Rapid regression of atherosclerosis: insights from the clinical and experimental literature

Advances in medical polyesters for vascular tissue engineering

Blood vessels are highly dynamic and complex structures with a variety of physiological functions, including the transport of oxygen, nutrients, and metabolic wastes. Their normal functioning involves the close and coordinated cooperation of a variety of cells. However, adverse internal and external environmental factors can lead to vascular damage and the induction of various vascular diseases, including atherosclerosis and thrombosis. This can have serious consequences for patients, and there is an urgent need for innovative techniques to repair damaged blood vessels. Polyesters have been extensively researched and used in the treatment of vascular disease and repair of blood vessels due to their excellent mechanical properties, adjustable biodegradation time, and excellent biocompatibility. Given the high complexity of vascular tissues, it is still challenging to optimize the utilization of polyesters for repairing damaged blood vessels. Nevertheless, they have considerable potential for vascular tissue engineering in a range of applications. This summary reviews the physicochemical properties of polyhydroxyalkanoate (PHA), polycaprolactone (PCL), poly-lactic acid (PLA), and poly(lactide-co-glycolide) (PLGA), focusing on their unique applications in vascular tissue engineering. Polyesters can be prepared not only as 3D scaffolds to repair damage as an alternative to vascular grafts, but also in various forms such as microspheres, fibrous membranes, and nanoparticles to deliver drugs or bioactive ingredients to damaged vessels. Finally, it is anticipated that further developments in polyesters will occur in the near future, with the potential to facilitate the wider application of these materials in vascular tissue engineering.

Atherosclerosis Progression in the APPLE Trial Can Be Predicted in Young People With Juvenile-Onset Systemic Lupus Erythematosus Using a Novel Lipid Metabolomic Signature

OBJECTIVE

Patients with juvenile-onset systemic lupus erythematosus (JSLE) have increased atherosclerosis risk. This study investigated novel atherosclerosis progression biomarkers in the Atherosclerosis Prevention in Pediatric Lupus Erythematosus (APPLE) trial, the largest investigator-led randomized control trial of atorvastatin versus placebo for atherosclerosis progression in JSLE, using carotid intima-media thickness (CIMT) as the primary outcome.

METHODS

Unsupervised clustering of baseline CIMT and CIMT progression over 36 months was used to stratify patients with JSLE. Disease characteristics, cardiovascular risk scores, and baseline serum metabolome were investigated in CIMT-stratified patients. Machine learning techniques were used to identify and validate a serum metabolomic signature of CIMT progression.

RESULTS

Baseline CIMT stratified patients with JSLE (N = 151) into three groups with distinct high, intermediate, and low CIMT trajectories irrespective of treatment allocation, despite most patients having low cardiovascular disease risk based on recommended assessment criteria. In the placebo group (n = 60), patients with high versus low CIMT progression had higher total (P = 0.001) and low-density lipoprotein (LDL) (P = 0.002) cholesterol levels, although within the reference range. Furthermore, a robust baseline metabolomic signature predictive of high CIMT progression was identified in the placebo arm (area under the curve, 80.7%). Patients treated with atorvastatin (n = 61) had reduced LDL cholesterol levels after 36 months, as expected; however, despite this, 36% still had high atherosclerosis progression, which was not predicted by metabolomic biomarkers, suggesting nonlipid drivers of atherosclerosis in JSLE with management implications for this subset of patients.

CONCLUSION

Significant baseline heterogeneity and distinct subclinical atherosclerosis progression trajectories exist in JSLE. Metabolomic signatures can predict atherosclerosis progression in some patients with JSLE with relevance for clinical trial stratification.

Specialized pro-resolving mediators in vascular inflammation and atherosclerotic cardiovascular disease

Timely resolution of the acute inflammatory response (or inflammation resolution) is an active, highly coordinated process that is essential to optimal health. Inflammation resolution is regulated by specific endogenous signalling molecules that function as 'stop signals' to terminate the inflammatory response when it is no longer needed; to actively promote healing, regeneration and tissue repair; and to limit pain. Specialized pro-resolving mediators are a superfamily of signalling molecules that initiate anti-inflammatory and pro-resolving actions. Without an effective and timely resolution response, inflammation can become chronic, a pathological state that is associated with many widely occurring human diseases, including atherosclerotic cardiovascular disease. Uncovering the mechanisms of inflammation resolution failure in cardiovascular diseases and identifying useful biomarkers for non-resolving inflammation are unmet needs. In this Review, we discuss the accumulating evidence that supports the role of non-resolving inflammation in atherosclerosis and the use of specialized pro-resolving mediators as therapeutic tools for the treatment of atherosclerotic cardiovascular disease. We highlight open questions about therapeutic strategies and mechanisms of disease to provide a framework for future studies on the prevention and treatment of atherosclerosis.

Eradicating Atherosclerotic Events by Targeting Early Subclinical Disease: It Is Time to Retire the Therapeutic Paradigm of Too Much, Too Late

Recent decades have seen spectacular advances in understanding and managing atherosclerotic cardiovascular disease, but paradoxically, clinical progress has stalled. Residual risk of atherosclerotic cardiovascular disease events is particularly vexing, given recognized lifestyle interventions and powerful modern medications. Why? Atherosclerosis begins early in life, yet clinical trials and mechanistic studies often emphasize terminal, end-stage plaques, meaning on the verge of causing heart attacks and strokes. Thus, current clinical evidence drives us to emphasize aggressive treatments that are delayed until patients already have advanced arterial disease. I call this paradigm "too much, too late." This brief review covers exciting efforts that focus on preventing, or finding and treating, arterial disease before its end-stage. Also included are specific proposals to establish a new evidence base that could justify intensive short-term interventions (induction-phase therapy) to treat subclinical plaques that are early enough perhaps to heal. If we can establish that such plaques are actionable, then broad screening to find them in early midlife individuals would become imperative-and achievable. You have a lump in your coronaries! can motivate patients and clinicians. We must stop thinking of a heart attack as a disease. The real disease is atherosclerosis. In my opinion, an atherosclerotic heart attack is a medical failure. It is a manifestation of longstanding arterial disease that we had allowed to progress to its end-stage, despite knowing that atherosclerosis begins early in life and despite the availability of remarkably safe and highly effective therapies. The field needs a transformational advance to shift the paradigm out of end-stage management and into early interventions that hold the possibility of eradicating the clinical burden of atherosclerotic cardiovascular disease, currently the biggest killer in the world. We urgently need a new evidence base to redirect our main focus from terminal, end-stage atherosclerosis to earlier, and likely reversible, human arterial disease.

Diagnostics of atherosclerosis: Overview of the existing methods

Atherosclerosis was and remains an extremely common and serious health problem. Since the elderly are most at risk of cardiovascular risk, and the average life expectancy is increasing, the spread of atherosclerosis and its consequences increases as well. One of the features of atherosclerosis is its asymptomaticity. This factor makes it difficult to make a timely diagnosis. This entails the lack of timely treatment and even prevention. To date, in the arsenal of physicians, there is only a limited set of methods to suspect and fully diagnose atherosclerosis. In this review, we have tried to briefly describe the most common and effective methods for diagnosing atherosclerosis.

Posing the rationale for synthetic lipoxin mimetics as an adjuvant treatment to gold standard atherosclerosis therapies

Atherosclerosis is a progressive, multifactorial inflammatory, and dyslipidaemic disease, responsible for the majority of cardiovascular diseases globally. The chronic inflammation is the main driver of the initiation and progression of such disease, as a result of an imbalanced lipid metabolism and an ineffective immune response to attenuate the inflammatory component. The importance of inflammation resolution is being increasingly recognised in atherosclerosis and cardiovascular disease. It has a complex mechanism consisting of multiple stages, including restoring an effective removal of apoptotic bodies (efferocytosis) and their degradation (effero-metabolism), a macrophage phenotype switching towards resolving phenotypes, and the promotion of tissue healing and regeneration. The low-grade inflammation associated with atherosclerosis development is a driving force in disease exacerbation, and hence inflammation resolution is a key area of research. In this review, we explore the complex disease pathogenesis and its many contributing factors to gain a greater understanding of the disease and identify the current and potential therapeutic targets. First-line treatments and their efficacy will also be discussed in detail, to highlight the emerging field of resolution pharmacology. Despite the great efforts made by current gold-standard treatments, such as lipid-lowering and glucose-lowering drugs, they remain ineffective at tackling residual inflammatory risk and residual cholesterol risk. Resolution pharmacology represents a new era of atherosclerosis therapy, as endogenous ligands associated with inflammation resolution are exploited for their pharmacological benefits in a more potent and longer-acting manner. Novel FPR2-agonists, such as synthetic lipoxin analogues, provide an exciting new approach to enhance the pro-resolving response of the immune system and subsequently end the pro-inflammatory response to allow for an anti-inflammatory and pro-resolving environment for tissue healing, regeneration, and return to homeostasis.

There is urgent need to treat atherosclerotic cardiovascular disease risk earlier, more intensively, and with greater precision: A review of current practice and recommendations for improved effectiveness

Atherosclerotic cardiovascular disease (ASCVD) is epidemic throughout the world and is etiologic for such acute cardiovascular events as myocardial infarction, ischemic stroke, unstable angina, and death. ASCVD also impacts risk for dementia, chronic kidney disease peripheral arterial disease and mobility, impaired sexual response, and a host of other visceral impairments that adversely impact the quality and rate of progression of aging. The relationship between low-density lipoprotein cholesterol (LDL-C) and risk for ASCVD is one of the most highly established and investigated issues in the entirety of modern medicine. Elevated LDL-C is a necessary condition for atherogenesis induction. Basic scientific investigation, prospective longitudinal cohorts, and randomized clinical trials have all validated this association. Yet despite the enormous number of clinical trials which support the need for reducing the burden of atherogenic lipoprotein in blood, the percentage of high and very high-risk patients who achieve risk stratified LDL-C target reductions is low and has remained low for the last thirty years. Atherosclerosis is a preventable disease. As clinicians, the time has come for us to take primordial and primary prevention more serously. Despite a plethora of therapeutic approaches, the large majority of patients at risk for ASCVD are poorly or inadequately treated, leaving them vulnerable to disease progression, acute cardiovascular events, and poor aging due to loss of function in multiple visceral organs. Herein we discuss the need to greatly intensify efforts to reduce risk, decrease disease burden, and provide more comprehensive and earlier risk assessment to optimally prevent ASCVD and its complications. Evidence is presented to support that treatment should aim for far lower goals in cholesterol management, should take into account many more factors than commonly employed today and should begin significantly earlier in life.

Loss of PRMT2 in myeloid cells in normoglycemic mice phenocopies impaired regression of atherosclerosis in diabetic mice

The regression, or resolution, of inflammation in atherosclerotic plaques is impaired in diabetes. However, the factors mediating this effect remain incomplete. We identified protein arginine methyltransferase 2 (PRMT2) as a protein whose expression in macrophages is reduced in hyperglycemia and diabetes. PRMT2 catalyzes arginine methylation to target proteins to modulate gene expression. Because PRMT2 expression is reduced in cells in hyperglycemia, we wanted to determine whether PRMT2 plays a causal role in the impairment of atherosclerosis regression in diabetes. We, therefore, examined the consequence of deleting PRMT2 in myeloid cells during the regression of atherosclerosis in normal and diabetic mice. Remarkably, we found significant impairment of atherosclerosis regression under normoglycemic conditions in mice lacking PRMT2 (Prmt2^-/-) in myeloid cells that mimic the decrease in regression of atherosclerosis in WT mice under diabetic conditions. This was associated with increased plaque macrophage retention, as well as increased apoptosis and necrosis. PRMT2-deficient plaque CD68+ cells under normoglycemic conditions showed increased expression of genes involved in cytokine signaling and inflammation compared to WT cells. Consistently, Prmt2^-/- bone marrow-derived macrophages (BMDMs) showed an increased response of proinflammatory genes to LPS and a decreased response of inflammation resolving genes to IL-4. This increased response to LPS in Prmt2^-/- BMDMs occurs via enhanced NF-kappa B activity. Thus, the loss of PRMT2 is causally linked to impaired atherosclerosis regression via a heightened inflammatory response in macrophages. That PRMT2 expression was lower in myeloid cells in plaques from human subjects with diabetes supports the relevance of our findings to human atherosclerosis.

The future Landscape of macrophage research in cardiovascular disease: a bibliometric analysis

Cardiovascular disease (CVD) refers to a group of diseases involving the heart or blood vessels and is currently the leading cause of morbidity and mortality in many countries around the world and poses a serious economic burden. Macrophages are key effectors of inflammatory and innate immune responses, and their aberrant expression contributes to the development of various types of CVD.This study retrieved articles published from 1990-2022 on macrophages in CVD from the Web of Science core collection, based on CiteSpace and VOSviewer on these literature The annual output, countries and regions, institutions, authors, core journals, keywords and co-cited literature were analyzed. A total of 7,197 articles and reviews were retrieved, with a general upward trend despite slight fluctuations in annual publications. Europe, the United States and Asia are the main countries and regions publishing articles, especially the United States, with the highest number of articles (2,581), citations (173,692) and H-index (197), which also has the world's largest number of elite institutions, professional The country also has the world's largest number of elite institutions, professional researchers and high-impact journals, and is the leading country in this field of research. Keywords "inflammation", "immunology", "autophagy", "lipid-peroxidation" are the main pathogenesis of CVD caused by macrophages. "NLRP3", "nf kappa b" and "TNF-α" are the most frequently studied signalling pathways. Atherosclerosis, myocarditis and myocardial injury are the most studied disease types in this field. In addition, the study of macrophage-related CVD induced by COVID-19 seems to be a recent hot topic, and the mechanisms involved are mainly macrophage polarization, inflammatory factor storm, ACE2 and so on. The present study reveals hot spots and new trends in research on macrophages in CVD, which can provide scholars with key information in this field of research and help further explore new research directions.

Recent advance in treatment of atherosclerosis: Key targets and plaque-positioned delivery strategies

Atherosclerosis, a chronic inflammatory disease of vascular wall, is a progressive pathophysiological process with lipids oxidation/depositing initiation and innate/adaptive immune responses. The coordination of multi systems covering oxidative stress, dysfunctional endothelium, diseased lipid uptake, cell apoptosis, thrombotic and pro-inflammatory responding as well as switched SMCs contributes to plaque growth. In this circumstance, inevitably, targeting these processes is considered to be effective for treating atherosclerosis. Arriving, retention and working of payload candidates mediated by targets in lesion direct ultimate therapeutic outcomes. Accumulating a series of scientific studies and clinical practice in the past decades, lesion homing delivery strategies including stent/balloon/nanoparticle-based transportation worked as the potent promotor to ensure a therapeutic effect. The objective of this review is to achieve a very brief summary about the effective therapeutic methods cooperating specifical targets and positioning-delivery strategies in atherosclerosis for better outcomes.

Survey of Approaches for Investigation of Atherosclerosis In Vivo

Although in vitro model systems are useful for investigation of atherosclerosis-associated processes, they represent simplification of complex events that occur in vivo, which involve interactions between many different cell types together with their environment. The use of animal model systems is important for more in-depth insights of the molecular mechanisms underlying atherosclerosis and for identifying potential targets for agents that can prevent plaque formation and even reverse existing disease. This chapter will provide a survey of such animal models and associated techniques that are routinely used for research of atherosclerosis in vivo.

Phosphatidylserine-containing liposomes: Therapeutic potentials against hypercholesterolemia and atherosclerosis

Liposomes have been suggested as potential tools for cholesterol deposit mobilization from atherosclerotic lesions. Here, we explored the anti-atherosclerotic effects of phosphatidylserine (PS)-containing liposomes in vivo. High-fat diet-fed New Zealand white rabbits which were divided into groups receiving weekly intravenous injections of PS liposomes, atorvastatin-loaded PS (PSA) liposomes (100 μg phospholipid/kg), or control buffer for four weeks. The size and severity grade of atherosclerotic plaques as well as lipid profile were evaluated at the completion of study. In vitro, the expression and levels of anti/pro-inflammatory genes and proteins, respectively, and macrophage cholesterol efflux capacity (CEC) of nanoliposomes were evaluated. Both PS and PSA lowered serum LDL-C (P = 0.0034, P = 0.0041) and TC (P = 0.029, P = 0.0054) levels but did not alter TG and HDL-C levels. Plaque size and grade were reduced by PS (P = 0.0025, P = 0.0031) and PSA (P = 0.016, P = 0.027) versus control. Moreover, intima-media thickness was significantly reduced in the PS vs. control group (P = 0.01). In cultured cells, ICAM-1 expression in the PS (P = 0.022) and VCAM-1 expression in the PS and PSA groups (P = 0.037, P = 0.004) were suppressed while TGF-β expression was induced by both PS and PSA (P = 0.048, P = 0.046). Moreover, CEC from macrophages to nanoliposomes was enhanced by PSA (P = 0.003). Administration of anionic PS-containing liposomes could improve lipid profile and promote plaque regression through mechanisms that may involve cholesterol efflux and modulation of adhesion molecules.

Helminth infections and cardiovascular diseases: A role for the microbiota and Mϕs?

Cardiovascular diseases are rising in developing countries with increasing urbanization and lifestyle changes and remains a major cause of death in the developed world. In this mini review, we discuss the possibility that the effect of helminth infections on the immune system and the microbiota may affect risk factors in cardiovascular diseases such as atherosclerosis, as part of the hygiene hypothesis. The effects of Type 2 immune responses induced by helminths and helminth derived molecules on regulating metabolism and Mϕ function could be a mechanistic link for further investigation. We emphasize the complexity and difficulties in determining indirect or direct and causal relationships between helminth infection status and cardiovascular diseases. New experimental models, such as rewilding laboratory mice, whereby different aspects of the environment and host genetics can be carefully dissected may provide further mechanistic insights and therapeutic strategies for treating cardiovascular diseases.

Clinical significance of microvessels detected by in vivo optical coherence tomography within human atherosclerotic coronary arterial intima: a study with multimodality intravascular imagings

The significance of microvessels within atherosclerotic plaques is not yet fully clarified. Associated with plaque vulnerability. The aim of this study is to examine tissue characteristics of plaque with microvessels detected by optical coherence tomography (OCT) by use of a commercially available color-coded intravascular ultrasound (IVUS) and coronary angioscopy (CAS). The subjects examined comprised of 44 patients with stable angina pectoris who underwent percutaneous coronary intervention. Microvessels were defined as a tiny tubule with a diameter of 50-300 µm detected over three or more frames in OCT. We compared the total volume of microvessels with tissue component such as fibrotic, lipidic, necrotic, and calcified volume and the number of yellow plaque. In IVUS analysis, % necrotic volume and % lipidic volume were significantly correlated and % fibrotic volume was inversely significantly correlated with the total volume of microvessel (r = 0.485, p = 0.0009; r = 0.401, p = 0.007; r = - 0.432, p = 0.003, respectively). The number of plaque with an angioscopic yellow grade of two or more was significantly correlated with the total volume of microvessel (r = 0.461, p = 0.002). The greater the luminal volume of microvessels, the more the percent content of necrotic/lipidic tissue volume within plaque and the more the number of yellow plaques. These data suggested that microvessels within coronary plaque might be related to plaque vulnerability.

Leukocyte Trafficking via Lymphatic Vessels in Atherosclerosis

In recent years, lymphatic vessels have received increasing attention and our understanding of their development and functional roles in health and diseases has greatly improved. It has become clear that lymphatic vessels are critically involved in acute and chronic inflammation and its resolution by supporting the transport of immune cells, fluid, and macromolecules. As we will discuss in this review, the involvement of lymphatic vessels has been uncovered in atherosclerosis, a chronic inflammatory disease of medium- and large-sized arteries causing deadly cardiovascular complications worldwide. The progression of atherosclerosis is associated with morphological and functional alterations in lymphatic vessels draining the diseased artery. These defects in the lymphatic vasculature impact the inflammatory response in atherosclerosis by affecting immune cell trafficking, lymphoid neogenesis, and clearance of macromolecules in the arterial wall. Based on these new findings, we propose that targeting lymphatic function could be considered in conjunction with existing drugs as a treatment option for atherosclerosis.

miR-33 Silencing Reprograms the Immune Cell Landscape in Atherosclerotic Plaques

[Figure: see text].

Atherosclerotic Cardiovascular Disease Prevalence Among Patients With Celiac Disease in the United States: An Observational Study

OBJECTIVE

To assess the prevalence of atherosclerotic cardiovascular disease (ASCVD) by age and sex in patients with celiac disease and to determine associations between ASCVD and celiac disease.

PATIENTS AND METHODS

This is a retrospective cohort study which included adults (>18 years old) who had hospitalizations recorded in the National Inpatient Sample database in the United States from January 1, 2005, to December 31, 2014. Patients with celiac disease were matched (1:5) by age, sex, race, and calendar year to patients without celiac disease. Prevalence of ASCVD was calculated in patients with celiac disease and controls, and compared by sex and age groups. Associations between celiac disease and ASCVD were determined after adjustment for common cardiovascular risk factors.

RESULTS

Among 371,776,860 patients hospitalized in the United States between 2005 and 2014, 227,172 adults with celiac disease were matched to 1,133,701 controls. Young women with celiac disease (age <40 years) had a higher prevalence of ASCVD and higher adjusted odds (aOR) of ASCVD when compared with controls (aged 18 to 29 years aOR, 2.22 [95% CI 1.41 to 3.5]; P<.001; and aged 30 to 39 years aOR 1.54 [95% CI 1.19 to 1.99]; P<.001). Adults with celiac disease of all ages and sexes had increased adjusted odds of death if they had ASCVD (aOR aged <40 years 7.31 [95% CI 2.49 to 21.46]; P<.001; and aOR aged ≥40 years 2.02 [95% CI 1.68 to 2.42]; P<.001).

CONCLUSION

We found significantly higher prevalence and adjusted odds of ASCVD in young women with celiac disease when compared with matched controls. ASCVD was associated with significant mortality among patients with celiac disease.

Effects of Statin Plus Ezetimibe on Coronary Plaques in Acute Coronary Syndrome Patients with Diabetes Mellitus: Sub-Analysis of PRECISE-IVUS Trial

AIM

Coronary plaque regression is weak in acute coronary syndrome (ACS) patients with diabetes mellitus (DM). We evaluated whether dual lipid-lowering therapy (DLLT) with ezetimibe and atorvastatin attenuates coronary plaques in ACS patients with DM.

METHODS

The prospective, randomized controlled, multicenter PRECISE-IVUS (Plaque Regression with Cholesterol Absorption Inhibitor or Synthesis Inhibitor Evaluated by Intravascular Ultrasound) trial assigned 246 patients undergoing percutaneous coronary intervention to DLLT or atorvastatin monotherapy and evaluated IVUS-derived changes in percent atheroma volume (ΔPAV), at baseline and 9-12-month follow-up, in 126 ACS cases, including 25 DM patients. The atorvastatin dose was up-titrated to achieve low-density lipoprotein cholesterol (LDL-C) ＜70 mg/dL.

RESULTS

In DM patients, the monotherapy group (n=13) and the DLLT group (n=12) showed a similar prevalence of coronary risks and baseline lipid profiles. During the study, the change in LDL-C level was similar between DM and non-DM patients. Compared with non-DM patients, DM patients showed weaker regression of ΔPAV by DLLT than those who underwent monotherapy (DM: -2.77±3.47% vs. -0.77±2.51%, P=0.11; non-DM: -2.01±3.36% vs. -0.08±2.66%, P=0.008). The change in LDL-C level was not correlated with ΔPAV in non-DM patients, but there was significant correlation between the change in LDL-C level and ΔPAV in DM patients (r=0.52, P=0.008).

CONCLUSIONS

ACS patients with DM showed weaker coronary plaque regression than their counterparts. A significant correlation between the change in LDL-C level and ΔPAV in DM patients suggested that more intensive lipid-lowering therapy is required in ACS patients with DM.

Atherosclerosis: Making a U Turn

The development of potent cholesterol-reducing medications in the last decade of the twentieth century has altered the approach to prevention and treatment of cardiovascular disease (CVD). Initial experience with statins, and more recently with the addition of PCSK9 inhibitors, has proven that human CVD, like that in animal models, can be halted and regressed. Available clinical data show that the lower the achieved level of low-density lipoprotein cholesterol, the greater the regression of disease. Investigative studies are now aimed to understand those factors that both accelerate and impede this healing process. Some of these are likely to be modifiable, and the future of atherosclerotic CVD treatment is likely to be early screening, use of measures to repair atherosclerotic arteries, and prevention of most CVD events.

Regulatory T Cells License Macrophage Pro-Resolving Functions During Atherosclerosis Regression

RATIONALE

Regression of atherosclerosis is an important clinical goal; however, the pathways that mediate the resolution of atherosclerotic inflammation and reversal of plaques are poorly understood. Regulatory T cells (Tregs) have been shown to be atheroprotective, yet the numbers of these immunosuppressive cells decrease with disease progression, and whether they contribute to atherosclerosis regression is not known.

OBJECTIVE

We investigated the roles of Tregs in the resolution of atherosclerotic inflammation, tissue remodeling, and plaque contraction during atherosclerosis regression.

METHODS AND RESULTS

Using multiple independent mouse models of atherosclerosis regression, we demonstrate that an increase in plaque Tregs is a common signature of regressing plaques. Single-cell RNA-sequencing of plaque immune cells revealed that unlike Tregs from progressing plaques that expressed markers of natural Tregs derived from the thymus, Tregs in regressing plaques lacked Nrp1 expression, suggesting that they are induced in the periphery during lipid-lowering therapy. To test whether Tregs are required for resolution of atherosclerotic inflammation and plaque regression, Tregs were depleted using CD25 monoclonal antibody in atherosclerotic mice during apolipoprotein B antisense oligonucleotide-mediated lipid lowering. Morphometric analyses revealed that Treg depletion blocked plaque remodeling and contraction, and impaired hallmarks of inflammation resolution, including dampening of the T helper 1 response, alternative activation of macrophages, efferocytosis, and upregulation of specialized proresolving lipid mediators.

CONCLUSIONS

Our data establish essential roles for Tregs in resolving atherosclerotic cardiovascular disease and provide mechanistic insight into the pathways governing plaque remodeling and regression of disease.

Prevalence and predictors of frailty in a high-income developing country: A cross-sectional study

Background: Frailty is a state of vulnerability and a decreased physiological response to stressors. As the population ages, the prevalence of frailty is expected to increase. Thus, identifying tools and resources that efficiently predict frailty among the Saudi population is important. We aimed to describe the prevalence and predictors of frailty among Saudi patients referred for cardiac stress testing with nuclear imaging. Methods: We included 876 patients (mean age 60.3 ± 11 years, women 48%) who underwent clinically indicated cardiac nuclear stress testing between January and October 2016. Fried Clinical Frailty Scale was used to assess frailty. Patients were considered frail if they had a score of four or higher. Multivariate adjusted logistic regression models were used to determine the independent predictors of elderly frail patients. Results: In this cohort, the median age of the included patients was 61 years, and the prevalence of frailty was 40%. The frail patients were older, more frequently women, and had a higher body mass index. Additionally, frailty was associated with a higher prevalence of cardiovascular risk factors: hypertension (85% vs. 70%) and diabetes (75% vs. 60%). In a fully adjusted logistic regression model, women, hypertension, and obesity (BMI ≥ 30 kg/m²) were independent predictors of elderly frail patients. Conclusions: With the aging of the Saudi population, frailty prevalence is expected to increase. Elderly, obesity, hypertension, and female gender are risk factors of frailty. Interventions to reduce frailty should be focused on this high-risk population.

Can atherosclerosis be cured?

PURPOSE OF REVIEW

Determine if evidence supports interventions to prevent development of atherosclerosis and atherosclerotic cardiovascular disease (ASCVD) events and death.

RECENT FINDINGS

An extensive body of evidence supports the fundamental causal role of apolipoprotein B lipoproteins in the development of atherosclerosis. Recent epidemiologic studies have shown that LDL-cholesterol (LDL-C) and non-HDL-cholesterol levels in early adults are associated with accelerated subclinical atherosclerosis and an excess of atherosclerotic cardiovascular events later in life. Animal and human data have shown that intensive LDL-C lowering can regress earlier stages of atherosclerosis.

SUMMARY

The next research priority is evaluating the impact of lowering LDL-C earlier in life to regress early atherosclerosis, followed by trials to demonstrate this approach will eradicate later-life ASCVD events and death. This approach of curing atherosclerosis will likely be the most effective strategy for reducing the huge global burden of atherosclerosis.

Glucose lowering by SGLT2-inhibitor empagliflozin accelerates atherosclerosis regression in hyperglycemic STZ-diabetic mice

Diabetes worsens atherosclerosis progression and leads to a defect in repair of arteries after cholesterol reduction, a process termed regression. Empagliflozin reduces blood glucose levels via inhibition of the sodium glucose cotransporter 2 (SGLT-2) in the kidney and has been shown to lead to a marked reduction in cardiovascular events in humans. To determine whether glucose lowering by empagliflozin accelerates atherosclerosis regression in a mouse model, male C57BL/6J mice were treated intraperitoneally with LDLR- and SRB1- antisense oligonucleotides and fed a high cholesterol diet for 16 weeks to induce severe hypercholesterolemia and atherosclerosis progression. At week 14 all mice were rendered diabetic by streptozotocin (STZ) injections. At week 16 a baseline group was sacrificed and displayed substantial atherosclerosis of the aortic root. In the remaining mice, plasma cholesterol was lowered by switching to chow diet and treatment with LDLR sense oligonucleotides to induce atherosclerosis regression. These mice then received either empagliflozin or vehicle for three weeks. Atherosclerotic plaques in the empagliflozin treated mice were significantly smaller, showed decreased lipid and CD68⁺ macrophage content, as well as greater collagen content. Proliferation of plaque resident macrophages and leukocyte adhesion to the vascular wall were significantly decreased in empagliflozin-treated mice. In summary, plasma glucose lowering by empagliflozin improves plaque regression in diabetic mice.

Epigenetic Hallmarks of Fetal Early Atherosclerotic Lesions in Humans

Importance

Although increasingly strong evidence suggests a role of maternal total cholesterol and low-density lipoprotein cholesterol (LDLC) levels during pregnancy as a risk factor for atherosclerotic disease in the offspring, the underlying mechanisms need to be clarified for future clinical applications.

Objective

To test whether epigenetic signatures characterize early fetal atherogenesis associated with maternal hypercholesterolemia and to provide a quantitative estimate of the contribution of maternal cholesterol level to fetal lesion size.

Design, Setting, and Participants

This autopsy study analyzed 78 human fetal aorta autopsy samples from the Division of Human Pathology, Department of Advanced Biomedical Sciences, Federico II University of Naples, Naples, Italy. Maternal levels of total cholesterol, LDLC, high-density lipoprotein cholesterol (HDLC), triglycerides, and glucose and body mass index (BMI) were determined during hospitalization owing to spontaneous fetal death. Data were collected and immediately processed and analyzed to prevent degradation from January 1, 2011, through November 30, 2016.

Main Outcomes and Measurements

Results of DNA methylation and messenger RNA levels of the following genes involved in cholesterol metabolism were assessed: superoxide dismutase 2 (SOD2), low-density lipoprotein receptor (LDLR), sterol regulatory element binding protein 2 (SREBP2), liver X receptor α (LXRα), and adenosine triphosphate-binding cassette transporter 1 (ABCA1).

Results

Among the 78 fetal samples included in the analysis (59% male; mean [SD] fetal age, 25 [3] weeks), maternal cholesterol level explained a significant proportion of the fetal aortic lesion variance in multivariate analysis (61%; P = .001) independently by the effect of levels of HDLC, triglycerides, and glucose and BMI. Moreover, maternal total cholesterol and LDLC levels were positively associated with methylation of SREBP2 in fetal aortas (Pearson correlation, 0.488 and 0.503, respectively), whereas in univariate analysis, they were inversely correlated with SREBP2 messenger RNA levels in fetal aortas (Pearson correlation, -0.534 and -0.671, respectively). Epivariations of genes controlling cholesterol metabolism in cholesterol-treated human aortic endothelial cells were also observed.

Conclusions and Relevance

The present study provides a stringent quantitative estimate of the magnitude of the association of maternal cholesterol levels during pregnancy with fetal aortic lesions and reveals the epigenetic response of fetal aortic SREBP2 to maternal cholesterol level. The role of maternal cholesterol level during pregnancy and epigenetic signature in offspring in cardiovascular primary prevention warrants further long-term causal relationship studies.

Active Phagocytosis and Diachronic Processing of Calcium Oxalate Monohydrate Crystals in an in vitro Macrophage Model

BACKGROUND

We previously discovered that renal macrophages (Mφs) phagocytose renal calcium oxalate monohydrate (COM) crystals. This study investigated the processing of engulfed crystals using in vitro models.

METHODS

J774.1 mouse Mφs were exposed to COM crystals and observed for 24 h using polarized light microscopy with/without cytochalasin B (CB), an inhibitor of phagocytosis, to confirm active crystal phagocytosis. LysoTracker and immunohistochemical staining using transmission electron microscopy for lysosomal-associated membrane protein 1 were used to confirm engulfed COM crystal uptake into lysosomes. Diachronic tracking of specific Mφs was performed to capture the entire course of engulfed COM crystal processing using polarized light microscopy. Follow-up studies of fluorescent COM (f-COM) crystals using imaging cytometry were performed in the presence and absence of nigericin to dissipate the pH gradient in acidic organelles.

RESULTS

Phagocytosis rates increased with COM density and were significantly lower in cells treated with CB (p < 0.01). We observed that engulfed crystals colocalized within lysosomes of the Mφs; moreover, diachronic observation indicated that the engulfed COM crystals were subdivided during Mφ division and eliminated by the 7th day of culture. Additionally, imaging cytometry showed that the fluorescence level of f-COM crystals in the nigericin (-) group after 48 h was significantly lower than that in the nigericin (+) group.

CONCLUSIONS

This study confirmed active phagocytosis and lysosomal processing of engulfed COM crystals by Mφs. This discovery is expected to contribute to the development of future drugs that enhance the COM crystal phagocytic ability of Mφs.

Atherosclerosis in Chronic Kidney Disease: More, Less, or Just Different?

Patients with chronic kidney disease (CKD) are at an increased risk of premature mortality, mainly from cardiovascular causes. The association between CKD on hemodialysis and accelerated atherosclerosis was described >40 years ago. However, more recently, it has been suggested that the increase in atherosclerosis risk is actually observed in early CKD stages, remaining stable thereafter. In this regard, interventions targeting the pathogenesis of atherosclerosis, such as statins, successful in the general population, have failed to benefit patients with very advanced CKD. This raises the issue of the relative contribution of atherosclerosis versus other forms of cardiovascular injury such as arteriosclerosis or myocardial injury to the increased cardiovascular risk in CKD. In this review, the pathophysiogical contributors to atherosclerosis in CKD that are shared with the general population, or specific to CKD, are discussed. The NEFRONA study (Observatorio Nacional de Atherosclerosis en NEFrologia) prospectively assessed the prevalence and progression of subclinical atherosclerosis (plaque in vascular ultrasound), confirming an increased prevalence of atherosclerosis in patients with moderate CKD. However, the adjusted odds ratio for subclinical atherosclerosis increased with CKD stage, suggesting a contribution of CKD itself to subclinical atherosclerosis. Progression of atherosclerosis was closely related to CKD progression as well as to the baseline presence of atheroma plaque, and to higher phosphate, uric acid, and ferritin and lower 25(OH) vitamin D levels. These insights may help design future clinical trials of stratified personalized medicine targeting atherosclerosis in patients with CKD. Future primary prevention trials should enroll patients with evidence of subclinical atherosclerosis and should provide a comprehensive control of all known risk factors in addition to testing any additional intervention or placebo.

Structure and Function of Proprotein Convertase Subtilisin/kexin Type 9 (PCSK9) in Hyperlipidemia and Atherosclerosis

Background:

One of the important factors in Low-Density Lipoprotein (LDL) metabolism is the LDL receptor (LDLR) by its capacity to bind and subsequently clear cholesterol derived from LDL (LDL-C) in the circulation. Proprotein Convertase Subtilisin-like Kexin type 9 (PCSK9) is a newly discovered serine protease that destroys LDLR in the liver and thereby controls the levels of LDL in plasma. Inhibition of PCSK9-mediated degradation of LDLR has, therefore, become a novel target for lipid-lowering therapy.

Methods:

We review the current understanding of the structure and function of PCSK9 as well as its implications for the treatment of hyperlipidemia and atherosclerosis.

Results:

New treatments such as monoclonal antibodies against PCSK9 may be useful agents to lower plasma levels of LDL and hence prevent atherosclerosis.

Conclusion:

PCSK9's mechanism of action is not yet fully clarified. However, treatments that target PCSK9 have shown striking early efficacy and promise to improve the lives of countless patients with hyperlipidemia and atherosclerosis.

EGFP-EGF1-conjugated poly(lactic-co-glycolic acid) nanoparticles, a new diagnostic tool and drug carrier for atherosclerosis

Background

EGFP-EGF1-conjugated poly(lactic-co-glycolic acid) (PLGA) nanoparticle (ENP) has a specific affinity to tissue factor (TF). The aim of this study was to investigate the target delivery of ENP to plaques and its uptake in a mouse model of atherosclerosis in vivo and in vitro.

Materials and methods

Coumarin-6- and 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindotricarbo cyanine iodide (DiR)-loaded ENPs were synthesized using a double-emulsion method. Mouse vascular smooth muscle cells (VSMCs) were induced with MCP-1 to obtain an increased TF expression. Fluorescence microscopy and flow cytometry assay were performed to examine the uptake of coumarin-6-loaded ENPs in cellular models. An animal model of atherosclerosis was established with an ApoE (−/−) mouse fed with continuous high-fat diets for 14 weeks. DiR-loaded ENPs (DiR-ENPs) were injected via the caudal vein. The distribution of DiR-ENPs was examined through organ imaging and confocal laser scanning microscopy.

Results

Results indicated TFs were highly expressed in the cellular model. The uptake of coumarin-6-loaded ENPs was significantly higher than that of common PLGA nanoparticles. Thickening of intima and lipid deposition in the aorta could be observed in atherosclerosis mouse models. Confocal laser scanning microscopy organ imaging showed ENPs accumulated in vessels with atherosclerotic plaques, which coincided with high expressions of TF.

Conclusion

This study showed that EGFP-EGF1-conjugated PLGA nanoparticles could be effectively delivered to atherosclerotic plaques in vivo and taken up by VSMCs with high TF expressions in vitro. Thus, it could be a promising carrier for targeted therapy of atherosclerosis.

Arterial Lymphatics in Atherosclerosis: Old Questions, New Insights, and Remaining Challenges

The lymphatic network is well known for its role in the maintenance of tissue fluid homeostasis, absorption of dietary lipids, trafficking of immune cells, and adaptive immunity. Aberrant lymphatic function has been linked to lymphedema and immune disorders for a long time. Discovery of lymphatic cell markers, novel insights into developmental and postnatal lymphangiogenesis, development of genetic mouse models, and the introduction of new imaging techniques have improved our understanding of lymphatic function in both health and disease, especially in the last decade. Previous studies linked the lymphatic vasculature to atherosclerosis through regulation of immune responses, reverse cholesterol transport, and inflammation. Despite extensive research, many aspects of the lymphatic circulation in atherosclerosis are still unknown and future studies are required to confirm that arterial lymphangiogenesis truly represents a therapeutic target in patients with cardiovascular disease. In this review article, we provide an overview of factors and mechanisms that regulate lymphangiogenesis, summarize recent findings on the role of lymphatics in macrophage reverse cholesterol transport, immune cell trafficking and pathogenesis of atherosclerosis, and present an overview of pharmacological and genetic strategies to modulate lymphatic vessel density in cardiovascular tissue.

Undiscovered pathology of transient scaffolding t1remains a driver of failures in clinical trials

AIM

To statistically examine the released clinical trials and meta-analyses of polymeric bioresorbable scaffolds resuming the main accomplishments in the field with a translation to the routine clinical practice.

METHODS

The statistical power in clinical trials such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA, and few meta-analyses by the post hoc odds ratio-based sample size calculation, and the patterns of artery remodeling published in papers from ABSORB A and B trials were evaluated.

RESULTS

The phenomenal admiration from the first ABSORB studies in 2006-2013 was replaced by the tremendous disappointment in 2014-2017 due to reported relatively higher rates of target lesion failure (a mean prevalence of 9.16%) and device thrombosis (2.38%) in randomized controlled trials. Otherwise, bioresorbable vascular scaffold (BVS) performs as well as the metallic drug-eluting stent (DES) with a trend toward some benefits for cardiac mortality [risk ratio (RR), 0.58-0.94, P > 0.05]. The underpowered design was confirmed for some studies such as ABSORB Japan, ABSORB China, EVERBIO II, AIDA trials, and meta-analyses of Polimeni, Collet, and Mahmoud with some unintentional bias (judged by the asymmetrical Funnel plot). Scaffold thrombosis rates with Absorb BRS were comparable with DES performed with a so-called strategy of the BVS implantation with optimized pre-dilation (P), sizing (S) and post-dilation (P) (PSP) implantation (RR, PSP vs no PSP 0.37) achieving 0.35 per 100 patient-years, which is comparable to the RR 0.49 with bare-metal stents and the RR 1.06 with everolimus DES. Both ABSORB II and ABSORB III trials were powered enough for a five-year follow-up, but the results were not entirely conclusive due to the mostly non-significant fashion of data. The powered meta-analyses were built mostly on statistically poor findings.

CONCLUSION

The misunderstanding of the pathology of transient scaffolding drives the failures of the clinical trials. More bench studies of the vascular response are required. Several next-generation BVS including multifunctional electronic scaffold grant cardiology with a huge promise to make BVS technology great again.

Sonodynamic therapy-induced foam cells apoptosis activates the phagocytic PPARγ-LXRα-ABCA1/ABCG1 pathway and promotes cholesterol efflux in advanced plaque

In advanced atherosclerotic plaques, defective efferocytosis of apoptotic foam cells and decreased cholesterol efflux contribute to lesion progression. In our previous study, we demonstrated that 5-aminolevulinic acid (ALA)-mediated sonodynamic therapy (SDT) could induce foam cells apoptosis via the mitochondrial-caspase pathway. In the current research, we sought to explore ALA-SDT-induced apoptosis of phagocytes and the effects of cholesterol efflux and efferocytosis in advanced apoE^-/- mice plaque.

Methods: apoE^-/- mice fed western diet were treated with ALA-SDT and sacrificed at day 1, day 3, day 7 and day 28 post treatment. THP-1 macrophage-derived foam cells were treated with ALA-SDT. 5 hours later, the supernatant was collected and added to fresh foam cells (phagocytes). Then, the lipid area, efferocytosis, cholesterol efflux, anti-inflammatory reactions and PPARγ-LXRα-ABCA1/ABCG1 pathway were detected in plaque in vivo and in phagocytes in vitro.

Results: We found that ALA-SDT induced foam cells apoptosis coupled with efferocytosis and upregulation of Mer tyrosine kinase (MerTK) both in vivo and in vitro. The lipid content in plaque decreased as early as 1 day after ALA-SDT and this tendency persisted until 28 days. The enhancement of phagocytes cholesterol efflux was accompanied by an approximately 40% decrease in free cholesterol and a 24% decrease in total cholesterol in vitro. More importantly, anti-inflammatory factors such as TGFβ and IL-10 were upregulated by ALA-SDT treatment. Finally, we found that PPARγ-LXRα-ABCA1/ABCG1 pathway was activated both in vivo and in vitro by ALA-SDT, which could be blocked by PPARγ siRNA.

Conclusions: Activation of PPARγ-LXRα-ABCA1/ABCG1 pathway induced by ALA-SDT treatment engages a virtuous cycle that enhances efferocytosis, cholesterol efflux and anti-inflammatory reactions in advanced plaque in vivo and in phagocytes in vitro.

Role of AGEs in the progression and regression of atherosclerotic plaques

The formation of advanced glycation end-products(AGEs) is an important cause of metabolic memory in diabetic patients and a key factor in the formation of atherosclerosis(AS) plaques in patients with diabetes mellitus. Related studies showed that AGEs could disrupt hemodynamic steady-state and destroy vascular wall integrity through the endothelial barrier damage, foam cell(FC) formation, apoptosis, calcium deposition and other aspects. At the same time, AGEs could initiate oxidative stress and inflammatory response cascade via receptor-depended and non-receptor-dependent pathways, promoting plaques to develop from a steady state to a vulnerable state and eventually tend to rupture and thrombosis. Numerous studies have confirmed that these pathological processes mentioned above could lead to acute coronary heart disease(CHD) and other acute cardiovascular and cerebrovascular events. However, the specific role of AGEs in the progression and regression of AS plaques has not yet been fully elucidated. In this paper, the formation, source, metabolism, physical and chemical properties of AGEs and their role in the migration of FCs and plaque calcification are briefly described, we hope to provide new ideas for the researchers that struggling in this field.

Insights From Pre-Clinical and Clinical Studies on the Role of Innate Inflammation in Atherosclerosis Regression

Atherosclerosis, the underlying cause of coronary artery (CAD) and other cardiovascular diseases, is initiated by macrophage-mediated immune responses to lipoprotein and cholesterol accumulation in artery walls, which result in the formation of plaques. Unlike at other sites of inflammation, the immune response becomes maladaptive and inflammation fails to resolve. The most common treatment for reducing the risk from atherosclerosis is low density lipoprotein cholesterol (LDL-C) lowering. Studies have shown, however, that while significant lowering of LDL-C reduces the risk of heart attacks to some degree, there is still residual risk for the majority of the population. We and others have observed “residual inflammatory risk” of atherosclerosis after plasma cholesterol lowering in pre-clinical studies, and that this phenomenon is clinically relevant has been dramatically reinforced by the recent Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS) trial. This review will summarize the role of the innate immune system, specifically macrophages, in atherosclerosis progression and regression, as well as the pre-clinical and clinical models that have provided significant insights into molecular pathways involved in the resolution of plaque inflammation and plaque regression. Partnered with clinical studies that can be envisioned in the post-CANTOS period, including progress in developing targeted plaque therapies, we expect that pre-clinical studies advancing on the path summarized in this review, already revealing key mechanisms, will continue to be essential contributors to achieve the goals of dampening plaque inflammation and inducing its resolution in order to maximize the therapeutic benefits of conventional risk factor modifications, such as LDL-C lowering.

Macrophages and lipid metabolism

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The transcriptional signature of Kupffer cells & Alveolar macrophages are enriched for lipid metabolism genes.

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Lipid metabolism may control macrophage phenotype.

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Dysregulated lipid metabolism in macrophages contributes to disease pathology.

Distinct macrophage populations throughout the body display highly heterogeneous transcriptional and epigenetic programs. Recent research has highlighted that these profiles enable the different macrophage populations to perform distinct functions as required in their tissue of residence, in addition to the prototypical macrophage functions such as in innate immunity. These ‘extra’ tissue-specific functions have been termed accessory functions. One such putative accessory function is lipid metabolism, with macrophages in the lung and liver in particular being associated with this function. As it is now appreciated that cell metabolism not only provides energy but also greatly influences the phenotype and function of the cell, here we review how lipid metabolism affects macrophage phenotype and function and the specific roles played by macrophages in the pathogenesis of lipid-related diseases. In addition, we highlight the current questions limiting our understanding of the role of macrophages in lipid metabolism.

Novel Reversible Model of Atherosclerosis and Regression Using Oligonucleotide Regulation of the LDL Receptor

RATIONALE

Animal models have been used to explore factors that regulate atherosclerosis. More recently, they have been used to study the factors that promote loss of macrophages and reduction in lesion size after lowering of plasma cholesterol levels. However, current animal models of atherosclerosis regression require challenging surgeries, time-consuming breeding strategies, and methods that block liver lipoprotein secretion.

OBJECTIVE

We sought to develop a more direct or time-effective method to create and then reverse hypercholesterolemia and atherosclerosis via transient knockdown of the hepatic LDLR (low-density lipoprotein receptor) followed by its rapid restoration.

METHODS AND RESULTS

We used antisense oligonucleotides directed to LDLR mRNA to create hypercholesterolemia in wild-type C57BL/6 mice fed an atherogenic diet. This led to the development of lesions in the aortic root, aortic arch, and brachiocephalic artery. Use of a sense oligonucleotide replicating the targeted sequence region of the LDLR mRNA rapidly reduced circulating cholesterol levels because of recovery of hepatic LDLR expression. This led to a decrease in macrophages within the aortic root plaques and brachiocephalic artery, that is, regression of inflammatory cell content, after a period of 2 to 3 weeks.

CONCLUSIONS

We have developed an inducible and reversible hepatic LDLR knockdown mouse model of atherosclerosis regression. Although cholesterol reduction decreased early en face lesions in the aortic arches, macrophage area was reduced in both early and late lesions within the aortic sinus after reversal of hypercholesterolemia. Our model circumvents many of the challenges associated with current mouse models of regression. The use of this technology will potentially expedite studies of atherosclerosis and regression without use of mice with genetic defects in lipid metabolism.

How radiation influences atherosclerotic plaque development: a biophysical approach in ApoE⁻/⁻ mice

Atherosclerosis is the development of lipid-laden plaques in arteries and is nowadays considered as an inflammatory disease. It has been shown that high doses of ionizing radiation, as used in radiotherapy, can increase the risk of development or progression of atherosclerosis. To elucidate the effects of radiation on atherosclerosis, we propose a mathematical model to describe radiation-promoted plaque development. This model distinguishes itself from other models by combining plaque initiation and plaque growth, and by incorporating information from biological experiments. It is based on two consecutive processes: a probabilistic dose-dependent plaque initiation process, followed by deterministic plaque growth. As a proof of principle, experimental plaque size data from carotid arteries from irradiated ApoE[Formula: see text] mice was used to illustrate how this model can provide insight into the underlying biological processes. This analysis supports the promoting role for radiation in plaque initiation, but the model can easily be extended to include dose-related effects on plaque growth if available experimental data would point in that direction. Moreover, the model could assist in designing future biological experiments on this research topic. Additional biological data such as plaque size data from chronically-irradiated mice or experimental data sets with a larger variety in biological parameters can help to further unravel the influence of radiation on plaque development. To the authors' knowledge, this is the first biophysical model that combines probabilistic and mechanistic modeling which uses experimental data to investigate the influence of radiation on plaque development.

Atheroregressive Potential of the Treatment with a Chimeric Monoclonal Antibody against Sulfated Glycosaminoglycans on Pre-existing Lesions in Apolipoprotein E-Deficient Mice

The retention of lipoprotein particles in the intima, in particular to glycosaminoglycan side chains of proteoglycans, is a critical step in atherosclerosis initiation. Administration of chP3R99, a chimeric mouse/human monoclonal antibody inducing an anti-idiotypic network response against glycosaminoglycans was previously shown to prevent atherosclerotic lesion progression, yet its effect in the late-stage progression of lesions remains unknown. This study investigated the effect of chP3R99 at a late stage of disease development in apolipoprotein E-deficient mice and the vascular mechanisms involved. Male apolipoprotein E-deficient mice were fed a high-fat high-cholesterol diet from 4 to 19 weeks old, at which time mice were fed normal chow and 5 doses of chP3R99 (50 μg) or isotype-matched IgG (hR3) were administered subcutaneously weekly for the first 3 administrations, then at weeks 24 and 26 before sacrifice (week 28). Lesions progression was reduced by 88% in treated mice with no change in total plasma cholesterol levels, yet with increased sera reactivity to chP3R99 idiotype and heparin, suggesting the induction of an anti-idiotype antibody cascade against glycosaminoglycans, which was likely related with the atheroprotective effect. chP3R99 treatment initiated regression in a significant number of mice. Circulating levels of interleukin-6 were reduced along with a striking diminution of inflammatory cell accumulation in the vessel wall, and of VCAM-1 labeling in vivo. The ratio of IL-10/iNOS gene expression in aortas increased in chP3R99-treated mice. In conclusion, our results show that treatment with chP3R99 reduces vascular inflammatory burden and halts lesion progression with potential for regression in the late phase of the disease in atherosclerotic mice, and support the therapeutic intervention against glycosaminoglycans as a novel strategy to reverse atherosclerosis.

4-phenylbutyrate and valproate treatment attenuates the progression of atherosclerosis and stabilizes existing plaques

BACKGROUND AND AIMS

Recent evidence suggests that endoplasmic reticulum (ER) stress signaling through glycogen synthase kinase (GSK)-3α/β is involved in the activation of pro-atherosclerotic processes. In this study, we examined the effects of small molecules that interfere with ER stress-GSK3α/β signaling on the progression and regression of atherosclerosis in a mouse model.

METHODS

To examine atherosclerotic progression, low-density lipoprotein receptor deficient (Ldlr^-/-) mice were placed on a high-fat diet (HFD) and treated with the chemical chaperone, 4-phenylbutyrate (4PBA, 3.8  g/L drinking water), or the GSK3α/β inhibitor, valproate (VPA, 625 mg VPA/kg diet), for 10 weeks. To examine potential effects on atherosclerotic regression, 4 week old Ldlr^-/- mice were placed on a HFD for 16 weeks. Subsets of mice were harvested at this time or switched to a chow (low fat) diet, or a chow diet with 4PBA or VPA treatment for 4 weeks.

RESULTS

In the progression model, the 4PBA- and VPA-treated mice had significantly reduced lesion and necrotic core size. Treatments had no effect on metabolic parameters, including plasma and hepatic lipid levels, or plaque composition. In the regression model, mice with 4PBA or VPA treatment showed no alterations in lesion size, but the lesions had significantly smaller necrotic cores, increased vascular smooth muscle cell content, and increased collagen content. These features are consistent with more stable plaques.

CONCLUSIONS

The pharmacological attenuation of ER stress or inhibition of GSK3α/β impedes the development of atherosclerosis in Ldlr^-/- mice and appears to promote the stabilization of existing lesions.

Inflammatory Ly6Chi monocytes and their conversion to M2 macrophages drive atherosclerosis regression

Atherosclerosis is a chronic inflammatory disease, and developing therapies to promote its regression is an important clinical goal. We previously established that atherosclerosis regression is characterized by an overall decrease in plaque macrophages and enrichment in markers of alternatively activated M2 macrophages. We have now investigated the origin and functional requirement for M2 macrophages in regression in normolipidemic mice that received transplants of atherosclerotic aortic segments. We compared plaque regression in WT normolipidemic recipients and those deficient in chemokine receptors necessary to recruit inflammatory Ly6Chi (Ccr2-/- or Cx3cr1-/-) or patrolling Ly6Clo (Ccr5-/-) monocytes. Atherosclerotic plaques transplanted into WT or Ccr5-/- recipients showed reduced macrophage content and increased M2 markers consistent with plaque regression, whereas plaques transplanted into Ccr2-/- or Cx3cr1-/- recipients lacked this regression signature. The requirement of recipient Ly6Chi monocyte recruitment was confirmed in cell trafficking studies. Fate-mapping and single-cell RNA sequencing studies also showed that M2-like macrophages were derived from newly recruited monocytes. Furthermore, we used recipient mice deficient in STAT6 to demonstrate a requirement for this critical component of M2 polarization in atherosclerosis regression. Collectively, these results suggest that continued recruitment of Ly6Chi inflammatory monocytes and their STAT6-dependent polarization to the M2 state are required for resolution of atherosclerotic inflammation and plaque regression.

The phenomenon of atherosclerosis reversal and regression: Lessons from animal models

Studies in non-rodent and murine models showed that atherosclerosis can be reversed. Atherosclerosis progression induced by high-fat or cholesterol-rich diet can be reduced and reversed to plaque regression after switching to a normal diet or through administration of lipid-lowering agents. The similar process should exist in humans after implementation of lipid-lowering therapy and as a result of targeting of small rupture-prone plaques that are major contributors for acute atherosclerotic complications. Lowering of low density lipoprotein (LDL) cholesterol and the activation of reverse cholesterol transport lead to a decline in foam cell content, to the depletion of plaque lipid reservoirs, a decrease in lesional macrophage numbers through the activation of macrophage emigration and, probably, apoptosis, dampening plaque inflammation, and the induction of anti-inflammatory macrophages involved in clearance of the necrotic core and plaque healing. By contrast, plaque regression is characterized by opposite events, leading to the retention of atherogenic LDL and oxidized LDL particles in the plaque, an increased flux of monocytes, the immobilization of macrophages in the intimal vascular tissues, and the propagation of intraplaque inflammation. Transfer of various apolipoprotein (apo) genes to spontaneously hypercholesterolemic mice deficient for either apoE or LDL receptor and, especially, the implementation of the transplantation murine model allowed studying molecular mechanisms of atherosclerotic regression, associated with the depletion of atherogenic lipids in the plaque, egress of macrophages and phenotypic switch of macrophages from the proinflammatory M1 to the anti-inflammatory M2.

Local Vascular Gene Therapy With Apolipoprotein A-I to Promote Regression of Atherosclerosis

OBJECTIVE

Gene therapy, delivered directly to the blood vessel wall, could potentially prevent atherosclerotic lesion growth and promote atherosclerosis regression. Previously, we reported that a helper-dependent adenoviral (HDAd) vector expressing apolipoprotein A-I (apoA-I) in carotid endothelium of fat-fed rabbits reduced early (4 weeks) atherosclerotic lesion growth. Here, we tested whether the same HDAd-delivered to the existing carotid atherosclerotic lesions-could promote regression.

APPROACH AND RESULTS

Rabbits (n=26) were fed a high-fat diet for 7 months, then treated with bilateral carotid gene transfer. One carotid was infused with an HDAd expressing apoA-I (HDAdApoAI) and the other with a control nonexpressing HDAd (HDAdNull). The side with HDAdApoAI was randomized. Rabbits were then switched to regular chow, lowering their plasma cholesterols by over 70%. ApoA-I mRNA and protein were detected in HDAdApoAI-transduced arteries. After 7 weeks of gene therapy, compared with HDAdNull-treated arteries in the same rabbits, HDAdApoAI-treated arteries had significantly less vascular cell adhesion molecule-1 expression (28%; P=0.04) along with modest but statistically insignificant trends toward decreased intimal lesion volume, lipid and macrophage content, and intercellular adhesion molecule-1 expression (9%-21%; P=0.1-0.4). Post hoc subgroup analysis of rabbits with small-to-moderate-sized lesions (n=20) showed that HDAdApoAI caused large reductions in lesion volume, lipid content, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1 expression (30%-50%; P≤0.04 for all). Macrophage content was reduced by 30% (P=0.06). There was a significant interaction (P=0.02) between lesion size and treatment efficacy.

CONCLUSIONS

Even when administered on a background of aggressive lowering of plasma cholesterol, local HDAdApoAI vascular gene therapy may promote rapid regression of small-to-moderate-sized atherosclerotic lesions.

Inflammatory processes in cardiovascular disease: a route to targeted therapies

Inflammatory processes are firmly established as central to the development and complications of cardiovascular diseases. Elevated levels of inflammatory markers have been shown to be predictive of future cardiovascular events. The specific targeting of these processes in experimental models has been shown to attenuate myocardial and arterial injury, reduce disease progression, and promote healing. However, the translation of these observations and the demonstration of clear efficacy in clinical practice have been disappointing. A major limitation might be that tools currently used to measure 'inflammation' are insufficiently precise and do not provide information about disease site and activity, or discriminate between functionally important activation pathways. The challenge, therefore, is to make measures of inflammation that are more meaningful, and which can guide specific targeted therapies. In this Review, we consider the roles of inflammatory processes in the related pathologies of atherosclerosis and acute myocardial infarction, by providing an evaluation of the known and emerging inflammatory pathways. We highlight contemporary techniques to characterize and quantify inflammation, and consider how they might be used to guide specific treatments. Finally, we discuss emerging opportunities in the field, including their current limitations and challenges that are the focus of ongoing study.

Interpretation of the evidence for the efficacy and safety of statin therapy

This Review is intended to help clinicians, patients, and the public make informed decisions about statin therapy for the prevention of heart attacks and strokes. It explains how the evidence that is available from randomised controlled trials yields reliable information about both the efficacy and safety of statin therapy. In addition, it discusses how claims that statins commonly cause adverse effects reflect a failure to recognise the limitations of other sources of evidence about the effects of treatment. Large-scale evidence from randomised trials shows that statin therapy reduces the risk of major vascular events (ie, coronary deaths or myocardial infarctions, strokes, and coronary revascularisation procedures) by about one-quarter for each mmol/L reduction in LDL cholesterol during each year (after the first) that it continues to be taken. The absolute benefits of statin therapy depend on an individual's absolute risk of occlusive vascular events and the absolute reduction in LDL cholesterol that is achieved. For example, lowering LDL cholesterol by 2 mmol/L (77 mg/dL) with an effective low-cost statin regimen (eg, atorvastatin 40 mg daily, costing about £2 per month) for 5 years in 10 000 patients would typically prevent major vascular events from occurring in about 1000 patients (ie, 10% absolute benefit) with pre-existing occlusive vascular disease (secondary prevention) and in 500 patients (ie, 5% absolute benefit) who are at increased risk but have not yet had a vascular event (primary prevention). Statin therapy has been shown to reduce vascular disease risk during each year it continues to be taken, so larger absolute benefits would accrue with more prolonged therapy, and these benefits persist long term. The only serious adverse events that have been shown to be caused by long-term statin therapy-ie, adverse effects of the statin-are myopathy (defined as muscle pain or weakness combined with large increases in blood concentrations of creatine kinase), new-onset diabetes mellitus, and, probably, haemorrhagic stroke. Typically, treatment of 10 000 patients for 5 years with an effective regimen (eg, atorvastatin 40 mg daily) would cause about 5 cases of myopathy (one of which might progress, if the statin therapy is not stopped, to the more severe condition of rhabdomyolysis), 50-100 new cases of diabetes, and 5-10 haemorrhagic strokes. However, any adverse impact of these side-effects on major vascular events has already been taken into account in the estimates of the absolute benefits. Statin therapy may cause symptomatic adverse events (eg, muscle pain or weakness) in up to about 50-100 patients (ie, 0·5-1·0% absolute harm) per 10 000 treated for 5 years. However, placebo-controlled randomised trials have shown definitively that almost all of the symptomatic adverse events that are attributed to statin therapy in routine practice are not actually caused by it (ie, they represent misattribution). The large-scale evidence available from randomised trials also indicates that it is unlikely that large absolute excesses in other serious adverse events still await discovery. Consequently, any further findings that emerge about the effects of statin therapy would not be expected to alter materially the balance of benefits and harms. It is, therefore, of concern that exaggerated claims about side-effect rates with statin therapy may be responsible for its under-use among individuals at increased risk of cardiovascular events. For, whereas the rare cases of myopathy and any muscle-related symptoms that are attributed to statin therapy generally resolve rapidly when treatment is stopped, the heart attacks or strokes that may occur if statin therapy is stopped unnecessarily can be devastating.

The central role of arterial retention of cholesterol-rich apolipoprotein-B-containing lipoproteins in the pathogenesis of atherosclerosis: a triumph of simplicity

PURPOSE OF REVIEW

Today, it is no longer a hypothesis, but an established fact, that increased plasma concentrations of cholesterol-rich apolipoprotein-B (apoB)-containing lipoproteins are causatively linked to atherosclerotic cardiovascular disease (ASCVD) and that lowering plasma LDL concentrations reduces cardiovascular events in humans. Here, we review evidence behind this assertion, with an emphasis on recent studies supporting the 'response-to-retention' model - namely, that the key initiating event in atherogenesis is the retention, or trapping, of cholesterol-rich apoB-containing lipoproteins within the arterial wall.

RECENT FINDINGS

New clinical trials have shown that ezetimibe and anti-PCSK9 antibodies - both nonstatins - lower ASCVD events, and they do so to the same extent as would be expected from comparable plasma LDL lowering by a statin. These studies demonstrate beyond any doubt the causal role of apoB-containing lipoproteins in atherogenesis. In addition, recent laboratory experimentation and human Mendelian randomization studies have revealed novel information about the critical role of apoB-containing lipoproteins in atherogenesis. New information has also emerged on mechanisms for the accumulation in plasma of harmful cholesterol-rich and triglyceride-rich apoB-containing remnant lipoproteins in states of overnutrition. Like LDL, these harmful cholesterol-rich and triglyceride-rich apoB-containing remnant lipoprotein remnants become retained and modified within the arterial wall, causing atherosclerosis.

SUMMARY

LDL and other cholesterol-rich, apoB-containing lipoproteins, once they become retained and modified within the arterial wall, cause atherosclerosis. This simple, robust pathophysiologic understanding may finally allow us to eradicate ASCVD, the leading killer in the world.

Microvesicles in Autoimmune Diseases

During apoptosis or activation, cells can release a subcellular structure, called a membrane microvesicle (also known as microparticle) into the extracellular environment. Microvesicles bud-off as a portion of cell membrane with its associated proteins and lipids surrounding a cytosolic core that contains intracellular proteins, lipids, and nucleic acids (DNA, RNA, siRNA, microRNA, lncRNA). Biologically active molecules on the microvesicle surface and encapsulated within can act on recipient cells as a novel mode of intercellular communication. Apoptosis has long been known to be involved in the development of diseases of autoimmunity. Abnormally persistent microvesicles, particularly apoptotic microvesicles, can accelerate autoimmune responses locally in specific organs and tissues as well as systemically. In this review, we focus on studies implicating microvesicles in the pathogenesis of autoimmune diseases and their complications.

Immune dysregulation mediated by the oral microbiome: potential link to chronic inflammation and atherosclerosis

Cardiovascular disease is an inflammatory disorder characterized by the progressive formation of plaque in coronary arteries, termed atherosclerosis. It is a multifactorial disease that is one of the leading causes of death worldwide. Although a number of risk factors have been associated with disease progression, the underlying inflammatory mechanisms contributing to atherosclerosis remain to be fully delineated. Within the last decade, the potential role for infection in inflammatory plaque progression has received considerable interest. Microbial pathogens associated with periodontal disease have been of particular interest due to the high levels of bacteremia that are observed after routine dental procedures and every day oral activities, such as tooth brushing. Here, we explore the potential mechanisms that may explain how periodontal pathogens either directly or indirectly elicit immune dysregulation and consequently progressive inflammation manifested as atherosclerosis. Periodontal pathogens have been shown to contribute directly to atherosclerosis by disrupting endothelial cell function, one of the earliest indicators of cardiovascular disease. Oral infection is thought to indirectly induce elevated production of inflammatory mediators in the systemic circulation. Recently, a number of studies have been conducted focusing on how disruption of the gut microbiome influences the systemic production of proinflammatory cytokines and consequently exacerbation of inflammatory diseases such as atherosclerosis. It is clear that the immune mechanisms leading to atherosclerotic plaque progression, by oral infection, are complex. Understanding the immune pathways leading to disease progression is essential for the future development of anti-inflammatory therapies for this chronic disease.