Primary bile duct stones and bacterial activity

Role of the biliary microbiome in gallstone disease

Gallstone disease is caused by multiple pathogenic factors and is common worldwide. Most studies have focused on the significance of the biliary microbiome in gallstone pathogenesis. Areas covered: In this study, the epidemiology of gallstone diseases and the existence, composition, origin, and mechanisms of the biliary microbiota were reviewed. Mechanisms involved in promoting the formation of different types of gallstones were also emphasized. The antibiotic susceptibility of the biliary microbiota is briefly discussed because it may guide clinical strategies. Expert commentary: The biliary microbiome facilitates the formation of brown pigment stones. Although glycoprotein (mucin) may be pivotal for many promoting substances to coagulate and integrate relevant components, new mechanisms involving prostaglandins, oxysterols, oxygen free radicals, and lipopolysaccharides have been discovered. Furthermore, specific bacterial species such as Helicobacter and Salmonella are involved in the pathogenesis of cholesterol gallstones. Recently, metabolomics of the biliary microbiome has been used to determine the detailed mechanisms that promote gallstone formation. Previously, the bacterial effects involved in the pathogenesis of brown pigment stones have not been analyzed in detail. Whether the administration of antibiotics is related to prophylaxis for gallstone formation and gallstone-associated infections remains unclear.

Gallstone disease: Free radical reactions and the ambivalent role of bilirubin in the pathomechanism of gallstone formation

Az epekőbetegségek kialakulásában számos gén működését teszik felelőssé, melyek kapcsolatba hozhatók elsődlegesen a máj betegségeivel, az epeelfolyási és -képződési rendellenességekkel, a lipidmetabolizmus módosulásával, diabetes mellitussal, obesitassal, glutensensitiv enteropathiával, Crohn-betegséggel, Down-szindrómával, Gaucher-kórral, cysticus fibrosissal, valamint haematológiai kórképekkel és ileumresectiot követő állapottal. Kialakulásában szerepet játszanak gyógyszermellékhatások, bakteriális fertőzések, gyulladások, fémionterhelés és szabadgyökös reakciók. A zsírmájból az epébe telítetlen zsírsavak, lipidoxidok, diénkonjugátumok, és egyéb lipidperoxidációs termékek kerülnek, melyek az epevezetékben és a hólyagban primer és szekunder szabadgyökös folyamatokat indítanak el. Az epehólyagfalban lejátszódó gyulladásos folyamatok szabadgyöktermeléssel járnak. Az epe szabad bilirubin-tartalma koncentrációfüggően pro-, illetve antioxidánsként viselkedik. Az ambivalens tulajdonságú szabad bilirubin, amely a mikroszómák szivárgása révén, illetve a bél felől a baktériumok deglükorinidáló hatása következtében kimutatható mennyiségben van jelen az epehólyagban, a szabadgyökös reakciókat felerősíti. A szabad bilirubin kőalkotó reakciója az epében jelen lévő fémionokkal, elsődlegesen a Ca++-ionokal kalcium-(hidrogén)-bilirubinátot eredményez. A Ca++a zsírsavakkal is reakcióba lép, és ezzel megváltoztatja az epe viszkozitását. A lipidek, a szabad bilirubin és a fémionok együttesen kőalkotó komponensek. Az antioxidánsok, illetve azok derivátumai vagy hatásukban antioxidáns tulajdonságot fokozó vegyületek, készítmények több szinten is kedvezően befolyásolhatják az epe összetételét, illetve az epekőképződés gátlását.

Inhibition of cholesterol crystallization under bilirubin deconjugation: partial characterization of mechanisms whereby infected bile accelerates pigment stone formation

Pigment gallstones have been reported to be closely associated with biliary tract infection. We previously reported that addition of unconjugated bilirubin (UCB), which is deconjugated by beta-glucuronidase in infected bile, could enhance cholesterol crystal formation in supersaturated model bile (MB). The present study evaluated the effect of beta-glucuronidase on the processes of pigment gallstone formation and cholesterol crystallization. Supersaturated MB (taurocholate/lecithin/cholesterol at 71:18:11, a total lipid concentration of 10.0 g/dl and a cholesterol saturation index (CSI) of 2.0) and native rat bile were mixed at a ratio of 3:1. Then, mixed bile was incubated with or without beta-glucuronidase and changes of the following parameters were investigated over time: (1) the UCB/total bilirubin ratio; (2) cholesterol crystal formation; (3) the precipitate weight and the cholesterol concentration in the precipitate and supernatant; and (4) the lipid distribution of vesicles in the supernatant. Compared with beta-glucuronidase-free bile, (1) beta-glucuronidase-containing bile showed a significant increase of the UCB/total bilirubin ratio, (2) as well as a significantly longer nucleation time (96+/-17.0 vs. 114+/-20.0) and fewer cholesterol crystals. (3) The precipitate weight and the cholesterol concentration in the precipitate were significantly increased, while the cholesterol concentration in supernatant was decreased. (4) When mixed bile was incubated with beta-glucuronidase, the cholesterol concentration in the vesicles was lower than in bile without beta-glucuronidase. The precipitate weight and the cholesterol concentration in the precipitate was increased by incubation with beta-glucuronidase, while cholesterol concentration was decreased in the supernatant (especially in the vesicles). This means that bile vesicles were more stable and it was more difficult for cholesterol crystals to form. Thus, the presence of beta-glucuronidase may inhibit the formation of pure cholesterol stones even in the presence of cholesterol supersaturation.

Relationship between bilirubin free radical and formation of pigment gallstone

In this paper, we summarize the main progresses made in our group in the field of the mechanism of pigment gallstone formation. It was found that after treatment with free radicals, bilirubin (BR) was changed into free radical itself, and a semiquinone free radical and a superoxide free radical bound with metal were recognized, which was detected by ESR (electron spin resonance). By the means of NMR (nuclear magnetic resonance) and IR (Infra-red spectra), it was postulated that bilirubin polymerized through the reaction between the vinyl group and the hydroxyl group under the attack of free radicals. It was also found that bilirubin free radical were liable to calcify in a kinetic study. Because of its chemical properties, bilirubin free radical was shown to be cytotoxic to hepatocyte, which was demonstrated based on the following facts: induction of phospholipid peroxidation (LPO), leakage of lactate dehydrogenase (LDH) and decrease of glutathione. As to the mechanism of bilirubin-induced cytotoxicity, it was postulated that the main target of bilirubin free radical was the cell membrane, including phospholipid and membrane bound proteins, especially spectrin, a content of cytoskeleton. Based on the results mentioned above, it was deduced that bilirubin free radical is the key factor that initiates and promotes the formation of pigment gallstone, which is consistent with other researches in recent years.

Single and multiple cholesterol gallstones and the influence of bacteria

Single and multiple cholesterol gallstones constitute at least 80% of the gallstone population observed at cholecystectomy in Western countries. While supersaturation of bile with cholesterol is necessary for gallstone growth, the kinetic determinant of crystal nucleation is perhaps the critical factor leading to the incidence of gallstones. Nucleation involves aggregation of nidus-forming materials like pigment precipitates and mucus proteins. In combination with cholesterol precipitates and crystal formation, gallstone propagation is enhanced. Bacterial species may augment the process of nucleation and gallstone growth by contributing specific enzyme activities resulting in the formation of insoluble precipitates in bile, or by acting as a nidus upon which the deposition of cholesterol crystals may initiate gallstone formation. The utilization of Raman microscopic techniques permits detailed mapping of the distribution of the gallstone components leading to identification and characterization of the site of nucleation. This, when coupled to molecular genetic tools such as PCR DNA amplification, would permit elucidation of the role of bacteria in vivo gallstone propagation mechanisms.

Pigment gallstone pathogenesis: slime production by biliary bacteria is more important than beta-glucuronidase production

Pigment stones are thought to form as a result of deconjugation of bilirubin by bacterial beta-glucuronidase, which results in precipitation of calcium bilirubinate. Calcium bilirubinate is then aggregated into stones by an anionic glycoprotein. Slime (glycocalyx), an anionic glycoprotein produced by bacteria causing foreign body infections, has been implicated in the formation of the precipitate that blocks biliary stents. We previously showed that bacteria are present within the pigment portions of gallstones and postulated a bacterial role in pigment stone formation through beta-glucuronidase or slime production. Ninety-one biliary bacterial isolates from 61 patients and 12 control stool organisms were tested for their production of beta-glucuronidase and slime. The average slime production was 42 for biliary bacteria and 2.5 for stool bacteria (P <0.001). Overall, 73% of biliary bacteria and 8% of stool bacteria produced slime (optical density >3). In contrast, only 38% of biliary bacteria produced beta-glucuronidase. Eighty-two percent of all patients, 90% of patients with common bile duct (CBD) stones, 100% of patients with primary CBD stones, and 93% of patients with biliary tubes had one or more bacterial species in their stones that produced slime. By comparison, only 47% of all patients, 60% of patients with CBD stones, 62% of patients with primary CBD stones, and 50% of patients with biliary tubes had one or more bacteria that produced beta-glucuronidase. Most biliary bacteria produced slime, and slime production correlated better than beta-glucuronidase production did with stone formation and the presence of biliary tubes or stents. Patients with primary CBD stones and biliary tubes had the highest incidence of slime production. These findings suggest that bacterial slime is important in gallstone formation and the blockage of biliary tubes.

Medical treatment of cholangiohepatitis and cholelithiasis in mature horses: 9 cases (1991-1998)

The medical approach to treatment of cholangiohepatitis and cholelithiasis in 9 horses is described. Seven horses were treated successfully and returned to normal use, with a minimum follow-up period of 12 months. Long-term antimicrobial therapy was believed to be critical in those cases that survived, with a median treatment duration of 51 days (range 17-124 days). Treatment failure was associated with severe periportal and bridging hepatic fibrosis from biopsy material obtained at admission in 2 horses, one of whom also presented with hyperammonaemic hepatic encephalopathy. Transabdominal ultrasound was used diagnostically in each case to obtain hepatic biopsy material for histopathology and bacterial culture, to evaluate hepatic size and echogenicity and to identify and monitor the dissolution of hepatoliths. Histologically, all horses had evidence of suppurative cholangiohepatitis with varying degrees of periportal and bridging fibrosis. Discrete hyperechoic calculi were identified in 4 cases, but all horses had ultrasonographic evidence of biliary obstruction with numerous dilated bile ducts. Aerobic and anaerobic cultures of liver biopsy material were negative from 7 horses, but 2 different species of Escherichia coli were obtained from one horse, and Bacteroides vulgatus and Escherichia coli were isolated from another. In all 7 horses that survived, clinical recovery was seen before normalisation of biochemical indices of hepatobiliary function including gammaglutamyl transaminopeptidase (GGT), alkaline phosphatase (AP), bile acids and serum bilirubin. Serum GGT levels were monitored extensively as a marker of hepatobiliary disease and actually increased during the initial period of clinical improvement in horses that recovered. Supportive medical therapy with i.v. fluids was also a critical part of the therapy of several cases in this report, both acutely and in the management of chronic cases that deteriorated clinically during treatment. Previous therapeutic failures may well be related to treatment periods of inadequate duration, and the authors recommend that antimicrobial therapy should be continued until GGT values are normal.