Oral application of 1,7-dimethylxanthine (paraxanthine) attenuates the formation of experimental cholestatic liver fibrosis.

摘要

Aim: Several epidemiological studies suggest a beneficial effect of coffee consumption on the formation and progression of fibrogenic diseases, particularly of the liver. Recent data now point to a modulation of transforming growth factor-beta (TGF-beta) signaling by paraxanthine (1,7-dimethylxanthine [1,7-DMX]), the demethylated primary metabolite of caffeine Methods: Twenty adult Sprague-Dawley rats were bile duct ligated (BDL) or sham operated with or without concomitant oral 1,7-DMX (1 mM) application. Serum was investigated by standard biochemical analysis, in-house connective tissue growth factor (CTGF), enzyme linked immunosorbent assay (ELISA) or liquid chromatography-mass spectrometry analysis. Liver tissue was stained using hematoxylin-eosin (HE) and Sirius-red staining. Whole liver lysates, primary rat hepatocytes (PC) and hepatic stellate cells (HSC) were investigated by CTGF, and total Smad2/3 Western blot analysis, CTGF reporter gene assay or an in-house malondialdehyde ELISA. Results: The in vitro 50% inhibitory dose (ID50) of 1,7-DMX was 0.95 mM by for CTGF promoter activity and protein expression in PC and 1.25 mM for protein expression in HSC. Oral 1,7-DMX application (1 mM) attenuated cholestatic hepatocellular injury in vivo as determined by biochemical serum analysis and reduced intercellular collagen deposition in the cholestatic rat liver (HE- and Sirius-red staining). Western Blot analysis of whole liver lysates revealed a reduction of intrahepatic concentrations of Smad2/3 and CTGF following oral 1,7-DMX intake. However, serum CTGF concentrations were not reduced in 1,7-DMX treated BDL rats. Oral 1,7-DMX furthermore led to a reduction of intrahepatic lipid peroxidation (malondialdehyde concentrations) as markers of oxidative stress in BDL rats. Conclusion: Our pilot study warrants further studies of 1,7-DMX as a potential new drug to fight fibrotic processes, not just of the liver.