Amyloid-β targeting immunisation in aged non-human primate (Microcebus murinus)

Non-human primates have an important translational value given their close phylogenetic relationship to humans. Studies in these animals remain essential for evaluating efficacy and safety of new therapeutic approaches, particularly in aging primates that display Alzheimer's disease (AD) -like pathology. With the objective to improve amyloid-β (Aβ) targeting immunotherapy, we investigated the safety and efficacy of an active immunisation with an Aβ derivative, K6Aβ1-30-NH2, in old non-human primates. Thirty-two aged (4-10 year-old) mouse lemurs were enrolled in the study, and received up to four subcutaneous injections of the vaccine in alum adjuvant or adjuvant alone. Even though antibody titres to Aβ were not high, pathological examination of the mouse lemur brains showed a significant reduction in intraneuronal Aβ that was associated with reduced microgliosis, and the vaccination did not lead to microhemorrhages. Moreover, a subtle cognitive improvement was observed in the vaccinated primates, which was probably linked to Aβ clearance. This Aβ derivative vaccine appeared to be safe as a prophylactic measure based on the brain analyses and because it did not appear to have detrimental effects on the general health of these old animals.

Reg-1α Promotes Differentiation of Cortical Progenitors via Its N-Terminal Active Domain

Reg-1α belongs to the Reg family of small, secreted proteins expressed in both pancreas and nervous system. Reg-1α is composed of two domains, an insoluble C-type lectin domain and a short soluble N-terminal peptide, which is released from the molecule upon proteolytic N-terminal processing, although the biological significance of this proteolysis remains unclear. We have previously shown that binding of Reg-1α to its receptor Extl3 stimulates axonal outgrowth. Reg-1α and Extl3 genes are expressed in the developing cortex but their expression decreases in adulthood, pointing to a possible function of this signaling system at the early developmental stages. Here, we demonstrate that recombinant Reg-1α increases migration and differentiation of cultured embryonic rat telencephalic progenitors via the activation of GSK-3β activity. In vivo overexpression of Reg-1α by in utero electroporation, has a similar effect, favoring premature differentiation of cortical progenitors. Notably, the N-terminal soluble domain, but not the C-type lectin domain, is largely responsible for Reg-1α effects on cortical neuronal differentiation. We thus conclude that Reg-1α via its proteolytically generated N-terminal domain is required for basic development processes.

Linking cognition to age and amyloid-β burden in the brain of a nonhuman primate (Microcebus murinus)

The gray mouse lemur (Microcebus murinus) is a valuable model in research on age-related proteopathies. This nonhuman primate, comparable to humans, naturally develops tau and amyloid-β proteopathies during aging. Whether these are linked to cognitive alterations is unknown. Here, standardized cognitive testing in pairwise discrimination and reversal learning in a sample of 37 aged (>5 years) subjects was combined with tau and amyloid-β histochemistry in individuals that died naturally. Correlation analyses in successfully tested subjects (n = 22) revealed a significant relation between object discrimination learning and age, strongly influenced by outliers, suggesting pathological cases. Where neuroimmunohistochemistry was possible, as subjects deceased, the naturally developed cortical amyloid-β burden was significantly linked to pretraining success (intraneuronal accumulations) and discrimination learning (extracellular deposits), showing that cognitive (pairwise discrimination) performance in old age predicts the natural accumulation of amyloid-β at death. This is the first description of a direct relation between the cortical amyloid-β burden and cognition in a nonhuman primate.

Neuroprotective brain-derived neurotrophic factor signaling in the TAU-P301L tauopathy zebrafish model

Brain-derived neurotrophic factor (BDNF) dysregulations contribute to the neurotoxicity in neurodegenerative pathologies and could be efficiently targeted by therapies. In Alzheimer's disease (AD), although the relationship between BDNF and amyloid load has been extensively studied, how Tau pathology affects BDNF signaling remains unclear. Using the TAU-P301L transgenic zebrafish line, we investigated how early Tau-induced neurotoxicity modifies BDNF signaling. Alterations in BDNF expression levels were observed as early as 48 h post fertilization in TAU-P301L zebrafish embryos while TrkB receptor expression was not affected. Decreasing BDNF expression, using a knockdown strategy in wild-type embryos to mimic Tau-associated decrease, did not modify TrkB expression but promoted neurotoxicity as demonstrated by axonal outgrowth shortening and neuronal cell death. Moreover, the TrkB antagonist ANA-12 reduced the length of axonal projections. Rescue experiments with exogenous BDNF partially corrected neuronal alterations in TAU-P301L by counteracting primary axonal growth impairment but without effect on apoptosis. Importantly, the axonal rescue was proved functionally effective in a behavioral test, at a similar level as obtained with the GSK3β inhibitor LiCl, known to decrease TAU phosphorylation. Finally, treatment with a TrkB agonist, 7,8-dihydroxyflavone, led to comparable results and allowed full rescue of locomotor response. We provided here strong evidence that Tau neurotoxicity provoked alterations in BDNF system and that BDNF pathway might represent an efficient therapeutic target.

Associations between long-term adherence to healthy diet and recurrent depressive symptoms in Whitehall II Study

PURPOSE

We examined whether long-term adherence to three diet quality scores-the Alternative Healthy Eating Index-2010 (AHEI-2010), Dietary Approach to Stop Hypertension (DASH) and  transformed-Mediterranean Diet Score (tMDS), Alternative Healthy Eating Index-2010 (AHEI-2010) and Dietary Approach to Stop Hypertension (DASH) is associated with the risk of recurrent depressive symptoms.

METHODS

Analyses were conducted on a sample of 4949 men and women from the Whitehall II study. Diet scores were calculated using data collected from food frequency questionnaires repeated over 11 years of exposure (1991/1993-2002/2004). Recurrence of depressive symptoms was defined when participants reported at least two episodes of depressive symptoms (assessed by Center for Epidemiologic Studies Depression Scale and use of antidepressants) over the four phases of follow-up (2002/04-2015/16).

RESULTS

After adjustment for potential cofounders, higher scores on AHEI-2010, DASH and tMDS at the end of the exposure period were associated with lower risk of recurrent depressive symptoms over the 13-year follow-up. Repeat measures of dietary history showed that participants who maintained a high AHEI-2010 score over the 11-year exposure period had a 19% (OR 0.81, 95% CI 0.65-1.00) lower odds of recurrent depressive symptoms compared to those who maintained a low AHEI score. Participants whose AHEI-2010 score decreased over time had a 1.34-fold increased odds (95% CI 1.02-1.75) of developing recurrent depressive symptoms compared to those maintaining a high AHEI-2010. No robust associations were observed for long-term tMDS and DASH.

CONCLUSION

Our findings suggest that long-term adherence to healthy diet defined by Alternative Healthy Eating Index-2010 confers protection against recurrent depressive symptoms.

Combining Gene Transfer and Nonhuman Primates to Better Understand and Treat Parkinson's Disease

Parkinson’s disease (PD) is a progressive CNS disorder that is primarily associated with impaired movement. PD develops over decades and is linked to the gradual loss of dopamine delivery to the striatum, via the loss of dopaminergic (DA) neurons in the substantia nigra pars compacta (SNpc). While the administration of L-dopa and deep brain stimulation are potent therapies, their costs, side effects and gradual loss of efficacy underlines the need to develop other approaches. Unfortunately, the lack of pertinent animal models that reproduce DA neuron loss and behavior deficits—in a timeline that mimics PD progression—has hindered the identification of alternative therapies. A complementary approach to transgenic animals is the use of nonhuman primates (NHPs) combined with the overexpression of disease-related genes using viral vectors. This approach may induce phenotypes that are not influenced by developmental compensation mechanisms, and that take into account the personality of animals. In this review article, we discuss the combination of gene transfer and NHPs to develop “genetic” models of PD that are suitable for testing therapeutic approaches.

Association of Long-Term Diet Quality with Hippocampal Volume: Longitudinal Cohort Study

BACKGROUND

Diet quality is associated with brain aging outcomes. However, few studies have explored in humans the brain structures potentially affected by long-term diet quality. We examined whether cumulative average of the Alternative Healthy Eating Index 2010 (AHEI-2010) score during adult life (an 11-year exposure period) is associated with hippocampal volume.

METHODS

Analyses were based on data from 459 participants of the Whitehall II imaging sub-study (mean age [standard deviation] (SD) = 59.6 [5.3] years in 2002-2004, 19.2% women). Multimodal magnetic resonance imaging examination was performed at the end of follow-up (2015-2016). Structural images were acquired using a high-resolution 3-dimensional T1-weighted sequence and processed with Functional Magnetic Resonance Imaging of the Brain Software Library (FSL) tools. An automated model-based segmentation and registration tool was applied to extract hippocampal volumes.

RESULTS

Higher AHEI-2010 cumulative average score (reflecting long-term healthy diet quality) was associated with a larger total hippocampal volume. For each 1 SD (SD = 8.7 points) increment in AHEI-2010 score, an increase of 92.5 mm³ (standard error = 42.0 mm³) in total hippocampal volume was observed. This association was independent of sociodemographic factors, smoking habits, physical activity, cardiometabolic health factors, cognitive impairment, and depressive symptoms, and was more pronounced in the left hippocampus than in the right hippocampus. Of the AHEI-2010 components, no or light alcohol consumption was independently associated with larger hippocampal volume.

CONCLUSIONS

Higher long-term AHEI-2010 scores were associated with larger hippocampal volume. Accounting for the importance of hippocampal structures in several neuropsychiatric diseases, our findings reaffirm the need to consider adherence to healthy dietary recommendation in multi-interventional programs to promote healthy brain aging.

Regenerating islet-derived 1α (REG-1α) protein increases tau phosphorylation in cell and animal models of tauopathies

REG-1α, a secreted protein containing a C-type lectin domain, is expressed in various organs and plays different roles in digestive system cells in physiological and pathological conditions. Like other members of the Reg family, REG-1α is expressed also in the brain where it has different functions. For instance, we previously reported that REG-1α regulates neurite outgrowth and is overexpressed during the very early stages of Alzheimer's disease (AD). However, REG-1α function in neural cells during neural degeneration remains unknown. First, REG-1α and phosphorylated tau expression were assessed in tissue sections from the hippocampus, representing neurofibrillary tangles (NFTs), from patients with AD, and from basal ganglia, representing subcortical NFTs, from patients with progressive supranuclear palsy (PSP). We found an association between REG-1α expression, tau hyperphosphorylation and NFTs in human brain samples from patients with these neurodegenerative diseases. Then, the effects of REG-1α overexpression on tau phosphorylation and axonal morphology were investigated i) in primary cultures of rat neurons that express human tau P301L and ii) in a transgenic zebrafish model of tauopathy that expresses human tau P301L. In the tau P301L cell model, REG-1α overexpression increased tau phosphorylation at the S202/T205 and S396 residues (early and late stages of abnormal phosphorylation, respectively) through the AKT/GSK3-β pathway. This effect was associated with axonal defects both in tau P301L-expressing rat neurons and zebrafish embryos. Our findings suggest a functional role for REG-1α during tauopathy development and progression and, specifically, its involvement in the modification of tau phosphorylation temporal sequence.

Exogenous LRRK2G2019S induces parkinsonian-like pathology in a nonhuman primate

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease among the elderly. To understand its pathogenesis and to test therapies, animal models that faithfully reproduce key pathological PD hallmarks are needed. As a prelude to developing a model of PD, we tested the tropism, efficacy, biodistribution, and transcriptional effect of canine adenovirus type 2 (CAV-2) vectors in the brain of Microcebus murinus, a nonhuman primate that naturally develops neurodegenerative lesions. We show that introducing helper-dependent (HD) CAV-2 vectors results in long-term, neuron-specific expression at the injection site and in afferent nuclei. Although HD CAV-2 vector injection induced a modest transcriptional response, no significant adaptive immune response was generated. We then generated and tested HD CAV-2 vectors expressing leucine-rich repeat kinase 2 (LRRK2) and LRRK2 carrying a G2019S mutation (LRRK2G2019S), which is linked to sporadic and familial autosomal dominant forms of PD. We show that HD-LRRK2G2019S expression induced parkinsonian-like motor symptoms and histological features in less than 4 months.

Nanoparticles as contrast agents for brain nuclear magnetic resonance imaging in Alzheimer's disease diagnosis

Nuclear Magnetic Resonance Imaging (MRI) of amyloid plaques is a powerful non-invasive approach for the early and accurate diagnosis of Alzheimer's disease (AD) along with clinical observations of behavioral changes and cognitive impairment. The present article aims at giving a critical and comprehensive review of recent advances in the development of nanoparticle-based contrast agents for brain MRI. Nanoparticles considered for the MRI of AD must comply with a highly stringent set of requirements including low toxicity and the ability to cross the blood-brain-barrier. In addition, to reach an optimal signal-to-noise ratio, they must exhibit a specific ability to target amyloid plaques, which can be achieved by grafting antibodies, peptides or small molecules. Finally, we propose to consider new directions for the future of MRI in the context of Alzheimer's disease, in particular by enhancing the performances of contrast agents and by including therapeutic functionalities following a theranostic strategy.

Photoperiodic regime influences onset of lens opacities in a non-human primate

Background

Opacities of the lens are typical age-related phenomena which have a high influence on photoreception and consequently circadian rhythm. In mouse lemurs, a small bodied non-human primate, a high incidence (more than 50% when >seven years) of cataracts has been previously described during aging. Previous studies showed that photoperiodically induced accelerated annual rhythms alter some of mouse lemurs’ life history traits. Whether a modification of photoperiod also affects the onset of age dependent lens opacities has not been investigated so far. The aim of this study was therefore to characterise the type of opacity and the mouse lemurs’ age at its onset in two colonies with different photoperiodic regimen.

Methods

Two of the largest mouse lemur colonies in Europe were investigated: Colony 1 having a natural annual photoperiodic regime and Colony 2 with an induced accelerated annual cycle. A slit-lamp was used to determine opacities in the lens. Furthermore, a subset of all animals which showed no opacities in the lens nucleus in the first examination but developed first changes in the following examination were further examined to estimate the age at onset of opacities. In total, 387 animals were examined and 57 represented the subset for age at onset estimation.

Results

The first and most commonly observable opacity in the lens was nuclear sclerosis. Mouse lemurs from Colony 1 showed a delayed onset of nuclear sclerosis compared to mouse lemurs from Colony 2 (4.35 ± 1.50 years vs. 2.75 ± 0.99 years). For colony 1, the chronological age was equivalent to the number of seasonal cycles experienced by the mouse lemurs. For colony 2, in which seasonal cycles were accelerated by a factor of 1.5, mouse lemurs had experienced 4.13 ± 1.50 seasonal cycles in 2.75 ± 0.99 chronological years.

Discussion

Our study showed clear differences in age at the onset of nuclear sclerosis formation between lemurs kept under different photoperiodic regimes. Instead of measuring the chronological age, the number of seasonal cycles (N = four) experienced by a mouse lemur can be used to estimate the risk of beginning nuclear sclerosis formation. Ophthalmological examinations should be taken into account when animals older than 5–6 seasonal cycles are used for experiments in which unrestricted visual ability has to be ensured. This study is the first to assess and demonstrate the influence of annual photoperiod regime on the incidence of lens opacities in a non-human primate.

A Fluorescent Oligothiophene-Bis-Triazine ligand interacts with PrP fibrils and detects SDS-resistant oligomers in human prion diseases

Background

Prion diseases are characterized by the accumulation in the central nervous system of an abnormally folded isoform of the prion protein, named PrP^Sc. Aggregation of PrP^Sc into oligomers and fibrils is critically involved in the pathogenesis of prion diseases. Oligomers are supposed to be the key neurotoxic agents in prion disease, so modulation of prion aggregation pathways with small molecules can be a valuable strategy for studying prion pathogenicity and for developing new diagnostic and therapeutic approaches. We previously identified thienyl pyrimidine compounds that induce SDS-resistant PrP^Sc (rSDS-PrP^Sc) oligomers in prion-infected samples.

Results

Due to the low effective doses of the thienyl pyrimidine hits, we synthesized a quaterthiophene-bis-triazine compound, called MR100 to better evaluate their diagnostic and therapeutic potentials. This molecule exhibits a powerful activity inducing rSDS-PrP^Sc oligomers at nanomolar concentrations in prion-infected cells. Fluorescence interaction studies of MR100 with mouse PrP fibrils showed substantial modification of the spectrum, and the interaction was confirmed in vitro by production of rSDS-oligomer species upon incubation of MR100 with fibrils in SDS-PAGE gel. We further explored whether MR100 compound has a potential to be used in the diagnosis of prion diseases. Our results showed that: (i) MR100 can detect rSDS-oligomers in prion-infected brain homogenates of various species, including human samples from CJD patients; (ii) A protocol, called “Rapid Centrifugation Assay” (RCA), was developed based on MR100 property of inducing rSDS-PrP^Sc oligomers only in prion-infected samples, and avoiding the protease digestion step. RCA allows the detection of both PK-sensitive and PK-resistant PrP^Sc species in rodents samples but also from patients with different CJD forms (sporadic and new variant); (iii) A correlation could be established between the amount of rSDS-PrP^Sc oligomers revealed by MR100 and the duration of the symptomatic phase of the disease in CJD patients; and (iv) Bioassay experiments showed that MR100 can trap prion infectivity more efficiently than P30 drug.

Conclusions

MR100 is a powerful tool not only for studying the prion aggregation pathways regarding oligomeric and sPrP^Sc species, but also for developing alternative methods for the detection of prion-infected samples. Considering our bioassay results, MR100 is a promising molecule for the development of prion decontamination approaches.

Electronic supplementary material

The online version of this article (doi:10.1186/s13024-016-0074-7) contains supplementary material, which is available to authorized users.

Lessons from the analysis of nonhuman primates for understanding human aging and neurodegenerative diseases

Animal models are necessary tools for solving the most serious challenges facing medical research. In aging and neurodegenerative disease studies, rodents occupy a place of choice. However, the most challenging questions about longevity, the complexity and functioning of brain networks or social intelligence can almost only be investigated in nonhuman primates. Beside the fact that their brain structure is much closer to that of humans, they develop highly complex cognitive strategies and they are visually-oriented like humans. For these reasons, they deserve consideration, although their management and care are more complicated and the related costs much higher. Despite these caveats, considerable scientific advances have been possible using nonhuman primates. This review concisely summarizes their role in the study of aging and of the mechanisms involved in neurodegenerative disorders associated mainly with cognitive dysfunctions (Alzheimer's and prion diseases) or motor deficits (Parkinson's and related diseases).

Developmental determinants in non-communicable chronic diseases and ageing

Prenatal and peri-natal events play a fundamental role in health, development of diseases and ageing (Developmental Origins of Health and Disease (DOHaD)). Research on the determinants of active and healthy ageing is a priority to: (i) inform strategies for reducing societal and individual costs of an ageing population and (ii) develop effective novel prevention strategies. It is important to compare the trajectories of respiratory diseases with those of other chronic diseases.

Thienyl pyrimidine derivatives with PrP(Sc) oligomer-inducing activity are a promising tool to study prions

Transmissible spongiform encephalopathies (TSEs), also called prion diseases, are fatal, infectious, genetic or sporadic neurodegenerative disorders of humans and animals. In humans, TSEs are represented by Creutzfeldt-Jakob disease (CJD), Gerstmann-Sträussler-Scheinker syndrome, Fatal Familial Insomnia and Kuru. In animals, the most prominent prion diseases are scrapie of sheep and goats, bovine spongiform encephalopathy (BSE) of cattle and chronic wasting disease (CWD) of deer and elk. A critical event in prion diseases is the accumulation in the central nervous system (CNS) of the abnormally folded PrP(Sc) protein that is the protease-resistant isoform of a normal cellular protein encoded by the host and called PrP(C). PrP(Sc) (also known as rPrP(Sc) or PrP27-30) represents the main marker of prion diseases and is routinely used in the reference method for the diagnosis of prion diseases. Most of the therapeutic strategies developed so far aimed at identifying compounds that diminish the levels of PrP(Sc), with variable success when tested in vivo. In this review, we present an alternative approach in which small molecules that induce PrP(Sc) oligomers are identified. By using virtual and cellular screenings, we found several thienyl pyrimidine compounds that trigger PrP(Sc) oligomerization and trap prion infectivity.

CXCR7 Receptor Controls the Maintenance of Subpial Positioning of Cajal-Retzius Cells

Cajal-Retzius (CR) cells are essential for cortical development and lamination. These pioneer neurons arise from distinct progenitor sources, including the cortical hem and the ventral pallium at pallium-subpallium boundary (PSB). CXCR4, the canonical receptor for the chemokine CXCL12, controls the superficial location of hem-derived CR cells. However, recent studies showed that CXCR7, a second CXCL12 receptor, is also expressed in CR cells at early developmental stages. We thus investigated the role of CXCR7 during CR cell development using multiple loss-of-function approaches. Cxcr7 gene inactivation led to aberrant localization of Reelin-positive cells within the pallium. In addition, Cxcr7(-/-) mice were characterized by significant accumulation of ectopic CR cells in the lateral part of the dorsal pallium compared with Cxcr4 knockout mice. Loss-of-function approaches, using either gene targeting or pharmacological receptor inhibition, reveal that CXCR7 and CXCR4 act both in CR positioning. Finally, conditional Cxcr7 deletion in cells derived from Dbx1-expressing progenitors indicates an essential role of CXCR7 in controlling the positioning of a subpopulation of PSB-derived CR cells. Our data demonstrate that CXCR7 has a role in the positioning of hem and PSB-derived CR cells, CXCL12 regulating CR cell subpial localization through the combined action of CXCR4 and CXCR7.

Corrective GUSB transfer to the canine mucopolysaccharidosis VII cornea using a helper-dependent canine adenovirus vector

Corneal transparency is maintained, in part, by specialized fibroblasts called keratocytes, which reside in the fibrous lamellae of the stroma. Corneal clouding, a condition that impairs visual acuity, is associated with numerous diseases, including mucopolysaccharidosis (MPS) type VII. MPS VII is due to deficiency in β-glucuronidase (β-glu) enzymatic activity, which leads to accumulation of glycosaminoglycans (GAGs), and secondary accumulation of gangliosides. Here, we tested the efficacy of canine adenovirus type 2 (CAV-2) vectors to transduce keratocyte in vivo in mice and nonhuman primates, and ex vivo in dog and human corneal explants. Following efficacy studies, we asked if we could treat corneal clouding by the injection a helper-dependent (HD) CAV-2 vector (HD-RIGIE) harboring the human cDNA coding for β-glu (GUSB) in the canine MPS VII cornea. β-Glu activity, GAG content, and lysosome morphology and physiopathology were analyzed. We found that HD-RIGIE injections efficiently transduced coxsackievirus adenovirus receptor-expressing keratocytes in the four species and, compared to mock-injected controls, improved the pathology in the canine MPS VII cornea. The key criterion to corrective therapy was the steady controlled release of β-glu and its diffusion throughout the collagen-dense stroma. These data support the continued evaluation of HD CAV-2 vectors to treat diseases affecting corneal keratocytes.

Amyloid beta immunization worsens iron deposits in the choroid plexus and cerebral microbleeds

Anti-amyloid beta (Aβ) immunotherapy provides potential benefits in Alzheimer's disease patients. Nevertheless, strategies based on Aβ1-42 peptide induced encephalomyelitis and possible microhemorrhages. These outcomes were not expected from studies performed in rodents. It is critical to determine if other animal models better predict side effects of immunotherapies. Mouse lemur primates can develop amyloidosis with aging. Here we used old lemurs to study immunotherapy based on Aβ1-42 or Aβ-derivative (K6Aβ1-30). We followed anti-Aβ40 immunoglobulin G and M responses and Aβ levels in plasma. In vivo magnetic resonance imaging and histology were used to evaluate amyloidosis, neuroinflammation, vasogenic edema, microhemorrhages, and brain iron deposits. The animals responded mainly to the Aβ1-42 immunogen. This treatment induced immune response and increased Aβ levels in plasma and also microhemorrhages and iron deposits in the choroid plexus. A complementary study of untreated lemurs showed iron accumulation in the choroid plexus with normal aging. Worsening of iron accumulation is thus a potential side effect of Aβ-immunization at prodromal stages of Alzheimer's disease, and should be monitored in clinical trials.

Increased amyloid-β peptide-induced memory deficits in phospholipid transfer protein (PLTP) gene knockout mice

Oxidative stress is recognized as one of the earliest and most intense pathological processes in Alzheimer's disease (AD), and the antioxidant vitamin E has been shown to efficiently prevent amyloid plaque formation and neurodegeneration. Plasma phospholipid transfer protein (PLTP) has a major role in vitamin E transfers in vivo, and PLTP deficiency in mice is associated with reduced brain vitamin E levels. To determine the impact of PLTP on amyloid pathology in vivo, we analyzed the vulnerability of PLTP-deficient (PLTP-KO) mice to the toxic effects induced by intracerebroventricular injection of oligomeric amyloid-β 25-35 (Aβ 25-35) peptide, a non-transgenic model of AD. Under basal conditions, PLTP-KO mice showed increased cerebral oxidative stress, increased brain Aβ 1-42 levels, and a lower expression of the synaptic function marker synaptophysin, as compared with wild-type mice. This PLTP-KO phenotype was associated with increased memory impairment 1 week after Aβ25-35 peptide injection. Restoration of brain vitamin E levels in PLTP-KO mice through a chronic dietary supplementation prevented Aβ 25-35-induced memory deficits and reduced cerebral oxidative stress and toxicity. We conclude that PLTP, through its ability to deliver vitamin E to the brain, constitutes an endogenous neuroprotective agent. Increasing PLTP activity may offer a new way to develop neuroprotective therapies.

Oral transmission of L-type bovine spongiform encephalopathy in primate model

We report transmission of atypical L-type bovine spongiform encephalopathy to mouse lemurs after oral or intracerebral inoculation with infected bovine brain tissue. After neurologic symptoms appeared, transmissibility of the disease by both inoculation routes was confirmed by detection of disease-associated prion protein in samples of brain tissue.

[The diversity of aging models]

Most of the signalling pathways involved in aging regulation have been recently found well conserved at various levels throughout the evolution. Taking this into account, a diversity of model organisms, including worms, rodents, and lemurs as well, allows to address different questions: how to understand the interactions between genetic and environmental factors while challenging theories of aging, to preserve hearing integrity, to fight against senescence of neural stem cells, or to explore brain fitness from gene expression to cognitive and social behavior? Here are the main issues that can be considered, stressing the complementarities of the models. The differentiation of aging physiological aspects from those induced by age-related pathologies will also be specified. By emphasizing recent ability of technologies to promote new aging insights, we discuss towards a better understanding of mechanisms governing aging.

Regenerating islet-derived 1α (Reg-1α) protein is new neuronal secreted factor that stimulates neurite outgrowth via exostosin Tumor-like 3 (EXTL3) receptor

Regenerating islet-derived 1α (Reg-1α)/lithostathine, a member of a family of secreted proteins containing a C-type lectin domain, is expressed in various organs and plays a role in proliferation, differentiation, inflammation, and carcinogenesis of cells of the digestive system. We previously reported that Reg-1α is overexpressed during the very early stages of Alzheimer disease, and Reg-1α deposits were detected in the brain of patients with Alzheimer disease. However, the physiological function of Reg-1α in neural cells remains unknown. Here, we show that Reg-1α is expressed in neuronal cell lines (PC12 and Neuro-2a) and in rat primary hippocampal neurons (E17.5). Reg-1α is mainly localized around the nucleus and at the membrane of cell bodies and neurites. Transient overexpression of Reg-1α or addition of recombinant Reg-1α significantly increases the number of cells with longer neurites by stimulating neurite outgrowth. These effects are abolished upon down-regulation of Reg-1α by siRNA and following inhibition of secreted Reg-1α by antibodies. Moreover, Reg-1α colocalizes with exostosin tumor-like 3 (EXTL3), its putative receptor, at the membrane of these cells. Overexpression of EXTL3 increases the effect of recombinant Reg-1α on neurite outgrowth, and Reg-1α is not effective when EXTL3 overexpression is down-regulated by shRNA. Our findings indicate that Reg-1α regulates neurite outgrowth and suggest that this effect is mediated by its receptor EXTL3.

Distinct transcriptome expression of the temporal cortex of the primate Microcebus murinus during brain aging versus Alzheimer's disease-like pathology

Aging is the primary risk factor of neurodegenerative disorders such as Alzheimer's disease (AD). However, the molecular events occurring during brain aging are extremely complex and still largely unknown. For a better understanding of these age-associated modifications, animal models as close as possible to humans are needed. We thus analyzed the transcriptome of the temporal cortex of the primate Microcebus murinus using human oligonucleotide microarrays (Affymetrix). Gene expression profiles were assessed in the temporal cortex of 6 young adults, 10 healthy old animals and 2 old, “AD-like” animals that presented ß-amyloid plaques and cortical atrophy, which are pathognomonic signs of AD in humans. Gene expression data of the 14,911 genes that were detected in at least 3 samples were analyzed. By SAM (significance analysis of microarrays), we identified 47 genes that discriminated young from healthy old and “AD-like” animals. These findings were confirmed by principal component analysis (PCA). ANOVA of the expression data from the three groups identified 695 genes (including the 47 genes previously identified by SAM and PCA) with significant changes of expression in old and “AD-like” in comparison to young animals. About one third of these genes showed similar changes of expression in healthy aging and in “AD-like” animals, whereas more than two thirds showed opposite changes in these two groups in comparison to young animals. Hierarchical clustering analysis of the 695 markers indicated that each group had distinct expression profiles which characterized each group, especially the “AD-like” group. Functional categorization showed that most of the genes that were up-regulated in healthy old animals and down-regulated in “AD-like” animals belonged to metabolic pathways, particularly protein synthesis. These data suggest the existence of compensatory mechanisms during physiological brain aging that disappear in “AD-like” animals. These results open the way to new exploration of physiological and “AD-like” aging in primates.

The three-panel runway maze adapted to Microcebus murinus reveals age-related differences in memory and perseverance performances

Microcebus murinus, a mouse lemur primate appears to be a valuable model for cerebral aging study and for Alzheimer's disease model since they can develop beta-amyloid plaques with age. Although the biological and biochemical analyses of cerebral aging are well documented, the cognitive abilities of this primate have not been thoroughly characterized. In this study, we adapted a spatial working memory procedure described in rodents, the sequential choice task in the three-panel runway, to mouse lemurs. We analyzed the age-related differences in a procedural memory task in the absence or presence of visual cues. Sixty percent of young adult and 48% of aged lemurs completed the exploratory, choice habituation and testing phases at the beginning of the procedure. Young adult lemurs showed a higher level of perseverative errors compared with aged animals, particularly in the presence of visual stimuli. Over trials, old animals made more reference errors compared to young ones that improved quickly their performances under random level. No significant improvement was observed in young adults and old ones over sessions. This study showed that behavioural performances of M. murinus assessed on the sequential choice task in the three-panel runway markedly differ from the previously reported abilities of rodents. The behavioural response of young adult lemurs was influenced by novelty-related anxiety that contributed to their performance in terms of perseverative errors. Conversely, aged lemurs showed less perseverative errors, a rapid habituation to the three-panel runway maze, but made more memory errors. Overall, these findings demonstrate the feasibility to use the three-panel runway task in assessing memory performance, particularly in aged mouse lemurs.

Discovering novelty in sequential patterns: application for analysis of microarray data on Alzheimer disease

Analyzing microarrays data is still a great challenge since existing methods produce huge amounts of useless results. We propose a new method called NoDisco for discovering novelties in gene sequences obtained by applying data-mining techniques to microarray data.

METHOD

We identify popular genes, which are often cited in the literature, and innovative genes, which are linked to the popular genes in the sequences but are not mentioned in the literature. We also identify popular and innovative sequences containing these genes. Biologists can thus select interesting sequences from the two sets and obtain the k-best documents.

RESULTS

We show the efficiency of this method by applying it on real data used to decipher the mechanisms underlying Alzheimer disease.

CONCLUSION

The first selection of sequences based on popularity and innovation help experts focus on relevant sequences while the top-k documents help them understand the sequences.

Artificial neural networks for assessing the risk factors for urinary calcium stones according to gender and family history of stone

OBJECTIVE

In a previous work, we evidenced that artificial neural networks (ANNs) were more informative than classical statistical analyses for assessing the risk of idiopathic calcium nephrolithiasis in male stone-formers.

MATERIAL AND METHODS

We compared risk factors for idiopathic calcium nephrolithiasis (age, body mass index, calcemia, calcium oxalate supersaturation, and 24-h calciuria, oxaluria, uricosuria, citraturia, urea, and sodium) in four populations: men and women with and without a family history of stone (FHS). A total of 119 males (58 with an FHS, 61 without) and 59 females (30 with an FHS, 29 without) were compared to healthy controls. For each variable, receiver operating characteristic (ROC) curve indices were calculated by means of ANNs.

RESULTS

In men without an FHS, the most discriminant variables were 24-h urea (ROC curve index 0.76), supersaturation (ROC curve index 0.72), 24-h calciuria (ROC curve index 0.68), 24-h uricosuria (ROC curve index 0.64), 24-h oxaluria (ROC curve index 0.63), 24-h sodium (ROC curve index 0.62), and calcemia (ROC curve index 0.60). In men with an FHS, only supersaturation (ROC curve index 0.67) was discriminant. In women without FHS, calcemia (ROC curve index 0.67), 24-h calciuria (ROC curve index 0.64), and 24-h uricosuria (ROC curve index 0.62) were discriminant. In women with an FHS, supersaturation (ROC curve index 0.70), 24-h uricosuria (ROC curve index 0.69), 24-h urea (ROC curve index 0.68), and 24-h calciuria (ROC curve index 0.67) were discriminant.

CONCLUSIONS

Risk factors for idiopathic calcium nephrolithiasis were roughly the same in men with or without an FHS, and in women with an FHS. In these patients, calcium oxalate supersaturation and 24-h urea were the most discriminant factors. Conversely, in women without an FHS, calcium abnormalities (calcemia, 24-h calciuria) were discriminant and should prompt a search for infraclinical primary hyperparathyroidism or sarcoidosis.

GeneMining: identification, visualization, and interpretation of brain ageing signatures

Transcriptomic technologies are promising tools for identifying new genes involved in cerebral ageing or in neurodegenerative diseases such as Alzheimer's disease. These technologies produce massive biological data, which so far are extremely difficult to exploit. In this context, we propose GeneMining, a multidisciplinary methodology, which aims at developing new strategies to analyse such data, and to design interactive tools to help biologists to identify, visualize and interpret brain ageing signatures. In order to address the specific problem of brain ageing signatures discovery, we combine and apply existing tools with emphasis to a new efficient data mining method based on sequential patterns.

Antibody response and plasma Abeta1-40 levels in young Microcebus murinus primates immunized with Abeta1-42 and its derivatives

We have been developing Abeta derivative vaccines with the objective to improve the safety of Abeta targeting immunotherapy. Our Abeta homologs are designed to have less direct toxicity and to produce a modified immune response compared to Abeta. In extensive mouse studies, all our vaccines have improved cognition in transgenic mice while eliciting different immune responses and reducing brain amyloid burden to a variable degree. While we are continuing to characterize these vaccines in mice, in preparation for studies in old primates and for human trials we assessed their effect in young lemur primates (n=25) that with age develop Abeta plaques and tau aggregates as seen in Alzheimer's disease. In the primates, all the peptides administered with alum adjuvant elicited a moderate to robust anti-Abeta IgM response. Abeta1-42, K6Abeta1-30 and K6Abeta1-30[E(18)E(19)] resulted in a high anti-Abeta IgG response, whereas Abeta1-30[E(18)E(19)] produced a weaker more variable IgG titer. Notably, 22 weeks after the 3rd immunization, IgM and IgG levels in derivative-vaccinated primates were similar to preimmune values whereas Abeta1-42 treated primates maintained a moderate IgG titer. The increase in antibodies that recognized Abeta1-40 often correlated with increase in Abeta1-40 in plasma, which suggests that the antibodies were binding to Abeta in vivo. Interestingly, significant transient weight gain was observed (K6Abeta1-30-, Abeta1-30[E(18)E(19)]- and Abeta1-42-treated) or a trend in the same direction (K6Abeta1-30[E(18)E(19)]-treated, adjuvant controls) following the injections. Based on these findings, we have chosen K6Abeta1-30 for immunizations in old primates as the antibody response to this vaccine was less variable compared to other Abeta derivatives. Our present findings indicate that most of our Abeta derivatives elicit a substantial antibody response in primates, and importantly this effect is reversible which enhances the safety profile of our approach.

Effective gene therapy in a mouse model of prion diseases

Classical drug therapies against prion diseases have encountered serious difficulties. It has become urgent to develop radically different therapeutic strategies. Previously, we showed that VSV-G pseudotyped FIV derived vectors carrying dominant negative mutants of the PrP gene are efficient to inhibit prion replication in chronically prion-infected cells. Besides, they can transduce neurons and cells of the lymphoreticular system, highlighting their potential use in gene therapy approaches. Here, we used lentiviral gene transfer to deliver PrPQ167R virions possessing anti-prion properties to analyse their efficiency in vivo. Since treatment for prion diseases is initiated belatedly in human patients, we focused on the development of a curative therapeutic protocol targeting the late stage of the disease, either at 35 or 105 days post-infection (d.p.i.) with prions. We observed a prolongation in the lifespan of the treated mice that prompted us to develop a system of cannula implantation into the brain of prion-infected mice. Chronic injections of PrPQ167R virions were done at 80 and 95 d.p.i. After only two injections, survival of the treated mice was extended by 30 days (20%), accompanied by substantial improvement in behaviour. This delay was correlated with: (i) a strong reduction of spongiosis in the ipsilateral side of the brain by comparison with the contralateral side; and (ii) a remarkable decrease in astrocytic gliosis in the whole brain. These results suggest that chronic injections of dominant negative lentiviral vectors into the brain, may be a promising approach for a curative treatment of prion diseases.

Artificial neural networks for assessing the risk of urinary calcium stone among men

The pathophysiology of idiopathic calcium oxalate nephrolithiasis involves metabolic abnormalities. Previous studies gave conflicting results about the metabolic factors in stone formers. Artificial neural networks (ANN) are new methods based on computer programming that have outperformed conventional methods in prediction of outcomes in different medical applications. The aim of our study was to compare with ANN the clinical and biochemical parameters implicated in urinary calcium stone between stone formers (SF) and controls (C). We compared 11 clinical and biochemical variables among 119 male idiopathic calcium oxalate SF and 96 C by univariate and multivariate statistical analyses. Univariate analyses included discriminant analysis, logistic regression analysis, and ANN. For multivariate analyses, stepwise discriminant analysis and ANN were performed. Variables included age, body mass index (BMI), family history of nephrolithiasis, supersaturation with respect to calcium oxalate, calcemia, and 24-h urinary calcium, oxalate, uric acid, urea, sodium, and citrate. With univariate and multivariate analyses, ANN were as efficient as classical statistical analyses in discriminating the different parameters. The sensitivity, the specificity, and the percentage of correctly classified patients were similar in all analyses. With ANN, supersaturation (receiver operating characteristic, ROC curves index 0.73) and urea (ROC 0.72) were the most discriminant followed by family history and urinary calcium (ROC 0.67). ROC index was 0.63 for citrate, 0.61 for oxalate and urate, 0.60 for sodium and calcemia, 0.58 for age, and 0.56 for BMI, but these parameters were not statistically different between SF and C. ANN gave additional information since they made it possible to determine the cut-off values of the parameters and their predictive power. Cut-off values for being a stone former were 8.9 for supersaturation and 363 mmol/day for urinary urea with a predictive power of 0.69 and 0.70, respectively. Univariate and multivariate analysis evidenced supersaturation and 24-h urinary urea excretion as the most discriminant parameters between the two populations. In addition to high supersaturation, the negative impact of protein intake was confirmed.

Age effect on olfactory discrimination in a non-human primate, Microcebus murinus

In order to characterize age-related cognitive changes, olfactory discrimination was assessed in Microcebus murinus, a prosimian primate. We compared young (n = 10) and old (n = 8) animals for individual performance on three olfactory tasks. Animals had to perform a detection, a transfer, and a reversal learning task using a go, no go conditioning procedure. No differences were observed between the two groups, indicating that aging is not inevitably associated with a decline in cognitive function. We did, however, observe two aged animals showing altered behavior. One animal displayed impairments in the reversal learning task, and the other showed impairments in both the transfer and reversal tasks. Transfer impairment may be due to a hippocampal alteration, whereas the perseverative tendency noted in the reversal task may be associated with frontal lobe dysfunction. Because some aged M. murinus display lesions that are pathognomonic of Alzheimer's disease, our observations highlight its potential utility as a primate model for studying cognitive deficits in relation to age and associated pathologies.

PAP IB, a new member of the Reg gene family: cloning, expression, structural properties, and evolution by gene duplication

Reg proteins are expressed in various organs and are involved in cancers and neurodegenerative diseases. They display a typical C-type lectin-like domain but possess additional highly conserved amino acids. By studying human databases and Expressed Sequence Tags library, we identified a new member called PAP IB. Using probabilistic approaches, we established a phylogenetic tree of eighteen Reg proteins. The dendogram showed that they constitute a superfamily composed of three distinct families (FI to FIII) of paralogues that resulted from duplication. We therefore focused on two proteins, REG Ialpha and PAP IB, belonging to the more closely related FI and FII families, respectively. REG Ialpha and PAP IB share 50% sequence identity. After cloning PAP IB, however, we found that it was expressed almost only in pancreas, unlike REG Ialpha, whose expression is ubiquitous. In addition, by building a model of the structure of PAP IB based on the X-ray structure of REG Ialpha, we observed that the two proteins displayed distinctive surface charge distribution, which may lead to different ligands binding. In spite of their common fold that should result in closely related functions, REG Ialpha and PAP IB are a good example of duplication and divergence, probably with the acquisition of new functions, thus participating in the evolution of the protein repertoire.

Odor discrimination assessment with an automated olfactometric method in a prosimian primate, Microcebus murinus

The present study was aimed at adapting an automated olfactometer designed for use with rodents to a nocturnal lemur Microcebus murinus. This apparatus allows rigorous control of odor stimuli. We show that M. murinus could remain quiet and attentive for about 20 min in the test chamber, allowing daily sessions of 40 consecutive trials. This allowed us to train M. murinus subjects to learn a go/no-go discrimination procedure using fruity-odor cues. Each of seven subjects reached or exceeded a criterion of 33 correct responses in a block of 40 trials in a range of 4-14 training sessions. When trained on an odor reversal task, performance initially dropped sharply, followed by rapid acquisition of the new task. These outcomes demonstrate that, like rodents, M. murinus can be trained using operant conditioning in an automated olfactometer. This species should prove useful for investigating cognitive capacities and neurodegenerative disease in a primitive primate model.

Lithostathine quadruple-helical filaments form proteinase K-resistant deposits in Creutzfeldt-Jakob disease

Autocatalytic cleavage of lithostathine leads to the formation of quadruple-helical fibrils (QHF-litho) that are present in Alzheimer's disease. Here we show that such fibrils also occur in Creutzfeldt-Jakob and Gerstmann-Sträussler-Scheinker diseases, where they form protease-K-resistant deposits and co-localize with amyloid plaques formed from prion protein. Lithostathine does not appear to change its native-like, globular structure during fibril formation. However, we obtained evidence that a cluster of six conserved tryptophans, positioned around a surface loop, could act as a mobile structural element that can be swapped between adjacent protein molecules, thereby enabling the formation of higher order fibril bundles. Despite their association with these clinical amyloid deposits, QHF-litho differ from typical amyloid fibrils in several ways, for example they produce a different infrared spectrum and cannot bind Congo Red, suggesting that they may not represent amyloid structures themselves. Instead, we suggest that lithostathine constitutes a novel component decorating disease-associated amyloid fibrils. Interestingly, [6,6']bibenzothiazolyl-2,2'-diamine, an agent found previously to disrupt aggregates of huntingtin associated with Huntington's disease, can dissociate lithostathine bundles into individual protofilaments. Disrupting QHF-litho fibrils could therefore represent a novel therapeutic strategy to combat clinical amyloidoses.

Specific binding of dehydroepiandrosterone to the N terminus of the microtubule-associated protein MAP2

The effect of neurosteroids is mediated through their membrane or nuclear receptors. However, no dehydroepiandrosterone (DHEA)-specific receptors have been evidenced so far in the brain. In this paper, we showed by isothermal titration calorimetry that the DHEA specifically binds to the dendritic brain microtubule-associated protein MAP2C with an association constant of 2.7 x 10(7) m-1 and at a molar ratio of 1:1. By partial tryptic digestions and mass spectrometry analysis, we found that the binding involved the N-terminal region of MAP2C. Interestingly, MAP2C displays homologies with 17 beta-hydroxysteroid dehydrogenase 1, an enzyme required for estrogen synthesis. Based on these sequence homologies and on the x-ray structure of the DHEA-binding pocket of 17 beta-hydroxysteroid dehydrogenase 1, we modeled the complex of DHEA with MAP2C. The binding of DHEA to MAP2C involved specific hydrogen bonds that orient the steroid into the pocket. This work suggests that DHEA can directly influence brain plasticity via MAP2C binding. It opens interesting ways for understanding the role of DHEA in the brain.

Optimized overproduction, purification, characterization and high-pressure sensitivity of the prion protein in the native (PrP(C)-like) or amyloid (PrP(Sc)-like) conformation

Overproduction and purification of the prion protein is a major concern for biological or biophysical analysis as are the structural specificities of this protein in relation to infectivity. We have developed a method for the effective cloning, overexpression in Escherichia coli and purification to homogeneity of Syrian golden hamster prion protein (SHaPrP(90-231)). A high level of overexpression, resulting in the formation of inclusion bodies, was obtained under the control of the T7-inducible promoter of the pET15b plasmid. The protein required denaturation, reduction and refolding steps to become soluble and attain its native conformation. Purification was carried out by differential centrifugation, gel filtration and reverse phase chromatography. An improved cysteine oxidation protocol using oxidized glutathione under denaturing conditions, resulted in the recovery of a higher yield of chromatographically pure protein. About 10 mg of PrP protein per liter of bacterial culture was obtained. The recombinant protein was identified by monoclonal antibodies and its integrity was confirmed by electrospray mass spectrometry (ES/MS), whereas correct folding was assessed by circular dichroism (CD) spectroscopy. This protein had the structural characteristics of PrP(C) and could be converted to an amyloid structure sharing biophysical and biochemical properties of the pathologic form (PrP(Sc)). The sensitivity of these two forms to high pressure was investigated. We demonstrate the potential of using pressure as a thermodynamic parameter to rescue trapped aggregated prion conformations into a soluble state, and to explore new conformational coordinates of the prion protein conformational landscape.

Optimized preparation of urine samples for two-dimensional electrophoresis and initial application to patient samples

OBJECTIVE

We optimized of the preparation of urinary samples to obtain a comprehensive map of urinary proteins of healthy subjects and then compared this map with the ones obtained with patient samples to show that the pattern was specific of their kidney disease.

DESIGN AND METHODS

The urinary protein excretion patterns of 49 healthy men and 4 patients with renal disease were obtained by 2D electrophoresis. Silver nitrate stained protein spots were identified by mass spectrometry.

RESULTS

Reproductive 2D gels identified 5 classes of proteins systematically found in healthy subjects, irrespective of age. The proteins evidenced included serum albumin and its specific proteolytic products, Tamm-Horsfall, transferrin, zinc-alpha2-glycoprotein, alpha1-microglobulin, haptoglobin, and Ig light chains.

CONCLUSIONS

This study of a large panel of healthy individual showed that 2D urinary pattern was constant over time and reveal for the first time the relative abundance of albumin fragments in healthy subjects' urine. The profiles of the 4 patients, were specific of their renal disease.

[Anti-TNF alpha monoclonal antibodies (infliximab) and tuberculosis: apropos of 3 cases]

INTRODUCTION

Monoclonal TNF alpha antibodies are a new treatment of severe rheumatoid arthritis. One of the possible side effects is the appearance of opportunistic infections. We report here on three cases of disseminated tuberculosis observed in patients undergoing treatment with infliximab.

EXEGESIS

A 45-year-old woman, treated with infliximab, was hospitalised after five infusions for fever and dyspnoea. The exams showed pulmonary and peritoneal tuberculosis. The second case is a 75-year-old woman whose symptoms were fever, cough and cervical adenopathy after three infliximab infusions. Diagnosis was disseminated tuberculosis. The third case is a 59-year-old man who was hospitalised for an infectious syndrome with dyspnoea, after two infliximab infusions. We discovered pulmonary tuberculosis.

CONCLUSION

These three cases added to the 68 cases of tuberculosis registered with the treatment of infliximab. This confirms the risk of severe opportunist infectious side effects. TNF alpha is a cytokine which has anti-infectious properties. These tuberculoses are severe and generalized. It is recommended to search for an active or latent tuberculosis before beginning treatment with infliximab, and to check these patients frequently.

[Long-term treatment of Alzheimer's disease: followup of a cohort of 255 patients treated with lacrine for four years]

We describe the follow-up of a cohort of 255 Alzheimer's disease (AD) patients (81 males, 174 females) treated by tacrine during 4 years. We performed the survey of hepatic, cholinergic and general tolérance. Drug efficacy was measured by MMS examination on weeks 0, 18, 30, 52, 104, 156 and 208. A total of 190 patients (74.5 percent) were dropped out of this study, 75 (29 percent) for adverse events. We found 85 hepatic (33 percent), 79 cholinergic (31 percent), 31 (12 percent) neuropsychiatric and 72 general (28 percent) side effects. In term of drug efficacy we observed a global decline of 2.5 MMS points during the first year and 2 MMS points between W52 and W156. Tacrine's symptomatic efficacy, defined as the number of patients improved or stabilized at W30, was present in 50 patients (46 percent) among the 109 patients reaching W30. The intensity of symptomatic efficacy was expressed by a 2.7 MMS points increase in 37 patients improved on W30. The long term effects of Tacrine, measured by the MMS score at one year, showed a positive impact as the MMS was 2.5 points above the expected score in non treated AD patients. This study raises the practical problem of optimal cholinesterase inhibitors use in AD and the theoretical question of long term action of cholinesterase inhibitors on cerebral lesions of AD.

Three-dimensional structure of the lithostathine protofibril, a protein involved in Alzheimer's disease

Neurodegenerative diseases are characterized by the presence of filamentous aggregates of proteins. We previously established that lithostathine is a protein overexpressed in the pre-clinical stages of Alzheimer's disease. Furthermore, it is present in the pathognomonic lesions associated with Alzheimer's disease. After self-proteolysis, the N-terminally truncated form of lithostathine leads to the formation of fibrillar aggregates. Here we observed using atomic force microscopy that these aggregates consisted of a network of protofibrils, each of which had a twisted appearance. Electron microscopy and image analysis showed that this twisted protofibril has a quadruple helical structure. Three-dimensional X-ray structural data and the results of biochemical experiments showed that when forming a protofibril, lithostathine was first assembled via lateral hydrophobic interactions into a tetramer. Each tetramer then linked up with another tetramer as the result of longitudinal electrostatic interactions. All these results were used to build a structural model for the lithostathine protofibril called the quadruple-helical filament (QHF-litho). In conclusion, lithostathine strongly resembles the prion protein in its dramatic proteolysis and amyloid proteins in its ability to form fibrils.

Lithostathine and pancreatitis-associated protein are involved in the very early stages of Alzheimer's disease

According to one of the theories formulated to explain the etiology of Alzheimer's disease (AD), amylosis may reflect a specific inflammatory response. Two inflammatory proteins, lithostathine and PAP, were evidenced by immunohistochemistry in senile plaques and neurofibrillary tangles of patients with AD. In addition, lithostathine and PAP were significantly increased in the cerebrospinal fluid of patients with AD when compared to patients with multiple sclerosis, another inflammatory disease, and to normal control subjects. However, no correlation was observed with age of occurrence. Furthermore, lithostathine and PAP were increased even at the very early stages of AD, and their level remained elevated during the course of the AD unlike TNFalpha whose level, very high at very early stages, regularly decreased. Finally, if part of lithostathine and PAP are synthesized in the brain, a large part comes from serum by passage over the blood-brain barrier. These results indicate (i) the existence of an acute phase response followed by a chronic inflammation in AD, and (ii) that lithostathine and PAP are involved even at the first pre-clinical biochemical events of AD. In addition, because lithostathine undergoes an autolytic cleavage leading to its precipitation and the formation of fibrils, we believe that it may be involved in amyloidosis and tangles by allowing heterogeneous precipitation of other proteins.

Association of APOE promoter but not A2M polymorphisms with risk of developing Alzheimer's disease

The APOE4 allele is widely accepted as a major risk factor for late-onset Alzheimer's disease (AD). Recently, it has been reported that polymorphisms in the APOE promoter and in the alpha2-macroglobulin gene (A2M) are associated with AD. We have analyzed the distribution of APOE alleles, -219T/G APOE promoter polymorphism, and A2M/A2Mdel polymorphism in a large case-control study. Our results showed that APOE genotype was the only informative marker of AD risk contrary to -219T/G and A2M/A2Mdel polymorphism. In AD patients however, a strong linkage disequilibrium was observed between the T allele of -219T/G polymorphism and APOE4 allele. This result indicates that -219T/G APOE promoter polymorphism is a risk factor for AD by increasing the APOE4-associated risk.

Mechanism of calcite crystal growth inhibition by the N-terminal undecapeptide of lithostathine

Pancreatic juice is supersaturated with calcium carbonate. Calcite crystals therefore may occur, obstruct pancreatic ducts, and finally cause a lithiasis. Human lithostathine, a protein synthesized by the pancreas, inhibits the growth of calcite crystals by inducing a habit modification: the rhombohedral (10 14) usual habit is transformed into a needle-like habit through the (11 0) crystal form. A similar observation was made with the N-terminal undecapeptide (pE(1)R(11)) of lithostathine. We therefore aimed at discovering how peptides inhibit calcium salt crystal growth. We solved the complete x-ray structure of lithostathine, including the flexible N-terminal domain, at 1.3 A. Docking studies of pE(1)R(11) with the (10 14) and (11 0) faces through molecular dynamics simulation resulted in three successive steps. First, the undecapeptide progressively unfolded as it approached the calcite surface. Second, mobile lateral chains of amino acids made hydrogen bonds with the calcite surface. Last, electrostatic bonds between calcium ions and peptide bonds stabilized and anchored pE(1)R(11) on the crystal surface. pE(1)R(11)-calcite interaction was stronger with the (11 0) face than with the (10 14) face, confirming earlier experimental observations. Energy contributions showed that the peptide backbone governed the binding more than did the lateral chains. The ability of peptides to inhibit crystal growth is therefore essentially based on backbone flexibility.