TY - JOUR T1 - Brain injury accelerates the onset of a reversible age-related microglial phenotype associated with hyperphagocytosis and inflammatory neurodegeneration JF - bioRxiv DO - 10.1101/2022.05.24.493292 SP - 2022.05.24.493292 AU - Rodney M. Ritzel AU - Yun Li AU - Yun Jiao AU - Zhuofan Lei AU - Sarah J. Doran AU - Junyun He AU - Rami A. Shahror AU - Rebecca J. Henry AU - Shaolin Liu AU - Bogdan A. Stoica AU - Alan I. Faden AU - Gregory Szeto AU - David J. Loane AU - Junfang Wu Y1 - 2022/01/01 UR - http://biorxiv.org/content/early/2022/05/25/2022.05.24.493292.abstract N2 - Lipofuscin is an autofluorescent (AF) pigment formed by lipids and misfolded proteins that accumulates in post-mitotic cells with advanced age. Here we immunophenotyped microglia in the brain of old C57BL/6 mice (>18 months-old) and demonstrate that in comparison to young mice, one third of old microglia are AF, characterized by profound changes in lipid and iron content, phagocytic activity, and oxidative stress. Pharmacological depletion of microglia in old mice eliminated the AF microglia following repopulation and reversed microglial dysfunction. Age-related neurological deficits and neurodegeneration after traumatic brain injury (TBI) were attenuated in old mice lacking AF microglia. Furthermore, hyperphagocytic activity and lipid accumulation in microglia persisted for up to one year after TBI, were modified by Apoe4 genotype, and chronically driven by phagocyte-mediated oxidative stress. Thus, AF may reflect a pathological state in aging microglia associated with hyperphagocytosis and inflammatory neurodegeneration that can be further accelerated by TBI.Teaser Traumatic brain injury accelerates age-related pathological phagocytosis and lipofuscin formation in microglia.Competing Interest StatementThe authors have declared no competing interest. ER -