NLRP3 Inflammasome Involvement in Heart, Liver, and Lung Diseases-A Lesson from Cytokine Storm Syndrome

Inflammation and inflammasomes have been proposed as important regulators of the host-microorganism interaction, playing a key role in morbidity and mortality due to the coronavirus disease 2019 (COVID-19) in subjects with chronic conditions and compromised immune system. The inflammasome consists of a multiprotein complex that finely regulates the activation of caspase-1 and the production and secretion of potent pro-inflammatory cytokines such as IL-1β and IL-18. The pyrin containing NOD (nucleotide-binding oligomerization domain) like receptor (NLRP) is a family of intracellular receptors, sensing patterns associated to pathogens or danger signals and NLRP3 inflammasome is the most deeply analyzed for its involvement in the innate and adaptive immune system as well as its contribution to several autoinflammatory and autoimmune diseases. It is highly expressed in leukocytes and up-regulated in sentinel cells upon inflammatory stimuli. NLRP3 expression has also been reported in B and T lymphocytes, in epithelial cells of oral and genital mucosa, in specific parenchymal cells as cardiomyocytes, and keratinocytes, and chondrocytes. It is well known that a dysregulated activation of the inflammasome is involved in the pathogenesis of different disorders that share the common red line of inflammation in their pathogenetic fingerprint. Here, we review the potential roles of the NLRP3 inflammasome in cardiovascular events, liver damage, pulmonary diseases, and in that wide range of systemic inflammatory syndromes named as a cytokine storm.

Identification of potential diagnostic biomarkers of atherosclerosis based on bioinformatics strategy

BACKGROUND

Atherosclerosis is the main pathological change in atherosclerotic cardiovascular disease, and its underlying mechanisms are not well understood. The aim of this study was to explore the hub genes involved in atherosclerosis and their potential mechanisms through bioinformatics analysis.

METHODS

Three microarray datasets from Gene Expression Omnibus (GEO) identified robust differentially expressed genes (DEGs) by robust rank aggregation (RRA). We performed connectivity map (CMap) analysis and functional enrichment analysis on robust DEGs and constructed a protein‒protein interaction (PPI) network using the STRING database to identify the hub gene using 12 algorithms of cytoHubba in Cytoscape. Receiver operating characteristic (ROC) analysis was used to assess the diagnostic potency of the hub genes.The CIBERSORT algorithm was used to perform immunocyte infiltration analysis and explore the association between the identified biomarkers and infiltrating immunocytes using Spearman's rank correlation analysis in R software. Finally, we evaluated the expression of the hub gene in foam cells.

RESULTS

A total of 155 robust DEGs were screened by RRA and were revealed to be mainly associated with cytokines and chemokines by functional enrichment analysis. CD52 and IL1RN were identified as hub genes and were validated in the GSE40231 dataset. Immunocyte infiltration analysis showed that CD52 was positively correlated with gamma delta T cells, M1 macrophages and CD4 memory resting T cells, while IL1RN was positively correlated with monocytes and activated mast cells. RT-qPCR results indicate that CD52 and IL1RN were highly expressed in foam cells, in agreement with bioinformatics analysis.

CONCLUSIONS

​This study has established that CD52 and IL1RN may play a key role in the occurrence and development of atherosclerosis, which opens new lines of thought for further research on the pathogenesis of atherosclerosis.

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.

The lipid paradox in neuroprogressive disorders: Causes and consequences

Chronic systemic inflammation is associated with an increased risk of cardiovascular disease in an environment of low low-density lipoprotein (LDL) and low total cholesterol and with the pathophysiology of neuroprogressive disorders. The causes and consequences of this lipid paradox are explored. Circulating activated neutrophils can release inflammatory molecules such as myeloperoxidase and the pro-inflammatory cytokines interleukin-1 beta, interleukin-6 and tumour necrosis factor-alpha. Since activated neutrophils are associated with atherosclerosis and cardiovascular disease and with major depressive disorder, bipolar disorder and schizophrenia, it seems reasonable to hypothesise that the inflammatory molecules released by them may act as mediators of the link between systemic inflammation and the development of atherosclerosis in neuroprogressive disorders. This hypothesis is tested by considering the association at a molecular level of systemic inflammation with increased LDL oxidation; increased small dense LDL levels; increased lipoprotein (a) concentration; secretory phospholipase A₂ activation; cytosolic phospholipase A₂ activation; increased platelet activation; decreased apolipoprotein A1 levels and function; decreased paroxonase-1 activity; hyperhomocysteinaemia; and metabolic endotoxaemia. These molecular mechanisms suggest potential therapeutic targets.

A Variant of IL1B Is Associated with the Risk and Blood Lipid Levels of Myocardial Infarction in Eastern Chinese Individuals

In this study, we determined to interpret the effects of the interleukin (IL)1B gene rs1143634 C/T polymorphism on myocardial infarction (MI) risk. This study, conducted in a Chinese Han population, recruited 369 MI patients and 465 controls. The variant of IL1B gene (rs1143634 C/T polymorphism) was genotyped by PCR-RFLP method. In this study, a significant link was shown between the IL1B rs1143634 C/T polymorphism and MI risk. We found that the IL1B rs1143634 C/T polymorphism enhanced the risk of MI in this population. Subgroup analysis detected that the IL1B rs1143634 C/T polymorphism associated with MI susceptibility in males, smokers, and individuals with diabetes mellitus. In addition, the IL1B rs1143634 C/T polymorphism was related with the levels of blood lipids including low-density lipoprotein (LDL), and total cholesterol (TC). This study uncovers that the IL1B rs1143634 C/T polymorphism may associate with the risk and blood lipid levels of MI in an Eastern Chinese Han population.Abbreviations: MI: myocardial infarction; IL-1: Interleukin-1; SNP: single nucleotide polymorphism; BMI: Body Mass Index; HDL: high-density lipoprotein; TC: total cholesterol; TG: triglyceride; LDL: low-density lipoprotein; PCR: polymerase chain reaction; 95% CI: 95% confidence interval; OR: odds ratio.

Polymorphism of Interleukin-1 Gene Cluster in Polish Patients with Acute Coronary Syndrome

Background and objectives: Some experimental studies demonstrated adverse modulation of atherothrombosis by interleukin-1beta (IL-1b). To assess the relationship between the five most common variants of three polymorphisms of the IL1b gene cluster and the complexity of coronary atherosclerosis expressed in Gensini Score (GS), and the age of onset of the first acute coronary syndrome (ACS), we assessed the patients (pts) hospitalized due to ACS in this aspect. Materials and Methods: 250 individuals were included. The single nucleotide polymorphisms of IL1b gene: transition T/C at -31 position, C/T at -511, and those of IL1 receptor antagonist gene (IL1RN)—variable number of tandem repeats allele 1, 2, 3, or 4—were determined by PCR. GS was calculated from the coronary angiogram performed at the index ACS. The impact of the presence of T or C and allele 1 to 4 at the investigated loci on the mean GS, GS greater than 40, mean age of onset of ACS, and the fraction of pts over 60 years of age at ACS were compared between the five most common genotype variants. Results: The five most common variants were present in 203 pts (81.2%). Patients with pair 22 in ILRN had the lowest rate and those with pair 12 had the highest rate of ACS before 60 years of age (29.4 vs. 67.8%; p = 0.004). GS > 40 entailed an eight-fold increase of risk, as observed when pts with one T allele at locus -31 were compared with carriers of 2 or no T allele at this locus: OR 8.73 [CI95 4.26–70.99] p = 0.04. Conclusion: Interleukin-1 beta is subject to frequent genetic variability and our results show a potential relationship of this polymorphism with the extent of coronary atherosclerosis and age at the first ACS.

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.

Anti-atherosclerotic effects of Lactobacillus plantarum ATCC 14917 in ApoE-/- mice through modulation of proinflammatory cytokines and oxidative stress

Atherosclerosis is a chronic inflammatory disease mediated by monocyte infiltration and cholesterol deposition into the subendothelial area, resulting in foam cell development. Probiotics are live bacteria that are beneficial for health when administered orally in adequate amounts. In this study, 8-week-old atherosclerosis-prone apolipoprotein E-deficient (ApoE^-/-) mice were fed with or without Lactobacillus plantarum ATCC 14917 per day for 12 weeks. Serum was collected to analyse the lipid profile, oxidative status and proinflammatory cytokines. The heart was isolated to quantify the atherosclerotic lesion size in the aortic arch. Quantitative real-time polymerase chain reaction was performed to determine the expression levels of tumour necrosis factor-alpha (TNF-α) and interleukin (IL)-1β in the aorta. The proteins extracted from the aorta were used for Western blot analysis to assess the expression levels of nuclear factor kappa B (NF-κB) and inhibitor of NF-κB (IκBα). The composition of gut microbiota was also examined through high-throughput sequencing. Results showed that the daily consumption of L. plantarum ATCC 14917 had no effect on body weight and lipid profile. L. plantarum ATCC 14917 treatment significantly inhibited atherosclerotic lesion formation. In addition, the oxLDL, MDA, TNF-α and IL-1β levels were significantly reduced, whereas the SOD level was induced in the bacteria + high-fat diet group. Furthermore, the administration of L. plantarum ATCC 14917 significantly attenuated IκBα protein degradation and inhibited the translocation of P65 subunits of NF-κB. L. plantarum ATCC 14917 treatment also modulated the composition of gut microbiota in ApoE^-/- mice. Our findings showed that L. plantarum ATCC 14917 supplementation decreases the progression of atherosclerotic lesion formation by alleviating the inflammatory process and lowering oxidative stress.

Bone Marrow Plasma Cytokine Signature Profiles in Severe Aplastic Anemia

OBJECTIVE

We studied bone marrow plasma (BMP) cytokines in severe aplastic anemia (SAA) patients and healthy volunteers to investigate differences in the cytokine profiles between them and propose a cytokine signature of SAA.

METHODS

A Bio-Plex suspension array system was used to measure 27 analytes in BMP samples from 47 SAA patients and 30 healthy donors.

RESULTS

Compared to healthy people, SAA patients had higher levels of tumor necrosis factor α (TNF-α (TNF-γ (IFN-γ (IFN-β (MIP-1β (MIP-1α (TNF-α (TNF-β (MIP-1β (MIP-1β (MIP-1γ (IFN-α (TNF.

CONCLUSIONS

The current study demonstrated distinct cytokine profiles among untreated SAA patients, recovering SAA (RSAA) patients, and healthy people. The cytokines of RSAA patients showed similar characteristics to those of untreated SAA patients and healthy people, respectively, which may reflect that the immune status of RSAA patients is in different stages of recovery after IST; thus, it may provide an important tool in diagnosing and evaluating or predicting curative effects in clinics.

Rutaecarpine derivative R3 attenuates atherosclerosis via inhibiting NLRP3 inflammasome-related inflammation and modulating cholesterol transport

Atherosclerosis is a chronic disease characterized by lipid deposition and inflammatory response. NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome-facilitated inflammatory responses are crucial in the pathogenesis of atherosclerosis, and thus new therapeutic approaches are emerging that target NLRP3 and inflammation. Here, we explored the anti-atherosclerotic effect and mechanisms of a new rutaecarpine derivative, 5-deoxy-rutaecarpine (R3) in vitro and in vivo. R3 treatment attenuated atherosclerosis development and increased plaque stability in Apoe^-/- mice fed a high-fat diet, and decreased levels of inflammatory mediators, such as interleukin-1β, in the serum of Apoe^-/- mice and in oxidized low-density lipoprotein (ox-LDL)-stimulated murine macrophages. R3 treatment inhibited NLRP3 inflammasome activation in the livers of Apoe^-/- mice and ox-LDL-stimulated murine macrophages by inhibiting NF-κB and MAPK pathways. Additionally, R3 significantly decreased total cholesterol in the serum and livers of Apoe^-/- mice and promoted cholesterol efflux in murine macrophages through upregulating protein expression of ATP-binding cassette subfamily A member 1 and scavenger receptor class B type I/human CD36 and lysosomal integral membrane protein-II analogous-1. Our results demonstrated that R3 prevented atherosclerotic progression via attenuating NLRP3 inflammasome-related inflammation and modulating cholesterol transport.

Polymorphism of Interleukin 1B May Modulate the Risk of Ischemic Stroke in Polish Patients

Background and Objectives: Inflammation plays a crucial role in the pathophysiology of ischemic stroke (IS). Interleukin-1B and interleukin-1 receptor antagonists are key factors in inflammatory processes. Aims: The aims of our study were to evaluate the relationship between genetic variation in interleukin-1B (IL1B) rs1143627 and interleukin-1 receptor antagonist (IL1RN) variable-number-tandem-repeats (VNTR), and overall IS and subtype prevalence rates. Materials and Methods: The analysis included 147 hospitalized Polish patients with IS diagnosed using conventional criteria. The control group consisted of 119 healthy subjects. Genotypes were determined by polymerase chain reaction. Results: A significant association between rs1143627 and stroke was found. The -31C IL1B polymorphism showed an association with overall IS, OR = 2.30 (1.36-3.87) p = 0.020. An association was also detected for LVI (large vessel infarction) subtypes of stroke. After risk factor adjustment (age, diabetes mellitus, dyslipidemia), the C allele was found to be an independent risk factor for LVI, OR = 1.99 (1.05-3.79) p = 0.036. Significant association was not observed between IL1RN alleles and IS. Conclusions: Our results suggest that the C allele of IL1B rs1143627 may be associated with susceptibility to overall IS and LVI subtypes of stroke in the Polish population.

Mid-portion Achilles tendinopathy in runners with metabolic disorders

INTRODUCTION

Running is a very popular modality of physical activity, which may help to lose weight and normalize pathological values of blood parameters in subjects suffering from metabolic disorders. Given that both overuse and metabolic pathologies are responsible for the onset of tendon damage, aim of the present study was to evaluate whether the first group of pathogenetic factors or the latter was more responsible for mid-portion Achilles tendinopathy.

METHOD

Thirty-six and 28 subjects with and without mid-portion Achilles tendinopathy, who were regular runners and started running for metabolic disorders, were enrolled, respectively. Information about body weight and blood parameters at baseline was collected. The characteristics of running practice, dietary habits and anthropometric measures were registered. An ultrasound evaluation of the tendon was performed, and the blood metabolic parameters were evaluated.

RESULTS

The amount of running years and mileage was equivalent in both groups. A similar weight loss was observed; the subjects with mid-portion Achilles tendinopathy showed a worse metabolic profile (Hb1aC%, p = 0.008; total cholesterol, p = 0.04; HDL cholesterol, p = 0.003; triglycerides, p = 0.009).

CONCLUSIONS

These findings suggest that the subjects with less evident positive effects of running on metabolism are more exposed to the onset of mid-portion Achilles tendinopathy.

Chlamydia pneumoniae Hijacks a Host Autoregulatory IL-1β Loop to Drive Foam Cell Formation and Accelerate Atherosclerosis

Pathogen burden accelerates atherosclerosis, but the mechanisms remain unresolved. Activation of the NLRP3 inflammasome is linked to atherogenesis. Here we investigated whether Chlamydia pneumoniae (C.pn) infection engages NLRP3 in promoting atherosclerosis. C.pn potentiated hyperlipidemia-induced inflammasome activity in cultured macrophages and in foam cells in atherosclerotic lesions of Ldlr^-/- mice. C.pn-induced acceleration of atherosclerosis was significantly dependent on NLRP3 and caspase-1. We discovered that C.pn-induced extracellular IL-1β triggers a negative feedback loop to inhibit GPR109a and ABCA1 expression and cholesterol efflux, leading to accumulation of intracellular cholesterol and foam cell formation. Gpr109a and Abca1 were both upregulated in plaque lesions in Nlrp3^-/- mice in both hyperlipidemic and C.pn infection models. Mature IL-1β and cholesterol may compete for access to the ABCA1 transporter to be exported from macrophages. C.pn exploits this metabolic-immune crosstalk, which can be modulated by NLRP3 inhibitors to alleviate atherosclerosis.

Vascular inflammation and low-density lipoproteins: is cholesterol the link? A lesson from the clinical trials

For long time, the role of LDL and inflammation in the pathogenesis of atherosclerosis have been studied independently from each other and only more recently a common platform has been suggested. Accumulation of excess cholesterol due to the presence of increased circulating LDL promotes endothelium dysfunction and activation, which is associated with increased production of pro-inflammatory cytokines, overexpression of adhesion molecules, chemokines and C-reactive protein (CRP), increased generation of reactive oxygen species and reduction of nitric oxide levels and bioavailability. All these processes favour the progressive infiltration of inflammatory cells within the arterial wall where cholesterol accumulates, both extracellularly and intracellularly, and promotes vascular inflammation. According to this, lipid-lowering therapies should improve inflammation and, indeed, statins decrease circulating inflammatory markers such as CRP and improve endothelial function and plaque burden. Pleiotropic activities have been proposed to explain this effect. However, mendelian randomization studies ruled out a direct role for CRP on coronary artery disease and studies with other lipid lowering drugs, such as ezetimibe showed that the beneficial effect of LDL-cholesterol-lowering therapies on systemic inflammatory status, as monitored by changes in CRP plasma levels, could be achieved, independently of the mechanism of action, only in patients presenting with baseline inflamed conditions. These observations strengthen the direct link between cholesterol and inflammation and indicate that decreasing LDL levels is one of the key goals for improving cardiovascular outcome.

LINKED ARTICLES

This article is part of a themed section on Targeting Inflammation to Reduce Cardiovascular Disease Risk. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.22/issuetoc and http://onlinelibrary.wiley.com/doi/10.1111/bcp.v82.4/issuetoc.

Clinical application of simultaneous detection of cystatin C, cathepsin S, and IL-1 in classification of coronary artery disease

Cystatin C, cathepsin S, and IL-1 are three important biomarkers of atherosclerosis. Previous studies emphasized the relationship between individual biomarkers in coronary artery disease (CAD) patients and severity of atherosclerostic lesions of the coronary arteries, while combined cystatin C, cathepsin S, and IL-1 have not been reported for clinical classification of CAD. We aimed to establish a link between cystatin C, cathepsin S, IL-1 and CAD in this cohort study. Totally 112 subjects were enrolled and divided into the stable angina pectoris group, the unstable angina pectoris group and the acute myocardial infarction (AMI) groups, and 50 healthy adults served as controls. The levels of the three biomarkers were detected by ELISA. The results showed that serum level of cystatin C (mg/L) was higher in CAD patients compared with those in the healthy controls (AMIvs. unstable angina pectoris vs. stable angina pectoris vs. controls: 1.27±0.18 vs. 1.09±0.19 vs. 0.91±0.05 vs. 0.78±0.07, all P<0.01). Cathepsin S (ng/mL) was also significantly different among the groups (AMI vs. unstable angina pectoris vs. stable angina pectoris vs. controls: 67.30±8.36 vs. 56.90±7.16 vs. 49.8±2.72 vs. 67.30±8.36, all P<0.01). IL-1 (pg/mL) was significantly different among the groups as well (AMIvs. unstable angina pectoris vs. stable angina pectoris vs. controls: 2.96±0.57 vs. 2.46±0.24 vs. 2.28±0.09 vs. 2.02±0.13, all P<0.01). Spearman's correlation test revealed positive correlation between cystatin C, cathepsin S, IL-1 and Gensini score (r=0.451, 0.491, 0.397, respectively). It is suggested that simultaneous detection of cystatin C, cathepsin S, and IL-1 in serum may be useful in clinical classification and assessment of severity of CAD.

Biomedical Risk Factors of Achilles Tendinopathy in Physically Active People: a Systematic Review

Background

Achilles tendinopathy is the most prevalent tendon disorder in people engaged in running and jumping sports. Aetiology of Achilles tendinopathy is complex and requires comprehensive research of contributing risk factors. There is relatively little research focussing on potential biomedical risk factors for Achilles tendinopathy. The purpose of this systematic review is to identify studies and summarise current knowledge of biomedical risk factors of Achilles tendinopathy in physically active people.

Methods

Research databases were searched for relevant articles followed by assessment in accordance with PRISMA statement and standards of Cochrane collaboration. Levels of evidence and quality assessment designation were implemented in accordance with OCEBM levels of evidence and Newcastle-Ottawa Quality Assessment Scale, respectively.

Results

A systematic review of the literature identified 22 suitable articles. All included studies had moderate level of evidence (2b) with the Newcastle-Ottawa score varying between 6 and 9. The majority (17) investigated genetic polymorphisms involved in tendon structure and homeostasis and apoptosis and inflammation pathways.

Overweight as a risk factor of Achilles tendinopathy was described in five included studies that investigated non-genetic factors. COL5A1 genetic variants were the most extensively studied, particularly in association with genetic variants in the genes involved in regulation of cell-matrix interaction in tendon and matrix homeostasis. It is important to investigate connections and pathways whose interactions might be disrupted and therefore alter collagen structure and lead to the development of pathology. Polymorphisms in genes involved in apoptosis and inflammation, and Achilles tendinopathy did not show strong association and, however, should be considered for further investigation.

Conclusions

This systematic review suggests that biomedical risk factors are an important consideration in the future study of propensity to the development of Achilles tendinopathy. The presence of certain medical comorbidities and genetic markers should be considered when contemplating the aetiology of Achilles tendinopathy. Further elucidation of biomedical risk factors will aid in the understanding of tendon pathology and patient risk, thereby informing prevention and management strategies for Achilles tendinopathy.

Trial Registration

PROSPERO CRD42016036558

Immune-mediated mechanisms of atherosclerosis and implications for the clinic

INTRODUCTION

A large body of evidence supports the inflammatory hypothesis of atherosclerosis, and both innate and adaptive immune responses play important roles in all disease stages. Areas covered: Here, we review our understanding of the role of the immune response in atherosclerosis, focusing on the pathways currently amenable to therapeutic modulation. We also discuss the advantages or undesirable effects that may be foreseen from targeting the immune response in patients at high cardiovascular risk, suggesting new avenues for research. Expert commentary: There is an extraordinary opportunity to directly test the inflammatory hypothesis of atherosclerosis in the clinic using currently available therapeutics. However, a more balanced interpretation of the experimental and translational data is needed, which may help address and identify in more detail the appropriate settings where an immune pathway can be targeted with minimal risk.

NLRP3 Inflammasome Expression and Activation in Human Atherosclerosis

Background

The NLR family, pyrin domain containing 3 (NLRP3) inflammasome is an interleukin (IL)‐1β and IL‐18 cytokine processing complex that is activated in inflammatory conditions. The role of the NLRP3 inflammasome in the pathogenesis of atherosclerosis and myocardial infarction is not fully understood.

Methods and Results

Atherosclerotic plaques were analyzed for transcripts of the NLRP3 inflammasome, and for IL‐1β release. The Swedish First‐ever myocardial Infarction study in Ac‐county (FIA) cohort consisting of DNA from 555 myocardial infarction patients and 1016 healthy individuals was used to determine the frequency of 4 single nucleotide polymorphisms (SNPs) from the downstream regulatory region of NLRP3. Expression of NLRP3, Apoptosis‐associated speck‐like protein containing a CARD (ASC), caspase‐1 (CASP1), IL1B, and IL18 mRNA was significantly increased in atherosclerotic plaques compared to normal arteries. The expression of NLRP3 mRNA was significantly higher in plaques of symptomatic patients when compared to asymptomatic ones. CD68‐positive macrophages were observed in the same areas of atherosclerotic lesions as NLRP3 and ASC expression. Occasionally, expression of NLRP3 and ASC was also present in smooth muscle cells. Cholesterol crystals and ATP induced IL‐1β release from lipopolysaccharide‐primed human atherosclerotic lesion plaques. The minor alleles of the variants rs4266924, rs6672995, and rs10733113 were associated with NLRP3 mRNA levels in peripheral blood mononuclear cells but not with the risk of myocardial infarction.

Conclusions

Our results indicate a possible role of the NLRP3 inflammasome and its genetic variants in the pathogenesis of atherosclerosis.

Transcriptome-based identification of new anti-inflammatory and vasodilating properties of the n-3 fatty acid docosahexaenoic acid in vascular endothelial cell under proinflammatory conditions [corrected]

Scope

High intakes of n-3 fatty acids exert anti-inflammatory effects and cardiovascular protection, but the underlying molecular basis is incompletely defined. By genome-wide analysis we searched for novel effects of docosahexaenoic acid (DHA) on gene expression and pathways in human vascular endothelium under pro-inflammatory conditions.

Methods and Results

Human umbilical vein endothelial cells were treated with DHA and then stimulated with interleukin(IL)-1β. Total RNA was extracted, and gene expression examined by DNA microarray. DHA alone altered the expression of 188 genes, decreasing 92 and increasing 96. IL-1β changed the expression of 2031 genes, decreasing 997 and increasing 1034. Treatment with DHA before stimulation significantly affected the expression of 116 IL-1β-deregulated genes, counter-regulating the expression of 55 genes among those decreased and of 61 among those increased. Functional and network analyses identified immunological, inflammatory and metabolic pathways as the most affected. Newly identified DHA-regulated genes are involved in stemness, cellular growth, cardiovascular system function and cancer, and included cytochrome p450 4F2(CYP4F2), transforming growth factor(TGF)-β2, Cluster of Differentiation (CD)47, caspase recruitment domain(CARD)11 and phosphodiesterase(PDE)5α.

Conclusions

Endothelial exposure to DHA regulates novel genes and related pathways. Such unbiased identification should increase our understanding of mechanisms by which n-3 fatty acids affect human diseases.

Serum CD121a (Interleukin 1 Receptor, Type I): A Potential Novel Inflammatory Marker for Coronary Heart Disease

Inflammation is now believed to be responsible for coronary heart disease (CHD). This belief has stimulated the evaluation of various inflammatory markers for predicting CHD. This study was designed to investigate the association between four inflammatory cytokines (CD121a, interleukin [IL]-1β, IL-8, and IL-11) and CHD. Here, we evaluated 443 patients with CHD and 160 CHD-free controls who underwent coronary angiography. Cytokines were evaluated using flow cytometry, and statistical analyses were performed to investigate the association between cytokine levels and the risk of CHD. Patients with CHD had significantly higher levels of CD121a. The odds ratios for CHD according to increasing CD121a quartiles were 1.00, 1.47 [95% confidence interval (CI): 0.79–2.72], 2.67 (95% CI: 1.47–4.84), and 4.71 (95% CI: 2.65–8.37) in an age- and sex-adjusted model, compared to 1.00, 1.48 (95% CI: 0.70–3.14), 2.25 (95% CI: 1.10–4.62), and 4.39 (95% CI: 2.19–8.79) in a model that was adjusted for multiple covariates. A comparison of the stable angina, unstable angina, and acute myocardial infarction (AMI) subgroups revealed that patients with AMI had the highest CD121a levels, although IL-1β levels were similar across all groups. IL-8 levels were also increased in AMI patients, and IL-11 levels were higher in CHD patients than in non-CHD patients. Correlation analysis revealed a positive association between CD121a, IL-8, and the Gensini score. Together, the significant increase in CD121a levels among CHD patients suggests that it may be a novel inflammatory marker for predicting CHD.

The inflammasomes and autoinflammatory syndromes

Inflammation, a vital response of the immune system to infection and damage to tissues, can be initiated by various germline-encoded innate immune-signaling receptors. Among these, the inflammasomes are critical for activation of the potent proinflammatory interleukin-1 cytokine family. Additionally, inflammasomes can trigger and maintain inflammatory responses aimed toward excess nutrients and the numerous danger signals that appear in a variety of chronic inflammatory diseases. We discuss our understanding of how inflammasomes assemble to trigger caspase-1 activation and subsequent cytokine release, describe how genetic mutations in inflammasome-related genes lead to autoinflammatory syndromes, and review the contribution of inflammasome activation to various pathologies arising from metabolic dysfunction. Insights into the mechanisms that govern inflammasome activation will help in the development of novel therapeutic strategies, not only for managing genetic diseases associated with overactive inflammasomes, but also for treating common metabolic diseases for which effective therapies are currently lacking.

Inflammation imaging of atherosclerosis in Apo-E-deficient mice using a (99m)Tc-labeled dual-domain cytokine ligand

Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) play a critical role in initiating and accelerating atherosclerosis. This study evaluated the imaging properties of (99m)Tc-TNFR2-Fc-IL-1RA ((99m)Tc-TFI), a dual-domain cytokine radioligand that targets TNF-α and IL-1β pathways, in assessing atherosclerosis development in apolipoprotein-E-deficient (ApoE(-)(/)(-)) mice.

METHODS

The feasibility and specificity of detecting atherosclerosis with (99m)Tc-TFI SPECT imaging were investigated in ApoE(-)(/)(-) and ApoE(+)(/)(+) mice. Fifty-four ApoE(-)(/)(-) mice were fed either an atherogenic diet (AGD) or a normal diet (ND) beginning at 5 weeks of age. Eighteen Apo-E wild-type (ApoE(+)(/)(+)) mice were fed an ND. Two groups of ApoE(-)(/)(-) mice (n=12 each group) on AGD and ND were imaged three times with (99m)Tc-TFI and a high-resolution SPECT system at 20-25, 30-40, and 48-52 weeks to study the evolution of atherosclerotic plaque.

RESULTS

Focal radioactive accumulations in the aortic arch region were observed in the ApoE(-)(/)(-) mice (n=12) on AGD but not in the ApoE(+)(/)(+) mice on ND (n=10). Apo-E(-)(/)(-) mice on ND (n=11) exhibited lower radioactive uptake than ApoE(-)(/)(-) mice on AGD (P<0.05). Co-injection of an excess of cold ligand with (99m)Tc-TFI resulted in significant reduction of (99m)Tc-TFI uptake in the ApoE(-)(/)(-) mice on AGD. Longitudinal studies showed that (99m)Tc-TFI uptake in the aortas of ApoE(-)(/)(-) mice progressively increased from 20 to 48 weeks. Real-time PCR assays demonstrated that atherosclerotic aortas expressed significantly higher IL-1β and TNF-α than the aortas from wild-type controls.

CONCLUSIONS

Atherosclerotic plaques were detected by (99m)Tc-TFI imaging in ApoE(-)(/)(-) mice. (99m)Tc-TFI is promising for specific detection of inflammatory response in atherosclerotic plaques.

Moderate hypoxia potentiates interleukin-1β production in activated human macrophages

RATIONALE

Inflammation drives atherogenesis. Animal and human studies have implicated interleukin-1β (IL-1β) in this disease. Moderate hypoxia, a condition that prevails in the atherosclerotic plaque, may conspire with inflammation and contribute to the evolution and complications of atherosclerosis through mechanisms that remain incompletely understood.

OBJECTIVE

This study investigated the links between hypoxia and inflammation by testing the hypothesis that moderate hypoxia modulates IL-1β production in activated human macrophages.

METHODS AND RESULTS

Our results demonstrated that hypoxia enhances pro-IL-1β protein, but not mRNA, expression in lipopolysaccharide-stimulated human macrophages. We show that hypoxia limits the selective targeting of pro-IL-1β to autophagic degradation, thus prolonging its half-life and promoting its intracellular accumulation. Furthermore, hypoxia increased the expression of NLRP3, a limiting factor in NLRP3 inflammasome function, and augmented caspase-1 activation in lipopolysaccharide-primed macrophages. Consequently, hypoxic human macrophages secreted higher amounts of mature IL-1β than did normoxic macrophages after treatment with crystalline cholesterol, an endogenous danger signal that contributes to atherogenesis. In human atherosclerotic plaques, IL-1β localizes predominantly to macrophage-rich regions that express activated caspase-1 and the hypoxia markers hypoxia-inducible factor 1α and hexokinase-2, as assessed by immunohistochemical staining of carotid endarterectomy specimens.

CONCLUSIONS

These results indicate that hypoxia potentiates IL-1β expression in cultured human macrophages and in the context of atheromata, therefore unveiling a novel proinflammatory mechanism that may participate in atherogenesis.

Pro-inflammatory interleukin-1 genotypes potentiate the risk of coronary artery disease and cardiovascular events mediated by oxidized phospholipids and lipoprotein(a)

OBJECTIVES

The aim of this study was to assess the influence of pro-inflammatory interleukin (IL)-1 genotype status on the risk for coronary artery disease (CAD), defined as >50% diameter stenosis, and cardiovascular events mediated by oxidized phospholipids (OxPLs) and lipoprotein (Lp) (a).

BACKGROUND

OxPLs are pro-inflammatory, circulate on Lp(a), and mediate CAD. Genetic variations in the IL-1 region are associated with increased inflammatory mediators.

METHODS

IL-1 genotypes, OxPL on apolipoprotein B-100 (OxPL/apoB), and Lp(a) levels were measured in 499 patients undergoing coronary angiography. The composite genotype termed IL-1(+) was defined by 3 single-nucleotide polymorphisms in the IL-1 gene cluster associated with higher levels of pro-inflammatory cytokines. All other IL-1 genotypes were termed IL-1(-).

RESULTS

Among IL-1(+) patients, the highest quartile of OxPL/apoB was significantly associated with a higher risk for CAD compared with the lowest quartile (odds ratio [OR]: 2.84; p = 0.001). This effect was accentuated in patients age ≤60 years (OR: 7.03; p < 0.001). In IL-1(-) patients, OxPL/apoB levels showed no association with CAD. The interaction was significant for OxPL/apoB (OR: 1.99; p = 0.004) and Lp(a) (OR: 1.96; p < 0.001) in the IL-1(+) group versus the IL-1(-) group in patients age ≤60 years but not in those age >60 years. In IL-1(+) patients age ≤60 years, after adjustment for established risk factors, high-sensitivity C-reactive protein, and Lp(a), OxPL/apoB remained an independent predictor of CAD. IL-1(+) patients above the median OxPL/apoB presented to the cardiac catheterization laboratory a mean of 3.9 years earlier (p = 0.002) and had worse 4-year event-free survival (death, myocardial infarction, stroke, and need for revascularization) compared with other groups (p = 0.006).

CONCLUSIONS

Our study suggests that IL-1 genotype status can stratify population risk for CAD and cardiovascular events mediated by OxPL. These data suggest a clinically relevant biological link between pro-inflammatory IL-1 genotype, oxidation of phospholipids, Lp(a), and genetic predisposition to CAD and cardiovascular events.

Expression of retinoic acid target genes in coronary artery disease

Coronary atherosclerosis can lead to myocardial infarction, and secondarily to post-infarct remodelling and heart failure. Retinoic acid (RA) influences cell proliferation. We hypothesized that RA could influence gene expression and proliferation of cardiovascular cells. Left ventricular biopsies from patients with end-stage heart failure due to coronary artery disease (CAD) or dilated cardiomyopathy were investigated for the content of RA metabolites using liquid chromatography mass spectrometry (LC-MS/MS), and compared with healthy donors. All-trans retinoic acid (ATRA) was increased in the hearts of CAD patients. Gene expression (quantitative PCR) of RA target genes was not influenced in failing hearts, but was increased in the hearts of patients with CAD undergoing open heart surgery. The expression of RA target genes was increased in atherosclerotic lesions from carotid arteries compared to healthy arteries. Stimulation of cardiomyocytes, cardiofibroblasts, smooth muscle cells and endothelial cells with ATRA increased the gene expression of the key enzymes. Cardiofibroblast and smooth muscle cell proliferation were reduced by ATRA, which increased endothelial cell proliferation. Coronary artery disease leads to increased expression of RA target genes. ATRA accumulated in the failing human heart. All investigated cell types present in the heart had induced expression of RA target genes when stimulated with ATRA, which also influenced cell proliferation.

NLRP3 and IL-1β in macrophages as critical regulators of metabolic diseases

The activation of the NLRP3 inflammasome leads to the autocleavage and activation of caspase-1. Caspase-1 cleaves several substrates, including the pro-inflammatory cytokine IL-1β. Inflammation, in particular IL-1β, has long been associated with the progression of metabolic disorders, and recent evidence suggests that the NLRP3 inflammasome plays a critical role in this inflammation. This review concentrates on the activation of NLRP3 during the development of metabolic disorders and the effect this activation has on the inflammatory state as well as the metabolic state of the cell.

High-sensitivity C-reactive protein and atherosclerotic disease: from improved risk prediction to risk-guided therapy

There is compelling experimental and clinical evidence suggesting a crucial role for inflammation in the initiation and also the progression of atherosclerosis. Numerous biomarkers involved at various levels of the inflammation cascade have been shown to be associated with adverse cardiovascular outcomes. Yet, to date, it is not clear whether inflammation simply accompanies the atherosclerotic process or represents a major driver. Among all blood biomarkers, C-reactive protein (CRP), the classical acute phase reactant that can be measured with high-sensitivity (hs) assays seems to be the most promising candidate. It has already found its way into the guidelines in primary prevention. Hs-CRP can also be used to identify a high-risk group for recurrent events in patients with manifest atherosclerosis. Several post hoc analyses of large-scale randomized clinical trials testing various statins have indicated that, besides low density lipoprotein (LDL) cholesterol, hs-CRP levels might also further aid in tailoring statin treatment. The large JUPITER trial has prospectively confirmed these findings in primary prevention in patients with elevated hs-CRP but normal LDL cholesterol levels. Still, statin therapy is not a specific anti-inflammatory regime acting on the inflammation cascade. Thus, to directly test the inflammation hypothesis, a novel, more proximally located cytokine-based approach is needed. Canakinumab, a fully human monoclonal antibody against interleukin-1β, might represent a promising compound in this regard and provide a proof of concept. If successful, this may become a novel strategy to treat high-risk patients with stable atherosclerotic disease to prevent recurrent events on top of standard medical care.

How metabolism generates signals during innate immunity and inflammation

The interplay between immunity, inflammation, and metabolic changes is a growing field of research. Toll-like receptors and NOD-like receptors are families of innate immune receptors, and their role in the human immune response is well documented. Exciting new evidence is emerging with regard to their role in the regulation of metabolism and the activation of inflammatory pathways during the progression of metabolic disorders such as type 2 diabetes and atherosclerosis. The proinflammatory cytokine IL-1β appears to play a central role in these disorders. There is also evidence that metabolites such as NAD(+) (acting via deacetylases such as SIRT1 and SIRT2) and succinate (which regulates hypoxia-inducible factor 1α) are signals that regulate innate immunity. In addition, the extracellular overproduction of metabolites such as uric acid and cholesterol crystals acts as a signal sensed by NLRP3, leading to the production of IL-1β. These observations cast new light on the role of metabolism during host defense and inflammation.

Low levels of interleukin-1 receptor antagonist (IL-1RA) predict engraftment syndrome after autologous stem cell transplantation in POEMS syndrome and other plasma cell neoplasms

A rare, multisystem, plasma cell neoplasm, POEMS (polyradiculoneuropathy, organomegaly, endocrinopathy, M-spike, skin changes) syndrome is characterized by an abundance of proinflammatory and angiogenic cytokines. Patients with POEMS are known to have a high incidence of engraftment syndrome after autologous stem cell transplantation. We conducted a pilot study assessing levels of 30 different pro- and anti-inflammatory cytokines before and serially after transplantation in 18 patients with plasma cell neoplasms: POEMS syndrome (n = 9), multiple myeloma (n = 4), and amyloidosis (n = 5). We show that POEMS patients have higher pretransplantation levels of IL-4, IL-10, IL-13, IFN-α, and EGF as compared with those with non-POEMS plasma cell neoplasms. Higher pre- and posttransplantation IL-13 levels correlated with delayed neutrophil engraftment in POEMS patients. Low posttransplantation IL-1RA levels correlated with engraftment syndrome in both POEMS and non-POEMS patients. We conclude that differences in the peri-transplantation cytokine milieu may explain the higher transplantation morbidity in patients with POEMS syndrome. Our results need validation in a larger cohort.

The Role of Interleukin-1 Genotype in the Association between Coronary Heart Disease and Periodontitis in a Syrian Population

Objective. To determine whether differences exist between periodontitis subjects with and without Coronary Heart Disease (CHD) in a Syrian population in the distribution of IL-1 alleles at positions IL-1α+4845, IL-1β+3954, IL-1β−511, and IL-1RN VNTR. Background. The role of Interleukin-1 genes in the association between periodontitis and CHD has been demonstrated in previous studies. No study has been carried out on the Syrian population to asses for such a role. Methods. 200 Syrian Arab periodontitis patients (184 males, 16 females; mean age 52.61) were divided into two groups: cases group 100 subjects with CHD (92 males, 8 females; mean age 52.06); controls group 100 subjects without CHD (92 males, 8 females; mean age 53.16). Probing depth (PD), clinical attachment loss (CAL), and alveolar bone loss (ABL) were performed for patients. Blood samples were collected for genotyping analysis of IL-1α+4845, IL-1β+3954, and IL-1β−511 using PCR-RFLP technique and IL-1RN VNTR using normal PCR. Results. An association between both (CAL and ABL) and CHD was shown after adjustment for other confounders (OR: 7.659, P = 0.001; OR: 3.645, P = 0.006, resp.). Also, an association between allele 2 of IL-1α+4845, IL-1β+3954, and IL-1β−511 and ABL was shown. Allele 2 of IL-1α+4845 and IL-1β−511 was associated with ABL among individuals with and without CHD. But after adjustment for other confounders, the association remained only between allele 2 of IL-11α+4845 and both CHD and severe ABL (OR: 0.189, P < 0.001). Conclusion. Allele 2 of IL-11α+4845 may be considered a risk indicator for having both CHD and severe ABL in the investigated Syrian population.

Effects of chimeric decoy oligodeoxynucleotide in the regulation of transcription factors NF-κB and Sp1 in an animal model of atherosclerosis

Atherosclerosis is a multifactorial and progressive disease in which the inflammatory reaction and inflammation-related factors play important roles at all stages. Modulation of NF-κB and Sp1 expression may be important targets for the prevention and treatment of atherosclerotic vascular disease. To develop a novel therapeutic approach in atherosclerosis, we examined the simultaneous suppression of the transcription factors NF-κB and Sp1 which regulate inflammation. We employed chimeric decoy oligodeoxynucleotide (ODN) containing the consensus of NF-κB and Sp1-binding sites to suppress these transcription factors simultaneously and to test chimeric decoy for anti-atherogenic effects in an atherogenic diet-induced atherosclerotic mouse model with inflammatory stimulation. C57BL/6 mice were fed with an atherogenic diet (15% fat, 1.25% cholesterol and 0.5% cholic acid) for 12 weeks to induce atherosclerosis; lipopolysaccharide (LPS, 2 mg/kg) was intraperitoneally injected in the first week of study to simulate underlying infectious burden during development of atherosclerosis. Decoy ODNs were injected into tail vein at 2, 4, 6, 8, 10 and 12 weeks after only three LPS injections in mice fed the atherogenic diet. Chimeric decoy ODN alleviated atherosclerotic changes and reduced serum cholesterol and inflammatory cytokines. In accordance with these results, the expressions of atherosclerotic markers were inhibited by chimeric decoy ODN. Chimeric decoy ODN modulates multiple pathogenic aspects of an atherogenic diet-induced atherosclerosis with inflammatory stimulation: hypercholesterolaemia and inflammation. Therefore, this study demonstrates the efficacy of chimeric decoy ODN on atherosclerosis with immunological complication.

Effect of interleukin 1β inhibition in cardiovascular disease

PURPOSE OF REVIEW

Atherosclerosis is greatly influenced by inflammatory mediators at all phases. Recent studies have suggested a causal role of one such mediator, interleukin 1β (IL-1β), in the development of atherosclerotic vascular disease. This review highlights recent investigation of the role of IL-1β in atherosclerosis and the potential of its inhibition as a promising therapeutic strategy for the treatment of atherosclerotic vascular disease.

RECENT FINDINGS

Studies in animals have generally shown decreased atherosclerotic plaque burden in atherosclerosis-prone mice deficient in IL-1β and increased plaque in mice exposed to excess IL-1β. In humans, IL-1β was found in greater concentrations in atherosclerotic human coronary arteries compared with normal coronary arteries. Preclinical and clinical studies of IL-1β inhibition have shown efficacy in the treatment of several inflammatory disorders, suggesting that IL-1β may be a novel therapeutic target for anti-inflammatory therapy in atherosclerosis, such as coronary artery disease (CAD).

SUMMARY

IL-1β inhibition offers an interesting and biology-based opportunity to test the potential beneficial effects of an anti-inflammatory therapeutic strategy in patients with CAD. A large clinical trial evaluating the impact of IL-1β inhibition in CAD is ongoing and will be an important test of the inflammation hypothesis in CAD.

Associations between interleukin-1 gene polymorphisms and coronary heart disease risk: a meta-analysis

Objective

A great number of studies regarding the associations between IL-1B-511, IL-1B+3954 and IL-1RN VNTR polymorphisms within the IL-1gene cluster and coronary heart disease (CHD) have been published. However, results have been inconsistent. In this study, a meta-analysis was performed to investigate the associations.

Methods

Published literature from PubMed and Embase databases were searched for eligible publications. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random- or fixed- effect model.

Results

Thirteen studies (3,219 cases/2,445 controls) for IL-1B-511 polymorphism, nine studies (1,828 cases/1,818 controls) for IL-1B+3954 polymorphism and twelve studies (2,987 cases/ 2,208 controls) for IL-1RN VNTR polymorphism were included in this meta analysis. The results indicated that both IL-1B-511 and IL-1B+3954 polymorphisms were not associated with CHD risk (IL-1B-511 T vs. C: OR = 0.98, 95%CI 0.87–1.09; IL-1B+3954 T vs. C: OR = 1.06, 95%CI 0.95–1.19). Similarly, there was no association between IL-1RN VNTR polymorphism and CHD risk (*2 vs. L: OR = 1.00, 95%CI 0.85–1.17).

Conclusions

This meta-analysis suggested that there were no associations between IL-1 gene cluster polymorphisms and CHD.

Single nucleotide polymorphisms in IL1B and the risk of acute coronary syndrome: a Danish case-cohort study

Background

Interleukin-1B (IL-1B) is a key pro-inflammatory cytokine that has been associated with the development of atherosclerosis and myocardial infarction. However, the prospective associations between functional single nucleotide polymorphisms (SNPs) in IL1B and incident acute coronary syndrome (ACS) have not been thoroughly investigated. The aims of this study were to examine the associations between individual SNPs in and SNP haplotypes of the promoter region of IL1B and incident ACS in a prospective study. Furthermore, we wanted to explore potential interactions with other risk factors for ACS on an additive scale.

Methodology/Principal Findings

The present study was based on the Danish prospective study Diet, Cancer and Health comprising more than 57 000 participants aged 50–64 at baseline. During a median follow-up of 7.2 years we identified 989 cases of incident ACS (755 men and 234 women). All cases were validated by review of medical records, and information on covariates was collected by study technicians. The study was conducted according to a case-cohort study design including ACS cases and a sex-stratified sub cohort of 1663 participants drawn randomly from the entire cohort. Weighted Cox proportional hazard models with age as time axis were used in the statistical analyses. Individual IL1B SNPs, SNP haplotypes, or haplotype combinations were not significantly associated with incident ACS, and, likewise, we found no evidence of interaction on an additive scale between IL1B haplotypes and risk factors, respectively.

Conclusions/Significance

Genetic variation in the promoter region of IL1B may not be associated with incident ACS in men or women above the age of 50 years.

Genetic variation within the interleukin-1 gene cluster and ischemic stroke

BACKGROUND AND PURPOSE

Evidence is emerging that inflammation plays a key role in the pathophysiology of ischemic stroke (IS). The aim of this study was to investigate whether genetic variation in the interleukin-1α, interleukin-1β, and interleukin-1 receptor antagonist genes (IL1A, IL1B, and IL1RN) is associated with IS and/or any etiologic subtype of IS.

METHODS

Twelve tagSNPs were analyzed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 844 patients with IS and 668 control subjects. IS subtypes were defined according to the Trial of Org 10172 in Acute Stroke Treatment criteria in SAHLSIS. The Lund Stroke Register and the Malmö Diet and Cancer study were used as a replication sample for overall IS (in total 3145 patients and 1793 control subjects).

RESULTS

The single nucleotide polymorphism rs380092 in IL1RN showed an association with overall IS in SAHLSIS (OR, 1.21; 95% CI, 1.02-1.43; P=0.03), which was replicated in the Lund Stroke Register and the Malmö Diet and Cancer study sample. An association was also detected in all samples combined (OR, 1.12; 95% CI, 1.04-1.21; P=0.03). Three single nucleotide polymorphisms in IL1RN (including rs380092) were nominally associated with the subtype of cryptogenic stroke in SAHLSIS, but the statistical significance did not remain after correction for multiple testing. Furthermore, increased plasma levels of interleukin-1 receptor antagonist were observed in the subtype of cryptogenic stroke compared with controls.

CONCLUSIONS

This comprehensive study, based on a tagSNP approach and replication, presents support for the role of IL1RN in overall IS.

Inflammasome activation in obesity-related inflammatory diseases and autoimmunity

The inflammasome is a highly regulated protein complex that triggers caspase-1 activation and subsequent secretion of IL-1β and IL-18. Recognition of microbial components and danger signals by NOD-like receptor (NLR) family members in the cytosol promotes inflammasome activation and downstream inflammatory cytokine production. Pathogen recognition by NLRs and downstream release of inflammasome-derived cytokines are important in host defense against numerous infections. Recent studies have also identified a unique role for inflammasome regulation in the induction and pathogenesis of multiple autoimmune and inflammatory disorders. We now know that obesity-related factors and endogenous markers of cellular stress can lead to unchecked activation of the inflammasome and provoke inflammation and subsequent destruction of vital organs. This review will highlight recent findings that link inflammasome signaling to the progression of autoinflammatory and autoimmune diseases. We will focus on the contribution of inflammasome activation to the pathogenesis of autoinflammatory and autoimmune diseases that are of major significance to human health including type 2 diabetes, atherosclerosis, multiple sclerosis, and type 1 diabetes.

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.

Lack of association between IL-1 and IL-6 gene polymorphisms and myocardial infarction in Turkish population

Inflammation and genetics play a key role in the pathogenesis of atherosclerosis and its clinical result myocardial infarction (MI). Proinflammatory cytokines, IL-1 and IL-6, have been shown to play essential roles in developmental stages of coronary artery plaque formation. The aim of this study was to determine the association between IL-1 [IL-1RN, IL-1β (-511, +3953)], IL-6 [-174, -572, -597] gene polymorphisms and MI in Turkish population. A total of 402 people were participated; 235 healthy control subjects and 167 MI patients (MI<40, n: 72; MI>40, n: 95). Polymerase chain reaction (PCR) was used to determine the genotype of IL-1RN, whereas the genotypes of IL-1β (-511, +3953) and IL-6 (-174, -572, -597) were determined using PCR followed with restriction digestion analysis. There was no significant difference between MI and controls for IL-1RN, IL-1β-511, +3953 (P: 0.875, 0.608, 0.442) and IL-6 -174, -572, -597 (P: 0.977, 0.632, 0.584) gene polymorphisms. Lack of association was observed between MI at younger age (MI<40) and either IL-1RN VNTR, IL-1β-511, +3953 (P: 0.878, 0.732, 0.978) or IL-6 -174, -572, -597 (P: 0.313, 0.654, 0.552) gene polymorphisms. This study demonstrated that there was not any association between IL-1, IL-6 gene variants and MI in Turkish population. In addition, IL-1 and IL-6 gene polymorphisms did not affect MI at younger age (MI<40) or older age (MI>40). Thus, IL-1 and IL-6 single nucleotide polymorphisms may not be a risk factor for susceptibility to MI in Turkish population.

PPARdelta inhibits IL-1beta-stimulated proliferation and migration of vascular smooth muscle cells via up-regulation of IL-1Ra

Activation of peroxisome proliferator-activated receptor (PPAR) delta by GW501516, a specific PPARdelta ligand, significantly inhibited interleukin (IL)-1beta-induced proliferation and migration of vascular smooth muscle cells (VSMCs). This effect of GW501516 was dependent on transforming growth factor-beta, and was mediated through the up-regulation of IL-1 receptor antagonist. The inhibitory effect of GW501516 on VSMC proliferation was associated with cell cycle arrest at the G1 to S phase transition, which was accompanied by the induction of p21 and p53 along with decreased cyclin-dependent kinase 4 expression. Inhibition of cell migration by GW501516 was associated with the down-regulation of matrix metalloproteinase (MMP)-2 and MMP-9 in IL-1beta-treated VSMCs. Inhibition of extracellular signal-regulated kinase significantly reduced the GW501516-mediated inhibition of IL-1beta-stimulated VSMC proliferation. These results suggest that PPARdelta plays an important role in the pathophysiology of diseases associated with the proliferation and migration of VSMCs.

The IL-1 family: regulators of immunity

Over recent years it has become increasingly clear that innate immune responses can shape the adaptive immune response. Among the most potent molecules of the innate immune system are the interleukin-1 (IL-1) family members. These evolutionarily ancient cytokines are made by and act on innate immune cells to influence their survival and function. In addition, they act directly on lymphocytes to reinforce certain adaptive immune responses. This Review provides an overview of both the long-established and more recently characterized members of the IL-1 family. In addition to their effects on immune cells, their involvement in human disease and disease models is discussed.