Metabolic drift in the aging brain.

Brain function is highly dependent upon controlled energy metabolism whose loss heralds cognitive impairments. This is particularly notable in the aged individuals and in age-related neurodegenerative diseases. However, how metabolic homeostasis is disrupted in the aging brain is still poorly understood. Here we performed global, metabolomic and proteomic analyses across different anatomical regions of mouse brain at different stages of its adult lifespan. Interestingly, while severe proteomic imbalance was absent, global-untargeted metabolomics revealed an energymetabolic drift or significant imbalance in core metabolite levels in aged mouse brains. Metabolic imbalance was characterized by compromised cellular energy status (NAD decline, increased AMP/ATP, purine/pyrimidine accumulation) and significantly altered oxidative phosphorylation and nucleotide biosynthesis and degradation. The central energy metabolic drift suggests a failure of the cellular machinery to restore metabostasis (metabolite homeostasis) in the aged brain and therefore an inability to respond properly to external stimuli, likely driving the alterations in signaling activity and thus in neuronal function and communication

Macrophage delivery of therapeutic nanozymes in a murine model of Parkinsons disease

Background: Parkinsons disease is a common progressive neurodegenerative disorder associated with profound nigrostriatal degeneration. Regrettably, no therapies are currently available that can attenuate disease progression. To this end, we developed a cell-based nanoformulation delivery system using the antioxidant enzyme catalase to attenuate neuroinflammatory processes linked to neuronal death. Methods: Nanoformulated catalase was obtained by coupling catalase to a synthetic polyelectrolyte of opposite charge, leading to the formation of a polyion complex micelle. The nanozyme was loaded into bone marrow macrophages and its transport to the substantia nigra pars compacta was evaluated in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-intoxicated mice. Results: Therapeutic efficacy of bone marrow macrophages loaded with nanozyme was confirmed by twofold reductions in microgliosis as measured by CD11b expression. A twofold increase in tyrosine hydroxylase-expressing dopaminergic neurons was detected in nanozyme-treated compared with untreated MPTP-intoxicated mice. Neuronal survival was confirmed by magnetic resonance spectroscopic imaging. Bone marrow macrophage-loaded catalase showed sustained release of the enzyme in plasma. Conclusion: These data support the importance of macrophage-based nanozyme carriage for Parkinsons disease therapies