title: Hippocampal adult neurogenesis: Does the immune system matter?
abstract: Adult hippocampal neurogenesis involves proliferation, survival, differentiation and integration of newborn neurons into pre-existing neuronal networks. Although its functional significance in the central nervous system (CNS) has not comprehensively elucidated, adult neurogenesis has been attributed a role in cognition, learning and memory. There is a growing body of evidence that CNS resident as well as peripheral immune cells participate in regulating hippocampal adult neurogenesis. Microglial cells are closely associated with neural stem/progenitor cell (NSPC) in the neurogenic niche engaged in a bidirectional communication with neurons, which may be important for adult neurogenesis. Microglial and neuronal crosstalk is mediated in part by CX3CL1/CX3CR1 signaling and a disruption in this pathway has been associated with impaired neurogenesis. It has been also reported that microglial neuroprotective or neurotoxic effects in adult neurogenesis occur in a context-dependent manner. Apart from microglia other brain resident and peripheral immune cells including pericytes, perivascular macrophages, mast cells and T-cells also modulate this phenomenon. It is worth mentioning that under some physiological circumstances such as normal aging there is a significant decrease in hippocampal neurogenesis. A role for innate and adaptive immune system in adult neurogenesis has been also reported during aging. Here, we review the current evidence regarding neuro-immune interactions in the regulation of neurogenesis under distinct conditions, including aging.
authors.affiliation: Neuroinflammation Research Center, Department of Neuroscience, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Laboratory of Neurobiology "Conceição Machado", Department of Morphology, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil; Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address: mirandas.aline@gmail.com.
authors.forename: Aline Silva
authors.initials: AS
authors.lastname: de Miranda
authors.affiliation: Neuroinflammation Research Center, Department of Neuroscience, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA; Department of Neurology, Key Laboratory of Neurorepair and Regeneration, Tianjin and Ministry of Education, Tianjin Neurological Institute, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Cun-Jin
authors.initials: CJ
authors.lastname: Zhang
authors.affiliation: Neuroinflammation Research Center, Department of Neuroscience, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Atsuko
authors.initials: A
authors.lastname: Katsumoto
authors.affiliation: Interdisciplinary Laboratory of Medical Investigation, School of Medicine, Federal University of Minas Gerais, Belo Horizonte, MG, Brazil. Electronic address: altexr@gmail.com.
authors.forename: Antônio Lúcio
authors.initials: AL
authors.lastname: Teixeira
mesh_terms: D000818:Animals; D049109:Cell Proliferation / Q000502:physiology; D006624:Hippocampus / Q000166:cytology*; D006801:Humans; D007107:Immune System / Q000502:physiology*; D058953:Neural Stem Cells / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology*
keywords: Aging; Fracktalkine; Microglia; Newborn neurons; T-cells