Can neutrophil microvesicles influence the phenotype of monocytes - linking systemic inflammation with heart disease

Cardiovascular disease (CVD) remains the leading cause of death worldwide. Atherosclerosis, the build up of fibro-fatty plaques in the wall of arteries, is the underlying cause of the heart attack and stroke. It is a chronic inflammatory disease characteristed by inappropriate recruitment of leukocytes, particularly monocytes, to the vessel wall. Monocytes play a major role in normal host defence, patrolling the vasculature for injury or invasion, clearing away dead cells and debris and promoting normal healing. Monocytes are recruited to sites of inflammation where they can engulf dead cells but can also differentiate into macrophages. In atherosclerosis, these macrophages take up modified lipid becoming foam cells, which leads to further propagation of the disease. Clinical evidence underpinning the role of inflammation in atherosclerosis has increased the interest in developing anti-inflammatory therapies for this disease, such as canakinumab as described in the CANTOS trial.

Despite inflammation being involved in atherosclerosis, the most abundant inflammatory cell in humans, the neutrophil, is not present in atherosclerotic lesions. However, we have recently found that neutrophil microvesicles, small membrane bound sacs released from the surface of cells containing proteins and micro-RNA, that act as a “MiniMe” of the cell and are able to influence the development of atherosclerosis and the recruitment of monocytes to the vessel wall (Gomez et al. Nature Commun. 2020). We have investigated the effects of these microvesicles on inflammatory activation of endothelial cells extensively but have not yet investigated any direct effects on monocytes.

You will test the hypothesis that neutrophil microvesicles can regulate the inflammatory phenotype of monocytes.

You will isolate primary human cells to investigate changes in monocyte phenotype induced by microvesicles by looking at markers on their surface using flow cytometry and release of secreted proteins using ELISA. To determine microvesicle concentration and purity you will use flow cytometry, nanoparticle tracking and electron microscopy. You will also investigate whether monocytes can internalize fluorescently labelled neutrophil microvesicles using confocal microscopy and determine the pathways involved. Using our biobank of plaque samples, you will also investigate whether microvesicles can affect monocyte phenotype in vivo.