In WP2, we aimed to detail the effect of cardiovascular risk factors on epigenetic changes in immune cells, establish its impact on atherosclerosis and investigate its therapeutic potential. Our studies have revealed that factors modulating CVD, including diet and exercise indeed affect the proliferative and differentiation capacity of hematopoietic stem and progenitor cells in the bone marrow, and of myeloid cells in lymphoid organs and in the circulation, thereby affecting the outcome of atherosclerosis. Moreover, we have also found that tissue macrophages have their tissue specific function and reactivity, depending on the event or disease. Our studies have revealed novel processes and (epigenetic) modifiers that mediate myeloid cell fate and activation in CVD, and we have investigated the therapeutic potential some of these candidates. Moreover, we have developed a small molecule inhibitor against an important modifier of inflammation (CD40-TRAF6), and were able to show that this drug could decrease atherosclerosis in a laboratory setting. In order to specifically target our new drug to macrophages, we developed a nanomedicinal delivery strategy and could successfully develiver our drug to macrophages and reduce atherosclerosis.
Cells of the innate immune system, including monocytes and macrophages, importantly contribute to the development of atherosclerotic CVD. We recently identified that these cells can build a long-term immunological memory, which is called trained immunity (TI), that results in a pro-atherogenic phenotype. In WP3, we aimed to identify drivers of TI and elucidate underlying mechanisms, including metabolic and epigenetic reprogramming with the ultimate aim to identify novel pharmacological targets. In an in vitro model of trained immunity in human myeloid cells, we identified various relevant stimuli that can induce trained immunity, including oxidized LDL, lipoprotein (a), catecholamines, aldosterone. Using transcriptomic, epigenomic, and metabolic approaches, we identified various metabolic and epigenetic mechanisms that are key to TI which can be used as novel targets for pharmacotherapy. In animal models of athesclerosis, we identified that dyslipidemia and hyperglycemia induces long-term reprogramming of the innate immune system by an effect on bone marrow progenitors. This was validated in humans with dyslipidemia and established atherosclerosis.
In WP4, we first identified a list of SNPs which correlated with trained immunity in monocytes in healthy volunteers. We assessed the predictive value of this ‘epigenetic’ gene risk score on CV-risk in the general population (Copenhagen General Population Study). Of the SNPs associated with trained immunity, none were convincingly associated with CVD-risk. We subsequently evaluated DNA-methylation, which is a more stable sign of epigenetic changes. We also addressed the reversibility of epigenetic remodeling by lowering of ‘traditional’ lipid risk factors in relation to inflammatory activity, assessed as plasma cytokines, immune cell phenotype of circulating cells and vascular wall inflammation. In various patient cohorts, we substantiated a multi-level pro-inflammatory state, ranging from all the way from bone-marrow, plasma immune cells to the arterial wall. In subsequent intervention studies, we were able to unravel the differential regulation of immune cell activation on various target levels. Furthermore we initiated a clinical study to address the impact of an epigenetic modulator on inflammatory activity in humans (oral methylbutyrate intake). In parallel, we conducted a clinical study to investigate the impact of the bromodomain inhibitor (RVX-208) on the inflammatory state in type 2 diabetes mellitus patients.
Monocytes and macrophages play a central role in the pathophysiology of inflammation, as well as in atherosclerosis. In WP5, it was found that these are activated in rheumatoid arthritis (RA), to massively infiltrate synovial tissues and produce tumour necrosis factor-alfa (TNF-alfa). Similarly, in atherosclerosis, macrophages are activated and produce TNF-alfa. Accordingly, therapies aimed at blocking this cytokine have emerged as a major tool in the treatment of RA. Most DAMPs in inflammatory diseases are TLR2- and TLR4-ligands and according to the current concept, repeated stimuli would result in tolerance.
