Neutrophils mediate early cerebral cortical hypoperfusion in a murine model of subarachnoid haemorrhage

Axel Neulen,Axel Neulen,Florian Ringel,Florian Ringel,Johannes Lotz,Johannes Lotz,Sven R Kantelhardt,Sven R Kantelhardt,Sascha Kunath,Sascha Kunath,Tobias Pantel,Tobias Pantel,Serge C Thal,Serge C Thal,Maximilian Petermeyer,Maximilian Petermeyer,Bernd Moosmann,Bernd Moosmann,Michael Kosterhon,Michael Kosterhon,Andreas Kramer

doi:10.1038/s41598-019-44906-9

Abstract

Cerebral hypoperfusion in the first hours after subarachnoid haemorrhage (SAH) is a major determinant of poor neurological outcome. However, the underlying pathophysiology is only partly understood. Here we induced neutropenia in C57BL/6N mice by anti-Ly6G antibody injection, induced SAH by endovascular filament perforation, and analysed cerebral cortical perfusion with laser SPECKLE contrast imaging to investigate the role of neutrophils in mediating cerebral hypoperfusion during the first 24 h post-SAH. SAH induction significantly increased the intracranial pressure (ICP), and significantly reduced the cerebral perfusion pressure (CPP). At 3 h after SAH, ICP had returned to baseline and CPP was similar between SAH and sham mice. However, in SAH mice with normal neutrophil counts cortical hypoperfusion persisted. Conversely, despite similar CPP, cortical perfusion was significantly higher at 3 h after SAH in mice with neutropenia. The levels of 8-iso-prostaglandin-F2α in the subarachnoid haematoma increased significantly at 3 h after SAH in animals with normal neutrophil counts indicating oxidative stress, which was not the case in neutropenic SAH animals. These results suggest that neutrophils are important mediators of cortical hypoperfusion and oxidative stress early after SAH. Targeting neutrophil function and neutrophil-induced oxidative stress could be a promising new approach to mitigate cerebral hypoperfusion early after SAH.

Highlights

Aneurysmal subarachnoid haemorrhage (SAH) is one of the most common forms of haemorrhagic stroke[1,2,3]
While major research efforts over the past few decades have focused on delayed cerebral ischemia (DCI), recent clinical research data indicate that the degree of cerebral hypoperfusion during the first hours after SAH determines the severity of early brain injury (EBI), the occurrence of DCI, and the neurological outcome[4,8,9,10,11,12,13,14]
The central role of leukocyte-dependent inflammation in the etiology of delayed cerebral vasospasm was demonstrated by results showing attenuated delayed vasospasm following experimental SAH by blocking leukocyte extravasation with antibodies directed against intercellular adhesion molecule 1, cluster of differentiation 11 (CD11), or CD1816,17

Summary

Introduction

Aneurysmal subarachnoid haemorrhage (SAH) is one of the most common forms of haemorrhagic stroke[1,2,3]. Induction of neutropenia by injection of an anti-Ly6G antibody attenuated delayed cerebral vasospasm[18] and improved neurological outcome[19] In line with these experimental data, a high percentage of neutrophils in human cerebrospinal fluid (CSF) samples on day 3 post-SAH was associated with development of cerebral vasospasm and markers of oxidative stress were elevated in CSF samples from SAH patients[20]. Friedrich et al.[24] reported that neutrophils accumulate in cerebral microvessels and infiltrate brain parenchyma within 10 min after induction of SAH in rats, while Yang et al.[25] observed leukocyte adhesion to postcapillary venules within 10 min after SAH in an in vivo microscopy study of mice These findings indicate that inflammatory processes induced by rapid neutrophil accumulation at the site of the subarachnoid haematoma may contribute to early cerebral hypoperfusion as well as delayed cerebral vasospasm

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Discussion

Conclusion