Effect of aldosterone and its antagonist on the expression of PAI-1 and TGF-β1 in rat hepatic stellate cells.

backgroundAldosterone has been implicated in a variety of organ fibroses, but its role and mechanism in liver fibrosis remain unclear.

methodsRat primary hepatic stellate cells (HSCs) were isolated, cultured, and characterized. HSCs were incubated with aldosterone (10(-6) M) for 4 h, 8 h, 12 h, 24 h, and 48 h, after which TGF-β1 (transforming growth factor beta 1) expression was measured by real-time PCR. Rat HSCs were treated with different concentrations of aldosterone (10(-6) M, 10(-7) M, 10(-8) M, and 10(-9) M), and the expressions of PAI-1 (plasminogen activator inhibitor-1) and TGF-β1 were determined by measuring mRNA and protein. HSCs were incubated in groups containing aldosterone (10(-6) M), spironolactone (10(-5) M), both aldosterone and spironolactone, or neither aldosterone nor spironolactone (control), after which mRNA and protein expression of PAI-1 and TGF-β1 were measured. Collagen I expression was detected by immunohistochemical analysis of supernatants of the aldosterone (10(-6) M), TGF-β1, and aldosterone plus TGF-β1 groups. SMAD expression was detected in rat HSC control, HSC plus aldosterone (10(-6) M), HSC plus TGF-β1, and HSC plus aldosterone plus TGF-β1 groups.

resultsHSCs were incubated with aldosterone for 4 h, 8 h, 12 h, 24 h, and 48 h after which TGF-β1 expression was measured. We found that TGF-β1 expression increased in a time dependent manner and reached a peak at 24 h. The expression of TGF-β1 in groups treated with aldosterone for 4 h, 8 h, 12 h, and 24 h was significantly different from the control group (P < 0.01). No significant difference was seen in TGF-β1 expression between the groups treated with aldosterone for 24 h and 48 h (P > 0.05). Compared with the control group, TGF-β1 expression was significantly increased after incubation with different concentrations of aldosterone (10(-6) M, 10(-7) M, 10(-8) M, and 10(-9) M) (P < 0.01). There were significant differences in the expression of TGF-β1 between 10(-6) M and 10(-7) M aldosterone treatment groups (P < 0.01). Compared with the control group, the expression of PAI-1 was significantly increased after incubation with different concentrations of aldosterone (10(-6) M, 10(-7) M, 10(-8) M, and 10(-9) M) (P < 0.01). PAI-1 expression was increased in the aldosterone, spironolactone, and aldosterone plus spironolactone groups. The expression of PAI-1 was significantly enhanced in the aldosterone and aldosterone plus spironolactone groups compared with the control group (P < 0.01). There was a marked enhancement of collagen I expression in the aldosterone, TGF-β1, and aldosterone plus TGF-β1 groups (P < 0.05). Collagen I expressions in the aldosterone and TGF-β1 groups were significantly different from the aldosterone plus TGF-β1 group (P < 0.01). Compared with the control group, SMAD expression was markedly elevated in the aldosterone, TGF-β1, and aldosterone plus TGF-β1 groups (P < 0.05). The expression of SMAD was significantly increased in the aldosterone plus TGF-β1 group compared with the aldosterone group (P < 0.01).

conclusionThis study demonstrated that aldosterone promoted HSC activation and the expression of TGF-β1, PAI-1, and collagen in hepatic fibrosis progression and that spironolactone administration partially reversed the effects. The aldosterone promotional effect on hepatic fibrosis was partially mediated by TGF-β1.