Ali, Ahmad H.

ABSTRACT Background and Aims Cellular senescence is a hallmark of several liver diseases, including primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC). Senescent cholangiocytes exhibit a senescence‐associated secretory phenotype (SASP), characterized by profibroinflammatory mediator release. Current cost‐effective biomarkers predicting disease progression, particularly for PSC, are limited and often lack mechanistic relevance. We sought to define a plasma biomarker signature for PSC and PBC. Methods Plasma from early‐ and late‐stage PSC and PBC, alcoholic liver disease (ALD), inflammatory bowel disease (IBD) patients, and healthy controls was analyzed. Seventy‐one analytes were quantified using Luminex Multiplex Immunoassay or enzyme‐linked immunosorbent assay (ELISA). Principal component analysis (PCA) identified key patterns. Findings from the PSC cohort were then applied to additional cohorts. Results Second principal component (PC2) (17 analytes, 17.1% variability) best separated PSC from controls. ANOVA showed significant differences in PC2 between early PSC vs. controls ( p = 0.0001), late PSC vs. controls ( p < 0.0001), and early vs. late PSC ( p < 0.0001). PC2 analytes also distinguished early PBC vs. controls ( p < 0.0332), late PBC ( p < 0.0001), and ALD ( p < 0.0001), and early vs. late PBC ( p < 0.0001), but not IBD vs. controls ( p = 0.119). Logistic regression using PC2 demonstrated strong discrimination of early‐ and late‐stage PSC (AUC = 0.86) and control vs. early‐stage PSC (AUC = 0.83). Conclusion This is the first study to define a plasma SASP biomarker signature associated with cholestatic liver disease. These analytes track disease stage and represent both mechanistic indicators and potential clinical trial endpoints.

Abstract Primary sclerosing cholangitis (PSC) is a complex bile duct disorder. Its etiology is incompletely understood, but environmental chemicals likely contribute to risk. Patients with PSC have an altered bile metabolome, which may be influenced by environmental chemicals. This novel study utilized state-of-the-art high-resolution mass spectrometry (HRMS) with bile samples to provide the first characterization of environmental chemicals and metabolomics (collectively, the exposome) in PSC patients located in the United States of America (USA) (n = 24) and Norway (n = 30). First, environmental chemical- and metabolome-wide association studies were conducted to assess geographic-based similarities and differences in the bile of PSC patients. Nine environmental chemicals (false discovery rate, FDR &lt; 0.20) and 3143 metabolic features (FDR &lt; 0.05) differed by site. Next, pathway analysis was performed to identify metabolomic pathways that were similarly and differentially enriched by the site. Fifteen pathways were differentially enriched (P &lt; .05) in the categories of amino acid, glycan, carbohydrate, energy, and vitamin/cofactor metabolism. Finally, chemicals and pathways were integrated to derive exposure–effect correlation networks by site. These networks demonstrate the shared and differential chemical–metabolome associations by site and highlight important pathways that are likely relevant to PSC. The USA patients demonstrated higher environmental chemical bile content and increased associations between chemicals and metabolic pathways than those in Norway. Polychlorinated biphenyl (PCB)-118 and PCB-101 were identified as chemicals of interest for additional investigation in PSC given broad associations with metabolomic pathways in both the USA and Norway patients. Associated pathways include glycan degradation pathways, which play a key role in microbiome regulation and thus may be implicated in PSC pathophysiology.

Abstract Background: Primary sclerosing cholangitis (PSC) is a rare, chronic cholestatic liver disease that often progresses to end-stage liver disease and/or the development of hepatobiliary neoplasia. Lack of prognostic tools and treatment options for PSC is driven in part by our poor understanding of its pathogenesis, which is thought to be complex, the interaction of genetic variants, environmental influences and biological response throughout the course of disease. The PSC Scientific Community Resource (PSC-SCR) seeks to overcome previous shortcomings by facilitating novel research in PSC with the ultimate goals of individualizing patient care and improving patient outcomes.Methods: PSC patients who receive their health care at Mayo Clinic or a collaborating site are identified by chart review and invited in person or by mail to participate. Non-Mayo patients are offered enrollment if they provide sufficient access to their medical records to evaluate inclusion/exclusion criteria. Controls without liver disease are identified with assistance of the Mayo Clinic Biobank. Participant consent is obtained at the beginning of the recruitment process by mail-in, electronic or face-to-face protocols. Clinical data is extracted from the medical record by qualified physicians and entered in a custom designed database. Participants fill out a custom-designed, comprehensive questionnaire, which collects scientifically relevant demographic and clinical information. Biospecimens are collected using mail-in kitsthar are returned via overnight carrier service and processed by the biospecimen accessioning and processing facility at Mayo Clinic, which coordinates sample transfers and provides required sample preparation services.The resource is currently being utilized to perform omics-scale projects investigating the exposome, metabolome, methylome, immunome and microbiome in PSC. Datasets and residual biospecimens will be shared with researchers proposing scientifically sound PSC-focused research with approval of the appropriate review boards.Discussion:Patient-based studies leveraging the latest technologies for targeted and wide-scale interrogation of multiple omics layers offer promise to accelerate PSC research through discovery of unappreciated aspects of disease pathogenesis. However, the rarity of PSC severely limits such studies. Here we describe our effort to overcome this limitation, the PSC-SCR, a repository of patient biospecimens coupled with clinical and omics data for use by the broader PSC research community.

Abstract Background: Quantification of circulating organ-specific cell-free DNA (cfDNA) provides a sensitive measure of ongoing cell death that could benefit evaluation of the cholestatic liver diseases primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC), which lack reliable non-invasive biomarkers. Our goal in this pilot study was to determine whether liver-specific cfDNA levels are increased in PBC and PSC patients relative to controls and in advanced versus early disease, to evaluate their potential as novel disease biomarkers.Methods: Peripheral blood derived bisulfite-treated DNA was PCR amplified from patients with PBC (n=48), PSC (n=48) and controls (n=96) to evaluate methylation status at 16 CpG sites reported to be specifically unmethylated in liver tissue near the genes IGF2R, ITIH4 and VTN. Amplicons were used to prepare paired end libraries which were sequenced on a MiSeq sequencer. Trimmed reads were aligned and used to determine unmethylation ratios and to calculate concentration of liver-specific cfDNA. Comparisons between groups were performed using the two-tailed Mann-Whitney Test and relationships between variables were evaluated using Pearson’s Correlation. Results: Levels of liver-specific cfDNA, as measured at the 3 genetic loci, were increased in PBC and PSC patients relative to controls and in late-stage relative to early-stage patients. As well, cfDNA levels were correlated with levels of alkaline phosphatase, a commonly used biochemical test to evaluate disease severity in liver disease, in patients, but not in controls. Conclusions: cfDNA offers promise as a non-invasive liquid-biopsy to evaluate liver-specific cell-death in patients with cholestatic liver diseases.

Background and Aims Altered bile acid (BA) homeostasis is an intrinsic facet of cholestatic liver diseases, but clinical usefulness of plasma BA assessment in primary sclerosing cholangitis (PSC) remains understudied. We performed BA profiling in a large retrospective cohort of patients with PSC and matched healthy controls, hypothesizing that plasma BA profiles vary among patients and have clinical utility. Approach and Results Plasma BA profiling was performed in the Clinical Biochemical Genetics Laboratory at Mayo Clinic using a mass spectrometry based assay. Cox proportional hazard (univariate) and gradient boosting machines (multivariable) models were used to evaluate whether BA variables predict 5‐year risk of hepatic decompensation (HD; defined as ascites, variceal hemorrhage, or encephalopathy). There were 400 patients with PSC and 302 controls in the derivation cohort (Mayo Clinic) and 108 patients with PSC in the validation cohort (Norwegian PSC Research Center). Patients with PSC had increased BA levels, conjugated fraction, and primary‐to‐secondary BA ratios relative to controls. Ursodeoxycholic acid (UDCA) increased total plasma BA level while lowering cholic acid and chenodeoxycholic acid concentrations. Patients without inflammatory bowel disease (IBD) had primary‐to‐secondary BA ratios between those of controls and patients with ulcerative colitis. HD risk was associated with increased concentration and conjugated fraction of many BA, whereas higher G:T conjugation ratios were protective. The machine‐learning model, PSC‐BA profile score (concordance statistic [C‐statistic], 0.95), predicted HD better than individual measures, including alkaline phosphatase, and performed well in validation (C‐statistic, 0.86). Conclusions Patients with PSC demonstrated alterations of plasma BA consistent with known mechanisms of cholestasis, UDCA treatment, and IBD. Notably, BA profiles predicted future HD, establishing the clinical potential of BA profiling, which may be suited for use in clinical trials.

INTRODUCTION: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) has been recognized worldwide. However, its natural history and long-term outcomes are not well known. METHODS: In this retrospective, single center, cohort study, we identified patients who received a diagnosis of IgG4-SC at Mayo Clinic Rochester from 1999 to 2018. The diagnosis of IgG4-SC was rigorously ascertained by review of medical records and using the validated HISORt criteria. Comprehensive clinical data was extracted from patients' charts. Long-term outcomes of interest included cirrhosis, cholangiocarcinoma (CCA), and death. To compare outcomes, a random sample of PSC patients was selected in a 1:1 ratio matched for age of diagnosis and gender. Survival analyses were performed for comparisons using the Kaplan-Meier method, and log-rank test, and the cumulative incidence of cirrhosis and CCA was assessed using the competing risks regression method. RESULTS: A total of 61 patients were diagnosed with IgG4-SC during the study period. The median age of diagnosis was 66 years (IQR: 56–71 years), 85% were male, and the median follow-up was 6.1 years (IQR: 3.2–8.3 years). The pancreas was the most commonly involved extra-biliary organ (93%). Fifty-five patients received prednisone of whom 96% experienced complete or partial remission. Sixteen patients received rituximab as maintenance therapy, of whom 88% maintained remission. Three patients (5%) developed cirrhosis, and 2 patients (3%) developed CCA. Nine patients (15%) died; 2 due to cirrhosis, 2 due to CCA, 1 due to pancreatic cancer, and 4 due to non-hepatobiliary causes. Patients with IgG4-SC had significantly lower 5- and 10-year cumulative incidence of developing cirrhosis (5 y: 4% vs. 34%; 10 y: 6% vs. 43%; P < 0.001) and CCA (5 y: 3% vs. 17%; 10 y: 4% vs. 22%; P = 0.012) compared with PSC patients. Two patients in the PSC group underwent liver transplantation, while none in the IgG4-SC group. Overall 5- and 10-year survival was greater in the IgG4-SC cohort (5 y: 92% vs. 70%; 10 y: 77% vs. 57%; P = 0.02). CONCLUSION: Patients with IgG4-SC, the majority of whom received treatment, have a small potential risk of long-term hepatobiliary complications. Their risk of cirrhosis, CCA and death, was lower than in patients with PSC. The better outcome in the IgG4-SC group is likely due to the benefit of treatment. Surveillance in this population needs further assessment, especially the subset that does receive or respond to treatment.