Purpose of review: The two major challenges in cardiovascular medicine are to refine risk prediction and to improve pharmacological prevention and treatment. The concept of innate immune memory, which is called trained immunity, has the potential to improve clinical practice in these regards.
Recent findings: Monocytes and macrophages have the capability to develop a long-term proinflammatory and proatherogenic phenotype after brief exposure to inflammatory stimuli, such as oxidized low-density lipoprotein particles. This innate immune memory develops because of rewiring of intracellular metabolic pathways and epigenetic reprogramming of histone modifications. The persistence of circulating hyperresponsive monocytes in vivo is explained by the fact that training occurs in myeloid progenitor cells in the bone marrow. Several recent studies reported the presence of monocytes with a trained immune phenotype in patients with established atherosclerosis, and in patients with an increased risk for atherosclerosis because of dyslipoproteinemia.
Summary: In monocytes and their bone marrow progenitors, metabolic and epigenetic reprogramming can induce trained immunity, which might contribute to the persistent nonresolving inflammation that characterizes atherosclerosis. These pathways offer exciting novel drug targets to improve the prevention and treatment of cardiovascular disease.