Investigating cell death pathways in the proinflammatory function of platelets and leukocytes during ischaemia-reperfusion injury
Recent studies from our laboratory have made the unexpected observation that a specific form of platelet cell death, termed programmed necrosis, plays a major role in promoting leukocyte recruitment and tissue damage following I/R injury. Notably, this pathway is resistant to the inhibitory effects of conventional anti-platelet and anti-inflammatory agents. We are examining the thrombo-inflammatory response of mice that are resistant to apoptotic cell death (Bak:Bax knock-out mice) or necrosis (Cyclophilin D knock-out mice), in in vivo models of inflammation and I/R injury. Our aim is to investigate the role of specific cell death pathways in regulating platelet proinflammatory function and leukocyte recruitment, with the ultimate aim of identifying new therapeutic targets to improve microvascular perfusion and reduce inflammation and organ injury.
Identifying new pathways regulating platelet hyperactivity and thrombosis in diabetes
Our laboratory has recently defined a new pathway promoting platelet aggregation and thrombus development that involves biomechanical platelet activation. More recently, we have identified that this pathway is dysregulated in diabetes and leads to enhanced platelet-endothelial interaction through a molecular process that is linked to atherogenesis. This project aims to identify the molecular mechanisms by which hyperglycemia leads to enhanced biomechanical platelet activation, and the relevance of this pathway to platelet-endothelial and platelet-platelet adhesive interactions linked to atherothrombosis.
Investigating a new innovative approach to the treatment of ischaemic stroke
Our laboratory has a longstanding interest in identifying pathways in platelets that are important for arterial thrombus formation, but less critical for haemostasis. One of these pathways involves shear activation of platelets through activation of the p110 isoform of PI 3-kinase (PI3K). We have developed isoform-selective inhibitors against PI3K and demonstrated that these inhibitors are highly effective at promoting and facilitating thrombus dissolution and complete vascular reperfusion, without markedly increasing tail bleeding times. Preliminary studies have revealed that PI3K inhibitors lead to localised regions of thrombus instability, that lead to the development of channels within the body of the thrombus. This project will examine the mechanisms by which PI3K inhibitors enhance reperfusion, examining the impact of thrombus channel formation on blood flow, thrombus porosity and thrombus dissolution. Moreover, the impact of PI3Kinhibitors on end-organ damage, particularly in the stroke context, will also be examined. These studies will not only provide important insight into our understanding of blood clot formation, but may also lead to new approaches to regulate the size and stability of blood clots forming in the body, providing major clinical benefit in the delivery of thrombolytic therapy (blood clot removal).
Investigating novel regulators of platelet procoagulant activity –targeting safer anticoagulation
The intracellular pathways that mediate procoagulant platelet function are only starting to be elucidated. Our laboratory has recently demonstrated that platelet PS exposure and procoagulant function is regulated by programmed cell death pathways, including apoptosis and necrosis. Utilising several novel mouse lines that specifically lack Bak, Bax and CypD in platelets, we have made the unexpected observation that these pathways only contribute to approximately 50% of the platelet procoagulant response. In this project, we are examining a new pathway we have identified to play an important role in regulating the platelet procoagulant response – which involves the signalling adaptor protein 14-3-3 regulating metabolic ATP. We have found that this pathway plays an important role in regulating platelet PS exposure and thrombin generation, necessary for thrombus growth and stability. We aim to determine whether therapeutic targeting of this pathway represents a safe and effective way of reducing thrombin generation in vivo without increasing bleeding risk.