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Taurocholate-stimulated leukotriene C4 biosynthesis and leukotriene C4-stimulated choleresis in isolated rat liver

Sat, 31 Dec 1994 23:00:00 GMT

Title: Taurocholate-stimulated leukotriene C4 biosynthesis and leukotriene C4-stimulated choleresis in isolated rat liver Author(s) : Rodriguez-Ortigosa, C.M. (Carlos M.); Vesperinas, I. (Idoia); Qian, C. (Cheng); Quiroga, J. (Jorge); Medina, J.F. (Juan Francisco); Prieto, J. (Jesús) Abstract: BACKGROUND/AIMS: Cysteinyl-containing leukotrienes seem to exert a cholestatic effect. However, leukotriene inhibitors were found to reduce bile salt efflux in isolated rat hepatocytes, suggesting a role for leukotrienes in bile flow formation. METHODS: In the isolated rat liver, the effects of two different concentrations of leukotriene C4 on bile flow and bile salt excretion are analyzed, as well as the possible effect of taurocholate on the hepatic production of cysteinyl-containing leukotrienes. RESULTS: Leukotriene C4 (0.25 fmol) increased bile salt excretion (+22.2%; P < 0.05), whereas a much higher dose (0.25 x 10(6) fmol) showed the known cholestatic effect, reducing bile salt excretion (-25.9%; P < 0.01). These dose-dependent biphasic effects were specific because they could be prevented by the simultaneous administration of cysteinyl-containing leukotriene antagonists. On the other hand, taurocholate administration induced a dose-dependent increase in biliary excretion of cysteinyl-containing leukotrienes. Furthermore, taurocholate increased messenger RNA levels of 5-lipoxygenase, a key enzyme in leukotriene biosynthesis. Taurocholate increase of hepatocyte intracellular calcium was not significant, suggesting that taurocholate effects are not mediated by stimulation of calcium metabolism. CONCLUSIONS: These results constitute evidence for the existence of a positive feedback mechanism by which bile salts stimulate the synthesis of leukotrienes that, in turn, stimulate bile salt excretion.

Renal prostacyclin influences renal function in non-azotemic cirrhotic patients treated with furosemide

Mon, 31 Dec 1990 23:00:00 GMT

Title: Renal prostacyclin influences renal function in non-azotemic cirrhotic patients treated with furosemide Author(s) : Quiroga, J. (Jorge); Zozaya, J.M. (José Manuel); Labarga, P. (Pablo); Rodriguez-Ortigosa, C.M. (Carlos M.); Milazzo, A. (Alfredo); Prieto, J. (Jesús) Abstract: The influence of prostaglandins on renal function changes induced by furosemide was analyzed in 21 non-azotemic cirrhotic patients with ascites. Patients were studied in two periods of 120 min immediately before and after furosemide infusion (20 mg, ev). Furosemide caused an increase in creatinine clearance in 15 patients (group A: 99 +/- 7 vs. 129 +/- 5 ml/min; mean +/- S.E.) and a reduction in the remaining six (group B: 102 +/- 13 vs. 71 +/- 9 ml/min). Parallel changes were observed in the urinary excretion of 6-Keto-prostaglandin-F1 alpha (metabolite of renal prostacyclin) which augmented after furosemide in 14 of the 15 patients from group A (478 +/- 107 vs. 1034 +/- 159 pg/min, p less than 0.001) and decreased in all patients from group B (1032 +/- 240 vs. 548 +/- 136 pg/min, p less than 0.05). In contrast, the urinary excretion of prostaglandin E2 was stimulated by furosemide in all patients (group A, 92 +/- 19 vs. 448 +/- 60 pg/min, p less than 0.001; and group B, 209 +/- 63 vs. 361 +/- 25 pg/min, p less than 0.05). In all of the patients furosemide-induced changes (post- minus pre-furosemide values) in creatinine clearance were closely correlated in a direct and linear fashion with those in 6-Keto-prostaglandin-F1 alpha (r = 0.74; p less than 0.001). These changes were associated with a higher furosemide-induced natriuresis in group A than in group B (641 +/- 68 vs. 302 +/-- 46 mumol/min, p less than 0.001.

Insulin-like growth factor I improves intestinal barrier function in cirrhotic rats

Sat, 31 Dec 2005 23:00:00 GMT

Title: Insulin-like growth factor I improves intestinal barrier function in cirrhotic rats Author(s) : Lorenzo-Zuñiga, V. (V.); Rodriguez-Ortigosa, C.M. (Carlos M.); Bartoli, R. (R.); Martinez-Chantar, M.L. (María Luz); Martinez-Peralta, L. (L.); Pardo, A. (A.); Ojanguren, I. (I.); Quiroga, J. (Jorge); Planas, R. (R.); Prieto, J. (Jesús) Abstract: BACKGROUND AND AIMS: In liver cirrhosis, disruption of the intestinal barrier facilitates bacterial translocation and spontaneous bacterial peritonitis. Insulin-like growth factor I (IGF-I) is an anabolic hormone synthesised by hepatocytes that displays hepatoprotective activities and trophic effects on the intestine. The aim of this study was to investigate the effect of IGF-I on intestinal barrier function in cirrhotic rats. METHODS: In rats with carbon tetrachloride induced cirrhosis, we investigated the effect of IGF-I therapy on: (a) portal pressure; (b) intestinal histology and permeability to endotoxin and bacteria; (c) intestinal expression of cyclooxygenase 2 (COX-2) and tumour necrosis factor alpha (TNF-alpha), two factors that influence in a positive and negative manner, respectively, the integrity of the intestinal barrier; (d) intestinal permeability to 3H-mannitol in rats with bile duct ligation (BDL); and (e) transepithelial electrical resistance (TER) of polarised monolayers of rat small intestine epithelial cells. RESULTS: IGF-I therapy reduced liver collagen expression and portal pressure in cirrhotic rats, induced improvement in intestinal histology, and caused a reduction in bacterial translocation and endotoxaemia. These changes were associated with diminished TNF-alpha expression and elevated COX-2 levels in the intestine. IGF-I reduced intestinal permeability in BDL rats and enhanced barrier function of the monolayers of epithelial intestinal cells where lipopolysaccharide (LPS) caused a decrease in TER that was reversed by IGF-I. This effect of IGF-I was associated with upregulation of COX-2 in LPS treated enterocytes. CONCLUSIONS: IGF-I enhances intestinal barrier function and reduces endotoxaemia and bacterial translocation in cirrhotic rats. IGF-I therapy might be useful in the prevention of spontaneous bacterial peritonitis in liver cirrhosis.

S-adenosyl-L-methionine protects the liver against the cholestatic, cytotoxic, and vasoactive effects of leukotriene D4: a study with isolated and perfused rat liver

Tue, 31 Dec 1996 23:00:00 GMT

Title: S-adenosyl-L-methionine protects the liver against the cholestatic, cytotoxic, and vasoactive effects of leukotriene D4: a study with isolated and perfused rat liver Author(s) : Cincu, R.N. (Rafael N.); Rodriguez-Ortigosa, C.M. (Carlos M.); Vesperinas, I. (Idoia); Quiroga, J. (Jorge); Prieto, J. (Jesús) Abstract: Cysteinyl-leukotrienes can cause cholestasis and liver damage when administered at nanomolar concentrations. Using the isolated and perfused rat liver we analyzed whether S-adenosyl-L-methionine (SAMe) may protect this organ against the noxious effects of leukotriene-D4 (LTD4). We observed that a 2 nmol bolus of this compound decreased bile flow (-12.6% +/- 1.6%, P < .02), and bile salt excretion (-23.5% +/- 2.2%, P < .02; both compared with baseline values), caused the release of glutamic-oxaloacetic transaminase (GOT) and lactic dehydrogenase (LDH) to the hepatic effluent, and increased significantly the perfusion pressure as compared with a control group not receiving LTD4 (6.0 +/- 1.1 vs. 0.2 +/- 0.02 mm hg, respectively; P < .001). The cholestatic effect of LTD4 was attenuated by infusion of SAMe which, at rates of 67 and 100 microg/min, totally prevented the decrease in bile salt excretion. Likewise, in SAMe infused livers, the release to the effluent of GOT and LDH was lower than in the group receiving LTD4 only, and was even lower than in the control group. We also found that the increase in perfusion pressure induced by LTD4 was prevented by SAMe in a dose-dependent manner. Of interest, SAMe increased the biliary excretion of the eicosanoid in a dose-related fashion. We conclude that SAMe reverts the cholestatic, cytotoxic, and hemodynamic effects of LTD4 on the liver, and that these protective effects might be partly because of a stimulation of the biliary excretion of the leukotriene.

Effect of ursodeoxycholic acid on methionine adenosyltransferase activity and hepatic glutathione metabolism in rats

Mon, 31 Dec 2001 23:00:00 GMT

Title: Effect of ursodeoxycholic acid on methionine adenosyltransferase activity and hepatic glutathione metabolism in rats Author(s) : Rodriguez-Ortigosa, C.M. (Carlos M.); Cincu, R.N. (Rafael N.); Sanz, S. (S.); Ruiz, F. (F.); Quiroga, J. (Jorge); Prieto, J. (Jesús) Abstract: BACKGROUND AND AIMS: Both bile salts and glutathione participate in the generation of canalicular bile flow. In this work, we have investigated the effect of different bile salts on hepatic glutathione metabolism. METHODS: Using the isolated and perfused rat liver, we studied hepatic glutathione content, and metabolism and catabolism of this compound in livers perfused with taurocholate, ursodeoxycholate, or deoxycholate. RESULTS: We found that in livers perfused with ursodeoxycholate, levels of glutathione and the activity of methionine adenosyltransferase (an enzyme involved in glutathione biosynthesis) were significantly higher than in livers perfused with other bile salts. In ursodeoxycholate perfused livers, methionine adenosyltransferase showed a predominant tetrameric conformation which is the isoform with highest activity at physiological concentrations of substrate. In contrast, the dimeric form prevailed in livers perfused with taurocholate or deoxycholate. The hepatic activities of gamma-glutamylcysteine synthetase and gamma-glutamyltranspeptidase, enzymes involved, respectively, in biosynthetic and catabolic pathways of glutathione, were not modified by bile salts. CONCLUSIONS: Ursodeoxycholate specifically enhanced methionine adenosyltransferase activity and hepatic glutathione levels. As glutathione is a defensive substance against oxidative cell damage, our observations provide an additional explanation for the known hepatoprotective effects of ursodeoxycholate.

Expression of insulin-like growth factor I by activated hepatic stellate cells reduces fibrogenesis and enhances regeneration after liver injury

Fri, 31 Dec 2004 23:00:00 GMT

Title: Expression of insulin-like growth factor I by activated hepatic stellate cells reduces fibrogenesis and enhances regeneration after liver injury Author(s) : Sanz, S. (S.); Pucilowska, J.B. (J. B.); Liu, S. (S.); Rodriguez-Ortigosa, C.M. (Carlos M.); Lund, P.K. (P. K.); Brenner, D.A. (D. A.); Fuller, C.R. (C. R.); Simmons, J.G. (J. G.); Pardo, A. (A.); Martinez-Chantar, M.L. (María Luz); Fagin, J.A. (J. A.); Prieto, J. (Jesús) Abstract: BACKGROUND/AIM: Hepatic stellate cells (HSCs) express alpha-smooth muscle actin (alphaSMA) and acquire a profibrogenic phenotype upon activation by noxious stimuli. Insulin-like growth I (IGF-I) has been shown to stimulate HSCs proliferation in vitro, but it has been reported to reduce liver damage and fibrogenesis when given to cirrhotic rats. METHODS: The authors used transgenic mice (SMP8-IGF-I) expressing IGF-I under control of alphaSMA promoter to study the influence of IGF-I synthesised by activated HSCs on the recovery from liver injury. RESULTS: The transgene was expressed by HSCs from SMP8-IGF-I mice upon activation in culture and in the livers of these animals after CCl4 challenge. Twenty four hours after administration of CCl4 both transgenic and wild type mice showed similar extensive necrosis and increased levels of serum transaminases. However at 72 hours SMP8-IGF-I mice exhibited lower serum transaminases, reduced hepatic expression of alphaSMA, and improved liver morphology compared with wild type littermates. Remarkably, at this time all eight CCl4 treated wild type mice manifested histological signs of liver necrosis that was severe in six of them, while six out of eight transgenic animals had virtually no necrosis. In SMP8-IGF-I mice robust DNA synthesis occurred earlier than in wild type animals and this was associated with enhanced production of HGF and lower TGFbeta1 mRNA expression in the SMP8-IGF-I group. Moreover, Colalpha1(I) mRNA abundance at 72 hours was reduced in SMP8-IGF-I mice compared with wild type controls. CONCLUSIONS: Targeted overexpression of IGF-I by activated HSCs restricts their activation, attenuates fibrogenesis, and accelerates liver regeneration. These effects appear to be mediated in part by upregulation of HGF and downregulation of TGFbeta1. The data indicate that IGF-I can modulate the cytokine response to liver injury facilitating regeneration and reducing fibrosis.

The epidermal growth factor receptor ligand amphiregulin is a negative regulator of hepatic acute-phase gene expression

Wed, 31 Dec 2008 23:00:00 GMT

Title: The epidermal growth factor receptor ligand amphiregulin is a negative regulator of hepatic acute-phase gene expression Author(s) : Pardo-Saganta, A. (Ana); Latasa, M.U. (María Ujué); Castillo, J. (Josefa); Alvarez-Asiain, L. (Laura); Perugorria, M.J. (María J.); Sarobe, P. (Pablo); Rodriguez-Ortigosa, C.M. (Carlos M.); Prieto, J. (Jesús); Berasain, C. (Carmen); Santamaria, M. (Mónica); Avila, M.A. (Matías Antonio) Abstract: BACKGROUND/AIMS: The modulation of the hepatic acute-phase reaction (APR) that occurs during inflammation and liver regeneration is important for allowing normal hepatocellular proliferation and the restoration of homeostasis. Activation of acute-phase protein (APP) gene expression by interleukin-6 (IL-6)-type cytokines is thought to be counteracted by growth factors released during hepatic inflammation and regeneration. The epidermal growth factor receptor (EGFR) ligand amphiregulin (AR) is readily induced by inflammatory signals and plays a nonredundant protective role during liver injury. In this paper, we investigated the role of AR as a modulator of liver APP gene expression. METHODS: Expression of APP genes was measured in the livers of AR(+/+) and AR(-/-)mice during inflammation and regeneration and in cultured liver cells treated with AR and oncostatin M (OSM). Crosstalk between AR and OSM signalling was studied. RESULTS: APP genes were overexpressed in the livers of AR(-/-) mice during inflammation and hepatocellular regeneration. In cultured AR-null hepatocytes and human hepatocellular carcinoma (HCC) cells after AR knockdown, APP gene expression is enhanced. AR counteracts OSM-triggered signal transducer and activator of transcription 3 signalling in hepatocytes and attenuates APP gene transcription. CONCLUSIONS: Our data support the relevance of EGFR-mediated signalling in the modulation of cytokine-activated pathways. We have identified AR as a key regulator of hepatic APP gene expression during inflammation and liver regeneration.

Bicarbonate-rich choleresis induced by secretin in normal rat is taurocholate-dependent and involves AE2 anion exchanger

Sat, 31 Dec 2005 23:00:00 GMT

Title: Bicarbonate-rich choleresis induced by secretin in normal rat is taurocholate-dependent and involves AE2 anion exchanger Author(s) : Banales, J.M. (Jesús M.); Arenas, F. (Fabián); Rodriguez-Ortigosa, C.M. (Carlos M.); Saez, E. (Elena); Uriarte, I. (Iker); Doctor, R.B. (R. Brian); Prieto, J. (Jesús); Medina, J.F. (Juan Francisco) Abstract: Canalicular bile is modified along bile ducts through reabsorptive and secretory processes regulated by nerves, bile salts, and hormones such as secretin. Secretin stimulates ductular cystic fibrosis transmembrane conductance regulator (CFTR)-dependent Cl- efflux and subsequent biliary HCO3- secretion, possibly via Cl-/HCO3- anion exchange (AE). However, the contribution of secretin to bile regulation in the normal rat, the significance of choleretic bile salts in secretin effects, and the role of Cl-/HCO3- exchange in secretin-stimulated HCO3- secretion all remain unclear. Here, secretin was administered to normal rats with maintained bile acid pool via continuous taurocholate infusion. Bile flow and biliary HCO3- and Cl- excretion were monitored following intrabiliary retrograde fluxes of saline solutions with and without the Cl- channel inhibitor 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) or the Cl-/HCO3- exchange inhibitor 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS). Secretin increased bile flow and biliary excretion of HCO3- and Cl-. Interestingly, secretin effects were not observed in the absence of taurocholate. Whereas secretin effects were all blocked by intrabiliary NPPB, DIDS only inhibited secretin-induced increases in bile flow and HCO3- excretion but not the increased Cl- excretion, revealing a role of biliary Cl-/HCO3- exchange in secretin-induced, bicarbonate-rich choleresis in normal rats. Finally, small hairpin RNA adenoviral constructs were used to demonstrate the involvement of the Na+-independent anion exchanger 2 (AE2) through gene silencing in normal rat cholangiocytes. AE2 gene silencing caused a marked inhibition of unstimulated and secretin-stimulated Cl-/HCO3- exchange. In conclusion, maintenance of the bile acid pool is crucial for secretin to induce bicarbonate-rich choleresis in the normal rat and that this occurs via a chloride-bicarbonate exchange process consistent with AE2 function.

Biliary secretion of S-nitrosoglutathione is involved in the hypercholeresis induced by ursodeoxycholic acid in the normal rat

Thu, 31 Dec 2009 23:00:00 GMT

Title: Biliary secretion of S-nitrosoglutathione is involved in the hypercholeresis induced by ursodeoxycholic acid in the normal rat Author(s) : Rodriguez-Ortigosa, C.M. (Carlos M.); Banales, J.M. (Jesús M.); Olivas, I. (Israel); Uriarte, I. (Iker); Marin, J.J.G (Jose J.G.); Corrales, F.J. (Fernando José); Medina, J.F. (Juan Francisco); Prieto, J. (Jesús) Abstract: Ursodeoxycholic acid (UDCA) induces bicarbonate-rich hypercholeresis by incompletely defined mechanisms that involve the stimulation of adenosine triphosphate (ATP) release from cholangiocytes. As nitric oxide (NO) at a low concentration can stimulate a variety of secretory processes, we investigated whether this mediator could be implicated in the choleretic response to UDCA. Our in vivo experiments with the in situ perfused rat liver model in anesthetized rats, showed that UDCA infusion increased the biliary secretion of NO derivatives, hepatic inducible NO synthase expression, and NO synthase activity in liver tissue. UDCA also stimulated NO release by isolated rat hepatocytes. In contrast to UDCA, cholic acid was a poor inducer of NO secretion, and tauroursodeoxycholic acid showed no effect on NO secretion. Upon UDCA administration, NO was found in bile as low-molecular-weight nitrosothiols, of which S-nitrosoglutathione (GSNO) was the predominant species. UDCA-stimulated biliary NO secretion was abolished by the inhibition of inducible NO synthase with N(omega)-nitro-L-arginine methyl ester in isolated perfused livers and also in rats whose livers were depleted of glutathione with buthionine sulfoximine. Moreover, the biliary secretion of NO species was significantly diminished in UDCA-infused transport mutant [ATP-binding cassette C2 (ABCC2)/multidrug resistance-associated protein 2 (Mrp2)-deficient] rats, and this finding was consistent with the involvement of the glutathione carrier ABCC2/Mrp2 in the canalicular transport of GSNO. It was particularly noteworthy that in cultured normal rat cholangiocytes, GSNO activated protein kinase B, protected against apoptosis, and enhanced UDCA-induced ATP release to the medium; this effect was blocked by phosphoinositide 3-kinase inhibition. Finally, retrograde GSNO infusion into the common bile duct increased bile flow and biliary bicarbonate secretion. Conclusion: UDCA induces biliary secretion of GSNO, which contributes to stimulating ductal secretion.

Oral methylthioadenosine administration attenuates fibrosis and chronic liver disease progression in Mdr2-/- mice

Thu, 31 Dec 2009 23:00:00 GMT

Title: Oral methylthioadenosine administration attenuates fibrosis and chronic liver disease progression in Mdr2-/- mice Author(s) : Latasa, M.U. (María Ujué); Gil-Puig, C. (Carmen); Fernandez-Barrena, M. G. (Maite G.); Rodriguez-Ortigosa, C.M. (Carlos M.); Banales, J.M. (Jesús M.); Urtasun, R. (Raquel); Goñi, S. (Saioa); Mendez, M. (Miriam); Arcelus, S. (Sara); Juanarena, N. (Nerea); Recio, J.A. (Juan A.); Lotersztajn, S. (Sophie); Prieto, J. (Jesús); Berasain, C. (Carmen); Corrales, F.J. (Fernando José); Lecanda, J. (Jon); Avila, M.A. (Matías Antonio) Abstract: BACKGROUND: Inflammation and fibrogenesis are directly related to chronic liver disease progression, including hepatocellular carcinoma (HCC) development. Currently there are few therapeutic options available to inhibit liver fibrosis. We have evaluated the hepatoprotective and anti-fibrotic potential of orally-administered 5'-methylthioadenosine (MTA) in Mdr2(-/-) mice, a clinically relevant model of sclerosing cholangitis and spontaneous biliary fibrosis, followed at later stages by HCC development. METHODOLOGY: MTA was administered daily by gavage to wild type and Mdr2(-/-) mice for three weeks. MTA anti-inflammatory and anti-fibrotic effects and potential mechanisms of action were examined in the liver of Mdr2(-/-) mice with ongoing fibrogenesis and in cultured liver fibrogenic cells (myofibroblasts). PRINCIPAL FINDINGS: MTA treatment reduced hepatomegaly and liver injury. α-Smooth muscle actin immunoreactivity and collagen deposition were also significantly decreased. Inflammatory infiltrate, the expression of the cytokines IL6 and Mcp-1, pro-fibrogenic factors like TGFβ2 and tenascin-C, as well as pro-fibrogenic intracellular signalling pathways were reduced by MTA in vivo. MTA inhibited the activation and proliferation of isolated myofibroblasts and down-regulated cyclin D1 gene expression at the transcriptional level. The expression of JunD, a key transcription factor in liver fibrogenesis, was also reduced by MTA in activated myofibroblasts. CONCLUSIONS/SIGNIFICANCE: Oral MTA administration was well tolerated and proved its efficacy in reducing liver inflammation and fibrosis. MTA may have multiple molecular and cellular targets. These include the inhibition of inflammatory and pro-fibrogenic cytokines, as well as the attenuation of myofibroblast activation and proliferation. Downregulation of JunD and cyclin D1 expression in myofibroblasts may be important regarding the mechanism of action of MTA. This compound could be a good candidate to be tested for the treatment of (biliary) liver fibrosis.