载脂蛋白E与阿尔茨海默病相关性研究进展

阿尔茨海默病(AD)是老年期痴呆的主要类型,目前发病机制不完全清楚,可能与基因和环境共同作用有关,载脂蛋白E(Apo E)基因是目前被公认的AD最常见的风险因子,Apo Eε4等位基因是目前散发性AD的最强遗传性危险因素。近年许多基因被证实与散发性AD具有相关性,研究Apo E在AD发病中的作用,对AD病理生理学机制的研究及AD的治疗具有重要意义。     

Effects of Apolipoprotein E Genotype on Cortical Neuropathology in Senile Dementia of the Lewy Body and Alzheimer's Disease

Apolipoprotein E (APO E) genotypes were determined in a UK population of neuropathologically confirmed control cases, and in cases of Lewy body dementia (SDLT) and late onset Alzheimer's disease (AD). APO E ϵ4 allele frequency was significantly elevated in both SDLT and AD groups with a concomitant reduction in the APO E ϵ3 allele frequency. The ϵ2 allele frequency in the AD group was only 25% of the control population, though because of the relatively small sample size this reduction was not significant; the ϵ2 allele frequency in the SDLT group was normal. No significant association was found between senile plaque density and neurofibrillary tangle density in the neocortex and APO E allele dose in either SDLT or AD. Although the possession of APO E ϵ4 is associated with an increased risk of developing SDLT and AD, actual APO E genotype does not appear to affect the burden of pathology.     

Apolipoprotein E Drives Early Blood–Brain Barrier Damage in Alzheimer’s Disease

Recently,the essential functions of the blood-brain barrier(BBB)have attracted increasing attention in the pathophysiology of Alzheimer's disease(AD)[1].How apolipoprotein E(APOE4),the most important high-risk gene for late-onset AD[2],drives early BBB damage in AD patients remains unclear.     

载脂蛋白E基因多态性与早发性阿尔茨海默病的相关性

目的：探讨载脂蛋白E（ApoE）基因多态性与早发性阿尔茨海默病（EOAD）的相关性。方法：用扩增抗拒突变系统法检测103例EOAD患者、159例迟发性阿尔茨海默病（LOAD）患者和118例认知功能正常对照（Nc）者的ApoE基因多态性,分析其与EOAD患病的相关性。结果：EOAD组ApoE等位基因和基因型分布频率与正常对照组差异有显著统计学意义,与LOAD组差异无统计学意义;Logisfc回归证实携带ApoEg4与EOAD有显著相关性;ε4等位基因拷贝数的增加,可显著提高EOAD的患病率,但不影响EOAD的发病年龄。结论：ApoEg4是EOAD的独立危险因素,可显著增加EOAD的患病率。     

Apolipoprotein E Genotype and Early Alzheimer''s Disease: A Longitudinal SPECT Study

BACKGROUND AND PURPOSE: To determine the association of the apolipoprotein E (APOE) genotype and longitudinal changes of regional cerebral blood flow (rCBF) in Alzheimer's disease (AD). Previous reports have yielded conflicting results concerning this association. METHODS: A retrospective cohort study was performed. rCBF was noninvasively measured using 99mTc-ethyl cysteinate dimer single-photon emission computed tomography in 23 patients with probable AD at the very early stage and at a mean interval of 24 months, as well as in 55 age-matched healthy volunteers. Patients were classified into 2 groups according to the presence of the epsilon 4 allele: 11 epsilon 4 carriers and 12 noncarriers. Correction for partial volume effects (PVEs) was performed in all patients using gray matter volume measured by magnetic resonance imaging. Statistical parametric mapping was used for the analysis of absolute rCBF data and the adjusted rCBF images of relative flow distribution. RESULTS: In the baseline study, both carriers and noncarriers showed significant decreases of absolute and adjusted rCBF in the psoterior cingulate gyri and precunei. After PVE correction, carriers showed a greater spread of areas with significant rCBF reduction from the parietotemporal to the frontal area than noncarriers during the follow-up period compared to healthy volunteers. Moreover, carriers showed a significant decline of absolute rCBF in the frontal cortex from the baseline to the follow-up study. CONCLUSIONS: The authors' study suggests that the APOE epsilon 4 allele is associated with the faster progression of AD, and PVE correction may be necessary for accurate assessments of SPECT studies of AD.     

Apolipoprotein Serum Amyloid A in Alzheimer's Disease

Alzheimer's disease is characterized by the tissue deposition of beta-amyloid peptide (Abeta) in the brain. Recent studies have shown apoproteins (apo) in amyloid plaques and associated with high-density lipoprotein (HDL) particles in the cerebrospinal fluid (CSF). Western blot analysis revealed that serum amyloid A (apoSAA) protein was present in control and AD patients at low levels compared to apoE and apoA-I, however, AD brains showed a significant increase over control values. Analysis of CSF-HDL from control and AD individuals showed that apoA-I, apoE and apoSAA were on the particle. Immuno-cytochemical analysis showed that SAA was detected in senile plaques in AD tissue, but was predominantly localized to neuritic plaques. ApoE staining of AD brain confirmed that most plaques contained the apoprotein, similar to Abeta immunoreactivity, whereas apoA-I expressed little staining of senile plaques. No significant differences were detected in the level of apoSAA when compared to APOE genotype in AD samples, suggesting that interactions with apoE were non-specific. These data imply that the specific interactions of SAA with Abeta in the neuritic plaques may play a role in AD.     

载脂蛋白E基因多态性与Alzheimer病

目的：探讨广东地区Ａｌｚｈｅｉｍｅｒ病（ＡＤ）患者与ａｐｏＥε４之间的关联性及性别的影响。方法：应用聚合酶链反应－限制性片段长度多态性分析（ＰＣＲ－ＲＦＬＰ）的技术对４４例晚发性散发性ＡＤ患者、３７例非痴呆老年人的ａｐｏＥ基因进行分型。结果：ａｐｏＥε４与晚发性ＡＤ有显著的关联;携带１个或１个以上ε４者与无ε４携带者比较,相对危险度（ＯＲ值）为４．０８,且随ε４基因剂量增加,ＡＤ的患病率上升,发病年龄明显提前（Ｐ＜０．０１）;ＡＤ患者不同性别之间ａｐｏＥε４基因型频率和等位基因频率无显著性差异（Ｐ＞０．０５）。结论ａｐｏＥε４是晚发性ＡＤ发病的危险因素;ＡＤ患者的性别因素与ａｐｏＥε４无相关性。     

Apolipoprotein E facilitates neuritic and cerebrovascular plaque formation in an Alzheimer's disease model

The epsilon4 allele of apolipoprotein E (ApoE) is an important genetic risk factor for Alzheimer's disease (AD). Increasing evidence suggests that this association may be linked to the ability of ApoE to interact with the amyloid-beta (Abeta) peptide and influence its concentration and structure. To determine the effect of ApoE on Abeta and other AD pathology in vivo, we used APPsw transgenic mice and ApoE knockout (-/-) mice to generate APPsw animals that carried two (ApoE +/+), one (ApoE +/-), or no copies (ApoE -/-) of the normal mouse ApoE gene. At 12 months of age, Abeta deposition was present in the cortex and hippocampus and was also prominent within leptomeningeal and cortical blood vessels of all APPsw ApoE +/+ mice. Importantly, although Abeta deposition still occurred in APPsw ApoE -/- mice, no fibrillar Abeta deposits were detected in the brain parenchyma or cerebrovasculature. There was also no neuritic degeneration associated with Abeta deposition in the absence of ApoE. These data demonstrate that ApoE facilitates the formation of both neuritic and cerebrovascular plaques, which are pathological hallmarks of AD and cerebral amyloid angiopathy.     

Apolipoprotein E in Alzheimer's disease and other neurological disorders

Apolipoprotein E (APOE) is a 299-aminoacid protein encoded by the APOE gene. Three common polymorphisms in the APOE gene, ?2, ?3, and ?4, result in a single aminoacid change in the APOE protein. APOE ?2, ?3, and ?4 alleles strongly alter, in a dose-dependent manner, the likelihood of developing Alzheimer's disease and cerebral amyloid angiopathy. In particular, APOE ?4 is associated with increased risk for Alzheimer's disease whereas APOE ?2 is associated with decreased risk. The effects of APOE genotype on risk of these diseases are likely to be mediated by differential effects of APOE on amyloid-β accumulation in the brain and its vasculature. Response to treatment for Alzheimer's disease might differ according to APOE genotype. Because convincing evidence ties the APOE genotype to risk of Alzheimer's disease and cerebral amyloid angiopathy, APOE has been studied in other neurological diseases. APOE ?4 is associated with poor outcome after traumatic brain injury and brain haemorrhage, although the mechanisms underlying these associations are unclear. The possibility that APOE has a role in these and other neurological diseases has been of great interest, but convincing associations have not yet emerged.     

Alzheimer's Disease Pathology in Non-Demented Elderly

The purpose of this study was to quantitate the extent of neuropathological lesions (neurofilbrillary tangles and senile plaques) characteristic of Alzheimer's disease in cognitively intact elderly control subjects. The subjects included twenty-six elderly individuals who were autopsied at a university-based Alzheimer's Disease Center. The mean age at autopsy was 78 years (range 51-99 years); there were 15 males and 11 females. All of these control subjects had a few neurons containing neurofibrillary tangles in the hippocampus, but no neurofibrillary tangles in the neocortex. Twelve of the 26 subjects (46%) had some senile plaques in the neocortex, while fourteen (54%) did not. Six subjects (23%) had substantial numbers of senile plaques in the neocortex. Neither the number of neurons containing neurofibrillary tangles nor the number of senile plaques correlated with age in these subjects. Possible conclusions are that there are many elderly individuals with incipient Alzheimer's Disease, or that one can have some degree of these lesions and still be cognitively normal. These data point out the need to have better pathological markers of the disease process and better diagnostic criteria to define Alzheimer's Disease.     

Apolipoprotein C-I Expression in the Brain in Alzheimer's Disease

The H2 allele of apolipoprotein (apo) C-I is associated with Alzheimer's disease (AD). However, this association is potentially confounded by the linkage disequilibrium of H2 with the epsilon2 and epsilon4 alleles of apoE and of H1 with the epsilon3 allele. To establish plausibility for a direct role for apoC-I in AD, we compared apoC-I and apoE protein and mRNA levels in postmortem specimens of frontal cortex and hippocampus from AD patients with levels in nondemented controls. In H2-allelic individuals (usually also epsilon4 carriers), apoC-I mRNA levels were strikingly lower with AD (by 65%, P < 0.05), but apoC-I protein levels in AD were significantly higher (by 34%, P < 0.05). The opposite direction of the apoC-I mRNA and apoC-I protein level changes in AD in the epsilon4/H2 genotype may reflect decreased clearance of CNS lipoproteins associated with apoE4. In H1/H1 (usually epsilon3/epsilon3) individuals, both apoC-I protein and mRNA were lower in AD. ApoC-I protein levels in hippocampus were nearly twice those in frontal cortex. Immunohistochemistry of hippocampus revealed colocalization of apoC-I protein with the astrocytic marker GFAP. In addition, cultured human astrocytes expressed the mRNA for apoC-I. This study confirms apoC-I expression in the CNS and identifies astrocytes as the source of apoC-I. In addition, it has revealed differences in apoC-I expression based on site, genotype, and disease status that may reflect a role for apoC-I in the pathogenesis of AD.     

Apolipoprotein E genotype and noncognitive symptoms in Alzheimer's disease.

BACKGROUND: The apolipoprotein E (ApoE) epsilon 4 allele confers significant risk for Alzheimer's disease and is associated with a greater amyloid burden in the brain. Future treatments may target molecular mechanisms associated with this allele, and it is important to define any phenotypic characteristics that correspond to this genotype. We sought to clarify the relationship between ApoE status and noncognitive symptoms in Alzheimer's disease patients. METHODS: Possible and probable Alzheimer's disease patients from a clinical trial (n = 605) were assessed with the 10-item Neuropsychiatric Inventory cross-sectionally prior to treatment, and their ApoE genotype was determined. Among the population studied, the following numbers with specific genotypes were studied: 23-2/3, 17-2/4, 209-3/3, 288-3/4, 68-4/4. RESULTS: When correlations were controlled for the patient's level of cognitive impairment, there was no relationship between epsilon 4 dose and any of the 10 noncognitive symptoms assessed, including psychosis, mood changes, and personality alterations. CONCLUSIONS: Among patients with comparable disease severity, the epsilon 4 allele does not confer additional psychiatric morbidity.     

Apolipoprotein E4 Genotype and Depressive Symptoms as Risk Factors for Dementia in an Older Korean Population

Objective

Growing evidence suggests the separate associations of apolipoprotein E e4 allele (apo E4) and depression with incident dementia. This study investigated the separate and combined effects of apo E4 and depression on the incidence of dementia in both men and women.

Methods

Of 625 elderly without dementia at baseline, 518 (83%) were followed over a 2.4-year period and were assessed clinically for incident dementia. The apo E polymorphism was ascertained, and depression was identified using the Korean version of the Geriatric Depression Scale (KGDS). Covariates included age, gender, education, disability, alcohol history, physical activity, and vascular risk factors.

Results

The incidence of dementia was significantly higher in elderly Koreans with both apo E4 and depression compared to those without both factors [adjusted odds ratio (95% CI)=5.85 (1.77-19.38)]. This interaction was significant in men (p=0.049), but not in women (p=0.354).

Conclusion

Depressed elderly people are at great risk for incident dementia in the presence of apo E4. Potential gender differences require further evaluation.     

Apolipoprotein E genotype and concomitant clinical features in early-onset Alzheimer's disease

We have studied the relationship between the apolipoprotein E gene (APOE) and the development of myoclonus, tremors, rigidity and seizures in 168 patients with probable early-onset Alzheimer's disease (AD). There was a statistically significantly lower risk of tremor for carriers of the 4 allele of APOE. This allele was also associated with an increased risk of myoclonus. Our findings suggest that there may be differences in progression and clinical appearance in early-onset AD related to the APOE genotype.     

Apolipoprotein E allele-dependent antioxidant activity in brains with Alzheimer's disease

Thiobarbituric acid-reactive substances (TBARS), an index of lipid peroxidation, were assayed in postmortem brain. Basal TBARS levels were increased and oxidative stimulation produced more TBARS in AD relative to control brains. In addition, apolipoprotein E isoforms showed differing antioxidant activities, with E2 > E3 > E4, suggesting that the lowest antioxidant activity of E4 could contribute to its association with AD.