3-nitrotyrosine and Amyloidosis

Microdose lithium is protective against Alzheimer's disease (AD), although the precise mechanisms through which its protective effects are conferred remain unclear.. To further examine the effects during the earliest stages of Aβ pathology, we evaluated whether NP03, a microdose lithium formulation, modulates Aβ-mediated oxidative damage and neuroinflammation when applied to a rat transgenic model of AD-like amyloidosis overexpressing amyloid precursor protein (APP).. McGill-R-Thy1-APP transgenic rats and wild-type littermates were treated with NP03 or vehicle formulation for 8 weeks beginning at 3 months of age - a phase preceding Aβ plaque deposition in the transgenic rats.. Oxidative and nitrosative stress markers, protein-bound 4-hydroxynonenal (HNE) and proteinresident 3-nitrotyrosine (3-NT), inflammatory cytokines production, as well as microglial recruitment towards Aβ-burdened neurons were assayed. NP03 significantly decreased cerebral HNE and 3-NT, and reduced production of pro-inflammatory cytokines in McGill-R-Thy1-APP transgenic rats. NP03 further reduced expression of microglia surface receptor Trem2 and led to a corresponding reduction in microglia recruitment towards Aβ-burdened neurons in the CA1 region of the hippocampus.. These results suggest that NP03 may function to slow the AD-like pathology in part by modifying oxidative/nitrosative damage and neuroinflammation, raising the possibility that low doses of microencapsulated lithium might be of therapeutic-preventive value during very early or preclinical AD.

Topics: Aldehydes; Alzheimer Disease; Amyloid beta-Protein Precursor; Amyloidosis; Animals; CA1 Region, Hippocampal; Cytokines; Disease Models, Animal; Encephalitis; Humans; Lithium; Mice, Transgenic; Mutation; Plaque, Amyloid; Rats; Tyrosine

Part of the inflammatory response in Alzheimer's disease (AD) is the upregulation of the inducible nitric oxide synthase (NOS2) resulting in increased NO production. NO contributes to cell signaling by inducing posttranslational protein modifications. Under pathological conditions there is a shift from the signal transducing actions to the formation of protein tyrosine nitration by secondary products like peroxynitrite and nitrogen dioxide. We identified amyloid β (Aβ) as an NO target, which is nitrated at tyrosine 10 (3NTyr(10)-Aβ). Nitration of Aβ accelerated its aggregation and was detected in the core of Aβ plaques of APP/PS1 mice and AD brains. NOS2 deficiency or oral treatment with the NOS2 inhibitor L-NIL strongly decreased 3NTyr(10)-Aβ, overall Aβ deposition and cognitive dysfunction in APP/PS1 mice. Further, injection of 3NTyr(10)-Aβ into the brain of young APP/PS1 mice induced β-amyloidosis. This suggests a disease modifying role for NOS2 in AD and therefore represents a potential therapeutic target.

Topics: Age Factors; Alzheimer Disease; Amyloid beta-Peptides; Amyloid beta-Protein Precursor; Amyloidosis; Animals; Biophysics; Brain; Disease Models, Animal; Drug Combinations; Electric Stimulation; Enzyme-Linked Immunosorbent Assay; Gene Expression Regulation; Hippocampus; Humans; Immunoprecipitation; In Vitro Techniques; Long-Term Potentiation; Maze Learning; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mutation; Neurons; Nitric Oxide Synthase Type II; Patch-Clamp Techniques; Peptide Fragments; Peroxynitrous Acid; Plaque, Amyloid; Presenilin-1; Tyrosine