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.

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Vasostatin-1, a chromogranin A (CgA)-derived peptide (76 amino acids), is known to suppress vasoconstriction and angiogenesis. A recent study has shown that vasostatin-1 suppresses the adhesion of human U937 monocytes to human endothelial cells (HECs) via adhesion molecule down-regulation. The present study evaluated the expression of vasostatin-1 in human atherosclerotic lesions and its effects on inflammatory responses in HECs and human THP-1 monocyte-derived macrophages, macrophage foam cell formation, migration and proliferation of human aortic smooth muscle cells (HASMCs) and extracellular matrix (ECM) production by HASMCs, and atherogenesis in apolipoprotein E-deficient (ApoE−/−) mice. Vasostatin-1 was expressed around Monckeberg’s medial calcific sclerosis in human radial arteries. Vasostatin-1 suppressed lipopolysaccharide (LPS)-induced up-regulation of monocyte chemotactic protein-1 (MCP-1), vascular cell adhesion molecule-1 (VCAM-1), and E-selectin in HECs. Vasostatin-1 suppressed inflammatory M1 phenotype and LPS-induced interleukin-6 (IL-6) secretion via nuclear factor-κB (NF-κB) down-regulation in macrophages. Vasostatin-1 suppressed oxidized low-density lipoprotein (oxLDL)-induced foam cell formation associated with acyl-CoA:cholesterol acyltransferase-1 (ACAT-1) and CD36 down-regulation and ATP-binding cassette transporter A1 (ABCA1) up-regulation in macrophages. In HASMCs, vasostatin-1 suppressed angiotensin II (AngII)-induced migration and collagen-3 and fibronectin expression via decreasing ERK1/2 and p38 phosphorylation, but increased elastin expression and matrix metalloproteinase (MMP)-2 and MMP-9 activities via increasing Akt and JNK phosphorylation. Vasostatin-1 did not affect the proliferation and apoptosis in HASMCs. Four-week infusion of vasostatin-1 suppressed the development of aortic atherosclerotic lesions with reductions in intra-plaque inflammation, macrophage infiltration, and SMC content, and plasma glucose level in ApoE−/− mice. These results indicate the inhibitory effects of vasostatin-1 against atherogenesis. The present study provided the first evidence that vasostatin-1 may serve as a novel therapeutic target for atherosclerosis.

Oxaliplatin, a chemotherapy medication, causes severe peripheral neuropathy. Although oxaliplatin-induced peripheral neuropathy is a dose-limiting toxicity, a therapeutic strategy against its effects has not been established. We previously reported the involvement of N-methyl-D-aspartate receptors and their intracellular signalling pathway in oxaliplatin-induced mechanical allodynia in rats. The aim of this study was to clarify the involvement of spinal glutamate transmission in oxaliplatin-induced mechanical allodynia. In vivo spinal microdialysis revealed that the baseline glutamate concentration was elevated in oxaliplatin-treated rats, and that mechanical stimulation of the hind paw markedly increased extracellular glutamate concentration in the same rats. In these rats, the expression of glutamate transporter 1 (GLT-1), which plays a major role in glutamate uptake, was decreased in the spinal cord. Moreover, we explored the potential of pharmacological therapy targeting maintenance of extracellular glutamate homeostasis. The administration of riluzole, an approved drug for amyotrophic lateral sclerosis, suppressed the increase of glutamate concentration, the decrease of GLT-1 expression and the development of mechanical allodynia. These results suggest that oxaliplatin disrupts the extracellular glutamate homeostasis in the spinal cord, which may result in neuropathic symptoms, and support the use of riluzole for prophylaxis of oxaliplatin-induced mechanical allodynia.

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BackgroundOxaliplatin has widely been used as a key drug in the treatment of colorectal cancer; however, it causes peripheral neuropathy. Exenatide, a glucagon-like peptide-1 (GLP-1) agonist, is an incretin mimetic secreted from ileal L cells, which is clinically used to treat type 2 diabetes mellitus. GLP-1 receptor agonists have been reported to exhibit neuroprotective effects on the central and peripheral nervous systems. In this study, we investigated the effects of exenatide on oxaliplatin-induced neuropathy in rats and cultured cells.MethodsOxaliplatin (4 mg/kg) was administered intravenously twice per week for 4 weeks, and mechanical allodynia was evaluated using the von Frey test in rats. Axonal degeneration was assessed by toluidine blue staining of sciatic nerves.ResultsRepeated administration of oxaliplatin caused mechanical allodynia from day 14 to 49. Although the co-administration of extended-release exenatide (100 μg/kg) could not inhibit the incidence of oxaliplatin-induced mechanical allodynia, it facilitated recovery from the oxaliplatin-induced neuropathy with reparation of axonal degeneration. Inhibition of neurite outgrowth was evaluated in cultured pheochromocytoma 12 (PC12) cells. Exenatide inhibited oxaliplatin-induced neurite degeneration, but did not affect oxaliplatin-induced cell injury in cultured PC12 cells. Additionally, extended-release exenatide had no effect on the anti-tumor activity of oxaliplatin in cultured murine colon adenocarcinoma 26 (C-26) cells or C-26 cell-implanted mice.ConclusionThese results suggest that exenatide may be useful for treating peripheral neuropathy induced by oxaliplatin in colorectal cancer patients with type 2 diabetes.

Legumain, a recently discovered cysteine protease, is increased in both carotid plaques and plasma of patients with carotid atherosclerosis. Legumain increases the migration of human monocytes and human umbilical vein endothelial cells (HUVECs). However, the causal relationship between legumain and atherosclerosis formation is not clear. We assessed the expression of legumain in aortic atheromatous plaques and after wire-injury-induced femoral artery neointimal thickening and investigated the effect of chronic legumain infusion on atherogenesis in Apoe−/− mice. We also investigated the associated cellular and molecular mechanisms in vitro, by assessing the effects of legumain on inflammatory responses in HUVECs and THP-1 monocyte-derived macrophages; macrophage foam cell formation; and migration, proliferation, and extracellular matrix protein expression in human aortic smooth muscle cells (HASMCs). Legumain was expressed at high levels in atheromatous plaques and wire injury-induced neointimal lesions in Apoe−/− mice. Legumain was also expressed abundantly in THP-1 monocytes, THP-1 monocyte-derived macrophages, HASMCs, and HUVECs. Legumain suppressed lipopolysaccharide-induced mRNA expression of vascular cell adhesion molecule-1 (VCAM1), but potentiated the expression of interleukin-6 (IL6) and E-selectin (SELE) in HUVECs. Legumain enhanced the inflammatory M1 phenotype and oxidized low-density lipoprotein-induced foam cell formation in macrophages. Legumain did not alter the proliferation or apoptosis of HASMCs, but it increased their migration. Moreover, legumain increased the expression of collagen-3, fibronectin, and elastin, but not collagen-1, in HASMCs. Chronic infusion of legumain into Apoe−/− mice potentiated the development of atherosclerotic lesions, accompanied by vascular remodeling, an increase in the number of macrophages and ASMCs, and increased collagen-3 expression in plaques. Our study provides the first evidence that legumain contributes to the induction of atherosclerotic vascular remodeling.

Tumor necrosis factor-stimulated gene-6 (TSG-6) is a 35-kDa glycoprotein that has been shown to exert anti-inflammatory effects in experimental models of arthritis, acute myocardial infarction, and acute cerebral infarction. Several lines of evidence have shed light on the pathophysiological roles of TSG-6 in atherosclerosis. TSG-6 suppresses inflammatory responses of endothelial cells, neutrophils, and macrophages as well as macrophage foam cell formation and vascular smooth muscle cell (VSMC) migration and proliferation. Exogenous TSG-6 infusion and endogenous TSG-6 attenuation with a neutralizing antibody for four weeks retards and accelerates, respectively, the development of aortic atherosclerotic lesions in ApoE-deficient mice. TSG-6 also decreases the macrophage/VSMC ratio (a marker of plaque instability) and promotes collagen fibers in atheromatous plaques. In patients with coronary artery disease (CAD), plasma TSG-6 levels are increased and TSG-6 is abundantly expressed in the fibrous cap within coronary atheromatous plaques, indicating that TSG-6 increases to counteract the progression of atherosclerosis and stabilize the plaque. These findings indicate that endogenous TSG-6 enhancement and exogenous TSG-6 replacement treatments are expected to emerge as new lines of therapy against atherosclerosis and related CAD. Therefore, this review provides support for the clinical utility of TSG-6 in the diagnosis and treatment of atherosclerotic cardiovascular diseases.