Nitric oxide-independent activation of soluble guanylate cyclase by BAY 60-2770 in experimental liver fibrosis

Liver cirrhosis is a chronic disease with high mortality rate and need for effective pharmacological intervention. The fibrotic remodelling of liver tissue is crucially dependent on hepatic stellate cell activation. Activation of hepatic stellate cells is reduced by an increase in cyclic guanosine monophosphate (cGMP). Stable cGMP analogues also reduce the contractile response of hepatic stellate cells. However, cGMP production is downregulated in the cirrhotic liver due to the reduced activity of the endothelial nitric oxide synthase.

Objective: Here we report that the novel activator of soluble Guanylate Cyclase (sGC), BAY 60-2770 (4-({(4-carboxybutyl) [2- (5-fluoro-2-{[4'-(trifluoromethyl) biphenyl-4-yl]methoxy}phenyl)ethyl] amino}methyl)benzoic acid), which increases the activity of sGC in a nitric oxide-independent manner, attenuates liver fibrosis in two rat models.

Methods: The compound was studied in the pig serum model and the carbon tetrachloride model. Fibrosis was assessed by estimating the increase in fibrous collagen by micromorphometry of histological sections stained with Sirius Red/Fast Green and by measuring total hepatic collagen.

Results: BAY 60-2770, on a recombinant sGC reporter cell line, stimulated the luminescence signals with an EC50 value of 5.4 +/- 1.2 nmol/L. In the presence of [1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ; 10 pmol/L) the EC50 was shifted to 0.39 +/- 0.11 nmol/L. In both fibrosis models, once daily oral administration of BAY 60-2770 concomittantly with the fibrotic stimulus prevented 60-75% of fibrosis, the lowest effective dose being 0.1 mg/kg in the pig serum model and 0.3 mg/kg in the carbon tetrachloride model. The treatment was well tolerated by all Animals. The doses used were devoid of any significant influence on systemic blood pressure.

Conclusion: Nitric oxide-independent activation of sGC might be an innovative therapeutic approach for the treatment of liver fibrosis of necro-inflammatory and immunological origin.