Age-dependent decline of copper clearance at the blood-cerebrospinal fluid barrier.

The homeostasis of copper (Cu) in the central nervous system is regulated by the blood-brain barrier and blood-cerebrospinal (CSF) barrier (BCB) in the choroid plexus. While proteins responsible for Cu uptake, release, storage and intracellular trafficking exist in the choroid plexus, the influence of age on Cu clearance from the CSF via the choroid plexus and how Cu transporting proteins contribute to the process are unelucidated. This study was designed to test the hypothesis that the aging process diminishes Cu clearance from the CSF of rats by disrupting Cu transporting proteins in the choroid plexus. Data from ventriculo-cisternal perfusion experiments demonstrated greater 64Cu radioactivity in the CSF effluents of older rats (18 months) compared to younger (1 month) and adult (2 months) rats, suggesting much slower removal of Cu by the choroid plexus in old animals. Studies utilizing qPCR and immunofluorescence revealed an age-specific expression pattern of Cu transporting proteins in the choroid plexus. Moreover, proteomic analyses unraveled age-specific proteomes in the choroid plexus with distinct pathway differences, particularly associated with extracellular matrix and neurodevelopment between young and old animals. Taken together, these findings support an age-dependent deterioration in CSF Cu clearance, which appears to be associated with altered subcellular distribution of Cu transporting proteins and proteomes in the choroid plexus.

Cerebrospinal Fluid Metals and the Association with Cerebral Small Vessel Disease.

BACKGROUND: Brain metal homeostasis is essential for brain health, and deregulation can result in oxidative stress on the brain parenchyma. OBJECTIVE: Our objective in this study was to focus on two hemorrhagic MRI manifestations of small vessel disease [cerebral microbleeds (CMBs) and cortical superficial siderosis (cSS)] and associations with cerebrospinal fluid (CSF) iron levels. In addition, we aimed to analyze CSF biomarkers for dementia and associations with CSF metal levels. METHODS: This is a cross-sectional study of 196 patients who underwent memory clinic investigation, including brain MRI. CSF was collected and analyzed for metals, amyloid-ß (Aß) 42, total tau (T-tau), and phosphorylated tau (P-tau), and CSF/serum albumin ratios. Statistical analyses were performed using generalized linear models. RESULTS: No significant difference was found between CSF metal levels across diagnostic groups. Higher iron and copper levels were associated with higher CSF levels of Aß42, T-tau, P-tau, and CSF/serum albumin ratios (p < 0.05). Zinc was associated with higher CSF/serum albumin ratios. There was no significant association between CMBs or cSS and CSF iron levels. An increase in CSF iron with the number of CMBs was seen in APOEɛ4 carriers. CONCLUSION: CSF iron levels are elevated with cerebral microbleeds in APOEɛ4 carriers, with no other association seen with hemorrhagic markers of small vessel disease. The association of elevated CSF iron and copper with tau could represent findings of increased neurodegeneration in these patients.

Copper and ceruloplasmin dyshomeostasis in serum and cerebrospinal fluid of multiple sclerosis subjects.

Although many studies have been carried out in order to understand the implication of copper (Cu) in the pathogenesis of multiple sclerosis (MS), the exact role that this metal plays in the disease is not still clear. Because of the lack of information in this subject, the present study compared the serum and cerebrospinal (CSF) levels of copper in MS patients in respect to a control group, matched for age and sex, finding a significant increase of metal concentrations, in both biological fluids of MS subjects. To confirm the possible impairment of Cu metabolism, we analyzed ceruloplasmin (Cp) level and activity, seeing as this protein is an established peripheral marker in diseases associated with Cu imbalance. By comparing these two parameters between control and MS subjects, we found an increase of Cp levels, associated with a decrease in Cp activity, in the second group. By analysing these data, free copper levels were calculated, significantly increased in serum of MS subjects; the increase in free copper could be one of the predisposing factors responsible for the Cu altered levels in CSF of MS patients. At the same time, this alteration could be attributable to the inability to incorporate Cu by Cp, probably due to the high oxidative environment found in serum of MS patients. Overall, all these copper alterations may play a role in MS pathogenesis.

Species fractionation in a case-control study concerning Parkinson's disease: Cu-amino acids discriminate CSF of PD from controls.

BACKGROUND: Parkinson's disease is affecting about 1% of the population above 65 years. Improvements in medicine support prolonged lifetime which increases the total concentration of humans affected by the disease. It is suggested that occupational and environmental exposure to metals like iron (Fe), manganese (Mn), copper (Cu) and zinc (Zn) can influence the risk for Parkinson's disease. These metals play a key role as cofactors in many enzymes and proteins. METHODS: In this case-control study, we investigated the Mn-, Fe-, Cu- and Zn-species in cerebrospinal fluid (CSF) by size-exclusion chromatography hyphenated to inductively coupled plasma mass spectrometry (SEC-ICP-MS) and the total concentration of these metals by inductively coupled plasma sector field mass spectrometry (ICP-sf-MS). RESULTS: The investigation of total metal concentration and speciation provided only minor changes, but it produced strong significance for a number of ratios. The analysis revealed a strong change in the ratio between total concentration of Fe and the amino acid-fraction of Cu. This could be observed when analyzing both the respective element concentrations of the fraction (which also depends on individual variation of the total element concentration) as well as when being expressed as percentage of total concentration (normalization) which more clearly shows changes of distribution pattern independent of individual variation of total element concentrations. CONCLUSION: Speciation analysis, therefore, is a powerful technique to investigate changes in a case-control study where ratios of different species play an important role.

Functionalized poly (ionic liquid) as the support to construct a ratiometric electrochemical biosensor for the selective determination of copper ions in AD rats.

An efficient ratiometric electrochemical biosensor for Cu2+ determination was constructed using dual hydroxyl-functionalized poly (ionic liquid) (DHF-PIL) as the catalyst support. The DHF-PIL exhibited typical macroporous structure, which provided a high surface area of 39.31m2/g for the sufficient loading of biomolecules. The specific recognition of Cu2+ was accomplished by employing neurokinin B (NKB) for the first time, which could bind to Cu2+ to form a [CuII(NKB)2] complex with high specificity. Meanwhile, a common redox mediator, 2, 2'-Azinobis-(3-ethylbenzthiazoline-6-sulfonate) (ABTS) was modified into DHF-PIL by electrostatic interactions to act as an inner reference molecule, which provided a built-in correction for environmental effects and improving the detection accuracy. With this strategy, the developed electrochemical biosensor was capable of determining Cu2+ with a linear range between 0.9 and 36.1µM and low detection limit (LOD) and quantification limit (LOQ) of 0.24 and 0.6µM, respectively. The sensor also displayed a satisfactory selectivity against a series of interferences in the brain, including metal ions, amino acids and other endogenous compounds. Accordingly, the present biosensor was successfully applied to evaluate Cu2+ levels in normal and AD rats.

Iron and copper in progressive demyelination--New lessons from Skogholt's disease.

The pathophysiological mechanisms of progressive demyelinating disorders including multiple sclerosis are incompletely understood. Increasing evidence indicates a role for trace metals in the progression of several neurodegenerative disorders. The study of Skogholt disease, a recently discovered demyelinating disease affecting both the central and peripheral nervous system, might shed some light on the mechanisms underlying demyelination. Cerebrospinal fluid iron and copper concentrations are about four times higher in Skogholt patients than in controls. The transit into cerebrospinal fluid of these elements from blood probably occurs in protein bound form. We hypothesize that exchangeable fractions of iron and copper are further transferred from cerebrospinal fluid into myelin, thereby contributing to the pathogenesis of demyelination. Free or weakly bound iron and copper ions may exert their toxic action on myelin by catalyzing production of oxygen radicals. Similarities to demyelinating processes in multiple sclerosis and other myelinopathies are discussed.

Simultaneous monitoring of cerebral metal accumulation in an experimental model of Wilson's disease by laser ablation inductively coupled plasma mass spectrometry.

BACKGROUND: Neuropsychiatric affection involving extrapyramidal symptoms is a frequent component of Wilson's disease (WD). WD is caused by a genetic defect of the copper (Cu) efflux pump ATPase7B. Mouse strains with natural or engineered transgenic defects of the Atp7b gene have served as model of WD. These show a gradual accumulation and concentration of Cu in liver, kidneys, and brain. However, still little is known about the regional distribution of Cu inside the brain, its influence on other metals and subsequent pathophysiological mechanisms. We have applied laser ablation inductively coupled plasma mass spectrometry and performed comparative metal bio-imaging in brain sections of wild type and Atp7b null mice in the age range of 11-24 months. Messenger RNA and protein expression of a panel of inflammatory markers were assessed using RT-PCR and Western blots of brain homogenates. RESULTS: We could confirm Cu accumulation in brain parenchyma by a factor of two in WD (5.5 µg g(-1) in the cortex) vs. controls (2.7 µg g(-1)) that was already fully established at 11 months. In the periventricular regions (PVR) known as structures of prominent Cu content, Cu was reduced in turn by a factor of 3. This corroborates the view of the PVR as efflux compartments with active transport of Cu into the cerebrospinal fluid. Furthermore, the gradient of Cu increasing downstream the PVR was relieved. Otherwise the architecture of Cu distribution was essentially maintained. Zinc (Zn) was increased by up to 40% especially in regions of high Cu but not in typical Zn accumulator regions, a side effect due to the fact that Zn is to some degree a substrate of Cu-ATPases. The concentrations of iron (Fe) and manganese (Mn) were constant throughout all regions assessed. Inflammatory markers TNF-α, TIMP-1 and the capillary proliferation marker α-SMA were increased by a factor of 2-3 in WD. CONCLUSIONS: This study confirmed stable cerebral Cu accumulation in parenchyma and discovered reduced Cu in cerebrospinal fluid in Atp7b null mice underlining the diagnostic value of micro-local analytical techniques.

Regulation of copper transport crossing brain barrier systems by Cu-ATPases: effect of manganese exposure.

Regulation of cellular copper (Cu) homeostasis involves Cu-transporting ATPases (Cu-ATPases), i.e., ATP7A and ATP7B. The question as to how these Cu-ATPases in brain barrier systems transport Cu, i.e., toward brain parenchyma, cerebrospinal fluid (CSF), or blood, remained unanswered. This study was designed to characterize roles of Cu-ATPases in regulating Cu transport at the blood-brain barrier (BBB) and blood-CSF barrier (BCB) and to investigate how exposure to toxic manganese (Mn) altered the function of Cu-ATPases, thereby contributing to the etiology of Mn-induced parkinsonian disorder. Studies by quantitative real-time RT-PCR (qPCR), Western blot, and immunocytochemistry revealed that both Cu-ATPases expressed abundantly in BBB and BCB. Transport kinetic studies by in situ brain infusion and ventriculo-cisternal (VC) perfusion in Sprague Dawley rat suggested that the BBB was a major site for Cu entry into brain, whereas the BCB was a predominant route for Cu efflux from the CSF to blood. Confocal evidence showed that the presence of excess Cu or Mn in the choroid plexus cells led to ATP7A relocating toward the apical microvilli facing the CSF, but ATP7B toward the basolateral membrane facing blood. Mn exposure inhibited the production of both Cu-ATPases. Collectively, these data suggest that Cu is transported by the BBB from the blood to brain, which is mediated by ATP7A in brain capillary. By diffusion, Cu ions move from the interstitial fluid into the CSF, where they are taken up by the BCB. Within the choroidal epithelial cells, Cu ions are transported by ATP7B back to the blood. Mn exposure alters these processes, leading to Cu dyshomeostasis-associated neuronal injury.

Fe and Cu do not differ in Parkinson's disease: a replication study plus meta-analysis.

To evaluate whether iron and copper levels in serum, plasma, and cerebrospinal fluid are disarranged in Parkinson's disease (PD), we performed meta-analyses of 33 studies on the topic published from 1987 to 2011 and contextually carried out a replication study in serum by ourselves as well. We found no variation in metals between PD patients and healthy controls, according to our replication study. The metaregression for sex revealed that serum copper differences found in some studies could be referred to the different percentage of women in the PD sample. Transferrin and transferrin saturation levels found increased in PD subjects underline the concept to extend the iron study in PD to iron master proteins.

Normal prions as a new target of cobalamin (vitamin B12) in rat central nervous system.

The pathogenesis of cobalamin (Cbl)-deficient (Cbl-D) neuropathy and the role of normal prions (PrPcs) in myelin maintenance are both subjects of debate. We have demonstrated that Cbl deficiency damages myelin by increasing tumor necrosis factor (TNF)-α, and decreasing epidermal growth factor (EGF) levels in the rat central nervous system (CNS). It is known that TNF-α and EGF regulate PrPc expression in vitro, and that myelin vacuolation, reactive astrocytosis and microglial activation are common to rat Cbl-D neuropathy and some prion diseases. We have shown that Cbl deficiency leads to high levels of PrPcs [particularly the octapeptide repeat (OR) domains] in the rat CNS thereby damaging the spinal cord (SC) myelin, and that chronic intra-cerebroventricular treatment with anti-OR antibodies normalizes SC myelin morphology. We have also found that PrPc levels are increased in the SC of Cbl-D rats by the time the myelin lesions appear, and that this increase is mediated by excess myelinotoxic TNF-α and prevented by EGF treatment, which has proved to be as effective as Cbl in preventing Cbl deficiency-induced lesions. Cbl stimulates PrPc mRNA-related synthesis in Cbl-D SC and duodenum, two rat tissues that are severely affected by Cbl deficiency. New PrPc synthesis is a common effect of various myelinotrophic agents, two of which (EGF and anti-TNF-α antibodies) also stimulate PrPc mRNA-related synthesis in the SC of Cbl-D rats.

Copper in Alzheimer's disease: a meta-analysis of serum, plasma, and cerebrospinal fluid studies.

This contribution reviews and corrects data from our previous meta-analysis, which appeared in the Journal of Alzheimer's Disease in 2011 concerning the role of copper in Alzheimer's disease. We repeated the meta-analysis after excluding four of the five studies from our laboratory to avoid possible bias in the result. In addition, we included two studies on serum copper levels in Alzheimer's disease not previously considered. The results indicate higher levels of copper in Alzheimer's disease patients than in controls, confirming our previous conclusion.

Cobalamin (vitamin B(12)) regulation of PrP(C), PrP(C)-mRNA and copper levels in rat central nervous system.

The pathogenesis of cobalamin (Cbl)-deficient (Cbl-D) neuropathy is not clear, nor is the role of prions (PrP(C)) in myelin maintenance. However, as it is known that Cbl deficiency damages myelin by increasing tumor necrosis factor (TNF)-α and decreasing epidermal growth factor (EGF) levels in rat spinal cord (SC), and that TNF-α and EGF regulate PrP(C) expression in vitro, we investigated whether Cbl deficiency modifies SC PrP(C) and PrP(C)-mRNA levels in Cbl-D rats. PrP(C) levels had increased by the time myelin lesions appeared. This increase was mediated by excess myelinotoxic TNF-α and prevented by EGF, which proved to be as effective as Cbl in preventing Cbl deficiency-induced lesions. There were no significant changes in hepatic PrP(C) levels of Cbl-D rats. Anti-octapeptide repeat (OR) region antibodies normalized SC myelin morphology. Cbl deficiency greatly reduced SC PrP(C)-mRNA levels, which were subsequently increased by Cbl and EGF. Cbl deficiency-induced excess OR is myelin-damaging, but new PrP(C) synthesis is a common effect of different myelinotrophic agents.

The role of metallobiology and amyloid-ß peptides in Alzheimer's disease.

The biggest risk factor for Alzheimer's disease is the process of ageing, but the mechanisms that lead to the manifestation of the disease remain to be elucidated. Why age triggers the disease is unclear but an emerging theme is the inability for a cell to efficiently maintain many key processes such as energy production, repair, and regenerative mechanisms. Metal ions are essential to the metabolic function of every cell. This review will explore the role and reported changes in metal ions in Alzheimer disease, particularly the brain, blood and cerebral spinal fluid, emphasizing how iron, copper and zinc may be involved through the interactions with amyloid precursor protein, the proteolytically cleaved peptide amyloid-beta (Aß), and other related metalloproteins. Finally, we explore the monomeric makeup of possible Aß dimers, what a dimeric Aß species from Alzheimer's disease brain tissue is likely to be composed of, and discuss how metals may influence Aß production and toxicity via a copper catalyzed dityrosine cross-link.

Regulation of brain copper homeostasis by the brain barrier systems: effects of Fe-overload and Fe-deficiency.

Maintaining brain Cu homeostasis is vital for normal brain function. The role of systemic Fe deficiency (FeD) or overload (FeO) due to metabolic diseases or environmental insults in Cu homeostasis in the cerebrospinal fluid (CSF) and brain tissues remains unknown. This study was designed to investigate how blood-brain barrier (BBB) and blood-SCF barrier (BCB) regulated Cu transport and how FeO or FeD altered brain Cu homeostasis. Rats received an Fe-enriched or Fe-depleted diet for 4 weeks. FeD and FeO treatment resulted in a significant increase (+55%) and decrease (-56%) in CSF Cu levels (p<0.05), respectively; however, neither treatment had any effect on CSF Fe levels. The FeD, but not FeO, led to significant increases in Cu levels in brain parenchyma and the choroid plexus. In situ brain perfusion studies demonstrated that the rate of Cu transport into the brain parenchyma was significantly faster in FeD rats (+92%) and significantly slower (-53%) in FeO rats than in controls. In vitro two chamber Transwell transepithelial transport studies using primary choroidal epithelial cells revealed a predominant efflux of Cu from the CSF to blood compartment by the BCB. Further ventriculo-cisternal perfusion studies showed that Cu clearance by the choroid plexus in FeD animals was significantly greater than control (p<0.05). Taken together, our results demonstrate that both the BBB and BCB contribute to maintain a stable Cu homeostasis in the brain and CSF. Cu appears to enter the brain primarily via the BBB and is subsequently removed from the CSF by the BCB. FeD has a more profound effect on brain Cu levels than FeO. FeD increases Cu transport at the brain barriers and prompts Cu overload in the CNS. The BCB plays a key role in removing the excess Cu from the CSF.

Concentration of calcium and magnesium and trace elements (zinc, copper, iron and manganese) in cerebrospinal fluid: a try of a pathophysiological classification.

The aim of this study is to analyze the variation of the elements (Ca, Mg, Cu, Fe, Zn and Mn) in normal and pathological CSF and develop a classification basing on the increases in cells and proteins and taking into account these variations. A total of 173 cerebrospinal fluids were analyzed. Of these, 37 fulfilled the criteria of normality and, after clinical exploration, were considered to be healthy (control group). The remaining 136 CSFs (pathological group) belonged to people for whom some neurological pathology had been observed in the clinical exploration and whose CSF analysis presented some abnormality. CSF was extracted by puncture in the lumbar cistern. The analysis of metals was performed by atomic absorption spectrophotometry. The statistical values (mean±standard deviation) obtained for each element analyzed in control group were as follows: Ca (mg/dL): 4.95±0.70; Mg (mg/dL): 2.74±0.10; Cu (µg/dL): 15.70±13.50; Fe (µg/dL): 13.10±3.60; Zn (µg/dL): 17.40±9.50 and Mn (µg/dL): 2.50±0.70. In the pathological CSFs, significant increases were found (p<0.050) in relation to the control group for Ca, Cu, Fe, Zn and Mn in groups with an increase of both cells and proteins. A significant decrease of Mg (p<0.050) was found in the groups with cell and protein increases. Given the results obtained in the different subgroups of the proposed classification, we conclude that it is necessary to further categorize the patients' diagnostics in the different subgroups. This would help to validate the classification.

Copper in Alzheimer's disease: a meta-analysis of serum,plasma, and cerebrospinal fluid studies.

There is an ongoing debate on the involvement of systemic copper (Cu) dysfunctions in Alzheimer's disease (AD), and clinical studies comparing Cu levels in serum, plasma, and cerebrospinal fluid (CSF) of AD patients with those of healthy controls have delivered non-univocal and often conflicting results. In an attempt to evaluate whether Cu should be considered a potential marker of AD, we applied meta-analysis to a selection of 26 studies published in the literature. Meta-analysis is a quantitative method that combines the results of independent reports to distinguish between small effects and no effects, random variations, variations in sample used, or in different analytical approaches. The subjects' sample obtained by merging studies was a pooled total of 761 AD subjects and 664 controls for serum Cu studies, 205 AD subjects and 167 controls for plasma Cu, and of 116 AD subjects and 129 controls for CSF Cu. Our meta-analysis of serum data showed that AD patients have higher levels of serum Cu than healthy controls. Plasma data did not allow conclusions, due to their high heterogeneity, but the meta-analysis of the combined serum and plasma studies confirmed higher Cu levels in AD. The analysis of CSF data, instead, revealed no difference between AD patients and controls.

Somatic mosaicism in Menkes disease suggests choroid plexus-mediated copper transport to the developing brain.

The primary mechanism of copper transport to the brain is unknown, although this process is drastically impaired in Menkes disease, an X-linked neurodevelopmental disorder caused by mutations in an evolutionarily conserved copper transporter, ATP7A. Potential central nervous system entry routes for copper include brain capillary endothelial cells that originate from mesodermal angioblasts and form the blood-brain barrier, and the choroid plexuses, which derive from embryonic ectoderm, and form the blood-cerebrospinal fluid barrier. We exploited a rare (and first reported) example of somatic mosaicism for an ATP7A mutation to shed light on questions about copper transport into the developing brain. In a 20-month-old Menkes disease patient evaluated before copper treatment, blood copper, and catecholamine concentrations were normal, whereas levels in cerebrospinal fluid were abnormal and consistent with his neurologically severe phenotype. We documented disparate levels of mosaicism for an ATP7A missense mutation, P1001L, in tissues derived from different embryonic origins; allele quantitation showed P1001L in approximately 27% of DNA samples from blood cells (mesoderm-derived) and 88% from cultured fibroblasts (ectoderm-derived). These findings imply that the P1001L mutation in the patient preceded formation of the three primary embryonic lineages at gastrulation, with the ectoderm layer ultimately harboring a higher percentage of mutation-bearing cells than mesoderm or endoderm. Since choroid plexus epithelia are derived from neuroectoderm, and brain capillary endothelial cells from mesodermal angioblasts, the clinical and biochemical findings in this infant support a critical role for the blood-CSF barrier (choroid plexus epithelia) in copper entry to the developing brain.

Copper status abnormalities and how to measure them in neurodegenerative disorders.

Copper is essential for life. It plays a pivotal role in the central nervous system, in which a low concentration of copper results in incomplete development, whereas an excess of copper is injurious. Redox reactions are at the basis of copper toxicity: in fact, it catalyses the production of reactive oxygen species in Fenton or Haber-Weiss reactions. Abnormalities of copper homeostasis in neurodegenerative disorders were discovered decades ago. The steady increase in reports from the literature demonstrating copper involvement in neurodegenerative disorders coincides with the improvement, reliability and low cost devices which measure copper markers in biological samples. These devices also demonstrate increasing relevance in diagnosis and in therapy monitoring as well. Methods and new perspectives for the analysis of copper markers status are discussed herein, weighing pros and cons of application to a specific neurological disorder. In particular, it have been introduced three patents regarding a new apparatus for measuring levels of metal in biological samples, employing a current measuring device. A mention of recent patents concerning new derivatives of curcumin has been done considering its metal chelating and multi-functional properties that make these compounds interesting candidates for treatment of some neurodegenerative disorders.

Bioavailability and catalytic properties of copper and iron for Fenton chemistry in human cerebrospinal fluid.

A breakdown in homeostasis of redox-active metals represents an important factor for neurodegeneration. We have used EPR spectroscopy and BMPO spin-trap to investigate the catalytic properties and ligand modulation of redox activity of copper and iron in human cerebrospinal fluid (CSF). In contrast to iron, copper supplementation provoked a statistically significant increase in hydroxyl free radical generation in CSF treated with H(2)O(2). However, in a binary copper/iron containing Fenton system, iron catalytically activated copper. The chelator EDTA, which represents a model of physiological metal ligands, completely prevented copper's redox activity in CSF, while iron chelation led to a significant increase in hydroxyl radical generation, indicating that copper and iron do not only have diverse catalytic properties in the CSF but also that their redox activities are differently modulated by ligands. The application of DDC reduced hydroxyl radical generation in the CSF containing catalytically active metals (free Cu(2+) or Fe(3+)-EDTA complex). We conclude that chelators, such as DDC, are capable of preventing the prooxidative activity of both metals and may be suitable for reducing hydroxyl radical formation in certain pathophysiological settings.

Zinc and copper modulate Alzheimer Abeta levels in human cerebrospinal fluid.

Abnormal interaction of beta-amyloid 42 (Abeta42) with copper, zinc and iron induce peptide aggregation and oxidation in Alzheimer's disease (AD). However, in health, Abeta degradation is mediated by extracellular metalloproteinases, neprilysin, insulin degrading enzyme (IDE) and matrix metalloproteinases. We investigated the relationship between levels of Abeta and biological metals in CSF. We assayed CSF copper, zinc, other metals and Abeta42 in ventricular autopsy samples of Japanese American men (N=131) from the population-based Honolulu Asia Aging Study. There was a significant inverse correlation of CSF Abeta42 with copper, zinc, iron, manganese and chromium. The association was particularly strong in the subgroup with high levels of both zinc and copper. Selenium and aluminum levels were not associated to CSF Abeta42. In vitro, the degradation of synthetic Abeta substrate added to CSF was markedly accelerated by low levels (2microM) of exogenous zinc and copper. While excessive interaction with copper and zinc may induce neocortical Abeta precipitation in AD, soluble Abeta degradation is normally promoted by physiological copper and zinc concentrations.