Makiko Ueda

Spotty Calcification Typifies the Culprit Plaque in Patients With Acute Myocardial Infarction An Intravascular Ultrasound Study

Background—Calcification is a common finding in human coronary arteries; however, the relationship between calcification patterns, plaque morphology, and patterns of remodeling of culprit lesions in a comparison of patients with acute coronary syndromes (ACS) and those with stable conditions has not been documented. Methods and Results—Preinterventional intravascular ultrasound (IVUS) images of 178 patients were studied, 61 with acute myocardial infarction (AMI), 70 with unstable angina pectoris (UAP), and 47 with stable angina pectoris (SAP). The frequency of calcium deposits within an arc of less than 90° for all calcium deposits was significantly different in culprit lesions of patients with AMI, UAP, and SAP (P<0.0001). Moreover, the average number of calcium deposits within an arc of <90° per patient was significantly higher in AMI than in SAP (P<0.0005; mean±SD, AMI 1.4±1.3, SAP 0.5±0.8). Conversely, calcium deposits were significantly longer in SAP patients (P<0.0001; mean±SD, AMI 2.2±1.6, UAP 1.9±1.8, and SAP 4.3±3.2 mm). In AMI patients, the typical pattern was spotty calcification, associated with a fibrofatty plaque and positive remodeling. In ACS patients showing negative remodeling, no calcification was the most frequent observation. Conversely, SAP patients had the highest frequency of extensive calcification. Conclusions—Our observations show that IVUS allows the identification of vulnerable plaques in coronary arteries, not only by identifying a fibrofatty plaque and positive remodeling, but also by identifying a spotty pattern of calcification.

Vascular Endothelial Growth Factor (VEGF) Expression in Human Coronary Atherosclerotic Lesions Possible Pathophysiological Significance of VEGF in Progression of Atherosclerosis

BACKGROUND Vascular endothelial growth factor (VEGF) is an important angiogenic factor reported to induce migration and proliferation of endothelial cells, enhance vascular permeability, and modulate thrombogenicity. VEGF expression in cultured cells (smooth muscle cells, macrophages, endothelial cells) is controlled by growth factors and cytokines. Hence, the question arises of whether VEGF could play a role in atherogenesis. METHODS AND RESULTS Frozen sections from 38 coronary artery segments were studied. The specimens were characterized as normal with diffuse intimal thickening, early atherosclerosis with hypercellularity, and advanced atherosclerosis (atheromatous plaques, fibrous plaques, and totally occlusive lesions). VEGF expression as well as the expression of 2 VEGF receptors, flt-1 and Flk-1, were studied with immunohistochemical techniques in these samples at the different stages of human coronary atherosclerosis progression. The expression of VEGF mRNA was also studied with reverse transcription-polymerase chain reaction. Normal arterial segments showed no substantial VEGF expression. Hypercellular and atheromatous lesions showed distinct VEGF positivity of activated endothelial cells, macrophages, and partially differentiated smooth muscle cells. VEGF positivity was also detected in endothelial cells of intraplaque microvessels within advanced lesions. In totally occlusive lesions with extensive neovascularization, intense immunostaining for VEGF was observed in accumulated macrophages and endothelial cells of the microvessels. Furthermore, VEGF mRNA expression was detected in atherosclerotic coronary segments but not in normal coronary segments. The immunostainings for flt-1 and Flk-1 were detected in aggregating macrophages in atherosclerotic lesions and also in endothelial cells of the microvessels in totally occlusive lesions. CONCLUSIONS These results demonstrate distinct expression of VEGF and its receptors (flt-1 and Flk-1) in atherosclerotic lesions in human coronary arteries. Considering the multipotent actions of VEGF documented experimentally in vivo and in vitro, our findings suggest that VEGF may have some role in the progression of human coronary atherosclerosis, as well as in recanalization processes in obstructive coronary diseases.

Neointimal Tissue Response at Sites of Coronary Stenting in Humans Macroscopic, Histological, and Immunohistochemical Analyses

BACKGROUND Experimental animal studies have shown that coronary stenting induces neointimal proliferation. However, the histopathological events after coronary stenting in humans have not been studied systematically. METHODS AND RESULTS We investigated 11 stented coronary arteries (9 Palmaz-Schatz stents, 1 Wiktor stent, and 1 ACS Multi-Link stent) obtained from 11 patients who had died 2 days to 21 months after stenting. We focused on gross, histological, and immunohistochemical aspects of the repair processes. Two patients developed symptoms of restenosis. Serial sections were stained with antibodies against smooth muscle cells (SMCs), macrophages, and endothelial cells. At 9 and 12 days after stenting, the stent sites showed thrombus formation with early formation of neointima composed of abundant macrophages and alpha-actin-negative spindle cells. From 64 days on, all sites with stenting showed a distinct layer of neointima, albeit to varying degrees. In nonrestenotic lesions, neointimal thickening was markedly less than in restenotic lesions but without qualitative differences; the neointima contained macrophages but was composed predominantly of alpha-actin-positive SMCs. CONCLUSIONS These observations strongly support the concept that neointimal proliferation in humans is a process of staged redifferentiation of SMCs, which may cause in-stent stenosis. Moreover, the exuberant neointimal proliferation with accumulation of macrophages and extensive neovascularization at sites of stent restenosis suggests a role for organization of mural thrombus.

Telomere Shortening in Human Coronary Artery Diseases

Background—Increased cell turnover in response to injury is considered to be important in the development of atherosclerotic plaques. Telomere shortening has been shown to be associated with cell turnover. We assessed the telomere length of human coronary endothelial cells to clarify whether there is a relationship between telomere shortening and coronary artery disease (CAD). Methods and Results—Coronary endothelial cells were obtained from 11 patients with CAD who underwent autopsy and 22 patients without CAD who underwent autopsy by scraping off the luminal surface of coronary arteries. DNA extracted from the endothelial cells were blotted and hybridized with telomere-specific oligonucleotide ([TTAGGG]4). The hybridization signal intensity, which represented telomeric DNA content, was standardized with centromeric DNA content (T/C ratio) to estimate telomere length. The T/C ratios were significantly smaller (P <0.0001) in CAD patients than in age-matched non-CAD patients (CAD patients, 0.462±0.135; non-CAD patients, 1.002±0.212). In 6 individual CAD patients, the T/C ratio at the atherosclerotic lesion was significantly smaller (P <0.05) than that at the non-atherosclerotic portion. Conclusions—These findings suggest that focal replicative senescence and telomere shortening of endothelial cells may play a critical role in coronary atherogenesis and CAD.

In Vivo Effect of TGF-β1: Enhanced Intimal Thickening by Administration of TGF-β1 in Rabbit Arteries Injured With a Balloon Catheter

Abstract The in vivo effect of transforming growth factor–β1 (TGF-β1) was studied in a model system in which arterial intimal thickening was induced by injury of rabbit arteries with a balloon cath...

Redifferentiation of Smooth Muscle Cells After Coronary Angioplasty Determined via Myosin Heavy Chain Expression

BACKGROUND The pathophysiology of phenotypic modulation of smooth muscle cells (SMCs) involved in restenosis after angioplasty is not well understood. Smooth muscle myosin heavy chain (SM MHC) isoforms (SM1 and SM2) are specific markers for SMC differentiation. In particular, SM2 is useful as a marker of mature SMCs. SMemb is a nonmuscle myosin heavy chain (NM MHC) whose expression is upregulated in immature or activated SMC. METHODS AND RESULTS To determine SMC phenotypes in neointimal tissues after percutaneous transluminal coronary angioplasty (PTCA), we performed immunohistochemistry on human coronary arteries with antibodies against alpha-SM actin, SM1, SM2, and SMemb. Tissues were obtained from six autopsied patients and from atherectomy specimens from 16 patients who had undergone PTCA. Medial SMCs were positive for alpha-actin, SM1, and SM2. Expression of SM1 and SM2 in the neointima varied with the time after intervention, whereas alpha-actin was constitutively expressed in all cases studied. Neointimal cells at 16 and 20 days after PTCA contained alpha-actin but little or no SM1 or SM2, indicating that these cells modulated their phenotype to the immature state. Neointimal SMCs recovered SM MHC expression, first SM1 and then SM2, by 6 months after PTCA. Increased expression of SMemb was found in the neointima but without apparent relationship to the time after PTCA. CONCLUSIONS Neointimal SMCs show features of an undifferentiated state, indicated by altered expression of SM MHC, and undergo redifferentiation in a time-dependent manner. The expression of SM MHC isoforms provides insight into the biology of healing after angioplasty and furnishes useful tools for the understanding of the roles of differentiation and phenotypic modulation of SMCs in human vascular lesions.

Localization of oxidized phosphatidylcholine in nonalcoholic fatty liver disease: Impact on disease progression

Nonalcoholic steatohepatitis/nonalcoholic fatty liver disease is considered to be a hepatic manifestation of various metabolic disorders. However, its precise pathogenic mechanism is obscure. Oxidative stress and consequent lipid peroxidation seem to play a pivotal role in disease progression. In this study, we analyzed the localization of oxidized phosphatidylcholine (oxPC), a lipid peroxide that serves as a ligand for scavenger receptors, in livers of patients with this steatotic disorder. Specimens of non‐alcoholic fatty liver disease (15 autopsy livers with simple steatosis and 32 biopsy livers with steatohepatitis) were examined via immunohistochemistry and immunoelectron microscopy using a specific antibody against oxPC. In addition, scavenger receptor expression, hepatocyte apoptosis, iron deposition, and inflammatory cell infiltration in the diseased livers were also assessed. Oxidized phosphatidylcholine was mainly localized to steatotic hepatocytes and some macrophages/Kupffer cells. A few degenerative or apoptotic hepatocytes were also positive for oxPC. Immunoelectron microscopy showed oxPC localized to cytoplasmic/intracytoplasmic membranes including lipid droplets. Steatotic livers showed enhanced expression of scavenger receptors. The number of oxPC cells was correlated with disease severity and the number of myeloperoxidase‐positive neutrophils, but not with the degree of iron deposition. In conclusion, distinct localization of oxPC in liver tissues suggest that neutrophil myeloperoxidase‐derived oxidative stress may be crucial in the formation of oxPC and the progression of steatotic liver disease. (HEPATOLOGY 2006;43:506–514.)

Enhanced expression of angiotensin-converting enzyme is associated with progression of coronary atherosclerosis in humans

Background The clinical usefulness of angiotensin converting enzyme (ACE) inhibitors in preventing the recurrence of myocardial infarction has been investigated in large randomized trials. Results from many studies using animal models have suggested that ACE inhibitors have vasculoprotective effects, which may contribute to the prevention of coronary atherosclerosis. Objective To examine the association between vascular angiotensin generation and the development of coronary atherosclerosis in humans. Methods We used immunocytochemical techniques to examine frozen sections from 44 coronary artery segments from 19 corpses. Results Three segments were sites of plaque rupture in patients who had died from acute myocardial infarction. Other specimens of coronary artery segments were characterized histologically to be normal artery segments with diffuse intimal thickening (n = 6), hypercellular lesions composed of smooth muscle cells with or without infiltration of macrophages (n = 11), atheromatous plaque (n = 12), and fibrosclerotic plaque (n = 12). In normal arteries with diffuse intimal thickening, ACE was expressed in endothelial cells. In those with hypercellular lesions and atheromatous plaques, however, enhanced ACE expression was found in macrophages and smooth muscle cells. In contrast, arteries with fibrosclerotic plaques exhibited little or no ACE expression within the plaque. All three ruptured plaques expressed ACE strongly in macrophages accumulated around the attenuated fibrous cap. Conclusion The strong association of enhanced ACE expression with the histologic characteristics of plaques suggests that ACE in hypercellular lesions, atheromatous plaques, and ruptured plaques contributes greatly to the further progression of atherosclerosis via an increase in vascular angiotensin II formation and inactivation of bradykinin.

Fibrocellular tissue response after percutaneous transluminal coronary angioplasty. An immunocytochemical analysis of the cellular composition.

BackgroundRestenosis after initial, successful percutaneous transluminal coronary angioplasty (PTCA) is due to fibrocellular proliferation. Methods and ResultsThe present study focused on the nature of fibrocellular tissue in humans by use of immunocytochemical techniques. Four hearts (five coronary arteries) were investigated; time lapse between PTCA and death varied between 20 days (two arteries) and 1 year 7 months. Proliferating cells stained positive with smooth muscle cell-specific monoclonal antibodies. Cells from early proliferative lesions (20 days) have a phenotypic expression different from cells in “old” lesions. Proliferating cells stained positive with vimentin but were negative with desmin, irrespective of the lesions age. ConclusionsThe findings indicate a change in actin isoform expression of smooth muscle cells while adapting to a pathological state.

Increased expression of T cell activation markers (CD25, CD26, CD40L and CD69) in atherectomy specimens of patients with unstable angina and acute myocardial infarction

Atherosclerotic plaques contain a chronic immune mediated inflammation in which T cells play an important role. A previous study revealed that the numbers of interleukin-2 receptor-positive T cells is increased in culprit lesions of patients with acute coronary syndromes; a finding of considerable interest since it indicates a recent change in the intraplaque T cell mediated immune response. Confirmation of this observation is important, because it could provide insight into the onset of the acute event. We have, therefore, expanded our earlier work by using a panel of different T cell activation markers (CD25, CD26, CD40L, CD69). The study is based on 58 culprit lesions from patients who underwent coronary atherectomy. There were four groups of patients: chronic stable angina (n=13), stabilized unstable angina (n=16), refractory unstable angina (n=15), and acute myocardial infarction (AMI; n=14). Activated T cells were expressed as a percentage of the total of CD3-positive cells. CD25, CD26, CD40L, and CD69/CD3 percentages increased with the severity of the coronary syndrome. In patients with AMI all percentages were significantly higher than in patients with chronic stable angina. CD25, CD26, CD40L, and CD69/CD3 percentages in patients with an unstable condition (refractory unstable angina and AMI) were significantly higher than those in patients with a stable condition (chronic stable or stabilized unstable angina) The finding that the percentage of T cells with recent onset activation is significantly increased in the culprit lesions of patients with acute coronary syndromes suggests strongly that a recent change in pathogenic stimulation has occurred leading to local T cell activation.