title: Microglia and macrophages are the major source of tumor necrosis factor in permanent middle cerebral artery occlusion in mice.
abstract: The proinflammatory cytokine tumor necrosis factor (TNF) is known to be expressed in brain ischemia; however, its cellular and temporal appearance is not fully settled. In this study, nonradioactive in situ hybridization for murine TNF mRNA was performed on brain sections from adult C57x129 mice at 6 hours, 12 hours, 24 hours, 2 days, 5 days, or 10 days (six to eight mice per group) after induction of permanent focal cerebral ischemia. Cortical infarct volumes were estimated, and TNF mRNA-expressing cells were counted within the infarct and infarct border using Cast-Grid analysis. At 12 hours, a peak of 19.2 +/- 5.1 TNF mRNA-expressing cells/mm2 was counted, contrasting two to three times lower values at 6 and 24 hours (6.4 +/- 4.6 and 9.2 +/- 3.4 cells/mm2, respectively) and <2 cells/mm2 at 48 hours and later stages. The TNF mRNA-expressing cells were distributed along the entire rostrocaudal axis of the cortical infarcts and occasionally within the caudate putamen. At all time points, TNF mRNA colocalized with Mac-1-positive microglia/macrophages but not with Ly-6G (Gr-1)-positive polymorphonuclear leukocytes. Similarly, combined in situ hybridization for TNF mRNA and immunohistochemistry for glial fibrillary acidic protein at 12 and 24 hours revealed no TNF mRNA-expressing astrocytes at these time points. Translation of TNF mRNA into bioactive protein was demonstrated in the neocortex of C57B1/6 mice subjected to permanent middle cerebral artery occlusion. In summary, this study points to a time-restricted microglial/macrophage production of TNF in focal cerebral ischemia in mice.
authors.affiliation: Department of Anatomy and Neurobiology, University of Southern Denmark/Odense University.
authors.forename: R
authors.initials: R
authors.lastname: Gregersen
authors.forename: K
authors.initials: K
authors.lastname: Lambertsen
authors.forename: B
authors.initials: B
authors.lastname: Finsen
mesh_terms: D000818:Animals; D001157:Arterial Occlusive Diseases / Q000150:complications / Q000378:metabolism*; D002545:Brain Ischemia / Q000150:complications; D002536:Cerebral Arteries; D002544:Cerebral Infarction / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D016177:Macrophage-1 Antigen / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000378:metabolism*; D009504:Neutrophils / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
chemical_list: D016177:Macrophage-1 Antigen; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha