Chemokines and their receptors in Atherosclerosis

Characterization of LncRNA expression profile and identification of novel LncRNA biomarkers to diagnose coronary artery disease

BACKGROUND AND AIMS

Dysregulation of long non-coding RNAs (lncRNAs) has been proven to be involved in the pathogenesis of coronary artery disease (CAD). However, it remains to be extensively explored. Thus, the present study aims to study expression patterns, biological functions, and diagnostic value of lncRNAs in CAD.

METHODS

Using microarray, we performed the transcriptome-wide lncRNA and mRNAs expression profile of peripheral blood mononuclear cells (PBMCs) of 93 CAD patients and 48 healthy controls. Gene Ontology (GO) and pathway analysis for differentially expressed mRNAs were used to investigate underlying biological associations of differentially expressed lncRNAs, and path-net was created to depict interactions of significant pathways. qRT-PCR was used to validate selected lncRNAs in 412 CAD patients and 295 healthy controls. Receiver operating characteristic (ROC) curve analysis was performed to evaluate whether lncRNAs could be used in the diagnosis of CAD patients. Finally, the functional significance of validated lncRNAs was determined in THP-1-derived macrophages.

RESULTS

We identified 1210 lncRNAs and 890 mRNAs differentially expressed from the expression profile and validated 7 lncRNAs. Two novel lncRNA biomarkers, ENST00000444488.1 and uc010yfd.1, together with CAD risk factors, had the better performance for discrimination of CAD patients from healthy controls, and ENST00000444488.1 could diagnose acute myocardial infarction (AMI) patients. The knockdown of 20 ENST00000444488.1, uc010yfd.1, ASO3973 and ENST00000602558.1 affected the expression of inflammation-related genes and their nearby genes in THP-1-derived macrophages, respectively.

CONCLUSIONS

We offered a transcriptome-wide overview of aberrantly expressed lncRNAs in CAD patients, and identified two novel lncRNA biomarkers for diagnosing CAD. Loss of validated lncRNAs regulated the expression of inflammation-related genes and their nearby genes.

Lipophilic components of diesel exhaust particles induce pro-inflammatory responses in human endothelial cells through AhR dependent pathway(s)

Background

Exposure to traffic-derived particulate matter (PM), such as diesel exhaust particles (DEP), is a leading environmental cause of cardiovascular disease (CVD), and may contribute to endothelial dysfunction and development of atherosclerosis. It is still debated how DEP and other inhaled PM can contribute to CVD. However, organic chemicals (OC) adhered to the particle surface, are considered central to many of the biological effects. In the present study, we have explored the ability of OC from DEP to reach the endothelium and trigger pro-inflammatory reactions, a central step on the path to atherosclerosis.

Results

Exposure-relevant concentrations of DEP (0.12 μg/cm²) applied on the epithelial side of an alveolar 3D tri-culture, rapidly induced pro-inflammatory and aryl hydrocarbon receptor (AhR)-regulated genes in the basolateral endothelial cells. These effects seem to be due to soluble lipophilic constituents rather than particle translocation. Extractable organic material of DEP (DEP-EOM) was next fractionated with increasing polarity, chemically characterized, and examined for direct effects on pro-inflammatory and AhR-regulated genes in human microvascular endothelial (HMEC-1) cells and primary human endothelial cells (PHEC) from four healthy donors. Exposure-relevant concentrations of lipophilic DEP-EOM (0.15 μg/cm²) induced low to moderate increases in IL-1α, IL-1β, COX2 and MMP-1 gene expression, and the MMP-1 secretion was increased. By contrast, the more polar EOM had negligible effects, even at higher concentrations. Use of pharmacological inhibitors indicated that AhR and protease-activated receptor-2 (PAR-2) were central in regulation of EOM-induced gene expression. Some effects also seemed to be attributed to redox-responses, at least at the highest exposure concentrations tested. Although the most lipophilic EOM, that contained the majority of PAHs and aliphatics, had the clearest low-concentration effects, there was no straight-forward link between chemical composition and biological effects.

Conclusion

Lipophilic and semi-lipophilic chemicals seemed to detach from DEP, translocate through alveolar epithelial cells and trigger pro-inflammatory reactions in endothelial cells at exposure-relevant concentrations. These effects appeared to be triggered by AhR agonists, and involve PAR-2 signaling.

Electronic supplementary material

The online version of this article (10.1186/s12989-018-0257-1) contains supplementary material, which is available to authorized users.

Radiopaque nano and polymeric materials for atherosclerosis imaging, embolization and other catheterization procedures

A review of radiopaque nano and polymeric materials for atherosclerosis imaging and catheterization procedures is presented in this paper. Cardiovascular diseases (CVDs) are the leading cause of death in the US with atherosclerosis as a significant contributor for mortality and morbidity. In this review paper, we discussed the physics of radiopacity and X-ray/CT, clinically used contrast agents, and the recent progress in the development of radiopaque imaging agents and devices for the diagnosis and treatment of CVDs. We focused on radiopaque imaging agents for atherosclerosis, radiopaque embolic agents and drug eluting beads, and other radiopaque medical devices related to catheterization procedures to treat CVDs. Common strategies of introducing radiopacity in the polymers, together with examples of their applications in imaging and medical devices, are also presented.

Inflammation in human carotid atheroma plaques

Inflammation in carotid atherosclerotic plaque is linked to plaque rupture and cerebrovascular accidents. The balance between pro- and anti-inflammatory mediators governs development of the plaque, and may mediate enhancement of lesion broadening or, on the contrary, delay progression. In addition to macrophages and endothelial cells, smooth muscle cells (SMCs), which are the dominant cell subset in advanced plaques, are crucial players in carotid atherosclerosis development given their ability to differentiate into distinct phenotypes in reponse to specific signals received from the environment of the lesion. Carotid atheroma SMCs actively contribute to the inflammation in the lesion because of their acquired capacity to produce inflammatory mediators. We review the successive stages of carotid atheroma plaque formation via fatty streak early-stage toward more advanced rupture-prone lesions and document involvement of cytokines and chemokines and their cellular sources and targets in plaque progression and rupture.

Interleukin-33 induces interleukin-8 expression via JNK/c-Jun/AP-1 pathway in human umbilical vein endothelial cells

Interleukin (IL)-33 is a member of the IL-1 cytokine family with dual functions as a traditional cytokine and as a transcriptional regulator. We recently reported that IL-33 up-regulated growth regulated oncogene (GRO)-α/CXCL1 expression in human vascular endothelial cells. The aim of this study was to investigate the effect of IL-33 on the expression of IL-8/CXCL8, another member of the CXC-chemokine family, and to elucidate its signaling pathways in human umbilical vein endothelial cells (HUVECs). Immunocytochemical staining and Western immunoblot analysis revealed that IL-33 augmented IL-8 protein expression in HUVECs. Real time reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) showed that IL-33 significantly increased IL-8 mRNA and secretion in a dose- and time-dependent manner. IL-33 preferentially stimulated proliferating subconfluent cells, and increased IL-8 secretion to a higher level compared with confluent cells. IL-33 also stimulated phosphorylations of c-Jun N-terminal kinase (JNK) and c-Jun, and enhanced activator protein (AP)-1 DNA-binding activity, all of which were suppressed by SP600125, a JNK inhibitor. Moreover, IL-33-induced IL-8 mRNA and secretion were also suppressed by SP600125. Transfection of c-Jun small interfering RNA into cultured HUVECs significantly reduced the IL-33-induced increase in IL-8 secretion from HUVECs. The present study demonstrates that IL-33 induces IL-8 expression via JNK/c-Jun/AP-1 pathway in human vascular endothelial cells, and provides a new insight into the role of IL-33-induced IL-8 in the pathophysiology of atherosclerosis and vascular inflammation.

The Aging Risk and Atherosclerosis: A Fresh Look at Arterial Homeostasis

A considerable volume of research over the last decade has focused on understanding the fundamental mechanisms for the progression of atherosclerosis-the underlying cause for the vast majority of all cardiovascular (CVD)-related complications. Aging is the dominant risk factor for clinically significant atherosclerotic lesion formation, yet the heightened impact of aging on the disease is not accounted for by changes in traditional risk factors, such as lack of physical activity, smoking, hypertension, hyperlipidemia, or diabetes mellitus. This review will examine the pathological and biochemical processes of atherosclerotic plaque formation and growth, with particular focus on the aging risk vis-a-vis arterial homeostasis. Particular focus will be placed on the impact of a number of important contributors to arterial homeostasis including bone marrow (BM)-derived vascular progenitor cells, differential monocyte subpopulations, and the role of cellular senescence. Finally, this review will explore many critical observations in the way the disease process has been reassessed both by clinicians and researchers, and will highlight recent advances in this field that have provided a greater understanding of this aging-driven disease.

Hepatocyte-derived macrophage migration inhibitory factor mediates alcohol-induced liver injury in mice and patients

BACKGROUND & AIMS

Macrophage migration inhibitory factor (MIF) is a multi-potent cytokine that contributes to the inflammatory response to injury. MIF is expressed by multiple cell types; however, the cellular source and actions of MIF in alcoholic liver disease (ALD) are not well known. Here we tested the hypothesis that non-myeloid cells, specifically hepatocytes, are an important cellular source of MIF in ALD.

METHODS

MIF expression was measured in HuH7 and differentiated THP-1 cells in response to ethanol. Ethanol-induced liver injury was assessed in C57BL/6 (WT) and Mif^-/- bone marrow chimeras. MIF was measured in peripheral and suprahepatic serum, as well as visualized by immunohistochemistry in liver biopsies, from patients with alcoholic hepatitis (AH).

RESULTS

HuH7 hepatocytes, but not THP-1 macrophages, released MIF in response to ethanol challenge in culture. In chimeric mice expressing MIF in non-myeloid cells (Mif^-/-→WT), chronic ethanol feeding increased ALT/AST, hepatic steatosis, and expression of cytokine/chemokine mRNA. In contrast, chimeric mice not expressing MIF in non-myeloid cells (WT→Mif^-/-) were protected from ethanol-induced liver injury. Immunohistochemical staining of liver biopsies from patients with AH revealed a predominant localization of MIF to hepatocytes. Interestingly, the concentration of MIF in suprahepatic serum, but not peripheral serum, was positively correlated with clinical indicators of disease severity and with an increased risk of mortality in patients with AH.

CONCLUSIONS

Taken together, these data provide evidence that hepatocyte-derived MIF is critical in the pathogenesis of ALD in mice and likely contributes to liver injury in patients with AH. Lay summary: Alcoholic liver disease is a major cause of preventable mortality worldwide, and lacks specific pharmacological therapies. Recent studies have recognized that macrophage migration inhibitor factor (MIF) has a critical role in the inflammatory response to liver damage. However, the cells that produce this protein are still unknown. Our present findings reveal that hepatocytes, the main cell type in the liver, are primarily responsible for MIF production in response to alcohol, which promotes liver injury. Our study suggests that drugs inhibiting MIF production could be beneficial in treating patients with liver disease due to excessive alcohol consumption.

MircroRNA-19a promotes vascular inflammation and foam cell formation by targeting HBP-1 in atherogenesis

Atherosclerosis, a serious threat to human cardiovascular health, involves inflammation throughout its various stages of development. MicroRNAs play an important regulatory role in macrophages that respond to inflammation, but the underlying mechanisms are largely unknown. In this work, we study the impact of miR-19a in macrophage-derived foam cell formation during atherogenesis. A microarray-based analysis of serums from patients with coronary heart disease in comparison with healthy controls reveals a significant enrichment of miR-19a in the serums of atherosclerosis patients. A higher level of miR-19a is also observed in atherosclerosis-prone ascending aortic wall tissues than in internal mammary artery amongst patients with coronary heart disease. We identify HMG-Box Transcription Factor 1 (HBP-1) as a target gene of miR-19a. HBP1 is repressor of macrophage migration inhibiting factor (MIF) and overexpression of miR-19a increases MIF expression. By administering a miR-19a antagonist to the caudal vein, we found a decrease in atherosclerotic plaques and lipids load in apoE-null mice fed with high-fat diet. These results support inhibition of miR-19a reduces inflammatory reaction and constitutes a potent therapeutic approach against atherosclerosis.

Tenascin-c renders a proangiogenic phenotype in macrophage via annexin II

Tenascin-c is an extracellular matrix glycoprotein, the expression of which relates to the progression of atherosclerosis, myocardial infarction and heart failure. Annexin II acts as a cell surface receptor of tenascin-c. This study aimed to delineate the role of tenascin-c and annexin II in macrophages presented in atherosclerotic plaque. Animal models with atherosclerotic lesions were established using ApoE-KO mice fed with high-cholesterol diet. The expression of tenascin-c and annexin II in atherosclerotic lesions was determined by qRT-PCR, Western blot and immunohistochemistry analysis. Raw 264.7 macrophages and human primary macrophages were exposed to 5, 10 and 15 μg/ml tenascin-c for 12 hrs. Cell migration as well as the proangiogenic ability of macrophages was examined. Additionally, annexin II expression was delineated in raw 264.7 macrophages under normal condition (20% O₂ ) for 12 hrs or hypoxic condition (1% O₂ ) for 6-12 hrs. The expression of tenascin-c and annexin II was markedly augmented in lesion aorta. Tenascin-c positively regulated macrophage migration, which was dependent on the expression of annexin II in macrophages. VEGF release from macrophages and endothelial tube induction by macrophage were boosted by tenascin-c and attenuated by annexin II blocking. Furthermore, tenascin-c activated Akt/NF-κB and ERK signalling through annexin II. Lastly, hypoxia conditioning remarkably facilitates annexin II expression in macrophages through hypoxia-inducible factor (HIF)-1α but not HIF-2α. In conclusion, tenascin-c promoted macrophage migration and VEGF expression through annexin II, the expression of which was modulated by HIF-1α.

Anti-Inflammatory Effects of the Mediterranean Diet in the Early and Late Stages of Atheroma Plaque Development

Objective. To evaluate the long-term effects of a Mediterranean diet (MeDiet) intervention on the plasma concentrations of inflammatory and plaque stability-related molecules in elderly people at high risk for cardiovascular disease. Design and Setting. 66 participants from primary care centers affiliated with the Hospital Clinic of Barcelona were randomized into 3 groups: MeDiet plus extra virgin olive oil (EVOO) or nuts and a low-fat diet (LFD). At baseline and at 3 and 5 years, we evaluated the changes in the plasma concentrations of 24 inflammatory biomarkers related to the different stages of the atherosclerotic process by Luminex®. Results. At 3 and 5 years, both MeDiet groups showed a significant reduction of IL-6, IL-8, MCP-1, and MIP-1β (P < 0.05; all) compared to LFD. IL-1β, IL-5, IL-7, IL-12p70, IL-18, TNF-α, IFN-γ, GCSF, GMCSF, and ENA78 (P < 0.05; all) only decreased in the MeDiet+EVOO group and E-selectin and sVCAM-1 (P < 0.05; both) in the MeDiet+nuts group. Conclusions. Long-term adherence to MeDiet decreases the plasma concentrations of inflammatory biomarkers related to different steps of atheroma plaque development in elderly persons at high cardiovascular risk.

Pathological and molecular analyses of atherosclerotic lesions in ApoE-knockout mice

The establishment of consistent and reliable methods for the analysis of atherosclerosis molecular pathways and for testing the efficiency of new therapeutics is of utmost importance. Here, we fed ApoE-knockout (KO) mice with high-fat diet to for 16 weeks to induce atherosclerosis. Atherosclerotic lesions in mice were methodically investigated using pathologic analyses and molecular biology tools. These lesions were histopathologically classified into three categories: early, progressive, and combined lesions. Immunohistochemical analyses showed that both F4/80 (macrophage marker) and tenascin-C are expressed in these lesions. Real-time PCR analysis conducted using formalin-fixed paraffin-embedded tissues with atherosclerotic lesions demonstrated an increase in the levels of many inflammatory chemokines, including Cxcl16, while antibody arrays performed using frozen atherosclerotic tissue samples showed elevated TIMP-1 expression. Subsequent immunohistochemical analyses showed that the expression of CXCL16, TIMP-1, MMP-9, MMP-8, and LOX-1 is localized in the atherosclerotic lesions. We confirmed that the expression of these proteins is localized to atherosclerotic lesion, which suggests their roles in the development of the lesions in ApoE-KO mice. Therefore, this mouse model represents an appropriate tool for elucidating molecular mechanisms underlying the development of atherosclerosis, and a model for the evaluation of therapeutic efficiency of novel drugs.

Receptor-interacting protein 2 (RIP2) gene polymorphisms are associated with increased risk of subclinical atherosclerosis and clinical and metabolic parameters. The Genetics of Atherosclerotic Disease (GEA) Mexican study

The receptor-interacting protein 2 (Rip2) is a serine/threonine kinase involved in multiple nuclear factor-κB (NFκB) activation pathways and is a key regulator of cellular lipid metabolism and cardiovascular disease. The aim of the present study was to evaluate the role of RIP2 gene polymorphisms as susceptibility markers for subclinical atherosclerosis (SA). Using an informatics analysis, four RIP2 gene polymorphisms with predicted functional effects (rs2293808, rs43133, rs431264, and rs16900627) were selected. The polymorphisms were genotyped in 405 individuals with SA (calcium score>0 assessed by computed tomography) and 1099 controls (calcium score=0). Clinical, anthropometric, tomographic and biochemical traits were measured. The association between the RIP2 polymorphisms and SA was evaluated using logistic regression analyses. Pair wise linkage disequilibrium (LD, D') estimations between polymorphisms and haplotype reconstruction were performed with Haploview version 4:1. Under different models adjusted by age, gender, body mass index, hypertension, diabetes mellitus, smoking habit, total cholesterol, HDL-cholesterol, LDL-cholesterol and triglyceride levels, rs43133 (OR=1.43, 95% CI: 1.05-1.94, P=0.022), and rs16900627 (OR=1.59, 95% CI: 1.00-2.54, P_dom=0.048 and OR=1.60, 95% CI: 1.05-2.54, P_add=0.028) were associated with increased risk of developing SA. Moreover, rs2293808, and rs431264 were associated with clinical or metabolic parameters in SA individuals and in healthy controls. The four polymorphisms were in high linkage disequilibrium and the GAAG haplotype was associated with increased risk of developing SA (OR=1.47, P=0.027). This study shows for the first time, that RIP2 polymorphisms are associated with increased risk of SA and with some clinical and metabolic parameters.

Serum macrophage migration inhibitory factor levels are associated with infarct volumes and long-term outcomes in patients with acute ischemic stroke

PURPOSE

Previous studies have shown that macrophage migration inhibition factor (MIF) plays a significant role in stroke. The aim of this study was to investigate the association of the serum MIF level with both infarct volume and long-term outcome in patients with acute ischemic stroke (AIS).

METHODS

This study included 146 patients who were identified within 24 h of first experiencing AIS symptoms. Serum MIF levels were tested at the time of admission and three months later. Logistic regression was used to evaluate the risk and long-term outcome of stroke according to serum MIF level.

RESULTS

Serum MIF levels were only higher in acute-stage AIS patients compared with those of the normal controls (p < 0.0001). Chronic-stage serum MIF levels were significantly lower than acute-stage serum MIF levels (p < 0.001) and were similar to serum MIF levels in the controls (p = 0.392). The serum MIF level was positively associated with infarct volume (r = 0.5515, p < 0.0001) and NIHSS score (r = 0.5190, p < 0.0001). After adjusting for other significant outcome predictors, the serum MIF level was an independent predictor of long-term outcome, with an adjusted OR of 1.113 (p = 0.005, 95% CI: 1.051-1.238).

CONCLUSIONS

This study demonstrated that serum MIF levels were significantly increased after AIS. Serum MIF levels at admission were positively correlated with infarct volume and long-term outcome in patients with AIS. The serum MIF level could serve as a useful prognostic marker in patients with AIS.

Linking CD11b (+) Dendritic Cells and Natural Killer T Cells to Plaque Inflammation in Atherosclerosis

Atherosclerosis remains the leading cause of death and disability in our Western society. To investigate whether the dynamics of leukocyte (sub)populations could be predictive for plaque inflammation during atherosclerosis, we analyzed innate and adaptive immune cell distributions in blood, plaques, and lymphoid tissue reservoirs in apolipoprotein E-deficient (ApoE^−/−) mice and in blood and plaques from patients undergoing endarterectomy. Firstly, there was predominance of the CD11b⁺ conventional dendritic cell (cDC) subset in the plaque. Secondly, a strong inverse correlation was observed between CD11b⁺ cDC or natural killer T (NKT) cells in blood and markers of inflammation in the plaque (including CD3, T-bet, CCR5, and CCR7). This indicates that circulating CD11b⁺ cDC and NKT cells show great potential to reflect the inflammatory status in the atherosclerotic plaque. Our results suggest that distinct changes in inflammatory cell dynamics may carry biomarker potential reflecting atherosclerotic lesion progression. This not only is crucial for a better understanding of the immunopathogenesis but also bares therapeutic potential, since immune cell-based therapies are emerging as a promising novel strategy in the battle against atherosclerosis and its associated comorbidities. The cDC-NKT cell interaction in atherosclerosis serves as a good candidate for future investigations.

Altered Macrophage and Dendritic Cell Response in Mif-/- Mice Reveals a Role of Mif for Inflammatory-Th1 Response in Type 1 Diabetes

Macrophage migration inhibitory factor (Mif) is highly expressed in type 1 diabetes mellitus (T1DM). However, there is limited information about how Mif influences the activation of macrophages (Mφ) and dendritic cells (DC) in T1DM. To address this issue, we induced T1DM by administering multiple low doses of streptozotocin (STZ) to Mif-/- or wild-type (Wt) BALB/c mice. We found that Mif-/- mice treated with STZ (Mif-/-STZ) developed lower levels of hyperglycemia, inflammatory cytokines, and specific pancreatic islet antigen- (PIAg-) IgG and displayed reduced cellular infiltration into the pancreatic islets compared to Wt mice treated with STZ (WtSTZ). Moreover, Mφ and DC from Mif-/-STZ displayed lower expression of MHC-II, costimulatory molecules CD80, CD86, and CD40, Toll-like receptor- (TLR-) 2, and TLR-4 than WtSTZ. These changes were associated with a reduced capacity of Mφ and DC from Mif-/-STZ to induce proliferation in ovalbumin-specific T cells. All the deficiencies observed in Mif-/-STZ were recovered by exogenous administration of recombinant Mif. These findings suggest that Mif plays a role in the molecular mechanisms of Mφ and DC activation and drives T cell responses involved in the pathology of T1DM. Therefore, Mif is a potential therapeutic target to reduce the pathology of T1DM.