Theo P. A. Kruck

Intramuscular desferrioxamine in patients with Alzheimer's disease

Although epidemiological and biochemical evidence suggests that aluminium may be associated with Alzheimers disease (AD), there is no convincing proof of a causal link for aluminium in disease progression. We have completed a two year, single-blind study to investigate whether the progression of dementia could be slowed by the trivalent ion chelator, desferrioxamine. 48 patients with probable AD were randomly assigned to receive desferrioxamine (125 mg intramuscularly twice daily, 5 days per week, for 24 months), oral placebo (lecithin), or no treatment. No significant differences in baseline measures of intelligence, memory, or speech ability existed between groups. Activities of daily living were assessed and videorecorded at 6, 12, 18, and 24 month intervals. There were no differences in the rate of deterioration of patients receiving either placebo or no treatment. Desferrioxamine treatment led to significant reduction in the rate of decline of daily living skills as assessed by both group means (p = 0.03) and variances (p less than 0.04). The mean rate of decline was twice as rapid for the no-treatment group. Appetite (n = 4) and weight (n = 1) loss were the only reported side-effects. We conclude that sustained administration of desferrioxamine may slow the clinical progression of the dementia associated with AD.

CAN THE CONTROVERSY OF THE ROLE OF ALUMINUM IN ALZHEIMER'S DISEASE BE RESOLVED? WHAT ARE THE SUGGESTED APPROACHES TO THIS CONTROVERSY AND METHODOLOGICAL ISSUES TO BE CONSIDERED?

Aluminum (Al) is unquestionably neurotoxic in both experimental animals and certain human diseases. Minute quantities injected intracerebrally into rabbits will induce severe neurological symptoms and neuropathological features of neurodegeneration. Hyper-aluminemia often develops in patients with renal failure being treated with intermittent hemodialysis on a chronic basis, and in severe cases results in an encephalopathy. Uremic adults and premature infants not on dialysis treatment also can develop encephalopathy due to Al toxicity, as is the case when large amounts of alum are used as a urinary bladder irrigant. There are many other examples of Al-induced neurotoxicity; however, the question as to whether Al presents a health hazard to humans as a contributing factor to Alzheimers disease is still the subject of debate. Several lines of evidence are presented that have formed the basis of the debate concerning the possible pathogenic role for Al in Alzheimers disease. Important evidence for an Al-Alzheimers causal relationship is the observation by laser microprobe mass analysis (LMMS) of the presence of Al in neurofibrillary tangles, although there are conflicting data on the extent of the Al deposition. The relatively poor sensitivity of some of the analytical instruments available for these challenging in situ microanalyses could explain the discrepant results, although LMMS and perhaps secondary ion mass spectrometry (SIMS) appear to be sufficiently sensitive. Harmonization of the techniques is an essential next step. There is new evidence that exposure to Al from drinking water might result in cognitive impairment and an increased incidence of Alzheimers disease. However, these epidemiological studies have inherent problems that must be scrutinized to determine if an association really does exist. An understanding of a possible enhanced bioavailability of Al in this type of exposure, versus other exposures such as antacid intake or industrial exposure, needs to be considered and explored. There has been one promising clinical trial of the treatment of Alzheimers disease patients with the Al chelator desferrioxamine (DFO). Further studies are needed, and if confirmation is forthcoming then such data could also support an Al-Alzheimers disease link as well as suggesting that DFO offers potential as a therapeutic agent. The possibility that iron might be the offending agent needs to be considered since DFO is a very strong iron chelator. The significance of Al-induced neurofibrillary degeneration in experimental animals should be assessed especially in light of new data showing that this model exhibits abnormally phosphorylated tau protein structures in the neuronal perikarya. Thus the key questions that must be answered before it can be asserted that Al possesses causal relationship to Alzheimers disease, are as follows and are addressed in this present discussion: (1) Are there elevations of the concentration of Al in the brains of Alzheimers disease patients? (2) Is there a relationship between environmental exposure to Al, particularly in drinking water, and an increased risk of Alzheimers disease? (3) Is treatment with DFO a potentially useful therapeutic approach and to what extent might beneficial effects of DFO implicate Al in the etiology of Alzheimers disease? (4) Are there similarities between the experimental animal studies and Alzheimers disease particularly in the development of abnormal forms of tau seen in neurofibrillary tangles? (5) Does Al promote the deposition of the A beta peptide in Alzheimers disease? (6) Does hyperaluminemia associated with long-term hemodialysis treatment induce neurofibrillary degeneration? If the answer to each of these six questions is yes, then does this assert that Al possesses a causal relationship to Alzheimers disease? On the other hand, must all six be met to be able to make this assertion?

Are hereditary hemochromatosis mutations involved in Alzheimer disease

Mutations in the class I-like major histocompatibility complex gene called HFE are associated with hereditary hemochromatosis (HHC), a disorder of excessive iron uptake. We screened DNA samples from patients with familial Alzheimer disease (FAD) (n = 26), adults with Down syndrome (DS) (n = 50), and older (n = 41) and younger (n = 52) healthy normal individuals, for two HHC point mutations-C282Y and H63D. Because the apolipoprotein E (ApoE) E4 allele is a risk factor for AD and possibly also for dementia of the AD type in DS, DNA samples were also ApoE genotyped. Chi-squared analyses were interpreted at the 0.05 level of significance without Bonferroni corrections. In the pooled healthy normal individuals, C282Y was negatively associated with ApoE E4, an effect also apparent in individuals with DS but not with FAD. Relative to older normals, ApoE E4 was overrepresented in both males and females with FAD, consistent with ApoE E4 being a risk factor for AD; HFE mutations were overrepresented in males and underrepresented in females with FAD. Strong gender effects on the distribution of HFE mutations were apparent in comparisons among ApoE E4 negative individuals in the FAD and healthy normal groups (P < 0.002). Our findings are consistent with the proposition that among ApoE E4 negative individuals HFE mutations are predisposing to FAD in males but are somewhat protective in females. Further, ApoE E4 effects in our FAD group are strongest in females lacking HFE mutations. Relative to younger normals there was a tendency for ApoE E4 and H63D to be overrepresented in males and underrepresented in females with DS. The possibility that HFE mutations are important new genetic risk factors for AD should be pursued further.

A novel trivalent cation chelator Feralex dissociates binding of aluminum and iron associated with hyperphosphorylated τ of Alzheimer’s disease

Aluminum (Al(III)) and iron (Fe(III)) are reported to accumulate in neurofibrillary tangles of the Alzheimers disease (AD) brain. In these lesions Al (III) and Fe (III) bind with hyperphosphorylated tau (PHFtau), the major constituent of the lesions, and induce its aggregation. It is thought that inhibition and dissociation of such Al (III)/Fe (III) binding associated with PHFtau could slow or halt the tau-related neurofibrillary degeneration in patients with AD. A study, using a previously developed in vitro system in which Al (III) and Fe (III) interact with PHFtau on AD brain sections and on immunoblot membranes showed that the potent Al (III)/Fe (III) chelator desferrioxamine elicited Al (III) chelation when subjected to autoclave heating. Here, the ability of a recently developed chemical chelator Feralex-G to remove PHFtau-bound Al (III)/Fe (III), using reaction conditions at 37 degrees C, was examined and compared with that of desferrioxamine. Chelation of Fe(III) was achieved by both compounds with no discernible difference in their chelating ability. In contrast, in the present system, the two chelators gave a different Al (III) chelation response. When incubated at 37 degrees C, desferrioxamine failed to attain notable Al (III) chelation, while Feralex-G displayed efficient Al (III) chelation. Thus, when considering competitive Al (III) removal from brain PHFtau, Feralex-G is a stronger chelator for Al(III) than desferrioxamine. The efficient Al (III) chelation attainable by Feralex-G adds weight to its potential clinical usefulness as a medicine in the aluminum/iron chelation therapy for patients with AD.

Towards the prevention of potential aluminum toxic effects and an effective treatment for Alzheimer’s disease

In 1991, treatment with low dose intramuscular desferrioxamine (DFO), a trivalent chelator that can remove excessive iron and/or aluminum from the body, was reported to slow the progression of Alzheimers disease (AD) by a factor of two. Twenty years later this promising trial has not been followed up and why this treatment worked still is not clear. In this critical interdisciplinary review, we provide an overview of the complexities of AD and involvement of metal ions, and revisit the neglected DFO trial. We discuss research done by us and others that is helping to explain involvement of metal ion catalyzed production of reactive oxygen species in the pathogenesis of AD, and emerging strategies for inhibition of metal-ion toxicity. Highlighted are insights to be considered in the quests to prevent potentially toxic effects of aluminum toxicity and prevention and intervention in AD.

Molecular shuttle chelation: the use of ascorbate, desferrioxamine and Feralex-G in combination to remove nuclear bound aluminum.

Abstract1. Abundant data suggest that aluminum (Al(III)) exposure may be an environmental risk factor contributing to the development, progression and/or neuropathology of several human neurodegenerative disorders, including Alzheimers disease (AD).2. Nuclei appear to be one directed target for Al(III) binding, accumulation, and Al(III)-mediated dysfunction due in part to their high content of polyphosphorylated nucleic acids, nucleotides, and nucleoproteins.3. The design of chelation therapies dealing with the removal of Al(III) from these genetic compartments therefore represents an attractive strategy to alleviate the development and/or progression of central nervous system dysfunction that may arise from excessive Al(III) exposure.4. In this study we have investigated the potential application of 10 natural and synthetic Al(III) chelators, including ascorbate (AS), desferrioxamine (DF), and Feralex-G (FG), used either alone or in combination, to remove Al(III) preincubated with intact human brain cell nuclei.5. Although nuclear bound Al(III) was found to be highly refractory to removal, the combination of AS+FG was found to be particularly effective in removing Al(III) from the nuclear matrix.6. Our data suggest that chelators carrying cis-hydroxy ketone groups, such as FG, are particularly suited to the removal of Al(III) from complex biological systems.7. We further suggest a mechanism whereby small chelating molecules may penetrate the nucleus, bind Al(III), diffuse to regions accessible by the larger DF or FG molecules and transfer their Al(III) to DF or FG.8. The proposed mechanism, called molecular shuttle chelation may provide a useful pharmacotherapy in the potential treatment of Al(III) overload disease.

Epidemic pathogenic selection: an explanation for hereditary hemochromatosis?

Hereditary hemochromatosis (HH) is a disorder associated with progressive iron overload and deposition in multiple organs. It is the most common inherited single gene disorder in people of Northern and Western European descent. About 80% of individuals of European descent with HH are homozygous for a cysteine-to-tyrosine substitution (C282Y) in the gene now called HFE. The function of HFE protein, a major histocompatibility class I-like transmembrane protein, has not been fully elucidated. Three consequences of the C282Y mutation are lack of expression of HFE on the cellular surface, a lowered iron level in macrophages, and an increased rate of clearance of iron from the intestinal lumen. These changes could confer protection against certain pathogens early in life before iron overload occurs. Furthermore, the C282Y mutation might have been selected for during the European plagues caused by Yersinia spp. and other pathogens because of the conferred resistance to infection, i.e., by epidemic pathogenic selection.

Suppression of deferoxamine mesylate treatment — induced side effects by coadministration of isoniazid in a patient with Alzheimer's disease subject to aluminum removal by ionspecific chelation

Deferoxamine treatment may produce serious side effects that can be eliminated by modification of treatment and by control of deferoxamine metabolism. A patient suffering from dementia of the Alzheimer type with normal liver and kidney function who was treated with deferoxamine initially tolerated a dose of 7 mg/kg deferoxamine mesylate injected intramuscularly twice a day for a total of 5 days a week. After several months nausea and weight loss gradually developed in the patient that could be controlled initially by dose reduction, leading to levels inappropriate for aluminum chelation. HPLC analysis of blood and urine revealed several metabolites including, as a major component, a plasma monoamine oxidase (MAO) catalyzed end product MFO1. Coadministration of isoniazid, a plasma MAO inhibitor, with deferoxamine resulted in reduction of MFO1 from 81% to 8% accompanied by increases in the amounts of metabolite 2 (MFO2) from 2% to 24% and unmetabolized deferoxamine from 17% to 68% after 6 months of treatment. The side effects subsided, the patient regained weight, and treatment could be continued.

Resolution of allelic and non-allelic variants of histone H1 by cation-exchange-hydrophilic-interaction chromatography

A mixed-mode high-performance liquid chromatography (HPLC) method that resolves the six known non-allelic variants of chicken erythrocyte histone H1 is described. Common, but previously unknown, allelic variants of H1 that comigrate in polyacrylamide gel electrophoresis are also resolved. The resolution of H1 variants achieved by this method should be useful in determining the functional significance of H1 sequence heterogeneity and in analyses of post-translational modification of H1. Furthermore, the principles behind the separation should be applicable to analyses of polymorphism in other proteins.

A predictor for side effects in patients with Alzheimer's disease treated with deferoxamine mesylate.

In a previously reported clinical trial, patients with Alzheimers disease were treated with deferoxamine mesylate, which resulted in a 50% reduction in the average rate of deterioration over 2 years. There were five deaths in the untreated group during the trial and no deaths in the treated group, although five of 25 treated patients reported anorexia. Deferoxamine metabolite analysis of urine for 24 hours after deferoxamine injection from sensitive and nonsensitive patients showed marked differences. Occurrence of side effects correlated with increased formation of a monoamine oxidase catalyzed (major) metabolite, MFO1. The metabolite ratio, MFO1/total metabolites, plus parent drug (TOT) showed a bimodal distribution with a mean ± SD value of 0.68 ± 0.06 for the nonsensitive and 0.79 ± 0.04 for sensitive patients. The MFO1/TOT ratio discriminates between sensitive and nonsensitive patients, and we suggest that the half difference mark between the two mean values (0.735) can be used as a predictor of side effects. Patients with a MFO1/TOT ratio of greater than 0.70 would be considered at risk and observed for onset of side effects. Patients with a MFO1/TOT ratio greater than 0.80 would be considered for immediate adjunct treatment with isoniazid or other monoamine oxidase inhibitors.