Decreased atherosclerosis in mice deficient in both macrophage colony-stimulating factor (op) and apolipoprotein E

Deficiency of 5-HT2B receptors alleviates atherosclerosis by regulating macrophage phenotype through inhibiting interferon signalling

BACKGROUND AND PURPOSE

Elevated levels of 5-HT have been correlated with coronary artery disease and cardiac events, suggesting 5-HT is a potential novel factor in the development of atherosclerotic cardiovascular disease. However, the underlying pathological mechanisms of the 5-HT system in atherosclerosis remain unclear. The 5-HT2B receptor (5-HT2BR), which establishes a positive feedback loop with 5-HT, has been identified as a contributor to pathophysiological processes in various vascular disorders. In this study, we investigated the immunological impact of 5-HT2BR in atherosclerosis-prone apolipoprotein E-deficient (ApoE-/-) mice.

EXPERIMENTAL APPROACH

Plasma levels of 5-HT were measured in mice using an ELISA kit. Atherosclerotic plaque formation, macrophage infiltration and inflammatory signalling were assessed in ApoE-/- mice by employing both pharmacological inhibition and genetic deficiency of 5-HT2BR. Inflammasome activation was elucidated using peritoneal macrophages isolated from 5-HT2BR-deficient mice.

KEY RESULTS

An upregulation of 5-HT2BR expression was observed in the aortas of ApoE-/- mice, exhibiting a strong correlation with the presence of macrophages in plaques. Atherosclerosis was attenuated in mice through pharmacological inhibition and genetic deficiency of 5-HT2BR. Additionally, a significant reduction in atherosclerotic plaque size was achieved through bone marrow reconstitution with 5-HT2BR-deficient cells. 5-HT2BR-deficient macrophages showed attenuated interferon (IFN) signalling, NLRP3 inflammasome activation, and interleukin-1β release. Moreover, macrophages primed with 5-HT2BR deficiency displayed an anti-inflammatory phenotype.

CONCLUSION AND IMPLICATIONS

These findings support the hypothesis that 5-HT2BR in macrophages plays a causal role in the development of atherosclerosis, revealing a novel perspective for potential therapeutic strategies in atherosclerosis-related diseases.

Colony stimulating factor 1 receptor (Csf1r) expressing cell ablation in mafia (macrophage-specific Fas-induced apoptosis) mice alters monocyte landscape and atherosclerotic lesion characteristics

Macrophage infiltration and accumulation in the atherosclerotic lesion are associated with plaque progression and instability. Depletion of macrophages from the lesion might provide valuable insights into plaque stabilization processes. Therefore, we assessed the effects of systemic and local macrophage depletion on atherogenesis. To deplete monocytes/macrophages we used atherosclerosis-susceptible Apoe- /- mice, bearing a MaFIA (macrophage-Fas-induced-apoptosis) suicide construct under control of the Csf1r (CD115) promotor, where selective apoptosis of Csf1r-expressing cells was induced in a controlled manner, by administration of a drug, AP20187. Systemic induction of apoptosis resulted in a decrease in lesion macrophages and smooth-muscle cells. Plaque size and necrotic core size remained unaffected. Two weeks after the systemic depletion of macrophages, we observed a replenishment of the myeloid compartment. Myelopoiesis was modulated resulting in an expansion of CSF1Rlo myeloid cells in the circulation and a shift from Ly6chi monocytes toward Ly6cint and Ly6clo populations in the spleen. Local apoptosis induction led to a decrease in plaque burden and macrophage content with marginal effects on the circulating myeloid cells. Local, but not systemic depletion of Csf1r+ myeloid cells resulted in decreased plaque burden. Systemic depletion led to CSF1Rlo-monocyte expansion in blood, possibly explaining the lack of effects on plaque development.

Biomimetic Nanoparticles for the Diagnosis and Therapy of Atherosclerosis

Atherosclerosis (AS) is a chronic inflammation of blood vessels, which often has no obvious symptoms in the early stage of the disease, but when atherosclerotic plaques are formed, they often cause lumen blockage, and even plaque rupture leads to thrombosis, that is the essential factor of cardiovascular events, for example myocardial infarction, cerebral infarction, and renal atrophy. Therefore, it is considerably significant for the early recognition and precise therapy of plaque. Biomimetic nanoparticles (BNPs), especially those coated with cell membranes, can retain the biological function of cell membranes or cells, which has led to extensive research and application in the diagnosis and treatment of AS in recent years. In this review, we summarized the roles of various key cells in AS progression, the construction of biomimetic nanoparticles based on these key cells as well as their applications in AS diagnosis and therapy. Furthermore, we give a challenge and prospect of biomimetic nanoparticles in AS, hoping to elevate their application quality and the possibility of clinical translation.

Translating Anti-Inflammatory Strategies for Atherosclerosis: Deep Phenotyping, Next-Generation Drug Targets, and Precision Medicine

Atherosclerosis is the main pathology underlying cardiovascular disease (CVD), including myocardial infarction and ischemic stroke [...].

Predictive value of baseline alpha defensin level in patients with stable coronary artery disease: A retrospective single center study

Background

Inflammation plays a central role in atherogenesis. The major neutrophilic peptide alpha-defensin is a promising evolving risk factor for atherosclerosis. The aim of the present study was to examine the role of alpha-defensin in predicting future major adverse cardiovascular events (MACE) occurrence in fully revascularized patients with stable CAD under optimal medical therapy.

Methods and results

We retrospectively examined the prognostic value of baseline plasma alpha-defensin levels in predicting MACE occurrence in 174 fully revascularized patients for stable CAD between March 2016 and January 2017. Alpha-defensin levels were found 20 % higher among demised patients (10,859 pg/ml, IQR [6,920 to 23,320] vs. 9,020 pg/ml, IQR [5,540 to 16,180] pg/ml, P = 0.15). The absolute increase in mortality risk in patients with alpha-defensin levels greater than the median values was 72.5 % (P = 0.33). Log-rank analysis proved both recurrent PCI for de novo lesions (14.9 % and 2.3 %) and the composite of mortality and recurrent PCI for de novo lesions (27.6 % vs. 9.2 %) were significantly related to alpha-defensin values greater than the median (>9200 pg/ml).

Conclusion

Baseline plasma alpha-defensin is an independent predictor of mortality and recurrent PCI among patients with stable CAD. Alpha-defensin may evolve as a promising factor in cardiovascular risk assessment beyond traditional risk factors. Targeting alpha-defensin to ameliorate MACE occurrence should be addressed in future studies.

Insights from Murine Studies on the Site Specificity of Atherosclerosis

Atherosclerosis is an inflammatory reaction that develops at specific regions within the artery wall and at specific sites of the arterial tree over a varying time frame in response to a variety of risk factors. The mechanisms that account for the interaction of systemic factors and atherosclerosis-susceptible regions of the arterial tree to mediate this site-specific development of atherosclerosis are not clear. The dynamics of blood flow has a major influence on where in the arterial tree atherosclerosis develops, priming the site for interactions with atherosclerotic risk factors and inducing cellular and molecular participants in atherogenesis. But how this accounts for lesion development at various locations along the vascular tree across differing time frames still requires additional study. Currently, murine models are favored for the experimental study of atherogenesis and provide the most insight into the mechanisms that may contribute to the development of atherosclerosis. Based largely on these studies, in this review, we discuss the role of hemodynamic shear stress, SR-B1, and other factors that may contribute to the site-specific development of atherosclerosis.

Disparity of gene expression in coronary artery disease: insights from MEIS1, HIRA, and Myocardin

INTRODUCTION

Coronary artery disease (CAD) in young adults can have devastating consequences. The cardiac developmental gene MEIS1 plays important roles in vascular networks and heart development. This gene effects on the regeneration capacity of the heart. Considering role of MEIS1 in cardiac tissue development and the progression of myocardial infarction this study investigated the expression levels of the MEIS1, HIRA, and Myocardin genes in premature CAD patients compared to healthy subjects and evaluated the relationships between these genes and possible inflammatory factors.

METHODS AND RESULTS

The study conducted a case-control design involving 35 CAD patients and 35 healthy individuals. Peripheral blood mononuclear cells (PBMCs) were collected, and gene expression analysis was performed using real-time PCR. Compared with control group, the number of PBMCs in the CAD group exhibited greater MEIS1 and HIRA gene expression, with fold changes of 2.45 and 3.6. The expression of MEIS1 exhibited a negative correlation with IL-10 (r= -0.312) expression and positive correlation with Interleukin (IL)-6 (r = 0.415) and tumor necrosis factor (TNF)-α (r = 0.534) gene expression. Moreover, there was an inverse correlation between the gene expression of HIRA and that of IL-10 (r= -0.326), and a positive correlation was revealed between the expression of this gene and that of the IL-6 (r = 0.453) and TNF-α (r = 0.572) genes.

CONCLUSION

This research demonstrated a disparity in expression levels of MEIS1, HIRA, and Myocardin, between CAD and healthy subjects. The results showed that, MEIS1 and HIRA play significant roles in regulating the synthesis of proinflammatory cytokines, namely, TNF-α and IL-6.

Metabolic Derangement by Arsenic: a Review of the Mechanisms

Studies have implicated arsenic exposure in various pathological conditions, including metabolic disorders, which have become a global phenomenon, affecting developed, developing, and under-developed nations. Despite the huge risks associated with arsenic exposure, humans remain constantly exposed to it, especially through the consumption of contaminated water and food. This present study provides an in-depth insight into the mechanistic pathways involved in the metabolic derangement by arsenic. Compelling pieces of evidence demonstrate that arsenic induces metabolic disorders via multiple pathways. Apart from the initiation of oxidative stress and inflammation, arsenic prevents the phosphorylation of Akt at Ser473 and Thr308, leading to the inhibition of PDK-1/Akt insulin signaling, thereby reducing GLUT4 translocation through the activation of Nrf2. Also, arsenic downregulates mitochondrial deacetylase Sirt3, decreasing the ability of its associated transcription factor, FOXO3a, to bind to the agents that support the genes for manganese superoxide dismutase and PPARg co-activator (PGC)-1a. In addition, arsenic activates MAPKs, modulates p53/ Bcl-2 signaling, suppresses Mdm-2 and PARP, activates NLRP3 inflammasome and caspase-mediated apoptosis, and induces ER stress, and ox-mtDNA-dependent mitophagy and autophagy. More so, arsenic alters lipid metabolism by decreasing the presence of 3-hydroxy-e-methylglutaryl-CoA synthase 1 and carnitine O-octanoyl transferase (Crot) and increasing the presence of fatty acid-binding protein-3 mRNA. Furthermore, arsenic promotes atherosclerosis by inducing endothelial damage. This cascade of pathophysiological events promotes metabolic derangement. Although the pieces of evidence provided by this study are convincing, future studies evaluating the involvement of other likely mechanisms are important. Also, epidemiological studies might be necessary for the translation of most of the findings in animal models to humans.

Myocardial infarction drives trained immunity of monocytes, accelerating atherosclerosis

BACKGROUND AND AIMS

Survivors of acute coronary syndromes face an elevated risk of recurrent atherosclerosis-related vascular events despite advanced medical treatments. The underlying causes remain unclear. This study aims to investigate whether myocardial infarction (MI)-induced trained immunity in monocytes could sustain proatherogenic traits and expedite atherosclerosis.

METHODS

Apolipoprotein-E deficient (ApoE-/-) mice and adoptive bone marrow transfer chimeric mice underwent MI or myocardial ischaemia-reperfusion (IR). A subsequent 12-week high-fat diet (HFD) regimen was implemented to elucidate the mechanism behind monocyte trained immunity. In addition, classical monocytes were analysed by flow cytometry in the blood of enrolled patients.

RESULTS

In MI and IR mice, blood monocytes and bone marrow-derived macrophages exhibited elevated spleen tyrosine kinase (SYK), lysine methyltransferase 5A (KMT5A), and CCHC-type zinc finger nucleic acid-binding protein (CNBP) expression upon exposure to a HFD or oxidized LDL (oxLDL) stimulation. MI-induced trained immunity was transmissible by transplantation of bone marrow to accelerate atherosclerosis in naive recipients. KMT5A specifically recruited monomethylation of Lys20 of histone H4 (H4K20me) to the gene body of SYK and synergistically transactivated SYK with CNBP. In vivo small interfering RNA (siRNA) inhibition of KMT5A or CNBP potentially slowed post-MI atherosclerosis. Sympathetic denervation with 6-hydroxydopamine reduced atherosclerosis and inflammation after MI. Classical monocytes from ST-elevation MI (STEMI) patients with advanced coronary lesions expressed higher SYK and KMT5A gene levels.

CONCLUSIONS

The findings underscore the crucial role of monocyte trained immunity in accelerated atherosclerosis after MI, implying that SYK in blood classical monocytes may serve as a predictive factor for the progression of atherosclerosis in STEMI patients.

Immunotherapy-Associated Atherosclerosis: A Comprehensive Review of Recent Findings and Implications for Future Research

Purpose of the Review

Even as immune checkpoint inhibitors (ICIs) have transformed the lifespan of many patients, they may also trigger acceleration of long-term cardiovascular disease. Our review aims to examine the current landscape of research on ICI-mediated atherosclerosis and address key questions regarding its pathogenesis and impact on patient management.

Recent Findings

Preclinical mouse models suggest that T cell dysregulation and proatherogenic cytokine production are key contributors to plaque development after checkpoint inhibition. Clinical data also highlight the significant burden of atherosclerotic cardiovascular disease (ASCVD) in patients on immunotherapy, although the value of proactively preventing and treating ASCVD in this population remains an open area of inquiry. Current treatment options include dietary/lifestyle modification and traditional medications to manage hypertension, hyperlipidemia, and diabetes risk factors; no current targeted therapies exist.

Summary

Early identification of high-risk patients is crucial for effective preventive strategies and timely intervention. Future research should focus on refining screening tools, elucidating targetable mechanisms driving ICI atherosclerosis, and evaluating long-term cardiovascular outcomes in cancer survivors who received immunotherapy. Moreover, close collaboration between oncologists and cardiologists is essential to optimize patient outcomes.

Atherosclerosis antigens as targets for immunotherapy

Atherosclerosis is a chronic inflammatory disease of the arteries that can lead to thrombosis, infarction and stroke, underlying the first cause of mortality worldwide. Adaptive immunity plays critical roles in atherosclerosis, and numerous studies have ascribed both atheroprotective and atherogenic functions to specific subsets of T and B cells. However, less is known on how antigen specificity determines the protective or adverse outcome of such adaptive responses. Understanding antigen triggers in atherosclerosis is crucial to delve deeper into mechanisms of disease initiation and progression and to implement specific immunotherapeutic approaches, including vaccination strategies. Here we review the role of adaptive immunity in atherosclerosis and the insights that single-cell technology has provided into the function of distinct immune cell subsets. We outline the most relevant atherosclerosis antigens and antibodies reported to date and examine their immunotherapeutic potential. Finally, we review the most promising vaccination-based clinical trials targeting the adaptive immune system.

Vitisin A, as a Type of Pyranoanthocyanin, Suppresses Inflammation by Restricting Hematopoietic Stem Cell Differentiation toward Monocytes in Bone Marrow

Hematopoietic stem and progenitor cells (HSPCs) could be differentiated into mature myeloid and lymphoid cells, maintaining the requirements of immune cells. Atherosclerosis and ulcerative colitis (UC) drive HSPC homeostasis destruction, which triggers expansive HSPC proliferation and Ly6Chi monocyte production, contributing to aggravated inflammation. Vitisin A belongs to the anthocyanin derivatives with excellent stability and bioactivity in vitro. However, there is no report about the anti-inflammation of Vitisin A via reprogramming HSPC differentiation toward monocytes. In this study, we found that Vitisin A presents anti-inflammatory ability during the development of atherosclerosis and UC by depressing Ly6Chi monocyte production from bone marrow. This performance depended on restricted HSPC differentiation, which suggested that Vitisin A participated in monocyte generation and carried out the immunomodulation. Together, Vitisin A ameliorates inflammation during atherosclerosis and UC via the suppressed differentiation of HSPCs toward monocytes, which could be considered an ideal functional component with immunomodulatory effects.

Targeting mitochondrial function in macrophages: A novel treatment strategy for atherosclerotic cardiovascular disease?

Atherosclerotic cardiovascular disease is a major cause of morbidity and mortality due to chronic arterial injury caused by hyperlipidemia, hypertension, inflammation and oxidative stress. Recent studies have shown that the progression of this disease is associated with mitochondrial dysfunction and with the accumulation of mitochondrial alterations within macrophages of atherosclerotic plaques. These alterations contribute to processes of inflammation and oxidative stress. Among the many players involved, macrophages play a pivotal role in atherogenesis as they can exert both beneficial and deleterious effects due to their anti- and pro-inflammatory properties. Their atheroprotective functions, such as cholesterol efflux and efferocytosis, as well as the maintenance of their polarization towards an anti-inflammatory state, are particularly dependent on mitochondrial metabolism. Moreover, in vitro studies have demonstrated deleterious effects of oxidized LDL on macrophage mitochondrial function, resulting in a switch to a pro-inflammatory state and to a potential loss of atheroprotective capacity. Therefore, preservation of mitochondrial function is now considered a legitimate therapeutic strategy. This review focuses on the potential therapeutic strategies that could improve the mitochondrial function of macrophages, enabling them to maintain their atheroprotective capacity. These emerging therapies could play a valuable role in counteracting the progression of atherosclerotic lesions and possibly inducing their regression.

In Vitro Anti-Inflammatory and Vasculoprotective Effects of Red Cell Extract from the Black Sea Urchin Arbacia lixula

Sea urchins have emerged as an important source of bioactive compounds with anti-inflammatory and antioxidant properties relevant to human health. Since inflammation is a crucial pathogenic process in the development and progression of atherosclerosis, we here assessed the potential anti-inflammatory and vasculoprotective effects of coelomic red-cell methanolic extract of the black sea urchin Arbacia lixula in an in vitro model of endothelial cell dysfunction. Human microvascular endothelial cells (HMEC-1) were pretreated with A. lixula red-cell extract (10 and 100 μg/mL) before exposure to the pro-inflammatory cytokine tumor necrosis factor (TNF)-α. The extract was non-toxic after 24 h cell treatment and was characterized by antioxidant power and phenol content. The TNF-α-stimulated expression of adhesion molecules (VCAM-1, ICAM-1) and cytokines/chemokines (MCP-1, CCL-5, IL-6, IL-8, M-CSF) was significantly attenuated by A. lixula red-cell extract. This was functionally accompanied by a reduction in monocyte adhesion and chemotaxis towards activated endothelial cells. At the molecular level, the tested extract significantly counteracted the TNF-α-stimulated activation of the pro-inflammatory transcription factor NF-κB. These results provide evidence of potential anti-atherosclerotic properties of A. lixula red-cell extract, and open avenues in the discovery and development of dietary supplements and/or drugs for the prevention or treatment of cardiovascular diseases.

A Hidden Organism, Chlamydia in the Age of Atherosclerosis

Atherosclerosis is a chronic inflammatory disease. It is still the leading cause of mortality and morbidity in the world. Inflammation in the vessels plays the most important role in the pathogenesis of atherosclerosis. Many studies have been emphasized that Chlamydia pneumoniae triggers inflammation in the vessels and associated with atherosclerosis. It is stated that most of the chlamydial infections are asymptomatic and around 40% of adult individuals are infected. Chlamydia has different subgroups. It was thought to be a virus due to its intracellular pathogenicity, but it was included in the bacteria genus because it contains DNA and RNA chromosomes and has enzymatic activity. Chlamidya can easily be transmitted through the respiratory tract and sexual transmission. Seroepidemiological and pathological studies of atherosclerotic plaques showed the presence of Chlamydia in the plaque. This section will provide relationship between Chlamydia and atherosclerosis on the recent researces and current information will be discussed.

Whole-Transcriptome Sequencing Analyses of Nuclear Antixoxidant-1 in Endothelial Cells: Role in Inflammation and Atherosclerosis

Inflammation, oxidative stress, and copper (Cu) play an important role in cardiovascular disease, including atherosclerosis. We previously reported that cytosolic Cu chaperone antioxidant-1 (Atox1) translocates to the nucleus in response to inflammatory cytokines or exogenous Cu and that Atox1 is localized at the nucleus in the endothelium of inflamed atherosclerotic aorta. However, the roles of nuclear Atox1 and their function are poorly understood. Here we showed that Atox1 deficiency in ApoE-/- mice with a Western diet exhibited a significant reduction of atherosclerotic lesion formation. In vitro, adenovirus-mediated overexpression of nuclear-targeted Atox1 (Ad-Atox1-NLS) in cultured human endothelial cells (ECs) increased monocyte adhesion and reactive oxygen species (ROS) production compared to control cells (Ad-null). To address the underlying mechanisms, we performed genome-wide mapping of Atox1-regulated targets in ECs, using an unbiased systemic approach integrating sequencing data. Combination of ChIP-Seq and RNA-Seq analyses in ECs transfected with Ad-Atox1-NLS or Ad-null identified 1387 differentially expressed genes (DEG). Motif enrichment assay and KEGG pathway enrichment analysis revealed that 248 differentially expressed genes, including inflammatory and angiogenic genes, were regulated by Atox1-NLS, which was then confirmed by real-time qPCR. Among these genes, functional analysis of inflammatory responses identified CD137, CSF1, and IL5RA as new nuclear Atox1-targeted inflammatory genes, while CD137 is also a key regulator of Atox1-NLS-induced ROS production. These findings uncover new nuclear Atox1 downstream targets involved in inflammation and ROS production and provide insights into the nuclear Atox1 as a potential therapeutic target for the treatment of inflammatory diseases such as atherosclerosis.

Understanding the role of alternative macrophage phenotypes in human atherosclerosis

INTRODUCTION

Atherosclerosis-based ischemic heart disease is still the primary cause of death throughout the world. Over the past decades there has been no significant changes in the therapeutic approaches to atherosclerosis, which are mainly based on lipid lowering therapies and management of comorbid conditions such as diabetes and hypertension. The involvement of macrophages in atherosclerosis has been recognized for decades. More recently, a more detailed and sophisticated understanding of their various phenotypes and roles in the atherosclerotic process has been recognized. This new data is revealing how specific subtypes of macrophage-induced inflammation may have distinct effects on atherosclerosis progression and may provide new approaches for treatment, based upon targeting of specific macrophage subtypes.

AREAS COVERED

We will comprehensively review the spectrum of macrophage phenotypes and how they contribute to atherosclerotic plaque development and progression.

EXPERT OPINION

Various signals derived from atherosclerotic lesions drive macrophages into complex subsets with different gene expression profiles, phenotypes, and functions, not all of which are understood. Macrophage phenotypes include those that enhance, heal, and regress the atherosclerotic lesions though various mechanisms. Targeting of specific macrophage phenotypes may provide a promising and novel approach to prevent atherosclerosis progression.

Smooth Muscle Cell—Macrophage Interactions Leading to Foam Cell Formation in Atherosclerosis: Location, Location, Location

Cholesterol-overloaded cells or “foam cells” in the artery wall are the biochemical hallmark of atherosclerosis, and are responsible for much of the growth, inflammation and susceptibility to rupture of atherosclerotic lesions. While it has previously been thought that macrophages are the main contributor to the foam cell population, recent evidence indicates arterial smooth muscle cells (SMCs) are the source of the majority of foam cells in both human and murine atherosclerosis. This review outlines the timeline, site of appearance and proximity of SMCs and macrophages with lipids in human and mouse atherosclerosis, and likely interactions between SMCs and macrophages that promote foam cell formation and removal by both cell types. An understanding of these SMC-macrophage interactions in foam cell formation and regression is expected to provide new therapeutic targets to reduce the burden of atherosclerosis for the prevention of coronary heart disease, stroke and peripheral vascular disease.

Loss of CD226 protects apolipoprotein E-deficient mice from diet-induced atherosclerosis

CD226 is a costimulatory molecule that regulates immune cell functions in T cells, natural killer cells, and macrophages. Because macrophage-derived foam cell formation is a crucial factor contributing to the development of atherosclerosis, we aimed to evaluate the potential roles of CD226 in the pathogenesis of atherosclerosis. The effects of CD226 on atherosclerosis were investigated in CD226 and apolipoprotein E double-knockout (CD226^-/- ApoE^-/-) mice fed with a high-cholesterol atherogenic diet. CD226 expression in macrophages was evaluated using flow cytometry. Histopathological analysis was performed to evaluate the atherosclerotic lesions. Inflammatory cell infiltration was detected using immunofluorescence staining. Bone marrow-derived macrophages (BMDMs) and peritoneal macrophages (PEMs) were isolated from the mice and used to explore the mechanism in vitro. The in vivo results indicated that CD226 knockdown protected against atherosclerosis in ApoE^-/- mice, evidenced by reduced plaque accumulation in the brachiocephalic artery, aortic roots, and main aortic tree. CD226 gene-deficient macrophages showed reduced foam cell formation under ox-low density lipoprotein stimulation compared with wild-type (WT) cells. CD226 deficiency also decreased the expression of CD36 and scavenger receptor (SR)-A (responsible for lipoprotein uptake) but increased the expression of ATP-binding cassette transporter A1 and G1 (two transporters for cholesterol efflux). Therefore, loss of CD226 hinders foam cell formation and atherosclerosis progression, suggesting that CD226 is a promising new therapeutic target for atherosclerosis.

A Role of IL-17 in Rheumatoid Arthritis Patients Complicated With Atherosclerosis

Rheumatoid arthritis (RA) is mainly caused by joint inflammation. RA significantly increases the probability of cardiovascular disease. Although the progress of RA has been well controlled recently, the mortality of patients with RA complicated with cardiovascular disease is 1.5–3 times higher than that of patients with RA alone. The number of people with atherosclerosis in patients with RA is much higher than that in the general population, and atherosclerotic lesions develop more rapidly in patients with RA, which has become one of the primary factors resulting in the death of patients with RA. The rapid development of atherosclerosis in RA is induced by inflammation-related factors. Recent studies have reported that the expression of IL-17 is significantly upregulated in patients with RA and atherosclerosis. Simultaneously, there is evidence that IL-17 can regulate the proliferation, migration, and apoptosis of vascular endothelial cells and vascular smooth muscle cells through various ways and promote the secretion of several cytokines leading to the occurrence and development of atherosclerosis. Presently, there is no clear prevention or treatment plan for atherosclerosis in patients with RA. Therefore, this paper explores the mechanism of IL-17 in RA complicated with atherosclerosis and shows the reasons for the high incidence of atherosclerosis in patients with RA. It is hoped that the occurrence and development of atherosclerosis in patients with RA can be diagnosed or prevented in time in the early stage of lesions, and the prevention and treatment of cardiovascular complications in patients with RA can be enhanced to reduce mortality.

Therapeutic strategies targeting inflammation and immunity in atherosclerosis: how to proceed?

Atherosclerosis is a chronic inflammatory disease of the arterial wall, characterized by the formation of plaques containing lipid, connective tissue and immune cells in the intima of large and medium-sized arteries. Over the past three decades, a substantial reduction in cardiovascular mortality has been achieved largely through LDL-cholesterol-lowering regimes and therapies targeting other traditional risk factors for cardiovascular disease, such as hypertension, smoking, diabetes mellitus and obesity. However, the overall benefits of targeting these risk factors have stagnated, and a huge global burden of cardiovascular disease remains. The indispensable role of immunological components in the establishment and chronicity of atherosclerosis has come to the forefront as a clinical target, with proof-of-principle studies demonstrating the benefit and challenges of targeting inflammation and the immune system in cardiovascular disease. In this Review, we provide an overview of the role of the immune system in atherosclerosis by discussing findings from preclinical research and clinical trials. We also identify important challenges that need to be addressed to advance the field and for successful clinical translation, including patient selection, identification of responders and non-responders to immunotherapies, implementation of patient immunophenotyping and potential surrogate end points for vascular inflammation. Finally, we provide strategic guidance for the translation of novel targets of immunotherapy into improvements in patient outcomes.

In this Review, the authors provide an overview of the immune cells involved in atherosclerosis, discuss preclinical research and published and ongoing clinical trials assessing the therapeutic potential of targeting the immune system in atherosclerosis, highlight emerging therapeutic targets from preclinical studies and identify challenges for successful clinical translation.

Inflammation is an important component of the pathophysiology of cardiovascular disease; an imbalance between pro-inflammatory and anti-inflammatory processes drives chronic inflammation and the formation of atherosclerotic plaques in the vessel wall.

Clinical trials assessing canakinumab and colchicine therapies in atherosclerotic cardiovascular disease have provided proof-of-principle of the benefits associated with therapeutic targeting of the immune system in atherosclerosis.

The immunosuppressive adverse effects associated with the systemic use of anti-inflammatory drugs can be minimized through targeted delivery of anti-inflammatory drugs to the atherosclerotic plaque, defining the window of opportunity for treatment and identifying more specific targets for cardiovascular inflammation.

Implementing immunophenotyping in clinical trials in patients with atherosclerotic cardiovascular disease will allow the identification of immune signatures and the selection of patients with the highest probability of deriving benefit from a specific therapy.

Clinical stratification via novel risk factors and discovery of new surrogate markers of vascular inflammation are crucial for identifying new immunotherapeutic targets and their successful translation into the clinic.

Trafficking of Mononuclear Phagocytes in Healthy Arteries and Atherosclerosis

Monocytes and macrophages play essential roles in all stages of atherosclerosis – from early precursor lesions to advanced stages of the disease. Intima-resident macrophages are among the first cells to be confronted with the influx and retention of apolipoprotein B-containing lipoproteins at the onset of hypercholesterolemia and atherosclerosis development. In this review, we outline the trafficking of monocytes and macrophages in and out of the healthy aorta, as well as the adaptation of their migratory behaviour during hypercholesterolemia. Furthermore, we discuss the functional and ontogenetic composition of the aortic pool of mononuclear phagocytes and its link to the atherosclerotic disease process. The development of mouse models of atherosclerosis regression in recent years, has enabled scientists to investigate the behaviour of monocytes and macrophages during the resolution of atherosclerosis. Herein, we describe the dynamics of these mononuclear phagocytes upon cessation of hypercholesterolemia and how they contribute to the restoration of tissue homeostasis. The aim of this review is to provide an insight into the trafficking, fate and disease-relevant dynamics of monocytes and macrophages during atherosclerosis, and to highlight remaining questions. We focus on the results of rodent studies, as analysis of cellular fates requires experimental manipulations that cannot be performed in humans but point out findings that could be replicated in human tissues. Understanding of the biology of macrophages in atherosclerosis provides an important basis for the development of therapeutic strategies to limit lesion formation and promote plaque regression.

Regulation of Macrophage Activation and Differentiation in Atherosclerosis

Chronic inflammation is a hallmark of atherosclerosis and macrophages play a central role in controlling inflammation at all stages of atherosclerosis. In atherosclerosis, macrophages and monocyte-derived macrophages are continuously exposed to cholesterol, oxidized lipids, cell debris, cytokines, and chemokines. Not only do these stimuli induce a specific macrophage phenotype, but they also interact extensively, leading to macrophage heterogeneity in atherosclerotic plaques. Herein, we review the diverse phenotypes of macrophages, the mechanisms underlying macrophage activation, and the contributions of macrophages to atherosclerosis in this context. We also summarize recent studies on foamy macrophages and monocyte-derived macrophages in plaque during disease progression. We provide a comprehensive overview of transcriptional, epigenetic, and metabolic reprogramming of macrophages and discuss the emerging concepts of targeting cytokines and macrophages to modulate atherosclerosis.

Exploiting dynamic enhancer landscapes to decode macrophage and microglia phenotypes in health and disease

The development and functional potential of metazoan cells is dependent on combinatorial roles of transcriptional enhancers and promoters. Macrophages provide exceptionally powerful model systems for investigation of mechanisms underlying the activation of cell-specific enhancers that drive transitions in cell fate and cell state. Here, we review recent advances that have expanded appreciation of the diversity of macrophage phenotypes in health and disease, emphasizing studies of liver, adipose tissue, and brain macrophages as paradigms for other tissue macrophages and cell types. Studies of normal tissue-resident macrophages and macrophages associated with cirrhosis, obese adipose tissue, and neurodegenerative disease illustrate the major roles of tissue environment in remodeling enhancer landscapes to specify the development and functions of distinct macrophage phenotypes. We discuss the utility of quantitative analysis of environment-dependent changes in enhancer activity states as an approach to discovery of regulatory transcription factors and upstream signaling pathways.

Ang II-Induced Hypertension Exacerbates the Pathogenesis of Tuberculosis

It has been known that infection plays a role in the development of hypertension. However, the role of hypertension in the progression of infectious diseases remain unknown. Many countries with high rates of hypertension show geographical overlaps with those showing high incidence rates of tuberculosis (TB). To explore the role of hypertension in tuberculosis, we compared the effects of hypertension during mycobacterial infection, we infected both hypertensive Angiotensin II (Ang II) and control mice with Mycobacterium tuberculosis (Mtb) strain H37Ra by intratracheal injection. Ang II-induced hypertension promotes cell death through both apoptosis and necrosis in Mtb H37Ra infected mouse lungs. Interestingly, we found that lipid accumulation in pulmonary tissues was significantly increased in the hypertension group compared to the normal controls. Ang II-induced hypertension increases the formation of foamy macrophages during Mtb infection and it leads to cell death. Moreover, the hypertension group showed more severe granuloma formation and fibrotic lesions in comparison with the control group. Finally, we observed that the total number of mycobacteria was increased in the lungs in the hypertension group compared to the normal controls. Taken together, these results suggest that hypertension increases intracellular survival of Mtb through formation of foamy macrophages, resulting in severe pathogenesis of TB.

Vascular Inflammation in Cardiovascular Disease: Is Immune System Protective or Bystander?

Cardiovascular disease (CVD) is one of the leading causes of death worldwide. Chronic atherosclerosis induced vascular inflammation and perturbation of lipid metabolism is believed to be a major cause of CVD. Interplay of innate and adaptive Immune system has been interwined with various risk factors associated with the initiation and progression of atherosclerosis in CVD. A large body of evidence indicates a correlation between immunity and atherosclerosis. Retention of plasma lipoproteins in arterial subendothelial wall triggers the T helper type 1 (Th1) cells and monocyte-derived macrophages to form atherosclerotic plaques. In the present review, we will discuss the pathogenesis of CVD in relation to atherosclerosis with a particular focus on pro-atherogenic role of immune cells. Recent findings have also suggested anti-atherogenic roles of different B cell subsets. Therapeutic approaches to target atherosclerosis risk factors have reduced the mortality, but a need exists for the novel therapies to treat arterial vascular inflammation. These insights into the immune pathogenesis of atherosclerosis can lead to new targeted therapeutics to abate cardiovascular mortality and morbidity.

Macrophage ontogeny and functional diversity in cardiometabolic diseases

Macrophages are the dominant immune cell types in the adipose tissue, the liver or the aortic wall and they were originally believed to mainly derived from monocytes to fuel tissue inflammation in cardiometabolic diseases. However, over the last decade the identification of tissue resident macrophages (trMacs) from embryonic origin in these metabolic tissues has provided a breakthrough in the field forcing to better comprehend macrophage diversity during pathological states. Infiltrated monocyte-derived macrophages (moMacs), similar to trMacs, adapt to the local metabolic environment that eventually shapes their functions. In this review, we will summarize the emerging versatility of macrophages in cardiometabolic diseases with a focus in the control of adipose tissue, liver and large vessels homeostasis.

Long non-coding RNA GAS5 knockdown facilitates proliferation and impedes apoptosis by regulating miR-128-3p/FBLN2 axis in ox-LDL-induced THP-1 cells

BACKGROUND

Long non-coding RNAs (lncRNAs) are found to involve in modulating the development of atherosclerosis (AS). But the molecular mechanism of lncRNA growth-arrest specific transcript 5 (GAS5) in AS is not fully understood.

METHODS

QRT-PCR was performed to measure the abundances of GAS5, miR-128-3p and fibulin 2 (FBLN2). Oxidized low-density lipoprotein (ox-LDL)-treated THP-1 cells were employed as cell models of AS. The cell proliferation and apoptosis were analyzed using CCK-8 and Flow cytometry assays, respectively. Levels of all protein were examined by western blot. The interaction among GAS5, miR-128-3p and FBLN2 was confirmed via dual-luciferase reporter and RNA immunoprecipitation (RIP) assays.

RESULTS

GAS5 was elevated and miR-128-3p was decreased in the serum of patients with AS and ox-LDL-stimulated THP-1 cells. Ox-LDL stimulation inhibited proliferation and induced apoptosis of THP-1 cells. Meanwhile, GAS5 directly targeted miR-128-3p and inversely modulated its expression. Importantly, GAS5 depletion facilitated cell proliferation and impaired apoptosis in ox-LDL-induced THP-1 cells. Additionally, GAS5 augmented FBLN2 expression through sponging miR-128-3p, and miR-128-3p facilitated proliferation and retarded apoptosis of ox-LDL-induced THP-1 cells by targeting FBLN2.

CONCLUSION

GAS5 knockdown promoted the growth of ox-LDL-induced THP-1 cells through down-modulating FBLN2 and increasing miR-128-3p, suggesting the potential value of GAS5 for treatment of AS.

Foam Cells as Therapeutic Targets in Atherosclerosis with a Focus on the Regulatory Roles of Non-Coding RNAs

Atherosclerosis is a major cause of human cardiovascular disease, which is the leading cause of mortality around the world. Various physiological and pathological processes are involved, including chronic inflammation, dysregulation of lipid metabolism, development of an environment characterized by oxidative stress and improper immune responses. Accordingly, the expansion of novel targets for the treatment of atherosclerosis is necessary. In this study, we focus on the role of foam cells in the development of atherosclerosis. The specific therapeutic goals associated with each stage in the formation of foam cells and the development of atherosclerosis will be considered. Processing and metabolism of cholesterol in the macrophage is one of the main steps in foam cell formation. Cholesterol processing involves lipid uptake, cholesterol esterification and cholesterol efflux, which ultimately leads to cholesterol equilibrium in the macrophage. Recently, many preclinical studies have appeared concerning the role of non-encoding RNAs in the formation of atherosclerotic lesions. Non-encoding RNAs, especially microRNAs, are considered regulators of lipid metabolism by affecting the expression of genes involved in the uptake (e.g., CD36 and LOX1) esterification (ACAT1) and efflux (ABCA1, ABCG1) of cholesterol. They are also able to regulate inflammatory pathways, produce cytokines and mediate foam cell apoptosis. We have reviewed important preclinical evidence of their therapeutic targeting in atherosclerosis, with a special focus on foam cell formation.

M2 Monocyte Polarization in Dialyzed Patients Is Associated with Increased Levels of M-CSF and Myeloperoxidase-Associated Oxidative Stress: Preliminary Results

Cardiovascular diseases represent a major issue in terms of morbidity and mortality for dialysis patients. This morbidity is due to the accelerated atherosclerosis observed in these patients. Atherosclerosis is a chronic inflammatory disease characterized by key players such as monocytes, macrophages, or oxidized LDLs. Monocytes-macrophages are classified into subsets of polarized cells, with M1 and M2 macrophages considered, respectively, as pro- and anti-inflammatory. (1) Methods: The monocyte subsets and phenotypes were analyzed by flow cytometry. These data were completed by the quantification of plasma M-CSF, IL-8, CRP, Mox-LDLs, Apo-B, Apo-AI, chloro-tyrosine, and homocitrulline concentrations. The statistical differences and associations between two continuous variables were assessed using the Mann-Whitney U test and Spearman's correlation coefficient, respectively. (2) Results: Hemodialyzed patients showed a significant increase in their concentrations of CRP, M-CSF, and IL-8 (inflammation biomarkers), as well as chloro-tyrosine and homocitrulline (myeloperoxidase-associated oxidative stress biomarkers). Moreover, we observed a higher percentage of M2 monocytes in the plasma of hemodialysis patients as compared to the controls. (3) Conclusions: Our data suggest that oxidative stress and an inflammatory environment, which is amplified in hemodialysis patients, seems to favor an increase in the concentration of circulating M-CSF, therefore leading to an increase in M2 polarization among circulating monocytes.

Local M-CSF (Macrophage Colony-Stimulating Factor) Expression Regulates Macrophage Proliferation and Apoptosis in Atherosclerosis

OBJECTIVE

Previous studies have shown that deficiency of M-CSF (macrophage colony-stimulating factor; or CSF1 [colony stimulating factor 1]) dramatically reduces atherosclerosis in hyperlipidemic mice. We characterize the underlying mechanism and investigate the relevant sources of CSF1 in lesions. Approach and Results: We quantitatively assessed the effects of CSF1 deficiency on macrophage proliferation and apoptosis in atherosclerotic lesions. Staining of aortic lesions with markers of proliferation, Ki-67 and bromodeoxyuridine, revealed around 40% reduction in CSF1 heterozygous (Csf1+/-) as compared with WT (wild type; Csf1+/+) mice. Similarly, staining with a marker of apoptosis, activated caspase-3, revealed a 3-fold increase in apoptotic cells in Csf1+/- mice. Next, we determined the cellular sources of CSF1 contributing to lesion development. Cell-specific deletions of Csf1 in smooth muscle cells using SM22α-Cre (smooth muscle protein 22-alpha-Cre) reduced lesions by about 40%, and in endothelial cells, deletions with Cdh5-Cre (VE-cadherin-Cre) reduced lesions by about 30%. Macrophage-specific deletion with LysM-Cre (lysozyme M-Cre), on the other hand, did not significantly reduce lesions size. Transplantation of Csf1 null (Csf1-/-) mice bone marrow into Csf1+/+ mice reduced lesions by about 35%, suggesting that CSF1 from hematopoietic cells other than macrophages contributes to atherosclerosis. None of the cell-specific knockouts affected circulating CSF1 levels, and only the smooth muscle cell deletions had any effect on the percentage monocytes in the circulation. Also, Csf1+/- mice did not exhibit significant differences in Ly6Chigh/Ly6Clow monocytes as compared with Csf1+/+.

CONCLUSIONS

CSF1 contributes to both macrophage proliferation and survival in lesions. Local CSF1 production by smooth muscle cell and endothelial cell rather than circulating CSF1 is the primary driver of macrophage expansion in atherosclerosis.

Monocyte Recruitment, Specification, and Function in Atherosclerosis

Atherosclerotic lesions progress through the continued recruitment of circulating blood monocytes that differentiate into macrophages within plaque. Lesion-associated macrophages are the primary immune cells present in plaque, where they take up cholesterol and store lipids in the form of small droplets resulting in a unique morphology termed foam cell. Recent scientific advances have used single-cell gene expression profiling, live-cell imaging, and fate mapping approaches to describe macrophage and monocyte contributions to pro- or anti-inflammatory mechanisms, in addition to functions of motility and proliferation within lesions. Yet, many questions regarding tissue-specific regulation of monocyte-to-macrophage differentiation and the contribution of recruited monocytes at stages of atherosclerotic disease progression remain unknown. In this review, we highlight recent advances regarding the role of monocyte and macrophage dynamics in atherosclerotic disease and identify gaps in knowledge that we hope will allow for advancing therapeutic treatment or prevention strategies for cardiovascular disease.

Interactive effects of interferon-gamma functional single nucleotid polymorphism (+874 T/A) with cardiovascular risk factors in coronary heart disease and early myocardial infarction risk

Atherosclerosis is an inflammatory disease characterized by extensive lipid accumulation in the artery wall. Throughout the atherosclerotic process, interferon-gamma (IFN-γ), which is an important pro-inflammatory cytokine, plays a central role in atherosclerotic plaque instability and the occurrence of myocardial infarction (MI). In this study, we aimed to investigate the relationship between IFN-γ +874 T/A (rs2430561) polymorphism and coronary heart disease (CHD) as well as its effects on MI and CHD. Three hundred and ninety patients with CHD (229 with MI, 161 without MI) and 233 healthy controls were screened by the amplification refractory mutation system (ARMS) PCR method for IFN-γ +874 T/A polymorphism. For MI risk, early adult age was important risk factors and the risk was increased with IFN-γ +874 T/A polymorphism. IFN-γ T allele was significantly increased in the CHD patients with age≤45 (p = 0.048) and patients with history of MI (p = 0.007). As IFN-γ is an inflammatory cytokine with an emerging role in the atherosclerotic process, it was suggested that inhibition of IFN-γ activity could be a therapeutic strategy to stabilize human atherosclerotic plaque. Our findings support the association between MI risk and IFN-γ +874 T/A polymorphism in the Turkish population, particularly by increasing the level of IFN-γ in young patients, thereby causing rupture of vulnerable plaques in atherosclerotic lesions. Identification of the IFN-γ +874 T/A gene variants as risk factors for early CHD and MI development may be a practical biomarker to guide the MI risk process and determine the ideal therapeutic approach.

Inflammatory cytokines in the pathogenesis of cardiovascular disease and cancer

Inflammatory cytokines are highly inducible small glycoproteins or regulatory proteins of low molecular weight secreted by different cell types. They regulate intercellular communication and mediate a number of physiological functions in the human immune system. Numerous prospective studies report that inflammatory cytokines strongly predict coronary artery disease, myocardial infarction, heart failure and other adverse cardiac events. Inflammatory cascade is believed to be a causative factor in the development of atherosclerotic process. Several aspects of atherogenesis are accelerated by cytokines. This article provides an overall overview of current understanding of cytokines in various cardiovascular events. Besides, inflammatory cytokines trigger cellular events that can induce malignancy and carcinogenesis. Elevated expression of several cytokines such as interleukin-1, interleukin-6, interleukin-10, tumor necrosis factor-α, macrophage migration inhibitory factor and transforming growth factor-β are involved in tumor initiation and progression. Thus, they exert a pivotal role in cancer pathogenesis. This review highlights the role of several cytokines in various events of tumorigenesis. Actually, this article summarizes the contributions of cytokines in the pathogenesis of cardiovascular disease and cancer.

Pulse wave velocity, augmentation index, and carotid intima-media thickness are each associated with different inflammatory protein signatures in young healthy adults: The lifestyle, biomarkers and atherosclerosis study

BACKGROUND AND AIMS

We aimed to identify plasma protein biomarkers related to inflammation that correlated with physiological measurements of vascular function and structure in healthy individuals.

METHODS

We used the OLINK proteomics panel, which measures 92 inflammatory proteins, in 834 young, healthy non-smokers (ages 18-26). Principal component analysis (PCA) was employed to identify patterns of proteins. The following measurements were used: pulse-wave velocity (PWV), carotid intima-media thickness (cIMT) and augmentation index (AIX). Established cardiovascular risk factors were included in multivariable models.

RESULTS

PCA showed four principal components (PC 1, PC 2, PC 3, PC 4). PC 3, comprising proteins related to hemostasis, was significantly and inversely correlated with PWV. Among the proteins with the highest factor loadings on PC 3, uPA was negatively correlated with PWV in multivariable regression models. AIX was significantly correlated with PC 2, comprising inflammatory cytokines. Among the proteins with the highest factor loadings on PC 2, interleukin-6 was significantly correlated with AIX in the multivariable model. cIMT was significantly correlated with PC 4, comprising proteins related to chemotaxis. Among the proteins with the highest factor loadings on PC 4, fractalkine was significantly correlated with cIMT in the multivariable model.

CONCLUSIONS

In young, healthy individuals, OLINK inflammatory proteins correlated with measures of vascular status. Each of the three measures PWV, AIX, and cIMT, which target different parts of the vasculature, correlated with its own specific protein signature, indicating that different subsets of inflammatory mediators affect different parts of the vasculature and are detectable already in young healthy adults.

Distinct subsets of T cells and macrophages impact venous remodeling during arteriovenous fistula maturation

Patients with end-stage renal failure depend on hemodialysis indefinitely without renal transplantation, requiring a long-term patent vascular access. While the arteriovenous fistula (AVF) remains the preferred vascular access for hemodialysis because of its longer patency and fewer complications compared with other vascular accesses, the primary patency of AVF is only 50-60%, presenting a clinical need for improvement. AVF mature by developing a thickened vascular wall and increased diameter to adapt to arterial blood pressure and flow volume. Inflammation plays a critical role during vascular remodeling and fistula maturation; increased shear stress triggers infiltration of T-cells and macrophages that initiate inflammation, with involvement of several different subsets of T-cells and macrophages. We review the literature describing distinct roles of the various subsets of T-cells and macrophages during vascular remodeling. Immunosuppression with sirolimus or prednisolone reduces neointimal hyperplasia during AVF maturation, suggesting novel approaches to enhance vascular remodeling. However, M2 macrophages and CD4+ T-cells play essential roles during AVF maturation, suggesting that total immunosuppression may suppress adaptive vascular remodeling. Therefore it is likely that regulation of inflammation during fistula maturation will require a balanced approach to coordinate the various inflammatory cell subsets. Advances in immunosuppressive drug development and delivery systems may allow for more targeted regulation of inflammation to improve vascular remodeling and enhance AVF maturation.

Hospitalization With Major Infection and Incidence of End-Stage Renal Disease: The Atherosclerosis Risk in Communities (ARIC) Study

OBJECTIVE

To evaluate whether the incidence of infectious diseases increases the long-term risk for incident end-stage renal disease (ESRD) in the general population.

PATIENTS AND METHODS

In 10,290 participants of the Atherosclerosis Risk in Communities Study who attended visit 4 (1996-1998), we evaluated the association of incident hospitalization with major infections (pneumonia, urinary tract infection, bloodstream infection, and cellulitis and osteomyelitis) with subsequent risk for ESRD through September 30, 2015. Hospitalization with major infection was entered into multivariable Cox models as a time-varying exposure to estimate the hazard ratios.

RESULTS

Mean age was 63 years, and of 10,290 individuals, 56% (n=5781) were women, 22% (n=2252) were black, and 7% (n=666) had an estimated glomerular filtration rate less than 60 mL/min/1.73 m2. During a median follow-up of 17.4 years, there were 2642 incident hospitalizations with major infection and 281 cases of ESRD (132 cases after hospitalization with major infection). The risk for ESRD was higher following major infection compared with while free of major infection (crude incidence rate, 10.9 vs 1.0 per 1000 person-years). In multivariable time-varying Cox analysis, hospitalization with major infection was associated with a 3.3-fold increased risk for ESRD (hazard ratio, 3.34; 95% CI, 2.56-4.37). The association was similar across pneumonia, urinary tract infection, bloodstream infection, and cellulitis and osteomyelitis, and remained significant across subgroups of age, sex, race, diabetes, history of cardiovascular disease, and chronic kidney disease.

CONCLUSION

Hospitalization with major infection was independently and robustly associated with subsequent risk for ESRD. Whether preventive approaches against infection have beneficial effects on kidney outcomes may deserve future investigations.

Sex-Specific Effects of the Nlrp3 Inflammasome on Atherogenesis in LDL Receptor-Deficient Mice

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In this study we observed sex-specific effects of the NLRP3 inflammasome on atherogenesis in LDLR-deficient mice, with NLRP3 inflammasome playing a more prominent role in atherosclerosis in female mice than in males.

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Sex hormones may be involved in NLRP3 inflammasome–mediated atherogenesis and may underlie differential responses to anti-NLRP3 therapy between males and females.

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Testosterone may play an inhibitory role by blocking NLRP3 inflammasome and inflammation in atherogenesis, whereas female sex hormones may promote NLRP3 inflammasome–mediated atherosclerosis.

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The results of the present study may help design future clinical trials, with the objective to personalize cardiovascular care for men and women.

In the Ldlr^-/- mouse model of atherosclerosis, female Nlrp3^-/- bone marrow chimera and Nlrp3^-/- mice developed significantly smaller lesions in the aortic sinus and decreased lipid content in aorta en face, but a similar protection was not observed in males. Ovariectomized female mice lost protection from atherosclerosis in the setting of NLRP3 deficiency, whereas atherosclerosis showed a greater dependency on NLRP3 in castrated males. Thus, castration increased the dependency of atherosclerosis on the NLRP3 inflammasome, suggesting that testosterone may block inflammation in atherogenesis. Conversely, ovariectomy reduced the dependency on NLRP3 inflammasome components for atherogenesis, suggesting that estrogen may promote inflammasome-mediated atherosclerosis.

Hematopoiesis is regulated by cholesterol efflux pathways and lipid rafts: connections with cardiovascular diseases

Lipid rafts are highly ordered regions of the plasma membrane that are enriched in cholesterol and sphingolipids and play important roles in many cells. In hematopoietic stem and progenitor cells (HSPCs), lipid rafts house receptors critical for normal hematopoiesis. Lipid rafts also can bind and sequester kinases that induce negative feedback pathways to limit proliferative cytokine receptor cycling back to the cell membrane. Modulation of lipid rafts occurs through an array of mechanisms, with optimal cholesterol efflux one of the major regulators. As such, cholesterol homeostasis also regulates hematopoiesis. Increased lipid raft content, which occurs in response to changes in cholesterol efflux in the membrane, can result in prolonged receptor occupancy in the cell membrane and enhanced signaling. In addition, certain diseases, like diabetes, may contribute to lipid raft formation and affect cholesterol retention in rafts. In this review, we explore the role of lipid raft-related mechanisms in hematopoiesis and CVD (specifically, atherosclerosis) and discuss how defective cholesterol efflux pathways in HSPCs contribute to expansion of lipid rafts, thereby promoting myelopoiesis and thrombopoiesis. We also discuss the utility of cholesterol acceptors in contributing to lipid raft regulation and disruption, and highlight the potential to manipulate these pathways for therapeutic gain in CVD as well as other disorders with aberrant hematopoiesis.jlr;61/5/667/F1F1f1.

Engineering Immunomodulatory Biomaterials for Regenerating the Infarcted Myocardium

Coronary artery disease is a severe ischemic condition characterized by the reduction of blood flow in the arteries of the heart that results in the dysfunction and death of cardiac tissue. Despite research over several decades on how to reduce long-term complications and promote angiogenesis in the infarct, the medical field has yet to define effective treatments for inducing revascularization in the ischemic tissue. With this work, we have developed functional biomaterials for the controlled release of immunomodulatory cytokines to direct immune cell fate for controlling wound healing in the ischemic myocardium. The reparative effects of colony-stimulating factor (CSF-1), and anti-inflammatory interleukins 4/6/13 (IL4/6/13) have been evaluated in vitro and in a predictive in vivo model of ischemia (the skin flap model) to optimize a new immunomodulatory biomaterial that we use for treating infarcted rat hearts. Alginate hydrogels have been produced by internal gelation with calcium carbonate (CaCO₃) as carriers for the immunomodulatory cues, and their stability, degradation, rheological properties and release kinetics have been evaluated in vitro. CD14 positive human peripheral blood monocytes treated with the immunomodulatory biomaterials show polarization into pro-healing macrophage phenotypes. Unloaded and CSF-1/IL4 loaded alginate gel formulations have been implanted in skin flap ischemic wounds to test the safety and efficacy of the delivery system in vivo. Faster wound healing is observed with the new therapeutic treatment, compared to the wounds treated with the unloaded controls at day 14. The optimized therapy has been evaluated in a rat model of myocardial infarct (ischemia/reperfusion). Macrophage polarization toward healing phenotypes and global cardiac function measured with echocardiography and immunohistochemistry at 4 and 15 days demonstrate the therapeutic potential of the proposed immunomodulatory treatment in a clinically relevant infarct model.

Molecular regulation of TLR signaling in health and disease: mechano-regulation of macrophages and TLR signaling

Immune cells encounter tissues with vastly different biochemical and physical characteristics. Much of the research emphasis has focused on the role of cytokines and chemokines in regulating immune cell function, but the role of the physical microenvironment has received considerably less attention. The tissue mechanics, or stiffness, of healthy tissues varies dramatically from soft adipose tissue and brain to stiff cartilage and bone. Tissue mechanics also change due to fibrosis and with diseases such as atherosclerosis or cancer. The process by which cells sense and respond to their physical microenvironment is called mechanotransduction. Here we review mechanotransduction in immunologically important diseases and how physical characteristics of tissues regulate immune cell function, with a specific emphasis on mechanoregulation of macrophages and TLR signaling.

Loss of 2 Akt (Protein Kinase B) Isoforms in Hematopoietic Cells Diminished Monocyte and Macrophage Survival and Reduces Atherosclerosis in Ldl Receptor-Null Mice

Objective- Macrophages express 3 Akt (protein kinase B) isoforms, Akt1, Akt2, and Akt3, which display isoform-specific functions but may be redundant in terms of Akt survival signaling. We hypothesize that loss of 2 Akt isoforms in macrophages will suppress their ability to survive and modulate the development of atherosclerosis. Approach and Results- To test this hypothesis, we reconstituted male Ldlr^-/- mice with double Akt2/Akt3 knockout hematopoietic cells expressing only the Akt1 isoform (Akt1^only). There were no differences in body weight and plasma lipid levels between the groups after 8 weeks of the Western diet; however, Akt1^only→ Ldlr^-/- mice developed smaller (57.6% reduction) atherosclerotic lesions with more apoptotic macrophages than control mice transplanted with WT (wild type) cells. Next, male and female Ldlr^-/- mice were reconstituted with double Akt1/Akt2 knockout hematopoietic cells expressing the Akt3 isoform (Akt3^only). Female and male Akt3^only→ Ldlr^-/- recipients had significantly smaller (61% and 41%, respectively) lesions than the control WT→ Ldlr^-/- mice. Loss of 2 Akt isoforms in hematopoietic cells resulted in markedly diminished levels of white blood cells, B cells, and monocytes and compromised viability of monocytes and peritoneal macrophages compared with WT cells. In response to lipopolysaccharides, macrophages with a single Akt isoform expressed low levels of inflammatory cytokines; however, Akt1^only macrophages were distinct in expressing high levels of antiapoptotic Il10 compared with WT and Akt3^only cells. Conclusions- Loss of 2 Akt isoforms in hematopoietic cells, preserving only a single Akt1 or Akt3 isoform, markedly compromises monocyte and macrophage viability and diminishes early atherosclerosis in Ldlr^-/- mice.

Who's in charge here? Macrophage colony stimulating factor and granulocyte macrophage colony stimulating factor: Competing factors in macrophage polarization

Macrophages make up a crucial aspect of the immune system, carrying out a variety of functions ranging from clearing cellular debris to their well-recognized roles as innate immune cells. These cells exist along a spectrum of phenotypes but can be generally divided into proinflammatory (M1) and anti-inflammatory (M2) groups, representing different states of polarization. Due to their diverse functions, macrophages are implicated in a variety of diseases such as atherosclerosis, lupus nephritis, or infection with HIV. Throughout their lifetime, macrophages can be influenced by a wide variety of signals that influence their polarization states, which can affect their function and influence their effects on disease progression. This review seeks to provide a summary of how GM-CSF and M-CSF influence macrophage activity during disease, and provide examples of in vitro research that indicate competition between the two cytokines in governing macrophage polarization. Gaining a greater understanding of the relationship between GM-CSF and M-CSF, along with how these cytokines fit into the larger context of diseases, will inform their use as treatments or targets for treatment in various diseases.

Comprehensive analysis of circRNA expression pattern and circRNA-miRNA-mRNA network in the pathogenesis of atherosclerosis in rabbits

Atherosclerosis is a chronic and multifactorial inflammatory disease and is closely associated with cardiovascular and cerebrovascular diseases. circRNAs can act as competing endogenous RNAs to mRNAs and function in various diseases. However, there is little known about the function of circRNAs in atherosclerosis. In this study, three rabbits in the case group were fed a high-fat diet to induce atherosclerosis and another three rabbits were fed a normal diet. To explore the biological functions of circRNAs in atherosclerosis, we analyzed the circRNA, miRNA and mRNA expression profiles using RNA-seq. Many miRNAs, mRNAs and circRNAs were identified as significantly changed in atherosclerosis. We next predicted miRNA-target interactions with the miRanda tool and constructed a differentially expressed circRNA-miRNA-mRNA triple network. A gene ontology enrichment analysis showed that genes in the network were involved in cell adhesion, cell activation and the immune response. Furthermore, we generated a dysregulated circRNA-related ceRNAs network and found seven circRNAs (ocu-cirR-novel-18038, -18298, -15993, -17934, -17879, -18036 and -14389) were related to atherosclerosis. We found these circRNAs also functioned in cell adhesion, cell activation and the immune response. These results show that the crosstalk between circRNAs and their competing mRNAs might play crucial roles in the development of atherosclerosis.

Screening of House Dust from Chinese Homes for Chemicals with Liver X Receptors Binding Activities and Characterization of Atherosclerotic Activity Using an in Vitro Macrophage Cell Line and ApoE-/- Mice

BACKGROUND

Atherosclerotic cardiovascular disease has become the leading cause of death worldwide, and environmental pollutants are increasingly recognized as risk factors for atherosclerosis. Liver X receptors (LXRs) play a central role in atherosclerosis; however, LXR activity of organic pollutants and associated potential risk of atherosclerosis have not yet been characterized.

OBJECTIVES

This study aimed to explore whether LXR-antagonistic chemicals are present in indoor house dust and, if so, to characterize this activity in relation to changes in macrophages in vitro and cardiovascular disease indicators in vivo in an atherosclerosis ApoE-/- mouse model.

METHODS

We used a His-LXRα-pull-down assay and a nontarget high-resolution mass spectrometry method to screen house dust collected from Chinese homes for LXRα- and LXRβ-antagonist activity. A chemical identified in this manner was assessed for its ability to induce cholesterol efflux and foam cell formation in RAW264.7 macrophages, to down-regulate the expression of two LXR-dependent genes, ABCA1 and ABCG1, and finally to induce atherosclerotic lesions in vivo using an ApoE-/- mouse model.

RESULTS

We identified the flame retardants triphenyl phosphate (TPHP) and 2-ethylhexyl diphenyl phosphate (EHDPP) in house dust samples and demonstrated their ability to antagonize LXRs. The potency of TPHP was similar to that of the LXR-antagonist SR9238. TPHP could also inhibit cholesterol efflux and promote foam cell formation in RAW264.7 macrophages and mouse peritoneal macrophages and significantly promoted atherosclerotic lesion formation in the ApoE-/- mouse model.

CONCLUSIONS

We found LXR-antagonist chemicals in environmental samples of indoor dust from Chinese homes. One of the chemicals, TPHP, was able to promote the development of atherosclerotic lesions in the ApoE-/- mouse model. These results highlight the need to assess the LXR-antagonist activities of pollutants in future environmental management programs. https://doi.org/10.1289/EHP5039.

Immunobiology of Atherosclerosis: A Complex Net of Interactions

Cardiovascular disease is the leading cause of mortality worldwide, and atherosclerosis the principal factor underlying cardiovascular events. Atherosclerosis is a chronic inflammatory disease characterized by endothelial dysfunction, intimal lipid deposition, smooth muscle cell proliferation, cell apoptosis and necrosis, and local and systemic inflammation, involving key contributions to from innate and adaptive immunity. The balance between proatherogenic inflammatory and atheroprotective anti-inflammatory responses is modulated by a complex network of interactions among vascular components and immune cells, including monocytes, macrophages, dendritic cells, and T, B, and foam cells; these interactions modulate the further progression and stability of the atherosclerotic lesion. In this review, we take a global perspective on existing knowledge about the pathogenesis of immune responses in the atherosclerotic microenvironment and the interplay between the major innate and adaptive immune factors in atherosclerosis. Studies such as this are the basis for the development of new therapies against atherosclerosis.