TY - JOUR
T1 - The cellular inflammatory response in human spinal cords after injury
AU - Fleming, Jennifer C.
AU - Norenberg, Michael D.
AU - Ramsay, David A.
AU - Dekaban, Gregory A.
AU - Marcillo, Alexander E.
AU - Saenz, Alvaro D.
AU - Pasquale-Styles, Melissa
AU - Dietrich, W. Dalton
AU - Weaver, Lynne C.
N1 - Funding Information:
This research was supported by a New Emerging Team Grant from the Canadian Institutes of Health Research (CIHR) and by grants NO1-NS-3-2351 and PO1 NS38665 from the National Institutes of Health of the USA. Ms Fleming held a studentship from the Ontario Neurotrauma Foundation, and currently holds a studentship from CIHR. Dr Weaver was a FORE-SCI (Facility of Research Excellence in SCI) visiting scholar and Ms Fleming held a FORE-SCI studentship at the Miami Project to Cure Paralysis during part of the course of this research. The authors are indebted to Ms Gladys Ruenes at the Miami Project for her superb technical advice. We also appreciate the assistance of colleagues at the Department of Pathology, London Health Sciences Centre: Ms Lynn James who retrieved case materials and Ms Deb Reade and Ms Deb Newman who sectioned some of the spinal cords. The authors also thank Dr Canio Polosa for his constructive suggestions regarding this research. Funding to pay the Open Access publication charges for this article was provided by a New Emerging Team Grant from the CIHR.
PY - 2006/12
Y1 - 2006/12
N2 - Spinal cord injury (SCI) provokes an inflammatory response that generates substantial secondary damage within the cord but also may contribute to its repair. Anti-inflammatory treatment of human SCI and its timing must be based on knowledge of the types of cells participating in the inflammatory response, the time after injury when they appear and then decrease in number, and the nature of their actions. Using post-mortem spinal cords, we evaluated the time course and distribution of pathological change, infiltrating neutrophils, monocytes/macrophages and lymphocytes, and microglial activation in injured spinal cords from patients who were 'dead at the scene' or who survived for intervals up to 1 year after SCI. SCI caused zones of pathological change, including areas of inflammation and necrosis in the acute cases, and cystic cavities with longer survival (Zone 1), mantles of less severe change, including axonal swellings, inflammation and Wallerian degeneration (Zone 2) and histologically intact areas (Zone 3). Zone 1 areas increased in size with time after injury whereas the overall injury (size of the Zones 1 and 2 combined) remained relatively constant from the time (1-3 days) when damage was first visible. The distribution of inflammatory cells correlated well with the location of Zone 1, and sometimes of Zone 2. Neutrophils, visualized by their expression of human neutrophil α-defensins (defensin), entered the spinal cord by haemorrhage or extravasation, were most numerous 1-3 days after SCI, and were detectable for up to 10 days after SCI. Significant numbers of activated CD68-immunoreactive ramified microglia and a few monocytes/macrophages were in injured tissue within 1-3 days of SCI. Activated microglia, a few monocytes/macrophages and numerous phagocytic macrophages were present for weeks to months after SCI. A few CD8+ lymphocytes were in the injured cords throughout the sampling intervals. Expression by the inflammatory cells of the oxidative enzymes myeloperoxidase (MPO) and nicotinamide adenine dinucleotide phosphate oxidase (gp91phox), and of the pro-inflammatory matrix metalloproteinase (MMP)-9, was analysed to determine their potential to cause oxidative and proteolytic damage. Oxidative activity, inferred from MPO and gp91phox immunoreactivity, was primarily associated with neutrophils and activated microglia. Phagocytic macrophages had weak or no expression of MPO or gp91phox. Only neutrophils expressed MMP-9. These data indicate that potentially destructive neutrophils and activated microglia, replete with oxidative and proteolytic enzymes, appear within the first few days of SCI, suggesting that anti-inflammatory 'neuroprotective' strategies should be directed at preventing early neutrophil influx and modifying microglial activation.
AB - Spinal cord injury (SCI) provokes an inflammatory response that generates substantial secondary damage within the cord but also may contribute to its repair. Anti-inflammatory treatment of human SCI and its timing must be based on knowledge of the types of cells participating in the inflammatory response, the time after injury when they appear and then decrease in number, and the nature of their actions. Using post-mortem spinal cords, we evaluated the time course and distribution of pathological change, infiltrating neutrophils, monocytes/macrophages and lymphocytes, and microglial activation in injured spinal cords from patients who were 'dead at the scene' or who survived for intervals up to 1 year after SCI. SCI caused zones of pathological change, including areas of inflammation and necrosis in the acute cases, and cystic cavities with longer survival (Zone 1), mantles of less severe change, including axonal swellings, inflammation and Wallerian degeneration (Zone 2) and histologically intact areas (Zone 3). Zone 1 areas increased in size with time after injury whereas the overall injury (size of the Zones 1 and 2 combined) remained relatively constant from the time (1-3 days) when damage was first visible. The distribution of inflammatory cells correlated well with the location of Zone 1, and sometimes of Zone 2. Neutrophils, visualized by their expression of human neutrophil α-defensins (defensin), entered the spinal cord by haemorrhage or extravasation, were most numerous 1-3 days after SCI, and were detectable for up to 10 days after SCI. Significant numbers of activated CD68-immunoreactive ramified microglia and a few monocytes/macrophages were in injured tissue within 1-3 days of SCI. Activated microglia, a few monocytes/macrophages and numerous phagocytic macrophages were present for weeks to months after SCI. A few CD8+ lymphocytes were in the injured cords throughout the sampling intervals. Expression by the inflammatory cells of the oxidative enzymes myeloperoxidase (MPO) and nicotinamide adenine dinucleotide phosphate oxidase (gp91phox), and of the pro-inflammatory matrix metalloproteinase (MMP)-9, was analysed to determine their potential to cause oxidative and proteolytic damage. Oxidative activity, inferred from MPO and gp91phox immunoreactivity, was primarily associated with neutrophils and activated microglia. Phagocytic macrophages had weak or no expression of MPO or gp91phox. Only neutrophils expressed MMP-9. These data indicate that potentially destructive neutrophils and activated microglia, replete with oxidative and proteolytic enzymes, appear within the first few days of SCI, suggesting that anti-inflammatory 'neuroprotective' strategies should be directed at preventing early neutrophil influx and modifying microglial activation.
KW - Inflammation
KW - Macrophage
KW - Neutrophil
KW - Oxidative activity
KW - SCI
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U2 - 10.1093/brain/awl296
DO - 10.1093/brain/awl296
M3 - Article
C2 - 17071951
AN - SCOPUS:33845332735
VL - 129
SP - 3249
EP - 3269
JO - Brain
JF - Brain
SN - 0006-8950
IS - 12
ER -