PhD defence: Beneath the surface - Cellular responses in the vasculature

The surface of cells contains specific proteins that mediate responses to extracellular stimuli. In this thesis we use mass spectrometry, a technique that enables us to simultaneously measure the levels of thousands of proteins, to study cellular responses in the vasculature. In addition to the regular protocol, we developed a technique that allows us to specifically focus on the cell surface, and thereby detect functional changes in cell surface proteins.

We primarily focused on endothelial cells, which form the inner layer of the vasculature, and macrophages, which are responsible for the clearance of pathogens and cell debris. We studied how the inflammatory response of endothelial cells develops and we observed that two completely distinct pro-inflammatory substances provoked a practically identical cellular response. Furthermore, we investigated the effect of blood flow on the function of endothelial cells and concluded that flow drastically affects the deposition of, and the interaction with the basal membrane which is situated directly below the endothelium and supports it.

In addition, we studied the development of monocytes into macrophages, dendritic cells and osteoclasts. Although these cell types serve quite distinct functions, their development was characterized by a group of proteins that changed in a remarkably similar manner for the different cell types.

Finally, we studied the uptake of hemostatic protein Von Willebrand Factor by macrophages and concluded that two proteins collaborate to facilitate this uptake. The research described in this thesis expands our knowledge of the vasculature and elucidates mechanisms involved in cellular responses therein.