Differential TET1/2/3 Protein Expression in Circulating Leukocytes of Statin-Treated Patients with HFrEF

Epigenetic mechanisms, including DNA methylation and hydroxymethylation, contribute to inflammation, cardiac remodelling and progression of heart failure. Ten–Eleven Translocation (TET) dioxygenases are key regulators of these processes, but the impact of statins on TET proteins in human heart failure is not well characterised. We investigated how statin therapy relates to TET1, TET2 and TET3 expression in circulating immune cells in heart failure with reduced ejection fraction (HFrEF). In this cross-sectional study, 106 patients with HFrEF were enrolled; 84 were receiving statins and 22 were not. Intracellular TET1/2/3 protein levels were measured by multiparameter flow cytometry in granulocytes, monocytes and lymphocytes, and clinical and laboratory characteristics were compared between groups. Statin-treated patients had lower NT-proBNP concentrations and lower neutrophil, lymphocyte and monocyte counts, and more often received guideline-directed medical therapy. Statin therapy was associated with a distinct TET expression profile, characterised by higher TET1 and TET3 indices in monocytes and lymphocytes and lower TET2 indices in granulocytes and monocytes. This pattern is compatible with a distinct immune-cell TET expression profile aligned with the anti-inflammatory and reparative profile attributed to statins, and the course of disease. These associations do not establish causality and require prospective validation. TET proteins may form part of an epigenetic signature associated with statin treatment in heart failure and warrant further study as potential biomarkers in larger, prospective cohorts.