Endovascular Treatment Versus Intravenous Thrombolysis for Acute Ischemic Stroke: a Quantitative Review and Meta-Analysis of 21 Randomized Trials

Emerging studies suggest that endovascular treatment (EVT) may be superior to intravenous thrombolysis for acute ischemic stroke (AIS). We performed a systematic review and meta-analysis of all randomized controlled trials (RCTs) to assess the efficacy and safety of endovascular treatment in patients with acute ischemic stroke as compared with intravenous thrombolysis. We assessed RCTs investigating EVT versus intravenous thrombolysis (IVT) published up to June 2015. In total, 21 studies of 4473 patients were included in the systematic review and meta-analysis. EVT significantly improved functional outcome at 90 days (risk ratio (RR) 1.35, 95 % confidence interval (CI) 1.18 to 1.55, I ² = 61 %) and reduced the mortality (RR 0.81, 95 % CI 0.68 to 0.95, I ² = 0 %), with similar symptomatic hemorrhagic transformation (SHT) rate (RR 1.12, 95 % CI 0.88 to 1.44, I ² = 0 %). Based on the current data, endovascular therapy may produce good clinical outcomes with similar symptomatic hemorrhage and mortality as compared with intravenous thrombolysis in acute ischemic stroke. This advancing intervention is a landmark change in stroke treatment and could be of huge potential benefit to patients worldwide.

PGRN Is Associated with Late-Onset Alzheimer's Disease: a Case-Control Replication Study and Meta-analysis

Progranulin (PGRN) plays an important role in Alzheimer's disease (AD) through participating in altering neurite outgrowth and neuronal survival. Previous studies identified that rs5848 in the 3'-untranslated region (3'-UTR) of the PGRN gene (GRN) is strongly associated with AD in Caucasians. In order to assess the involvement of the GRN polymorphism in the risk of late-onset AD (LOAD), we analyzed the genotype and allele distributions of rs5848 in 2350 Han Chinese subjects (AD, 992; control, 1358). The minor T allele of rs5848 was significantly associated with an increased risk of LOAD (P = 0.005, odds ratio (OR) = 1.197, 95 % confidence interval (CI) = 1.057-1.355). Moreover, the association was further validated in the multivariate logistic regression analysis (dominant model: OR = 1.195, P = 0.038, recessive model: OR = 1.386, P = 0.025; additive model: OR = 1.187, P = 0.009). Interestingly, we observed that the interaction between apolipoprotein E (APOE) and rs5848 significantly altered the risk for AD. The rs5848 polymorphism was only significantly associated with LOAD in APOE ε4 allele carriers. Then we included five studies (including the present study) and conducted a meta-analysis which consisted of 3236 cases (male, 1152; female, 2084) and 3405 (male, 1436; female, 1969) controls. The result of the meta-analysis supported T allele of rs5848 within GRN as a risk factor for AD. In conclusion, our results demonstrated that rs5848 polymorphism within GRN was associated with LOAD.

The prevalence of neuropsychiatric symptoms in Alzheimer's disease: Systematic review and meta-analysis

BACKGROUND

Neuropsychiatric symptoms (NPS) are being increasingly recognized as common serious problems in Alzheimer's disease (AD). However, published data on the prevalence of NPS in persons with AD are conflicting. This meta-analysis aimed to estimate the prevalence of NPS in persons with AD.

METHODS

Studies published from 1964 to September 30, 2014, were identified from PubMed and Embase database, reference lists and conference abstracts. We calculated prevalence rates and conducted meta-regression analysis with random-effects model, according to study characteristics, population demographics or condition information.

RESULTS

We identified 48 eligible articles, which provided data for 12 NPS reported in Neuropsychiatric Inventory (NPI). The most frequent NPS was apathy, with an overall prevalence of 49% (95% CI 41-57%), followed by depression, aggression, anxiety and sleep disorder, the pooled prevalence estimates of which were 42% (95% CI 37-46%), 40% (95% CI 33-46%), 39% (95% CI 32-46%) and 39% (95% CI 30-47%), respectively. The less prevalent NPS were irritability (36%, 31-41%), appetite disorder (34%, 27-41%), aberrant motor behavior (32%, 25-38%), delusion (31%, 27-35%), disinhibition (17%, 12-21%) and hallucination (16%, 13-18%). Least common was euphoria, with an overall prevalence of 7% (95% CI 5-9%).

LIMITATIONS

Several aspects, such as the quality of included studies were not always optimal and there was significant heterogeneity of prevalence estimate across studies.

CONCLUSIONS

NPS were observed to be highly prevalent in AD patients. Disease duration, age, education level, population origin and the severity of cognitive impairment had influence on the prevalence of some NPS.

GWAS-Linked Loci and Neuroimaging Measures in Alzheimer's Disease

Recently, 19 susceptibility loci for Alzheimer's disease (AD) had been identified through AD genome-wide association studies (GWAS) meta-analysis. However, how they influence the pathogenesis of AD still remains largely unknown. We studied those loci with six MRI measures, abnormal glucose metabolism, and β-amyloid (Aβ) deposition on neuroimaging in a large cohort from Alzheimer's Disease Neuroimaging Initiative (ADNI) database in order to provide clues of the mechanisms through which these genetic variants might be acting. As a result, single nucleotide polymorphisms (SNPs) at rs983392 within MS4A6A and rs11218343 within SOLR1 were both associated with the percentage of increase in the volume of left inferior temporal regions in the follow-up study. Meanwhile, rs11218343 at SORL1 and rs6733839 at BIN1 was associated with rate of volume change of left parahippocampal and right inferior parietal, respectively. Moreover, rs6656401 at CR1 and rs983392 at MS4A6A were both associated with smaller volume of right middle temporal at baseline. However, in addition to the APOE locus, we did not detect any influence on glucose metabolism and Aβ deposition. APOE ε4 allele was associated with almost all measures. Altogether, five loci (rs6656401 at CR1, rs983392within MS4A6A, rs11218343 at SORL1, rs6733839 at BIN1, and APOE ε4) have been detected to be associated with one or a few established AD-related neuroimaging measures.

Meta-analysis of modifiable risk factors for Alzheimer's disease

BACKGROUND

The aetiology of Alzheimer's disease (AD) is believed to involve environmental exposure and genetic susceptibility. The aim of our present systematic review and meta-analysis was to roundly evaluate the association between AD and its modifiable risk factors.

METHODS

We systematically searched PubMed and the Cochrane Database of Systematic Reviews from inception to July 2014, and the references of retrieved relevant articles. We included prospective cohort studies and retrospective case-control studies.

RESULTS

16,906 articles were identified of which 323 with 93 factors met the inclusion criteria for meta-analysis. Among factors with relatively strong evidence (pooled population >5000) in our meta-analysis, we found grade I evidence for 4 medical exposures (oestrogen, statin, antihypertensive medications and non-steroidal anti-inflammatory drugs therapy) as well as 4 dietary exposures (folate, vitamin E/C and coffee) as protective factors of AD. We found grade I evidence showing that one biochemical exposure (hyperhomocysteine) and one psychological condition (depression) significantly increase risk of developing AD. We also found grade I evidence indicative of complex roles of pre-existing disease (frailty, carotid atherosclerosis, hypertension, low diastolic blood pressure, type 2 diabetes mellitus (Asian population) increasing risk whereas history of arthritis, heart disease, metabolic syndrome and cancer decreasing risk) and lifestyle (low education, high body mass index (BMI) in mid-life and low BMI increasing the risk whereas cognitive activity, current smoking (Western population), light-to-moderate drinking, stress, high BMI in late-life decreasing the risk) in influencing AD risk. We identified no evidence suggestive of significant association with occupational exposures.

CONCLUSIONS

Effective interventions in diet, medications, biochemical exposures, psychological condition, pre-existing disease and lifestyle may decrease new incidence of AD.

Association of Single-Nucleotide Polymorphism in ANK1 with Late-Onset Alzheimer's Disease in Han Chinese

Recently, two CpG sites in ankyrin 1 (ANK1) gene were identified to be hypermethylated and associated with Alzheimer's disease (AD)-related neuropathology in two large independent studies. Genetic variations are indicated to be involved in DNA methylation, especially when the associated single-nucleotide polymorphisms (SNPs) are located adjacent to the CpG site. Accordingly, ANK1 polymorphisms might contribute to late-onset AD (LOAD) risk. One polymorphism rs515071 was identified to be a potential risk factor for type 2 diabetes (T2D). As shared genetic background was found underlying T2D and AD, we postulate that rs515071 polymorphism may be associated with late-onset AD (LOAD) risk and assessed the association in 982 LOAD patients and 1346 sex- and age-matched healthy controls. Our results showed that minor allele A of rs515071 significantly increased LOAD risk in the APOE ε4 (+) subgroup (genotype P = 0.015, allele P = 0.020). After adjusting for age and gender, the association remained significant under the dominant model (OR = 1.809, 95 % confidence interval (CI) = 1.186-2.757, P = 0.006). In conclusion, our findings demonstrate that rs515071 in ANK1 is a novel genetic risk for LOAD susceptibility in Han Chinese.

Frontotemporal Lobar Degeneration: Mechanisms and Therapeutic Strategies

Frontotemporal lobar degeneration (FTLD) is characterized by progressive deterioration of frontal and anterior temporal lobes of the brain and often exhibits frontotemporal dementia (FTD) on clinic, in <65-year-old patients at the time of diagnosis. Interdisciplinary approaches combining genetics, molecular and cell biology, and laboratory animal science have revealed some of its potential molecular mechanisms. Although there is still no effective treatment to delay, prevent, and reverse the progression of FTD, emergence of agents targeting molecular mechanisms has been beginning to promote potential pharmaceutical development. Our review summarizes the latest new findings of FTLD and challenges in FTLD therapy.

Effect of EPHA1 genetic variation on cerebrospinal fluid and neuroimaging biomarkers in healthy, mild cognitive impairment and Alzheimer's disease cohorts

Ephrin type-A receptor 1 (EPHA1) (11771145) was documented to be one of the most strongly associated locus with Alzheimer's disease (AD) in a recent meta-analysis of five genome wide association studies. However, its contribution to the pathogenesis of AD remains unclear to date. Here, we addressed the role of EPHA1 in AD by investigating the influence of EPHA1 on cerebrospinal fluid and neuroimaging biomarkers in three clinical stages from the Alzheimer's Disease Neuroimaging Initiative (ADNI) database. We did not detect significant association of EPHA1 with amyloid-β deposition or tau protein. However, the A-allele in the mild cognitive impairment group remarkably prevented hippocampal atrophy (partial correlation coefficient 2.812, 95% CI 0.651 to 4.973) at two-year follow-up. Additionally, AD subjects with the A-allele displayed less atrophy and greater cerebral metabolic rate for glucose (CMRgl) in the right lateral occipitotemporal gyrus (volume: partial correlation coefficient 540.10, 95% CI 247.26 to 832.95; CMRgl: partial correlation coefficient 0.056, 95% CI 0.024 to 0.087) and inferior temporal gyrus (volume: partial correlation coefficient 327.98, 95% CI 11.65 to 644.31; CMRgl: partial correlation coefficient 0.055, 95% CI 0.019 to 0.091) at baseline. This study suggests EPHA1 (rs11771145) interferes with the pathological alteration of the hippocampus and the lateral occipitotemporal and inferior temporal gyri throughout the AD process, leading to a lower risk of AD. However, the limited sample size and follow-up as well as the diversity across ethnicities precluded explanation of these findings.

Depression in Alzheimer's disease: epidemiology, mechanisms, and management

Depression occurs with a high prevalence of up to 50% in patients with Alzheimer's disease (AD) and increases the caregivers' burden. Depression symptoms can precede clinical diagnosis of AD for years or occurs around the onset of AD, although the etiology and pathologic mechanism of depression in AD pathogenesis remain unclear. Here, we provide an overview on recent studies, indicating that genetic factors, neuroanatomic changes, vascular risk factors, and the imbalance of neurotransmitters might contribute to depressive symptoms in AD. Tau pathology and amyloid-β accumulation also correlate with depression in AD. In addition, the alteration of hypothalamic-pituitary-adrenal axis, inflammatory pathway, and neurotrophin deficiency are the possible biological mechanisms linking depression and AD, and might become the potential targets for AD treatment. Current data support that antidepressants are promising to alleviate the symptom, though the efficacy is controversial. Moreover, antidementia medication and non-pharmacological interventions can be potential choices. In this review, we describe the prevalence and clinical course of depression in AD, analyze the underlying mechanisms, and discuss the possible management strategies for depression in patients with AD.

Role of pro-inflammatory cytokines released from microglia in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder of the brain, which is characterized by the formation of extracellular amyloid plaques (or senile plaques) and intracellular neurofibrillary tangles. However, increasing evidences demonstrated that neuroinflammatory changes, including chronic microgliosis are key pathological components of AD. Microglia, the resident immune cells of the brain, is constantly survey the microenvironment under physiological conditions. In AD, deposition of β-amyliod (Aβ) peptide initiates a spectrum of cerebral neuroinflammation mediated by activating microglia. Activated microglia may play a potentially detrimental role by eliciting the expression of pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) influencing the surrounding brain tissue. Emerging studies have demonstrated that up-regulation of pro-inflammatory cytokines play multiple roles in both neurodegeneration and neuroprotection. Understanding the pro-inflammatory cytokines signaling pathways involved in the regulation of AD is crucial to the development of strategies for therapy. This review will discuss the mechanisms and important role of pro-inflammatory cytokines in the pathogenesis of AD, and the ongoing drug targeting pro-inflammatory cytokine for therapeutic modulation.

The genetic variation of ARRB2 is associated with late-onset Alzheimer's disease in Han Chinese

Emerging evidence indicates that β-arrestin 2, an important regulator of G protein coupled receptors, is involved in the pathogenesis of Alzheimer's disease (AD). The aim of this study was to investigate the association between β-arrestin 2 gene (ARRB2) variation and the risk of late-onset AD (LOAD). A total of 1132 LOAD patients and 1158 healthy controls from the Han Chinese population were included in this study. Initially, four common single nucleotide polymorphisms (SNPs) (rs3786047, rs16954146, rs1045280 and rs2271167) were selected by consulting the Han Chinese from Beijing genotype data in HapMap database. Considering the fact that these four SNPs were located in one haplotype block and any two of them were in almost complete linkage disequilibrium (D'=1, r2≥0.897), we chose rs1045280 (a coding- synonymous variant) that covered all the common genetic variations in ARRB2 with r2≥0.8 as the tag SNP (tSNP) for the subsequent genotyping. Our results showed that the minor allele of rs1045280 was associated with an increased LOAD risk after adjusting for age, gender, educational level, and the apolipoprotein E (APOE) ε4 status under dominant (OR=1.291; 95% CI: 1.063-1.568; Bonferroni-corrected P=0.03) and additive (OR=1.269; 95% CI: 1.069-1.507; Bonferroni- corrected P=0.018) models. Meanwhile, when these data were stratified by APOE ε4 status, this association was evident only in APOE ε4 carriers (OR=1.617; 95% CI: 1.01-2.588; P=0.045). In summary, this study provide the first evidence that the tSNP of ARRB2 significantly increases LOAD risk in Han Chinese, suggesting ARRB2 may represent a susceptibility gene for LOAD.

Efficacy and adverse effects of ginkgo biloba for cognitive impairment and dementia: a systematic review and meta-analysis

BACKGROUND

Research into Ginkgo biloba has been ongoing for many years, while the benefit and adverse effects of Ginkgo biloba extract EGb761 for cognitive impairment and dementia has been discussed controversially.

OBJECTIVE

To discuss new evidence on the clinical and adverse effects of standardized Ginkgo biloba extract EGb761 for cognitive impairment and dementia.

METHODS

MEDLINE, EMBASE, Cochrane, and other relevant databases were searched in March 2014 for eligible randomized controlled trials of Ginkgo biloba EGb761 therapy in patients with cognitive impairment and dementia.

RESULTS

Nine trials met our inclusion criteria. Trials were of 22-26 weeks duration and included 2,561 patients in total. In the meta-analysis, the weighted mean differences in change scores for cognition were in favor of EGb761 compared to placebo (-2.86, 95%CI -3.18; -2.54); the standardized mean differences in change scores for activities in daily living (ADLs) were also in favor of EGb761 compared to placebo (-0.36, 95%CI -0.44; -0.28); Peto OR showed a statistically significant difference from placebo for Clinicians' Global Impression of Change (CGIC) scale (1.88, 95%CI 1.54; 2.29). All these benefits are mainly associated with EGb761 at a dose of 240 mg/day. For subgroup analysis in patients with neuropsychiatric symptoms, 240 mg/day EGb761 improved cognitive function, ADLs, CGIC, and also neuropsychiatric symptoms with statistical superiority than for the whole group. For the Alzheimer's disease subgroup, the main outcomes were almost the same as the whole group of patients with no statistical superiority. Finally, safety data revealed no important safety concerns with EGb761.

CONCLUSIONS

EGb761 at 240 mg/day is able to stabilize or slow decline in cognition, function, behavior, and global change at 22-26 weeks in cognitive impairment and dementia, especially for patients with neuropsychiatric symptoms.

Circulating microRNAs are promising novel biomarkers for drug-resistant epilepsy

MicroRNAs (miRNAs) open up a new field for molecular diagnosis for cancer and other diseases based on their stability in serum. However, the role of circulating miRNAs in plasma/serum in epilepsy diagnosis is still unclear. The aim of this study was to evaluate whether miRNAs can be used as biomarkers for drug-resistant epilepsy. We measured the differences in serum miRNA levels between 30 drug-resistant patients and 30 drug-responsive epilepsy patients in discovery and training phases using Illumina HiSeq2000 sequencing followed by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assays. The selected miRNAs were then validated in 77 drug-resistant epilepsy patients, 81 drug-responsive epilepsy patients and 85 healthy controls by qRT-PCR. We found that circulating miRNAs are differentially expressed between drug-resistant group and drug-responsive group. MiR-194-5p, -301a-3p, -30b-5p, -342-5p and -4446-3p were significantly deregulated in drug-resistant group compared to drug-responsive group and control group. Among these 5 miRNAs, miR-301a-3p had the best diagnostic value for drug-resistant epilepsy with 80.5% sensitivity and 81.2% specificity, and was negatively associated with seizure severity. These provide the rationale for further confirmation studies in larger prospective cohorts and in other ethnics.

Efficacy and safety of atypical antipsychotic drug treatment for dementia: a systematic review and meta-analysis

INTRODUCTION

A wide variety of atypical antipsychotic drugs (risperidone, olanzapine, quetiapine, aripiprazole, ziprasidone and clozapine) are widely used in the management of neuropsychiatric symptoms, which are commonly seen in dementia, but results from randomised controlled trials (RCTs) on the efficacy and safety of these agents are conflicting. We aimed to quantify the efficacy and safety of atypical antipsychotic drugs on neuropsychiatric symptoms in dementia patients.

METHODS

PubMed, EMBASE, the Cochrane Controlled Trials Register and the Cochrane Database of Systematic Reviews for reports published before August 2014 were searched for eligible randomized controlled trials of atypical antipsychotic drugs therapy in patients with psychotic symptoms of dementia. Two reviewers independently assessed the quality of the trials and extracted information.

RESULTS

Overall, 23 relevant RCTs with 5,819 participants were identified. This meta-analysis demonstrated a significant efficacy of atypical antipsychotics on psychiatric symptoms and cognitive functions compared to placebo. In the meta-analysis, the weighted mean differences (WMDs) in change scores for psychiatric symptoms were in favor of aripiprazole (-4.4, 95% confidence interval (CI) - 7.04 to -1.77) and risperidone (-1.48, 95% CI -2.35 to -0.61) compared to placebo. In cognitive effects, WMDs in change scores for the Clinical Global Impression-Change (CGI-C) were in favor of aripiprazole, risperidone, olanzapine and quetiapine which ranged from a -0.30 points mean difference (95% CI:-0.59 to -0.01) in the aripiprazole trials to -0.43 (95% CI:-0.62 to -0.25) in the risperidone group. Patients receiving atypical antipsychotics showed no difference in risk for injuries or falls (P > 0.05), significantly higher risks (P < 0.05) for somnolence, urinary tract infection, edema and abnormal gait. However, there was no significant evidence for death reported.

CONCLUSION

Aripiprazole and risperidone are able to improve psychiatric symptoms and slow decline in cognition function at average 12 weeks in patients with neuropsychiatric symptoms of dementia. However, high adverse events may offset the efficacy of atypical antipsychotics in dementia.

Genome-wide circulating microRNA expression profiling indicates biomarkers for epilepsy

MicroRNAs (miRNAs) have been proposed as biomarkers for cancer and other diseases due to their stability in serum. In epilepsy, miRNAs have almost been studied in brain tissues and in animals' circulation, but not in circulation of human. To date, a major challenge is to develop biomarkers to improve the current diagnosis of epilepsy. The aim of this study was to evaluate whether circulating miRNAs can be used as biomarkers for epilepsy. We measured the differences in serum miRNA levels between 30 epilepsy patients and 30 healthy controls in discovery and training phases using Illumina HiSeq2000 sequencing followed by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) assays. The selected miRNAs were then validated in 117 epilepsy patients and 112 healthy controls by qRT-PCR. Let-7d-5p, miR-106b-5p, -130a-3p and -146a-5p were found up-regulated, whereas miR-15a-5p and -194-5p were down-regulated in epilepsy patients compared to controls (P < 0.0001). Among these miRNAs, miR-106b-5p had the best diagnostic value for epilepsy with 80.3% sensitivity and 81.2% specificity. Circulating miRNAs were differentially regulated in epilepsy patients as compared with controls. MiR-106b-5p may serve as a novel, noninvasive biomarker to improve the current diagnosis of epilepsy.

Efficacy and safety of donepezil, galantamine, rivastigmine, and memantine for the treatment of Alzheimer's disease: a systematic review and meta-analysis

BACKGROUND

The role of currently available drugs for Alzheimer's disease (AD) has been controversial, with some national formularies restricting their use, and health economists questioning whether the small clinical effects are economically worthwhile.

OBJECTIVE

To estimate the efficacy and safety of donepezil, galantamine, rivastigmine, and memantine for the treatment of AD.

METHODS

Double-blind, placebo-controlled, with random assignment to a cholinesterase inhibitor or memantine trials were included into the pooled studies.

RESULTS

Cognitive effects were significant for all drugs, ranging from a -1.29 points mean difference (95% CI -2.30 to -0.28) in the 20 mg daily memantine trials to -3.20 points (95% CI -3.28 to -3.12) in the 32 mg daily galantamine group. Only memantine had no effect on the Clinicians' Global Impression of Change scale. No behavioral benefits were observed, except for -2.72 (95% CI -4.92 to -0.52) in the 10 mg daily donepezil group and -1.72 (95% CI -3.12 to -0.33) for 24 mg daily galantamine trial. Only 5 mg daily donepezil had no effect on the function outcome. Compared with placebo, more dropouts and adverse events occurred with the cholinesterase inhibitors, but not with memantine.

CONCLUSIONS

Cholinesterase inhibitors and memantine are able to stabilize or slow decline in cognition, function, behavior, and global change.

Efficacy and safety of cholinesterase inhibitors and memantine in cognitive impairment in Parkinson's disease, Parkinson's disease dementia, and dementia with Lewy bodies: systematic review with meta-analysis and trial sequential analysis

OBJECTIVE

Recently, several large randomised controlled trials about the treatments of cognitive impairment or dementia due to Parkinson's disease (CIND-PD or PDD) and dementia with Lewy bodies (DLB) were completed. Here, we systematically reviewed the studies (including the recent reports) to provide updated evidence for the treatments of CIND-PD, PDD and DLB.

METHODS

We searched Cochrane Dementia and Cognitive Improvement Group Specialised Register, Pubmed, Embase, and other sources for eligible trials. We selected global impression and cognitive function as primary efficacy outcomes, and dropouts and adverse events as safety outcomes. Furthermore, Meta-analysis and trial sequential analysis (TSA) were used here.

RESULTS

Ten trials were included in this study. Cholinesterase inhibitors and memantine produced small global efficacy on clinicians' global impression of change (CGIC), from a weighted mean difference of -0.40 (95% CI -0.77 to -0.03) to -0.65 (95% CI -1.28 to -0.01); however, cholinesterase inhibitors but not memantine significantly improved cognition on Mini-Mental State Examination (MMSE), from 1.04 (95% CI 0.43 to 1.65) to 2.57 (95% CI 0.90 to 4.23). Additionally, both of them had good safety outcomes, although rivastigmine showed an increased risk on adverse events than placebo (risk ratio, RR 1.19, TSA adjusted 95% CI 1.04 to 1.36), these events were usually mild or moderate, and the risk disappeared on serious adverse events.

CONCLUSIONS

Cholinesterase inhibitors and memantine slightly improve global impression; however, only cholinesterase inhibitors enhance cognitive function. Besides, all the drugs have good safety outcomes. But the limited trials precluded the generalisation of these outcomes.

NLRP1 inflammasome is activated in patients with medial temporal lobe epilepsy and contributes to neuronal pyroptosis in amygdala kindling-induced rat model

Background

Temporal lobe epilepsy (TLE) is often characterized pathologically by severe neuronal loss in the hippocampus. Understanding the mechanisms of neuron death is key to preventing the neurodegeneration associated with TLE. However, the involvement of neuronal loss to the epileptogenic process has yet to be fully determined. Recent studies have shown that the activation of NLRP1 can generate a functional caspase-1-containing inflammasome in vivo to drive the proinflammatory programmed cell death termed ‘pyroptosis’, which has a key role in the pathogenesis of neurological disorders. To the best of our knowledge, there are no reported studies that performed detailed identification and validation of NLRP1 inflammasome during the epileptogenic process.

Methods

We first compared expression of NLRP1 and caspase-1 in resected hippocampus from patients with intractable mesial temporal lobe epilepsy (mTLE) with that of matched control samples. To further examine whether the activation of NLRP1 inflammasome contributes to neuronal pyroptosis, we employed a nonviral strategy to knock down the expression of NLRP1 and caspase-1 in the amygdala kindling-induced rat model. Proinflammatory cytokines levels and hippocampal neuronal loss were evaluated after 6 weeks of treatment in these NLRP1 or caspase-1 deficiency TLE rats.

Results

Western blotting detected upregulated NLRP1 levels and active caspase-1 in mTLE patients in comparison to those levels seen in the controls, suggesting a role for this inflammasome in mTLE. Moreover, we employed direct in vivo infusion of nonviral small interfering RNA to knockdown NLRP1 or caspase-1 in the amygdala kindling-induced rat model, and discovered that these NLRP1 or caspase-1 silencing rats resulted in significantly reduced neuronal pyroptosis.

Conclusions

Our data suggest that NLRP1/caspase-1 signaling participates in the seizure-induced degenerative process in humans and in the animal model of TLE and points to the silencing of NLRP1 inflammasome as a promising strategy for TLE therapy.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0233-0) contains supplementary material, which is available to authorized users.

Acute metformin preconditioning confers neuroprotection against focal cerebral ischaemia by pre-activation of AMPK-dependent autophagy

BACKGROUND AND PURPOSE

Recent clinical trials report that metformin, an activator of AMP-activated protein kinase (AMPK) used to treat type 2 diabetes, significantly reduces the risk of stroke by actions that are independent of its glucose-lowering effects. However, the underlying molecular mechanisms are not known. Here, we tested the possibility that acute metformin preconditioning confers neuroprotection by pre-activation of AMPK-dependent autophagy in a rat model of permanent middle cerebral artery occlusion (pMCAO).

EXPERIMENTAL APPROACH

Male Sprague-Dawley rats were pretreated with either vehicle, an AMPK inhibitor, Compound C, or an autophagy inhibitor, 3-methyladenine, and were injected with a single dose of metformin (10 mg kg(-1), i.p.). Then, AMPK activity and autophagy biomarkers in the brain were assessed. At 24 h after metformin treatment, rats were subjected to pMCAO; infarct volume, neurological deficits and cell apoptosis were evaluated 24 and 96 h later.

KEY RESULTS

A single dose of metformin significantly activated AMPK and induced autophagy in the brain. The enhanced autophagic activity was inhibited by Compound C pretreatment. Furthermore, acute metformin preconditioning significantly reduced infarct volume, neurological deficits and cell apoptosis during a subsequent focal cerebral ischaemia. The neuroprotection mediated by metformin preconditioning was fully abolished by Compound C and partially inhibited by 3-methyladenine.

CONCLUSIONS AND IMPLICATIONS

These results provide the first evidence that acute metformin preconditioning induces autophagy by activation of brain AMPK, which confers neuroprotection against subsequent cerebral ischaemia. This suggests that metformin, a well-known hypoglycaemic drug, may have a practical clinical use for stroke prevention.

Genome-wide association studies in neurology

Genome-wide association studies (GWAS) are a powerful tool for understanding the genetic underpinnings of human disease. In this article, we briefly review the role and findings of GWAS in common neurological diseases, including Stroke, Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, migraine, amyotrophic lateral sclerosis, frontotemporal lobar degeneration, restless legs syndrome, intracranial aneurysm, human prion diseases and moyamoya disease. We then discuss the present and future implications of these findings with regards to disease prediction, uncovering basic biology, and the development of potential therapeutic agents.

Application of next-generation sequencing technologies in Neurology

Genetic risk factors that underlie many rare and common neurological diseases remain poorly understood because of the multi-factorial and heterogeneous nature of these disorders. Although genome-wide association studies (GWAS) have successfully uncovered numerous susceptibility genes for these diseases, odds ratios associated with risk alleles are generally low and account for only a small proportion of estimated heritability. These results implicated that there are rare (present in <5% of the population) but not causative variants exist in the pathogenesis of these diseases, which usually have large effect size and cannot be captured by GWAS. With the decreasing cost of next-generation sequencing (NGS) technologies, whole-genome sequencing (WGS) and whole-exome sequencing (WES) have enabled the rapid identification of rare variants with large effect size, which made huge progress in understanding the basis of many Mendelian neurological conditions as well as complex neurological diseases. In this article, recent NGS-based studies that aimed to investigate genetic causes for neurological diseases, including Alzheimer's disease, Parkinson's disease, epilepsy, multiple sclerosis, stroke, amyotrophic lateral sclerosis and spinocerebellar ataxias, have been reviewed. In addition, we also discuss the future directions of NGS applications in this article.

Common Variants in PLD3 and Correlation to Amyloid-Related Phenotypes in Alzheimer's Disease

The phospholipase D3 (PLD3) gene has shown association with Alzheimer's disease (AD). However, the role of PLD3 common variants in amyloid-β (Aβ) pathology remains unclear. We examined the association of thirteen common single nucleotide polymorphisms (SNPs) with cerebrospinal fluid (CSF) Aβ(1- 42) levels and florbetapir retention on florbetapir 18F amyloid positron emission tomography (AV45-PET) in a large population. We found that one SNP (rs11667768) was significantly associated with CSF Aβ(1- 42) levels in the normal cognition group. We did not observe an association of any SNP with florbetapir retention. Our study predicted the potential role of PLD3 variants in Aβ pathology.

Inhibition of the NLRP3 inflammasome provides neuroprotection in rats following amygdala kindling-induced status epilepticus

Background

NLRP3 inflammasome is proposed to regulate inflammation in several neurological diseases, but its role in epilepsy remains largely unknown. This study aimed to investigate the role of the NLRP3 inflammasome in neuroinflammation, spontaneous recurrent seizures (SRS) and hippocampal neuronal loss in rat brain following amygdala kindling-induced status epilepticus (SE).

Methods

We detected the protein levels of IL-1β and NLRP3 inflammasome components by Western blot in the hippocampus of shams and SE rats at different time points following SE. To further examine whether the activation of the NLRP3 inflammasome contributes to SE-associated neuronal damage, we employed a nonviral strategy to knock down NLRP3 and caspase-1 expression in brain before undergoing SE. Proinflammatory cytokine levels and hippocampal neuronal loss were evaluated at 12 hours and at 6 weeks following SE respectively in these NLRP3 and caspase-1 deficient rats. Meanwhile, SRS occurrence was evaluated through a 4-week video recording started 2 weeks after SE in these NLRP3 and caspase-1 deficient rats.

Results

IL-1β levels and NLRP3 inflammasome components levels dramatically increased at 3 hours after SE, and reached a maximum at 12 hours after SE compared with the control group. Knock down of NLRP3 or caspase-1 decreased the levels of IL-1β and IL-18 at 12 hours after SE, which was accompanied by a significant suppression in the development and severity of SRS during the chronic epileptic phase. Meanwhile, knock down of NLRP3 or caspase-1 led to a remarkable reduction of hippocampal neuronal loss in the CA1 and CA3 area of the hippocampus at 6 weeks after SE.

Conclusions

Our study provides the first evidence that the NLRP3 inflammasome was significantly up-regulated following SE. More importantly, we show that inhibition of the NLRP3 inflammasome provides neuroprotection in rats following SE. These findings suggest that NLRP3 may represent a potential target for the treatment of epileptogenesis

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-014-0212-5) contains supplementary material, which is available to authorized users.

Resveratrol as a therapeutic agent for Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia, but there is no effective therapy till now. The pathogenic mechanisms of AD are considerably complex, including Aβ accumulation, tau protein phosphorylation, oxidative stress, and inflammation. Exactly, resveratrol, a polyphenol in red wine and many plants, is indicated to show the neuroprotective effect on mechanisms mostly above. Recent years, there are numerous researches about resveratrol acting on AD in many models, both in vitro and in vivo. However, the effects of resveratrol are limited by its pool bioavailability; therefore researchers have been trying a variety of methods to improve the efficiency. This review summarizes the recent studies in cell cultures and animal models, mainly discusses the molecular mechanisms of the neuroprotective effects of resveratrol, and thus investigates the therapeutic potential in AD.

IL12/23 p40 inhibition ameliorates Alzheimer's disease-associated neuropathology and spatial memory in SAMP8 mice

Progressively increased proinflammatory status is a major characteristic of the aging process and associated with age-related diseases such as Alzheimer's diseases (AD). However, the regulation and role of common proinflammatory cytokines, including interleukin-12 (IL-12) and IL-23, in the aged brain are still unclear. Using the senescence-accelerated mouse prone-8 (SAMP8) model, we screened the cerebral expression of IL-12/23 in 3-, 7-, and 11-month-old mice and observed that their levels in the brain were upregulated during aging. To further examine whether the heightened activation of inflammatory cytokines may contribute to age-related brain dysfunction, we employed direct in vivo infusion of nonviral small interfering RNA (siRNA) to knock down the common IL-12/23 signaling subunit p40 in the brain. We found that these p40-deficient mice had significantly decreased cerebral amyloid-β levels, reduced synaptic and neuronal loss, and reversed cognitive impairments. Furthermore, in vivo delivery of a neutralizing p40-specific antibody likewise ameliorated AD-associated pathology and cognitive deficits in SAMP8 mice. Thus, our data indicate that the upregulated cerebral IL-12/23 during aging is involved in age-associated brain dysfunction and point to the modulation of IL-12/23 signaling molecule p40 as a promising strategy for the development of an AD therapy.

Increased expression of TREM2 in peripheral blood of Alzheimer's disease patients

TREM2 has been reported to be associated with Alzheimer's disease (AD). Here, we evaluated TREM2 mRNA and protein expressions in peripheral blood from AD patients and healthy controls. Higher levels of TREM2 mRNA (p = 0.002) and protein (p < 0.001) were identified in AD patients. We observed a significant correlation between TREM2 expressions and MMSE score (mRNA: r = -0.482, protein: r = -0.582; p < 0.01). According to ROC curve analysis, the diagnostic accuracy for TREM2 protein levels on monocytes was 70%, with the sensitivity and specificity 68% and 72%, respectively. Our results indicate that TREM2 might serve as a novel noninvasive biomarker for AD diagnosis.

Behavioral and psychological symptoms in Alzheimer's disease

Neuropsychiatric symptoms (NPS) such as depression, apathy, aggression, and psychosis are now recognized as core features of Alzheimer's disease (AD), and there is a general consensus that greater symptom severity is predictive of faster cognitive decline, loss of independence, and even shorter survival. Whether these symptoms result from the same pathogenic processes responsible for cognitive decline or have unique etiologies independent of AD-associated neurodegeneration is unclear. Many structural and metabolic features of the AD brain are associated with individual neuropsychiatric symptoms or symptom clusters. In addition, many genes have been identified and confirmed that are associated with symptom risk in a few cases. However, there are no single genes strongly predictive of individual neuropsychiatric syndromes, while functional and structural brain changes unique to specific symptoms may reflect variability in progression of the same pathological processes. Unfortunately, treatment success for these psychiatric symptoms may be lower when comorbid with AD, underscoring the importance of future research on their pathobiology and treatment. This review summarizes some of the most salient aspects of NPS pathogenesis.

Association of IL-12A and IL-12B polymorphisms with Alzheimer's disease susceptibility in a Han Chinese population

As a pro-inflammatory cytokine belonging to the interleukin (IL)-1 family, IL-12 is recently found to be involved in the pathogenesis of Alzheimer's disease (AD). Here, we investigated the relations of three potentially functional single nucleotide polymorphisms (SNPs) in IL-12A (rs2243115 and rs568408) and IL-12B (rs3212227) with late-onset AD (LOAD) risk in a Northern Han Chinese cohort containing 1133 patients and 1158 healthy controls. Our findings indicated that these SNPs in IL-12A and IL-12B can individually and jointly contribute to LOAD risk in Han Chinese, implying that the genes encoding IL-12 subunits represent novel genetic risk factors for LOAD susceptibility.

Angiotensin-(1-7) induces cerebral ischaemic tolerance by promoting brain angiogenesis in a Mas/eNOS-dependent pathway

BACKGROUND AND PURPOSE

As a newer component of the renin-angiotensin system, angiotensin-(1-7) [Ang-(1-7) ] has been shown to facilitate angiogenesis and protect against ischaemic damage in peripheral tissues. However, the role of Ang-(1-7) in brain angiogenesis remains unclear. The aim of this study was to investigate whether Ang-(1-7) could promote angiogenesis in brain, thus inducing tolerance against focal cerebral ischaemia.

EXPERIMENTAL APPROACH

Male Sprague-Dawley rats were i.c.v. infused with Ang-(1-7), A-779 (a Mas receptor antagonist), L-NIO, a specific endothelial NOS (eNOS) inhibitor, endostatin (an anti-angiogenic compound) or vehicle, alone or simultaneously, for 1-4 weeks. Capillary density, endothelial cell proliferation and key components of eNOS pathway in the brain were evaluated. Afterwards, rats were subjected to permanent middle cerebral artery occlusion (pMCAO), and regional cerebral blood flow (rCBF), infarct volume and neurological deficits were measured 24 h later.

KEY RESULTS

Infusion of Ang-(1-7) for 4 weeks significantly increased brain capillary density via promoting endothelial cell proliferation, which was accompanied by eNOS activation and up-regulation of NO and VEGF in brain. These effects were abolished by A-779 or L-NIO. More importantly, Ang-(1-7) improved rCBF and decreased infarct volume and neurological deficits after pMCAO, which could be reversed by A-779, L-NIO or endostatin.

CONCLUSIONS AND IMPLICATIONS

This is the first evidence that Ang-(1-7) promotes brain angiogenesis via a Mas/eNOS-dependent pathway, which enhances tolerance against subsequent cerebral ischaemia. These findings highlight brain Ang-(1-7)/Mas signalling as a potential target in stroke prevention.

ABCA7 in Alzheimer's Disease

ATP-binding cassette A7 (ABCA7) gene has recently been identified as a strong genetic locus associated with late-onset Alzheimer's disease (LOAD) through genome-wide association studies (GWASs). ABCA7 is a member of the ATP-binding cassette (ABC) transporter gene superfamily, which codes for 49 ABC proteins, divided into 7 subfamilies (coded A-G). As a multispan transmembrane protein, ABCA7 is most abundantly expressed in the microglial cells in the brain. The levels of ABCA7 have been detected to be increased in the Alzheimer's disease (AD) brain, which positively correlated with amyloid plaque burden and disease severity. Emerging data suggests that ABCA7 could be associated with AD via various pathways, possibly including amyloid-β (Aβ) accumulation, lipid metabolism, and phagocytosis. In this review, we summarize the known functions of ABCA7 and discuss the single-nucleotide polymorphisms (SNPs) related to LOAD, as well as their potential physiological effects. Finally, given the contributions of ABCA7 to AD pathogenesis, targeting ABCA7 might provide novel opportunities for AD therapy.

Ischemic preconditioning provides neuroprotection by induction of AMP-activated protein kinase-dependent autophagy in a rat model of ischemic stroke

Accumulating evidence suggests that ischemic preconditioning (IPC) increases cerebral tolerance to the subsequent ischemic exposure. However, the underlying mechanisms are still not fully understood. In the present study, we tested the hypothesis that AMP-activated protein kinase (AMPK)-dependent autophagy contributed to the neuroprotection of IPC in rats with permanent cerebral ischemia. Male Sprague-Dawley rats were pretreated with vehicle, compound C (an AMPK inhibitor), or 3-methyladenine (3-MA, an autophagy inhibitor) and then were subjected to IPC induced by a 10-min middle cerebral artery occlusion. Afterward, the brain AMPK activity and autophagy biomarkers were measured. At 24 h after IPC, permanent cerebral ischemia was induced in these rats, and infarct volume, neurological deficits as well as cell apoptosis were evaluated 24 h later. We demonstrated that IPC activated AMPK and induced autophagy in the brain, which was accompanied by a reduction of infract volume, neurological deficits, and cell apoptosis after cerebral ischemia. Meanwhile, the IPC-induced autophagy was inhibited by compound C while the neuroprotection of IPC was abolished by compound C or 3-MA. These findings suggest that AMPK-mediated autophagy contributes to the neuroprotection of IPC, highlighting AMPK as a therapeutic target for stroke prevention and treatment.

Temsirolimus promotes autophagic clearance of amyloid-β and provides protective effects in cellular and animal models of Alzheimer's disease

Accumulation of amyloid-β peptides (Aβ) within brain is a major pathogenic hallmark of Alzheimer's disease (AD). Emerging evidence suggests that autophagy, an important intracellular catabolic process, is involved in Aβ clearance. Here, we investigated whether temsirolimus, a newly developed compound approved by Food and Drug Administration and European Medicines Agency for renal cell carcinoma treatment, would promote autophagic clearance of Aβ and thus provide protective effects in cellular and animal models of AD. HEK293 cells expressing the Swedish mutant of APP695 (HEK293-APP695) were treated with vehicle or 100nM temsirolimus for 24h in the presence or absence of 3-methyladenine (5mM) or Atg5-siRNA, and intracellular Aβ levels as well as autophagy biomarkers were measured. Meanwhile, APP/PS1 mice received intraperitoneal injection of temsirolimus (20mg/kg) every 2 days for 60 days, and brain Aβ burden, autophagy biomarkers, cellular apoptosis in hippocampus, and spatial cognitive functions were assessed. Our results showed that temsirolimus enhanced Aβ clearance in HEK293-APP695 cells and in brain of APP/PS1 mice in an autophagy-dependent manner. Meanwhile, temsirolimus attenuated cellular apoptosis in hippocampus of APP/PS1 mice, which was accompanied by an improvement in spatial learning and memory abilities. In conclusion, our study provides the first evidence that temsirolimus promotes autophagic Aβ clearance and exerts protective effects in cellular and animal models of AD, suggesting that temsirolimus administration may represent a new therapeutic strategy for AD treatment. Meanwhile, these findings emphasize the notion that many therapeutic agents possess pleiotropic actions aside from their main applications.

Association of LRRTM3 polymorphisms with late-onset Alzheimer's disease in Han Chinese

The leucine-rich repeat transmembrane 3 (LRRTM3) has been defined as a positional and functional candidate gene for Alzheimer's disease. Recently, four novel variants (rs16923760, rs1925608, rs1925609 and rs10997477) within LRRTM3 were reported to be associated with late-onset Alzheimer's disease (LOAD) in Caucasians. To evaluate the association of the LRRTM3 polymorphisms with LOAD in Asians, we performed a case-control study of 2287 unrelated subjects (1129 cases and 1158 age- and gender-matched controls) in Han Chinese. The rs10997477 T allele was significantly associated with a decreased risk of LOAD in APOE ε4 allele noncarriers (OR=0.750, PC<0.001). Besides, the rs16923760 C allele significantly increased the risk of LOAD in APOE ε4 allele carriers (OR=1.837, PC<0.001). The genotype distribution of rs1925609 polymorphism also significantly differed in APOE ε4 allele noncarriers (PC=0.008). Moreover, the association was further demonstrated in multivariate logistic regression analysis (rs10997477: Recessive model: OR=0.156, PC=0.004; Additive model: OR=0.731, PC<0.001; rs16923760: Dominant model: OR=1.944, PC=0.024; Additive model: OR=1.885, PC<0.001; Recessive model: OR=3.565, PC=0.010; rs1925609: Recessive model: OR=0.421, PC=0.024). As for rs1925608, we failed to detect any association with LOAD. This study firstly provides the independent evidence that the LRRTM3 polymorphisms may play a role in the pathogenesis of LOAD in a Northern Han Chinese population. However, additional independent replication groups are required to further validate this association.

Decreased expression of CD33 in peripheral mononuclear cells of Alzheimer's disease patients

Recently, two independent genome-wide association studies (GWAS) have identified CD33 gene, encoding cluster of differentiation 33 (CD33), as a genetic locus associated with Alzheimer's disease (AD). It has been suggested that CD33 may contribute to AD pathogenesis by involving in inflammatory response, synaptic dysfunction and cell membrane processes. We analyzed the expressions of CD33 in peripheral blood mononuclear cells (PBMCs) in AD group and control group by real-time quantitative polymerase chain reaction and flow cytometry. Expression of CD33 mRNA was down-regulated in AD patients comparing to controls (p=0.001). The frequency of CD33 positive monocytes was also lower in AD patients than in controls (44.02 ± 22.17% versus 54.06 ± 21.86%, p=0.001). Moreover, we observed a correlation between CD33 positive monocytes levels and Mini Mental State Examination (MMSE) score (r=0.220, p<0.05). According to receiver operating characteristic (ROC) curve analysis, the diagnostic accuracy for CD33 alone is relatively lower, while, combining with additional parameters might further improve the diagnostic value for AD.

NLRP3 polymorphisms are associated with late-onset Alzheimer's disease in Han Chinese

The innate immunity and inflammatory response plays an important role in AD pathogenesis. Recently, a wealth of information linking the activation of NLRP3 inflammasome to Alzheimer's disease (AD) pathogenesis has emerged. Considering the pivotal role of NLRP3 in the inflammatory process and in AD, we hypothesized that variations in NLRP3 gene may also affect susceptibility to AD. Three selected functional single-nucleotide polymorphisms (SNPs) in NLRP3 gene (rs2027432, rs10754558, rs35829419) were genotyped in 1133 late-onset AD (LOAD) patients and 1159 healthy controls in a large Northern Han Chinese population. Among them, the 5'-flanking rs2027432 polymorphism seemed to be most associated with LOAD risk even after adjusting for age, gender, and ApoE ε4 status. For rs10754558, the genotype frequency differed significantly only in ApoE ε4 carriers. On the other hand, the minor A allele of rs35829419 (Q705K) polymorphism appeared to exert a protective effect against the development of LOAD. Our data support the notion that genetic variation in NLRP3 gene may contribute to LOAD risk in Northern Han Chinese.

Circulating miR-125b as a biomarker of Alzheimer's disease

BACKGROUND

MicroRNAs (miRNAs) are endogenous small RNAs of 21-25 nucleotides that post-transcriptionally regulate gene expressions. Recently, circulating miRNAs have been reported as promising biomarkers for neurodegenerative disorders and processes affecting the central nervous system. This study was conducted to investigate the potential role of serum miRNAs as diagnostic biomarkers for Alzheimer's disease (AD).

METHODS

Serum samples were obtained from 105 probable AD patients and 150 age- and gender-matched normal controls. The serum concentrations of miRNAs miR-9, miR-29a, miR-29b, miR-101, miR-125b, and miR-181c were measured with a real-time quantitative reverse transcriptase PCR (qRT-PCR) method.

RESULTS

We found both miR-125b and miR-181c were down-regulated while miR-9 was up-regulated in serum of AD patients compared with that of normal controls. Among the receiver operating characteristic (ROC) results, miR-125b alone showed its priority with a specificity up to 68.3% and a sensitivity of 80.8%. Importantly, miR-125b was correlated with the Mini Mental State Examination (MMSE) in AD patients.

CONCLUSIONS

Our results indicate that serum miR-125b may serve as a useful noninvasive biomarker for AD.

Genetic variation in PICALM and Alzheimer's disease risk in Han Chinese

The current study was conducted to investigate the association of phosphatidylinositol-binding clathrin assembly protein gene (PICALM) with late-onset Alzheimer's disease (LOAD) risk in Han Chinese. We first sequenced PICALM for variants in a small sample (n = 100), and the selected variants were then genotyped in a larger cohort (n = 2292). Sequencing analysis identified 16 variants within PICALM including 5 new variants with extreme low frequency in the northern Han Chinese population. However, in the subsequent genotyping, none showed a significant association with LOAD risk after Bonferroni correction. These findings implicate that PICALM might not play a major role in the genetic predisposition to LOAD in Han Chinese.

Epigenetic mechanisms in Alzheimer's disease: implications for pathogenesis and therapy

The vast majority of Alzheimer's disease (AD) are late-onset forms (LOAD) likely due to the interplay of environmental influences and individual genetic susceptibility. Epigenetic mechanisms, including DNA methylation, histone modifications and non-coding RNAs, constitute dynamic intracellular processes for translating environmental stimuli into modifications in gene expression. Over the past decade it has become increasingly clear that epigenetic mechanisms play a pivotal role in aging the pathogenesis of AD. Here, we provide a review of the major mechanisms for epigenetic modification and how they are reportedly altered in aging and AD. Moreover, we also consider how aberrant epigenetic modifications may lead to AD pathogenesis, and we review the therapeutic potential of epigenetic treatments for AD.

Toll-like receptor 9 promoter polymorphism is associated with decreased risk of Alzheimer's disease in Han Chinese

Background

Toll-like receptors (TLRs), as major innate immune mediators, may be involved in clearance of cerebral amyloid-β (Aβ) deposits. Recently, a novel TLR9 signaling pathway has been uncovered, which is functionally associated with the immune inflammatory response and reducing Aβ burden in Alzheimer’s disease (AD) mice. Therefore, TLR9 might represent a reasonable functional candidate gene for AD.

Findings

Our study investigated 1,133 sporadic late-onset AD (LOAD) and 1,159 healthy controls matched for sex and age in a large Han Chinese population. One selected functional rs187084 polymorphism within the TLR9 gene was genotyped by polymerase chain reaction-ligase detection reaction in a case–control associated study. The TLR9 rs187084 variant homozygote GG was significantly associated with a decreased LOAD risk after adjusting for age, gender, and ApoE ϵ4 status by logistic regression analysis (P = 0.035). Our result showed significant evidence of the interaction of ApoE ϵ4 with rs187084. When we further stratified our data by the ApoE ϵ4 status, we detected significant differences in the genotype and allele distributions of rs187084 between LOAD patients and controls in ApoE ϵ4 carriers (P < 0.001, P = 0.003, respectively). Moreover, we examined TLR9 expression in peripheral blood monocytes by flow cytometry, and the GG genotype of the TLR9 rs187084 polymorphism was associated with a higher TLR9 expression than two other genotypes in LOAD patients.

Conclusion

Our findings support the hypothesis that the TLR9 polymorphism may modify LOAD risk in the Han Chinese population.