title: Depletion of Ly6G/Gr-1 leukocytes after spinal cord injury in mice alters wound healing and worsens neurological outcome.
abstract: Spinal cord injury (SCI) induces a robust inflammatory response and the extravasation of leukocytes into the injured tissue. To further knowledge of the functions of neuroinflammation in SCI in mice, we depleted the early arriving neutrophils using an anti-Ly6G/Gr-1 antibody. Complete blood counts revealed that neutrophils increased approximately 3-fold over uninjured controls and peaked at 6-12 h after injury, and that anti-Ly6G/Gr-1 treatment reduced circulating neutrophils by >90% at these time points. Intravital and spinning disk confocal microscopy of the exposed posterior vein and postcapillary venules showed a significant reduction in rolling and adhering neutrophils in vivo after anti-Ly6G/Gr-1 treatment; this was accompanied by a parallel reduction in neutrophil numbers within the injured spinal cord at 24 and 48 h as determined by flow cytometry. The evolution of astrocyte reactivity, a wound healing response, was reduced in anti-Ly6G/Gr-1-treated mice, which also had less spared white matter and axonal preservation compared with isotype controls. These histological outcomes may be caused by alterations of growth factors and chemokines important in promoting wound healing. Importantly, anti-Ly6G/Gr-1 treatment worsened behavioral outcome as determined using the Basso Mouse Scale and subscores. Although the spectrum of cells affected by anti-Ly6G/Gr-1 antibody treatment cannot be fully ascertained at this point, the correspondence of neutrophil depletion and worsened recovery suggests that neutrophils promote recovery after SCI through wound healing and protective events that limit lesion propagation.
authors.affiliation: Hotchkiss Brain Institute and Department of Clinical Neurosciences, University of Calgary, Calgary, Alberta, Canada.
authors.forename: David P
authors.initials: DP
authors.lastname: Stirling
authors.forename: Shuhong
authors.initials: S
authors.lastname: Liu
authors.forename: Paul
authors.initials: P
authors.lastname: Kubes
authors.forename: V Wee
authors.initials: VW
authors.lastname: Yong
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000950:Antigens, Ly / Q000276:immunology / Q000378:metabolism*; D001522:Behavior, Animal / Q000187:drug effects; D002135:Calcium-Binding Proteins / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D004195:Disease Models, Animal; D005434:Flow Cytometry / Q000379:methods; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D008840:Microfilament Proteins; D022423:Myeloid Cells / Q000187:drug effects / Q000502:physiology; D016900:Neurofilament Proteins / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects; D012720:Severity of Illness Index; D013119:Spinal Cord Injuries / Q000097:blood* / Q000503:physiopathology*; D013997:Time Factors; D014945:Wound Healing / Q000187:drug effects / Q000502:physiology*
chemical_list: C491049:Aif1 protein, mouse; D000906:Antibodies; D000950:Antigens, Ly; D002135:Calcium-Binding Proteins; D016207:Cytokines; D005904:Glial Fibrillary Acidic Protein; D036341:Intercellular Signaling Peptides and Proteins; C480309:Ly6G antigen, mouse; D008840:Microfilament Proteins; D016900:Neurofilament Proteins; C051774:neurofilament protein H; D049452:Green Fluorescent Proteins