Hatsue Ishibashi-Ueda

Increased endoplasmic reticulum stress in atherosclerotic plaques associated with acute coronary syndrome

Background— The endoplasmic reticulum (ER) responds to various stresses by upregulation of ER chaperones, but prolonged ER stress eventually causes apoptosis. Although apoptosis is considered to be essential for the progression and rupture of atherosclerotic plaques, the influence of ER stress and apoptosis on rupture of unstable coronary plaques remains unclear. Methods and Results— Coronary artery segments were obtained at autopsy from 71 patients, and atherectomy specimens were obtained from 40 patients. Smooth muscle cells and macrophages in the fibrous caps of thin-cap atheroma and ruptured plaques, but not in the fibrous caps of thick-cap atheroma and fibrous plaques, showed a marked increase of ER chaperone expression and apoptotic cells. ER chaperones also showed higher expression in atherectomy specimens from patients with unstable angina pectoris than in specimens from those with stable angina. Expression of 7-ketocholesterol was increased in the fibrous caps of thin-cap atheroma compared with thick-cap atheroma. Treatment of cultured coronary artery smooth muscle cells or THP-1 cells with 7-ketocholesterol induced upregulation of ER chaperones and apoptosis, whereas these changes were prevented by antioxidants. We also investigated possible signaling pathways for ER-initiated apoptosis and found that the CHOP (a transcription factor induced by ER stress)-dependent pathway was activated in unstable plaques. In addition, knockdown of CHOP expression by small interfering RNA decreased ER stress-dependent death of cultured coronary artery smooth muscle cells and THP-1 cells. Conclusions— Increased ER stress occurs in unstable plaques. Our findings suggest that ER stress-induced apoptosis of smooth muscle cells and macrophages may contribute to plaque vulnerability.

Coronary calcification in patients with chronic kidney disease and coronary artery disease.

BACKGROUND AND OBJECTIVES A close linkage between chronic kidney disease (CKD) and cardiovascular disease (CVD) has been demonstrated. Coronary artery calcification (CAC) is considered to be the causal link connecting them. The aim of the study is to determine the relationship between level of kidney function and the prevalence of CAC. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Autopsy subjects known to have coronary artery disease and a wide range of kidney function were studied. Patients without CKD were classified into five groups depending on estimated GFR (eGFR) and proteinuria: eGFR > or =60 ml/min/1.73 m(2) without proteinuria; CKD1/2: eGFR > or =60 ml/min/1.73 m(2) with proteinuria; CKD3: 60 ml/min/1.73 m(2) >eGFR > or =30 ml/min/1.73 m(2); CKD4/5: eGFR <30 ml/min/1.73 m(2); and CKD5D: on hemodialysis. Intimal and medial calcification of the coronary arteries was evaluated. Risk factors for CVD and uremia were identified as relevant to CAC using logistic regression analysis. RESULTS Intimal calcification of plaques was present in all groups, but was most frequent and severe in the CKD5D group and less so in the CKD4/5 and CKD3 groups. Risk factors included luminal stenosis, age, smoking, diabetes, calcium-phosphorus product, inflammation, and kidney function. Medial calcification was seen in a small number of CKD4/5 and CKD5D groups. Risk factors were use of calcium-containing phosphate binders, hemodialysis treatment, and duration. CONCLUSIONS It was concluded that CAC was present in the intimal plaque of both nonrenal and renal patients. Renal function and traditional risks were linked to initimal calcification. Medial calcification occurred only in CKD patients.

Adrenomedullin Infusion Attenuates Myocardial Ischemia/Reperfusion Injury Through the Phosphatidylinositol 3-Kinase/Akt-Dependent Pathway

Background—Infusion of adrenomedullin (AM) has beneficial hemodynamic effects in patients with heart failure. However, the effect of AM on myocardial ischemia/reperfusion remains unknown. Methods and Results—Male Sprague-Dawley rats were exposed to a 30-minute period of ischemia induced by ligation of the left coronary artery. They were randomized to receive AM, AM plus wortmannin (a phosphatidylinositol 3-kinase [PI3K] inhibitor), or saline for 60 minutes after coronary ligation. Hemodynamics and infarct size were examined 24 hours after reperfusion. Myocardial apoptosis was also examined 6 hours after reperfusion. The effect of AM on Akt phosphorylation in cardiac tissues was examined by Western blotting. Intravenous administration of AM significantly reduced myocardial infarct size (28±4% to 16±1%, P <0.01), left ventricular end-diastolic pressure (19±2 to 8±2 mm Hg, P <0.05), and myocardial apoptotic death (19±2% to 9±4%, P <0.05). Western blot analysis showed that AM infusion accelerated Akt phosphorylation in cardiac tissues and that pretreatment with wortmannin significantly attenuated AM-induced Akt phosphorylation. Moreover, pretreatment with wortmannin abolished the beneficial effects of AM: a reduction of infarct size, a decrease in left ventricular end-diastolic pressure, and inhibition of myocardial apoptosis after ischemia/reperfusion. Conclusions—Short-term infusion of AM significantly attenuated myocardial ischemia/reperfusion injury. These cardioprotective effects are attributed mainly to antiapoptotic effects of AM via a PI3K/Akt-dependent pathway.

Overview of Late Outcome of Medical and Surgical Treatment for Takayasu Arteritis

Takayasu arteritis (TA), which is a nonspecific inflammatory disease of unknown origin, causes various types of aortoarterial stenosis/occlusion or dilatation (Figure). Historically, Mikito Takayasu, a Japanese ophthalmologist, described a peculiar wreathlike arteriovenous anastomosis around the papillae of the retina (Takayasu disease) in 1908.1 In the first necropsy case reported in 1940, this ophthalmologic finding was related to cervical vessel occlusion.2,3 Subsequently, this nonspecific panarteritis that affects the intima and the adventitia of the aorta and its main branches was called Takayasu arteritis . Its clinical manifestations are varied and related to the vessel that presents the stenotic or occlusive lesions, such as the aortic arch (pulseless disease),4 descending thoracic or abdominal aorta (atypical coarctation),5 renal arteries,6 coronary arteries,7 and pulmonary arteries. Aortic aneurysm8 and aortic valve regurgitation with ascending aortic dilatation9 may also develop in some instances. Pharmacological treatment with corticosteroids is usually the initial treatment. Some patients require surgical treatment such as bypass grafting and graft replacement or endovascular repair including percutaneous transluminal angioplasty (PTA) and stent grafting, even in the active phase or in the inactive chronic phase with adequate control of the inflammation. Since the 1960s, acceptable early and midterm outcomes of medical and/or surgical treatment have been published. However, the long-term outcome, including that of recently developed endovascular treatment, has not been discussed. In this article, we describe an overview, particularly focusing on the late outcome of treatment for TA. Figure. Three-dimensional computed tomographic findings of an active phase of Takayasu arteritis (21 years, female). Three-dimensional computed tomographic findings include multiple stenotic lesions on the carotid and subclavian arteries (A), aneurysmal dilatation of the ascending aorta to the aortic arch and of the main pulmonary artery (B), aneurysmal dilatation of the descending aorta, stenosis of the right renal …

Increased plasma monocyte chemoattractant protein‐1 level in idiopathic pulmonary arterial hypertension

Objective:  Monocyte chemoattractant protein‐1 (MCP‐1), a pro‐inflammatory chemokine, has potent chemoattractant activity for monocytes/macrophages. We sought to investigate the clinical significance of MCP‐1 in idiopathic pulmonary arterial hypertension (IPAH).

Hemorrhagic infarct of the brain without a reopening of the occluded arteries in cardioembolic stroke.

We examined the brains of 14 patients (four men and 10 women, mean age 68.9 years) who died from brain herniation after cardioembolic stroke with persistent occlusion of the internal carotid-middle cerebral arterial axis. Our examination showed hemorrhagic infarct in seven patients and pale infarct in the other seven, contradicting the commonly proposed pathophysiologic mechanism for the development of hemorrhagic infarct that the opening of previously occluded vessels makes an infarct hemorrhagic. Analysis of blood pressure after stroke revealed one or more surges of arterial hypertension or rapid rise of blood pressure in patients with hemorrhagic infarct without a reopening of the occluded artery. Such arterial hypertension was not always present in patients with pale infarct. Hemorrhage into an infarct with persisting occlusion of the proximal artery is assumed to occur when the involved blood vessels are exposed to the force of arterial blood pressure from the leptomeningeal collaterals. This occurs when arterial blood pressure rises after stroke in the presence of efficient leptomeningeal collaterals and before occlusion of these collaterals by a swollen cerebral hemisphere containing a large infarct.

Heart failure causes cholinergic transdifferentiation of cardiac sympathetic nerves via gp130-signaling cytokines in rodents

Although several cytokines and neurotrophic factors induce sympathetic neurons to transdifferentiate into cholinergic neurons in vitro, the physiological and pathophysiological roles of this remain unknown. During congestive heart failure (CHF), sympathetic neural tone is upregulated, but there is a paradoxical reduction in norepinephrine synthesis and reuptake in the cardiac sympathetic nervous system (SNS). Here we examined whether cholinergic transdifferentiation can occur in the cardiac SNS in rodent models of CHF and investigated the underlying molecular mechanism(s) using genetically modified mice. We used Dahl salt-sensitive rats to model CHF and found that, upon CHF induction, the cardiac SNS clearly acquired cholinergic characteristics. Of the various cholinergic differentiation factors, leukemia inhibitory factor (LIF) and cardiotrophin-1 were strongly upregulated in the ventricles of rats with CHF. Further, LIF and cardiotrophin-1 secreted from cultured failing rat cardiomyocytes induced cholinergic transdifferentiation in cultured sympathetic neurons, and this process was reversed by siRNAs targeting Lif and cardiotrophin-1. Consistent with the data in rats, heart-specific overexpression of LIF in mice caused cholinergic transdifferentiation in the cardiac SNS. Further, SNS-specific targeting of the gene encoding the gp130 subunit of the receptor for LIF and cardiotrophin-1 in mice prevented CHF-induced cholinergic transdifferentiation. Cholinergic transdifferentiation was also observed in the cardiac SNS of autopsied patients with CHF. Thus, CHF causes target-dependent cholinergic transdifferentiation of the cardiac SNS via gp130-signaling cytokines secreted from the failing myocardium.

Impact of anti-apoptotic and anti-oxidative effects of bone marrow mesenchymal stem cells with transient overexpression of heme oxygenase-1 on myocardial ischemia

Although mesenchymal stem cells (MSCs) have therapeutic potential for tissue injury, intolerance and poor cell viability limit their reparative capability. Therefore, we examined the impact of bone marrow-derived MSCs, in which heme oxygenase-1 (HO-1) was transiently overexpressed, on the repair of an ischemic myocardial injury. When MSCs and HO-1-overexpressed MSCs (MSC(HO-1)) were exposed to serum deprivation/hypoxia or H(2)O(2)-induced oxidative stress, MSC(HO-1) exhibited increased resistance to cell apoptosis compared with MSCs (17 +/- 1 vs. 30 +/- 2%, P < 0.05) and were markedly resistant to cell death (2 +/- 1 vs. 32 +/- 2%, P < 0.05). Under these conditions, vascular endothelial growth factor (VEGF) production was 2.1-fold greater in MSC(HO-1) than in MSCs. Pretreatment of MSCs and MSC(HO-1) with phosphatidylinositol 3-kinase (PI 3-kinase)/protein kinase B (Akt) pathway inhibitors such as LY-294002 (50 muM) or wortmannin (100 nM) significantly decreased VEGF production. In a rat infarction model with MSCs or MSC(HO-1) (5 x 10(6) +/- 0.1 x 10(6) cells/rat) transplantation, the number of TdT-mediated dUTP nick end-labeling-positive cells was significantly lower in the MSC(HO-1) group than in the MSC group (12.1 +/- 1.0 cells/field vs. 26.5 +/- 2.6, P < 0.05) on the 4th day after cell transplantation. On the 28th day, increased capillary density associated with decreased infarction size was observed in the MSC(HO-1) group (1,415 +/- 47/mm(2) with 21.6 +/- 2.3%) compared with those in the MSCs group (1,215 +/- 43/mm(2) with 28.2 +/- 2.3%, P < 0.05), although infarction size relative to area at risk was not different in each group at 24 h after transplantation. These results demonstrate that MSC(HO-1) exhibit markedly enhanced anti-apoptotic and anti-oxidative capabilities compared with MSCs, thus contributing to improved repair of ischemic myocardial injury through cell survival and VEGF production associated with the PI 3-kinase/Akt pathway.

Injury-induced neural stem/progenitor cells in post-stroke human cerebral cortex.

Increasing evidence points to accelerated neurogenesis after stroke, and support of such endogenous neurogenesis has been shown to improve stroke outcome in experimental animal models. The present study analyses post‐stroke cerebral cortex after cardiogenic embolism in autoptic human brain. Induction of nestin‐ and musashi‐1‐positive cells, potential neural stem/progenitor cells, was observed at the site of ischemic lesions from day 1 after stroke. These two cell populations were present at distinct locations and displayed different temporal profiles of marker expression. However, no surviving differentiated mature neural cells were observed by 90 days after stroke in the previously ischemic region. Consistent with recent reports of neurogenesis in the cerebral cortex after induction of stroke in rodent models, the present current data indicate the presence of a regional regenerative response in human cerebral cortex. Furthermore, observations underline the potential importance of supporting survival and differentiation of endogenous neural stem/progenitor cells in post‐stroke human brain.

Histologic Evidence of Foreign Body Granulation Tissue and de novo Lesions in Patients with Coronary Stent Restenosis

Objectives: We examined the relative contributions of foreign body granulation and de novo lesions to neointimal hyperplasia in atherectomized specimens of restenosis after coronary stenting. Background: Clinicopathological studies have suggested that smooth muscle cell (SMC) hyperplasia is the most likely cause of restenosis after coronary stenting. It is not yet fully understood how SMC hyperplasia occurs or how SMCs stimulation can lead to intimal hyperplasia. Although inflammation has been postulated to be a major contributor to restenosis after coronary stenting, there is a paucity of data on the relationsip between inflammation and subsequent neointimal formation in humans. Only in a porcine experimental model of stent restenosis, foreign body granulation tissue as a cause of inflammation in stent restenosis was reported. Methods: Tissue specimens were retrieved by directional atherectomy from 11 patients in whom stent restenosis developed after percutaneous revascularization of coronary artery disease. For specimens preserved in 10% buffered formalin, analysis of cellular composition was performed quantitatively after cell-specific immunostaining, i.e. CD68, UCHL-1, HLA-DR, smooth muscle actin, vimentin, desmin, PCNA and TGF-β. Results: Five of the 11 patients showed granulation tissues 3–6 months after stent implantation, of whom 3 patients revealed foreign body multinucleated giant cells around the stent struts where PCNA- and vimentin-positive SMCs were demonstrated. Calcification and de novo lesions in medial and adventitial tissues were observed in 3 other patients, and fresh and/or organized thrombi were documented in 3 of the 11 patients. Conclusions: These findings support the notion that stent restenosis results from SMC hyperplasia and suggest that the foreign body granulation tissue against metals of the stents and de novo lesions could play an important role in chronic inflammation leading to intimal hyperplasia and subsequently to stent restenosis in some patients. Clinicians should thus consider whether a patient may be allergic to stent components with unknown reaction, e.g. haptens.