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Published on: September 28, 2015
Attenuated hepatic inflammation and fibrosis in angiotensin type 1a receptor deficient mice
Liu Yang1, Ramón Bataller, Jennyfer Dulyx
1Department of Medicine, University of North Carolina, Chapel Hill, NC, USA.
Background/Aims:
Pharmacological blockade of the renin-angiotensin system (RAS) attenuates liver fibrogenesis in rats. Here, we provide genetic evidence implicating angiotensin type 1 (AT1) receptors in liver fibrogenesis.
Methods:
Wild type (WT) and AT1a knockout [AT1a (-/-)] mice were subjected to either sham operation or bile-duct ligation. Fibrosis was assessed by Sirius Red staining and hydroxyproline hepatic content. Fibrogenic and inflammatory cytokines were measured by ELISA.
Results:
Bile duct ligation-induced elevation of serum liver enzymes was similar in WT and AT1a (-/-) mice. Bile duct ligated WT mice showed inflammatory changes and severe septal fibrosis. In contrast, AT1a (-/-) mice showed minor fibrotic lesions. Collagen accumulation was lower in AT1a (-/-) mice compared to WT mice. The increase in hepatic concentration of TGFbeta1 and pro-inflammatory cytokines was attenuated in AT1a (-/-) mice compared to WT mice. Immunohistochemistry analysis revealed decreased infiltration by inflammatory cells, lipid peroxidation products as well as decreased phosphorylation of c-Jun and p42/44 MAPK in AT1a (-/-) mice compared to AT1 (+/+) mice.
Conclusions:
AT1 receptors play an important role in the development of fibrosis. Pharmacological blockade of AT1 receptors appears to be a promising approach to treat liver fibrosis.
