TREM2 and Alzheimer disease: While inflammation has long been understood to be a part of the brain response to plaque and tangle pathology associated with AD, the recent identification of mutations in the triggering receptor expressed on myeloid cell-2 (TREM2), a single transmembrane receptor expressed on the surface of microglia, has provoked further excitement surrounding immune modulation as a candidate therapeutic target for AD [5, 6].