Primary sclerosing cholangitis (PSC) is a severe liver disease of unknown etiology leading to fibrotic destruction of the bile ducts and ultimately to the need for liver transplantation(1-3). We compared 3,789 PSC cases of European ancestry to 25,079 population controls across 130,422 SNPs genotyped using the Immunochip(4). We identified 12 genome-wide significant associations outside the human leukocyte antigen (HLA) complex, 9 of which were new, increasing the number of known PSC risk loci to 16. Despite comorbidity with inflammatory bowel disease (IBD) in 72% of the cases, 6 of the 12 loci showed significantly stronger association with PSC than with IBD, suggesting overlapping yet distinct genetic architectures for these two diseases. We incorporated association statistics from 7 diseases clinically occurring with PSC in the analysis and found suggestive evidence for 33 additional pleiotropic PSC risk loci. Together with network analyses, these findings add to the genetic risk map of PSC and expand on the relationship between PSC and other immune-mediated diseases

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Background The relationship between intestinal epithelial integrity and the development of intestinal disease is of increasing interest. A reduction in mucosal integrity has been associated with ulcerative colitis, Crohn’s disease and potentially could have links with colorectal cancer development. The Ussing chamber system can be utilised as a valuable tool for measuring gut integrity. Here we describe step-by-step methodology required to measure intestinal permeability of both mouse and human colonic tissue samples ex vivo, using the latest equipment and software. This system can be modified to accommodate other tissues. Methods An Ussing chamber was constructed and adapted to support both mouse and human tissue to measure intestinal permeability, using paracellular flux and electrical measurements. Two mouse models of intestinal inflammation (dextran sodium sulphate treatment and T regulatory cell depletion using C57BL/6-FoxP3 DTR mice) were used to validate the system along with human colonic biopsy samples. Results Distinct regional differences in permeability were consistently identified within mouse and healthy human colon. In particular, mice showed increased permeability in the mid colonic region. In humans the left colon is more permeable than the right. Furthermore, inflammatory conditions induced chemically or due to autoimmunity reduced intestinal integrity, validating the use of the system. Conclusions The Ussing chamber has been used for many years to measure barrier function. However, a clear and informative methods paper describing the setup of modern equipment and step-by-step procedure to measure mouse and human intestinal permeability isn’t available. The Ussing chamber system methodology we describe provides such detail to guide investigation of gut integrity. Electronic supplementary material The online version of this article (10.1186/s12876-019-1002-4) contains supplementary material, which is available to authorized users.

We sought to identify factors that are predictive of liver transplantation or death in patients with primary sclerosing cholangitis (PSC), and to develop and validate a contemporaneous risk score for use in a real‐world clinical setting. Analyzing data from 1,001 patients recruited to the UK‐PSC research cohort, we evaluated clinical variables for their association with 2‐year and 10‐year outcome through Cox‐proportional hazards and C‐statistic analyses. We generated risk scores for short‐term and long‐term outcome prediction, validating their use in two independent cohorts totaling 451 patients. Thirty‐six percent of the derivation cohort were transplanted or died over a cumulative follow‐up of 7,904 years. Serum alkaline phosphatase of at least 2.4 × upper limit of normal at 1 year after diagnosis was predictive of 10‐year outcome (hazard ratio [HR] = 3.05; C = 0.63; median transplant‐free survival 63 versus 108 months; P < 0.0001), as was the presence of extrahepatic biliary disease (HR = 1.45; P = 0.01). We developed two risk scoring systems based on age, values of bilirubin, alkaline phosphatase, albumin, platelets, presence of extrahepatic biliary disease, and variceal hemorrhage, which predicted 2‐year and 10‐year outcomes with good discrimination (C statistic = 0.81 and 0.80, respectively). Both UK‐PSC risk scores were well‐validated in our external cohort and outperformed the Mayo Clinic and aspartate aminotransferase‐to‐platelet ratio index (APRI) scores (C statistic = 0.75 and 0.63, respectively). Although heterozygosity for the previously validated human leukocyte antigen (HLA)‐DR*03:01 risk allele predicted increased risk of adverse outcome (HR = 1.33; P = 0.001), its addition did not improve the predictive accuracy of the UK‐PSC risk scores. Conclusion: Our analyses, based on a detailed clinical evaluation of a large representative cohort of participants with PSC, furthers our understanding of clinical risk markers and reports the development and validation of a real‐world scoring system to identify those patients most likely to die or require liver transplantation.

Objective Primary sclerosing cholangitis (PSC) is a genetically complex, inflammatory bile duct disease of largely unknown aetiology often leading to liver transplantation or death. Little is known about the genetic contribution to the severity and progression of PSC. The aim of this study is to identify genetic variants associated with PSC disease progression and development of complications. Design We collected standardised PSC subphenotypes in a large cohort of 3402 patients with PSC. After quality control, we combined 130 422 single nucleotide polymorphisms of all patients—obtained using the Illumina immunochip—with their disease subphenotypes. Using logistic regression and Cox proportional hazards models, we identified genetic variants associated with binary and time-to-event PSC subphenotypes. Results We identified genetic variant rs853974 to be associated with liver transplant-free survival (p=6.07×10−9). Kaplan-Meier survival analysis showed a 50.9% (95% CI 41.5% to 59.5%) transplant-free survival for homozygous AA allele carriers of rs853974 compared with 72.8% (95% CI 69.6% to 75.7%) for GG carriers at 10 years after PSC diagnosis. For the candidate gene in the region, RSPO3, we demonstrated expression in key liver-resident effector cells, such as human and murine cholangiocytes and human hepatic stellate cells. Conclusion We present a large international PSC cohort, and report genetic loci associated with PSC disease progression. For liver transplant-free survival, we identified a genome-wide significant signal and demonstrated expression of the candidate gene RSPO3 in key liver-resident effector cells. This warrants further assessments of the role of this potential key PSC modifier gene.