Arginine vasopressin induces contraction and stimulates growth of cultured human hepatic stellate cells

Nan

Pharmacology & Toxicology

et al. 2000

Tetrandrine, an alkaloid isolated from the Chinese medicinal herb Stephania tetrandra, has been shown to elicit antifibrotic effects in various cell types. In the present study, the effect of tetrandrine on liver fibrosis was investigated by using bile duct ligation and scission in rats as a model of hepatic fibrosis. Treatment with tetrandrine in fibrotic rats reduced serum aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase levels to 72%, 52% and 51% that of controls at 10 mg/kg/day, respectively. Liver hydroxyproline contents in tetrandrine-treated rats with bile duct ligation and scission were also reduced to 65% of that of control rats with bile duct ligation and scission at 10 mg/kg/day. The morphological characteristics of fibrotic liver, which appeared in control bile duct ligation and scission group, were improved in tetrandrine-treated bile duct ligation and scission group. We also examined the effect of tetrandrine on cultured rat hepatic stellate cells, which plays an important role in the pathogenesis of hepatic fibrosis, activation to investigate whether it could act mainly by direct action on rat hepatic fibroblastic cells. In cultured rat hepatic stellate cells, tetrandrine reduced DNA synthesis to 57% of control hepatic stellate cells at 10 mg/ml without affecting cell viability. Smooth muscle-a-actin expression, the phenotypic marker of activated hepatic stellate cells, was also decreased. We conclude that tetrandrine has an antifibrotic effect on liver fibrosis in rats induced by bile duct ligation and scission, indicating that it might exert a direct effect on rat hepatic stellate cells.Hepatic fibrosis is a consequence of severe liver damage that occurs in many patients with chronic liver disease. Regardless of many different causes, hepatic fibrosis is characterized by increased and altered deposition of newly formed extracellular matrix components such as collagens, proteoglycans, fibronectin and hyaluronic acid (Friedman 1993), leading to the complication of portal hypertension and hepatic failure.In the injured liver, these extracellular matrix components are produced in hepatic stellate cells in the space of Disse, which function in intact liver lobules as the primary storage area for retinoids (Hendrisks et al. 1985). During the course of ongoing liver fibrogenesis, hepatic stellate cells acquire myofibroblastic features, proliferate (Friedman et al. 1989;Hautekeete & Geerts 1997), synthesize increased amounts of extracellular matrix components (Shiratori et al. 1987) and express smooth muscle-a-actin . The transformation of hepatic stellate cells into myofibroblast-like cells is recognized as a critical step in hepatic fibrosis. Therefore, this cell type is an important target for antifibrotic therapy.Tetrandrine is a bis-benzyl isoquinoline alkaloid derived from Stephania tetrandra (Moore). This compound has been characterized pharmacologically to exhibit hypotensive, immunosuppressive properties (Sutter & Wang 1993), and inhibition of lipid perox...

Section: Discussionmentioning

confidence: 99%

Effect of Tetrandrine on Experimental Hepatic Fibrosis Induced by Bile Duct Ligation and Scission in Rats

Nan

Pharmacology & Toxicology

et al. 2000

“…After 2 hours, cells were washed and HSE cell purity assessed by ovalbumin endocytosis (Ͼ95%). Primary cultured human HSCs were obtained in their activated phenotype by outgrowth from explants of nontumoral tissue 22 and cultured in noncoated wells (0.5 ϫ 10 4 HSCs/cm 2 ) in DMEM culture medium supplemented with 10% FCS. Cell isolates were characterized by a positive staining for ASMA and used at passage 2-6.…”

Section: Methodsmentioning

confidence: 99%

Proangiogenic Role of Tumor–Activated Hepatic Stellate Cells in Experimental Melanoma Metastasis

2003

Myofibroblasts infiltrate malignant liver tumors, although their pathogenic implications are unclear. Immunohistochemical detection of ␣-smooth muscle actin, glial fibrillary acidic protein (GFAP), and CD31 and CD34 expression was used to analyze the contribution of myofibroblasts to angiogenesis in hepatic metastasis produced by intrasplenically-injected B16 melanoma (B16M). Because activated hepatic stellate cells (HSCs) are oxygen-sensing myofibroblasts producing vascular endothelial growth factor (VEGF), the effect of B16M and human A375 melanoma supernatants on VEGF production by immortalized rat HSC line T6 and primary cultured human HSCs also was studied under an hypoxic atmosphere mimicking a tumor microenvironment. Myofibroblast infiltration preceded endothelium recruitment in avascular micrometastasis and generated specific stroma for sinusoidal-type and portal-type angiogeneses. Thereafter, myofibroblasts and endothelial cells colocalized within both angiogenic patterns and their numerical densities correlated with metastasis development. Myofibroblasts often were GFAPpositive, suggesting an HSC origin. Melanoma supernatants stimulated VEGF messenger RNA and protein synthesis by HSCs. These effects were potentiated by hypoxia. VEGF up-regulation was accompanied by increased expression of cyclooxygenase type 2 (COX-2) and PGE2 synthesis. HSC production of VEGF decreased under COX-2 inhibition, whereas it was increased by exogenous PGE2. The high VEGF expression in HSCs induced by melanoma factors and hypoxia resulted in mitogenic, antiapoptotic, and motogenic stimulation of both murine hepatic sinusoidal endothelium and human umbilical vein endothelium. In conclusion, temporal and positional relationships evolve between myofibroblast and endothelium recruitment during metastasis development. Mechanistically, hypoxic induction of VEGF in tumor-activated HSCs may create a proangiogenic microenvironment, facilitating endothelial cell recruitment and survival during hepatic metastasis transition from an avascular to a vascular stage. (HEPATOLOGY 2003;37:674-685.)

“…15,19 Briefly, after a combined digestion of liver tissue with collagenase and pronase (Boehringer Mannheim, Mannheim, Germany), the resulting cell suspension was filtered through a 105-µm nylon gauze. HSCs were separated from other nonparenchymal cells by ultracentrifugation over gradients of stractan (Cellshep Isotonic Solution; Larex International Co, Tacoma, WA).…”

Section: Isolation and Culture Of Human And Rat Hepatic Stellate Cellmentioning

confidence: 99%

“…[4][5][6][7][8][9][10] Moreover, HSCs have receptors for a large number of vasoconstrictor substances, including endothelin-1, arginine vasopressin, thrombin, thromboxanes, and angiotensin II. 6,8,[11][12][13][14][15] Finally, the stimulation of HSCs in culture with these vasoconstrictor substances is associated with a marked increase in intracellular calcium concentration ([Ca 2ϩ ] i ) and cell contraction, 6,[8][9][10][11][12][13][14][15] suggesting that the contractile function of HSCs may be regulated by the action of vasoconstrictors.In contractile cells, the effects of vasoconstrictor agonists may be attenuated by the action of vasodilators. In fact, the state of contraction/relaxation of contractile cells is dependent on the interaction between vasoconstrictor and vasodilator factors.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Atrial natriuretic peptide antagonizes endothelin-induced calcium increase and cell contraction in cultured human hepatic stellate cells

et al. 1999

Several lines of evidence indicate that hepatic stellate cells (HSCs), besides their crucial role in the increased synthesis of extracellular matrix components that occurs in chronic liver diseases, may participate in the regulation of sinusoidal blood flow. [1][2][3] Morphological studies have shown that HSCs have numerous cell processes that surround the sinusoids and contain cytosolic proteins characteristic of contractile cells. [4][5][6][7][8][9][10] Moreover, HSCs have receptors for a large number of vasoconstrictor substances, including endothelin-1, arginine vasopressin, thrombin, thromboxanes, and angiotensin II. 6,8,[11][12][13][14][15] Finally, the stimulation of HSCs in culture with these vasoconstrictor substances is associated with a marked increase in intracellular calcium concentration ([Ca 2ϩ ] i ) and cell contraction, 6,[8][9][10][11][12][13][14][15] suggesting that the contractile function of HSCs may be regulated by the action of vasoconstrictors.In contractile cells, the effects of vasoconstrictor agonists may be attenuated by the action of vasodilators. In fact, the state of contraction/relaxation of contractile cells is dependent on the interaction between vasoconstrictor and vasodilator factors. 16 In clear contrast with the large amount of information available on the effects of vasoconstrictor factors on HSCs, little is known about the effects of vasodilating substances on these cells. It has been shown that prostaglandins and nitric oxide produce relaxation of HSCs in culture and reduce the effects of vasoconstrictor agents, which suggests that these vasodilator factors may act as paracrine or autocrine regulators of HSCs' contractility. 10,12 However, it is not known whether the contractile function of HSCs may also be regulated by circulating vasodilator substances. One of the most important circulating vasodilators is atrial natriuretic peptide (ANP), a peptide synthesized in atrial myocytes, which besides its potent natriuretic action has important effects in the circulation by antagonizing the effects of vasoconstrictors. 17,18 Therefore, the aims of the current study were to determine (1) whether human HSCs have receptors for ANP, and (2) whether the stimulation of human HSCs with ANP in vitro reduces the effects elicited by contractile agonists on these cells. MATERIALS AND METHODSIsolation and Culture of Human and Rat Hepatic Stellate Cells. Human HSCs were isolated from fragments of normal human livers obtained from resections of liver metastases as described in detail elsewhere. 15,19 Briefly, after a combined digestion of liver tissue with