Role of neutrophils in spinal cord injury in the rat

doi:10.1016/S0306-4522(97)00011-0

Neuroscience

Volume 79, Issue 4, 6 June 1997, Pages 1177-1182

https://doi.org/10.1016/S0306-4522(97)00011-0 Get rights and content

Abstract

Activated neutrophils are thought to be involved in tissue injury through the release of various inflammatory mediators. To understand the role of neutrophils in spinal cord injury, the effects of nitrogen mustard-induced leukocyte depletion and the administration of an anti-P-selectin monoclonal antibody on motor disturbances observed following spinal cord compression were examined in rats. Spinal cord injury was induced by applying a 20-g weight for 20 min at the level of the 12th thoracic vertebra, resulting in motor disturbances of the hindlimbs 24 h postcompression. Motor disturbances, evaluated using Tarlov's index, an inclined-plane test and climbing ability, were markedly attenuated in rats with nitrogen mustard-induced leukocytopenia. Administration of the anti-P-selectin monoclonal antibody, by which adhesion of activated neutrophils to endothelial cells may be inhibited, also attenuated motor disturbances. Histological examination revealed that intramedullary hemorrhages observed 24 h after compression at the 12th thoracic vertebra of the spinal cord were significantly attenuated in leukocytopenic animals and those which received the anti-P-selectin monoclonal antibody. The accumulation of neutrophils at the site of compression, as evaluated by measuring the tissue myeloperoxidase activity, significantly increased with time following the compression, peaking at 3 h postcompression. Spinal cord myeloperoxidase activity did not increase in sham-operated animals. Leukocyte depletion and administration of the anti-P-selectin monoclonal antibody both reduced the accumulation of neutrophils in the damaged spinal cord segment 3 h postcompression.

These observations strongly suggest that activated neutrophils play an important role in compression-induced thoracic spinal cord injury and that a P-selectin-mediated interaction between activated neutrophils and endothelial cells may be a critical step in endothelial cell injury leading to spinal cord injury.

Section snippets

Monoclonal antibodies to P-selectin

Murine immunoglobulin G1 anti-human P-selectin monoclonal antibody (MAb PB1.3) and a non-blocking control monoclonal antibody (MAb PNB1.6) were kindly provided by Sumitomo Pharmaceutical Co. (Osaka, Japan). MAb PNB 1.6 is structurally similar to MAb PB1.3, which inhibits the P-selectin-mediated adhesion of rat platelets to human neutrophils, and binds to cobra venom factor-activated rat pulmonary endothelium, whereas MAb PNB 1.6 does not.[18]

Reduction in circulating leukocytes by nitrogen mustard

Nitrogen mustard (NM, 1.75 mg/kg, Sigma Chemical Co.,

Effects of nitrogen mustard-induced leukocytopenia and anti-P-selectin monoclonal antibodies (MAb PB1.3 and MAb PNB1.6) on compression-induced spinal cord injury

The effects of NM-induced leukocytopenia and the administration of anti-P-selectin MAbs on the motor function of hindlimbs 24 h postcompression are shown in Fig. 2 and 3. Motor function evaluated using Tarlov's motor scale (Fig. 2) and the inclined-plane test (Table 1) significantly improved both in animals made leukocytopenic and in those that received the anti-P-selectin MAb PB1.3, compared with control animals. In contrast, MAb PNB1.6 did not improve the motor function.

Although all

Discussion

In the present study, motor disturbances following spinal cord compression were significantly attenuated in leukocytopenic rats and in those that received the anti-P-selectin MAb PB1.3. Although animals with Tarlov's motor scale 2 (n=19) could not stand, most of them could climb on to the platform in the present study. However, the time required for climbing on to the platform (7.90±0.57 s, mean±S.D., n=17) was significantly longer than that of sham-operated animals (0.88±0.07 s, n=10, P<0.01).

Conclusions

Leukocyte depletion and administration of an anti-P-selectin MAb significantly attenuated thoracic compression-induced SCI leading to temporary paralysis of the lower extremities in rats. The observations in the present study strongly suggest that activated neutrophils play an important role in compression-induced SCI and that a P-selectin-mediated interaction between activated neutrophils and endothelial cells appears to be critical in endothelial cell injury leading to SCI.

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View full text

Role of neutrophils in spinal cord injury in the rat

Abstract

Section snippets

Monoclonal antibodies to P-selectin

Reduction in circulating leukocytes by nitrogen mustard

Effects of nitrogen mustard-induced leukocytopenia and anti-P-selectin monoclonal antibodies (MAb PB1.3 and MAb PNB1.6) on compression-induced spinal cord injury

Discussion

Conclusions

Ann. emerg. Med.

Blood

Free Rad. Biol. Med.

Expl Neurol.

Blood

J. Chronic Dis.

Polymorphonuclear leukocyte infiltration into cerebral focal ischemic tissue

J. Neurosci. Res.

Macrophages and inflammatory damage in spinal cord injury

J. Neurotrauma

Proteolysis by neutrophils

J. clin. Invest.

Postischemic administration of an anti-Mac-1 antibody reduces ischemic cell damage after middle cerebral artery occlusion in rats

Stroke

The free radical pathology and the microcirculation in the major central nervous system disorders

Acta physiol. scand. Suppl.

The fine structure of endothelial surfaces in the microcirculation

Scan. Electron Microsc.