ACE inhibition lowers angiotensin II-induced chemokine expression by reduction of NF-kappaB activity and AT1 receptor expression.

OBJECTIVE: Angiotensin converting enzyme (ACE) inhibitors significantly improve survival in patients with atherosclerosis. Although ACE inhibitors reduce local angiotensin II (AngII) formation, serine proteases form AngII to an enormous amount independently from ACE. Therefore, our study concentrates on the effect of the ACE-inhibitor ramiprilat on chemokine release, AngII receptor (ATR) expression, and NF-kappaB activity in monocytes stimulated with AngII. METHODS AND RESULTS: AngII-induced upregulation of IL-8 and MCP-1 protein and RNA in monocytes was inhibited by the AT1R-blocker losartan, but not by the AT2R-blocker PD 123.319. Ramiprilat dose-dependently suppressed AngII-induced upregulation of IL-8 and MCP-1. The suppressive effect of ramiprilat on AngII-induced chemokine production and release was in part caused by downregulation of NF-kappaB, but more by a selective and highly significant reduced expression of AT1 receptors as shown in monocytes and endothelial cells. CONCLUSION: In our study we demonstrated for the first time that ramiprilat reduced expression of AT1R in monocytes and endothelial cells. In addition, ramiprilat downregulated NF-kappaB activity and thereby reduced the AngII-induced release of IL-8 and MCP-1 in monocytes. This antiinflammatory effect, at least in part, may contribute to the clinical benefit of the ACE inhibitor in the treatment of coronary artery disease.

Atorvastatin induces tissue transglutaminase in human endothelial cells.

Tissue transglutaminase (tTgase) contributes to the organisation of the basement membrane and is therefore thought to be important for the integrity and stability of the vessel wall. In the present study, we hypothesised that the HMG-CoA reductase inhibitor atorvastatin may up-regulate the tTgase expression in endothelial cells and thereby exert beneficial effects on endothelial function. Treatment of human umbilical vein endothelial cells (HUVEC) with atorvastatin (1-10 microM) caused a clear increased expression of tTgase in both permeabilised and non-permeabilised HUVEC. In contrast, stimulation of HUVEC with TNFalpha had no substantial effect on tTgase expression or localisation but inhibited the atorvastatin-induced up-regulation and externalisation of tTgase. Propidium iodide staining revealed that statin-induced apoptosis is not responsible for the enhanced expression. By inducing the expression of tTgase, statins may promote tTgase-mediated stabilisation of the basement membrane. This effect of atorvastatin may contribute to the beneficial role of statins on endothelial function.

Enhanced levels of CD154 (CD40 ligand) on platelets in patients with chronic heart failure.

BACKGROUND: Inflammation plays a significant contributory role in the pathogenesis of chronic heart failure (CHF). Previous data have shown enhanced plasma levels of proinflammatory cytokines, i.e. TNF-alpha and IL-6, as well as a persistent immune activation in patients with CHF. Furthermore, the immune modulator CD154 has been receiving increased attention, since it plays a key role in the pathophysiology of multicellular vascular events such as thrombosis, inflammation and atherosclerosis. Since CD154 initiates and maintains the release of proinflammatory cytokines from endothelial cells, its potential role for the development and progression of CHF is of interest. METHODS: Fifty patients with CHF (aged 66.9+/-12.6 years, mean ejection fraction 22.1+/-9.2%, NYHA II-IV, 39 of ischemic origin, 11 with idiopathic dilated cardiomyopathy) and 15 healthy controls (aged 62.5+/-9.8 years) were examined. Thirty-two patients were taking aspirin (100 mg/day). Blood was drawn from a peripheral vein and immediately fixed with 1% paraformaldehyde, incubated with anti-CD154, anti-P-selectin, and anti-CD61 and thereafter analyzed by flow cytometry. RESULTS: Patients with CHF showed significantly enhanced expression of platelet-bound CD154 and P-selectin as compared to controls (CD154: median 35.6 25th percentile: 26.3; 75th percentile: 44.6 vs. 12.8; 25th: 6.8; 75th: 15.6 mean fluorescence intensity [MFI], P<0.001; P-selectin: median 3.2 25th percentile: 1.9; 75th percentile: 5.9 vs. 1.4; 25th: 1.2; 75th: 1.9, MFI, P<0.001). CD154 expression on platelets positively correlated with increasing NYHA-class. In contrast, no significant differences in serum levels of soluble CD154 or CD40 expression on monocytes were detected in the study groups. Antiplatelet-therapy with aspirin did not influence CD154 or P-selectin expression on platelets. CONCLUSION: Our pilot study demonstrates significantly enhanced levels of CD154 on platelets in patients with CHF. This suggests that the CD40-CD154 axis may contribute to the proinflammatory milieu, which exists in CHF and thus may play a pathogenic role in the development and progression of CHF.

Induction of cyclooxygenase-2 and enhanced release of prostaglandin E(2) and I(2) in human endothelial cells by engagement of CD40.

OBJECTIVES: The hypothesis was tested that CD40-CD154 interaction is involved in the induction of cyclooxygenase-2 and the release of prostanoids in human endothelial cells. METHODS AND RESULTS: In a coculture model of human endothelial cells and a transfected CD154 positive cell line, engagement of CD40 on endothelial cells dramatically increased the synthesis of prostacyclin, prostaglandin E(2) and thromboxane A(2). This upregulation was mediated through an induction of cyclooxygenase-2 (Cox-2), as it was blocked by Cox-2-selective inhibitors. Western blot analysis demonstrated that Cox-2 protein was markedly increased in endothelial cells following CD40 engagement, an effect that was inhibited by pretreatment of cells with an anti-CD154 antibody. CONCLUSION: The data indicate that signaling via CD40 constitutes a major pathway in human endothelial cells for the induction of Cox-2 and release of prostanoids. The CD40-Cox-2 axis thus may represent an important pathway for initiating or maintaining an inflammatory process at the vessel wall.