Elevated IL-27 in patients with acute coronary syndrome is associated with adverse ventricular remodeling and increased risk of recurrent myocardial infarction and cardiovascular death.

BACKGROUND AND AIMS: IL-27 is an immunoregulatory cytokine belonging to the IL-6/IL-12 family that was found to be elevated in acute coronary syndrome (ACS) patients. We investigated whether IL-27 is related to post-ischemic cardiac remodeling and long-term prognosis in this patient group. METHODS: We included 524 ACS patients, defined as acute myocardial infarction (AMI) or unstable angina (UA). A subgroup of 107 patients donated blood samples 6 weeks after the index event, and underwent a follow-up echocardiographical examination at 1 year. We measured plasma levels of IL-27, high sensitivity troponin T (hsTNT), C-reactive protein (hsCRP) and cystatin C at baseline and in the 6-week samples. The median follow-up period of the cohort was 2.2 years. RESULTS: The incidence of the combined end-point of AMI and cardiovascular death was higher in patients with plasma IL-27 within the top two tertiles both at baseline and after 6 weeks. After correction for cardiovascular risk factors, medication, hsTNT, hsCRP, and eGFR, patients with baseline IL-27 levels within the highest tertile had a significantly elevated risk for the combined end-point compared with the lowest tertile (hazard ratio 2.70, 95% CI 1.06-6.90, p = .038). Additionally, higher baseline IL-27 levels were associated with deleterious left ventricular remodeling and deterioration of systolic and diastolic function during the first year of follow-up. CONCLUSIONS: Elevated IL-27 at the time of an ACS is independently related to impaired cardiac function and worse long-term prognosis. Our data warrants further mechanistic studies to elucidate the involvement of IL-27 in cardiac repair and remodeling after ACS.

Sphingolipids Contribute to Human Atherosclerotic Plaque Inflammation.

OBJECTIVE: Lipids are central to the development of atherosclerotic plaques. Specifically, which lipids are culprits remains controversial, and promising targets have failed in clinical studies. Sphingolipids are bioactive lipids present in atherosclerotic plaques, and they have been suggested to have both proatherogenic and antiatherogenic. However, the biological effects of these lipids remain unknown in the human atherosclerotic plaque. The aim of this study was to assess plaque levels of sphingolipids and investigate their potential association with and contribution to plaque vulnerability. APPROACH AND RESULTS: Glucosylceramide, lactosylceramide, ceramide, dihydroceramide, sphingomyelin, and sphingosine-1-phosphate were analyzed in homogenates from 200 human carotid plaques using mass spectrometry. Inflammatory activity was determined by analyzing plaque levels of cytokines and plaque histology. Caspase-3 was analyzed by ELISA technique. Expression of regulatory enzymes was analyzed with RNA sequencing. Human coronary artery smooth muscle cells were used to analyze the potential role of the 6 sphingolipids as inducers of plaque inflammation and cellular apoptosis in vitro. All sphingolipids were increased in plaques associated with symptoms and correlated with inflammatory cytokines. All sphingolipids, except sphingosine-1-phosphate, also correlated with histological markers of plaque instability. Lactosylceramide, ceramide, sphingomyelin, and sphingosine-1-phosphate correlated with caspase-3 activity. In vitro experiments revealed that glucosylceramide, lactosylceramide, and ceramide induced cellular apoptosis. All analyzed sphingolipids induced an inflammatory response in human coronary artery smooth muscle cells. CONCLUSIONS: This study shows for the first time that sphingolipids and particularly glucosylceramide are associated with and are possible inducers of plaque inflammation and instability, pointing to sphingolipid metabolic pathways as possible novel therapeutic targets.

High plasma levels of heparin-binding epidermal growth factor are associated with a more stable plaque phenotype and reduced incidence of coronary events.

OBJECTIVE: Rupture of atherosclerotic plaques is the major cause of acute coronary events (CEs). Plaque destabilization is the consequence of an imbalance between inflammatory-driven degradation of fibrous tissue and smooth muscle cell-dependent tissue repair. Proinflammatory factors have been documented extensively as biomarkers of cardiovascular risk but factors that contribute to stabilization of atherosclerotic plaques have received less attention. The present study aimed to investigate whether plasma levels of the smooth muscle cell growth factor epidermal growth factor (EGF), heparin-binding-EGF (HB-EGF), and platelet-derived growth factor correlate with plaque phenotype and incidence of CEs. APPROACH AND RESULTS: HB-EGF, EGF and platelet-derived growth factor were measured in plasma from 202 patients undergoing carotid endarterectomy and in 384 incident CE cases and 409 matched controls recruited from the Malmö Diet and Cancer cohort. Significant positive associations were found between the plasma levels of all 3 growth factors and the collagen and elastin contents of the removed plaques. CE cases in the Malmö Diet and Cancer cohort had lower levels of HB-EGF in plasma, whereas no significant differences were found for EGF and platelet-derived growth factor. After adjusting for cardiovascular risk factors in a Cox proportional hazard model, the hazard ratio for the highest HB-EGF tertile was 0.61 (95% confidence interval, 0.47-0.82; P<0.001). CONCLUSIONS: The associations between high levels of smooth muscle cell growth factors in plasma and a more fibrous plaque phenotype as well as the association between low levels of HB-EGF and incident CEs point to a potential clinically important role for factors that contribute to plaque stabilization by stimulating smooth muscle cells.

Impaired fibrous repair: a possible contributor to atherosclerotic plaque vulnerability in patients with type II diabetes.

OBJECTIVE: Diabetes mellitus (DM) type II is increasing rapidly worldwide. Patients with DM II have a greater atherosclerotic burden and higher risk of developing cardiovascular complications. Inflammation has been proposed as the main cause for the high risk of atherosclerotic disease in DM II. In this study, we compared markers of inflammation and fibrous repair in plaques from subjects with and without DM II. APPROACH AND RESULTS: Carotid endarterectomy specimens were obtained from 63 patients with and 131 without DM. Plaque structure, connective tissue proteins, inflammatory cells, and markers were analyzed by immunohistochemistry, ELISA, Mesoscale, and Luminex technology. Carotid plaques from diabetics had lower levels of extracellular matrix proteins, elastin, and collagen, which are critical for plaque stability. Plaques from diabetics had reduced levels of platelet-derived growth factor and matrix metalloproteinase-2, both important for tissue repair. No differences were observed in inflammatory markers in plaques from diabetic and nondiabetic patients. CONCLUSION: This study suggests that atherosclerotic plaques in subjects with DM II are more prone to rupture because of impaired repair responses rather than to increased vascular inflammation. Although this study did not have a mechanistic design, our findings suggest that targeting impaired repair responses in carotid plaques may help to increase our understanding of atherosclerotic plaque development and vulnerability in patients with DM II.

Evidence supporting a key role of Lp-PLA2-generated lysophosphatidylcholine in human atherosclerotic plaque inflammation.

OBJECTIVE: To determine whether the level of lysophosphatidylcholine (lysoPC) generated by lipoprotein-associated phospholipase A2 (Lp-PLA2) is associated with severity of inflammation in human atherosclerotic plaques. Elevated plasma Lp-PLA2 is associated with increased cardiovascular risk. Lp-PLA2 inhibition reduces atherosclerosis. Lp-PLA2 hydrolyzes low-density lipoprotein-oxidized phospholipids generating lysoPCs. According to in vitro studies, lysoPCs are proinflammatory but the association between their generation and plaque inflammation remains unknown. METHODS AND RESULTS: Inflammatory activity in carotid plaques (162 patients) was determined immunohistochemically and by analyzing cytokines in homogenates (multiplex immunoassay). LysoPCs were quantified using mass spectrometry and Lp-PLA2 and the lysoPC metabolite lysophosphatidic acid (LPA) by ELISA. There was a strong correlation among lysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 in plaques. LysoPC 16:0, 18:0, 18:1, LPA, and Lp-PLA2 correlated with interleukin-1ß, interleukin-6, monocyte chemoattractant protein-1, macrophage inflammatory protein-1ß, regulated on activation normal T-cell expressed and secreted, and tumor necrosis factor-α in plaques. High lysoPC and Lp-PLA2 correlated with increased plaque macrophages and lipids and with low content of smooth muscle cells, whereas LPA only correlated with plaque macrophages. Lp-PLA2, lysoPC 16:0, 18:0, and 18:1, but not LPA were higher in symptomatic than in asymptomatic plaques. CONCLUSIONS: The associations among Lp-PLA2, lysoPCs, LPA, and proinflammatory cytokines in human plaques suggest that lysoPCs play a key role in plaque inflammation and vulnerability. Our findings support Lp-PLA2 inhibition as a possible strategy for the prevention of cardiovascular disease.

Soluble urokinase plasminogen activator receptor is associated with inflammation in the vulnerable human atherosclerotic plaque.

BACKGROUND AND PURPOSE: Recently, plasma soluble urokinase plasminogen activator receptor (suPAR) has gained interest as a marker of cardiovascular risk. suPAR is released through the cleavage of urokinase plasminogen activator receptor (uPAR), which is found in monocytes, activated T-lymphocytes and endothelial cells, all involved in atherosclerosis. suPAR levels have been well studied in plasma, but no studies have focused on suPAR in human atherosclerotic plaques. The aim of this study was to determine whether suPAR measured in the plaque is associated with symptomatic plaques and plaque inflammation. METHODS: Plasma and carotid plaques from 162 patients were analyzed. Lipids, collagen, uPAR, and macrophages were measured histologically. Cytokines and suPAR were measured in homogenized plaque extracts using multiplex immunoassay and ELISA, respectively. Plasma levels of suPAR were analysed with ELISA. CD3, CD4, as well as uPAR mRNA expression were assessed with quantitative real-time polymerase chain reaction in plaque homogenates from 123 patients. RESULTS: Plaque and plasma suPAR levels were higher in symptomatic patients compared with asymptomatic patients. Plaque suPAR levels correlated with plaque content of lipids and macrophages and with proinflammatory chemokines and cytokines monocyte chemoattractant protein 1, tumor necrosis factor α, interleukin 1ß, interleukin 6, platelet-derived growth factor AB/BB, monocyte inflammatory protein 1ß, regulated on activation normal T-cell expressed and secreted, and s-CD40L. uPAR mRNA and histological staining for uPAR correlated with plaque content of suPAR. CONCLUSIONS: This study shows that suPAR in human carotid plaques and plasma is associated with the presence of symptoms and that plaque suPAR is associated with the vulnerable inflammatory plaque. These findings strengthen the hypothesis of suPAR as a future marker of vulnerable atherosclerotic plaques.

The soluble receptor for advanced glycation end-products (sRAGE) has a dual phase-dependent association with residual cardiovascular risk after an acute coronary event.

BACKGROUND AND AIMS: The pro-inflammatory alarmin S100A12 (EN-RAGE) and the soluble form of its receptor, the receptor for advanced glycation endproducts (sRAGE), have diverging roles in cardiovascular disease. In experimental studies, S100A12 promoted atherosclerosis while sRAGE treatment was anti-atherogenic and reduced myocardial infarction size by scavenging RAGE ligands. Here, we aimed to explore the links between S100A12, sRAGE, and long-term prognosis after an acute coronary syndrome (ACS). METHODS: We measured S100A12 and sRAGE in 524 patients within 24 h after an ACS, and again 6 weeks later in a subgroup of 114 patients. This subgroup also completed a follow-up echocardiography after 1 year. The median follow-up time for recurrent major adverse cardiovascular events (MACE), defined as recurrent ACS or cardiovascular death, was 25.7 ±â€¯12.6 months. RESULTS: In Cox proportional hazard analyses, baseline S100A12 and sRAGE were positively associated with the risk of MACE, independently of traditional cardiovascular risk factors. The association between sRAGE and MACE remained significant after additional adjustment for troponin T, NT-proBNP and hsCRP [HR 95%CI for highest versus lowest tertile 3.2 (1.5-6.5), p = 0.002]. High sRAGE was also associated with deteriorating left ventricular function and an increased rate of heart failure hospitalization post-discharge. In contrast, patients with increasing sRAGE at 6 weeks compared to baseline had lower incidence of recurrent ACS. CONCLUSIONS: Our data suggest that sRAGE has a dual, phase-dependent association with residual cardiovascular risk after ACS. These findings are important for the design and interpretation of future studies on sRAGE as biomarker and potential treatment in ACS patients.

Circulating cytokines reflect the expression of pro-inflammatory cytokines in atherosclerotic plaques.

AIMS: Inflammation is a key factor in the development of plaque rupture and acute cardiovascular events. Although imaging techniques can be used to identify vulnerable atherosclerotic plaques, we are lacking non-invasive methods, such as plasma markers of plaque inflammation that could help to identify presence of vulnerable plaques. The aim of the present study was to investigate whether increased plasma levels of pro-inflammatory cytokines reflects inflammatory activity within atherosclerotic plaques. METHODS AND RESULTS: Cytokines were measured using Luminex immunoassay in 200 homogenized plaque extracts and plasma, obtained from 197 subjects undergoing carotid surgery. Plasma levels of macrophage inflammatory protein-1ß (MIP-1ß), tumor necrosis factor- α (TNF-α) and fractalkine correlated significantly, not only with plaque levels of the same cytokines but also with the abundance of several pro-inflammatory and atherogenic cytokines assessed in plaque tissue. High plasma levels (upper tertile) of MIP-1ß, TNF-α and fractalkine identified the presence of a plaque with high inflammation (above median of a score based on the plaque content of MIP-1ß, TNF-α, interferon-γ (IFN-γ) and fractalkine) with a sensitivity between 65 and 67% and a specificity between 78 and 83%. Furthermore, this study shows that high plasma levels of MIP-1ß, TNF-α and fractalkine predict future transient ischemic attacks. CONCLUSIONS: Our findings show that the plasma levels of MIP-1ß, TNF-α and fractalkine reflect the levels of several pro-atherogenic cytokines in plaque tissue and might be possible plasma markers for a vulnerable atherosclerotic disease. We thereby propose that these cytokines can be used as surrogate markers for the identification of patients with high-risk plaques.

Increased aldehyde-modification of collagen type IV in symptomatic plaques--a possible cause of endothelial dysfunction.

OBJECTIVE: Subendothelial LDL-adhesion and its subsequent oxidation are considered as key events in the development of atherosclerotic lesions. During oxidation of LDL, reactive aldehydes such as malondialdehyde (MDA) are formed, which modify apolipoprotein B100. However, the possibility that these reactive aldehydes could leak out of the LDL-particle and modify surrounding extracellular matrix proteins has been largely unexplored. We have investigated if aldehyde-modification of collagen type IV, one of the major basement membrane components, in plaques is associated with cardiovascular events. METHODS: The amount of MDA-modified collagen type IV and native collagen type IV were determined in homogenates from 155 carotid artery lesions, removed by endarterectomy from patients with or without previous cerebrovascular events. RESULTS: Plaque MDA-collagen type IV, but not native collagen type IV, correlated with oxidized LDL (r=0.31, P<0.001) and lipoprotein-associated phospholipase A2 (r=0.44, P<0.001). MDA-collagen type IV was increased in lesions from symptomatic patients compared to lesions from asymptomatic patients. Auto-antibodies against MDA-collagen type IV in plasma correlated with the amount of MDA-collagen type IV in lesions. MDA-modification of collagen type IV decreased endothelial cell attachment. In addition, culture of endothelial cells with MDA-modified collagen type IV increased vascular cell adhesion molecule expression and reduced the anti-coagulant proteins thrombomodulin and endothelial protein C receptor. In the lesions native collagen type IV, but not MDA-collagen type IV, was positively associated with thrombomodulin. CONCLUSION: The present observations imply that aldehyde-modification of collagen type IV, associated with LDL oxidation, in atherosclerotic plaques may cause endothelial dysfunction and increase the risk of clinical events.

Evidence for altered inflammatory and repair responses in symptomatic carotid plaques from elderly patients.

OBJECTIVE: Most acute cardiovascular events are caused by rupture of an atherosclerotic plaque. The incidence of cardiovascular events increases with age and inflammation is generally considered to be the main cause of increased plaque vulnerability. However, the relationship between age and plaque inflammation has not yet been fully clarified. The aim of our study was to determine if age-dependent plaque vulnerability is associated with increased plaque inflammation. METHODS: We collected 200 endarterectomy specimens, 103 of which were from patients 70 years or older. One-hundred and five patients had a recent cerebrovascular event, whereas the rest were asymptomatic despite significant carotid stenosis. Smooth muscle cell, lipid and macrophage content were analyzed by histology. Cytokines, growth factors and extracellular matrix proteins were analyzed in whole plaque homogenates by immunoassays and biochemical methods. RESULTS: Plaques from elderly patients contained less IFN-γ, TNF-α, fractalkine, sCD40L, and elastin. Lipid and macrophage content was higher in plaques from symptomatic compared to asymptomatic patients in the elderly group, but not in younger patients. The elastin and collagen content was lower in plaques from symptomatic patients in both age groups. Plaques associated with symptoms also contained more TNF-α, IL-1ß, IL-6, sCD40L, MIP-1ß, MCP-1, RANTES and VEGF, regardless of age. CONCLUSIONS: Our data imply that increased plaque vulnerability in the symptomatic elderly patients is associated with increased lipid accumulation and impaired tissue repair, rather than with increased plaque inflammation, compared to younger individuals.

NFAT regulates the expression of AIF-1 and IRT-1: yin and yang splice variants of neointima formation and atherosclerosis.

AIMS: Alternative transcription and splicing of the allograft inflammatory factor-1 (AIF-1) gene results in the expression of two different proteins: AIF-1 and interferon responsive transcript-1 (IRT-1).  Here, we explore the impact of AIF-1 and IRT-1 on vascular smooth muscle cell (VSMC) activation and neointima formation, the mechanisms underlying their alternative splicing, and associations of AIF-1 and IRT-1 mRNA with parameters defining human atherosclerotic plaque phenotype. METHODS AND RESULTS: Translation of AIF-1 and IRT-1 results in different products with contrasting cellular distribution and functions. Overexpression of AIF-1 stimulates migration and proliferation of human VSMCs, whereas IRT-1 exerts opposite effects. Adenoviral infection of angioplasty-injured rat carotid arteries with AdAIF-1 exacerbates intima hyperplasia, whereas infection with AdIRT-1 reduces neointima. Expression of these variants is modulated by changes in nuclear factor of activated T-cells (NFAT) activity.  Pharmacological inhibition of NFAT or targeting of NFATc3 with small interfering RNA (siRNA) lowers the AIF-1/IRT-1 ratio and favours an anti-proliferative outcome.  NFAT acts as a repressor on the IRT-1 transcriptional start site, which is also sensitive to interferon-γ stimulation. Expression of AIF-1 mRNA in human carotid plaques associates with less extracellular matrix and a more pro-inflammatory plaque and plasma profile, features that may predispose to plaque rupture. In contrast, expression of IRT-1 mRNA associates with a less aggressive phenotype and less VSMCs at the most stenotic region of the plaque. CONCLUSION: Inhibition of NFAT signalling, by shifting the AIF-1/IRT-1 ratio, may be an attractive target to regulate the VSMC response to injury and manipulate plaque stability in atherosclerosis.