Distinct gut microbiota profiles in patients with primary sclerosing cholangitis and ulcerative colitis

AIM

To characterize the gut bacterial microbiota of patients with primary sclerosing cholangitis (PSC) and ulcerative colitis (UC).

METHODS

Stool samples were collected and relevant clinical data obtained from 106 study participants, 43 PSC patients with (n = 32) or without (n = 11) concomitant inflammatory bowel disease, 32 UC patients, and 31 healthy controls. The V3 and V4 regions of the 16S ribosomal RNA gene were sequenced on Illumina MiSeq platform to cover low taxonomic levels. Data were further processed in QIIME employing MaAsLin and LEfSe tools for analysis of the output data.

RESULTS

Microbial profiles in both PSC and UC were characterized by low bacterial diversity and significant change in global microbial composition. Rothia, Enterococcus, Streptococcus, Veillonella, and three other genera were markedly overrepresented in PSC regardless of concomitant inflammatory bowel disease (IBD). Rothia, Veillonella and Streptococcus were tracked to the species level to identify Rothia mucilaginosa, Streptococcus infantus, S. alactolyticus, and S. equi along with Veillonella parvula and V. dispar. PSC was further characterized by decreased abundance of Adlercreutzia equolifaciens and Prevotella copri. Decrease in genus Phascolarctobacterium was linked to presence of colonic inflammation regardless of IBD phenotype. Akkermansia muciniphila, Butyricicoccus pullicaecorum and Clostridium colinum were decreased in UC along with genus Roseburia. Low levels of serum albumin were significantly correlated with enrichment of order Actinomycetales.

CONCLUSION

PSC is associated with specific gut microbes independently of concomitant IBD and several bacterial taxa clearly distinguish IBD phenotypes (PSC-IBD and UC).

Identification of Helicobacter pylori and other Helicobacter species by PCR, hybridization, and partial DNA sequencing in human liver samples from patients with primary sclerosing cholangitis or primary biliary cirrhosis

Helicobacter pylori was identified in human liver tissue by PCR, hybridization, and partial DNA sequencing. Liver biopsies were obtained from patients with primary sclerosing cholangitis (n = 12), primary biliary cirrhosis (n = 12), and noncholestatic liver cirrhosis (n = 13) and (as controls) normal livers (n = 10). PCR analyses were carried out using primers for the Helicobacter genus, Helicobacter pylori (the gene encoding a species-specific 26-kDa protein and the 16S rRNA), Helicobacter bilis, Helicobacter pullorum, and Helicobacter hepaticus. Samples from patients with primary biliary cirrhosis and primary sclerosing cholangitis (11 and 9 samples, respectively) were positive by PCR with Helicobacter genus-specific primers. Of these 20 samples, 8 were positive with the 16S rRNA primer and 9 were positive with the 26-kDa protein primer of H. pylori. These nine latter samples were also positive by Southern blot hybridization for the amplified 26-kDa fragment, and four of those were verified to be H. pylori by partial 16S rDNA sequencing. None of the samples reacted with primers for H. bilis, H. pullorum, or H. hepaticus. None of the normal livers had positive results in the Helicobacter genus PCR assay, and only one patient in the noncholestatic liver cirrhosis group, a young boy who at reexamination showed histological features suggesting primary sclerosing cholangitis, had a positive result in the same assay. Helicobacter positivity was thus significantly more common in patients with cholestatic diseases (20 of 24) than in patients with noncholestatic diseases and normal controls (1 of 23) (P = <0.00001). Patients positive for Helicobacter genus had significantly higher values of alkaline phosphatases and prothrombin complex than Helicobacter-negative patients (P = 0.0001 and P = 0.0003, respectively). Among primary sclerosing cholangitis patients, Helicobacter genus PCR positivity was weakly associated with ulcerative colitis (P = 0.05). Significant differences related to blood group or HLA status were not found.

Extended analysis of a genome-wide association study in primary sclerosing cholangitis detects multiple novel risk loci

BACKGROUND & AIMS

A limited number of genetic risk factors have been reported in primary sclerosing cholangitis (PSC). To discover further genetic susceptibility factors for PSC, we followed up on a second tier of single nucleotide polymorphisms (SNPs) from a genome-wide association study (GWAS).

METHODS

We analyzed 45 SNPs in 1221 PSC cases and 3508 controls. The association results from the replication analysis and the original GWAS (715 PSC cases and 2962 controls) were combined in a meta-analysis comprising 1936 PSC cases and 6470 controls. We performed an analysis of bile microbial community composition in 39 PSC patients by 16S rRNA sequencing.

RESULTS

Seventeen SNPs representing 12 distinct genetic loci achieved nominal significance (p(replication) <0.05) in the replication. The most robust novel association was detected at chromosome 1p36 (rs3748816; p(combined)=2.1 × 10(-8)) where the MMEL1 and TNFRSF14 genes represent potential disease genes. Eight additional novel loci showed suggestive evidence of association (p(repl) <0.05). FUT2 at chromosome 19q13 (rs602662; p(comb)=1.9 × 10(-6), rs281377; p(comb)=2.1 × 10(-6) and rs601338; p(comb)=2.7 × 10(-6)) is notable due to its implication in altered susceptibility to infectious agents. We found that FUT2 secretor status and genotype defined by rs601338 significantly influence biliary microbial community composition in PSC patients.

CONCLUSIONS

We identify multiple new PSC risk loci by extended analysis of a PSC GWAS. FUT2 genotype needs to be taken into account when assessing the influence of microbiota on biliary pathology in PSC.

Bile duct bacterial isolates in primary sclerosing cholangitis: a study of explanted livers

BACKGROUND/AIMS

The pathogenesis of the inflammatory lesion in primary sclerosing cholangitis is unknown. The clinical picture is characterized by i.a. episodes of fever, the cause of which also remains speculative. Previous studies of bacterial isolates in the liver or bile ducts in primary sclerosing cholangitis have had the shortcoming of possible contamination associated with the sampling. The aim of this study was to investigate whether bile and bile duct tissue, obtained under sterile conditions in connection with liver transplantation, contain bacteria.

METHODS

We studied bile from bile duct walls and bile collected from the explanted livers of 36 patients with primary sclerosing cholangitis and 14 patients with primary biliary cirrhosis.

RESULTS

Positive cultures were obtained from 21 of 36 primary sclerosing cholangitis patients, but from none of the primary biliary cirrhosis patients. The number of bacterial strains was inversely related to the time after the last endoscopic retrograde cholangiography. Treatment with antibiotics or intraductal stent, or the occurrence of fever before liver transplantation did not seem to influence the culture results, whereas antibiotic treatment in connection with endoscopic retrograde cholangiography may possibly have reduced the number of isolates in the cultures. Alpha-haemolytic Streptococci were retrieved as late as 4 years after the last endoscopic retrograde cholangiography. Retrospective analysis of liver laboratory tests after endoscopic retrograde cholangiography did not indicate a deleterious effect of the investigation.

CONCLUSIONS

The data suggest that antibiotics should be given routinely in connection with endoscopic retrograde cholangiography. They also raise the question of a possible role of alpha-haemolytic Streptococci in the progression of primary sclerosing cholangitis.

Alterations in Intestinal Microbiota Lead to Production of Interleukin 17 by Intrahepatic γδ T-Cell Receptor-Positive Cells and Pathogenesis of Cholestatic Liver Disease

BACKGROUND & AIMS

Variants at the ABCB4 or MDR2 locus, which encodes a biliary transport protein, are associated with a spectrum of cholestatic liver diseases. Exacerbation of liver disease has been linked to increased hepatic levels of interleukin (IL) 17, yet the mechanisms of this increase are not understood. We studied mice with disruption of Mdr2 to determine how defects in liver and alteration in the microbiota contribute to production of IL17 by intrahepatic γδ T cells.

METHODS

We performed studies with Mdr2-/- and littermate FVB/NJ (control) mice. IL17 was measured in serum samples by an enzyme-linked immunosorbent assay. Mice were injected with neutralizing antibodies against the γδ T-cell receptor (TCR; anti-γδ TCR) or mouse IL17A (anti-IL17A). Livers were collected and bacteria were identified in homogenates by culture procedures; TCRγδ+ cells were isolated by flow cytometry. Fecal samples were collected from mice and analyzed by 16S ribosomal DNA sequencing. Cells were stimulated with antibodies or bacteria, and cytokine production was measured. We obtained tissues from 10 patients undergoing liver transplantation for primary sclerosing cholangitis or chronic hepatitis C virus infection. Tissues were analyzed for cytokine production by γδ TCR+ cells.

RESULTS

Mdr2-/- mice had collagen deposition around hepatic bile ducts and periportal-bridging fibrosis with influx of inflammatory cells and increased serum levels of IL17 compared with control mice. Administration of anti-IL17A reduced hepatic fibrosis. Livers from Mdr2-/- mice had increased numbers of IL17A+ γδTCR+ cells-particularly of IL17A+ Vγ6Jγ1 γδ TCR+ cells. Fecal samples from Mdr2-/- mice were enriched in Lactobacillus, and liver tissues were enriched in Lactobacillus gasseri compared with control mice. Mdr2-/- mice also had increased intestinal permeability. The γδ TCR+ cells isolated from Mdr2-/- livers produced IL17 in response to heat-killed L gasseri. Intraperitoneal injection of control mice with L gasseri led to increased serum levels of IL17 and liver infiltration by inflammatory cells; injection of these mice with anti-γδ TCR reduced serum level of IL17. Intravenous injections of Mdr2-/- mice with anti-γδ TCR reduced fibrosis; liver levels of IL17, and inflammatory cells; and serum levels of IL17. γδTCR+ cells isolated from livers of patients with primary sclerosing cholangitis, but not hepatitis C virus infection, produced IL17.

CONCLUSIONS

In Mdr2-/- mice, we found development of liver fibrosis and inflammation to require hepatic activation of γδ TCR+ cells and production of IL17 mediated by exposure to L gasseri. This pathway appears to contribute to development of cholestatic liver disease in patients.

The role of dominant stenoses in bacterial infections of bile ducts in primary sclerosing cholangitis

OBJECTIVE

Primary sclerosing cholangitis (PSC) is characterized by progressive fibrotic inflammation and strictures of the biliary system. We studied the role of dominant stenoses in bacterial biliary infections and the effect of routine antibiotic administration with cholangiography.

DESIGN

A prospective clinical trial without blinding or randomization.

SETTING

The endoscopy unit in a university hospital.

PARTICIPANTS

Fifty patients with PSC entered and finished the study.

INTERVENTIONS

A total of 103 endoscopic retrograde cholangiographies (ERC) was performed in 37 PSC patients with dominant stenosis and 13 controls with PSC but no dominant stenosis. After selective cannulation of the bile duct, bile samples were obtained during each procedure. All patients received systemic antibiotic treatment with ciprofloxacin for one week after ERC.

RESULTS

Enteric bacteria were detected in the bile specimens of 15 out of 37 PSC patients (40.5%) with dominant stenosis but never in the absence of dominant stenosis (P=0.004). Positive cultures for enteric bacteria were associated with elevated serum C-reactive protein, high leukocyte counts in bile (P<0.05) and the deterioration of liver function assessed by increasing bilirubin levels during the follow-up period lasting a median of 7 months (P=0.06). Despite the high rate of susceptibility in vitro, ciprofloxacin treatment eradicated enteric bacteria in only two out of 12 cases.

CONCLUSION

Bacterial infection of the bile ducts with dominant stenosis is a frequent finding and may play a role in the progression of PSC. Short-course antibiotic treatment is not very effective in eradicating acteria from the bile ducts.

Gut microbiome in primary sclerosing cholangitis: A review

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by biliary inflammation and stricturing. Exploration of the pathogenesis of PSC in light of its association with inflammatory bowel disease (IBD) and the “gut-liver” axis is an emerging area of interest. A growing number of studies have begun to elucidate the role of the gut microbiota, its metabolites and its influence on host immune responses in the development of PSC and PSC-IBD. Studies of the fecal microbiota have highlighted enriched levels of certain species, including Veillonella, Streptococcus and Enterococcus, among others. A heightened immune response to enteric dysbiosis and bacterial translocation have also been implicated. For example, Klebsiella pneumoniae strains derived from gnotobiotic mice transplanted with PSC-IBD microbiota were found to induce pore formation in human intestinal epithelial cells and enhanced Th17 responses. Gut microbes have additionally been hypothesized to be implicated in PSC pathogenesis through their role in the synthesis of various metabolites, including bile acids (BAs), which function as signaling molecules with important gut and hepatic effects. An expanded knowledge of the gut microbiome as it relates to PSC offers critical insight into the development of microbe-altering therapeutic interventions, such as antibiotics, nutritional interventions and fecal microbial transplantation. Some of these have already shown some preliminary evidence of benefit. Despite exciting progress in the field, much work remains to be done; areas that are particularly lacking include functional characterization of the microbiome and examination of pediatric populations. In this review, we summarize studies that have investigated the microbiome in PSC and PSC-IBD as well as putative mechanisms, including the potential role of metabolites, such as BAs. We then briefly review the evidence for interventions with microbe-altering properties for treating PSC.

Review article: Helicobacter species and hepatobiliary diseases

Helicobacter species, which may colonize the biliary tract, have been implicated as a possible cause of hepatobiliary diseases ranging from chronic cholecystitis and primary sclerosing cholangitis to gall-bladder carcinoma and primary hepatic carcinomas. Research in this area has been limited by the lack of a gold standard in the diagnosis of these organisms in bile. Most published data to date have been based on molecular techniques that detect the DNA of Helicobacter species in bile, rather than evidence of viable organisms in bile. Helicobacter species have not been shown to induce histological injury to the biliary epithelium or liver parenchyma. The strongest association of the presence of these organisms in bile is with cholestatic conditions. This article reviews the literature on this newly developing field as it has evolved historically, taking pertinent methodological issues into account.

Role of the microbiota and antibiotics in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is an idiopathic, progressive, cholestatic liver disease with considerable morbidity and mortality and no established pharmacotherapy. In addition to the long-recognized association between PSC and inflammatory bowel disease, several lines of preclinical and clinical evidence implicate the microbiota in the etiopathogenesis of PSC. Here we provide a concise review of these data which, taken together, support further investigation of the role of the microbiota and antibiotics in PSC as potential avenues toward elucidating safe and effective pharmacotherapy for patients afflicted by this illness.

Primary sclerosing cholangitis and the microbiota: current knowledge and perspectives on etiopathogenesis and emerging therapies

Primary sclerosing cholangitis (PSC) is a chronic, fibroinflammatory, cholestatic liver disease of unknown etiopathogenesis. PSC generally progresses to liver cirrhosis, is a major risk factor for hepatobiliary and colonic neoplasia, and confers a median survival to death or liver transplantation of only 12 years. Although it is well recognized that approximately 75% of patients with PSC also have inflammatory bowel disease (IBD), the significance of this association remains elusive. Accumulating evidence now suggests a potentially important role for the intestinal microbiota, and enterohepatic circulation of molecules derived therefrom, as a putative mechanistic link between PSC and IBD and a central pathobiological driver of PSC. In this concise review, we provide a summary of and perspectives regarding the relevant basic, translational, and clinical data, which, taken together, encourage further investigation of the role of the microbiota and microbial metabolites in the etiopathogenesis of PSC and as a potential target for novel pharmacotherapies.

Bile microbiota in primary sclerosing cholangitis: Impact on disease progression and development of biliary dysplasia

Objective

The etiopathogenesis and risk for development of biliary neoplasia in primary sclerosing cholangitis (PSC) are largely unknown. Microbes or their metabolites have been suggested to play a role. To explore this potential microbial involvement, we evaluated the differences in biliary microbiota in PSC patients at an early disease stage without previous endoscopic retrograde cholangiography (ERC) examinations, advanced disease stage, and with biliary dysplasia or cholangiocarcinoma.

Design

Bile samples from the common bile duct were collected from 46 controls and 80 patients with PSC during ERC (37 with early disease, 32 with advanced disease, and 11 with biliary dysplasia). DNA isolation, amplification, and Illumina MiSeq sequencing were performed for the V1-V3 regions of the bacterial 16S rRNA gene.

Results

The most common phyla found were Bacteroidetes, Firmicutes, Proteobacteria, Fusobacteria, and Actinobacteria. The most common families were Prevotellaceae, Streptococcaceae, Veillonellaceae, Fusobacteriaceae, and Pasteurellaceae, and the most common genera were Prevotella, Streptococcus, Veillonella, Fusobacterium, and Haemophilus. The bacterial communities of non-PSC subjects and early stage PSC patients were similar. Alpha diversity was lower in patients with biliary dysplasia/cholangiocarcinoma than in other groups. An increase in Streptococcus abundance was positively correlated with the number of ERC examinations. Streptococcus abundance was also positively correlated with an increase in disease severity, even after controlling for the number of ERC examinations.

Conclusions

Our findings suggest that the aetiology of PSC is not associated with changes in bile microbial communities, but the genus Streptococcus may play a pathogenic role in the progression of the disease.

Biliary candida infections in primary sclerosing cholangitis

BACKGROUND/AIMS

Patients with Primary Sclerosing Cholangitis (PSC) frequently develop dominant stenoses of the bile ducts and bacterial infections represent a major problem in such patients. In the present study, the role of fungal infections of the bile ducts has been evaluated.

METHODS

In a prospective non-randomized trial, in 67 consecutive patients with PSC, 148 bile samples, each taken at one endoscopic examination, were microbiologically analysed.

RESULTS

Candida species were found in 8/67 patients whereas Aspergillus was not detected. Seven patients with biliary Candida had a dominant stenosis and one had a wide papillotomy with chronic ascending cholangitis. Altogether 7/49 of patients with dominant stenosis and 1/18 of patients without dominant stenosis had Candida in their bile. All patients with biliary Candida intermittently had received antibiotics and had advanced disease with cholestasis. Candida disappeared spontaneously in 2/7 patients, cleared after antifungal treatment in 2, and persisted in 3 patients. Patients with biliary Candida had more severe cholangitis with higher CRP and serum bilirubin compared to those without Candida infection.

CONCLUSIONS

This is the first report on the identification of Candida species in the bile of patients with PSC. Apart from bacterial also fungal infection of the bile ducts should be considered in the treatment of such patients.

Sclerosing cholangitis associated to cryptosporidiosis in liver-transplanted children

Three children of a series of 461 pediatric liver transplant recipients developed diffuse cholangitis associated with intestinal cryptosporidium carriage. All three received immunosuppression consisting of tacrolimus and prednisone. Cryprosporidium carriage was treated with paramomycin, while immunosuppression was decreased according to graft tolerance. No other infectious pathogens were found, and no vascular problems were detected. Bile duct anastomosis was reoperated in all three, but biliary cirrhosis developed in one patient, requiring retransplantation. All three patients are alive and well, and free of intestinal parasites on follow-up.

CONCLUSION

Cryptosporidium intestinal infection may play a role in some cases of otherwise unexplained cholangiopathies in pediatric liver transplant recipients. This may lead to significant morbidity, including need for retransplantation.

Impact of Microbes on the Pathogenesis of Primary Biliary Cirrhosis (PBC) and Primary Sclerosing Cholangitis (PSC)

Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC) represent the major clinical entities of chronic cholestatic liver diseases. Both disorders are characterized by portal inflammation and slowly progress to obliterative fibrosis and eventually liver cirrhosis. Although immune-pathogenic mechanisms have been implicated in the pathogenesis of PBC and PSC, neither disorder is considered to be a classical autoimmune disease, as PSC and PBC patients do not respond to immune-suppressants. Furthermore, the decreased bile flow resulting from the immune-mediated tissue assault and the subsequent accumulation of toxic bile products in PBC and PSC not only perpetuates biliary epithelial damage, but also alters the composition of the intestinal and biliary microbiota and its mutual interactions with the host. Consistent with the close association of PSC and inflammatory bowel disease (IBD), the polyclonal hyper IgM response in PBC and (auto-)antibodies which cross-react to microbial antigens in both diseases, an expansion of individual microbes leads to shifts in the composition of the intestinal or biliary microbiota and a subsequent altered integrity of epithelial layers, promoting microbial translocation. These changes have been implicated in the pathogenesis of both devastating disorders. Thus, we will discuss here these recent findings in the context of novel and alternative therapeutic options.

A survey of infectious agents as risk factors for primary sclerosing cholangitis: are Chlamydia species involved?

OBJECTIVES

The aetiology of primary sclerosing cholangitis (PSC) is unknown, and the role of micro-organisms has been studied only to a limited extent. We tested the hypothesis that past or persisting infection with common viruses or atypical bacteria might play a role in genetically susceptible hosts.

DESIGN

Case-control study.

METHODS

Serological screening for antibodies against 22 viruses as well as Chlamydia spp. and Mycoplasma pneumoniae was carried out in 41 well-established PSC patients. All 5110 sera tested in 1997 for these micro-organisms at our laboratory served as a background reference group. Subsequently, Chlamydia anti-lipopolysaccharide (LPS) antibodies were determined by enzyme-linked immunosorbent assay (ELISA) in the PSC group and in three race-matched control groups (inflammatory bowel disease (IBD) group, n = 35; non-IBD patients group, n = 39; healthy blood donor group, n = 40). Subtyping in Chlamydia trachomatis and C. pneumoniae serotypes by specific anti-major outer membrane protein (MOMP) assays was carried out in the four groups. Immunohistochemical staining using specific markers for chlamydiae was carried out on liver biopsies of 14 PSC patients.

RESULTS

There was a markedly elevated seroprevalence of Chlamydia-LPS antibodies compared with the 1997 reference group. The odds ratios (ORs) for the presence of immunoglobulin G, immunoglobulin M and immunoglobulin A antibodies for the PSC patients versus the control group were 2.4 (95% confidence interval (CI) 1.1 to 5.4), 1.9 (95% CI 0.9 to 4.0) and 6.7 (95% CI 3.0 to 17.0), respectively. All other micro-organisms tested showed normal antibody profiles that did not differ from the 1997 reference group. The seroprevalence of Chlamydia-anti-LPS antibodies was elevated markedly in the PSC patients compared with the IBD, non-IBD and blood donor groups. The outcomes in the C. trachomatis and C. pneumoniae anti-MOMP assays did not correlate with the anti-LPS-positive PSC sera. The actual presence of Chlamydia bodies in liver tissue could not be demonstrated.

CONCLUSION

Our findings suggest an association between PSC and (previous) infection with Chlamydia.

The Gut-Liver Axis in Cholestatic Liver Diseases

The gut-liver axis describes the physiological interplay between the gut and the liver and has important implications for the maintenance of health. Disruptions of this equilibrium are an important factor in the evolution and progression of many liver diseases. The composition of the gut microbiome, the gut barrier, bacterial translocation, and bile acid metabolism are the key features of this cycle. Chronic cholestatic liver diseases include primary sclerosing cholangitis, the generic term secondary sclerosing cholangitis implying the disease secondary sclerosing cholangitis in critically ill patients and primary biliary cirrhosis. Pathophysiology of these diseases is not fully understood but seems to be multifactorial. Knowledge about the alterations of the gut-liver axis influencing the pathogenesis and the outcome of these diseases has considerably increased. Therefore, this review aims to describe the function of the healthy gut-liver axis and to sum up the pathological changes in these cholestatic liver diseases. The review compromises the actual level of knowledge about the gut microbiome (including the mycobiome and the virome), the gut barrier and the consequences of increased gut permeability, the effects of bacterial translocation, and the influence of bile acid composition and pool size in chronic cholestatic liver diseases. Furthermore, therapeutic implications and future scientific objectives are outlined.

Sclerosing cholangitis and liver cirrhosis after extrabiliary infections: report on three cases

OBJECTIVE

To describe three unusual cases of sclerosing cholangitis after severe extrahepatic/extrabiliary bacterial infections.

DESIGN

Case report, clinical.

SETTING

Tertiary care intensive care unit (ICU).

PATIENTS

Three patients admitted to the ICU with infections from Gram-positive bacteria followed by sclerosing cholangitis and secondary biliary cirrhosis.

MAIN RESULTS

Three unusual cases of persisting cholestasis that occurred after bacterial infections originating from extrahepatic/extrabiliary foci are described. Endoscopic retrograde cholangiopancreatography and magnetic resonance cholangiopancreatography revealed multiple strictures of the intrahepatic bile ducts as a sign of sclerosing cholangitis. All patients progressed to biliary cirrhosis within months after the onset of cholestasis.

CONCLUSION

Infection-associated cholestasis is usually a functional disorder and subsides after effective treatment of the underlying inflammatory focus. In rare cases, however, extrahepatic/extrabiliary infections may lead to sclerosing cholangitis and secondary biliary cirrhosis via unknown mechanisms.

Helicobacter pylori may play a contributory role in the pathogenesis of primary sclerosing cholangitis

Helicobacter pylori (H. pylori) DNA has been identified in human livers and has been implicated in chronic liver disease and liver cancer. To better understand the role of H pylori in primary sclerosing cholangitis (PSC), 25 patients with end-stage PSC and 31 controls were studied. Genomic DNA was extracted from microdissected hilar hepatic ducts of liver explants and was amplified for H pylori DNA. Serum was tested for H pylori antibodies. Helicobacter DNA was detected in 9 of the 56 (16%) patients by 16SrRNA PCR (an additional case [for a total of 18%] was antibody positive). Seven of the 9 cases identified by polymerase chain reaction were positive for the CagA gene, confirming they were H pylori. Seven of the 25 (28%) patients with PSC and 3 of the 31 (9.7%) controls were positive for Helicobacter (P=.087). H pylori DNA was detected in microdissected hilar biliary epithelium in more PSC patients than controls, supporting the hypothesis that bile reflux from the duodenum into the biliary tract might carry H pylori organisms into the proximal biliary system, possibly contributing to PSC development and/or progression in some patients.

Biliary phosphatidylcholine and lysophosphatidylcholine profiles in sclerosing cholangitis

AIM: To analyze phospholipid profiles in intrahepatic bile from patients with primary sclerosing cholangitis (PSC) and secondary sclerosing cholangitis (SSC).

METHODS: Intrahepatic bile specimens collected via endoscopic retrograde cholangiography from 41 patients were analyzed. Fourteen of these patients were diagnosed with PSC, 10 with SSC, 11 with choledocholithiasis or no identifiable biliary disease, and 6 with cholangiocellular carcinoma (CCC). Bile acid, cholesterol, protein, and bilirubin contents as well as pancreas lipase activity in bile were determined by biochemical methods. Phosphatidylcholine (PC) and lysophosphatidylcholine (LPC) species were quantified using nano-electrospray ionization tandem mass spectrometry.

RESULTS: Bile from all the examined patient groups showed a remarkably similar PC and LPC species composition, with only minor statistical differences. Total biliary PC concentrations were highest in controls (8030 ± 1843 μmol/L) and lowest in patients with CCC (1969 ± 981 μmol/L) (P = 0.005, controls vs SSC and CCC, respectively, P < 0.05). LPC contents in bile were overall low (4.2% ± 1.8%). Biliary LPC/PC ratios and ratios of biliary PC to bilirubin, PC to cholesterol, PC to protein, and PC to bile acids showed no intergroup differences.

CONCLUSION: PC and LPC profiles being similar in patients with or without sclerosing cholangitis, these phospholipids are likely not of major pathogenetic importance in this disease group.

The role of Helicobacter spp. in the pathogenesis of primary biliary cirrhosis and primary sclerosing cholangitis

Helicobacter species DNA has been detected in liver tissue of patients affected by primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). To investigate a potential causative relation between Helicobacter species and PBC/PSC, we compared the presence of Helicobacter species-specific DNA in liver tissue of patients with PBC/PSC (n=18/n=13) with those of a control group of patients with various liver diseases with known cause (n=29). A PCR with Helicobacter genus-specific 16S rRNA primers was performed on DNA isolated from paraffin embedded liver tissue. Control patients had hepatitis-B (n=9), alcoholic cirrhosis (n=14), or non-cirrhotic metabolic liver disease (n=6). There was no significant difference between the incidence of Helicobacter spp.-specific DNA in PBC/PSC (9/31; 29%) and the control group (10/29; 34%). Sequence analysis confirmed Helicobacter spp. DNA. Because Helicobacter spp. DNA can be found in approximately one-third of all samples tested, it is unlikely that PSC and PBC are caused by Helicobacter infection.

Fut2 genotype is a risk factor for dominant stenosis and biliary candida infections in primary sclerosing cholangitis

BACKGROUND

A recent genome-wide association study identified the FUT2 secretor status and genotype defined by the single-nucleotide polymorphism rs601338 as potential genetic risk factor in primary sclerosing cholangitis (PSC), which significantly influences biliary bacterial composition.

AIM

To determine the impact of the rs601338-FUT2 genotype on frequency of biliary infections, development of dominant stenosis and liver-transplantation-free survival in patients with PSC.

METHODS

Cohort study of 215 patients with PSC treated at our tertiary care centre with respect to their rs601338-FUT2 genotype. Results of endoscopic retrograde cholangiography and bile culture were analysed; 639 biliary samples were obtained, cultured and subjected to microbial analysis. Clinical and laboratory data were analysed using chart reviews.

RESULTS

For the rs601338-FUT2 genotype, 69 patients (32.1%) were found to be wildtype (GG), 97 (45.1%) patients were heterozygous (AG) and 49 patients (22.8%) were homozygous-mutated (AA). In addition to alterations in the bacterial pattern, especially in heterozygous carriers, patients with mutated alleles had a marked increase in the frequency of biliary Candida infections (P = 0.025). Further, patients with mutated alleles showed an increased frequency of episodes of cholangitis (P = 0.0025), development of dominant stenosis (P < 0.002) and a reduced actuarial transplantation-free survival (P = 0.044). Levels of biliary Ca19-9 were significantly elevated in the homozygous-mutated patients.

CONCLUSIONS

The rs601338-FUT2 genotype is strongly associated with episodes of cholangitis, fungobilia and the incidence of dominant stenosis, which are three clinical hallmarks of PSC; FUT2 is thus an important genetic risk factor for host-microbial diversity and disease progression in PSC.

Successful treatment of AIDS-related cryptosporidial sclerosing cholangitis

OBJECTIVE

Cryptosporidium is a well recognized cause of AIDS-related sclerosing cholangitis for which no efficacious therapy exists at present. We evaluated the efficiency of the combination of paromomycin and letrazuril in the treatment of this condition.

CASE REPORT

We report a case of cryptosporidial cholangitis in a patient with AIDS who responded to treatment with intravenous paromomycin followed by oral letrazuril as maintenance therapy.

CONCLUSION

The combination of paromomycin and letrazuril should be considered in the treatment of AIDS-related sclerosing cholangitis.

Hepcidin is an antibacterial, stress-inducible peptide of the biliary system

BACKGROUND/AIMS

Hepcidin (gene name HAMP), an IL-6-inducible acute phase peptide with antimicrobial properties, is the key negative regulator of iron metabolism. Liver is the primary source of HAMP synthesis, but it is also produced by other tissues such as kidney or heart and is found in body fluids such as urine or cerebrospinal fluid. While the role of hepcidin in biliary system is unknown, a recent study demonstrated that conditional gp130-knockout mice display diminished hepcidin levels and increased rate of biliary infections.

METHODS

Expression and localization of HAMP in biliary system was analyzed by real time RT-PCR, in-situ hybridization, immunostaining and -blotting, while prohepcidin levels in human bile were determined by ELISA.

RESULTS

Hepcidin was detected in mouse/human gallbladder and bile duct epithelia. Biliary HAMP is stress-inducible, in that it is increased in biliary cell lines upon IL-6 stimulation and in gallbladder mucosa of patients with acute cholecystitis. Hepcidin is also present in the bile and elevated prohepcidin levels were observed in bile of primary sclerosing cholangitis (PSC) patients with concurrent bacterial cholangitis compared to PSC subjects without bacterial infection (median values 22.3 vs. 8.9; p = 0.03). In PSC-cholangitis subjects, bile prohepcidin levels positively correlated with C-reactive protein and bilirubin levels (r = 0.48 and r = 0.71, respectively). In vitro, hepcidin enhanced the antimicrobial capacity of human bile (p<0.05).

CONCLUSION

Hepcidin is a stress-inducible peptide of the biliary epithelia and a potential marker of biliary stress. In the bile, hepcidin may serve local functions such as protection from bacterial infections.

Emerging pharmacologic therapies for primary sclerosing cholangitis

PURPOSE OF REVIEW

The only currently approved treatment for primary sclerosing cholangitis (PSC) is liver transplantation, with a median time to transplant of 12-18 years after diagnosis. There are a number of emerging drugs that have the potential to meet this critically unmet need that will be summarized and discussed herein.

RECENT FINDINGS

Although the cause of PSC is unknown, there are a number of novel therapeutics under development. These drugs target presumed pathogenic mechanisms largely extrapolated from ex-vivo and in-vivo preclinical models, as well as translational observations.

SUMMARY

Future therapeutic strategies for PSC may include a multitude of complex pathogenic mechanisms encompassing pathways of immunomodulation, the microbiome and inflammation-related fibrosis.