Association Between HLA Haplotypes and Increased Serum Levels of IgG4 in Patients With Primary Sclerosing Cholangitis

Immunogenomics of cholangiocarcinoma

The development of cholangiocarcinoma spans years, if not decades, during which the immune system becomes corrupted and permissive to primary tumor development and metastasis. This involves subversion of local immunity at tumor sites, as well as systemic immunity and the wider host response. While immune dysfunction is a hallmark of all cholangiocarcinoma, the specific steps of the cancer-immunity cycle that are perturbed differ between patients. Heterogeneous immune functionality impacts the evolutionary development, pathobiological behavior, and therapeutic response of these tumors. Integrative genomic analyses of thousands of primary tumors have supported a biological rationale for immune-based stratification of patients, encompassing immune cell composition and functionality. However, discerning immune alterations responsible for promoting tumor initiation, maintenance, and progression from those present as bystander events remains challenging. Functionally uncoupling the tumor-promoting or tumor-suppressing roles of immune profiles will be critical for identifying new immunomodulatory treatment strategies and associated biomarkers for patient stratification. This review will discuss the immunogenomics of cholangiocarcinoma, including the impact of genomic alterations on immune functionality, subversion of the cancer-immunity cycle, as well as clinical implications for existing and novel treatment strategies.

Risk stratification in primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a chronic liver disorder commonly affecting young patients and associated with uncertain prognosis and elevated risk of end-stage liver disease and hepatobiliary cancer. Rate of progression in PSC is heterogeneous and accurately predicting the disease course is of paramount importance to clinical practice and interventional trial design. So far, efforts have brought to the development of models looking at short-to-middle-term outcome using composite models including clinical, laboratory, radiological and histological parameters with limited performance. In the era of whole genome sequencing and digital innovation, the time is ripe for the development of stratified medicine in PSC. Efforts should be directed toward developing well-phenotyped cohorts of patients with longitudinal follow-up across sustained periods of time, application of novel image-processing technology, and biomarker discovery using multiomics platforms.

Comparison of the long-term outcomes between proximal and distal IgG4-related sclerosing cholangitis: A multicenter cohort study

BACKGROUND AND AIMS

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is considered a biliary manifestation of IgG4-related diseases. However, there has been a controversy on the clinical outcomes according to the location of the involved bile duct. We therefore compared the clinical outcomes and long-term prognosis of IgG4-SC with proximal bile duct involvement (proximal IgG4-SC) and IgG4-SC with distal bile duct involvement (distal IgG4-SC).

METHODS

We reviewed the data of patients with IgG4-SC that were prospectively collected at 10 tertiary centers between March 2002 and October 2020. Clinical manifestations, outcomes, association with autoimmune pancreatitis (AIP), steroid-responsiveness, and relapse of IgG4-SC were evaluated.

RESULTS

A total of 148 patients (proximal IgG4-SC, n = 59; distal IgG4-SC, n = 89) were analyzed. The median age was 65 years (IQR, 56.25-71), and 86% were male. The two groups were similar in terms of jaundice at initial presentation (51% vs 65%; P = 0.082) and presence of elevated serum IgG4 (66% vs 70%; P = 0.649). The two groups showed significant differences in terms of steroid-responsiveness (91% vs 100%; P = 0.008), association with AIP (75% vs 99%; P = 0.001), and occurrence of liver cirrhosis (9% vs 1%; P = 0.034). During a median follow-up of 64 months (IQR, 21.9-84.7), the cumulative relapse-free survival was significantly different between the two groups (67% vs 79% at 5 years; P = 0.035).

CONCLUSIONS

Relapse of IgG4-SC frequently occurred during follow-up. Proximal IgG4-SC and distal IgG4-SC had different long-term outcomes in terms of steroid-responsiveness, occurrence of liver cirrhosis, and recurrence. It may be advantageous to determine the therapeutic and follow-up strategies according to the location of bile duct involvement.

Gene Set Enrichment Analysis Detected Immune Cell-Related Pathways Associated with Primary Sclerosing Cholangitis

Aim

To explore various immune cell-related causal pathways for primary sclerosing cholangitis (PSC).

Methods

Immune cell-related pathway association study was conducted via integrative analysis of PSC GWAS summary and five immune cell-related eQTL datasets. The GWAS summary data of PSC was driven from 4,796 PSC cases and 19,955 healthy controls. The eQTL datasets of CD4+ T cells, CD8+ T cells, B cells, natural killer cells (NK), monocytes, and peripheral blood cells (PB) were collected from recently eQTL study. The PSC GWAS summary dataset was first aligned with eQTL datasets of six blood cells to obtain the GWAS summary data at overlapped eQTL loci, separately. For each type of cell, the obtained PSC GWAS summary dataset of eQTLs was subjected to pathway enrichment analysis. 853 biological pathways from Kyoto Encyclopedia of Genes and Genomes, BioCarta, and Reactome pathway databases were analyzed.

Results

We identified 36 pathways for B cells, 33 pathways for CD4+ T cells, 28 pathways for CD8+ T cells, 33 pathways for monocytes (MN), 35 pathways for NK cells, and 33 for PB cells (all empirical P values <5.0 × 10⁻⁵). Comparing the pathway analysis results detected 25 pathways shared by five immune cells, such as KEGG_CELL_ADHESION_MOLECULES_CAMS (P value <5.0 × 10⁻⁵) and REACTOME_MHC_CLASS_II_ANTIGEN_ PRESENTATION (P value <5.0 × 10⁻⁵). Several cell-specific pathways were also identified, including BIOCARTA_INFLAM_PATHWAY (P value <5 × 10⁻⁵) for B cell.

Conclusion

Our study holds potential to identify novel candidate causal pathways and provides clues for revealing the complex genetic mechanism of PSC.

A systematic review and meta-analysis of HLA class II associations in patients with IgG4 autoimmunity

Autoimmune diseases caused by pathogenic IgG4 subclass autoantibodies (IgG4-AID) include diseases like MuSK myasthenia gravis, pemphigus vulgaris or thrombotic thrombocytopenic purpura. Their etiology is still unknown. Polymorphisms in the human leukocyte antigen (HLA) gene locus, particularly in HLA-DRB1, are known genetic susceptibility factors for autoimmune diseases. We hypothesized a similar role for HLA polymorphisms in IgG4-AID and conducted a systematic review and meta-analysis with case-control studies on IgG4-AID based on MOOSE/ HuGENet guidelines. Genotype (G) and allele (A) frequencies of HLA-DQB1*05 (G: OR 3.8; 95% CI 2.44-5.9; p < 0.00001; A: OR 2.54; 95% CI 1.82-3.55; p < 0.00001) and HLA-DRB1*14 (G: OR 4.31; 95% CI 2.82-6.59; p < 0.00001; A: OR 4.78; 95% CI 3.52-6.49; p < 0.00001) and the HLA-DRB1*14-DQB1*05 haplotype (OR 6.3; 95% CI 3.28-12.09; p < 0.00001/OR 4.98; 95% CI 3.8-6.53; p < 0.00001) were increased while HLA-DRB1*13 (G: OR 0.48; 95% CI 0.34-0.68; p < 0.0001; A: OR 0.46; 95% CI 0.34-0.62; p < 0.00001) was decreased in IgG4-AID patients. In conclusion, the HLA-DQB1*05, HLA-DRB1*14 alleles and the HLA-DQB1*05-DRB1*14 haplotype could be genetic risk factors that predispose for the production of pathogenic IgG4 autoantibodies and the HLA-DRB1*13 allele may protect from IgG4 autoimmunity.

Serum IgG4 cut-off of 70 mg/dL is associated with a shorter time to cirrhosis decompensation and liver transplantation in primary sclerosing cholangitis patients

BACKGROUND

Primary sclerosing cholangitis (PSC) is an immune-mediated biliary disorder of unknown etiology with no effective treatment. The purpose of this study was to better prognosticate the development of cirrhosis, decompensation, and requirement for liver transplantation (LT) in PSC patients based on serum immunoglobulin G4 (IgG4) levels.

METHODS

A retrospective chart review was conducted on PSC patients seen at the University of Alberta Hospital between 2002 and 2017. PSC patients were categorized as high IgG4 group (≥70 mg/dL) or normal IgG4 group (<70 mg/dL). Laboratory parameters, clinical characteristics, and outcomes were compared between the groups.

RESULTS

One hundred and ten patients were followed over a mean period of 7.3 (SD 5) years. Seventy-two patients (66%) were male, the mean age at diagnosis of PSC was 35 (SD 15) years, and inflammatory bowel disease (IBD) was present in 80 patients (73%). High IgG4 levels were found in 37 patients (34%). PSC patients with high IgG4 had a shorter mean cholangitis-free survival time (5.3 versus 10.4 years, p = 0.02), cirrhosis-free survival time (8.7 versus 13.0 years, p = 0.02), and LT-free survival time (9.3 years versus 18.9 years, p <0.001). IgG4 ≥70 mg/dL was independently associated with liver decompensation and LT-free outcomes. A cut-off IgG4 value of ≥70 mg/dL performed better than a cut-off value of ≥140 mg/dL to predict time to LT (area under the curve [AUC] 0.68, p = 0.03, sensitivity 72%, specificity 78%).

CONCLUSIONS

Serum IgG4 ≥70 mg/dL in PSC predicts a shorter time to cirrhosis decompensation and LT.

EASL Clinical Practice Guidelines on non-invasive tests for evaluation of liver disease severity and prognosis - 2021 update

Non-invasive tests are increasingly being used to improve the diagnosis and prognostication of chronic liver diseases across aetiologies. Herein, we provide the latest update to the EASL Clinical Practice Guidelines on the use of non-invasive tests for the evaluation of liver disease severity and prognosis, focusing on the topics for which relevant evidence has been published in the last 5 years.

Diagnosing Biliary Strictures: Distinguishing IgG4-Related Sclerosing Cholangitis From Cholangiocarcinoma and Primary Sclerosing Cholangitis

Biliary strictures caused by inflammation or fibrosis lead to jaundice and cholangitis which often make it difficult to distinguish malignant strictures. In cases when malignancy cannot be excluded, surgery is often performed. The concept of immunoglobulin G4 (IgG4)-related sclerosing cholangitis (SC) as a benign biliary stricture was recently proposed. The high prevalence of the disease in Asian countries has resulted in multiple diagnostic and treatment guidelines; however, there is need to formulate a standardized diagnostic strategy among various countries considering the utility, invasiveness, and cost-effectiveness. We evaluated accuracies of various diagnostic modalities for biliary strictures comparing pathology in the Delphi meetings which were held in Rochester, MN. The diagnostic utility for each modality was graded according to the experts, including gastroenterologists, endoscopists, radiologists, and pathologists from the United States and Japan. Diagnostic utility of 10 modalities, including serum IgG4 level, noninvasive imaging, endoscopic ultrasound, endoscopic retrograde cholangiopancreatography-related diagnostic procedures were advocated and the reasons were specified. Serum IgG4 level, noninvasive imaging, diagnostic endoscopic ultrasound and intraductal ultrasonography under endoscopic retrograde cholangiopancreatography were recognized as useful modalities for the diagnosis. The information in this article will aid in the diagnosis of biliary strictures particularly for distinguishing IgG4-SC from cholangiocarcinoma and/or primary SC.

Cellular Mechanisms of Liver Fibrosis

The liver is a central organ in the human body, coordinating several key metabolic roles. The structure of the liver which consists of the distinctive arrangement of hepatocytes, hepatic sinusoids, the hepatic artery, portal vein and the central vein, is critical for its function. Due to its unique position in the human body, the liver interacts with components of circulation targeted for the rest of the body and in the process, it is exposed to a vast array of external agents such as dietary metabolites and compounds absorbed through the intestine, including alcohol and drugs, as well as pathogens. Some of these agents may result in injury to the cellular components of liver leading to the activation of the natural wound healing response of the body or fibrogenesis. Long-term injury to liver cells and consistent activation of the fibrogenic response can lead to liver fibrosis such as that seen in chronic alcoholics or clinically obese individuals. Unidentified fibrosis can evolve into more severe consequences over a period of time such as cirrhosis and hepatocellular carcinoma. It is well recognized now that in addition to external agents, genetic predisposition also plays a role in the development of liver fibrosis. An improved understanding of the cellular pathways of fibrosis can illuminate our understanding of this process, and uncover potential therapeutic targets. Here we summarized recent aspects in the understanding of relevant pathways, cellular and molecular drivers of hepatic fibrosis and discuss how this knowledge impact the therapy of respective disease.

Primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a rare chronic cholestatic liver disease characterized by inflammatory destruction of the intrahepatic and/or extrahepatic bile ducts, leading to bile stasis, fibrosis, and ultimately to cirrhosis, and often requires liver transplantation (LT). PSC occurs more commonly in men, and is typically diagnosed between the ages of 30 and 40. Most cases occur in association with inflammatory bowel disease (IBD), which often precedes the development of PSC. PSC is usually diagnosed after detection of cholestasis during health evaluation or screening of patients with IBD. When symptomatic, the most common presenting symptoms are abdominal pain, pruritus, jaundice or fatigue. The etiology of PSC is poorly understood, but an increasing body of evidence supports the concept of cholangiocyte injury as a result of environmental exposure and an abnormal immune response in genetically susceptible individuals. PSC is a progressive disease, yet no effective medical therapy for halting disease progression has been identified. Management of PSC is mainly focused on treatment of symptoms and addressing complications. PSC can be complicated by bacterial cholangitis, dominant strictures (DSs), gallbladder polyps and adenocarcinoma, cholangiocarcinoma (CCA) and, in patients with IBD, colorectal malignancy. CCA is the most common malignancy in PSC with a cumulative lifetime risk of 10-20%, and accounts for a large proportion of mortality in PSC. LT is currently the only life-extending therapeutic approach for eligible patients with end-stage PSC, ultimately required in approximately 40% of patients. LT secondary to PSC has an excellent outcome compared to other LT indications, although the disease can recur and result in morbidity post-transplant.

Common Denominators in the Immunobiology of IgG4 Autoimmune Diseases: What Do Glomerulonephritis, Pemphigus Vulgaris, Myasthenia Gravis, Thrombotic Thrombocytopenic Purpura and Autoimmune Encephalitis Have in Common?

IgG4 autoimmune diseases (IgG4-AID) are an emerging group of autoimmune diseases that are caused by pathogenic autoantibodies of the IgG4 subclass. It has only recently been appreciated, that members of this group share relevant immunobiological and therapeutic aspects even though different antigens, tissues and organs are affected: glomerulonephritis (kidney), pemphigus vulgaris (skin), thrombotic thrombocytopenic purpura (hematologic system) muscle-specific kinase (MuSK) in myasthenia gravis (peripheral nervous system) and autoimmune encephalitis (central nervous system) to give some examples. In all these diseases, patients’ IgG4 subclass autoantibodies block protein-protein interactions instead of causing complement mediated tissue injury, patients respond favorably to rituximab and share a genetic predisposition: at least five HLA class II genes have been reported in individual studies to be associated with several different IgG4-AID. This suggests a role for the HLA class II region and specifically the DRβ1 chain for aberrant priming of autoreactive T-cells toward a chronic immune response skewed toward the production of IgG4 subclass autoantibodies. The aim of this review is to provide an update on findings arguing for a common pathogenic mechanism in IgG4-AID in general and to provide hypotheses about the role of distinct HLA haplotypes, T-cells and cytokines in IgG4-AID.

Genetic variants of UDP-glucuronosyltransferase 1A genes are associated with disease presentation and outcome in primary sclerosing cholangitis

BACKGROUND AND AIMS

Primary sclerosing cholangitis (PSC) is a progressive cholestatic liver disease without a curative medical therapy. The human UDP-glucuronosyltransferases 1A play a major role in the detoxification and elimination of bilirubin, bile acids and xenobiotics. Whether genetic UGT1A variants determine course and outcome of PSC has not yet been described.

METHODS

A large cohort of German PSC patients with a long-term-follow-up was genotyped for UGT1A variants including UGT1A1*28, UGT1A3-66 T>C and UGT1A7 p.N129K/p.R131K using TaqMan 5'-nuclease assays. Results were correlated with clinical characteristics and transplant-free survival.

RESULTS

About 331 patients with PSC were included in the study (69.9% male, mean age at diagnosis 32.6 years). Median transplant-free survival was 14.9 years. Patients with wild-type alleles of all three UGT1A genes had a longer transplant-free survival (17.2 vs. 14.4 years, P = .048) than patients carrying a homozygous or heterozygous SNP variant in at least one of the UGT1A1, UGT1A3 or UGT1A7 genes. Additionally, we found that patients carrying wild-type alleles of all three UGT1A genes had lower serum bilirubin (25 vs. 38 µmol/L, P = .02) and serum cholesterol (195 vs. 223 mg/dL), P = .035) at first presentation. Furthermore, inflammatory bowel disease was found to be associated with wild-type UGT1A alleles (82.2% vs. 68.4%, P = .046).

CONCLUSIONS

This large cohort shows an association with single nucleotide polymorphisms of the UGT1A1, UGT1A3 and UGT1A7 genes and outcome in PSC. Thus, UGT1A variants may represent a tool for the prognostic stratification of PSC patients and establish a link between disease progression and the regulation of detoxification by glucuronidation in PSC.

Review of primary sclerosing cholangitis with increased IgG4 levels

Primary sclerosing cholangitis (PSC) is a chronic progressive liver disease. Sub-types of PSC have been described, most recently PSC with elevated serum and/or tissue IgG4 subclass. We aim to summarise the clinical phenotype, disease associations, differential diagnosis, response to therapy and pathogenic mechanisms underlying PSC-high IgG4 subtype. We reviewed PubMed, MEDLINE and Embase with the search terms "primary sclerosing cholangitis", "IgG4", and "IgG4-related sclerosing cholangitis (IgG4-SC)". Elevated serum IgG4 are found in up-to one-quarter, and abundant IgG4-plasma cell infiltrates in the liver and bile ducts are found in up-to one-fifth of PSC patients. This group have a distinct clinical phenotype, with some studies reporting a more aggressive course of liver and associated inflammatory bowel disease, compared to PSC-normal IgG4 and the disease mimic IgG4-SC. Distinguishing PSC-high IgG4 from IgG4-SC remains challenging, requiring careful assessment of clinical features, organ involvement and tissue morphology. Calculation of serum IgG4:IgG1 ratios and use of a novel IgG4:IgG RNA ratio have been reported to have excellent specificity to distinguish IgG4-SC and PSC-high IgG4 but require validation in larger cohorts. A role for corticosteroid therapy in PSC-high IgG4 remains unanswered, with concerns of increased toxicity and lack of outcome data. The immunological drivers underlying prominent IgG4 antibodies in PSC are incompletely defined. An association with PSC-high IgG4 and HLA class-II haplotypes (B*07, DRB1*15), T-helper2 and T-regulatory cytokines (IL4, IL10, IL13) and chemokines (CCL1, CCR8) have been described. PSC-high IgG4 have a distinct clinical phenotype and need careful discrimination from IgG4-SC, although response to immunosuppressive treatments and long-term outcome remains unresolved. The presence of IgG4 likely represents chronic activation to persistent antigenic exposure in genetically predisposed individuals.

Primary sclerosing cholangitis with increased immunoglobulin G4 levels: A case report

RATIONALE

Primary sclerosing cholangitis (PSC) is recognized as an autoimmune-mediated liver disease characterized by progressive biliary inflammation and fibrosis. Some PSC cases with elevated immunoglobulin G4 (IgG4) levels are likely to be misdiagnosed with immunoglobulin G4-related sclerosing cholangitis (IgG4-SC). Thus, distinguishing these 2 diseases is particularly important.

PATIENT CONCERNS

A 34-year-old male presented with right hypochondrium abdominal intermittent pain and jaundice lasting for 1 month. Here, we present a case of PSC with increased IgG4 levels with improvement of quality of life upon liver transplantation (LT).

DIAGNOSIS

The diagnosis of PSC was confirmed based on clinical symptoms, laboratory test results, imaging findings, pathologic results and a lack of response to steroid therapy.

INTERVENTIONS

LT surgery was performed successfully when his vital parameters were stabilized. Immunosuppressive agents were routinely used after LT.

OUTCOMES

Three years after LT, liver function values show that alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were in the normal range. An abdominal ultrasonography showed no obvious abnormalities.

LESSONS

There are similar biochemical characteristics and cholangiographic findings between PSC and IgG4-SC. Therefore, distinguishing these 2 diseases is particularly important. LT remains the only option for end-stage PSC. Early diagnosis and effective treatment can achieve a good prognosis.

Variant and Specific Forms of Autoimmune Cholestatic Liver Diseases

Primary biliary cholangitis (PBC) and primary sclerosing cholangitis (PSC) are the main autoimmune cholestatic liver diseases. IgG4-associated sclerosing cholangitis is another distinct immune-mediated cholestatic disorder of unknown aetiology that is frequently associated with autoimmune pancreatitis or other IgG4-related diseases. Although the majority of PBC and PSC patients have a typical presentation, there are common and uncommon important variants or specific subgroups that observed in everyday routine clinical practice. In this updated review, we summarize the published data giving also our own experience on the variants and specific groups of autoimmune cholestatic liver diseases. Actually, we give in detail the underlining difficulties and the rising dilemmas concerning the diagnosis and management of these special conditions in the clinical spectrum of autoimmune cholestatic liver diseases including the IgG4-associated sclerosing cholangitis highlighting also the uncertainties and the potential new eras of the research agenda.

Clinical practice guidelines for IgG4-related sclerosing cholangitis

IgG4‐related sclerosing cholangitis (IgG4‐SC) is a distinct type of cholangitis frequently associated with autoimmune pancreatitis and currently recognized as a biliary manifestation of IgG4‐related disease. Although clinical diagnostic criteria of IgG4‐SC were established in 2012, differential diagnosis from primary sclerosing cholangitis and cholangiocarcinoma is sometimes difficult. Furthermore, no practical guidelines for IgG4‐SC are available. Because the evidence level of most articles retrieved through searching the PubMed, Cochrane Library, and Igaku Chuo Zasshi databases was below C based on the systematic review evaluation system of clinical practice guidelines MINDS 2014, we developed consensus guidelines using the modified Delphi approach. Three committees (a guideline creating committee, an expert panelist committee for rating statements according to the modified Delphi method, and an evaluating committee) were organized. Eighteen clinical questions (CQs) with clinical statements were developed regarding diagnosis (14 CQs) and treatment (4 CQs). Recommendation levels for clinical statements were set using the modified Delphi approach. The guidelines explain methods for accurate diagnosis, and safe and appropriate treatment of IgG4‐SC.

The impact of human leukocyte antigen donor and recipient serotyping and matching on liver transplant graft failure in primary sclerosing cholangitis, autoimmune hepatitis, and primary biliary cholangitis

Human leukocyte antigen (HLA) serotyping is not considered to have significant impact on liver graft survival and does not factor into U.S. organ allocation. Immune-related liver diseases such as primary sclerosing cholangitis (PSC), autoimmune hepatitis (AIH), and primary biliary cholangitis (PBC) have been speculated to represent a disease subgroup that may have significantly different graft outcomes depending on HLA donor/recipient characterization. The aim of this study was to investigate whether HLA serotyping/matching influenced post-transplant graft failure for immune-related liver diseases using the United Network for Organ Sharing database. From 1994 to 2015, 5665 patients underwent first-time liver-only transplants for PSC, AIH, and PBC with complete graft survival and donor/recipient HLA data. Graft failure was noted in 38.6% (2188/5665), and all groups had comparable 5-year graft survival (75.1%-78.8%, P = 0.069). The overall degree of, and loci-specific mismatch level, did not influence outcomes. Multivariable Cox proportional hazards regression noted increased graft failure risk for recipient HLA-B7, HLA-B57, HLA-B75, HLA-DR13 and donor HLA-B55, HLA-B58, and HLA-DR8 for PSC patients, protective effects for recipient HLA-DR1 and HLA-DR3 for AIH patients, and increased risk for HLA-DR7 for AIH patients. These findings warrant further investigation to evaluate the impact of HLA serotyping on post-transplant outcomes.

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.

Antineutrophil antibodies define clinical and genetic subgroups in primary sclerosing cholangitis

BACKGROUND & AIMS

The strongest genetic risk factors in primary sclerosing cholangitis (PSC) are encoded in the HLA complex. Antineutrophil cytoplasmic antibodies (ANCA) have been reported in up to 94% of PSC patients, but their clinical significance and immunogenetic basis are ill defined. We aimed to characterize clinical and genetic associations of ANCA in PSC.

METHODS

Antineutrophil cytoplasmic antibodies were analysed with indirect immunofluorescence in 241 Norwegian PSC patients. HLA-B and HLA-DRB1 genotyping was performed in the patients and in 368 healthy controls. Data on perinuclear ANCA (pANCA) and HLA-DRB1 were available from 274 ulcerative colitis (UC) patients without known liver disease.

RESULTS

Antineutrophil cytoplasmic antibodies were found in 193 (80%) of the PSC patients, with pANCA in 169 (70%). ANCA-positive patients were younger than ANCA negative at diagnosis of PSC and had a lower frequency of biliary cancer (9% vs 19%, P=.047). There were no differences between PSC patients with and without inflammatory bowel disease. Genetically, the strong PSC risk factors HLA-B*08 (frequency in healthy 13%) and DRB1*03 (14%) were more prevalent in ANCA-positive than -negative patients (43% vs 25%, P=.0012 and 43% vs 25%, P=.0015 respectively). The results were similar when restricting the analysis to pANCA-positive patients. In UC patients without liver disease, HLA-DRB1*03 was more prevalent in pANCA-positive compared with -negative patients (P=.03).

CONCLUSIONS

Antineutrophil cytoplasmic antibodies identified PSC patients with particular clinical and genetic characteristics, suggesting that ANCA may mark a clinically relevant pathogenetic subgroup in the PSC-UC disease spectrum.

High-density Association Mapping and Interaction Analysis of PLA2R1 and HLA Regions with Idiopathic Membranous Nephropathy in Japanese

Although recent studies showed anti-PLA2R antibody plays a crucial role in idiopathic membranous nephropathy (IMN), detailed HLA mapping and interaction between the HLA genes and PLA2R1 have not been investigated in IMN. We genotyped across the PLA2R1 gene and the HLA region, using 183 IMN patients and 811 healthy controls. Five SNPs around the PLA2R1 gene were significantly associated with IMN. In addition to the two SNPs previously reported to be strongly associated with IMN, rs3749119 and rs35771982 (OR 3.02 and 2.93, P = 3.24E-14 and 4.64E-14, respectively), two novel intronic SNPs (rs2715928 and rs16844715) were also identified as IMN-associated SNPs (OR = 2.30 and 2.51, P = 3.15E-10 and 5.66E-13, respectively). In the HLA gene analysis, DRB1*1501 and DQB1*0602 were strongly associated with IMN (P = 1.14E-11 and 1.25E-11, respectively). The interaction was strongest between HLA-DRB1*15:01 - HLA-DQB1*06:02 and the intronic SNP rs2715928 (OR = 17.53, P = 4.26E-26). Furthermore, positive interaction was also observed between HLA-DRB1*15:01 - HLA-DQB1*06:02 and the missense SNP rs35771982 (OR = 15.91, P = 2.76E-29), which is in strong linkage disequilibrium with 5′UTR SNP rs3749119, and intronic SNP rs16844715 (OR = 15.91, P = 2.30E-26) for IMN. Neither HLA-DRB1*15:01 nor HLA-DQB1*06:02 was associated with steroid responsiveness, overall survival and renal survival during the observation period of mean 11 years though limited number of analysis.

IgG4-related hepatobiliary disease: an overview

IgG4-related hepatobiliary diseases are part of a multiorgan fibroinflammatory condition termed IgG4-related disease, and include IgG4-related sclerosing cholangitis (IgG4-SC) and IgG4-related hepatopathy. These diseases can present with biliary strictures and/or mass lesions, making them difficult to differentiate from primary sclerosing cholangitis (PSC) or other hepatobiliary malignancies. Diagnosis is based on a combination of clinical, biochemical, radiological and histological findings. However, a gold standard diagnostic test is lacking, warranting the identification of more specific disease markers. Novel assays - such as the serum IgG4:IgG1 ratio and IgG4:IgG RNA ratio (which distinguish IgG4-SC from PSC with high serum IgG4 levels), and plasmablast expansion to recognize IgG4-SC with normal serum IgG4 levels - require further validation. Steroids and other immunosuppressive therapies can lead to clinical and radiological improvement when given in the inflammatory phase of the disease, but evidence for the efficacy of treatment regimens is limited. Progressive fibrosclerotic disease, liver cirrhosis and an increased risk of malignancy are now recognized outcomes. Insights into the genetic and immunological features of the disease have increased over the past decade, with an emphasis on HLAs, T cells, circulating memory B cells and plasmablasts, chemokine-mediated trafficking, as well as the role of the innate immune system.

Infliximab-Associated Immunomediated Hepatitis in Children With Inflammatory Bowel Disease

Infliximab (IFX) is commonly used to induce and maintain remission in inflammatory bowel disease (IBD). We report the first 2 cases of children with ulcerative colitis who had normal liver transaminases before IFX and were diagnosed with immunomediated hepatitis after IFX induction. Both the cases had negative antibodies for antinuclear, smooth muscle, and liver kidney microsome, with 1 patient having positive autoimmune serology (dsDNA) and overlap primary sclerosing cholangitis. IFX was discontinued and transaminases normalized without steroid administration. Clinicians treating pediatric patients with IBD with IFX should be aware of IFX immunomediated hepatitis. This phenomenon is previously reported in adult patients with IBD. To our knowledge, these are the first cases reported in pediatric patients with IBD.

Adult bile duct strictures: differentiating benign biliary stenosis from cholangiocarcinoma

Biliary epithelial cells preferentially respond to various insults under chronic pathological conditions leading to reactively atypical changes, hyperplasia, or the development of biliary neoplasms (such as biliary intraepithelial neoplasia, intraductal papillary neoplasm of the bile duct, and cholangiocarcinoma). Moreover, benign biliary strictures can be caused by a variety of disorders (such as IgG4-related sclerosing cholangitis, eosinophilic cholangitis, and follicular cholangitis) and often mimic malignancies, despite their benign nature. In addition, primary sclerosing cholangitis is a well-characterized precursor lesion of cholangiocarcinoma and many other chronic inflammatory disorders increase the risk of malignancies. Because of these factors and the changes in biliary epithelial cells, biliary strictures frequently pose a diagnostic challenge. Although the ability to differentiate neoplastic from non-neoplastic biliary strictures has markedly progressed with the advance in radiological modalities, brush cytology and bile duct biopsy examination remains effective. However, no single modality is adequate to diagnose benign biliary strictures because of the low sensitivity. Therefore, understanding the underlying causes by compiling the entire clinical, laboratory, and imaging data; considering the under-recognized causes; and collaborating between experts in various fields including cytopathologists with multiple approaches is necessary to achieve an accurate diagnosis.

The changing faces of cholangitis

A variety of diseases are included under the umbrella term ‘cholangitis’, including hepatobiliary diseases with an autoimmune pathogenesis (such as primary sclerosing cholangitis, primary biliary cholangitis, and IgG4-associated sclerosing cholangitis) and disease processes associated with intraductal stones and infectious etiologies (such as ascending bacterial cholangitis, recurrent pyogenic cholangitis, and liver fluke-associated cholangitis). Recent advances in the pathophysiologic bases of these disorders, particularly with respect to the autoimmune variety, are allowing improved diagnosis and prognostication as well as providing the opportunity to refine and re-imagine treatment modalities. The aim of this review is to highlight selected advances in cholangitis research that point to novel insights into the pathophysiology, diagnosis, and treatment of this diverse array of disorders.

Differentiation of benign and malignant hilar bile duct stenosis

BACKGROUND

Failure to differentiate benign and malignant hilar bile duct stenosis may lead to inappropriate treatment. We retrospectively analyzed the methods for differentiation.

MATERIALS AND METHODS

A total of 53 patients with hilar bile duct stenosis were included, comprising 41 malignant cases (hilar cholangiocarcinoma) and 12 benign cases (six primary sclerosing cholangitis and six IgG4-associated sclerosing cholangitis). Data of clinical histories, laboratory tests, imaging studies, and liver pathologies were collected, and comparison was made between benign and malignant groups.

RESULTS

Compared with malignant group, patients in the benign group were more likely to have multiorgan involvement of clinical histories (P < 0.001). There was no difference on bilirubin, liver enzyme, and serum tumor marker between the two groups, whereas serum IgG4 levels were higher in the benign group (P = 0.003). Patients in the benign group were more likely to have pancreatic changes (P < 0.001) and multiple-segmental bile duct stenosis (P < 0.001) on imaging. Compared with the malignant group, patients in the benign group were more likely to show severe periportal inflammation in noninvolved liver (P < 0.001), fibrosis around intrahepatic bile duct (P < 0.001), and more IgG4-positive plasma cells (P < 0.001) on liver pathology.

CONCLUSIONS

Benign lesion should be considered for patients with history of multiorgan involvement, pancreas changes, or multiple-segmental bile duct stenosis on imaging. Liver biopsy could be helpful for differential diagnosis before surgery.

High-throughput T-cell receptor sequencing across chronic liver diseases reveals distinct disease-associated repertoires

Hepatic T-cell infiltrates and a strong genetic human leukocyte antigen association represent characteristic features of various immune-mediated liver diseases. Conceptually the presence of disease-associated antigens is predicted to be reflected in T-cell receptor (TCR) repertoires. Here, we aimed to determine if disease-associated TCRs could be identified in the nonviral chronic liver diseases primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), and alcoholic liver disease (ALD). We performed high-throughput sequencing of the TCRβ chain complementarity-determining region 3 of liver-infiltrating T cells from PSC (n = 20), PBC (n = 10), and ALD (n = 10) patients, alongside genomic human leukocyte antigen typing. The frequency of TCRβ nucleotide sequences was significantly higher in PSC samples (2.53 ± 0.80, mean ± standard error of the mean) compared to PBC samples (1.13 ± 0.17, P < 0.0001) and ALD samples (0.62 ± 0.10, P < 0.0001). An average clonotype overlap of 0.85% was detected among PSC samples, significantly higher compared to the average overlap of 0.77% seen within the PBC (P = 0.024) and ALD groups (0.40%, P < 0.0001). From eight to 42 clonotypes were uniquely detected in each of the three disease groups (≥30% of the respective patient samples). Multiple, unique sequences using different variable family genes encoded the same amino acid clonotypes, providing additional support for antigen-driven selection. In PSC and PBC, disease-associated clonotypes were detected among patients with human leukocyte antigen susceptibility alleles.

CONCLUSION

We demonstrate liver-infiltrating disease-associated clonotypes in all three diseases evaluated, and evidence for antigen-driven clonal expansions. Our findings indicate that differential TCR signatures, as determined by high-throughput sequencing, may represent an imprint of distinctive antigenic repertoires present in the different chronic liver diseases; this thereby opens up the prospect of studying disease-relevant T cells in order to better understand and treat liver disease.

The Immunogenetics of Autoimmune Cholestasis

The immune-mediated hepatobiliary diseases, primary biliary cirrhosis and primary sclerosing cholangitis are relatively rare, albeit and account for a significant amount of liver transplant activity and liver-related mortality globally. Precise disease mechanisms are yet to be described although a contributory role of genetic predisposition is firmly established. In addition to links with the major histocompatibility complex, a number of associations outside this region harbor additional loci which underscore the fundamental role of breaks in immune tolerance and mucosal immunogenicity in the pathogenesis of autoimmune biliary disease. We provide an overview of these key discoveries before discussing putative avenues of therapeutic exploitation based on existing findings.

Primary sclerosing cholangitis - the Norwegian experience

Research related to primary sclerosing cholangitis (PSC) has since 1980 been a major activity at the Oslo University Hospital Rikshospitalet. The purpose of this publication is to describe the development of this research, the impact of this research on the clinical handling of the patients, and finally to describe what we believe are the most urgent, remaining problems to be solved. During the early years, our research dealt primarily with clinical aspects of the disease. The concomitant inflammatory bowel disease (IBD) seen in most patients with PSC was a major interest and we also started looking into genetic associations of PSC. Prognosis, malignancy development and treatment with special emphasis on transplantation have later been dealt with. These activities has had impact on several aspects of PSC management; when and how to diagnose PSC and variant forms of PSC, how to handle IBD in PSC and how to deal with the increased rate of malignancy? The problems remaining to be solved are many. What is the role of the gut and the gut microbiota in the development of PSC? Do the PSC patients have an underlying disturbance in the bile homeostasis? And how does the characteristic type of fibrosis in PSC develop? The genetic studies have supported a role for the adaptive immune system in the disease development, but how should this be dealt with? Importantly, the development of malignancy in PSC is still not understood, and we lack appropriate medical treatment for our patients.