Rena Watanabe

Counteractive effects of omentin-1 against atherogenesis

AIMS Omentin-1, a novel adipocytokine expressed in visceral fat tissue, is negatively correlated with obesity, insulin resistance, and stable coronary artery disease (CAD). However, there have been no previous reports regarding the effects of omentin-1 on atherogenesis. METHODS AND RESULTS This study was performed to evaluate the atheroprotective effects of omentin-1 on human monocyte-derived macrophages, human aortic smooth muscle cells (HASMCs) in vitro, and aortic lesions in Apoe(-/-) mice in vivo. The histological expression of omentin-1 in coronary artery lesions and epicardial adipose tissues and its plasma levels were compared between CAD and non-CAD patients. Omentin-1 was abundantly expressed in human umbilical vein endothelial cells, macrophages, HASMCs, and human coronary artery SMCs in vitro. Omentin-1 promoted anti-inflammatory M2 phenotype during differentiation of human monocytes into macrophages. Omentin-1 suppressed oxidized low-density lipoprotein-induced foam cell formation associated with down-regulation of CD36, scavenger receptor class A, and acyl-CoA:cholesterol acyltransferase-1 and up-regulation of neutral cholesterol ester hydrolase in human macrophages. Omentin-1 suppressed angiotensin II-induced migration and platelet-derived growth factor-BB-induced proliferation, and collagen-1 and -3 expression in HASMCs. Four-week infusion of omentin-1 into Apoe(-/-) mice retarded the development of aortic atherosclerotic lesions with reduced contents of monocytes/macrophages, SMCs, and collagen fibres along with peritoneal M2-activated macrophages with inflammasome down-regulation and lowered plasma total cholesterol levels. Omentin-1 levels were markedly reduced in coronary endothelium and epicardial fat but increased in plasma and atheromatous plaques (macrophages/SMCs) in CAD patients compared with non-CAD patients. CONCLUSION This study provided the first evidence that omentin-1 may serve as a novel therapeutic target for atherosclerosis and CAD.

Salusins: Potential Use as a Biomarker for Atherosclerotic Cardiovascular Diseases

Human salusin-α and salusin-β are related peptides produced from prosalusin. Bolus injection of salusin-β into rats induces more profound hypotension and bradycardia than salusin-α. Central administration of salusin-β increases blood pressure via release of norepinephrine and arginine-vasopressin. Circulating levels of salusin-α and salusin-β are lower in patients with essential hypertension. Salusin-β exerts more potent mitogenic effects on human vascular smooth muscle cells (VSMCs) and fibroblasts than salusin-α. Salusin-β accelerates inflammatory responses in human endothelial cells and monocyte-endothelial adhesion. Human macrophage foam cell formation is stimulated by salusin-β but suppressed by salusin-α. Chronic salusin-β infusion into apolipoprotein E-deficient mice enhances atherosclerotic lesions; salusin-α infusion reduces lesions. Salusin-β is expressed in proliferative neointimal lesions of porcine coronary arteries after stenting. Salusin-α and salusin-β immunoreactivity have been detected in human coronary atherosclerotic plaques, with dominance of salusin-β in macrophage foam cells, VSMCs, and fibroblasts. Circulating salusin-β levels increase and salusin-α levels decrease in patients with coronary artery disease. These findings suggest that salusin-β and salusin-α may contribute to proatherogenesis and antiatherogenesis, respectively. Increased salusin-β and/or decreased salusin-α levels in circulating blood and vascular tissue are closely linked with atherosclerosis. Salusin-α and salusin-β could be candidate biomarkers and therapeutic targets for atherosclerotic cardiovascular diseases.

Stimulatory Effects of Cardiotrophin 1 on Atherosclerosis

Cardiotrophin 1 (CT-1), an interleukin-6 family cytokine, was recently shown to be expressed in the intima of early atherosclerotic lesions in the human carotid artery. CT-1 stimulates proatherogenic molecule expression in human vascular endothelial cells and monocyte migration. However, it has not been reported whether CT-1 accelerates atherosclerosis. This study was performed to examine the stimulatory effects of CT-1 on human macrophage foam cell formation and vascular smooth muscle cell migration and proliferation in vitro, and on the development of atherosclerotic lesions in apolipoprotein E–deficient (ApoE−/−) mice in vivo. CT-1 was expressed at high levels in endothelial cells and macrophages in both humans and ApoE−/− mice. CT-1 significantly enhanced oxidized low-density lipoprotein–induced foam cell formation associated with increased levels of CD36 and acyl-CoA:cholesterol acyltransferase-1 expression in human monocyte–derived macrophages. CT-1 significantly stimulated the migration, proliferation, and collagen-1 expression in human aortic vascular smooth muscle cells. Four-week infusion of CT-1 into ApoE−/− mice significantly accelerated the development of aortic atherosclerotic lesions with increased monocyte/macrophage infiltration, vascular smooth muscle cell proliferation, and collagen-1 content in the aortic wall. Activation of inflammasome, such as apoptosis-associated speck-like protein containing a caspase recruitment domain, nuclear factor &kgr;B, and cyclooxygenase-2, was observed in exudate peritoneal macrophages from ApoE−/− mice infused with CT-1. Infusion of anti–CT-1–neutralizing antibody alone into ApoE−/− mice significantly suppressed monocyte/macrophage infiltration in atherosclerotic lesions. These results indicate that CT-1 accelerates the development of atherosclerotic lesions by stimulating the inflammasome, foam cell formation associated with CD36 and acyl-CoA:cholesterol acyltransferase-1 upregulation in macrophages, and migration, proliferation, and collagen-1 production in vascular smooth muscle cells.

Vasoprotective Effects of Urocortin 1 against Atherosclerosis In Vitro and In Vivo

Aim Atherosclerosis is the complex lesion that consists of endothelial inflammation, macrophage foam cell formation, vascular smooth muscle cell (VSMC) migration and proliferation, and extracellular matrix production. Human urocortin 1 (Ucn1), a 40-amino acid peptide member of the corticotrophin-releasing factor/urotensin I family, has potent cardiovascular protective effects. This peptide induces potent and long-lasting hypotension and coronary vasodilation. However, the relationship of Ucn1 with atherosclerosis remains unclear. The present study was performed to clarify the effects of Ucn1 on atherosclerosis. Methods We assessed the effects of Ucn1 on the inflammatory response and proliferation of human endothelial cells (ECs), human macrophage foam cell formation, migration and proliferation of human VSMCs, extracellular matrix expression in VSMCs, and the development of atherosclerosis in apolipoprotein E-deficient (Apoe −/−) mice. Results Ucn1 significantly suppressed cell proliferation without inducing apoptosis, and lipopolysaccharide-induced up-regulation of monocyte chemoattractant protein-1 and intercellular adhesion molecule-1 in human ECs. Ucn1 significantly reduced oxidized low-density lipoprotein-induced foam cell formation with a significant down-regulation of CD36 and acyl-CoA:cholesterol acyltransferase 1 in human monocyte-derived macrophages. Ucn1 significantly suppressed the migration and proliferation of human VSMCs and increased the activities of matrix metalloproteinase-2 (MMP2) and MMP9 in human VSMCs. Intraperitoneal injection of Ucn1 into Apoe −/− mice for 4 weeks significantly retarded the development of aortic atherosclerotic lesions. Conclusions This study provided the first evidence that Ucn1 prevents the development of atherosclerosis by suppressing EC inflammatory response and proliferation, macrophage foam cell formation, and VSMC migration and proliferation. Thus, Ucn1 could serve as a novel therapeutic target for atherosclerotic cardiovascular diseases.

Facilitatory effects of fetuin-A on atherosclerosis.

OBJECTIVE Fetuin-A is a circulating glycoprotein that is produced by liver and adipose tissue. Fetuin-A is known to induce insulin resistance and suppress vascular calcification. There are conflicting reports that show increased or decreased serum fetuin-A levels in patients with coronary artery disease (CAD). Since the role of fetuin-A in atherosclerosis remains still controversial, we aimed to clarify it in this study. METHODS We investigated the expression of fetuin-A in atheromatous plaques in CAD patients and restenosis lesions in balloon-injured rat carotid arteries in vivo. We also assessed in vitro effects of fetuin-A on inflammatory molecules in human umbilical vein endothelial cells (HUVECs), oxidized low-density lipoprotein-induced foam cell formation in human monocyte-derived macrophages, and the migration, proliferation, and extracellular matrix expression in human aortic smooth muscle cells (HASMCs) in a serum-free culture system. RESULTS Fetuin-A was abundantly expressed in cultured human monocytes, macrophages, fibroblasts, HASMCs, and human coronary artery SMCs, atheromatous plaques in human coronary arteries, and restenosis lesions in rat carotid arteries. In vitro experiments showed that fetuin-A stimulated interleukin-6, monocyte chemotactic protein-1, intercellular adhesion molecule-1, and E-selectin expression in HUVECs. Fetuin-A enhanced macrophage foam cell formation associated with scavenger receptors (CD36 and SR-A) and acyl-CoA:cholesterol acyltransferase-1 up-regulation and ATP-binding cassette transporter A1 down-regulation, and increased cell proliferation and collagen-1 and -3 expression via PI3K/AKT/c-Src/NF-κB/ERK1/2 pathways in HASMCs. CONCLUSION Our results indicate that fetuin-A exerts the stimulatory effects on inflammatory responses in HUVECs, macrophage foam cell formation, and proliferation and collagen production in HASMCs, leading to the development of atherosclerosis.

Atheroprotective Effects of Tumor Necrosis Factor–Stimulated Gene-6

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Catestatin Prevents Macrophage-Driven Atherosclerosis but Not Arterial Injury–Induced Neointimal Hyperplasia

Catestatin, a catecholamine-release inhibitory peptide, has multiple cardiovascular activities. Conflicting results have been recently reported by increased or decreased plasma levels of catestatin in patients with coronary artery disease (CAD). However, there have been no previous reports regarding the effects of catestatin on arteriosclerosis. This study evaluated the vasoprotective effects of catestatin on human macrophages, human aortic smooth muscle cells (HASMCs) and human umbilical vein endothelial cells (HUVECs) in vitro, and aortic atherosclerosis and wire injury-induced femoral artery neointimal hyperplasia in apolipoprotein E-deficient (ApoE-/-) mice fed with a high-cholesterol diet. Histological expression of catestatin in coronary artery lesions and its plasma level were compared between CAD and non-CAD patients. Catestatin was abundantly expressed in cultured human monocytes, macrophages, HASMCs and HUVECs. Catestatin significantly suppressed lipopolysaccharide-induced upregulation of tumour necrosis factor-α, vascular cell adhesion molecule-1 and intercellular adhesion molecule-1 in HUVECs. Catestatin significantly suppressed inflammatory responses and oxidized low-density lipoprotein-induced foam cell formation associated with acyl-CoA:cholesterol acyltransferase-1 downregulation and ATP-binding cassette transporter A1 upregulation in human macrophages. Catestatin significantly suppressed migration, proliferation and collagen-1 expression without inducing apoptosis, and increased elastin and fibronectin expression in HASMCs. Administration of catestatin into ApoE-/- mice significantly retarded entire aortic atherosclerotic lesions with declined contents of macrophages, SMCs and collagen fibres in atheromatous plaques, but not the femoral artery injury-induced neointimal hyperplasia. In CAD patients, catestatin levels were significantly decreased in plasma but increased in coronary atheromatous plaques. This study provided the first evidence that catestatin could prevent macrophage-driven atherosclerosis, but not SMC-derived neointimal hyperplasia after vascular injury.

Potent Vasoconstrictor Kisspeptin‐10 Induces Atherosclerotic Plaque Progression and Instability: Reversal by its Receptor GPR54 Antagonist

Background Kisspeptin‐10 (KP‐10), a potent vasoconstrictor and inhibitor of angiogenesis, and its receptor, GPR54, have currently received much attention in relation to pre‐eclampsia. However, it still remains unknown whether KP‐10 could affect atherogenesis. Methods and Results We evaluated the effects of KP‐10 on human umbilical vein endothelial cells, human monocyte‐derived macrophages, human aortic smooth muscle cells in vitro, and atherosclerotic lesions in apolipoprotein E–deficient (ApoE−/−) mice in vivo. KP‐10 significantly increased the adhesion of human monocytes to human umbilical vein endothelial cells, which was significantly inhibited by pretreatment with P234, a GPR54 antagonist. KP‐10 stimulated mRNA expression of tumor necrosis factor‐α, interleukin‐6, monocyte chemotactic protein‐1, intercellular adhesion molecule‐1, vascular adhesion molecule‐1, and E‐selectin in human umbilical vein endothelial cells. KP‐10 significantly enhanced oxidized low‐density lipoprotein–induced foam cell formation associated with upregulation of CD36 and acyl‐CoA:cholesterol acyltransferase‐1 in human monocyte‐derived macrophages. In human aortic smooth muscle cells, KP‐10 significantly suppressed angiotensin II–induced migration and proliferation, but enhanced apoptosis and activities of matrix metalloproteinase (MMP)‐2 and MMP‐9 by upregulation of extracellular signal‐regulated kinase 1 and 2, p38, Bcl‐2‐associated X protein, and caspase‐3. Four‐week‐infusion of KP‐10 into ApoE−/− mice significantly accelerated the development of aortic atherosclerotic lesions with increased monocyte/macrophage infiltration and vascular inflammation as well as decreased intraplaque vascular smooth muscle cells contents. Proatherosclerotic effects of endogenous and exogenous KP‐10 were completely canceled by P234 infusion in ApoE−/− mice. Conclusions Our results suggest that KP‐10 may contribute to accelerate the progression and instability of atheromatous plaques, leading to plaque rupture. The GPR54 antagonist may be useful for prevention and treatment of atherosclerosis. Thus, the KP‐10/GPR54 system may serve as a novel therapeutic target for atherosclerotic diseases.

Contrasting effects of stanniocalcin-related polypeptides on macrophage foam cell formation and vascular smooth muscle cell migration

Stanniocalcin (STC) is a calcium- and phosphate-regulating hormone secreted by the corpuscles of Stannius, an endocrine gland of bony fish. Its human homologues, STC1 and STC2 showing 34% amino acid identity each other, are expressed in a variety of human tissues. To clarify their roles in atherosclerosis, we investigated the effects of their full-length proteins, STC1(18-247) and STC2(25-302), and STC2-derived fragment peptides, STC2(80-100) and STC2(85-99), on inflammatory responses in human umbilical vein endothelial cells (HUVECs), human macrophage foam cell formation, the migration and proliferation of human aortic smooth muscle cells (HASMCs) and the extracellular matrix expression. All these polypeptides suppressed lipopolysaccharide-induced expressions of interleukin-6, monocyte chemotactic protein-1, and intercellular adhesion molecule-1 in HUVECs. Oxidized low-density lipoprotein-induced foam cell formation was significantly decreased by STC1(18-247) and increased by STC2(80-100) and STC2(85-99), but not STC2(25-302), in human macrophages. Expression of acyl-CoA:cholesterol acyltransferase-1 (ACAT1) was significantly suppressed by STC1(18-247) but stimulated by STC2(80-100) and STC2(85-99). Expression of ATP-binding cassette transporter A1 was significantly stimulated by STC1(18-247). Neither STC1(18-247) nor STC2-derived peptides significantly affected CD36 expression in human macrophages or HASMC proliferation. STC2(80-100) and STC2(85-99) significantly increased HASMC migration, whereas STC1(18-247) significantly suppressed the angiotensin II-induced HASMC migration. Expressions of collagen-1, fibronectin, matrix metalloproteinase-2, and elastin were mostly unchanged with the exception of fibronectin up-regulation by STC2(80-100). Our results demonstrated the contrasting effects of STC1 and STC2-derived peptides on human macrophage foam cell formation associated with ACAT1 expression and on HASMC migration. Thus, STC-related polypeptides could serve as a novel therapeutic target for atherosclerosis.

Adipose Tissue-Derived Omentin-1 Function and Regulation

Omentin-1, also known as intelectin-1, is a recently identified novel adipocytokine of 313 amino acids, which is expressed in visceral (omental and epicardial) fat as well as mesothelial cells, vascular cells, airway goblet cells, small intestine, colon, ovary, and plasma. The level of omentin-1 expression in (pre)adipocytes is decreased by glucose/insulin and stimulated by fibroblast growth factor-21 and dexamethasone. Several lines of experimental evidence have shown that omentin-1 plays crucial roles in the maintenance of body metabolism and insulin sensitivity, and has anti-inflammatory, anti-atherosclerotic, and cardiovascular protective effects via AMP-activated protein kinase/Akt/nuclear factor-κB/mitogen-activated protein kinase (ERK, JNK, and p38) signaling. Clinical studies have indicated the usage of circulating omentin-1 as a biomarker of obesity, metabolic disorders including insulin resistance, diabetes, and metabolic syndrome, and atherosclerotic cardiovascular diseases. It is also possible to use circulating omentin-1 as a biomarker of bone metabolism, inflammatory diseases, cancers, sleep apnea syndrome, preeclampsia, and polycystic ovary syndrome. Decreased omentin-1 levels are generally associated with these diseases. However, omentin-1 increases to counteract the acute phase after onset of these diseases. These findings indicate that omentin-1 may be a negative risk factor for these diseases, and also act as an acute-phase reactant by its anti-inflammatory and atheroprotective effects. Therapeutic strategies to restore omentin-1 levels may be valuable for the prevention or treatment of these diseases. Weight loss, olive oil-rich diet, aerobic training, and treatment with atorvastatin and antidiabetic drugs (metformin, pioglitazone, and exenatide) are effective means of increasing circulating omentin-1 levels. This review provides insights into the potential use of omentin-1 as a biomarker and therapeutic target for these diseases.