Welcome to the EAS 2023 Interactive Program

Background and Aims

Low Cholesterol efflux capacity (CEC) and elevated levels of IL-1Beta (IL-1β) are strongly and independently associated with cardiovascular outcomes after Myocardial Infarction (MI). Both pathways are currently evaluated as new therapeutic targets in ongoing clinical trials. Animal studies demonstrated that alteration of cholesterol efflux leads to IL-1ß production, suggesting that defective CEC triggers inflammation.

The present study aims to evaluate (1) potential synergetic effect of CEC and IL-1β on recurrent major cardiovascular events (MACE) at one-year after a first MI and (2) the capacity of HDL particles to activate inflammation according to the risk of recurrent MACE.

Methods

CEC and IL-1B levels were measured among 2012 ST-segment elevation MI patients. The association of these biomarkers with the primary outcome of MACE was evaluated at one-year follow-up using a multivariate-cox analysis. In-vitro analyses of HDL functions including anti-inflammatory properties and CEC was evaluated in human THP-1 macrophages.

Results

Patients exhibited both reduced CEC and an elevated level of IL-1β displayed an increased risk of recurrent MACE at one year compared to patients with both high CEC and low IL-1β. HDL particles isolated from highest risk patients exhibited a reduced CEC from macrophages, as well as higher pro-inflammatory properties, as compared to patients at lower risk of recurrent MACE.

Conclusions

Defective CEC and elevated IL-1B increase synergistically the residual cardiovascular risk in MI patients. HDL particles from patients at highest risk of recurrent MACE after MI exhibit defective biological activities. These latter patients may benefit from a dual therapeutic approach targeting both CEC and inflammation.

Background and Aims

Chronic inflammation and immune dysregulation drive atherosclerosis development in rheumatoid arthritis (RA). Recent evidence suggests a link via humoral responses against high-density lipoproteins (HDL). However, their specificity, clinical relevance and emergence along disease course are unknown, especially during the earliest phases of RA.

Methods

IgG and IgM serum levels of antibodies against HDL (anti-HDL) and Apolipoprotein A1 (anti-ApoA1) were measured in 82 early RA patients, 14 arthralgia individuals and 96 controls. Established RA patients (n=42) were included for validation. Atherosclerosis and vascular stiffness were measured by Doppler-ultrasound. Lipoprotein content, particle numbers and size were measured by H-NMR. Cytokines were measured by immunoassays. A cardiometabolic-related protein panel was evaluated using high-throughput targeted proteomics.

Results

Anti-HDL and anti-ApoA1 responses were increased in early RA compared to controls and were comparable to established disease. Only anti-ApoA1 antibodies were increased in arthralgia. IgG anti-HDL and anti-ApoA1 were associated with unfavourable lipoprotein traits in RA and arthralgia, respectively. A similar picture was observed for inflammatory mediators. No associations with clinical features or risk factors were found. IgG anti-HDL were independently associated with atherosclerosis occurrence in early RA, and outperformed patient stratification over conventional algorithms and their anti-ApoA1 counterparts. Anti-HDL antibodies correlated with proteins involved in immune activation, remodelling, and lipid metabolism pathways in early RA.

Conclusions

Humoral responses against HDL particles may be a missing link between inflammation and atherosclerosis along arthritis course, although quantitative and qualitative differences can be noticed. These differences informed distinct capacities as biomarkers and underlying pathogenic circuits.

Background and Aims

Alzheimer’s disease (AD) is the leading cause of dementia with over 50 million affected individuals worldwide. In addition to the well described neuropathological hallmarks; beta-amyloid and neurofirbllary tangles, the role of the cerebrovascular is increasingly recognized in the development of AD. High-density lipoprotein (HDL), possesses several vasoprotective functions and epidemiological studies showed inverse associations between the levels of either apolipoprotein (apo)A-I or HDL-cholesterol with AD risk. Several lines of evidence suggest that HDL reduces AD risk by decreasing both beta-amyloid deposition within the vasculature and inhibiting vascular inflammation. Our group further found that HDL enriched in apoE (HDLE+) is more effective in removing vascular beta-amyloid deposits than those lacking apoE (HDLE-). However, HDL circulating in the blood must first interact with brain endothelial cells (EC) to display its anti-AD functions, a process that remains poorly understood.

Methods

HDL was isolated from plasma of healthy donors by ultracentrifugation before being further fractionated into HDLE⁺ and HDLE^- using an apoE immunoaffinity column.

Results

Using microscopy, HDLE+ and HDLE- were found to partially colocalize, suggesting potential independent trafficking pathways. Further, HDLE+ bound to and was transcytosed through brain EC significantly more than HDLE-. Using RNA interference and pharmacological inhibitions, we showed that HDL binding and association were dependent of scavenger receptor BI (SR-BI) and endothelial lipase. Interestingly, interference of the low-density lipoprotein receptor (LDLR) also reduced HDL internalization but not binding to brain EC.

Conclusions

Together our findings suggest distinct trafficking pathways for HDLE+ and HDLE- through brain EC that might imply different cerebrovascular functions relevant to AD.

Background and Aims

PCSK9 is a serine protease that increases LDL-cholesterol levels due to endosomal and lysosomal degradation of the LDL-receptor. Studies have shown that PCSK9 is attached in all plasma lipoproteins. We investigated the effect of LDL and HDL-associated PCSK9 on platelet aggregation and on endothelial cell activation.

Methods

Washed platelets (WP), isolated from healthy volunteers, were incubated with 0.1mg/ml LDL or HDL in the presence or absence of 2.5μg/ml polyclonal antibody against PCSK9 (anti-PCSK9pAb) and activated with 0.1 units/ml thrombin or 0.25mM AA and monitored using Light Transmittance Aggregometry. Human Umbilical Vein Endothelial Cells (HUVECs) were cultured and pre-incubated with 0.1mg/ml LDL or HDL in the presence or absence of anti-PCSK9pAb for 5min followed by activation with 0.25ng/ml Tumor Necrosis Factor-α (TNF-α) for 6h. Cell activation was studied by flow cytometry for the membrane expression of ICAM-1 (Intercellular Adhesion Molecule-1).

Results

Thrombin and AΑ-induced platelet aggregation was inhibited by 50±19% and 38±11%, respectively in the presence of HDL and by 28±15 and 39±12%, respectively in the presence of LDL. These effects were not significantly influenced in the presence of anti-PCSK9pAb. ICAM-1 membrane expression was inhibited by 49±7.5% and 20±1.7% in the presence of HDL and LDL respectively, whereas these inhibitions were significantly reduced (p<0.05) in the presence of anti-PCSK9pAb by 22±6.9% and 9.2±0.8%, respectively.

Conclusions

HDL and LDL-associated PCSK9 does not affect the inhibitory effect of these lipoproteins on platelet activation whereas it significantly increases their inhibitory effect on inflammatory stimulation of endothelial cells.