Andreas Knorr

Nitric Oxide-independent Activation of Soluble Guanylate Cyclase by BAY 60-2770 in Experimental Liver Fibrosis

UNLABELLEDnLiver 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.nnnOBJECTIVEnHere 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.nnnMETHODSnThe 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.nnnRESULTSnBAY 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.nnnCONCLUSIONnNitric oxide-independent activation of sGC might be an innovative therapeutic approach for the treatment of liver fibrosis of necro-inflammatory and immunological origin.

Cardiovascular effects of a novel potent and highly selective azaindole-based inhibitor of Rho-kinase

Rho‐kinase (ROCK) has been implicated in the pathophysiology of altered vasoregulation leading to hypertension. Here we describe the pharmacological characterization of a potent, highly selective and orally active ROCK inhibitor, the derivative of a class of azaindoles, azaindole 1(6‐chloro‐N 4‐{3,5‐difluoro‐4‐[(3‐methyl‐1H‐pyrrolo[2,3‐b]pyridin‐4‐yl)oxy]‐phenyl}pyrimidine‐2,4‐diamine).

Design and Synthesis of Potent and Selective Azaindole‐Based Rho Kinase (ROCK) Inhibitors

Rho kinase plays a pivotal role in several cellular processes such as vasoregulation, making it a suitable target for the treatment of hypertension and related disorders. We discovered a new compound class of Rho kinase (ROCK) inhibitors containing a 7‐azaindole hinge‐binding scaffold tethered to an aminopyrimidine core. Herein we describe the structure–activity relationships elucidated through biochemical and functional assays. The introduction of suitable substituents at the 3‐position of the bicyclic moiety led to an increase in activity, which was required to design compounds with favorable pharmacokinetic profile. Azaindole 32 was identified as a highly selective and orally available ROCK inhibitor able to cause a sustained blood pressure reduction inu2005vivo.

Inactivated Orf virus (Parapoxvirus ovis) elicits antifibrotic activity in models of liver fibrosis

Inactivated Orf virus (ORFV, Parapoxvirus ovis) demonstrates strong antiviral activity in animal models including a human hepatitis B virus (HBV)‐transgenic mouse. In addition, expression of interferon (IFN)‐γ and interleukin‐10 (IL‐10) was induced after administration of inactivated ORFV in these mice. IFN‐γ and IL‐10 are known to elicit antifibrotic activity. We therefore aimed to study antifibrotic activity of inactivated ORFV in models of liver fibrosis.

Inactivated Orf Virus Shows Antifibrotic Activity and Inhibits Human Hepatitis B Virus (HBV) and Hepatitis C Virus (HCV) Replication in Preclinical Models

Inactivated orf virus (iORFV), strain D1701, is a potent immune modulator in various animal species. We recently demonstrated that iORFV induces strong antiviral activity in animal models of acute and chronic viral infections. In addition, we found D1701-mediated antifibrotic effects in different rat models of liver fibrosis. In the present study, we compare iORFV derived from two different strains of ORFV, D1701 and NZ2, respectively, with respect to their antifibrotic potential as well as their potential to induce an antiviral response controlling infections with the hepatotropic pathogens hepatitis C virus (HCV) and hepatitis B virus (HBV). Both strains of ORFV showed anti-viral activity against HCV in vitro and against HBV in a transgenic mouse model without signs of necro-inflammation in vivo. Our experiments suggest that the absence of liver damage is potentially mediated by iORFV-induced downregulation of antigen cross-presentation in liver sinus endothelial cells. Furthermore, both strains showed significant anti-fibrotic activity in rat models of liver fibrosis. iORFV strain NZ2 appeared more potent compared to strain D1701 with respect to both its antiviral and antifibrotic activity on the basis of dosages estimated by titration of active virus. These results show a potential therapeutic approach against two important human liver pathogens HBV and HCV that independently addresses concomitant liver fibrosis. Further studies are required to characterize the details of the mechanisms involved in this novel therapeutic principle.

Antifibrotic effects of an sGC activator in rat models of liver fibrosis

Background Liver fibrosis and cirrhosis are late complications common to liver diseases of different etiology such as viral hepatitis and alcoholic liver disease. Irrespective of the initial cause of liver disease, activation of hepatic stellate cells is a crucial step in the fibrotic pathomechanism. Activated hepatic stellate cells produce excess collagen as well as profibrotic cytokines and change to a contractile phenotype which reduces the diameter of the hepatic sinusoids. Activation of hepatic stellate cells is reduced by an increase in intracellular cyclic guanosine monophoshate (cGMP). Stable cGMP analogues also reduce the contractile response of hepatic stellate cells. However, cGMP production is downregulated in the cirrhotic liver due to reduced activity of the endothelial NO synthase. The recently discovered activators of soluble guanylate cyclase (sGC) increase cGMP production independently of NO. We therefore investigated the effects of an sGC activator in two classical rat models of liver fibrosis, the pig serum model and the carbon tetrachloride model.