Involvement of PKC and NF-kappaB in nitric oxide induced apoptosis in human coronary artery smooth muscle cells.

Apoptosis of vascular smooth muscle cells is critically involved in progression of atherosclerosis and may prevent intimal hyperplasia in restenosis and vascular remodeling. Nitric oxide (NO) is known to induce apoptosis, but the signaling pathways still remain unclear. We investigated p53 accumulation, protein kinase C (PKC) activation and nuclear transcription factor (NF-kappaB) binding activity as possible signaling mechanisms of NO-induced apoptosis. Apoptosis was induced dose-dependently with the NO-donors sodiumnitroprusside (SNP: 232+/-48%) and SIN-1 (241+/-90% of actinomycin D induced apoptosis; means +/- SEM, *p< or =0.05 vs. control) in HSMC. Inhibition of PKC significantly attenuated NO-induced apoptosis. Staurosporine reduced SIN-1/SNP-mediated DNA fragmentation by 55.3+/-13.8% and 38.3+/-13.9% respectively. Comparable results were obtained for calphostin C. However, NO-mediated induction of apoptosis was not preceded by p53 accumulation. SNP decreased NF-kappaB binding activity in HSMC. These results suggest that induction of apoptosis by exogenous NO in HSMC is not dependent on p53 accumulation but involves protein kinase C signaling and regulation of NF-kappaB binding activity. This opens a new therapeutical approach in preventing restenosis after angioplasty.

Effects of local delivery of trapidil on neointima formation in a rabbit angioplasty model.

1. Smooth muscle cell (SMC) proliferation can result in luminal reduction of a vessel following balloon angioplasty. This study was designed (i) to determine if local administration of trapidil (triazolopyrimidine) into a vessel wall reduces neointima formation, and (ii) to explore the mechanism involved in the subsequent reduction in cell proliferation. 2. Following balloon angioplasty in 40 anaesthetized New Zealand White rabbits, trapidil (50-200 mg) or its vehicle (saline) was injected into the dilated vessel wall of the right femoral artery. Experimental groups and time of investigation: (I) vehicle (2 weeks, n = 3), (II) trapidil-100 mg (2 weeks, n = 3), (III) vehicle (3 weeks, n = 8), (IV) trapidil-50 mg (3 weeks, n = 5); (V) trapidil-100 mg (3 weeks, n = 9) or (V) trapidil-200 mg (3 weeks, n = 7). 3. After 2 weeks, there was a significant reduction of intimal hyperplasia (expressed as intima to media area ratio) in the trapidil group compared with vehicle (0.44 +/- 0.04 vs 0.93 +/- 0.04, *P < 0.05) and also a significant reduction in cell proliferation (% ratio of BrdU-positive cells to total cell number: vehicle 14 +/- 2% vs trapidil 6 +/- 1%, *P < 0.05). 4. After 3 weeks, there was a dose-dependent reduction of intimal hyperplasia in the trapidil groups compared with vehicle (trapidil 50 mg 1.14 +/- 0.04; trapidil 100 mg 0.91 +/- 0.09*; trapidil 200 mg 0.77 +/- 0.09* vs vehicle 1.67 +/- 0.23, *P < 0.05). 5. Thus, the local administration of trapidil to the rabbit femoral artery reduces the neointima formation, which occurs 2 or 3 weeks after balloon angioplasty via a mechanism, which is dependent on inhibition of cell proliferation.

NO reduces PMN adhesion to human vascular endothelial cells due to downregulation of ICAM-1 mRNA and surface expression.

Reperfusion damage is largely due to the adherence of polymorphonuclear leukocytes to the endothelium initiated by adhesion molecule upregulation. The reduced endothelial nitric oxide release during ischemia may be involved in the upregulation of intercellular adhesion molecule 1. In this study, we tested if nitric oxide donors suppress polymorphonuclear leukocyte adherence to activated endothelial cells by inhibition of the intercellular adhesion molecule 1 surface expression. Confluent human umbilical vein endothelial cells were stimulated with tumor necrosis factor alpha (300 U/mL) after preincubation with increasing concentrations of the nitric oxide donors CAS 1609 (0.005-5 mM/L) and 3-(4-morpholinyl)-sydnonimine (0.01-1 mM/L). Intercellular adhesion molecule 1 surface expression was measured in a cell surface enzyme-linked immunosorbent assay, intercellular adhesion molecule 1 mRNA by Northern analysis. Human saphenous vein endothelial cells were transfected with the inducible nitric oxide synthase gene and stimulated with tumor necrosis factor alpha (300 U/mL). Fluorescein green-labeled polymorphonuclear leukocytes adhering to activated human umbilical vein endothelial cells/human saphenous vein endothelial cells were quantified by epifluorescent microscopy. The intercellular adhesion molecule 1 surface expression of activated human umbilical vein endothelial cells/human saphenous vein endothelial cells was significantly diminished to 40 to 60% of the maximum after treatment with CAS 1609, 3-(4-morpholinyl)-sydnonimine, or transfection with the inducible nitric oxide synthase gene. Intercellular adhesion molecule 1 mRNA was diminished by CAS 1609 and 3-(4-morpholinyl)-sydnonimine in the same manner. The functional relevance of our data was shown by reduction of polymorphonuclear leukocyte adherence to activated human umbilical vein endothelial cells/human saphenous vein endothelial cells following treatment with CAS 1609 and 3-(4-morpholinyl)-sydnonimine or transfection with inducible nitric oxide synthase. Tumor necrosis factor-induced polymorphonuclear leukocyte adherence was abolished by blocking antibody against intercellular adhesion molecule 1. Thus, exogenous or endogenous substitution of nitric oxide diminishes the expression of endothelial intercellular adhesion molecule 1 and its mRNA following tumor necrosis factor alpha stimulation. This results in a reduced polymorphonuclear leukocyte adherence to activated endothelium.

A nonhealing ulcer diagnosed as extramedullary plasmocytoma of the limb eight years after cardiac transplantation.

A 63-year-old man was hospitalized for a nonhealing ulcer of the left lower leg that appeared 8 years after orthotopic cardiac transplantation under immunosuppressive therapy including cyclosporine. Serum protein electrophoresis, immunofixation, and urinalysis revealed a monoclonal gammopathy IgG kappa. The final diagnosis of an extramedullary plasmocytoma was made by biopsy of the ulcer, which showed formations of plasmablastic cells. We report a rare case of extramedullary plasmocytoma as a posttransplantational malignancy.