Platelets, via their adhesive receptors (GPIb, GPVI, CLEC-2), monitor vascular integrity and control the trafficking and function of immune cells. GPV, part of the GPIb-V-IX complex, is proteolytically cleaved by thrombin and thereby spatio-temporally controls thrombin activity and fibrin generation, while CLEC-2 is critical for blood-lymphatic separation, vascular homeostasis, and limits macrophage inflammatory activation. Mice deficient for both, GPV and CLEC-2, display altered vascularisation pointing to a loss of vascular barrier function. We hypothesize that the interplay of platelet receptors GPV and CLEC-2 is required to maintain vascular integrity in homeostasis and thrombo-inflammatory processes. P02 aims to understand how GPV and CLEC-2 synergistically act together and protect from vascular inflammation, and how platelets through these receptors interact with endothelial cells and immune cells to ensure vascular integrity and homeostasis in health and disease, e.g. during atherosclerosis. To address these questions, we will generate and apply antibodies against GPV, GPIb and CLEC-2 and employ genetic/humanized mouse models and recombinant proteins to study the interplay of GPV and CLEC-2 in vivo and in vitro. We will use confocal (intravital) microscopy of multiple tissues (e.g. mesenteries, retina) to examine vascularization, vascular integrity and platelet-EC interactions, study platelet-immune cell interactions under static and flow conditions (microfluidics), and use scRNA sequencing.

The two early-stage researchers (ECR.P02.02 and ECR.P02.03) involved in this project will work closely together to unravel the functional roles and interplay of GPV and CLEC-2 in vascular homeostasis and inflammation, understand how GPV and CLEC-2 synergistically work together to ensure vascular barrier function, and explore how GPV/CLEC-2 crosstalk affects (peri-)vascular immune cells.