Welcome to the EAS 2021 Interactive Program
The congress will officially run on EEST time zone (Eastern European Summer Time, Helsinki, CET+1)
Introduction (ID 1583)
Mechanisms of acute coronary syndromes (ID 1309)
Are mastcells welcomed in the atherosclerotic lesions? (ID 1308)
Humoral immune responses in the artery wall. (ID 1307)
O033 - CHIP mutations mediate human atherosclerosis by activating monocyte pro-inflammatory pathways without evidently promoting monocyte chemotaxis (ID 713)
Abstract
Background and Aims
Clonal hematopoiesis of indeterminate potential (CHIP) is an age‑associated expansion of blood cells that carry specific somatic mutations. CHIP mutations double the risk of CAD and are associated with worse overall survival. Our research aims to understand how CHIP mutations change the myeloid cell biology and contribute to atherosclerosis.
Methods
We screened 812 patients admitted for left heart coronary angiography in University Heart Center Freiburg and conducted targeted genomic sequencing to identify CHIP carriers. We applied single‑cell gDNA/mRNA parallel sequencing to perform intra‑individual comparison of gene expression in monocytes carrying DNMT3A H882 hotspot mutation and that in non‑mutated monocytes.
Results
The prevalence of CHIP mutation was at least two times higher in all age groups of our cohort than that of general population. Middle‑aged (age of 40 to 69) patients with mutations in the two most common CHIP genes, DNMT3A and TET2, had significantly higher burden of CAD than those without CHIP mutations. Single‑cell RNA profiling revealed that monocytes with DNMT3A H882C mutation formed separate clusters and distinctively increased the expression of genes that regulate IFNγ, IL‑6, IL‑12, and TNF production or response. Genes regulating monocyte chemotaxis was not differentially expressed in mutated monocytes.
Conclusions
We confirmed the enhanced risk of CAD associated with CHIP mutations. With single‑cell gDNA/RNA parallel sequencing, we demonstrated the direct effect of CHIP mutation on monocyte biology, avoiding inter‑individual variation. DNMT3A H882C mutation altered gene expression of monocytes and activated pro‑inflammatory pathways without noticeable influences on monocyte chemotaxis.
O034 - Deficiency of myeloid phd proteins aggravates atherogenesis via macrophage apoptosis and paracrine fibrotic signaling (ID 1187)
Abstract
Background and Aims
Atherosclerotic plaque hypoxia is detrimental for macrophage function. Prolyl hydroxylases (PHDs) initiate cellular hypoxic responses, possibly influencing macrophage function in plaque hypoxia. Thus, we elucidated the role of myeloid PHDs in atherosclerosis.
Methods
Myeloid specific PHD knockout (PHDko) mice were fed high cholesterol diet for 6-12 weeks to induce atherosclerosis. Plaque parameters, e.g. plaque size and macrophage content, were analyzed. Bulk and single cell RNA sequencing was performed on PHD2 BMDMs and plaque macrophages, respectively.
Results
Aortic root plaque size was augmented 2.6fold in PHD2cko, and 1.4-fold in PHD3ko, but not in PHD1ko mice compared to controls. Macrophage apoptosis was promoted in PHD2cko and PHD3ko mice in vitro and in vivo, via the HIF1α/BNIP3 axis. Bulk and single cell RNA data of PHD2cko bone-marrow-derived macrophages (BMDM) and plaque macrophages, respectively, confirmed these findings and were validated by siRNA silencing. Human plaque BNIP3 mRNA associated with plaque necrotic core, suggesting similar adverse effects. Further, PHD2cko plaques displayed enhanced fibrosis, independent of macrophage and SMC function. PHD2cko BMDMs enhanced fibroblast collagen secretion in a paracrine manner and in silico analysis of macrophage-fibroblast communication predicted SPP1 signaling as regulator, in line with enhanced plaque SPP1 protein content, and SPP1mRNA in TREM2-foamy plaque macrophages, but not in neutrophils.
Conclusions
Myeloid PHD2cko and PHD3ko enhanced plaque growth, macrophage apoptosis, and PHD2cko activated paracrine collagen secretion by fibroblasts. PHD1 did not seem paramount in myeloid cells in atherogenesis.
O035 - Phosphorylcholine-targeting vaccination reduces experimental atherosclerosis progression by expanding the B1-like specific B cell pool (ID 726)
Abstract
Background and Aims
Vaccination with phosphorylcholine (PC) reduces experimental atherosclerosis by raising the titer of PC-specific IgM in Apolipoprotein E knockout (ApoEKO) mice.
The epitope of the antibodies elicited by the PC-Vaccine coincides with that of 'natural' anti-pneumococcal antibodies and strikingly similar results can be obtained by vaccination with Prevenar®.
The aim of the present study was therefore to assess whether the atheroprotective effects carried by PC-Vaccine and Prevenar@ are linked to the activation of the germline encoded B cell pool, which is responsible for the production of natural antibodies.
Methods
AID Cre mice were crossed with ApoEKO mice and double transgenic mice were immunized with PC-Vaccine or with Prevenar® as previously reported (DOI:10.1016/j.atherosclerosis.2018.06.903). Three months later, atherosclerotic lesions and natural anti-PC IgM antibodies values were compared to the AID+ (affinity maturated) IgM+ (B1-like) cell pool in the peritoneal cavity and draining lymph nodes.
Results
Discriminant analysis showed that the rise of natural anti-PC IgM antibodies (AB1-2 IgM), the proportion of affinity matured (AID+) B1-like cells (CD19+ CD5+ CD43+ CD1d+ IgM+) having migrated from the draining lymph node to the peritoneal cavity and the lesion size (AUC) were interdependent from each other and that atheroprotection in both PC-Vaccine and Prevenar® mouse groups was proportional to the fraction of affinity matured B1-like cells in the peritoneal cavity and the rise of natural anti-PC IgM antibody production (individual data and bivariate plots are displayed in the figure).
Conclusions
Phosphorylcholine-targeting vaccination boosts affinity maturation of B lymphocytes involved in the production of natural antibodies and prevents experimental atherosclerosis progression.