Haemopexin affects iron distribution and ferritin expression in mouse brain

Area of Science:

• Neuroscience
• Biochemistry
• Cell Biology

Background:

• Haemopexin (Hx) is a plasma glycoprotein primarily synthesized by the liver, responsible for binding and delivering heme to the liver.
• This heme-binding system protects against oxidative stress, limits pathogen access to heme, and aids iron homeostasis.
• Hx has been detected in various tissues, including the brain, and its levels are elevated in cerebrospinal fluid of Alzheimer's disease patients.

Purpose of the Study:

• To investigate the role of Haemopexin (Hx) in heme scavenging and iron regulation within the brain.
• To determine if Hx synthesis in the brain by ventricular ependymal cells impacts iron deposition and ferritin expression.
• To explore the potential involvement of Hx in iron-related neurodegenerative diseases.

Main Methods:

• Analysis of iron deposits and ferritin expression in specific brain regions of Hx-null mice and wild-type controls.
• Quantification of iron-loaded oligodendrocytes in the basal ganglia and thalamus.
• Measurement of malondialdehyde levels and Cu-Zn superoxide dismutase-1 expression in brain tissue.

Main Results:

• Hx-null mice exhibited a twofold increase in iron-loaded oligodendrocytes in the basal ganglia and thalamus compared to wild-type controls.
• No significant increase in H- and L-ferritin expression was observed in these iron-accumulating regions in Hx-null mice.
• A reduction in ferritin-positive cells was noted in the cerebral cortex of Hx-null animals, alongside elevated malondialdehyde and Cu-Zn superoxide dismutase-1 levels.

Conclusions:

• Haemopexin (Hx) plays a crucial role in regulating iron distribution within the brain.
• The absence of Hx leads to iron accumulation in oligodendrocytes without a compensatory increase in ferritin, a pattern observed in neurodegenerative conditions.
• These findings suggest that Hx is involved in the pathogenesis of iron-related neurodegenerative diseases, including Alzheimer's and Parkinson's disease.