Inducible interleukin-1 gene expression in human vascular smooth muscle cells

The Role of Pro-Inflammatory Cytokines in the Pathogenesis of Cardiovascular Disease

With cardiovascular disease (CVD) being a primary source of global morbidity and mortality, it is crucial that we understand the molecular pathophysiological mechanisms at play. Recently, numerous pro-inflammatory cytokines have been linked to several different CVDs, which are now often considered an adversely pro-inflammatory state. These cytokines most notably include interleukin-6 (IL-6),tumor necrosis factor (TNF)α, and the interleukin-1 (IL-1) family, amongst others. Not only does inflammation have intricate and complex interactions with pathophysiological processes such as oxidative stress and calcium mishandling, but it also plays a role in the balance between tissue repair and destruction. In this regard, pre-clinical and clinical evidence has clearly demonstrated the involvement and dynamic nature of pro-inflammatory cytokines in many heart conditions; however, the clinical utility of the findings so far remains unclear. Whether these cytokines can serve as markers or risk predictors of disease states or act as potential therapeutic targets, further extensive research is needed to fully understand the complex network of interactions that these molecules encompass in the context of heart disease. This review will highlight the significant advances in our understanding of the contributions of pro-inflammatory cytokines in CVDs, including ischemic heart disease (atherosclerosis, thrombosis, acute myocardial infarction, and ischemia-reperfusion injury), cardiac remodeling (hypertension, cardiac hypertrophy, cardiac fibrosis, cardiac apoptosis, and heart failure), different cardiomyopathies as well as ventricular arrhythmias and atrial fibrillation. In addition, this article is focused on discussing the shortcomings in both pathological and therapeutic aspects of pro-inflammatory cytokines in CVD that still need to be addressed by future studies.

Novel Anti-Inflammatory Therapies in Coronary Artery Disease and Acute Coronary Syndromes

Evidence suggests that inflammation plays an important role in atherosclerosis and the consequent clinical presentation, including stable coronary artery disease (CAD) and acute coronary syndromes (ACS). The most essential elements are cytokines, proteins with hormone-like properties that are produced by the immune cells, endothelial cells, platelets, fibroblasts, and some stromal cells. Interleukins (IL-1β and IL-6), chemokines, interferon-γ (IFN-γ), and tumor necrosis factor-alpha (TNF-α) are the cytokines commonly associated with endothelial dysfunction, vascular inflammation, and atherosclerosis. These molecules can be targeted by commonly used therapeutic substances or selective molecules that exert targeted anti-inflammatory actions. The most significant anti-inflammatory therapies are aspirin, statins, colchicine, IL-1β inhibitors, and IL-6 inhibitors, along with novel therapies such as TNF-α inhibitors and IL-1 receptor antagonists. Aspirin and statins are well-established therapies for atherosclerosis and CAD and their pleiotropic and anti-inflammatory actions contribute to their efficacy and favorable profile. Colchicine may also be considered in high-risk patients if recurrent ACS episodes occur when on optimal medical therapy according to the most recent guidelines. Recent randomized studies have also shown that therapies specifically targeting inflammatory interleukins and inflammation can reduce the risk for cardiovascular events, but these therapies are yet to be fully implemented in clinical practice. Preclinical research is also intense, targeting various inflammatory mediators that are believed to be implicated in CAD, namely repeated transfers of the soluble mutant of IFN-γ receptors, NLRP3 inflammasome inhibitors, IL-10 delivery by nanocarriers, chemokine modulatory treatments, and reacting oxygen species (ROS) targeting nanoparticles. Such approaches, although intriguing and promising, ought to be tested in clinical settings before safe conclusions can be drawn. Although the link between inflammation and atherosclerosis is significant, further studies are needed in order to elucidate this association and improve outcomes in patients with CAD.

The Impact of Cytokines in Coronary Atherosclerotic Plaque: Current Therapeutic Approaches

Coronary atherosclerosis is a chronic pathological process that involves inflammation together with endothelial dysfunction and lipoprotein dysregulation. Experimental studies during the past decades have established the role of inflammatory cytokines in coronary artery disease, namely interleukins (ILs), tumor necrosis factor (TNF)-α, interferon-γ, and chemokines. Moreover, their value as biomarkers in disease development and progression further enhance the validity of this interaction. Recently, cytokine-targeted treatment approaches have emerged as potential tools in the management of atherosclerotic disease. IL-1β, based on the results of the CANTOS trial, remains the most validated option in reducing the residual cardiovascular risk. Along the same line, colchicine was also proven efficacious in preventing major adverse cardiovascular events in large clinical trials of patients with acute and chronic coronary syndrome. Other commercially available agents targeting IL-6 (tocilizumab), TNF-α (etanercept, adalimumab, infliximab), or IL-1 receptor antagonist (anakinra) have mostly been assessed in the setting of other inflammatory diseases and further testing in atherosclerosis is required. In the future, potential targeting of the NLRP3 inflammasome, anti-inflammatory IL-10, or atherogenic chemokines could represent appealing options, provided that patient safety is proven to be of no concern.

Research progress on Th17 and T regulatory cells and their cytokines in regulating atherosclerosis

Background

Coronary heart disease due to atherosclerosis is the leading cause of death worldwide. Atherosclerosis is considered a chronic inflammatory state in the arterial wall that promotes disease progression and outcome, and immune cells play an important role in the inflammatory process.

Purpose

We review the mechanisms of CD4+ T subsets, i.e., helper T17 (Th17) cells and regulatory T cells (Tregs), in regulating atherosclerosis, focusing on the role of interleukin (IL)-17, IL-10, and other cytokines in this disease and the factors influencing the effects of these cytokines.

Results

IL-17 secreted by Th17 cells can promote atherosclerosis, but few studies have reported that IL-17 can also stabilize atherosclerotic plaques. Tregs play a protective role in atherosclerosis, and Th17/Treg imbalance also plays an important role in atherosclerosis.

Conclusion

The immune response is important in regulating atherosclerosis, and studying the mechanism of action of each immune cell on atherosclerosis presents directions for the treatment of atherosclerosis. Nevertheless, the current studies are insufficient for elucidating the mechanism of action, and further in-depth studies are needed to provide a theoretical basis for clinical drug development.

Animal Models of Atherosclerosis-Supportive Notes and Tricks of the Trade

Atherosclerotic cardiovascular disease is a major cause of death among humans. Animal models have shown that cholesterol and inflammation are causatively involved in the disease process. Apolipoprotein B-containing lipoproteins elicit immune reactions and instigate inflammation in the vessel wall. Still, a treatment that is specific to vascular inflammation is lacking, which motivates continued in vivo investigations of the immune-vascular interactions that drive the disease. In this review, we distill old notions with emerging concepts into a contemporary understanding of vascular disease models. Pros and cons of different models are listed and the complex integrative interplay between cholesterol homeostasis, immune activation, and adaptations of the vascular system is discussed. Key limitations with atherosclerosis models are highlighted, and we suggest improvements that could accelerate progress in the field. However, excessively rigid experimental guidelines or limiting usage to certain animal models can be counterproductive. Continued work in improved models, as well as the development of new models, should be of great value in research and could aid the development of cardiovascular disease diagnostics and therapeutics of the future.

Key Roles of Inflammation in Atherosclerosis: Mediators Involved in Orchestrating the Inflammatory Response and Its Resolution in the Disease Along with Therapeutic Avenues Targeting Inflammation

Inflammation is a critical driver of all stages of atherosclerosis, from lesion development to plaque rupture. Cytokines are mediators of the immune response and in atherosclerosis, the balance of anti- and pro-inflammatory cytokines is tipped in favor of the latter, resulting in persistent and unresolved inflammation. Although reducing plasma cholesterol levels mainly via the use of statins has positively impacted patient outcomes and reduced mortality rates, the presence of significant residual inflammation and cardiovascular risk posttherapy emphasizes the prevailing risk of primary and secondary events driven by inflammation independently of hyperlipidemia. Given the dominant role of inflammation in driving pathogenesis, alternative therapeutic avenues beyond targeting lowering of plasma lipids are required. This chapter will discuss the role of inflammation and pro-inflammatory cytokines in driving atherogenesis and disease progression, the therapeutic potential of targeting cytokines for atherosclerosis and promising avenues in this area.

Inflammation, Oxidative Stress, Senescence in Atherosclerosis: Thioredoxine-1 as an Emerging Therapeutic Target

Atherosclerosis is a leading cause of cardiovascular diseases (CVD) worldwide and intimately linked to aging. This pathology is characterized by chronic inflammation, oxidative stress, gradual accumulation of low-density lipoproteins (LDL) particles and fibrous elements in focal areas of large and medium arteries. These fibrofatty lesions in the artery wall become progressively unstable and thrombogenic leading to heart attack, stroke or other severe heart ischemic syndromes. Elevated blood levels of LDL are major triggering events for atherosclerosis. A cascade of molecular and cellular events results in the atherosclerotic plaque formation, evolution, and rupture. Moreover, the senescence of multiple cell types present in the vasculature were reported to contribute to atherosclerotic plaque progression and destabilization. Classical therapeutic interventions consist of lipid-lowering drugs, anti-inflammatory and life style dispositions. Moreover, targeting oxidative stress by developing innovative antioxidant agents or boosting antioxidant systems is also a well-established strategy. Accumulation of senescent cells (SC) is also another important feature of atherosclerosis and was detected in various models. Hence, targeting SCs appears as an emerging therapeutic option, since senolytic agents favorably disturb atherosclerotic plaques. In this review, we propose a survey of the impact of inflammation, oxidative stress, and senescence in atherosclerosis; and the emerging therapeutic options, including thioredoxin-based approaches such as anti-oxidant, anti-inflammatory, and anti-atherogenic strategy with promising potential of senomodulation.

Targeted delivery of protein arginine deiminase-4 inhibitors to limit arterial intimal NETosis and preserve endothelial integrity

AIMS

Recent evidence suggests that 'vulnerable plaques', which have received intense attention as underlying mechanism of acute coronary syndromes over the decades, actually rarely rupture and cause clinical events. Superficial plaque erosion has emerged as a growing cause of residual thrombotic complications of atherosclerosis in an era of increased preventive measures including lipid lowering, antihypertensive therapy, and smoking cessation. The mechanisms of plaque erosion remain poorly understood, and we currently lack validated effective diagnostics or therapeutics for superficial erosion. Eroded plaques have a rich extracellular matrix, an intact fibrous cap, sparse lipid, and few mononuclear cells, but do harbour neutrophil extracellular traps (NETs). We recently reported that NETs amplify and propagate the endothelial damage at the site of arterial lesions that recapitulate superficial erosion in mice. We showed that genetic loss of protein arginine deiminase (PAD)-4 function inhibited NETosis and preserved endothelial integrity. The current study used systemic administration of targeted nanoparticles to deliver an agent that limits NETs formation to probe mechanisms of and demonstrate a novel therapeutic approach to plaque erosion that limits endothelial damage.

METHODS AND RESULTS

We developed Collagen IV-targeted nanoparticles (Col IV NP) to deliver PAD4 inhibitors selectively to regions of endothelial cell sloughing and collagen IV-rich basement membrane exposure. We assessed the binding capability of the targeting ligand in vitro and evaluated Col IV NP targeting to areas of denuded endothelium in vivo in a mouse preparation that recapitulates features of superficial erosion. Delivery of the PAD4 inhibitor GSK484 reduced NET accumulation at sites of intimal injury and preserved endothelial continuity.

CONCLUSIONS

NPs directed to Col IV show selective uptake and delivery of their payload to experimentally eroded regions, illustrating their translational potential. Our results further support the role of PAD4 and NETs in superficial erosion.

Synergistic effects of electronegative-LDL- and palmitic-acid-triggered IL-1β production in macrophages via LOX-1- and voltage-gated-potassium-channel-dependent pathways

Electronegative LDL (LDL(-)) and free fatty acids (FFAs) are circulating risk factors for cardiovascular diseases (CVDs) and have been associated with inflammation. Interleukin-1 beta (IL-1β) represents a key cytokine in the development of CVD; however, the initial trigger of IL-1β in CVD remains to be explored. In this study, we investigated the combined effects of LDL(-) from the plasma of ST-segment elevation myocardial infarction (STEMI) patients or diet-induced hypercholesterolemic rabbits and bovine serum albumin bound palmitic acid (PA-BSA) on IL-1β production in macrophages. Macrophages derived from THP-1 cells or human peripheral blood mononuclear cells were independently treated with LDL(-), PA-BSA or cotreated with LDL(-) and PA-BSA. The results showed that nLDL and/or PA-BSA had no effect on IL-1β, and LDL(-) slightly increased IL-1β; however, cotreatment with LDL(-) and PA-BSA resulted in abundant secretion of IL-1β in macrophages. Rabbit LDL(-) induced the elevation of cellular pro-IL-1β and p-Iκ-Bα, but PA-BSA had no effect on pro-IL-1β or p-Iκ-Bα. In potassium-free buffer, LDL(-)-induced IL-1β reached a level similar to that induced by cotreatment with LDL(-) and PA-BSA. Moreover, LDL(-) and PA-BSA-induced IL-1β was inhibited in lectin-type oxidized LDL receptor-1 (LOX-1) knockdown cells and by blockers of voltage-gated potassium (Kv) channels. LDL(-) from diet-induced hypercholesterolemic rabbit had a similar effect as STEMI LDL(-) on IL-1β in macrophages. These results show that PA-BSA cooperates with LDL(-) to trigger IL-1β production in macrophages via a mechanism involving the LOX-1 and Kv channel pathways, which may play crucial roles in the regulation of inflammation in CVD.

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.

Inflammation in Atherosclerosis-No Longer a Theory

BACKGROUND

Inflammation links to atherosclerosis and its complications in various experimental investigations. Animal studies have implicated numerous inflammatory mediators in the initiation and complication of atherosclerosis. Numerous studies in humans have shown associations of biomarkers of inflammation with cardiovascular events provoked by atheromata. Inflammatory status, determined by the biomarker C-reactive protein, can guide the allocation of statin therapy to individuals without elevated low-density lipoprotein (LDL) concentrations to prevent first ever adverse cardiovascular events.

CONTENT

Until recently, no direct evidence has shown that an intervention that selectively limits inflammation can improve outcomes in patients with atherosclerosis. A recent study, based on decades of preclinical investigation, treated patients who had sustained a myocardial infarction and whose LDL was well-controlled on statin treatment with an antibody that neutralizes interleukin-1 beta. This trial, conducted in over 10 000 individuals, showed a reduction in major adverse cardiac events, establishing for the first time the clinical efficacy of an anti-inflammatory intervention in atherosclerosis. Two large subsequent studies have shown that colchicine treatment can also prevent recurrent events in patients recovering from an acute coronary syndrome or in the stable phase of coronary artery disease. These clinical trials have transformed inflammation in atherosclerosis from theory to practice.

SUMMARY

Much work remains to optimize further anti-inflammatory interventions, minimize unwanted actions, and refine patient selection. This long road from discovery in the laboratory to successful clinical trials represents a victory for medical science, and opens a new avenue to reducing the risk that remains despite current treatments for atherosclerosis.

The Role of Interleukin-18 in the Development and Progression of Atherosclerosis

Atherosclerosis (AS), as a chronic inflammatory disorder of the cardiovascular system, is one of the leading causes of ischemic heart disease, stroke and peripheral vascular disease. There is growing evidence on the role of innate and adaptive immunity in the pathogenesis of atherosclerosis. Interleukin-18 is one of the novel proinflammatory cytokines involved in atherogenesis, atherosclerotic plaque instability and plaque rupture. In this review, we overview the findings of preclinical and clinical studies about the role and mechanism of action of IL-18 in the pathogenesis of AS, which could offer novel prognostic and therapeutic approaches.

Targeting Inflammatory Pathways in Cardiovascular Disease: The Inflammasome, Interleukin-1, Interleukin-6 and Beyond

Recent clinical trials have now firmly established that inflammation participates causally in human atherosclerosis. These observations point the way toward novel treatments that add to established therapies to help stem the growing global epidemic of cardiovascular disease. Fortunately, we now have a number of actionable targets whose clinical exploration will help achieve the goal of optimizing beneficial effects while avoiding undue interference with host defenses or other unwanted actions. This review aims to furnish the foundation for this quest by critical evaluation of the current state of anti-inflammatory interventions within close reach of clinical application, with a primary focus on innate immunity. In particular, this paper highlights the pathway from the inflammasome, through interleukin (IL)-1 to IL-6 supported by a promising body of pre-clinical, clinical, and human genetic data. This paper also considers the use of biomarkers to guide allocation of anti-inflammatory therapies as a step toward realizing the promise of precision medicine. The validation of decades of experimental work and association studies in humans by recent clinical investigations provides a strong impetus for further efforts to target inflammation in atherosclerosis to address the considerable risk that remains despite current therapies.

Transforming growth factor-β1 inhibits interleukin-1β-induced expression of inflammatory genes and Cathepsin S activity in human vascular smooth muscle cells

OBJECTIVE AND DESIGN

This study investigated the opposite mechanisms by which IL-1β and TGF-β1 modulated the inflammatory and migratory phenotypes in cultured human intimal vascular smooth muscle cells vSMCs.

MATERIALS AND TREATMENT

Primary human vSMCs, obtained from twelve hypertensive patients who underwent carotid endarterectomy, were incubated for 24 hours with either 40 pM TGF-β1, or 1 nmol/L IL-1β, or their combination in presence or absence of anti-TGF-β neutralizing antibody.

METHODS

The expression levels of matrix metalloproteases and their inhibitors, and the elastolytic enzyme cathepsin S (CTSS) and its inhibitor cystatin C were evaluated with RT-PCR. CTSS activity was measured by fluorometry.

RESULTS

TGF-β1 reversed IL-1β-induced expression of iNOS, CXCL6, IL1R1, MMP12, and CTSS, while upregulated TIMP2 expression. Furthermore, anti-TGF-β neutralizing antibody abrogated TGF-β effects. Combination with IL-1β and TGF-β1 induced the expression of IL1α, IL1β, IL1R1, and CTSS, but suppressed CST3 expression. CTSS expression in the combination treatment was higher than that of cells treated with anti-TGF-β antibodies alone. Moreover, IL-1β-induced CTSS enzymatic activity was reduced when human vSMCs were co-treated with TGF-β, whereas this reduction was abrogated by anti-TGF-β neutralizing antibody.

CONCLUSION

TGF-β1 abrogated IL-1β-induced expression of inflammatory genes and elastolytic activity in cultured human vSMCs. Thus, TGF-β1 can play a crucial role in impairing IL-1β-induced vascular inflammation and damage involved in the etiology of cardiovascular diseases.

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.

Stage-dependent differential effects of interleukin-1 isoforms on experimental atherosclerosis

AIMS

Targeting interleukin-1 (IL-1) represents a novel therapeutic approach to atherosclerosis. CANTOS demonstrated the benefits of IL-1β neutralization in patients post-myocardial infarction with residual inflammatory risk. Yet, some mouse data have shown a prominent role of IL-1α rather than IL-1β in atherosclerosis, or even a deleterious effect of IL-1 on outward arterial remodelling in atherosclerosis-susceptible mice. To shed light on these disparate results, this study investigated the effect of neutralizing IL-1α or/and IL-1β isoforms starting either early in atherogenesis or later in ApoE-/- mice with established atheroma.

METHODS AND RESULTS

The neutralization of IL-1α or of both IL-1 isoforms impaired outward remodelling during early atherogenesis as assessed by micro-computed tomographic and histologic assessment. In contrast, the neutralization of IL-1β did not impair outward remodelling either during early atherogenesis or in mice with established lesions. Interleukin-1β inhibition promoted a slant of blood monocytes towards a less inflammatory state during atherogenesis, reduced the size of established atheromata, and increased plasma levels of IL-10 without limiting outward remodelling of brachiocephalic arteries.

CONCLUSION

This study established a pivotal role for IL-1α in the remodelling of arteries during early experimental atherogenesis, whereas IL-1β drives inflammation during atherogenesis and the evolution of advanced atheroma in mice.

Future of preventing and managing common chronic inflammatory diseases

Chronic inflammation has emerged as a key factor that contributes to some common chronic diseases and reduces lifespan. Studies have identified multiple types of chronic inflammation ranging from autoimmune disease, which attacks specific tissues, to autoinflammatory diseases, which cause low-grade systemic inflammation and contribute to several common chronic diseases. This article highlights new perspectives on the role of chronic inflammation in cardiovascular disease (CVD). Such information is being leveraged to develop new treatment strategies for CVD and may inform how periodontal disease influences CVD.

The differential statin effect on cytokine production of monocytes or macrophages is mediated by differential geranylgeranylation-dependent Rac1 activation

Monocytes and macrophages contribute to pathogenesis of various inflammatory diseases, including auto-inflammatory diseases, cancer, sepsis, or atherosclerosis. They do so by production of cytokines, the central regulators of inflammation. Isoprenylation of small G-proteins is involved in regulation of production of some cytokines. Statins possibly affect isoprenylation-dependent cytokine production of monocytes and macrophages differentially. Thus, we compared statin-dependent cytokine production of lipopolysaccharide (LPS)-stimulated freshly isolated human monocytes and macrophages derived from monocytes by overnight differentiation. Stimulated monocytes readily produced tumor necrosis factor-α, interleukin-6, and interleukin-1β. Statins did not alter cytokine production of LPS-stimulated monocytes. In contrast, monocyte-derived macrophages prepared in the absence of statin lost the capacity to produce cytokines, whereas macrophages prepared in the presence of statin still produced cytokines. The cells expressed indistinguishable nuclear factor-kB activity, suggesting involvement of separate, statin-dependent regulation pathways. The presence of statin was necessary during the differentiation phase of the macrophages, indicating that retainment-of-function rather than costimulation was involved. Reconstitution with mevalonic acid, farnesyl pyrophosphate, or geranylgeranyl pyrophosphate blocked the retainment effect, whereas reconstitution of cholesterol synthesis by squalene did not. Inhibition of geranylgeranylation by GGTI-298, but not inhibition of farnesylation or cholesterol synthesis, mimicked the retainment effect of the statin. Inhibition of Rac1 activation by the Rac1/TIAM1-inhibitor NSC23766 or by Rac1-siRNA (small interfering RNA) blocked the retainment effect. Consistent with this finding, macrophages differentiated in the presence of statin expressed enhanced Rac1-GTP-levels. In line with the above hypothesis that monocytes and macrophages are differentially regulated by statins, the CD14/CD16-, merTK-, CX₃CR1-, or CD163-expression (M2-macrophage-related) correlated inversely to the cytokine production. Thus, monocytes and macrophages display differential Rac1-geranylgeranylation-dependent functional capacities, that is, statins sway monocytes and macrophages differentially.

NLRP3 Inflammasome and the IL-1 Pathway in Atherosclerosis

Inflammation is an important driver of atherosclerosis, the underlying pathology of cardiovascular diseases. Therefore, therapeutic targeting of inflammatory pathways is suggested to improve cardiovascular outcomes in patients with cardiovascular diseases. This concept was recently proven by CANTOS (Canakinumab Anti-Inflammatory Thrombosis Outcomes Study), which demonstrated the therapeutic potential of the monoclonal IL (interleukin)-1β-neutralizing antibody canakinumab. IL-1β and other IL-1 family cytokines are important vascular and systemic inflammatory mediators, which contribute to atherogenesis. The NLRP3 (NOD [nucleotide oligomerization domain]-, LRR [leucine-rich repeat]-, and PYD [pyrin domain]-containing protein 3) inflammasome, an innate immune signaling complex, is the key mediator of IL-1 family cytokine production in atherosclerosis. NLRP3 is activated by various endogenous danger signals abundantly present in atherosclerotic lesions, such as oxidized low-density lipoprotein and cholesterol crystals. Consequently, NLRP3 inflammasome activation contributes to the vascular inflammatory response driving atherosclerosis development and progression. Here, we review the mechanisms of NLRP3 inflammasome activation and proinflammatory IL-1 family cytokine production in the context of atherosclerosis and discuss treatment possibilities in light of the positive outcomes of the CANTOS trial.

Chlamydia and Lipids Engage a Common Signaling Pathway That Promotes Atherogenesis

BACKGROUND

Recent studies indicate that Toll-like receptor 4 (TLR4) and myeloid differentiation factor 88 (MyD88) signaling promote the development of high fat diet-induced atherosclerosis in hypercholesterolemic mice.

OBJECTIVES

The authors investigated the role of TLR4/MyD88 signaling in hematopoietic and stromal cells in the development and infection-mediated acceleration of atherosclerosis.

METHODS

The authors generated bone marrow chimeras between wild-type and Tlr4^-/- mice, as well as wild-type and Myd88^-/- mice. All mice were on the Apoe^-/- background and fed high fat diet. The authors infected the chimeric mice with C. pneumoniae (CP) and fed them high fat diet.

RESULTS

Aortic sinus plaques and lipid content were significantly reduced in Apoe^-/- mice that received Tlr4^-/-or Myd88^-/- bone marrow compared with control animals despite similar cholesterol levels. Similarly, Tlr4 or Myd88 deficiency in stromal cells also led to a reduction in the lesion area and lipid in aortic sinus plaques. MyD88 expression only in CD11c+ dendritic cells (myeloid cells) in cells was sufficient in otherwise MyD88-deficient mice to induce CP infection-mediated acceleration of atherosclerosis, underlining the key role of MyD88 in CD11c+ dendritic cells (myeloid cells). Whereas CP infection markedly accelerated atherosclerosis in TLR4- or MyD88-positive chimeras, CP infection had a minimal effect on atherosclerosis in TLR4- or MyD88-deficient mice (either in the hematopoietic or stromal cell compartments).

CONCLUSIONS

The authors show that both CP infection and metabolic stress associated with dyslipidemia use the same innate immune response pathway, utilizing TLR4/MyD88 signaling, with similar relative contributions in bone marrow-derived hematopoietic cells and in stromal cells. Further studies are required to understand this intricate and complex cross talk among innate and adaptive immune systems in various conditions to more effectively design dendritic cell-mediated atheroprotective vaccines and other therapeutic strategies.

Swell, or Not Too Swell: Cytokines Regulate Arterial Aneurysm Formation

Arterial remodeling participates pivotally in many diseases including arterial aneurysms. In this issue of Immunity, Da Ros et al. (2017) report that, in experimental aortic aneurysm formation, neutralization of interleukin-1β reduced arterial wall stiffness and hampered aneurysm development.

Inflammation, Immunity, and Infection in Atherothrombosis: JACC Review Topic of the Week

Observations on human and experimental atherosclerosis, biomarker studies, and now a large-scale clinical trial support the operation of immune and inflammatory pathways in this disease. The factors that incite innate and adaptive immune responses implicated in atherogenesis and in lesion complication include traditional risk factors such as protein and lipid components of native and modified low-density lipoprotein, angiotensin II, smoking, visceral adipose tissue, and dysmetabolism. Infectious processes and products of the endogenous microbiome might also modulate atherosclerosis and its complications either directly, or indirectly by eliciting local and systemic responses that potentiate disease expression. Trials with antibiotics have not reduced recurrent cardiovascular events, nor have vaccination strategies yet achieved clinical translation. However, anti-inflammatory interventions such as anticytokine therapy and colchicine have begun to show efficacy in this regard. Thus, inflammatory and immune mechanisms can link traditional and emerging risk factors to atherosclerosis, and offer novel avenues for therapeutic intervention.

Interleukin-1 Beta as a Target for Atherosclerosis Therapy: Biological Basis of CANTOS and Beyond

Inflammatory pathways drive atherogenesis and link conventional risk factors to atherosclerosis and its complications. One inflammatory mediator has come to the fore as a therapeutic target in cardiovascular disease. The experimental and clinical evidence reviewed here support interleukin-1 beta (IL-1β) as both a local vascular and systemic contributor in this regard. Intrinsic vascular wall cells and lesional leukocytes alike can produce this cytokine. Local stimuli in the plaque favor the generation of active IL-1β through the action of a molecular assembly known as the inflammasome. Clinically applicable interventions that interfere with IL-1 action can improve cardiovascular outcomes, ushering in a new era of anti-inflammatory therapies for atherosclerosis. The translational path described here illustrates how advances in basic vascular biology may transform therapy. Biomarker-directed application of anti-inflammatory interventions promises to help us achieve a more precise and personalized allocation of therapy for our cardiovascular patients.

Role of the sympathetic nervous system in carbon tetrachloride-induced hepatotoxicity and systemic inflammation

Carbon tetrachloride (CCl₄) is widely used as an animal model of hepatotoxicity and the mechanisms have been arduously studied, however, the contribution of the sympathetic nervous system (SNS) in CCl₄-induced acute hepatotoxicity remains controversial. It is also known that either CCl₄ or SNS can affect systemic inflammatory responses. The aim of this study was to establish the effect of chemical sympathectomy with 6-hydroxydopamine (6-OHDA) in a mouse model of CCl₄-induced acute hepatotoxicity and systemic inflammatory response. Mice exposed to CCl₄ or vehicle were pretreated with 6-OHDA or saline. The serum levels of aminotransferases and alkaline phosphatase in the CCl₄-poisoning mice with sympathetic denervation were significantly lower than those without sympathetic denervation. With sympathetic denervation, hepatocellular necrosis and fat infiltration induced by CCl₄ were greatly decreased. Sympathetic denervation significantly attenuated CCl₄-induced lipid peroxidation in liver and serum. Acute CCl₄ intoxication showed increased expression of inflammatory cytokines/chemokines [eotaxin-2/CCL24, Fas ligand, interleukin (IL)-1α, IL-6, IL-12p40p70, monocyte chemoattractant protein-1 (MCP-1/CCL2), and tumor necrosis factor-α (TNF-α)], as well as decreased expression of granulocyte colony-stimulating factor and keratinocyte-derived chemokine. The overexpressed levels of IL-1α, IL-6, IL-12p40p70, MCP-1/CCL2, and TNF-α were attenuated by sympathetic denervation. Pretreatment with dexamethasone significantly reduced CCl₄-induced hepatic injury. Collectively, this study demonstrates that the SNS plays an important role in CCl₄-induced acute hepatotoxicity and systemic inflammation and the effect may be connected with chemical- or drug-induced hepatotoxicity and circulating immune response.

Interleukin-1 potently contributes to 25-hydroxycholesterol-induced synergistic cytokine production in smooth muscle cell-monocyte interactions

OBJECTIVES

Inflammation is essential for atherogenesis. Cholesterol, a cardiovascular risk factor, may activate inflammation in the vessel wall during this process. Cytokine-mediated interactions of human monocytes with vascular smooth muscle cells (SMCs) may perpetuate this process.

METHODS

We investigated the capacity of the cholesterol metabolite 25-hydroxycholesterol to induce inflammatory mediators in cocultures of freshly isolated monocytes with SMCs. We determined the role of interleukin-(IL)-1 in this interaction using qPCR, bioassays, ELISA and western blot. Cocultures with SMC to monocyte ratios from 1:4 to 1:20 were tested.

RESULTS

In separate SMC and monocyte cultures (monocultures) 25-hydroxycholesterol only poorly activated IL-1, IL-6 and MCP-1 production, whereas LPS stimulated much higher cytokine levels than unstimulated cultures. In contrast, cocultures of SMCs and monocytes stimulated with 25-hydroxycholesterol produced hundredfold higher cytokine levels than the corresponding monocultures. Blocking experiments with IL-1-receptor antagonist showed that IL-1 decisively contributed to the 25-hydroxycholesterol-induced synergistic IL-6 and MCP-1 production. The presence of intracellular IL-1β precursor, released mature IL-1β, and caspase-1 p10 indicated that the inflammasome was involved in this process. Determination of IL-1-mRNA in Transwell experiments indicated that the monocytes are the major source of IL-1, which subsequently activates the SMCs, the primary source of IL-6 in the coculture.

CONCLUSION

Taken together, these interactions between local vessel wall cells and invading monocytes may multiply cholesterol-triggered inflammation in the vessel wall, and IL-1 may play a key role in this process. The data also indicate that lower cholesterol levels than expected from monocultures may suffice to initiate inflammation in the tissue.

The interleukin-1 gene cluster polymorphisms are associated with Takayasu's arteritis in Mexican patients

Takayasu's arteritis (TA) is a chronic inflammatory arteritis of unknown etiology involving mainly the aorta and its major branches. The interleukin (IL) 1β and IL-1 receptor antagonist have been playing an important role as regulators of inflammation. We investigated whether the polymorphisms at the IL-1B and IL-1RN gene cluster were associated with the genetic susceptibility to develop TA. We analyzed the IL-1B, IL-1F10.3, and IL-1RN polymorphisms in a sample of 58 TA patients, and 248 clinically healthy unrelated Mexican individuals by 5' exonuclease TaqMan polymerase chain reaction. Polymorphic haplotypes were constructed after linkage disequilibrium analysis. We found increased frequencies of different polymorphisms (C allele and TC genotype of IL-1F10.3; TT genotype of IL-1RN.4; C allele and TC genotype of IL-1RN6.1; G allele of IL-1RN6.2 and haplotypes "1T" and "1C" of IL-RN VNTR and IL-1RN6.1) in the group of TA when compared to healthy controls. On the other hand, decreased frequency of IL-1-511 TC genotype was found in the TA group compared to controls. IL-1B and IL-1RN gene polymorphisms could be involved in the risk of developing TA in the Mexican population. These associations were independent of the affected vessels.

Interleukin-1 associations in inflammatory bowel disease and the enteropathic seronegative spondylarthritis

Purpose

This study aims to investigate any associations of the proinflammatory cytokine IL-1 in treated patients with inflammatory bowel disease (IBD) and the enteropathic seronegative spondylarthritis (eSpA).

Methods

Thirty-four patients with Crohn’s disease (CD), 26 with ulcerative colitis (UC) and 14 patients with SpA participated in the study. Valid clinical indexes, CRP values and the endoscopic and histologic examination were used for the determination of disease activity. IL-1α, IL-1β, IL-1 receptor antagonist (IL-1Ra) were measured by ELISA. Nonparametric tests were used for continuous and categorical data.

Results

Enteropathic SpA diagnosed in 29.4 % CD and 30.8 % UC patients. Active disease had 58.8 % CD (aCD), 76.9 % UC and 50 % SpA patients. Active and inactive CD (iCD) significantly differ on IL-1α levels (11.2 vs. 3.9 pg/ml; p = 0.034). Active and inactive UC significantly differ on IL-1β (3.7 vs. 2.3 pg/ml; p = 0.054) and IL-1Ra levels (15.9 vs. 12.7 pg/ml; p = 0.023). Active and inactive SpA (iSpA) significantly differ on IL-1Ra (16.9 vs. 14.8 pg/ml; p = 0.033) and marginally on IL-1α levels (20 vs. 3.9 pg/ml; p = 0.06). Patients with aCD/ieSpA exhibited significant differences on IL-1α (p = 0.022) compared to those with iCD/ieSpA.

Conclusions

IL-1α is associated with CD activity, while IL-1β and IL-1Ra are associated with UC activity in treated patients with IBD. Prominent cytokine in SpAs seems to be IL-1α.

Inflammation in atherosclerosis

Experimental work has elucidated molecular and cellular pathways of inflammation that promote atherosclerosis. Unraveling the roles of cytokines as inflammatory messengers provided a mechanism whereby risk factors for atherosclerosis can alter arterial biology, and produce a systemic milieu that favors atherothrombotic events. The discovery of the immune basis of allograft arteriosclerosis demonstrated that inflammation per se can drive arterial hyperplasia, even in the absence of traditional risk factors. Inflammation regulates aspects of plaque biology that trigger the thrombotic complications of atherosclerosis. Translation of these discoveries to humans has enabled both novel mechanistic insights and practical clinical advances.

Functional polymorphism of IL-1 alpha and its potential role in obesity in humans and mice

Proinflammatory cytokines secreted from adipose tissue contribute to the morbidity associated with obesity. IL-1α is one of the proinflammatory cytokines; however, it has not been clarified whether IL-1α may also cause obesity. In this study, we investigated whether polymorphisms in IL-1α contribute to human obesity. A total of 260 obese subjects were genotyped for IL-1α C-889T (rs1800587) and IL-1α G+4845T (rs17561). Analyses of genotype distributions revealed that both IL-1α polymorphisms C-889T (rs1800587) and G+4845T (rs17561) were associated with an increase in body mass index in obese healthy women. In addition, the effect of rs1800587 on the transcriptional activity of IL-1α was explored in pre-adipocyte 3T3-L1 cells. Significant difference was found between the rs1800587 polymorphism in the regulatory region of the IL-1α gene and transcriptional activity. We extended these observations in vivo to a high-fat diet-induced obese mouse model and in vitro to pre-adipocyte 3T3-L1 cells. IL-1α levels were dramatically augmented in obese mice, and triglyceride was increased 12 hours after IL-1α injection. Taken together, IL-1α treatment regulated the differentiation of preadipocytes. IL-1α C-889T (rs1800587) is a functional polymorphism of IL-1α associated with obesity. IL-1α may have a critical function in the development of obesity.

Interleukin-1 receptor type-1 in non-hematopoietic cells is the target for the pro-atherogenic effects of interleukin-1 in apoE-deficient mice

OBJECTIVES

Interleukin (IL)-1 produced by vascular and bone marrow-derived cells exerts proinflammatory effects in these cell types by binding to IL-1 receptor type-1 (IL-1R1). We have previously shown that bone marrow-derived IL-1α and IL-1β are critical for atherogenesis in apoE knockout (KO) mice. The aim of the present study was to investigate whether IL-1R1 on vascular wall resident or bone marrow-derived cells mediates IL-1's effects in atherogenesis.

METHODS AND RESULTS

We generated apoE-/-/IL-1R1-/- double knockout (DKO) mice and created radiation chimeras. Aortic sinus lesion area was 20-47% lower in DKO compared to apoE KO mice with similar plasma lipids. The production of IL-1α and IL-1β upon stimulation with LPS was not altered in IL-1R1-/- compared to IL-1R1+/+ peritoneal macrophages. DKO mice transplanted with IL-1R1+/+ bone marrow-derived cells had reduced (48%) aortic sinus lesion compared to apoE KO mice while specific deficiency of IL-1R1 in bone marrow-derived cells did not attenuate atherosclerosis. The mRNA levels of genes that promote macrophage recruitment to the vascular wall, namely CD68, VCAM-1, ICAM-1 and MCP-1 were lower in aortas from DKO compared to apoE KO mice. Finally, blockade of IL-1R1 with IL-1R antagonist (IL-1Ra) resulted in complete abrogation of IL-1β-induced expression of adhesion and chemotactic molecules and IL-1α, in isolated human umbilical vein endothelial cells (HUVEC).

CONCLUSIONS

Vascular wall resident cells are the main targets for the pro-atherogenic effects of bone marrow-derived IL-1 through IL-1R1, partly by induction of adhesion and chemotactic molecules in endothelial cells.

Interleukin-1β inhibition and the prevention of recurrent cardiovascular events: rationale and design of the Canakinumab Anti-inflammatory Thrombosis Outcomes Study (CANTOS)

BACKGROUND

Inflammation contributes to all phases of the atherothrombotic process, and patients with elevated inflammatory biomarkers such as high-sensitivity C-reactive protein (hsCRP) have increased vascular risk. Yet, it remains unknown whether direct inhibition of inflammation will reduce cardiovascular event rates.

DESIGN

The CANTOS will evaluate whether interleukin-1β (IL-1β) inhibition as compared with placebo can reduce rates of recurrent myocardial infarction, stroke, and cardiovascular death among stable patients with coronary artery disease who remain at high vascular risk due to persistent elevations of hsCRP (>2 mg/L) despite contemporary secondary prevention strategies. Canakinumab is a human monoclonal antibody that selectively neutralizes IL-1β, a proinflammatory cytokine that plays multiple roles in the atherothrombotic process and that undergoes activation by the nucleotide-binding leucine-rich repeat-containing pyrin receptor 3 inflammasome, a process promoted by cholesterol crystals. Canakinumab significantly reduces systemic C-reactive protein and other inflammatory biomarker levels, is generally well tolerated, and is currently indicated for the treatment of inherited IL-1β driven inflammatory diseases such as the Muckle-Wells syndrome. In a multinational collaborative effort using an event-driven intention-to-treat protocol, CANTOS will randomly allocate 17,200 stable postmyocardial infarction patients with persistent elevation of hsCRP to either placebo or to canakinumab at doses of 50, 150, or 300 mg every 3 months, administered subcutaneously. All participants will be followed up over an estimated period of up to 4 years for the trial primary end point (nonfatal myocardial infarction, nonfatal stroke, cardiovascular death) as well as for other vascular events, total mortality, adverse events, and specific clinical end points associated with inflammation including new onset diabetes, venous thrombosis, and atrial fibrillation.

SUMMARY

If positive, CANTOS would confirm the inflammatory hypothesis of atherothrombosis and provide a novel cytokine-based therapy for the secondary prevention of cardiovascular disease and new-onset diabetes.

Contribution of vascular cell-derived cytokines to innate and inflammatory pathways in atherogenesis

Inflammation is a central element of atherogenesis. Innate pathways contribute to vascular inflammation. However, the initial molecular process(es) starting atherogenesis remain elusive. The various risk factors, represented by particular compounds (activators), may cause altered cellular functions in the endothelium (e.g. vascular endothelial cell activation or -dysfunction), in invading cells (e.g. inflammatory mediator production) or in local vessel wall cells (e.g. inflammatory mediators, migration), thereby triggering the innate inflammatory process. The cellular components of innate immunology include granulocytes, natural killer cells and monocytes. Among the molecular innate constituents are innate molecules, such as the toll-like receptors or innate cytokines. Interleukin-1 (IL-1) and IL-6 are among the innate cytokines. Cytokines are potent activators of a great number of cellular functions relevant to maintain or commove homeostasis of the vessel wall. Within the vessel wall, vascular smooth muscle cells (SMCs) can significantly contribute to the cytokine-dependent inflammatory network by: (i) production of cytokines, (ii) response to cytokines and (iii) cytokine-mediated interaction with invading leucocytes. The cytokines IL-1 and IL-6 are involved in SMC-leucocyte interaction. The IL-6 effects are proposed to be mediated by trans-signalling. Dysregulated cellular functions resulting from dysregulated cytokine production may be the cause of cell accumulation, subsequent low-density lipoprotein accumulation and deposition of extracellular matrix (ECM). The deposition of ECM, increased accumulation of leucocytes and altered levels of inflammatory mediators may constitute an 'innate-immunovascular-memory' resulting in an ever-growing response to anew invasion. Thus, SMC-fostered inflammation, promoted by invading innate cells, may be a potent component for development and acceleration of atherosclerosis.

Interleukin-1 regulates multiple atherogenic mechanisms in response to fat feeding

Background

Atherosclerosis is an inflammatory process that develops in individuals with known risk factors that include hypertension and hyperlipidaemia, influenced by diet. However, the interplay between diet, inflammatory mechanisms and vascular risk factors requires further research. We hypothesised that interleukin-1 (IL-1) signaling in the vessel wall would raise arterial blood pressure and promote atheroma.

Methodology/Principal Findings

Apoe^−/− and Apoe^−/−/IL-1R1^−/− mice were fed high fat diets for 8 weeks, and their blood pressure and atherosclerosis development measured. Apoe^−/−/IL-R1^−/− mice had a reduced blood pressure and significantly less atheroma than Apoe^−/− mice. Selective loss of IL-1 signaling in the vessel wall by bone marrow transplantation also reduced plaque burden (p<0.05). This was associated with an IL-1 mediated loss of endothelium-dependent relaxation and an increase in vessel wall Nox 4. Inhibition of IL-1 restored endothelium-dependent vasodilatation and reduced levels of arterial oxidative stress.

Conclusions/Significance

The IL-1 cytokine system links atherogenic environmental stimuli with arterial inflammation, oxidative stress, increased blood pressure and atherosclerosis. This is the first demonstration that inhibition of a single cytokine can block the rise in blood pressure in response to an environmental stimulus. IL-1 inhibition may have profound beneficial effects on atherogenesis in man.

Increased interleukin (IL)-1beta messenger ribonucleic acid expression in beta -cells of individuals with type 2 diabetes and regulation of IL-1beta in human islets by glucose and autostimulation

CONTEXT

Elevated glucose levels impair islet function and survival, and it has been proposed that intraislet expression of IL-1beta contributes to glucotoxicity.

OBJECTIVE

The objective was to investigate IL-1beta mRNA expression in near-pure beta-cells of patients with type 2 diabetes (T2DM) and study the regulation of IL-1beta by glucose in isolated human islets.

METHODS

Laser capture microdissection was performed to isolate beta-cells from pancreas sections of 10 type 2 diabetic donors and nine controls, and IL-1beta mRNA expression was analyzed using gene arrays and PCR. Cultured human islets and fluorescence-activated cell sorter-purified human beta-cells were used to study the regulation of IL-1beta expression by glucose and IL-1beta.

RESULTS

Gene array analysis of RNA from beta-cells of individuals with T2DM revealed increased expression of IL-1beta mRNA. Real-time PCR confirmed increased IL-1beta expression in six of 10 T2DM samples, with minimal or no expression in nine control samples. In cultured human islets, IL-1beta mRNA and protein expression was induced by high glucose and IL-1beta autostimulation and decreased by the IL-1 receptor antagonist IL-1Ra. The glucose response was negatively correlated with basal IL-1beta expression levels. Autostimulation was transient and nuclear factor-kappaB dependent. Glucose-induced IL-1beta was biologically active and stimulated IL-8 release. Low picogram per milliliter concentrations of IL-1beta up-regulated inflammatory factors IL-8 and IL-6.

CONCLUSION

Evidence that IL-1beta mRNA expression is up-regulated in beta-cells of patients with T2DM is presented, and glucose-promoted IL-1beta autostimulation may be a possible contributor.

Vascular cells contribute to atherosclerosis by cytokine- and innate-immunity-related inflammatory mechanisms

Cardiovascular diseases are the human diseases with the highest death rate and atherosclerosis is one of the major underlying causes of cardiovascular diseases. Inflammatory and innate immune mechanisms, employing monocytes, innate receptors, innate cytokines, or chemokines are suggested to be involved in atherogenesis. Among the inflammatory pathways the cytokines are central players. Plasma levels of cytokines and related proteins, such as CRP, have been investigated in cardiovascular patients, tissue mRNA expression was analyzed and correlations to vascular diseases established. Consistent with these findings the generation of cytokine-deficient animals has provided direct evidence for a role of cytokines in atherosclerosis. In vitro cell culture experiments further support the suggestion that cytokines and other innate mechanisms contribute to atherogenesis. Among the initiation pathways of atherogenesis are innate mechanisms, such as toll-like-receptors (TLRs), including the endotoxin receptor TLR4. On the other hand, innate cytokines, such as IL-1 or TNF, or even autoimmune triggers may activate the cells. Cytokines potently activate multiple functions relevant to maintain or spoil homeostasis within the vessel wall. Vascular cells, not least smooth muscle cells, can actively contribute to the inflammatory cytokine-dependent network in the blood vessel wall by: (i) production of cytokines; (ii) response to these potent cell activators; and (iii) cytokine-mediated interaction with invading cells, such as monocytes, T-cells, or mast cells. Activation of these pathways results in accumulation of cells and increased LDL- and ECM-deposition which may serve as an 'immunovascular memory' resulting in an ever-growing response to subsequent invasions. Thus, vascular cells may potently contribute to the inflammatory pathways involved in development and acceleration of atherosclerosis.

Airway smooth muscle in asthma

Airway smooth muscle plays a multifaceted role in the pathogenesis of asthma. We review the current understanding of the contribution of airway myocytes to airway inflammation, airway wall remodeling, and airflow obstruction in this prevalent disease syndrome. Together, these roles make airway smooth muscle an attractive target for asthma therapy.

Major differences in gene expression in human coronary smooth muscle cells after nebivolol or metoprolol treatment

OBJECTIVE

Vascular smooth muscle cells play a pivotal role in all stages of atherogenesis. Targeting their inflammatory and proliferative qualities might therefore inhibit the progression of atherosclerosis. This study aimed to characterize and compare the effects of the beta-receptor antagonists nebivolol and metoprolol on gene expression in human coronary artery smooth muscle cells (hcaSMC).

METHODS AND RESULTS

hcaSMC were incubated with nebivolol or metoprolol (10(-5) mol/l) for 72 h. The downregulated genes are involved in inflammatory processes, oxidative stress and smooth muscle cell proliferation: i.e. downregulated were by nebivolol: interleukin-1alpha, cyclooxygenase-2, tumor-necrosis-factor (TNF)-alpha-induced protein 6, PDGF-A, growth-related oncogenes 2 and 3. Metoprolol increased the expression of interleukin-1alpha, cyclooxygenase-1, TNF-alpha-induced protein 3, heme oxygenase 1 and granulocyte/macrophage-colony-stimulating factor. In addition downregulated was monocyte chemoattractant protein 1 (MCP-1) mRNA by nebivolol. Nebivolol (10(-5) mol/l) reduced the amount of basal NF-kappaB after 48 and 52 h but not metoprolol. In the culture supernatants, MCP-1 concentrations were reduced by nebivolol.

CONCLUSIONS

Nebivolol induced changes in the expression of inflammatory mediators in hcaSMC. These results add to data that suggest specific anti-inflammatory qualities of a beta-blocker of the third generation in comparison to metoprolol.

Inflammatory mechanisms: the molecular basis of inflammation and disease

Inflammation participates importantly in host defenses against infectious agents and injury, but it also contributes to the pathophysiology of many chronic diseases. Interactions of cells in the innate immune system, adaptive immune system, and inflammatory mediators orchestrate aspects of the acute and chronic inflammation that underlie diseases of many organs. A coordinated series of common effector mechanisms of inflammation contribute to tissue injury, oxidative stress, remodeling of the extracellular matrix, angiogenesis, and fibrosis in diverse target tissues. Atherosclerosis provides an example of a chronic disease that involves inflammatory mechanisms. Recruitment of blood leukocytes characterizes the initiation of this disease. Its progression involves many inflammatory mediators, modulated by cells of both innate and adaptive immunity. The complications of established atheroma, including plaque disruption and thrombosis, also intimately involve inflammation. Mastery of the inflammatory response should aid the development of novel strategies to predict disease susceptibility, target and monitor therapies, and ultimately develop new approaches to the prevention and treatment of chronic diseases associated with aging, such as atherosclerosis.

Fat Cell‐Derived Modulators of Vascular Cell Pathophysiology: The List Keeps Growing

Independent of the association of obesity with dyslipidemia, hypertension, and increased propensity for diabetes, fatness per se is increasingly recognized as a cardiovascular offender. That adipose tissue releases a wide range of adipokines, growth factors, enzymes, and enzyme substrates linked to vascular injury provides a plausible explanation for the role of fat in vascular disease: tumor necrosis factor-alpha, leptin, resistin, interleukin-1, -6, -8, and -18, serum amyloid A, monocyte chemoattractant protein I, macrophage inhibitory factor, aortic carboxypeptidase, hepa-rin-binding epidermal growth factor-like growth factor, vascular endothelial growth factor, transforming growth factor beta, angiotensinogen, cathepsin S, estradiol, cortisol, mineralocorticoid releasing factor, and calcitonin peptides are probable fat-derived prothrombotic, proinflammatory, and proatherosclerotic agents acting in a paracrine and/or endocrine manner. Other adipocyte products such as adiponectin, transforming growth factor beta, and interleukin-10 exert some antiatherogenic effects. The following is a short overview of how adipose tissue products affect the vasculature.

Differential role and tissue specificity of interleukin-1alpha gene expression in atherogenesis and lipid metabolism

OBJECTIVE

We examined the role of IL-1alpha and IL-1beta expressed by bone marrow-derived cells in atherogenesis and lipid metabolism.

METHODS AND RESULTS

We first studied the effect of atherogenic diet on wild-type C57BL/6 IL-1alpha or IL-1beta deficient mice. IL-1alpha KO resulted in a comparatively higher total cholesterol levels, compared to WT and IL-1beta KO mice (398+/-10; 266+/-19; 223+/-13 mg/dl, respectively, p<0.001), due to higher non-HDL cholesterol. Nevertheless, aortic sinus lesion area was 56% lower in IL-1alpha KO (p<0.05) and 50% lower in IL-1beta KO (p=0.08), compared to WT mice. Likewise, SAA levels in IL-1alpha KO mice were markedly lower compared to WT and IL-1beta KO mice (31+/-14; 220+/-33 and 106+/-39 microg/ml, respectively, p<0.001). To study the specific role of bone marrow-derived IL-1, irradiated C57BL/6 mice were transplanted with either IL-1+/+, IL-1alpha-/- or IL-1beta-/- bone marrow cells. Despite similar lipoprotein levels, aortic sinus lesion area was 59% lower in IL-1alpha-/- transplanted (p<0.05) compared to IL-1+/+ transplanted mice. Lesion area in IL-1beta-/- was 33% lower than in IL-1+/+ recipient mice, but it was not statistically significant.

CONCLUSION

We demonstrated that early lesion formation is accelerated specifically by bone marrow-derived IL-1alpha. Furthermore, we showed that the expression of IL-1alpha in cells other than the bone marrow plays a significant role in non-HDL cholesterol metabolism.

The effect of interleukin-1 receptor antagonist on arteries and cholesterol metabolism

This review summarizes both the structure and function of IL-1 receptor antagonist (IL-1Ra), and relates our new findings, particularly those obtained in IL-1Ra-deficient mice (IL-1Ra(-/-)), to the role of IL-1Ra in arterial diseases and cholesterol metabolism. IL-1Ra(-/-) mice show an increase in neointima-formation after arterial injury. Heterozygosity in the IL-1Ra gene against the apolipoprotein E-deficient background revealed a role for IL-1 in promoting atherogenic cell signaling and that the larger lesions of IL-1Ra(-/-) mice are enriched in macrophages and depleted of smooth muscle cells. Furthermore, IL-1Ra(-/-) mice developed severe fatty livers and hypercholesteroremia following 20 weeks on a atherogenic diet compared to WT mice. Taken together, these results suggest that IL-1Ra plays important roles in restenosis after angioplasty, the development of atherosclerosis, and the metabolism of cholesterol in vivo.

Proinflammatory phenotype of vascular smooth muscle cells: role of efficient Toll-like receptor 4 signaling

Recent evidence supports a role of Toll-like receptor (TLR) signaling in the development of atherosclerotic lesions. In this study, we tested whether TLR4 signaling promotes a proinflammatory phenotype in human and mouse arterial smooth muscle cells (SMC), characterized by increased cytokine and chemokine synthesis and increased TLR expression. Human arterial SMC were found to express mRNA encoding TLR4 and the TLR4-associated molecules MD-2 and CD14 but not TLR2 mRNA. Mouse aortic SMC, on the other hand, expressed both TLR2 and TLR4 mRNA constitutively. Human SMC derived from the coronary artery, but not those from the pulmonary artery, were found to express cell surface-associated CD14. Low concentrations (ng/ml) of Escherichia coli LPS, the prototypical TLR4 agonist, markedly stimulated extracellular regulated kinase 1/2 (ERK1/2) activity, induced release of monocyte-chemoattractant protein-1 (MCP-1) and interleukin (IL)-6, and stimulated IL-1alpha expression in human aortic SMC, and exogenous CD14 enhanced these effects. Expression of a dominant negative form of TLR4 in human SMC attenuated LPS-induced ERK1/2 and MCP-1 release. LPS was a potent inducer of NF-kappaB activity, ERK1/2 phosphorylation, MCP-1 release, and TLR2 mRNA expression in wild-type mice but not in TLR4-signaling deficient mouse aortic SMC. These studies show that TLR4 signaling promotes a proinflammatory phenotype in vascular smooth muscle cells (VSMC) and suggest that VSMC may potentially play an active role in vascular inflammation via the release of chemokines, proinflammatory cytokines, and increased expression of TLR2.