Distinct patterns of expression of fibroblast growth factors and their receptors in human atheroma and nonatherosclerotic arteries. Association of acidic FGF with plaque microvessels and macrophages

Vascular endothelium and atherosclerosis

Atherosclerosis depends critically on altered behavior of the intrinsic cells of the artery wall, the endothelial cells and smooth muscle cells, and inflammatory leukocytes that join them in the arterial intima during the atherogenic process. The homeostatic properties of the normal endothelium contribute importantly to maintenance of aspects of arterial health including the appropriate regulation of blood flow, a basal anti-inflammatory state, promotion of fibrinolysis while opposing blood coagulation, and control of the balance of cellular proliferation and death. Alterations in these endothelial homeostatic mechanisms contribute critically to atherogenesis, the progression of this disease, and ist complications. Recent advances have highlighted novel molecular mechanisms that regulate the atheroprotective functions of normal endothelial cells that go awry during atherogenesis. Therapeutic strategies that alter the course of atherosclerosis may act by combating endothelial dysfunction.

Monocyte recruitment and foam cell formation in atherosclerosis

Atherosclerosis is a chronic immune-inflammatory disease in which the interactions of monocytes with activated endothelium are crucial events leading to atherosclerotic alteration of the arterial intima. In early atherosclerosis, monocytes migrate into the subendothelial layer of the intima where they differentiate into macrophages or dendritic cells. In the subendothelial space enriched with atherogenic lipoproteins, most macrophages transform into foam cells. Foam cells aggregate to form the atheromatous core and as this process progresses, the atheromatous centres of plaques become necrotic, consisting of lipids, cholesterol crystals and cell debris. This review highlights some aspects of monocyte recruitment and foam cell formation in atherosclerosis.

Biostimulation of dermal fibroblast by sublethal Q-switched Nd:YAG 532nm laser: Collagen remodeling and pigmentation

The application of medical lasers in treating pigmented lesions has rapidly developed over the past decade. In both clinical and cosmetic application, melanin is targeted in pigmented areas and destroyed by the mechanism of selective photothermolysis. When laser radiation passes through superficial pigmented tissue, energy will be further reduced by dermal collagen scattering and absorption. Non-pigmented dermal fibroblasts will be exposed to co-incidental laser irradiation at lower energy levels. Biostimulation of dermal fibroblasts by low energy laser is reported in this paper. The Q-switched frequency doubled Nd:YAG 532nm laser used in clinical laser therapy was used in this study. Sublethal laser fluence was determined at 0.8J/cm(2) and used to stimulate normal human fibroblasts in monolayer culture. The results showed that there was no significant difference in collagen synthesis between the stimulated fibroblasts and controls. However, significant delay in collagen remodeling activity was demonstrated in the irradiated group by measuring fibroblast populated collagen lattice (FPCL) contraction. The stimulation of SCF, HGF and b-FGF gene expression was determined by RT-PCR analysis and demonstrated to vary between cases. Two out of six cell lineages that showed stronger responses to laser stimulation on SCF, HGF and b-FGF gene expressions were used to prepare conditioned media. The conditioned media from irradiated groups showed significant increase in SCF and b-FGF content and stimulated SK-mel-3 melanoma cells to synthesize more melanin in vitro. These results suggest that sublethal laser stimulation of fibroblasts may cause post-laser hyperpigmentation through production of melanogenic stimulatory cytokines. The degree of stimulation of SCF, HGF and b-FGF production varied between individual cell lineages, which may reflect the true variation of post-laser hyperpigmentation in clinical practice.

A study of Q-switched Nd:YAG laser irradiation and paracrine function in human skin cells

BACKGROUND AND OBJECTIVES

This preliminary laboratory-based study looks at the paracrine release from human skin cells subject to sublethal Q-switched Nd:YAG 532 nm laser irradiation.

STUDY DESIGN/MATERIALS AND METHODS

Human dermal fibroblast and keratinocyte cultures were exposed to sublethal energy using the Nd:YAG 532 nm laser. Altered gene expression was then screened using RT-PCR for a range of paracrine factors known to affect melanogenesis, basic fibroblast growth factor (b-FGF), hepatocyte growth factor (HGF), stem cell factor (SCF), melanocyte stimulating hormone (MSH), endothelin-1 (ET-1), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-alpha) and protease-activated receptor-2 (PAR-2). Enzyme-linked immunosorbent assay (ELISA) was used to confirm protein production. Conditioned medium was used to assess altered melanogenesis in a melanoma cell line.

RESULTS

Fibroblasts exposed to sublethal radiation showed upregulation of b-FGF, HGF and SCF. This contrasts with keratinocytes which showed upregulation of IL-6. Elevated protein levels of b-FGF and SCF were confirmed by ELISA assay. Conditioned fibroblast medium was shown to stimulate melanogenesis in a melanoma cell line.

CONCLUSIONS

This preliminary laboratory study reports, for the first time, specific gene upregulation using the Q-switched Nd:YAG 532 nm laser.

Fibroblast growth factor-10 and fibroblast growth factor receptors 1-4: expression and peptide localization in human decidua and placenta

The development of the chorionic villous tree into a complex and organized ramified tubular network can be termed branching morphogenesis. Studying the molecular mechanisms involved in this process may contribute to the understanding of pregnancy complications such as preeclampsia. We hypothesized that fibroblast growth factor-10 (FGF-10) and fibroblast growth factor receptors 1-4 (FGFR 1-4) are expressed in human decidual and placental tissues. We analyzed the expression of FGF-10 and FGFRs 1-4 in 1st, 2nd and 3rd trimester placentas, as well as in decidua. RT-PCR and immunohistochemistry were employed to study mRNA and protein expression. FGF-10 was expressed by decidual cells and by cytotrophoblasts of the cytotrophoblast columns during all three trimesters. FGFR 1-4 were expressed in the placenta but not in the decidua. Placental expression of FGFRs was temporally regulated: In 1st trimester placentas, FGFR 1-4 were expressed by Hofbauer cells, FGFR-1 and FGFR-4 were expressed in cytotrophoblast columns, and the latter was also expressed by syncytiotrophoblasts. Similar expression was seen in 2nd trimester placentas with additional expression of FGFR-1 in blood vessel walls. The expression of FGFR-1 and FGFR-4 in the 3rd trimester was comparable to that seen in the 2nd trimester. The expression of FGF-10, FGFR-1 and FGFR-4 in the maternal-fetal interphase suggests their role in decidual-trophoblast interaction. The abundance of FGFR expression in Hofbauer cells implies that mesenchymal-trophoblast interaction is important for regulation of villous development.

The human FGF2 level is influenced by genetic predisposition

BACKGROUND

The fibroblast growth factor 2 (FGF2) is involved in various processes possibly leading to the development of complex diseases such as atherosclerosis. In recent studies, its cardioprotective properties, due to its ability to stimulate the proliferation of collateral vessels, could be shown.

STUDY DESIGN

In this clinical study, the relation between clinical risk markers, a genomic variant of FGF2, namely the c.223C>T polymorphism, and the in vivo FGF2 expression was evaluated. Therefore, 198 clinically well-characterized probands, all of Caucasian origin, were included. The FGF2 mRNA level was determined in monocytes by competitive RT-PCR, whereas the plasma level of circulating FGF2 protein was analysed by ELISA. By considering the angiographically proven stenotic state of the patient, a significant increase in FGF2 mRNA, but not in protein level, could be shown for patients with significant stenosis. Apart from this, no influence on FGF2 expression was found in the case of all of the clinical and biochemical markers investigated. However, in the case of the c.223C>T polymorphism, a significant increase in the individual FGF2 mRNA and protein level in CC-carriers was shown. In multivariate analysis, this relation was independent of all other risk markers investigated.

CONCLUSIONS

Our results suggest that an increase in FGF2 mRNA expression, related to coronary atherosclerosis, may be necessary for the maintenance of the individual FGF2 plasma level. Since the individual FGF2 mRNA and protein level are, to a large extent, triggered off by genetic background, the FGF2 expression cannot be referred to as an independent clinical marker for CAD.

Proliferation of Neointimal Smooth Muscle Cells after Arterial Injury

The growth factor signaling mechanisms responsible for neointimal smooth muscle cell (SMC) proliferation and accumulation, a characteristic feature of many vascular pathologies that can lead to restenosis after angioplasty, remain to be identified. Here, we examined the contribution of fibroblast growth factor receptors (FGFRs) 2 and 3 as well as novel fibroblast growth factors (FGFs) to such proliferation. Balloon catheter injury to the rat carotid artery stimulated the expression of two distinctly spliced FGFR-2 isoforms, differing only by the presence or absence of the acidic box, and two distinctly spliced FGFR-3 isoforms containing the acidic box and differing only by the presence of either the IIIb or IIIc exon. Post-injury arterial administration of recombinant adenoviruses expressing dominant negative mutant forms of these FGFRs were used to assess the roles of the endogenous FGFR isoforms in neointimal SMC proliferation. Dominant negative FGFR-2 containing the acidic box inhibited such proliferation by 40%, whereas the dominant negative FGFR-3 forms had little effect. Expression of FGF-9, known to be capable of binding to all four neointimal FGFR-2/-3 isoforms, was abundant within the neointima. FGF-9 markedly stimulated both the proliferation of neointimal SMCs and the activation of extracellular signal-related kinases 1/2, effects which were abrogated by the administration of antisense FGF-9 oligonucleotides to injured arteries and the expression of the dominant negative FGFR-2 adenovirus in cultured neointimal SMCs. These studies demonstrate that, although multiple FGFRs are induced in neointimal SMCs following arterial injury, specific interactions between distinctly spliced FGFR-2 isoforms and FGF-9 contribute to the proliferation of these SMCs.

Loss of collagen XVIII enhances neovascularization and vascular permeability in atherosclerosis

BACKGROUND

Plaque neovascularization is thought to promote atherosclerosis; however, the mechanisms of its regulation are not understood. Collagen XVIII and its proteolytically released endostatin fragment are abundant proteoglycans in vascular basement membranes and the walls of major blood vessels. We hypothesized that collagen XVIII in the aortic wall inhibits the proliferation and intimal extension of vasa vasorum.

METHODS AND RESULTS

To test our hypothesis, we bred collagen XVIII-knockout (Col18a1(-/-)) mice into the atherosclerosis-prone apolipoprotein E-deficient (ApoE(-/-)) strain. After 6 months on a cholesterol diet, aortas from ApoE(-/-);Col18a1(-/-) and ApoE(-/-);Col18a1(+/-) heterozygote mice showed increased atheroma coverage and enhanced lipid accumulation compared with wild-type littermates. We observed more extensive vasa vasorum and intimal neovascularization in knockout but not heterozygote aortas. Endothelial cells sprouting from Col18a1(-/-) aortas were increased compared with heterozygote and wild-type aortas. In contrast, vascular permeability of large and small blood vessels was enhanced with even heterozygous loss of collagen XVIII but was not suppressed by increasing serum endostatin to wild-type levels.

CONCLUSIONS

Our results identify a previously unrecognized function for collagen XVIII that maintains vascular permeability. Loss of this basement membrane proteoglycan enhances angiogenesis and vascular permeability during atherosclerosis by distinct gene-dose-dependent mechanisms.

Mast cells in neovascularized human coronary plaques store and secrete basic fibroblast growth factor, a potent angiogenic mediator

OBJECTIVE

Intraplaque neovascularization and hemorrhage may facilitate plaque progression. We studied expression of basic fibroblast growth factor (bFGF), a potent angiogenic mediator, by mast cells (MCs) in human coronary plaques with increasing degrees of atherosclerosis.

METHODS AND RESULTS

Normal and atherosclerotic coronary segments were collected from 30 autopsied subjects. Immunohistochemical methods were used to detect MCs, bFGF, and microvessels. Both adventitial and intimal MCs showed intracytoplasmic granular staining for bFGF, and bFGF-positive extracellular granules were observed close to the MCs. Increased numbers of bFGF-positive MCs were detected in neovascularized areas of plaques, and there was a positive correlation between numbers of bFGF-positive MCs and microvessels in both the intima and adventitia. In plaques, the highly neovascularized areas contained increased numbers of bFGF-positive MCs compared with the adjacent nonvascularized areas, where only few MCs were present. Importantly, the proportion of intimal MCs expressing bFGF increased with increasing severity of atherosclerosis.

CONCLUSIONS

The present work reveals a novel source of bFGF in human coronary arteries, the intimal and adventitial MCs. The association of bFGF-positive MCs with microvessels and with the severity of atherosclerosis suggests that coronary MCs, by releasing bFGF, may play a role in angiogenesis and progression of coronary plaques.

Signaling, internalization, and intracellular activity of fibroblast growth factor

The fibroblast growth factor (FGF) family contains 23 members in mammals including its prototype members FGF-1 and FGF-2. FGFs have been implicated in regulation of many key cellular responses involved in developmental and physiological processes. These includes proliferation, differentiation, migration, apoptosis, angiogenesis, and wound healing. FGFs bind to five related, specific cell surface receptors (FGFRs). Four of these have intrinsic tyrosine kinase activity. Dimerization of the receptor is a prerequisite for receptor transphosphorylation and activation of downstream signaling molecules. All members of the FGF family have a high affinity for heparin and for cell surface heparan sulfate proteoglycans, which participate in formation of stable and active FGF-FGFR complexes. FGF-mediated signaling is an evolutionarily conserved signaling module operative in invertebrates and vertebrates. It seems that some members of the family have a dual mode of action. FGF-1, FGF-2, FGF-3, and FGF-11-14 have been found intranuclearly as endogenous proteins. Exogenous FGF-1 and FGF-2 are internalized by receptor-mediated endocytosis, in a clathrin-dependent and -independent way. Internalized FGF-1 and FGF-2 are able to cross cellular membranes to reach the cytosol and the nuclear compartment. The role of FGF internalization and the intracellular activity of some FGFs are discussed in the context of the known signaling induced by FGF.

Peroxynitrite modulates acidic fibroblast growth factor (FGF-1) activity

To establish peroxynitrite (ONOO(-)) as a mediator of acidic fibroblast growth factor (FGF-1) function, preparations of recombinant human FGF-1 were treated with the pro-oxidant in vitro and identified amino acid modifications were correlated with biologic activity. The sequence of FGF-1 amino acid modifications induced by increasing concentrations of ONOO(-) was from cysteine oxidation to dityrosine formation, and to tyrosine/tryptophan nitration. Low steady-state ONOO(-) concentrations (10-50 microM) induced formation of dityrosine, which involved less than 0.1% of the total tyrosines. Treatment of FGF-1 with ONOO(-) induced a dose-dependent (10-50 microM) loss of sulfhydryl groups that correlated with formation of reducible (dithiothreitol, arsenite) FGF-1 aggregates containing 50% latent biologic activity. Treatment with 0.1-0.5mM ONOO(-) induced increasing formation of non-reducible, inactivated FGF-1 structures. Combination of real-time spectral analysis and electrospray mass spectroscopy revealed that six residues (Y29, Y69, Y108, Y111, Y139, and W121) were nitrated by ONOO(-). ONOO(-) treatment (0.1mM) of an active FGF-1 mutant (cysteines converted to serines) induced dose-dependent, non-reversible inhibition of biologic activity that correlated with nitration of Y108 and Y111, both of which reside within a conserved domain encompassing the putative FGF-1 receptor binding site. Collectively, these observations predict a role for low levels of ONOO(-) during secretion of FGF-1 as an extracellular complex containing latent biologic activity. High steady-state levels of ONOO(-) may induce extensive cysteine oxidation, critical tyrosine nitration, and non-reversible inactivation of FGF-1, a potential inhibitory feedback mechanism restoring cellular homeostatis during the resolution of inflammation and repair.

Low density lipoproteins interact with acidic fibroblast growth factor and modify its function

OBJECTIVE

Oxidized LDL (oxLDL) was shown to trigger the release of acidic fibroblast growth factor (FGF-1). Because these components are likely to be present simultaneously in the atherosclerotic milieu, we investigated whether oxLDL interacts with FGF-1 and whether this interaction affects FGF-1 functioning.

METHODS AND RESULTS

Using molecular sieve and electrophoretic mobility shift assays, we found that FGF-1 forms a complex with oxLDL in vitro, in contrast to its low affinity for nonatherogenic, native LDL. The FGF-1/oxLDL complex had a dramatically decreased ability to bind heparin and was nonmitogenic on cultured smooth muscle cells. In human atherosclerotic lesions, the highest FGF-1 immunoreactivity was found in macrophages. With respect to oxLDL accumulation, 2 patterns were distinguished: (1) moderate, intracellular in matrix-rich regions containing viable cells and (2) massive, both cell-associated and extracellular oxLDL deposits in foam cell-rich regions with necrotic areas. The proliferating cell nuclear antigen readings for proliferating cells reflected that the mitogenic activity of FGF-1 was confined to the regions where oxLDL was strictly intracellular and was inhibited in the regions with extracellular oxLDL deposition.

CONCLUSIONS

oxLDL, besides being a bulky component of the atherosclerotic lesion, possibly manifests its pathogenicity by complexing FGF-1 and inhibiting its growth-promoting function during atherogenesis.

Involvement of the fibroblast growth factor system in adaptive and chemokine-induced arteriogenesis

Fibroblast growth factors (FGFs) have been applied in a variety of therapeutic and experimental studies to improve collateral blood flow. However, the pathophysiological role and the temporospatial expression of the FGFs and their receptors during arteriogenesis have never been elucidated in vivo. Here, we report that collateral artery growth in its early phase is associated with an increased expression of FGF receptor-1 (FGFR-1) and syndecan-4 on mRNA and protein levels as well as with an increased kinase activity of FGFR-1 in a rabbit model of arteriogenesis. However, the mRNA levels of FGF-1 and -2 remained constant. Our data suggest that these growth factors are supplied by endothelial attracted monocytes that, in turn, produce and deliver the FGFs to growing collateral arteries. Monocyte chemoattractant protein-1-stimulated arteriogenesis was strongly reduced in rabbits by application of the FGF inhibitor polyanetholesulfonic acid, indicating that the monocyte-related arteriogenesis (as well as the unstimulated adaptation proper) is promoted by FGFs. In summary, this study shows that arteriogenesis is associated with an increased expression of the FGFRs at the site of the vessel, whereas the growth-promoting ligands are supplied by monocytes in a paracrine way.

Molecular biology and gene transfer in atherosclerosis in the stenting era

Atherosclerosis is the major cause of death in the developed world. Understanding the pathogenesis of atherosclerosis has been a major challenge to cardiovascular research over the past several decades. During this period a number of advances in various scientific disciplines has increased our understanding of this disease. These include improved understanding of the structural and functional components of normal vessel wall and more recently the use of cell biology and molecular biology techniques to elucidate the pathogenesis of atherosclerosis. None of these advances has been more dramatic nor has potentially more far reaching consequences as the application of molecular biology and gene technology to the practice of cardiovascular medicine. These developments have already opened new and exciting areas of vascular research and may in the future provide for earlier identification of genetic predisposition to atherosclerosis, strategic planning of preventive therapy and more tailored pharmacologic approaches for established disease.

An association between aortic pulse wave velocity, blood pressure and chronic inflammation in ESRD patients on peritoneal dialysis

Increased aortic pulse wave velocity (AoPWV) has been identified as a risk factor for cardiovascular morbidity in the general population and in patients on dialysis. Most of the studies in ESRD patients refer to subjects on hemodialysis. Influence of the inflammatory process on aortic stiffening remains largely unknown. The aim of the present study was to evaluate potential relationships between AoPWV and blood pressure, basic anthropometric parameters, selected growth factors and markers of the inflammatory process in ESRD patients treated with peritoneal dialysis. The study population consisted of 43 patients (19 F, 24 M) with a mean age of 50.6 +/- 13.4 years on PD for a mean period of 21.9 +/- 20.7 months. AoPWV was measured using two pressure transducers placed on the carotid and femoral arteries and connected to an automatic processor (Complion Colson AS, Paris, France). Serum levels of Tumor Necrosis Factor alpha (TNFalpha), interleukin 6 (IL-6) and plasma basic Fibroblast Growth Factor (bFGF) were measured with ELISA; C-reactive protein and fibrinogen with nephelometry. Serum lipid profile was also assessed. Blood pressure was measured in an outpatient department under standardized conditions. Mean aortic pulse wave velocity in the study population was 10.7 +/- 2.1 m/s. No difference in AoPWV was found between men and women. AoPWV correlated significantly with age (R = 0.41; p < 0.01) but not with time on dialysis. Positive relationship between AoPWV and body weight and BMI was shown (R = 0.31; p < 0.05 and R = 0.35; p < 0.05, respectively). AoPWV correlated significantly with systolic blood pressure (SBP), mean arterial pressure (MAP) and pulse pressure (PP) (R = 0.46, p < 0.005, R = 0.46, p < 0.005 and R = 0.43, p < 0.01, respectively). AoPWV correlated with serum IL-6 and plasma bFGF (R = 0.32, p < 0.05 and R = 0.4, p < 0.01; respectively). The correlation with serum CRP was borderline significant (p < 0.53). In multiple regression analysis age (beta 0.38; p < 0.005), plasma bFGF level (beta 0.3; p < 0.05), and systolic blood pressure (beta 0.29; p < 0.05) were independently associated with pulse wave velocity. Our results suggest that AoPWV values in patients on PD are associated with factors similar to those encountered in the general population. We suggest that increased aortic stiffening may also be related to the chronic inflammatory process in PD patients.

Alternatively spliced FGFR-1 isoform signaling differentially modulates endothelial cell responses to peroxynitrite

Mounting experimental evidence has suggested that the trophic environment of cells in culture is an important determinant of their vulnerability to the cytotoxic effects of reactive oxidants such as peroxynitrite (ONOO(-)). However, acidic fibroblast growth factor (FGF-1)-induced signaling renders some cells more sensitive and others resistant to the cytotoxic effects of ONOO(-). To determine whether alternatively spliced fibroblast growth factor receptor (FGFR-1) isoforms are responsible for this differential response, we have stably transfected FGFR-negative rat brain-derived resistant vessel endothelial cells (RVEC) with human cDNA sequences encoding either FGFR-1 alpha or FGFR-1 beta. FGF-1 treatment of RVEC(R-1 alpha) transfectants enhanced ONOO(-)-mediated cell death in a manner dependent upon FGFR-1 tyrosine kinase, MEK/Erk 1/2 kinase, and p38 MAP kinase activities and independent of Src-family kinase (SFK) activity. FGF-1 treatment of RVEC(R-1 beta) transfectants inhibited the cytotoxic effects of ONOO(-) in a manner dependent upon FGFR-1 tyrosine kinase, MEK/Erk 1/2 kinase, and SFK activities and independent of p38 MAP kinase activity. FGF-1-induced preactivation of both FGFR-1 tyrosine and Erk 1/2 kinases was detected in both RVEC(R-1 alpha) and RVEC(R-1 beta) transfectants. FGF-1-induced preactivation of p38 MAPK was restricted to RVEC(R-1 alpha) transfectants, whereas, ligand-induced preactivation of SFK was limited to RVEC(R-1 beta) transfectants. Collectively, these results both reemphasize the role of extracellular trophic factors and their receptor-mediated signaling pathways during cellular responses to oxidant stress and provide a first indication that the alternatively spliced FGFR-1 isoforms induce differential signal transduction pathways.

An association between coronary artery calcification score, lipid profile, and selected markers of chronic inflammation in ESRD patients treated with peritoneal dialysis

BACKGROUND

Chronic uremia is considered a proinflammatory state associated with high cardiovascular morbidity and mortality. The aim of the present study is to evaluate the potential relationship between the prevalence of coronary artery calcification (CAC) and selected factors that may be involved in the process of atherogenesis (lipid profile, acute-phase reactants, growth factors, and cytokines).

METHODS

The study group consisted of 43 patients (19 women, 24 men) with a mean age of 50.6 +/- 13.4 years treated with peritoneal dialysis (PD) for a median period of 15 months (range, 2 to 96 months). Only patients with sinus rhythm were included. CAC score (CaSc) was measured using multirow spiral computed tomography (MSCT). As parameters of lipid profile, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides were assayed. C-reactive protein (CRP) and fibrinogen represented the level of acute-phase activation. Proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor-alpha [TNF-alpha]), leptin, and basic fibroblast growth factor (bFGF) also were measured.

RESULTS

Median CaSc equaled 17.9 Agatston units (range, 0 to 5,502 Agatston units). No calcification was detected in 20 subjects (46.5%; CaSc < 10 Agatston units). CaSc correlated with age (R = 0.57; P < 0.0001), body mass index (R = 0.42; P < 0.005), and serum leptin (R = 0.3; P < 0.05) and CRP levels (R = 0.38; P < 0.05). The correlation with PD therapy duration was borderline statistically significant (P = 0.063). Patients with the greatest values for CaSc (> 400 Agatston units) were characterized by significantly greater levels of IL-6, bFGF, and CRP compared with subjects with a CaSc less than 10 Agatston units (P < 0.05 for all). Patients with history of coronary artery disease (CAD) had significantly greater CaSc values (median, 778.6 versus 3.3 Agatston units; P < 0.001) compared with those without CAD. Serum triglyceride levels were significantly greater and HDL cholesterol levels were significantly lower in patients with CAD. The first group also was characterized by significantly greater serum TNF-alpha (P < 0.01) and CRP levels (P < 0.005). In multiple regression analysis, only age was independently associated with CaSc (beta = 0.45; P = 0.002).

CONCLUSION

Our results may suggest an association between CAC and chronic inflammation activity in the mentioned group of patients. To our knowledge, this is the first study reporting the prevalence of CAC in PD patients using the MSCT method. The association between CaSc results and classic, as well as inflammatory, risk factors for CAD found in this study should be interpreted with caution because of its method limitations (cross-sectional design, heterogeneity of study population, and small number of studied patients).

Inflammation in atherosclerosis

Abundant data link hypercholesterolaemia to atherogenesis. However, only recently have we appreciated that inflammatory mechanisms couple dyslipidaemia to atheroma formation. Leukocyte recruitment and expression of pro-inflammatory cytokines characterize early atherogenesis, and malfunction of inflammatory mediators mutes atheroma formation in mice. Moreover, inflammatory pathways promote thrombosis, a late and dreaded complication of atherosclerosis responsible for myocardial infarctions and most strokes. The new appreciation of the role of inflammation in atherosclerosis provides a mechanistic framework for understanding the clinical benefits of lipid-lowering therapies. Identifying the triggers for inflammation and unravelling the details of inflammatory pathways may eventually furnish new therapeutic targets.

Fibroblast growth factor receptor-1 signaling induces osteopontin expression and vascular smooth muscle cell-dependent adventitial fibroblast migration in vitro

BACKGROUND

Increased expression of osteopontin (OPN), fibroblast growth factors (FGFs), and their type-1 receptor (FGFR-1) is associated with neointima formation and atherosclerosis. This study tested the hypothesis that ligand activation of FGFR-1 stimulates OPN expression in rat aortic smooth muscle cells (RASMCs), explored the signaling pathway involved, and assessed the functional consequences of activating this pathway on adventitial fibroblast (AF) migration in vitro.

METHODS AND RESULTS

Exogenous FGF-1 stimulated expression of OPN mRNA and protein in RASMCs in vitro in a dose- and time-dependent manner. OPN mRNA induction by FGF-1 was completely inhibited by either actinomycin D or cycloheximide, selective inhibitors of RNA polymerase and protein synthesis, respectively. OPN mRNA induction by FGF-1 was attenuated by PD 166866, a highly selective and potent FGFR-1 tyrosine kinase inhibitor. Addition of either PP2 or PD98059, specific inhibitors of Src and mitogen-activated extracellular signal-regulated kinase (MEK)/mitogen-activated protein (MAP) kinases, respectively, attenuated FGF-1-stimulated OPN mRNA expression. FGF-1 treatment of RASMCs enhanced RASMC-conditioned medium-stimulated AF migration; this effect was inhibited by pretreatment of RASMCs with either PD166866 or PP2. Immunodepletion of OPN from RASMC-conditioned medium inhibited both basal and FGF-1-stimulated AF migration.

CONCLUSIONS

This in vitro study provided a first indication that ligand-activated FGFR-1 plays a significant role in upregulation of OPN expression at the transcriptional level via signaling to Src/MEK/MAP kinases in RASMCs and that this pathway is functionally significant in mediating AF migration via stimulation of OPN expression.

Glomerular targeting of acidic fibroblast growth factor-1 in renal transplanted rats

BACKGROUND

Acidic fibroblast growth factor (FGF-1) functions as a potent hormonal inducer of wound repair mechanisms in vivo. In addition, the involvement of FGF-1 in a number of pathophysiological conditions, including chronic human renal allograft rejection, has been described. Consequently, there is an increasing need to monitor FGF-1 pharmacokinetics and distribution for both therapeutic and diagnostic opportunities. We now describe in vivo imaging and targeting of FGF-1 in renal transplanted rats.

METHODS

Sham-operated, syngeneic renal transplanted, and allogeneic renal transplanted rats were imaged using an Anger gamma camera. Renal function was evaluated first by dynamic 99mTc-MAG3 imaging, and subsequently, 99mTc-labeled FGF-1 (99mTc-FGF-1) was imaged after i.v. injection. Microautoradiography of harvested kidneys determined the compartmental localization of 99mTc-FGF-1.

RESULTS

99mTc-MAG3 renal scans were grossly abnormal in the allogeneic renal transplanted rats. In this group, a significant reduction in 99mTc-FGF-1 renal binding was measured by imaging analyses, as compared with renal binding in the sham-operated and syngeneic renal transplanted groups, which were not significantly different. Both groups of renal transplanted rats showed a redistribution of FGF-1 to the glomerular compartment.

CONCLUSIONS

99mTc-FGF-1 serves as a new radiotracer to measure in vivo targeting of the growth factor. Reduced renal binding of 99mTc-FGF-1 in the allogeneic transplanted kidney was consistent with decreased blood flow. Unique glomerular targeting of 99mTc-FGF-1 in the transplanted kidney provides additional evidence supporting a role for this growth factor in the pathogenesis of chronic rejection.

Polypeptide growth factors and phorbol ester induce progressive ankylosis (ank) gene expression in murine and human fibroblasts

Polypeptide growth factors promote cellular proliferation by binding to specific plasma membrane-anchored receptors. This interaction triggers the phosphorylation of signal transducing molecules and the transcriptional activation of numerous genes. We have used a differential display approach to identify fibroblast growth factor (FGF)-1-inducible genes in murine NIH 3T3 fibroblasts. Here we report that one of these genes encodes ank, a type IIIa transmembrane protein reported to function in cells as an inorganic pyrophosphate transporter. FGF-1 induction of ank mRNA expression is first detectable at 2 h after growth factor addition and is dependent on de novo RNA and protein synthesis. Ank gene expression is also upregulated after treating quiescent fibroblasts with several other mitogenic agents (e.g., calf serum or platelet-derived growth factor-BB) or the tumor promoter phorbol 12-myristate 13-acetate. Furthermore, in comparison to parental NIH 3T3 cells, oncogene-transformed NIH 3T3 cells constitutively express elevated levels of ank mRNA. FGF-1 also increases ank gene expression in non-immortalized human embryonic lung fibroblasts. Finally, the murine and human ank genes are expressed in vivo in a tissue-specific manner, with highest levels of mRNA expression found in brain, heart, and skeletal muscle. These results indicate that ank is a growth factor-regulated delayed-early response gene in mammalian cells, and we propose that increased ank expression during cell cycle progression may be necessary to maintain proper intracellular pyrophosphate levels during conditions of high cellular metabolic activity.

Induction of the transcriptional repressor Yin Yang-1 by vascular cell injury. Autocrine/paracrine role of endogenous fibroblast growth factor-2

Yin Yang-1 (YY1) is a multifunctional transcription factor that can repress the expression of many growth factor, hormone, and cytokine genes implicated in atherogenesis. YY1 expression is activated in rat vascular smooth muscle cells shortly after injury. YY1 DNA binding activity paralleled elevated protein levels in the nucleus. Smooth muscle cell injury triggered the rapid extracellular release of immunoreactive fibroblast growth factor-2 (FGF-2). YY1 induction after injury was blocked by neutralizing antibodies directed against FGF-2. This growth factor increased YY1 mRNA and protein expression and stimulated YY1 binding and transcriptional activity. Overexpression of YY1 inhibited smooth muscle cell replication. Immunohistochemical analysis demonstrated YY1 staining in medial smooth muscle cells, coincident with FGF-2 expression. Proliferating cell nuclear antigen staining, in contrast, was confined mainly to the atherosclerotic intima. This is the first demonstration that YY1 is induced by either injury or FGF-2, is differentially expressed in normal and diseased human arteries, and that its overexpression inhibits vascular smooth muscle but not endothelial cell replication.

Implantation of bone marrow mononuclear cells into ischemic myocardium enhances collateral perfusion and regional function via side supply of angioblasts, angiogenic ligands, and cytokines

BACKGROUND

Bone marrow implantation (BMI) was shown to enhance angiogenesis in a rat ischemic heart model. This preclinical study using a swine model was designed to test the safety and therapeutic effectiveness of BMI.

METHODS AND RESULTS

BM-derived mononuclear cells (BM-MNCs) were injected into a zone made ischemic by coronary artery ligation. Three weeks after BMI, regional blood flow and capillary densities were significantly higher (4.6- and 2.8-fold, respectively), and cardiac function was improved. Angiography revealed that there was a marked increase (5.7-fold) in number of visible collateral vessels. Implantation of porcine coronary microvascular endothelial cells (CMECs) did not cause any significant increase in capillary densities. Labeled BM-MNCs were incorporated into approximately 31% of neocapillaries and corresponded to approximately 8.7% of macrophages but did not actively survive as myoblasts or fibroblasts. There was no bone formation by osteoblasts or malignant ventricular arrhythmia. Time-dependent changes in plasma levels for cardiac enzymes (troponin I and creatine kinase-MB) did not differ between the BMI, CMEC, and medium-alone implantation groups. BM-MNCs contained 16% of endothelial-lineage cells and expressed basic fibroblast growth factor>>vascular endothelial growth factor>angiopoietin 1 mRNAs, and their cardiac levels were significantly upregulated by BMI. Cardiac interleukin-1beta and tumor necrosis factor-alpha mRNA expression were also induced by BMI but not by CMEC implantation. BM-MNCs were actively differentiated to endothelial cells in vitro and formed network structure with human umbilical vein endothelial cells.

CONCLUSIONS

BMI may constitute a novel safety strategy for achieving optimal therapeutic angiogenesis by the natural ability of the BM cells to secrete potent angiogenic ligands and cytokines as well as to be incorporated into foci of neovascularization.

Vascular smooth muscle growth: autocrine growth mechanisms

Vascular smooth muscle cells (VSMC) exhibit several growth responses to agonists that regulate their function including proliferation (hyperplasia with an increase in cell number), hypertrophy (an increase in cell size without change in DNA content), endoreduplication (an increase in DNA content and usually size), and apoptosis. Both autocrine growth mechanisms (in which the individual cell synthesizes and/or secretes a substance that stimulates that same cell type to undergo a growth response) and paracrine growth mechanisms (in which the individual cells responding to the growth factor synthesize and/or secrete a substance that stimulates neighboring cells of another cell type) are important in VSMC growth. In this review I discuss the autocrine and paracrine growth factors important for VSMC growth in culture and in vessels. Four mechanisms by which individual agonists signal are described: direct effects of agonists on their receptors, transactivation of tyrosine kinase-coupled receptors, generation of reactive oxygen species, and induction/secretion of other growth and survival factors. Additional growth effects mediated by changes in cell matrix are discussed. The temporal and spatial coordination of these events are shown to modulate the environment in which other growth factors initiate cell cycle events. Finally, the heterogeneous nature of VSMC developmental origin provides another level of complexity in VSMC growth mechanisms.

Mast cells in acute and chronic rejection of rat cardiac allografts--a major source of basic fibroblast growth factor

BACKGROUND

Studies of cardiac allograft arteriosclerosis, i.e., chronic rejection, have largely focused on mononuclear inflammatory cell infiltrates in the vascular wall and periphery of the occluded vessels. The purpose of this study was to investigate the role of mast cells in the development of acute and chronic rejection in rat cardiac allografts.

METHODS

In the acute rejection model, transplant recipients were not treated with immunosuppressants, and the grafts were removed 5 days after transplantation at the time of severe acute rejection. In the chronic rejection model, the recipients were administered triple-drug immunosuppression, and the grafts were removed 90 days after transplantation.

RESULTS

During acute rejection, the number of mast cells was not increased, but the localization pattern differed from that of syngeneic grafts. In acute rejection, mast cells were located in the perivascular region of the allografts, but in syngeneic grafts, mast cells had a more interstitial location. In the chronic rejection model, the cardiac allografts with severe intimal thickening showed large numbers of mast cells at perivascular sites of occluded intramyocardial vessels and in the interstitium. Linear regression analysis revealed a significant correlation between the numbers of perivascular and interstitial mast cells and the intensity of intimal thickening. The majority of mast cells showed positive immunoreactivity to basic fibroblast growth factor (bFGF). Macrophage bFGF expression was not so prominent, but macrophages were more frequent in numbers. Tumor necrosis factor-alpha expression was detected mainly in macrophages and in only a few mast cells. When the intensity of arteriosclerosis was decreased by an increase in the intensity of immunosuppression, the numbers of intragraft mast cells and other mononuclear cells, and also the production of their respective cytokines, bFGF and tumor necrosis factor-alpha, gradually diminished.

CONCLUSIONS

Taken together, our data show that the intensity of intramyocardial mast cell infiltration was associated with the intensity of chronic inflammation and allograft arteriosclerotic changes, but not with acute rejection, and that mast cells, in addition to macrophages, are a major source of myocardial bFGF. The results also demonstrate that when the T-cell activation pathway is blocked using cyclosporin, the number of mast cells is decreased. Cyclosporin may have affected the cytokine production that interfered with both the mast cell-dependent initiation and the leukocyte- and mast cell-dependent amplification and progression of the immune responses influenced by mast cell-leukocyte cytokine cascades. bFGF produced by mast cells may contribute to enhanced inflammation, neovascularization, and fibrosis during cardiac allograft arteriosclerosis.

Plaque angiogenesis and atherosclerosis

Therapeutic angiogenesis trials refer to the stimulation of collateral arterioles and new vascular conduits to perfuse ischemic myocardium and limbs. Atherosclerotic lesions responsible for vascular occlusions themselves are associated with angiogenesis within the vessel wall. Plaque neovascularization is comprised of a network of capillaries that arise from the adventitial vasa vasorum and extend into the intimal layer of atherosclerotic lesions and other types of vascular injury. The functions of these plaque capillaries are proposed to be important regulators of plaque growth and lesion instability. The development of agents that are positive and negative regulators of angiogenesis may have potential therapeutic implications in the progression and acute manifestations of atherosclerosis. This review focuses on the role of plaque angiogenesis in atherosclerosis and discusses the potential therapeutic applications of angiogenesis inhibitors in this disease.

Vascular endothelial growth factor enhances atherosclerotic plaque progression

Vascular endothelial growth factor (VEGF) can promote angiogenesis but may also exert certain effects to alter the rate of atherosclerotic plaque development. To evaluate this potential impact on plaque progression, we treated cholesterol-fed mice doubly deficient in apolipoprotein E/apolipoprotein B100 with low doses of VEGF (2 microg/kg) or albumin. VEGF significantly increased macrophage levels in bone marrow and peripheral blood and increased plaque area 5-, 14- and 4-fold compared with controls at weeks 1, 2 and 3, respectively. Plaque macrophage and endothelial cell content also increased disproportionately over controls. In order to confirm that the VEGF-mediated plaque progression was not species-specific, the experiment was repeated in cholesterol-fed rabbits at the three-week timepoint, which showed comparable increases in plaque progression.

Intimal hyperplasia recurs after removal of PDGF-AB and -BB inhibition in the rat carotid artery injury model

Several antagonists specific for platelet-derived growth factor (PDGF) or its receptors have recently been developed and shown to inhibit intimal hyperplasia formation in various animal models, but data investigating the durability of this intervention is limited. The present study was designed to investigate the potency of PDGF B-chain aptamer, a novel type of PDGF-AB and -BB antagonist, in the rat carotid model and to characterize intermediate-term effects on lesion formation. One hundred thirty-four animals were randomized to aptamer treatment or placebo. Daily treatment with the antagonist resulted in a 50% reduction in lesion size at 2 weeks (P<0.001). The beneficial effect involved increased apoptosis and possibly an interference with smooth muscle cell migration. Discontinuing administration 1 week earlier did not give any significant benefit compared with phosphate-buffered saline-treated controls. When the antagonist was administered for 2 weeks and the vessels analyzed 6 weeks later, the beneficial effect was lost and the treated lesions had a higher intima-media and area-cell ratio compared with the treated lesions in the 2-week-endpoint study. Our findings confirm a role of PDGF B-chain in intimal hyperplasia, but the successful use of PDGF antagonists may require either prolonged treatment or combination therapy with other agents.

Endothelium-derived factors as paracrine mediators of prostate cancer progression

BACKGROUND

Vascular endothelium represents a complex network of cells producing a large number of active substrates affecting physiologic, metabolic, and immunologic properties of the whole organism, as well as particular organs or tissues. The potential influence of endothelium-derived paracrine factors on prostate cancer progression has only begun to be examined.

METHODS

This review summarizes recent literature on endothelium-derived factors, including vasoactive agents, peptide growth factors, cytokines, and colony-stimulating factors, involved in the development and progression of prostate cancer.

RESULTS

Endothelial cells produce an array of active substrates, many of which have been shown to influence prostate cancer growth. Available data demonstrate the positive impact of such molecules as endothelin-1, basic FGF, TGF-beta, IL-6, and IL-8 on prostate cancer progression. Many other endothelium-derived factors NO, IGF, PDGF, IL-1, G-CSF, and GM-CSF (Nitric Oxide, Insulin-Like Growth Factor, Platelet-Derived Growth Factor, Interleukin-1, Granulocyte Colony Stimulating Factor, and Granulocyte-Macrophage Colony Stimulating Factor) are, at best, implicated in prostate cancer growth, and in most cases support cancer progression.

CONCLUSIONS

A better understanding of endothelium-derived factors, as paracrine mediators of prostate carcinogenesis and progression, should aid in the development of novel therapeutic strategies.

Imaging Tc-99m-labeled FGF-1 targeting in rats

Recombinant human acidic fibroblast growth factor (FGF-1) was radiolabeled with (99m)Tc by the HYNIC method. The (99m)Tc-FGF-1 retained its representative molecular mass, heparin affinity, cellular binding to both low (Kd = 9.5 nM) and high (Kd = 125 pM) affinity sites, and mitogenic activity. Gamma camera imaging after intravenous dosing in rats confirmed high liver and kidney binding. Heparin significantly decreased (99m)Tc-FGF-1 liver uptake and increased urinary excretion. These studies illustrate a new method for imaging FGF-1 targeting under various conditions.

Basic fibroblast growth factor increases tissue factor expression in circulating monocytes and in vascular wall

BACKGROUND

Basic fibroblast growth factor (bFGF) promotes vascular repair and angiogenesis and can induce in vitro tissue factor (TF), a potent agent initiating thrombogenesis, which probably plays a role in angiogenesis. We investigated whether bFGF administration induced TF expression by monocytes and vascular cells.

METHODS AND RESULTS

We studied TF expression in normally fed (n=16) and cholesterol-fed (2% for 6 weeks, n=16) rabbits. Animals were then randomized to receive intravenous bFGF (2.5 microg twice weekly for 3 weeks) or saline injections. TF expression was evaluated in mononuclear cells from arterial blood and in aortic sections by an immunohistochemical assay using a monoclonal anti-rabbit TF antibody (activator protein 1). Monocyte TF expression was increased by bFGF administration in both normal and hypercholesterolemic rabbits (129+/-45 versus 19+/-3 mU TF/1000 monocytes, P<0.05, and 31+/-12 versus 7+/-1 mU TF/1000 monocytes, P<0.005, respectively) and was further increased by stimulation of monocytes by endotoxin in vitro. TF expression was lower in hypercholesterolemic rabbits than in normal rabbits. In the media of the vascular wall, bFGF induced strong TF expression in normal rabbits and only weak TF expression in hypercholesterolemic ones.

CONCLUSIONS

This study demonstrates that systemic administration of bFGF induces an impressive increase of TF expression in circulating monocytes and in the vascular wall in normal and to a lower extent in hypercholesterolemic rabbits. The significance of this observation in terms of inducing thrombosis in vivo needs clarification.

Requirement of phosphatidylinositol 3-kinase activity for translocation of exogenous aFGF to the cytosol and nucleus

Acidic fibroblast growth factor (aFGF) is a potent mitogen for many cells. Exogenous aFGF is able to enter the cytosol and nucleus of sensitive cells. There are indications that both activation of the receptor tyrosine kinase and translocation of aFGF to the nucleus are of importance for mitogenesis. However, the mechanism of transport of aFGF from the cell surface to the nucleus is poorly understood. In this work we demonstrate that inhibition of phosphatidylinositol (PI) 3-kinase by chemical inhibitors and by expression of a dominant negative mutant of PI 3-kinase blocks translocation of aFGF to the cytosol and nucleus. Translocation to the cytosol and nucleus was monitored by cell fractionation, by farnesylation of aFGF modified to contain a farnesylation signal, and by phosphorylation by protein kinase C of aFGF added externally to cells. If aFGF is fused to diphtheria toxin A-fragment, it can be artificially translocated from the cell surface to the cytoplasm by the diphtheria toxin pathway. Upon further incubation, the fusion protein enters the nucleus due to a nuclear localization sequence in aFGF. We demonstrate here that upon inhibition of PI 3-kinase the fusion protein remains in the cytosol. We also provide evidence that the phosphorylation status of the fusion protein does not regulate its nucleocytoplasmic distribution.

Changing concepts of atherogenesis

This review discusses three stages in the life history of an atheroma: initiation, progression and complication. Recruitment of mononuclear leucocytes to the intima characterizes initiation of the atherosclerotic lesion. Specific adhesion molecules expressed on the surface of vascular endothelial cells mediate leucocyte adhesion: the selectins and members of the immunoglobulin superfamily such as vascular cell adhesion molecule-1 (VCAM-1). Once adherent, the leucocytes enter the artery wall directed by chemoattractant chemokines such as macrophage chemoattractant protein-1 (MCP-1). Modified lipoproteins contain oxidized phospholipids which can elicit expression of adhesion molecule and cytokines implicated in early atherogenesis. Progression of atheroma involves accumulation of smooth muscle cells which elaborate extracellular matrix macromolecules. These processes appear to result from an eventual net positive balance of growth stimulatory versus growth inhibitory stimuli, including proteins (cytokines and growth factors) and small molecules (e.g. prostanoids and nitric oxide). The clinically important complications of atheroma usually involve thrombosis. Arterial stenoses by themselves seldom cause acute unstable angina or acute myocardial infarction. Indeed, sizeable atheroma may remain silent for decades or produce only stable symptoms such as angina pectoris precipitated by increased demand. Recent research has furnished new insight into the molecular mechanisms that cause transition from the chronic to the acute phase of atherosclerosis. Thrombus formation usually occurs because of a physical disruption of atherosclerotic plaque. The majority of coronary thromboses result from a rupture of the plaque's protective fibrous cap, which permits contact between blood and the highly thrombogenic material located in the lesion's lipid core, e.g. tissue factor. Interstitial collagen accounts for most of the tensile strength of the plaque's fibrous cap. The amount of collagen in the lesion's fibrous cap depends upon its rate of biosynthesis stimulated by factors released from platelets (e.g. transforming growth factor beta or platelet-derived growth factor), but inhibited by gamma interferon, a product of activated T cells found in plaques. Degradation by specialized enzymes (matrix metalloproteinases) also influences the level of collagen in the plaque's fibrous cap. Such studies illustrate how the application of cellular and molecular approaches has fostered a deeper understanding of the pathogenesis of atherosclerosis. This increased knowledge of the basic mechanisms enables us to understand how current therapies for atherosclerosis may act. Moreover, the insights derived from recent scientific advances should aid the discovery of new therapeutic targets that would stimulate development of novel treatments. Such new treatments could further reduce the considerable burden of morbidity and mortality due to this modern scourge, and reduce reliance on costly technologies that address the symptoms rather than the cause of atherosclerosis.

Vascular delay and administration of basic fibroblast growth factor augment latissimus dorsi muscle flap perfusion and function

Ischemia of the distal latissimus dorsi muscle flap occurs when the entire muscle is acutely elevated. Although this level of ischemia may not be critical if the muscle is to be used as a conventional muscle flap, the ischemia causes decreased distal muscle function if it is used for dynamic muscle flap transfer. This experiment was designed to determine whether or not the administration of exogenous basic fibroblast growth factor (bFGF), combined with a sublethal ischemic insult (i.e., vascular delay), would further augment muscle perfusion and function. Both latissimus dorsi muscles of nine canines were subjected to a bipedicle vascular delay procedure immediately followed by thoracodorsal intraarterial injection of 100 microg of bFGF on one side and by intraarterial injection of vehicle on the other. Ten days later, both latissimus dorsi muscles were raised as thoracodorsally based island flaps, with perfusion determined by laser-Doppler fluximetry. The muscles were wrapped around silicone chambers, simulating cardiomyoplasty, and stimulating electrodes were placed around each thoracodorsal nerve. The muscles were then subjected to an experimental protocol to determine muscle contractile function. At the end of the experiment, latissimus dorsi muscle biopsies were obtained for measurement of bFGF expression. The results demonstrated that the administration of 100 microg of bFGF immediately after the vascular delay procedure increases expression of native bFGF. In the distal and middle muscle segments, it also significantly increased muscle perfusion by approximately 20 percent and fatigue resistance by approximately 300 percent. The administration of growth factors may serve as an important adjuvant to surgical procedures using dynamic muscle flap transfers.

Oxidized low-density lipoproteins inhibit endothelial cell proliferation by suppressing basic fibroblast growth factor expression

BACKGROUND

Hyperlipidemia inhibits proliferation of endothelial cells (ECs) in culture and angiogenesis in vivo and in arterial explants. Elucidation of the mechanisms may suggest novel therapies against atherosclerosis.

METHODS AND RESULTS

Basic fibroblast growth factor (bFGF) expression and mitogenic effects were assessed in bovine aortic ECs incubated with oxidized LDL (ox-LDL). Compared with native LDL and lipoprotein-free controls, ox-LDL reduced bFGF mRNA levels in a time- and concentration-dependent manner, 100 microg/mL producing a maximum reduction of 40% to 50% within 24 to 48 hours. There were commensurate reductions in intracellular and extracellular bFGF concentrations, DNA and total RNA syntheses, and cell replication. FGF receptor 1 and beta-actin mRNA levels were unchanged. Ox-LDL accelerated bFGF mRNA degradation in actinomycin D-treated cells. However, inhibition of bFGF expression by ox-LDL was attenuated by cyclohexamide, indicating a requirement for continuous new protein synthesis for posttranscriptional destabilization. Reduced syntheses of DNA and total RNA were completely restored by bFGF but not by vascular endothelial growth factor. Inhibition of total RNA synthesis achieved by exposing cells to a bFGF-neutralizing antibody was similar in magnitude to that induced by ox-LDL.

CONCLUSIONS

Cytotoxic effects of ox-LDL on ECs are attributable in part to suppression of bFGF expression.

Endothelial-monocyte activating polypeptide II, a novel antitumor cytokine that suppresses primary and metastatic tumor growth and induces apoptosis in growing endothelial cells

Neovascularization is essential for growth and spread of primary and metastatic tumors. We have identified a novel cytokine, endothelial-monocyte activating polypeptide (EMAP) II, that potently inhibits tumor growth, and appears to have antiangiogenic activity. Mice implanted with Matrigel showed an intense local angiogenic response, which EMAP II blocked by 76% (P < 0.001). Neovascularization of the mouse cornea was similarly prevented by EMAP II (P < 0.003). Intraperitoneally administered EMAP II suppressed the growth of primary Lewis lung carcinomas, with a reduction in tumor volume of 65% versus controls (P < 0.003). Tumors from human breast carcinoma-derived MDA-MB 468 cells were suppressed by >80% in EMAP II-treated animals (P < 0.005). In a lung metastasis model, EMAP II blocked outgrowth of Lewis lung carcinoma macrometastases; total surface metastases were diminished by 65%, and of the 35% metastases present, approximately 80% were inhibited with maximum diameter <2 mm (P < 0.002 vs. controls). In growing capillary endothelial cultures, EMAP II induced apoptosis in a time- and dose-dependent manner, whereas other cell types were unaffected. These data suggest that EMAP II is a tumor-suppressive mediator with antiangiogenic properties allowing it to target growing endothelium and limit establishment of neovasculature.

Fibroblast growth factor 2 enhances early stages of in vitro endothelial repair by microfilament bundle reorganization and cell elongation

As endothelial cells convert from quiescent to migrating cells over 8 h along a wound edge, actin microfilaments undergo well-defined sequential changes characterized by an initial random distribution followed by a parallel and then a perpendicular orientation of microfilaments with respect to the wound edge. The latter is associated with subsequent cell migration. We tested the hypothesis that fibroblast growth factor 2 (FGF-2) can enhance the very early stages of wound repair even prior to migration and that FGF-2 enhancement of wound repair is associated with changes in the endothelial actin cytoskeleton. Using an in vitro two-sided wound model, the addition of FGF-2 at the time of wounding enhanced the extent of wound closure over 8 h. Treatment with FGF-2 was associated with significantly longer cells along the wound edge at 4 and 8 h after wounding. When treated with increasing concentrations of neutralizing FGF-2 antibody, the extent of wound closure decreased over 8 h and was associated with a decrease in cell length along the wound edge. Actin microfilaments were localized using rhodamine phalloidin and viewed using laser confocal microscopy. At 4 h after wounding, FGF-2 treatment was associated with significantly more cells along the wound expressing perpendicular microfilaments compared to untreated cells, which suggested a more rapid transition of parallel to perpendicular microfilament distribution. Thus, FGF-2 affects the very early stages of wound repair prior to migration by enhancing wound closure due to the early appearance of perpendicular microfilaments and lengthening of cells along the wound edge.

Characterization of the entire transcription unit of the mouse fibroblast growth factor 1 (FGF-1) gene. Tissue-specific expression of the FGF-1.A mRNA

Fibroblast growth factor 1 (FGF-1, also known as acidic FGF) is a mitogen for a variety of mesoderm- and neuroectoderm-derived cells, as well as an angiogenic factor in vivo. It has been implicated in angiogenic diseases including atherosclerosis, cancer and inflammatory diseases. In the present study, the entire transcriptional unit of the mouse FGF-1 gene, including four promoters, is characterized. By nucleotide sequence and RNase protection analyses, we have determined that its 3'-end resides 3.2 kilobase pairs downstream from the stop codon. We have previously cloned and characterized the mouse homologue of the human 1B promoter, as well as a novel upstream untranslated exon. In order to elucidate the regulatory mechanism of FGF-1 gene expression, the mouse promoter containing TATA and CAAT consensus sequences (FGF-1. A) was isolated from a P1 library and characterized. We further determined that the mouse heart is the most abundant source for the FGF-1.A mRNA. Finally, via both RNase protection analysis and 5'-rapid amplification of cDNA ends, we determined the transcription start site of the FGF-1.A mRNA.

Angiotensin II activates the proinflammatory transcription factor nuclear factor-kappaB in human monocytes

The renin-angiotensin system may contribute to the pathogenesis of atherosclerosis. A common feature of all stages of atherosclerosis is inflammation of the vessel wall. The transcription factor nuclear factor-kappaB (NF-kappaB) participates in most signaling pathways involved in inflammation. This study therefore examined the effect of angiotensin (ANG) II on NF-kappaB activation in monocytic cells, a major cellular component of human atheroma, by electrophoretic mobility shift assay. ANG II, like TNFalpha, caused rapid activation of NF-kappaB in human mononuclear cells isolated from peripheral blood by Ficoll density gradient. This ANG II effect was blocked by the angiotensin AT1 receptor antagonist losartan. Specificity of ANG II-induced NF-kappaB activation was ascertained by supershift and competition experiments. Moreover, ANG II stimulated NF-kappaB activation in human monocytes, but not in lymphocytes from the same preparation. Together, the data demonstrate the ability of the vasoactive peptide ANG II to activate inflammatory pathways in human monocytes.

Angiogenesis inhibitors endostatin or TNP-470 reduce intimal neovascularization and plaque growth in apolipoprotein E-deficient mice

BACKGROUND

Neovascularization within the intima of human atherosclerotic lesions is well described, but its role in the progression of atherosclerosis is unknown. In this report, we first demonstrate that intimal vessels occur in advanced lesions of apolipoprotein E-deficient (apoE -/-) mice. To test the hypothesis that intimal vessels promote atherosclerosis, we investigated the effect of angiogenesis inhibitors on plaque growth in apoE -/- mice.

METHODS AND RESULTS

ApoE -/- mice were fed a 0.15% cholesterol diet. At age 20 weeks, mice were divided into 3 groups and treated for 16 weeks as follows: group 1, recombinant mouse endostatin, 20 mg. kg-1. d-1; group 2, fumagillin analogue TNP-470, 30 mg/kg every other day; and group 3, control animals that received a similar volume of buffer. Average cholesterol levels were similar in all groups. Plaque areas were quantified at the aortic origin. Median plaque area before treatment was 0.250 mm2 (range, 0.170 to 0.348; n=10). Median plaque areas were 0.321 (0.238 to 0.412; n=10), 0.402 (0.248 to 0.533; n=15), and 0.751 mm2 (0.503 to 0.838; n=12) for the endostatin, TNP-470, and control groups, respectively (P</=0.0001). Therefore, endostatin and TNP-470 inhibited plaque growth during the treatment period by 85% and 70%. Intimal smooth muscle cell contents of plaques from control and treated mice were similar.

CONCLUSIONS

Prolonged treatment with either angiogenesis inhibitor reduced plaque growth and intimal neovascularization in apoE -/- mice. Although the mechanism of plaque inhibition induced by these agents is not established, these results suggest that intimal neovascularization may promote plaque development.

An Unusual Etiology of Biliary Hilar Obstruction and the Potential Role of Acidic Fibroblast Growth Factor in the Development of a Biliary Neuroma

Neuroma of the biliary tract is a rare condition thought to be caused by trauma secondary to cholecystectomy. More rare is the occurrence that causes symptomatic biliary obstruction. A 65-year-old woman was hospitalized because of abdominal pain, nausea, vomiting, and general malaise of 1 to 2 months duration. Cholecystectomy had been performed 40 years before. Ultrasound revealed hepatomegaly and dilated intrahepatic ducts. CT showed intra- and extrahepatic ductal dilatation with questionable intraductal mass. Endoscopic retrograde cholangiopancreatography and percutaneous transhepatic cholangiography demonstrated stricture of the hepatic duct bifurcation. The biliary bifurcation was resected, and hepaticojejunostomy was performed. The patient's postoperative course was unremarkable. Histological examination of the surgical specimen revealed positive staining for the S-100 antigen of the obstructing luminal stricture (without evidence of cholangiocarcinoma), which was consistent with a biliary neuroma. Positive staining was also found for acidic (and not basic) fibroblast growth factor (FGF) and two of its high affinity receptors (FGFR-1 and FGFR-4). This study supports the apparent association between biliary neuromas and cholecystectomy as well as the potential role of an established angiogenic and neurogenic growth factor in the formation of this tumor. Finally, this case is also unique in that it represents the longest interval between cholecystectomy and presentation of a biliary neuroma, 40 years after surgery.

Studies on the histogenesis of myxomatous tissue of human coronary lesions

Myxomatous tissue is a characteristic component of human coronary artery lesions, found more often in restenotic lesions. It represents a bulky accumulation of stellate-shaped cells of unknown histogenesis that are embedded in a loose stroma. We analyzed 64 atherectomy specimens containing substantial amounts of myxomatous tissue by using immunohistochemistry, in situ hybridization, and electron microscopy techniques. Stellate cells represented a heterogeneous population, sharing features of smooth muscle cells (SMCs), macrophages, as well as antigen-presenting dendritic cells. Like quiescent medial SMCs, the stellate cells in all specimens expressed high levels of SM alpha-actin message and protein and showed heterogeneity with respect to heavy-chain myosin, SM22, desmin, and vimentin. Ultrastructurally, stellate cells resembled SMCs, with some peculiarities that distinguish them from both differentiated and dedifferentiated SMCs. In contrast to quiescent SMCs, the stellate cells expressed high levels of acidic fibroblast growth factor mRNA and protein similar to cells of monocyte/macrophage lineage. However, stellate cells did not express the marker of mature macrophages, HAM56, and were heterogeneous with respect to CD68. Moreover, unlike SMCs, the stellate cells bore some of the major phenotypic markers of dendritic cells: they were S100-positive and showed various reactivity with respect to CD1a and human leukocyte antigen (HLA)-DR. Invasion of myxomatous tissue with CD45RO-positive T lymphocytes was correlated with strong expression of CD1a in these specimens. Stellate cells also expressed a pericyte marker, high-molecular-weight melanoma-associated antigen. We conclude that stellate cells of myxomatous tissue represent a specific phenotype of mesenchymal cells (possibly pericytes), which is activated to express some markers of antigen-presenting cells. These findings suggest involvement of the stellate cells in a local immune response.

Placenta growth factor (PlGF) mRNA expression in brain tumors

To investigate the relationship between placenta growth factor (PlGF) and brain tumor angiogenesis, we screened 36 primary and 3 metastatic brain tumors. We examined the expression of PlGF mRNA with respect to vasculature of various tumors which was determined by preoperative angiography. The expression of genes of the other angiogenic factors, vascular endothelial growth factor (VEGF), and basic fibroblast growth factor (bFGF) was also tested, and compared to that of PlGF. The primary tumors consisted of 16 meningiomas, 7 gliomas, 7 schwannomas, 4 pituitary adenomas, 1 germinoma, and 1 choriocarcinoma. Using a quantitative reverse transcription-polymerase chain reaction, the mRNA for PlGF149 and PlGF170 were detected in 25 out of 39 (64.1%) brain tumors. In primary brain tumors, PIGF mRNA was expressed in all the hypervascular tumors, but only in 5 of 16 hypovascular tumors (31.3%). None of the 3 metastatic hypervascular tumors expressed PlGF mRNA. The VEGF and bFGF mRNA expression was both detected in 87.2% of the tumors examined. We conducted hypoxic experiments with cultured U-251MG human glioma cells to determine the mechanism of PIGF gene regulation. As the atmospheric oxygen concentration was decreased, the PIGF mRNA level in the U-251MG cells was markedly increased. These results suggest that PIGF may contribute to the pathogenesis of brain tumor angiogenesis.

Modulation by interleukin-2 of cellular response to fibroblast growth factor-1 in F69-3 fibrosarcoma cells

FGF-1 stimulated DNA synthesis and induced expression of IL-2 receptors in the murine fibrosarcoma cell line, F69-3. Concomitant treatment with IL-2 abolished the stimulation of DNA synthesis, but not binding of FGF-1 to the FGF-receptors or subsequent endocytosis of the bound growth factor. Also, it did not inhibit activation of the FGF-receptor tyrosine kinase or stimulation of the downstream effector, MAP kinase. Treatment with IL-2 prevented transport of FGF-1 to the nuclear fraction in a time- and dose-dependent manner that parallelled the inhibition of FGF-1 stimulated DNA synthesis. The data support our earlier finding that transport of FGF-1 to the nucleus is an important event in the mechanism of stimulation of DNA synthesis induced by the growth factor, and they demonstrate that treatment with a cytokine can modulate the cellular response to FGF-1.

Regulation of a promoter of the fibroblast growth factor 1 gene in prostate and breast cancer cells

FGF-1 mRNA is expressed in the prostate cancer cell lines LNCaP and PC-3 and in the breast carcinoma cell line MDA-MB-231. Levels of FGF-1 mRNA have been shown to be up-regulated by serum, phorbol esters, and combinations of growth factors. It was shown that the major FGF-1 mRNA species expressed following serum stimulation in MDA-MB-231 cells is FGF-1.C. To better understand the potential role of FGF-1 in human prostate and breast cancer, we began an analysis of the cis- and trans-acting elements of one of its promoters required for the serum, PMA, and androgen regulation in breast and prostate cancer cell lines. We show that FGF-1.C steady-state mRNA levels are increased following serum or PMA stimulation of PC-3 cells. Further, we determine the FGF-1.C transcription start site in PC-3 cells. By sequence analysis, we show that consensus AP1, AP2, and Sp1 sites and ARE- and CRE-near consensus elements are present in the immediate 5' region of the FGF-1.C transcription start site. Gel-shift assays show that oligonucleotides containing FGF-1.C AP1, AP2, or Spl sequences form specific DNA-protein complexes with nuclear extracts from PC-3 cells. To determine if these or other cis-acting sequences are responsible for the serum, androgen, or growth factor regulation of FGF-1 expression, fragments of the FGF-1.C promoter region were cloned upstream of the luciferase reporter gene. We show that FGF-1 synergizes with androgen to enhance FGF-1.C transcription in LNCaP cells. We further show that the DNA fragment containing sequence up to 1614 nucleotides upstream of the FGF-1.C transcription start site is sufficient for stimulating promoter activity following serum treatment of MDA-MB-231 cells. Thus, FGF-1.C promoter contains sequences that are important for androgen or serum stimulation in prostate and breast cancer cells.