Immune defects in Alzheimer's disease: new medications development

Alzheimer's disease (AD) is a neurodegenerative disease characterized by the accumulation of intracellular and extracellular aggregates. According to the amyloid beta (Aβ) hypothesis, amyloidosis occurring in the brain is a leading cause of neurodegeneration in AD. Defects in the innate immune system may decrease the clearance of Aβ in the brain. Macrophages of most AD patients do not transport Aβ into endosomes and lysosomes, and monocytes from AD patients do not efficiently clear Aβ from AD brain. After stimulation with Aβ, mononuclear cells of normal subjects display up-regulated transcription of MGAT3, which encodes β-1,4-mannosyl-glycoprotein 4-β-N-acetylglucosaminyltransferase, and Toll-like receptor (TLR) genes. Monocytes of AD patients generally down-regulate these genes. A commonly used, naturally occurring material from a spice that enhances certain key functions defective in cells of innate immunity of many AD patients has shown epidemiologic rationale for use in AD treatment. Bisdemethoxycurcumin, a natural curcumin, is a minor constituent of turmeric (curry), and it enhances phagocytosis and clearance of Aβ in cells from most AD patients. We confirmed the effectiveness of a synthetic version of the same compound. In mononuclear cells of most AD patients, bisdemethoxycurcumin enhanced defective phagocytosis of Aβ and increased the transcription of MGAT3 and TLR genes. The potency of bisdemethoxycurcumin as a highly purified compound in facilitating the clearance of Aβ in mononuclear cells suggests the promise of enhanced effectiveness compared to curcuminoid mixtures. Bisdemethoxycurcumin appears to enhance immune function in mononuclear cells of AD patients and may provide a novel approach to AD immunotherapy.