Frau Dr. Valéria Lamounier-Zepter

Endocrine Function of Adipose Tissue – Effect of adipocyte-derived factors in the pathogenesis of cardiovascular disease

Previous and current research

Obesity is a well-known risk factor for cardiovascular disease, including systemic hypertension and heart failure. Recent studies have revealed the importance of human adipose tissue as a highly active endocrine organ. White adipose tissue produces and releases a wide variety of peptides and proteins, collectively referred to as adipokines, which may mediate the communication of adipose tissue with other organs, such as muscle, liver, pancreas, brain and heart. We are interested in the interaction of adipose tissue and the cardiovascular system, via the release of adipokines, as a basis to understand the pathophysiology of obesity-associated cardiovascular disorders, such as hypertension and heart failure. We have recently identified mineralocorticoid-releasing factors (adipotensins) secreted by human adipocytes, supposedly implicated in the pathophysiology of obesity-mediated hypertension (Fig. 1). Indeed, increased aldosterone levels have been observed in obese patients. In ongoing studies we are characterizing the factors responsible for this stimulation.

Fig. 1. Proposed mechanisms for obesity-related hypertension
(Lamounier-Zepter et al. HMR 2004).

A further objective of our studies refers to the effect of adipose tissue on the heart physiology. Obesity has long been recognized as an important risk factor in heart failure, independent of diabetes mellitus and arterial hypertension. In cooperation with Prof. I. Morano, Department of Muscle Physiology, Max-Delbrück Center for Moleculare Medicine in Berlin we are analyzing the effect of adipocyte-derived factors on cardiomyocyte contractile function.

Ongoing studies:

Characterisation of the factors responsible for the aldosterone stimulation and the adrenal mechanisms involved in the adipocyte-dependent aldosterone production.
Regulation of production and secretion of adipokines.
Analysis of a direct effect of adipocyte-factors on cardiomyocyte contraction and its mechanisms involved.

Selected publications

Lamounier-Zepter V Ehrhart-Bornstein M, Karczewski S, Bornstein SR, Morano I. Human adipocytes attenuate cardiomyocytes contraction. Characterization of an adipocyte-derived negative inotropic activity. (submitted)
Lamounier-Zepter V, Ehrhart-Bornstein M, Bornstein SR. Metabolic syndrome and the endocrine stress system. Horm Metab Res. In press
Lamounier-Zepter V, Ehrhart-Bornstein M. Fat tissue metabolism and adrenal steroid secretion. Current Hypertension Reports In press.
Lamounier-Zepter V, Ehrhart-Bornstein M, Bornstein SR (2005). Mineralocorticoid-stimulating activity of adipose tissue. Best Pract Res Clin Endocrinol Metab. 19, 567-575.
Lamounier-Zepter V, Bornstein SR, Ehrhart-Bornstein M (2004). Mechanisms of obesity-related hypertension. Horm Metab Res 36, 376-380.
Ehrhart-Bornstein M, Lamounier-Zepter V, Schraven A, Langenbach J, Willenberg HS, Barthel A, Hauner H, Mc Cann SM, Scherbaum WA, Bornstein SR (2003). Human adipocytes secrete mineralocorticoid-releasing factors. Proc Natl Acad Sci USA 100, 14211-14216.
Lamounier-Zepter V, Baltas LG, Morano I (2003) Distinct contractile systems for electromechanical and pharmacomechanical coupling in smooth muscle. Adv Exp Med Biol 538,417-25.
Morano I, Chai G-X, Baltas LG, Lamounier-Zepter V, Lutsch G, Kott M, Haase H, Bader M (2000). Smooth-muscle myosin contraction without smooth muscle myosin. Nature Cell Biology 2, 371-375.

Curriculum Vitae

1990-1996: Medical Faculty of Universidade Federal de Minas Gerais, Brazil and University of Düsseldorf, Germany, Diploma degree in Medicine, Brazil

1997-1998: Resident in Internal Medicine, Hospital Governador Israel Pinheiro, Brazil

1999-2002: Training in Basic Research, Department of Muscle Physiology, Max Delbrück Center for Moleculare Medicine, Berlin. Doctoral Thesis

2003: MD at the Humboldt University, Berlin

2002-2004: Resident and postdoctoral research at the University of Düsseldorf, Department of Endocrinology, Diabetes and Rheumatology

Since 2005: Resident and postdoctoral research at the University of Dresden, Medical Clinic III