Primary sclerosing cholangitis: 50 years of a gut-liver relationship and still no love?

Intestinal microbiota and biliary system diseases

Introduction

The incidence of biliary system diseases has been continuously increasing in the past decade. Biliary system diseases bring a heavy burden to humanity and society. However, the specific etiology and pathogenesis are still unknown. The biliary system, as a bridge between the liver and intestine, plays an indispensable role in maintaining the physiological metabolism of the body. Therefore, prevention and treatment of biliary diseases are crucial. It is worth noting that the microorganisms participate in the lipid metabolism of the bile duct, especially the largest proportion of intestinal bacteria.

Methods

We systematically reviewed the intestinal microbiota in patients with gallstones (GS), non-calculous biliary inflammatory, and biliary tract cancer (BTC). And searched Pubmed, Embase and Web of science for research studies published up to November 2023.

Results

We found that the abundance of Faecalibacterium genus is decreased in GS, primary sclerosing cholangitis (PSC), primary biliary cholangitis (PBC) and BTC. Veillonella, Lactobacillus, Streptococcus and Enterococcus genus were significantly increased in PSC, PBC and BTC. Interestingly, we found that the relative abundance of Clostridium was generally reduced in GS, PBC and BTC. However, Clostridium was generally increased in PSC.

Discussion

The existing research mostly focuses on exploring the mechanisms of bacteria targeting a single disease. Lacking comparison of multiple diseases and changes in bacteria during the disease process. We hope to provide biomarkers forearly diagnosis of biliary system diseases and provide new directions for the mechanism of intestinal microbiota in biliary diseases.

Efficacy and safety of biologics in primary sclerosing cholangitis with inflammatory bowel disease: A systematic review and meta-analysis

BACKGROUND

Primary sclerosing cholangitis (PSC) is an immune-mediated, chronic cholestatic liver disease. Currently, liver transplantation is the only established life-saving treatment. Several studies have evaluated the effect of different biologic therapies on PSC with inconclusive findings. We conducted a systematic review and meta-analysis to assess the effects of biologics in PSC and associated inflammatory bowel disease (IBD).

METHODS

MEDLINE, Scopus, and Embase were searched up to July 31, 2023, for studies reporting the effects of biologics in patients with PSC-IBD. Effects of biologic therapy on alkaline phosphatase, total bilirubin, ulcerative colitis response score, and adverse events were calculated and expressed as standardized difference of means (SMD), proportions, and 95% CI using a random-effects model.

RESULTS

Six studies, including 411 PSC-IBD patients who received biologics, were included. Biologic treatment was associated with no change in alkaline phosphatase (SMD: 0.1, 95% CI: -0.07 -0.17, p=0.43), but a small and statistically significant increase in total bilirubin (SMD: 0.2, 95% CI: 0.05-0.35, p<0.01). 31.2% (95% CI: 23.8-39.7) of patients with IBD achieved endoscopic response, and there was a significant improvement in ulcerative colitis response score (SMD: -0.6,95% CI: -0.88 to 0.36, p<0.01). Furthermore, 17.6% (95% CI: 13.0-23.5) of patients experienced adverse events severe enough to discontinue therapy, and 29.9% (95% CI: 25.2-34.8) had a loss of response to biologics.

CONCLUSIONS

Treatment of patients with PSC-IBD with biologics (vedolizumab, infliximab, and adalimumab) was not associated with improvement of biochemical markers of cholestasis. Biologics are effective in treating the colitis associated with PSC. Vedolizumab was associated with worsening liver enzymes in contrast to other biologics, a finding that warrants further study.

Low prevalence of primary sclerosing cholangitis in patients with inflammatory bowel disease in India

BACKGROUND/AIMS

Primary sclerosing cholangitis (PSC) represents the most common hepatobiliary extraintestinal manifestation of inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn's disease (CD). Limited data exist on PSC in patients with IBD from India. We aimed to assess the prevalence and disease spectrum of PSC in Indian patients with IBD.

METHODS

Database of IBD patients at 5 tertiary care IBD centers in India were analyzed retrospectively. Data were extracted and the prevalence of PSC-IBD was calculated.

RESULTS

Forty-eight patients out of 12,216 patients with IBD (9,231 UC, 2,939 CD, and 46 IBD unclassified) were identified to have PSC, resulting in a prevalence of 0.39%. The UC to CD ratio was 7:1. Male sex and pancolitis (UC) or colonic CD were more commonly associated with PSC-IBD. The diagnosis of IBD preceded the diagnosis of PSC in most of the patients. Majority of the patients were symptomatic for liver disease at diagnosis. Eight patients (16.66%) developed cirrhosis, 5 patients (10.41%), all UC, developed malignancies (3 colorectal cancer [6.25%] and 2 cholangiocarcinoma [4.16%]), and 3 patients died (2 decompensated liver disease [4.16%] and 1 cholangiocarcinoma [2.08%]) on follow-up. None of the patients mandated surgical therapy for IBD.

CONCLUSIONS

Concomitant PSC in patients with IBD is uncommon in India and is associated with lower rates of development of malignancies.

Comparative analysis of bile metabolic profile in patients with biliary obstruction complicated by Clonorchis sinensis infection

Background

Clonorchiasis is an important foodborne parasitic disease. However, eggs of Clonorchis sinensis (C. sinensis) cannot be detected in feces during biliary obstruction. Moreover, many diseases can cause biliary obstruction, such as gallstones, adenocarcinoma, cholangiocarcinoma and Ascaris lumbricoides infection. Therefore, it is of great significance to distinguish between patients of biliary obstruction and biliary obstruction with C. sinensis infection.

Methods

A total of 48 biliary obstruction patients were enrolled, including 23 infected with C. sinensis (C. sinensis) (OB+C.s) and 25 non-infected subjects (OB). The bile samples were collected by endoscopic retrograde cholangiopancreatography and analyzed using ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF MS). Additionally, multivariate statistical analysis methods were employed to identify differential metabolites. Next, bile amino acid levels were determined by targeted metabolomics analysis.

Result

A total of 146 and 132 significant metabolites were identified in electrospray ionization (ESI)+ and ESI- modes, respectively. The levels of amino acids (asparagine, glutamate, ornithine) and polyamines (spermidine and spermine) were significantly changed. Targeted analysis showed that the levels of amino acids (such as L-arginine, L-glutamine, L-lysine, L-propionic, and L-tyrosine) were lower in OB+C.s patients compared to those in OB patients. Marked metabolic pathways were involved in "Glutathione metabolism", "Caffeine metabolism", "Alanine, aspartate and glutamate metabolism", "Arginine and proline metabolism", "Purine metabolism", "Beta-Alanine metabolism", and "D-glutamine and D-glutamate metabolism".

Conclusion

These results show that there were significant differences between OB+C.s and OB patients, especially in amino acids. The metabolic signature and perturbations in metabolic pathways may help to better distinguish OB+C.s and OB patients.

Gut-liver axis: Pathophysiological concepts and clinical implications

Bidirectional crosstalk along the gut-liver axis controls gastrointestinal health and disease and exploits environmental and host mediators. Nutrients, microbial antigens, metabolites, and bile acids regulate metabolism and immune responses in the gut and liver, which reciprocally shape microbial community structure and function. Perturbation of such host-microbe interactions is observed in a variety of experimental liver diseases and is facilitated by an impaired intestinal barrier, which is fueling hepatic inflammation and disease progression. Clinical evidence describes perturbation of the gut-liver crosstalk in non-alcoholic fatty liver disease, alcoholic liver disease, and primary sclerosing cholangitis. In liver cirrhosis, a common sequela of these diseases, the intestinal microbiota and microbial pathogen-associated molecular patterns constitute liver inflammation and clinical complications, such as hepatic encephalopathy. Understanding the intricate metabolic interplay between the gut and liver in health and disease opens an avenue for targeted therapies in the future, which is probed in controlled clinical trials.

A Randomized, Dose-Finding, Proof-of-Concept Study of Berberine Ursodeoxycholate in Patients With Primary Sclerosing Cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a fibroinflammatory disease of the bile ducts leading to cirrhosis and hepatic decompensation. There are no approved pharmaceutical therapies for PSC. Berberine ursodeoxycholate (HTD1801) is an ionic salt of berberine and ursodeoxycholic acid with pleiotropic mechanisms of action.

METHODS

An 18-week proof-of-concept study was conducted to assess the safety and efficacy of HTD1801 in PSC. This study had three 6-week periods: (i) a placebo-controlled period, (ii) a treatment extension period, and (iii) a randomized treatment withdrawal period. The primary end point was change from baseline in alkaline phosphatase (ALP) at week 6.

RESULTS

Fifty-five patients were randomized and treated; 35 (64%) had inflammatory bowel disease and 22 (40%) had previously received ursodeoxycholic acid. Patients were initially randomized to placebo (n = 16), HTD1801 500 mg BID (n = 15), or HTD1801 1000 mg BID (n = 24). At baseline, mean (range) ALP values were 414 U/L (138-1,048), 397 U/L (237-773), and 335 U/L (122-882) for the placebo, HTD1801 500 mg BID, and HTD1801 1,000 mg BID groups, respectively. At week 6, a significant decrease in ALP was observed with HTD1801 (least square mean; HTD1801 500 mg BID = -53 U/L, P = 0.016; HTD1801 1000 mg BID = -37 U/L, P = 0.019) compared with placebo (98 U/L). ALP reductions were sustained through week 18 in those who remained on therapy, whereas ALP increased in those who crossed over to placebo during period 3. HTD1801 was generally well tolerated; 4 patients experienced serious adverse events, none attributed to HTD1801.

DISCUSSION

HTD1801 is associated with significant improvement in ALP and warrants further study as a treatment for PSC.

Potential Association of Doxycycline With the Onset of Primary Sclerosing Cholangitis: A Case Series

BACKGROUND

Primary sclerosing cholangitis (PSC) is linked to inflammatory bowel diseases (IBD). Evidence suggests an association between the gut microbiome and PSC. However, the putative relationship between exposure to antibiotics and onset of PSC has never been reported. We observed 3 cases in which patients without antecedent liver or bowel issues developed symptoms leading to diagnosis of IBD and subsequently PSC after being exposed to doxycycline. We aimed to identify, through the PSC Partners national patient registry, additional cases of PSC in which there is a temporal relationship between exposure to doxycycline and onset of PSC or PSC-IBD.

AREAS OF UNCERTAINTY

The etiopathogenesis of PSC remains an enigma.

DATA SOURCES

We collected data from patients with PSC and PSC-IBD in which there seemed to be a temporal relationship between exposure to doxycycline and PSC. Time from doxycycline exposure to: (1) onset of PSC or PSC-IBD symptoms and (2) diagnosis of PSC were documented for each patient. Descriptive statistical analyses were performed.

RESULTS

We identified 6 additional patients with PSC or PSC-IBD in whom there was a temporal relationship between exposure to doxycycline and onset of PSC or PSC-IBD. The median age of these 9 patients was 20 years, 6 were female, and 7 had ulcerative colitis. The median time from doxycycline exposure to onset of first symptoms was 3 months, and median time from doxycycline exposure to diagnosis of PSC was 15 months.

THERAPEUTIC HYPOTHESIS

We describe 9 cases of PSC and PSC-IBD in which there seem to be a temporal relationship between exposure to doxycycline and onset of PSC.

Gender and Autoimmune Liver Diseases: Relevant Aspects in Clinical Practice

Autoimmune liver diseases (AILDs) include autoimmune hepatitis, primary biliary cholangitis and primary sclerosing cholangitis. The etiologies of AILD are not well understood but appear to involve a combination of genetic and environmental factors. AILDs commonly affect young individuals and are characterized by a highly variable clinical course. These diseases significantly influence quality of life and can progress toward liver decompensation or the onset of hepatocellular or cholangiocarcinoma; a significant number of patients eventually progress to end-stage liver disease, requiring liver transplantation. In this review, we focus on the sex characteristics and peculiarities of AILD patients and highlight the relevance of a sex-specific analysis in future studies. Understanding the sex differences underlying AILD immune dysregulation may be critical for developing more effective treatments.

Primary Biliary Cholangitis and Primary Sclerosing Cholangitis: Current Knowledge of Pathogenesis and Therapeutics

Cholangiopathies encompass various biliary diseases affecting the biliary epithelium, resulting in cholestasis, inflammation, fibrosis, and ultimately liver cirrhosis. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the most important progressive cholangiopathies in adults. Much research has broadened the scope of disease biology to genetic risk, epigenetic changes, dysregulated mucosal immunity, altered biliary epithelial cell function, and dysbiosis, all of which interact and arise in the context of ill-defined environmental triggers. An in-depth understanding of the molecular pathogenesis of these cholestatic diseases will help clinicians better prevent and treat diseases. In this review, we focus on the main underlying mechanisms of disease initiation and progression, and novel targeted therapeutics beyond currently approved treatments.

Inflammatory pathways and cholangiocarcinoma risk mechanisms and prevention

Cholangiocarcinoma (CCA), a neoplasm burdened by a poor prognosis and currently lacking adequate therapeutic treatments, can originate at different levels of the biliary tree, in the intrahepatic, hilar, or extrahepatic area. The main risk factors for the development of CCA are the presence of chronic cholangiopathies of various etiology. To date, the most studied prodromal diseases of CCA are primary sclerosing cholangitis, Caroli's disease and fluke infestations, but other conditions, such as metabolic syndrome, nonalcoholic fatty liver disease and obesity, are emerging as associated with an increased risk of CCA development. In this review, we focused on the analysis of the pro-inflammatory mechanisms that induce the development of CCA and on the role of cells of the immune response in cholangiocarcinogenesis. In very recent times, these cellular mechanisms have been the subject of emerging studies aimed at verifying how the modulation of the inflammatory and immunological responses can have a therapeutic significance and how these can be used as therapeutic targets.

Si-Wu-Tang ameliorates fibrotic liver injury via modulating intestinal microbiota and bile acid homeostasis

Background

Fibrotic liver injury is a progressive scarring event, which may permanently affect liver function and progress into devastating end-stage liver diseases due to the absence of effective therapies. Si-Wu-Tang (SWT), a traditional Chinese medicine formula used in clinic to treat gynecological disorders for centuries, has been investigated in recent preliminary findings for its role in alleviating chronic liver diseases. Here we aim to elucidate the therapeutic effects and possible mechanisms of SWT against fibrotic liver injury.

Methods

UHPLC-MS/MS was performed to investigate the chemical characterization of SWT. After intragastrically administered with carbon tetrachloride (CCl₄) every 3 days for 1-week, C57BL/6 mice were orally administered with SWT (5.2, 10.4 and 20.8 g/kg) once daily for 3 weeks along with CCl₄ challenge. Liver function was determined by the measurement of serum biomarkers, hematoxylin and eosin (H&E) and Masson’s trichrome staining. Intestinal inflammatory infiltration and the disruption of intestinal barrier were examined by H&E and E-cadherin immunohistochemical staining. The microbial composition of intestinal content was determined by 16S rRNA sequencing. Serum bile acids (BAs) profiling was analyzed by LC–MS/MS. Simultaneously, the expression of genes of interest was determined by qPCR and western blot.

Results

SWT exhibited remarkable therapeutic effects on CCl₄-induced liver fibrosis, as indicated by improved collagen accumulation in livers, intestinal barrier injury and hepatic and intestinal inflammatory response. Results of 16S rRNA sequencing revealed that SWT treatment strikingly restructured intestinal microbiota in fibrotic mice by increasing the relative abundances of Bacteroides and Lachnoclostridium and decreasing the relative abundances of Alistipes and Rikenellaceae. UHPLC-MS/MS data suggested that SWT altered the composition of BAs in circulation as evidenced by increased unconjugated BAs like cholic acid and chenodeoxycholic acid but decreased conjugated BAs including taurocholic acid and taurodeoxycholic acid, compared to that in CCl₄ mice. Notably, SWT efficiently improved the imbalance of BA homeostasis in livers caused by CCl₄ via activating farnesoid X receptor (FXR)-fibroblast growth factor 15 enterohepatic and FXR-small heterodimer partner hepatic pathways.

Conclusion

SWT decreased inflammatory response, reconstructed gut microbiota-mediated BA homeostasis as well as activated FXR pathways, which eventually protected against CCl₄-induced fibrotic liver injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-021-00524-0.

Microbiota and viral hepatitis: State of the art of a complex matter

Changes in gut microbiota influence both the gut and liver, which are strictly connected by the so-called "gut-liver axis". The gut microbiota acts as a major determinant of this relationship in the onset and clinical course of liver diseases. According to the results of several studies, gut dysbiosis is linked to viral hepatitis, mainly hepatitis C virus and hepatitis B virus infection. Gut bacteria-derived metabolites and cellular components are key molecules that affect liver function and modulate the pathology of viral hepatitis. Recent studies showed that the gut microbiota produces various molecules, such as peptidoglycans, lipopolysaccharides, DNA, lipoteichoic acid, indole-derivatives, bile acids, and trimethylamine, which are translocated to the liver and interact with liver immune cells causing pathological effects. Therefore, the existence of crosstalk between the gut microbiota and the liver and its implications on host health and pathologic status are essential factors impacting the etiology and therapeutic approach. Concrete mechanisms behind the pathogenic role of gut-derived components on the pathogenesis of viral hepatitis remain unclear and not understood. In this review, we discuss the current findings of research on the bidirectional relationship of the components of gut microbiota and the progression of liver diseases and viral hepatitis and vice versa. Moreover, this paper highlights the current therapeutic and preventive strategies, such as fecal transplantation, used to restore the gut microbiota composition and so improve host health.

The Gut Microbiota-Derived Immune Response in Chronic Liver Disease

In chronic liver disease, the causative factor is important; however, recently, the intestinal microbiome has been associated with the progression of chronic liver disease and the occurrence of side effects. The immune system is affected by the metabolites of the microbiome, and diet is the primary regulator of the microbiota composition and function in the gut–liver axis. These metabolites can be used as therapeutic material, and postbiotics, in the future, can increase or decrease human immunity by modulating inflammation and immune reactions. Therefore, the excessive intake of nutrients and the lack of nutrition have important effects on immunity and inflammation. Evidence has been published indicating that microbiome-induced chronic inflammation and the consequent immune dysregulation affect the development of chronic liver disease. In this research paper, we discuss the overall trend of microbiome-derived substances related to immunity and the future research directions.

Causal Linkage Between Inflammatory Bowel Disease and Primary Sclerosing Cholangitis: A Two-Sample Mendelian Randomization Analysis

Background

Observational studies suggest an association between inflammatory bowel disease (IBD) [including ulcerative colitis (UC) and Crohn’s disease (CD)] and Primary sclerosing cholangitis (PSC), but the causal association between the two diseases remains unclear.

Methods

We used two-sample Mendelian randomization (MR) to estimate the causal association between IBD and PSC. We chose single nucleotide polymorphisms (SNPs) data for analysis, obtained from previous genome-wide association studies (GWASs). Pleiotropy, heterogeneity, and sensitivity analyses were performed for quality control.

Results

We found that the causal associations between IBD (both UC and CD) and PSC were significant (e.g., IBD and PSC, Robust adjusted profile score (RAPS) OR = 1.29, 95% CI 1.16∼1.44, p< 0.01; UC and PSC, RAPS OR = 1.40, 95% CI 1.23∼1.58, p< 0.01; CD and PSC, RAPS OR = 1.13, 95% CI 1.02∼1.26, p = 0.02). MR Egger, IVW, and ML tests found statistical heterogeneity between determined IV estimates. The leave-one-out analysis also indicated the sensitivity of the SNPs (e.g., IBD and PSC, MR-Egger Q = 644.30, p< 0.01; UC and PSC, MR-Egger Q = 378.30, p< 0.01; UC and PSC, MR-Egger Q = 538.50, p < 0.01).

Conclusion

MR analyses support the positive causal effect of IBD (including UC and CD) on PSC in a European population. We provide suggestions for preventing and treating the two diseases.

Monocytes as Potential Mediators of Pathogen-Induced T-Helper 17 Differentiation in Patients With Primary Sclerosing Cholangitis (PSC)

BACKGROUND AND AIMS

T cells from patients with primary sclerosing cholangitis (PSC) show a prominent interleukin (IL)-17 response upon stimulation with bacteria or fungi, yet the reasons for this dominant T-helper 17 (Th17) response in PSC are not clear. Here, we analyzed the potential role of monocytes in microbial recognition and in skewing the T-cell response toward Th17.

APPROACH AND RESULTS

Monocytes and T cells from blood and livers of PSC patients and controls were analyzed ex vivo and in vitro using transwell experiments with cholangiocytes. Cytokine production was measured using flow cytometry, enzyme-linked immunosorbent assay, RNA in situ hybridization, and quantitative real-time PCR. Genetic polymorphisms were obtained from ImmunoChip analysis. Following ex vivo stimulation with phorbol myristate acetate/ionomycin, PSC patients showed significantly increased numbers of IL-17A-producing peripheral blood CD4⁺ T cells compared to PBC patients and healthy controls, indicating increased Th17 differentiation in vivo. Upon stimulation with microbes, monocytes from PSC patients produced significantly more IL-1β and IL-6, cytokines known to drive Th17 cell differentiation. Moreover, microbe-activated monocytes induced the secretion of Th17 and monocyte-recruiting chemokines chemokine (C-C motif) ligand (CCL)-20 and CCL-2 in human primary cholangiocytes. In livers of patients with PSC cirrhosis, CD14^hiCD16^int and CD14^loCD16^hi monocytes/macrophages were increased compared to alcoholic cirrhosis, and monocytes were found to be located around bile ducts.

CONCLUSIONS

PSC patients show increased Th17 differentiation already in vivo. Microbe-stimulated monocytes drive Th17 differentiation in vitro and induce cholangiocytes to produce chemokines mediating recruitment of Th17 cells and more monocytes into portal tracts. Taken together, these results point to a pathogenic role of monocytes in patients with PSC.

Microbiome: Emerging Concepts in Patients with Chronic Liver Disease

The gut microbiome is an exciting new area of research in chronic liver disease. It has shown promise in expanding our understanding of these complicated disease processes and has opened up new treatment modalities. The aim of this review is to increase understanding of the microbiome and explain the collection and analysis process in the context of liver disease. It also looks at our current understanding of the role of the microbiome in the wide spectrum of chronic liver diseases and how it is being used in current therapies and treatments.

Targeting the Gut Microbiome as a Treatment for Primary Sclerosing Cholangitis: A Conceptional Framework

Primary sclerosing cholangitis (PSC) is a rare, immune-mediated, chronic cholestatic liver disease associated with a unique phenotype of inflammatory bowel disease that frequently manifests as pancolitis with right-sided predominance. Available data suggest a bidirectional interplay of the gut-liver axis with critical roles for the gastrointestinal microbiome and circulating bile acids (BAs) in the pathophysiology of PSC. BAs shape the gut microbiome, whereas gut microbes have the potential to alter BAs, and there are emerging data that alterations of BAs and the microbiome are not simply a consequence but the cause of PSC. Clustering of PSC in families may suggest that PSC occurs in genetically susceptible individuals. After exposure to an environmental trigger (e.g., microbial byproducts or BAs), an aberrant or exaggerated cholangiocyte-induced immune cascade occurs, ultimately leading to bile duct damage and progressive fibrosis. The pathophysiology can be conceptualized as a triad of (1) gut dysbiosis, (2) altered BA metabolism, and (3) immune-mediated biliary injury. Immune activation seems to be central to the disease process, but immunosuppression does not improve clinical outcomes or alter the natural history of PSC. Currently, orthoptic liver transplantation is the only established life-saving treatment, whereas antimicrobial therapy or fecal transplantation is an emerging therapeutic option for PSC. The beneficial effects of these microbiome-based therapies are likely mediated by a shift of the gut microbiome with favorable effects on BA metabolism. In the future, personalized approaches will allow to better target the interdependence between microbiome, immune function, and BA metabolism and potentially cure patients with PSC.

A story of liver and gut microbes: how does the intestinal flora affect liver disease? A review of the literature

Each individual is endowed with a unique gut microbiota (GM) footprint that mediates numerous host-related physiological functions, such as nutrient metabolism, maintenance of the structural integrity of the gut mucosal barrier, immunomodulation, and protection against microbial pathogens. Because of increased scientific interest in the GM, its central role in the pathophysiology of many intestinal and extraintestinal conditions has been recognized. Given the close relationship between the gastrointestinal tract and the liver, many pathological processes have been investigated in the light of a microbial-centered hypothesis of hepatic damage. In this review we introduce to neophytes the vast world of gut microbes, including prevalent bacterial distribution in healthy individuals, how the microbiota is commonly analyzed, and the current knowledge of the role of GM in liver disease pathophysiology. Also, we highlight the potentials and downsides of GM-based therapy.

Emerging therapies in primary sclerosing cholangitis: pathophysiological basis and clinical opportunities

Primary sclerosing cholangitis (PSC) is a progressive liver disease, histologically characterized by inflammation and fibrosis of the bile ducts, and clinically leading to multi-focal biliary strictures and with time cirrhosis and liver failure. Patients bear a significant risk of cholangiocarcinoma and colorectal cancer, and frequently have concomitant inflammatory bowel disease and autoimmune disease manifestations. To date, no medical therapy has proven significant impact on clinical outcomes and most patients ultimately need liver transplantation. Several treatment strategies have failed in the past and whilst prescription of ursodeoxycholic acid (UDCA) prevails, controversy regarding benefits remains. Lack of statistical power, slow and variable disease progression, lack of surrogate biomarkers for disease severity and other challenges in trial design serve as critical obstacles in the development of effective therapy. Advances in our understanding of PSC pathogenesis and biliary physiology over recent years has however led to a surge of clinical trials targeting various mechanistic compartments and currently raising hopes for imminent changes in patient management. Here, in light of pathophysiology, we outline and critically evaluate emerging treatment strategies in PSC, as tested in recent or ongoing phase II and III trials, stratified per a triad of targets of nuclear and membrane receptors regulating bile acid metabolism, immune modulators, and effects on the gut microbiome. Furthermore, we revisit the UDCA trials of the past and critically discuss relevant aspects of clinical trial design, including how the choice of endpoints, alkaline phosphatase in particular, may affect the future path to novel, effective PSC therapeutics.

Clinical Characteristics, Associated Malignancies and Management of Primary Sclerosing Cholangitis in Inflammatory Bowel Disease Patients: A Multicentre Retrospective Cohort Study

BACKGROUND AND AIMS

Primary sclerosing cholangitis [PSC] is usually associated with inflammatory bowel disease [IBD]. An increased risk of malignancies, mainly colorectal cancer [CRC] and cholangiocarcinoma [CCA], has been reported in PSC-IBD patients. Our aim was to determine the clinical characteristics and management of PSC in IBD patients, and the factors associated with malignancies.

METHODS

PSC-IBD patients were identified from the Spanish ENEIDA registry of GETECCU. Additional data were collected using the AEG-REDCap electronic data capture tool.

RESULTS

In total, 277 PSC-IBD patients were included, with an incidence rate of 61 PSC cases per 100 000 IBD patient-years, 69.7% men, 67.5% ulcerative colitis and mean age at PSC diagnosis of 40 ± 16 years. Most patients [85.2%] were treated with ursodeoxycholic acid. Liver transplantation was required in 35 patients [12.6%] after 79 months (interquartile range [IQR] 50-139). It was more common in intra- and extrahepatic PSC compared with small-duct PSC (16.3% vs 3.3%; odds ratio [OR] 5.7: 95% confidence interval [CI] = 1.7-19.3). The incidence rate of CRC since PSC diagnosis was 3.3 cases per 1000 patient-years [95% CI = 1.9-5.6]. Having symptoms of PSC at PSC diagnosis was the only factor related to an increased risk of CRC after IBD diagnosis [hazard ratio= 3.3: 95% CI = 1.1-9.9]. CCA was detected in seven patients [2.5%] with intra- and extrahepatic PSC, with median age of 42 years [IQR 39-53], and presented a lower life expectancy compared with patients without CCA and patients with or without CRC.

CONCLUSIONS

PSC-IBD patients with symptoms of PSC at PSC diagnosis have an increased risk of CRC. CCA was only diagnosed in patients with intra- and extrahepatic PSC and was associated with poor survival.

Intestinal dysbiosis augments liver disease progression via NLRP3 in a murine model of primary sclerosing cholangitis

OBJECTIVE

There is a striking association between human cholestatic liver disease (CLD) and inflammatory bowel disease. However, the functional implications for intestinal microbiota and inflammasome-mediated innate immune response in CLD remain elusive. Here we investigated the functional role of gut-liver crosstalk for CLD in the murine Mdr2 knockout (Mdr2-/-) model resembling human primary sclerosing cholangitis (PSC).

DESIGN

Male Mdr2-/-, Mdr2-/- crossed with hepatocyte-specific deletion of caspase-8 (Mdr2-/- /Casp8∆hepa) and wild-type (WT) control mice were housed for 8 or 52 weeks, respectively, to characterise the impact of Mdr2 deletion on liver and gut including bile acid and microbiota profiling. To block caspase activation, a pan-caspase inhibitor (IDN-7314) was administered. Finally, the functional role of Mdr2-/- -associated intestinal dysbiosis was studied by microbiota transfer experiments.

RESULTS

Mdr2-/- mice displayed an unfavourable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut-liver axis. Intestinal dysbiosis in Mdr2-/- mice prompted intestinal barrier dysfunction and increased bacterial translocation amplifying the hepatic NLRP3-mediated innate immune response. Transfer of Mdr2-/- microbiota into healthy WT control mice induced significant liver injury in recipient mice, highlighting the causal role of intestinal dysbiosis for disease progression. Strikingly, IDN-7314 dampened inflammasome activation, ameliorated liver injury, reversed serum bile acid profile and cholestasis-associated microbiota signature.

CONCLUSIONS

MDR2-associated cholestasis triggers intestinal dysbiosis. In turn, translocation of endotoxin into the portal vein and subsequent NLRP3 inflammasome activation contribute to higher liver injury. This process does not essentially depend on caspase-8 in hepatocytes, but can be blocked by IDN-7314.

The role of the gut microbiome in chronic liver disease: the clinical evidence revised

Recent research has suggested a role for the intestinal microbiota in the pathogenesis and potential treatment of a wide range of liver diseases. The intestinal microbiota and bacterial products may contribute to the development of liver diseases through multiple mechanisms including increased intestinal permeability, chronic systemic inflammation, production of short-chain fatty acids and changes in metabolism. This suggests a potential role for pre-, pro- and synbiotic products in the prevention or treatment of some liver diseases. In addition, there is emerging evidence on the effects of faecal microbial transplant. Herein, we discuss the relationship between the intestinal microbiota and liver diseases, as well as reviewing intestinal microbiota-based treatment options that are currently being investigated.

Emerging novel treatments for autoimmune liver diseases

The etiology of autoimmune liver diseases, such as autoimmune hepatitis (AIH), primary biliary cholangitis (PBC), and primary sclerosing cholangitis (PSC), still remains largely unknown and no therapeutic agents that are able to "cure" these diseases have been developed. Although corticosteroids for AIH and ursodeoxycholic acid for PBC have been shown to significantly improve liver transplantation (LT)-free survival and are recommended as first-line drugs, treatment strategies for patients who show incomplete response to these drugs have not yet been fully established. No drug is significantly associated with long LT-free survival in PSC patients. Nevertheless, with progress in genetics, immunology, and cellular biology, several new compounds or antibodies are expected to have an effect on autoimmune liver diseases and several drugs are under consideration for clinical use. Although most clinical trials have been carried out in the USA or Europe, some are, or will be, undertaken in Japan in the future. In this review, the current standard-of-care of autoimmune liver diseases will be summarized, together with emerging novel treatments relevant to clinical practice in Japan.

Metabolomic Profiling of Portal Blood and Bile Reveals Metabolic Signatures of Primary Sclerosing Cholangitis

Primary sclerosing cholangitis (PSC) is a pathogenically complex, chronic, fibroinflammatory disorder of the bile ducts without known etiology or effective pharmacotherapy. Emerging in vitro and in vivo evidence support fundamental pathophysiologic mechanisms in PSC centered on enterohepatic circulation. To date, no studies have specifically interrogated the chemical footprint of enterohepatic circulation in PSC. Herein, we evaluated the metabolome and lipidome of portal venous blood and bile obtained at the time of liver transplantation in patients with PSC (n = 7) as compared to individuals with noncholestatic, end-stage liver disease (viral, metabolic, etc. (disease control, DC, n = 19)) and to nondisease controls (NC, living donors, n = 12). Global metabolomic and lipidomic profiling was performed on serum derived from portal venous blood (portal serum) and bile using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and differential mobility spectroscopy-mass spectroscopy (DMS-MS; complex lipid platform). The Mann⁻Whitney U test was used to identify metabolites that significantly differed between groups. Principal-component analysis (PCA) showed significant separation of both PSC and DC from NC for both portal serum and bile. Metabolite set enrichment analysis of portal serum and bile demonstrated that the liver-disease cohorts (PSC and DC) exhibited similar enrichment in several metabolite categories compared to NC. Interestingly, the bile in PSC was uniquely enriched for dipeptide and polyamine metabolites. Finally, analysis of patient-matched portal serum and biliary metabolome revealed that these biological fluids were more homogeneous in PSC than in DC or NC, suggesting aberrant bile formation and enterohepatic circulation. In summary, PSC and DC patients exhibited alterations in several metabolites in portal serum and bile, while PSC patients exhibited a unique bile metabolome. These specific alterations in PSC are amenable to hypothesis testing and, potentially, therapeutic pharmacologic manipulation.

The IBD and PSC Phenotypes of PSC-IBD

PURPOSE OF REVIEW

To review the characteristics of IBD and PSC that occur in association, as well as their reciprocal influences on disease evolution, in adult and pediatric populations.

RECENT FINDINGS

IBD co-existing with PSC is genetically and clinically distinct from IBD alone. It is frequently characterized by pancolitis, rectal sparing, and possibly backwash ileitis, as well as a threefold increased risk of colorectal dysplasia. Adults and children with colitis and PSC appear to be at increased risk of active endoscopic and histologic disease in the absence of symptoms compared to individuals without PSC. PSC occurring with Crohn's disease has been observed to be less severe than PSC co-existing with ulcerative colitis, independent of its association with small duct disease. Recent studies suggest that colectomy is associated with a decreased risk of recurrent PSC after liver transplantation, challenging the traditional teaching that PSC and IBD evolve independently. While much about the gut-liver axis in PSC-IBD remains poorly understood, the IBD associated with PSC has a unique phenotype, of which subclinical inflammation is an important component. Additional research is needed to characterize further the potentially protective role of colectomy against recurrent PSC post-liver transplantation and to investigate the influence of IBD control and/or colectomy on PSC progression.

Neutralization of IL-15 abrogates experimental immune-mediated cholangitis in diet-induced obese mice

Obesity is a global epidemic affecting chronic inflammatory diseases. Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease that can occur as an extraintestinal manifestation of inflammatory bowel disease (IBD). Previously we reported that patients with PSC who are obese have a higher risk of advanced liver disease. Currently it is unknown how obesity accelerates or worsens PSC. We evaluated the progression of PSC in an antigen-driven cholangitis mouse model of diet-induced obesity. Obesity was induced in our murine model of immune-mediated cholangitis (OVAbil). OVAbil mice were fed standard chow or high-fat/sucrose diet for twelve weeks followed by induction of biliary inflammation by OVA-specific T cell transfer. Histopathological damage in portal tracts was scored and serum collected. Neutralizing antibodies against IL-15 were administered daily until study termination. Obese mice developed exacerbated liver inflammation and damage. Immune cell phenotyping in liver revealed greater numbers of neutrophils and CD8+ T cells in obese mice. Higher levels of cytokines and chemokines were found in obese mice with cholangitis. Immuno-neutralizing antibodies against IL-15 greatly attenuated cholangitis in obese mice. Obesity exacerbated experimental PSC in part by overproduction of IL-15. Timely targeting of IL-15 may slow the progression of PSC.

Primary sclerosing cholangitis - a comprehensive review

Primary sclerosing cholangitis (PSC) is a rare disorder characterised by multi-focal bile duct strictures and progressive liver disease. Inflammatory bowel disease is usually present and there is a high risk of cholangiocarcinoma and colorectal cancer. Most patients ultimately require liver transplantation, after which disease recurrence may occur. With limited therapeutic options and a lack of proven surveillance strategies, patients currently have significant unmet needs. In the present seminar, we provide a comprehensive review of the status of the field. We emphasise developments related to patient stratification and disease behaviour, and provide an overview of management options from a practical, patient-centered perspective. We survey advances made in the understanding of PSC pathogenesis and summarise the ongoing efforts to develop an effective therapy based on these insights.

Primary sclerosing cholangitis and the management of uncertainty and complexity

Primary sclerosing cholangitis (PSC) is a rare chronic autoimmune disease with no effective therapy and a large unmet need for new treatments. Patients require significant healthcare resources over their lifetime with high rates of hospital admission, malignancy, liver transplantation and death. As a rare disease, expertise in management can be limited to large referral liver transplant programmes, and even then there is frequently variation in practice. In this case-based review, we aim to discuss common clinical dilemmas encountered by clinicians managing patients with PSC and address related competencies in the 2010 Gastroenterology Curriculum.

Bile acids and intestinal microbiota in autoimmune cholestatic liver diseases

Autoimmune cholestatic liver diseases, including primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), are manifested as an impairment of normal bile flow and excessive accumulation of potentially toxic bile acids. Endogenous bile acids are involved in the pathogenesis and progression of cholestasis. Consequently, chronic cholestasis affects the expression of bile acid transporters and nuclear receptors, and results in liver injury. Several lines of evidence suggest that intestinal microbiota plays an important role in the etiopathogenesis of cholestatic liver diseases by regulating metabolism and immune responses. However, progression of the disease may also affect the composition of gut microbiota, which in turn exacerbates the progression of cholestasis. In addition, the interaction between intestinal microbiota and bile acids is not unidirectional. Bile acids can shape the gut microbiota community, and in turn, intestinal microbes are able to alter bile acid pool. In general, gut microbiota actively communicates with bile acids, and together play an important role in the pathogenesis of PBC and PSC. Targeting the link between bile acids and intestinal microbiota offers exciting new perspectives for the treatment of those cholestatic liver diseases. This review highlights current understanding of the interactions between bile acids and intestinal microbiota and their roles in autoimmune cholestatic liver diseases. Further, we postulate a bile acids-intestinal microbiota-cholestasis triangle in the pathogenesis of autoimmune cholestatic liver diseases and potential therapeutic strategies by targeting this triangle.

Update on pharmacotherapies for cholestatic liver disease

Cholestatic liver diseases are conditions with impaired bile formation and/or flow due to genetic, immunologic, environmental, or other causes. Unless successfully treated, this can lead to chronic liver injury and end-stage liver disease. Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) embody the most prominent adult cholestatic liver diseases with regard to incidence, morbidity, and mortality. A considerable proportion of patients with PBC and PSC experience progressive liver disease and ultimately liver-related death due to a paucity of effective pharmacotherapy; however, novel pharmacologic developments offer substantial promise in this regard. Here, we provide a brief review and update on current and emerging pharmacotherapies for PBC and PSC. (Hepatology Communications 2017;1:7-17).