Increased expression of mineralocorticoid receptor and 11beta-hydroxysteroid dehydrogenase type 2 in human atria during atrial fibrillation.

BACKGROUND: Atrialfibrillation (AF) is associated with the activation of the renin-angiotensin-aldosterone system in the atria. It is not clear whether the expression of a mineralocorticoid receptor (MR), or 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2), conferring aldosterone specificity to the MR, in patients with AF is altered. HYPOTHESIS: Patients with AF may be associated with increased expression of MR and 11betaHSD2 in the atria. METHODS: Atrial tissue samples of 25 patients with rheumatic heart valve disease undergoing a valve replacement operation were examined. A total of 13 patients had chronic persistent AF (>6 mo) and 12 patients had no history of AF. The MR and 11betaHSD2 expression were analyzed at the mRNA and protein level. The localization of MR and 11betaHSD2 in atrial tissue was performed using specific immunohistochemistry staining. RESULTS: The results of real-time quantitative polymerase chain reaction (PCR) showed that AF groups, in comparison with sinus rhythm, had a higher mRNA expression level of MR or 11betaHSD2 (all P < 0.01). Both the MR and 11betaHSD2 protein expression level in atrial tissue were also significantly increased in patients with AF compared with patients with sinus rhythm (P < 0.05 or P < 0.01). The immunohistochemical staining of MR or 11betaHSD2 demonstrated that MR and 11betaHSD2 predominately located in the cytoplasm of myocardial cells in the atrium and the intensity and density of immunostaining appeared to be increased in the atria of patients with AF compared to those without AF. CONCLUSIONS: Increasing expression of MR and 11betaHSD2 in the atria during AF is one of the molecular mechanisms for development of atrial interstitial fibrosis in patients with AF. These findings may have an important impact on the treatment of AF with aldosterone antagonists.

Atrial 11beta-hydroxysteroid dehydrogenase type 2 expression in rheumatic heart disease patients with or without atrial fibrillation / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the mRNA and protein expressions of 11beta-Hydroxysteroid dehydrogenase type 2 (11betaHSD2) in patients with atrial fibrillation.</p><p><b>METHODS</b>Right and left atrial lateral wall tissue samples were obtained during mitral/aortic valve replacement operation from 25 patients with rheumatic heart valve disease (12 in sinus rhythm and 13 in chronic atrial fibrillation). Realtime quantitative PCR and Western blot were used to determine the mRNA and protein expressions of 11betaHSD2 in atria specimens. The distribution of 11betaHSD2 in human atrial tissue was analyzed by specific immunohistochemical staining. Echocardiography examination was performed before operation.</p><p><b>RESULTS</b>The left atrial diameters were significantly higher in the atrial fibrillation group as compared to sinus rhythm group (P < 0.01). Similarly, mRNA expression of 11betaHSD2 (0.86 +/- 0.14 vs 0.33 +/- 0.12 in right atria, 0.95 +/- 0.15 vs 0.37 +/- 0.10 in left atria, all P < 0.01) and protein expression of 11betaHSD2 (1.18 +/- 0.64 vs 0.71 +/- 0.21 in right atria, P < 0.01; and 1.36 +/- 0.58 vs 0.85 +/- 0.15 in left atria, P < 0.05) were also significantly upregulated in atrial fibrillation groups than those in sinus rhythm groups. The mRNA and protein expressions of 11betaHSD2 were similar between left atria and right atria both in fibrillation and sinus groups (all P > 0.05). The special immunohistochemical staining demonstrated that 11betaHSD2 was abundant in the human atrial myocardium and located mainly in the cytoplasm.</p><p><b>CONCLUSION</b>These findings suggested that upregulated 11betaHSD2 might be associated to the development and persistence of atrial fibrillation.</p>