Yukihiro Hojo

Expression of Vascular Endothelial Growth Factor in Patients With Acute Myocardial Infarction

OBJECTIVE The purpose of this study was to investigate the clinical significance of vascular endothelial growth factor (VEGF) in acute myocardial infarction (AMI). We also examined the involvement of peripheral blood mononuclear cells (PBMCs), which are a possible source of VEGF in AMI. BACKGROUND VEGF is a potent endothelial cell-specific mitogen and could affect the outcome of AMI. METHODS Thirty patients with AMI were used for this study. Serum and PBMCs were isolated from peripheral blood on days 1, 7, 14 and 21 after the onset of AMI. PBMCs were cultured at a density of 5 x 10(6) cells/ml for 24 h. VEGF levels in serum and the culture media were measured by enzyme-linked immunosorbent assay using a specific anti-human VEGF antibody. RESULTS Serum VEGF levels elevated gradually after the onset of AMI and reached a peak on day 14. VEGF levels in the culture medium of PBMCs after incubation for 24 h (PBMC-VEGF) were maximally elevated 7 days after the onset. Maximum serum VEGF levels showed significant positive correlations with maximum creatine phosphokinase (CPK) levels (r = +0.70, p < 0.001), but maximum PBMC-VEGF levels did not correlate with maximum CPK levels. Patients showing improvement in left ventricular systolic function during the course of AMI showed significantly higher PBMC-VEGF levels than patients without improvement. CONCLUSIONS The extent of myocardial damage contributes to the elevation of serum VEGF levels in AMI. VEGF produced by PBMCs may play an important role in the improvement of left ventricular function by promoting angiogenesis and reendothelialization after AMI.

Interleukin 6 expression in coronary circulation after coronary angioplasty as a risk factor for restenosis

OBJECTIVE To investigate changes in cytokine expression in the coronary circulation induced by percutaneous transluminal coronary angioplasty (PTCA). METHODS The study involved 32 patients with ischaemic heart disease who underwent elective PTCA for isolated stenotic lesions of the left coronary artery. Ten patients had plain old balloon angioplasty, 10 had percutaneous transluminal rotational atherectomy, and 12 had stent implantation. Blood samples were drawn from the coronary sinus before and immediately after PTCA. Plasma concentrations of interleukin 6 (IL-6), platelet derived growth factor (PDGF), monocyte chemoattractant protein 1 (MCP-1), and macrophage coronary stimulating factor (M-CSF) were measured. The patients were scheduled for follow up angiography six months after PTCA. Late loss index was calculated using quantitative coronary angiography. RESULTS IL-6 concentrations in coronary sinus blood increased immediately after PTCA (p < 0.001), but there was no change in PDGF, MCP-1, or M-CSF. There was a positive correlation between changes in IL-6 concentrations immediately after PTCA and late loss index six months after PTCA (r = 0.73, p < 0.001). IL-6 concentrations in coronary sinus blood were higher in patients with late restenosis than in those without restenosis (p < 0.001). CONCLUSIONS PTCA induces IL-6 production in the coronary circulation. This may induce subsequent inflammatory responses in injured vessels and play an important role in late restenosis after PTCA.

Procoagulant and proinflammatory activity in acute coronary syndromes

Objectives: Both the hemostatic and inflammatory system are thought to play a role in the pathogenesis of acute coronary syndromes. However, their respective contribution and interrelationship remain unclear, therefore, we studied the relationship between activation of the coagulation system and proinflammatory activity in ischemic coronary syndromes. Methods: Thrombin–antithrombin III (TAT), prothrombin fragments F1+2, fibrinopeptide A (FPA), interleukin-6 (IL-6) and interleukin-8 (IL-8) were measured in 50 patients with unstable angina (UA), 60 patients with acute myocardial infarction (AMI) and in 50 patients with stable angina (SA). Results: FPA levels were significantly higher in patients with UA and AMI than in patients with SA ( p =0.0015 and p <0.0001), and were higher in patients with AMI than UA ( p =0.0013). Plasma IL-6 concentrations were significantly higher in patients with UA and AMI than in patients with SA ( p =0.0020 and p <0.001), and again were higher in AMI than UA ( p =0.001). Interestingly, FPA or IL-6 elevations on admission were found in different patients. In contrast, TAT, F1+2 and IL-8 levels were not different between the three groups. Conclusions: IL-6 and FPA were shown to be independent predictive markers with equal discriminative power to distinguish stable (SA) from unstable (UA+AMI) patients. Moreover, hemostatic and inflammatory markers can be elevated independently in the acute phase of ischemic coronary syndromes.

Increased levels of monocyte-related cytokines in patients with unstable angina

Inflammatory cytokines play important roles in coronary artery disease. We investigated the clinical significance of monocyte-related cytokine expression in patients with angina pectoris. We studied 26 patients with stable effort angina and 20 patients with unstable angina in whom stenotic lesions of the coronary arteries were confirmed by selective coronary angiography. Plasma levels of interleukin-6 (IL-6), macrophage colony stimulating factor (MCSF), and monocyte chemoattractant protein-1 (MCP-1) were measured. Plasma levels of IL-6, MCSF, and MCP-1 in patients with unstable angina were significantly higher than those in patients with stable angina or control subjects. Patients with unstable angina were further divided into sub-groups according to their clinical classification; Levels of IL-6, MCSF, and MCP-1 in patients, who had anginal attacks at rest within the 48 h prior to admission (Braunwald class IIIB) were significantly higher than those in patients, who did not have attacks at rest (class IB). Five unstable patients, who were refractory to medical therapy and were referred for emergency coronary revascularization showed marked elevation of plasma MCSF and MCP-1 levels. In conclusion, plasma levels of monocyte-related cytokines were elevated in unstable angina. These increases were marked in patients with unstable angina with recent ischemic attack at rest, suggesting that activation of monocytes is involved in vulnerability of underlying atheromatous plaque.

Matrix metalloproteinase expression in the coronary circulation induced by coronary angioplasty

Recent studies have revealed that matrix metalloproteinases (MMPs) play an important role in cardiovascular remodeling by degrading the extracellular matrix. We investigated changes in the expression of MMPs due to percutaneous transluminal coronary angioplasty (PTCA). We studied 47 patients with ischemic heart disease who underwent elective PTCA on isolated stenotic lesion of left coronary arteries. Twelve patients received conventional balloon angioplasty, 14 percutaneous transluminal rotational atherectomy and 21 stent implantation. Blood samples were drawn from the coronary sinus immediately before and after, as well as 4 and 24 h, after PTCA. Plasma levels of MMP-1, MMP-2, tissue inhibitor of MMP (TIMP)-1 and TIMP-2 were measured by enzyme-linked immunosorbent assay. Plasma MMP-2 activity was determined with the digestion of a specific chromogenic peptide substrate. We could observe serial changes in plasma MMP-1 levels in the coronary circulation only in one patient, because MMP-1 levels were lower than the limit of detection in other patients. On the other hand, plasma MMP-2 levels in the coronary sinus were detectable in all subjects and increased significantly 4 and 24 h after PTCA. Plasma TIMP-1 levels also showed significant increases 4 and 24 h after PTCA, whereas TIMP-2 did not show significant changes. Plasma MMP-2/TIMP-2 ratio and MMP-2 activity in the coronary sinus showed significant increases 4 and 24 h after PTCA. A positive correlation was observed between MMP-2 levels in the coronary sinus 4 h after PTCA and late loss index 6 months after PTCA. MMP-2 levels in the coronary sinus blood were significantly higher in patients with late restenosis than in those without restenosis. PTCA induces increases in plasma MMP-2 levels and activity in the coronary circulation, which may contribute to vascular remodeling and late restenosis after PTCA.

Interaction between monocytes and vascular smooth muscle cells enhances Matrix metalloproteinase-1 production

Matrix metalloproteinase-1 (MMP-1) plays an important role in atherosclerotic plaque rupture. The purpose of this study was to investigate the expression of MMP-1 by cell-to-cell interactions between monocytes and vascular smooth muscle cells (VSMCs). Human VSMCs and THP-1 cells (human monocytoid cells) were cocultured. MMP-1 levels were measured by enzyme-linked immunosorbent assay. Collagenolytic activity was determined by fluorescent labeled-collagen digestion. Immunohistochemistry was performed to determine which types of cells produce MMP-1. Adding THP-1 cells to VSMCs markedly increased the MMP-1 levels and activity of the culture media. MMP-1 levels were maximal when the cellular ratio of THP-1 cells/VSMCs was 1.0. Immunohistochemistry revealed that both types of cells in the coculture produced MMP-1. Separated coculture experiments showed that both direct contact and a soluble factor(s) contributed to MMP-1 production. Neutralizing anti-interleukin (IL)-6 and tumor necrosis factor-alpha antibodies inhibited coculture conditioned medium-induced MMP-1 production by VSMCs and THP-1 cells. Protein kinase C inhibitors, tyrosine kinase inhibitors, and a mitogen-activated protein kinase inhibitor significantly inhibited MMP-1 production by cocultures. Direct cell-to-cell interaction between THP-1 cells and VSMCs enhanced MMP-1 synthesis in both types of cells. Increased local MMP-1 production and activity induced by monocyte-VSMC interaction play an important pathogenic role in atherosclerotic plaque rupture.

Collagen Metabolism in Extracellular Matrix May Be Involved in Arterial Stiffness in Older Hypertensive Patients with Left Ventricular Hypertrophy

Collagen metabolism in the extracellular matrix (ECM) is related to the pathogenesis of cardiovascular stiffness and remodeling in hypertension. We evaluated the association between collagen metabolism markers and the newly developed parameter, brachial-ankle pulse wave velocity (baPWV), in older hypertensive patients with left ventricular hypertrophy (LVH). We performed echocardiography and baPWV measurement using a new device, form PWV/ABI (Colin Medical Technology, Komaki, Japan), and measured plasma levels of markers of collagen metabolism such as procollagen type I C-terminal propeptide (PICP: a marker of collagen synthesis), collagen type I pyridinoline cross-linked C-terminal telopeptide (ICTP: a marker of collagen type I degradation), matrix metalloproteinase-1 (MMP-1: a marker of collagen degradation) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) in 46 hypertensive patients with LVH. BaPWV was correlated with the plasma level of PICP (r=0.33, p=0.03) and ICTP (r=0.29, p=0.05) and the total TIMP-1/MMP-1 ratio (an index of collagen turnover; r=0.30, p=0.04). BaPWV was negatively correlated with the E/A ratio of left ventricular inflow (r=−0.36, p<0.05), while baPWV was not correlated with left ventricular mass index (LVMI; r=−0.175, p=0.25) or deceleration time of the mitral E wave (DCT; r=0.15, p=0.31). The measures of hypertensive heart disease, such as the E/A ratio, DCT or LVMI were not correlated with any collagen markers in this study. In multiple regression analysis adjusted for confounding factors such as age, sex, pulse pressure, mean blood pressure, pulse rate, LVMI, E/A ratio and DCT, the positive correlation between baPWV and total TIMP-1/MMP-1 ratio remained significant (p<0.05). In conclusion, arterial stiffness in high-risk older hypertensive patients may involve ECM collagen metabolism.

Familial Isolated Noncompaction of the Left Ventricular Myocardium

Noncompaction of the ventricular myocardium (sometimes referred to as ‘spongy myocardium’) is believed to represent an arrest in endomyocardial morphogenesis. The gross anatomical appearance is characterized by numerous excessively prominent trabeculations and deep intertrabecular recesses. Distinct morphological features can be diagnosed on two-dimensional echocardiography. We present here a family of isolated noncompaction of the left ventricular myocardium, in which 5 affected individuals suggested the presence of some genetic abnormalities in this disorder.

Production of hepatocyte growth factor during acute myocardial infarction

OBJECTIVE To investigate the clinical significance of circulating hepatocyte growth factor (HGF) and the role of peripheral blood mononuclear cells (monocytes), which are a possible source of HGF, in patients with acute myocardial infarction. DESIGN AND PATIENTS 37 patients with acute myocardial infarction and 13 normal control subjects were recruited. Peripheral venous blood samples were drawn from the infarct patients 1, 7, 14, and 21 days after onset. Monocytes were isolated from peripheral blood at those times. HGF concentrations in serum and in a culture medium of monocytes after incubation for 24 hours (monocyte HGF levels) were measured by enzyme linked immunosorbent assay. RESULTS Serum HGF and monocyte HGF values within seven days after onset of myocardial infarction were significantly higher than those of control subjects and decreased by day 14. There were significant positive correlations between serum HGF and monocyte HGF levels on day 7; between maximum plasma creatine phosphokinase levels and serum HGF levels on day 1; between maximum plasma C reactive protein and serum HGF levels; and between maximum C reactive protein and monocyte HGF levels. Monocyte HGF levels were raised in the patients with progression of ventricular enlargement in the course of acute myocardial infarction. CONCLUSIONS Early serum HGF concentrations reflect the extent of myocardial damage in acute myocardial infarction patients. Inflammation after acute myocardial infarction is supposed to be involved in enhanced HGF production. Monocytes may play an important role in ventricular remodelling after acute myocardial infarction by releasing the cardiovascular protective mitogen HGF.

Assessment of coagulation and platelet activation in coronary sinus blood induced by transcatheter coronary intervention for narrowing of the left anterior descending coronary artery.

Influences of recently developed methods for coronary intervention on hemostasis in the coronary circulation are unclear. The objective of this study was to investigate changes in coagulation and platelet activation in the coronary circulation induced by percutaneous transluminal coronary angioplasty (PTCA). We studied 35 patients with coronary heart disease who underwent elective PTCA to isolated stenotic narrowing of left coronary arteries. Seven patients received only PTCA, 12 underwent percutaneous transluminal rotational atherectomy (PTRA), and 16 underwent stent implantation. Blood samples were drawn from the coronary sinus immediately before and after as well as 4 and 24 hours after PTCA. Plasma levels of tissue factor (TF), thrombin-antithrombin III complex, plasminogen activator inhibitor (PAI)-1, tissue plasminogen activator (t-PA), beta-thromboglobulin, and platelet factor 4 were measured by enzyme-linked immunosorbent assay. In all patients, TF levels in the coronary sinus blood showed significant increases 4 and 24 hours after PTCA and thrombin-antithrombin III complex levels showed significant increases 24 hours after PTCA. PAI-1 showed significant increases 24 hours after PTCA and t-PA showed significant increases 4 and 24 hours after PTCA. Changes in levels of these markers by PTCA were similar among the 3 groups. In PTRA, levels of beta-thromboglobulin and platelet factor 4, markers of platelet activation, increased immediately after the procedure and returned to baseline levels after 4 hours. PTCA induced increases in blood coagulation and fibrinolysis in the coronary circulation. PTRA caused a marked but transient activation of platelets. These changes may contribute to acute complications during the procedure.