The IL-1 receptor accessory protein (AcP) is required for IL-33 signaling and soluble AcP enhances the ability of soluble ST2 to inhibit IL-33

Interleukin (IL)-33 (or IL-1F11) was recently identified as a ligand for the orphan IL-1 receptor family member T1/ST2 (ST2). IL-33 belongs to the IL-1 cytokine family and, upon binding to ST2, induces intracellular signals similar to those utilized by IL-1. The effects of other IL-1 family cytokines are mediated by their binding to a specific receptor and the recruitment of a co-receptor required for elicitation of signaling. The aim of this study was to characterize the co-receptor involved in IL-33 signaling. Immunoprecipitation confirmed that IL-33 specifically binds ST2 and revealed that cellular IL-1 receptor accessory protein (AcP) associates with ST2 in a ligand-dependent manner. Receptor binding measurements demonstrated that the affinity of mouse (m)IL-33 for ST2 is increased by 4-fold in presence of AcP. IL-33 dose-dependently stimulated IL-6 secretion from wild-type (WT) mast cells, while no effect of IL-33 was observed with mast cells derived from AcP-deficient mice. Finally, soluble (s)ST2-Fc and sAcP-Fc acted synergistically to inhibit IL-33 activity. These observations identify AcP as a shared co-receptor within the IL-1 family that is essential for IL-33 signaling and suggest a novel role for sAcP in modulating the activity of IL-33.     

MicroRNAs as a therapeutic target for cardiovascular diseases

MicroRNAs (miRNAs) are tiny, endogenous, conserved, non-coding RNAs that negatively modulate gene expression by either promoting the degradation of mRNA or down-regulating the protein production by translational repression. They maintain optimal dose of cellular proteins and thus play a crucial role in the regulation of biological functions. Recent discovery of miRNAs in the heart and their differential expressions in pathological conditions provide glimpses of undiscovered regulatory mechanisms underlying cardiovascular diseases. Nearly 50 miRNAs are overexpressed in mouse heart. The implication of several miRNAs in cardiovascular diseases has been well documented such as miRNA-1 in arrhythmia, miRNA-29 in cardiac fibrosis, miRNA-126 in angiogenesis and miRNA-133 in cardiac hypertrophy. Aberrant expression of Dicer (an enzyme required for maturation of all miRNAs) during heart failure indicates its direct involvement in the regulation of cardiac diseases. MiRNAs and Dicer provide a particular layer of network of precise gene regulation in heart and vascular tissues in a spatiotemporal manner suggesting their implications as a powerful intervention tool for therapy. The combined strategy of manipulating miRNAs in stem cells for their target directed differentiation and optimizing the mode of delivery of miRNAs to the desired cells would determine the future potential of miRNAs to treat a disease. This review embodies the recent progress made in microRNomics of cardiovascular diseases and the future of miRNAs as a potential therapeutic target - the putative challenges and the approaches to deal with it.     

Interleukin-33/ST2 signaling promotes production of interleukin-6 and interleukin-8 in systemic inflammation in cigarette smoke-induced chronic obstructive pulmonary disease mice

Interleukin-33 is a newly described member of the interleukin-1 family. Recent research suggests that IL-33 is increased in lungs and plays a critical role in chronic airway inflammation in cigarette smoke-induced chronic obstructive pulmonary disease (COPD) mice. To determine the role of IL-33 in systemic inflammation, we induced COPD mice models by passive cigarette smoking and identified the IL-33 expression in bronchial endothelial cells and peripheral blood mononuclear cells (PBMCs) of them. After isolation, PBMCs were cultured and stimulated in vitro. We measured expressions of interleukin-6 and interleukin-8 in PBMCs in different groups. The expression of IL-33 in bronchial endothelial cells and PBMCs of COPD mice were highly expressed. Stimulated by cigarette smoke extract (CSE), the expression of IL-6 and IL-8 were induced and enhanced by IL-33. PBMCs of COPD mice produced more IL-6 and IL-8 stimulated by CSE and IL-33. Expression of IL-6 and IL-8 were decreased when stimulated by IL-33 together with soluble ST2. The mRNA production of ST2 in IL-33 stimulated PBMCs was increased. Being pretreated with several kinds of MAPK inhibitors, the secretions of IL-6 and IL-8 in PBMCs did not decrease except for the p38 MAPK inhibitor. We found that IL-33 could induce and enhance the expression of IL-6 and IL-8 in PBMCs of COPD mice via p38 MAPK pathway, and it is a promoter of the IL-6 and IL-8 production in systemic inflammation in COPD mice.     

The potential of adipokines as therapeutic agents for cardiovascular disease

Adipose tissue functions as an endocrine organ by producing bioactive secretory proteins, also known as adipokines, that can directly act on nearby or remote organs. Most of the adipokines are upregulated by obese conditions, and typically promote obese complications. In contrast, some adipokines, such as adiponectin, CTRP9 and omentin, are downregulated in obese states. These factors exert salutary actions on obesity-linked cardiovascular disorders. In this review, we focus on the significance of adiponectin, CTRP9 and omentin as therapeutic agents for cardiovascular disease.     

IL-33／ST2信号通路在疾病中作用的研究进展

IL-33是在2005年发现的一个多功能细胞因子,属于IL-1家族新成员。IL-33通过受体ST2活化NF-KB和MAPK信号通路,促进Th2细胞因子的产生,在多种疾病的发生发展过程中起着重要的作用。     

IL-33/ST2 contributes to severe symptoms in Plasmodium chabaudi-infected BALB/c mice

It has been reported that IL-33 contributes to potentiation of Th2 inflammatory diseases and protection against helminth infection. Increased plasma IL-33 levels have been observed in patients with severe falciparum malaria, however, the role of IL-33 in malaria remains unclear. Here we report that IL-33 enhances inflammatory responses in malaria infection. ST2-deficiency altered severity of inflammation in the liver and serum levels of pro-inflammatory cytokines such as TNF-α and IL-6, and IL-13 that is a Th2 cytokine during Plasmodium chabaudi infection. IL-13-deficient mice have similar phenotype with ST2-deficient mice during P. chabaudi infection. Furthermore, ST2- and IL-13-deficiency reduced mortality from P. chabaudi infection. These results indicate that IL-33/ST2 can induce production of proinflammatory cytokines, such as TNF-α and IL-6, through production of IL-13 in P. chabaudi-infected BALB/c mice, suggesting that IL-33/ST2 play a critical role in inflammatory responses to malaria infection. Thus, these findings may define a novel therapeutic target for patients with severe malaria.     

Predictive values of sST2 and IL-33 for heart failure in patients with acute myocardial infarction

Timely prediction of the risk of heart failure in acute myocardial infarction patients is critical for better prognosis. This article aims to evaluate the predictive value of serum soluble growth stimulation expressed gene 2 (sST2) and interleukin-33 in patients with acute myocardial infarction complicated by heart failure. A total of 42 healthy controls and 144 acute myocardial infarction patients were recruited in the study. According to Killip cardiac function classification as the basis for concurrent heart failure, they were distributed into non-heart failure group (n = 76) and heart failure group (n = 68). ELISA was utilized to determine the serum sST2 and interleukin-33 levels, and the diagnostic efficiency was evaluated by receiver operating characteristics curve. sST2 and interleukin-33 levels in patients with acute myocardial infarction were significantly increased when compared with normal healthy controls, and were further enhanced in the heart failure group. With the increased Killip cardiac function classification, interleukin-33 and sST2 levels were gradually elevated. Multivariate analysis indicated that interleukin-33 and sST2 could be used as independent predictors for heart failure combined with acute myocardial infarction.     

KU812 cells provide a novel in vitro model of the human IL-33/ST2L axis: Functional responses and identification of signaling pathways

Activation of interleukin-1 family receptor ST2L by its ligand interleukin-33 (IL-33) is an important component in inflammatory responses. Peripheral blood basophils, recognized as major effector cells in allergic inflammation that play a role in both innate and adaptive immunity, are activated by IL-33 through ST2L. However, studies are challenging due to the paucity of this cell population, representing less than 1% of peripheral blood leukocytes. We identified a basophil-like chronic myelogenous leukemia cell line, KU812, that constitutively expresses ST2L and demonstrates functional responses to IL-33 stimulation. IL-33 induced production of multiple inflammatory mediators in KU812 cells that were blocked by anti-ST2L and anti-IL-33 antibodies. The interaction of IL-33 and ST2L activated NF-κB, JNK, and p38 MAPK, but not ERK1/2 signaling pathways. Studies using pharmacological inhibitors to IKK-2 and MAP kinases revealed that one of the functional responses, IL-33-induced IL-13 production, was regulated through NF-κB, but not JNK or p38 MAPK signaling. The requirement of NF-κB was confirmed by IKK-2 knockdown using shRNA. KU812 represents the first human cell line-based in vitro model of the IL-33/ST2L axis and provides a valuable tool to aid in understanding the mechanism and significance of IL-33 and ST2L interaction and function.     

Stem cell-derived exosomes as a therapeutic tool for cardiovascular disease

Mesenchymal stem cells(MSCs) have been used to treat patients suffering from acute myocardial infarction(AMI) and subsequent heart failure. Although it was originally assumed that MSCs differentiated into heart cells such as cardiomyocytes, recent evidence suggests that the differentiation capacity of MSCs is minimal and that injected MSCs restore cardiac function via the secretion of paracrine factors. MSCs secrete paracrine factors in not only naked forms but also membrane vesicles including exosomes containing bioactive substances such as proteins, messenger RNAs, and microR NAs. Although the details remain unclear, these bioactive molecules are selectively sorted in exosomes that are then released from donor cells in a regulated manner. Furthermore, exosomes are specifically internalized by recipient cells via ligand-receptor interactions. Thus, exosomes are promising natural vehicles that stably and specifically transport bioactive molecules to recipient cells. Indeed, stem cell-derived exosomes have been successfully used to treat cardiovascular disease(CVD), such as AMI, stroke, and pulmonary hypertension, in animal models, and their efficacy has been demonstrated. Therefore, exosome administration may be a promising strategy for the treatment of CVD. Furthermore, modifications of exosomal contents may enhance their therapeutic effects. Future clinical studies are required to confirm the efficacy of exosome treatment for CVD.     

Mitochondrial cyclophilin-D as a potential therapeutic target for post-myocardial infarction heart failure

The pharmacological inhibition or genetic ablation of cyclophilin-D (CypD), a critical regulator of the mitochondrial permeability transition pore (mPTP), confers myocardial resistance to acute ischemia-reperfusion injury, but its role in post-myocardial infarction (MI) heart failure is unknown. The aim of this study was to determine whether mitochondrial CypD is also a therapeutic target for the treatment of post-MI heart failure. Wild-type (WT) and CypD(-/-) mice were subjected to either sham surgery or permanent ligation of the left main coronary artery to induce MI, and were assessed at either 2 or 28 days to determine the long-term effects of CypD ablation. After 2 days, myocardial infarct size was smaller and left ventricular (LV) function was better preserved in CypD(-/-) mice compared to WT mice. After 28 days, when compared to WT mice, in the CypD(-/-) mice, mortality was halved, myocardial infarct size was reduced, LV systolic function was better preserved, LV dilatation was attenuated and in the remote non-infarcted myocardium, there was less cardiomyocyte hypertrophy and interstitial fibrosis. Finally, ex vivo fibroblast proliferation was found to be reduced in CypD(-/-) cardiac fibroblasts, and in WT cardiac fibroblasts treated with the known CypD inhibitors, cyclosporin-A and sanglifehrin-A. Following an MI, mice lacking CypD have less mortality, smaller infarct size, better preserved LV systolic function and undergo less adverse LV remodelling. These findings suggest that the inhibition of mitochondrial CypD may be a novel therapeutic treatment strategy for post-MI heart failure.     

Crystal structure of cathepsin A,a novel target for the treatment of cardiovascular diseases

The lysosomal serine carboxypeptidase cathepsin A is involved in the breakdown of peptide hormones like endothelin and bradykinin. Recent pharmacological studies with cathepsin A inhibitors in rodents showed a remarkable reduction in cardiac hypertrophy and atrial fibrillation, making cathepsin A a promising target for the treatment of heart failure. Here we describe the crystal structures of activated cathepsin A without inhibitor and with two compounds that mimic the tetrahedral intermediate and the reaction product, respectively. The structure of activated cathepsin A turned out to be very similar to the structure of the inactive precursor. The only difference was the removal of a 40 residue activation domain, partially due to proteolytic removal of the activation peptide, and partially by an order–disorder transition of the peptides flanking the removed activation peptide. The termini of the catalytic core are held together by the Cys253–Cys303 disulfide bond, just before and after the activation domain. One of the compounds we soaked in our crystals reacted covalently with the catalytic Ser150 and formed a tetrahedral intermediate. The other compound got cleaved by the enzyme and a fragment, resembling one of the natural reaction products, was found in the active site. These studies establish cathepsin A as a classical serine proteinase with a well-defined oxyanion hole. The carboxylate group of the cleavage product is bound by a hydrogen-bonding network involving one aspartate and two glutamate side chains. This network can only form if at least half of the carboxylate groups involved are protonated, which explains the acidic pH optimum of the enzyme.     

The pyruvate dehydrogenase complex as a therapeutic target for age-related diseases

Considerable research has been conducted on mitochondrial biology as it pertains to aging. However, relatively little attention has been accorded the pyruvate dehydrogenase complex (PDC) relative to how we grow old and acquire age-related diseases. The purpose of this review is threefold: first, to describe the physiological chemistry of the PDC and define its place in normal cellular bioenergetics; second, to compare and contrast the pathogenesis and clinical features of congenital PDC deficiency with discrete examples of age-associated dysfunction of the complex; and third, to summarize recent findings in Caenorhabditis elegans that shed additional new light on the significance of the PDC to the aging process.     

Modulation of cellular membrane properties as a potential therapeutic strategy to counter lipointoxication in obstructive pulmonary diseases

Maintaining the equilibrium between saturated and unsaturated fatty acids within membrane phospholipids (PLs) is crucial to sustain the optimal membrane biophysical properties, compatible with selective organelle-based processes. Lipointoxication is a pathological condition under which saturated PLs tend to accumulate within the cell at the expense of unsaturated species, with major impacts on organelle function. Here, we show that human bronchial epithelial cells extracted from lungs of patients with Obstructive Pulmonary Diseases (OPDs), i. e. Cystic Fibrosis (CF) individuals and Smokers, display a characteristic lipointoxication signature, with excessive amounts of saturated PLs. Reconstitution of this signature in cellulo and in silico revealed that such an imbalance results in altered membrane properties and in a dramatic disorganization of the intracellular network of bronchial epithelial cells, in a process which can account for several OPD traits. Such features include Endoplasmic Reticulum-stress, constitutive IL8 secretion, bronchoconstriction and, ultimately, epithelial cell death by apoptosis. We also demonstrate that a recently-identified lipid-like molecule, which has been shown to behave as a “membrane-reshaper”, counters all the lipointoxication hallmarks tested. Altogether, these insights highlight the modulation of membrane properties as a potential new strategy to heal and prevent highly detrimental symptoms associated with OPDs.     

Serum sulfatides as a novel biomarker for cardiovascular disease in patients with end-stage renal failure

Sulfatides, normal components of serum lipoproteins, may play an important role in cardiovascular disease due to their various modulatory functions in haemostasis. The incidence of cardiovascular disease in patients with end-stage renal failure undergoing maintenance hemodialysis has been reported to be approximately 10 to 30 times higher than that in the general population. To elucidate the possible roles of serum sulfatides in this high incidence, we measured the level of sulfatides in 59 such patients, by converting them to lysosulfatides according to a recently developed quantitative, qualitative, high-throughput technique using matrix-assisted laser desorption ionization-time of flight mass spectrometry. The mean level of sulfatides in patients 3.58 ± 1.18 nmol/ml was significantly lower than that in age-matched normal subjects (8.21 ± 1.50 nmol/ml; P < 0.001). Patients receiving maintenance hemodialysis over a longer period had lower levels of sulfatides. When the mean levels of sulfatides were compared between patients with cardiovascular disease (N = 22) and those without the disease (N = 37), the level in the former group 2.85 ± 0.67 nmol/ml was found to be significantly lower than that in the latter group 4.01 ± 1.22 nmol/ml (P < 0.001). These findings reveal a close correlation between low levels of serum sulfatides and a high risk of cardiovascular disease in these patients. Determination of the level of serum sulfatides can contribute to predictions of the incidence of cardiovascular disease in patients with end-stage renal failure undergoing maintenance hemodialysis.     

Scavenger receptor Class B type I as a potential risk stratification biomarker and therapeutic target in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of mortality globally. There are few useful markers available for CVD risk stratification that has proven clinical utility. Scavenger receptor B type I (SR-BI) is a cell surface protein that plays a major role in cholesterol homeostasis through its interaction with high-density lipoprotein-cholesterol (HDL-C) esters (CE). HDL delivers CE to the liver through selective uptake by the SR-BI. SR-BI also regulates the inflammatory response. It has been shown that SR-BI overexpression has beneficial, protective effects in atherogenesis, and there is considerable interest in developing antiatherogenic strategies that involve SR-BI-mediated increases in reverse cholesterol transport through HDL and/or low-density lipoprotein. Further investigations are essential to explore the clinical utility of this approach. Moreover, there is growing evidence showing associations between genetic variants with modulation of SR-BI function that may, thereby, increase CVD risk. The aim of the current review was to provide an overview of the possible molecular mechanisms by which SR-BI may affect CVD risk, and the clinical implications of this, with particular emphasis on preclinical studies on genetic changes of SR-BI and CVD risk.     

Evaluating the potential of IL-27 as a novel therapeutic agent in HIV-1 infection

Interleukin 27 (IL-27) is an immunomodulatory cytokine with important roles in both the innate and adaptive immune systems. In the last five years, the addition of exogenous IL-27 to primary cell cultures has been demonstrated to decrease HIV-1 replication in a number of cell types including peripheral blood mononuclear cells (PBMCs), CD4+ T cells, macrophages and dendritic cells. These in vitro findings suggest that IL-27 may have therapeutic value in the setting of HIV-1 infection. In this review, we describe the current knowledge of the biology of IL-27, its effects primarily on HIV-1 replication but also in other viral infections and explore its potential role as a therapeutic cytokine for the treatment of patients with HIV-1 infection.     

The potential of adipokines as biomarkers and therapeutic agents for vascular complications in type 2 diabetes mellitus

Over the past decades, there has been a major increase in type 2 diabetes (T2D) prevalence in most regions of the world. Diabetic patients are more prone to cardiovascular complications. Accumulating evidence suggests that adipose tissue is not simply an energy storage tissue but it also functions as a secretory tissue producing a variety of bioactive substances, also referred to as adipokines. The balance between pro-inflammatory adipokines and protective adipokines is disturbed in type 2 diabetes, this can be regarded as adipose tissue dysfunction which partly promote the pathogenesis of diabetes complications. In this review, we not only discuss the favorable adipokines like adiponectin, omentin, C1q tumor necrosis factor-related proteins, but also unfavorable ones like resisitin and visfatin, in the aim of finding potential biomarkers recommended for the clinical use in the diagnosis, prognosis and follow up of patients with T2D at high risk of developing cardiovascular diseases as well as leading to new therapeutic approaches.     

Reconstitution of ST2 (IL-1R4) specific for IL-33 activity; no suppression by IL-1Ra though a common chain IL-1R3 (IL-1RAcP) shared with IL-1

Interleukin-33 (IL-33) receptors are composed of ST2 (also known as IL-1R4), a ligand binding chain, and IL-1 receptor accessory protein (IL-1RAcP, also known as IL-1R3), a signal transducing chain. IL-1R3 is a common receptor for IL-1α, and IL-1β, IL-33, and three IL-36 isoforms. A549 human lung epithelial cells are highly sensitive to IL-1α and IL-1β but not respond to IL-33. The lack of responsiveness to IL-33 is due to ST2 expression. ST2 was stably transfected into A549 cells to reconstitute its activity. RT-PCR and FACS analysis confirmed ST2 expression on the cell surface of A549/ST2 cells. Upon IL-33 stimulation, A549/ST2 cells induced IL-8 and IL-6 production in a dose dependent manner while A549/mock cells remained unresponsive. There was no difference in IL-1α and IL-1β activity in A549/ST2 cells compared to A549/mock cells despite the fact that IL-33 shares IL-1R3 with IL-1α/β. IL-33 activated inflammatory signaling molecules in a time- and dose-dependent manner. Anti-ST2 antibody and soluble recombinant ST2-Fc abolished IL-33-induced IL-6 and IL-8 production in A549/ST2 cells but the IL-1 receptor antagonist failed to block IL-33-induced cytokines. This result demonstrates for the first time the reconstitution of ST2 in A549 human lung epithelial cell line and verified its function in IL-33-mediated cytokine production and signal transduction.