontinuation process and a weaning trial that is undertaken too early are undesirable. In this study, we analyzed respiratory pattern variability using the respiratory volume signal of patients submitted to two different levels of pressure support ventilation (PSV), prior to withdrawal of the mechanical ventilation. In order to characterize the respiratory pattern, we analyzed the following time series: inspiratory time, expiratory time, breath duration, tidal volume, fractional inspiratory time, mean inspiratory flow and rapid shallow breathing. Several autoregressive modeling techniques were considered: autoregressive models (AR), autoregressive moving average models (ARMA), and autoregressive models with exogenous input (ARX). The following classification methods were used: logistic regression (LR), linear discriminant analysis (LDA) and support vector machines (SVM). 20 patients on weaning trials from mechanical ventilation were analyzed. The patients, submitted to two different levels of PSV, were classified as low PSV and high PSV. The variability of the respiratory patterns of these patients were analyzed. The most relevant parameters were extracted using the classifiers methods. The best results were obtained with the interquartile range and the final prediction errors of AR, ARMA and ARX models. An accuracy of 95% (93% sensitivity and 90% specificity) was obtained when the interquartile range of the expiratory time and the breath duration time series were used a LDA model. All classifiers showed a good compromise between sensitivity and specificity.

JTD Keywords: autoregressive moving average processes, feature extraction, medical signal processing, patient care, pneumodynamics, signal classification, support vector machines, time series, ARX, autoregressive modeling techniques, autoregressive models with exogenous input, autoregressive moving average model, breath duration time series, classification method, classifier method, discontinuing mechanical ventilation, expiratory time, feature extraction, final prediction errors, fractional inspiratory time, intensive care, interquartile range, linear discriminant analysis, logistic regression analysis, mean inspiratory flow, patient respiratory volume signal, pressure support level, pressure support ventilation, rapid shallow breathing, respiratory pattern variability characterization, support vector machines, tidal volume, weaning trial, Analytical models, Autoregressive processes, Biological system modeling, Estimation, Support vector machines, Time series analysis, Ventilation

One objective of mechanical ventilation is the recovery of spontaneous breathing as soon as possible. Remove the mechanical ventilation is sometimes more difficult that maintain it. This paper proposes the study of respiratory flow signal of patients on weaning trials process by autoregressive moving average model (ARMA), through the location of poles and zeros of the model. A total of 151 patients under extubation process (T-tube test) were analyzed: 91 patients with successful weaning (GS), 39 patients that failed to maintain spontaneous breathing and were reconnected (GF), and 21 patients extubated after the test but before 48 hours were reintubated (GR). The optimal model was obtained with order 8, and statistical significant differences were obtained considering the values of angles of the first four poles and the first zero. The best classification was obtained between GF and GR, with an accuracy of 75.3% on the mean value of the angle of the first pole.

JTD Keywords: Analytical models, Biological system modeling, Computational modeling, Estimation, Hospitals, Poles and zeros, Ventilation, Autoregressive moving average processes, Patient care, Patient monitoring, Pneumodynamics, Poles and zeros, Ventilation, ARMA model, T-tube test, Autoregressive moving average model, Extubation process, Mechanical ventilation, Optimal model, Patient classification, Respiratory flow signal, Roots, Spontaneous breathing, Weaning trials

Weaning trials process of patients in intensive care units is a complex clinical procedure. 153 patients under extubation process (T-tube test) were studied: 94 patients with successful trials (group S), 38 patients who failed to maintain spontaneous breathing and were reconnected (group F), and 21 patients with successful test but that had to be reintubated before 48 hours (group R). The respiratory pattern of each patient was characterized through the following time series: inspiratory time (T_I), expiratory time (T_E), breathing cycle duration (T_Tot), tidal volume (V_T), inspiratory fraction (T_I/T_Tot), half inspired flow (V_T/T_I), and rapid shallow index (f/V_T), where f is respiratory rate. Using techniques as autoregressive models (AR), autoregressive moving average models (ARMA) and autoregressive models with exogenous input (ARX), the most relevant parameters of the respiratory pattern were obtained. We proposed the evaluation of these parameters using classifiers as logistic regression (LR), linear discriminant analysis (LDA), support vector machines (SVM) and classification and regression tree (CART) to discriminate between patients from groups S, F and R. An accuracy of 93% (98% sensitivity and 82% specificity) has been obtained using CART classification.

JTD Keywords: Accuracy, Indexes, Logistics, Regression tree analysis, Support vector machines, Time series analysis, Autoregressive moving average processes, Medical signal processing, Pattern classification, Pneumodynamics, Regression analysis, Sensitivity, Signal classification, Support vector machines, Time series, SVM, T-tube testing, Autoregressive models-with-exogenous input, Autoregressive moving average models, Breathing cycle duration, Classification-and-regression tree, Expiratory time, Extubation process, Half inspired flow, Inspiratory fraction, Inspiratory time, Intensive care units, Linear discriminant analysis, Logistic regression, Rapid shallow index, Respiratory pattern parameter performance, Sensitivity, Spontaneous breathing, Support vector machines, Tidal volume, Time 48 hr, Time series, Weaning process classifiers

Alzheimer's disease neuropathology is characterized by neuronal death, amyloid beta-peptide deposits and neurofibrillary tangles composed of paired helical filaments of tau protein. Although crucial for our understanding of the pathogenesis of Alzheimer's disease, the molecular mechanisms linking amyloid beta-peptide and paired helical filaments remain unknown. Here, we show that amyloid beta-peptide-induced nitro-oxidative damage promotes the nitrotyrosination of the glycolytic enzyme triosephosphate isomerase in human neuroblastoma cells. Consequently, nitro-triosephosphate isomerase was found to be present in brain slides from double transgenic mice overexpressing human amyloid precursor protein and presenilin 1, and in Alzheimer's disease patients. Higher levels of nitro-triosephosphate isomerase (P < 0.05) were detected, by Western blot, in immunoprecipitates from hippocampus (9 individuals) and frontal cortex (13 individuals) of Alzheimer's disease patients, compared with healthy subjects (4 and 9 individuals, respectively). Triosephosphate isomerase nitrotyrosination decreases the glycolytic flow. Moreover, during its isomerase activity, it triggers the production of the highly neurotoxic methylglyoxal (n = 4; P < 0.05). The bioinformatics simulation of the nitration of tyrosines 164 and 208, close to the catalytic centre, fits with a reduced isomerase activity. Human embryonic kidney (HEK) cells overexpressing double mutant triosephosphate isomerase (Tyr164 and 208 by Phe164 and 208) showed high methylglyoxal production. This finding correlates with the widespread glycation immunostaining in Alzheimer's disease cortex and hippocampus from double transgenic mice overexpressing amyloid precursor protein and presenilin 1. Furthermore, nitro-triosephosphate isomerase formed large beta-sheet aggregates in vitro and in vivo, as demonstrated by turbidometric analysis and electron microscopy. Transmission electron microscopy (TEM) and atomic force microscopy studies have demonstrated that nitro-triosephosphate isomerase binds tau monomers and induces tau aggregation to form paired helical filaments, the characteristic intracellular hallmark of Alzheimer's disease brains. Our results link oxidative stress, the main etiopathogenic mechanism in sporadic Alzheimer's disease, via the production of peroxynitrite and nitrotyrosination of triosephosphate isomerase, to amyloid beta-peptide-induced toxicity and tau pathology.

JTD Keywords: Alzheimer's disease, Amyloid β-peptide, Tau protein, Triosephosphate isomerase, Peroxynitrite