Surveillance, phagocytosis, and inflammation: how never-resting microglia influence adult hippocampal neurogenesis.
Microglia cells are the major orchestrator of the brain inflammatory response. As such, they are traditionally studied in various contexts of trauma, injury, and disease, where they are well-known for regulating a wide range of physiological processes by their release of proinflammatory cytokines, reactive oxygen species, and trophic factors, among other crucial mediators. In the last few years, however, this classical view of microglia was challenged by a series of discoveries showing their active and positive contribution to normal brain functions. In light of these discoveries, surveillant microglia are now emerging as an important effector of cellular plasticity in the healthy brain, alongside astrocytes and other types of inflammatory cells. Here, we will review the roles of microglia in adult hippocampal neurogenesis and their regulation by inflammation during chronic stress, aging, and neurodegenerative diseases, with a particular emphasis on their underlying molecular mechanisms and their functional consequences for learning and memory.
Ikerbasque Foundation, 48011 Bilbao, Spain ; Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, 48170 Zamudio, Spain ; Department of Neurosciences, University of the Basque Country, 48940 Leioa, Spain.
Amanda
A
Sierra
Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, 48170 Zamudio, Spain ; Department of Neurosciences, University of the Basque Country, 48940 Leioa, Spain.
Sol
S
Beccari
Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, 48170 Zamudio, Spain ; Department of Neurosciences, University of the Basque Country, 48940 Leioa, Spain.
Irune
I
Diaz-Aparicio
Ikerbasque Foundation, 48011 Bilbao, Spain ; Achucarro Basque Center for Neuroscience, Bizkaia Science and Technology Park, 48170 Zamudio, Spain ; Department of Neurosciences, University of the Basque Country, 48940 Leioa, Spain.
Juan M
JM
Encinas
Centre de Recherche du CHU de Québec, Axe Neurosciences, Canada G1P 4C7 ; Département de Médecine Moléculaire, Université Laval, Canada G1V 4G2.
Samuel
S
Comeau
Centre de Recherche du CHU de Québec, Axe Neurosciences, Canada G1P 4C7 ; Département de Médecine Moléculaire, Université Laval, Canada G1V 4G2.
Marie-Ève
MÈ
Tremblay
D000375:Aging / Q000276:immunology / Q000502:physiology; D000818:Animals; D006624:Hippocampus / Q000166:cytology / Q000254:growth & development* / Q000502:physiology; D006801:Humans; D007157:Immunologic Surveillance / Q000502:physiology*; D007249:Inflammation / Q000503:physiopathology*; D017628:Microglia / Q000502:physiology*; D019636:Neurodegenerative Diseases / Q000473:pathology / Q000503:physiopathology; D055495:Neurogenesis / Q000276:immunology / Q000502:physiology*; D010587:Phagocytosis / Q000502:physiology*; D013315:Stress, Psychological