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Magnetite, a common air pollutant, can induce toxic protein accumulation and neuronal loss associated with Alzheimer’s. During experiments exposing mice to magnetite particles, in only 4 months, increased accumulation of amyloid plaques and behavioral changes were significantly observed. The researchers hope that the study will contribute to the development of preventive health and government measures against the disease.
Magnetite (Fe3O4) is an air pollutant originating from the combustion products of fossil resources such as coal, oil and natural gas. It is commonly found in smoke from coal-fired power plants, vehicle exhaust and brake pads, and engine friction.
Studies have shown that once inhaled, atmospheric particles can accumulate in the lower respiratory tract and then cross the alveolar-capillary barrier and migrate into the systemic circulation. These particles can pass through the olfactory bulb (a small structure located at the base of the brain, responsible for processing smells) to reach the brain and thus cross the blood-brain barrier.
It has been suggested that by entering the brain, these particles may be involved in the etiology of various neurodegenerative diseases, including Alzheimer’s. Indeed, postmortem samples of the patient’s brain have been found to contain abnormally high amounts of magnetite particles. These people lived in heavily polluted areas and were between 40 and 65 years old at the time of death. Note that iron and iron oxide are naturally present in the brain and are required for many metabolic processes. However, their excessive presence can prove toxic, especially inducing oxidative damage.
On the other hand, “Given that less than 1% of Alzheimer’s cases are inherited, it is likely that environment and lifestyle play a major role in the development of the disease,” Cindy Gunawan said in a press release. Sydney (UTS), Australia. However, no studies to date have explored exactly how magnetite and associated particles may lead to Alzheimer’s-related neurodegeneration.
With this vision, Gunawan and his team sought to determine the biomolecular mechanisms underlying this correlation, as part of their new study detailed in the journal. Environment International. Researchers from the University of Technology Sydney, the University of New South Wales and the Singapore Institute of Technology also contributed to the research.
Neurodegenerative effects independent of pathological condition
The new study aimed to investigate in vivo And in vitro To analyze the biological activities of atmospheric pollutants that may be involved in Alzheimer’s. Particles smaller than 1 micron have been specifically targeted, including iron, hydrocarbon-based particles, and magnetite. To do this, researchers exposed human neurons as well as healthy mouse models prone to Alzheimer’s (genetically modified) to these pollutants for 4 months.
The researchers found that magnetite generally stimulated the pathological processes associated with Alzheimer’s in all models. This includes severe loss of neurons in the hippocampus (required for memory) and the somatosensory cortex (involved in processing sensation). In contrast, disease-prone mice showed increased accumulation of the amyloid plaques characteristic of the disease.
Behavioral changes consistent with disease symptoms have also been observed, including stress, anxiety, and short-term memory problems. These latter symptoms were mainly observed in genetically predisposed mice.
See also
In vivo behavioral studies of genetically modified or non-genetically modified mice exposed to model air pollutant particles “IRON”, “DE”, “MAG” (magnetite). Transmission electron microscopy (TEM) images for exposure to (A) iron (B) DE and (C) magnetite. (D) Schematic representation of the elevated plus maze test (EPM) performed by study mice. (E) Time spent in closed arms for wild-type mice exposed to particles. (F) Time spent in closed arms for Alzheimer-prone mice. © Cindy Gunawan et al.
On the other hand, magnetite induced an unusually high immune response in all animals as well as in human neuronal cultures. The mineral triggers an inflammatory response and oxidative stress, which leads to neuronal damage. Inflammation and oxidative stress have also been identified as important factors that may contribute to dementia.
Furthermore, it is interesting to note that “magnetite-induced neurodegeneration also shows signs of Alzheimer’s in the brains of healthy mice, independent of the pathological condition”, suggests Charlotte Fleming of the University of Technology Sydney, co-lead author. Research has indeed found no significant differences in the effects of exposure to pollutants in healthy and diseased mice, except for the accumulation of amyloid plaques.
According to the team, these findings may have important implications for developing guidelines for disease prevention. Researchers suggest magnetite particles in air quality measurements and other measures, including taking appropriate action.
Sources: Environment International
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