Neutrophil elastase and neurovascular injury following focal stroke and reperfusion

https://doi.org/10.1016/j.nbd.2009.04.006Get rights and content

Abstract

Neutrophil elastase (NE) degrades basal lamina and extracellular matrix molecules, and recruits leukocytes during inflammation; however, a basic understanding of the role of NE in stroke pathology is lacking. We measured an increased number of extravascular NE-positive cells, as well as increased levels of tissue elastase protein and activity, following transient middle cerebral artery occlusion (tMCAo). Both pharmacologic inhibition of NE with ZN200355 (ZN), and genetic deletion of NE, significantly reduced infarct volume, blood–brain barrier disruption, vasogenic edema, and leukocyte–endothelial adherence 24 h after tMCAo. ZN also reduced infarct volume in MMP9-null mice following tMCAo. There were, however, no reductions in infarct volume or vasogenic edema in NE-null mice in two models of permanent middle cerebral artery occlusion. Our findings confirm the involvement of NE in neurovascular stroke pathology, when reperfusion allows neutrophils access to vulnerable brain, with pharmacologic or genetic inhibition of NE being both neuro- and vasculo-protective in this setting.

Section snippets

Transient and permanent focal cerebral ischemia

The Animal Studies Committee at Washington University School of Medicine approved all experimental methods and animal care procedures in accordance with NIH guidelines. Occlusion of the middle cerebral artery was performed in adult male Swiss–Webster/ND4 (SW/ND4), 129SvEv (wild-type; WT), and NE−/− mice or MMP9−/− mice on a 129SvEv background, at 10–16 weeks of age, as described previously (Gidday et al., 2005). Pilot studies were conducted in SW/ND4 and WT mice to establish transient middle

Physiologic and hemodynamic parameters

Table 1 depicts representative physiologic data, by experimental group, for the animals in which leukocyte adherence was measured. Transcranial Doppler flowmetry established CBF prior to, and immediately following, tMCAo suture placement to confirm the MCA occlusion. As shown in Table 2, suture placement significantly lowered CBF during ischemia relative to baseline CBF within each experimental group, and CBF at 15 min of reperfusion remained significantly lower than baseline (p < 0.05) in all

Discussion

In many pathologic conditions, leukocyte-derived proteases, such as NE, degrade the basement membrane to allow leukocyte extravasation into the surrounding tissue, jeopardizing BBB integrity in the process (Nagy et al., 1998, Man et al., 2007). Once present in the parenchymal extracellular space, NE may also degrade additional extracellular matrix substrates (e.g. collagens, laminins) to threaten neuronal and glial viability. In the present study, we confirmed the presence of extravascular

Acknowledgments

The authors thank Steven S. Shapiro for the breeder pairs of NE−/− mice, and Lena Martensson at AstraZeneca (Wilmington, Delaware) for kindly providing the ZN200355. The authors would like to recognize NIH RO1 NS21045 (TSP), RO1 HL079278 (JMG), PO1 NS032636 (JMG), P01 HL29594 (TLAK), and the Spastic Paralysis Research Foundation of the Illinois-Eastern Iowa District of Kiwanis International (TSP), for funding this research. Ann Stowe is a Hope Center Fellow supported by the Hope Center for

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