A Sensitive and Cost-Effective Chemiluminescence ELISA for Measurement of Amyloid-ß 1-42 Peptide in Human Plasma.

BACKGROUND: Amyloid-ß42 (Aß42) is associated with plaque formation in the brain of patients with Alzheimer's disease (AD). Studies have suggested the potential utility of plasma Aß42 levels in the diagnosis, and in longitudinal study of AD pathology. Conventional ELISAs are used to measure Aß42 levels in plasma but are not sensitive enough to quantitate low levels. Although ultrasensitive assays like single molecule array or immunoprecipitation-mass spectrometry have been developed to quantitate plasma Aß42 levels, the high cost of instruments and reagents limit their use. OBJECTIVE: We hypothesized that a sensitive and cost-effective chemiluminescence (CL) immunoassay could be developed to detect low Aß42 levels in human plasma. METHODS: We developed a sandwich ELISA using high affinity rabbit monoclonal antibody specific to Aß42. The sensitivity of the assay was increased using CL substrate to quantitate low levels of Aß42 in plasma. We examined the levels in plasma from 13 AD, 25 Down syndrome (DS), and 50 elderly controls. RESULTS: The measurement range of the assay was 0.25 to 500 pg/ml. The limit of detection was 1 pg/ml. All AD, DS, and 45 of 50 control plasma showed measurable Aß42 levels. CONCLUSION: This assay detects low levels of Aß42 in plasma and does not need any expensive equipment or reagents. It offers a preferred alternative to ultrasensitive assays. Since the antibodies, peptide, and substrate are commercially available, the assay is well suited for academic or diagnostic laboratories, and has a potential for the diagnosis of AD or in clinical trials.

Generation and Partial Characterization of Rabbit Monoclonal Antibody to Pyroglutamate Amyloid-ß3-42 (pE3-Aß).

N-terminally truncated pyroglutamate amyloid-ß (Aß) peptide starting at position 3 represents a significant fraction of Aß peptides (pE3-Aß) in amyloid plaques of postmortem brains from patients with Alzheimer's disease (AD) and older persons with Down syndrome (DS). Studies in transgenic mouse models of AD also showed that pE3-Aß is a major component of plaques, and mouse monoclonal antibody to pE3-Aß appears to be a desirable therapeutic agent for AD. Since small peptides do not typically elicit a good immune response in mice, but do so favorably in rabbits, our aims were to generate and partially characterize a rabbit monoclonal antibody (RabmAb) to pE3-Aß. The generated RabmAb was found to be specific for pE3-Aß, since it showed no reactivity with Aß16, Aß40, Aß42, Aß3-11, and pE11-17 Aß peptides in an enzyme linked immunosorbent assay (ELISA). The isotype of the antibody was found to be IgG class. The antibody possesses high affinity to pE3-Aß with dissociation constant (KD) for the antibody of 1 nM. The epitope of the antibody lies within the sequence of pE3-FRHD. In dot blotting, the optimal detection of pE3-Aß was at an antibody concentration of 0.5 µg/ml. The threshold of pE3-Aß detection was 2 fmol. The antibody was sensitive enough to detect 10 pg/ml of pE3-Aß in sandwich ELISA. pE3-Aß was detected in AD and DS brain extracts in ELISA and immunoblotting. Immunohistological studies showed immunolabeling of plaques and blood vessels in brains from patients with AD, and DS showing AD pathology. Thus, the antibody can be widely applied in AD and DS research, and therapeutic applications.

Targeting Apolipoprotein E/Amyloid ß Binding by Peptoid CPO_Aß17-21 P Ameliorates Alzheimer's Disease Related Pathology and Cognitive Decline.

Inheritance of the apolipoprotein E4 (apoE4) genotype has been identified as the major genetic risk factor for late onset Alzheimer's disease (AD). Studies have shown that apoE, apoE4 in particular, binds to amyloid-ß (Aß) peptides at residues 12-28 of Aß and this binding modulates Aß accumulation and disease progression. We have previously shown in several AD transgenic mice lines that blocking the apoE/Aß interaction with Aß12-28 P reduced Aß and tau-related pathology, leading to cognitive improvements in treated AD mice. Recently, we have designed a small peptoid library derived from the Aß12-28 P sequence to screen for new apoE/Aß binding inhibitors with higher efficacy and safety. Peptoids are better drug candidates than peptides due to their inherently more favorable pharmacokinetic properties. One of the lead peptoid compounds, CPO_Aß17-21 P, diminished the apoE/Aß interaction and attenuated the apoE4 pro-fibrillogenic effects on Aß aggregation in vitro as well as apoE4 potentiation of Aß cytotoxicity. CPO_Aß17-21 P reduced Aß-related pathology coupled with cognitive improvements in an AD APP/PS1 transgenic mouse model. Our study suggests the non-toxic, non-fibrillogenic peptoid CPO_Aß17-21 P has significant promise as a new AD therapeutic agent which targets the Aß related apoE pathway, with improved efficacy and pharmacokinetic properties.

Physical activity predicts reduced plasma ß amyloid in the Cardiovascular Health Study.

OBJECTIVE: Higher levels of physical activity (PA) reduce the risk of cognitive impairment, but the underlying mechanisms are unclear. Using longitudinal data from the Cardiovascular Health Study, we examined whether PA predicted plasma Aß levels and risk for cognitive decline 9-13 years later. METHODS: Linear and logistic regressions (controlling for APOE status, age, gender, body mass index, cardiovascular disease, brain white matter lesions, and cystatin C levels) tested associations between PA, Aß, and cognitive impairment in a sample of 149 cognitively normal older adults (mean age 83 years). RESULTS: More PA at baseline predicted lower levels of Aß 9-13 years later. Higher Aß levels at year 9 predicted greater risk for cognitive impairment at year 13. Levels of Aß at year 9 mediated the relationship between PA and cognitive impairment. INTERPRETATION: Greater PA may reduce plasma levels of a neurotoxic peptide at an age when the risk for cognitive impairment is especially high.

Generation and Partial Characterization of Rabbit Monoclonal Antibody to Amyloid-ß Peptide 1-37 (Aß37).

Secreted soluble amyloid-ß 1-37 (Aß37) peptide is one of the prominent Aß forms next to Aß40, and is found in cerebrospinal fluid (CSF) and blood. Recent studies have shown the importance of quantitation of CSF Aß37 levels in combination with Aß38, Aß40, and Aß42 to support the diagnosis of patients with probable Alzheimer's disease (AD), and the value of antibody to Aß37 to facilitate drug discovery studies. However, the availability of reliable and specific monoclonal antibody to Aß37 is very limited. Our aims were: 1) to generate and partially characterize rabbit monoclonal antibody (RabmAb) to Aß37, and 2) to determine whether the antibody detects changes in Aß37 levels produced by a γ-secretase modulator (GSM). Our generated RabmAb to Aß37 was found to be specific to Aß37, since it did not react with Aß36, Aß38, Aß39, Aß40, and Aß42 in an ELISA or immunoblotting. The epitope of the antibody was contained in the seven C-terminal residues of Aß37. The antibody was sensitive enough to measure CSF and plasma Aß37 levels in ELISA. Immunohistological studies showed the presence of Aß37-positive deposits in the brain of AD, and Down syndrome persons diagnosed with AD. Our studies also showed that the antibody detected Aß37 increases in CSF and brains of rodents following treatment with a GSM. Thus, our antibody can be widely applied to AD research, and in a panel based approach it may have potential to support the diagnosis of probable AD, and in testing the effect of GSMs to target AD.

Innate Immunity Stimulation via Toll-Like Receptor 9 Ameliorates Vascular Amyloid Pathology in Tg-SwDI Mice with Associated Cognitive Benefits.

Alzheimer's disease (AD) is characterized by the presence of parenchymal amyloid-ß (Aß) plaques, cerebral amyloid angiopathy (CAA) and neurofibrillary tangles. Currently there are no effective treatments for AD. Immunotherapeutic approaches under development are hampered by complications related to ineffectual clearance of CAA. Genome-wide association studies have demonstrated the importance of microglia in AD pathogenesis. Microglia are the primary innate immune cells of the brain. Depending on their activation state and environment, microglia can be beneficial or detrimental. In our prior work, we showed that stimulation of innate immunity with Toll-like receptor 9 agonist, class B CpG (cytosine-phosphate-guanine) oligodeoxynucleotides (ODNs), can reduce amyloid and tau pathologies without causing toxicity in Tg2576 and 3xTg-AD mouse models. However, these transgenic mice have relatively little CAA. In the current study, we evaluated the therapeutic profile of CpG ODN in a triple transgenic mouse model, Tg-SwDI, with abundant vascular amyloid, in association with low levels of parenchymal amyloid deposits. Peripheral administration of CpG ODN, both before and after the development of CAA, negated short-term memory deficits, as assessed by object-recognition tests, and was effective at improving spatial and working memory evaluated using a radial arm maze. These findings were associated with significant reductions of CAA pathology lacking adverse effects. Together, our extensive evidence suggests that this innovative immunomodulation may be a safe approach to ameliorate all hallmarks of AD pathology, supporting the potential clinical applicability of CpG ODN. SIGNIFICANCE STATEMENT: Recent genetic studies have underscored the emerging role of microglia in Alzheimer's disease (AD) pathogenesis. Microglia lose their amyloid-ß-clearing capabilities with age and as AD progresses. Therefore, the ability to modulate microglia profiles offers a promising therapeutic avenue for reducing AD pathology. Current immunotherapeutic approaches have been limited by poor clearance of a core AD lesion, cerebral amyloid angiopathy (CAA). The present study used Tg-SwDI mice, which have extensive CAA. We found that stimulation of the innate immune system and microglia/macrophage activation via Toll-like receptor 9 using CpG (cytosine-phosphate-guanine) oligodeoxynucleotides (ODNs) leads to cognitive improvements and CAA reduction, without associated toxicity. Our data indicate that this novel concept of immunomodulation represents a safer method to reduce all aspects of AD pathology and provide essential information for potential clinical use of CpG ODN.

Generation of Rabbit Monoclonal Antibody to Amyloid-ß38 (Aß38): Increased Plasma Aß38 Levels in Down Syndrome.

Secreted soluble amyloid-ß (Aß)38 is the second most prominent Aß form next to Aß40, and is found in cerebrospinal fluid (CSF) and blood. Recent studies have shown the importance of quantitation of CSF Aß38 levels in combination with those of Aß40 and Aß42 to support the diagnosis of Alzheimer's disease (AD), and other neurodegenerative diseases, and to facilitate drug discovery studies. However, the availability of reliable and specific Aß38 monoclonal antibody is limited. Our first aim was to generate and partially characterize rabbit monoclonal antibody (RabmAb) to Aß38. The antibody was specific to Aß38, since it did not react with Aß37, Aß39, Aß40, or Aß42 in ELISA or immunoblotting. The antibody was sensitive enough to measure Aß38 levels in plasma. Our second aim was to quantitate Aß38 levels in plasma from older Down syndrome (DS) persons and age-matched controls. Persons with DS (35 years and older) have neuropathological changes characteristic of AD. Studies have shown that plasma Aß40 and Aß42 levels are higher in older persons with DS than in controls. However, none examined Aß38 levels in DS. Our quantitation data showed that, like Aß40 and Aß42 plasma levels, Aß38 plasma levels were higher in DS than in controls. Longitudinal studies will determine whether plasma Aß38 levels in combination with levels of Aß40 and Aß42 are useful to predict early signs of AD in DS.

Bone mineral density, adiposity, and cognitive functions.

Cognitive decline and dementia due to Alzheimer's disease (AD) have been associated with genetic, lifestyle, and environmental factors. A number of potentially modifiable risk factors should be taken into account when preventive or ameliorative interventions targeting dementia and its preclinical stages are investigated. Bone mineral density (BMD) and body composition are two such potentially modifiable risk factors, and their association with cognitive decline was investigated in this study. 164 participants, aged 34-87 years old (62.78 ± 9.27), were recruited for this longitudinal study and underwent cognitive and clinical examinations at baseline and after 3 years. Blood samples were collected for apolipoprotein E (APOE) genotyping and dual energy x-ray absorptiometry (DXA) was conducted at the same day as cognitive assessment. Using hierarchical regression analysis, we found that BMD and lean body mass, as measured using DXA were significant predictors of episodic memory. Age, gender, APOE status, and premorbid IQ were controlled for. Specifically, the List A learning from California Verbal Learning Test was significantly associated with BMD and lean mass both at baseline and at follow up assessment. Our findings indicate that there is a significant association between BMD and lean body mass and episodic verbal learning. While the involvement of modifiable lifestyle factors in human cognitive function has been examined in different studies, there is a need for further research to understand the potential underlying mechanisms.

Amyloid ß and Tau Alzheimer's disease related pathology is reduced by Toll-like receptor 9 stimulation.

Alzheimer's disease (AD) is the most common cause of dementia, and currently, there is no effective treatment. The major neuropathological lesions in AD are accumulation of amyloid ß (Aß) as amyloid plaques and congophilic amyloid angiopathy, as well as aggregated tau in the form of neurofibrillary tangles (NFTs). In addition, inflammation and microglia/macrophage function play an important role in AD pathogenesis. We have hypothesized that stimulation of the innate immune system via Toll-like receptor 9 (TLR9) agonists, such as type B CpG oligodeoxynucleotides (ODNs), might be an effective way to ameliorate AD related pathology. We have previously shown in the Tg2576 AD model that CpG ODN can reduce amyloid deposition and prevent cognitive deficits. In the present study, we used the 3xTg-AD mice with both Aß and tau related pathology. The mice were divided into 2 groups treated from 7 to 20 months of age, prior to onset of pathology and from 11 to 18 months of age, when pathology is already present. We demonstrated that immunomodulatory treatment with CpG ODN reduces both Aß and tau pathologies, as well as levels of toxic oligomers, in the absence of any apparent inflammatory toxicity, in both animal groups. This pathology reduction is associated with a cognitive rescue in the 3xTg-AD mice. Our data indicate that modulation of microglial function via TLR9 stimulation is effective at ameliorating all the cardinal AD related pathologies in an AD mouse model suggesting such an approach would have a greater chance of achieving clinical efficacy.

Blocking the apolipoprotein E/amyloid ß interaction in triple transgenic mice ameliorates Alzheimer's disease related amyloid ß and tau pathology.

Inheritance of the apolipoprotein E4 (apoE4) genotype has been identified as the major genetic risk factor for late-onset Alzheimer's disease (AD). Studies have shown that the binding between apoE and amyloid-ß (Aß) peptides occurs at residues 244-272 of apoE and residues 12-28 of Aß. ApoE4 has been implicated in promoting Aß deposition and impairing clearance of Aß. We hypothesized that blocking the apoE/Aß interaction would serve as an effective new approach to AD therapy. We have previously shown that treatment with Aß12-28P can reduce amyloid plaques in APP/PS1 transgenic (Tg) mice and vascular amyloid in TgSwDI mice with congophilic amyloid angiopathy. In the present study, we investigated whether the Aß12-28P elicits a therapeutic effect on tau-related pathology in addition to amyloid pathology using old triple transgenic AD mice (3xTg, with PS1M146V , APPSwe and tauP30IL transgenes) with established pathology from the ages of 21 to 26 months. We show that treatment with Aß12-28P substantially reduces tau pathology both immunohistochemically and biochemically, as well as reducing the amyloid burden and suppressing the activation of astrocytes and microglia. These affects correlate with a behavioral amelioration in the treated Tg mice.

Lower CSF amyloid beta peptides and higher F2-isoprostanes in cognitively intact elderly individuals with major depressive disorder.

OBJECTIVE: Major depressive disorder is common in the elderly, and symptoms are often not responsive to conventional antidepressant treatment, especially in the long term. Soluble oligomeric and aggregated forms of amyloid beta peptides, especially amyloid beta 42, impair neuronal and synaptic function. Amyloid beta 42 is the main component of plaques and is implicated in Alzheimer's disease. Amyloid beta peptides also induce a depressive state in rodents and disrupt major neurotransmitter systems linked to depression. The authors assessed whether major depression was associated with CSF levels of amyloid beta, tau protein, and F2-isoprostanes in elderly individuals with major depressive disorder and age-matched nondepressed comparison subjects. METHOD: CSF was obtained from 47 cognitively intact volunteers (major depression group, N=28; comparison group, N=19) and analyzed for levels of soluble amyloid beta, total and phosphorylated tau proteins, and isoprostanes. RESULTS: Amyloid beta 42 levels were significantly lower in the major depression group relative to the comparison group, and amyloid beta 40 levels were lower but only approaching statistical significance. In contrast, isoprostane levels were higher in the major depression group. No differences were observed in total and phosphorylated tau proteins across conditions. Antidepressant use was not associated with differences in amyloid beta 42 levels. CONCLUSIONS: Reduction in CSF levels of amyloid beta 42 may be related to increased brain amyloid beta plaques or decreased soluble amyloid beta production in elderly individuals with major depression relative to nondepressed comparison subjects. These results may have implications for our understanding of the pathophysiology of major depression and for the development of treatment strategies.

Plasma BDNF levels vary in relation to body weight in females.

Brain derived neurotrophic factor (BDNF) has been implicated in the pathophysiology of depression as well as neuropsychiatric and neurodegenerative disorders. Recent studies show a role of BDNF in energy metabolism and body weight regulation. We examined BDNF levels in plasma and cerebrospinal fluid (CSF) samples from age matched elderly depressed and control subjects. Also, the association of BDNF levels with age, gender, body weight, body mass index (BMI), and cognitive performance was evaluated. We did not find any significant differences in plasma and CSF BDNF levels between depressed and control subjects. Plasma BDNF levels were negatively correlated with age (but not with BMI and body weight), when analyses were performed including both depressed and control subjects. A significant reduction in plasma BDNF levels was observed in females as compared to male subjects, and the change in BDNF levels were significantly and positively related to body weight in females. Furthermore, significant increases in Total Recall and Delayed Recall values were found in females as compared to males. In conclusion, the lower BDNF levels observed in females suggest that changes in peripheral BDNF levels are likely secondary to an altered energy balance. However, further studies using larger sample size are warranted.

Abnormal intracellular accumulation and extracellular Aß deposition in idiopathic and Dup15q11.2-q13 autism spectrum disorders.

BACKGROUND: It has been shown that amyloid ß (Aß), a product of proteolytic cleavage of the amyloid ß precursor protein (APP), accumulates in neuronal cytoplasm in non-affected individuals in a cell type-specific amount. METHODOLOGY/PRINCIPAL FINDINGS: In the present study, we found that the percentage of amyloid-positive neurons increases in subjects diagnosed with idiopathic autism and subjects diagnosed with duplication 15q11.2-q13 (dup15) and autism spectrum disorder (ASD). In spite of interindividual differences within each examined group, levels of intraneuronal Aß load were significantly greater in the dup(15) autism group than in either the control or the idiopathic autism group in 11 of 12 examined regions (p<0.0001 for all comparisons; Kruskall-Wallis test). In eight regions, intraneuronal Aß load differed significantly between idiopathic autism and control groups (p<0.0001). The intraneuronal Aß was mainly N-terminally truncated. Increased intraneuronal accumulation of Aß(17-40/42) in children and adults suggests a life-long enhancement of APP processing with α-secretase in autistic subjects. Aß accumulation in neuronal endosomes, autophagic vacuoles, Lamp1-positive lysosomes and lipofuscin, as revealed by confocal microscopy, indicates that products of enhanced α-secretase processing accumulate in organelles involved in proteolysis and storage of metabolic remnants. Diffuse plaques containing Aß(1-40/42) detected in three subjects with ASD, 39 to 52 years of age, suggest that there is an age-associated risk of alterations of APP processing with an intraneuronal accumulation of a short form of Aß and an extracellular deposition of full-length Aß in nonfibrillar plaques. CONCLUSIONS/SIGNIFICANCE: The higher prevalence of excessive Aß accumulation in neurons in individuals with early onset of intractable seizures, and with a high risk of sudden unexpected death in epilepsy in autistic subjects with dup(15) compared to subjects with idiopathic ASD, supports the concept of mechanistic and functional links between autism, epilepsy and alterations of APP processing leading to neuronal and astrocytic Aß accumulation and diffuse plaque formation.

Cognitive response to estradiol in postmenopausal women is modified by high cortisol.

Estradiol has potent favorable effects on brain function and behavior in animals while in human trials, the results are inconsistent. A number of potential mediating variables influencing response to estradiol have been proposed to account for this variability, 1 of which includes stress. We conducted a placebo-controlled study to examine joint and independent effects of estradiol and elevated levels of the stress hormone cortisol on cognition and biomarkers of aging and neurodegenerative disease. Thirty-nine healthy postmenopausal women (56-84 years) received 0.10 mg/dL of transdermal 17ß-estradiol (E2) or placebo for 8 weeks. During the last 4 days of the trial, subjects also received 90 mg/day (30 mg 3×/day) of oral hydrocortisone (CORT) to induce stress-level elevations in cortisol, or a matched placebo. The 4 groups thus included placebo (placebo patch/placebo pill), CORT-alone (placebo patch/hydrocortisone), E2-alone (estradiol patch/placebo pill), and E2+CORT (estradiol patch/hydrocortisone). Eight weeks of E2 increased plasma estradiol by 167%, and 4 days of CORT increased plasma cortisol by 119%. Overall, E2 had favorable effects on verbal memory (p = 0.03), working memory (p = 0.02), and selective attention (p = 0.04), and the magnitude of these effects was attenuated for E2+CORT. E2-alone and E2+CORT had opposing effects on plasma levels of the amyloid-ß (Aß) biomarker (Aß40/42 ratio, p < 0.05), with the more favorable response observed for E2-alone. CORT-induced increases in insulin-like growth factor-1 were blunted by E2 coadministration. Our findings indicate that cognitive and physiological responses to estradiol are adversely affected by elevated stress hormone levels of cortisol in healthy postmenopausal women.

Association between variants in IDE-KIF11-HHEX and plasma amyloid ß levels.

Genetic linkage and association studies in late-onset Alzheimer's disease (LOAD) or its endophenotypes have pointed to several regions on chromosome 10q, among these the ∼ 250 kb linkage disequilibrium (LD) block harboring the genes IDE, KIF1, and HHEX. We explored the association between variants in the genomic region harboring the IDE-KIF11-HHEX complex with plasma Aß40 and Aß42 levels in a case-control cohort of Caribbean Hispanics. First, we performed single marker linear regression analysis relating the individual single nucleotide polymorphisms (SNPs) with plasma Aß40 and Aß42 levels. Then we performed 3-SNP sliding window haplotype analyses, correcting all analyses for multiple testing. Out of 32 SNPs in this region, 3 SNPs in IDE (rs2421943, rs12264682, rs11187060) were associated with plasma Aß40 or Aß42 levels in single marker and haplotype analyses after correction for multiple testing. All these SNPs lie within the same LD block, and are in LD with the previously reported haplotypes. Our findings provide support for an association in the IDE region on chromosome 10q with Aß40 and 42 levels.

TOMM40 poly-T variants and cerebrospinal fluid amyloid beta levels in the elderly.

A variable poly-T polymorphism in the TOMM40 gene, which is in linkage disequilibrium with APOE, was recently implicated with increased risk and earlier onset age for late-onset Alzheimer's disease in APOE ε3 carriers. To elucidate potential neurobiological mechanisms underlying this association, we compared the effect of TOMM40 poly-T variants to the effect of APOE, an established LOAD-risk modulator, on cerebrospinal fluid (CSF) amyloid beta (Aß) and tau levels, in cognitively intact elderly subjects. APOE ε4 carriers showed significant reductions in Aß 1-42 levels compared to non-ε4 carriers, but no differences were detected across TOMM40 variants. Neither Aß 1-40 nor tau levels were affected by APOE or TOMM40.

High-affinity rabbit monoclonal antibodies specific for amyloid peptides amyloid-ß40 and amyloid-ß42.

Antibodies that specifically bind to either amyloid-ß peptide (Aß) isoform Aß40 or Aß42 contribute to the study of Alzheimer's disease (AD) pathology and to the development of cerebrospinal fluid-based tests for the probable diagnosis of AD. Polyclonal rabbit anti-Aß antibodies possess high affinity and specificity, but their generation requires a long immunization period, and the resulting antibodies exhibit variable specificities and affinities. To secure a continuing supply of antibodies with uniform properties, we generated and partially characterized rabbit monoclonal antibodies specific for either Aß40 or Aß42. These antibodies possess nanomolar or sub-nanomolar dissociation constants and are at least 3,000-fold more selective for one isoform over the other. These antibodies are suitable for immunoblotting and, in a sandwich ELISA, RabmAb42 (anti-Aß42) is sensitive enough to measure plasma levels of Aß42. In addition, these antibodies have been applied to the immunohistology of Down syndrome and AD brain tissues, where they reveal fibrillar and diffuse amyloid deposits and are almost free of non-specific staining. The data indicate that diffuse amyloid deposits contain only minute amounts of Aß40. Thus these rabbit monoclonal anti-Aß antibodies can be widely applied in AD and Down syndrome research and diagnosis.

Anti-PrPC monoclonal antibody infusion as a novel treatment for cognitive deficits in an Alzheimer's disease model mouse.

BACKGROUND: Alzheimer's Disease (AD) is the most common of the conformational neurodegenerative disorders characterized by the conversion of a normal biological protein into a ß-sheet-rich pathological isoform. In AD the normal soluble Aß (sAß) forms oligomers and fibrils which assemble into neuritic plaques. The most toxic form of Aß is thought to be oligomeric. A recent study reveals the cellular prion protein, PrPC, to be a receptor for Aß oligomers. Aß oligomers suppress LTP signal in murine hippocampal slices but activity remains when pretreated with the PrP monoclonal anti-PrP antibody, 6D11. We hypothesized that targeting of PrPC to prevent Aß oligomer-related cognitive deficits is a potentially novel therapeutic approach. APP/PS1 transgenic mice aged 8 months were intraperitoneally (i.p.) injected with 1 mg 6D11 for 5 days/week for 2 weeks. Two wild-type control groups were given either the same 6D11 injections or vehicle solution. Additional groups of APP/PS1 transgenic mice were given either i.p. injections of vehicle solution or the same dose of mouse IgG over the same period. The mice were then subjected to cognitive behavioral testing using a radial arm maze, over a period of 10 days. At the conclusion of behavioral testing, animals were sacrificed and brain tissue was analyzed biochemically or immunohistochemically for the levels of amyloid plaques, PrPC, synaptophysin, Aß40/42 and Aß oligomers. RESULTS: Behavioral testing showed a marked decrease in errors in 6D11 treated APP/PS1 Tg mice compared with the non-6D11 treated Tg groups (p < 0.0001). 6D11 treated APP/PS1 Tg mice behaved the same as wild-type controls indicating a recovery in cognitive learning, even after this short term 6D11 treatment. Brain tissue analysis from both treated and vehicle treated APP/PS1 groups indicate no significant differences in amyloid plaque burden, Aß40/42, PrPC or Aß oligomer levels. 6D11 treated APP/PS1 Tg mice had significantly greater synaptophysin immunoreactivity in the dentate gyrus molecular layer of the hippocampus compared to vehicle treated APP/PS1 Tg mice (p < 0.05). CONCLUSIONS: Even short term treatment with monoclonal antibodies such as 6D11 or other compounds which block the binding of Aß oligomers to PrPC can be used to treat cognitive deficits in aged AD transgenic mice.

Oxidative stress and amyloid-beta pathology in normal individuals with a maternal history of Alzheimer's.

BACKGROUND: Epidemiology and imaging studies showed that cognitively normal (NL) individuals with a maternal history (MH) of late-onset Alzheimer's disease (LOAD) might be at increased risk for Alzheimer's disease (AD) compared with NL with a paternal history (PH) and NL with a negative family history of LOAD (NH). With a panel of cerebrospinal fluid (CSF) markers, this study examined whether NL MH showed evidence for AD pathology compared with PH and NH. METHODS: Fifty-nine 40-80-year-old NL subjects were examined, including 23 MH and 14 PH whose parents had a clinician-certified diagnosis of LOAD and 22 NH. All subjects completed clinical neuropsychological examinations and a lumbar puncture to measure CSF levels of amyloid-beta (Aß(40), Aß(42), Aß(42/40)), total and hyperphosphorylated tau (T-Tau and P-Tau(231); markers of axonal degeneration and neurofibrillary tangles, respectively), and F2-isoprostanes (IsoP) (a marker of oxidative stress). RESULTS: Groups were comparable for demographic and neuropsychological measures. The MH subjects showed higher IsoP and reduced Aß(42/40) CSF levels compared with NH and with PH (p values ≤ .05), whereas no differences were found between NH and PH. No group differences were found for P-Tau(231) and T-Tau. The IsoP and Aß(42/40) levels were correlated only within the MH group (R² = .32, p = .005) and discriminated MH from the other subjects with 70% accuracy (relative risk = 3.7%, 95% confidence interval = 1.6-9.7, p < .001). Results remained significant controlling for age, gender, education, and apolipoprotein E genotype. CONCLUSIONS: Adult children of LOAD-affected mothers express a pathobiological phenotype characterized by Aß-associated oxidative stress consistent with AD, which might reflect increased risk for developing the disease.

Aerobic exercise improves cognition for older adults with glucose intolerance, a risk factor for Alzheimer's disease.

Impaired glucose regulation is a defining characteristic of type 2 diabetes mellitus (T2DM) pathology and has been linked to increased risk of cognitive impairment and dementia. Although the benefits of aerobic exercise for physical health are well-documented, exercise effects on cognition have not been examined for older adults with poor glucose regulation associated with prediabetes and early T2DM. Using a randomized controlled design, twenty-eight adults (57-83 y old) meeting 2-h tolerance test criteria for glucose intolerance completed 6 months of aerobic exercise or stretching, which served as the control. The primary cognitive outcomes included measures of executive function (Trails B, Task Switching, Stroop, Self-ordered Pointing Test, and Verbal Fluency). Other outcomes included memory performance (Story Recall, List Learning), measures of cardiorespiratory fitness obtained via maximal-graded exercise treadmill test, glucose disposal during hyperinsulinemic-euglycemic clamp, body fat, and fasting plasma levels of insulin, cortisol, brain-derived neurotrophic factor, insulin-like growth factor-1, amyloid-ß (Aß40 and Aß42). Six months of aerobic exercise improved executive function (MANCOVA, p=0.04), cardiorespiratory fitness (MANOVA, p=0.03), and insulin sensitivity (p=0.05). Across all subjects, 6-month changes in cardiorespiratory fitness and insulin sensitivity were positively correlated (p=0.01). For Aß42, plasma levels tended to decrease for the aerobic group relative to controls (p=0.07). The results of our study using rigorous controlled methodology suggest a cognition-enhancing effect of aerobic exercise for older glucose intolerant adults. Although replication in a larger sample is needed, our findings potentially have important therapeutic implications for a growing number of adults at increased risk of cognitive decline.