Impact of the neutrophil response to granulocyte colony-stimulating factor on the risk of hemorrhage when used in combination with tissue plasminogen activator during the acute phase of experimental stroke

Abstract

BackgroundGranulocyte colony-stimulating factor (G-CSF) is a pharmacologic agent inducing neutrophil mobilization and a new candidate for neuroprotection and neuroregeneration in stroke. Its effects when used in combination with tissue plasminogen activator (tPA) were explored during the acute phase of ischemic stroke.MethodsWe used a middle cerebral artery occlusion (MCAO) model of cerebral ischemia, associated with treatment with tPA, in male spontaneously hypertensive rats (SHR). Granulocyte colony-stimulating factor (G-CSF; 60 μg/kg) was injected just before tPA. Neutrophil response in peripheral blood and in the infarct area was quantified in parallel to the infarct volume. Protease matrix metallopeptidase 9 (MMP-9) release from circulating neutrophils was analyzed by immunochemistry and zymography. Vascular reactivity and hemorrhagic volume in the infarct area was also assessed.ResultsTwenty four hours after ischemia and tPA, G-CSF administration induced a significant increase of neutrophils in peripheral blood (P <0.05). At 72 hours post-ischemia, G-CSF was significantly associated with an increased risk of hemorrhage in the infarct area (2.5 times more likely; P <0.05) and significant cerebral endothelium-dependent dysfunction. Ex vivo, an increased MMP-9 release from neutrophils after tPA administration correlated to the increased hemorrhagic risk (P <0.05). In parallel, G-CSF administration was associated with a decreased neutrophil infiltration in the infarct area (-50%; P <0.05), with a concomitant significant neuroprotective effect (infarct volume: -40%; P <0.05).ConclusionsWe demonstrate that G-CSF potentiates the risk of hemorrhage in experimental stroke when used in combination with tPA by inducing neutrophilia. This effect is concomitant to an increased MMP-9 release from peripheral neutrophils induced by the tPA treatment. These results highlight the potential hemorrhagic risk of associating G-CSF to thrombolysis during the acute phase of stroke.

Targeting Neutrophils in Ischemic Stroke: Translational Insights from Experimental Studies

“…In a rat MCAO stroke model, G-CSF increases peripheral neutrophil numbers at 24 hours, and this is associated with an increase in MMP-9 and tPA-related HT. 82 It was found to potentiate neutrophil release of MMP-9 in the present of tPA. In humans, G-CSF administered after ischemic stroke has also been found to increase peripheral leukocyte count.…”

Immune responses in stroke: how the immune system contributes to damage and healing after stroke and how this knowledge could be translated to better cures?

“…IL‐1 up‐regulates the neutrophil‐selective chemokines CXCL1 and CXCL2 within the plasma to recruit neutrophils into the brain during ischaemia . In conjunction with this, intercellular adhesion molecule 1 has been shown to facilitate neutrophil adhesion to endothelial cells during MCAO, and consequently to induce BBB dysfunction by disrupting the tight junction protein Claudin‐5 through the production of MMP‐9 . Inhibition of either neutrophil infiltration or neutrophil‐derived MMP‐9 reduces inflammatory‐mediated cerebral damage and risk of haemorrhagic stroke, suggesting that neutrophils can mediate BBB dysfunction and consequently affect neuronal health.…”

Treatment with recombinant tissue plasminogen activator (r-TPA) induces neutrophil degranulation in vitro via defined pathways

“…However, in vitro mechanistic insights on r-tPA-triggered intracellular pathways and the potential clinical relevance of r-tPA-induced neutrophil degranulation in AIS patients remain unexplored. Among different early complications associated with thrombolysis in which neutrophil degranulation might play a pathophysiological role, we focused on AIS hemorrhagic transformations [21,22], which range from of 1.7% to 13% of thrombolysed patients [23,24]. In addition, this translational study aims at investigating the potential degranulating activity of r-tPA and downstream activation of intracellular pathways in vitro on human neutrophils cultured on different substrate cultures.…”