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P Libby

Publications and source records attributed to P Libby.

At least 181 records · Page 10Linked to original sources
PubMed1995

Adenovirus-mediated gene transfer into normal rabbit arteries results in prolonged vascular cell activation, inflammation, and neointimal hyperplasia.

Adenovirus vectors are capable of high efficiency in vivo arterial gene transfer, and are currently in use as therapeutic agents in animal models of vascular disease. However, despite substantial data on the ability of viruses to cause vascular inflammation and proliferation, and the presence in current adenovirus vectors of viral open reading frames that are translated in vivo, no study has examined the effect of adenovirus vectors alone on the arterial phenotype. In a rabbit model of gene transfer into a normal artery, we examined potential vascular cell activation, inflammation, and neointimal proliferation resulting from exposure to replication-defective adenovirus. Exposure of normal arteries to adenovirus vectors resulted in: (a) pronounced infiltration of T cells throughout the artery wall; (b) upregulation of intercellular adhesion molecule-1 and vascular cell adhesion molecule-1 in arterial smooth muscle cells; (c) neointimal hyperplasia. These findings were present both 10 and 30 d after gene transfer, with no evidence of a decline in severity over time. Adenovirus vectors have pleiotropic effects on the arterial wall and cause significant pathology. Interpretation of experimental protocols that use adenovirus vectors to address either biological or therapeutic issues should take these observations into account. These observations should also prompt the design of more inert gene transfer vectors.

Adenoviridae↗
PubMed1995

Evidence for apoptosis in advanced human atheroma. Colocalization with interleukin-1 beta-converting enzyme.

This study sought evidence for apoptosis, a form of programmed cell death, in human atheromatous coronary and carotid arteries. Markers for apoptotic cells included in situ terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), genomic DNA electrophoresis, and morphological analysis. Intimal lesions contained more TUNEL+ cells (34 +/- 6%, n = 8) than non-atherosclerotic arterial intima (8 +/- 3%, n = 5, P < 0.05). The tunica media of the diseased arteries had a percentage of TUNEL+ cells (5 +/- 1%) similar to that in the normal vessels (3 +/- 1%, N.S.). Oligonucleosomal DNA fragments were visualized in extracts from 12 atheromatous plaques but in none of 5 non-atherosclerotic vessels. Both smooth muscle cells (SMC) and macrophages, two major cell types in the atherosclerotic intima, bore markers of apoptosis, but with different patterns, as determined by double histochemical labeling for cell types and TUNEL. The TUNEL+ SMC localized mainly in the fibrotic portion of the atheroma, whereas TUNEL+ macrophages clustered near or within the lipid-rich core of the lesion. Atheromatous lesions expressed mRNA encoding interleukin-1 beta-converting enzyme (ICE), a mammalian cell death gene, as demonstrated by reverse transcriptase polymerase chain reaction. Immunohistochemistry revealed that ICE localized in regions of TUNEL+ SMC and macrophages. TUNEL- cells showed little or no immunoreactive ICE. These data point to a role for apoptosis in regulation of cell accumulation during atherogenesis and suggest involvement of ICE in SMC death in fibrous regions of complex atheroma, and in macrophage death in the lipid-rich core of the lesion. Apoptosis of vascular cells in fibrous cap may impede maintenance or repair of the matrix in this region and affect stability of the plaques.

Apoptosis↗
PubMed1995

Smooth muscle cells of the coronary arterial tunica media express tumor necrosis factor-alpha and proliferate during acute rejection of rabbit cardiac allografts.

Graft coronary arteriosclerosis (GCA) frequently limits the long-term success of cardiac transplantation. The pathogenic mechanisms of and stimuli that provoke GCA remain uncertain. Whatever the initiating factors, deranged control of smooth muscle cells (SMC) proliferation likely contributes to the intimal hyperplasia that produces obstructive lesions. To identify mediators that may contribute to ongoing modulation of SMC functions during acute rejection and to explore the mechanisms of the pathogenesis of graft coronary arteriosclerosis, we studied the kinetics of proliferation and the expression of tumor necrosis factor-alpha (TNF-alpha), a proinflammatory and SMC growth-promoting cytokine, in coronary arterial SMCs in rabbit hearts transplanted heterotopically without immunosuppression. Hearts were harvested at 2 (n = 5), 5 (n = 5), and 8.2 +/- 0.4 (mean +/- SD, n = 5) days after transplantation, just before graft failure as judged clinically. SMC proliferation was assessed by continuous bromodeoxyuridine labeling (BrdU 10 mg/kg/d. s.q.). Whole heart cross sections were stained immunohistochemically with monoclonal antibodies that recognize TNF-alpha, BrdU, and SMCs (muscle alpha-actin). Major epicardial coronary arteries (five to nine profiles in each animal) were evaluated. Histological rejection grades by the International Society for Heart and Lung Transplantation scale at 2, 5, and 10 days were 1.6 +/- 0.9, 2.8 +/- 1.1, and 4.0 +/- 0.0, respectively. Medial SMCs in normal hearts and 2 days after transplant expressed little or no TNF-alpha and displayed negligible BrdU incorporation. At 5 days after transplantation, some medial SMCs stained for TNF-alpha and had a low BrdU labeling index (0.5 +/- 0.8%). At 8.2 days after transplant, almost all medial SMCs expressed TNF-alpha intensely and had a high labeling index (29.8 +/- 8.0%). These results demonstrate that acute rejection activates medial SMCs in coronary arteries to express TNF-alpha and that SMC-derived TNF-alpha may contribute to medial SMC proliferation in coronary arteries during acute rejection. This finding of early medial SMC replication suggests a novel and heretofore unsuspected mechanism of intimal expansion consequent to the allogeneic state. These results furnish additional insight into the possible mechanisms that link acute rejection with graft coronary arteriosclerosis. Furthermore, the close association of TNF-alpha expression with SMC replication provides not only a novel marker of SMC activation but also a potential new therapeutic target for the prevention of graft coronary disease.

Animals↗
PubMed1995

Components of the protein fraction of oxidized low density lipoprotein stimulate interleukin-1 alpha production by rabbit arterial macrophage-derived foam cells.

Oxidized low density lipoproteins (oxLDL) (0.5-50 micrograms/ml) generated from both rabbit and human LDL stimulated the production of interleukin-1 alpha (IL-1 alpha) by as much as 2- and 6-fold, respectively, as compared to native LDL after a 2-h incubation with macrophage-derived foam cells isolated from the balloon-injured arteries of cholesterol-fed rabbits. Northern blot analyses confirmed that there was also an increase in the mRNA for IL-1 alpha and IL-beta in response to oxLDL in the isolated foam cells. The stimulation of IL-1 expression and production was not due to the contamination of the oxLDL preparations with endotoxin as neither the amount of endotoxin found to be associated with the lipoproteins nor amounts up to 1 ng/ml stimulated IL-1 alpha production to the same degree as oxLDL. Neither oxidized beta-very low density lipoprotein (VLDL) nor oxidized high density lipoprotein (HDL) stimulated IL-1 alpha production by the foam cells. Furthermore, acetyl-LDL had a very limited stimulatory effect, but other known ligands of the scavenger receptor such as maleylated-BSA, polyinosinic acid, and fucoidin elicited maximal IL-1 alpha responses. Fractionation of the oxLDL into lipid- and protein-soluble fractions showed that there was some stimulatory activity in the lipid phase but that known products of lipid peroxidation such as 9- and 13-HODE had no effect when added independently of lipoproteins. When added in combination with native LDL, only 13-HODE stimulated IL-1 alpha production. The delipidated apolipoprotein fragments of oxLDL that had been solubilized in beta-octylglucoside stimulated the production of IL-1 alpha by the foam cells to a greater degree than the lipid extract, while reductively methylated oxLDL did not. These data suggest that interactions of components of both the lipid- and protein-soluble fractions of oxLDL with scavenger receptors or potentially with surface proteins that bind oxLDL may induce production of IL-1 by arterial macrophages.

Animals↗
PubMed1995

Interrelation between atherosclerosis and restenosis.

Atherosclerosis and restenosis following PTCA share many pathophysiologic features although they differ in the inciting stimuli and in their time-course. Both are characterized by an inflammatory reaction of the vessel wall whose modulation may offer therapeutic approaches for either entity.

Angioplasty, Balloon, Coronary↗
PubMed1994

The omega-3 fatty acid docosahexaenoate reduces cytokine-induced expression of proatherogenic and proinflammatory proteins in human endothelial cells.

The mechanisms by which dietary fatty acids can modulate atherogenesis and inflammation are poorly understood. Induction in endothelial cells of adhesion molecules for circulating leukocytes and of inflammatory mediators by cytokines probably contributes to the early phases of atherogenesis and inflammation. We report here that incorporation into cellular lipids of docosahexaenoic acid (DHA), a specific fatty acid of the omega 3 family, decreases cytokine-induced expression of endothelial leukocyte adhesion molecules, secretion of inflammatory mediators, and leukocyte adhesion to cultured endothelial cells. DHA, but not eicosapentaenoic acid, decreased in a dose- and time-dependent fashion the expression of vascular cell adhesion molecule 1 (VCAM-1) induced by interleukin (IL)-1, tumor necrosis factor (TNF), IL-4, or bacterial lipopolysaccharide, with half-maximum inhibition at < 10 mumol/L. This reduction required prolonged (24- to 96-hour) exposure of endothelial cells to DHA and correlated with the degree of DHA incorporation into cellular lipids. DHA also limited cytokine-stimulated endothelial cell expression of E-selectin and intercellular adhesion molecule 1 and the secretion of IL-6 and IL-8 into the medium but not the surface expression of constitutive surface molecules. Cyclooxygenase inhibition did not block the effect of DHA on VCAM-1. In parallel with reduced surface VCAM-1 protein expression, DHA reduced VCAM-1 mRNA induction by IL-1 or TNF. DHA treatment also reduced the adhesion of human monocytes and of monocytic U937 cells to cytokine-stimulated endothelial cells. These properties of DHA may contribute to antiatherogenic and anti-inflammatory effects of omega 3 fatty acids.

Arteriosclerosis↗
PubMed1994

Interaction of the allogeneic state and hypercholesterolemia in arterial lesion formation in experimental cardiac allografts.

To learn more about the interaction of allogeneic transplantation and hypercholesterolemia in the formation of arterial lesions, we performed heterotopic cardiac transplantation in rabbits. We analyzed lesions in both the coronary arteries and the proximal ascending aorta 6 weeks after surgery in both transplanted and native hearts of normocholesterolemic rabbits and those with diet-induced hypercholesterolemia (serum cholesterol, 1638 +/- 366 mg/dL, n = 6, 6 weeks after transplantation). All animals received cyclosporin A (5 mg.kg-1.d-1) for immunosuppression. The transplanted aortas of hypercholesterolemic animals had thicker intimal lesions than did the native aortas (intima/media ratio, 0.67 +/- 0.4 versus 0.08 +/- 0.1, P < .05) and contained more T cells (37.4 +/- 12.8 versus 5.7 +/- 6.2 per high-power field, P < .001). In normocholesterolemic animals (n = 5) the coronary arteries had negligible lesions in the native heart and only slight and inconsistent intimal lesions in the transplanted heart. In the hypercholesterolemic animals, more coronary arteries had intimal lesions in the transplanted hearts than in the native hearts (74% versus 43%). Coronary artery lesions in the native hearts consisted mostly of foam cells, while those in transplanted hearts had more abundant smooth muscle cells as determined by alpha-actin staining. Intimal endothelial cells in transplanted aortas expressed increased levels of vascular cell adhesion molecule-1 and intracellular adhesion molecule-1 compared with the native vessels subjected to identical levels of cholesterolemia. Medial smooth muscle cells in transplanted aortas contained much higher levels of immunoreactive tumor necrosis factor-alpha than did medial cells of the native aorta in the same hypercholesterolemic animals. The intima of transplanted aortas contained prominent microvessels compared with the native aorta of the hypercholesterolemic rabbits. We conclude that even during treatment with doses of cyclosporine that control acute myocardial rejection, hypercholesterolemia and the allogeneic state act together to augment allograft atherosclerosis, T-cell accumulation, intimal neovascularization, local cytokine expression, and indices of cell activation in arteries.

Animals↗
PubMed1994

Diversity of T-cell antigen receptor V beta gene utilization in advanced human atheroma.

Human atheromata contain T lymphocytes, but knowledge of the function and receptor specificity of these cells is limited. Immunohistochemical studies have established that T cells in advanced human carotid plaques express predominantly the alpha/beta form of the T-cell receptor (TCR). We then compared the use of variable region genes of the beta-chain (V beta) of the TCR for antigen by analysis of 14 carotid plaques and peripheral blood samples obtained at carotid endarterectomy. We used a direct approach that avoids isolation and culture of T cells. RNA extracted from lesions and peripheral blood mononuclear cells was reverse transcribed and amplified by polymerase chain reaction (PCR) to determine rearrangements of 18 V beta sequences. PCR products were visualized on Southern blots using a probe internal to the PCR primers. Input cDNA from lesions and peripheral blood was adjusted to yield equivalent signals for a conserved region of the TCR beta-chain to permit comparisons. As expected, utilization of TCR V beta genes in peripheral blood cells was nonselective: an average of 17 of 18 V beta regions yielded signals (n = 14). Frequency of variable-region gene usage in lesions and blood was highly concordant: of 252 sequences tested (14 samples, 18 sequences per sample), 240 were identified in peripheral blood versus 207 in plaques. V beta genes 10 and 11 were not expressed in plaques, a significant difference when compared with peripheral blood (P = .0001 by chi 2). However, the remaining 16 genes showed no significant differences. This analysis indicates that T cells generally express a diverse pattern of V beta genes within complex human atheroma.

Arteriosclerosis↗
PubMed1994

Cytokine-stimulated human vascular smooth muscle cells synthesize a complement of enzymes required for extracellular matrix digestion.

Vascular matrix remodeling occurs during development, growth, and several pathological conditions that affect blood vessels. We investigated the capacity of human smooth muscle cells (SMCs) to express matrix metalloproteinases (MMPs), enzymes that selectively digest components of the extracellular matrix (ECM), in the basal state or after stimulation with certain cytokines implicated in vascular homeostasis and pathology. Enzymatic activity associated with various proteins secreted in the culture media was detected by gelatin or casein sodium dodecyl sulfate-polyacrylamide gel electrophoresis zymography. Proteins were identified by immunoprecipitation and mRNA by Northern blotting. SMCs constitutively secreted a 72-kD gelatinase and the tissue inhibitors of MMPs (TIMPs) types 1 and 2. SMCs stimulated with interleukin-1 or tumor necrosis factor-alpha synthesized de novo 92-kD gelatinase, interstitial collagenase, and stromelysin. Several lines of evidence suggest that when stimulated by cytokines, SMCs produce activated forms of MMPs. Together, the constitutive and the cytokine-induced enzymes can digest all the major components of the vascular ECM. Moreover, since these mediators augment the production of MMPs without appreciably affecting the synthesis of TIMPs, locally secreted cytokines may tip the regional balance of MMP activity in favor of vascular matrix degradation.

Cells, Cultured↗
PubMed1994

Increased expression of matrix metalloproteinases and matrix degrading activity in vulnerable regions of human atherosclerotic plaques.

Dysregulated extracellular matrix (ECM) metabolism may contribute to vascular remodeling during the development and complication of human atherosclerotic lesions. We investigated the expression of matrix metalloproteinases (MMPs), a family of enzymes that degrade ECM components in human atherosclerotic plaques (n = 30) and in uninvolved arterial specimens (n = 11). We studied members of all three MMP classes (interstitial collagenase, MMP-1; gelatinases, MMP-2 and MMP-9; and stromelysin, MMP-3) and their endogenous inhibitors (TIMPs 1 and 2) by immunocytochemistry, zymography, and immunoprecipitation. Normal arteries stained uniformly for 72-kD gelatinase and TIMPs. In contrast, plaques' shoulders and regions of foam cell accumulation displayed locally increased expression of 92-kD gelatinase, stromelysin, and interstitial collagenase. However, the mere presence of MMP does not establish their catalytic capacity, as the zymogens lack activity, and TIMPs may block activated MMPs. All plaque extracts contained activated forms of gelatinases determined zymographically and by degradation of 3H-collagen type IV. To test directly whether atheromata actually contain active matrix-degrading enzymes in situ, we devised a method which allows the detection and microscopic localization of MMP enzymatic activity directly in tissue sections. In situ zymography revealed gelatinolytic and caseinolytic activity in frozen sections of atherosclerotic but not of uninvolved arterial tissues. The MMP inhibitors, EDTA and 1,10-phenanthroline, as well as recombinant TIMP-1, reduced these activities which colocalized with regions of increased immunoreactive MMP expression, i.e., the shoulders, core, and microvasculature of the plaques. Focal overexpression of activated MMP may promote destabilization and complication of atherosclerotic plaques and provide novel targets for therapeutic intervention.

Arteries↗
PubMed1994

Endothelial and smooth muscle cells express leukocyte adhesion molecules heterogeneously during acute rejection of rabbit cardiac allografts.

Interactions of leukocytes with vascular wall cells figure prominently in acute rejection and development of vascular occlusive disease after cardiac transplantation. To investigate the time course and distribution among different types of vessels of expression of endothelial leukocyte adhesion molecules, issues difficult to address in humans, we studied heterotopic transplants of Dutch-Belted rabbit hearts into New Zealand white recipients without immunosuppression (average time to graft failure 8.2 +/- 0.4 days). We found constitutive expression of vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) by coronary arterial endothelium in normal rabbits, whereas myocardial capillaries and the endocardial lining cells showed little or no expression of VCAM-1. VCAM-1 expression increased within 1 day after transplantation on the endothelium of the transplanted aorta and endocardium and on myocardial microvascular endothelial cells. ICAM-1 expression increased remarkably on all endothelia studied from 2 to 8 days after transplantation. Adhesion molecule expression on coronary artery endothelial cells also increased during severe allograft rejection (from a histological score of 1.7 +/- 0.6 pretransplant to 4.8 +/- 0.2 8 days after transplant for VCAM-1 and from 0.9 +/- 0.6 to 4.4 +/- 0.3 for ICAM-1, n = 43 arteries in 5 animals, mean +/- SD). In addition, coronary artery and aortic smooth muscle cells also showed induction of VCAM-1 and ICAM-1 8 days after transplant. We conclude that endothelial activation in a transplanted organ can occur rapidly and varies among microvascular, endocardial, and coronary artery endothelial cells, a point germane to the interpretation of endomyocardial biopsies. Augmented expression of adhesion molecules precedes temporally leukocyte accumulation in vessels. In addition, our finding of activation of coronary artery smooth muscle cells during acute rejection suggests that such episodes may contribute to the development of accelerated coronary arteriosclerosis.

Acute Disease↗
PubMed1994

The pathogenesis of coronary arteriosclerosis ("chronic rejection") in transplanted hearts.

"Chronic rejection" of allografts may mean different things to different people. Some use this term to refer to a process more specifically described as arteriosclerotic obstruction of the coronary arteries of transplanted hearts. A number of mechanisms might contribute to the pathogenesis of this accelerated form of arterial disease, including administration of immunosuppressive agents such as corticosteroids with attendant hyperlipoproteinemia, viral infections, or ischemic injury of coronary artery endothelium occurring between harvest and reimplantation. However, involvement of the engrafted vessels with sparing of the host's native arteries suggested to us that immune phenomena underlie graft arteriosclerosis. In 1989 we proposed a model for the pathogenesis of accelerated arteriosclerosis associated with cardiac transplantation that linked a cellular immune response akin to delayed-type hypersensitivity to leukocyte recruitment and altered vascular cell function via a cytokine cascade (1). In support of this concept, coronary artery endothelium can express class II histocompatibility antigens (HLA) that might elicit a cellular immune response (2, 3). Leukocytes including macrophages and T lymphocytes accumulate in transplanted coronary arteries, as would be expected if an ongoing immune or inflammatory response contributed to this type of "chronic rejection". As we have previously suggested, T cells activated by graft endothelial cells that bear class II HLA probably secrete cytokines that could promote macrophage recruitment and activation, and proliferation and extracellular matrix synthesis by smooth muscle cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Endothelin-1 and endothelin receptor mRNA expression in normal and atherosclerotic human arteries.

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide implicated in a number of human diseases including atherosclerosis. ET-1 binds to two distinct G protein-coupled receptors, known as the ETA and ETB receptor subtypes. In this study, we have examined ET-1, ETA and ETB mRNA expression levels in human vascular cells cultured in vitro and in normal and atherosclerotic human arteries. The results indicate that (a) ET-1 mRNA is constitutively expressed by endothelial cells but not by smooth muscle cells, (b) endothelial cells express only ETB mRNA but smooth muscle cells co-express ETA and ETB mRNA, and (c) in comparison to normal aorta, ET-1 mRNA expression is elevated and endothelin receptor mRNA expression is repressed in atherosclerotic lesions.

Arteries↗
PubMed1993

An atherogenic diet rapidly induces VCAM-1, a cytokine-regulatable mononuclear leukocyte adhesion molecule, in rabbit aortic endothelium.

Accumulation of monocyte-derived foam cells in focal areas of the arterial intima is a key step in early atherogenesis. We investigated the expression of vascular cell adhesion molecule-1 (VCAM-1), a mononuclear leukocyte adhesion molecule, in the arterial endothelium during the early phases of diet-induced atherogenesis in rabbits in vivo and the regulation of VCAM-1 expression by cytokines in rabbit aortic organoid cultures in vitro. Rabbits were fed either an atherogenic diet (containing 0.3% cholesterol, 9% coconut oil, and 1% corn oil) or an isocaloric control diet (10% corn oil) for 4 days or 1, 3, 6, or 13 weeks. The endothelium in the ascending aorta focally expressed VCAM-1 after only 1 week on the atherogenic diet but before the first appearance of intimal macrophages, as judged by immunohistochemical staining of serial sections. The rabbits that consumed the atherogenic diet for 3 weeks or longer developed lesions in the intima composed of macrophages bearing class II major histocompatibility antigen (MHC-II). Endothelial cells continued to focally express VCAM-1 at sites of MHC-II-positive intimal macrophages for up to 13 weeks. The ascending aortas of control rabbits lacked VCAM-1 or MHC-II-positive endothelium or macrophages at all times studied. These observations demonstrate the focal activation of arterial endothelium as early as 7 days after initiation of an atherogenic diet (at serum cholesterol levels of 308 +/- 57 mg/dl).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Sustained activation of vascular cells and leukocytes in the rabbit aorta after balloon injury.

BACKGROUND: To improve understanding of the cellular basis of the arterial response to injury, we tested whether balloon withdrawal can induce certain inflammatory functions of vascular cells and leukocytes and whether such "activation" persists even after the acute phase of injury. METHODS AND RESULTS: We examined the expression of several inducible cell surface molecules in the rabbit aorta at 2, 5, 10, and 30 days after balloon injury. Longitudinal sections encompassing parts of the uninjured, border, and injured zones were examined for expression of vascular adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), class II major histocompatibility (MHC) antigens, and markers for smooth muscle cells (SMCs), macrophages, endothelial cells, and T-lymphocytes. Endothelial cell healing involved true endothelial regeneration as well as migration, as shown by nuclear incorporation of bromodeoxyuridine. Luminal endothelial cells at the leading edge of repopulation at each time point expressed VCAM-1. As healing progressed, VCAM-1 expression decreased in the regenerated endothelial cells. The neointimal endothelium also expressed high levels of ICAM-1 that persisted longer than the elevation of VCAM-1. SMCs in the neointima also showed increased levels of ICAM-1. Some neointimal endothelial cells, SMCs, and macrophages also expressed high levels of class II MHC antigens during 30 days after injury. CONCLUSIONS: Local inflammatory activation of endothelial cells, SMCs, and leukocytes occurs in a predictable sequence and persists up to 30 days after balloon injury to the rabbit aorta. Our findings suggest that ongoing local signals persisting after the original balloon injury may contribute to later phases of intimal thickening.

Angioplasty, Balloon↗
PubMed1993

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.

Because fibroblast growth factors (FGFs) modulate important functions of endothelial cells (EC) and smooth muscle cells (SMC), we studied FGF expression in human vascular cells and control or atherosclerotic arteries. All cells and arteries contained acidic (a) FGF and basic (b) FGF mRNA. Northern analysis detected aFGF mRNA only in one of five control arteries but in all five atheroma tested, while levels of bFGF mRNA did not differ among control (n = 3) vs. plaque specimens (n = 6). Immunolocalization revealed abundant bFGF protein in control vessels (n = 10), but little in plaques (n = 14). In contrast, atheroma (n = 14), but not control arteries (n = 10), consistently exhibited immunoreactive aFGF, notably in neovascularized and macrophage-rich regions of plaque. Because macrophages colocalized with aFGF, we tested human monocytoid THP-1 cells and demonstrated accumulation of aFGF mRNA during PMA-induced differentiation. We also examined the expression of mRNA encoding FGF receptors (FGFRs). All cells and arteries contained FGFR-1 mRNA. Only SMC and control vessels had FGFR-2 mRNA, while EC and some arteries contained FGFR-4 mRNA. The relative lack of bFGF in plaques vs. normal arteries suggests that this growth factor may not contribute to cell proliferation in advanced atherosclerosis. However, aFGF produced by plaque macrophages may stimulate the growth of microvessels during human atherogenesis.

Arteries↗