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K + ‐channel inhibition reduces portal perfusion pressure in fibrotic rats and fibrosis associated characteristics of hepatic stellate cells
Author(s) -
Freise Christian,
Heldwein Silke,
Erben Ulrike,
Hoyer Joachim,
Köhler Ralf,
Jöhrens Korinna,
Patsenker Eleonora,
Ruehl Martin,
Seehofer Daniel,
Stickel Felix,
Somasundaram Rajan
Publication year - 2015
Publication title -
liver international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.873
H-Index - 110
eISSN - 1478-3231
pISSN - 1478-3223
DOI - 10.1111/liv.12681
Subject(s) - hepatic stellate cell , in vivo , extracellular matrix , hepatic fibrosis , fibrosis , biology , western blot , microbiology and biotechnology , chemistry , pathology , medicine , endocrinology , gene , biochemistry
Background & Aims In liver fibrosis, activated hepatic stellate cells ( HSC ) secrete excess extracellular matrix, thus, represent key targets for antifibrotic treatment strategies. Intermediate‐conductance Ca 2 + ‐activated K + ‐channels ( KC a3.1) are expressed in non‐excitable tissues affecting proliferation, migration and vascular resistance rendering KC a3.1 potential targets in liver fibrosis. So far, no information about KC a3.1 expression and their role in HSC exists. Aim was to quantify the KC a3.1 expression in HSC depending on HSC activation and investigation of antifibrotic properties of the specific KC a3.1 inhibitor TRAM ‐34 in vitro and in vivo . Methods KC a3.1 expression and functionality were studied in TGF ‐β1–activated HSC by quantitative real time PCR , western‐blot and patch‐clamp analysis respectively. Effects of TRAM ‐34 on HSC proliferation, cell cycle and fibrosis‐related gene expression were assessed by [ 3 H]‐thymidine incorporation, FACS ‐analysis and RT ‐ PCR respectively. In vivo , vascular resistance and KC a3.1 gene and protein expression were determined in bile duct ligated rats by in situ liver perfusion, Taqman PCR and immunohistochemistry respectively. Results Fibrotic tissues and TGF ‐β1‐activated HSC exhibited higher KC a3.1‐expressions than normal tissue and untreated cells. KC a3.1 inhibition with TRAM ‐34 reduced HSC proliferation by induction of cell cycle arrest and reduced TGF ‐β1‐induced gene expression of collagen I, alpha‐smooth muscle actin and TGF ‐β1 itself. Furthermore, TRAM ‐34 blocked TGF ‐β1‐induced activation of TGF ‐β signalling in HSC . In vivo , TRAM ‐34 reduced the thromboxane agonist‐induced portal perfusion pressure. Conclusion Inhibition of KC a3.1 with TRAM ‐34 downregulates fibrosis‐associated gene expression in vitro, and reduces portal perfusion pressure in vivo . Thus, KC a3.1 may represent novel targets for the treatment of liver fibrosis.