Angiotensin II Has Multiple Profibrotic Effects in Human Cardiac Fibroblasts

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Abstract
Background —Angiotensin II (Ang II) is implicated in cardiac remodeling and is increasingly recognized for its profibrotic activity. Methods and Results —Because little is known about the direct cellular effects of Ang II on human cardiac fibroblasts, we isolated fibroblasts from ventricles of explanted human hearts and added Ang II (100 nmol/L) to determine its role in growth, extracellular matrix accumulation, and adhesion. To assess which Ang II receptor is involved, Ang II was added in the presence of irbesartan (10 μmol/L), a specific AT 1 receptor antagonist; PD 123319 (10 μmol/L), a specific AT 2 receptor antagonist, or divalinil (100 nmol/L), an AT 4 receptor inhibitor. In human ventricles (n=13), message levels of atrial natriuretic peptide and AT 1 receptor were inversely correlated, which suggests a decrease in AT 1 receptor expression with progressive heart failure. Northern analysis and fluorescence-activated cell sorting demonstrated AT 1 receptor in cultured human cardiac fibroblasts. Ang II increased mitogen-activated protein kinase activity and in DNA synthesis (5-fold, P 1 ( P P P Conclusions —Activation of the AT 1 receptor in human heart promotes fibrosis. Ang II plays a novel role in stimulation of plasminogen activator inhibitor-1 expression and adhesion of cardiac fibroblasts to collagen.

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