Role of Vitamin D in Amyloid clearance via LRP-1 upregulation in Alzheimer's disease: A potential therapeutic target?
Amyloid beta (Aβ) deposition is considered to be one of the primary reason to trigger Alzheimer's disease (AD). Literature clearly suggests decline in Aβ clearance to be accountable for progression of late onset AD as compared to augmented Aβ production. There may be several pathways for Aβ clearance out of which one of the major pathway is the vascular-mediated removal of Aβ from the brain across the blood-brain barrier (BBB) via efflux pumps or receptors. Among Aβ scavenger receptors, low density lipoprotein receptor related protein (LRP-1) has been most extensively studied. LRP-1, is highly expressed in neurons and located on abluminal side of the brain capillaries whose expression decreases in AD patients which give rise to increased cerebral Aβ deposition. Recent evidences reveal that post 1,25-(OH)2D3 treatment, LRP1 expression increases significantly for both in-vivo and in-vitro studies, since Vitamin D receptors (VDR) are broadly expressed in brain. Biological actions of Vitamin D are mediated via its nuclear hormone receptor vitamin D receptor (VDR) and is found to regulate many genes. Several lines of evidence suggest that VDR deficiency/inhibition can be a potential risk factor for AD and sufficient Vitamin D supplementation is beneficial to prevent AD onset/pathology or slow down the progression of disease. The present review establishes a strong correlation between Vitamin D and LRP-1 and their possible involvement in Aβ clearance and thereby emerging as new therapeutic target.