Could a dysfunction of ferritin be a determinant factor in the aetiology of some neurodegenerative diseases?

BACKGROUND: The concentration of iron in the brain increases with aging. Furthermore, it has also been observed that patients suffering from neurological diseases (e.g. Parkinson, Alzheimer...) accumulate iron in the brain regions affected by the disease. Nevertheless, it is still not clear whether this accumulation is the initial cause or a secondary consequence of the disease. Free iron excess may be an oxidative stress source causing cell damage if it is not correctly stored in ferritin cores as a ferric iron oxide redox-inert form.

SCOPE: Both, the composition of ferritin cores and their location at subcellular level have been studied using analytical transmission electron microscopy in brain tissues from progressive supranuclear palsy (PSP) and Alzheimer disease (AD) patients.

MAJOR CONCLUSIONS: Ferritin has been mainly found in oligodendrocytes and in dystrophic myelinated axons from the neuropili in AD. In relation to the biomineralization of iron inside the ferritin shell, several different crystalline structures have been observed in the study of physiological and pathological ferritin. Two cubic mixed ferric-ferrous iron oxides are the major components of pathological ferritins whereas ferrihydrite, a hexagonal ferric iron oxide, is the major component of physiological ferritin. We hypothesize a dysfunction of ferritin in its ferroxidase activity.

GENERAL SIGNIFICANCE: The different mineralization of iron inside ferritin may be related to oxidative stress in olygodendrocites, which could affect myelination processes with the consequent perturbation of information transference.