Increased expression of lectin-like oxidized low density lipoprotein receptor-1 in initial atherosclerotic lesions of Watanabe heritable hyperlipidemic rabbits

Receptor for advanced glycation end products polymorphisms in coronary artery ectasia

BACKGROUND

Although the implication of receptor of advanced glycation endproducts (RAGE) has been reported in coronary artery disease, its roles in coronary artery ectasia (CAE) have remained undetermined. Furthermore, the effect of RAGE polymorfisms were not well-defined in scope of soluble RAGE (sRAGE) levels. Thus, we aimed to investigate the influence of the functional polymorphisms of RAGE -374T > A (rs1800624) and G82S (rs2070600) in CAE development.

METHODS

This prospective observational study was conducted in 2 groups selected of 2452 patients who underwent elective coronary angiography (CAG) for evaluation after positive noninvasive heart tests. Group-I included 98 patients with non-obstructive coronary artery disease and CAE, and Group-II (control) included 100 patients with normal coronary arteries. SNPs were genotyped by real-time PCR using Taqman® genotyping assay. Serum sRAGE and soluble lectin-like oxidized receptor-1 (sOLR1) were assayed by ELISA and serum lipids were measured enzymatically.

RESULTS

The frequencies of the RAGE -374A allele and -374AA genotype were significantly higher in CAE patients compared to controls (p < 0.001). sRAGE levels were not different between study groups, while sOLR1 levels were elevated in CAE (p = 0.004). In controls without systemic disease, -374A allele was associated with low sRAGE levels (p < 0.05), but this association was not significant in controls with HT. Similarly, sRAGE levels of CAE patients with both HT and T2DM were higher than those no systemic disease (p = 0.02). The -374A allele was also associated with younger patient age and higher platelet count in the CAE group in both total and subgroup analyses. In the correlation analyses, the -374A allele was also negatively correlated with age and positively correlated with Plt in all of these CAE groups. In the total CAE group, sRAGE levels also showed a positive correlation with age and a negative correlation with HDL-cholesterol levels. On the other hand, a negative correlation was observed between sRAGE and Plt in the total, hypertensive and no systemic disease control subgroups. Multivariate logistic regression analysis confirmed that the -374A allele (p < 0.001), hyperlipidemia (p < 0.05), and high sOLR1 level (p < 0.05) are risk factors for CAE. ROC curve analysis shows that RAGE -374A allele has AUC of 0.713 (sensitivity: 83.7 %, specificity: 59.0 %), which is higher than HLD (sensitivity: 59.2 %, specificity: 69.0 %), HT (sensitivity: 62.4 %, specificity: 61.1 %) and high sOLR1 level (≥0.67 ng/ml)) (sensitivity: 59.8 %, specificity: 58.5 %).

CONCLUSION

Beside the demonstration of the relationship between -374A allele and increased risk of CAE for the first time, our results indicate that antihypertensive and antidiabetic treatment in CAE patients causes an increase in sRAGE levels. The lack of an association between the expected -374A allele and low sRAGE levels in total CAE group was attributed to the high proportion of hypertensive patients and hence to antihypertensive treatment. Moreover, the RAGE -374A allele is associated with younger age at CAE and higher Plt, suggesting that -374A may also be associated with platelet activation, which plays a role in the pathogenesis of CAE. However, our data need to be confirmed in a large study for definitive conclusions.

LOX-1 in Cardiovascular Disease: A Comprehensive Molecular and Clinical Review

LOX-1, ORL-1, or lectin-like oxidized low-density lipoprotein receptor 1 is a transmembrane glycoprotein that binds and internalizes ox-LDL in foam cells. LOX-1 is the main receptor for oxidized low-density lipoproteins (ox-LDL). The LDL comes from food intake and circulates through the bloodstream. LOX-1 belongs to scavenger receptors (SR), which are associated with various cardiovascular diseases. The most important and severe of these is the formation of atherosclerotic plaques in the intimal layer of the endothelium. These plaques can evolve into complicated thrombi with the participation of fibroblasts, activated platelets, apoptotic muscle cells, and macrophages transformed into foam cells. This process causes changes in vascular endothelial homeostasis, leading to partial or total obstruction in the lumen of blood vessels. This obstruction can result in oxygen deprivation to the heart. Recently, LOX-1 has been involved in other pathologies, such as obesity and diabetes mellitus. However, the development of atherosclerosis has been the most relevant due to its relationship with cerebrovascular accidents and heart attacks. In this review, we will summarize findings related to the physiologic and pathophysiological processes of LOX-1 to support the detection, diagnosis, and prevention of those diseases.

Exploring the druggability of oxidized low-density lipoprotein (ox-LDL) receptor, LOX-1, a proatherogenic drug target involved in atherosclerosis

Lectin-like oxidized low-density lipoprotein (ox-LDL) receptor 1 (LOX-1) is a vital scavenger receptor involved in ox-LDL binding, internalization, and subsequent proatherogenic signaling leading to cellular dysfunction and atherosclerotic plaque formation. Existing data suggest that modulation of ox-LDL - LOX-1 interaction can prevent or slow down atherosclerosis. Therefore, we utilized computational methods such as multi-solvent simulation and characterized two top-ranked druggable sites. Using systematic molecular docking followed by atomistic molecular dynamics simulation, we have identified and shortlisted small molecules from the NCI library that target two key binding sites. We demonstrate, using surface plasmon resonance (SPR), that four of the shortlisted molecules bind one-on-one to the purified C-terminal domain (CTLD) of LOX-1 receptor with high affinity (K_D), ranging from 4.9 nM to 20.1 μM. Further, we performed WaterMap analysis to understand the role of individual water molecules in small molecule binding and the LOX-1-ligand complex stability. Our data clearly show that LOX-1 is druggable with small molecules. Our study provides strategies to identify novel inhibitors to attenuate ox-LDL - LOX-1 interaction.

The structural basis of effective LOX-1 inhibition

Along with other scavenger receptors, splice variants of LOX-1 play an important role in modulating numerous subcellular mechanisms such as normal cell development, differentiation and growth in response to physiological stimuli. Thus, LOX-1 activity is a key regulator in determining the severity of many genetic, metabolic, cardiovascular, renal, and neurodegenerative diseases and/or cancer. Increased expression of LOX-1 precipitates pathological disorders during the aging process. Therefore, it becomes important to develop novel LOX-1 inhibitors based on its ligand binding polarity and/or affinity and disrupt the uptake of its ligand: oxidized low-density lipoproteins (ox-LDL). In this review, we shed light on the presently studied and developed novel LOX-1 inhibitors that may have potential for treatment of diseases characterized by LOX-1 activation.

Knockdown of lectin-like oxidized low-density lipoprotein-1 ameliorates alcoholic cardiomyopathy via inactivating the p38 mitogen-activated protein kinase pathway

LOX-1 triggers myocardial fibrosis, but its roles and mechanisms in alcoholic cardiomyopathy and the involvement of the downstream signaling pathways had not been fully reported. We planned to explore how LOX-1 facilitated myocardial fibrosis in alcoholic cardiomyopathy. The in vitro and in vivo alcoholic cardiomyopathy model was established by alcohol treatment to rats' cardiac fibroblasts and rats, respectively. Masson staining was conducted to observe the collagen deposition and the IHC assay was executed to evaluate the contents of collagen I and III in vitro and in vivo. The cardiac tissues were also observed under TEM and the cardiac function of rats was evaluated using UCG. The expression levels of LOX-1 and P38MAPK in cardiac fibroblasts and tissues at both mRNA and protein levels were analyzed by RT-qPCR and western blot, respectively. Alcohol treatment could trigger collagen deposition, cell hypertrophy, fibrotic changes and increased the expression levels of LOX-1 and P38MAPK both in vivo and in vitro. It also deteriorated the cardiac function of rats in vivo. Overexpression of LOX-1 in vitro could aggravate the fibrotic changes while knockdown of LOX-1 ameliorated the fibrotic effects of alcohol treatment both in vitro and in vivo such as reduction of collagen deposition, relief of cell hypertrophy and inactivation of the P38MAPK signaling pathway. We concluded that knockdown of LOX-1 exerted anti-fibrotic effects via inhibiting P38MAPK signaling in alcoholic cardiomyopathy both in vitro and in vivo. Our findings highlighted that LOX-1 could become a potential therapeutic target in the treatment of alcoholic cardiomyopathy.

Biomarkers in the clinical management of patients with atrial fibrillation and heart failure

Atrial fibrillation (AF) and heart failure (HF) are two cardiovascular diseases with an increasing prevalence worldwide. These conditions share common pathophysiologiesand frequently co-exit. In fact, the occurrence of either condition can 'cause' the development of the other, creating a new patient group that demands different management strategies to that if they occur in isolation. Regardless of the temproral association of the two conditions, their presence is linked with adverse cardiovascular outcomes, increased rate of hospitalizations, and increased economic burden on healthcare systems. The use of low-cost, easily accessible and applicable biomarkers may hasten the correct diagnosis and the effective treatment of AF and HF. Both AF and HF effect multiple physiological pathways and thus a great number of biomarkers can be measured that potentially give the clinician important diagnostic and prognostic information. These will then guide patient centred therapeutic management. The current biomarkers that offer potential for guiding therapy, focus on the physiological pathways of miRNA, myocardial stretch and injury, oxidative stress, inflammation, fibrosis, coagulation and renal impairment. Each of these has different utility in current clinincal practice.

Status of biomarkers for the identification of stable or vulnerable plaques in atherosclerosis

Atherosclerosis is a systemic inflammation of the arteries characterized by atherosclerotic plaque due to the accumulation of lipids, inflammatory cells, apoptotic cells, calcium and extracellular matrix (ECM) proteins. Stable plaques present a chronic inflammatory infiltration, whereas vulnerable plaques present an 'active' inflammation involved in the thinning of the fibrous cap that predisposes to plaque rupture. Several complex biological cellular processes lead plaques to evolve from stable to vulnerable predisposing them to rupture and thrombosis. In this review, we analyze some emerging circulating biomarkers related to inflammation, ECM and lipid infiltration, angiogenesis, metalloproteinases and microRNA (miRNA), as possible diagnostic and prognostic indicators of plaque vulnerability.

Decidua basalis and acute atherosis: Expression of atherosclerotic foam cell associated proteins

INTRODUCTION

Uteroplacental acute atherosis is frequently observed in preeclampsia, and shares features with early atherosclerotic lesions, including artery wall foam cells. The lipid-associated proteins FABP4 (fatty acid binding protein 4), perilipin-2, and LOX-1 (lectin-like oxidized LDL-receptor 1) are involved in atherosclerotic foam cell formation. Increased levels of these proteins have been associated with preeclampsia systemically and in placental tissue. Their role in acute atherosis is yet unidentified. Our aim was to describe the presence of these proteins in acute atherosis, and compare our findings to what is known in early atherosclerotic lesions.

METHODS

Serial sections of decidua basalis tissue from 12 normotensive (4 with acute atherosis) and 23 preeclamptic pregnancies (16 with acute atherosis) were stained with HE and immunostained for CK7, CD68, FABP4, perilipin-2, and LOX-1. Artery wall and perivascular protein expression was assessed in 190 spiral artery sections; 55 with acute atherosis.

RESULTS

Acute atherosis foam cells were commonly positive for perilipin-2 (55%), less often for FABP4 (13%), and never for LOX-1. LOX-1 was frequently observed in intramural trophoblasts of normal spiral arteries. Perivascularly, LOX-1 positivity of decidual stromal cells surrounding arteries with acute atherosis was significantly increased as compared to arteries lacking acute atherosis (38% vs. 15%, p < 0.001).

DISCUSSION

We found that perilipin-2 and FABP4 are expressed by acute atherosis foam cells, similar to atherosclerosis, supporting possible shared pathways for foam cell generation. Unlike atherosclerosis, LOX-1 is not present in acute atherosis, possibly explained by pregnancy-specific routes to decidua basalis foam cell generation.

Association of circulating soluble lectin-like oxidized low-density lipoprotein receptor-1 with inflammatory markers and urinary albumin excretion in patients with type 2 diabetes

OBJECTIVES

The main purpose of the study was to study the association between circulating soluble lectin-like oxidized low-density lipoprotein receptor-1 levels and various markers, including inflammatory markers such as high-sensitivity C-reactive protein and fibrinogen, serum lipids, and renal function, in patients with poorly controlled type 2 diabetes.

METHODS

The subjects were 70 patients (men 45, women 25) who were hospitalized for treatment of poor glycemic control. Plasma soluble lectin-like oxidized low-density lipoprotein receptor-1 levels were assayed using a sandwich chemiluminescence enzyme immunoassay.

RESULTS

Circulating soluble lectin-like oxidized low-density lipoprotein receptor-1 was significantly positively correlated with lectin-like oxidized low-density lipoprotein-1 ligands containing apolipoprotein B, reflecting modified low-density lipoprotein, and with inflammatory markers such as high-sensitivity C-reactive protein and fibrinogen. In addition, there was a significant positive correlation between soluble lectin-like oxidized low-density lipoprotein receptor-1 and urinary albumin excretion.

CONCLUSIONS

Soluble lectin-like oxidized low-density lipoprotein receptor-1 may serve as a marker reflecting the degrees of inflammation and albuminuria in patients with poorly controlled type 2 diabetes.

Prominent Receptors of Liver Sinusoidal Endothelial Cells in Liver Homeostasis and Disease

Liver sinusoidal endothelial cells (LSECs) are the most abundant non-parenchymal cells lining the sinusoidal capillaries of the hepatic system. LSECs are characterized with numerous fenestrae and lack basement membrane as well as a diaphragm. These unique morphological characteristics of LSECs makes them the most permeable endothelial cells of the mammalian vasculature and aid in regulating flow of macromolecules and small lipid-based structures between sinusoidal blood and parenchymal cells. LSECs have a very high endocytic capacity aided by scavenger receptors (SR), such as SR-A, SR-B (SR-B1 and CD-36), SR-E (Lox-1 and mannose receptors), and SR-H (Stabilins). Other high-affinity receptors for mediating endocytosis include the FcγRIIb, which assist in the antibody-mediated removal of immune complexes. Complemented with intense lysosomal activity, LSECs play a vital role in the uptake and degradation of many blood borne waste macromolecules and small (<280 nm) colloids. Currently, seven Toll-like receptors have been investigated in LSECs, which are involved in the recognition and clearance of pathogen-associated molecular pattern (PAMPs) as well as damage associated molecular pattern (DAMP). Along with other SRs, LSECs play an essential role in maintaining lipid homeostasis with the low-density lipoprotein receptor-related protein-1 (LRP-1), in juxtaposition with hepatocytes. LSECs co-express two surface lectins called L-Specific Intercellular adhesion molecule-3 Grabbing Non-integrin Receptor (L-SIGN) and liver sinusoidal endothelial cell lectin (LSECtin). LSECs also express several adhesion molecules which are involved in the recruitment of leukocytes at the site of inflammation. Here, we review these cell surface receptors as well as other components expressed by LSECs and their functions in the maintenance of liver homeostasis. We further discuss receptor expression and activity and dysregulation associated with the initiation and progression of many liver diseases, such as hepatocellular carcinoma, liver fibrosis, and cirrhosis, alcoholic and non-alcoholic fatty liver diseases and pseudocapillarization with aging.

New aspects of hepatic endothelial cells in physiology and nonalcoholic fatty liver disease

The liver is the central metabolic hub for carbohydrate, lipid, and protein metabolism. It is composed of four major types of cells, including hepatocytes, endothelial cells (ECs), Kupffer cells, and stellate cells. Hepatic ECs are highly heterogeneous in both mice and humans, representing the second largest population of cells in liver. The majority of them line hepatic sinusoids known as liver sinusoidal ECs (LSECs). The structure and biology of LSECs and their roles in physiology and liver disease were reviewed recently. Here, we do not give a comprehensive review of LSEC structure, function, or pathophysiology. Instead, we focus on the recent progress in LSEC research and other hepatic ECs in physiology and nonalcoholic fatty liver disease and other hepatic fibrosis-related conditions. We discuss several current areas of interest, including capillarization, scavenger function, autophagy, cellular senescence, paracrine effects, and mechanotransduction. In addition, we summarize the strengths and weaknesses of evidence for the potential role of endothelial-to-mesenchymal transition in liver fibrosis.

ERK1/2-PPARγ pathway is involved in Chlamydia pneumonia-induced human umbilical vein endothelial cell apoptosis through increased LOX-1 expression

Chlamydia pneumonia (C.pn) is a common respiratory pathogen that is involved in human cardiovascular diseases and promotes the development of atherosclerosis in hyperlipidemic animal models. C.pn reportedly up-regulated lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) in endothelial cells. Recently, the anti-atherosclerotic activity of peroxisome proliferator-activated receptor γ (PPARγ) has been documented. In the present study, we investigated the effect of C.pn on LOX-1 expression in human umbilical vein endothelial cells (HUVECs) and identified the involvement of the PPARγ signaling pathway therein. The results showed that C.pn increased the expression of LOX-1 in HUVECs in a dose- and time-dependent manner. C.pn-induced up-regulation of LOX-1 was mediated by ERK1/2, whereas p38 MAPK and JNK had no effect on this process. C.pn induced apoptosis, inhibited cell proliferation, and decreased the expression PPARγ in HUVECs. Additionally, LOX-1 activity and cell injury caused by C.pn through activation of ERK1/2 was completely inhibited by rosiglitazone, a PPARγ agonist. In conclusion, we inferred that activation of PPARγ in HUVECs suppressed C.pn-induced LOX-1 expression and cell damage by inhibiting ERK1/2 signaling.

Detection of a High Ratio of Soluble to Membrane-Bound LOX-1 in Aspirated Coronary Thrombi From Patients With ST-Segment-Elevation Myocardial Infarction

Background

The circulating level of soluble lectin‐like oxidized low‐density lipoprotein receptor‐1 (sLOX‐1) is a valuable biomarker of acute myocardial infarction (AMI). The most electronegative low‐density lipoprotein, L5, signals through LOX‐1 to trigger atherogenesis. We examined the characteristics of LOX‐1 and the role of L5 in aspirated coronary thrombi of AMI patients.

Methods and Results

Intracoronary thrombi were aspirated by performing interventional thrombosuction in patients with ST‐segment–elevation myocardial infarction (STEMI; n=32) or non–ST‐segment–elevation myocardial infarction (n=12). LOX‐1 level and the ratio of sLOX‐1 to membrane‐bound LOX‐1 were higher in thrombi of STEMI patients than in those of non–ST‐segment–elevation myocardial infarction patients. In all aspirated thrombi, LOX‐1 colocalized with apoB100. When we explored the role of L5 in AMI, deconvolution microscopy showed that particles of L5 but not L1 (the least electronegative low‐density lipoprotein) quickly formed aggregates prone to retention in thrombi. Treating human monocytic THP‐1 cells with L5 or L1 showed that L5 induced cellular adhesion and promoted the differentiation of monocytes into macrophages in a dose‐dependent manner. In a second cohort of AMI patients, the L5 percentage and plasma concentration of sLOX‐1 were higher in STEMI patients (n=33) than in non–ST‐segment–elevation myocardial infarction patients (n=25), and sLOX‐1 level positively correlated with L5 level in AMI patients.

Conclusions

The level of LOX‐1 and the ratio of sLOX‐1 to membrane‐bound LOX‐1 in aspirated thrombi, as well as the circulating level of sLOX‐1 were higher in STEMI patients than in non–ST‐segment–elevation myocardial infarction patients. L5 may play a role in releasing a high level of sLOX‐1 into the circulation of STEMI patients.

Inhibition of β-amyloid-induced neurotoxicity by planar analogues of procyanidin B3

Reactive oxygen species (ROS) are known to be produced during the amyloid beta (Aβ) aggregation process. Both ROS production and Aβ fibril formation can result in nerve cell injury. Proanthocyanidins are oligomers of catechin that can act as inhibitors of Aβ aggregation. Procyanidin B3 (Cat-Cat), the dimer of (+)-catechin, can easily cross the blood-brain barrier. Previously, we synthesized two derivatives of Cat-Cat, namely Cat-PCat and PCat-PCat, in which the geometry of one or both catechin molecules in Cat-Cat was constrained to be planar. The antioxidative activities of Cat-PCat and PCat-PCat were found to be stronger than that of Cat-Cat, with PCat-PC at exhibiting the most potent activity. These compounds are predicted to protect against Aβ-induced neurotoxicity via inhibition of Aβ aggregation as well as by antioxidative effects toward Aβ-induced intracellular ROS generation. PCat-PCat exhibited the most potent neuroprotective effects against Aβ-induced cytotoxicity, which resulted from inhibition of β-sheet structure formation during the Aβ aggregation process. PCat-PCat may be a promising lead compound for the treatment of Alzheimer's disease.

LOX-1: Regulation, Signaling and Its Role in Atherosclerosis

Atherosclerosis has long been known to be a chronic inflammatory disease. In addition, there is intense oxidative stress in atherosclerosis resulting from an imbalance between the excess reactive oxygen species (ROS) generation and inadequate anti-oxidant defense forces. The excess of the oxidative forces results in the conversion of low-density lipoproteins (LDL) to oxidized LDL (ox-LDL), which is highly atherogenic. The sub-endothelial deposition of ox-LDL, formation of foamy macrophages, vascular smooth muscle cell (VSMC) proliferation and migration, and deposition of collagen are central pathophysiologic steps in the formation of atherosclerotic plaque. Ox-LDL exerts its action through several different scavenger receptors, the most important of which is LOX-1 in atherogenesis. LOX-1 is a transmembrane glycoprotein that binds to and internalizes ox-LDL. This interaction results in variable downstream effects based on the cell type. In endothelial cells, there is an increased expression of cellular adhesion molecules, resulting in the increased attachment and migration of inflammatory cells to intima, followed by their differentiation into macrophages. There is also a worsening endothelial dysfunction due to the increased production of vasoconstrictors, increased ROS, and depletion of endothelial nitric oxide (NO). In the macrophages and VSMCs, ox-LDL causes further upregulation of the LOX-1 gene, modulation of calpains, macrophage migration, VSMC proliferation and foam cell formation. Soluble LOX-1 (sLOX-1), a fragment of the main LOX-1 molecule, is being investigated as a diagnostic marker because it has been shown to be present in increased quantities in patients with hypertension, diabetes, metabolic syndrome and coronary artery disease. LOX-1 gene deletion in mice and anti-LOX-1 therapy has been shown to decrease inflammation, oxidative stress and atherosclerosis. LOX-1 deletion also results in damage from ischemia, making LOX-1 a promising target of therapy for atherosclerosis and related disorders. In this article we focus on the different mechanisms for regulation, signaling and the various effects of LOX-1 in contributing to atherosclerosis.

Ginkgolide B ameliorates oxidized low-density lipoprotein-induced endothelial dysfunction via modulating Lectin-like ox-LDL-receptor-1 and NADPH oxidase 4 expression and inflammatory cascades

The current study was undertaken to delineate the protective effect of Ginkgolide B, a phyto-constituent from Ginkgo biloba, on oxidized (ox)-LDL-induced endothelial dysfunction via targeting Lectin-like ox-LDL-receptor-1 (LOX-1), NADPH oxidase 4 (NOX-4), and other inflammatory proteins. Our results have shown that Ginkgolide B downregulated the expression of LOX-1 in ox-LDL-treated human umbilical vein endothelial cells (HUVECs) and RAW246.7 murine macrophages which ultimately resulted in decreased cholesterol deposits in HUVECs and RAW264.7. Moreover, Ginkgolide B suppressed the enhanced NOX4 expression, which was associated with attenuation of ROS generation in ox-LDL-stimulated HUVECs and RAW264.7 cells. Ginkgolide B also ameliorated the endothelial dysfunction by inhibiting the augmented expression of monocyte chemotactic protein-1 (MCP-1), intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) in ox-LDL-activated HUVECs. Furthermore, the enhanced expression of many inflammatory cytokines in ox-LDL-induced RAW264.7 macrophages, both at transcription and protein level, was significantly down-regulated after Ginkgolide B treatment. Ginkgolide B also illustrated atheroprotective property via suppressing the augmented expression of matrix metalloproteinase-1 and cyclooxygenase-2 in ox-LDL-stimulated RAW264.7 macrophages. In summary, our study has established that Ginkgolide B ameliorates endothelial dysfunction via targeting LOX-1, NOX-4, MCP-1, ICAM-1, and VCAM-1 along with the markers associated with inflammatory cascades and thus could be promoted as a valuable therapeutic agent in prevention and management of atherosclerosis.

Primary prevention of atherosclerosis by pretreatment of low-density lipoprotein receptor knockout mice with sesame oil and its aqueous components

Pharmacological intervention using statins and PCSK9 inhibitors have become first-line therapy in the prevention of hypercholesterolemia and atherosclerosis. Currently, no agent is available for the primary prevention of atherosclerosis. However, there is an emerging hypothesis that atherosclerosis could be driven by inflammation. In this study, we tested whether pretreatment with an aqueous extract from sesame oil (SOAE), which showed potent anti-inflammatory properties without hypocholesterolemic actions, would prevent subsequent atherosclerosis development in a mouse model. RAW 264.7 macrophages and female low-density lipoprotein receptor knockout (LDLR^−/−) mice were used for in vitro and in vivo studies, respectively. Plasma lipids, cytokines and atherosclerotic lesions were quantified at the end of the study. RNA was extracted from the liver and aortic tissues and used for gene analysis. Pre-treatment of SOAE prevented Ox-LDL uptake by RAW macrophages and further inflammation in vitro. SOAE pre-treatment significantly reduced atherosclerotic lesions and pro-inflammatory gene expressions in LDLR^−/− mice as compared to control mice. No significant change in plasma cholesterol levels was observed. A significant reduction in plasma levels of TNF-α, IL-6, MCP-1 and VCAM1 was observed in the SOAE pre-treated animals. This is the first study that demonstrates that pre-treatment with anti-inflammatory agents, could delay/decrease atherosclerosis.

Ecrg4 peptide is the ligand of multiple scavenger receptors

Esophageal cancer-related gene 4 (Ecrg4) encodes a hormone-like peptide that is believed to be involved in a variety of physiological phenomena, including tumour suppression. Recent progress in the study of Ecrg4 has shown that Ecrg4 is a proinflammatory factor and induces the expression of several cytokines and chemokines in macrophages/microglia. However, the detailed molecular mechanisms of Ecrg4 signalling, especially the Ecrg4 receptors, remain poorly understood. Here, using retrovirus-mediated expression cloning, we identified lectin-like oxidised low-density lipoprotein receptor-1 (LOX-1) as a membrane protein that binds amino acid residues 71–132 of Ecrg4 (Ecrg4(71–132)). Moreover, in addition to LOX-1, several scavenger receptors, such as Scarf1, Cd36 and Stabilin-1, facilitated the efficient internalisation of Ecrg4(71–132) into cells. A broad competitive inhibitor of scavenger receptors, polyinosinic acid, reduced both the binding of Ecrg4(71–132) and the activation of NF-κB in microglia. This activation was dependent on MyD88, an adaptor protein that recruits signalling proteins to Toll-like receptors (TLRs), with the consequent induction of various immune responses. These data suggest that multiple scavenger receptors recognise Ecrg4(71–132) and transduce its signals, together with TLRs, in microglia.

LOX-1 receptor: A potential link in atherosclerosis and cancer

Altered production of reactive oxygen species (ROS), causing lipid peroxidation and DNA damage, contributes to the progression of atherosclerosis and cancer. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a lectin-like receptor for oxidized low-density lipoproteins (ox-LDL) primarily expressed in endothelial cells and vasculature-rich organs. LOX-1 receptors is a marker for atherosclerosis, and once activated by ox-LDL or other ligands, stimulates the expression of adhesion molecules, pro-inflammatory signaling pathways and proangiogenic proteins, including NF-kB and VEGF, in vascular endothelial cells and macrophages. Several different types of cancer reported LOX-1 gene upregulation, and numerous interplays exist concerning LOX-1 in atherosclerosis, metabolic diseases and cancer. One of them involves NF-kB, an oncogenic protein that regulates the transcription of several inflammatory genes response. In a model of cellular transformation, the MCF10A ER-Src, inhibition of LOX-1 gene reduces NF-kB activation and the inflammatory and hypoxia pathways, suggesting a mechanistic connection between cellular transformation and atherosclerosis. The remodeling proteins MMP-2 and MMP-9 have been found increased in angiogenesis in atherosclerotic plaque and also in human prostate cancer cells. In this review, we outlined the role of LOX-1 in atherogenesis and tumorigenesis as a potential link in these diseases, suggesting that LOX-1 inhibition could represent a promising strategy in the treatment of atherosclerosis and tumors.

Increased Levels of Lectin-Like Oxidized Low-Density Lipoprotein Receptor-1 in Ischemic Stroke and Transient Ischemic Attack

Background

Soluble lectin‐like oxidized low‐density lipoprotein receptor‐1 (sLOX‐1) has been shown to be increased in patients with acute ischemic stroke. Here, we evaluated plasma sLOX‐1 levels and vascular carotid plaque LOX‐1 (ie, OLR1) gene expression in patients with ischemic stroke and transient ischemic attack (TIA) with particular focus on their relation to time since symptom onset.

Methods and Results

Plasma sLOX‐1 (n=232) and carotid plaque OLR1 gene expression (n=146) were evaluated in patients who were referred to evaluation for carotid endarterectomy, as well as in healthy control plasma (n=81). Patients were categorized according to presence of acute ischemic stroke or transient ischemic attack (n=35) ≤7 days, >7 days ≤3 months (n=90), >3 months (n=40), or no reported symptoms before study inclusion (n=67). Our major findings were the following: (1) Patients with carotid atherosclerosis had increased plasma sLOX‐1 levels as compared with controls. (2) Plaque OLR1 mRNA levels were increased in carotid plaques (n=146) compared with nonatherosclerotic vessels (ie, common iliac arteries of organ donors, n=10). (3) There were no differences in sLOX plasma levels or OLR1 gene expression when analyzed according to the time since relevant cerebral ischemic symptoms. (4) Also patients with severe carotid atherosclerosis without any previous ischemic events had raised sLOX‐1 levels. (5) Immunostaining showed colocalization between LOX‐1 and macrophages within the carotid plaques. (6) Also patients with acute stroke (within 7 days) caused by atrial fibrillation (n=22) had comparable raised sLOX‐1 levels.

Conclusions

sLOX‐1 levels are elevated in patients with ischemic stroke and transient ischemic attack independent of cause and time since the ischemic event.

Enhanced radical scavenging activity of a procyanidin B3 analogue comprised of a dimer of planar catechin

Proanthocyanidins are oligomers of catechins that exhibit potent antioxidative activity and inhibit binding of oxidized low-density lipoprotein (OxLDL) to the lectin-like oxidized LDL receptor (LOX-1), which is involved in the onset and development of arteriosclerosis. Previous attempts aimed at developing proanthocyanidin derivatives with more potent antioxidative activity and stronger inhibition for LOX-1 demonstrated the synthesis of a novel proanthocyanidin derivative (1), in which the geometry of one catechin molecule in procyanidin B3 was constrained to a planar orientation. The radical scavenging activity of 1 was 1.9-fold higher than that of procyanidin B3. Herein, we synthesized another procyanidin B3 analogue (2), in which the geometries of both catechin molecules in the dimer were constrained to planar orientations. The radical scavenging activity of 2 was 1.5-fold higher than that of 1, suggesting that 2 may be a more effective candidate than 1 as a therapeutic agent to reduce oxidative stress induced in arteriosclerosis or related cerebrovascular disease.

Advanced Maternal Age Worsens Postpartum Vascular Function

The age at which women experience their first pregnancy has increased throughout the decades. Pregnancy has an important influence on maternal short- and long-term cardiovascular outcomes. Pregnancy at an advanced maternal age increases maternal risk of gestational diabetes, preeclampsia, placenta previa and caesarian delivery; complications which predict worsened cardiovascular health in later years. Aging also independently increases the risk of cardiovascular disease; therefore, combined risk in women of advanced maternal age may lead to detrimental cardiovascular outcomes later in life. We hypothesized that pregnancy at an advanced maternal age would lead to postpartum vascular dysfunction. We used a reproductively aged rat model to investigate vascular function in never pregnant (virgin), previously pregnant (postpartum) and previously mated but never delivered (nulliparous) rats at approximately 13.5 months of age (3 months postpartum or equivalent). Nulliparous rats, in which pregnancy was spontaneously lost, demonstrated significantly reduced aortic relaxation responses (methylcholine [MCh] Emax: 54.2 ± 12.6%) vs. virgin and postpartum rats (MCh Emax: 84.8 ± 3.5% and 84.7 ± 3.2% respectively); suggesting pregnancy loss causes a worsened vascular pathology. Oxidized LDL reduced relaxation to MCh in aorta from virgin and postpartum, but not nulliparous rats, with an increased contribution of the LOX-1 receptor in the postpartum group. Further, in mesenteric arteries from postpartum rats, endothelium-derived hyperpolarization (EDH)-mediated vasodilation was reduced and a constrictive prostaglandin effect was apparent. In conclusion, aged postpartum rats exhibited vascular dysfunction, while rats which had pregnancy loss demonstrated a distinct vascular pathology. These data demonstrate mechanisms which may lead to worsened outcomes at an advanced maternal age; including early pregnancy loss and later life cardiovascular dysfunction.

Lectin-like oxidized low-density lipoprotein receptor-1 facilitates metastasis of gastric cancer through driving epithelial-mesenchymal transition and PI3K/Akt/GSK3β activation

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a pattern recognition receptor that plays a critical role in vascular diseases and host immune response. Recently, our research discovered that LOX-1 could facilitate the uptake of dying cells and cross-presentation of cellular antigen via binding with heat shock proteins, which have a close relationship with gastric neoplasia. Therefore, we speculated that LOX-1 may serve as an oncogene in gastric cancer (GC) development and progression. In this study, through immunohistochemistry staining assay and cancer-related databases, we found that LOX-1 expression was up-regulated in GC tissues and correlated with a poor prognosis in GC patients. The expression of LOX-1 was an independent prognostic factor for OS in GC patients, and the incorporation of LOX-1 with TNM stage is more accurate for predicting prognosis. Additionally, in vitro study by transwell assay and western blot analysis confirmed that LOX-1 could promote the migration and invasion of GC cells by driving epithelial-mesenchymal transition and PI3K/Akt/GSK3β activation. Taken together, we first explored the expression profiles, clinical significance and biological function of LOX-1 in GC, and these data suggest that LOX-1 may represent a promising prognostic biomarker for GC and offer a novel molecular target for GC therapies.

IL-7δ5 protein is expressed in human tissues and induces expression of the oxidized low density lipoprotein receptor 1 (OLR1) in CD14+ monocytes

OBJECTIVES

The 6-exon-spanning 'canonical' Interleukin-7 (IL-7c) is a non-redundant cytokine in human T-cell homeostasis that undergoes extensive alternative pre-mRNA splicing. The IL-7 gene variant lacking, exon 5 (IL-7δ5), exhibits agonistic effects as compared to IL-7c. We studied in this report for the first time the protein expression of IL-7δ5 variant in tissues and its role in monocyte activation.

METHODS

We visualized the expression of IL-7δ5 protein by immunohistochemistry in both healthy and malignant (human) tissues and investigated the impact of IL-7δ5 stimulation on CD14+ monocytes using gene expression analysis and flow cytometry.

RESULTS

IL-7δ5 is largely expressed by human epithelial cells, yet also by stromal cells in malignant lesions. Gene expression analysis in CD14+ monocytes, induced by the 6-exon spanning IL-7 or IL-7δ5 showed similar changes resulting in a pro-inflammatory phenotype and increased expression of genes involved in lipid metabolism. IL7δ5 was superior in inducing upregulation of the oxidised low density lipoprotein receptor (OLR), measured by flow cytometry, in CD14+ cells.

CONCLUSION

IL-7δ5, produced from non-transformed and transformed cells, may contribute to chronic inflammatory responses and development of 'foamy' cells by increased OLR1 expression that mediates increased oxLDL uptake.

LOX-1 and TLR4 affect each other and regulate the generation of ROS in A. fumigatus keratitis

PURPOSE

To explore the relationship between LOX-1 and TLR4 in Aspergillus fumigatus (A. fumigatus) keratitis. To determine LOX-1 and TLR4 can affect each other and regulate inflammation through regulation of the generation of reactive oxygen species (ROS) in A. fumigatus keratitis.

METHODS

The cornea and abdominal cavity extracted neutrophils of susceptible C57BL/6 mice were infected with A. fumigatus. The cornea and neutrophils were pretreated with LOX-1 neutralizing antibody, Polyinosinic acid (Poly(I)) (the inhibitor of LOX-1) or CLI-095 (the inhibitor of TLR4) separately before infection. LOX-1, TLR4 and IL-1β expression were detected in normal and infected cornea by PCR and Western Blot, while ROS was detected in the neutrophils by flow cytometry.

RESULTS

LOX-1, TLR4, IL-1β mRNA and protein levels were up-regulated in C57BL/6 cornea after infection. LOX-1 neutralizing antibody or Poly(I) pretreatment decreased the expression of LOX-1, TLR4 and IL-1β in C57BL/6 cornea after infection and CLI-095 pretreatment decreased the expression of LOX-1, TLR4 and IL-1β in C57BL/6 cornea after infection. ROS generation was increased in C57BL/6 neutrophils after infection, however, ROS generation was decreased in C57BL/6 neutrophils after infection by LOX-1 neutralizing antibody or Poly(I) or CLI-095 pretreatment.

CONCLUSION

LOX-1, TLR4 and IL-1β expression and ROS generation are increased after infection. LOX-1 and TLR4 can affect each other and regulate the generation of ROS in A. fumigatus keratitis. Inhibition of LOX-1 and TLR4 can reduce ROS generation.

Mechanism of tacrolimus-induced chronic renal fibrosis following transplantation is regulated by ox-LDL and its receptor, LOX-1

Chronic renal allograft dysfunction (CRAD) is the most common cause of graft failure following renal transplantation. However, the underlying mechanisms remain to be fully elucidated. Immunosuppressants and hyperlipidemia are associated with renal fibrosis following long-term use. The present study aimed to determine the effects of tacrolimus (FK506) and lipid metabolism disorder on CRAD. In vitro and in vivo models were used for this investigation. Cells of the mouse proximal renal tubular epithelial cell strain, NRK-52E, were cultured either with oxidized low-density lipoprotein (ox-LDL), FK506, ox-LDL combined with FK506, or vehicle, respectively. Changes in cell morphology and changes in the levels of lectin-like ox-LDL receptor-1 (LOX-1), reactive oxygen species (ROS), hydrogen peroxide and fibrosis-associated genes were evaluated at 24, 48 and 72 h. In separate experiment, total of 60 Sprague-Dawley rats were divided randomly into four groups, which included a high-fat group, FK506 group, high-fat combined with FK506 group, and control group. After 2, 4 and 8 weeks, the serum lipid levels, the levels of ox-LDL, ROS, and the expression levels of transforming growth factor (TGF)-β1 and connective tissue growth factor were determined. The in vitro and in vivo models revealed that lipid metabolism disorder and FK506 caused oxidative stress and a fibrogenic response. In addition, decreased levels of LOX-1 markedly reduced the levels of TGF-β1 in the in vitro model. Taken together, FK506 and dyslipidemia were found to be associated with CRAD following transplantation.

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) in sickle cell disease vasculopathy

Lectin-like oxidized low-density lipoprotein (LDL) receptor-1 (LOX-1) is an endothelial receptor for oxidized LDL. Increased expression of LOX-1 has been demonstrated in atherosclerotic lesions and diabetic vasculopathy. In this study, we investigate the expression of LOX-1 receptor in sickle cell disease (SCD) vasculopathy. Expression of LOX-1 in brain vascular endothelium is markedly increased and LOX-1 gene expression is upregulated in cultured human brain microvascular endothelial cells by incubation with SCD erythrocytes. Also, the level of circulating soluble LOX-1 concentration is elevated in the plasma of SCD patients. Increased LOX-1 expression in endothelial cells is potentially involved in the pathogenesis of SCD vasculopathy. Soluble LOX-1 concentration in SCD may provide a novel biomarker for risk stratification of sickle cell vascular complications.

Hyperlipidemia-associated gene variations and expression patterns revealed by whole-genome and transcriptome sequencing of rabbit models

The rabbit (Oryctolagus cuniculus) is an important experimental animal for studying human diseases, such as hypercholesterolemia and atherosclerosis. Despite this, genetic information and RNA expression profiling of laboratory rabbits are lacking. Here, we characterized the whole-genome variants of three breeds of the most popular experimental rabbits, New Zealand White (NZW), Japanese White (JW) and Watanabe heritable hyperlipidemic (WHHL) rabbits. Although the genetic diversity of WHHL rabbits was relatively low, they accumulated a large proportion of high-frequency deleterious mutations due to the small population size. Some of the deleterious mutations were associated with the pathophysiology of WHHL rabbits in addition to the LDLR deficiency. Furthermore, we conducted transcriptome sequencing of different organs of both WHHL and cholesterol-rich diet (Chol)-fed NZW rabbits. We found that gene expression profiles of the two rabbit models were essentially similar in the aorta, even though they exhibited different types of hypercholesterolemia. In contrast, Chol-fed rabbits, but not WHHL rabbits, exhibited pronounced inflammatory responses and abnormal lipid metabolism in the liver. These results provide valuable insights into identifying therapeutic targets of hypercholesterolemia and atherosclerosis with rabbit models.

Deletion of LOX-1 Protects against Heart Failure Induced by Doxorubicin

Oxidative stress is one of the major factors in doxorubicin (DOX)-induced cardiomyopathy. Lectin-like oxidized low-density lipoprotein (oxLDL) receptor-1 (LOX-1) plays an important role to regulate cardiac remodeling and oxidative stress after ischemia-reperfusion. Therefore, we examined whether or not LOX-1 contributes to the pathogenesis of DOX-induced cardiomyopathy. Cardiomyopathy was induced by a single intraperitoneal injection of DOX into wild-type (WT) mice and LOX-1 knockout (KO) mice. Echocardiography and catheter-based hemodynamic assessment apparently revealed preserved left ventricular (LV) fractional shortening (FS) and cavity size of LOX-1 KO mice compared with those of WT mice after DOX administration. Less production of tumor necrosis factor alpha (TNF-α) and interleukin-1 beta (IL-1ß) was observed in LOX-1 KO mice than WT mice after DOX administration. Western blotting analysis also showed lower activation of nuclear factor κB (NF-κB) and p38 mitogen-activated protein kinase (MAPK) in LOX-1 KO mice treated with DOX than WT mice treated with DOX. In fact, NF-κB-dependent gene expressions of LOX-1 and vascular cell adhesion molecule-1 (VCAM-1) were suppressed in LOX-1 KO mice treated with DOX compared with WT mice treated with DOX. Therefore, histological analyses showed attenuation of leukocyte infiltration and cardiac fibrosis in LOX-1 KO mice compared with WT mice. Meanwhile, extracellular signal-regulated kinase MAPK (ERK) inactivation and decreased expression of sarcomeric proteins and related transcription factor GATA-4 in WT mice treated with DOX administration were not seen in LOX-1 KO mice treated with DOX administration and WT and LOX-1 KO mice treated with vehicle. Decreased expression of sarcometric proteins resulted in smaller diameters of cardiomyocytes in WT mice than in LOX-1 KO mice after DOX treatment. The expression of LOX-1 in cardiomyocytes was much more abundant than that in endothelial cells, fibroblasts and inflammatory cells. Endothelial cells, fibroblasts and inflammatory cells treated with DOX showed no elevated LOX-1 expression compared with those treated with vehicle. However, cardiomyocytes treated with DOX showed much more expression of LOX-1 than those treated with vehicle. Immunohistochemistry study also showed that LOX-1 expression was strongly elevated in cardiomyocytes in the heart tissue of mice treated with DOX in vivo. We conclude that LOX-1 in cardiomyocytes plays the most important roles in the pathology of DOX-induced cardiomyopathy. LOX-1 deletion altered the LOX-1-related signaling pathway, which led to improvements in cardiac function, myocardial inflammation, fibrosis and degenerative changes after DOX treatment.

Roles of LOX-1 in microvascular dysfunction

Studies from human and animal models with metabolic disease and hypertension highlight atrophic remodeling, reduced lumen size and thinner vascular walls of microvessels with profound density reduction. This impaired vascular response limits the perfusion of peripheral tissues inducing organ damage. These conditions are strongly associated with oxidative stress and in particular with the up-regulation of lectin-like oxidized low density lipoprotein receptor-1 (LOX-1). Several factors such as cytokines, shear stress, and advanced glycation end-products, especially oxLDL, can up-regulate LOX-1. The activation of this receptor induces the production of adhesion molecules, cytokines and the release of reactive oxygen species via NADPH oxidase. LOX-1 is considered a potent mediator of endothelial dysfunction and it is significantly associated with reduced microvascular endothelium NO-dependent vasodilation in hypercholesterolemia and hypertension. Microvascular endothelial cells increased the expression of IL-6 in association with the increased concentration of LDL and its degree of oxidation. Moreover, increased IL-6 levels are associated with up-regulation of LOX-1 in a dose-dependent manner. Another consequence of microvascular inflammation is the generation of small amounts of ROS, similar to those induced by low concentration of oxLDL (<5 μg/mL) which induces capillary tube formation of endothelial cells, through LOX-1 up-regulation. In light of its central role, LOX-1 represents an attractive therapeutic target for the treatment of human atherosclerotic diseases and microvascular disorders.

Plasma L5 levels are elevated in ischemic stroke patients and enhance platelet aggregation

L5, the most electronegative and atherogenic subfraction of low-density lipoprotein (LDL), induces platelet activation. We hypothesized that plasma L5 levels are increased in acute ischemic stroke patients and examined whether lectin-like oxidized LDL receptor-1 (LOX-1), the receptor for L5 on endothelial cells and platelets, plays a critical role in stroke. Because amyloid β (Aβ) stimulates platelet aggregation, we studied whether L5 and Aβ function synergistically to induce prothrombotic pathways leading to stroke. Levels of plasma L5, serum Aβ, and platelet LOX-1 expression were significantly higher in acute ischemic stroke patients than in controls without metabolic syndrome (P < .01). In mice subjected to focal cerebral ischemia, L5 treatment resulted in larger infarction volumes than did phosphate-buffered saline treatment. Deficiency or neutralizing of LOX-1 reduced infarct volume up to threefold after focal cerebral ischemia in mice, illustrating the importance of LOX-1 in stroke injury. In human platelets, L5 but not L1 (the least electronegative LDL subfraction) induced Aβ release via IκB kinase 2 (IKK2). Furthermore, L5+Aβ synergistically induced glycoprotein IIb/IIIa receptor activation; phosphorylation of IKK2, IκBα, p65, and c-Jun N-terminal kinase 1; and platelet aggregation. These effects were blocked by inhibiting IKK2, LOX-1, or nuclear factor-κB (NF-κB). Injecting L5+Aβ shortened tail-bleeding time by 50% (n = 12; P < .05 vs L1-injected mice), which was prevented by the IKK2 inhibitor. Our findings suggest that, through LOX-1, atherogenic L5 potentiates Aβ-mediated platelet activation, platelet aggregation, and hemostasis via IKK2/NF-κB signaling. L5 elevation may be a risk factor for cerebral atherothrombosis, and downregulating LOX-1 and inhibiting IKK2 may be novel antithrombotic strategies.

Role of 4-hydroxynonenal-protein adducts in human diseases

SIGNIFICANCE

Oxidative stress provokes the peroxidation of polyunsaturated fatty acids in cellular membranes, leading to the formation of aldheydes that, due to their high chemical reactivity, are considered to act as second messengers of oxidative stress. Among the aldehydes formed during lipid peroxidation (LPO), 4-hydroxy-2-nonenal (HNE) is produced at a high level and easily reacts with both low-molecular-weight compounds and macromolecules, such as proteins and DNA. In particular, HNE-protein adducts have been extensively investigated in diseases characterized by the pathogenic contribution of oxidative stress, such as cancer, neurodegenerative, chronic inflammatory, and autoimmune diseases.

RECENT ADVANCES

In this review, we describe and discuss recent insights regarding the role played by covalent adducts of HNE with proteins in the development and evolution of those among the earlier mentioned disease conditions in which the functional consequences of their formation have been characterized.

CRITICAL ISSUES

Results obtained in recent years have shown that the generation of HNE-protein adducts can play important pathogenic roles in several diseases. However, in some cases, the generation of HNE-protein adducts can represent a contrast to the progression of disease or can promote adaptive cell responses, demonstrating that HNE is not only a toxic product of LPO but also a regulatory molecule that is involved in several biochemical pathways.

FUTURE DIRECTIONS

In the next few years, the refinement of proteomical techniques, allowing the individuation of novel cellular targets of HNE, will lead to a better understanding the role of HNE in human diseases.

Infection with Chlamydia pneumoniae as a cause of coronary heart disease: the hypothesis is still untested

Review of the possible role of Chlamydia pneumoniae infection in the pathogenesis of heart disease.

Oxidized low-density lipoprotein is associated with advanced-stage prostate cancer

Clinical and epidemiological data suggest coronary artery disease shares etiology with prostate cancer (PCa). The aim of this work was to assess the effects of several serum markers reported in cardiovascular disease on PCa. Serum markers (oxidized low-density lipoprotein [ox-LDL], apolipoprotein [apo] B100, and apoB48) in peripheral blood samples from 50 patients from Fudan University Shanghai Cancer Center (FUSCC) with localized or lymph node metastatic PCa were investigated in this study. Twenty-five samples from normal individuals were set as controls. We first conducted enzyme-linked immunosorbent assay analysis to select candidate markers that were significantly different between these patients and controls. Then, the clinical relevance between OLR1 (the ox-LDL receptor) expression and PCa was analyzed in The Cancer Genome Atlas (TCGA) cohort. We also investigated the function of ox-LDL in PCa cell lines in vitro. Phosphorylation protein chips were used to analyze cell signaling pathways in ox-LDL-treated PC-3 cells. The ox-LDL level was found to be significantly correlated with N stage of prostate cancer. OLR1 expression was correlated with lymph node metastasis in the TCGA cohort. In vitro, ox-LDL stimulated the proliferation, migration, and invasion of LNCaP and PC-3 in a dose-dependent manner. The results of phosphoprotein microarray illustrated that ox-LDL could influence multiple signaling pathways of PC-3. Activation of proliferation promoting signaling pathways (including β-catenin, cMyc, NF-κB, STAT1, STAT3) as well as apoptosis-associating signaling pathways (including p27, caspase-3) demonstrated that ox-LDL had complicated effects on prostate cancer. Increased serum ox-LDL level and OLR1 expression may indicate advanced-stage PCa and lymph node metastasis. Moreover, ox-LDL could stimulate PCa proliferation, migration, and invasion in vitro.

LOX-1 plays an important role in ischemia-induced angiogenesis of limbs

LOX-1, lectin-like oxidized low-density lipoprotein (LDL) receptor-1, is a single transmembrane receptor mainly expressed on endothelial cells. LOX-1 mediates the uptake of oxidized LDL, an early step in atherosclerosis; however, little is known about whether LOX-1 is involved in angiogenesis during tissue ischemia. Therefore, we examined the role of LOX-1 in ischemia-induced angiogenesis in the hindlimbs of LOX-1 knockout (KO) mice. Angiogenesis was evaluated in a surgically induced hindlimb ischemia model using laser Doppler blood flowmetry (LDBF) and histological capillary density (CD) and arteriole density (AD). After right hindlimb ischemia, the ischemic/nonischemic hindlimb blood flow ratio was persistently lower in LOX-1 KO mice than in wild-type (WT) mice. CD and AD were significantly smaller in LOX-1 KO mice than in WT mice on postoperative day 14. Immunohistochemical analysis revealed that the number of macrophages infiltrating ischemic tissues was significantly smaller in LOX-1 KO mice than in WT mice. The number of infiltrated macrophages expressing VEGF was also significantly smaller in LOX-1 KO mice than in WT mice. Western blot analysis and ROS production assay revealed that LOX- KO mice show significant decrease in Nox2 expression, ROS production and HIF-1α expression, the phosphorylation of p38 MAPK and NF-κB p65 subunit as well as expression of redox-sensitive vascular cell adhesion molecule-1 (VCAM-1) and LOX-1 itself in ischemic muscles, which is supposed to be required for macrophage infiltration expressing angiogenic factor VEGF. Reduction of VEGF expression successively suppressed the phosphorylation of Akt and eNOS, which accelerated angiogenesis, in the ischemic leg of LOX-1 KO mice. Our findings indicate that LOX-1 plays an important role in ischemia-induced angiogenesis by 1) Nox2-ROS-NF-κB activation, 2) upregulated expression of adhesion molecules: VCAM-1 and LOX-1 and 3) promoting macrophage infiltration, which expresses angiogenic factor VEGF.

Association of LOXIN, a new functional splicing isoform of the OLR1 gene, with severity and prognostic localization of critical coronary artery stenoses

AIMS

To evaluate the association between LOXIN, a new functional protective splicing isoform of the oxidized LDL receptor 1 (OLR1) gene, and the severity of coronary artery stenoses.

METHODS

We analyzed 100 consecutive patients with coronary artery disease (CAD) and 100 controls, all evaluated by a new molecular biology test using highly specific allele primers able to identify the single nucleotide variation (IVS4-14 A>G) in the OLR1 gene (Loxin Test - Technogenetics). All the patients and the controls underwent coronary angiography and, for quantitative evaluation, we used both vessel and stenosis score, and SYNTAX score to evaluate the severity of CAD. Moreover, we defined the prognostic localization of CAD as a critical stenosis (>50%) of the left main and/or proximal segment of left anterior descending artery (LAD). Finally, we evaluated a correlation with the presence of diabetes mellitus, dyslipidemia, hypertension, smoking and family history of CAD.

RESULTS

In this selected population, even though the 'AA nonrisk haplotype' is more frequent in the controls, we did not find any statistically significant correlation between the severity of CAD or the prognostic localization of critical stenosis and the difference of IVS4-14 A>G OLR1 genotype (P > 0.05). CAD patients showed significantly higher frequencies of dyslipidemia and smoking (P < 0.05) than controls, but no significant association was found between overall risk factors and the OLR1 polymorphism.

CONCLUSION

In this selected population, we did not find any correlation of LOXIN with the severity or prognostic localization of CAD on left main and/or proximal LAD.

Serum lectin-like oxidized-low density lipoprotein receptor-1 and adiponectin levels are associated with coronary artery disease accompanied with metabolic syndrome

Background:

Coronary artery disease (CAD) is a major public health problem for developed and developing countries and is the single leading cause of death worldwide.

Objectives:

There is very few evidence regarding changes of both serum Lectin-like oxidized-low density lipoprotein receptor-1 (LOX-1) and adiponectin in patients with CAD accompanied with metabolic syndrome (MS). Here we aimed to evaluate serum levels of LOX-1 and adiponectin in patients with CAD accompanied with MS.

Patients and Methods:

Thirty patients with coronary artery disease without metabolic syndrome, 30 patients with coronary artery disease and metabolic syndrome, 30 ones with metabolic syndrome and 30 healthy subjects were enrolled. For all subjects, a questionnaire was filled to collect data, and peripheral blood samples were collected aseptically from the antecubital vein to measure serum Lectin-like oxidized-low density lipoprotein receptor-1 and adiponectin levels by enzyme-linked immunosorbent assay.

Results:

Serum LOX-1 level was highest in CAD + MS group; the difference between control and disease groups was statistically significant (P < 0.001). Adiponectin level had the lowest value in CAD + MS group; the difference between control and disease groups was statistically significant (P < 0.05). No significant differences were observed in serum Lectin-like oxidized-low density lipoprotein receptor-1and adiponectin in patients with different ages and gender. Serum LOX-1 level was changed negatively and linearly (R2 = 0.721) correlated with adiponectin level in different groups.

Conclusions:

Patient with CAD and MS had higher risk than those with only CAD because of lipid and glucose metabolism abnormalities. Combination measurements of serum LOX-1 and adiponectin levels may be helpful to evaluate the severity of CAD together with MS.

Ox-LDL induces endothelial cell apoptosis via the LOX-1-dependent endoplasmic reticulum stress pathway

OBJECTIVE

To investigate the effect of lectin-like ox-LDL receptor-1 (LOX-1) on oxidized low-density lipoprotein (ox-LDL)-induced apoptosis and the involvement of the endoplasmic reticulum (ER) stress response pathway.

METHODS AND RESULTS

Human umbilical vein endothelial cells were treated with 50, 100, or 200 μg/ml ox-LDL and cultured for 12, 24, or 48 h for concentration- and time-dependent studies. Cells were transfected with LOX-1 or Nox-4 shRNAs, and target proteins were inhibited with the corresponding antibodies for mechanistic studies. Active proteins and mRNAs were analyzed by Western blotting and RT-PCR, respectively. Cell apoptosis was analyzed by Annexin and Hoechst staining assays. Ox-LDL induced both apoptosis and protein expression of LOX-1 and Nox-4 through activation of ER stress sensors IRE1 and PERK, and nuclear translocation of ATF6 and their subsequent pathways were indicated by JNK, eukaryotic initiation factor 2 phosphorylation, XBP-1, and chaperone GRP78 expression; up-regulation of proapoptotic proteins CHOP and Bcl-2; and caspase-12 activity. LOX-1 gene silencing and treatment with an anti-LOX-1 antibody attenuated the effects of ox-LDL. Pretreatment with irestatin 9389, salubrinal, or AEBSF also blocked ox-LDL-induced expression of CHOP and Bcl-2 and activation of caspase-12 activity, leading to an attenuation of endothelial cell apoptosis. Furthermore, Nox-4 siRNA attenuated the up-regulated expression of GRP78, PERK, IRE1, and XBP-1 to reduce ox-LDL-induced endothelial cell apoptosis.

CONCLUSIONS

LOX-1 plays a critical role in ox-LDL-induced endothelial cell apoptosis via the ER stress pathway.

Endothelium and its alterations in cardiovascular diseases: life style intervention

The endothelium, which forms the inner cellular lining of blood vessels and lymphatics, is a highly metabolically active organ that is involved in many physiopathological processes, including the control of vasomotor tone, barrier function, leukocyte adhesion, and trafficking and inflammation. In this review, we summarized and described the following: (i) endothelial cell function in physiological conditions and (ii) endothelial cell activation and dysfunction in the main cardiovascular diseases (such as atherosclerosis, and hypertension) and to diabetes, cigarette smoking, and aging physiological process. Finally, we presented the currently available evidence that supports the beneficial effects of physical activity and various dietary compounds on endothelial functions.

Chlamydia pneumoniae induces expression of pro-atherogenic factors through activation of the lectin-like oxidized LDL receptor-1

Several lines of evidence have associated Chlamydia pneumoniae with cardiovascular disease including acceleration of atherosclerotic lesion progression in hyperlipidemic animal models by infection. Many of the pro-atherogenic effects of oxidized low-density lipoprotein (ox-LDL) occur through the activation of the lectin-like ox-LDL receptor-1 (LOX-1). Chlamydia pneumoniae upregulates the expression of the LOX-1 mRNA, promotes the uptake of ox-LDL, and utilizes the LOX-1 receptor for infectivity. The overall goal of this study was to determine whether C. pneumoniae organisms upregulated LOX-1 protein expression in vascular cells and whether upregulation of pro-atherogenic factors by C. pneumoniae occurred through LOX-1. Chlamydia pneumoniae induced LOX-1 protein expression in both endothelial cells and RAW macrophages. Upregulation was prevented by preincubation of cells with LOX-1 antibody prior to infection. Similarly, C. pneumoniae upregulated protein expression of adhesion molecules, MMP-1, and MMP-3, which was mitigated by anti-LOX-1 antibody. Prior treatment of organisms with PNGase, which removes the chlamydial glycan that is N-linked to the major outer membrane, abolished C. pneumoniae upregulation of LOX-1. These studies suggest that activation of LOX-1 expression occurs through binding of the chlamydial glycan and provides one mechanism by which C. pneumoniae infection could play a role in the pathogenesis of atherosclerosis.

LOX-1, a new marker of risk and prognosis in coronary artery disease?

The development of atherosclerosis is caused by the accumulation of lipid, inflammatory cytokine production, and the large amount of inflammatory cells in the arterial wall. It is now established that the presence of oxidized low-density lipoproteins (ox-LDL) has an important role in the pathogenesis of the disease. There are many scavenger receptors for ox-LDL, among which LOX-1 seems to be important for the induction of endothelial dysfunction and the other subsequent events that lead to the formation of atheromatous plaque. Our findings indicate the presence of a regulatory role induced by the presence of ox-LDL on LOX-1 through the amplification of IL-6 synthesis. This mechanism contributes to the upregulation of the ORL-1 gene expression in presence of risk factors. Many authors have shown the possibility to use LOX-1 as a good marker for the diagnosis and prognosis of coronary artery disease because it is easy to measure and more sensitive than other markers commonly used in the routine of laboratory medicine.

Severity dependent up-regulations of LOX-1 and MCP-1 in early sclerotic changes of common carotid arteries in spontaneously hypertensive rats

Lectin-like oxidized low-density lipoprotein receptor (LOX-1) and monocyte chemoattractant protein-1 (MCP-1) are molecules involving in the initiation and progression of atherosclerosis. In order to examine a possible difference in LOX-1 and MCP-1 expressions depending on the severity of early stage of atherosclerosis, we investigated atherosclerotic changes by exposure to hypertension and hyperlipidemia in common carotid arteries (CCAs) of stroke-prone spontaneously hypertensive rat (SHR-SP). Three rat model groups such as control [Wistar Kyoto rat (WKY) group], hypertension (SHR-SP group) and hypertension + hyperlipidemia [SHR-SP + high fat and cholesterol (HFC) group] were used. Body weights, brain weights, systolic blood pressures and serum levels of total cholesterol, low-density lipoprotein and triglyceride were measured at 0, 5, 10 and 15 days after appropriate diet. Immunohistochemistry showed that the positive area and the strength of LOX-1 and MCP-1 were larger in the SHR-SP + HFC group than in the SHR-SP group, while no immunoreactivities were found in the WKY group. Conventional RT-PCR and real-time PCR analyses showed that mRNAs of those in the SHR-SP group were higher with greater up-regulation in the SHR-SP + HFC group. LOX-1 and MCP-1 expressions were coordinately up-regulated at mRNA and protein levels in an early stage of sclerosis depending on the severity of atherosclerotic stress. Activations of LOX-1 and MCP-1 are collectively involved in the early stage of atherosclerosis.

The changing face of vascular interventional radiology: the future role of pharmacotherapies and molecular imaging

Interventional radiology has had to evolve constantly because there is the ever-present competition and threat from other specialties within medicine, surgery, and research. The development of new technologies, techniques, and therapies is vital to broaden the horizon of interventional radiology and to ensure its continued success in the future. In part, this change will be due to improved chronic disease prevention altering what we treat and in whom. The most important of these strategies are the therapeutic use of statins, Beta-blockers, angiotensin-converting enzyme inhibitors, and substances that interfere with mast cell degeneration. Molecular imaging and therapeutic strategies will move away from conventional techniques and nano and microparticle molecular technology, tissue factor imaging, gene therapy, endothelial progenitor cells, and photodynamic therapy will become an important part of interventional radiology of the future. This review looks at these new and exciting technologies.

Milk-derived peptides, Val-Pro-Pro and Ile-Pro-Pro, attenuate atherosclerosis development in apolipoprotein e-deficient mice: a preliminary study

Milk-derived peptides, Val-Pro-Pro (VPP) and Ile-Pro-Pro (IPP), have angiotensin I-converting enzyme inhibitory activities and blood pressure-lowering effects. We examined the effects of these peptides on the development of atherosclerosis in apolipoprotein E-deficient [apoE(-/-)] mice. For 31 weeks, six-week-old male apoE(-/-) mice received a diet that included one of the following: fermented milk containing both VPP and IPP; casein hydrolysate containing both of these peptides; synthesized VPP; synthesized IPP; enalapril; captopril; or control diet. At the end of feeding, blood biochemistry, aortic atherogenesis, and gene expression by DNA microarray analysis were evaluated. There were no significant changes in the plasma lipid levels and 8-isoprostane, a marker of oxidative stress. The area ratio of intima to media in the aortic arch was significantly lower in the fermented milk, casein hydrolysate, synthesized VPP, enalapril, and captopril groups than in the control group. As is common with diets containing VPP and/or IPP, we observed reductions in mRNA expression of inflammatory cytokines, such as interleukin (IL)-6 and IL-1β, oxidized low-density lipoprotein receptor, and transcription regulators. These results suggest that a continuous intake of VPP and IPP might be beneficial for preventing atherosclerosis caused by hypercholesterolemia.