apelin-13-peptide and apelin-12-peptide

Patients with moyamoya disease (MMD) or intracranial atherosclerotic disease (ICAD) experience similar cerebral ischaemic events. However, MMD patients show greater angiogenesis and arteriogenesis, which play crucial roles in collateral circulation development to enhance clinical prognosis and outcome. Apelins have been associated with angiogenesis and arteriogenesis. Therefore, the aim of the present study was to determine whether apelin levels were higher in patients with MMD than in patients with ICAD or in healthy controls. We compared plasma apelin levels in 29 patients with MMD, 82 patients with ICAD, and 25 healthy participants. Twelve-hour fasting blood samples were collected and analysed using commercially available kits. Univariate analyses indicated that compared with the ICAD and healthy control groups, the MMD group had higher apelin-12, apelin-13, apelin-36, and nitric oxide levels. Binary logistic regression analyses further showed that the plasma apelin-12 level was substantially higher in MMD patients than in ICAD patients. Patients with MMD were also differentiated from patients with ICAD by their mean ages, with the former being younger. Therefore, the plasma apelin-12 level is a potential diagnostic marker for differentiating MMD and ICAD and may provide a treatment strategy for enhancing collateral circulation development and clinical prognosis and outcome.

Topics: Adult; Age Factors; Aged; Apelin; Biomarkers; Case-Control Studies; Cerebrovascular Circulation; Diagnosis, Differential; Fasting; Female; Humans; Intercellular Signaling Peptides and Proteins; Intracranial Arteriosclerosis; Logistic Models; Male; Middle Aged; Moyamoya Disease; Neovascularization, Physiologic; Nitric Oxide; Prognosis

Adipocytes are cells able to produce and secrete several active substances (adipokines) with direct effects on vascular cells. Apelin, one of the most recently identified adipokines has been studied in cardiovascular system physiology in regard to vessel vasodilation and myocardial contraction, but it has not yet completely characterised for its pathophysiological role in cardiovascular disease and especially in acute coronary syndromes (ACS). Several studies have indicated that tissue factor (TF) plays a pivotal role in the pathophysiology of ACS by triggering the formation of intracoronary thrombi following endothelial injury. This study investigates the effects of apelin 12 and apelin 13 on TF in human umbilical endothelial cells (HUVECs) and monocytes. Cells were stimulated with increasing concentrations of apelin 12 or apelin 13 and then processed to evaluate TF-mRNA levels by real-time PCR as well as TF expression/activity by FACS analysis and pro-coagulant activity. Finally, a potential molecular pathway involved in modulating this phenomenon was investigated. We demonstrate that apelin 13 but not apelin 12 induces transcription of mRNA for TF. In addition, we show that this adipokine promotes surface expression of TF that is functionally active. Apelin 13 effects on TF appear modulated by the activation of the G-protein-transcription factor nuclear factor (NF)-κB axis since G-protein inhibitors suppressed NF-κB mediated TF expression. Data of the present study, although in vitro, indicate that apelin-13, induces a procoagulant phenotype in HUVECs and monocytes by promoting TF expression. These observations support the hypothesis that this adipokine might play a relevant role as an active partaker in athero-thrombotic disease.

Topics: Adipokines; Cell Separation; Coronary Thrombosis; Endothelial Cells; Endothelium, Vascular; Flow Cytometry; Gene Expression Regulation; GTP-Binding Proteins; Human Umbilical Vein Endothelial Cells; Humans; Intercellular Signaling Peptides and Proteins; Monocytes; NF-kappa B; Protein Isoforms; Real-Time Polymerase Chain Reaction; RNA, Messenger; Signal Transduction; Thromboplastin

Mitochondria-derived oxidative stress is believed to be crucially involved in cardiac ischaemia reperfusion (I/R) injury, although currently no therapies exist that specifically target mitochondrial reactive oxygen species (ROS) production. The present study was designed to evaluate the potential effects of the structural analogues of apelin-12, an adipocyte-derived peptide, on mitochondrial ROS generation, cardiomyocyte apoptosis, and metabolic and functional recovery to myocardial I/R injury.. In cultured H9C2 cardiomyoblasts and adult cardiomyocytes, oxidative stress was induced by hypoxia reoxygenation. Isolated rat hearts were subjected to 35 min of global ischaemia and 30 min of reperfusion. Apelin-12, apelin-13 and structural apelin-12 analogues, AI and AII, were infused during 5 min prior to ischaemia.. In cardiac cells, mitochondrial ROS production was inhibited by the structural analogues of apelin, AI and AII, in comparison with the natural peptides, apelin-12 and apelin-13. Treatment of cardiomyocytes with AI and AII decreased cell apoptosis concentration-dependently. In a rat model of I/R injury, pre-ischaemic infusion of AI and AII markedly reduced ROS formation in the myocardial effluent and attenuated cell membrane damage. Prevention of oxidative damage by AI and AII was associated with the improvement of functional and metabolic recovery after I/R in the heart.. These data provide the evidence for the potential of the structural apelin analogues in selective reduction of mitochondrial ROS generation and myocardial apoptosis and form the basis for a promising therapeutic strategy in the treatment of oxidative stress-related heart disease.

Topics: Animals; Apoptosis; Cell Membrane; Dose-Response Relationship, Drug; Intercellular Signaling Peptides and Proteins; Male; Mitochondria; Myocardial Reperfusion Injury; Myocytes, Cardiac; Oxidative Stress; Rats; Rats, Wistar; Reactive Oxygen Species

Although the apelin/APJ system is abundantly expressed in vascular endothelial cells (EC), it has not yet been considered to be regulated by fluid flow. The aim of this study was to explore the influence of shear stress on the expression of apelin/APJ in human EC. Therefore, gene and protein expression were assessed after flow exposure; cell supernatants were collected for measurements of NO and apelin; APJ or apelin knockdown were performed using siRNA. Our data show that gene and protein expression of apelin and APJ are modulated by fluid flow depending on the magnitude of shear stress. Moreover, apelin-12 activated NO production via PI3K/Akt signaling in human EC. In contrast, apelin-13 additionally activated Erk1/2 phosphorylation and enhanced EC proliferation. Knockdown of APJ inhibited phosphorylation of PI3K and impaired flow-induced eNOS and PECAM-1 expression. Knockdown of apelin had no influence on flow-induced APJ and PECAM-1 expression, but derogated eNOS expression under static and flow conditions. The present study reveals a flow-mediated adjustment of the apelin/APJ system in human EC in which APJ expression is induced by shear stress independently of its ligand. Furthermore, apelin-12 signaling is an essential regulatory element in endothelial NO synthesis.

Topics: Apelin Receptors; Cell Line; Enzyme-Linked Immunosorbent Assay; Human Umbilical Vein Endothelial Cells; Humans; Intercellular Signaling Peptides and Proteins; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Muscle, Smooth, Vascular; NG-Nitroarginine Methyl Ester; Nitric Oxide; Nitric Oxide Synthase Type III; Phosphatidylinositol 3-Kinases; Phosphorylation; Platelet Endothelial Cell Adhesion Molecule-1; Proto-Oncogene Proteins c-akt; Receptors, G-Protein-Coupled; Shear Strength; Signal Transduction

The apelin peptide is the endogenous ligand for the apelin G protein-coupled receptor. The distribution of the apelin peptides and receptor are widespread in the central nervous system and periphery, with reported roles in the hypothalamic-pituitary-adrenal axis, blood pressure regulation and as one of the most potent positive inotropic substances yet identified. In this report, we show that in native tissues preproapelin exists as a dimer. Dimeric preproapelin was reduced to monomers by dithiothreitol treatment, indicating disulfide linkages. To evaluate the role of the carboxyl-terminal phenylalanine in the hypotensive action of apelin-13, analogs were generated and tested for their role on blood pressure regulation. Injections of apelin-13 and apelin-12 (15 microg/kg) into spontaneously hypertensive rats lowered systolic and diastolic blood pressure to result in decreases of approximately 60% and 15% in mean arterial blood pressure, respectively. Apelin-13(13[D-Phe]) treatment did not differ from apelin-13 in either efficacy or duration of effect, whereas apelin-13(F13A) revealed a loss of function. However, concomitant administration of apelin-13(F13A) (30 microg/kg) blocked hypotensive effects of apelin-13 (15 microg/kg), which revealed that apelin-13(F13A) behaved as an apelin-specific antagonist.

Topics: Adipokines; Amino Acid Sequence; Animals; Apelin; Blood Pressure; Carrier Proteins; Cells, Cultured; Chlorocebus aethiops; COS Cells; Dimerization; Dithiothreitol; Intercellular Signaling Peptides and Proteins; Mice; Mice, Transgenic; Phenylalanine; Rats; Rats, Inbred SHR; Rats, Wistar