Expression of the angiogenic protein, platelet-derived endothelial cell growth factor, in coronary atherosclerotic plaques: In vivo correlation of lesional microvessel density and constrictive vascular remodeling

Angiogenic content of microparticles in patients with diabetes and coronary artery disease predicts networks of endothelial dysfunction

BACKGROUND

Elevated endothelial microparticles (EMPs) levels are surrogate markers of vascular dysfunction. We analyzed EMPs with apoptotic characteristics and assessed the angiogenic contents of microparticles in the blood of patients with type 2 diabetes (T2D) according to the presence of coronary artery disease (CAD).

METHODS

A total of 80 participants were recruited and equally classified as (1) healthy without T2D, (2) T2D without cardiovascular complications, (3) T2D and chronic coronary artery disease (CAD), and (4) T2D and acute coronary syndrome (ACS). MPs were isolated from the peripheral circulation, and EMPs were characterized using flow cytometry of CD42 and CD31. CD62E was used to determine EMPs' apoptotic/activation state. MPs content was extracted and profiled using an angiogenesis array.

RESULTS

Levels of CD42- CD31 + EMPs were significantly increased in T2D with ACS (257.5 ± 35.58) when compared to healthy subjects (105.7 ± 12.96, p < 0.01). There was no significant difference when comparing T2D with and without chronic CAD. The ratio of CD42-CD62 +/CD42-CD31 + EMPs was reduced in all T2D patients, with further reduction in ACS when compared to chronic CAD, reflecting a release by apoptotic endothelial cells. The angiogenic content of the full population of MPs was analyzed. It revealed a significant differential expression of 5 factors in patients with ACS and diabetes, including TGF-β1, PD-ECGF, platelet factor 4, serpin E1, and thrombospondin 1. Ingenuity Pathway Analysis revealed that those five differentially expressed molecules, mainly TGF-β1, inhibit key pathways involved in normal endothelial function. Further comparison of the three diabetes groups to healthy controls and diabetes without cardiovascular disease to diabetes with CAD identified networks that inhibit normal endothelial cell function. Interestingly, DDP-IV was the only differentially expressed protein between chronic CAD and ACS in patients with diabetes.

CONCLUSION

Our data showed that the release of apoptosis-induced EMPs is increased in diabetes, irrespective of CAD, ACS patients having the highest levels. The protein contents of MPs interact in networks that indicate vascular dysfunction.

Targeting Thymidine Phosphorylase With Tipiracil Hydrochloride Attenuates Thrombosis Without Increasing Risk of Bleeding in Mice

OBJECTIVE

Current antiplatelet medications increase the risk of bleeding, which leads to a clear clinical need in developing novel mechanism-based antiplatelet drugs. TYMP (Thymidine phosphorylase), a cytoplasm protein that is highly expressed in platelets, facilitates multiple agonist-induced platelet activation, and enhances thrombosis. Tipiracil hydrochloride (TPI), a selective TYMP inhibitor, has been approved by the Food and Drug Administration for clinical use. We tested the hypothesis that TPI is a safe antithrombotic medication. Approach and Results: By coexpression of TYMP and Lyn, GST (glutathione S-transferase) tagged Lyn-SH3 domain or Lyn-SH2 domain, we showed the direct evidence that TYMP binds to Lyn through both SH3 and SH2 domains, and TPI diminished the binding. TYMP deficiency significantly inhibits thrombosis in vivo in both sexes. Pretreatment of platelets with TPI rapidly inhibited collagen- and ADP-induced platelet aggregation. Under either normal or hyperlipidemic conditions, treating wild-type mice with TPI via intraperitoneal injection, intravenous injection, or gavage feeding dramatically inhibited thrombosis without inducing significant bleeding. Even at high doses, TPI has a lower bleeding side effect compared with aspirin and clopidogrel. Intravenous delivery of TPI alone or combined with tissue plasminogen activator dramatically inhibited thrombosis. Dual administration of a very low dose of aspirin and TPI, which had no antithrombotic effects when used alone, significantly inhibited thrombosis without disturbing hemostasis.

CONCLUSIONS

This study demonstrated that inhibition of TYMP, a cytoplasmic protein, attenuated multiple signaling pathways that mediate platelet activation, aggregation, and thrombosis. TPI can be used as a novel antithrombotic medication without the increase in risk of bleeding.

Immunological Aspects of Age-Related Macular Degeneration

Increasing evidence over the past two decades points to a pivotal role for immune mechanisms in age-related macular degeneration (AMD) pathobiology. In this chapter, we will explore immunological aspects of AMD, with a specific focus on how immune mechanisms modulate clinical phenotypes of disease and severity and how components of the immune system may serve as triggers for disease progression in both dry and neovascular AMD. We will briefly review the biology of the immune system, defining the role of immune mechanisms in chronic degenerative disease and differentiating from immune responses to acute injury or infection. We will explore current understanding of the roles of innate immunity (especially macrophages), antigen-specific immunity (T cells, B cells, and autoimmunity), immune amplifications systems, especially complement activity and the NLRP3 inflammasome, in the pathogenesis of both dry and neovascular AMD, reviewing data from pathology, experimental animal models, and clinical studies of AMD patients. We will also assess how interactions between the immune system and infectious pathogens could potentially modulate AMD pathobiology via alterations in in immune effector mechanisms. We will conclude by reviewing the paradigm of "response to injury," which provides a means to integrate various immunologic mechanisms along with nonimmune mechanisms of tissue injury and repair as a model to understand the pathobiology of AMD.

Vascular Damage - Coronary Artery Disease

Cardiovascular complications during chemotherapy and radiotherapy are becoming an increasing problem because many patients with cancer are treated with agents that exert significant vascular toxicity. Coronary heart disease in patients with cancer presents particular challenges, which directly impact the management of both the coronary disease and malignancy. Several chemotherapeutic agents have been shown to trigger ischemic heart disease, and as it has happened for myocardial cardiotoxicity, more attention should be dedicated to improving early recognition and prevention of cardiac vascular toxicity. Cardiac imaging could facilitate early detection of vascular toxicity, but a thorough risk stratification should always be performed to identify patients at higher risk of vascular impairment.

Angiogenic growth factors in myocardial infarction: a critical appraisal

In the recent past, substantial advances have been made in the treatment of myocardial infarction (MI). Despite the impact of these positive developments, MI remains to be a leading cause of morbidity as well as mortality. An interesting hypothesis is that the development of new blood vessels (angiogenesis) or the remodeling of preexisting collaterals may form natural bypasses that could compensate for the occlusion of an epicardial coronary artery. A number of angiogenic factors are proven to be elicited during MI. Exogenous supplementation of these growth factors either in the form of recombinant protein or gene would enhance the collateral vessel formation and thereby improve the outcome after MI. The aim of this review is to describe the nature and potentials of different angiogenic factors, their expression, their efficacy in animal studies, and clinical trials pertaining to MI.

Thymidine phosphorylase: A potential new target for treating cardiovascular disease

We recently found that thymidine phosphorylase (TYMP), also known as platelet-derived endothelial cell growth factor, plays an important role in platelet activation in vitro and thrombosis in vivo by participating in multiple signaling pathways. Platelets are a major source of TYMP. Since platelet-mediated clot formation is a key event in several fatal diseases, such as myocardial infarction, stroke and pulmonary embolism, understanding TYMP in depth may lead to uncovering novel mechanisms in the development of cardiovascular diseases. Targeting TYMP may become a novel therapeutic for cardiovascular disorders. In this review article, we summarize the discovery of TYMP and the potential molecular mechanisms of TYMP involved in the development of various diseases, especially cardiovascular diseases. We also offer insights regarding future studies exploring the role of TYMP in the development of cardiovascular disease as well as in therapy.

Pathophysiology of cardiotoxicity induced by nonanthracycline chemotherapy

The risk and mechanism of chemotherapy-induced cardiotoxicity (CTX) vary depending on the type and intensity of the anticancer regimen. Myriad chemotherapeutic drugs produce adverse cardiovascular effects such as arterial hypertension, heart failure, and thromboembolic events. Among the numerous classes of these drugs, anthracyclines have been studied most extensively because of their overt cardiovascular effects and the high associated incidence of heart failure. However, CTX might also be caused by other types of chemotherapeutic agents, including alkylating agents (cyclophosphamide, ifosfamide), platinum agents, antimetabolites (5-fluorouracil, capecitabine), antibiotics (mitoxantrone, mitomycin, bleomycin), and antimicrotubule agents (taxanes). Here, we review the incidence, clinical impact, and potential mechanisms of CTX associated with nonanthracycline chemotherapy used for cancer patients. The published data support a marked increase in CTX risk, particularly with certain drugs such as 5-fluorouracil and cisplatin. Each anticancer regimen is associated with distinct modes of heart damage, both symptomatic and asymptomatic. However, the underlying mechanisms of CTX have been established only in a few cases, and only few nonanthracycline chemotherapeutics (mitoxantrone, mitomycin, ifosfamide) act through a recognizable mechanism and show a predictable dose dependence. Lastly, nonanthracycline chemotherapy can induce both chronic lesions, such as systolic dysfunction, and acute lesions, such as the ischemia that occurs within hours or days after treatment. An increased understanding of the incidence, mechanisms, and potential therapeutic targets of CTX induced by various nonanthracycline chemotherapeutic agents is clearly required.

5-fluorouracil causes endothelial cell senescence: potential protective role of glucagon-like peptide 1

BACKGROUND AND PURPOSE

5-fluorouracil (5FU) and its prodrug, capecitabine, can damage endothelial cells, whilst endothelial integrity is preserved by glucagon-like peptide 1 (GLP-1). Here, we studied the effect of 5FU on endothelial senescence and whether GLP-1 antagonizes it.

EXPERIMENTAL APPROACH

EA.hy926 cells were exposed to 5FU or sera from patients taking capecitabine, with or without pre-incubation with GLP-1. Senescence was identified by expression of senescence-associated β-galactosidase and p16^INK4a and reduced cell proliferation. Soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1) and CD146 (marker of endothelial injury) were measured by ELISA before and at completion of capecitabine chemotherapy. RT-PCR, western blotting, functional experiments with signalling inhibitors and ERK1/2 silencing were performed to characterize 5FU-induced phenotype and elucidate the pathways underlying 5FU and GLP-1 activity.

KEY RESULTS

Both 5FU and sera from capecitabine-treated patients stimulated endothelial cell senescence. 5FU-elicited senescence occurred via activation of p38 and JNK, and was associated with decreased eNOS and SIRT-1 levels. Furthermore, 5FU up-regulated VCAM1 and TYMP (encodes enzyme activating capecitabine and 5FU), and sVCAM-1 and CD146 concentrations were higher after than before capecitabine chemotherapy. A non-significant trend for higher ICAM1 levels was also observed. GLP-1 counteracted 5FU-initiated senescence and reduced eNOS and SIRT-1 expression, this protection being mediated by GLP-1 receptor, ERK1/2 and, possibly, PKA and PI3K.

CONCLUSIONS AND IMPLICATIONS

5FU causes endothelial cell senescence and dysfunction, which may contribute to its cardiovascular side effects. 5FU-triggered senescence was prevented by GLP-1, raising the possibility of using GLP-1 analogues and degradation inhibitors to treat 5FU and capecitabine vascular toxicity.

LINKED ARTICLES

This article is part of a themed section on New Insights into Cardiotoxicity Caused by Chemotherapeutic Agents. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.21/issuetoc.

Mutually Supportive Mechanisms of Inflammation and Vascular Remodeling

Chronic inflammation is often accompanied by angiogenesis, the development of new blood vessels from existing ones. This vascular response is a response to chronic hypoxia and/or ischemia, but is also contributory to the progression of disorders including atherosclerosis, arthritis, and tumor growth. Proinflammatory and proangiogenic mediators and signaling pathways form a complex and interrelated network in these conditions, and many factors exert multiple effects. Inflammation drives angiogenesis by direct and indirect mechanisms, promoting endothelial proliferation, migration, and vessel sprouting, but also by mediating extracellular matrix remodeling and release of sequestered growth factors, and recruitment of proangiogenic leukocyte subsets. The role of inflammation in promoting angiogenesis is well documented, but by facilitating greater infiltration of leukocytes and plasma proteins into inflamed tissues, angiogenesis can also propagate chronic inflammation. This review examines the mutually supportive relationship between angiogenesis and inflammation, and considers how these interactions might be exploited to promote resolution of chronic inflammatory or angiogenic disorders.

Effects of 5-fluorouracil on morphology, cell cycle, proliferation, apoptosis, autophagy and ROS production in endothelial cells and cardiomyocytes

Antimetabolites are a class of effective anticancer drugs interfering in essential biochemical processes. 5-Fluorouracil (5-FU) and its prodrug Capecitabine are widely used in the treatment of several solid tumors (gastro-intestinal, gynecological, head and neck, breast carcinomas). Therapy with fluoropyrimidines is associated with a wide range of adverse effects, including diarrhea, dehydration, abdominal pain, nausea, stomatitis, and hand-foot syndrome. Among the 5-FU side effects, increasing attention is given to cardiovascular toxicities induced at different levels and intensities. Since the mechanisms related to 5-FU-induced cardiotoxicity are still unclear, we examined the effects of 5-FU on primary cell cultures of human cardiomyocytes and endothelial cells, which represent two key components of the cardiovascular system. We analyzed at the cellular and molecular level 5-FU effects on cell proliferation, cell cycle, survival and induction of apoptosis, in an experimental cardioncology approach. We observed autophagic features at the ultrastructural and molecular levels, in particular in 5-FU exposed cardiomyocytes. Reactive oxygen species (ROS) elevation characterized the endothelial response. These responses were prevented by a ROS scavenger. We found induction of a senescent phenotype on both cell types treated with 5-FU. In vivo, in a xenograft model of colon cancer, we showed that 5-FU treatment induced ultrastructural changes in the endothelium of various organs. Taken together, our data suggest that 5-FU can affect, both at the cellular and molecular levels, two key cell types of the cardiovascular system, potentially explaining some manifestations of 5-FU-induced cardiovascular toxicity.

Thymidine phosphorylase participates in platelet signaling and promotes thrombosis

RATIONALE

Platelets contain abundant thymidine phosphorylase (TYMP), which is highly expressed in diseases with high risk of thrombosis, such as atherosclerosis and type II diabetes mellitus.

OBJECTIVE

To test the hypothesis that TYMP participates in platelet signaling and promotes thrombosis.

METHODS AND RESULTS

By using a ferric chloride (FeCl3)-induced carotid artery injury thrombosis model, we found time to blood flow cessation was significantly prolonged in Tymp(-/-) and Tymp(+/-) mice compared with wild-type mice. Bone marrow transplantation and platelet transfusion studies demonstrated that platelet TYMP was responsible for the antithrombotic phenomenon in the TYMP-deficient mice. Collagen-, collagen-related peptide-, adenosine diphosphate-, or thrombin-induced platelet aggregation were significantly attenuated in Tymp(+/-) and Tymp(-/-) platelets, and in wild type or human platelets pretreated with TYMP inhibitor KIN59. Tymp deficiency also significantly decreased agonist-induced P-selectin expression. TYMP contains an N-terminal SH3 domain-binding proline-rich motif and forms a complex with the tyrosine kinases Lyn, Fyn, and Yes in platelets. TYMP-associated Lyn was inactive in resting platelets, and TYMP trapped and diminished active Lyn after collagen stimulation. Tymp/Lyn double haploinsufficiency diminished the antithrombotic phenotype of Tymp(+/-) mice. TYMP deletion or inhibition of TYMP with KIN59 dramatically increased platelet-endothelial cell adhesion molecule 1 tyrosine phosphorylation and diminished collagen-related peptide- or collagen-induced AKT phosphorylation. In vivo administration of KIN59 significantly inhibited FeCl3-induced carotid artery thrombosis without affecting hemostasis.

CONCLUSIONS

TYMP participates in multiple platelet signaling pathways and regulates platelet activation and thrombosis. Targeting TYMP might be a novel antiplatelet and antithrombosis therapy.

Capecitabine-induced cardiotoxicity: more evidence or clinical approaches to protect the patients' heart?

Fluoropyrimidines, such as capecitabine and 5-fluorouracil, may cause cardiac toxicity. In recent years, the incidence of this side effect has increased and it is expected to further rise due to the population aging and the disproportionate incidence of breast and gastrointestinal cancers in older individuals. The spectrum of cardiac manifestations includes different signs and symptoms and the diagnosis may be difficult. Here, we report the case of a 43-year-old woman with advanced breast cancer who was rechallenged with a capecitabine-based regimen after experiencing a cardiac adverse event during the first fluoropyrimidine exposure. This real-practice case serves as a springboard for discussion about the current evidence on differential diagnosis of capecitabine-related cardiac toxicity, its risk factors, and the underpinning mechanisms of early onset. Moreover, we discussed whether a rechallenge with fluoropyrimidines could be safe in patients who had experienced a previous cardiac adverse event.

Experimentally induced puromycine aminonucleoside nephrosis (PAN) in rats: evaluation of angiogenic protein platelet-derived endothelial cell growth factor (PD-ECGF) expression in glomeruli

BACKGROUND

In experimentally induced puromycine aminonucleoside nephrosis (PAN) animal models, nephrotic syndrome with minimal change disease and focal and segmental sclerosis-like nephritis similar to that in human is demonstrated; however, the real mechanism of PAN is not yet elucidated. Platelet derived endothelial cell growth factor (PD-ECGF), an endothelial mitogen protein, is believed to take part in microvessel formation and in stimulation of angiogenesis and its expression has not been totally demonstrated in PAN rats yet. In this study, we aimed to examine PD-ECGF expression in acute and chronic PAN induced in rats and find out the association between its expression and the stages of angiogenesis in kidney.

METHODS

For the experiment, twenty-four Male Wistar Albino rats were used and divided into four groups; control group (n = 6), pre-proteinuria group (n = 6), acute group (n = 6) and chronic group (n = 6). We compared statistically all data by One-way ANOVA Test followed by Dunn Multiple Comparison Test.

RESULTS

Proteinurea levels in control and pre-proteinuria groups were not statistically different; however, it was remarkably higher in the acute nephrosis group and significantly greater in the chronic nephrosis group than control group (p < 0.0025). In pre-proteinuria group, the serum albumin and creatinine clearances also did not significantly differ from the control group. On the other hand, in the acute and chronic nephrosis groups, serum albumin and creatinine clearances progressively decreased (p < 0.05). In our immunohistochemical studies, we showed elevated PD-ECGF expression in glomeruli of acute and chronic PAN rats. Microscopic and ultrastructural appearances of the glomeruli of acute and chronic PAN showed various sequential steps of angiogenesis, macrophages and immature capillaries with primitive lumens and apoptotic endothelial cells in the increased mesangial matrix.

CONCLUSIONS

It is reported that acute and chronic PAN progressively increase PD-ECGF expression and following induction of angiogenesis in the affected glomeruli.

Therapeutic angiogenesis for myocardial ischemia revisited: basic biological concepts and focus on latest clinical trials

Therapeutic angiogenesis is based on the premise that the development of new blood vessels can be augmented by exogenous administration of the appropriate growth factors. Over the last years, successful preclinical studies and promising results of early clinical trials have created great excitement about the potential of therapeutic angiogenesis for patients with advanced ischemic heart disease. The authors provide an overview of the biology of angiogenesis, the basic characteristics of angiogenic factors, and the different routes of their delivery. They discuss experimental studies in animal models of myocardial ischemia and outline available clinical studies on therapeutic angiogenesis for myocardial ischemia. Related safety issues are also addressed followed by a critical perspective about the future of proangiogenic therapies for ischemic cardiovascular disorders. Despite the established proof of concept and reasonable safety, however, results of the latest trials on therapeutic angiogenesis for myocardial ischemia have provided inconsistent results and the definite means of inducing clinically useful therapeutic angiogenesis remain elusive. More studies are required to gain further insights into the biology of angiogenesis and address pharmacological limitations of current approaches of angiogenic therapy. The authors hope and envisage that in the not-too-distant future, these investigative efforts will lead to important new strategies for treatment of myocardial ischemic syndromes. Means of non-invasive individualized pharmacological therapeutic neovascularization may be the next major advance in the treatment of ischaemic heart disease.

Evaluation of recombinant endostatin in the treatment of atherosclerotic plaques and neovascularization in rabbits

OBJECTIVE

Atherosclerotic plaques and neovascularization play an important role in the course of coronary atherosclerosis. This study evaluated the effect of recombinant endostatin on experimental atherosclerotic plaques and neovascularization in rabbits.

METHODS

Eighteen healthy male rabbits were divided into three groups: control group, atherosclerotic model group, and recombinant endostatin treated group. The atherosclerotic model was established via a high-cholesterol diet after balloon catheter injury. The subject weights, serum total cholesterol, creatine kinase-myocardial band fraction (CKMB), and matrix metalloproteinase-2 (MMP-2) were measured. Six weeks after treatment, the aortic roots were taken for pathological assay. The thickness ratio of the intima to media was measured by hematoxylin and eosin (HE) staining, and the number of neovessels was measured by immunohistochemistry via monoclonal antibody CD31 staining.

RESULTS

The weight, plasma total cholesterol, and CKMB were not significantly different between the atherosclerotic model group and the recombinant endostatin treated group, but much higher than those of the control group (P<0.05). The thickness ratio of the intima to media in the recombinant endostatin treated group was distinctly less than that in the atherosclerotic model group (P<0.05). The number of neovessels decreased dramatically (P<0.05) and the content of MMP-2 decreased slightly without statistical difference (P>0.05) in the recombinant endostatin treated group, compared to the atherosclerotic model group.

CONCLUSIONS

Recombinant endostatin is able to inhibit the growth of neovascularization in the atherosclerotic plaque and the development of plaque.

Myocardial expression of PDECGF is associated with extracellular matrix remodeling in experimental myocardial infarction in rats

Platelet-derived endothelial cell growth factor (PDECGF) is a potent angiogenic peptide with anti-apoptotic activity expressed widely in tumours. However, its expression in myocardial infarction (MI) is not yet established. This study aimed to assess the myocardial expression of PDECGF in rats after MI. Extracellular matrix (ECM) remodeling plays an important role in angiogenesis; hence, changes in the ECM components were investigated in the myocardium after MI, which was induced in rats by coronary artery ligation (CAL) and verified using biochemical markers and histopathology. Immunohistochemistry, RT-PCR, and activity assays identified the expression pattern of PDECGF on days 1, 2, 4, 8, 16, and 32 after CAL. The levels of TNF-alpha, MMP-2, collagen, and glycosaminoglycans in the ECM were assessed. Studies on immunohistochemistry, RT-PCR, and PDECGF activity demonstrated elevated levels of PDECGF expression from day 2 after CAL. Macrophages, endothelial cells, fibroblasts, and cardiomyocytes, especially at the border region of the lesion, showed an enhanced expression for PDECGF. Remodeling of the ECM was depicted by changes in the levels of TNF-alpha, MMP-2, collagen, and GAG. Hence, this study clearly indicated PDECGF as an important angiogenic molecule expressed during MI and the alterations in ECM components facilitated the process of angiogenesis.

Novel concepts in atherogenesis: angiogenesis and hypoxia in atherosclerosis

The clinical complications of atherosclerosis are caused by thrombus formation, which in turn results from rupture of an unstable atherosclerotic plaque. The formation of microvessels (angiogenesis) in an atherosclerotic plaque contributes to the development of plaques, increasing the risk of rupture. Microvessel content increases with human plaque progression and is likely stimulated by plaque hypoxia, reactive oxygen species and hypoxia-inducible factor (HIF) signalling. The presence of plaque hypoxia is primarily determined by plaque inflammation (increasing oxygen demand), while the contribution of plaque thickness (reducing oxygen supply) seems to be minor. Inflammation and hypoxia are almost interchangeable and both stimuli may initiate HIF-driven angiogenesis in atherosclerosis. Despite the scarcity of microvessels in animal models, atherogenesis is not limited in these models. This suggests that abundant plaque angiogenesis is not a requirement for atherogenesis and may be a physiological response to the pathophysiological state of the arterial wall. However, the destruction of the integrity of microvessel endothelium likely leads to intraplaque haemorrhage and plaques at increased risk for rupture. Although a causal relation between the compromised microvessel structure and atherogenesis or between angiogenic stimuli and plaque angiogenesis remains tentative, both plaque angiogenesis and plaque hypoxia represent novel targets for non-invasive imaging of plaques at risk for rupture, potentially permitting early diagnosis and/or risk prediction of patients with atherosclerosis in the near future.

C-reactive protein and coronary composition in patients with percutaneous revascularization

BACKGROUND

C-Reactive Protein (CRP) is considered a predictive factor for cardiovascular events and its serum levels have been shown to correlate with thin cap coronary plaques in sudden coronary death. Whether serum CRP levels are associated with in vivo atherothrombotic features is unclear. We thus analysed samples from coronary atherectomy specimens obtained during percutaneous coronary intervention.

MATERIALS AND METHODS

Patients with coronary artery disease undergoing directional atherectomy, distinguished by unstable versus stable coronary syndrome diagnosis, provided coronary specimens from culprit lesions. Assessment was conducted by means of conventional histology, morphometry and immunohistochemistry. Specific antibodies against erythrocyte-specific protein glycophorin A, endothelial and macrophage antigens were also used.

RESULTS

There were 51 patients with unstable coronary disease and 47 patients with stable angina. Serum CRP levels >/= 1 mg L(-1) were detected in 24/98 patients, and were significantly associated with hypercellularity, macrophage infiltrates, neoangiogenesis and intraplaque haemorrhage (all P < 0.05). Furthermore, coronary plaques from patients with unstable angina contained larger atheromas, more hypercellular plaques, with abundant macrophages, neoangiogenesis and intraplaque haemorrhages and lesser fibrous tissue (all P < 0.05).

CONCLUSIONS

We observed a positive correlation between increased serum CRP levels and typical pathological features of complex atherothrombotic coronary disease, confirming in vivo the mechanistic role of CRP in coronary atherothrombosis.

Induction of platelet derived-endothelial cell growth factor in the brain after ischemia

OBJECTIVES

Platelet derived-endothelial cell growth factor (PD-ECGF) is a highly potent angiogenic factor. Although angiogenesis plays an active role in pathophysiology of stroke, the expression pattern of this molecule in ischemic brain has not been investigated. In the present study, therefore, we investigated the change of PD-ECGF expression in the brain after ischemia.

METHODS

Using male Wistar rats, the right middle cerebral artery was occluded by a nylon thread for 90 minutes. The animals were decapitated 3 hours, 1, 4 and 10 days after the reperfusion, and frozen sections were prepared. We then performed immunohistochemistry for PD-ECGF and identified the cell phenotype which strongly expressed it by fluorescent double staining.

RESULTS

In the sham-operated brain, only small numbers of cells slightly expressed PD-ECGF. The number of positively stained cells increased at the peri-ischemic area from hour 3 of reperfusion. Not only small-sized cells but also large-sized cells became stained. The number of stained cells further increased, and peaked at day 4 for large-sized cells and at day 10 as to small-sized cells. Fluorescent double staining revealed that both large-sized and small-sized cells were neurons, indicating that neurons are the main source of PD-ECGF production in the ischemic brain.

DISCUSSION

PD-ECGF has a strong angiogenic property without vascular permeability increasing effect. This molecule may have a therapeutic potential for ischemic stroke treatment.

In vivo coronary plaque histology in patients with stable and acute coronary syndromes

OBJECTIVES

Aim of the study was to investigate whether maintained moderate statin treatment influence atheroma, macrophage content, neoangiogenesis and/or haemorrhage in coronary plaques from patients with non-fatal coronary syndromes.

METHODS

A total of 48 patients underwent elective directional coronary atherectomy on "de novo" culprit lesions; 16 patients had non-treated hypercholesterolemia, 16 patients received maintained moderate statin treatment for hypercholesterolemia and 16 had no lipoprotein abnormalities. These three patients groups were matched for age and clinical diagnosis of stable angina (SA) or unstable angina/non-ST-elevation myocardial infarction (UA/NSTEMI). Atherectomy specimens were stained with antibodies against macrophages, endothelial cells and glycophorin A. Results of histology and immunohistochemistry were morphometrically analyzed by using computer-assisted image analysis.

RESULTS

Atheroma and fibrous tissue, neoangiogenesis, macrophage and haemorrhage (i.e., glycophorin A) differed between the three groups (P<0.05). Statin-treated group showed significantly decreased atheroma (P=0.016), fibrous tissue (P=0.42), macrophage content (P=0.012), neoangiogenesis (P=0.00048) and haemorrhage (P=0.0092) as compared with the non-treated hyperlipidemic group.

CONCLUSIONS

The present findings show that maintained moderate statin treatment may contribute to plaque stabilization in non-fatal coronary syndromes by decreasing intraplaque neoangiogenesis and haemorrhage, lipid burden and macrophage content, and, on the other hand, by increasing plaque collagenization.

Plaque neovascularization and antiangiogenic therapy for atherosclerosis

The concept that neovascularization of the vessel wall may play a fundamental role in the pathophysiology of atherosclerosis was proposed more than a century ago. In recent years, supportive experimental evidence for this hypothesis (such as the finding that neointimal microvessels may increase delivery of cellular and soluble lesion components to the vessel wall) has been underscored by clinical studies associating plaque angiogenesis with more rapidly progressive high-grade disease. Attention has also focused on a possible role for microvessel-derived intraplaque hemorrhage in the development of acute lesion instability. The interest of clinicians in this phenomenon has been spurred by the potential to target vessel wall neovascularization with angiogenesis inhibitors, a therapeutic approach that has been associated with impressive reductions in plaque progression in animal models of vascular disease. The rationale for pursuing an "antiangiogenic" strategy in the treatment of patients with vascular disease, and a framework for further preclinical evaluation of such therapy, is presented here.

Targeting platelet-derived endothelial cell growth factor/thymidine phosphorylase for cancer therapy

Thymidine phosphorylase (TP) is a key enzyme in the pyrimidine nucleoside salvage pathway, but it also recognizes and inactivates various anti-cancer chemotherapeutic agents. Moreover, TP is identical to platelet-derived endothelial cell growth factor (PD-ECGF), an angiogenic factor with anti-apoptotic properties. Increased expression of PD-ECGF/TP is found in many tumor and stromal cells, and elevated TP levels are associated with aggressive disease and/or poor prognosis. Thus, progression and metastasis of TP-expressing tumors might be abrogated by TP inhibitors that are used as single agents or in combination with (TP-sensitive) nucleoside analogues. On the other hand, increased TP activity in tumors may be exploited for the tumor-specific activation of fluoropyrimidine prodrugs, such as capecitabine. This review will focus on the different biological activities of PD-ECGF/TP and their implications for cancer progression and treatment.

Intimal Neovascularisation is a Prominent Feature of Atherosclerotic Plaques in Diabetic Patients with Critical Limb Ischaemia

INTRODUCTION

Neovascularisation of atherosclerotic plaques correlates with increased plaque instability and subsequent risk of vascular complications. Diabetics have widespread atherosclerotic involvement of the arterial tree and a more aggressive form of the disease culminating in increased plaque instability. This results in a greater incidence of ischaemic sequelae than in non-diabetics. Previous studies have examined neovascularisation as a marker of plaque instability in both the carotid and coronary territories and revealed a greater degree in both symptomatic and diabetic patients. This is the first study to examine intimal neovascularisation in lower limb peripheral arterial disease.

METHODS

Arterial specimens were taken from 20 patients, ten of whom were type 2 diabetics, undergoing major lower limb amputation for unreconstructable critical ischaemia. Sections were stained with H&E for morphological assessment and inflammatory cell characterisation. Additional sections underwent immunohistochemical staining for CD31 and von-Willebrand Factor (vWF) and the number of intimal vessels per four 40x magnification fields assessed.

RESULTS

There was a more prominent inflammatory infiltrate in diabetic subjects compared to non-diabetic controls. Diabetic patients had a greater degree of intimal neovascularisation compared to controls with a median of 11.5 and 2.0 vessels per field respectively (P<0.05). Sub-group analysis revealed that diabetic patients medicating with HMG-CoA Reductase inhibitors (Statins) had a greater degree of neovascularisation compared to those not taking this class of medication.

CONCLUSION

Diabetic patients with critical limb ischaemia requiring amputation demonstrate a greater degree of plaque intimal neovascularisation and inflammatory infiltrate compared to their non-diabetic counterparts. This may explain the greater plaque instability and subsequent cardiovascular complications seen in these patients.

Efficacy of peroxisome proliferative activated receptor (PPAR)-alpha ligands, fenofibrate, on intimal hyperplasia and constrictive remodeling after coronary angioplasty in porcine models

Constrictive remodeling and intimal hyperplasia play a prominent role in restenosis after angioplasty. It has been reported that the severity of constrictive remodeling and intimal hyperplasia correlate with adventitial angiogenesis and inflammation. Experimental evidence indicates that inflammation participates in angiogenesis, and therefore inhibition of inflammation may impair neovascularization. We tested whether fenofibrate, peroxisome proliferative activated receptors (PPAR)-alpha specific ligand, inhibits the early inflammation, adventitial angiogenesis, constrictive remodeling and intimal hyperplasia after angioplasty using porcine coronary arteries. Fenofibrate was tested in vivo, in 30 coronary arteries of 10 pigs (1g/day, orally) and was compared to placebo. Quantitative intravascular ultrasound and histopathologic assessment showed that fenofibrate increased lumen (6.28 mm(2) versus 5.15 mm(2)), vessel area (7.34 mm(2) versus 6.69 mm(2)) and inhibited constrictive remodeling. Inflammatory cell infiltration was evaluated with scanning electron microscopy 3 days after angioplasty and was significantly decreased in the treated vessels compared to control. Adventitial angiogenesis 3 days after angioplasty was significantly reduced in the injured vessels derived from the fenofibrate treated group compared to placebo. In conclusion, pharmacological activation of PPAR-alpha inhibited constrictive remodeling and neointimal hyperplasia after angioplasty through inhibition of inflammation and adventitial neovascularization.

Apoptosis and angiogenesis are induced in the unstable coronary atherosclerotic plaque

OBJECTIVE

Apoptosis and angiogenesis may be involved in the pathogenesis of atherosclerosis and plaque destabilization. In this study, we investigated if apoptosis and angiogenesis were induced in the unstable human coronary atherosclerotic plaque compared to stable atherosclerotic plaque.

METHODS

Atherosclerotic plaques from patients with stable (n = 9) and unstable angina (n = 13) were obtained by directional coronary atherectomy performed during percutaneous transluminal coronary angioplasty. Apoptosis was detected by terminal deoxynucleotidyl transferase end labelling (TUNEL), as well as by immunostaining for caspase 3, Bax and Bcl-2. Neovascularization was determined by immunostaining for the endothelial cell-specific CD31, vascular endothelial growth factor (VEGF-A), angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), hypoxia inducible factor-1alpha (HIF-alpha), and the sections were quantified blindly.

RESULTS

The apoptotic nuclei were more frequently found in the unstable coronary atherosclerotic plaques. When the number of apoptotic cells was quantified, an increased apoptotic index was found in the unstable plaques (P = 0.04). The positive staining for caspase-3 was increased in the unstable plaques (P = 0.0008), while no difference in either Bax or Bcl-2 was found between groups. Neovascularization, as evidenced by lumens surrounded by a CD31 positive endothelial layer, was more frequently present in the plaques from patients with unstable angina (P = 0.04). The number of cells with positive staining for VEGF-A was increased in unstable plaques (P = 0.005). No difference of Ang I, Ang II, HIF1-alpha was found between groups.

CONCLUSIONS

In unstable human coronary plaques, apoptosis probably involving caspase 3 was found. The plaques had an increased neovascularization, probably induced by VEGF-A. These factors may contribute to explaining plaque destabilization and intraplaque haemorrhage.

The different apoptotic potential of the p53 codon 72 alleles increases with age and modulates in vivo ischaemia-induced cell death

A common arginine to proline polymorphism is harboured at codon 72 of the human p53 gene. In this investigation, we found that fibroblasts and lymphocytes isolated from arginine allele homozygote centenarians and sexagenarians (Arg+) undergo an oxidative-stress-induced apoptosis at a higher extent than cells obtained from proline allele carriers (Pro+). At variance, the difference in apoptosis susceptibility between Arg+ and Pro+ is not significant when cells from 30-year-old people are studied. Further, we found that Arg+ and Pro+ cells from centenarians differ in the constitutive levels of p53 protein and p53/MDM2 complex, as well as in the levels of oxidative stress-induced p53/Bcl-xL complex and mitochondria-localised p53. Consistently, all these differences are less evident in cells from 30-year-old people. Finally, we investigated the in vivo functional relevance of the p53 codon 72 genotype in a group of old patients (66-99 years of age) affected by acute myocardial ischaemia, a clinical condition in which in vivo cell death occurs. We found that Arg+ patients show increased levels of Troponin I and CK-MB, two serum markers that correlate with the extent of the ischaemic damage in comparison to Pro+ patients. In conclusion, these data suggest that p53 codon 72 polymorphism contributes to a genetically determined variability in apoptotic susceptibility among old people, which has a potentially relevant role in the context of an age-related pathologic condition, such as myocardial ischaemia.

Crystal Structure of Human Thymidine Phosphorylase in Complex with a Small Molecule Inhibitor

Human thymidine phosphorylase (HTP), also known as platelet-derived endothelial cell growth factor (PD-ECGF), is overexpressed in certain solid tumors where it is linked to poor prognosis. HTP expression is utilized for certain chemotherapeutic strategies and is also thought to play a role in tumor angiogenesis. We determined the structure of HTP bound to the small molecule inhibitor 5-chloro-6-[1-(2-iminopyrrolidinyl) methyl] uracil hydrochloride (TPI). The inhibitor appears to mimic the substrate transition state, which may help explain the potency of this inhibitor and the catalytic mechanism of pyrimidine nucleotide phosphorylases (PYNPs). Further, we have confirmed the validity of the HTP structure as a template for structure-based drug design by predicting binding affinities for TPI and other known HTP inhibitors using in silico docking techniques. This work provides the first structural insight into the binding mode of any inhibitor to this important drug target and forms the basis for designing novel inhibitors for use in anticancer therapy.

Identification of new genes differentially expressed in coronary artery disease by expression profiling

Genetic factors increase the risk to coronary artery disease (CAD). To date, a limited number of genes that potentially contribute to development of CAD have been identified. In this study, we have performed large-scale gene expression analysis of approximately 12,000 human genes in nine severely atherosclerotic and six nonatherosclerotic human coronary arteries using oligonucleotide microarrays. Fifty-six genes showed differential expression in atherosclerotic coronary artery tissues; expression of 55 genes was increased in atherosclerotic coronary arteries, whereas only one gene, GST, encoding a reducing agent, showed downregulated expression. The expression data of selected genes were validated by quantitative RT-PCR analysis as well as immunostaining. The associations of 49 genes with CAD appear to be novel, and they include genes encoding ICAM-2, PIM-2, ECGF1, fusin, B cell activator (BL34, GOS8), Rho GTPase activating protein-4, retinoic acid receptor responder, beta2-arrestin, membrane aminopeptidase, cathepsins K and H, MIR-7, TNF-alpha-induced protein 2 (B94), and flavocytochrome 558. In conclusion, we have identified 56 genes whose expression is associated with CAD, and 49 of them may represent new genes linked to CAD.

Thymidine phosphorylase and vascular endothelial growth factor in patients with Stage I lung adenocarcinoma

BACKGROUND

Thymidine phosphorylase (TP) has chemotactic activity in endothelial cells in vitro and angiogenic activity in vivo. However, the clinical significance of TP and cooperative roles of TP with other angiogenic factors have remained unclear in nonsmall cell lung carcinoma (NSCLC).

METHODS

The authors stained for TP, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) in 132 tumors from patients with Stage I NSCLC. They compared TP, VEGF, and bFGF expression levels with microvessel counts (MVCs), macrophage counts, mast cell counts, and clinical outcomes of patients with Stage I NSCLC.

RESULTS

In adenocarcinoma samples, only stromal cell-TP expression and tumor cell-VEGF expression were associated with MVCs and mast cell counts but not with macrophage counts. In squamous cell carcinoma samples, there were no significant associations of the expression of any examined angiogenic factors with MVCs, mast cell counts, or macrophage counts. More importantly, only among patients with Stage I adenocarcinoma of the lung did patients in the stromal cell-TP positive tumor group and in the tumor cell-VEGF positive tumor group have a significantly worse prognosis compared with patients in the stromal cell-TP negative tumor group and in the tumor cell VEGF negative group, respectively. In addition, among patients with Stage I adenocarcinoma, patients in the stromal cell-TP positive and tumor cell-VEGF positive tumor group had a significantly worse prognosis among the four groups.

CONCLUSIONS

TP induction in tumoral stroma, but not in tumor cells, and tumor cell-VEGF induction may promote angiogenesis cooperatively in adenocarcinoma of the lung. Stromal cell-TP expression and tumor cell-VEGF expression may be important prognostic factors in adenocarcinoma of the lung, and stromal cell-TP expression may be a marker of active remodeling stroma in adenocarcinoma of the lung.

Anti-angiogenic activity of a novel multi-substrate analogue inhibitor of thymidine phosphorylase

7-Deazaxanthine (7-DX) was recently identified as the first purine derivative with pronounced inhibitory activity against Escherichia coli thymidine phosphorylase (TP) and angiogenesis. In order to "freeze" the enzyme in an open, inactive conformation, a novel multi-substrate analogue inhibitor of TP, containing an alkyl phosphonate moiety covalently linked to 7-DX, was synthesized. The prototype compound TP65 (9-(8-phosphonooctyl)-7-deazaxanthine) (at 250 microM) completely inhibited TP-induced formation of microvascular sprouts from endothelial cell aggregates in a three-dimensional fibrin gel. In the chick chorioallantoic membrane assay, TP caused a dose-dependent stimulation of angiogenesis, which was completely inhibited by 250 nmol TP65. This dose proved to be non-toxic for the developing chick embryo. TP65 thus emerges as a potent and specific inhibitor of TP and TP-induced angiogenesis, which opens new perspectives for multi-substrate analogue inhibitors of TP as potential anti-cancer agents and as inhibitors of angiogenesis and of diseases with enhanced expression of TP.

Age-associated neovasculopathy with recurrent bleeding

We hypothesize the existence of an age-associated neovasculopathy with recurrent bleeding. It could be the result of age-related defects in the regulation of the angiogenetic process creating pathologic small vessels with a bleeding tendency. Conditions like subdural hematoma, ocular angiopathies, intestinal angiodysplasia, coronary atherosclerotic plaques and others, may be the clinical expression of such a neovasculopathy.

Intracoronary basic fibroblast growth factor (FGF-2) in patients with severe ischemic heart disease: results of a phase I open-label dose escalation study

OBJECTIVES

Evaluate the safety, tolerability and preliminary efficacy of intracoronary (IC) basic fibroblast growth factor (bFGF, FGF-2).

BACKGROUND

FGF-2 is a heparin-binding growth factor capable of inducing functionally significant angiogenesis in animal models of myocardial ischemia.

METHODS

Phase I, open-label dose-escalation study of FGF-2 administered as a single 20-min infusion in patients with ischemic heart disease not amenable to treatment with CABG or PTCA.

RESULTS

Fifty-two patients enrolled in this study received IC FGF-2 (0.33 to 48 microg/kg). Hypotension was dose-dependent and dose-limiting, with 36 microg/kg being the maximally tolerated dose. Four patients died and four patients had non-Q-wave myocardial infarctions. Laboratory parameters and retinal examinations showed mild and mainly transient changes during the 6-month follow-up. There was an improvement in quality of life as assessed by Seattle Angina Questionnaire and improvement in exercise tolerance as assessed by treadmill exercise testing (510+/-24 s at baseline, 561+/-26 s at day 29 [p = 0.023], 609+/-26 s at day 57 (p < 0.001), and 633+/-24 s at day 180 (p < 0.001), overall p < 0.001). Magnetic resonance (MR) imaging showed increased regional wall thickening (baseline: 34+/-1.7%, day 29: 38.7+/-1.9% [p = 0.006], day 57: 41.4+/-1.9% [p < 0.001], and day 180: 42.0+/-2.3% [p < 0.001], overall p = 0.001) and a reduction in the extent of the ischemic area at all time points compared with baseline.

CONCLUSIONS

Intracoronary administration of rFGF-2 appears safe and is well tolerated over a 100-fold dose range (0.33 to 0.36 microk/kg). Preliminary evidence of efficacy is tempered by the open-label uncontrolled design of the study.