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

Basic fibroblast growth factor alterations during development of monocrotaline-induced pulmonary hypertension in rats

The chemical signaling pathways which orchestrate lung cell responses in hypertensive pulmonary vascular disease are poorly understood. The present study examined temporal alterations in lung basic Fibroblast Growth Factor (bFGF) in a well characterized rat model of monocrotaline (MCT)-induced pulmonary hypertension. By immunohistochemical analysis, there were progressive increases in bFGF in airway, vascular and gas exchange regions of MCT-treated rat lungs. Increases in bFGF preceded the onset of right ventricular hypertrophy at day 21 after MCT administration. Enhanced bFGF immunostaining was observed as early as day 4 in focal areas of the parenchyma, and by day 14 there was enhanced bFGF staining in alveolar macrophages, neutrophils and alveolar septa, which persisted through day 21. In conducting airways, there was elevated bFGF immunostaining in the smooth muscle cell (SMC) layer by days 4 and 7 and in the ciliated epithelium and its basement membrane at days 14 and 21. Cells morphologically similar to Clara cells in the luminal surfaces of bronchioles stained intensely on days 14 and 21. In the nucleus and cytoplasm of medial SMCs within pulmonary arteries, there was a progressive increase in bFGF staining starting at day 4. Lung bFGF mRNA was increased slightly at days 1, 4 and 7, while lung bFGF protein, as judged by western blot analysis, was increased at days 14 and 21 compared to controls. The present results, considered in teh light of teh documented roles of bFGF in vascular cell migration, growth and synthesis of extracellular matrix components, suggest that bFGF may contribute to the structural remodeling processes underlying the development of chronic pulmonary hypertension in MCT-treated rats.

Differential regulation of acidic and basic fibroblast growth factor gene expression in fibroblast growth factor-treated rat aortic smooth muscle cells

The acidic fibroblast growth factor (aFGF) and basic fibroblast growth factor (bFGF) proteins are potent vascular smooth muscle cell (SMC) mitogens that are expressed by endothelial cells and SMCs in vivo. Overexpression of these proteins in transfected cell lines can result in autocrine transformation; therefore, the precise control of fibroblast growth factor gene expression in the vessel wall may be an important mechanism regulating vascular cell growth. In the present study, we demonstrate that bFGF can induce bFGF mRNA expression, but not aFGF mRNA expression, in serum-starved rat aortic SMCs. bFGF autoinduction is maximal at 4 hours, requires de novo RNA and protein synthesis, and is mediated predominantly by a protein kinase C-dependent signaling pathway. Furthermore, aFGF treatment of rat SMCs also increases bFGF mRNA and protein expression; however, aFGF mRNA levels are only slightly modulated. These results suggest that the local release of aFGF or bFGF within the vessel wall could promote a prolonged period of elevated bFGF synthesis. This, in turn, could be of importance in the SMC hyperplasia that occurs in response to vascular injury and during atherosclerotic plaque formation.

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.