TREM2 Maintains Microglial Metabolic Fitness in Alzheimer's Disease.
1. Cell. 2017 Aug 10;170(4):649-663.e13. doi: 10.1016/j.cell.2017.07.023. TREM2 Maintains Microglial Metabolic Fitness in Alzheimer's Disease. Ulland TK(1), Song WM(1), Huang SC(1), Ulrich JD(2), Sergushichev A(3), Beatty WL(4), Loboda AA(3), Zhou Y(1), Cairns NJ(2), Kambal A(1), Loginicheva E(1), Gilfillan S(1), Cella M(1), Virgin HW(1), Unanue ER(1), Wang Y(1), Artyomov MN(1), Holtzman DM(2), Colonna M(5). Author information: (1)Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. (2)Department of Neurology, Washington University School of Medicine, St. Louis, MO 63110, USA; Knight Alzheimer's Disease Research Center, Washington University School of Medicine, St. Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA. (3)Computer Technologies Department, ITMO University, Saint Petersburg 197101, Russia. (4)Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA. (5)Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, MO 63110, USA. Electronic address: mcolonna@wustl.edu. Elevated risk of developing Alzheimer's disease (AD) is associated with hypomorphic variants of TREM2, a surface receptor required for microglial responses to neurodegeneration, including proliferation, survival, clustering, and phagocytosis. How TREM2 promotes such diverse responses is unknown. Here, we find that microglia in AD patients carrying TREM2 risk variants and TREM2-deficient mice with AD-like pathology have abundant autophagic vesicles, as do TREM2-deficient macrophages under growth-factor limitation or endoplasmic reticulum (ER) stress. Combined metabolomics and RNA sequencing (RNA-seq) linked this anomalous autophagy to defective mammalian target of rapamycin (mTOR) signaling, which affects ATP levels and biosynthetic pathways. Metabolic derailment and autophagy were offset in vitro through Dectin-1, a receptor that elicits TREM2-like intracellular signals, and cyclocreatine, a creatine analog that can supply ATP. Dietary cyclocreatine tempered autophagy, restored microglial clustering around plaques, and decreased plaque-adjacent neuronal dystrophy in TREM2-deficient mice with amyloid-β pathology. Thus, TREM2 enables microglial responses during AD by sustaining cellular energetic and biosynthetic metabolism. Copyright © 2017 Elsevier Inc. All rights reserved. DOI: 10.1016/j.cell.2017.07.023 PMCID: PMC5573224 PMID: 28802038 [Indexed for MEDLINE]