The direct effect of injectable cyclosporine and its vehicle, cremophor, on endothelial vascular cell adhesion molecule-1 expression. Ricinoleic acid inhibits coronary artery endothelial activation

Effect of cyclosporine on arterial balloon injury lesions in cholesterol-clamped rabbits: T lymphocyte-mediated immune responses not involved in balloon injury-induced neointimal proliferation

Restenosis after balloon dilatation of stenosed coronary arteries is a major clinical problem. Because T lymphocytes occur in neointima and because cyclosporine inhibits T-lymphocyte proliferation, we tested the hypothesis that cyclosporine would attenuate neointimal proliferation after balloon dilation injury. Rabbits with a balloon-injured aorta, randomized to cyclosporine in the human therapeutic range (n=13) or vehicle (n=14) were followed up for 5 weeks; as a control for the effect of cyclosporine, half the rabbits received in addition an aorta allograft. Rabbits were clamped at a human plasma cholesterol level of 5 to 7 mmol/L. Cyclosporine did not affect aorta cholesterol accumulation or neointimal proliferation in balloon-injured aortas; however, it attenuated both in transplanted aortas. Likewise, cyclosporine had no effect on endothelial cells at balloon-injured sites, but protected these cells in the transplanted aortas. Infiltration of smooth muscle cells, T lymphocytes, and macrophages were unaffected by cyclosporine in balloon-injured aortas; however, in transplanted aortas, cyclosporine reduced the relative number of T lymphocytes and macrophages but increased the relative number of smooth muscle cells. Finally, in balloon-injured aortas, cyclosporine did not affect expression of vascular adhesion molecule-1, intercellular adhesion molecule-1, or major histocompatibility complex II, but all these cellular activation markers were attenuated by cyclosporine in transplanted aortas. These results suggest that cyclosporine does not attenuate neointimal proliferation after balloon dilatation, and that T lymphocyte--mediated immune responses are not involved in neointimal proliferation after balloon dilatation.

A high linoleic acid diet increases oxidative stress in vivo and affects nitric oxide metabolism in humans

Evidence from in vitro studies shows that increased intake of polyunsaturated fatty acids leads to increased oxidative stress, which may be associated with endothelial damage. We measured the urinary levels of 8-iso-PGF2alpha and nitric oxide metabolites as well as plasma sICAM-1 levels from healthy subjects after strictly controlled diets rich in either linoleic acid (LA, C18:2 n-6) or oleic acid (OA, C18:1 n-9). Thirty-eight volunteers (20 women and 18 men, mean age 27 years) consumed a baseline diet rich in saturated fatty acids (SFA) for 4 weeks and were then switched to either a high LA diet (11.5 en%) or a high OA diet (18.0 en%) also for 4 weeks. During the LA and OA diets, nearly all food was provided for the whole day. A control group of 13 subjects consumed their habitual diet throughout the study. Urinary excretion of 8-iso-PGF2alpha was significantly increased after the LA diet (170 vs 241 ng/mmol creatinine, P=0.04), whereas the urinary concentration of nitric oxide metabolites decreased (4.2 vs 2.6 mg/mmol creatinine, P=0.03). No significant changes were seen in the OA group. Significant differences between the LA and control group were found for both 8-oxo-PGF2alpha (P=0.03) and NO (P=0.02), whereas the OA and LA groups did not differ with respect to any parameter. Also plasma sICAM-1 remained unchanged in both groups throughout the study. In conclusion, the high-LA diet increased oxidative stress and affected endothelial function in a way which may in the long-term predispose to endothelial dysfunction.

Functional food science and the cardiovascular system

Cardiovascular disease has a multifactorial aetiology, as is illustrated by the existence of numerous risk indicators, many of which can be influenced by dietary means. It should be recalled, however, that only after a cause-and-effect relationship has been established between the disease and a given risk indicator (called a risk factor in that case), can modifying this factor be expected to affect disease morbidity and mortality. In this paper, effects of diet on cardiovascular risk are reviewed, with special emphasis on modification of the plasma lipoprotein profile and of hypertension. In addition, dietary influences on arterial thrombotic processes, immunological interactions, insulin resistance and hyperhomocysteinaemia are discussed. Dietary lipids are able to affect lipoprotein metabolism in a significant way, thereby modifying the risk of cardiovascular disease. However, more research is required concerning the possible interactions between the various dietary fatty acids, and between fatty acids and dietary cholesterol. In addition, more studies are needed with respect to the possible importance of the postprandial state. Although in the aetiology of hypertension the genetic component is definitely stronger than environmental factors, some benefit in terms of the development and coronary complications of atherosclerosis in hypertensive patients can be expected from fatty acids such as alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid. This particularly holds for those subjects where the hypertensive mechanism involves the formation of thromboxane A2 and/or alpha 1-adrenergic activities. However, large-scale trials are required to test this contention. Certain aspects of blood platelet function, blood coagulability, and fibrinolytic activity are associated with cardiovascular risk, but causality has been insufficiently proven. Nonetheless, well-designed intervention studies should be initiated to further evaluate such promising dietary components as the various n-3 and n-6 fatty acids and their combination, antioxidants, fibre, etc. for their effect on processes participating in arterial thrombus formation. Long-chain polyenes of the n-3 family and antioxidants can modify the activity of immunocompetent cells, but we are at an early stage of examining the role of immune function on the development of atherosclerotic plaques. Actually, there is little, if any, evidence that dietary modulation of immune system responses of cells participating in atherogenesis exerts beneficial effects. Although it seems feasible to modulate insulin sensitivity and subsequent cardiovascular risk factors by decreasing the total amount of dietary fat and increasing the proportion of polyunsaturated fatty acids, additional studies on the efficacy of specific fatty acids, dietary fibre, and low-energy diets, as well as on the mechanisms involved are required to understand the real function of these dietary components. Finally, dietary supplements containing folate and vitamins B6 and/or B12 should be tested for their potential to reduce cardiovascular risk by lowering the plasma level of homocysteine.

Cell adhesion molecules in clinical renal transplantation

Leukocyte adhesion molecules are critically involved at a number of stages in immune and inflammatory responses, and their importance in the response to a renal allograft has been recognized for some years. They are involved in antigen presentation, in the cascade of events leading to extravasation of leukocytes into the allograft, in the subsequent migration of leukocytes through the extracellular matrix, and in the interactions between effector and target cells. Thus the adhesion molecules are highly attractive targets for therapeutic intervention in organ transplantation. Strategies have been explored to exploit the involvement of adhesion molecules in ischemia/reperfusion injury, allograft rejection, and the induction of immunological tolerance. Furthermore, the expression of a number of adhesion molecules is regulated by cytokines, and elevated levels may be detected both in transplant biopsies and as soluble forms measured in serum and urine. It has been proposed that these changes in levels might provide useful information in the diagnosis of allograft rejection and differentiation from other causes of graft dysfunction.

Effect of cyclosporine A on the release of tissue factor pathway inhibitor from endothelial cells in heart transplant patients and cell culture

We investigated the influence of cyclosporine A on the concentration of tissue factor pathway inhibitor and von Willebrand factor antigen in plasma of heart transplant outpatients. Tissue factor pathway inhibitor was quantified in plasma of blood donors (n = 50) and heart transplant outpatients (n = 50) by a chromogenic substrate assay with a mean of 32.4 micrograms/l and 98.2 micrograms/l, respectively. Von Willebrand factor antigen was determined with an enzyme-linked immunoassay with a mean of 90.9% for blood donors and 184.5% in plasma of heart transplant recipients. In addition, we investigated the effect of cyclosporine A on endothelial cell cultures over an incubation period of four days. A dose-dependent effect of cyclosporine A on the release of endothelial tissue factor pathway inhibitor and von Willebrand factor antigen was determined in a concentration range from 100 to 200 micrograms/l cyclosporine A. The tissue factor pathway inhibitor and von Willebrand factor antigen concentrations in the cell culture supernatant increased during the incubation time according to the cyclosporine A concentration 2-3 fold and 2 fold, respectively. For a further elucidation of the cyclosporine A effect we investigated the influence of cremophor EL, the vehicle of cyclosporine A. Cremophor EL alone did not increase the tissue factor pathway inhibitor release. However, the release was enhanced 2-4 fold after co-stimulation with the calcium ionophore A 23187 (10(-4) mol/l) in a concentration-dependent mode. We conclude that a generalized endothelial damage or activation is most probably caused by cyclosporine A and its vehicle cremophor EL. This process probably depends upon the increase of cytosolic free calcium, as described for the liberation of von Willebrand factor by endothelial cells.

Effect of probucol treatment on gene expression of VCAM-1, MCP-1, and M-CSF in the aortic wall of LDL receptor-deficient rabbits during early atherogenesis

Probucol is a potent inhibitor of atherosclerosis in animal models. However, the mechanism of its antiatherogenic effect is not known. To investigate the effects of probucol on gene expression of VCAM-1, MCP-1, and M-CSF in vivo during the early stages of atherogenesis, we determined gene expression in 12 control WHHL rabbits and 12 WHHL rabbits fed 1% probucol from age 3 weeks. Three animals from each group were killed at 6, 9, 12, and 18 weeks of age. Two intimal/medial segments of the thoracic aorta, each comprising the orifices of a pair of intercostal arteries, were analyzed by semiquantitative RT-PCR using GAPDH as an internal standard. A third segment located between these two segments was studied by immunocytochemistry. A basal level of VCAM-1 gene expression was observed in lesion-free aortas of both treated and untreated WHHL rabbits (and in normal NZW aortas). Immunocytochemistry showed some VCAM-1 protein in normal arteries and confirmed that VCAM-1 protein expression generally correlated with gene expression. In the untreated WHHL rabbits, a marked upregulation of VCAM-1 expression was observed at 18 weeks. To correlate gene expression with intimal monocyte/macrophages in each animal, the macrophage area was determined by morphometry of immunostained sections. In addition, a scoring system of lesions was used. VCAM-1 expression showed a highly significant correlation with the extent of intimal macrophage presence (P < .001). A lesser degree of correlation between gene expression and macrophage accumulation was also seen for MCP-1. In contrast, M-CSF expression remained constant over the entire study period and showed no correlation with the intimal macrophage accumulation. Probucol treatment completely prevented lesion formation in all animals up to 18 weeks of age. Probucol reduced the level of basal VCAM-1 expression and prevented its upregulation. MCP-1 expression was not affected by probucol treatment, whereas M-CSF expression was significantly lowered by probucol. Our results support the idea that VCAM-1 plays an important role in early atherogenesis and suggest that the antiatherogenic effect of probucol may in part be due to a downregulation of VCAM-1. Reduction of the basal level of M-CSF gene expression by probucol treatment may also contribute to its ability to inhibit atherogenesis.

Actions of ricinoleic acid and structurally related fatty acids on the gastrointestinal tract. II. Effects on water and electrolyte absorption in vitro

Ricinoleic acid, the active component of castor oil, and related fatty acids were studied to determine their relative inhibitory effects on water and electrolyte absorption using everted hamster jejunal and ileal segments. Differences were found between hydroxylated and nonhydroxylated congeners as well as between cis and trans geometric isomers. At a mucosal concentration of 2.0 mM, the unsaturated fatty acids had the following rank order of potency on inhibition of water absorption: ricionoleate greater than or equal to ricinelaidate- greater than equal to linoleate greater than oleate greater than linelaidate greater than elaidate. Ricinoleyl alcohol was effective at 2.0 mM but the methyl ester of ricinoleic acid was ineffective at this concentration. Among a series of saturated fatty acids including palmitate, stearate, a mixture of 9- and 10-hydroxystearate, and 12-hydroxystearate, only the last compound had any inhibitory effect on water absorption. The results define those portions of the ricinoleic acid molecule required for its effect on water and electrolyte absorption and suggest that classification of this cathartic as an "irritant" or "stimulant" should be re-evlauated.