Inflammation and Infective Endocarditis

Infective endocarditis (IE) is challenging to diagnose despite modern, multi-modality imaging techniques. Its frequency is increasing as more interventions are performed on patients with pre-existing valve disease. Current strategies for diagnosis and management are relatively historical; patients require positive blood cultures and are managed with intravenous antibiotics and cardiac surgery. While the immunological complications of IE are well recognised (e.g. rheumatoid factor positivity), there has been very little research to explore the immune system's role in disease onset and progression. The investigators laboratory has discovered and characterised a group of circulating immune cells (cMET+ T-cells) that appear to have a direct role in the progression of another inflammatory heart disease known as myocarditis. Pilot data from the investigators laboratory (n=3 patients) suggests that these cells are also detectable in explanted valve tissue from patients undergoing endocarditis surgery. The investigators suspect that the presence of these cells in IE implies that there may be a significant contribution to disease progression from the immune system. It is possible that the exposure of cardiac proteins by damage caused by a bacterial infection primes the immune system against self, and that these auto-reactive T-cells then go on to attack and destroy native valve tissue. The investigators would like to investigate whether circulating and myocardial cMET+ T-cells are detectable across the wide spectrum of patients with IE and further explore their role in this condition. The investigators are planning to functionally characterise both circulating cells and those that are detectable in explanted valve tissue using a combination of flow cytometry and spatial RNA sequencing. The investigators propose that cMET+ T-cells may have utility in the diagnosis of IE and that in patients with a significantly elevated number, the investigators might be able to offer novel (and highly specific) targeted immunological therapy that could improve patient outcomes.