Angiotensin II has multiple profibrotic effects in human cardiac fibroblasts.
BACKGROUND
Angiotensin II (Ang II) is implicated in cardiac remodeling and is increasingly recognized for its profibrotic activity.


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
H
H
Department of Medicine, Division of Endocrinology, Diabetes, and Hypertension, University of California at Los Angeles School of Medicine, CA 90024, USA.
Do
Y S
YS
Kawano
Y
Y
Starnes
V
V
Barr
M
M
Law
R E
RE
Hsueh
W A
WA
D000293:Adolescent; D000328:Adult; D000368:Aged; D000804:Angiotensin II / Q000494:pharmacology*; D057911:Angiotensin Receptor Antagonists; D002448:Cell Adhesion / Q000187:drug effects; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002455:Cell Division / Q000187:drug effects; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005347:Fibroblasts / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005355:Fibrosis / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D006321:Heart / Q000187:drug effects*; D006801:Humans; D008875:Middle Aged; D009206:Myocardium / Q000473:pathology*; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism
D057911:Angiotensin Receptor Antagonists; D015815:Cell Adhesion Molecules; D017395:Plasminogen Activator Inhibitor 1; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D044139:Receptor, Angiotensin, Type 2; D011945:Receptors, Angiotensin; D016212:Transforming Growth Factor beta; D000804:Angiotensin II