Microglial TREM2 senses TDP‐43 and protects against TDP‐43‐related neurodegeneration

Abstract

AbstractBackgroundTriggering receptor expressed on myeloid cell 2 (TREM2) is a surface receptor that, in the central nervous system, is exclusively expressed on microglia. TREM2 variants have been linked to increased risk for neurodegenerative diseases, but the functional effects of microglial TREM2 in TAR‐DNA binding protein 43 kDa (TDP‐43)‐related neurodegeneration remain largely unknown.MethodWe investigated TDP‐43 neurodegeneration via viral‐mediated expression of hTDP‐43 protein in mice or inducible expression of hTDP43 with defective nuclear localization signals in transgenic mice. Mass cytometry analysis, mass spectrometry, surface plasmon resonance, and computational simulation were used to study the interaction between TREM2 and TDP‐43.ResultWe found that TREM2 deficiency impaired microglia phagocytic clearance of pathological TDP‐43, and enhanced neuronal damage and motor function impairments. hTDP‐43 induced a TREM2‐dependent subpopulation of microglia with high CD11c expression and higher phagocytic ability. We further demonstrated an interaction between TDP‐43 and TREM2, in vitro and in vivo, in hTDP‐43‐expressing transgenic mouse brains. We computationally identified the region within hTDP‐43 that interacts with TREM2 and observed the potential interaction in ALS patient tissues.ConclusionOur data reveal the novel interaction between TREM2 and TDP‐43, highlighting that TDP‐43 is a potential ligand for microglial TREM2 and the interaction mediates neuroprotection of microglial TREM2 in TDP‐43‐related neurodegeneration.