Immunological signatures in frontotemporal lobar degeneration.

PURPOSE OF REVIEW: Over the last year, research into the immunological and inflammatory signatures of frontotemporal lobar degeneration (FTLD) has accelerated greatly. Herein, we highlight recently proposed roles of brain-resident microglia as well as peripheral myeloid cells in frontotemporal dementia (FTD)-spectrum disorders.

RECENT FINDINGS: Recent unbiased genetic, transcriptomic, and proteomic surveys using human data confirm significantly altered immune-function genes as well as transcript and protein modules associated with inflammatory and immune function. Beyond human studies, novel animal models indicate important roles for both microglia and monocytes, and central involvement of genes such as Trem2, Apoe, and Tbk1.

SUMMARY: The importance of neuroinflammatory activity in FTD pathophysiology is unambiguous, but whether this activity is primarily beneficial or detrimental remains unclear, with variable results reported for distinct disease paradigms. Going forward, it will be crucial to determine which types of microglial and peripheral myeloid responses are favorable, in response to which specific proteinopathies, and at which point in disease course.