👤 Esther Lutgens

The repertoire of adhesion receptors and ligands is supported by molecules, which are primarily recognized for their roles in immunity. We have recently shown that the co-stimulatory molecule CD40 ligand (CD154/CD40L) is pro-atherogenic and serves as an adhesive ligand for cells expressing the integrin Mac-1 (CD11b/CD18). Here, we studied the role of endothelial CD40L in several models of cardiovascular inflammation. We generated mice with an endothelial cell-specific deficiency of CD40L, Bmx-Cre In this functional validation study, we demonstrate that endothelial cell-expressed CD40L serves as an adhesion molecule in different models of acute inflammation in the aortic, peritoneal, mesenteric, and coronary vasculature. CD40L may therefore represent a promising therapeutic target at the interface of adaptive immunity and myeloid inflammation. Show less

High plasma lipoprotein(a) [Lp(a)] levels are associated with accelerated atherosclerosis and subsequent atherosclerotic cardiovascular disease (ASCVD), potentially through enhanced inflammatory signaling of monocytes. Given that monocytes are major players in ASCVD risk and the role of epigenetic changes in regulating their responsiveness, we propose that investigating changes in chromatin accessibility could reveal the underlying mechanisms of enhanced monocyte inflammation. In this observational case-control study, we collected blood from subjects with low (<25 nmol/L) and elevated (>350 nmol/L) plasma Lp(a) with and without a history of ASCVD, matched for age and sex. A total of 60 subjects were included in the study, comprising 60% males and a mean age of 62.8 ± 7.8 years. We assessed gene expression and chromatin accessibility of fluorescence-activated cell sorting (FACS)-sorted classical monocytes using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and bulk assay for transposase-accessible chromatin (ATAC)-sequencing and analyzed plasma cytokine levels. Subjects with high plasma Lp(a) showed significantly increased gene expression of IFIT3. At the plasma level, subjects with high Lp(a) without ASCVD were distinguished by higher concentrations of chemokine C-X-C motif ligand 10 (CXCL10). While these results are consistent with previous research demonstrating increased interferon-γ signaling in monocytes of individuals with elevated Lp(a), we did not detect differences in chromatin accessibility of monocytes between subjects with high or low Lp(a), irrespective of ASCVD status. While subjects with high Lp(a) levels showed enhanced monocyte inflammation, no differences in chromatin accessibility were detected. This suggests that the pro-inflammatory signature of Lp(a) and ASCVD on monocytes is regulated at a level other than chromatin accessibility. Show less

Circadian disturbance (CD) is the consequence of a mismatch between endogenous circadian rhythms, behaviour, and/or environmental cycles, and frequently occurs during shift work. Shift work has been associated with elevated risk for atherosclerotic cardiovascular disease (asCVD) in humans, but evidence for the effectiveness of prevention strategies is lacking. Here, we applied time-restricted feeding (TRF) as a strategy to counteract atherosclerosis development during CD in female APOE∗3-Leiden.CETP mice, a well-established model for humanized lipoprotein metabolism. Control groups were subjected to a fixed 12:12 h light-dark cycle, while CD groups were subjected to 6-h phase advancement every 3 days. Groups had either ad libitum (AL) access to food or were subjected to TRF with restricted food access to the dark phase. TRF did not prevent the increase in the relative abundance of circulating inflammatory monocytes and elevation of (postprandial) plasma triglycerides during CD. Nonetheless, TRF reduced atherosclerotic lesion size and prevented an elevation in macrophage content of atherosclerotic lesions during CD, while it increased the relative abundance of anti-inflammatory monocytes, prevented activation of T cells, and lowered plasma total cholesterol levels and markers of hepatic cholesterol synthesis. These effects were independent of total food intake. We propose that time restricted eating could be a promising strategy for the primary prevention of asCVD risk in shift workers, which warrants future study in humans. This work was funded by the Novo Nordisk Foundation, the Netherlands Ministry of Social Affairs and Employment, Amsterdam Cardiovascular Sciences, and the Dutch Heart Foundation. Show less

Disruption of circadian rhythm by means of shift work has been associated with cardiovascular disease in humans. However, causality and underlying mechanisms have not yet been established. In this study, we exposed hyperlipidemic APOE*3-Leiden.CETP mice to either regular light-dark cycles, weekly 6 hours phase advances or delays, or weekly alternating light-dark cycles (12 hours shifts), as a well-established model for shift work. We found that mice exposed to 15 weeks of alternating light-dark cycles displayed a striking increase in atherosclerosis, with an approximately twofold increase in lesion size and severity, while mice exposed to phase advances and delays showed a milder circadian disruption and no significant effect on atherosclerosis development. We observed a higher lesion macrophage content in mice exposed to alternating light-dark cycles without obvious changes in plasma lipids, suggesting involvement of the immune system. Moreover, while no changes in the number or activation status of circulating monocytes and other immune cells were observed, we identified increased markers for inflammation, oxidative stress, and chemoattraction in the vessel wall. Altogether, this is the first study to show that circadian disruption by shifting light-dark cycles directly aggravates atherosclerosis development. Show less