Effects of losartan on hepatic expression of nonphagocytic NADPH oxidase and fibrogenic genes in patients with chronic hepatitis C

Abstract

Angiotensin II promotes liver fibrogenesis by stimulating nonphagocytic NADPH oxidase (NOX)-induced oxidative stress. Angiotensin II type 1 (AT1) receptor blockers attenuate experimental liver fibrosis, yet their effects in human liver fibrosis are unknown. We investigated the effects of losartan on hepatic expression of fibrogenic, inflammatory, and NOX genes in patients with chronic hepatitis C (CHC). Fourteen patients with CHC and liver fibrosis received oral losartan (50 mg/day) for 18 mo. Liver biopsies were performed at baseline and after treatment. The degree of inflammation and fibrosis was evaluated by histological analysis (METAVIR). Collagen content was measured by morphometric quantification of Sirius red staining. Overall collagen content and fibrosis stage remained stable in the whole series, yet the fibrosis stage decreased in seven patients. Inflammatory activity improved in seven patients. The effect of losartan on hepatic expression of 31 profibrogenic and inflammatory genes and components of the NOX complex was assessed by quantitative PCR. Losartan treatment was associated with a significant decrease in the expression of several profibrogenic and NOX genes including procollagen alpha1(I) and alpha1(IV), urokinase-type plasminogen activator, metalloproteinase type 2, NOX activator 1 (NOXA-1) and organizer 1 (NOXO-1), and Rac-1. Losartan was well tolerated in all patients and was effective in attenuating the activity of the systemic renin-angiotensin system. No effects on serum liver tests or viral load were observed. We conclude that prolonged administration of losartan, an oral AT1 receptor blocker, is associated with downregulation of NOX components and fibrogenic genes in patients with CHC. Controlled studies are warranted to assess the effect of AT1 receptor blockers in chronic liver injury.

Trial registration: ClinicalTrials.gov NCT00298714.

Fig. 1.

Changes in the degree of inflammation and fibrosis before and after losartan treatment assessed by histological analysis using the METAVIR score (A, C, D: hematoxylin and eosin and Masson's trichromic staining) and morphometry (B: Sirius red staining). A: changes in the stage of liver fibrosis [F0: no fibrosis; F1: portal; F2: rare septa; F3: numerous septa; F4: cirrhosis; not significant (n.s.)]. B: changes in collagen content (not significant). C: changes in the inflammatory activity (A0: none; A1: mild; A2: moderate; A3: severe; P < 0.05). D: changes in the degree of piecemeal necrosis (P < 0.05).

Fig. 2.

Unsupervised hierarchical clustering of normal (NORM) livers (n = 6) and patients with chronic hepatitis C (HCV) before treatment with oral losartan (n = 14) according to the expression profile of the selected genes.

Fig. 3.

A: changes in the degree of urokinase-type plasminogen activator (ut-PA) expression in liver samples assessed by immunohistochemistry (IHC) (P < 0.05 vs. baseline). B: representative picture of ut-PA immunohistochemistry in 1 patient at baseline and after prolonged treatment with losartan (magnification ×200). D: ut-PA expression was noted in hepatocytes (solid arrows) and within the fibrous stroma (open arrows). C: correlation between changes in gene expression of ut-PA (fold vs. baseline) and changes in protein expression of ut-PA (vs. baseline) following treatment with losartan.