Glucose metabolism and gray-matter concentration in apolipoprotein E ε4 positive normal subjects

Apolipoprotein E (ApoE) ε4 is known as a genetic risk factor for Alzheimer's disease (AD). This study investigated the prevalence of imaging abnormalities suggestive of AD in cognitively normal ApoE ε4 carriers using (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) and voxel-based morphometry (VBM). Forty-five cognitive normal ApoE ε4 allele carriers and 45 noncarriers underwent both FDG positron emission tomography and magnetic resonance imaging (MRI). A total of 90 normal database sets were generated for the individual 45 ε4 carriers and 45 noncarriers. Mean z-scores in the predefined AD-specific regions of interest (ROI) were calculated for each ε4 carrier and noncarrier using the individually defined normal database. The prevalence of AD-like hypometabolism and atrophy in the ε4 carriers was 8.9% and 17.7%, respectively, and did not differ significantly from those in the noncarriers (8.9%, 8.8%). The majority of ε4 carriers showed preserved FDG uptake or gray matter concentration.     

Abnormal event-related potentials in young and middle-aged adults with the ApoE ε4 allele

The largest genetic susceptibility factor for Alzheimer's disease is the Apolipoprotein E (ApoE) ε4 allele. Cognitive decline and olfactory impairment are greater in those positive for the ε4 allele. This study sought to determine if the olfactory event-related potential (OERP), compared to the visual ERP, would be sensitive to these subtle declines. Participants included 40 individuals from two age groups, half of each group were ε4 allele positive and half were ε4 negative. Visual ERPs did not demonstrate significant differences between ApoE groups. OERPs demonstrated robust age by ApoE interactions. P3 latencies were significantly longer in ε4 young and middle age participants. These findings suggest that very early olfactory and cognitive changes related to ApoE status are detectible via the OERP.     

Alzheimer's disease patients not carrying the apolipoprotein E ε4 allele show more severe slowing of oscillatory brain activity

The objective of this study was to quantitatively assess the relationship between apolipoprotein (APOE) genotype and electroencephalographic oscillatory brain dynamics in Alzheimer's disease (AD) patients and control subjects and its regional distribution. We obtained resting-state electroencephalographs of 320 AD patients and 246 control subjects, categorized into APOE ε4 carriers and noncarriers. Peak frequency and relative power in 4 different frequency bands were calculated. We tested the associations between APOE genotype and relative power in 4 brain regions. Peak frequency was comparable in APOE ε4 carrying and noncarrying control subjects, but lower in APOE ε4 noncarrying AD patients. In control subjects, APOE ε4 carriers had a different regional distribution of alpha power than noncarriers. We found no APOE effect in beta, delta, and theta bands. In AD, APOE ε4 noncarriers had lower alpha and higher delta power than carriers. This difference was most pronounced in the parieto-occipital region. In the theta band, APOE ε4 noncarriers had a different regional distribution of power compared with carriers. In conclusion, the most pronounced effect of genotype was seen in AD patients, and APOE ε4 noncarriers showed slower activity, especially in parieto-occipital regions.     

Similar promotion of Aβ1-42 fibrillogenesis by native apolipoprotein E ε3 and ε4 isoforms

The apolipoprotein E ε4 allele contributes to the genetic susceptibility underlying a large proportion (~40–60%) of typical, sporadic Alzheimer disease. Apolipoprotein E deficient mice made transgenic for human apolipoprotein E ε4 accumulate excess cerebral amyloid when compared to similarly prepared mice expressing human apolipoprotein E ε3. Therefore, it is important to search for relevant interactions(s) between apolipoprotein E ε4 and Aβ in order to clarify the biological role for apolipoprotein E ε4 in Alzheimer disease. Using a thioflavine T (ThT)-based assay, we have investigated the effects of native human apolipoprotein E isoforms on the kinetics of Aβ fibrillogenesis. No obvious profibrillogenic activity was detected in Aβ_1-40-based assays of any native apolipoprotein E isoform. However, when ThT assays were repeated using Aβ_1-42, modest, but statistically significant, profibrillogenic activity was detected in both apolipoprotein E ε3- and apolipoprotein E ε4-containing media and was similar in magnitude for the two isoforms. These data demonstrate that native apolipoprotein E possesses "pathological chaperone"-type activity for Aβ: in other words, the data indicate that a chaperone-like misfolding reaction can occur between native apolipoprotein E and Aβ. However, the equipotent activities of the apolipoprotein E ε3 and ε4 isoforms suggests the possibility that either extended co-incubation of apolipoprotein E and Aβ, or, perhaps, the inclusion in the reaction of other fibrillogenesis-modulation co-factors (such as metal ions, or inflammatory mediators such as reactive oxygen species, α₂-macroglobulin, apolipoprotein J, etc.) may be required for modeling in vitro the apolipoprotein E-isoform-specific-regulation of extracellular Aβ accumulation that occurs in vivo. Alternatively, other events, such as differential apolipoprotein E-isoform-mediated clearance of Aβ or of apolipoprotein E/Aβ complexes may underlie apolipoprotein E-isoform-dependent Aβ accumulation.     

GFAP reactivity,apolipoprotein E redistribution and cholesterol reduction in human astrocytes treated with α-synuclein

α-Synuclein (α-syn) is an abundant neuronal protein expressed at the synapse. In neurodegenerative disease α-syn accumulates in the extracellular space. Astrocytes present at neural synapses are thought to contribute to synaptogenesis through cholesterol release and normally exhibit increased glial fibrillary acid protein (GFAP) reactivity and apolipoprotein E (apoE) expression in neurodegenerative disease states. We proposed that extracellular α-syn treatment of human astrocytes would impact cholesterol levels and expression of GFAP and apolipoprotein E (apoE). Human astrocytes were treated with α-syn at different concentrations and time points to determine the effective membrane permeability of the peptide. After α-syn treatment, we analyzed apoE and cholesterol levels in the astrocyte membrane. Lastly, we performed immunocytochemistry for GFAP in control and α-syn treated cells. Our results indicate membrane apoE was reduced and redistributed from a nuclear and membranous dominated expression to the cytosol. Cholesterol levels were also reduced in the astrocyte cell membrane. GFAP expression was sharply increased in α-syn treated cells indicating that α-syn may contribute to reactive gliosis. Our results support the conclusion that astrocytes play a role in pathological mechanisms in synucleinopathies.     

The expression and preliminary evaluation of HPV6bL2△N360E7E6 fusion protein in E.coli for genital warts

Objective To express HPV6bL2△N360E7E6 fusion protein in E.coli and preliminarily evaluate its immune effect.Methods Three HPV6b gene fragments,which were L2(1-360 bp),E7 and E6,were fused by overlapping PCR,then were inserted into a prokaryotic expression vector and expressed in E.coli.C57BL/6 mice were immunized with purified fusion protein plus Al(OH)3 and/or CpG adjuvants through intramuscular route,the cellular and humoral immune responses were detected by IFN-γ ELISPOT and ELISA respectively.Results Protein plus CpG adjuvant could induce the strongest cellular immune response to E7 and E6,high antibody titer against L2 could be detected in all immunized groups but there were no significant difference among these groups.Conclutions HPV6bL2△N360E7E6 gene was successfully cloned into pQE30 vector and expressed in E.coli,the fusion protein was also purified and proved that could induce strong cellular and humoral immune responses with appropriate adjuvant in C57 BL/ 6 mice and could be used for future research.     

The expression and preliminary evaluation of HPV6bL2△N360E7E6 fusion protein in E.coli for genital warts

Objective To express HPV6bL2△N360E7E6 fusion protein in E.coli and preliminarily evaluate its immune effect.Methods Three HPV6b gene fragments,which were L2(1-360 bp),E7 and E6,were fused by overlapping PCR,then were inserted into a prokaryotic expression vector and expressed in E.coli.C57BL/6 mice were immunized with purified fusion protein plus Al(OH)3 and/or CpG adjuvants through intramuscular route,the cellular and humoral immune responses were detected by IFN-γ ELISPOT and ELISA respectively.Results Protein plus CpG adjuvant could induce the strongest cellular immune response to E7 and E6,high antibody titer against L2 could be detected in all immunized groups but there were no significant difference among these groups.Conclutions HPV6bL2△N360E7E6 gene was successfully cloned into pQE30 vector and expressed in E.coli,the fusion protein was also purified and proved that could induce strong cellular and humoral immune responses with appropriate adjuvant in C57 BL/ 6 mice and could be used for future research.     

The effects of β-adrenergic stimulation and exercise on NR4A3 protein expression in rat skeletal muscle

β-Adrenergic stimulation and exercise up-regulate the mRNA expression of nuclear receptor NR4A3, which is involved in the regulation of glucose and fatty acid utilization genes in skeletal muscle. The objective of our study was to examine the effects of β-adrenergic stimulation and exercise on the expression of NR4A3 protein in rat skeletal muscle. A single subcutaneous injection of clenbuterol, which is a β2-adrenergic receptor (β2-AR) agonist, increased NR4A3 mRNA and protein expression in the fast-twitch glycolytic triceps muscle. On the other hand, an acute 3-h session of either treadmill running or swimming did not increase the NR4A3 protein level in the exercised muscle, although both treadmill running and swimming increased NR4A3 mRNA. Finally, loss of postural contractile activity because of hindlimb immobilization reduced NR4A3 mRNA and protein in the slow-twitch oxidative soleus muscle. These results suggest that: β-adrenergic stimulation up-regulates not only NR4A3 mRNA but also NR4A3 protein in fast-twitch glycolytic muscle; exercise may increase NR4A3 mRNA but not NR4A3 protein in skeletal muscle; and local postural contractile activity plays a crucial role in maintaining NR4A3 protein expression level in postural muscle.     

Substantial effects of apolipoprotein E ε4 on memory decline in very old age: longitudinal findings from a population-based sample

We examined associations between the apolipoprotein E (APOE) ε4 allele and levels of performance and rates of change in cognition in late life taking incident dementia into account. The sample consisted of 482 nondemented individuals, aged 80 years and older at baseline, drawn from the OCTO twin study. A battery of 10 cognitive tests was administered at 5 occasions with measurements intervals of 2 years. We fitted hierarchical linear models with time specified as time to death and controlled for baseline age, sex, education, stroke, cardiovascular disease, hypertension, diabetes, and incident dementia. The ε4 allele was significantly associated with lower levels of performance or steeper rate of decline in all 7 memory tests. Largest effect sizes were found in tests of delayed recall and recognition memory. The effects of the APOE ε4 allele were, however, reduced to a nonsignificant level in all tests except 1 after accounting for incident dementia. The findings support the notion that the APOE ε4 allele is associated with substantial memory decline in very old age, but as expected, the effect is largely related to incident dementia.     

Apolipoprotein E ε4 and age effects on florbetapir positron emission tomography in healthy aging and Alzheimer disease

Objectives

Investigate apolipoprotein E ε4 (APOE4) gene and aging effects on florbetapir F18 positron emission tomography (PET) in normal aging and Alzheimer's disease (AD). Methods: Florbetapir F18 PET images were analyzed from 245 participants, 18–92 years of age, from Avid Radiopharmaceutical's multicenter registered trials, including 86 younger healthy control volunteers (yHC), 61 older healthy control volunteers (oHC), 53 mild cognitive impairment (MCI) patients, and 45 AD dementia patients (DAT). Mean florbetapir standard uptake value ratios (SUVRs) were used to evaluate the effects of APOE4 carrier status, older age, and their interaction in each of these groups. Results: In comparison with non-carriers, the APOE4 carriers in each of the oHC, MCI, and DAT groups had higher mean cortical-to-cerebellar florbetapir SUVRs, patterns of florbetapir PET elevations characteristic of DAT, and a higher proportion meeting florbetapir PET positivity criteria. Only the oHC group had a significant association between mean cortical florbetapir SUVRs and age. In cognitively normal adults, without regards to APOE4 genotype, amyloid began to increase at age 58 (95% confidence interval [CI]: 52.3–63.7), with a predicted typical age of florbetapir positivity occurring around age 71 years. Presence of the APOE4 gene reduced the age of predicted florbetapir positivity in normal aging to around age 56 years, approximately 20 years younger than non-carriers. Interpretation: Cerebral amyloid deposition is associated with APOE4 carrier status in older healthy control subjects and symptomatic AD patients, and increases with age in older cognitively normal individuals. Amyloid imaging positivity appears to begin near age 56 years in cognitively intact APOE4 carriers and age 76 years in APOE4 non-carriers.     

ApoE ε4 is associated with eIF2α phosphorylation and impaired learning in young mice

Protein translation is regulated during both initiation and elongation phases to enable cells to accommodate for ever-changing environmental and internal states. Eukaryotic initiation factor-2 (eIF2)α, a major signaling pathway for responses to metabolic stress, controls translation initiation in various cells, including neurons, and affects cognitive functions. The main risk factor for sporadic Alzheimer's disease (SAD) is aging, and the main genetic risk factor reducing the age of SAD onset is the expression of apolipoprotein E (ApoE)4. We tested the hypothesis that both genetic and aging risk factors converge on the eIF2α pathway. Aged rodents showed increased eIF2α phosphorylation in the brain, indicating a shift in the rate of translation initiation with increasing age. Interestingly, mice overexpressing human ApoE4 already, at an early age, exhibited increased eIF2α phosphorylation together with mild impairment in cognitive tasks, compared with ApoE3 mice. These results suggest that the eIF2α pathway is linked to SAD, possibly via genetic as well as prolonged metabolic stress, and these findings position it as a new and important target for treatment of the currently incurable Alzheimer's disease.     

The effect of APOE genotype on brain levels of oxysterols in young and old human APOE ε2, ε3 and ε4 knock-in mice

Despite apolipoprotein E's important role in cholesterol transport and metabolism in the brain as well as its influence on Alzheimer's disease, the impact of the human APOE genotype on cholesterol metabolism in brain has not been fully examined. This study was carried out to investigate APOE genotype effects on oxysterols measured. In this study the measurement of cholesterol and several oxysterols in the brains of human APOE ε2, ε3 and ε4 knock-in mice at 8 weeks and 1 year of age using gas chromatography mass spectrometry (GC–MS) demonstrated no APOE genotype or age effect on total brain cholesterol and the oxysterol 24-hydroxycholesterol. The level of 27-hydroxycholesterol was elevated in 1 year old animals for all APOE genotypes. Interestingly, lathosterol an indicator of cholesterol synthesis was significantly reduced in the 1 year old animals for all APOE genotypes. APOE ε4 expressing mice exhibited statistically lower levels of lathosterol compared to APOE ε2 in both the young and old mice. Oxidized cholesterol metabolites were significantly lower in APOE ε2 mice compared to other genotypes at 8 weeks old. Although minimal differences were observed between APOE E3 and E4 knock-in (KI) mice, these findings indicate that there are some clear APOE genotype specific effects on brain cholesterol synthesis and associated metabolic pathways, particularly in APOE ε2 KI mice.     

Genetic interaction between α4 and β2 subunits of high affinity nicotinic receptor: analysis in schizophrenia

Cholinergic dysfunction is one of the hypotheses for the cognitive deficits of schizophrenia. Neurocognitive deficits, which are well-described clinical features of schizophrenia, may be remediated by nicotine; therefore investigations of nicotinic receptor subtypes is of considerable clinical interest. We typed polymorphisms in CHRNA4 and CHRNB2 genes controlling the expression of neuronal high-affinity nicotinic receptors in 117 Canadian families having at least one schizophrenic patient. Using a family-based association strategy, we performed allele, haplotype and interaction analysis of these two loci. In the families tested, the two cholinergic genes interact to affect schizophrenia in combination (P=0.010), while neither was sufficient alone to confer susceptibility. Our present study provided the first line of direct evidence suggesting that the CHRNA4 gene combined with CHRNB2 receptor gene may be linked to schizophrenia.Vincenzo De Luca and Sophocles Voineskos have contributed equally to this work     

Four weeks one-leg training and high fat diet does not alter PPARα protein or mRNA expression in human skeletal muscle

Fatty acid metabolism is influenced by training and diet with exercise training mediating this through activation of nuclear hormone receptor peroxisome proliferator-activated receptor α (PPARα) in skeletal muscle. This study investigated the effect of training and high fat or normal diet on PPARα expression in human skeletal muscle. Thirteen men trained one leg (T) four weeks (31.5 h in total), while the other leg (UT) served as control. During the 4 weeks six subjects consumed high fat (FAT) diet and seven subjects maintained a normal (CHO) diet. Biopsies were obtained from vastus lateralis muscle in both legs before and after training. After the biopsy, one-leg extension exercise was performed in random order with both legs 30 min at 95% of workload max. A training effect was evident as citrate synthase activity increased (P < 0.05) by 15% in the trained, but not the control leg in both groups. During exercise respiratory exchange ratio was lower in FAT (0.86 ± 0.01, 0.83 ± 0.01, mean ± SEM) than CHO (0.96 ± 0.02, 0.94 ± 0.03) and in UT than T legs, respectively. The PPARα protein (144 ± 44, 104 ± 28, 79 ± 15, 79 ± 14, % of pre level) and PPARα mRNA (69 ± [2, 2], 78 ± [7, 6], 92 ± [22, 18], 106 ± [21, 18], % of pre level, geometric mean ± SEM) expression remained unchanged by diet and training in FAT (UT, T) and CHO (UT, T), respectively. After the training and diet CS, HAD, PPARα, UCP2, UCP3 and mFABP mRNA content remained unchanged, whereas GLUT4 mRNA was lower in both groups and LDHA mRNA was lower (P < 0.05) only in FAT. In conclusion: 4 weeks one leg knee extensor training did not affect PPARα protein or mRNA expression. Furthermore, higher fat oxidation during exercise after fat rich diet was not accompanied by an increased PPARα protein or mRNA expression after 4 weeks.     

The expression of PD-1 and level of CXCL10 in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is known tobe a chronic and complicated rheumatic diseasewith an autoimmune etiology.SLEis also a proto-type of autoimmune disease due to a substantialoverlapinits clinical symptoms withother autoim-mune diseases . The immune systemof SLElosesbalance of auto-tolerance ,in which lymphocytesare activated excessively,contributingto SLE de-velopment .It has been well established that effi-cient T cell-mediated immune responses requirenot only the TCR-mediat…     

The associations of circulating CD4+CD25high regulatory T cells and TGF-β with disease activity and clinical course in patients with adult-onset Still's disease

Objective. To determine circulating levels of CD4⁺CD25^high regulatory T (Treg) cells and transforming growth factor-β (TGF-β) in patients with adult-onset Still's disease (AOSD) and to examine the associations with disease activity and clinical course of this disease. Methods. The frequencies of circulating CD4⁺CD25^high Treg cells in 52 active AOSD patients, 42 active systemic lupus erythematosus (SLE) patients, and 22 healthy controls (HCs) were determined using flow cytometry analysis. Levels of serum TGF-β and soluble interleukin-2 receptor (sIL-2R) were measured by enzyme-linked immunosorbent assay. Results. Significantly lower levels of circulating CD4⁺CD25^high Treg cells and serum TGF-β were found in AOSD patients and SLE patients than those found in HCs. Levels of circulating CD4⁺CD25^high Treg cells and TGF-β were inversely correlated with disease activity scores for AOSD patients and SLE patients. Circulating CD4⁺CD25^high Treg cell frequencies were positively correlated with serum TGF-β levels for patients with both diseases. Levels of circulating CD4⁺CD25^high Treg cells and TGF-β significantly increased, paralleling clinical remission and the decrease in levels of C-reactive protein and soluble interleukin-2 receptor after effective therapy in AOSD patients. AOSD patients with monocyclic course had significantly higher levels of circulating CD4⁺CD25^high Treg cells and TGF-β compared to those with polycyclic and chronic articular course. Conclusion. Diminished levels of circulating CD4⁺CD25^high Treg cells and TGF-β, and inverse correlation with disease activity in patients with AOSD and SLE might be involved in the pathogenesis of both diseases. Increased levels of circulating CD4⁺CD25^high Treg cells or TGF-β might be associated with a favorable clinical course in AOSD patients.     

Apolipoprotein E (APOE) ε4 and episodic memory decline in Alzheimer’s disease: A review

A growing body of research has examined the relationship between episodic memory decline, the cognitive hallmark of Alzheimer’s disease (AD), and the presence of Apolipoprotein E ε4 (APOE ε4) allele, a major genetic risk factor for the disease. Our review attempts to summarize and critically evaluate this literature. We performed a systematic search for studies assessing episodic memory in AD patients who were genotyped for APOE ε4 and identified fourteen papers. Although most of these papers reported significant relationships between APOE ε4 and episodic memory decline in AD, some papers did not confirm this relationship. Our review links this controversy to the conflicting literature about the effects of APOE ε4 on general cognitive functioning in AD. We identify several shortcoming and limitations of the research on the relationship between APOE ε4 and episodic memory in AD, such as small sample sizes, non-representative populations, lack of comparison of early-onset vs. late-onset disease, and lack of comparison among different genotypes that include APOE ε4 (i.e., zero, one, or two ε4 alleles). Another major shortcoming of the reviewed literature was the lack of comprehensive evaluation of episodic memory decline, since episodic memory was solely evaluated with regard to encoding and retrieval, omitting evaluation of core episodic features that decline in AD, such as context recall (e.g., how, where, and when an episodic event has occurred) and subjective experience of remembering (e.g., reliving, emotion and feeling during episodic recollection). Future research taking these limitations into consideration could illuminate the nature of the relationship between APOE ε4 and episodic memory decline in AD.     

The role of C/EBP-α expression in human liver and liver fibrosis and its relationship with autophagy

Aim: To investigate the expression of CCAAT enhancer binding protein-α (C/EBP-α) in normal human liver and liver fibrosis and its probable association with autophagy. Methods: Double label immunohistochemistry was used to detect the location of C/EBP-α in hepatocytes and hepatic stellate cells (HSCs). The expression of C/EBP-α, Atg5, and Atg6 was also evaluated by immunohistochemistry in paraffin sections of human liver. HSC-T6 cells were treated with rapamycin and 3-methyladenine (3MA) to induce or inhibit autophagy, and the expression of C/EBP-α protein was detected by Western blotting. Results: Double label immunohistochemistry showed that C/EBP-α was predominantly located in hepatocytes and that its expression was significantly decreased in fibrosis compared with normal liver. Atg5 expression was increased in fibrosis but was located primarily in liver septa and peri-vascular areas, which was consistent with the distribution of HSCs. In contrast, Atg6 was not expressed in normal or fibrotic liver. Treatment of HSC-T6 cells in culture with rapamycin or 3MA decreased or increased C/EBP-α expression, respectively, as shown by Western blotting. Conclusion: C/EBP-α was primarily expressed in hepatocytes in normal liver, but its expression decreased significantly in liver fibrosis. Autophagy might play a role in liver fibrosis through its association with C/EBP-α, but this hypothesis warrants further investigation.