The role of extracellular matrix laminin-10 in vascular inflammation, blood-brain barrier repair and angiogenesis after cerebrovascular disease.

UoM administered thesis: Phd

  • Authors:
  • Hannah Thurgur

Abstract

Stroke remains a devastating health issue worldwide with limited treatment available. Interleukin-1 (IL-1) is a major cytokine implicated in the pathogenesis of stroke, and the blood-brain barrier (BBB) is a major target of IL-1-induced neuroinflammation. The extracellular matrix (ECM) plays a dynamic role in the brain and recent evidence has identified laminin (LM)-10 as a mediator of BBB repair. The aim of this thesis was to determine the role of LM-10 as a modulator of endothelial inflammation and angiogenesis, as well as the role of cerebrovasculature IL-1R1 signalling on laminin expression after stroke. First, I sought to establish a suitable in vitro model to investigate the role of LM-10 as a modulator of IL-1 beta-induced endothelial activation and the angiogenic response of cerebral endothelial cells. I determined a novel role of LM-10 as a modulator of IL-1 beta-induced intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) expression in hCMEC/D3 cells and demonstrated that LM-10 increases endothelial proliferation and migration. I elucidated a novel relationship between IL-1 beta and Hippo signalling, and demonstrated altered Hippo signalling on LM-10. In order to investigate the role of cerebrovasculature IL-1R1 signalling on laminin expression after cerebral ischaemia, I induced conditional deletion of IL-1R1 in brain endothelial cells and performed experimental stroke by occlusion of the middle cerebral artery (MCA). I found that laminin alpha 4 (expressed in LM-8) is more dynamically regulated than laminin alpha 5 (expressed in LM-10) across several time points post-stroke and that laminin alpha 4 expression is regulated by endothelial IL-1R1 signalling. To assess the role of laminin alpha 5 after stroke in vivo, I generated a conditional deletion brain endothelial cell-specific laminin alpha 5 mouse strain and successfully confirmed laminin alpha 5 deletion. I induced experimental stroke by occlusion of the MCA but did not observe an effect of laminin alpha 5 on infarct volume, neurological outcome or cerebral blood flow recovery after stroke. Our results support evidence that the ECM plays a dynamic role in inflammatory conditions in the brain and I have identified a novel crosstalk between IL-1 beta and the Hippo pathway. Although I did not observe an effect of laminin alpha 5 in ischaemic stroke, I believe that further investigation of the isoform specific roles of laminins in cerebrovascular diseases will provide new insights in the role of the ECM during the pathophysiology of stroke that could lead to new therapeutic treatments.

Details

Original languageEnglish
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Award date31 Dec 2020