Effect of ursodeoxycholic acid on serum liver enzymes and bile acid metabolism in chronic active hepatitis C virus infection

Aim:  Many reports have revealed ursodeoxycholic acid (UDCA) to be effective against chronic hepatitis C virus (HCV). However, some cases resist this therapy and the mechanism of action remains unclear. In this study, UDCA was administered to patients with chronic HCV and the correlation between the bile acids of the biliary bile and serum and the drug efficacy was investigated.
Methods:  Fifteen patients were given 600 mg/day of UDCA for more than 24 weeks. The serum bile acid concentrations and biliary and serum bile acid were collected before and after 24 weeks of UDCA treatment, and composition determined by high-performance liquid chromatography.
Results:  The treatment was effective in nine cases (ALT decreased to less than twice the normal values 80 IU/L) and ineffective in six cases. There was no significant difference in the serum bile acid concentrations before and after UDCA treatment between the values of both cases. After UDCA treatment, the serum percentage of UDCA (effective, 62.5 ± 2.0; ineffective, 53.5 ± 2.5, ( P  = 0.02)) and the percentage of chenodeoxycholic acid (CDCA) showed no remarkable changes. In the biliary bile the percentage of CDCA (effective, 30.9 ± 2.0; ineffective, 20.0 ± 3.0, ( P  = 0.007)) and the percentage of UDCA showed no remarkable changes.
Conclusion:  In the effective cases, the percentage of UDCA in the serum and the percentage of CDCA in biliary bile were significantly higher than in the ineffective cases. This indicates that, when effective, CDCA decreases in hepatocytes and this reduction contributes to hepatoprotection.     

Urinary bile acid sulfate levels in patients with hepatitis C virus-related chronic liver diseases

Aim:  Urinary bile acids are mainly conjugated with sulfuric acid, and urinary sulfated bile acid (USBA) levels in hepatobiliary diseases have been reported. However, the relationship between USBA and fasting serum total bile acid (TBA) has not been studied in hepatobiliary diseases. In the present study, we measured USBA levels in patients with hepatitis C virus-related chronic liver diseases, and the relationship between TBA and various laboratory tests was studied.
Methods:  USBA was measured using an automatic assay kit in 66 patients with chronic hepatitis and 28 patients with liver cirrhosis, and its relationship between TBA and various laboratory tests was studied.
Results:  The median USBA level was 10.7 µmol/g creatinine in patients with chronic hepatitis and 41.1 µmol/g creatinine in liver cirrhosis ( P  = 0.000). More patients with chronic hepatitis had elevated USBA levels (61%) compared to TBA level (39%) ( P  = 0.002). USBA level was well correlated with TBA (r_s = 0.680), and negatively correlated with albumin (r_s = −0.488), prothrombin time (r_s = −0.385) and platelet counts (r_s = −0.394). In patients with liver cirrhosis, USBA was significantly elevated in Child–Pugh class B compared to Child–Pugh class A ( P  = 0.036).
Conclusion:  Although the metabolic pathways of USBA and TBA are different, these levels correlated very well, and USBA is considered to be a useful indicator of hepatic function like TBA in patients with chronic hepatitis C.     

Effect of ursodeoxycholic acid administration on bile duct proliferation and cholestasis in bile duct ligated rat

The origin, mechanism, and significance of the bile duct proliferation (BDP) associated with cholestasis remain unexplained. This study examined the effect of oral administration of ursodeoxycholic acid (UDCA) on both BDP and cholestasis in the rat. After bile duct ligation, male Sprague-Dawley rats were treated for 30 days with either UDCA (5 mg/day) (group A) or saline solution (group B). Animals were sacrificed at day 30. The serum activity of aminotransferase (ALT, AST), alkaline phosphatase, and -glutamyltransferase (GGT) was significantly lower (P<0.01) in the UDCA-treated rats. Total serum bilirubin and total serum bile acids were lower (P<0.001) in group A. Moreover, the control of BA in bile was reduced also (P<0.02). Conversely, serum cholesterol levels were not different between the two groups. Histological examination showed that the number of ductular cells in the portal areas was significantly (P<0.001) reduced in UDCA-treated as compared to saline-treated rats. The replication activity, assessed as the number of bromodeoxyuridine-positive cells, was also significantly lower in treated animals (33±11 vs 64±22 per 1000 cells;P<0.001). Lobular bile ductules were three times larger in group B, and extrahepatic duct measurements confirmed this increase in size of the larger biliary ducts (P<0.001). These findings demonstrate that UDCA reduces BDP in response to BD ligation. Although the mechanism(s) of this effect is still hypothetical, UDCA may reduce the level of irritating bile salts such as chenodeoxycholic acid and lithocolate and increase periductular bile acid recirculation. These data support the beneficial effect of UDCA treatment in chronic cholestatic disease.     

Urinary bile acid sulfate levels in patients with primary biliary cirrhosis

Aim: Urinary bile acids are mainly conjugated with sulfuric acid. In a previous work, we demonstrated that the levels of urinary sulfated bile acids (USBA) and serum total bile acids (TBA) were correlated very well and also that USBA was considered to be a more useful indicator of hepatic fibrosis than TBA in patients with hepatitis C virus (HCV)‐related liver diseases. In the current study we aimed to confirm these finding in patients with primary biliary cirrhosis (PBC), a prototypic cholestatic liver disease. Methods: Urinary sulfated bile acids were measured using an automatic assay kit in 50 patients with PBC, of whom 11 were diagnosed as having cirrhosis. We obtained specimens before ursodeoxycholic acid (UDCA) administration in four patients, and during UDCA in 46 patients. The correlations between USBA and various laboratory tests were studied. Results: The median USBA level was 67.9 µmol/g creatinine in PBC; 27.7 without cirrhosis and 210.3 with cirrhosis (P = 0.001). The number of PBC patients with elevated USBA was significantly higher than those with elevated TBA (82% vs. 56%). This significance was remarkable especially in early stages, non‐cirrhotic patients (77% vs. 49%). USBA level was well correlated with TBA (r_s = 0.72), and negatively correlated with platelet (r_s = ?0.34) and albumin (r_s = ?0.31). Conclusion: Urinary sulfated bile acids and TBA are well correlated, and together with the findings that USBA is not affected by meals, USBA is considered to be more beneficial and convenient than TBA for earlier detection of fibrosis in PBC.     

肠道菌群和胆汁酸代谢对非酒精性脂肪性肝病发生发展的作用

随着肥胖及代谢综合征的流行,非酒精性脂肪性肝病的患病率逐年递增,在该病的发生和发展过程中,肠道菌群和胆汁酸代谢均发挥重要作用。讨论了肠道菌群和胆汁酸代谢之间的关系,重点强调了肠道菌群、胆汁酸和胆汁酸受体在非酒精性脂肪性肝病发生发展的过程中所起到的作用。     

Evaluation of an oral bile acid loading test for assessment of liver function in chronic hepatitis A comparison with fasting serum bile acids and i.v. galactose elimination test

ABSTRACT— In 40 patients with histologically verified chronic hepatitis, (chronic persistent hepatitis, n = 13; chronic active hepatitis without, n = 14; or with cirrhosis, n = 13), of viral and autoimmune origin, serum bile acids (SBA) were measured before and during 3 h after oral ingestion of I g chenodeoxycholic acid (CDA). Fasting SBA were elevated in 22 (55%) patients, whereas the CDA loading test was abnormal in 15 (38%) patients and the galactose elimination was prolonged in 16 (40%) patients. In patients with chronic active hepatitis, 20/27 had elevated SBA either in the fasting state (18/27) or after the CDA loading test (13/27). Normal SBA values were found in 9/13 (70%) patients with chronic persistent hepatitis. Thus, fasting SBA is not sensitive enough to detect mild chronic inflammatory liver disease as chronic persistent hepatitis, but seems to be as sensitive as the galactose elimination or CDA loading tests in detecting potential severe liver disease. Fasting SBA may thus be used as a complement of conventional liver tests in the follow-up of chronic hepatitis as assessment of liver function. An oral CDA loading and an i.v. galactose elimination test add no further information to that given by fasting serum bile acids.     

丹皮酚调控ApoE－/－小鼠胆汁酸代谢发挥抗动脉粥样硬化作用

目的探究丹皮酚通过调控ApoE-/-小鼠胆汁酸代谢影响FXR-FGF15信号通路,从而影响脂质代谢发挥抗动脉粥样硬化的作用。方法采用高脂饲料喂养ApoE-/-小鼠20周建立动脉粥样硬化斑块模型,造模同时灌胃丹皮酚(200 mg/kg)。油红O染色观察主动脉大体和肝脏组织病理形态学变化;酶法检测血脂和肝脂水平;LC-MS/MS检测小鼠肠道胆汁酸组分变化;Western blot检测小鼠肝脏CYP7A1及回肠FXR、FGF15蛋白的表达。结果丹皮酚显著减轻动脉粥样硬化模型小鼠主动脉斑块面积,减少肝脏脂质沉积;明显降低血清和肝脏中甘油三酯、总胆固醇水平及肝脏系数;升高FXR拮抗剂TαMCA、TβMCA含量,降低FXR激动剂CDCA和LCA含量,抑制肠FXR-FGF15信号通路,诱导肝组织CYP7A1蛋白表达,增加粪便中总胆汁酸外排。结论丹皮酚可能通过影响胆汁酸代谢,抑制FXR-FGF15轴从而促进肝脏胆汁酸合成与排泄,减少胆固醇蓄积,进而实现其抗动脉粥样硬化的作用。     

The effect of extrahepatic cholestasis on liver regeneration after partial hepatectomy in the rat

Abstract: Liver regeneration after partial hepatectomy was studied in four groups of rats: control rats (n=12), rats with 1 week of common bile duct obstruction (n=11), rats with restoration of bile flow after 1 week of obstruction (n=9) and a sham-operated group (n=7). Parameters of DNA synthesis – thymidine kinase activity and in vivo bromodeoxyuridine incorporation – were measured at partial hepatectomy (T=0), and 24 and 48 h after partial hepatectomy. During common bile duct obstruction, DNA synthesis was already stimulated at T=0, but partial hepatectomy in common bile duct obstruction rats induced a delayed DNA synthesis. After 1 week of restoration of bile flow, normal DNA synthesis had returned at T=0, but DNA synthesis after partial hepatectomy was still delayed. The sham-operated rats showed a normal regeneration response after partial hepatectomy assessed by bromodeoxyuridine incorporation but delayed as assessed by thymidine kinase activity, partly due to the impaired physical condition of the animals. The present data support the hypothesis that during cholestasis, regeneration promoting, and inhibitory factors accumulate in the liver, their balance determining whether regeneration after partial hepatectomy will occur in a normal, enhanced or delayed way.     

Effect of olsalazine on sodium-dependent bile acid transport in rat ileum

Olsalazine (OLZ), a relatively new form of 5-aminosalicylic acid (5-ASA), is being used for the treatment of colitis. A major side effect of olsalazine is diarrhea, reported in 12–25% of patients. One suggested mechanism for this side effect is enhanced ileal water and electolyte secretion. We propose that OLZ may also inhibit ileal bile acid (BA) transport, resulting in choleretic diarrhea. This would result in excess BAs reaching the colon, with consequent BA-induced secretory diarrhea. Therefore, we studied the effect of OLZ on rat ileal absorption of taurocholate. BA uptake was determined in rat ileal segments, everted sacs, brush border membrane vesicles (BBMV), andXenopus laevis oocytes. Segments and everted sacs were treated with 5 mM OLZ for 30 min prior to and throughout 10-min taurocholate (Tc) uptake. Terminal ileal BBMV were used to study the effect of OLZ on sodium-dependent bile acid uptake independent of cellular metabolism. Direct effects on the bile acid carrier were examined usingXenopus laevis oocytes expressing the cloned apical rat ileal BA transporter. In ileal segments 5 mM OLZ inhibited 10-min Tc uptake by 69.4±8.8% (P<0.01) (N=10 animals). Increasing concentrations of OLZ resulted in a dose-dependent inhibition of Tc uptake. Ten-minute Tc uptake with 0.5, 1.0, 2.0, 2.5, and 5 mM OLZ was inhibited by 13.5, 39.6, 49.7, and 70.5%, respectively. In BBMV, OLZ inhibited 45-sec Tc uptake in a dose-dependent manner but did not effect Na-dependentl-alanine uptake. Kinetic analysis revealed a noncompetitive inhibition by 2 mM olsalazine. Olsalazine, 5 mM, also inhibited Na-dependent uptake of Tc into oocytes, which expressed the rat ileal sodium-dependent bile acid transporter (8.0±3.7 vs 2.6±2.0 pmol/oocyte/hr,P<0.001). OLZ inhibits sodium-dependent Tc uptake and transmucosal transport in the rat ileum in a dose-dependent manner. This inhibition is relatively specific, noncompetitive, and does not require intact cellular mechanisms. This effect of OLZ on ileal function may contribute to the diarrhea frequently observed with this drug.Supported in part by a grant from Reach Out For Youth with IBD and a gift from Ruth & Leonard Litwin and by grants from the National Institute of Health (DK02076,34989,43509, HD07388, HD20632 and HD27757).This work was presented in part at the American Gastroenterological Association meeting, Boston, Massachusetts, May 19, 1993.Address for reprint requests: Dr. Anupama Chawla, Pediatric Gastroenterology, North Shore University Hospital-Cornell University Medical College, 300 Community Drive, Manhasset, New York 11030.     

Liver regeneration is impaired by FK778 in partially hepatectomized rats, while supplemental uridine restores both liver growth and hepatocyte proliferation

Aim:  The impact of mandatory immunosuppression on liver regeneration after segmental liver transplantation is of clinical importance. FK778, a novel immunosuppressant, inhibits pyrimidine biosynthesis and prevents rejection after organ transplantation in a dose-dependent manner. We investigated the effect of FK778 at a highly effective dose on liver regeneration in a small animal model.
Methods:  Inbred Lewis rats were subjected to 70% partial hepatectomy (PH) and treated with saline ( n  = 28), uridine ( n  = 16), FK778 alone ( n  = 28) or in combination with uridine ( n  = 16). FK778 was given intravenously daily at a dose of 25 mg/kg bodyweight (bw) and uridine was given daily intraperitoneally at a dose of 250 mg/kg bw. Liver bodyweight ratio (LBR), hepatocyte proliferation index (PI), blood chemistry and morphological analysis were incorporated. PI was determined by Ki-67 immunostaining. De Ritis ratio was calculated to assess the extent of liver damage.
Results:  In FK778-treated animals PI was decreased at 24 h and 72 h and LBR was lower at 48 h and 72 h ( P  < 0.05) after the PH. In addition, morphological analysis showed confluent central lobular necrosis at 72 h in four of seven animals. Uridine supplementation restored PI, LBR and the de Ritis ratio in FK778-treated animals and no confluent necroses were observed.
Conclusion:  FK778 is antihepatotrophic as well as antiproliferative during rat liver regeneration. Both liver growth and hepatocyte proliferation are completely restored by supplementation with uridine. In addition, supplemental uridine markedly reduces the severity of morphological abnormalities consistent with FK778 toxicity.     

Alteration of bile acid metabolism and vitamin-B12-absorption in diabetics on biguanides

Summary Since vitamin B₁₂malabsorption has been described in diabetics on biguanides and inhibition of bile acid absorption found in rat ileum the effect of treatment with different biguanides (phenformin, buformin, metformin) on bile acid metabolism and vitamin B₁₂ absorption was assessed in maturity onset diabetics. Biguanides did not alter faecal weight or faecal fat excretion, but they decreased faecal bile acid excretion. All biguanides tested increased deconjugation of glycocholic acid, as determined by a simple breath test technique. Vitamin B₁₂ malabsorption was most prominent in patients on metformin. Discontinuation of biguanide treatment, or administration of antibiotics, normalized or improved the increased deconjugation of bile acids and the Schilling test. Decreased faecal bile acid excretion, positive¹⁴C-glycocholate breath tests, pathological Schilling tests and the reversal of pathological tests by antibiotic treatment suggest that small intestinal bacterial overgrowth, leading to binding of the intrinsic-factor-vitamin B₁₂-complex to bacteria, is responsible for the previously observed pathological Schilling tests in diabetics on biguanides. Bile acid malabsorption, possibly responsible for the cholesterol-lowering effect of biguanides, does not occur in diabetics on biguanides. Whether qualitative changes in small intestinal bile acid composition might affect cholesterol metabolism remains to be determined.Presented at the 11th Meeting of the German Diabetes-Society, Braunlage, May 1976     

Hepatoprotective impact of the bile acid receptor TGR5

During liver repair after injury, bile secretion has to be tightly modulated in order to preserve liver parenchyma from bile acid (BA)‐induced injury. The mechanisms allowing the liver to maintain biliary homeostasis during repair after injury are not completely understood. Besides their historical role in lipid digestion, bile acids (BA) and their receptors constitute a signalling network with multiple impacts on liver repair, both stimulating regeneration and protecting the liver from BA overload. BA signal through nuclear (mainly Farnesoid X Receptor, FXR) and membrane (mainly G Protein‐coupled BA Receptor 1, GPBAR‐1 or TGR5) receptors to elicit a wide array of biological responses. While a great number of studies have been dedicated to the hepato‐protective impact of FXR signalling, TGR5 is by far less explored in this context. Because the liver has to face massive and potentially harmful BA overload after partial ablation or destruction, BA‐induced protective responses crucially contribute to spare liver repair capacities. Based on the available literature, the TGR5 BA receptor protects the remnant liver and maintains biliary homeostasis, mainly through the control of inflammation, biliary epithelial barrier permeability, BA pool hydrophobicity and sinusoidal blood flow. Mouse experimental models of liver injury reveal that in the lack of TGR5, excessive inflammation, leaky biliary epithelium and hydrophobic BA overload result in parenchymal insult and compromise optimal restoration of a functional liver mass. Translational perspectives are thus opened to target TGR5 with the aim of protecting the liver in the context of injury and BA overload.     

Evolution of biliary secretion during bile diversion in normal and two-thirds hepatectomized rats

The effect of the interruption of the enterohepatic circulation on bile production in anesthetized rats both before and after two thirds partial hepatectomy (PH) was studied. Both in the control animals and in the different periods after PH, interruption of the enterohepatic circulation led to significant decreases in bile flow and bile acid and sodium output. The evolution of choleresis in all the experimental groups was seen to follow a parallel course to that of sodium output and showed qualitative and quantitative discrepancies with the behavior of bile acid output. The cumulative secretion of bile acids expressed per 100 g of body weight was comparable in the controls and at 384 h after PH, though only in the former did the bile acid circulating pool size seem to be depleted. This depletion was more delayed than that described for conscious nonfasting rats. At 96 and 384 h after PH both cumulative bile flow and cumulative sodium secretion expressed per gram of liver were greater than those of the control animals. The choleretic capacity of the bile acids and the bile acid independent fraction of bile flow were significantly modified in the different posthepatectomy periods.     

Splenic artery ligation improves remnant liver function in partially hepatectomized rats with ischemia/reperfusion injury

Background: In liver resection, the temporary occlusion of the hepatoduodenal ligament (Pringle maneuver) is often used. However, the maneuver causes severe ischemia/reperfusion injury in the remnant liver. Our aim was to investigate the effects of splenic artery ligation on the liver function in partially hepatectomized rat with the Pringle maneuver. Methods: The Pringle maneuver was conducted for 30 min just before a two‐thirds partial hepatectomy. Splenic artery ligation was performed before the Pringle maneuver. The efficacy of splenic artery ligation was assessed by survival, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), recovery of remnant liver weight, and portal pressure. Results: On day 3, animal survival was four rats of 12 in partially hepatectomized rats with the Pringle maneuver and 10 rats of 12 in the splenic artery ligation‐treated partially hepatectomized rats with the Pringle maneuver. A two‐thirds partial hepatectomy alone or splenic artery ligation itself did not show any effects on the survival. Compared with partially hepatectomized rats with the Pringle maneuver, splenic artery‐ligated animals had lower serum AST and ALT levels, and higher recovery of remnant liver weight. Splenic artery ligation significantly reduced the portal pressure and also decreased the fatality in excessively hepatectomized rats. Conclusions: Splenic artery ligation ameliorated the remnant liver function in partially hepatectomized rats with the Pringle maneuver and excessively hepatectomized rats. The amelioration may be mediated at least by decreasing portal pressure.     

Inhibition of ileal bile acid absorption by colestimide

BACKGROUND: Colestimide is a new type of anion-exchange resin in Japan, but its effect on bile acid absorption in the ileum has not been studied. METHODS: Absorption of ursodeoxycholate, tauroursodeoxycholate, cholate, taurocholate and taurolithocholate-sulfate in rat ileum was compared in the presence and absence of colestimide. Bile acid adsorption by colestimide in vitro was also studied. RESULTS: All bile acids were efficiently absorbed by the ileum, and the cumulative absorption during 60 min was 25-78%. The absorption of ursodeoxycholate, tauroursodeoxycholate and taurocholate was inhibited by colestimide, whereas that of cholate and taurolithocholate-sulfate was not inhibited by colestimide. Adsorption of bile acids by colestimide in vitro was higher with taurine conjugates than with the unconjugated forms. CONCLUSIONS: Colestimide was shown to be useful to inhibit the physiologically important ileal absorption of bile acid amides in vivo.     

Regurgitation of bile acids in rat liver under bile drainage: quantitative analysis by taurine or ursodeoxycholate loading test

Abstract In rats with an interrupted enterohepatic circulation of bile acids, levels of serum taurine-conjugated bile acids were increased significantly 3 h after intravenous administration of taurine. Similarly, serum taurine- or glycine-conjugated ursodeoxycholic acid (UDCA) was increased significantly 2 h after UDCA administration. These findings suggested that the administered taurine or UDCA was taken up into hepatocytes and utilized to form conjugated bile acids, which were thereafter regurgitated into the systemic circulation from the liver. The proportion of regurgitated taurine-conjugated bile acids relative to total serum bile acids measured by taurine loading (30%) almost coincided with that of regurgitated taurine- or glycine-conjugated UDCA relative to total serum bile acids measured by UDCA loading (31.6%). Thus, the present study showed conclusively that at least 30% of serum bile acids are derived from newly conjugated bile acids that are regurgitated from the liver in rats with bile fistula.     

Fatty acid bile acid conjugates (FABACs)--new molecules for the prevention of cholesterol crystallisation in bile

BACKGROUND: Cholesterol gall stones are a frequent disease for which at present surgery is the usual therapy. Despite the importance of bile acids it has become evident that phospholipids are the main cholesterol solubilisers in bile. Even phospholipid components, such as fatty acids, have anticrystallising activity. AIM: To synthesise fatty acid bile acid conjugates (FABACs) and study their effects on cholesterol crystallisation in bile in vitro and in vivo. METHODS: FABACs were prepared by conjugation of cholic acid at position 3 with saturated fatty acids of variable chain length using an amide bond. Cholesterol crystallisation and its kinetics (crystal observation time, crystal mass) were studied in model bile, pooled enriched human bile, and fresh human bile using FABACs with saturated fatty acids of varying chain length (C-6 to C-22). Absorption of FABACs into blood and bile was tested in hamsters. Prevention of biliary cholesterol crystallisation in vivo was tested in hamsters and inbred mice. RESULTS: FABACs strongly inhibited cholesterol crystallisation in model as well as native bile. The FABACs with longer acyl chains (C-16 to C-22) were more effective. At a concentration of 5 mM, FABACs almost completely inhibited cholesterol crystallisation in fresh human bile for 21 days. FABACs were absorbed and found in both portal and heart blood of hamsters. Levels in bile were 2-3 times higher than in blood, indicating active secretion. Appreciable levels were found in the systemic circulation 24-48 hours after a single administration. Ingested FABACs completely prevented the formation of cholesterol crystals in the gall bladders of hamsters and mice fed a lithogenic diet. CONCLUSIONS: FABACs are potent inhibitors of cholesterol crystallisation in bile. They are absorbed and secreted into bile and prevent the earliest step of cholesterol gall stone formation in animals. These compounds may be of potential use in cholesterol gall stone disease in humans.