title: Tumor necrosis factor receptor 1 is a negative regulator of progenitor proliferation in adult hippocampal neurogenesis.
abstract: Tumor necrosis factor-alpha (TNF-alpha) is a proinflammatory cytokine, acting through the TNF-R1 and TNF-R2 receptors. The two receptors have been proposed to mediate distinct TNF-alpha effects in the CNS, TNF-R1 contributing to neuronal damage and TNF-R2 being neuroprotective. Whether TNF-alpha and its receptors play any role for neurogenesis in the adult brain is unclear. Here we used mouse models with loss of TNF-R1 and TNF-R2 function to establish whether signaling through these receptors could influence hippocampal neurogenesis in vivo under basal conditions, as well as after status epilepticus (SE), which is associated with inflammation and elevated TNF-alpha levels. Notably, in the intact brain, the number of new, mature hippocampal neurons was elevated in TNF-R1(-/-) and TNF-R1/R2(-/-) mice, whereas no significant changes were detected in TNF-R2(-/-) mice. Also after SE, the TNF-R1(-/-) and TNF-R1/R2(-/-) mice produced more new neurons. In contrast, the TNF-R2(-/-) mice showed reduced SE-induced neurogenesis. Cell proliferation in the dentate subgranular zone was elevated in TNF-R1(-/-) and TNF-R1/R2(-/-) mice both under basal conditions and after SE. The TNF-R2(-/-) mice either showed no change or minor decrease of cell proliferation. TNF-R1 and TNF-R2 receptors were expressed by hippocampal progenitors, as assessed with reverse transcription-PCR on sorted or cultured cells and immunocytochemistry on cultures. Our data reveal differential actions of TNF-R1 and TNF-R2 signaling in adult hippocampal neurogenesis and identify for the first time TNF-R1 as a negative regulator of neural progenitor proliferation in both the intact and pathological brain.
authors.affiliation: Laboratory of Neurogenesis and Cell Therapy, Section of Restorative Neurology, Wallenberg Neuroscience Center, University Hospital, SE 221 84 Lund, Sweden.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Iosif
authors.forename: Christine T
authors.initials: CT
authors.lastname: Ekdahl
authors.forename: Henrik
authors.initials: H
authors.lastname: Ahlenius
authors.forename: Cornelis J H
authors.initials: CJ
authors.lastname: Pronk
authors.forename: Sara
authors.initials: S
authors.lastname: Bonde
authors.forename: Zaal
authors.initials: Z
authors.lastname: Kokaia
authors.forename: Sten-Eirik W
authors.initials: SE
authors.lastname: Jacobsen
authors.forename: Olle
authors.initials: O
authors.lastname: Lindvall
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D006131:Growth Inhibitors / Q000235:genetics / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology* / Q000473:pathology / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009474:Neurons / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000172:deficiency / Q000502:physiology; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology*
chemical_list: D006131:Growth Inhibitors; D047888:Receptors, Tumor Necrosis Factor, Type I; D047889:Receptors, Tumor Necrosis Factor, Type II