Adult human vascular endothelial cells express the IL6 gene differentially in response to LPS or IL1

Serum NLRP3: A potential marker for identifying high-risk coronary arterial aneurysm in children with Kawasaki disease

BACKGROUND

Kawasaki disease (KD) is a vasculitis of unknown etiology in children aged under 5 years. Coronary arterial aneurysm (CAA) is the major complication of KD. It is no longer though to be a self-limiting disease because its cardiovascular sequelae might persist into adulthood. NLRP3 is a key protein of the NLRP3 inflammasome that participates in sterile inflammatory disease. This study investigated the serum levels of NLRP3 in patients with KD at different stages to explore the relationships between serum NLRP3 and clinical parameters.

METHODS

A total of 247 children enrolled in this study. There were 123 patients in the acute stage of KD, and 93 healthy children made up the healthy control (HC) group. Among the acute KD patients, 52 had coronary arterial aneurysm (KD-CAA) and 71 did not (KD-NCAA). 36 patient samples were collected after IVIG and aspirin treatment. Additionally, 29 patients were in the cardiovascular sequelae stage. Enzyme-linked immunosorbent assay was used to measure serum NLRP3 levels in all subjects.

RESULTS

Serum NLRP3 was elevated in the KD group and was even higher in the KD-CAA subgroup than in the KD-NCAA subgroup of acute-stage patients. Serum NLRP3 declined when the patients were treated with IVIG and aspirin, but during the convalescent (coronary sequelae) stage, serum NLRP3 re-increased. Serum NLRP3 was higher in the ≥ 6-mm-coronary-arterial-diameter group than that the < 6-mm-diameter group. The ROC curve of serum NLRP3 indicated its utility in the prediction of both KD and KD-CAA.

CONCLUSIONS

NLRP3 may be involved in the development of KD and CAA in children with KD. Targeting NLRP3 might mitigate CAA, thereby reducing the risk of cardiovascular events in adulthood.

Long COVID Definition, Symptoms, Risk Factors, Epidemiology and Autoimmunity: A Narrative Review

The virus called SARS-CoV-2 emerged in 2019 and quickly spread worldwide, causing COVID-19. It has greatly impacted on everyday life, healthcare systems, and the global economy. In order to save as many lives as possible, precautions such as social distancing, quarantine, and testing policies were implemented, and effective vaccines were developed. A growing amount of data collected worldwide allowed the characterization of this new disease, which turned out to be more complex than other common respiratory tract infections. An increasing number of convalescents presented with a variety of nonspecific symptoms emerging after the acute infection. This possible new global health problem was identified and labelled as long COVID. Since then, a great effort has been made by clinicians and the scientific community to understand the underlying mechanisms and to develop preventive measures and effective treatment. The role of autoimmunity induced by SARS-CoV-2 infection in the development of long COVID is discussed in this review. We aim to deliver a description of several conditions with an autoimmune background observed in COVID-19 convalescents, including Guillain-Barré syndrome, antiphospholipid syndrome and related thrombosis, and Kawasaki disease highlighting a relationship between SARS-CoV-2 infection and the development of autoimmunity. However, further studies are required to determine its true clinical significance.

Obesity and prostate cancer - microenvironmental roles of adipose tissue

Obesity is known to have important roles in driving prostate cancer aggressiveness and increased mortality. Multiple mechanisms have been postulated for these clinical observations, including effects of diet and lifestyle, systemic changes in energy balance and hormonal regulation and activation of signalling by growth factors and cytokines and other components of the immune system. Over the past decade, research on obesity has shifted towards investigating the role of peri-prostatic white adipose tissue as an important source of locally produced factors that stimulate prostate cancer progression. Cells that comprise white adipose tissue, the adipocytes and their progenitor adipose stromal cells (ASCs), which proliferate to accommodate white adipose tissue expansion in obesity, have been identified as important drivers of obesity-associated cancer progression. Accumulating evidence suggests that adipocytes are a source of lipids that are used by adjacent prostate cancer cells. However, results of preclinical studies indicate that ASCs promote tumour growth by remodelling extracellular matrix and supporting neovascularization, contributing to the recruitment of immunosuppressive cells, and inducing epithelial-mesenchymal transition through paracrine signalling. Because epithelial-mesenchymal transition is associated with cancer chemotherapy resistance and metastasis, ASCs are considered to be potential targets of therapies that could be developed to suppress cancer aggressiveness in patients with obesity.

Secondary Cardiovascular Prevention after Acute Coronary Syndrome: Emerging Risk Factors and Novel Therapeutic Targets

The control of cardiovascular risk factors, the promotion of a healthy lifestyle, and antithrombotic therapy are the cornerstones of secondary prevention after acute coronary syndrome (ACS). However, many patients have recurrent ischemic events despite the optimal control of traditional modifiable risk factors and the use of tailored pharmacological therapy, including new-generation antiplatelet and lipid-lowering agents. This evidence emphasizes the importance of identifying novel risk factors and targets to optimize secondary preventive strategies. Lipoprotein(a) (Lp(a)) has emerged as an independent predictor of adverse events after ACS. New molecules such as anti-PCSK9 monoclonal antibodies, small interfering RNAs, and antisense oligonucleotides can reduce plasma Lp(a) levels and are associated with a long-term outcome benefit after the index event. The inflammatory stimulus and the inflammasome, pivotal elements in the development and progression of atherosclerosis, have been widely investigated in patients with coronary artery disease. More recently, randomized clinical trials including post-ACS patients treated with colchicine and monoclonal antibodies targeting cytokines yielded promising results in the reduction in major cardiovascular events after an ACS. Gut dysbiosis has also raised great interest for its potential pathophysiological role in cardiovascular disease. This evidence, albeit preliminary and needing confirmation by larger population-based studies, suggests the possibility of targeting the gut microbiome in particularly high-risk populations. The risk of recurrent ischemic events after ACS is related to the complex interaction between intrinsic predisposing factors and environmental triggers. The identification of novel risk factors and targets is fundamental to customizing patient clinical management with a precision medicine perspective.

The complex pathophysiology of cardiac cachexia: A review of current pathophysiology and implications for clinical practice

Cardiac cachexia is a muscle wasting process that often develops in those with chronic heart failure resulting in weight loss, low levels of physical activity, reduced quality of life, and is associated with a poor prognosis. The pathology of cardiac cachexia is complex with new evidence emerging that implicates several body systems. This review describes the pathophysiology associated with cardiac cachexia and addresses: 1) hormonal changes- neurohormonal abnormalities and metabolic hormone imbalance; 2) mechanisms of muscle wasting in cardiac cachexia, and the integral mechanisms between changed hormones due to cardiac cachexia and muscle wasting processes, and 3) associated abnormalities of gastrointestinal system that contribute to cardiac cachexia. These pleiotropic mechanisms demonstrate the intricate interplay between the affected systems and account for why cardiac cachexia is difficult to manage clinically. This review summarises current pathophysiology of cardiac cachexia and highlights symptoms of cardiac cachexia, implications for clinical practice and research gaps.

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.

Increased serum IL-6 is predictive of long-term cardiovascular events in high-risk patients submitted to coronary angiography: an observational study

BACKGROUND

Interleukin-6 (IL-6) is an inflammation-related cytokine associated with an elevated risk of cardiovascular events. In a previous study, we demonstrated that increased IL-6 was predictive of sub-clinical atherosclerotic coronary disease in intermediate-risk patients undergoing coronary angiography. In the present study, we investigated whether increased serum IL-6 is predictive of cardiovascular events in high-risk patients.

METHODS

In this observational study, consecutive patients referred for elective coronary angiography due to stable chest pain/myocardial ischemia had IL-6 measured immediately before the procedure. Long-term follow-up was performed by phone call or e-mail, and their clinical registries were revised. The primary outcome was a composite of new myocardial infarction, new ischemic stroke, hospitalization due to heart failure, new coronary revascularization, cardiovascular death, and death due to all causes.

RESULTS

From 141 patients submitted to coronary angiography and IL-6 analysis, 100 had complete follow-up data for a mean of 5.7 years. The median age was 61.1 years, 44% were men, and 61% had type-2 diabetes. The median overall time-to-event for the primary outcome was 297 weeks (95% confidence interval [CI] 266.95-327.16). A receiver operator characteristic curve defined the best cut-off value of baseline serum IL-6 (0.44 pg/mL) with sensitivity (84.37%) and specificity (38.24%) to define two groups. High (> 0.44 pg/mL) IL-6 levels were predictive of cardiovascular events. (p for interaction = 0.015) (hazard ratio = 2.81; 95% CI 1.38-5.72, p = 0.01). Subgroup analysis did not find interactions between patients with or without diabetes, obesity, or hypertension.

CONCLUSION

In conclusion, an interleukin-6 level higher than 0.44 pg/mL, obtained just before elective coronary angiography, was associated with a poorer prognosis after a mean of 5,7-year. A pre-procedure IL-6 below 0.44 pg/mL, on the other hand, has a very good negative predictive value, suggesting a good prognosis, and may be useful to better indicate coronary angiography in high-risk patients. .

Bone marrow endothelial dysfunction promotes myeloid cell expansion in cardiovascular disease

Abnormal hematopoiesis advances cardiovascular disease by generating excess inflammatory leukocytes that attack the arteries and the heart. The bone marrow niche regulates hematopoietic stem cell proliferation and hence the systemic leukocyte pool, but whether cardiovascular disease affects the hematopoietic organ's microvasculature is unknown. Here we show that hypertension, atherosclerosis and myocardial infarction (MI) instigate endothelial dysfunction, leakage, vascular fibrosis and angiogenesis in the bone marrow, altogether leading to overproduction of inflammatory myeloid cells and systemic leukocytosis. Limiting angiogenesis with endothelial deletion of Vegfr2 (encoding vascular endothelial growth factor (VEGF) receptor 2) curbed emergency hematopoiesis after MI. We noted that bone marrow endothelial cells assumed inflammatory transcriptional phenotypes in all examined stages of cardiovascular disease. Endothelial deletion of Il6 or Vcan (encoding versican), genes shown to be highly expressed in mice with atherosclerosis or MI, reduced hematopoiesis and systemic myeloid cell numbers in these conditions. Our findings establish that cardiovascular disease remodels the vascular bone marrow niche, stimulating hematopoiesis and production of inflammatory leukocytes.

Pathophysiology of Circulating Biomarkers and Relationship With Vascular Aging: A Review of the Literature From VascAgeNet Group on Circulating Biomarkers, European Cooperation in Science and Technology Action 18216

Impairment of the arteries is a product of sustained exposure to various deleterious factors and progresses with time; a phenomenon inherent to vascular aging. Oxidative stress, inflammation, the accumulation of harmful agents in high cardiovascular risk conditions, changes to the extracellular matrix, and/or alterations of the epigenetic modification of molecules, are all vital pathophysiological processes proven to contribute to vascular aging, and also lead to changes in levels of associated circulating molecules. Many of these molecules are consequently recognized as markers of vascular impairment and accelerated vascular aging in clinical and research settings, however, for these molecules to be classified as biomarkers of vascular aging, further criteria must be met. In this paper, we conducted a scoping literature review identifying thirty of the most important, and eight less important, biomarkers of vascular aging. Herein, we overview a selection of the most important molecules connected with the above-mentioned pathological conditions and study their usefulness as circulating biomarkers of vascular aging.

Heparin - Messias or Verschlimmbesserung?

A heightened risk of thrombosis noted early on with the severe acute respiratory syndrome coronavirus 2 infection led to the widespread use of heparin anticoagulation in the coronavirus disease 2019 (COVID-19) pandemic. However, reports soon started appearing in the literature where an apparent failure of heparin to prevent thrombotic events was observed in hospitalized patients with this viral infection. In this review, we explore the likely mechanisms for heparin failure with particular relevance to COVID-19. We also explore the role of anti-Xa assays and global hemostatic tests in this context. The current controversy of dosing heparin in this disease is detailed with some possible mechanistic reasons for anticoagulant failure. We hope that lessons learnt from the use of heparin in COVID-19 could assist us in the appropriate use of this anticoagulant in the future.

COVID-19 and Acute Coronary Syndromes: From Pathophysiology to Clinical Perspectives

Acute coronary syndromes (ACS) are frequently reported in patients with coronavirus disease 2019 (COVID-19) and may impact patient clinical course and mortality. Although the underlying pathogenesis remains unclear, several potential mechanisms have been hypothesized, including oxygen supply/demand imbalance, direct viral cellular damage, systemic inflammatory response with cytokine-mediated injury, microvascular thrombosis, and endothelial dysfunction. The severe hypoxic state, combined with other conditions frequently reported in COVID-19, namely sepsis, tachyarrhythmias, anemia, hypotension, and shock, can induce a myocardial damage due to the mismatch between oxygen supply and demand and results in type 2 myocardial infarction (MI). In addition, COVID-19 promotes atherosclerotic plaque instability and thrombus formation and may precipitate type 1 MI. Patients with severe disease often show decrease in platelets count, higher levels of d-dimer, ultralarge von Willebrand factor multimers, tissue factor, and prolongation of prothrombin time, which reflects a prothrombotic state. An endothelial dysfunction has been described as a consequence of the direct viral effects and of the hyperinflammatory environment. The expression of tissue factor, von Willebrand factor, thromboxane, and plasminogen activator inhibitor-1 promotes the prothrombotic status. In addition, endothelial cells generate superoxide anions, with enhanced local oxidative stress, and endothelin-1, which affects the vasodilator/vasoconstrictor balance and platelet aggregation. The optimal management of COVID-19 patients is a challenge both for logistic and clinical reasons. A deeper understanding of ACS pathophysiology may yield novel research insights and therapeutic perspectives in higher cardiovascular risk subjects with COVID-19.

IL-6 inhibition with ziltivekimab in patients at high atherosclerotic risk (RESCUE): a double-blind, randomised, placebo-controlled, phase 2 trial

BACKGROUND

IL-6 has emerged as a pivotal factor in atherothrombosis. Yet, the safety and efficacy of IL-6 inhibition among individuals at high atherosclerotic risk but without a systemic inflammatory disorder is unknown. We therefore addressed whether ziltivekimab, a fully human monoclonal antibody directed against the IL-6 ligand, safely and effectively reduces biomarkers of inflammation and thrombosis among patients with high cardiovascular risk. We focused on individuals with elevated high-sensitivity CRP and chronic kidney disease, a group with substantial unmet clinical need in whom previous studies in inflammation inhibition have shown efficacy for cardiovascular event reduction.

METHODS

RESCUE is a randomised, double-blind, phase 2 trial done at 40 clinical sites in the USA. Inclusion criteria were age 18 years or older, moderate to severe chronic kidney disease, and high-sensitivity CRP of at least 2 mg/L. Participants were randomly allocated (1:1:1:1) to subcutaneous administration of placebo or ziltivekimab 7·5 mg, 15 mg, or 30 mg every 4 weeks up to 24 weeks. The primary outcome was percentage change from baseline in high-sensitivity CRP after 12 weeks of treatment with ziltivekimab compared with placebo, with additional biomarker and safety data collected over 24 weeks of treatment. Primary analyses were done in the intention-to-treat population. Safety was assessed in all patients who received at least one dose of assigned treatment. The trial is registered with ClinicalTrials.gov, NCT03926117.

FINDINGS

Between June 17, 2019, and Jan 14, 2020, 264 participants were enrolled into the trial, of whom 66 were randomly assigned to each of the four treatment groups. At 12 weeks after randomisation, median high-sensitivity CRP levels were reduced by 77% for the 7·5 mg group, 88% for the 15 mg group, and 92% for the 30 mg group compared with 4% for the placebo group. As such, the median pairwise differences in percentage change in high-sensitivity CRP between the ziltivekimab and placebo groups, after aligning for strata, were -66·2% for the 7·5 mg group, -77·7% for the 15 mg group, and -87·8% for the 30 mg group (all p<0·0001). Effects were stable over the 24-week treatment period. Dose-dependent reductions were also observed for fibrinogen, serum amyloid A, haptoglobin, secretory phospholipase A2, and lipoprotein(a). Ziltivekimab was well tolerated, did not affect the total cholesterol to HDL cholesterol ratio, and there were no serious injection-site reactions, sustained grade 3 or 4 neutropenia or thrombocytopenia.

INTERPRETATION

Ziltivekimab markedly reduced biomarkers of inflammation and thrombosis relevant to atherosclerosis. On the basis of these data, a large-scale cardiovascular outcomes trial will investigate the effect of ziltivekimab in patients with chronic kidney disease, increased high-sensitivity CRP, and established cardiovascular disease.

FUNDING

Novo Nordisk.

Beyond Lipoprotein(a) plasma measurements: Lipoprotein(a) and inflammation

Genome wide association, epidemiological, and clinical studies have established high lipoprotein(a) [Lp(a)] as a causal risk factor for atherosclerotic cardiovascular disease (ASCVD). Lp(a) is an apoB100 containing lipoprotein covalently bound to apolipoprotein(a) [apo(a)], a glycoprotein. Plasma Lp(a) levels are to a large extent determined by genetics. Its link to cardiovascular disease (CVD) may be driven by its pro-inflammatory effects, of which its association with oxidized phospholipids (oxPL) bound to Lp(a) is the most studied. Various inflammatory conditions, such as rheumatoid arthritis (RA), systemic lupus erythematosus, acquired immunodeficiency syndrome, and chronic renal failure are associated with high Lp(a) levels. In cases of RA, high Lp(a) levels are reversed by interleukin-6 receptor (IL-6R) blockade by tocilizumab, suggesting a potential role for IL-6 in regulating Lp(a) plasma levels. Elevated levels of IL-6 and IL-6R polymorphisms are associated with CVD. Therapies aimed at lowering apo(a) and thereby reducing plasma Lp(a) levels are in clinical trials. Their results will determine if reductions in apo(a) and Lp(a) decrease cardiovascular outcomes. As we enter this new arena of available treatments, there is a need to improve our understanding of mechanisms. This review will focus on the role of Lp(a) in inflammation and CVD.

Interleukin-6 Signaling and Anti-Interleukin-6 Therapeutics in Cardiovascular Disease

IL (interleukin)-6 is a pivotal cytokine of innate immunity, which enacts a broad set of physiological functions traditionally associated with host defense, immune cell regulation, proliferation, and differentiation. Following recognition of innate immune pathways leading from the NLRP3 (NOD-, LRR-, and pyrin domain-containing protein 3) inflammasome to IL-1 to IL-6 and on to the hepatically derived clinical biomarker CRP (C-reactive protein), an expanding literature has led to understanding of the proatherogenic role for IL-6 in cardiovascular disease and thus the potential for IL-6 inhibition as a novel method for vascular protection. In this review, we provide an overview of the mechanisms by which IL-6 signaling occurs and how that impacts upon pharmacological inhibition; describe murine models of IL-6 and atherogenesis; summarize human epidemiological data outlining the utility of IL-6 as a biomarker of vascular risk; outline genetic data suggesting a causal role for IL-6 in systemic atherothrombosis and aneurysm formation; and then detail the potential role of IL-6 inhibition in stable coronary disease, acute coronary syndromes, heart failure, and the atherothrombotic complications associated with chronic kidney disease and end-stage renal failure. Finally, we review anti-inflammatory and antithrombotic findings for ziltivekimab, a novel IL-6 ligand inhibitor being developed specifically for use in atherosclerotic disease and poised to be tested formally in a large-scale cardiovascular outcomes trial focused on individuals with chronic kidney disease and elevated levels of CRP, a population at high residual atherothrombotic risk, high residual inflammatory risk, and considerable unmet clinical need.

Inhibition of IL-6 in the LCWE Mouse Model of Kawasaki Disease Inhibits Acute Phase Reactant Serum Amyloid A but Fails to Attenuate Vasculitis

Objective

Kawasaki disease (KD) is the most common cause of acquired pediatric heart disease in the developed world. 10% of KD patients are resistant to front-line therapy, and no interventions exist to address secondary complications such as myocardial fibrosis. We sought to identify proteins and pathways associated with disease and anti-IL-1 treatment in a mouse model of KD.

Methods

Vasculitis was induced via Lactobacillus casei cell wall extract (LCWE) injection in 5-week-old male mice. Groups of mice were injected with LCWE alone, LCWE and IL-1 receptor antagonist anakinra, or saline for controls. Upper heart tissue was assessed by quantitative mass spectrometry analysis. Expression and activation of STAT3 was assessed by immunohistochemistry, immunofluorescence and Western blot, and IL-6 expression by RNA-seq and ELISA. A STAT3 small molecular inhibitor and anti-IL-6R antibody were used to evaluate the role of STAT3 and IL-6 in disease development.

Results

STAT3 was highly expressed and phosphorylated in cardiac tissue of LCWE-injected mice, and reduced following anakinra treatment. Il6 and Stat3 gene expression was enhanced in abdominal aorta of LCWE-injected mice and reduced with Anakinra treatment. IL-6 serum levels were enhanced in LCWE-injected mice and normalized by anakinra. However, neither inhibition of STAT3 nor blockade of IL-6 altered disease development.

Conclusion

Proteomic analysis of cardiac tissues demonstrates differential protein expression between KD-like, control and anakinra treated cardiac tissue. STAT3 and IL-6 were highly upregulated with LCWE and normalized by anakinra treatment. However, both STAT3 and IL-6 were dispensable for disease development indicating they may be bystanders of inflammation.

Targeting inflammation in atherosclerosis - from experimental insights to the clinic

Atherosclerosis, a dominant and growing cause of death and disability worldwide, involves inflammation from its inception to the emergence of complications. Targeting inflammatory pathways could therefore provide a promising new avenue to prevent and treat atherosclerosis. Indeed, clinical studies have now demonstrated unequivocally that modulation of inflammation can forestall the clinical complications of atherosclerosis. This progress pinpoints the need for preclinical investigations to refine strategies for combatting inflammation in the human disease. In this Review, we consider a gamut of attractive possibilities for modifying inflammation in atherosclerosis, including targeting pivotal inflammatory pathways such as the inflammasomes, inhibiting cytokines, manipulating adaptive immunity and promoting pro-resolution mechanisms. Along with lifestyle measures, pharmacological interventions to mute inflammation could complement traditional targets, such as lipids and hypertension, to make new inroads into the management of atherosclerotic risk.

Longitudinal Transcriptomic Profiling in Carrageenan-Induced Rat Hind Paw Peripheral Inflammation and Hyperalgesia Reveals Progressive Recruitment of Innate Immune System Components

Pain is a common but potentially debilitating symptom, often requiring complex management strategies. To understand the molecular dynamics of peripheral inflammation and nociceptive pain, we investigated longitudinal changes in behavior, tissue structure, and transcriptomic profiles in the rat carrageenan-induced peripheral inflammation model. Sequential changes in the number of differentially expressed genes are consistent with temporal recruitment of key leukocyte populations, mainly neutrophils and macrophages with each wave being preceded by upregulation of the cell-specific chemoattractants, Cxcl1 and Cxcl2, and Ccl2 and Ccl7, respectively. We defined 12 temporal gene clusters based on expression pattern. Within the patterns we extracted genes comprising the inflammatory secretome and others related to nociceptive tissue remodeling and to sensory perception of pain. Structural tissue changes, involving upregulation of multiple collagens occurred as soon as 1-hour postinjection, consistent with inflammatory tissue remodeling. Inflammatory expression profiling revealed a broad-spectrum, temporally orchestrated molecular and cellular recruitment process. The results provide numerous potential targets for modulation of pain and inflammation. PERSPECTIVE: This study investigates the highly orchestrated biological response during tissue inflammation with precise assessment of molecular dynamics at the transcriptional level. The results identify transcriptional changes that define an evolving inflammatory state in rats. This study provides foundational data for identifying markers of, and potential treatments for, inflammation and pain in patients.

Inflammation in Coronary Atherosclerosis and Its Therapeutic Implications

Atherosclerotic coronary artery disease has a complex pathogenesis which extends beyond cholesterol intimal infiltration. It involves chronic inflammation of the coronary artery wall driven by systemic and local activation of both the adaptive and innate immune systems, which can ultimately result in the rupture or erosion of atherosclerotic plaque, leading to thrombosis and myocardial infarction (MI). Despite current best practice care, including the widespread use of cholesterol-lowering statins, atherothrombotic cardiovascular events recur at alarming rates post-MI. To a large extent, this reflects residual inflammation that is not adequately controlled by contemporary treatment. Consequently, there has been increasing interest in the pharmacological targeting of inflammation to improve outcomes in atherosclerotic cardiovascular disease. This has comprised both novel pathway-specific agents, most notably the anti-interleukin-1 beta monoclonal antibody, canakinumab, and the repurposing of established, broad-acting drugs, such as colchicine, that are already approved for the management of other inflammatory conditions. Here we discuss the importance of inflammation in mediating atherosclerosis and its complications and provide a timely update on "new" and "old" anti-inflammatory therapies currently being investigated to target it.

COVID-19 is, in the end, an endothelial disease

The vascular endothelium provides the crucial interface between the blood compartment and tissues, and displays a series of remarkable properties that normally maintain homeostasis. This tightly regulated palette of functions includes control of haemostasis, fibrinolysis, vasomotion, inflammation, oxidative stress, vascular permeability, and structure. While these functions participate in the moment-to-moment regulation of the circulation and coordinate many host defence mechanisms, they can also contribute to disease when their usually homeostatic and defensive functions over-reach and turn against the host. SARS-CoV-2, the aetiological agent of COVID-19, causes the current pandemic. It produces protean manifestations ranging from head to toe, wreaking seemingly indiscriminate havoc on multiple organ systems including the lungs, heart, brain, kidney, and vasculature. This essay explores the hypothesis that COVID-19, particularly in the later complicated stages, represents an endothelial disease. Cytokines, protein pro-inflammatory mediators, serve as key danger signals that shift endothelial functions from the homeostatic into the defensive mode. The endgame of COVID-19 usually involves a cytokine storm, a phlogistic phenomenon fed by well-understood positive feedback loops that govern cytokine production and overwhelm counter-regulatory mechanisms. The concept of COVID-19 as an endothelial disease provides a unifying pathophysiological picture of this raging infection, and also provides a framework for a rational treatment strategy at a time when we possess an indeed modest evidence base to guide our therapeutic attempts to confront this novel pandemic.

Platelet Transforming Growth Factor-β1 Induces Liver Sinusoidal Endothelial Cells to Secrete Interleukin-6

The roles and interactions of platelets and liver sinusoidal endothelial cells in liver regeneration are unclear, and the trigger that initiates hepatocyte proliferation is unknown. We aimed to identify the key factors released by activated platelets that induce liver sinusoidal endothelial cells to produce interleukin-6 (IL-6), a cytokine implicated in the early phase of liver regeneration. We characterized the releasate of activated platelets inducing the in vitro production of IL-6 by mouse liver sinusoidal endothelial cells and observed that the stimulating factor was a thermolabile protein. Following gel filtration, a single fraction of activated platelet releasate induced a maximal IL-6 secretion by liver sinusoidal endothelial cells (90.2 ± 13.9 versus control with buffer, 9.0 ± 0.8 pg/mL, p < 0.05). Mass spectroscopy analysis of this fraction, followed by in silico processing, resulted in a reduced list of 18 candidates. Several proteins from the list were tested, and only recombinant transforming growth factor β1 (TGF-β1) resulted in an increased IL-6 production up to 242.7 ± 30.5 pg/mL, which was comparable to non-fractionated platelet releasate effect. Using neutralizing anti-TGF-β1 antibody or a TGF-β1 receptor inhibitor, IL-6 production by liver sinusoidal endothelial cells was dramatically reduced. These results support a role of platelet TGF-β1 β1 in the priming phase of liver regeneration.

Genetic Interleukin 6 Signaling Deficiency Attenuates Cardiovascular Risk in Clonal Hematopoiesis

BACKGROUND

Clonal hematopoiesis of indeterminate potential (CHIP) refers to clonal expansion of hematopoietic stem cells attributable to acquired leukemic mutations in genes such as DNMT3A or TET2. In humans, CHIP associates with prevalent myocardial infarction. In mice, CHIP accelerates atherosclerosis and increases IL-6/IL-1β expression, raising the hypothesis that IL-6 pathway antagonism in CHIP carriers would decrease cardiovascular disease (CVD) risk.

METHODS

We analyzed exome sequences from 35 416 individuals in the UK Biobank without prevalent CVD, to identify participants with DNMT3A or TET2 CHIP. We used the IL6R p.Asp358Ala coding mutation as a genetic proxy for IL-6 inhibition. We tested the association of CHIP status with incident CVD events (myocardial infarction, coronary revascularization, stroke, or death), and whether it was modified by IL6R p.Asp358Ala.

RESULTS

We identified 1079 (3.0%) individuals with CHIP, including 432 (1.2%) with large clones (allele fraction >10%). During 6.9-year median follow-up, CHIP associated with increased incident CVD event risk (hazard ratio, 1.27 [95% CI, 1.04-1.56], P=0.019), with greater risk from large CHIP clones (hazard ratio, 1.59 [95% CI, 1.21-2.09], P<0.001). IL6R p.Asp358Ala attenuated CVD event risk among participants with large CHIP clones (hazard ratio, 0.46 [95% CI, 0.29-0.73], P<0.001) but not in individuals without CHIP (hazard ratio, 0.95 [95% CI, 0.89-1.01], P=0.08; Pinteraction=0.003). In 9951 independent participants, the association of CHIP status with myocardial infarction similarly varied by IL6R p.Asp358Ala (Pinteraction=0.036).

CONCLUSIONS

CHIP is associated with increased risk of incident CVD. Among carriers of large CHIP clones, genetically reduced IL-6 signaling abrogated this risk.

Modulation of the interleukin-6 signalling pathway and incidence rates of atherosclerotic events and all-cause mortality: analyses from the Canakinumab Anti-Inflammatory Thrombosis Outcomes Study (CANTOS)

Aims

Canakinumab, a monoclonal antibody targeting interleukin (IL)-1β, reduces rates of recurrent cardiovascular events without lowering lipids. It is uncertain, however, to what extent these beneficial cardiovascular outcomes are mediated through interleukin-6 (IL-6) signalling, an issue with substantial pathophysiologic consequences and therapeutic implications.

Methods and results

A total of 4833 stable atherosclerosis patients in the Canakinumab Anti-Inflammatory Thrombosis Outcomes Study (CANTOS) had IL-6 levels measured before randomization and after treatment with placebo or one of three doses of canakinumab (50 mg, 150 mg, or 300 mg) given subcutaneously once every 3 months. Participants were followed for up to 5 years (median follow-up 3.7 years). Compared with those allocated to placebo, CANTOS participants receiving canakinumab who achieved on-treatment IL-6 levels below the study median value of 1.65 ng/L experienced a 32% reduction in major adverse cardiovascular events [MACE, multivariable adjusted hazard ratio (HRadj) 0.68, 95% confidence interval (CI) 0.56-0.82; P < 0.0001], a 30% reduction in MACE plus the additional endpoint of hospitalization for unstable angina requiring urgent revascularization (MACE+, HRadj 0.70, 95% CI 0.59-0.84; P < 0.0001), a 52% reduction in cardiovascular mortality (HRadj 0.48, 95% CI 0.34-0.68; P < 0.0001), and a 48% reduction in all-cause mortality (HRadj 0.52, 95% CI 0.40-0.68; P < 0.0001) with prolonged treatment. In contrast, those with on-treatment IL-6 levels equal to or above 1.65 ng/L after taking the first dose of canakinumab had no significant benefit for any of these endpoints. These differential findings based on the magnitude of IL-6 response were seen in analyses alternatively based on tertiles of on-treatment IL-6 levels, and in analyses using a statistical inference approach to estimate the effect of treatment among individuals who would achieve a targeted IL-6 level.

Conclusion

CANTOS provides proof of concept evidence in humans that modulation of the IL-6 signalling pathway, at least with canakinumab, associates with reduced cardiovascular event rates, independent of lipid lowering.

Clinical trial registration

ClinicalTrials.gov NCT01327846.

Anticytokine Immune Therapy and Atherothrombotic Cardiovascular Risk

Accumulating observations in humans and animals indicate that inflammation plays a key role in atherosclerosis development and subsequent complications. Moreover, the use of loss- or gain-of-function genetically modified, atherosclerosis-prone mice has provided strong experimental evidence for a causal role of innate and adaptive immunity in atherosclerosis and has revealed the pathogenic activity of proinflammatory cytokines, including TNF (tumor necrosis factor)-α, IL (interleukin)-1β, IL-6, and IL-18, and the atheroprotective effect of anti-inflammatory cytokines, including IL-10 and TGF-β. For the past 15 years, treatments using monoclonal antibodies specifically targeting cytokines, commonly referred as biological therapies, have transformed the treatment of chronic inflammatory diseases, such as rheumatoid arthritis or psoriasis, both conditions associated with increased cardiovascular risk. Analyzing the impact of anticytokine therapies on the cardiovascular outcomes of patients with chronic inflammatory diseases provides insight into the clinical relevance of experimental data on the role of inflammation in atherothrombotic cardiovascular diseases. CANTOS (Canakinumab Antiinflammatory Thrombosis Outcome Study) provided the first evidence that targeting inflammation in humans with atherosclerosis could improve clinical outcomes. Treatment with the anti-IL-1β antibody canakinumab significantly reduced recurrent cardiovascular events in individuals with stable coronary artery disease well-treated with standard-of-care measures. Other clinical studies support the protective effects of treatment with anti-TNF-α and anti-IL-6 receptor monoclonal antibodies on cardiovascular risk. Blockade of the IL-23/IL-17 axis, however, warrants caution as a cardiovascular intervention. Targeting this pathway has improved psoriasis but may augment cardiovascular risk in certain patients. Thus, careful consideration of the cardiovascular risk profile may influence the choice of the most appropriate treatment for patients with chronic inflammatory diseases.Visual Overview: An online visual overview is available for this article.

Caspase-1 induces smooth muscle cell growth in hypoxia-induced pulmonary hypertension

Lung diseases with hypoxia are complicated by pulmonary hypertension, leading to heart failure and death. No pharmacological treatment exists. Increased proinflammatory cytokines are found in hypoxic patients, suggesting an inflammatory pathogenesis. Caspase-1, the effector of the inflammasome, mediates inflammation through activation of the proinflammatory cytokines interleukin (IL)-18 and IL-1β. Here, we investigate inflammasome-related mechanisms that can trigger hypoxia-induced pulmonary hypertension. Our aim was to examine whether caspase-1 induces development of hypoxia-related pulmonary hypertension and is a suitable target for therapy. Wild-type (WT) and caspase-1^-/- mice were exposed to 10% oxygen for 14 days. Hypoxic caspase-1^-/- mice showed lower pressure and reduced muscularization in pulmonary arteries, as well as reduced right ventricular remodeling compared with WT. Smooth muscle cell (SMC) proliferation was reduced in caspase-1-deficient pulmonary arteries and in WT arteries treated with a caspase-1 inhibitor. Impaired inflammation was shown in hypoxic caspase-1^-/- mice by abolished pulmonary influx of immune cells and lower levels of IL-18, IL-1β, and IL-6, which were also reduced in the medium surrounding caspase-1 abrogated pulmonary arteries. By adding IL-18 or IL-1β to caspase-1-deficient pulmonary arteries, SMC proliferation was retained. Furthermore, inhibition of both IL-6 and phosphorylated STAT3 reduced proliferation of SMC in vitro, indicating IL-18, IL-6, and STAT3 as downstream mediators of caspase-1-induced SMC proliferation in pulmonary arteries. Caspase-1 induces SMC proliferation in pulmonary arteries through the caspase-1/IL-18/IL-6/STAT3 pathway, leading to pulmonary hypertension in mice exposed to hypoxia. We propose that caspase-1 inhibition is a potential target for treatment of pulmonary hypertension.

Anti-Atherogenic Effects of Vaspin on Human Aortic Smooth Muscle Cell/Macrophage Responses and Hyperlipidemic Mouse Plaque Phenotype

Vaspin (visceral adipose tissue-derived serine protease inhibitor) was recently identified as a novel adipocytokine with insulin-sensitizing effects. Serum vaspin levels are reported either increased or decreased in patients with coronary artery disease. Our translational research was performed to evaluate the expression of vaspin in human coronary atherosclerotic lesions, and its effects on atherogenic responses in human macrophages and human aortic smooth muscle cells (HASMC), as well as aortic atherosclerotic lesion development in spontaneously hyperlipidemic Apoe−/− mice, an animal model of atherosclerosis. Vaspin was expressed at high levels in macrophages/vascular smooth muscle cells (VSMCs) within human coronary atheromatous plaques. Vaspin significantly suppressed inflammatory phenotypes with nuclear factor κB down-regulation in human macrophages. Vaspin significantly suppressed oxidized low-density lipoprotein-induced foam cell formation with CD36 and acyl-coenzyme A: cholesterol acyltransferase-1 down-regulation and ATP-binding cassette transporters A1 and G1, and scavenger receptor class B type 1 up-regulation in human macrophages. Vaspin significantly suppressed angiotensin II-induced migration and proliferation with ERK1/2 and JNK down-regulation, and increased collagen production with phosphoinositide 3-kinase and Akt up-regulation in HASMCs. Chronic infusion of vaspin into Apoe−/− mice significantly suppressed the development of aortic atherosclerotic lesions, with significant reductions of intraplaque inflammation and the macrophage/VSMC ratio, a marker of plaque instability. Our study indicates that vaspin prevents atherosclerotic plaque formation and instability, and may serve as a novel therapeutic target in atherosclerotic cardiovascular diseases.

Cellular and Oxidative Mechanisms Associated with Interleukin-6 Signaling in the Vasculature

Reactive oxygen species, particularly superoxide, promote endothelial dysfunction and alterations in vascular structure. It is increasingly recognized that inflammatory cytokines, such as interleukin-6 (IL-6), contribute to endothelial dysfunction and vascular hypertrophy and fibrosis. IL-6 is increased in a number of cardiovascular diseases, including hypertension. IL-6 is also associated with a higher incidence of future cardiovascular events and all-cause mortality. Both immune and vascular cells produce IL-6 in response to a number of stimuli, such as angiotensin II. The vasculature is responsive to IL-6 produced from vascular and non-vascular sources via classical IL-6 signaling involving a membrane-bound IL-6 receptor (IL-6R) and membrane-bound gp130 via Jak/STAT as well as SHP2-dependent signaling pathways. IL-6 signaling is unique because it can also occur via a soluble IL-6 receptor (sIL-6R) which allows for IL-6 signaling in tissues that do not normally express IL-6R through a process referred to as IL-6 trans-signaling. IL-6 signaling mediates a vast array of effects in the vascular wall, including endothelial activation, vascular permeability, immune cell recruitment, endothelial dysfunction, as well as vascular hypertrophy and fibrosis. Many of the effects of IL-6 on vascular function and structure are representative of loss or reductions in nitric oxide (NO) bioavailability. IL-6 has direct effects on endothelial nitric oxide synthase activity and expression as well as increasing vascular superoxide, which rapidly inactivates NO thereby limiting NO bioavailability. The goal of this review is to highlight both the cellular and oxidative mechanisms associated with IL-6-signaling in the vascular wall in general, in hypertension, and in response to angiotensin II.

The influence of low-grade inflammation on platelets in patients with stable coronary artery disease

Inflammation is likely to be involved in all stages of atherosclerosis. Numerous inflammatory biomarkers are currently being studied, and even subtle increases in inflammatory biomarkers have been associated with increased risk of cardiovascular events in patients with coronary artery disease (CAD). Low-grade inflammation may influence both platelet production and platelet activation potentially leading to enhanced platelet aggregation. Thrombopoietin is considered the primary regulator of platelet production, but it likely acts in conjunction with numerous cytokines, of which many have altered levels in CAD. Previous studies have shown that high-sensitive C-reactive protein (CRP) independently predicts increased platelet aggregation in stable CAD patients. Increased levels of CRP, fibrinogen, interleukin-6, stromal cell-derived factor-1, CXC motif ligand 16, macrophage migration inhibitory factor, RANTES, calprotectin, and copeptin have been associated with increased risk of cardiovascular events in CAD patients. Additionally, some of these inflammatory markers have been associated with enhanced platelet activation and aggregation. However, CRP and other inflammatory markers provide only limited additional predictive value to classical risk factors such as smoking, blood pressure, and cholesterol levels. Existing data do not clarify whether inflammation simply accompanies CAD and increased production and aggregation of platelets, or whether a causal relationship exists. In this review, we provide a comprehensive overview of inflammatory markers in stable CAD with particular emphasis on platelet production, activation, and aggregation in CAD patients.

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.

Schisandrin B inhibits LPS-induced inflammatory response in human umbilical vein endothelial cells by activating Nrf2

Schisandrin B (SchB), an active ingredient extracted from Schisandra chinensis (Turcz.) Baill, has been known to have anti-oxidant and anti-inflammatory activities. In this study, we investigated the anti-inflammatory effects and mechanism of SchB in LPS-stimulated human umbilical vein endothelial cells (HUVECs). The effects of SchB on VCAM-1, ICAM-1, NF-κB and Nrf2 expression were detected by western blot analysis. The effects of SchB on TNF-α and IL-8 production were detected by ELISA. The results showed that SchB strongly suppressed the production of TNF-α and IL-8 in HUVECs stimulated with LPS. SchB also inhibited LPS-induced VCAM-1 and ICAM-1 expression. Furthermore, SchB blocked the activation of NF-κB induced by LPS. In addition, SchB increased the expression of Nrf2 and HO-1 in a concentration-dependent manner. And the inhibition of TNF-α and IL-8 production by SchB was blocked by transfection with Nrf2 siRNA. Our findings showed that SchB inhibited LPS-induced inflammation in HUVECs by activating Nrf2 signaling pathway.

Proinflammatory cytokines remain elevated despite long-term remission in Cushing's disease: a prospective study

CONTEXT

Inflammation contributes to the development of metabolic and cardiovascular disease. Cushing's disease (CD), a state of chronic glucocorticoid (GC) excess characterized by visceral obesity and insulin resistance, may be associated with increased systemic inflammation. Cardiovascular mortality in CD remains elevated even after successful remission. It is unclear whether a chronic low-grade inflammatory state persists even after remission of CD, which may account for the increased CVD mortality.

PURPOSE

(1) To assess circulating proinflammatory cytokines in patients with active CD and BMI-matched controls; (2) to prospectively follow plasma cytokine concentrations in patients with CD before and after surgical remission; and (3) to assess whether plasma cytokine concentrations correlate with adipose tissue distribution and ectopic lipid content in liver and muscle.

METHODS

Plasma cytokines from prospectively enrolled patients with CD (N = 31) were quantified during active disease (v1) vs controls (N = 18) and 19·5 ± 12·9 months after surgical remission (v2). Fasting plasma IL-6, IL-1β, TNF-α, IL-8, IL-17 and IL-10 were quantified using a multiplex assay. Total and regional fat masses were measured by whole-body MRI.

RESULTS

Circulating IL-6 and IL-1β were elevated in patients with active CD vs controls (P < 0·05) and remained elevated in CD after surgical remission, despite decreases in BMI (P < 0·001), HOMA-IR (P < 0·001), and visceral, hepatic and intermuscular fat (P < 0·001, <0·001 and 0·03, respectively).

CONCLUSIONS

Despite long-term remission and improvements in fat distribution and insulin sensitivity, patients with CD may suffer from a state of chronic low-grade inflammation, which could contribute to increased cardiovascular mortality.

S-form LPS induces leukocyte adhesion to human vascular endothelial cells as potent as IL-1: lipid A precursor Ia antagonizes induction of adhesion by LPS

The expression of adhesion molecules on human vascular endothelial cells (EC) during infection or inflammation is necessary to initiate migration of leukocytes to the disease focus. Various bacteria or endotoxins (lipopolysaccharide, LPS) might exert differential capacity to induce adhesion molecules in endothelial cells. Therefore, we first investigated induction of adhesion by bacteria. Heat-killed Gram-negative bacteria (Escherichia coli) induced adhesion, whereas the Gram-positive Bacillus subtilis and Staphylococcus epidermidis or Mycobacterium tuberculosis did not, indicating the significance of LPS for this activation. Purified S-form LPS stimulated endothelial cells to express adhesion molecules for polymorphonuclear cells (PMN) or lymphocytes in a dose-dependent fashion. S-form LPS, containing an 0-specific chain, induced a maximal level of adhesion, comparable to adhesion induced by interleukin-1 (IL-1). We obtained the same results in cell ELISA with anti-ICAM-1 antibody (84H10). R-form LPS and free lipid A, lacking an O-specific chain also stimulated adhesion, however, to a lower degree (39-60%). Synthetic lipid A precursor Ia (compound 406) or another LPS-antagonist (non-toxic Rhodobacter capsulatus LPS) did not trigger endothelial cells to express adhesion molecules. These antagonists specifically inhibited LPS- or free lipid A-, but not IL-1-induced adhesion. These results suggest that lipid A is the active structure of LPS necessary for induction of adhesion, that the oligosaccharide portion is important for the capacity of LPS to stimulate adhesion, and that activation of adhesion to endothelial cells by LPS requires specific LPS binding sites.

Macrophage migration inhibitory factor: a potential therapeutic target for rheumatoid arthritis

Macrophage migration inhibitory factor (MIF) is originally identified in the culture medium of activated T lymphocytes as a soluble factor that inhibits the random migration of macrophages. MIF is now recognized as a multipotent cytokine involved in the regulation of immune and inf lammatory responses. In rheumatoid arthritis (RA), MIF promotes inf lammatory responses by inducing proinflammatory cytokines and tissue-degrading molecules, promoting the proliferation and survival of synovial fibroblasts, stimulating neutrophil chemotaxis, and regulating angiogenesis and osteoclast differentiation. Expression of MIF in synovial tissue and synovial fluid levels of MIF are elevated in RA patients. Specifically, MIF levels correlate with RA disease activity and high levels are associated with bone erosion. In animal models of RA, the genetic and therapeutic inhibition of MIF has been shown to control inflammation and bone destruction. Based on the role of MIF in RA pathogenesis, small molecular inhibitors targeting it or its receptor pathways could provide a new therapeutic option for RA patients.

Direct inhibition, but indirect sensitization of pacemaker activity to sympathetic tone by the interaction of endotoxin with HCN-channels

In critically ill patients regulation of heart-rate is often severely disturbed. Interaction of bacterial endotoxin (lipopolysaccharide, LPS) with hyperpolarization-activated cyclic nucleotide-gated cation-(HCN)-channels may interfere with heart-rate regulation. This study analyzes the effect of LPS, the HCN-channel blocker ivabradine or Ca(2+) -channel blockers (nifedipine, verapamil) on pacemaking in spontaneously beating neonatal rat cardiomyocytes (CM) in vitro. In vivo, the effect of LPS on the heart-rate of adult CD1-mice with and without autonomic blockade is analyzed telemetrically. LPS (100 ng/mL) and ivabradine (5 μg/mL) reduced the beating-rate of CM by 20.1% and 24.6%, respectively. Coincubation of CM with both, LPS and ivabradine, did not further reduce the beating-rate, indicating interaction of both compounds with HCN-channels, while coincubation with Ca(2+) -channel blockers and LPS caused additive beating-rate reduction. In CD1-mice (containing an active autonomic-nervous-system), injection of LPS (0.4 mg/kg) expectedly resulted in increased heart-rate. However, if the autonomic nervous system was blocked by propranolol and atropine, in line with the in vitro data, LPS induced a significant reduction of heart-rate, which was not additive to ivabradine. The in vivo and in vitro results indicate that LPS interacts with HCN-channels of cardiomyocytes. Thus, LPS indirectly sensitizes HCN-channels for sympathetic activation (tachycardic-effect), and in parallel directly inhibits channel activity (bradycardic-effect). Both effects may contribute to the detrimental effects of septic cardiomyopathy and septic autonomic dysfunction.

The role of endothelial cell adhesion molecules in the development of atherosclerosis

The vascular endothelium serves as a dynamic interface between circulating blood elements and the interstitial tissues. As such, it communicates to cells within the vessel wall as well as to the surrounding tissue, sensing its environment and responding accordingly. The vasculature must maintain a delicate balance when initiating a functional response by producing both proinflammatory and antiinflammatory mediators, vasoconstrictors and vasodilators, growth stimulators and inhibitors, and prothrombogenic and antithrombogenic factors. Any response to injurious agents could lead to pathology. Confounding this complex interplay is the fact that the very response to injury that may have developed to undo the damage may itself be even more deleterious. One response to injury by the endothelium is the new or increased expression of surface receptors for immune elements. In atherosclerosis, the adhesion of monocytes (and T cells) to the endothelium is a key event triggered by some form of insult. Subsequent events include monocytic infiltration of the vessel wall, alterations in lipid metabolism, and the activation of these cells into foam cells. The presence of large numbers of foam cells in the intima may produce a high concentration of cytokines and growth factors within a localized area, extracellular matrix perturbations, smooth muscle cell proliferation, and ultimately platelet aggregation at the site of stenosis. Endothelial cells themselves will not only elaborate factors after the initial injury to the vessel wall but also in response to the factors produced by foam cells within the plaque. These endothelial cell factors include MCP-1, a chemoattractant for monocytes (179,180), IL-1 (63,64), IL-6 (interleukin-6) (65-67), IL-8 (interleukin 8) (181), and PDGF, a potent smooth muscle mitogen (4,72) (Fig. 3). Endothelial cells will propagate an inflammatory response long after the initial insult to the arterial vessel. A chronic cycle of endothelial cell activation and leukocyte infiltration is constitutively activated. Thus, all of the cellular elements of the vessel wall, as well as the atherosclerotic plaque itself, elaborate cytokines and growth factors that amplify and propagate the pathological process.

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.

A role for innate immunity in the development of hypertension

Clinically, angiotensin II (Ang II) has been implicated in some forms of hypertension and linked to vascular injury. Experimentally, chronic Ang II infusion leads to an increase in blood pressure, resulting in impaired endothelial function and vascular hypertrophy. Ang II also upregulates the activity and expression of a number of inflammatory molecules, including nuclear factor kappa B (NFκB) and pro-inflammatory cytokines, such as interleukin-6 (IL-6). More recently, it has been reported that Ang II is associated with upregulation of toll-like receptor TLR expression, specifically TLR4. Classical TLR4 signaling is mediated in large part by the effector protein myeloid differentiation factor 88 (MyD88), with resultant activation of NFκB, a transcription factor that promotes expression of a number of inflammatory gene products, including IL-6. A role for IL-6 has been previously implicated in the vascular dysfunction associated with Ang II-dependent hypertension. It is not known whether the MyD88 signaling pathway represents a cellular mechanism by which Ang II promotes endothelial dysfunction via NFκB activation and increases in IL-6. Taken together, we propose to mechanistically elucidate the role of innate immune signaling in Ang II-dependent hypertension. We hypothesize MyD88-deficiency will prevent the activation and transcription of NFκB-related gene products, including IL-6, thereby limiting Ang II-dependent hypertension and vascular complications.

Andes-virus-induced cytokine storm is partially suppressed by ribavirin

BACKGROUND

Microbe-induced over-activation of cytokines, especially tumour necrosis factor (TNF)-α, is key to the pathogenesis of hantavirus infection leading to severe inflammation with high mortality rate. Although ribavirin showed promise in inhibiting viral replication in vitro, its clinical efficacy remains controversial.

METHODS

Various concentrations of ribavirin were used to determine its effect on cytokine activation in our infectious model system.

RESULTS

Ribavirin decreased the virus load and dose-dependently inhibited the accumulation of RANTES messenger RNA in Andes-virus (ANDV)-infected human endothelial cells, but failed to suppress TNF-α-induced activation of RANTES and interleukin-6 in ANDV-inoculated cultures. This report also shows, for the first time, that the deleterious over-stimulation by TNF-α is mediated by nuclear factor-κB, and describes the effect of ribavirin on cytokine production following ANDV infection.

CONCLUSIONS

Although highly effective in preventing ANDV replication and suppressing activation of select inflammatory mediators, the therapeutic efficacy of ribavirin is limited due to its inability to fully inhibit cytokine outburst triggered by hantavirus infection.

Cytokine release from human leukocytes exposed to silorane- and methacrylate-based dental materials

OBJECTIVES

Silorane-based dental monomers contain an epoxy functional group. Less is known about the toxicological and inflammatory potential of silorane-based composites. Therefore we compared the release of 24 cytokines from human leukocytes after incubation with silorane-based Filtek™ Silorane (Silo) and methacrylate-based TetricEvo Flow® (TC).

METHODS

Leukocytes from nine healthy test persons (P) were incubated with Silo or TC for up to 72h. All 24h cytokines were quantified with a magnetic bead assay.

RESULTS

Silo stimulates the leukocytes to higher release of cytokines when compared to TC. 72h after beginning the experiment, leukocytes from P6 incubated with Silo secreted more than an 18-fold amount of interleukin (IL)-6 when compared with leukocytes incubated with TC (771.8 vs 42.1pg/ml). Only leukocytes from P8 incubated with Silo release up to 14.4pg/ml IL-2 after 72h.

SIGNIFICANCE

The significantly higher induction of cytokines with Silo in comparison to TC is test person independent. This indicates a higher sensitization potential for Silo. Because of the cytokine release pattern (especially the release of T-cell dependent IL-2) from leukocytes from P8 after incubation with Silo it is likely that P8 can develop an allergic Type IV sensitization to Silo. Therefore the cytokine release assay is a helpful tool for providing information about possible immunological reactions to dental resins in individual cases as well as for a general risk assessment and comparison between different dental materials.

Neutralizing IL-6 reduces human arterial allograft rejection by allowing emergence of CD161+ CD4+ regulatory T cells

Perioperative injuries to an allograft exacerbate graft rejection, which in humans is primarily mediated by effector memory T cells. IL-6 transcripts in human coronary artery segments rapidly increase posttransplantation into immunodeficient mouse hosts compared with those of pretransplant specimens and fall dramatically by 30 d. Adoptive transfer of human PBMCs allogeneic to the artery 2 d postoperatively results in T cell infiltrates and intimal expansion 4 wk later. Ab neutralization of human IL-6 reduces the magnitude of intimal expansion and total T cell infiltration but increases the relative expression of CD161 while decreasing other Th17 markers. Coculture of MHC class II-expressing human endothelial cells (ECs) with allogeneic CD4(+) memory T cells results in T cell activation and EC secretion of IL-6. Neutralizing IL-6 in primary allogeneic T cell-EC cocultures results in enhanced T cell proliferation of CD161(+) CD4(+) T cells, reduces total T cell proliferation upon restimulation in secondary cultures (an effect dependent on CD161(+) T cells), increases expression of FOXP3 in CD161(+) T cells, and generates T cells that suppress proliferation of freshly isolated T cells. These data suggest that IL-6 released from injured allograft vessels enhances allogeneic T cell infiltration and intimal expansion in a model of human allograft rejection by inhibiting an increase in CD161(+) regulatory T cells.

Statins potently reduce the cytokine-mediated IL-6 release in SMC/MNC cocultures

Inflammatory pathways are involved in the development of atherosclerosis. Interaction of vessel wall cells and invading monocytes by cytokines may trigger local inflammatory processes. 3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) are standard medications used in cardiovascular diseases. They are thought to have anti-inflammatory capacities, in addition to their lipid-lowering effects. We investigated the anti-inflammatory effect of statins in the cytokine-mediated-interaction-model of human vascular smooth muscle cells (SMC) and human mononuclear cells (MNC). In this atherosclerosis-related inflammatory model LPS (lipopolysaccharide, endotoxin), as well as high mobility group box 1 stimulation resulted in synergistic (i.e. over-additive) IL-6 (interleukin-6) production as measured in ELISA. Recombinant IL-1, tumour necrosis factor-α and IL-6 mediated the synergistic IL-6 production. The standard anti-inflammatory drugs aspirin and indomethacin (Indo) reduced the synergistic IL-6 production by 60%. Simvastatin, atorvastatin, fluvastatin or pravastatin reduced the IL-6 production by 53%, 50%, 64% and 60%, respectively. The inhibition by the statins was dose dependent. Combination of statins with aspirin and/or Indo resulted in complete inhibition of the synergistic IL-6 production. The same inhibitors blocked STAT3 phosphorylation, providing evidence for an autocrine role of IL-6 in the synergism. MNC from volunteers after 5 day aspirin or simvastatin administration showed no decreased IL-6 production, probably due to drug removal during MNC isolation. Taken together, the data show that anti-inflammatory functions (here shown for statins) can be sensitively and reproducibly determined in this novel SMC/MNC coculture model. These data implicate that statins have the capacity to affect atherosclerosis by regulating cytokine-mediated innate inflammatory pathways in the vessel wall.

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.

Integrin beta4 attenuates SHP-2 and MAPK signaling and reduces human lung endothelial inflammatory responses

We previously identified the marked upregulation of integrin beta4 in human lung endothelial cells (EC) treated with simvastatin, an HMG coA-reductase inhibitor with vascular-protective and anti-inflammatory properties in murine models of acute lung injury (ALI). We now investigate the role of integrin beta4 as a novel mediator of vascular inflammatory responses with a focus on mitogen-activated protein kinases (MAPK) signaling and the downstream expression of the inflammatory cytokines (IL-6 and IL-8) essential for the full elaboration of inflammatory lung injury. Silencing of integrin beta4 (siITGB4) in human lung EC resulted in significant increases in both basal and LPS-induced phosphorylation of ERK 1/2, JNK, and p38 MAPK, consistent with robust integrin beta4 regulation of MAPK activation. In addition, siITB4 increased both basal and LPS-induced expression of IL-6 and IL-8 mRNA and protein secretion into the media. We next observed that integrin beta4 silencing increased basal and LPS-induced phosphorylation of SHP-2, a protein tyrosine phosphatase known to modulate MAPK signaling. In contrast, inhibition of SHP-2 enzymatic activity (sodium stibogluconate) abrogated the increased ERK phosphorylation associated with integrin beta4 silencing in LPS-treated EC and attenuated the increases in levels of IL-6 and IL-8 in integrin-beta4-silenced EC. These findings highlight a novel negative regulatory role for integrin beta4 in EC inflammatory responses involving SHP-2-mediated MAPK signaling. Upregulation of integrin beta4 may represent an important element of the anti-inflammatory and vascular-protective properties of statins and provides a novel strategy to limit inflammatory vascular syndromes.

Intragraft gene expression profile associated with the induction of tolerance by allochimeric MHC I in the rat heart transplantation model

The MHC class I allochimeric protein containing donor-type epitopes on recipient-type heavy chains induces indefinite survival of heterotopic cardiac allografts in rats. We analyzed gene expression profile of heart allograft tissue. Mutated peptide [alpha1h1/u]-RT1.Aa that contains donor-type (Wistar Furth, WF; RT1u) immunogenic epitopes displayed on recipient-type (ACI, RT1a) was delivered into ACI recipients of WF hearts at the time of transplantation in addition to a 3 days course of oral cyclosporine. Microarray analysis was performed using Affymetrix Rat 230 2.0 Microarray. Allochimeric molecule treatment caused upregulation of genes involved in structural integrity of heart muscle, downregulation of IL-1beta a key modulator of the immune response, and downregulation of partitioning defective six homolog gamma PAR6, which is involved in T cell polarity, motility, and ability to scan dendritic cells (DC). These indicate that the immunosuppressive function of allochimeric molecule and/or the establishment of allograft tolerance depend on the induction of genes responsible for the heart tissue integrity, the suppression of cytokine pathway(s), and possibly the impairment of T cells mobility and their DC scanning ability. These novel findings may have important clinical implications for inhibition of chronic rejection in transplant recipients.

S100A12 mediates aortic wall remodeling and aortic aneurysm

RATIONALE

S100A12 is a small calcium binding protein that is a ligand of RAGE (receptor for advanced glycation end products). RAGE has been extensively implicated in inflammatory states such as atherosclerosis, but the role of S100A12 as its ligand is less clear.

OBJECTIVE

To test the role of S100A12 in vascular inflammation, we generated and analyzed mice expressing human S100A12 in vascular smooth muscle under control of the smooth muscle 22alpha promoter because S100A12 is not present in mice.

METHODS AND RESULTS

Transgenic mice displayed pathological vascular remodeling with aberrant thickening of the aortic media, disarray of elastic fibers, and increased collagen deposition, together with increased latent matrix metalloproteinase-2 protein and reduction in smooth muscle stress fibers leading to a progressive dilatation of the aorta. In primary aortic smooth muscle cell cultures, we found that S100A12 mediates increased interleukin-6 production, activation of transforming growth factor beta pathways and increased metabolic activity with enhanced oxidative stress. To correlate our findings to human aortic aneurysmal disease, we examined S100A12 expression in aortic tissue from patients with thoracic aortic aneurysm and found increased S100A12 expression in vascular smooth muscle cells.

CONCLUSIONS

S100A12 expression is sufficient to activate pathogenic pathways through the modulation of oxidative stress, inflammation and vascular remodeling in vivo.