Relevance of host tau in tau seeding and spreading in 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.     

The Relationship Between Development of Neuronal and Astrocytic Tau Pathologies in Subcortical Nuclei and Progression of Argyrophilic Grain Disease

Progressive supranuclear palsy (PSP) cases frequently have argyrophilic grain disease (AGD). However, the PSP‐like tau pathology in AGD cases has not been fully clarified. To address this, we examined tau pathologies in the subcortical nuclei and frontal cortex in 19 AGD cases that did not meet the pathological criteria of PSP or corticobasal degeneration, nine PSP cases and 20 Braak NFT stage‐matched controls. Of the 19 AGD cases, five (26.3%) had a few Gallyas‐positive tau‐positive tufted astrocytes (TAs) and Gallyas‐negative tau‐positive TA‐like astrocytic inclusions (TAIs), and six (31.6%) had only TAIs in the striatum and/or frontal cortex. Subcortical tau pathology was sequentially and significantly greater in AGD cases lacking these tau‐positive astrocytic lesions, AGD cases having them, and PSP cases than in controls. There was a significant correlation between three histologic factors, including the AGD stage and the quantities of subcortical neuronal and astrocytic tau pathologies. Tau immunoblotting demonstrated 68‐ and 64‐kDa bands and 33‐kDa low‐molecular mass tau fragments in PSP cases, and although with lesser intensity, in AGD cases with and without TAs and TAIs also. Given these findings, the progression of AGD may be associated with development of the neuronal and astrocytic tau pathologies characteristic of PSP.     

Protein astrogliopathies in human neurodegenerative diseases and aging

Neurodegenerative diseases are characterized by progressive dysfunction and loss of neurons associated with depositions of pathologically altered proteins showing hierarchical involvement of brain regions. The role of astrocytes in the pathogenesis of neurodegenerative diseases is explored as contributors to neuronal degeneration or neuroprotection pathways, and also as potential mediators of the transcellular spreading of disease‐associated proteins. Protein astrogliopathy (PAG), including deposition of amyloid‐β, prion protein, tau, α‐synuclein, and very rarely transactive response DNA‐binding protein 43 (TDP‐43) is not unprecedented or unusual in neurodegenerative diseases. Morphological characterization of PAG is considered, however, only for the neuropathological diagnosis and classification of tauopathies. Astrocytic tau pathology is seen in primary frontotemporal lobar degeneration (FTLD) associated with tau pathologies (FTLD‐Tau), and also in the form of aging‐related tau astrogliopathy (ARTAG). Importantly, ARTAG shares common features with primary FTLD‐Tau as well as with the astroglial tau pathologies that are thought to be hallmarks of a brain injury‐related tauopathy known as chronic traumatic encephalopathy (CTE). Supported by experimental observations, the morphological variability of PAG might reflect distinct pathogenic involvement of different astrocytic populations. PAG might indicate astrocytic contribution to spreading or clearance of disease‐associated proteins, however, this might lead to astrocytic dysfunction and eventually contribute to the degeneration of neurons. Here, we review recent advances in understanding ARTAG and other related forms of PAG.     

A parietal‐to‐frontal shift in the P300 is associated with compensation of tactile discrimination deficits in late middle‐aged adults

Tactile perception declines with age on both behavioral and neurophysiological levels. Less well understood is how neurophysiological changes relate to tactile discrimination performance in middle adulthood. A tactile discrimination task was conducted while ERPs were measured in three groups of healthy adults aged 20 to 66 years. Accuracy was lowest in late middle adulthood (56–66 years) while somatosensory ERP components (P50, N70, P100, N140) were comparable across age groups. The cognitive P300 revealed age‐related differences in scalp distribution typical for older adults to already be present in late middle adulthood. Increased recruitment of frontal cognitive processes was positively related to performance in later middle adulthood. Our results further the understanding of age‐related differences in tactile perception during middle adulthood and the importance of cognitive processes to compensate for age‐related decline.     

Comparative analysis of NK cell subset distribution in normal and lymphoproliferative disease of granular lymphocyte conditions

We have characterized the heterogeneity of human blood NK cell subsets defined by expression of KIR, lectin like receptors and NK cell differentiation markers within a cohort of 51 healthy Caucasian individuals. High inter-individual variability in cell surface expression of most NK cell markers is observed. Range values defining NK cell subsets in healthy donors were further used as references to characterize 14 patients with NK-type lymphoproliferative disease of granular lymphocytes (NK-LDGL). Alterations of the KIR repertoire were noted in all NK-LDGL patients. NK cell expansions were classified as oligoclonal KIR(+) or as non-detectable KIR ((nd)KIR) using anti-KIR2DL1/2DS1, anti-KIR2DL2/2DL3/2DS2, anti-KIR3DL1 and anti-KIR2DS4 monoclonal antibodies. A major reduction in the size of the CD56(bright) NK cell subset was a constant feature of NK-LDGL. Altered distribution of CD94(+), CD161(+), and CD162R(+) NK cell subsets was also observed in NK-LDGL patients. Considering the potential role of NK cells in eliminating tumors or virus-infected cells, the reference values defined in this study should be valuable to characterize both quantitative and qualitative alterations of the NK cell repertoire in pathological conditions and to monitor NK cell reconstitution following hematopoietic transplantation.     

Elevation of casein kinase 1ε associated with TDP‐43 and tau pathologies in Alzheimer's disease

Alzheimer's disease (AD) is characterized by the presence of extracellular amyloid β plaques and intraneuronal neurofibrillary tangles of hyperphosphorylated microtubule‐associated protein tau in the brain. Aggregation of transactive response DNA‐binding protein of 43 kDa (TDP‐43) in the neuronal cytoplasm is another feature of AD. However, how TDP‐43 is associated with AD pathogenesis is unknown. Here, we found that casein kinase 1ε (CK1ε) phosphorylated TDP‐43 at Ser403/404 and Ser409/410. In AD brains, the level of CK1ε was dramatically increased and positively correlated with the phosphorylation of TDP‐43 at Ser403/404 and Ser409/410. Overexpression of CK1ε promoted its cytoplasmic aggregation and suppressed TDP‐43‐promoted tau mRNA instability and tau exon 10 inclusion, leading to an increase of tau and 3R‐tau expressions. Levels of CK1ε and TDP‐43 phosphorylation were positively correlated with the levels of total tau and 3R‐tau in human brains. Furthermore, we observed, in pilot immunohistochemical studies, that the severe tau pathology was accompanied by robust TDP‐43 pathology and a high level of CK1ε. Taken together, our findings suggest that the elevation of CK1ε in AD brain may phosphorylate TDP‐43, promote its cytoplasmic aggregation and suppress its function in tau mRNA processing, leading to acceleration/exacerbation of tau pathology. Thus, the elevation of CK1ε may link TDP‐43 to tau pathogenesis in AD brain.     

Factors affecting quality of life in children and adolescents with hypermobile Ehlers‐Danlos syndrome/hypermobility spectrum disorders

Hypermobile Ehlers‐Danlos syndrome (hEDS) is a hereditary disorder of connective tissue, often presenting with complex symptoms can include chronic pain, fatigue, and dysautonomia. Factors influencing functional disability in the pediatric hEDS population are incompletely studied. This study's aims were to assess factors that affect quality of life in children and adolescents with hEDS. Individuals with hEDS between the ages 12–20 years and matched parents were recruited through retrospective chart review at two genetics clinics. Participants completed a questionnaire that included the Pediatric Quality of Life Inventory (PedsQL?), PedsQL Multidimentional Fatigue Scale, Functional Disability Inventory, Pain‐Frequency‐Severity‐Duration Scale, the Brief Illness Perception Questionnaire, measures of anxiety and depression, and helpful interventions. Survey responses were completed for 47 children and adolescents with hEDS/hypermobility spectrum disorder (81% female, mean age 16 years), some by the affected individual, some by their parent, and some by both. Clinical data derived from chart review were compared statistically to survey responses. All outcomes correlated moderately to strongly with each other. Using multiple regression, general fatigue and pain scores were the best predictors of the PedsQL total score. Additionally, presence of any psychiatric diagnosis was correlated with a lower PedsQL score. Current management guidelines recommend early intervention to prevent disability from deconditioning; these results may help identify target interventions in this vulnerable population.     

Impaired p53/CEP‐1 is associated with lifespan extension through an age‐related imbalance in the energy metabolism of C. elegans

In the nematode Caenorhabditis elegans, the mammalian tumor suppressor p53 ortholog CEP‐1 mediates the stress response, activates germ line apoptosis and regulates meiotic chromosome segregation. A reduction in its expression, which frequently occurs in mammalian cancer cells, extends lifespan and induces an adaptive response in C. elegans. However, these effects do not involve an increase in oxidative stress resistance. Here, we showed that intermittent exposure to hyperoxia, which induces oxidative stress resistance and lowers the production of ROS derived from mitochondrial respiration in C. elegans, slightly improved the lifespan extension of cep‐1 mutant. Interestingly, ATP levels were increased without an increase in oxygen consumption in cep‐1 mutant during aging. In the wild‐type, lactate levels and consequentially the lactate/pyruvate ratio decreased during aging in adults. Furthermore, the expression levels of mitochondrial respiration‐related sco‐1, which is a target of p53/CEP‐1, as well as those of gluconeogenesis regulation and mammalian sirtuin ortholog genes, were also increased in the aged and adaptive conditioned wild‐type animals. In contrast, the lactate/pyruvate ratio increased in cells of the cep‐1 mutant and was amplified by intermittent hyperoxia. These results suggest that impaired p53/CEP‐1 leads to an imbalance in the age‐related energy metabolic alteration between mitochondrial oxidative phosphorylation and aerobic glycolysis and plays an important role in the extension of both intact and adaptive lifespans.     

Age differences in the association of obstructive sleep apnea risk with cognition and quality of life

Using a sample of 2925 stroke‐free participants drawn from a national population‐based study, we examined cross‐sectional associations of obstructive sleep apnea (OSA) risk with cognition and quality of life and whether these vary with age, while controlling for demographics and comorbidities. Included participants from the REasons for Geographic And Racial Differences in Stroke (REGARDS) study were aged 47–93 years. OSA risk was categorized as high or low based on responses to the Berlin Sleep Questionnaire. Cognitive function was assessed with standardized fluency and recall measures. Depressive symptoms were assessed with the four‐item Center for Epidemiologic Studies Depression Scale. Health‐related quality of life (HRQoL) was assessed with the Medical Outcomes Study Short Form‐12 (SF‐12). Multivariate analyses of covariance (mancova ) statistics were applied separately to the cognitive and quality of life dependent variables while accounting for potential confounders (demographics, comorbidities). In fully adjusted models, those at high risk for OSA had significantly lower cognitive scores (Wilks’ lambda = 0.996, F_3,2786 = 3.31, P < 0.05) and lower quality of life [depressive symptoms and HRQoL] (Wilks’ lambda = 0.989, F_3,2786 = 10.02, P < 0.0001). However, some of the associations were age‐dependent. Differences in cognition and quality of life between those at high and low obstructive sleep apnea risk were most pronounced during middle age, with attenuated effects after age 70 years.     

Dendritic cell differentiation with prostaglandin E2 results in selective attenuation of the extracellular signal-related kinase pathway and decreased interleukin-23 production

The balance between interleukin (IL)‐12 and IL‐23 production by dendritic cells (DCs) is crucial for the induction of appropriate immune responses. In the present study, we examined the effect of prostaglandin E₂ (PGE₂) treatment of DCs during differentiation on IL‐12 and IL‐23 production in response to Toll‐like receptor (TLR) stimulation. Bone marrow‐derived DCs were generated by culturing murine bone marrow cells with granulocyte–macrophage colony‐stimulating factor (GM‐CSF) alone (cont‐DCs) or GM‐CSF plus PGE₂ (PG‐DCs). Upon TLR stimulation, IL‐23 production by PG‐DCs was markedly decreased compared with that by cont‐DCs. However, no significant difference was detected in IL‐12 production between these types of DC. To examine the mechanism underlying the impaired production of IL‐23 by PG‐DCs, we analysed the activities of extracellular signal‐related kinases (ERKs) 1/2, p38 mitogen‐activated protein kinase (MAPK), c‐jun N‐terminal kinases 1/2, Akt, and nuclear factor (NF)‐κB (p65) in these DCs upon TLR stimulation. The ERK1/2 activity in PG‐DCs was significantly lower than that of cont‐DCs. No significant differences were detected in the activities of other molecules between cont‐DCs and PG‐DCs. In addition, treatment of cont‐DCs with U0126, a specific inhibitor of the ERK pathway, reduced the TLR‐mediated production by the DCs of IL‐23 but not IL‐12. Thus, DC development in the presence of PGE₂ results in selective attenuation of the ERK pathway. The attenuation of ERK activation appears to be responsible for the decreased IL‐23 production by PG‐DCs.     

High-resolution melting curve analysis for high-throughput genotyping of NOD2/CARD15 mutations and distribution of these mutations in Slovenian inflammatory bowel diseases patients

Inflammatory bowel diseases (IBD) are usually classified into Crohn's disease (CD) and ulcerative colitis (UC). NOD2/CARD15 was the first identified CD-susceptibility gene and was confirmed as the most potent disease gene in CD pathogenesis. Three NOD2/CARD15 variants, namely two missense polymorphisms R702W (rs2066844) and G908R (rs2066845), and a frame shift polymorphism L1007fs (rs2066847), were associated with CD in Caucasian populations. High resolution melting analysis (HRMA) with saturation LCGreen dyes was previously reported as a simple, inexpensive, accurate and sensitive method for genotyping and/or scanning of rare variants. For this reasons we used qPCR-HRMA for genotyping NOD2/CARD15 variants in 588 Slovenian IBD patients and 256 healthy controls. PCR-RFLP was used as a reference method for genotyping of clinical samples. The optimization of an HRM experiment required careful design and adjustment of main parameters, such as primer concentration, MgCl_{2} concentration, probe design and template DNA concentration. Different HRMA approaches were tested and used to develop a reliable and low-cost SNP genotyping assays for polymorphisms in NOD2/CARD15 gene. Direct HRMA was the fastest and cheapest HRMA approach for L1007fs and R702W polymorphisms, yet for G908R polymorphism sufficient reliability was achieved after introduction of unlabeled probe. In association analysis, we found statistically significant association of L1007fs (p =0.001, OR=3.011, CI95%=1.494-6.071) and G908R (p=2.62 × 10^{-4}, OR=14.117, CI95%= 1.884-105.799) polymorphisms with CD patients. At least one of NOD2/CARD15 polymorphisms was found in 78/354 (22.03% (12.69%) in UC patients and in 26/256 (10.15%) in healthy controls. We have successfully implemented NOD2/CARD15 HRMA assays, which may contribute to the development of genetic profiles for risk prediction of developing CD and for differential diagnosis of CD vs. UC.     

No mutations of SAP/SH2D1A/DSHP and perforin genes in patients with Epstein-Barr virus-associated hemophagocytic syndrome in Japan

Recently, mutations of two genes, SAP/SH2D1A/DSHP and perforin genes, have been identified in two fatal inherited lymphoproliferative diseases, X-linked lymphoproliferative disease and familial hemophagocytic lymphohistiocytosis, respectively. Epstein-Barr virus (EBV)-associated hemophagocytic syndrome, a fulminant non-inherited T-cell lymphoproliferative disease, is relatively common in Japan and is extremely difficult to distinguish from X-linked lymphoproliferative disease and familial hemophagocytic lymphohistiocytosis, especially in sporadic cases, because of similarities in clinical and laboratory features. Mutation analysis was carried out of samples obtained from 14 patients with EBV-associated hemophagocytic syndrome by sequencing the genomic SAP/SH2D1A/DSHP and perforin genes. However, a specific mutation was not identified in either of the genes, suggesting that mutations of the SAP/SH2D1A/DSHP and perforin genes are not responsible for the pathogenesis of EBV-associated hemophagocytic syndrome in Japan.     

A novel truncating variant within exon 7 of KAT6B associated with features of both Say–Barber–Bieseker–Young–Simpson syndrome and genitopatellar syndrome: Further evidence of a continuum in the clinical spectrum of KAT6B‐related disorders

KAT6B sequence variants have been identified in both patients with the Say–Barber–Biesecker–Young–Simpson syndrome (SBBYSS) and in the genitopatellar syndrome (GPS). In SBBYSS, they were reported to affect mostly exons 16–18 of KAT6B, and the predicted mechanism of pathogenesis was haploinsufficiency or a partial loss of protein function. Truncating variants in KAT6B leading to GPS appear to cluster within the proximal portion of exon 18, associated with a dominant‐negative effect of the mutated protein, most likely. Although SBBYSS and GPS have been initially considered allelic disorders with distinctive genetic and clinical features, there is evidence that they represent two ends of a spectrum of conditions referable as KAT6B‐related disorders. We detected a de novo truncating variant within exon 7 of KAT6B in a 8‐year‐old female who presented with mild intellectual disability, facial dysmorphisms highly consistent with SBBYSS, and skeletal anomalies including exostosis, that are usually considered component manifestations of GPS. Following the clinical diagnosis driven by the striking facial phenotype, we analyzed the KAT6B gene by NGS techniques. The present report highlights the pivotal role of clinical genetics in avoiding clear‐cut genotype‐phenotype categories in syndromic forms of intellectual disability. In addition, it further supports the evidence that a continuum exists within the clinical spectrum of KAT6B‐associated disorders.

     

Polymorphisms at GLUT1 gene are not associated with the development of TSP/HAM in Brazilian HTLV‐1 infected individuals and the discovery of a new polymorphism at GLUT1 gene

The development of HTLV‐1 associated clinical manifestations, such as TSP/HAM and ATLL, occur in 2–4% of the infected population and it is still unclear why this infection remains asymptomatic in most infected carriers. Recently, it has been demonstrated that HTLV uses the Glucose transporter type 1 (GLUT1) to infect T‐CD4⁺ lymphocytes and that single nucleotide polymorphisms (SNP) in the GLUT1 gene are associated with diabetic nephropathy in patients with diabetes mellitus in different populations. These polymorphisms could contribute to a higher GLUT1 protein expression on cellular membrane, facilitating the entry of HTLV and its transmission cell by cell. This could result in a higher provirus load and consequently in the development of TSP/HAM. To evaluate the role of GLUT1 gene polymorphisms in the development of TSP/HAM in HTLV‐1 infected individuals, the g.22999G > T, g.15339T > C and c.‐2841A > T sites were analyzed by PCR/RFLP or sequencing in 244 infected individuals and 102 normal controls. The proviral load of the HTLV‐1 infected patients was also analyzed using Real Time Quantitative PCR. Genotypic and allelic frequencies of the three sites did not differ significantly between controls and HTLV‐1 infected individuals. There was no difference in genotypic and allelic distributions among patients as to the presence or absence of HTLV‐1 associated clinic manifestations. As regards the quantification of the provirus load, we observed a significant reduction in the asymptomatic individuals compared with the oligosymptomatic and TSP/HAM individuals. These results suggest that g.22999G > T, g.15339T > C, and c.‐2841A > T SNP do not contribute to HTLV‐1 infection nor to the genetic susceptibility of TSP/HAM in Brazilian HTLV‐1 infected individuals. J. Med. Virol. 81:552–557, 2009. © 2009 Wiley‐Liss, Inc.     

BDCA3 expression is associated with high IFN‐λ production by CD34+‐derived dendritic cells generated in the presence of GM‐CSF,IL‐4, and/or TGF‐β

High BDCA3 expression is associated with a specific human IFN‐λ‐producing dendritic cell (DC) subset. However, BDCA3 has also been detected on other DC subsets. Thus far, development and function of BDCA3 expression on DCs remains poorly understood. Human Langerhans cells (LCs) and interstitial DCs (intDCs) can be generated in vitro by differentiation of CD34⁺ hematopoietic progenitors via distinct precursor DCs (preDCs), CD1a⁺ preDCs, and CD14⁺ preDCs, respectively. Here, we identified BDCA3 expression in this well‐known GM‐CSF/TNF‐α‐driven culture system and described the effect of IL‐4 and/or TGF‐β on induction of BDCA3 expression. In control or TGF‐β cultures, BDCA3 was only detected on CD14⁺ preDC‐derived intDCs. IL‐4 induced BDCA3 expression in both CD14⁺‐derived and CD1a⁺‐derived cultures. TGF‐β and IL‐4 together further increased CD14⁺‐derived and CD1a⁺‐derived BDCA3⁺ DC frequencies, which partly expressed CLEC9A, but were not identical to the BDCA3^highCLEC9A⁺ DC subset in vivo. Importantly, BDCA3⁺ cells, but not BDCA3^? cells, in this system produced high IFN‐λ levels upon polyinosinic:polycytidylic acid (polyI:C) stimulation. This culture system, in which BDCA3 expression is preferentially associated with the intDC lineage and IFN‐λ‐producing capacity, will greatly contribute to further research on the function and regulation of BDCA3 expression and IFN‐λ production by DCs.     

Weight affect relapse rates in latinos with genotype 2/3 chronic hepatitis C (CHC) treated with peg IFN alfa-2a (Pegasys) 180 mcg/week and 800 mg daily of ribavirin for 24 weeks

Efficacy of chronic hepatitis C (CHC) treatment with Peg-IFN and Ribavirin (RBV) is superior for genotypes 2/3 (GT-2/3) than for genotype 1 (GT-1) patients. Efficacy of treatment in Latinos infected with GT-2/3 is unknown. The purpose of the study was to examine efficacy of Peg-IFN/RBV in Latinos and factors that predict sustained viral response (SVR). This was a retrospective study of GT-2/3 patients treated with Peg-IFN alfa-2a and RBV for 24 weeks. Multiple baseline characteristics were evaluated. SVR and relapse rates were calculated, as well as multiple regression models performed to examine factors that predict SVR and relapse, as genotype, HVL, weight, steatosis at liver biopsy, total cholesterol triglyceride and diabetes. Thirty five consecutive patients were included in the study; [26] GT-2 and [9] GT-3. Baseline characteristics were similar between both genotypes. SVR was (18/26) or 69.2% for GT-2 and (8/9) or 88.9% for GT-3 for combined SVR of (26/35), 74.3%. Relapse rates were 28.0% for GT-2 and 11.1% for GT-3 patients for a combined relapse rate of 23.5%. Patients heavier than 75 kg had relapse rates twofold higher than leaner patients, (6/21) or 28.6% versus (2/14) or 14.3% (P = 0.088). Weight increase in kg was the only predictor for risk of relapse, P = 0.043 (SD 0.0445 95% CI 1.0026-1.1772). In conclusion, Latinos heavier than 75 kg with GT-2/3 HCV infection achieve lower SVR than those who weight less than 75 kg, because a higher relapse rate. More research in ethnic and racial minorities is needed to further establish optimal treatment in this population.