The role of IL-1 in the pathogenesis of heart disease

Involvement of cytokines in the modulation and progression of renal fibrosis induced by unilateral ureteral obstruction in C57BL/6 mice: effects of thalidomide and dexamethasone

This study investigated the kinetics of cytokines that are involved in the development of interstitial fibrosis in mice that were subjected to UUO, the interstitial type I and III collagen deposition, and the effects of Thalido and Dexa treatment on these parameters. Inbred C57BL/6 mice were divided into the groups: Normal (not submitted surgery), Sham (sham surgery), Control (UUO treated with 0.5% carboxymethyl cellulose), Thalido (UUO treated with 5 mg/kg thalidomide), and Dexa (UUO treated with 1 mg/kg dexamethasone). The treatments began the day before surgery and were administered once daily by gavage for 1, 7, or 14 days. At the end of each treatment period, blood samples were collected for the determination of creatinine, urea, cytokines. The Control group exhibited a increase in creatinine concentration compared with the Normal and Sham groups within the first 24 h after UUO, which remained high until days 7 and 14. The urea concentration was higher on days 7 and 14 in the Control group compared with the Sham group. In the Thalido and Dexa groups, a reduction of serum creatinine concentration was seen on day 14. Treatment with Dexa reduced the serum concentration of urea on day 7. The serum concentrations of cytokines (TNF-α, IL-1β, IL-6, IL-10 and IL-17) and chemokines (KC, MIG, bFGF) increased in UUO mice at all of the sampling times. The Dexa and Thalido groups exhibited alterations in the concentrations of these cytokines, suggesting the involvement of anti-inflammatory and immunomodulatory mechanisms that may have modified the fibrosis framework.

Targeting Interleukin-1β Reduces Leukocyte Production After Acute Myocardial Infarction

BACKGROUND

Myocardial infarction (MI) is an ischemic wound that recruits millions of leukocytes. MI-associated blood leukocytosis correlates inversely with patient survival, yet the signals driving heightened leukocyte production after MI remain incompletely understood.

METHODS AND RESULTS

With the use of parabiosis surgery, this study shows that soluble danger signals, among them interleukin-1β, increase bone marrow hematopoietic stem cell proliferation after MI. Data obtained in bone marrow reconstitution experiments reveal that interleukin-1β enhances hematopoietic stem cell proliferation by both direct actions on hematopoietic cells and through modulation of the bone marrow's hematopoietic microenvironment. An antibody that neutralizes interleukin-1β suppresses these effects. Anti-interleukin-1β treatment dampens the post-MI increase in hematopoietic stem cell proliferation. Consequently, decreased leukocyte numbers in the blood and infarct reduce inflammation and diminish post-MI heart failure in ApoE(-/-) mice with atherosclerosis.

CONCLUSIONS

The presented insight into post-MI bone marrow activation identifies a mechanistic target for muting inflammation in the ischemically damaged heart.

Inflammatory and fibrotic responses of cardiac fibroblasts to myocardial damage associated molecular patterns (DAMPs)

Cardiac fibroblasts (CF) are well-established as key regulators of extracellular matrix (ECM) turnover in the context of myocardial remodelling and fibrosis. Recently, this cell type has also been shown to act as a sensor of myocardial damage by detecting and responding to damage-associated molecular patterns (DAMPs) upregulated with cardiac injury. CF express a range of innate immunity pattern recognition receptors (TLRs, NLRs, IL-1R1, RAGE) that are stimulated by a host of different DAMPs that are evident in the injured or remodelling myocardium. These include intracellular molecules released by necrotic cells (heat shock proteins, high mobility group box 1 protein, S100 proteins), proinflammatory cytokines (interleukin-1α), specific ECM molecules up-regulated in response to tissue injury (fibronectin-EDA, tenascin-C) or molecules modified by a pathological environment (advanced glycation end product-modified proteins observed with diabetes). DAMP receptor activation on fibroblasts is coupled to altered cellular function including changes in proliferation, migration, myofibroblast transdifferentiation, ECM turnover and production of fibrotic and inflammatory paracrine factors, which directly impact on the heart's ability to respond to injury. This review gives an overview of the important role played by CF in responding to myocardial DAMPs and how the DAMP/CF axis could be exploited experimentally and therapeutically.

Time course of cardiac inflammation during nitric oxide synthase inhibition in SHR: impact of prior transient ACE inhibition

We have previously demonstrated that angiotensin-converting enzyme (ACE) inhibition with enalapril produces persistent effects that protect against future nitric oxide synthase (NOS) inhibitor (L-arginine methyl ester, L-NAME)-induced cardiac dysfunction and outer wall collagen deposition in spontaneously hypertensive rats (SHR). In the present study, we dissect the cytokine/chemokine release profile during NOS inhibition, its correlation to pathological cardiac remodeling and the impact of transient ACE inhibition on these effects. Adult male SHR were treated with enalapril (E+L) or tap water (C+L) for 2 weeks followed by a 2-week washout period. Rats were then subjected to 0, 3, 7 or 10 days of L-NAME treatment. The temporal response to NOS inhibition was evaluated by measuring arterial pressure, cardiac remodeling and cytokine/chemokine levels. L-NAME equivalently increased blood pressure and myocardial and vascular injury in C+L and E+L rats. However, pulse pressure (PP) was only transiently altered in C+L rats. The levels of several inflammatory mediators were increased during L-NAME treatment. However, interleukin-6 (IL-6) and IL-10 and monocyte chemoattractant protein-1 were uniquely increased in C+L hearts; whereas IL-4 and fractalkine were only elevated in E+L hearts. By days 7 and 10 of L-NAME treatment, there was a significant increase in the cardiac density of macrophages and proliferating cells, respectively only in C+L rats. Although myocardial injury was similar in both treatment groups, PP was not changed and there was a distinct cardiac chemokine/cytokine signature in rats previously treated with enalapril that may be related to the lack of proliferative response and macrophage infiltration in these hearts.

Pathophysiology of Myocardial Infarction

Myocardial infarction is defined as sudden ischemic death of myocardial tissue. In the clinical context, myocardial infarction is usually due to thrombotic occlusion of a coronary vessel caused by rupture of a vulnerable plaque. Ischemia induces profound metabolic and ionic perturbations in the affected myocardium and causes rapid depression of systolic function. Prolonged myocardial ischemia activates a "wavefront" of cardiomyocyte death that extends from the subendocardium to the subepicardium. Mitochondrial alterations are prominently involved in apoptosis and necrosis of cardiomyocytes in the infarcted heart. The adult mammalian heart has negligible regenerative capacity, thus the infarcted myocardium heals through formation of a scar. Infarct healing is dependent on an inflammatory cascade, triggered by alarmins released by dying cells. Clearance of dead cells and matrix debris by infiltrating phagocytes activates anti-inflammatory pathways leading to suppression of cytokine and chemokine signaling. Activation of the renin-angiotensin-aldosterone system and release of transforming growth factor-β induce conversion of fibroblasts into myofibroblasts, promoting deposition of extracellular matrix proteins. Infarct healing is intertwined with geometric remodeling of the chamber, characterized by dilation, hypertrophy of viable segments, and progressive dysfunction. This review manuscript describes the molecular signals and cellular effectors implicated in injury, repair, and remodeling of the infarcted heart, the mechanistic basis of the most common complications associated with myocardial infarction, and the pathophysiologic effects of established treatment strategies. Moreover, we discuss the implications of pathophysiological insights in design and implementation of new promising therapeutic approaches for patients with myocardial infarction.

Granulysin Expression in Lymphocytes that Populate the Peripheral Blood and the Myocardium after an Acute Coronary Event

We aimed to analyse granulysin (GNLY)-mediated cytotoxicity in the peripheral blood of patients with non-ST-segment elevation myocardial infarction (NSTEMI) treated with anti-ischaemic drug therapy. Thirty-nine NSTEMI patients with a median age of 70 years and 28 age-matched healthy subjects were enrolled in this study. On day 7 after MI, the number of GNLY(+) lymphocytes in the peripheral blood increased approximately six-fold of that in the healthy subjects, measured by flow cytometry. On day 14, the number of GNLY(+) cells significantly decreased in T, NKT, and both CD56(+dim) and CD56(+bright) NK subsets. GNLY(+) CD3(+) and GNLY(+) CD56(+) cells infiltrated central zone of myocardial infarction (MI). In persons who died in the first week after MI, GNLY(+) cells were found within accumulation of apoptotic leucocytes and reached the apoptotic cardiomyocytes in border MI zones probably due to the influence of interleukin-15 in peri-necrotic cardiomyocytes, as it is was shown by immunohistology. By day 28, the percentage of GNLY(+) lymphocytes in peripheral blood returned to the levels similar to that of the healthy subjects. Anti-GNLY mAb decreased apoptosis of K562 targets using peripheral blood NK cells from days 7 and 28 after MI, while in assays using cells from days 1 and 21, both anti-GNLY and anti-perforin mAbs were required to significantly decrease apoptosis. Using NK cells from day 14, K562 apoptosis was nearly absent. In conclusion, it seems that GNLY(+) lymphocytes, probably attracted by IL-15, not only participate partially in myocardial cell apoptosis, but also hasten resolution of cardiac leucocyte infiltration in patients with NSTEMI.

In vitro models for the study of osteoarthritis

Osteoarthritis (OA) is a prevalent disease of most mammalian species and is a significant cause of welfare and economic morbidity in affected individuals and populations. In vitro models of osteoarthritis are vital to advance research into the causes of the disease, and the subsequent design and testing of potential therapeutics. However, a plethora of in vitro models have been used by researchers but with no consensus on the most appropriate model. Models attempt to mimic factors and conditions which initiate OA, or dissect the pathways active in the disease. Underlying uncertainty as to the cause of OA and the different attributes of isolated cells and tissues used mean that similar models may produce differing results and can differ from the naturally occurring disease. This review article assesses a selection of the in vitro models currently used in OA research, and considers the merits of each. Particular focus is placed on the more prevalent cytokine stimulation and load-based models. A brief review of the mechanism of these models is given, with their relevance to the naturally occurring disease. Most in vitro models have used supraphysiological loads or cytokine concentrations (compared with the natural disease) in order to impart a timely response from the cells or tissue assessed. Whilst models inducing OA-like pathology with a single stimulus can answer important biological questions about the behaviour of cells and tissues, the development of combinatorial models encompassing different physiological and molecular aspects of the disease should more accurately reflect the pathogenesis of the naturally occurring disease.

Role of angiotensin II in experimental Venezuelan equine encephalitis in rats

Venezuelan equine encephalitis (VEE) is a viral disease transmitted by mosquitoes. The inflammation induced by the VEE virus is associated with a high mortality rate in mice. Angiotensin II (Ang II), a pro-inflammatory molecule, is produced in the normal rat brain. There is no information about the role of this molecule in the inflammatory events occurring during VEE and the effect of inflammation on the mortality rate in VEE-virus-infected rats. This study was designed to determine the role of Ang II in VEE and to analyze the effect of inflammation on mortality in infected rats. Two groups of rats were studied: 1) Virus-infected animals and controls (n = 60) were treated with losartan (a blocker of the Ang II-AT1 receptor) or with pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB) or left untreated and analyzed for morbidity and mortality. 2) Animals treated using the same protocol (n = 30) were sacrificed at day 4 postinfection and analyzed by immunohistochemistry and histopathology and for cytokine production. Increased expression of Ang II, ICAM-1, ED-1 and cytokines (IL-1α, MCP-1, IL-6 and IL-10) in infected animals was observed. The main histopathology findings were dilated capillaries and capillaries with endothelial detachment. Losartan and PDTC reduced the expression of IL-1α, MCP-1, and IL-10, and the number of dilated capillaries and capillaries with endothelial detachment. Survival analysis showed that 100% mortality was reached earlier in infected rats treated with losartan (day 14) or PDTC (day 11) than in untreated animals (day 19). These findings suggest that Ang II plays a role in VEE and that brain inflammation is protective against viral infection.

Cross talk of the first-line defense TLRs with PI3K/Akt pathway, in preconditioning therapeutic approach

Toll-like receptor family (TLRs), pattern recognition receptors, is expressed not only on immune cells but also on non-immune cells, including cardiomyocytes, fibroblasts, and vascular endothelial cells. One main function of TLRs in the non-immune system is to regulate apoptosis. TLRs are the central mediators in hepatic, pulmonary, brain, and renal ischemic/reperfusion (I/R) injury. Up-regulation of TLRs and their ligation by either exogenous or endogenous danger signals plays critical roles in ischemia/reperfusion-induced tissue damage. Conventional TLR-NF-κB pathways are markedly activated in failing and ischemic myocardium. Recent studies have identified a cross talk between TLR activation and the PI3K/Akt pathway. The activation of TLRs is proposed to be the most potent preconditioning method after ischemia, to improve the cell survival via the mechanism involved the PI3K/Akt signaling pathway and to attenuate the subsequent TLR-NF-κB pathway stimulation. Thus, TLRs could be a great target in the new treatment approaches for myocardial I/R injury.

Cross talk of the first-line defense TLRs with PI3K/Akt pathway, in preconditioning therapeutic approach

Toll-like receptor family (TLRs), pattern recognition receptors, is expressed not only on immune cells but also on non-immune cells, including cardiomyocytes, fibroblasts, and vascular endothelial cells. One main function of TLRs in the non-immune system is to regulate apoptosis. TLRs are the central mediators in hepatic, pulmonary, brain, and renal ischemic/reperfusion (I/R) injury. Up-regulation of TLRs and their ligation by either exogenous or endogenous danger signals plays critical roles in ischemia/reperfusion-induced tissue damage. Conventional TLR-NF-κB pathways are markedly activated in failing and ischemic myocardium. Recent studies have identified a cross talk between TLR activation and the PI3K/Akt pathway. The activation of TLRs is proposed to be the most potent preconditioning method after ischemia, to improve the cell survival via the mechanism involved the PI3K/Akt signaling pathway and to attenuate the subsequent TLR-NF-κB pathway stimulation. Thus, TLRs could be a great target in the new treatment approaches for myocardial I/R injury.

Role of inflammation in the pathogenesis of heart failure with preserved ejection fraction and its potential as a therapeutic target

Heart failure (HF) with preserved ejection fraction (HFPEF) is an increasingly prevalent clinical syndrome with many unresolved issues regarding diagnosis, pathophysiology, and treatment. The major pathophysiological mechanisms underlying HFPEF are known to be fibrosis and reduced ventricular compliance, and hypertension (HTN) is perhaps the most significant risk factor for the development of left ventricular diastolic dysfunction (LVDD). Inflammation is one of the earliest events in cardiac stress situations such as pressure and/or volume overload and involves elevated levels of endothelial adhesion molecules as well as increased production and release of inflammatory cytokines and chemokines in the tissue. The latter promotes the infiltration of activated inflammatory cells, particularly monocytes, into the cardiac tissue. Increased monocyte infiltration is seen in the early and late stages of HTN and HFPEF. Once inside the tissue, monocytes differentiate into macrophages and promote cardiac inflammation, tissue injury, and myocardial fibrosis. This review focuses on inflammation as the initial and primary trigger of ventricular remodelling in HTN and LVDD, affecting progression to HFPEF. The link between inflammation and b-type natriuretic peptide (BNP), a clinical marker of cardiac pressure overload which is positively associated with cardiac dysfunction and HF, is also described. Finally, current and prospective therapeutic approaches for HFPEF based on modification of the inflammatory response are reviewed.

Cardiovascular risk and the use of biologic agents in rheumatoid arthritis

Although patients with rheumatoid arthritis (RA) are recognized to be disproportionately impacted by cardiovascular disease (CVD), effective approaches of primary and secondary CVD prevention have not been well defined in this population. Given their robust disease-modifying potential and effects on both pro-inflammatory and pro-atherogenic pathways, there has been substantial speculation that biologic treatments may serve as a means of providing highly effective RA disease control while simultaneously reducing CVD risk in this high risk group. In this review, we examine available evidence relevant to the associations of approved biologic treatments with CVD outcomes in the context of RA.

Enhancer of zeste homolog-2 (EZH2) methyltransferase regulates transgelin/smooth muscle-22α expression in endothelial cells in response to interleukin-1β and transforming growth factor-β2

Smooth muscle-22α (SM22α), encoded by transgelin (TAGLN), is expressed in mesenchymal lineage cells, including myofibroblasts and smooth muscle cells. It is an F-actin binding protein that regulates the organization of actin cytoskeleton, cellular contractility and motility. SM22α is crucial for the maintenance of smooth muscle cell phenotype and its function. SM22α is also expressed in the processes of mesenchymal transition of epithelial (EMT) or endothelial cells (EndMT). The expression of TAGLN/SM22α is induced by transforming growth factor-β (TGFβ) signaling and enhanced by concomitant interleukin-1β (IL-1β) signaling. We investigated the epigenetic regulation of TAGLN expression by enhancer of zeste homolog-2 (EZH2), the methyltransferase of Polycomb, in the context of TGFβ and IL-1β signaling in endothelial cells. We demonstrate that the expression of EZH2 in endothelial cells was regulated by the inflammatory cytokine IL-1β. A decrease in both expression and activity of EZH2 led to an increase in TAGLN expression. Inhibition of EZH2 augmented TGFβ2-induced SM22α expression. The decrease of EZH2 levels in endothelial cells co-stimulated with IL-1β and TGFβ2 correlated with decreased H3K27me3 levels at the TAGLN proximal promoter. Moreover, the SM22α expression increased. Taken together, this suggests that EZH2 regulates the chromatin structure at the TAGLN promoter through tri-methylation of H3K27. EZH2 therefore acts as an epigenetic integrator of IL-1β and TGFβ2 signaling, providing an example of how cellular signaling can be resolved at the level of epigenetic regulation. Since IL-1β and TGFβ2 represent the pro-inflammatory and pro-fibrotic conditions during vascular fibroproliferative disease, we surmise that EZH2, as the molecule that integrates their signaling, could also be a promising target for development of future therapy.

Pathways involved in interleukin-1β-mediated murine cardiomyocyte apoptosis

Accumulating evidence suggests that interleukin-1 (IL-1) signaling plays an essential role in the pathogenesis of heart failure by inducing cardiomyocyte apoptosis, but the mechanisms of this process are poorly defined. We further explored these molecular pathways. We isolated cardiomyocytes from neonatal mice and then cultured and stimulated them with murine IL-1β in vitro. Cell apoptotic ratios were measured by means of flow cytometry. Expression of effector molecules was analyzed by means of enzyme-linked immunosorbent assay, Western blotting, and real-time quantitative polymerase chain reaction. The results showed that IL-1β induced murine cardiomyocyte apoptosis through a release of cytochrome c into cytoplasm and through caspase 3 activation. Simultaneously, IL-1β signaling promoted expression of endonuclease G and high-temperature requirement protein A2 messenger RNA. Survivin and X-linked inhibitors of apoptosis protein (IAP), members of the IAP family, were inhibited on the messenger RNA level during IL-1β-mediated cardiomyocyte apoptosis. We found that IL-1β signaling during cardiomyocyte apoptosis in vitro induced the activation of caspase-dependent and caspase-independent pathways, and inhibited IAPs. Understanding the molecular mechanisms involved in IL-1β-mediated cardiomyocyte apoptosis might assist in the design of therapeutic approaches to protect cardiomyocyte function and prevent heart failure.

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.

Inflammatory markers in ST-elevation acute myocardial infarction

After acute myocardial infarction, ventricular remodeling is characterized by changes at the molecular, structural, geometrical and functional level that determine progression to heart failure. Inflammation plays a key role in wound healing and scar formation, affecting ventricular remodeling. Several, rather different, components of the inflammatory response were studied as biomarkers in ST-elevation acute myocardial infarction. Widely available and inexpensive tests, such as leukocyte count at admission, as well as more sophisticated immunoassays provide powerful predictors of adverse outcome in patients with ST-elevation acute myocardial infarction. We review the value of inflammatory markers in ST-elevation acute myocardial infarction and their association with ventricular remodeling, heart failure and sudden death. In conclusion, the use of these biomarkers may identify subjects at greater risk of adverse events and perhaps provide an insight into the mechanisms of disease progression.

Exogenous H2S protects H9c2 cardiac cells against high glucose-induced injury and inflammation by inhibiting the activation of the NF-κB and IL-1β pathways

Hyperglycemia has been reported to activate the nuclear factor-κB (NF-κB) pathway. We have previously demonstrated that exogenous hydrogen sulfide (H2S) protects cardiomyocytes against high glucose (HG)-induced injury by inhibiting the activity of p38 mitogen-activated protein kinase (MAPK), which can activate the NF-κB pathway and induce interleukin (IL)-1β production. In the present study, we aimed to investigate the hypothesis that exogenous H2S protects cardiomyocytes against HG-induced injury and inflammation through the inhibition of the NF-κB/IL-1β pathway. H9c2 cardiac cells were treated with 35 mM glucose (HG) for 24 h to establish a model of HG-induced damage. Our results demonstrated that treatment of the cells with 400 µM sodium hydrogen sulfide (NaHS, a donor of H2S) or 100 µM pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB) for 30 min prior to exposure to HG markedly attenuated the HG-induced increase in the expression levels of the phosphorylated (p)-NF-κB p65 subunit. Notably, pre-treatment of the H9c2 cardiac cells with NaHS or PDTC significantly suppressed the HG-induced injury, including cytotoxicity, apoptosis, oxidative stress and mitochondrial insults, as evidenced by an increase in cell viability, as well as a decrease in the number of apoptotic cells, the expression of cleaved caspase-3, the generation of reactive oxygen species (ROS) and the dissipation of mitochondrial membrane potential (MMP). In addition, pre-treatment of the cells with NaHS or PDTC ameliorated the HG-induced inflammatory response, leading to a decrease in the levels of IL-1β, IL-6 and tumor necrosis factor-α (TNF-α). Importantly, co-treatment of the H9c2 cells with 20 ng/ml IL-1 receptor antagonist (IL-1Ra) and HG markedly reduced the HG-induced increase in p-NF-κB p65 expression, cytotoxicity, the number of apoptotic cells, as well as the production of TNF-α. In conclusion, the present study presents novel mechanistic evidence that exogenous H2S protects H9c2 cardiac cells against HG-induced inflammation and injury, including cytotoxicity, apoptosis, overproduction of ROS and the dissipation of MMP, by inhibiting the NF-κB/IL-1β pathway. We also provide new data indicating that the positive interaction between the NF-κB pathway and IL-1β is critical in HG-induced injury and inflammation in H9c2 cardiac cells.

The immune system and the remodeling infarcted heart: cell biological insights and therapeutic opportunities

Extensive necrosis of ischemic cardiomyocytes in the infarcted myocardium activates the innate immune response triggering an intense inflammatory reaction. Release of danger signals from dying cells and damaged matrix activates the complement cascade and stimulates Toll-like receptor/interleukin-1 signaling, resulting in the activation of the nuclear factor-κB system and induction of chemokines, cytokines, and adhesion molecules. Subsequent infiltration of the infarct with neutrophils and mononuclear cells serves to clear the wound from dead cells and matrix debris, while stimulating reparative pathways. In addition to its role in repair of the infarcted heart and formation of a scar, the immune system is also involved in adverse remodeling of the infarcted ventricle. Overactive immune responses and defects in suppression, containment, and resolution of the postinfarction inflammatory reaction accentuate dilative remodeling in experimental models and may be associated with chamber dilation, systolic dysfunction, and heart failure in patients surviving a myocardial infarction. Interventions targeting the inflammatory response to attenuate adverse remodeling may hold promise in patients with myocardial infarction that exhibit accentuated, prolonged, or dysregulated immune responses to the acute injury.

Inflammation revisited: inflammation versus resolution of inflammation following myocardial infarction

Myocardial infarction (MI) is the main cause for the progression of the left ventricle towards congestive heart failure. The optimal healing after MI requires timely induction and resolution of inflammation. Primarily, there have been a number of strategies applied to inhibit the post-MI inflammation but approaches that focus on the resolution of inflammation have sparsely been used in the treatment of heart failure. The early attempts to inhibit post-MI inflammation resulted in adverse outcomes that were realized in heart failure trials. We provide here an overview on the cyclooxygenase (COX)- and lipoxygenase (LOX)-derived lipid mediators that are either impairing or resolving the post-MI inflammation. With the evolution of lipidomics there has been emerging novel bioactive-specialized lipid mediators that promise to resolve chronic inflammation rather than promoting inhibition. The current review is focused on post-MI immune cells kinetics and the unexplored array of lipid mediators that are coordinated by COX and LOX. Thus, an emphasis on COX and LOX poses key questions and potential for the development of novel targets in the heart failure treatment strategy. This updated dynamic approach aims to fuse basic pre-clinical discoveries and translational bioactive lipid-based resolvin discoveries that could be potentially used in the clinic for the treatment of heart failure.

The IL-1 family in fish: swimming through the muddy waters of inflammasome evolution

Inflammatory diseases are a significant burden on global healthcare systems, and tackling these diseases is a major focus of modern medicine. Key to many inflammatory diseases is the cytokine, Interleukin-1 (IL-1). Due to its apical role in initiating the inflammatory response, dysregulated IL-1 signalling results in a number of pathologies. Treatment of inflammatory diseases with anti-IL-1 therapies has offered many therapeutic benefits, however current therapies are protein based, with all the accompanying limitations. The non-conventional pathways involved in IL-1 signalling provide a number of potential therapeutic targets for clinical intervention and this has led to the exploitation of a number of model organisms for the study of IL-1 biology. Murine models have long been used to study IL-1 processing and release, but do not allow direct visualisation in vivo. Recently, fish models have emerged as genetically tractable and optically transparent inflammatory disease models. These models have raised questions on the evolutionary origins of the IL-1 family and the conservation in its processing and activation. Here we review the current understanding of IL-1 evolution in fish and discuss the study of IL-1 processing in these models.

Cross Talk Between Vascular Smooth Muscle Cells and Monocytes Through Interleukin-1β/Interleukin-18 Signaling Promotes Vein Graft Thickening

Objective—

Interleukin (IL)-1β and IL-18 are key proinflammatory cytokines that play important roles in the pathophysiology of vein graft remodeling. However, the mechanism of IL-1β/IL-18 production and its role in the development of graft remodeling remain unclear.

Approach and Results—

IL-1β/IL-18 were rapidly expressed in venous interposition grafts. Vascular smooth muscle cell (VSMC) death and monocytic inflammasome activation occurred in grafted veins. Necrotic VSMCs induced the expression of IL-1β, IL-18, and other inflammasome-associated proteins in monocytes, which was partially inhibited by their antagonist, recombinant IL-1ra-Fc-IL-18bp. Activated monocytes stimulated proliferation of VSMCs by activating cell growth–related signaling molecules (AKT, STAT3, ERK1/2, and mTOR [AKT/protein kinase B, signal transducer and activator of transcription 3, extracellular signal-regulated kinase 1/2, mammalian target of rapamycin]) and increasing production of platelet-derived growth factor-bb; these effects were suppressed by IL-1ra-Fc-IL-18bp. Activated monocytes also promoted migration of VSMCs, which was independent of IL-1β/IL-18 signaling. Importantly, administration of IL-1ra-Fc-IL-18bp inhibited activation of cell growth–related signaling molecules, VSMC proliferation, and vein graft thickening in vivo.

Conclusions—

Our work identified an interaction among necrotic VSMCs, monocytes, and viable VSMCs through IL-1β/IL-18 signaling, which might be exploited as a therapeutic target in vein graft remodeling.

NLRP3 gene silencing ameliorates diabetic cardiomyopathy in a type 2 diabetes rat model

BACKGROUND

Nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) inflammasome is associated with metabolic disorder and cell death, which are important triggers in diabetic cardiomyopathy (DCM). We aimed to explore whether NLRP3 inflammasome activation contributes to DCM and the mechanism involved.

METHODS

Type 2 diabetic rat model was induced by high fat diet and low dose streptozotocin. The characteristics of type 2 DCM were evaluated by metabolic tests, echocardiography and histopathology. Gene silencing therapy was used to investigate the role of NLRP3 in the pathogenesis of DCM. High glucose treated H9c2 cardiomyocytes were used to determine the mechanism by which NLRP3 modulated the DCM. The cell death in vitro was detected by TUNEL and EthD-III staining. TXNIP-siRNA and pharmacological inhibitors of ROS and NF-kB were used to explore the mechanism of NLRP3 inflammasome activation.

RESULTS

Diabetic rats showed severe metabolic disorder, cardiac inflammation, cell death, disorganized ultrastructure, fibrosis and excessive activation of NLRP3, apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), pro-caspase-1, activated caspase-1 and mature interleukin-1β (IL-1β). Evidence for pyroptosis was found in vivo, and the caspase-1 dependent pyroptosis was found in vitro. Silencing of NLRP3 in vivo did not attenuate systemic metabolic disturbances. However, NLRP3 gene silencing therapy ameliorated cardiac inflammation, pyroptosis, fibrosis and cardiac function. Silencing of NLRP3 in H9c2 cardiomyocytes suppressed pyroptosis under high glucose. ROS inhibition markedly decreased nuclear factor-kB (NF-kB) phosphorylation, thioredoxin interacting/inhibiting protein (TXNIP), NLRP3 inflammasome, and mature IL-1β in high glucose treated H9c2 cells. Inhibition of NF-kB reduced the activation of NLRP3 inflammasome. TXNIP-siRNA decreased the activation of caspase-1 and IL-1β.

CONCLUSION

NLRP3 inflammasome contributed to the development of DCM. NF-κB and TXNIP mediated the ROS-induced caspase-1 and IL-1β activation, which are the effectors of NLRP3 inflammasome. NLRP3 gene silencing may exert a protective effect on DCM.

5TNF-α and IL-1β neutralization ameliorates angiotensin II-induced cardiac damage in male mice

Inflammation is a key event in hypertensive organ damage, and TNF-α and IL-1β are elevated in hypertension. In this study, we evaluated the effects of TNF-α and IL-1β elevation on hypertensive cardiac damage by treatment with a bifunctional inflammatory inhibitor, TNF receptor 2-fragment crystalization-IL-1 receptor antagonist (TFI), which can neutralize these 2 cytokines simultaneously. A mouse hypertension model of angiotensin II (Ang II) infusion (1500 ng/kg·min for 7 d) was induced in wild-type mice. TNF-α and IL-1β were inhibited by TFI administration (5 mg/kg, every other day), the effects of inhibition on cardiac damage were examined, and its mechanism on inflammatory infiltration was further studied in vivo and in vitro. Ang II infusion induced cardiac injury, including increased macrophage infiltration, expression of inflammatory cytokines (IL-12, IL-6, etc), and cardiac fibrosis, such as elevated α-smooth muscle actin, collagen I, and TGF-β expression. Importantly, the Ang II-induced cardiac injury was suppressed by TFI treatment. Moreover, TFI reduced the expression of adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) and monocyte chemotactic protein-1 expression in Ang II-treated hearts. Additionally, blockade of TNF-α and IL-1β by TFI reduced monocyte adherence to endothelia cell and macrophage migration. This study demonstrates that blocking TNF-α and IL-1β by TFI prevents cardiac damage in response to Ang II, and targeting these 2 cytokines simultaneously might be a novel tool to treat hypertensive heart injury.

Interaction between interleukin-1 beta and angiotensin II receptor 1 in hypothalamic paraventricular nucleus contributes to progression of heart failure

The central mechanisms by which interleukin-1 beta (IL-1β) and angiotension II receptor 1 (AT1-R) contribute to sympathoexcitation in heart failure (HF) are unclear. In this study, we determined whether an interaction between IL-1β and AT1-R in the paraventricular nucleus (PVN) contributes to progression of HF. Rats were implanted with bilateral PVN cannulae and subjected to coronary artery ligation or sham surgery (Sham). Subsequently, animals were treated for 4 weeks through PVN infusion with either vehicle, losartan (LOS, 200 μg/day), IL-1β (IL, 1 μg/day), or IL-1β along with LOS (LOS+IL). HF rats had higher levels of corticotropin-releasing hormone (CRH), norepinephrine (NE), and glutamate (Glu); lower levels of gamma-aminobutyric acid (GABA); and more positive fra-like activity in PVN when compared with Sham rats. HF rats also had higher levels of NE, epinephrine (EPI), and IL-1β in plasma. PVN infusion of LOS attenuated the decreases in GABA and the increases in CRH, NE, and Glu in the PVN of HF rats. IL-1β could further increase the expression of CRH, NE, Glu, EPI, and IL-1β and decrease GABA expression. Treatment with IL-1β along with LOS could eliminate the effects of IL-1β. These findings suggest that an interaction between AT1-R and IL-1β in the PVN contributes to progression in HF.

Interleukin-1β attenuates myofibroblast formation and extracellular matrix production in dermal and lung fibroblasts exposed to transforming growth factor-β1

One of the most potent pro-fibrotic cytokines is transforming growth factor (TGFβ). TGFβ is involved in the activation of fibroblasts into myofibroblasts, resulting in the hallmark of fibrosis: the pathological accumulation of collagen. Interleukin-1β (IL1β) can influence the severity of fibrosis, however much less is known about the direct effects on fibroblasts. Using lung and dermal fibroblasts, we have investigated the effects of IL1β, TGFβ1, and IL1β in combination with TGFβ1 on myofibroblast formation, collagen synthesis and collagen modification (including prolyl hydroxylase, lysyl hydroxylase and lysyl oxidase), and matrix metalloproteinases (MMPs). We found that IL1β alone has no obvious pro-fibrotic effect on fibroblasts. However, IL1β is able to inhibit the TGFβ1-induced myofibroblast formation as well as collagen synthesis. Glioma-associated oncogene homolog 1 (GLI1), the Hedgehog transcription factor that is involved in the transformation of fibroblasts into myofibroblasts is upregulated by TGFβ1. The addition of IL1β reduced the expression of GLI1 and thereby also indirectly inhibits myofibroblast formation. Other potentially anti-fibrotic effects of IL1β that were observed are the increased levels of MMP1, −2, −9 and −14 produced by fibroblasts exposed to TGFβ1/IL1β in comparison with fibroblasts exposed to TGFβ1 alone. In addition, IL1β decreased the TGFβ1-induced upregulation of lysyl oxidase, an enzyme involved in collagen cross-linking. Furthermore, we found that lung and dermal fibroblasts do not always behave identically towards IL1β. Suppression of COL1A1 by IL1β in the presence of TGFβ1 is more pronounced in lung fibroblasts compared to dermal fibroblasts, whereas a higher upregulation of MMP1 is seen in dermal fibroblasts. The role of IL1β in fibrosis should be reconsidered, and the differences in phenotypical properties of fibroblasts derived from different organs should be taken into account in future anti-fibrotic treatment regimes.

Interleukin-1β attenuates myofibroblast formation and extracellular matrix production in dermal and lung fibroblasts exposed to transforming growth factor-β1

One of the most potent pro-fibrotic cytokines is transforming growth factor (TGFβ). TGFβ is involved in the activation of fibroblasts into myofibroblasts, resulting in the hallmark of fibrosis: the pathological accumulation of collagen. Interleukin-1β (IL1β) can influence the severity of fibrosis, however much less is known about the direct effects on fibroblasts. Using lung and dermal fibroblasts, we have investigated the effects of IL1β, TGFβ1, and IL1β in combination with TGFβ1 on myofibroblast formation, collagen synthesis and collagen modification (including prolyl hydroxylase, lysyl hydroxylase and lysyl oxidase), and matrix metalloproteinases (MMPs). We found that IL1β alone has no obvious pro-fibrotic effect on fibroblasts. However, IL1β is able to inhibit the TGFβ1-induced myofibroblast formation as well as collagen synthesis. Glioma-associated oncogene homolog 1 (GLI1), the Hedgehog transcription factor that is involved in the transformation of fibroblasts into myofibroblasts is upregulated by TGFβ1. The addition of IL1β reduced the expression of GLI1 and thereby also indirectly inhibits myofibroblast formation. Other potentially anti-fibrotic effects of IL1β that were observed are the increased levels of MMP1, -2, -9 and -14 produced by fibroblasts exposed to TGFβ1/IL1β in comparison with fibroblasts exposed to TGFβ1 alone. In addition, IL1β decreased the TGFβ1-induced upregulation of lysyl oxidase, an enzyme involved in collagen cross-linking. Furthermore, we found that lung and dermal fibroblasts do not always behave identically towards IL1β. Suppression of COL1A1 by IL1β in the presence of TGFβ1 is more pronounced in lung fibroblasts compared to dermal fibroblasts, whereas a higher upregulation of MMP1 is seen in dermal fibroblasts. The role of IL1β in fibrosis should be reconsidered, and the differences in phenotypical properties of fibroblasts derived from different organs should be taken into account in future anti-fibrotic treatment regimes.

Anti-inflammatory strategies for ventricular remodeling following ST-segment elevation acute myocardial infarction

Acute myocardial infarction (AMI) leads to molecular, structural, geometric, and functional changes in the heart in a process known as ventricular remodeling. An intense organized inflammatory response is triggered after myocardial ischemia and necrosis and involves all components of the innate immunity, affecting both cardiomyocytes and noncardiomyocyte cells. Inflammation is triggered by tissue injury; it mediates wound healing and scar formation and affects ventricular remodeling. Many therapeutic attempts aimed at reducing inflammation in AMI during the past 3 decades presented issues of impaired healing or increased risk of cardiac rupture or failed to show any additional benefit in addition to standard therapies. More recent strategies aimed at selectively blocking one of the key factors upstream rather than globally suppressing the response downstream have shown some promising results in pilot trials. We herein review the pathophysiological mechanisms of inflammation and ventricular remodeling after AMI and the results of clinical trials with anti-inflammatory strategies.

Comparison the prognostic value of galectin-3 and serum markers of cardiac extracellular matrix turnover in patients with chronic systolic heart failure

BACKGROUND

Galectin-3 (Gal-3) shows the ability of survival prediction in heart failure (HF) patients. However, Gal-3 is strongly associated with serum markers of cardiac extracellular matrix (ECM) turnover. The aim of this study is to compare the impact of Gal-3 and serum markers of cardiac ECM turnover on prognostic prediction of chronic systolic HF patients.

METHODS

Serum Gal-3, brain natriuretic peptide (BNP), extracellular matrix including type I and III aminoterminal propeptide of procollagen (PINP and PIIINP), matrix metalloproteinase-2, 9 (MMP-2, 9), and tissue inhibitor of metalloproteinase-1 (TIMP-1) were analyzed. Cox regression analysis was used for survival analysis.

RESULTS

A total of 105 (81 male) patients were enrolled. During 980±346 days follow-up, 17 patients died and 36 episodes of HF admission happened. Mortality of these patients was significantly associated with the log PIIINP (β= 15.380; P=0.042), log TIMP-1(β= 44.530; P=0.003), log MMP-2 (β= 554.336; P<0.001), log BNP (β= 28.273; P=0.034). Log Gal-3 (β= 7.484; P=0.066) is borderline associated with mortality. Mortality or first HF admission of these patients was significantly associated with the log TIMP-1(β= 16.496; P=0.006), log MMP-2 (β= 221.864; P<0.001), log BNP (β= 5.999; P=0.034). Log Gal-3 (β= 4.486; P=0.095) only showed borderline significance. In several models adjusting clinical parameters, log MMP-2 was significantly associated with clinical outcome. In contrast, log Gal-3 was not.

CONCLUSION

The prognostic strength of MMP-2 to clinical outcome prediction in HF patients is stronger than Gal-3.

Heart failure with preserved ejection fraction: emerging drug strategies

Approximately half of heart failure patients have a normal ejection fraction, a condition designated as heart failure with preserved ejection fraction (HFpEF). This heart failure subtype disproportionately affects women and the elderly and is commonly associated with other cardiovascular comorbidities, such as hypertension and diabetes. HFpEF is increasing at a steady rate and is predicted to become the leading cause of heart failure within a decade. HFpEF is characterized by impaired diastolic function, thought to be due to concentric remodeling of the heart along with increased stiffness of both the extracellular matrix and myofilaments. In addition, oxidative stress and inflammation are thought to have a role in HFpEF progression, along with endothelial dysfunction and impaired nitric oxide-cyclic guanosine monophosphate-protein kinase G signaling. Surprisingly a number of clinical studies have failed to demonstrate any benefit of drugs effective in heart failure with systolic dysfunction in HFpEF patients. Thus, HFpEF is one of the largest unmet needs in cardiovascular medicine, and there is a substantial need for new therapeutic approaches and strategies that target mechanisms specific for HFpEF. This conclusion is underscored by the recently reported disappointing results of the RELAX trial, which assessed the use of phosphodiesterase-5 inhibitor sildenafil for treating HFpEF. In animal models, endothelial nitric oxide synthase activators and If current inhibitors have shown benefit in improving diastolic function, and there is a rationale for assessing matrix metalloproteinase 9 inhibitors and nitroxyl donors. LCZ696, a combination drug of angiotensin II receptor blocker and neprilysin inhibitor, and the aldosterone receptor antagonist spironolactone are currently in clinical trial for treating HFpEF. Here we present an overview of the etiology and diagnosis of HFpEF that segues into a discussion of new therapeutic approaches emerging from basic research and drugs currently in clinical trial that primarily target diastolic dysfunction or imbalanced ventricular-arterial coupling.

Targeting inflammation: impact on atherothrombosis

Atherothrombosis is a worldwide epidemic accounting for an unacceptable toll of deaths and disabilities. Its pathophysiology is complex and hardly referable to a specific mechanism; however, in the last 20 years, a growing amount of evidence has demonstrated that inflammatory processes play a major role from the very beginning to the ultimate complication of atherothrombosis. These evidences are addressing a growing interest toward anti-inflammatory agents as preventive or curative treatments of atherothrombosis. At present, accumulated data are not conclusive, but strong evidence exists in favor of an anti-inflammatory positive effect for several drugs as statins or renin-angiotensin inhibitors. More conclusive data are expected from ongoing trials directly exploring the role of specific cytokines antagonists.

Assessment and comparison of acute cardiac toxicity during high-dose cyclophosphamide and high-dose etoposide stem cell mobilization regimens with N-terminal pro-B-type natriuretic peptide

This study was undertaken to prospectively evaluate and compare the acute effect of high-dose (HD), cyclophosphamide (CY) and HD etoposide (ET) on cardiac function assessed by plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) in patients undergoing stem-cell mobilization. NT-proBNP was measured at baseline and 6h after completion of mobilization chemotherapy (MC) in 58 patients. Of 58 patients, 33 received HD CY, and 25 received HD ET. The mean baseline NT-proBNP values were similar between the CY and ET group (119.5 vs 149, respectively, p>0.05). NT-proBNP levels were increased in almost all patients, except 2 from CY group. A significant difference between NT-proBNP concentrations at baseline and 6h after completion of MC was observed in both groups (p<0.001). The value of changes in NT-proBNP was more significant in the ET group. The changes in NT-proBNP according to the MC regimens were analyzed and a cut-off value of 422pg/ml was determined. Based on this cut-off value, only the type of MC was significantly correlated with the chances in NT-proBNP concentrations. Receiving HD ET as a MC was found to be 5.25 times more cardiotoxic compared to the HD CY. Congestive heart failure was seen in 3 (5.2%) patients. Our results suggest that stem cell mobilization with HD CY and HD ET cause acute cardiac toxicity mediated by neurohumoral activation, which was detected by the increases in cardiac biomarker NT-proBNP, and as a matter of fact cardiotoxicity of HD ET seems to be more potent than those exhibited by HD CY.

Fibroblasts in myocardial infarction: a role in inflammation and repair

Fibroblasts do not only serve as matrix-producing reparative cells, but exhibit a wide range of functions in inflammatory and immune responses, angiogenesis and neoplasia. The adult mammalian myocardium contains abundant fibroblasts enmeshed within the interstitial and perivascular extracellular matrix. The current review manuscript discusses the dynamic phenotypic and functional alterations of cardiac fibroblasts following myocardial infarction. Extensive necrosis of cardiomyocytes in the infarcted heart triggers an intense inflammatory reaction. In the early stages of infarct healing, fibroblasts become pro-inflammatory cells, activating the inflammasome and producing cytokines, chemokines and proteases. Pro-inflammatory cytokines (such as Interleukin-1) delay myofibroblast transformation, until the wound is cleared from dead cells and matrix debris. Resolution of the inflammatory infiltrate is associated with fibroblast migration, proliferation, matrix protein synthesis and myofibroblast conversion. Growth factors and matricellular proteins play an important role in myofibroblast activation during the proliferative phase of healing. Formation of a mature cross-linked scar is associated with clearance of fibroblasts, as poorly-understood inhibitory signals restrain the fibrotic response. However, in the non-infarcted remodeling myocardium, local fibroblasts may remain activated in response to volume and pressure overload and may promote interstitial fibrosis. Considering their abundance, their crucial role in cardiac inflammation and repair, and their involvement in myocardial dysfunction and arrhythmogenesis, cardiac fibroblasts may be key therapeutic targets in cardiac remodeling. This article is part of a Special Issue entitled Myocyte-Fibroblast Signalling in Myocardium.

A pro-inflammatory role for nuclear factor kappa B in childhood obstructive sleep apnea syndrome

STUDY OBJECTIVES

Childhood obstructive sleep apnea syndrome (OSAS) is associated with an elevation of inflammatory markers such as C-reactive protein (CRP) that correlates with specific morbidities and subsides following intervention. In adults, OSAS is associated with activation of the transcription factor nuclear factor kappa B (NF-kB). We explored the mechanisms underlying NF-kB activation, based on the hypothesis that specific NF-kB signaling is activated in children with OSAS.

DESIGN

Adenoid and tonsillar tissues from children with OSAS and matched controls were immunostained against NF-kB classical (p65 and p50) and alternative (RelB and p52) pathway subunits, and NF-kB-dependent cytokines: interleukin (IL)- 1α, IL-1β, tumor necrosis factor-α, and IL-8). Serum CRP levels were measured in all subjects. NF-kB induction was evaluated by a luciferase-NF-kB reporter assay in L428 cells constitutively expressing NF-kB and in Jurkat cells with inducible NF-kB expression. p65 translocation to the nucleus, reflecting NF-kB activation, was measured in cells expressing fluorescent NF-kB-p65-GFP (green fluorescent protein).

SETTING

Sleep research laboratory.

PATIENTS OR PARTICIPANTS

Twenty-five children with OSAS and 24 without OSAS.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

Higher expression of IL-1α and classical NF-kB subunits p65 and p50 was observed in adenoids and tonsils of children with OSAS. Patient serum induced NF-kB activity, as measured by a luciferase-NF-kB reporter assay and by induction of p65 nuclear translocation in cells permanently transfected with GFP-p65 plasmid. IL-1β showed increased epithelial expression in OSAS tissues.

CONCLUSIONS

Nuclear factor kappa B is locally and systemically activated in children with obstructive sleep apnea syndrome. This observation may motivate the search for new anti-inflammatory strategies for controlling nuclear factor kappa B activation in obstructive sleep apnea syndrome.

Toll-like receptor-2 mediates adaptive cardiac hypertrophy in response to pressure overload through interleukin-1β upregulation via nuclear factor κB activation

BACKGROUND

Inflammation is induced in the heart during the development of cardiac hypertrophy. The initiating mechanisms and the role of inflammation in cardiac hypertrophy, however, remain unclear. Toll-like receptor-2 (TLR2) recognizes endogenous molecules that induce noninfectious inflammation. Here, we examined the role of TLR2-mediated inflammation in cardiac hypertrophy.

METHODS AND RESULTS

At 2 weeks after transverse aortic constriction, Tlr2(-/-) mice showed reduced cardiac hypertrophy and fibrosis with greater left ventricular dilatation and impaired systolic function compared with wild-type mice, which indicated impaired cardiac adaptation in Tlr2(-/-) mice. Bone marrow transplantation experiment revealed that TLR2 expressed in the heart, but not in bone marrow-derived cells, is important for cardiac adaptive response to pressure overload. In vitro experiments demonstrated that TLR2 signaling can induce cardiomyocyte hypertrophy and fibroblast and vascular endothelial cell proliferation through nuclear factor-κB activation and interleukin-1β upregulation. Systemic administration of a nuclear factor-κB inhibitor or anti-interleukin-1β antibodies to wild-type mice resulted in impaired adaptive cardiac hypertrophy after transverse aortic constriction. We also found that heat shock protein 70, which was increased in murine plasma after transverse aortic constriction, can activate TLR2 signaling in vitro and in vivo. Systemic administration of anti-heat shock protein 70 antibodies to wild-type mice impaired adaptive cardiac hypertrophy after transverse aortic constriction.

CONCLUSIONS

Our results demonstrate that TLR2-mediated inflammation induced by extracellularly released heat shock protein 70 is essential for adaptive cardiac hypertrophy in response to pressure overload. Thus, modulation of TLR2 signaling in the heart may provide a novel strategy for treating heart failure due to inadequate adaptation to hemodynamic stress.

Early short-term doxycycline therapy in patients with acute myocardial infarction and left ventricular dysfunction to prevent the ominous progression to adverse remodelling: the TIPTOP trial

AIMS

Experimental studies suggest that doxycycline attenuates post-infarction remodelling and exerts protective effects on myocardial ischaemia/reperfusion injury. However, the effects of the drug in the clinical setting are unknown. The aim of this study was to examine the effect of doxycycline on left ventricular (LV) remodelling in patients with acute ST-segment elevation myocardial infarction (STEMI) and LV dysfunction.

METHODS AND RESULTS

Open-label, randomized, phase II trial. Immediately after primary percutaneous coronary intervention, patients with STEMI and LV ejection fraction < 40% were randomly assigned to doxycycline (100 mg b.i.d. for 7 days) in addition to standard therapy, or to standard care. The echo LV end-diastolic volumes index (LVEDVi) was determined at baseline and 6 months. (99m)Tc-Sestamibi-single-photon emission computed tomography infarct size and severity were assessed at 6 months. We calculated a sample size of 110 patients, assuming that doxycycline may reduce the increase in the LVEDVi from baseline to 6 months > 50% compared with the standard therapy (statistical power > 80% with a type I error = 0.05). The 6-month changes in %LVEDVi were significant smaller in the doxycycline group than in the control group [0.4% (IQR: -16.0 to 14.2%) vs.13.4% (IQR: -7.9 to 29.3%); P = 0.012], as well as infarct size [5.5% (IQR: 0 to 18.8%) vs. 10.4% (IQR: 0.3 to 29.9%) P = 0.052], and infarct severity [0.53 (IQR: 0.43-0.62) vs. 0.44 (IQR: 0.29-0.60), P = 0.014], respectively.

CONCLUSION

In patients with acute STEMI and LV dysfunction, doxycycline reduces the adverse LV remodelling for comparable definite myocardial infarct size (NCT00469261).

IL-1 induces proinflammatory leukocyte infiltration and regulates fibroblast phenotype in the infarcted myocardium

In the infarcted myocardium, activation of the inflammatory cascade clears the wound from dead cells, whereas stimulating matrix degradation and chamber dilation, thus contributing to the development of heart failure. IL-1 is critically involved in the postinfarction inflammatory reaction and mediates adverse dilative remodeling. We hypothesized that IL-1 may regulate postinfarction repair and remodeling through cell-specific actions on leukocytes and fibroblasts. Flow cytometry demonstrated that in mouse infarcts, early recruitment of proinflammatory Ly6C(hi) cells expressing IL-1R1, the signaling receptor for IL-1, was followed by infiltration with cells expressing the decoy receptor, IL-1R2. Increased expression of IL-1R2 may serve to terminate IL-1-driven inflammation after infarction. Loss of IL-1 signaling in IL-1R1 null mice globally attenuated leukocyte recruitment, reducing the number of infiltrating Ly6C(hi) and Ly6C(lo) cells. Nonmyeloid CD11b(-) cells harvested during the inflammatory phase of cardiac repair exhibited marked upregulation of chemokines and cytokines; their inflammatory activation was IL-1R1 dependent. Moreover, IL-1β attenuated TGF-β-induced contractile activity of fibroblasts populating collagen pads, attenuated α-smooth muscle actin expression, and stimulated matrix metalloproteinase synthesis in an IL-1R1-dependent manner. The effects of IL-1 on TGF-β responses in cardiac fibroblasts were not due to direct effects on Smad activation, but were associated with endoglin suppression and accentuated expression of bone morphogenetic protein and activin membrane-bound inhibitor, a negative regulator of TGF-β signaling. IL-1 may orchestrate fibroblast responses in the infarct; early stimulation of fibroblast IL-1R1 signaling during the inflammatory phase may prevent premature activation of a matrix-synthetic contractile phenotype until the wound is cleared, and the infarct microenvironment can support mesenchymal cell growth.

Cytokine mediated tissue fibrosis

Acute inflammation is a recognised part of normal wound healing. However, when inflammation fails to resolve and a chronic inflammatory response is established this process can become dysregulated resulting in pathological wound repair, accumulation of permanent fibrotic scar tissue at the site of injury and the failure to return the tissue to normal function. Fibrosis can affect any organ including the lung, skin, heart, kidney and liver and it is estimated that 45% of deaths in the western world can now be attributed to diseases where fibrosis plays a major aetiological role. In this review we examine the evidence that cytokines play a vital role in the acute and chronic inflammatory responses that drive fibrosis in injured tissues. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Effects of interleukin-1 on cardiac fibroblast function: relevance to post-myocardial infarction remodelling

The cardiac fibroblast (CF) is a multifunctional and heterogeneous cell type that plays an essential role in regulating cardiac development, structure and function. Following myocardial infarction (MI), the myocardium undergoes complex structural remodelling in an attempt to repair the damaged tissue and overcome the loss of function induced by ischemia/reperfusion injury. Evidence is emerging that CF play critical roles in all stages of post-MI remodelling, including the initial inflammatory phase that is triggered in response to myocardial damage. CF are particularly responsive to the proinflammatory cytokine interleukin-1 (IL-1) whose levels are rapidly induced in the myocardium after MI. Studies from our laboratory in recent years have sought to evaluate the functional effects of IL-1 on human CF function and to determine the underlying molecular mechanisms. This review summarises these data and sets it in the context of post-MI cardiac remodelling, identifying the fibroblast as a potential therapeutic target for reducing adverse cardiac remodelling and its devastating consequences.

IL-1β suppresses TGF-β-mediated myofibroblast differentiation in cardiac fibroblasts

Cardiac fibrosis is a maladaptive response of the injured myocardium and is mediated through a complex interplay between molecular triggers and cellular responses. Interleukin (IL)-1β is a key inflammatory inducer in cardiac disease and promotes cell invasion and cardiomyocyte injury, but little is known of its impact on fibrosis. A major cornerstone of fibrosis is the differentiation of cardiac fibroblasts (CFs) into myofibroblasts (myoFbs), which is highly promoted by Transforming Growth Factor (TGF)-β. Therefore, we asked how IL-1β functionally modulated CF-to-myoFb differentiation. Using a differentiation model of ventricular fibroblasts, we found that IL-1β instigated substantial anti-fibrogenic effects. In specific, IL-1β reduced proliferation, matrix activity, cell motility and α-smooth muscle actin expression, which are all hallmarks of myoFb differentiation. These findings suggest that IL-1β, besides from its acknowledged adverse role in the inflammatory response, can also exert beneficial effects in cardiac fibrosis by actively suppressing differentiation of CFs into fibrogenic myoFbs.

Effects of interleukin-1 blockade with anakinra on adverse cardiac remodeling and heart failure after acute myocardial infarction [from the Virginia Commonwealth University-Anakinra Remodeling Trial (2) (VCU-ART2) pilot study]

A first pilot study of interleukin-1 blockade in ST-segment elevation acute myocardial infarction showed improved remodeling. In the present second pilot study, we enrolled 30 patients with clinically stable ST-segment elevation acute myocardial infarction randomized to anakinra, recombinant interleukin-1 receptor antagonist, 100 mg/day for 14 days or placebo in a double-blind fashion. The primary end point was the difference in the interval change in left ventricular (LV) end-systolic volume index between the 2 groups within 10 to 14 weeks. The secondary end points included changes in the LV end-diastolic volume index, LV ejection fraction, and C-reactive protein levels. No significant changes in end-systolic volume index, LV end-diastolic volume index, or LV ejection fraction were seen in the placebo group. Compared to placebo, treatment with anakinra led to no measurable differences in these parameters. Anakinra significantly blunted the increase in C-reactive protein between admission and 72 hours (+0.8 mg/dl, interquartile range -6.4 to +4.2, vs +21.1 mg/dl, interquartile range +8.7 to +36.6, p = 0.002), which correlated with the changes in LV end-diastolic volume index and LV end-systolic volume index at 10 to 14 weeks (R = +0.83, p = 0.002, and R = +0.55, p = 0.077, respectively). One patient in the placebo group (7%) died. One patient (7%) in the anakinra group developed recurrent acute myocardial infarction. More patients were diagnosed with new-onset heart failure in the placebo group (4, 27%) than in the anakinra group (1, 7%; p = 0.13). When the data were pooled with those from the first Virginia Commonwealth University-Anakinra Remodeling Trial (n = 40), this difference reached statistical significance (30% vs 5%, p = 0.035). In conclusion, interleukin-1 blockade with anakinra blunted the acute inflammatory response associated with ST-segment elevation acute myocardial infarction. Although it failed to show a statistically significant effect on LV end-systolic volume index, LV end-diastolic volume index, or LV ejection fraction in this cohort of clinically stable patients with near-normal LV dimensions and function, anakinra led to a numerically lower incidence of heart failure.

Extracellular β-NAD(+) inhibits interleukin-1-induced matrix metalloproteinase-1 and -3 expression on human gingival fibroblasts

There is increasing evidence to show that extracellular β-nicotinamide adenine dinucleotide (β-NAD(+)) modulates various biological functions in inflammatory/immune regions. The aim of this study was to determine the effect of β-NAD(+) on matrix metalloproteinase (MMP) expression on human gingival fibroblasts (hGF), the excess production of which leads to the matrix degradation associated with the pathological processes of periodontitis. The expression of MMP-1 and MMP-3 on hGF was determined by real-time polymerase chain reaction (PCR) and an enzyme-linked immunosorbent assay. The phosphorylated status of mitogen-activated protein (MAP) kinases, extracellular signal-regulated kinase 1/2 (ERK), c-Jun N-terminal kinase (JNK), and p38 and the expression of inhibitor κB (IκB)α were determined by Western blotting. β-NAD(+) inhibited the expression of MMP-1 and MMP-3 triggered by IL-1α at gene and protein levels. β-NAD(+) had no significant effect on the IL-1α-induced phosphorylation of ERK1/2, JNK, and p38 and also had no effect on the IL-1α-induced degradation of IκBα relative to the control, suggesting that inhibition by β-NAD(+) was independent of the MAP kinase and the nuclear factor-κB signaling pathways. Transcripts of NAD(+)-metabolizing enzymes, such as NAD(+)-glycohydrolase, adenosine diphosphate (ADP)-ribosylcyclase, and ADP-ribosyltransferase, were expressed by hGF as assessed by RT-PCR. Experiments using α-NAD(+), which is not a substrate for ADP-ribosylcyclase or ADP-ribosyltransferase, revealed the possible contribution of NAD(+)-glycohydrolase to the inhibition of MMP. This is consistent with the finding that ADP-ribose, an NAD(+)-metabolite by NAD(+)-glycohydrolase, exhibited MMP inhibition similar to β-NAD(+). The present findings may provide an additional viewpoint to clarify a natural feedback mechanism during the inflammatory process in periodontal tissue.