Olivier C. Maes

MicroRNA Expression in Alzheimer Blood Mononuclear Cells

Various coding genes representing multiple functional categories are downregulated in blood mononuclear cells (BMC) of patients with sporadic Alzheimer disease (AD). Noncoding microRNAs (miRNA) regulate gene expression by degrading messages or inhibiting translation. Using BMC as a paradigm for the study of systemic alterations in AD, we investigated whether peripheral miRNA expression is altered in this condition. MicroRNA levels were assessed using the microRNA microarray (MMChip) containing 462 human miRNA, and the results validated by real time PCR. Sixteen AD patients and sixteen normal elderly controls (NEC) were matched for ethnicity, age, gender and education. The expression of several BMC miRNAs was found to increase in AD relative to NEC levels, and may differ between AD subjects bearing one or two APOE4 alleles. As compared to NEC, miRNAs significantly upregulated in AD subjects and confirmed by qPCR were miR-34a and 181b. Predicted target genes downregulated in Alzheimer BMC that correlated with the upregulated miRNAs were largely represented in the functional categories of Transcription/Translation and Synaptic Activity. Several miRNAs targeting the same genes were within the functional category of Injury response/Redox homeostasis. Taken together, induction of microRNA expression in BMC may contribute to the aberrant systemic decline in mRNA levels in sporadic AD.

Transcriptional profiling of Alzheimer blood mononuclear cells by microarray.

We evaluated pathomechanisms and systemic manifestations of Alzheimer disease (AD), an aging-related dementing neurodegenerative disorder, by expression profiling. Blood mononuclear cell (BMC) transcriptomes of sporadic AD subjects and aged-matched normal elderly controls (NEC) were compared using the human NIA microarray. Relative to the NEC samples, the Alzheimer BMC exhibited a significant decline in the expression of genes concerned with cytoskeletal maintenance, cellular trafficking, cellular stress response, redox homeostasis, transcription and DNA repair. We observed decreased expression of several genes which may impact amyloid-beta production and the processing of the microtubule-associated protein tau. The microarray results were validated by quantitative real time PCR and revealed gender differences in the levels of altered gene expression. Our findings attest to the systemic nature of gene dys-regulation in sporadic AD, implicate disruption of cytoskeletal integrity, DNA repair mechanisms and cellular defenses in this condition, and suggest novel pathways of beta-amyloid deposition in this disease. BMC are highly accessible and may reflect molecular events germane to the neuropathophysiology of AD.

Characterization of α1-antitrypsin as a heme oxygenase-1 suppressor in Alzheimer plasma

Heme oxygenase-1 (HO-1) mRNA and protein levels are diminished in Alzheimer disease (AD) blood, cerebrospinal fluid (CSF) and choroid plexus. Herein, the presence of a heme oxygenase-1 suppressor (HOS) factor was ascertained by astroglial bioassay, biochemical techniques and immunofluorescence confocal microscopy. We report significantly augmented plasma HOS activity in AD patients relative to healthy elderly and neurological controls. The HOS factor was determined to be a 50-100 kDa heat-labile, heparin-binding glycoprotein that is unrelated to antioxidant ingestion, plasma total antioxidant capacity, circulating cortisol levels or apolipoprotein E epsilon4 carrier status. HOS bioactivity was recapitulated by exogenous alpha(1)-antitrypsin. alpha(1)-antitrypsin levels were significantly increased in AD plasma and correlated with HOS activity and MMSE scores. alpha(1)-antitrypsin immunodepletion attenuated HOS activity of AD plasma. In AD brain, alpha(1)-antitrypsin immunoreactivity was augmented and co-distributed with HO-1. HOS activity of alpha(1)-antitrypsin may curtail HO-1-dependent derangement of cerebral iron homeostasis and account for diminished HO-1 expression in AD peripheral tissues.

Near-Infrared Spectroscopy of Blood Plasma for Diagnosis of Sporadic Alzheimer's Disease

There are currently no accepted blood-based biomarkers of sporadic Alzheimers disease (AD). Augmented oxidative stress has been implicated in both neural and peripheral AD tissues. In this study, we determined whether short-wavelength near-infrared (NIR) spectrophotometry of blood plasma differentiates mild sporadic AD from normal aging. NIR analysis was conducted on 75 microl plasma samples from 19 AD, 27 amnestic MCI, and 17 normal elderly control (NEC) persons using an optical fiber-coupled, holographic grating-based NIR spectrograph. Five spectral bands associated with heme, R-CH, R-OH, H2O, and R-NH functional groups were sensitive to oxidative modification in pre-clinical studies and were pre-selected to develop a logistic regression model for sample classification. This model differentiated AD from NEC samples with a sensitivity of 80% and specificity of 77%. Fifteen and twelve MCI patients were classified with the NEC and AD groups, respectively. The spectra were not influenced by age, gender, exposure to cholinesterase inhibitors or vitamin E, or sample storage time. The NIR data further implicate oxidative stress in the systemic pathophysiology of sporadic AD and differentiate mild (and possibly pre-clinical) AD from NEC individuals with moderate-high accuracy. The procedure is minimally-invasive, rapid, relatively-inexpensive, and may provide a useful biological marker of sporadic AD.

Methodology for Discovery of Alzheimer's Disease Blood-Based Biomarkers

Alzheimers disease (AD) is a degenerative brain disorder. The disease also affects peripheral tissue such as peripheral blood mononuclear cells (PBMCs). Delineating biochemical alterations in AD blood constituents may possibly allow the identification of accessible footprints that reflect degenerative processes within the central nervous system. Here, we describe an integrated methodology for the generation of a blood-based molecular bio-repository, including the collection of clinical and demographic data for downstream stringent sample selection and stratification for the study of molecular signatures in AD. We report the simultaneous extraction of high quality and yield of DNA, RNA, and protein from PBMCs of individuals with sporadic AD, mild cognitive impairment, and normal elderly controls. We describe experimental designs and present examples for the discovery of underlying etiopathogenetic networks in sporadic AD. We suggest that PBMC-associated biomarkers may provide insights into the pathogenesis of AD and be used to monitor disease diagnosis and progression.

Spectroscopy of human plasma for diagnosis of idiopathic Parkinson's disease

BACKGROUND No established chemical biomarkers of idiopathic Parkinsons disease (PD) currently exist. Augmented oxidative stress (OS) has been implicated in both neural and peripheral PD tissues. METHODS In this study, Raman scattering and near-infrared spectroscopy were used to detect and quantify oxidative substrate modifications in blood plasma samples from PD and normal elderly control (NEC) subjects. RESULTS Hypothesis-driven preselection of OS-sensitive bandwidths distinguished PD from NEC subjects with approximately 75% sensitivity and specificity using both complementary spectroscopic techniques. CONCLUSION Biospectroscopy of plasma may provide a rapid, minimally invasive and inexpensive chemical biomarker of idiopathic PD.

Stress Gene Deregulation in Alzheimer Peripheral Blood Mononuclear Cells

Alzheimer’s disease (AD) is a primary degenerative brain disorder that also affects peripheral tissues such as peripheral blood mononuclear cells (PBMC). Several hypotheses for the pathogenesis of AD are intrinsically related to mechanisms of aging and include excitotoxicity, neuroinflammation, mitochondrial dysfunction, and enhanced oxidative stress. Delineation of biochemical alterations in AD blood components may provide insights into the pathogenesis of sporadic AD and facilitate the development of diagnostic and prognostic biomarkers. Here we describe our published experimental approaches and PBMC gene expression data in sporadic AD, with emphasis on the role of altered redox homeostasis in the development of this common affliction.

P1-398: Near-infrared spectrophotometry of blood plasma for diagnosis of sporadic Alzheimer's disease

Background: There are currently no accepted blood-based biomarkers of sporadic AD. Augmented oxidative stress (OS) has been implicated in both neural and peripheral AD tissues. Methods: NIR analysis was conducted on 75 l plasma samples from 19 AD, 27 amnestic mild cognitive impairment (MCI) and 17 normal elderly control (NEC) persons using an optical fiber-coupled, holographic grating-based NIR spectrograph. Results: Five spectral bands associated with heme, R-CH, R-OH, H2O and R-NH functional groups were sensitive to oxidative modification in pre-clinical studies and were pre-selected to develop a logistic regression model for sample classification. This model differentiated AD from NEC samples with a sensitivity of 80% and specificity of 77%. Fifteen and twelve MCI patients were classified with the NEC and AD groups, respectively. The spectra were not influenced by age, gender, exposure to cholinesterase inhibitors or sample storage time. Conclusions: The NIR data further implicate OS in the systemic pathophysiology of sporadic AD. NIR spectrophotometry of plasma differentiates mild (and possibly pre-clinical) sporadic AD from NEC individuals with moderate-high accuracy. The procedure is minimally-invasive, rapid, and relatively-inexpensive. NIR spectrophtometry may fulfil criteria for a useful biological marker of sporadic AD.