High-density lipoprotein cholesterol associated with change in coronary plaque lipid burden assessed by near infrared spectroscopy

Design, Synthesis, and Anti-Inflammatory Evaluation of a Novel PPARδ Agonist with a 4-(1-Pyrrolidinyl)piperidine Structure

Peroxisome proliferator-activated receptor δ (PPARδ) is considered to be a pharmaceutical target to treat metabolic diseases including atherosclerosis, but there is no PPARδ agonist available for clinical use. We have previously reported the discovery of piperidinyl/piperazinyl benzothiazole derivatives as a new series of PPARδ agonists using docking-based virtual screening methods. In the present study, we found that introduction of a pyrrolidine group into the 4-position of their central piperidine rings enhances hPPARδ activity and subtype selectivity. This led to the discovery of 21 having strong PPARδ agonist activity (EC50 = 3.6 nM) with excellent ADME properties. Furthermore, 21 significantly suppressed atherosclerosis progression by 50-60% with reduction of the serum level of MCP-1 in LDLr-KO mice.

The association between circulating lipoprotein subfractions and lipid content in coronary atheromatous plaques assessed by near-infrared spectroscopy

Background

Lipid content in coronary atheromatous plaques, measured by near-infrared spectroscopy (NIRS), can predict the risk of future coronary events. Biomarkers that reflect lipid content in coronary plaques may therefore improve coronary artery disease (CAD) risk assessment.

Purpose

We aimed to investigate the association between circulating lipoprotein subfractions and lipid content in coronary atheromatous plaques in statin-treated patients with stable CAD undergoing percutaneous coronary intervention.

Methods

56 patients with stable CAD underwent three-vessel imaging with NIRS when feasible. The coronary artery segment with the highest lipid content, defined as the maximum lipid core burden index within any 4 mm length across the entire lesion (maxLCBI_4mm), was defined as target segment. Lipoprotein subfractions and Lipoprotein a (Lp(a)) were analyzed in fasting serum samples by nuclear magnetic resonance spectroscopy and by standard in-hospital procedures, respectively. Penalized linear regression analyses were used to identify the best predictors of maxLCBI_4mm. The uncertainty of the lasso estimates was assessed as the percentage presence of a variable in resampled datasets by bootstrapping.

Results

Only modest evidence was found for an association between lipoprotein subfractions and maxLCBI_4mm. The lipoprotein subfractions with strongest potential as predictors according to the percentage presence in resampled datasets were Lp(a) (78.1 % presence) and free cholesterol in the smallest high-density lipoprotein (HDL) subfractions (74.3 % presence). When including established cardiovascular disease (CVD) risk factors in the regression model, none of the lipoprotein subfractions were considered potential predictors of maxLCBI_4mm.

Conclusion

In this study, serum levels of Lp(a) and free cholesterol in the smallest HDL subfractions showed the strongest potential as predictors for lipid content in coronary atheromatous plaques. Although the evidence is modest, our study suggests that measurement of lipoprotein subfractions may provide additional information with respect to coronary plaque composition compared to traditional lipid measurements, but not in addition to established risk factors. Further and larger studies are needed to assess the potential of circulating lipoprotein subfractions as meaningful biomarkers both for lipid content in coronary atheromatous plaques and as CVD risk markers.

Associations of plaque morphology and location with Intraplaque neovascularization in the carotid artery by contrast-enhanced ultrasound imaging

Objective

Intraplaque neovascularization (IPN) is a known indicator of plaque vulnerability, and is thus considered a predictor of stroke. The morphology and location of the carotid plaque may be correlated with plaque vulnerability. Therefore, our study aimed to examine the associations of carotid plaque morphology and location with IPN.

Methods

A total of 141 patients with carotid atherosclerosis (mean age, 64.99 ± 10.96 years) who underwent carotid contrast-enhanced ultrasound (CEUS) between November 2021 and March 2022 were retrospectively analyzed. IPN was graded according to the presence and location of microbubbles within the plaque. The association of IPN grade with carotid plaque morphology and location was evaluated using ordered logistic regression.

Results

Of the 171 plaques, 89 (52%) were IPN Grade 0, 21 (12.2%) were Grade 1, and 61 (35.6%) were Grade 2. IPN grade significantly associated with both plaque morphology and location, with higher grades observed among Type III morphology and common carotid artery plaques. Significant negative association was further shown between IPN grade and serum high-density lipoprotein cholesterol (HDL-C) level. Plaque morphology and location, and HDL-C remained significantly associated with IPN grade after adjusting for confounding factors.

Conclusion

The location and morphology of carotid plaques were significantly associated with the IPN grade on CEUS, and therefore show potential as biomarkers for plaque vulnerability. Serum HDL-C was also identified as a protective factor against IPN, and may play a role in the management of carotid atherosclerosis. Our study provided a potential strategy for identification of vulnerable carotid plaques and elucidated the important imaging predictors of stroke.

What Is Hidden Behind Yellow Pixels: from Pathology to Intravascular Imaging of Atherosclerotic Plaque

PURPOSE OF REVIEW

Intravascular imaging systems can identify lipid-rich and vulnerable plaques and help in treatment guidance. The comparability of different intracoronary imaging methods remains unclear. In this paper, we review atherosclerotic plaque pathology, plaque-stabilising effects of different lipid-lowering therapies and usage of intravascular imaging modalities. We present the results of our study in which we evaluated the correlation of the intravascular ultrasound iMAP system (iMAP-IVUS) and near-infrared spectroscopy (NIRS) in the diagnosis of vulnerable coronary plaques.

RECENT FINDINGS

Lipids have an essential contribution to plaque evolution and vulnerability. Increase in plaque vulnerability alone even without increase in plaque burden defines progression of atherosclerosis. Lipidic tissue has a significant diagnostic value in patient risk stratification and can serve as a treatment target. Different vulnerable plaque parameters can be visualised with iMAP-IVUS and NIRS. Intravascular imaging systems can differ with regard to their sensitivity, specificity and limitations. Lipid-lowering therapy is crucial in plaque stabilisation.

Low-density lipoproteins cause atherosclerotic cardiovascular disease: pathophysiological, genetic, and therapeutic insights: a consensus statement from the European Atherosclerosis Society Consensus Panel

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Omega-3 fatty acids ameliorate vascular inflammation: A rationale for their atheroprotective effects

BACKGROUND AND AIMS

Clinical trials have demonstrated reductions in major adverse cardiovascular events with purified high-dose eicosapentaenoic acid (EPA), independent of effects on lipids. We aimed to investigate whether omega-3 fatty acids reduce vascular inflammation, a critical mediator of atherosclerosis, and hypothesised that EPA is superior to docosahexaenoic acid (DHA).

METHODS

In a double-blind randomised controlled trial and cell-culture study, 40 healthy volunteers were supplemented with 4 g daily of either EPA, DHA, fish oil (2:1 EPA:DHA), or placebo for 30 days. Serum was incubated with TNF-stimulated human umbilical vein endothelial cells (HUVECs), and markers of acute vascular inflammation (AVI) were measured. The effects of EPA, DHA (600 mg/kg/day), olive oil, or no treatment were also measured in preclinical models of [1] AVI using a periarterial collar (C57Bl/6J; n = 40 mice) and [2] atherosclerosis where ApoE^-/- mice (n = 40) were fed a 16-week atherogenic diet.

RESULTS

EPA supplementation reduced expression of C-C motif chemokine ligand 2 (CCL2) by 25% compared to placebo (p = 0.03). In the AVI model, EPA reduced vascular expression of VCAM1 by 43% (p = 0.02) and CCL2 by 41% (p = 0.03). Significant inverse correlations were observed between EPA levels and vascular expression of VCAM1 (r = -0.56, p = 0.001) and CCL2 (r = -0.56, p = 0.001). In ApoE^-/- mice, EPA reduced aortic expression of Il1b by 44% (p = 0.04) and Tnf by 49% (p = 0.04), with similar inverse correlations between EPA levels and both Il1b (r = -0.63, p = 0.009) and Tnf (r = -0.50, p = 0.04).

CONCLUSIONS

Supplementation with EPA, more so than DHA, ameliorates acute and chronic vascular inflammation, providing a rationale for the cardiovascular benefit observed with high dose omega-3 fatty acid administration.

Coronary plaque volume and predictors for fast plaque progression assessed by serial coronary CT angiography-A single-center observational study

PURPOSE

The rationale of this study was to identify patients with fast progression of coronary plaque volume PV and characterize changes in PV and plaque components over time.

METHOD

Total PV (TPV) was measured in 350 patients undergoing serial coronary computed tomography angiography (median scan interval 3.6 years) using semi-automated software. Plaque morphology was assessed based on attenuation values and stratified into calcified, fibrous, fibrous-fatty and low-attenuation PV for volumetric measurements. Every plaque was additionally classified as either calcified, partially calcified or non-calcified.

RESULTS

In total, 812 and 955 plaques were detected in the first and second scan. Mean TPV increase was 20 % on a per-patient base (51.3 mm³ [interquartile range (IQR): 14.4, 126.7] vs. 61.6 mm³ [IQR: 16.7, 170.0]). TPV increase was driven by calcified PV (first scan: 7.6 mm³ [IQR: 0.2, 33.6] vs. second scan: 16.6 mm³ [IQR: 1.8, 62.1], p < 0.01). Forty-two patients showed fast progression of TPV, defined as >1.3 mm³ increase of TPV per month. Male sex (odds ratio 3.1, p = 0.02) and typical angina (odds ratio 3.95, p = 0.03) were identified as risk factors for fast TPV progression, while high-density lipoprotein cholesterol had a protective effect (odds ratio per 10 mg/dl increase of HDL cholesterol: 0.72, p < 0.01). Progression to >50 % stenosis at follow-up was observed in 34 of 327 (10.4 %) calcified plaques, in 13 of 401 (3.2 %) partially calcified plaques and 2 of 221 (0.9 %) non-calcified plaques (p < 0.01).

CONCLUSION

Fast plaque progression was observed in male patients and patients with typical angina. High HDL cholesterol showed a protective effect.

Associations of ABCG1-mediated cholesterol efflux capacity with coronary artery lipid content assessed by near-infrared spectroscopy

Background

Although high-density lipoprotein (HDL) has atheroprotective properties, the association of HDL functionality with coronary plaques remains unclear.

Methods

We investigated the association between HDL-mediated cholesterol efflux capacity (CEC) and coronary lipid burden in 74 patients who underwent near-infrared spectroscopy (NIRS) imaging for acute coronary syndrome (ACS) or stable ischemic symptoms. We measured baseline HDL-mediated CEC, distinguishing the specific pathways, and stratified patients according to their median CEC values. Coronary lipid burden was assessed as lipid core burden index (LCBI) using NIRS at baseline (n=74) and on serial imaging (n=47).

Results

Patients with baseline ATP-binding cassette transporter G1 (ABCG1)-mediated CEC > median had a greater baseline LCBI {74 [20, 128] vs. 32 [5, 66]; P=0.04} or change in LCBI {-30 [-89, 0] vs. -3 [-16, 0]; P=0.048}. In addition to a negative association between baseline LCBI and change in LCBI (standardized β=-0.31; P=0.02), multivariable analysis demonstrated a significant interaction effect between clinical presentation of coronary artery disease (CAD) and baseline ABCG1-mediated CEC on change in LCBI (P=0.003), indicating that baseline ABCG1-mediated CEC was inversely associated with change in LCBI in patients with ACS (standardized β=-0.79, P=0.003), but not in those with stable ischemic symptoms (P=0.52).

Conclusions

In this study, ABCG1-mediated CEC, but not ATP-binding cassette transporter A1 and scavenger receptor B type I, was associated with regression of coronary artery lipid content, especially in patients with high-risk phenotype. Further studies are required to determine the roles of ABCG1 pathway in the development coronary plaques.

Intracoronary near-infrared spectroscopy and the risk of future cardiovascular events

Objectives

The objectives of this study were to investigate if findings by intracoronary near-infrared spectroscopy (NIRS) and intravascular ultrasound (IVUS) are associated with future cardiovascular events and if NIRS can differentiate culprit from non-culprit segments in patients with coronary artery disease.

Methods

The study included 144 patients with coronary artery disease undergoing percutaneous coronary intervention and combined NIRS-IVUS imaging at two Swedish hospitals. The NIRS-derived lipid core burden index (LCBI), the 4 mm segment with maximum LCBI (MaxLCBI4mm) and the IVUS-derived maximum plaque burden (MaxPB) were analysed within the culprit segment and continuous 10 mm non-culprit segments of the index culprit vessels. The association with future major adverse cardiovascular and cerebrovascular events (MACCE), defined as all-cause mortality, acute coronary syndrome requiring revascularisation and cerebrovascular events during follow-up was evaluated using multivariable Cox regressions. A receiver operating characteristic (ROC) analysis was performed to test the ability of NIRS to discriminate culprit against non-culprit segments.

Results

A non-culprit maxLCBI4mm ≥400 (HR: 3.67, 95% CI 1.46 to 9.23, p=0.006) and a non-culprit LCBI ≥ median (HR: 3.08, 95% CI 1.11 to 8.56, p=0.031) were both significantly associated with MACCE, whereas a non-culprit MaxPB ≥70% (HR: 0.61, 95% CI 0.08 to 4.59, p=0.63) was not. The culprit segments had larger lipid cores compared with non-culprit segments (MaxLCBI4mm 425 vs 74, p<0.001), and the ROC analysis showed that NIRS can differentiate culprit against non-culprit segments (c-statistics: 0.85, 95% CI 0.81 to 0.89).

Conclusion

A maxLCBI4mm ≥400 and LCBI ≥ median, assessed by NIRS in non-culprit segments of a culprit artery, were significantly associated with patient-level MACCE. NIRS furthermore adequately discriminated culprit against non-culprit segments in patients with coronary disease.

Translating Evidence of HDL and Plaque Regression

Considerable evidence from preclinical and population studies suggests that HDLs (high-density lipoproteins) possess atheroprotective properties. Reports from HDL infusion studies in animals and early clinical imaging trials reported evidence of plaque regression. These findings have stimulated further interest in developing new agents targeting HDL. However, the results of more recent imaging studies in the setting of high-intensity statin use have been disappointing. As the concept of plaque changes with HDL therapeutics evolves and imaging technology to evaluate these effects advances, there will become increasing opportunity to determine the effects of HDL agents on atherosclerotic plaque (Graphic Abstract).

Lipid lowering drugs and inflammatory changes: an impact on cardiovascular outcomes?

Inflammatory changes are responsible for maintenance of the atherosclerotic process and may underlie some of the most feared vascular complications. Among the multiple mechanisms of inflammation, the arterial deposition of lipids and particularly of cholesterol crystals is the one responsible for the activation of inflammasome NLRP3, followed by the rise of circulating markers, mainly C-reactive protein (CRP). Elevation of lipoproteins, LDL but also VLDL and remnants, associates with increased inflammatory changes and coronary risk. Lipid lowering medications can reduce cholesterolemia and CRP: patients with elevations of both are at greatest cardiovascular (CV) risk and receive maximum benefit from therapy. Evaluation of the major drug series indicates that statins exert the largest LDL and CRP reduction, accompanied by reduced CV events. Other drugs, mainly active on the triglyceride/HDL axis, for example, PPAR agonists, may improve CRP and the lipid pattern, especially in patients with metabolic syndrome. PCSK9 antagonists, the newest most potent medications, do not induce significant changes in inflammatory markers, but patients with the highest baseline CRP levels show the best CV risk reduction. Parallel evaluation of lipids and inflammatory changes clearly indicates a significant link, both guiding to patients at highest risk, and to the best pharmacological approach. Key messages Lipid lowering agents with "pleiotropic" effects provide a more effective approach to CV prevention In CANTOS study, patients achieving on-treatment hsCRP concentrations ≤2 mg/L had a higher benefit in terms of reduction in major CV events The anti-inflammatory activity of PCSK9 antagonists appears to be of a minimal extent.

Impact of the triglyceride level on coronary plaque components in female patients with coronary artery disease treated with statins

Several studies have reported that elevated triglyceride (TG) levels may be more strongly associated with an increased risk of coronary artery disease (CAD) in females than in males. We examined gender differences in the relationship between TG levels and coronary atherosclerosis using integrated backscatter intravascular ultrasound (IB IVUS) in CAD patients treated with statins. Three hundred seventy-eight CAD patients (105 females and 273 males) who underwent percutaneous coronary intervention using IB IVUS, and who were already receiving statin treatment, were included. Gray-scale and IB IVUS examinations were performed for the non-culprit segment of a coronary artery and fasting serum TG concentrations were measured. We found that TG levels were significantly correlated with increased lipid (r = 0.40, p < 0.001) and decreased fibrous (r = - 0.37, p < 0.001) plaque components in females, but not in males. Low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels were not related to either the gray-scale or IB IVUS parameters in both genders. After adjustment for conventional coronary risk factors by a multivariate stepwise regression analysis, higher TG levels in females were independently associated with increased lipid (β = 0.31, p< 0.001) contents in coronary plaques. In conclusion, among CAD patients treated with statins, TG levels were associated with lipid-rich coronary plaques in females, but not in males. TG levels may be more important indicators of residual risk after statin treatment in females than in males.