Interleukin-18 as a therapeutic target in acute myocardial infarction and heart failure

Adenine decreases hypertrophic effects through interleukin-18 receptor

Cardiac hypertrophy is the main cause of heart failure. Levels of circulating interleukin-18 (IL-18) have been reported to increase in congestive heart disease and cardiac hypertrophy. Relationships among IL-18 levels, IL-18 receptor (IL-18R) expression, and cardiac hypertrophy remain unclear. IL-18 can induce cardiac hypertrophy in cardiomyoblasts. We also studied IL-18R messenger RNA (mRNA) and protein expression through quantitative-polymerase chain reaction and Western blotting. Furthermore, we treated cardiomyoblasts with adenine, gold nanoparticles (AuNPs), and inhibitors to analyze the morphology and identify signaling pathways involved in cardiac hypertrophy. Moreover, we studied the effects of IL-18R small interfering RNA (siRNA) on signaling pathways through Western blotting. The mRNA expression of IL-18R in H9c2 cardiomyoblasts, which was induced by IL-18, increased significantly after 8 h, and the protein level increased significantly after 15 h. Morphological examination of H9c2 cardiomyoblasts showed that cell volume and cell diameter decreased after adenine pretreatment. Both p38 MAPK and PI3 kinase are biomarkers in the pathway correlated with cardiac hypertrophy. After treatment with inhibitors SB203580 and LY294002, the levels of p38 MAPK and PI3 kinase, respectively, decreased along with cell size and IL-18R expression. Treatment with adenine, but not AuNPs, reduced the levels of phosphorylated p38 and PI3 kinase expression more effectively than did treatment with the respective inhibitors alone. IL-18R siRNA significantly reduced cell size but not PI3 kinase expression and phosphorylation of p38 MAPK. However, adenine treatment reduced PI3 kinase expression after treatment with IL-18R siRNA. In this study, IL-18 induced cardiomyoblast hypertrophy through IL-18R upregulation, which was found to be related to p38 MAPK and PI3 kinase signaling. Adenine, but not AuNPs, showed antihypertrophic effects possibly because of decreased levels of signaling.

The selective NLRP3-inflammasome inhibitor MCC950 reduces myocardial fibrosis and improves cardiac remodeling in a mouse model of myocardial infarction

BACKGROUND/AIMS

Early inflammatory responses after myocardial infarction (MI) are likely to increase myocardial fibrosis and subsequent cardiac remodeling. MCC950, a specific NLRP3 inhibitor, was previously found to effectively inhibit the release of inflammatory factors IL-18 and IL-1β. In this study, we evaluated the effect of MCC950, as a potential new treatment strategy for MI, on myocardial fibrosis and cardiac remodeling using an experimental mouse model.

METHODS

Male C57BL/6 mice were subjected to left coronary artery ligation to induce MI and then treated with MCC950 (10 mg/kg) or PBS for 14 days. After 30 days, echocardiography was performed to assess cardiac function and myocardial fibrosis was evaluated using H&E- and Masson's Trichrome-stained sections. Myocardial expression of inflammatory factors and fibrosis markers was analyzed by western blotting, immunofluorescence, ELISA, and real-time quantitative PCR.

RESULTS

The ejection fraction in the 10 mg/kg group (40.7 ± 4.2%; N = 6, p = 0.0029) was statistically preserved compared to that in the control group (14.0 ± 4.4%). Myocardial fibrosis was also reduced in MCC950-treated animals (MCC950, 23.2 ± 3.0 vs PBS, 36.2 ± 3.7; p < 0.05). Moreover, myocardial NLRP3, cleaved IL-1β, and IL-18 levels were reduced in MCC950-treated animals. H&E and molecular examination revealed decreases in inflammatory cell infiltration and inflammatory factor expression in the heart. In vitro, MCC950 inhibited NLRP3, reduced caspase-1 activity, and further downregulated IL-1β and IL-18.

CONCLUSION

MCC950, as a specific NLRP3 inhibitor, can alleviate fibrosis and improve cardiac function in a mouse model by suppressing early inflammatory responses post-MI.

An Orally Available NLRP3 Inflammasome Inhibitor Prevents Western Diet-Induced Cardiac Dysfunction in Mice

BACKGROUND

A diet rich in saturated fat and sugars (Western diet, WD) induces myocardial expression of the NLRP3 inflammasome and dysfunction in mice. We therefore hypothesized that a diet enriched with an orally available NLRP3 inflammasome inhibitor could prevent WD-induced cardiac dysfunction in mice.

METHODS

Ten-week-old CD-1 male mice were fed WD or standard diet (SD) for 8 weeks. The compound 16673-34-0, an orally active NLRP3 inhibitor, was added to the diet at a concentration of 100 mg/Kg. The plasmatic levels of the NLRP3 inflammasome inhibitor were measured. Food intake, body weight, and glucose tolerance were assessed. Cardiac systolic and diastolic functions were measured by Doppler echocardiography at baseline, 4 weeks, and 8 weeks.

RESULTS

WD induced a significant increase in body weight (+14%, P = 0.02), impaired glucose tolerance (+34%, P = 0.03), and a significant increase in isovolumetric relaxation time (+129%, P = 0.03) and reduction in left ventricular ejection fraction (-10%, P = 0.03), as compared to standard chow diet (SD). The treatment with NLRP3 inhibitor in the diet prevented cardiac systolic and diastolic dysfunction (P < 0.05 for left ventricular ejection fraction, isovolumetric relaxation time, and myocardial performance index in WD with drug vs. WD without drug), without significant changes in heart rate and metabolic parameters.

CONCLUSIONS

An orally available NLRP3 inhibitor prevented WD-induced cardiac dysfunction in obese mice.

The Influence of Proinflammatory Cytokines on Voriconazole Trough Concentration in Patients With Different Forms of Hematologic Disorders

Even though multiple factors are involved in the high fluctuation of voriconazole (VCZ) plasma concentration, little is known regarding the influence of proinflammatory cytokines on VCZ concentration. The aim of this study was to investigate the influence of proinflammatory cytokines, namely, interleukin (IL)-1β, IL-6, IL-18, interferon-γ, tumor necrosis factor-α, and transforming growth factor (TGF)-β1 on VCZ trough concentration (VCZ-C_min ) in Chinese patients with different forms of hematologic disorders. A total of 250 plasma samples from 113 patients were analyzed for VCZ-C_min and proinflammatory cytokines using a validated liquid chromatography-tandem mass spectrometry and enzyme-linked immunosorbent assay methods, respectively. Patient demographics and clinical characteristics were obtained from hospital records. VCZ-C_min was significantly correlated with IL-18 in acute myeloid leukemia (r = 0.456; P ˂ .0001), acute lymphoblastic leukemia (r = 0.317; P = .019), and chronic myeloid leukemia (r = 0.737; P = .004) while VCZ-C_min and TGF-β1 were correlated (r = 0.436; P ˂ .001) in acute myeloid leukemia patients only. VCZ-C_min at different concentration range showed significant inhibitory effect of IL-6. A backward multiple linear regression model revealed patient age (coefficient [β] = 0.025; P = .04), gamma-glutamyl transferase (β = 0.003; P = .023), IL-6 (β = -0.001; P = .024), proton pump inhibitor coadministration (β = 1.518; P = .002), and cytochrome P450 (CYP) 2C19 polymorphism as predictors of VCZ-C_min ; however, these factors explained only 29% of VCZ-C_min variation. In conclusion, IL-18 and TGF-β1 have correlation with VCZ-C_min in Chinese patients with leukemia. Apparently, VCZ may have an inhibitory effect on IL-6 levels. Furthermore, patient age, gamma-glutamyl transferase, IL-6, PPI coadministration, and cytochrome P450 2C19 polymormorphism partially predicted the VCZ-C_min . Therapeutic drug monitoring of VCZ in Chinese patients is highly encouraged.

Role of IL-37 in Cardiovascular Disease Inflammation

Inflammation is closely related to the pathogenesis and prognosis of cardiovascular disease (CVD). Interleukin-37 (IL-37), an anti-inflammatory IL-1 family cytokine, shifts cytokine expression from pro- to anti-inflammation via regulation of macrophage polarization and lipid metabolism. In macrophages, IL-37 functions through both intracellular and extracellular pathways to regulate the activity of NF-kB and PTEN as well as the expression of cytokines, including IL-1β, IL-6, and IL-10. Moreover, IL-37 levels are increased in the serum of patients with heart failure, atherosclerosis, and acute coronary syndrome with no evidence of anti-inflammatory effects. However, transgenic overexpression of IL-37 improves cardiac infarct and attenuates atherosclerosis plaque expansion. Hence, it is worthwhile to investigate the precise mechanism and role of IL-37 in the pathogenesis of CVD, which may provide deeper understanding of the inflammatory response in this context. This review summarizes the regulatory role of IL-37 in systematic inflammation induced by CVD and highlights recent advancements in the clinical application of IL-37 as a therapeutic agent or biomarker for diagnosis of CVD.

SGK1-dependent stimulation of vascular smooth muscle cell osteo-/chondrogenic transdifferentiation by interleukin-18

The serum- and glucocorticoid-inducible kinase 1 (SGK1) is a key regulator of osteo-/chondrogenic transdifferentiation and subsequent calcification of vascular smooth muscle cells (VSMCs). The phenotypical transdifferentiation of VSMCs is associated with increased interleukin-18 (IL-18) levels and generalized inflammation. Therefore, the present study investigated the possible involvement of SGK1 in IL-18-induced vascular calcification. Experiments were performed in primary human aortic smooth muscle cells (HAoSMCs) treated with recombinant human IL-18 protein in control or high phosphate conditions and following SGK1 knockdown by siRNA or pharmacological inhibition of SGK1, PI3K, and PDK1. As a result, IL-18 treatment increased SGK1 mRNA and protein expression in HAoSMCs. IL-18 upregulated SGK1 mRNA expression in a dose-dependent manner. This effect was paralleled by upregulation of the mRNA expression of MSX2 and CBFA1, osteogenic transcription factors, and of tissue-nonspecific alkaline phosphatase (ALPL), an osteogenic enzyme, as markers of increased osteo-/chondrogenic transdifferentiation. Phosphate treatment increased SGK1 and osteogenic markers mRNA expression as well as ALPL activity and induced calcification of HAoSMCs, all effects significantly augmented by additional treatment with IL-18. Conversely, silencing of SGK1 or cotreatment with the SGK1 inhibitor EMD638683 blunted the effects of IL-18 on osteo-/chondrogenic transdifferentiation and calcification of HAoSMCs. The procalcific effects of IL-18 were similarly suppressed in the presence of PI3K or PDK1 inhibitors. In conclusion, SGK1 expression is upregulated by IL-18 in VSMCs and SGK1 participates in the intracellular signaling of IL-18-induced osteo-/chondrogenic transdifferentiation of VSMCs. Thus, SGK1 may serve as therapeutic target to limit the progression of medial vascular calcification during vascular inflammation.

Interleukin-1 Blockade in Cardiovascular Diseases: From Bench to Bedside

Interleukin-1 (IL-1) is the prototypical pro-inflammatory cytokine that occupies an apical place in the inflammatory cascade and also modulates cardiac function, functioning as a soluble cardiodepressant factor. Preclinical research over the past 4 decades has shown that blocking IL-1 processing or activity favorably affects cardiomyocyte survival and cardiac function in experimental animal models, paving the way for clinical studies in patients with heart disease. The promising results of phase II clinical trials of IL-1 blockade in patients with acute myocardial infarction and heart failure have been followed by a successful phase III trial in patients with prior acute myocardial infarction. Three IL-1 blockers with different mechanism of action are currently available for clinical use, although currently none have an indication for heart disease. We herein review the bench-to-bedside clinical translation of IL-1 targeting strategies and discuss the potential use of IL-1 blockade in patients with heart disease.

Therapeutic potential of dinitrobenzene sulfonic acid (DNBS)-induced colitis in mice by targeting IL-1β and IL-18

Interleukin (IL)-1 and IL-18 belong to the IL-1 family of ligands, and their receptors are members of the IL-1 receptor family. Both cytokines drive an extensive range of pro-inflammatory networks in many cell types using common signal transduction cascades. Anyway, differences in signaling pathways exist. With this aim in mind, we investigated by using transgenic mice the mechanisms through the simultaneous deficiency of both IL-1β and IL-18 could be more protective compared to blocking the single cytokine IL-1β or IL-18 during colitis. Colitis was provoked in mice by instillation of dinitrobenzene sulfonic acid (DNBS) in the colon. The results indicated that single knockout (KO) mice of IL-1β or IL-18, and double KO mice of both IL-1β and IL-18 were hyporesponsive to DNBS-induced colitis compared to wild type (WT) mice, in which double KO were less sensitive than single KO mice. Moreover, treatment with Anakinra (IL-1R antagonist) also ameliorated colitis, in views of macroscopic and histological alteration, infiltration of neutrophils or Th1 cells, oxidative and nitrosative stress. Anakinra more significantly reduced cyclooxygenase (COX-2) and nuclear factor (NF-κB) levels as well as IKB-α degradation compared to blocking IL-18. On the contrary, the absence of IL-18 reduced p-ERK and p-p38 mitogen-activated protein kinase (MAPKs) in a more significant way compared to blocking IL-1β. Thus, the double KO increased the protective effects against colon inflammation maybe because different converging inflammatory pathways are being inhibited. In conclusion, the blocking of both IL-1β and IL-18 function may be advantageous in the treatment of IBD or inflammatory diseases.

Inflammasome, pyroptosis, and cytokines in myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury induces a sterile inflammatory response, leading to further injury that contributes to the final infarct size. Locally released danger-associated molecular patterns lead to priming and triggering of the NOD-like receptor protein 3 inflammasome and amplification of the inflammatory response and cell death by activation of caspase-1. We review strategies inhibiting priming, triggering, or caspase-1 activity or blockade of the inflammasome-related cytokines interleukin-1β and interleukin-18, focusing on the beneficial effects in experimental models of acute myocardial infarction in animals and the initial results of clinical translational research trials.

RVX 208: A novel BET protein inhibitor, role as an inducer of apo A-I/HDL and beyond

Low-density cholesterol (LDL) has been the prime target of currently available lipid-lowering therapies although current research is expanding the focus beyond LDL lowering and has included high-density cholesterol (HDL) also as the target. Bromo and extra-terminal (BET) proteins are implicated in the regulation of transcription of several regulatory genes and regulation of proinflammatory pathways. As atherosclerosis is an inflammatory pathway and studies showed that BET inhibition has a role in inhibiting inflammation, the concept of BET inhibition came in the field of atherosclerosis. RVX 208 is a novel, orally active, BET protein inhibitor and the only BET inhibitor currently available in the field of atherosclerosis. RVX 208 acts primarily by increasing apo A-I (apolipoprotein A-I) and HDL levels. RVX 208 has a novel action of increasing larger, more cardio-protective HDL particles. Post hoc analysis of Phase II trials also showed that RVX 208 reduced major adverse cardiovascular events (MACE) in treated patients, over and above that of apo A-I/HDL increasing action. This MACE reducing actions of RVX 208 were largely due to its novel anti-inflammatory actions. Currently, a phase III trial, BETonMACE, is recruiting patients to look for the effects of RVX 208 in patients with increased risk of atherosclerotic cardiovascular disease. So BET inhibitors act in multiple ways to inhibit and modulate atherosclerosis and would be an emerging and potential option in the management of multifactorial disease like coronary artery disease by inhibiting a single substrate. But we need long-term phase III trial data's to look for effects on real-world patients.

Increased Expression of Interleukin-18 mRNA is Associated with Carotid Artery Stenosis

Background:

Carotid artery stenosis is the atherosclerotic narrowing of the proximal internal carotid artery and one of the primary causes of stroke. Elevated expression of the pleiotropic proinflammatory cytokine interleukin-18 has been demonstrated in human atherosclerotic plaques.

Aims:

To investigate whether the mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 −137 G/C (rs187238) variants are associated with carotid artery stenosis development.

Study Design:

Case-control study.

Methods:

The mRNA expression levels of interleukin-18 and interleukin-18-binding protein and interleukin-18 rs187238 variants were evaluated by quantitative real-time polymerase chain reaction and real-time polymerase chain reaction, respectively, in the peripheral blood mononuclear cells of 70 patients with carotid artery stenosis (36 symptomatic, 34 asymptomatic) and 75 healthy controls.

Results:

Interleukin-18 mRNA expression was significantly increased in carotid artery stenosis patients compared to that in healthy controls (p=0.01). However, no significant difference was observed between interleukin-18-binding protein mRNA expression levels in patients with carotid artery stenosis and those in controls (p=0.101). Internal carotid artery stenosis severity was significantly higher in symptomatic patients than that in asymptomatic patients (p<0.001). A significant relationship was identified between interleukin-18 expression and internal carotid artery stenosis severity in patients with carotid artery stenosis (p=0.051). Interleukin-18 rs187238 polymorphism genotype frequencies did not significantly differ between patients with carotid artery stenosis and controls (p=0.246). A significant difference was identified between interleukin-18-binding protein gene expression and symptomatic and asymptomatic patients (p=0.026), but there was no difference in interleukin-18 expression between the symptomatic and asymptomatic subgroups (p=0.397).

Conclusion:

Interleukin-18 mRNA expression may affect carotid artery stenosis etiopathogenesis and internal carotid artery stenosis severity and also may play a mechanistic role in the pathogenesis of carotid artery stenosis, influencing the appearance of symptoms.

The selective NLRP3-inflammasome inhibitor MCC950 reduces infarct size and preserves cardiac function in a pig model of myocardial infarction

Aims

Myocardial infarction (MI) triggers an intense inflammatory response that is associated with infarct expansion and is detrimental for cardiac function. Interleukin (IL)-1β and IL-18 are key players in this response and are controlled by the NLRP3-inflammasome. In the current study, we therefore hypothesized that selective inhibition of the NLRP3-inflammasome reduces infarct size and preserves cardiac function in a porcine MI model.

Methods and results

Thirty female landrace pigs were subjected to 75 min transluminal balloon occlusion and treated with the NLRP3-inflammasome inhibitor MCC950 (6 or 3 mg/kg) or placebo for 7 days in a randomized, blinded fashion. After 7 days, 3D-echocardiography was performed to assess cardiac function and Evans blue/TTC double staining was executed to assess the area at risk (AAR) and infarct size (IS). The IS/AAR was lower in the 6 mg/kg group (64.6 ± 8.8%, P = 0.004) and 3 mg/kg group (69.7 ± 7.2%, P = 0.038) compared with the control group (77.5 ± 6.3%). MCC950 treatment markedly preserved left ventricular ejection fraction in treated animals (6 mg/kg 47 ± 8%, P = 0.001; 3 mg/kg 45 ± 7%, P = 0.031; control 37 ± 6%). Myocardial neutrophil influx was attenuated in treated compared with non-treated animals (6 mg/kg 132 ± 72 neutrophils/mm2, P = 0.035; 3 mg/kg 207 ± 210 neutrophils/mm2, P = 0.5; control 266 ± 158 neutrophils/mm2). Myocardial IL-1β levels were dose-dependently reduced in treated animals.

Conclusions

NLRP3-inflammasome inhibition reduces infarct size and preserves cardiac function in a randomized, blinded translational large animal MI model. Hence, NLRP3-inflammasome inhibition may have therapeutic potential in acute MI patients.

Interleukin-18 deteriorates Fabry cardiomyopathy and contributes to the development of left ventricular hypertrophy in Fabry patients with GLA IVS4+919 G>A mutation

RATIONALE

A high incidence of GLA IVS4+919 G>A mutation in patients with Fabry disease of the later-onset cardiac phenotype, has been reported in Taiwan. However, suitable biomarkers or potential therapeutic surrogates for Fabry cardiomyopathy (FC) in such patients under enzyme replacement treatment (ERT) remain unknown.

OBJECTIVE

Using FC patients carrying IVS4+919 G>A mutation, we constructed an induced pluripotent stem cell (iPSC)-based disease model to investigate the pathogenetic biomarkers and potential therapeutic targets in ERT-treated FC.

RESULTS AND METHODS

The iPSC-differentiated cardiomyocytes derived from FC-patients (FC-iPSC-CMs) carried IVS4+919 G>A mutation recapitulating FC characteristics, including low α-galactosidase A enzyme activity, cellular hypertrophy, and massive globotriaosylceramide accumulation. Microarray analysis revealed that interleukin-18 (IL-18), a pleiotropic cytokine involved in various myocardial diseases, was the most highly upregulated marker in FC-iPSC-CMs. Meanwhile, IL-18 levels were found to be significantly elevated in the culture media of FC-iPSC-CMs and patients' sera. Notably, the serum IL-18 levels were highly paralleled with the progression of left ventricular hypertrophy in Fabry patients receiving ERT. Finally, using FC-iPSC-CMs as in vitro FC model, neutralization of IL-18 with specific antibodies combined with ERT synergistically reduced the secretion of IL-18 and the progression of cardiomyocyte hypertrophy in FC-iPSC-CMs.

CONCLUSION

Our data demonstrated that cardiac IL-18 and circulating IL-18 are involved in the pathogenesis of FC and LVH. IL-18 may be a novel marker for evaluating ERT efficacy, and targeting IL-18 might be a potential adjunctive therapy combined with ERT for the treatment of advanced cardiomyopathy in FC patients with IVS4+919 G>A mutation.

Expression of vascular endothelial growth factor in cardiac repair: Signaling mechanisms mediating vascular protective effects

The present study was aimed to investigate the vascular endothelial growth factor expression pattern in acute myocardial infarction induced rats. Serum level of vascular endothelial growth factor and its mRNA expression in myocardium were determined. Protein expression of vascular endothelial growth factor and endothelial nitric oxide synthase were measured. Serum level of vascular endothelial growth factor was increased 105.3, 260, 378.2 and 271.3% following the onset of acute myocardial infarction at 3, 6, 9 and 12days respectively. The mRNA and protein expression of vascular endothelial growth factor was substantially increased following the onset of acute myocardial infarction. Protein expression of endothelial nitric oxide synthase was increased up to 1.02 fold. Taking all these data together, it is concluded that the vascular endothelial growth factor was increased in serum and tissue and attained peak at 9th day following the onset of acute myocardial infarction. Increased vascular endothelial growth factor level in serum and tissue could increase endothelial cell proliferation and angiogenesis, and endothelial nitric oxide synthase could inhibit apoptosis and protect cardiomyocytes. In conclusion, the increased vascular endothelial growth factor expression could play an essential role in cardiac repair following the onset of acute myocardial infarction.

The Role of Toll-Like Receptor Signaling in the Progression of Heart Failure

Medical systems worldwide are being faced with a growing need to understand mechanisms behind the pathogenesis of heart failure (HF) that is considered as a leading cause of morbidity and mortality around the world. Elevated levels of inflammatory mediators have been identified in patients with HF, which are primarily manifestations of innate immune responses mediated by pattern recognition receptors (PRRs). Toll-like receptors (TLRs), which belong to PRRs, are subjected to the release of pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) to generate innate immune responses. More and more emerging data indicate that TLR signaling pathway molecules are involved in the progression of HF. Herein, we present new data with regard to the activation of TLRs in the failing heart, focusing on TLR2, TLR3, TLR4, and TLR9, and suggest the potential use of TLRs in target therapy.

Inflammation and Its Consequences After Surgical Versus Transcatheter Aortic Valve Replacement

Symptomatic aortic stenosis can be treated by surgical aortic valve replacement (SAVR) or transcatheter aortic valve replacement (TAVR), the latter of which is regarded as a minimally invasive procedure. Differences between these procedures regarding immune responses or changes in coagulation and neurocognitive function have thus far been evaluated only sparsely. We carried out a prospective, single-center, nonrandomized explorative study with 38 patients. Thirteen patients were subjected to either SAVR or transfemoral (TF-) TAVR, and 12 patients underwent transapical (TA-) TAVR. Plasma cytokines (IL-6, -8, -18, presepsin) and acute-phase proteins (C-reactive protein, procalcitonin), markers of coagulation and platelet function, and neurocognitive function (via various standard tests) were assessed before and at five-time points during a 72-h follow-up after surgery. SAVR and TA-TAVR patients responded similarly to the procedure in terms of C-reactive protein, leukocyte numbers, and IL-6, whereas these responses were substantially lower in TF-TAVR patients. Only SAVR patients showed measurable IL-10 levels. SAVR patients without prior anticoagulation experienced a robust and transient restoration of platelet function after surgery, with no hypercoagulation observable in functional coagulation assays. None of the procedures led to an immediate improvement of hand and leg coordination, but patients after TA-TAVR had decreased neurocognitive function. Patients after SAVR or TA-TAVR exhibit a robust pro-inflammatory response, which is-on the cytokine level-counterbalanced only in SAVR patients. Our results point toward a greater impact of TA-TAVR on neurocognitive function and indicate a potentially detrimental activation of platelets in some patients after SAVR.

The NLRP3 inflammasome in acute myocardial infarction

The heart is extremely sensitive to ischaemic injury. During an acute myocardial infarction (AMI) event, the injury is initially caused by reduced blood supply to the tissues, which is then further exacerbated by an intense and highly specific inflammatory response that occurs during reperfusion. Numerous studies have highlighted the central role of the NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome in this process. The inflammasome, an integral part of the innate immune system, is a macromolecular protein complex that finely regulates the activation of caspase 1 and the production and secretion of powerful pro-inflammatory cytokines such as IL-1β and IL-18. In this Review, we summarize evidence supporting the therapeutic value of NLRP3 inflammasome-targeted strategies in experimental models, and the data supporting the role of the NLRP3 inflammasome in AMI and its consequences on adverse cardiac remodelling, cytokine-mediated systolic dysfunction, and heart failure.

Biomarkers of Endothelial, Renal, and Platelet Dysfunction in Stage 5 Chronic Kidney Disease Hemodialysis Patients With Heart Failure

The aim of this study was to determine the role of endothelial, renal, and inflammatory biomarkers in the pathogenesis of heart failure (HF) in patients with stage 5 chronic kidney disease (CKD5) undergoing maintenance hemodialysis (HD). Plasma levels of biomarkers-kidney injury molecule 1 (KIM-1), N-terminal pro brain natriuretic peptide (NT-proBNP), glycated hemoglobin, neutrophil gelatinase-associated lipocalin, interleukin-18,platelet-derived growth factor, platelet factor 4 (PF4), 25-OH vitamin D, parathyroid hormone (PTH), endothelin, and endocan-were measured in CKD5-HD patients at the Loyola University Ambulatory Dialysis facility. The HF (+) CKD5-HD patients, as compared to HF (-) CKD5-HD patients, exhibited significantly elevated NT-proBNP ( P = .0194) and KIM-1 ( P = .0485). The NT-proBNP in HF (+) CKD5-HD patients was found to correlate with the levels of serum potassium ( P = .023, R = -.39), calcium ( P = .029, R = -.38), and PF4 ( P = .045, R = -.35). The KIM-1 in HF (+) CKD5-HD patients was found to correlate with PTH ( P = .043, R = -.36) and 25-OH vitamin D ( P = .037, R = .36). Elevated plasma NT-proBNP and KIM-1 in CKD5-HD and HF (+) CKD5-HD patients suggest that natriuretic peptides and KIM-1 may contribute to the pathogenesis of HF in CKD5-HD patients.

Endothelial dysfunction mediated by interleukin-18 in patients with ischemic heart disease undergoing coronary artery bypass grafting surgery

When medication management or percutaneous coronary intervention is not successful in patients with advanced ischemic heart disease, surgical revascularisation-predominantly coronary artery bypass grafting (CABG)-is considered the gold standard. However, CABG surgery can lead to ischemia/reperfusion injury, which is characterized by a strong inflammatory response. Interleukin (IL)-18, is a strong inflammatory mediator, that is released from cardiomyocytes and can be found in the systemic circulation of patients during and immediately after CABG surgery. The existing damage of endothelial glycocalyx in patients with ischemic heart disease is further impaired concurrently during the surgery due to the anaesthesia-surgical technique used and intravascular fluid loading. This results in the increased incidence of adverse events, including myocardial infarction. IL-18 leads to the activation of lymphocyte cytotoxicity via cytotoxic mediators (Fas ligand, Tumour necrosis factor (TNF)-related apoptosis-inducing ligand, perforin, and granulysin). We hypothesize that IL-18 is released locally in the heart and the systemic circulation in patients undergoing CABG surgery and may be correlated with the level of activity of circulating lymphocytes. In turn, this may lead to lymphocyte-mediated cytotoxicity directed toward damaged and activated endothelial cells. Shear stress glycocalyx, as well as damaged and activated endothelial cells then become the main the source of pro-inflammatory cytokines, chemokines, and adhesion molecules. These attract activated lymphocytes to adhere to the endothelium or enter the subintimal layer, increasing existing or initiating the formation of new plaques, which leads to the development of myocardial infarction during or shortly after surgery. To evaluate our hypothesis, we will measure the local concentration of IL-18 in the sinus coronarius and systemic circulation. These values will then be correlated with immunological and biochemical parameters, predominantly with the concentration of degradation products of glycocalyx and cytotoxic mediators in activated lymphocytes. If our hypothesis is correct, measuring the IL-18 concentration that is responsible for glycocalyx deterioration, may become a useful tool for predicting myocardial infarction occurrence in patients undergoing CABG surgery.

Interleukin-18 gene deletion protects against sepsis-induced cardiac dysfunction by inhibiting PP2A activity

BACKGROUND

Interleukin-18 (IL-18) neutralization protects against lipopolysaccharide (LPS)-induced injuries, including myocardial dysfunction. However, the mechanism is yet to be fully elucidated. The aim of the present study was to determine whether IL-18 gene deletion prevents sepsis-induced cardiac dysfunction and to elucidate the potential mechanisms underlying IL-18-mediated cardiotoxicity by LPS.

METHODS AND RESULTS

Ten-week-old male wild-type (WT) and IL-18 knockout (IL-18 KO) mice were intraperitoneally administered LPS. Serial echocardiography showed better systolic pump function and less left ventricular (LV) dilatation in LPS-treated IL-18 KO mice compared with those in LPS-treated WT mice. LPS treatment significantly decreased the levels of phospholamban (PLN) and Akt phosphorylation in WT mice compared with those in saline-treated WT mice, while the LPS-induced decrease in the phosphorylation levels was attenuated in IL-18 KO mice compared with that in WT mice. IL-18 gene deletion also attenuated an LPS-induced increase of type 2 protein phosphatase 2A (PP2A) activity, a molecule that dephosphorylates PLN and Akt. There was no difference in type 1 protein phosphatase (PP1) activity. To address whether IL-18 affects PLN and Akt phosphorylation via PP2A activation in cardiomyocytes, rat neonatal cardiac myocytes were cultured and stimulated using 100ng/ml of recombinant rat IL-18. Exogenous IL-18 decreased the level of PLN and Akt phosphorylation in cardiomyocytes. PP2A activity but not PP1 activity was increased by IL-18 stimulation in cardiomyocytes.

CONCLUSIONS

IL-18 plays a pivotal role in advancing sepsis-induced cardiac dysfunction, and the mechanisms underlying IL-18-mediated cardiotoxicity potentially involve the regulation of PLN and Akt phosphorylation through PP2A activity.

Interleukin-18 mediates cardiac dysfunction induced by western diet independent of obesity and hyperglycemia in the mouse

Obesity and diabetes are independent risk factors for heart failure and are associated with the consumption of diet rich in saturated fat and sugar, Western diet (WD), known to induce cardiac dysfunction in the mouse through incompletely characterized inflammatory mechanisms. We hypothesized that the detrimental cardiac effects of WD are mediated by interleukin-18 (IL-18), pro-inflammatory cytokine linked to cardiac dysfunction. C57BL/6J wild-type male mice and IL-18 knockout male mice were fed high-saturated fat and high-sugar diet for 8 weeks. We measured food intake, body weight and fasting glycemia. We assessed left ventricular (LV) systolic and diastolic function by Doppler echocardiography and cardiac catheterization. In wild-type mice, WD induced a significant increase in isovolumetric relaxation time, myocardial performance index and left ventricular end-diastolic pressure, reflecting an impairment in diastolic function, paired with a mild reduction in LV ejection fraction. IL-18 KO mice had higher food intake and greater increase in body weight without significant differences in hyperglycemia. Despite displaying greater obesity, IL-18 knockout mice fed with WD for 8 weeks had preserved cardiac diastolic function and higher left ventricular ejection fraction. IL-18 mediates diet-induced cardiac dysfunction, independent of food intake and obesity, thus highlighting a disconnect between the metabolic and cardiac effects of IL-18.

Association Between Interleukin-18 Level and Left Ventricular Mass Index in Hypertensive Patients

BACKGROUND AND OBJECTIVES

In clinical trials, hypertensive patients tend to have higher interleukin-18 (IL-18) concentrations than normotensive groups, but the relationship between IL-18 and left ventricular hypertrophy (LVH), which is a marker of end-organ damage, is not well studied. We aimed to investigate the relationship between IL-18 and LVH in apparently healthy subjects free of clinically significant atherosclerotic disease.

SUBJECTS AND METHODS

We enrolled 198 subjects (102 women and 96 men) between May 2006 and March 2007, who were free of cardiovascular or immune diseases, but were suspected to have hypertension. Twenty-four-hour ambulatory blood pressure monitoring and two-dimensional echocardiography were performed. Lipid profiles, high-sensitivity CRP (hs-CRP), IL-18, and whole blood cell counts were measured for all subjects.

RESULTS

White blood cell count, hs-CRP, left ventricular mass, left ventricular mass index (LVMI), and IL-18 were higher in the hypertensive group than in the normotensive group (p=0.045, p=0.004, p<0.0001, p=0.001, and p=0.017 respectively). Twenty-four hour day and night systolic and diastolic blood pressure averages were positively correlated with IL-18 level in the entire study population. In multivariate regression analysis, left ventricular mass index and hs-CRP level were independently associated with IL-18 level in both the hypertensive group and the entire study population (β=0.154, β=0.149 p=0.033, p=0.040 and β=0.151, β=0.155 p=0.036, p=0.032 respectively).

CONCLUSION

We found that IL-18 level independently predicted LVMI in both the general population and in newly diagnosed hypertensive patients.

Obesity and Heart Failure: Focus on the Obesity Paradox

The escalating prevalence of obesity has been linked to substantial increases in both metabolic and cardiovascular disease. Nevertheless, the direct effects of obesity on cardiovascular health and function require further exploration. In particular, the relationship between obesity and cardiac function has received intense scrutiny. Although obesity increases the risk for development of heart failure (HF), it appears to exert a protective effect in patients in whom HF has already been diagnosed (the "obesity paradox"). The protective effects of obesity in patients with previously diagnosed HF are the focus of particularly intense research. Several explanations have been proposed, but most studies are limited by the use of body mass index to classify obesity. Because body mass index does not distinguish between fat mass, fat-free mass, and lean mass, individuals with similar body mass indices may have vastly different body composition. This article discusses the roles of body composition, diet, cardiorespiratory fitness, and weight loss in the development of cardiac dysfunction and HF and the potential protective role that body composition compartments might play in improving HF prognosis. Based on an intensive literature search (Pubmed, Google Scholar) and critical review of the literature, we also discuss how a multidisciplinary approach including a nutritional intervention targeted to reduce systemic inflammation and lean mass-targeted exercise training could potentially exert beneficial effects for patients with HF.

Cytokines are early diagnostic biomarkers of graft-versus-host disease in liver recipients

BACKGROUND

Graft-versus-host disease (GVHD) is associated with high mortality. Early diagnosis is essential to start treatment and to improve outcomes. Because of the inflammatory nature, we hypothesis that cytokine profile of patients with GVHD may serve as diagnostic markers. The present study was to evaluate the role of cytokine profile in the diagnosis of GVHD.

METHODS

An immunoassay was used to detect 29 cytokines simultaneously in the serum; the measuring sensitivity of all cytokines was pg/mL. Healthy subjects undergoing annual routine physical examinations served as negative controls; 23 patients with hepatocellular carcinoma (HCC) who had undergone liver transplantation (the LT group) comprised the test subjects. A total of 22 kidney recipients with biopsy-confirmed GVHD (the RT group) were included for comparison. HCC patients with radical surgery (the HCC group, n=22) served as positive control. The liver contents of the three cytokines, IL-2, IL-18, and IFN-gamma, were detected with immunohistochemistry. Serum granzyme B and perforin were measured by flow cytometry.

RESULTS

Of the 29 cytokines, the levels of IL-2 and IL-18 were increased significantly in liver recipients with GVHD compared with healthy controls (P<0.05). The serum levels of these three cytokines in the healthy, HCC, LT, and RT groups were IL-2: 0.90+/-0.02, 4.14+/-0.61, 5.10+/-0.89, and 1.48+/-0.09 pg/mL; IL-18: 80.61+/-9.35, 109.51+/-10.93, 230.11+/-12.92, and 61.98+/-7.88 pg/mL; IFN-gamma: 24.06+/-3.88, 24.84+/-3.21, 40.37+/-5.88, and 15.33+/-4.72 pg/mL, respectively. Immunohistochemistry showed that these 3 cytokines expressions in the liver were parallel to the serum cytokine. After standard anti-GVHD treatment, the expressions of IL-2, IL-18, and IFN-gamma were decreased in the liver (P<0.05). Serum granzyme B and perforin were significantly increased in GVHD patients (P<0.05).

CONCLUSIONS

IL-2, IL-18 and IFN-gamma were from liver and might serve as biomarkers for monitoring GVHD development and the effects of anti-GVHD treatment. Granzyme B and perforin may play a role in increasing IL-2, IL-18, and IFN-gamma levels in GVHD patients.

A potentially protective role of IL-18 Binding Protein in HIV-infected Long-Term Non-Progressors

An imbalance between IL-18 and its antagonist, IL-18 Binding Protein, occurs in the circulation of HIV-infected individuals. We show here for the first time that HIV-infected Long Term Non-Progressors (LTNPs) do not develop this imbalance, and maintain normal levels of IL-18BP in the circulation. Their circulating levels of the antagonist correlate negatively with viral loads and show a positive trend with CD4+ T cells counts. The maintenance of normal production of IL-18BP may contribute, at least in part, to the ability of LTNPs to delay AIDS progression.

Inflammatory Cytokines as Risk Factors for Mortality After Acute Cardiac Events

INTRODUCTION

Inflammatory markers have been identified as potential indicators of future adverse outcome after acute cardiac events.

AIM

This study aimed to analyze baseline inflammatory cytokines levels in patients with acute heart failure (AHF) and/or acute coronary syndrome (ACS) according to survival. The main objective was to identify risk factors for mortality after an episode of AHF and/or ACS.

METHODS

In this prospective longitudinal study 75 patients with the diagnosis of AHF and/or ACS were enrolled. Baseline laboratory and clinical data were retrieved. Serum and urine interleukin-6 (IL-6) and interleukin-18 (IL-18) levels, plasma B-type natriuretic peptide (BNP) and serum cystatin C values were determined. The primary outcome was in-hospital mortality while secondary outcome was six-month mortality.

RESULTS

Median serum and urine IL-6 levels, serum and urine IL-18 levels, as well as median concentrations of plasma BNP and serum cystatin C, were significantly increased in deceased in comparison to surviving AHF and/or ACS patients. Univariate Cox regression analysis identified serum IL-6, serum IL-18, urine IL-6, urine IL-18 as well as serum cystatin C and Acute Physiology and Chronic Health Evaluation (APACHE) II score as risk factors for mortality after an episode of AHF and/or ACS. Multivariate Cox regression analysis revealed that only serum IL-6 is the independent risk factor for mortality after acute cardiac events (HR 61.7, 95% CI 2.1-1851.0; p=0.018).

CONCLUSION

Present study demonstrated the strong prognostic value of serum IL-6 in predicting mortality of patients with AHF and/or ACS.

Targeting the Innate Immune Response to Improve Cardiac Graft Recovery after Heart Transplantation: Implications for the Donation after Cardiac Death

Heart transplantation (HTx) is the ultimate treatment for end-stage heart failure. The number of patients on waiting lists for heart transplants, however, is much higher than the number of available organs. The shortage of donor hearts is a serious concern since the population affected by heart failure is constantly increasing. Furthermore, the long-term success of HTx poses some challenges despite the improvement in the management of the short-term complications and in the methods to limit graft rejection. Myocardial injury occurs during transplantation. Injury initiated in the donor as result of brain or cardiac death is exacerbated by organ procurement and storage, and is ultimately amplified by reperfusion injury at the time of transplantation. The innate immune system is a mechanism of first-line defense against pathogens and cell injury. Innate immunity is activated during myocardial injury and produces deleterious effects on the heart structure and function. Here, we briefly discuss the role of the innate immunity in the initiation of myocardial injury, with particular focus on the Toll-like receptors and inflammasome, and how to potentially expand the donor population by targeting the innate immune response.

Review of novel therapeutic targets for improving heart failure treatment based on experimental and clinical studies

Heart failure (HF) is a major public health priority due to its epidemiological transition and the world's aging population. HF is typified by continuous loss of contractile function with reduced, normal, or preserved ejection fraction, elevated vascular resistance, fluid and autonomic imbalance, and ventricular dilatation. Despite considerable advances in the treatment of HF over the past few decades, mortality remains substantial. Pharmacological treatments including β-blockers, angiotensin-converting enzyme inhibitors, angiotensin receptor blockers, and aldosterone antagonists have been proven to prolong the survival of patients with HF. However, there are still instances where patients remain symptomatic, despite optimal use of existing therapeutic agents. This understanding that patients with chronic HF progress into advanced stages despite receiving optimal treatment has increased the quest for alternatives, exploring the roles of additional pathways that contribute to the development and progression of HF. Several pharmacological targets associated with pathogenesis of HF have been identified and novel therapies have emerged. In this work, we review recent evidence from proposed mechanisms to the outcomes of experimental and clinical studies of the novel pharmacological agents that have emerged for the treatment of HF.

Pharmacologic Inhibition of the NLRP3 Inflammasome Preserves Cardiac Function After Ischemic and Nonischemic Injury in the Mouse

BACKGROUND

Sterile inflammation resulting from myocardial injury activates the NLRP3 inflammasome and amplifies the inflammatory response mediating further damage.

METHODS

We used 2 experimental models of ischemic injury (acute myocardial infarction [AMI] with and without reperfusion) and a model of nonischemic injury due to doxorubicin 10 mg/kg to determine whether the NLRP3 inflammasome preserved cardiac function after injury.

RESULTS

Treatment with the NLRP3 inflammasome inhibitor in the reperfused AMI model caused a significant reduction in infarct size measured at pathology or as serum cardiac troponin I level (-56% and -82%, respectively, both P < 0.001) and preserved left ventricular fractional shortening (LVFS, 31 ± 2 vs. vehicle 26% ± 1%, P = 0.003). In the non-reperfused AMI model, treatment with the NLRP3 inhibitor significantly limited LV systolic dysfunction at 7 days (LVFS of 20 ± 2 vs. 14% ± 1%, P = 0.002), without a significant effect on infarct size. In the doxorubicin model, a significant increase in myocardial interstitial fibrosis and a decline in systolic function were seen in vehicle-treated mice, whereas treatment with the NLRP3 inhibitor significantly reduced fibrosis (-80%, P = 0.001) and preserved systolic function (LVFS 35 ± 2 vs. vehicle 27% ± 2%, P = 0.017).

CONCLUSIONS

Pharmacological inhibition of the NLRP3 inflammasome limits cell death and LV systolic dysfunction after ischemic and nonischemic injury in the mouse.

Imbalanced production of IL-18 and its antagonist in human diseases, and its implications for HIV-1 infection

IL-18 is a pleiotropic and multifunctional cytokine that belongs to the IL-1 family. It is produced as a biologically inactive precursor, which is cleaved into its active mature form mainly by caspase-1. The caspase becomes active from its inactive precursor (procaspase-1) upon assembly of an inflammasome. Because of IL-18's potential pro-inflammatory and tissue destructive effects, its biological activities are tightly controlled in the body by its naturally occurring antagonist called IL-18BP. The antagonist is produced in the body both constitutively and in response to an increased production of IL-18 as a negative feedback mechanism. Under physiological conditions, most of IL-18 in the circulation is bound with IL-18BP and is inactive. However, an imbalance in the production of IL-18 and its antagonist (an increase in the production of IL-18 with a decrease, no increase or an insufficient increase in the production of IL-18BP) has been described in many chronic inflammatory diseases in humans. The imbalance results in an increase in the concentrations of free IL-18 (unbound with its antagonist) resulting in increased biological activities of the cytokine that contribute towards pathogenesis of the disease. In this article, we provide an overview of the current biology of IL-18 and its antagonist, discuss how the imbalance occurs in HIV infections and how it contributes towards development of AIDS and other non-AIDS-associated clinical conditions occurring in HIV-infected individuals undergoing combination anti-retroviral therapy (cART). Finally, we discuss challenges facing immunotherapeutic strategies aimed at restoring balance between IL-18 and its antagonist in these patients.

RVX-208, a BET-inhibitor for treating atherosclerotic cardiovascular disease, raises ApoA-I/HDL and represses pathways that contribute to cardiovascular disease

High density lipoproteins (HDL), through activity of the main protein component apolipoprotein A-I (ApoA-I), can reduce the risk of cardiovascular disease (CVD) by removing excess cholesterol from atherosclerotic plaque. In this study, we demonstrate that the bromodomain and extraterminal domain (BET) inhibitor RVX-208 increases ApoA-I gene transcription and protein production in human and primate primary hepatocytes. Accordingly, RVX-208 also significantly increases levels of ApoA-I, HDL-associated cholesterol, and HDL particle number in patients who received the compound in recently completed phase 2b trials SUSTAIN and ASSURE. Moreover, a post-hoc analysis showed lower instances of major adverse cardiac events in patients receiving RVX-208. To understand the effects of RVX-208 on biological processes underlying cardiovascular risk, we performed microarray analyses of human primary hepatocytes and whole blood treated ex vivo. Overall, data showed that RVX-208 raises ApoA-I/HDL and represses pro-inflammatory, pro-atherosclerotic and pro-thrombotic pathways that can contribute to CVD risk.

Increased IL18 mRNA levels in peripheral artery disease and its association with triglyceride and LDL cholesterol levels: a pilot study

Peripheral artery disease (PAD) typically refers to lower limb vessel ischemia caused by atherosclerotic stenosis of lower extremity arteries. IL18 is a pleiotropic pro-inflammatory cytokine reported to function as an inflammatory biomarker in cardiovascular diseases. IL18 activity is balanced by high-affinity naturally occurring IL18-binding protein (IL18BP). This study aimed to determine whether IL18, IL18 BP mRNA levels and -137 G/C (rs187238) polymorphism, which was previously associated with IL18 gene transcriptional activity, were associated with PAD etiology. IL18, IL18BP mRNA levels from peripheral blood mononuclear cells and -137 G/C (rs187238) polymorphism were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and RT-PCR, respectively, in 55 PAD patients (26 aorta-iliac, 29 femoro-popliteal) and 61 disease-free controls. IL18 mRNA levels were increased in PAD patients compared with healthy controls (p = 0.09); however, did not reach a statistical significant level, also did not significantly differ between aorta-iliac and femoro-popliteal occlusive PAD subgroups (p = 0.285). However, IL18BP mRNA levels were significantly lower in PAD group compared with controls (p < 0.001). Genotype frequencies of rs187238 polymorphism did not significantly differ between PAD patients and controls (p = 0.385). IL18 mRNA levels were significantly correlated with triglycerides and LDL cholesterol levels in PAD patients (p = 0.003, p = 0.014, respectively). HDL cholesterol levels were negatively correlated with IL18 mRNA levels in controls (p = 0.05). This report is a preliminary study to show an association between IL18, IL18BP mRNA levels and PAD and suggests that the IL18 gene may have a significant relationship with triglyceride and LDL cholesterol levels in PAD patients.

The IL-1 Pathway in Type 2 Diabetes and Cardiovascular Complications

Patients with type 2 diabetes (T2D) exhibit chronic activation of the innate immune system in pancreatic islets, in insulin-sensitive tissues, and at sites of diabetic complications. This results from a pathological response to overnutrition and physical inactivity seen in genetically predisposed individuals. Processes mediated by the proinflammatory cytokine interleukin-1 (IL-1) link obesity and dyslipidemia and have implicated IL-1β in T2D and related cardiovascular complications. Epidemiological, molecular, and animal studies have now assigned a central role for IL-1β in driving tissue inflammation during metabolic stress. Proof-of-concept clinical studies have validated IL-1β as a target to improve insulin production and action in patients with T2D. Large ongoing clinical trials will address the potential of IL-1 antagonism to prevent cardiovascular and other related complications.

Ticagrelor Protects the Heart Against Reperfusion Injury and Improves Remodeling After Myocardial Infarction

Objective—

In addition to P2Y 12 receptor antagonism, ticagrelor inhibits adenosine cell uptake. Prior data show that 7-day pretreatment with ticagrelor limits infarct size. We explored the acute effects of ticagrelor and clopidogrel on infarct size and potential long-term effects on heart function.

Approach and Results—

Rats underwent 30-minute ischemia per 24-hour reperfusion. (1) Ticagrelor (10 or 30 mg/kg) or clopidogrel (12.5 mg/kg) was given via intraperitoneal injection 5 minutes before reperfusion. (2) Rats received ticagrelor acute (intraperitoneal; 30 mg/kg), chronic (oral; 300 mg/kg per day) for 4 weeks starting 1 day after reperfusion or the combination (acute+chronic). Another group received clopidogrel (intraperitoneal [12.5 mg/kg]+oral [62.5 mg/kg per day]) for 4 weeks. (1) Ticagrelor dose-dependently reduced infarct size, 10 mg/kg (31.5%±1.8%; P <0.001) and 30 mg/kg (21.4%±2.6%; P <0.001) versus control (45.3±1.7%), whereas clopidogrel had no effect (42.4%±2.6%). Ticagrelor, but not clopidogrel, increased myocardial adenosine levels, increased phosphorylation of Akt, endothelial NO synthase, and extracellular-signal-regulated kinase 1/2 4 hours after reperfusion and decreased apoptosis. (2) After 4 weeks, left ventricular ejection fraction was reduced in the vehicle-treated group (44.8%±3.5%) versus sham (77.6%±0.9%). All ticagrelor treatments improved left ventricular ejection fraction, acute (69.5%±1.6%), chronic (69.2%±1.0%), and acute+chronic (76.3%±1.2%), whereas clopidogrel had no effect (37.4%±3.7%). Ticagrelor, but not clopidogrel, attenuated fibrosis and decreased collagen-III mRNA levels 4 weeks after ischemia/reperfusion. Ticagrelor, but not clopidogrel, attenuated the increase in proinflammatory tumor necrosis factor-α, interleukin-1β, and interleukin-18, and increased anti-inflammatory 15-epi-lipoxin-A 4 levels.

Conclusions—

Ticagrelor, but not clopidogrel, administered just before reperfusion protects against reperfusion injury. This acute treatment or chronic ticagrelor for 4 weeks or their combination improved heart function, whereas clopidogrel, despite achieving a similar degree of platelet inhibition, had no effect.

Effect of Cardiac Resynchronization Therapy on Inflammation in Congestive Heart Failure: A Review

Congestive heart failure is associated with increased levels of several inflammatory mediators, and animal studies have shown that infusion of a number of cytokines can induce heart failure. However, several drugs with proven efficacy in heart failure have failed to affect inflammatory mediators, and anti-inflammatory therapy in heart failure patients has thus far been disappointing. Hence, to what extent heart failure is caused by or responsible for the increased inflammatory burden in the patient is still unclear. Over the past couple of decades, resynchronization therapy with a biventricular pacemaker has emerged as an effective treatment in a subset of heart failure patients, reducing both morbidity and mortality. Such treatment has also been shown to affect the inflammation associated with heart failure. In this study, we review recent data on the association between heart failure and inflammation, and in particular how resynchronization therapy can affect the inflammatory process.

The Importance of NLRP3 Inflammasome in Heart Failure

Patients with heart failure continue to suffer adverse health consequences despite advances in therapies over the past 2 decades. Identification of novel therapeutic targets that may attenuate disease progression is therefore needed. The inflammasome may play a central role in modulating chronic inflammation and in turn affecting heart failure progression. The inflammasome is a complex of intracellular interaction proteins that trigger maturation of proinflammatory cytokines interleukin-1β and interleukin-18 to initiate the inflammatory response. This response is amplified through production of tumor necrosis factor α and activation of inducible nitric oxide synthase. The purpose of this review is to discuss recent evidence implicating this inflammatory pathway in the pathophysiology of heart failure.

The inflammasome in myocardial injury and cardiac remodeling

SIGNIFICANCE

An inflammatory response follows an injury of any nature, and while such a response is an attempt to promote healing, it may, itself, result in further injury.

RECENT ADVANCES

The inflammasome is a macromolecular structure recently recognized as a central mediator in the acute inflammatory response. The inflammasome senses the injury and it amplifies the response by leading to the release of powerful pro-inflammatory cytokines, interleukin-1β (IL-1β) and IL-18.

CRITICAL ISSUES

The activation of the inflammasome in the heart during ischemic and nonischemic injury represents an exaggerated response to sterile injury and promotes adverse cardiac remodeling and failure.

FUTURE DIRECTIONS

Pilot clinical trials have explored blockade of the inflammasome-derived IL-1β and have shown beneficial effects on cardiac function. Additional clinical studies testing this approach are warranted. Moreover, specific inflammasome inhibitors that are ready for clinical use are currently lacking.

Interleukin-1 in cardiac injury, repair, and remodeling: pathophysiologic and translational concepts

In the infarcted myocardium, necrotic cardiomyocytes release danger signals activating an intense inflammatory reaction that serves to clear the wound from dead cells and matrix debris, but may also extend injury. A growing body of evidence suggests an important role for members of the Interleukin (IL)-1 family in injury, repair and remodeling of the infarcted heart. This review manuscript discusses the pathophysiologic functions of IL-1 in the infarcted and remodeling myocardium and its potential role as a therapeutic target in patients with myocardial infarction. Dead cardiomyocytes release IL-1a that may function as a crucial alarmin triggering the post-infarction inflammatory reaction. IL-1b is markedly upregulated in the infarcted myocardium; activation of the inflammasome in both cardiomyocytes and interstitial cells results in release of bioactive IL-1b in the infarcted area. Binding of IL-1 to the type 1 receptor triggers an inflammatory cascade, inducing recruitment of pro-inflammatory leukocytes and stimulating a matrix-degrading program in fibroblasts, while delaying myofibroblast conversion. IL-1 mediates dilative remodeling following infarction and may play a role in the pathogenesis of post-infarction heart failure. As the wound is cleared from dead cells and matrix debris, endogenous inhibitory signals suppress the IL-1 response resulting in repression of inflammation and resolution of the inflammatory infiltrate. Other members of the IL-1 family (such as IL-18 and IL-33) are also implicated in regulation of the inflammatory and reparative response following myocardial infarction. IL-18 may participate in pro-inflammatory signaling, whereas IL-33 may exert cytoprotective effects. Early clinical trials suggest that IL-1 blockade may be a promising therapeutic strategy for patients with myocardial infarction.

Interleukin-18 increases TLR4 and mannose receptor expression and modulates cytokine production in human monocytes

Interleukin-18 is a proinflammatory cytokine belonging to the interleukin-1 family of cytokines. This cytokine exerts many unique biological and immunological effects. To explore the role of IL-18 in inflammatory innate immune responses, we investigated its impact on expression of two toll-like receptors (TLR2 and TLR4) and mannose receptor (MR) by human peripheral blood monocytes and its effect on TNF-α, IL-12, IL-15, and IL-10 production. Monocytes from healthy donors were stimulated or not with IL-18 for 18 h, and then the TLR2, TLR4, and MR expression and intracellular TNF-α, IL-12, and IL-10 production were assessed by flow cytometry and the levels of TNF-α, IL-12, IL-15, and IL-10 in culture supernatants were measured by ELISA. IL-18 treatment was able to increase TLR4 and MR expression by monocytes. The production of TNF-α and IL-10 was also increased by cytokine treatment. However, IL-18 was unable to induce neither IL-12 nor IL-15 production by these cells. Taken together, these results show an important role of IL-18 on the early phase of inflammatory response by promoting the expression of some pattern recognition receptors (PRRs) that are important during the microbe recognition phase and by inducing some important cytokines such as TNF-α and IL-10.

Effects of statins on TH1 modulating cytokines in human subjects

Background. Activation of the innate immune system by cholesterol accelerates atherosclerosis. High levels or modified forms of cholesterol stimulate release of the inflammatory cytokines IL-12 and IL-18 that synergistically stimulate T lymphocytes to produce the atherogenic cytokine interferon-γ. While activation of the innate immune system by cholesterol is well-described in animal models and human subjects with high cholesterol levels or known atherosclerotic disease, the interaction of cholesterol and lipoproteins with the innate immune system in human subjects without known atherosclerosis is less well-described. The goal of our study was to assess the T_H1 modulating cytokines IL-12 p40 and IL-18, and their counter regulatory cytokines IL-18 binding protein and IL-27, to determine if their levels are linked to cholesterol levels or other factors.

Methods. We performed a blinded, randomized hypothesis-generating study in human subjects without known atherosclerotic disease. We measured serum lipids, lipoprotein levels, and collected plasma samples at baseline. Subjects were randomized to two weeks of therapy with atorvastatin, pravastatin, or rosuvastatin. Lipids and cytokine levels were measured after two weeks of statin treatment. Subjects were given a four-week statin-free period. At the end of the four-week statin-free period, venous blood was sampled again to determine if serum lipids returned to within 5% of their pre-statin levels. When lipid levels returned to baseline, subjects were again treated with the next statin in the randomization scheme. IL-12, IL-18, IL-18 binding protein, and IL-27 were measured at baseline and after each statin treatment to determine effects of statin treatment on their blood levels, and identify correlations with lipids and lipoproteins.

Results. Therapy with statins revealed no significant change in the levels of IL-12, IL-18, IL-18 binding protein or IL-27 levels. We found that IL-18 levels positively correlate with total cholesterol levels (r² = 0.15, p < 0.03), but not HDL or LDL cholesterol. In contrast, IL-12 p40 levels inversely correlated with total cholesterol (r² = −0.17, p < 0.008), HDL cholesterol (r² = −0.22, p < 0.002), and apolipoprotein A1 (r² = −0.21, p < 0.002). Similarly, IL-18 binding protein levels inversely correlated with apolipoprotein A1 levels (r² = −0.13, p < 0.02).

Conclusions. Our findings suggest that total cholesterol levels positively regulate IL-18, while HDL cholesterol and apolipoprotein A1 may reduce IL-12 p40 and IL-18 binding protein levels. Additional studies in a larger patient population are needed to confirm these findings, and verify mechanistically whether HDL cholesterol can directly suppress IL-12 p40 and IL-18 binding protein levels in human subjects.