Reversible bile acid changes in bile duct obstruction and its potential for hepatocellular injury

Benign obstruction of the common hepatic duct (Mirizzi syndrome): diagnosis and operative management

BACKGROUND

Mirizzi syndrome is a rare complication of prolonged cholelithiasis, characterized by narrowing of the common hepatic duct due to mechanical compression and/or inflammation due to biliary calculus impacted in the infundibula of the gallbladder or in the cystic duct.

OBJECTIVES

To describe a series of eight consecutive patients with Mirizzi syndrome, at a single institution, submitted to surgical treatment and to comment on their aspects with emphasis on the diagnosis and treatment.

METHODS

Four women and four men, with a mean age of 61.6 years (42 to 82 years), presenting Mirizzi syndrome were operated between 1997 and 2003. The following items were evaluated: clinical presentation, laboratory results, preoperative evaluation, operative findings, presence of choledocholithiasis, type of Mirizzi syndrome according to the classification by Csendes, choice of operative procedures, and complications.

RESULTS

The most frequent symptoms were abdominal pain (87.5%) and jaundice (87.5%). All the patients presented altered hepatic function tests. The diagnosis of Mirizzi syndrome was intra-operative in seven (87.5%) patients, and preoperative in one (12.5%). Cholecystocholedochal fistula associated with choledocholithiasis was observed in three (37.5%) cases. Mirizzi syndrome was classified as Csendes type I in five (62.5%) patients, type II in one (12.5%), type III in one (12,5%) and type IV in another (12.5%). Cholecystectomy, as an isolated surgical procedure, was performed in four (50.0%) patients. One (12.5%) patient was submitted to partial cholecystectomy and closure of the fistulous orifice with the central part of the infundibula. Two (25.0%) patients were submitted to cholecystectomy and side-to-side choledochoduodenostomy and another (12.5%) to side-to-side choledochoduodenostomy remaining the gallbladder in situ. Seven (87.5%) patients had an uneventful recovery and were discharged in good conditions. One (12.5%) patient presented a postoperative sepsis due to a sub-hepatic abscess, and was reoperated. There was no operative mortality.

CONCLUSION

The preoperative diagnosis of Mirizzi syndrome is difficult and an awarded suspicion is necessary to avoid lesions of the biliary tree. The problem may only become evident during the operation due to firm adherences around Calot's triangle. The success of the treatment is related to a precocious recognition of the condition, even at the time of surgery, and adapting the management considering to the individual characteristics of each case.

Repetitive short-term bile duct obstruction and relief causes reproducible and reversible bile acid regurgitation

BACKGROUND

Long-term bile duct obstruction causes sinusoidal regurgitation of bile acids, a shift in bile acid metabolism, and alterations of liver histology. In this study we investigated the regurgitation of bile acids during short-term bile duct obstruction and its reversibility and reproducibility. In addition, the biotransformation of taurodeoxycholate and its appearance in bile and perfusate effluent were studied as well as liver histology.

METHODS

Rat livers (n = 5) were perfused in vitro with 32 nmol/min/g liver taurodeoxycholate over 85 min with the bile duct being intermittently closed for 30 and 20 min, respectively.

RESULTS

Within the first 5 min after bile duct obstruction bile acids started to regurgitate to the perfusate effluent amounting to approximately 15% of hepatic uptake until the end of the perfusion period. After relief of obstruction, bile flow and biliary bile acid excretion showed an overshoot phenomenon and were almost doubled compared to preobstruction. In contrast, sinusoidal bile acid regurgitation declined. The same phenomenon was observed during the second closure/opening cycle of the bile duct. Regurgitated bile acids consisted of significantly more taurodeoxycholate metabolites (approximately 70%) than did biliary bile acids (approximately 30%). Histology of liver parenchyma was preserved.

CONCLUSIONS

During repetitive short-term bile duct obstruction bile acid regurgitation is reversible and reproducible. The absence of altered mechanical barriers suggests that specific pathways are involved in the regurgitation process of bile acids.

Ebselen protects against the reduction in levels of drug-metabolizing enzymes in livers of rats with deoxycholic acid-induced liver injury

Ebselen is a seleno-organic compound that inhibits oxidative stress by lipid peroxidation through a glutathione peroxidase-like activity. We studied the effect of ebselen on the expression of hepatic drug-metabolizing enzymes in rats with deoxycholic acid-induced liver injury. Hydrophobic bile acids, such as deoxycholic acid, are known to cause cholestatic liver injury, and it was reported that expression of hepatic cytochrome P-450 (CYP) was reduced by deoxycholic acid administration in rats. Hydrophobic bile acids induce lipid peroxidation in the liver, and this may be one mechanism of the development of liver injury. In the present study, we investigated the effect of ebselen (30 mg/kg/day for 10 days) on rats ingesting deoxycholic acid (1% of diet for 10 days). Deoxycholic acid decreased levels of CYP1A1, 2B1, 2E1 and 3A2 to 34, 58, 62 and 37% of control values, respectively, and increased serum alkaline phosphatase (ALP) and alanine aminotransferase (ALT) activities to 1.8 and 8.6 times the levels of controls, respectively. Administration of ebselen with deoxycholic acid prevented the decreases in levels of CYP1A1 and 3A2 (86 and 65% of control, respectively) and the increases in serum ALP and ALT activities (1.4 and 1.9 times of control, respectively) caused by deoxycholic acid. These results indicate that ebselen may have a protective effect against hydrophobic bile acid-induced liver injury.

Human biliary beta-glucuronidase activity before and after relief of bile duct obstruction: is it the major role in the formation of pigment gallstones?

BACKGROUND AND AIMS

The bacterial beta-glucuronidase (bBG) can deconjugate conjugated bilirubin to form calcium bilirubinate gallstone. Yet, the role of the human biliary beta-glucuronidase (hBG) in the pathogenesis of pigment gallstone formation still remains unsolved.

METHODS

Hepatic bile was collected from bile-duct-obstructed patients on the day of, and 3 days after, biliary drainage. Patients were divided into pigment-stone (PS) group (n = 34) and stone-free (SF) group (n = 29). All patients of the PS group had the complication of cholangitis. The concentrations of bile contents and the activities of bBG and hBG were measured.

RESULTS

The activities of hBG and bBG in bile obtained on the day of biliary drainage were higher in the PS group than in the SF group (activities corrected for bile salt concentration: hBG 128.7 +/- 340.0 vs 13.1 +/- 25.0 U/mmol; bBG 12.5 +/- 22.2 vs 4.6 +/- 7.7 U/mmol, P < 0.05). This difference disappeared after biliary drainage. The changes of enzyme activity in the bile of the SF group were unremarkable before and after biliary drainage. The mean concentrations of bile pigments and free calcium in the PS group were lower than those in the SF group.

CONCLUSIONS

An increase in the activity of hBG may be a secondary response, developed after bile duct inflammation because it was elevated only when the bile duct obstruction was associated with infection.

Bile duct ligation in rats induces biliary expression of cytokine-induced neutrophil chemoattractant

BACKGROUND & AIMS

Bile duct obstruction causes neutrophilic inflammation of the liver and leads to hepatic fibrosis. In obstructive liver disease, the localization of neutrophils in portal tracts suggests that cells within this region produce neutrophil chemoattractants. In this study, we investigated whether bile duct obstruction in rats induces portal expression of cytokine-induced neutrophil chemoattractant (CINC).

METHODS

Rats underwent bile duct ligation for 3 hours to 8 days. CINC regulation was examined in vivo at various intervals by immunohistochemistry, ribonuclease protection, and in situ hybridization. CINC production was also investigated in cell culture, in response to putative stimuli from obstructed liver.

RESULTS

Bile duct ligation caused neutrophilic infiltration of the liver within 3 hours. CINC was also rapidly induced, with specific expression identified in biliary cells. Rat intrahepatic biliary cells produced CINC constitutively in culture; when exposed to cholestatic bile, they showed a 12-fold increase in CINC secretion. The effect of bile was not attributable to toxicity or to dissolved cytokines or endotoxin. Mechanical strain, designed to mimic the stretching of biliary cells during obstruction, did not induce CINC.

CONCLUSIONS

Biliary cells contribute to hepatic inflammation during cholestasis by producing neutrophil chemoattractants. A major stimulus to biliary chemoattractant production in vivo may be bile itself.

Effect of silymarin on biliary bile salt secretion in the rat

The effect of the hepatoprotector silymarin on bile secretion, with particular regard to bile salt secretion, was studied in Wistar rats. Silymarin (25, 50, 100, and 150 mg/kg/day, i.p., for 5 days) induced a dose-dependent increase in bile flow and bile salt secretion, the maximal effect being reached at a dose of 100 mg/kg/day (+17 and +49%, for bile flow and bile salt output, respectively; P < 0.05). Assessment of bile salt composition in bile revealed that stimulation of the bile salt secretion was accounted for mainly by an increase in the biliary secretion of beta-muricholate and, to a lesser extent, of alpha-muricholate, chenodeoxycholate, ursodeoxycholate, and deoxycholate. The maximum secretory rate (T(m)) of bile salts, as assessed by infusing the non-hepatotoxic bile salt tauroursodeoxycholate i.v. at stepwise-increasing rates, was not influenced by silymarin. The flavonolignan also increased the endogenous bile salt pool size (+53%, P < 0.05) and biliary bile acid excretion after bile acid pool depletion (+54%, P < 0.05), a measure of de novo bile salt synthesis. These results suggest that silymarin increases the biliary excretion and the endogenous pool of bile salts by stimulating the synthesis, among others, of hepatoprotective bile salts, such as beta-muricholate and ursodeoxycholate.

Ursodeoxycholic acid prevents hepatic cytochrome P450 isozyme reduction in rats with deoxycholic acid-induced liver injury

BACKGROUND/AIMS

Hydrophobic bile acids, such as deoxycholic acid produce cholestatic liver injury. Ursodeoxycholic acid has been shown to be useful in the treatment of cholestatic liver disease.

METHODS

In this study, we investigated the effects of deoxycholic acid or ursodeoxycholic acid (1% of diet, for 14 days) and their combination (1% each) on expression of hepatic cytochrome P450 isozymes, their related enzyme activities and mRNA level in rats.

RESULTS

Adding 1% deoxycholic acid to chow caused a marked increase in serum total bilirubin (47-fold) and total bile acid (8-fold) concentrations and in alkaline phosphatase (2.5-fold, p<0.01) and alanine aminotransferase activities (23.5-fold, p<0.01). Adding the same dose of ursodeoxycholic acid along with the deoxycholic acid mitigated both the rise in serum total bilirubin and bile acid concentrations and that in alkaline phosphatase and alanine aminotransferase activities, although the use of ursodeoxycholic acid alone did not affect any of the above. Feeding 1% deoxycholic acid caused a decrease (48% of control) in total cytochrome P450 content in hepatic microsomes. Addition of 1% ursodeoxycholic acid along with the 1% deoxycholic acid completely prevented the decrease in total cytochrome P450 content. Feeding ursodeoxycholic acid alone did not affect the total cytochrome P450 content. The expression of cytochrome P450 2B1, 2E1, 3A2, 2C6, 2C11 and 4A1 proteins in hepatic microsomes was decreased by deoxycholic acid (44, 51, 23, 59, 30 and 74% of control, respectively). Likewise, the activities of cytochrome P450 2B1 (pentoxyresorufin O-depentylation), 2E1 (aniline p-hydroxylation) and 3A2 (testosterone 6beta-hydroxylation) isozymes and the 3A2 mRNA levels in liver were decreased by deoxycholic acid. Addition of 1% ursodeoxycholic acid to 1% deoxycholic acid also prevented the decrease in these cytochrome P450 proteins, related enzyme activities and mRNA levels in liver.

CONCLUSIONS

These results indicate that, in rats with deoxycholic acid-induced liver injury, ursodeoxycholic acid prevents the decrease in hepatic cytochrome P450 isozymes and suggest that ursodeoxycholic acid is useful for the treatment of liver injury in terms of aiding the normalization of the hepatic drug-metabolizing system.

Microsomal function in biliary obstructed rats: effects of S-adenosylmethionine

BACKGROUND/AIMS

S-adenosylmethionine has been reported to have beneficial effects in the treatment of different chronic liver diseases and to protect against different hepatotoxic agents. The aim of this study was to investigate whether S-adenosylmethionine treatment might contribute to improved microsomal function in chronically biliary obstructed rats.

METHODS

Secondary biliary cirrhosis was induced by 28 days of bile duct obstruction. Groups of control and cirrhotic animals received S-adenosylmethionine (10 mg/kg per day) through the experimental period.

RESULTS

Bile duct obstruction resulted in a marked increase in lipid peroxidation levels and decreases in glutathione concentration, microsomal membrane fluidity, microsomal cytochrome P-450 content, NADPH-cytochrome P-450 reductase activity and the activities of the aniline hydroxylase, aminopyrine demethylase and ethoxycoumarin deethylase. Reductions in glutathione and cytochrome P-450 concentration were not corrected by S-adenosylmethionine, but lipid peroxidation, the decrease in the activities of the various microsomal monooxygenases and the reduction in microsomal membrane fluidity were partially prevented. A significant relationship was found between membrane fluidity and aniline hydroxylase, aminopyrine demethylase or ethoxycoumarin deethylase activities.

CONCLUSIONS

S-adenosylmethionine administration partially preserves microsomal function. This effect could be associated to the protection of membrane function by restoring transmethylation reactions.

Enhanced biliary excretion of canalicular membrane enzymes in estrogen-induced and obstructive cholestasis, and effects of different bile acids in the isolated perfused rat liver

BACKGROUNDS/AIMS

Canalicular membrane enzymes are normally released into bile by partially known processes. This study was undertaken to investigate whether hepatocellular cholestatis induced in rats by ethynylestradiol or obstructive cholestasis produced by complete biliary obstruction for 24 h is associated with an increased release of alkaline phosphatase and gamma-glutamyl transpeptidase into bile, and to clarify how this process is affected by different bile acids.

METHODS

The studies were performed in the isolated perfused liver during infusion of sodium taurocholate, taurochenodeoxycholate and tauroursodeoxycholate at increasing rates.

RESULTS

Maximum sodium taurocholate, taurochenodeoxycholate and tauroursodeoxycholate secretory rates were decreased in both cholestatic groups (complete biliary obstruction > ethynylestradiol) compared with controls. Maximum biliary outputs of alkaline phosphatase and gamma-glutamyl transpeptidase were significantly increased in the ethynylestradiol group during infusion of sodium taurocholate and taurochenodeoxycholate, but not of tauroursodeoxycholate, and were increased in the complete biliary obstruction group during the infusion of sodium taurocholate and tauroursodeoxycholate but not of taurochenodeoxycholate. The biliary outputs of alkaline phosphatase and gamma-glutamyl transpeptidase showed a significant and direct linear relationship with sodium taurocholate and taurochenodeoxycholate secretory rates in both cholestatic groups. However, only in the complete biliary obstruction group did alkaline phosphatase and gamma-glutamyl transpeptidase excretion show a significant correlation with tauroursodeoxycholate secretory rates. The slope of the line, which indicated the mU of enzyme activity secreted per nmol of sodium taurocholate or taurochenodeoxycholate, was greater for gamma-glutamyl transpeptidase and alkaline phosphatase in both cholestatic groups (ethynylestradiol > complete biliary obstruction) than in the control group. Alkaline phosphatase activity in purified isolated canalicular and sinusoidal membranes was significantly increased in both cholestatic groups (complete biliary obstruction > ethynylestradiol), while gamma-glutamyl transpeptidase activity was unchanged compared with controls.

CONCLUSION

The marked increase in sodium taurocholate and taurochenodeoxycholate-mediated release of alkaline phosphatase and gamma-glutamyl transpeptidase into bile in cholestatic rats suggests an increased lability of these intrinsic membrane proteins to the detergent effects of secreted bile acids. It remains to be elucidated whether this phenomenon, which was particularly intense in ethynylestradiol induced cholestasis, is important in the pathogenesis and perpetuation of bile secretory failure. In contrast, tauroursodeoxycholate administration did not result in enhanced biliary excretion of these membrane enzymes, in either the control group or the ethynylestradiol group, supporting the concept that this bile salt lacks the membrane toxicity of common bile acids.

Pattern of bile acid regurgitation and metabolism during perfusion of the bile duct obstructed rat liver

Bile acid processing in the long-term, bile duct obstructed rat liver was studied ex vivo. Twenty four and 72 h, respectively, after bile duct obstruction the isolated liver was perfused with taurodeoxycholate (16 nmol/min per g liver) the bile duct still being closed. Uptake, metabolism and regurgitation profile were traced by bolus injection of tritium-labeled bile acid; in addition, concurrent histological changes were examined by light- and electron microscopy. Ligation caused dilatation of the intrahepatic ductular branches and increased the serum bile acid concentration to 740 +/- 75 microM (controls: 16 +/- 2.12), reaching its maximum within 24 h. At 16 nmol/min per g liver uptake rate was > 96% in controls and in bile duct obstructed rats. Maximal uptake rates (assessed separately) differed between controls and bile duct obstructed rats (700 nmol/min per g liver vs. 460). Controls excreted more than 80% of labeled bile acid in bile within 10 min after bolus injection. Biliary recovery of label was virtually completed after 30 min. In bile duct obstructed rats excretion of label back to the perfusate effluent (regurgitation) started quantitatively 5 min after bolus application and peaked between 10 and 40 min; after 80 min, effluent recovery was incomplete (about 60% of bolus injected). Biliary bile acids of controls consisted of about 20% taurodeoxycholate-metabolites; bile acids in the perfusate effluent of bile duct obstructed rats of about 55%. The major metabolite in all animal groups was taurocholate; minor metabolites were tauroursocholate, tauro-3 alpha,7 = 0,12 alpha-cholanoic acid and 3-sulfo-taurodeoxycholate. Histologically, inflammation and periportal edema were present after 1 day of bile duct obstruction. After 3 days, marked proliferation of bile ductules was the dominant histological feature. It is concluded that during initial bile duct obstruction, bile acid processing is not altered, although ultrastructural alterations occur early.