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International Journal of Cell Biology
Volume 2013 (2013), Article ID 576383, 7 pages
http://dx.doi.org/10.1155/2013/576383
Review Article

The Innate Immune System in Alzheimer’s Disease

1Department of Neurology, New York University School of Medicine, Alexandria East River Science Park, 450 East 29th Street, Room 802, New York City, NY 10016, USA
2Psychiatry Department, New York University School of Medicine, Alexandria East River Science Park, 450 East 29th Street, Room 802, New York City, NY 10016, USA
3Physiology and Neuroscience Department, New York University School of Medicine, Alexandria East River Science Park, 450 East 29th Street, Room 802, New York City, NY 10016, USA
4King Abdulaziz University, School of Medicine, Jeddah, KAU 21589, Saudi Arabia
5Pathology, New York University School of Medicine, Alexandria East River Science Park, 450 East 29th Street, Room 802, New York City, NY 10016, USA

Received 24 May 2013; Accepted 9 September 2013

Academic Editor: Alessio Cardinale

Copyright © 2013 Allal Boutajangout and Thomas Wisniewski. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Alzheimer’s disease (AD) is the leading cause for dementia in the world. It is characterized by two biochemically distinct types of protein aggregates: amyloid β (Aβ) peptide in the forms of parenchymal amyloid plaques and congophilic amyloid angiopathy (CAA) and aggregated tau protein in the form of intraneuronal neurofibrillary tangles (NFT). Several risk factors have been discovered that are associated with AD. The most well-known genetic risk factor for late-onset AD is apolipoprotein E4 (ApoE4) (Potter and Wisniewski (2012), and Verghese et al. (2011)). Recently, it has been reported by two groups independently that a rare functional variant (R47H) of TREM2 is associated with the late-onset risk of AD. TREM2 is expressed on myeloid cells including microglia, macrophages, and dendritic cells, as well as osteoclasts. Microglia are a major part of the innate immune system in the CNS and are also involved in stimulating adaptive immunity. Microglia express several Toll-like receptors (TLRs) and are the resident macrophages of the central nervous system (CNS). In this review, we will focus on the recent advances regarding the role of TREM2, as well as the effects of TLRs 4 and 9 on AD.