Prof Johnson has a long-standing interest in the pathophysiology of numerous cardiovascular pathologies including atherosclerosis, aortic aneurysms, and restenosis. His studies include a marriage of basic science and translational cardiovascular research with the goal of facilitating the development and deployment of novel therapies to combat the aforementioned cardiovascular diseases, alongside the identification of potential biomarkers of disease progression.

Research within Professor Johnson’s group has underpinned the dogma that not all matrix metalloproteinases (MMPs) play detrimental roles in the progression of atherosclerosis. Moreover, he has aided the identification of a macrophage phenotype (under the control of GM-CSF) which is characterised by high MMP-12 and MMP-14 protein expression alongside low TIMP-3 levels. Further work has also identified a novel node of microRNA regulation within GM-CSF macrophages, highlighting several potential new therapeutic avenues, including miR-181b inhibition and the selective inhibition of MMP-12. Collectively, these studies have made a major contribution to understanding the role of MMPs and macrophage heterogeneity in atherosclerotic plaque progression. Supporting studies in human aneurysm samples and pertinent pre-clinical in vivo models has reaffirmed the notion that the proteolytic profile of macrophage subsets predicts aneurysm development and progression. These findings are now being tested in a novel ex vivo human model of aneurysm that will hopefully supplant the requirement for animal studies. More recent studies aim at elucidating the contribution of neovascularisation to the progression of cardiovascular diseases.