The present study demonstrates that estrogen affects the human atrial myocardium and mediates protective actions through estrogen receptors-(ER) dependent signaling. Estrogen substantially modulates the local RAS via downregulation of ACE and simultaneous upregulation of ACE2, AT2R and MAS expression levels. This is indicative of a shift of the classical RAS/ACE axis to the alternative, protective RAS/ACE2 axis. In support of this view, estrogen attenuated the expression of RAS-associated downstream effectors, LOX-1, and ICAM-1. A specific antagonist of ERa reversed the anti-inflammatory and anti-oxidative effects of estrogen in paced and nonpaced atrial tissue slices. In summary, our data demonstrate the existence of protective effects of estrogen in atrial tissue from elderly men which are at least in part, mediated by the regulation of local RAS homeostasis. AbstractData from animal experiments and clinical investigations suggest that components of the renin-angiotensin system are markedly affected by sex hormones. However, whether estrogen affects human atrial myocardium has not been investigated yet. In this study, we determined the effects of estrogen on key components of atrial renin-angiotensin system: angiotensin-converting enzyme, responsible for generation of angiotensin II and angiotensin-converting enzyme 2, counteracting majority of AngII effects, and different renin-angiotensin system receptors, AT1R, AT2R, and MAS. First, the expression levels of estrogen receptors mRNA were determined in right atrial appendages obtained from patients undergoing heart surgery. The amounts of estrogen receptor a and estrogen receptor b mRNA were similar between women (n ¼ 14) and men (n ¼ 10). Atrial tissue slices (350 mm) were prepared from male donors which were exposed to estrogen (1-100 nM; n ¼ 21) or stimulated at 4 Hz for 24 h in the presence or absence of 100 nM estrogen (n ¼ 16), respectively. The administration of estrogen did not change mRNA levels of estrogen receptors, but activated MAP kinases, Erk1/2. Furthermore, estrogen increased the amounts of angiotensin-converting enzyme 2-mRNA (1.89 AE 0.23; P < 0.05) but reduced that of angiotensin-converting enzyme-mRNA (0.78 AE 0.07, P < 0.05). In addition, the transcript levels of AT2R and MAS were upregulated by estrogen. Pacing of tissue slices significantly increased the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at both the mRNA and protein level. During pacing, administration of estrogen substantially lowered the angiotensin-converting enzyme/angiotensin-converting enzyme 2 ratio at the transcript (0.92 AE 0.21 vs. 2.12 AE 0.27 at 4 Hz) and protein level (0.94 AE 0.20 vs. 2.14 AE 0.3 at 4 Hz). Moreover, estrogen elicited anti-inflammatory and anti-oxidative effects on renin-angiotensin system-associated downstream effectors such as pro-oxidative LOX-1 and pro-inflammatory ICAM-1. An antagonist of estrogen receptor a reversed these anti-inflammatory and anti-oxidative effects of estrogen significantly. Overall, our results demo...

Abstract-Recent findings suggest that inflammation plays a role in atherosclerosis and its acute complications. Cellular response in infections with Gram-negative bacteria is mediated by bacterial lipopolysaccharide (LPS), which activates monocytes to expression of cytokines, growth factors, and procoagulatory factors via LPS receptor CD14. Endothelial cells and smooth muscle cells are stimulated by a complex of LPS and soluble CD14. In this study, LPS receptor CD14 was analyzed to find genetic variants and check them for an association with coronary artery disease or myocardial infarction (MI). When screening the CD14 gene by single-strand conformation polymorphism analysis, a promoter polymorphism was detected and confirmed as a T-to-C exchange at position Ϫ159. We determined the genotypes of 2228 men who had undergone coronary angiography for diagnostic purposes. Within the total study group there was no significant association of either genotype with MI or coronary artery disease. However, in a subgroup with low coronary risk (normotensive nonsmokers), a relative risk for MI in probands homozygous for the T allele could be evaluated (OR, 1.6; 95% CI, 1.0 to 2.4; PϽ0.05). The association was even stronger in low-risk patients older than 62 years (OR, 3.8; 95% CI, 1.6 to 9.0; PϽ0.01). In conclusion, we describe a new CD14 promoter polymorphism that is associated with MI, especially in older patients with a low atherosclerotic risk profile. (Arterioscler Thromb Vasc Biol. 1999;19:932-938.)Key Words: CD14 Ⅲ genetics Ⅲ coronary disease Ⅲ myocardial infarction Ⅲ risk factors C D14 is a leucine-rich 55-kDa glycoprotein that is expressed in considerable amounts by mature monocytes, macrophages, and activated neutrophil granulocytes. 1 In these cells CD14 is known as a surface marker, being glycosylphosphatidylinositol anchored in the cell membrane (mCD14). 2 In addition, soluble CD14 (sCD14) can be found in serum where 2 major isoforms coexist, differing in molecular weight. 3 CD14 serves as receptor for bacterial lipopolysaccharide (LPS, endotoxin) and mediates cell activation by LPS. 4 The receptor-ligand interaction depends on a serum protein, LPS-binding protein, which complexes LPS and facilitates binding to mCD14 or sCD14. 5 Endothelial cells 6 and smooth muscle cells 7 are activated via sCD14, lacking their own membranous protein and CD14 mRNA. 7 In addition, they are activated indirectly by cytokines from LPSstimulated monocytes. 8 Endotoxin-activated monocytes produce proinflammatory cytokines such as tumor necrosis factor-␣, interleukin-1 and interleukin-6, and growth factors. 9 In stimulated endothelial cells, expression of endothelial leukocyte adhesion molecule-1, 10 intercellular adhesion molecule-1, 11 and vascular cell adhesion molecule-1 12 is induced, accompanying cell adhesion to endothelium. 12 LPS increases the levels of LDL and VLDL and supports the oxidation of LDL; HDL levels are decreased. 13 It stimulates smooth muscle cell proliferation and migration by release of platelet-derived growth f...

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Accumulating evidence links calcium-overload and oxidative stress to atrial remodeling during atrial fibrillation (AF). Furthermore, atrial remodeling appears to increase atrial thrombogeneity, characterized by increased expression of adhesion molecules. The aim of this study was to assess mitochondrial dysfunction and oxidative stress-activated signal transduction (nuclear factor-kappaB [NF-kappa B], lectin-like oxidized low-density lipoprotein receptor [LOX-1], intercellular adhesion molecule-1 [ICAM-1], and hemeoxgenase-1 [HO-1]) in atrial tissue during AF. Ex vivo atrial tissue from patients with and without AF and, additionally, rapid pacing of human atrial tissue slices were used to study mitochondrial structure by electron microscopy and mitochondrial respiration. Furthermore, quantitative reverse transcription polymerase chain reaction (RT-PCR), immunoblot analyses, gel-shift assays, and enzyme-linked immunosorbent assay (ELISA) were applied to measure nuclear amounts of NF-kappa B target gene expression. Using ex vivo atrial tissue samples from patients with AF we demonstrated oxidative stress and impaired mitochondrial structure and respiration, which was accompanied by nuclear accumulation of NF-kappa B and elevated expression levels of the adhesion molecule ICAM-1 and the oxidative stress-induced markers HO-1 and LOX-1. All these changes were reproduced by rapid pacing for 24 hours of human atrial tissue slices. Furthermore, the blockade of calcium inward current with verapamil effectively prevented both the mitochondrial changes and the activation of NF-kappa B signaling and target gene expression. The latter appeared also diminished by the antioxidants apocynin and resveratrol (an inhibitor of NF-kappa B), or the angiotensin II receptor type 1 antagonist, olmesartan. This study demonstrates that calcium inward current via L-type calcium channels contributes to oxidative stress and increased expression of oxidative stress markers and adhesion molecules during cardiac tachyarrhythmia.