Ischemic tau protein gene induction as an additional key factor driving development of Alzheimer’s phenotype changes in CA1 area of hippocampus in an ischemic model of Alzheimer’s disease

Background

Tauopathies are a class of neurodegenerative illnesses associated with the aberrant accumulation of the tau protein in the brain. The best known out of these diseases is Alzheimer’s disease, a disorder where the microtubule associated tau protein becomes hyperphosphorylated (which lowers its binding affinity to microtubules) and accumulates inside neurons in the form of tangles. In this study, we attempt to find out whether brain ischemia may play an important role in tau protein gene alterations.

肝素类药物防治阿尔采末病的研究进展

本文分析了阿尔采末病(AD)的病理机制,对肝素类药物神经保护机制的进展进行了综述。阐明了肝素类药物可通过调节IP3受体介导的细胞内钙释放,影响淀粉样蛋白(Aβ)沉积及其毒性、调节tau蛋白的磷酸化状态,保护胆碱能神经元等发挥神经保护作用,从而延缓AD的发生与发展。     

Immunotherapy for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia worldwide. In AD the normal soluble amyloid β (sAβ) peptide is converted into oligomeric/fibrillar Aβ. The oligomeric forms of Aβ are thought to be the most toxic, while fibrillar Aβ becomes deposited as amyloid plaques and congophilic angiopathy, which serve as neuropathological markers of the disease. In addition the accumulation of abnormally phosphorylated tau as soluble toxic oligomers and as neurofibrillary tangles is a critical part of the pathology. Numerous therapeutic interventions are under investigation to prevent and treat AD. Among the more exciting and advanced of these approaches is vaccination. Active and passive Immunotherapy targeting only Aβ has been successful in many AD model animal trials; however, the more limited human data has shown much less benefit so far, with encephalitis occurring in a minority of patients treated with active immunization and vasogenic edema or amyloid-related imaging abnormalities (ARIA) being a complication in some passive immunization trials. Therapeutic intervention targeting only tau has been tested only in mouse models; and no approaches targeting both pathologies concurrently has been attempted, until very recently. The immune approaches tried so far were targeting a self-protein, albeit in an abnormal conformation; however, effective enhanced clearance of the disease associated conformer has to be balanced with the potential risk of stimulating excessive toxic inflammation. The design of future more effective immunomodulatory approaches will need to target all aspects of AD pathology, as well as specifically targeting pathological oligomeric conformers, without the use of any self-antigen.     

Changes of serum Tau, GFAP, TNF-α and malonaldehyde after blast-related traumatic brain injury

Objective： To determine the changes of serum Tau protein, glial fibrillary acidic protein （GFAP）, tumor necrosis factor alpha （TNF-α）, and malonaldehyde （MDA） in rats after blast-related traumatic brain injury （BTBI） and to provide relative information for further studies on BTBI mechanism and seek specific biomarkers for BTBI. Methods： Ninety male Sprague-Dawley rats were randomly assigned into three groups： control group, moderate blast injury group, and severe blast injury group （n=30 for each）. Rats in the moderate and severe blast injury groups were respectively exposed to corresponding levels of BTBI. After explosion, serum levels of Tau, GFAP, TNF-α, and MDA in each group were determined by Elisa assay at different time points after injury （8 h, 24 h, 3 d, and 6 d）. The extent of brain damage was detected by Nissl staining and TUNEL assay. Results： Serum levels of Tau and GFAP rapidly increased and reached the peak at 24 h after either moderate or severe blast injury. All the values were significantly higher than control group at all time points （P〈0.05）. Serum TNF-α level of both injury groups peaked at 8 h after BTBI and stayed significantly higher than control group at all time points （P〈0.05）. Serum MDA of two injury groups began to significantly increase at 3 d and the level stayed significantly higher than control group until 6 d （P〈0.05）. Moreover, unlike the other biomarkers, serum MDA of severe blast injury group was significantly higher than moderate blast injury group at 6 d （P〈0.05）. Conclusion： The changes of serum Tau, GFAP, and TNF-α showed a good sensitivity at the acute phase after BTBI （within 24 h）. However, their specificity and correlation with the extent of injury were limited in this experiment. Moreover, although the change of serum MDA showed a poor sensitivity and specificity to the diagnosis of BTBI during the first few days, it can reflect the injury degree at 6 d after injury. Therefore, further studies are nee     

The clinical use of cerebrospinal fluid biomarker testing for Alzheimer's disease diagnosis: A consensus paper from the Alzheimer's Biomarkers Standardization Initiative

BackgroundCerebrospinal fluid (CSF) biomarkers β-amyloid 1-42 (Aβ_1-42), also expressed as Aβ_1-42:Aβ_1-40 ratio, T-tau, and P-tau_181P, have proven diagnostic accuracy for mild cognitive impairment and Alzheimer's disease (AD). How to use, interpret, and disclose biomarker results drives the need for standardization.MethodsPrevious Alzheimer's Biomarkers Standardization Initiative meetings discussed preanalytical issues affecting Aβ_1-42 and tau in CSF. This second round of consensus meetings focused on issues related to clinical use of AD CSF biomarkers.ResultsConsensus was reached that lumbar puncture for AD CSF biomarker analysis be considered as a routine clinical test in patients with early-onset dementia, at the prodromal stage or with atypical AD. Moreover, consensus was reached on which biomarkers to use, how results should be interpreted, and potential confounding factors.ConclusionsChanges in Aβ_1-42, T-tau, and P-tau_181P allow diagnosis of AD in its prodromal stage. Conversely, having all three biomarkers in the normal range rules out AD. Intermediate conditions require further patient follow-up.     

Tau蛋白表达与复发转移性乳腺癌紫杉醇化疗敏感性关系

【摘要】〓目的〓探讨复发转移性乳腺癌组织中Tau蛋白的表达情况及其与紫杉醇药物姑息性化疗敏感性的相关性。方法〓采用免疫组化Envision二步法检测136例复发转移性乳腺癌患者转移病灶的组织样本中Tau蛋白的表达水平,χ2检验或Fisher 精确概率法分析其与复发转移性乳腺癌临床病理特征及与紫杉醇类药物姑息性化疗敏感性的关系。结果〓复发转移性乳腺癌患者Tau蛋白的阳性表达率为28.68%(39/136),Tau蛋白的阳性表达与患者的年龄、身体密度、ECOG分值、病理分型、组织学分级、孕激素受体、表皮生长因子受体-2、增殖指数Ki-67及P53阳性表达均无相关性,但与乳腺癌组织的雌激素受体表达相关(P<0.05)。而且,Tau蛋白的表达与紫杉醇药物性化疗疗效相关(P<0.01)。结论〓Tau蛋白表达水平与复发转移性乳腺癌紫杉醇类药物姑息性化疗敏感性呈负相关,临床检测Tau蛋白表达可能可作为复发转移性乳腺癌行紫杉醇类药物性姑息性化疗方案的选择依据。     

基于^18F-APN-1607PET影像的阿尔茨海默病tau蛋白沉积相关疾病模式探究

目的 探究阿尔茨海默病(AD)患者^18F-APN-1607 PET影像脑内tau蛋白沉积相关疾病模式(tauRDP).方法 收集复旦大学附属华山医院17例AD患者[男6例,女11例;年龄(61.7±12.3)岁;简易精神状态检查量表(MMSE)评分(17.6±7.9)分]和10名年龄性别匹配的健康对照(NC)者[男6名,女4名;年龄(61.2±4.7)岁]的^18F-APN-1607脑影像.在体素层面使用基于主成分分析(PCA)的尺度子轮廓模型(SSM)技术构建tauRDP,计算每个样本tauRDP表达值,通过两样本t检验比较tauRDP表达值在AD患者和健康对照者间的差异;使用Pearson相关分析AD患者tauRDP表达值与MMSE评分的相关性.结果 AD患者的tauRDP脑区主要包括:中央前回、背外侧额上回、额中回、岛盖部额下回、三角部额下回、补充运动区、内侧额上回、左侧内侧和旁扣带脑回、右侧楔叶、枕上回、枕中回、中央后回、顶上回、顶下缘角回、缘上回、角回、楔前叶和颞中回.AD患者tauRDP表达值为(12.6±8.0),与NC(0.0±1.0)间差异有统计学意义(t=4.395,P<0.001),且AD组tauRDP表达值与MMSE得分相关(r=-0.566,P=0.018).结论 基于SSM/PCA方法建立的tauRDP可用于定量表达tau蛋白沉积空间分布异常,tauRDP表达值有潜力用于评估AD严重程度.     

The genetics of primary progressive aphasia

Background: Primary progressive aphasia (PPA) is a disorder in which language impairment is the initial and predominant symptom. Three main phenotypes are described, the nonfluent variant (nfvPPA), the semantic variant (svPPA) and the logopenic variant (lvPPA). Although PPA is most commonly a sporadic disorder, recent studies have shown an association of PPA with mutations in a number of genes.

Aims: To understand the extent to which PPA may be inherited, which genetic mutations may cause it, and whether the phenotypes of genetic PPA differ from sporadic PPA.

Main Contribution: In around 20–30% of patients with PPA, a family history is present although nfvPPA is more heritable than svPPA and lvPPA which are both usually sporadic disorders. Mutations in the progranulin (GRN) and chromosome 9 open reading frame 72 (C9orf72), genes are the major causes of genetic PPA.

Conclusions: Key pointers that may suggest testing for a GRN mutation in PPA are a family history of one of the disorders within the frontotemporal dementia spectrum, a nfvPPA phenotype, particularly if presenting with a prominent anomia and asymmetrical fronto-temporo-parietal atrophy. In someone with nfvPPA and a family history, GRN should be tested initially but a search for hexanucleotide repeat expansions in the C9orf72 gene should be performed if negative, particularly if there are features of motor neurone disease, or a family history of someone with motor neurone disease. Mutations in other genes are only very rare causes of PPA but if GRN and C9orf72 are both negative, testing for mutations in the microtubule-associated protein tau (MAPT), valosin-containing protein (VCP) and presenilin 1 (PSEN1) should be considered.     

Why Alzheimer trials fail: removing soluble oligomeric beta amyloid is essential,inconsistent, and difficult

Before amyloid formation, peptides cleaved from the amyloid precursor protein (APP) exist as soluble oligomers. These are extremely neurotoxic. Their concentration is strongly correlated with synaptic impairment in animals and parallel cognitive decline in animals and humans. Clinical trials have largely been aimed at removing insoluble beta amyloid in senile plaques and have not reduced soluble load. Even treatment that should remove soluble oligomers has not consistently reduced the load. Failure to significantly improve cognition has frequently been attributed to failure of the amyloid hypothesis or to irreversible alteration in the brain. Instead, trial failures may be because of failure to significantly reduce load of toxic Aβ oligomers. Moreover, targeting only synthesis of Aβ peptides, only the oligomers themselves, or only the final insoluble amyloid may fail to significantly reduce soluble load because of the interrelationship between these 3 points in the amyloid cascade. Thus, treatments may fail unless trials target simultaneously all 3 points in the equation–"triple therapy". Cerebrospinal fluid analysis and other monitoring tools may in the future provide reliable measurement of soluble load. But currently, only analysis of autopsied brains can provide this data and thus enable proper evaluation and explanation of the outcome of clinical trials. These data are essential before attributing trial failures to the advanced nature of the disease or asserting that failures prove that the theory linking Alzheimer's disease to products of amyloid precursor protein is incorrect.     

Assessment of ZnT3 and PSD95 protein levels in Lewy body dementias and Alzheimer's disease: association with cognitive impairment

The loss of zinc transporter 3 (ZnT3) has been implicated in age-related cognitive decline in mice, and the protein has been associated with plaques. We investigated the levels of ZnT3 and postsynaptic density protein 95 (PSD95), a marker of the postsynaptic terminal, in people with Parkinson's disease dementia (PDD, n = 31), dementia with Lewy bodies (DLB, n = 44), Alzheimer's disease (AD, n = 16), and controls (n = 24), using semiquantitative western blotting and immunohistochemistry in 3 cortical regions. Standardized cognitive assessments during life and semiquantitative scoring of amyloid β (Aβ), tau, and α-synuclein at postmortem were used to investigate the relationship between ZnT3 and PSD95, cognition and pathology. Associations were observed between ZnT3 and PSD95 levels in prefrontal cortex and cognitive impairment (p = 0.001 and p = 0.002, respectively) and between ZnT3 levels in the parietal cortex and cognitive impairment (p = 0.036). Associations were also seen between ZnT3 levels in cingulate cortex and severity of Aβ (p = 0.003) and tau (p = 0.011) pathologies. DLB and PDD were characterized by significant reductions of PSD95 (p < 0.05) and ZnT3 (p < 0.001) in prefrontal cortex compared with controls and AD. PSD95 levels in the parietal cortex were found to be decreased in AD cases compared with controls (p = 0.02) and PDD (p = 0.005). This study has identified Zn²⁺ modulation as a possible novel target for the treatment of cognitive impairment in DLB and PDD and the potential for synaptic proteins to be used as a biomarker for the differentiation of DLB and PDD from AD.