Salvianolic acid B lowers portal pressure in cirrhotic rats and attenuates contraction of rat hepatic stellate cells by inhibiting RhoA signaling pathway

Abstract

The contraction of hepatic stellate cells (HSCs) has a critical role in the regulation of intrahepatic vascular resistance and portal hypertension. Previous studies have confirmed that salvianolic acid B (Sal B) is effective against liver fibrosis. In the present study, we evaluated the effect of Sal B on portal hypertension and on HSCs contractility. Liver cirrhosis was induced in rats by peritoneal injection of dimethylnitrosamine and the portal pressure was measured. HSCs contraction was evaluated by collagen gel contraction assay. Glycerol-urea gel electrophoresis was performed to determine the phosphorylation of myosin light chain 2 (MLC2). F-actin stress fiber polymerization was detected by fluorescein isothiocyanate-labeled phalloidin. Intracellular Ca 2 þ and RhoA signaling activation were also measured. Sal B effectively reduced the portal pressure in DMN-induced cirrhotic rats. It decreased the contraction by endothelin-1 (ET-1)-activated HSCs by B66.5% and caused the disassembly of actin stress fibers and MLC2 dephosphorylation. Although Sal B reduced ET-1-induced intracellular Ca 2 þ increase, blocking Ca 2 þ increase completely by BAPTA-AM, a Ca 2 þ chelator, barely affected the magnitude of contraction. Sal B decreased ET-1-induced RhoA and Rho-associated coiled coil-forming protein kinase (ROCK) II activation by 66.84% and by 76.79%, respectively, and inhibited Thr 696 phosphorylation of MYPT1 by 80.09%. In vivo, Sal B lowers the portal pressure in rats with DMN-induced cirrhosis. In vitro, Sal B attenuates ET-1-induced HSCs contraction by inhibiting the activation of RhoA and ROCK II and the downstream MYPT1 phosphorylation at Thr 696 . We consider Sal B a potential candidate for the pharmacological treatment of portal hypertension.

Translating an Understanding of the Pathogenesis of Hepatic Fibrosis to Novel Therapies

“…Stellate cell contraction has been reported to be mediated by Ca++ dependent and independent mechanisms 63–66 . Stellate cell contraction has a multitude of effects in the injured liver including in perisinuoidal constriction and portal hypertension, and may also lead to the collapse and shrunken state of cirrhotic livers 45 .…”

“…Stellate cell contraction has a multitude of effects in the injured liver including in perisinuoidal constriction and portal hypertension, and may also lead to the collapse and shrunken state of cirrhotic livers 45 . Stellate cell contractility is likely tied to multiple different systems, including the endothelin, angiotensin, adrenergic, and perhaps other systems 44, 45, 66–71 .…”

Effect of QSKL on MAPK and RhoA Pathways in a Rat Model of Heart Failure

“…This inhibitory effect on RhoA/ROCK could be exerted by the effective components of QSKL. Salvianolic acid B, one of the major effective constituents identified in Salvia Miltiorrhiza Bunge, has been shown to inhibit the RhoA signaling pathway in cirrhotic rats [30]. Other components of QSKL, such as astragaloside IV, luteolin, and tanshinone IIA, have also been shown to have inhibitory effects on the RhoA/ROCK pathway under various pathological conditions [31–34].…”

Traditional Chinese medicine for treatment of liver diseases: progress, challenges and opportunities

“…FZHYC can also promote apoptosis of activated HSCs, inhibit synthesis and secretion of collagen, inhibit angiogenesis and promote degradation of collagen [59] . Studies showed that FZHYC achieved its antifibrotic activity through multiple signal pathways and targets [57,58,[60][61][62][63] , such as transforming growth factor β-1 (TGF-β1), SMADs, insulin-like growth factors-1 (IGF-1), phosphatidylinositol 3-kinase (PI3K), extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (p38 MAPK), RhoA/Rho-associated coiled-coil forming protein kinase (ROCK) and renin-angiotensin system (RAS) signaling pathways [64,65] .…”