Dr Jason Johnson from the Bristol Heart Institute has been awarded a major Fellowship from the British Heart Foundation. These Fellowships are awarded to outstanding young scientists to help them become independent researchers. Dr Johnson was awarded over £365,000 for four years, which includes salary for a technician.

Dr Johnson’s research focuses on the process of atherosclerosis – the buildup of fatty material on the lining of arteries to form ‘plaques’ that can partially block blood flow. Heart attacks and strokes are primarily caused by cracking of these plaques, triggering the formation of a blood clot that can completely block the blood vessel – starving the heart or brain of blood and oxygen. Exactly what causes the plaques to rupture is unknown, and forms the basis of Dr Johnson’s Fellowship.

The fatty material forming the plaque consists of different types of cell. One of them – macrophages – may also contribute to their cracking. Dr Johnson recently found that the macrophages exist in several forms, some having good effects and some bad upon plaque formation and cracking. The ‘bad’ macrophages have a greater capacity to divide into more cells and increase the size of the plaque; they may also trigger death of smooth muscle cells that normally stabilise the plaques.

Dr Johnson will investigate why some plaques have a high number of the ‘bad’ macrophages, and also hopes to identify markers in blood and tissues that may reveal whether a patient is at risk of plaque rupture, and hence of having a heart attack or stroke. He has already found that the ‘bad’ macrophages contain high levels of a particular enzyme which might not only be one of the causes of plaque cracking but also serve as a marker for it.

Patients thought to be at risk could then be tested for presence of the marker and protective measures undertaken – for example, anticoagulant treatment to prevent clotting after rupture. Dr Johnson is also investigating methods of stabilising the plaques to prevent rupture in the first place.