Angiotensin II increased DNA synthesis 5-fold (P<0.01) and stimulated a 2-fold increase in TGF-beta1, laminin, and fibronectin mRNA levels in human cardiac fibroblasts via the AT1 receptor.
Does Angiotensin II promote profibrotic effects in human cardiac fibroblasts?
Angiotensin II promotes fibrosis in human cardiac fibroblasts via the AT1 receptor by stimulating growth, extracellular matrix accumulation, and adhesion, providing mechanistic insight into cardiac remodeling.
Effect estimate: 5-fold increase in DNA synthesis
p-value: p=<0.01
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 micromol/L), a specific AT(1) receptor antagonist; PD 123319 (10 micromol/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<0.01) stimulated a 2-fold increase in transforming growth factor-beta(1) (P<0.05) mRNA levels at 2 hours and a 2-fold increase in laminin (P<0.05) and fibronectin (P<0.05) mRNA levels at 24 hours. Ang II also enhanced plasminogen activator inhibitor-1 expression, which inhibits metalloproteinases that degrade the extracellular matrix. All of these effects were inhibited by irbesartan but not PD 123319 or divalinil. In addition, Ang II increased cardiac fibroblast attachment to collagens I and III, which was associated with an increase in focal adhesion kinase activity. 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.
Kawano et al. (Tue,) conducted a other in Heart failure (n=13). Angiotensin II vs. Irbesartan, PD 123319, or divalinil was evaluated on DNA synthesis and profibrotic marker mRNA levels (5-fold increase in DNA synthesis, p=<0.01). Angiotensin II increased DNA synthesis 5-fold (P<0.01) and stimulated a 2-fold increase in TGF-beta1, laminin, and fibronectin mRNA levels in human cardiac fibroblasts via the AT1 receptor.