Increased oxidative activity in human blood neutrophils and monocytes after spinal cord injury

• Published in: Experimental neurology Vol. 215; no. 2; pp. 308 - 316
• Main Authors: Bao, Feng, Bailey, Christopher S., Gurr, Kevin R., Bailey, Stewart I., Rosas-Arellano, M. Patricia, Dekaban, Gregory A., Weaver, Lynne C.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.02.2009; Elsevier
• Subjects: Adult; Aged, 80 and over; Analysis of Variance; Biological and medical sciences; Cyclooxygenase 2 - metabolism; Female; Fluoresceins; Humans; Inflammation; Injuries of the nervous system and the skull. Diseases due to physical agents; Lipid Peroxidation - physiology; Macrophage; Male; Medical sciences; Middle Aged; Monocytes - metabolism; Neurology; Neutrophil; Neutrophils - metabolism; NF-kappa B - metabolism; Nitric Oxide Synthase Type II - metabolism; Oxidative damage; Oxidative enzyme; Peroxidase; Reactive Oxygen Species - blood; Rhodamines; Spinal Cord Injuries - blood; Trauma; Traumas. Diseases due to physical agents; Young Adult; NADPH; DHR123; Oxidative enzyme; COX-2; fMLP; gp91 phox; Oxidative damage; DCF; R123; CNS; TBARS; Inflammation; MDA; MPO; Trauma; DCFH-DA; TBA; RCF; ANOVA; KPBS; SCI; iNOS; Neutrophil; Macrophage; Human; Nervous system diseases; Monocyte; Enzyme; Spinal cord trauma; Central nervous system disease; Spinal cord disease
• DOI: 10.1016/j.expneurol.2008.10.022
• ISSN: 0014-4886; 1090-2430

Traumatic injury can cause a systemic inflammatory response, increasing oxidative activity of circulating leukocytes and potentially exacerbating the original injury, as well as causing damage to initially unaffected organs. Although the importance of intraspinal inflammation after human spinal cord injury is appreciated, the role of the systemic inflammatory response to this injury is not widely recognised. We investigated oxidative activity of blood leukocytes from nine cord-injured subjects and six trauma controls (bone fractures without CNS injury) at 6 h–2 weeks after injury, comparing values to those of ten uninjured subjects. Neutrophil and monocyte free radical production, evaluated by flow cytometry, increased significantly more in cord injury subjects than in trauma controls (6-fold vs 50% increases). In leukocyte homogenates, the concentration of free radicals increased significantly more in cord injury subjects (2-fold) than in the trauma controls (1.6-fold) as did activity of myeloperoxidase (2.3-fold vs. 1.7-fold). Moreover, in homogenates and blood smears, expression of the NADPH oxidase subunit gp91 phox and of the oxidative enzyme, inducible nitric oxide synthetase was 20–25% greater in cord injury subjects than in trauma controls. Expression of the pro-inflammatory transcription factor NF-κB and of cyclooxygenase-2 increased similarly after both injuries. Finally, aldehyde products of tissue-damaging lipid peroxidation also increased significantly more in the plasma of spinal cord injury subjects than in trauma controls (2.6 fold vs. 1.9-fold). Spinal cord injury causes a particularly intense systemic inflammatory response. Limiting this response briefly after cord injury should protect the spinal cord and tissues/organs outside the CNS from secondary damage.