IgG4-related autoimmune pancreatitis and sclerosing cholangitis: A case report and literature review

RATIONALE

Immunoglobulin G4-related disease (IgG4-RD) can involve various organs throughout the body, primarily manifesting as endocrine dysfunction, visual impairment, jaundice, and limited sexual function. IgG4-related autoimmune pancreatitis is triggered by autoimmune reactions and characterized by structural changes in the pancreas and pancreatic ducts. The disease mainly affects middle-aged and elderly males, typically presenting as progressive painless jaundice and misdiagnosed as cholangiocarcinoma or pancreatic cancer.

PATIENT CONCERNS

This study reports a 54-year-old male who consulted with different institutions multiple times due to diabetes, pancreatitis, elevated liver enzymes, and jaundice.

DIAGNOSES

Magnetic resonance imaging revealed swollen head of the pancreas and atrophic tail. Liver and pancreatic tissue pathology showed IgG4 plasma cell infiltration, while liver biopsy indicated interface hepatitis, liver fibrosis, and pseudolobule formation, with no evidence of bile duct damage.

INTERVENTIONS

Following hormone therapy, the patient's serum IgG4 levels and liver enzyme levels returned to normal.

OUTCOMES

The disease relapsed 2 years after maintaining hormone therapy, and the patient underwent additional hormone-induced remission therapy combined with azathioprine.

LESSONS

The purpose of this research report is to enhance the awareness and understanding of IgG4-RD, emphasizing the necessity for personalized treatment strategies that take into account its recurrence, associations, and imaging features. This report provides valuable insights and guidance for clinicians in managing and diagnosing patients with IgG4-RD.

Autoantibodies to beta tubulin in autoimmune liver diseases-Relation to pANCA and clinical relevance

There was evidence that perinuclear antineutrophil cytoplasmic antibodies (pANCA) in autoimmune liver diseases react with human beta-tubulin-5 (TBB5). Here, we reevaluate the specificity and clinical relevance of anti-TBB5 antibodies. Patients with untreated autoimmune hepatitis (AIH; n = 53), AIH under immunosuppressive therapy (AIH-IS; n = 125), primary sclerosing cholangitis (PSC; n = 40), primary biliary cholangitis (PBC; n = 250), nonautoimmune liver diseases (n = 158), inflammatory bowel diseases (IBD; n = 30), and healthy individuals (n = 62) were tested by enzyme-linked immunosorbent assay for IgG- and IgA-antibodies against recombinant human TBB5. pANCA were detected by immunofluorescence test. Sera were absorbed with TBB5 coupled to cyanogen bromide-activated sepharose. Prevalence and reactivity of IgG anti-TBB5 were significantly higher in patients with untreated AIH (68%; arbitrary units [AU] median: 369) than in PSC (28%; AU median: 84, P < 0.001), other liver diseases (14%; AU median: 185, P < 0.0001), IBD (3%; AU median: 111, P < 0.0001), and healthy controls (3%; AU median: 135; P < 0.0001). Anti-TBB5 did not correlate with pANCA, and immunoprecipitation with TBB5 did not abolish pANCA reactivity. In untreated AIH, anti-TBB5-reactivity was significantly higher than in AIH-IS. Transaminases decreased under IS preferentially in anti-TBB5-negative patients. There was no correlation between anti-TBB5-reactivity and histological stages. IgA-anti-TBB5 was mainly found in alcohol-associated liver disease (ALD; 39%). Our data do not support TBB5 as an autoantigenic target of pANCA. However, IgG-anti-TBB5 showed high specificity for (untreated) AIH. While they did not correlate with histological and laboratory parameters, their presence may indicate a poor response to IS.

Gut-Liver Immune Traffic: Deciphering Immune-Pathogenesis to Underpin Translational Therapy

The tight relationship between the gut and liver on embryological, anatomical and physiological levels inspired the concept of a gut-liver axis as a central element in the pathogenesis of gut-liver axis diseases. This axis refers to the reciprocal regulation between these two organs causing an integrated system of immune homeostasis or tolerance breakdown guided by the microbiota, the diet, genetic background, and environmental factors. Continuous exposure of gut microbiome, various hormones, drugs and toxins, or metabolites from the diet through the portal vein adapt the liver to maintain its tolerogenic state. This is orchestrated by the combined effort of immune cells network: behaving as a sinusoidal and biliary firewall, along with a regulatory network of immune cells including, regulatory T cells and tolerogenic dendritic cells (DC). In addition, downregulation of costimulatory molecules on hepatic sinusoids, hepatocytes and biliary epithelial cells as well as regulating the bile acids chain also play a part in hepatic immune homeostasis. Recent evidence also demonstrated the link between changes in the gut microbiome and liver resident immune cells in the progression of cirrhosis and the tight correlation among primary sclerosing cholangitis (PSC) and also checkpoint induced liver and gut injury. In this review, we will summarize the most recent evidence of the bidirectional relationship among the gut and the liver and how it contributes to liver disease, focusing mainly on PSC and checkpoint induced hepatitis and colitis. We will also focus on completed therapeutic options and on potential targets for future treatment linking with immunology and describe the future direction of this research, taking advantage of modern technologies.

Serum IgG4 Subclass Deficiency Defines a Distinct, Commonly Encountered, Severe Inflammatory Bowel Disease Subtype

BACKGROUND

Immunoglobulin G subclass 4 (IgG4) is hypothesized to play an immunomodulatory role, downregulating humoral immune responses. The role of this anti-inflammatory molecule in inflammatory bowel disease (IBD) has not been fully characterized. We sought to define alterations in serum IgG4 in patients with IBD and their association with multiyear disease severity.

METHODS

We analyzed metadata derived from curated electronic health records from consented patients with IBD prospectively followed at a tertiary center over a 10-year time period. Patients with IBD with IgG4 serum levels available formed the study population. Demographics and multiyear clinical data were collected and analyzed. We stratified patients with IBD with low, normal, or high serum IgG4 levels.

RESULTS

We found IgG4 characterized in 1193 patients with IBD and low IgG4 levels in 233 patients (20%) and elevated IgG4 levels in 61 patients (5%). An IgG4 deficiency did not significantly correlate with other antibody deficiencies. In a multiple Poisson regression analysis, low IgG4 was associated with more years on biologic agents (P = 0.002) and steroids (P = 0.049) and more hospital admissions (P < 0.001), clinic visits (P = 0.010), outpatient antibiotic prescriptions (P < 0.001), and CD-related surgeries (P = 0.011) during the study period after controlling for certain confounders. Elevated IgG4 was only associated with primary sclerosing cholangitis (P = 0.011). A cohort of patients with IgG4-deficient severe IBD received intravenous Ig replacement therapy, which benefited and was continued in 10 out of 11 individuals.

CONCLUSIONS

An IgG4 subclass deficiency, distinct from other antibody deficiencies, occurred commonly in a referral IBD population and was associated with multiple markers of disease severity. This is the first association of IgG4 subclass deficiency with an inflammatory disease process. Further work is needed to define the mechanistic role of IgG4 deficiency in this severe IBD subgroup.

Immunoglobulin G4-Related Sclerosing Cholangitis Revealed by 68Ga-FAPI PET/MR

ABSTRACT

A 60-year-old woman with surgically confirmed immunoglobulin G4-related sclerosing cholangitis underwent 18F-FDG PET/CT due to significantly elevated serum CA-19-9 level, which revealed a hypermetabolic lesion in the residual liver. 68Ga-FAPI PET/MR was performed to further evaluate whether the FDG-avid lesion is a malignant tumor. Astonishingly, diffuse intense radioactivity was revealed throughout the liver, suggesting involvement of active immunoglobulin G4-related sclerosing cholangitis, but nonfocal elevated 68Ga-FAPI accumulation in the FDG-avid lesion indicated postoperative change. From this case, we speculated that FAPI imaging could be used for evaluation of chronic liver disease because fibroblast activation protein has a profibrogenic role in chronic liver injury.

Circulating Macrophage Activation Markers Predict Transplant-Free Survival in Patients With Primary Sclerosing Cholangitis

INTRODUCTION

Primary sclerosing cholangitis (PSC) is a progressive liver disease characterized by bile duct inflammation and fibrosis. The role of macrophages in PSC development and progression is less studied. Macrophage activation markers soluble (s)CD163 and mannose receptor (sMR) are associated with disease severity and outcome in other liver diseases, but not previously investigated in PSC. We evaluated sCD163 and sMR regarding disease severity and prognosis in patients with PSC.

METHODS

We investigated 2 independent PSC cohorts from Oslo (n = 138) and Helsinki (n = 159) and analyzed blood sCD163 and sMR levels. The Mayo score, Enhanced Liver Fibrosis Test, and Amsterdam-Oxford model were assessed for comparison.

RESULTS

Median (interquartile range) sCD163 was 3.32 (2.27-5.60) and 1.96 (1.47-2.70) mg/L in the Oslo and Helsinki cohorts, respectively, reflecting differences in disease severity between cohorts. Median sMR was similar in both cohorts, 0.28 (0.22-0.44) and 0.28 mg/L (0.20-0.36), respectively. In both cohorts, sCD163 and sMR levels raised with increasing disease severity (liver enzymes, Mayo score, and enhanced liver fibrosis test). Patients with high baseline levels of sCD163 had shorter transplant-free survival than patients with low baseline levels. Furthermore, sCD163 was associated with transplant-free survival in univariate cox-regression analyses. Both sCD163 and sMR performed better in the Oslo cohort of more severely diseased patients than those in the Helsinki cohort of more mildly diseased patients.

DISCUSSION

Macrophage activation markers are elevated according to disease severity suggesting an important role of macrophages in PSC. Furthermore, sCD163 was identified as a prognostic marker and predictor of transplant-free survival in PSC (see Visual Abstract, Supplementary Digital Content 4, http://links.lww.com/CTG/A516).

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.

Gut microbiome in primary sclerosing cholangitis: A review

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

Effects of Vedolizumab in Patients With Primary Sclerosing Cholangitis and Inflammatory Bowel Diseases

BACKGROUND & AIMS

Gut-homing lymphocytes that express the integrin α4β7 and CCR9 might contribute to development of primary sclerosing cholangitis (PSC). Vedolizumab, which blocks the integrin α4β7, is used to treat patients with inflammatory bowel diseases (IBD), but there are few data on its efficacy in patients with PSC. We investigated the effects of vedolizumab in a large international cohort of patients with PSC and IBD.

METHODS

We collected data from European and North American centers participating in the International PSC Study Group from patients with PSC and IBD who received at least 3 doses of vedolizumab (n = 102; median vedolizumab treatment duration, 412 days). Demographic and clinical data were collected from baseline and during the follow-up period (until liver transplantation, death, or 56 days after the final vedolizumab infusion). We analyzed overall changes in biochemical features of liver and proportions of patients with reductions in serum levels of alkaline phosphatase (ALP) of 20% or more, from baseline through last follow-up evaluation. Other endpoints included response of IBD to treatment (improved, unchanged, or worsened, judged by the treating clinician, as well as endoscopic score) and liver-related outcomes.

RESULTS

In the entire cohort, the median serum level of ALP increased from 1.54-fold the upper limit of normal at baseline to 1.64-fold the upper limit of normal at the last follow-up examination (P = .018); serum levels of transaminases and bilirubin also increased by a small amount between baseline and the last follow-up examination. Serum levels of ALP decreased by 20% or more in 21 patients (20.6%); only the presence of cirrhosis (odds ratio, 4.48; P = .019) was independently associated with this outcome. Of patients with available endoscopic data, 56.8% had a response of IBD to treatment. Liver-related events occurred in 21 patients (20.6%), including bacterial cholangitis, cirrhosis decompensation, or transplantation.

CONCLUSIONS

In an analysis of patients with PSC and IBD in an international study group, we found no evidence for a biochemical response to vedolizumab, although serum level of ALP decreased by 20% or more in a subset of patients. Vedolizumab appears to be well tolerated and the overall response of IBD was the same as expected for patients without PSC.

Interferon-γ-dependent immune responses contribute to the pathogenesis of sclerosing cholangitis in mice

BACKGROUND AND AIMS

Primary sclerosing cholangitis (PSC) is an idiopathic, chronic cholestatic liver disorder characterized by biliary inflammation and fibrosis. Increased numbers of intrahepatic interferon-γ- (IFNγ) producing lymphocytes have been documented in patients with PSC, yet their functional role remains to be determined.

METHODS

Liver tissue samples were collected from patients with PSC. The contribution of lymphocytes to liver pathology was assessed in Mdr2-/- x Rag1-/- mice, which lack T and B cells, and following depletion of CD90.2+ or natural killer (NK)p46+ cells in Mdr2-/- mice. Liver pathology was also determined in Mdr2-/- x Ifng-/- mice and following anti-IFNγ antibody treatment of Mdr2-/- mice. Immune cell composition was analysed by multi-colour flow cytometry. Liver injury and fibrosis were determined by standard assays.

RESULTS

Patients with PSC showed increased IFNγ serum levels and elevated numbers of hepatic CD56bright NK cells. In Mdr2-/- mice, hepatic CD8+ T cells and NK cells were the primary source of IFNγ. Depletion of CD90.2+ cells reduced hepatic Ifng expression, NK cell cytotoxicity and liver injury similar to Mdr2-/- x Rag1-/- mice. Depletion of NK cells resulted in reduced CD8+ T cell cytotoxicity and liver fibrosis. The complete absence of IFNγ in Mdr2-/-x Ifng-/- mice reduced NK cell and CD8+ T cell frequencies expressing the cytotoxic effector molecules granzyme B and TRAIL and prevented liver fibrosis. The antifibrotic effect of IFNγ was also observed upon antibody-dependent neutralisation in Mdr2-/- mice.

CONCLUSION

IFNγ changed the phenotype of hepatic CD8+ T cells and NK cells towards increased cytotoxicity and its absence attenuated liver fibrosis in chronic sclerosing cholangitis. Therefore, unravelling the immunopathogenesis of PSC with a particular focus on IFNγ might help to develop novel treatment options.

LAY SUMMARY

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disease characterized by biliary inflammation and fibrosis, whose current medical treatment is hardly effective. We observed an increased interferon (IFN)-γ response in patients with PSC and in a mouse model of sclerosing cholangitis. IFNγ changed the phenotype of hepatic CD8+ T lymphocytes and NK cells towards increased cytotoxicity, and its absence decreased liver cell death, reduced frequencies of inflammatory macrophages in the liver and attenuated liver fibrosis. Therefore, IFNγ-dependent immune responses may disclose checkpoints for future therapeutic intervention strategies in sclerosing cholangitis.

In vivo 1 H MRS of human gallbladder bile in understanding the pathophysiology of primary sclerosing cholangitis (PSC): Immune-mediated disease versus bile acid-induced injury

Primary sclerosing cholangitis (PSC) has been considered to be either an "autoimmune disease" or a "bile acid-induced injury." In vitro MRS studies on PSC patients have limitations due to the contamination of bile with contrast agent (commonly administered during endoscopic retrograde cholangiopancreatography) and/or the use of patient cohorts with other diseases as controls. The objective of this study was to quantify biliary metabolites using in vivo ¹ H MRS and gain insight into the pathogenesis of PSC. Biliary metabolites in 10 PSC patients and 14 healthy controls were quantified in vivo using ¹ H MRS on a 3 T MR scanner. The concentrations of total bile acids plus cholesterol, glycine-conjugated bile acids, taurine-conjugated bile acids, and choline-containing phospholipids (chol-PLs) were compared between the two groups. There were statistically significant decreases in the levels of the above mentioned biliary metabolites in the PSC patients compared with controls. The reduction in bile acid secretion in bile of PSC patients indicates accumulation of bile acids in hepatocytes. Moreover, reduction in the levels of chol-PLs in bile may increase the toxic effects of bile acids. Our findings suggest that the bile duct injury in PSC patients is most likely due to "bile acid-induced injury."

Sclerosing Cholangitis Related to IgG4: Not Always a Curable Entity

IgG4-related disease is a recently-described fibro-inflammatory condition with characteristic histopathological findings in the organs involved. The most commonly affected organs are pancreas, lymph nodes, and retroperitoneum. Liver disease usually involves bile structures and therefore IgG4-related disease is considered a cause of secondary sclerosing cholangitis. One out of three patients with IgG4 sclerosing cholangitis also presents autoimmune pancreatitis, although it can be associated with manifestations in other organs. One of the main features of IgG4-related disease is its good prognosis due to the great response to glucocorticoid therapy. However, relapse of the disease is not uncommon, especially when steroid therapy is decreased or stopped. Rituximab seems to be an effective treatment to achieve remission of the disease. We report the case of a 74 year-old man diagnosed with IgG4-related disease based on increase of serum IgG4 levels, imaging and histopathological findings, with systemic involvement including sclerosing cholangitis. Despite the absence of liver fibrosis at onset, the early use of glucocorticoids and rituximab therapy, the patient presented clinical and analytical deterioration, leading to secondary biliary cirrhosis. In conclusion, this clinical case highlights the importance of prompt diagnosis and therapeutics for sclerosing cholangitis secondary to IgG4-related disease in order to avoid progression of the disease and development of liver cirrhosis, as well as the refractory, aggressive nature of the disease in some cases as this one.

Extrahepatic autoimmunity in autoimmune liver disease

The most important autoimmune liver disease include: autoimmune hepatitis, primary biliary cholangitis and primary sclerosing cholangitis. In general, about one in three patients with an autoimmune liver disease have a concomitant extrahepatic autoimmune disease, which may include rheumatological, endocrinological, gastrointestinal, pulmonary or dermatological conditions. The pathogenesis of these conditions includes the production of both innate and adaptive immune responses targeting cholangiocytes as well as different extrahepatic tissues. In this sense, extrahepatic autoimmunity represent a continuous spectrum of autoimmunity involving liver and extrahepatic tissues. This review aims to focus the clinical and pathophysiological aspects of extrahepatic autoimmunity associated to autoimmune liver diseases.

Immunoglobulin G4-related sclerosing cholangitis

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory condition of which IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation. In this review, we provide an overview of IgG4-RD, with a focus on the biliary manifestations. In particular, we describe the important differential diagnoses of IgG4-SC, namely, primary sclerosing cholangitis and cholangiocarcinoma, outline diagnostic criteria for IgG4-SC, provide insight into possible pathophysiological mechanisms underlying the disease and discuss short and long-term management options of this recently described disease.

Macrophages contribute to the pathogenesis of sclerosing cholangitis in mice

BACKGROUND & AIMS

Macrophages contribute to liver disease, but their role in cholestatic liver injury, including primary sclerosing cholangitis (PSC), is unclear. We tested the hypothesis that macrophages contribute to the pathogenesis of, and are therapeutic targets for, PSC.

METHODS

Immune cell profile, hepatic macrophage number, localization and polarization, fibrosis, and serum markers of liver injury and cholestasis were measured in an acute (intrabiliary injection of the inhibitor of apoptosis antagonist BV6) and chronic (Mdr2^-/- mice) mouse model of sclerosing cholangitis (SC). Selected observations were confirmed in liver specimens from patients with PSC. Because of the known role of the CCR2/CCL2 axis in monocyte/macrophage chemotaxis, therapeutic effects of the CCR2/5 antagonist cenicriviroc (CVC), or genetic deletion of CCR2 (Ccr2^-/- mice) were determined in BV6-injected mice.

RESULTS

We found increased peribiliary pro-inflammatory (M1-like) and alternatively-activated (M2-like) monocyte-derived macrophages in PSC compared to normal livers. In both SC models, genetic profiling of liver immune cells identified a predominance of monocytes/macrophages; immunohistochemistry confirmed peribiliary monocyte-derived macrophage recruitment (M1>M2-polarized), which paralleled injury onset and was reversed upon resolution in acute SC mice. PSC, senescent and BV6-treated human cholangiocytes released monocyte chemoattractants (CCL2, IL-8) and macrophage-activating factors in vitro. Pharmacological inhibition of monocyte recruitment by CVC treatment or CCR2 genetic deletion attenuated macrophage accumulation, liver injury and fibrosis in acute SC.

CONCLUSIONS

Peribiliary recruited macrophages are a feature of both PSC and acute and chronic murine SC models. Pharmacologic and genetic inhibition of peribiliary macrophage recruitment decreases liver injury and fibrosis in mouse SC. These observations suggest monocyte-derived macrophages contribute to the development of SC in mice and in PSC pathogenesis, and support their potential as a therapeutic target.

LAY SUMMARY

Primary sclerosing cholangitis (PSC) is an inflammatory liver disease which often progresses to liver failure. The cause of the disease is unclear and therapeutic options are limited. Therefore, we explored the role of white blood cells termed macrophages in PSC given their frequent contribution to other human inflammatory diseases. Our results implicate macrophages in PSC and PSC-like diseases in mice. More importantly, we found that pharmacologic inhibition of macrophage recruitment to the liver reduces PSC-like liver injury in the mouse. These exciting observations highlight potential new strategies to treat PSC.

Mucosal Autoimmunity to Cell-Bound GP2 Isoforms Is a Sensitive Marker in PSC and Associated With the Clinical Phenotype

Introduction: Zymogen granule glycoprotein 2 (GP2) was demonstrated as first autoimmune mucosal target in primary sclerosing cholangitis (PSC) associated with disease severity. Autoantibodies to four GP2 isoforms (aGP21-4) were found in patients with inflammatory bowel diseases but reactivity against specific GP2 epitopes has not been investigated in PSC yet. Hence, the prevalence of aGP21-4 and their association with the PSC phenotype for risk prediction were examined. Methods: GP2 isoforms were stably expressed as glycosylphosphatidyl - inositol-anchored molecules in the membrane of HEp-2 cells and used as autoantigenic targets in indirect immunofluorescence assay (IFA). aGP21-4 IgA and IgG were detected by IFA in 212 PSC patients of four European university hospitals and 145 controls comprising 95 patients with cystic fibrosis and 50 healthy subjects. Results: Combined aGP21 and aGP24 IgA testing with a sensitivity of 66.0% and a specificity of 97.9% resulted in the best diagnostic performance (Youden index: 0.64) regarding all aGP2 and combinations thereof. aGP24 IgA positivity is significantly associated with the presence of cirrhosis in PSC (p = 0.0056). Logistic regression revealed the occurrence of aGP21 IgA (odds ratio [OR] 1.38, 95% confidence interval [CI]: 1.03-1.86) and aGP24 IgA (OR 1.52, 95%CI: 1.07-2.15) along with male gender (OR 0.51, 95%CI: 0.27-0.97) and older age (OR 1.03 95%CI: 1.01-1.05) as significant risks for the concomitant presence of cirrhosis in PSC. Conclusions: Combined aGP21 and aGP24 IgA analysis is preferred to single aGP2 isoform analysis for sensitive PSC autoantibody testing. Positivity for aGP21 and aGP24 IgA is associated with cirrhosis in PSC and could be used for risk stratification.

A case report of immunoglobulin G4-related sclerosing cholangitis with multiple relapse

RATIONALE

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is classified as a biliary tract manifestation of immunoglobulin G4-related disease (IgG4-RD). Glucocorticoid is the first-line therapy for most patients, but the optimal starting dose, adequate maintaining dose and withdrawal time remain disputable.

PATIENT CONCERNS

An elderly male patient presented to our hospital with neoplasms of the bile duct and pancreas at first visit in December 2011. Further examination revealed bile duct stenosis and obstruction, and elevated serum IgG4 level.

DIAGNOSES

A diagnosis of IgG4-SC was established by examination results and effectiveness of steroid therapy, although IgG4-positive plasma cells were seldom seen in the liver sample.

INTERVENTIONS

Prednisolone was started from 40 mg daily, tapered gradually, and totally withdrawn after 22 months of treatment.

OUTCOMES

A new-onset cholangitis was detected 2 months later. Prednisolone 10 mg daily was administered again. Prednisolone was reduced to 5 mg every other day without consultation with his doctor 1 year ago in May 2017, then he presented to our hospital again with recurrent abdominal pain and jaundice.

LESSONS

IgG4-SC is a protean condition and can be distinguished from primary sclerosing cholangitis, malignancy, and other inflammatory disorders based on 4 clinical criteria. Serum IgG4/IgG1 ratio is a practicable diagnostic algorithm to distinguish PSC from IgG4-SC. The dose and duration of glucocorticoid for treatment should be adjusted according to clinical situations, and proper maintaining dose is essential for a better prognosis.

Biliary Tract Cancer: Implicated Immune-Mediated Pathways and Their Associated Potential Targets

There is a well-established link between biliary tract cancers (BTC) and chronic inflammatory conditions such as primary sclerosing cholangitis, chronic cholecystitis, chronic cholelithiasis, liver fluke-associated infestations, and chronic viral hepatic infections. These associated risk factors highlight the potential for development of immune-modulatory agents in this poor-prognostic disease group with limited treatment options. Clinical trials have evaluated the role of immune cells, inflammatory biomarkers, vaccines, cytokines, adoptive cell therapy, and immune checkpoint inhibitors in patients with BTC. Although these have demonstrated the importance of the immune environment in BTC, currently none of the immune-based therapies have been approved for use in this disease group. The role of immunomodulatory agents is a developing field and has yet to find its way 'from bench to bedside' in BTC.

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.

Autoimmune liver disease-related autoantibodies in patients with biliary atresia

AIM

To investigate the prevalence and clinical significance of autoimmune liver disease (ALD)-related autoantibodies in patients with biliary atresia (BA).

METHODS

Sera of 124 BA patients and 140 age-matched non-BA controls were assayed for detection of the following autoantibodies: ALD profile and specific anti-nuclear antibodies (ANAs), by line-blot assay; ANA and anti-neutrophil cytoplasmic antibody (ANCA), by indirect immunofluorescence assay; specific ANCAs and anti-M2-3E, by enzyme linked immunosorbent assay. Associations of these autoantibodies with the clinical features of BA (i.e., cytomegalovirus infection, degree of liver fibrosis, and short-term prognosis of Kasai procedure) were evaluated by Spearman’s correlation coefficient.

RESULTS

The overall positive rate of serum autoantibodies in preoperative BA patients was 56.5%. ALD profile assay showed that the positive reaction to primary biliary cholangitis-related autoantibodies in BA patients was higher than that to autoimmune hepatitis-related autoantibodies. Among these autoantibodies, anti-BPO was detected more frequently in the BA patients than in the controls (14.8% vs 2.2%, P < 0.05). Accordingly, 32 (25.8%) of the 124 BA patients also showed a high positive reaction for anti-M2-3E. By comparison, the controls had a remarkably lower frequency of anti-M2-3E (P < 0.05), with 6/92 (8.6%) of patients with other liver diseases and 2/48 (4.2%) of healthy controls. The prevalence of ANA in BA patients was 11.3%, which was higher than that in disease controls (3.3%, P < 0.05), but the reactivity to specific ANAs was only 8.2%. The prevalence of ANCAs (ANCA or specific ANCAs) in BA patients was also remarkably higher than that in the healthy controls (37.9% vs 6.3%, P < 0.05), but showed no difference from that in patients with other cholestasis. ANCA positivity was closely associated with the occurrence of postoperative cholangitis (r = 0.61, P < 0.05), whereas none of the autoantibodies showed a correlation to cytomegalovirus infection or the stages of liver fibrosis.

CONCLUSION

High prevalence of autoantibodies in the BA developmental process strongly reveals the autoimmune-mediated pathogenesis. Serological ANCA positivity may be a useful predictive biomarker of postoperative cholangitis.

Gut barrier failure biomarkers are associated with poor disease outcome in patients with primary sclerosing cholangitis

AIM

To assess the prevalence of a panel of serologic markers that reflect gut barrier dysfunction in a mixed cohort of pediatric and adult primary sclerosing cholangitis (PSC) patients.

METHODS

Sera of 67 PSC patients [median age (range): 32 (5-79) years, concomitant IBD: 67% and cirrhosis: 20%] were assayed for the presence of antibodies against to F-actin (AAA IgA/IgG) and gliadin (AGA IgA/IgG)] and for serum level of intestinal fatty acid-binding protein (I-FABP) by ELISA. Markers of lipopolysaccharide (LPS) exposure [LPS binding protein (LBP)] and various anti-microbial antibodies [anti-OMP Plus IgA and endotoxin core IgA antibody (EndoCAb)] were also determined. Poor disease outcome was defined as orthotopic liver transplantation and/or liver-related death during the follow-up [median: 99 (14-106) mo]. One hundred and fifty-three healthy subjects (HCONT) and 172 ulcerative colitis (UC) patients were the controls.

RESULTS

A total of 28.4%, 28.0%, 9% and 20.9% of PSC patients were positive for AAA IgA, AAA IgG, AGA IgA and AGA IgG, respectively. Frequencies of AAA IgA and AAA IgG (P < 0.001, for both) and AGA IgG (P = 0.01, for both) but not AGA IgA were significantly higher compared to both of the HCONT and the UC groups. In survival analysis, AAA IgA-positivity was revealed as an independent predictor of poor disease outcome after adjusting either for the presence of cirrhosis [HR = 5.15 (1.27-20.86), P = 0.022 or for the Mayo risk score (HR = 4.24 (0.99-18.21), P = 0.052]. AAA IgA-positivity was significantly associated with higher frequency of anti-microbial antibodies (P < 0.001 for EndoCab IgA and P = 0.012 for anti-OMP Plus IgA) and higher level of the enterocyte damage marker (median I-FABP_{AAA IgA posvsneg}: 365 vs 166 pg/mL, P = 0.011), but not with serum LBP level.

CONCLUSION

Presence of IgA type AAA identified PSC patients with progressive disease. Moreover, it is associated with enhanced mucosal immune response to various microbial antigens and enterocyte damage further highlighting the importance of the gut-liver interaction in PSC.

Comparative clinical characteristics and natural history of three variants of sclerosing cholangitis: IgG4-related SC, PSC/AIH and PSC alone

There is increased interest and recognition of the clinical variants of Sclerosing Cholangitis (SC) namely IgG4-SC, PSC/AIH overlap and PSC. For most Centers, the characteristic of IgG4-SC has not been thoroughly clinically compared with other sclerosing cholangitis variants. Further there are relatively few PSC/AIH overlap patients and the clinical outcome is not well characterized, especially for the PSC/AIH overlap syndrome. Our objective herein is to clarify the differences and similarities of the natural history of IgG4-SC, the PSC/AIH overlap and PSC alone. We also place in perspective the diagnostic value of serum IgG4 for IgG4-SC and investigate biomarkers for predicting the prognosis of sclerosing cholangitis. In this study, we took advantage of our large and well-defined patient cohort to perform a retrospective cohort study including 57 IgG4-SC, 36 PSC/AIH overlap patients, and 55 PSC patients. Firstly, as expected, we noted significant differences among immunoglobulin profiles and all patients exhibited similar cholestatic profiles at presentation. Cirrhotic events were found in 20 of total 57 IgG4-SC, 15 of 36 PSC/AIH overlap, and 18 of 55 PSC patients. Serum IgG4 was elevated in 92.65% of IgG4-SC patients with an 86% sensitivity and 98% specificity for diagnosis. IgG4-SC patients had a better treatment response at 6-month and 1-year than PSC/AIH patients, while the latter responded better with steroids than PSC patients. Importantly the adverse outcome-free survival of IgG4-SC patients was reduced, unlike earlier reports, and therefore similar to the PSC/AIH overlap syndrome. Serum IgG and total bilirubin were useful to predict long-term survival of IgG4-SC and PSC/AIH, respectively. In conclusion, serum IgG4≧1.25 ULN shows an excellent predictability to distinguish IgG4-SC among SC patients. IgG4-SC appears to be immune-mediated inflammatory process, while PSC/AIH overlap more tends to be cholestatic disease.

Pathogenesis and clinical spectrum of primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is a disease of the biliary tract, which has been documented in the literature since 1867. This disease has a strong predilection for affecting men and can be seen in individuals as young as 2 years of age. PSC has a strong associated with inflammatory bowel disease, more commonly with ulcerative colitis, and is also part of the clinical spectrum of IgG4-related diseases. Small-duct PSC, a variant of PSC, also has an association with inflammatory bowel disease. The exact pathogenesis of PSC is not well understood at present, however, is likely a combination of a genetic predisposition with alteration of the molecular structure of the gut. Abnormal serum liver chemistry and presence of certain autoimmune markers are usually the first indicators leading to a diagnosis of PCS, however, these may often be normal in early stages of this disease. The diagnosis is made by cholangiography, which is now considered the gold standard. PSC is a known pre-malignant condition. Such patients have an increased risk of developing cholangiocarcinoma, gallbladder neoplasia, and colon cancer. Many new treatment modalities have emerged in the recent past, including anti-tumor necrosis factor- α and anti-integrins; however, liver transplantation is the only known cure for PSC. Despite past and present research, PSC remains an enigmatic biliary disease with few viable treatment options.

ETS Proto-oncogene 1 Transcriptionally Up-regulates the Cholangiocyte Senescence-associated Protein Cyclin-dependent Kinase Inhibitor 2A

Primary sclerosing cholangitis (PSC) is a chronic, fibroinflammatory cholangiopathy (disease of the bile ducts) of unknown pathogenesis. We reported that cholangiocyte senescence features prominently in PSC and that neuroblastoma RAS viral oncogene homolog (NRAS) is activated in PSC cholangiocytes. Additionally, persistent microbial insult (e.g. LPSs) induces cyclin-dependent kinase inhibitor 2A (CDKN2A/p16INK4a) expression and senescence in cultured cholangiocytes in an NRAS-dependent manner. However, the molecular mechanisms involved in LPS-induced cholangiocyte senescence and NRAS-dependent regulation of CDKN2A remain unclear. Using our in vitro senescence model, we found that LPS-induced CDKN2A expression coincided with a 4.5-fold increase in ETS1 (ETS proto-oncogene 1) mRNA, suggesting that ETS1 is involved in regulating CDKN2A This idea was confirmed by RNAi-mediated suppression or genetic deletion of ETS1, which blocked CDKN2A expression and reduced cholangiocyte senescence. Furthermore, site-directed mutagenesis of a predicted ETS-binding site within the CDKN2A promoter abolished luciferase reporter activity. Pharmacological inhibition of RAS/MAPK reduced ETS1 and CDKN2A protein expression and CDKN2A promoter-driven luciferase activity by ∼50%. In contrast, constitutively active NRAS expression induced ETS1 and CDKN2A protein expression, whereas ETS1 RNAi blocked this increase. Chromatin immunoprecipitation-PCR detected increased ETS1 and histone 3 lysine 4 trimethylation (H3K4Me3) at the CDKN2A promoter following LPS-induced senescence. Additionally, phospho-ETS1 expression was increased in cholangiocytes of human PSC livers and in the Abcb4 (Mdr2)-/- mouse model of PSC. These data pinpoint ETS1 and H3K4Me3 as key transcriptional regulators in NRAS-induced expression of CDKN2A, and this regulatory axis may therefore represent a potential therapeutic target for PSC treatment.

Recent advances in IgG4-related disease, autoimmune pancreatitis and sclerosing cholangitis

Recently, a novel concept of IgG4-related disease (IgG4-RD), which shows increased serum IgG4/IgE levels, abundant infiltration of IgG4+plasmacytes and lymphocytes, fibrosis, and steroid responsiveness, has been worldwide accepted. The international consensus diagnostic criteria suggested the existence of two subtypes of autoimmune pancreatitis (AIP) : type 1 related with IgG4, and type 2 related with a granulocytic epithelial lesion. Before the IgG4-era, most of IgG4-SC cases were misdiagnosed as primary sclerosing cholangitis (PSC). Now, type 1 AIP and IgG4-sclerosing cholangitis (IgG4-SC) are defined as pancreatic and biliary manifestations of IgG4-RD, individually. Inflammatory bowel disease is often associated with type 2 AIP and PSC, but not Iwith type 1 or IgG4-SC. Steroid treatment is effective for IgG4-RD, but the long-term outcome still remains unclear.

To screen or not to screen? Celiac antibodies in liver diseases

Celiac disease (CD) is a systemic immune-mediated disorder triggered by dietary gluten in genetically predisposed individuals. The typical symptoms are anemia, diarrhea, fatigue, weight loss, and abdominal pain. CD has been reported in patients with primary sclerosing cholangitis, primary biliary cholangitis, autoimmune hepatitis, aminotransferase elevations, nonalcoholic fatty liver disease, hepatitis B, hepatitis C, portal hypertension and liver cirrhosis. We evaluate recommendations for active screening for CD in patients with liver diseases, and the effect of a gluten-free diet in these different settings. Active screening for CD is recommended in patients with liver diseases, particularly in those with autoimmune disorders, steatosis in the absence of metabolic syndrome, noncirrhotic intrahepatic portal hypertension, cryptogenic cirrhosis, and in the context of liver transplantation. In hepatitis C, diagnosis of CD can be important as a relative contraindication to interferon use. Gluten-free diet ameliorates the symptoms associated with CD; however, the associated liver disease may improve, remain the same, or progress.

The importance of IgG4 screening in patients diagnosed with primary sclerosing cholangitis in the past: A case rediagnosed as IgG4-SC after 10 years

RATIONALE

While primary sclerosing cholangitis (PSC) has been recognized for decades, immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) has been correctly diagnosed only in recent years. PSC and IgG4-SC show similar clinical symptoms, serologic markers, and imaging results, but the treatment strategies and prognosis of patients differ.

PATIENT CONCERNS

Here, we present the case report of a patient diagnosed with PSC for 10 years and rediagnosed with IgG4-SC recently, to emphasize the importance of screening serum IgG4 levels in patients with previous diagnosis of PSC.

DIAGNOSES

A 57-year-old woman with 10-year history of PSC was hospitalized due to pruritus. In 2004, the patient underwent cholecystectomy and cholangioenterostomy because of unexplained jaundice with pancreatic swelling. In the last 10 years, her liver enzyme levels were continuously elevated. The latest liver function profile showed elevated alanine aminotransferase, aspartate aminotransferase, and total bilirubin. IgG4 was 3.69 (0.03-2.01 g/L). Immunohistochemical staining of the surgical specimen showed >10 IgG4-positive plasma cells per high-power field, and IgG4+/IgG+ plasma cells >40%.

INTERVENTIONS AND OUTCOMES

She was treated with prednisone 40 mg once-daily and the dose was gradually tapered. The patient remains well after 18 months.

LESSONS SUBSECTIONS

Patients with IgG4-SC may be misdiagnosed as PSC due to lack of IgG4 screening. It is important to perform IgG4 screening in patients diagnosed as PSC. Steroid is effective to prevent disease progression in these patients.

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

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

Autoanti-C in a patient with primary sclerosing cholangitis and autoimmune hemolytic anemia: a rare presentation

Primary sclerosing cholangitis (PSC) is rarely associated with autoimmune hemolytic anemia (AIHA), and the presence of specific autoantibodies has not been reported previously. We present a unique case report of PSC associated with AIHA implicating autoanti-C. A 17-year-old girl was admitted to our hospital with PSC along with AIHA. Her blood sample demonstrated a positive direct antiglobulin test and a positive autocontrol in the antihuman globulin phase, confirming the patient had warm-reactive AIHA. Further testing showed the possibility of anti-C. The patient’s Rh phenotype was C+D+E–c–e+. Further testing with select cells, serial alloadsorption, and an elution confirmed anti-C specificity. The patient was transfused with two C–, crossmatch-compatible packed red blood cell units. The patient’s hemoglobin level and general condition showed improvement. This unique case report shows PSC associated with AIHA caused by autoanti-C. Usually, warm AIHA presents with a panreactive pattern, and it is difficult to find compatible blood. In this rare case, we could determine the specific antibody; efforts should always be made in cases of AIHA to identify the specificity of autoantibody.

IgG4-related sclerosing cholangitis: all we need to know

Our knowledge and experience of IgG4-related sclerosing cholangitis (ISC) have expanded in the last decade. ISC is one of the common organ manifestations of IgG4-related disease (IgG4-RD); approximately 60 % of patients with this systemic condition have ISC in the proximal and/or distal bile ducts. ISC needs to be discriminated from primary sclerosing cholangitis, cholangiocarcinoma, and other rare forms of lymphoplasmacytic cholangiopathy (e.g., follicular cholangitis and sclerosing cholangitis with granulocytic epithelial lesions). Its diagnosis requires a multidisciplinary approach, in which serology, histology, and imaging play crucial roles. Treatments with high-dose corticosteroids typically lead to the rapid and consistent induction of disease remission. Another promising therapeutic approach is B-cell depletion with rituximab. Although disease relapse is relatively common, provided that appropriate treatments are administered, ISC is considered a "benign" disease with a low risk of liver failure and biliary malignancy. Its molecular pathology is characterized by Th2-dominant immune reactions, regulatory T-cell activation, and CCL1-CCR8 interactions. Particular subsets of B cells such as plasmablasts and regulatory B cells also expand. A recent global proteomic study demonstrated that three significantly activated immunological cascades in ISC were all B-cell- or immunoglobulin-related (Fc-gamma receptor-mediated phagocytosis, B-cell receptor signaling pathway, and Fc-epsilon receptor I signaling pathway), suggesting the crucial roles of B cells in the underlying immune reactions. Despite the expansion of our knowledge of the pathophysiology of ISC, the exact role of IgG4 remains unclear. A better understanding of its immunopathology will offer some potential drug targets for this emerging biliary disease.

Comparison of the multidetector-row computed tomography findings of IgG4-related sclerosing cholangitis and extrahepatic cholangiocarcinoma

AIM

To compare the multidetector-row computed tomography (MDCT) findings of IgG4-related sclerosing cholangitis (IgG4-SC) and extrahepatic cholangiocarcinoma (EH-CCA).

MATERIALS AND METHODS

Two radiologists who had no knowledge of the patients' clinical information retrospectively evaluated the CT findings of patients with IgG4-SC (n=33) and EH-CCA (n=39) on a consensus basis. Another radiologist measured the biliary lesions. IgG4-SC was diagnosed using the Japan Biliary Association criteria (2012) or the Mayo Clinic's HISORt criteria. EH-CCA was diagnosed based on surgical findings.

RESULTS

Compared with EH-CCA, IgG4-SC exhibited the following findings significantly more frequently: (a) wall thickening alone, (b) concentric wall thickening, (c) smooth inner margins, (d) homogeneous attenuation in the arterial phase, (e) a lesion involving the intrapancreatic bile duct, (f) smooth outer margins, (g) fully visible lumen, (h) a funnel-shaped proximal bile duct, (i) skip lesions, and (j) abnormal pancreatic findings. Conversely, (k) dual-layered attenuation in all phases was significantly more common in EH-CCA. The specificity values of parameters (e-k) were >80%. Regarding dimensions, (l) the biliary lesions were longer in IgG4-SC than in EH-CCA. (m) The diameters of the dilated proximal common bile duct and (n) the dilated proximal intrahepatic bile duct were smaller in IgG4-SC than in EH-CCA.

CONCLUSION

A number of CT findings are useful for differentiating between IgG4-SC and EH-CCA. CT findings (e-k) are particularly useful for this purpose.

Using GWAS to identify genetic predisposition in hepatic autoimmunity

Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) represent the three major hepatic autoimmune conditions. Patient morbidity and mortality remain high across these three diseases, and an unmet need for rational therapy exists. Disease understanding has focused on combining clinical and laboratory based science to provide better insights into the joint host and environmental factors necessary for the initiation, and perpetuation, of hepato-biliary inflammation. Twin studies, family studies, population studies and an inter-relationship with other autoimmune phenomena suggest a genetic component to risk for each disease. Until recently, understanding of this genetic risk has been limited to HLA haplotypes. Associations with risk-conferring and protective HLA haplotypes are present in all three diseases. Over the last few years, genome-wide association studies (GWAS), and related genetic association studies, have greatly increased understanding of the genetic risk signature of these three diseases and autoimmunity in general. Here we consider the rationale for GWAS in general and with specific reference to hepatic autoimmunity. We consider the process of GWAS, and highlight major findings to date. Potential functional implications of key findings are discussed including the IL-12/STAT4 pathway in PBC and the CD28/IL-2 pathway in PSC. We describe the marked pleiotropy demonstrated by PBC and PSC, which is consistent with other autoimmune diseases. Further, we focus on specific gene associations including SH2B3, which is common to all three diseases, and FUT2 in PSC, which represents a link between environment and genetics. We review attempts to translate GWAS findings into basic laboratory models including in vivo systems and highlight where clinical observations relate to genetics. Finally we describe deficiencies in GWAS to date and consider future study of genetics in hepatic autoimmunity.

IgG4-Associated Cholangitis--A Mimic of PSC

IgG4-associated cholangitis (IAC) is an inflammatory disorder of the biliary tract representing a major manifestation of IgG4-related disease (IgG4-RD) often with elevation of serum IgG4 levels, infiltration of IgG4+ plasma cells in the affected tissue and good response to immunosuppressive treatment. Its first description may go back to 150 years ago. The clinical presentation of IAC is often misleading, mimicking other biliary diseases such as primary sclerosing cholangitis (PSC) or cholangiocarcinoma. The HISORt criteria--histopathological, imaging, and serological features (sIgG4), other organ manifestations of IgG4-RD and response to treatment--are the standard for the diagnosis of IAC. In this overview of a recent lecture, we summarize our original findings on IgG4-RD that (i) dominant IgG4+ B-cell clones identified by advanced next generation sequencing (NGS) are highly specific for IgG4-RD (meanwhile confirmed by others), are a highly accurate diagnostic marker to distinguish IgG4-RD from PSC and biliary/pancreatic malignancies and may be crucial in unravelling the pathophysiology of IgG4-RD; (ii) sIgG4/sIgG1 >0.24 have additional diagnostic value in comparison to sIgG4 in differentiating IAC from PSC; (iii) blood IgG4 mRNA is a highly accurate diagnostic marker comparable to NGS and may become an easily available and affordable diagnostic standard for distinguishing IgG4-RD from PSC and biliary/pancreatic malignancies; and (iv) 'blue collar work' with long-term exposure to solvents, paints, oil products or industrial gases may be a risk factor for development of IgG4-RD. These findings may contribute to the understanding of the pathophysiology and to the early diagnosis and adequate treatment of IgG4-RD.

Paediatric Autoimmune Liver Disease

In paediatrics, there are 2 liver disorders in which liver damage most likely stems from an autoimmune attack: 'classical' autoimmune hepatitis (AIH) and the AIH/sclerosing cholangitis overlap syndrome (also known as autoimmune sclerosing cholangitis, ASC). The presentation of childhood autoimmune liver disease (AILD) is non-specific and can mimic most other liver disorders. AIH is exquisitely responsive to immunosuppressive treatment, which should be instituted promptly to prevent rapid deterioration and promote remission and long-term survival. Difficult-to-treat or non-responsive patients should be treated with mycophenolate mofetil; if this fails then calcineurin inhibitors can be tried. Persistent failure to respond or lack of adherence to treatment result in end-stage liver disease. These patients, and those with fulminant liver failure at diagnosis, will require liver transplantation. ASC responds to the same immunosuppressive treatment used for AIH when treatment is initiated early. Abnormal liver function tests often resolve within a few months of treatment, although medium- to long-term prognosis is worse than that of AIH because bile duct disease continues to progress despite treatment in approximately 50% of patients. Ursodeoxycholic acid is usually added to conventional treatment regimen in ASC, but whether this actually helps arrest the progression of bile duct disease remains to be established. The pathogenesis of paediatric-onset AILD is not fully understood, although there is mounting evidence that genetic susceptibility, molecular mimicry and impaired immunoregulatory networks contribute to the initiation and perpetuation of the autoimmune attack. Liver damage is thought to be mediated primarily by CD4pos T-cells. While Th1 effector cells are associated with hepatocyte damage in both AIH and ASC, Th17 immune responses predominate in the latter where they correlate with biochemical indices of cholestasis, indicating that IL-17 is involved in the bile duct damage characteristic of this condition. Since a substantial difference between these 2 pathologies is the frequent association of ASC with inflammatory bowel disease, it can be speculated that lymphocytes of intestinal origin are present in patients with a diagnosis of ASC rather than in those with AIH. Animal models faithfully representing the human conditions are needed to unravel the contribution of innate and adaptive, effector and regulatory immune responses. A deeper understanding of the pathogenesis of AILD is likely to contribute to the development of novel treatments, such as the adoptive transfer of autologous expanded antigen-specific regulatory T-cells, which ultimately aim at restoring tolerance to liver-derived antigens.

Genetic Risk and the Development of Autoimmune Liver Disease

Primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH) have collectively been recognized as autoimmune liver diseases. They have all been subjected to genome-wide association studies (GWAS) and several dozens susceptibility loci have been determined. The predominant feature of the genetic findings is that of a strong association with the human leukocyte antigen (HLA) and numerous weak associations scattered throughout the remainder of the genome. The non-HLA associations show some degree of overlap, not only between PBC, PSC and AIH, but also with other autoimmune and immune-mediated diseases. Mathematical modelling shows that the main fraction of autoimmune disease risk (including that of autoimmune liver diseases) is not explained by GWAS, proposing a major role of environmental factors. The HLA associations and autoantibodies observed in these conditions may hold clues as to the nature of such factors, which are exceedingly difficult to map by means of epidemiological study designs. The present review article explores the potential relationship between genetic risk as determined by GWAS and environmental risk in autoimmune liver diseases, and proposes a model for relevant thinking on the susceptibility genes in PBC, PSC and AIH.

Regulatory T Cells in Hepatic Immune Tolerance and Autoimmune Liver Diseases

Regulatory T cells (Tregs) have a profound ability to control immune responses. A majority of Tregs are derived from the thymus; yet a substantial Treg fraction is derived from the periphery. The liver seems to be an important source of peripherally derived Tregs. Indeed, the liver's well-known ability to induce immune tolerance is at least partly based on hepatic Treg generation. With recently developed tools to deliver antigens to tolerance-inducing liver cells, it is now possible to harness liver-derived Tregs for specific control of unwanted immune responses. Indeed, the selective delivery of autoantigens to liver sinusoidal endothelial cells could induce autoantigen-specific Tregs in vivo, providing effective treatment of autoimmune disease. Owing to the fundamental role Tregs play in controlling immune responses, an impairment of Tregs seems to be a plausible explanation for the development of autoimmune diseases, for example, in the liver. However, the actual role of Treg impairment in autoimmune liver diseases, such as autoimmune hepatitis (AIH), remains controversial. Major obstacles for clarifying the role of Tregs in autoimmune liver diseases are related to the difficulty to identify human Tregs unambiguously and to the difficulty to identify those Tregs and effector T cells that specifically recognize disease-driving autoantigens. However, even if AIH turned out to be a disease that is not driven by Treg impairment, Treg-based therapies for autoimmune liver diseases might still be effective, provided the Tregs for therapeutic use recognize the relevant antigens.

Extensive Metastatic Cholangiocarcinoma Associated With IgG4-Related Sclerosing Cholangitis Misdiagnosed as Isolated IgG4-Related Sclerosing Cholangitis: A Case Report and Literature Review

As cholangiographic features of IgG4-related sclerosing cholangitis (IgG4-SC) resemble those of cholangiocarcinoma, it is highly confusing between the 2 conditions on the basis of cholangiographic findings. This study presents a case of extensive metastatic cholangiocarcinoma with IgG4-SC misdiagnosed as isolated IgG4-SC, and reviews recent studies of the 2 diseases.A 56-year-old man with no family history of malignant tumors or liver diseases presented with recurrent mild abdominal pain and distention for 3 months. Magnetic resonance cholangiopancreatography showed a 3.7 cm nodular lesion with unclear boundary in segment VI of the liver. Serum IgG4 and CA19-9 were slightly elevated. Histopathological examination was consistent with the consensus statement on the pathology of IgG4-SC. IgG4-SC was thus considered. Due to his mild symptoms, glucocorticoid was not given at first. However, 3 months after his first admission, he had more severe abdominal pain and further elevated serum CA19-9. Actually he was found suffering from extensive metastatic cholangiocarcinoma with IgG4-SC by exploratory laparotomy.The present case serves as a reminder that extensive metastatic cholangiocarcinoma with or without IgG4-SC may be misdiagnosed as an isolated IgG4-SC case if one relies solely on elevated serum and tissue IgG4 levels. We emphasize on the importance of repeated core needle biopsy or exploratory laparoscopy/laparotomy before immunosuppressive drugs are given, and on follow-up of imaging findings and serum CA19-9 once immunosuppressive therapy is started.

Membranous Nephropathy Associated With Immunological Disorder-Related Liver Disease: A Retrospective Study of 10 Cases

The association between membranous nephropathy (MN) and immunological disorder-related liver disease has not been extensively investigated, and the specific features of this uncommon association, if any, remain to be determined.We retrospectively identified 10 patients with this association. We aimed to describe the clinical, biological, and pathological characteristics of these patients and their therapeutic management. The possible involvement of the phospholipase A2 receptor (PLA2R) in these apparent secondary forms of MN was assessed by immunohistochemistry with renal and liver biopsy specimens.The mean delay between MN and liver disease diagnoses was 3.9 years and the interval between the diagnosis of the glomerular and liver diseases was <1.5 years in 5 patients. MN was associated with a broad spectrum of liver diseases including primary biliary cirrhosis (PBC), autoimmune hepatitis (AIH), and primary sclerosing cholangitis (PSC). AIH whether isolated (n = 3) or associated with PBC (n = 2) or PSC (n = 2) was the most frequent autoimmune liver disease. Circulating PLA2R antibodies were detected in 4 out of 9 patients but the test was performed under specific immunosuppressive treatment in 3 out of 9 patients. Seven of the 9 patients with available renal tissue specimens displayed enhanced expression of PLA2R in glomeruli whereas PLA2R was not expressed in liver parenchyma from these patients or in normal liver tissue. The study of immunoglobulin (Ig) subclasses of deposits in glomeruli revealed that the most frequent pattern was the coexistence of IgG1 and IgG4 immune deposits with IgG4 predominating.Detection of PLA2R antibodies in glomeruli but not in liver parenchyma is a common finding in patients with MN associated with autoimmune liver disease, suggesting that these autoantibodies are not exclusively detected in idiopathic MN.

Fucosyltransferase 2: a genetic risk factor for primary sclerosing cholangitis and Crohn's disease--a comprehensive review

Fucosyltransferase 2 (FUT2) mediates the inclusion of fucose in sugar moieties of glycoproteins and glycolipids. ABO blood group antigens and host-microbe interactions are influenced by FUT2 activity. About 20 % of the population has a "non-secretor" status caused by inactivating variants of FUT2 on both alleles. The non-sense mutation G428A and the missense mutation A385T are responsible for the vast majority of the non-secretor status in Caucasians, Africans, and Asians, respectively. Non-secretor individuals do not secrete fucose-positive antigens and lack fucosylation in epithelia. They also appear to be protected against a number of infectious diseases, such as Norovirus and Rotavirus infections. In recent years, genome-wide association studies (GWAS) identified inactivating variants at the FUT2 locus to be associated with primary sclerosing cholangitis (PSC), Crohn's disease (CD), and biochemical markers of biliary damage. These associations are intriguing given the important roles of fucosylated glycans in host-microbe interactions and membrane stability. Non-secretors have a reduced fecal content of Bifidobacteria. The intestinal bacterial composition of CD patients resembles the one of non-secretors, with an increase in Firmicutes and decreases in Proteobacteria and Actinobacteria. Non-secretor individuals lack fucosylated glycans at the surface of biliary epithelium and display a different bacterial composition of bile compared to secretors. Notably, an intact biliary epithelial glycocalix is relevant for a stable 'biliary HCO3 (-) umbrella' to protect against toxic effects of hydrophobic bile salt monomers. Here, the biology of FUT2 will be discussed as well as hypotheses to explain the role of FUT2 in the pathophysiology of PSC and Crohn's disease.

Childhood Autoimmune Hepatitis in Bahrain: a Tertiary Center Experience

BACKGROUND

Autoimmune hepatitis (AIH) in childhood has variable modes of presentation, and the disease should be suspected and excluded in all children presenting with symptoms and signs of prolonged or severe acute liver disease. In AIH, the liver biopsy histopathology shows inflammation in addition to presence of serum autoimmune antibodies and increased levels of immunoglobulin G (IgG).

OBJECTIVES

To investigate the situation of childhood autoimmune hepatitis in Bahrain and to compare it with other studies worldwide.

METHODS

A retrospective study describing the AIH pediatric cases diagnosed during the period of Jan 2005 to Dec 2009. We report the clinical, biochemical, histopathological, and immunological findings, mainly autoimmune profile, in addition to response to treatment, of Bahraini children with autoimmune hepatitis.

RESULTS

Five Bahraini children, three females and two males were diagnosed as autoimmune hepatitis during the study period. Their ages at presentation ranged from 9 to 15 (median 10.6) years. One of our patients had a fulminating type. Two had other autoimmune related conditions, namely autoimmune sclerosing cholangitis and ulcerative colitis. All were AIH type 1. Variable response to conventional immunosuppressive therapy was found, from an excellent response with good prognosis, to cirrhosis, hepatic failure and liver transplantation.

CONCLUSION

Childhood AIH is a rare medical problem in Bahrain, with both sexes affected and a variable response to immunosuppressive therapy.

Rare case of Helicobacter pylori-positive multiorgan IgG4-related disease and gastric cancer

A 61-year-old male from Northeast China presented with a 2-mo history of abdominal distension, pruritus and jaundice. Laboratory testing revealed an elevated serum IgG4 level. A computed tomography scan showed a typical feature of autoimmune pancreatitis (AIP) and cholecystocholangitis. Early gastric cancer was incidentally discovered when endoscopic untrasound-guided fine needle aspiration (EUS-FNA) of the pancreas was carried out. The patient underwent radical subtotal gastrectomy for gastric cancer combined with cholecystectomy. Helicobacter pylori (H. pylori) and IgG4-positive plasmacytes were detected in gastric cancer tissue, pancreatic EUS-FNA sample and resected gallbladder specimen by immunohistochemistry. The patient was diagnosed with H. pylori-positive IgG4-related AIP and sclerosing cholecystocholangitis as well as H. pylori-positive gastric cancer. He responded well to steroid therapy and remains healthy with no signs of recurrence at one year follow-up. We speculate that H. pylori might act as a trigger via direct or indirect action in the initiation of onset of gastric cancer and multiorgan IgG4-related disease.

Histopathological diagnostic value of the IgG4+/IgG+ ratio of plasmacytic infiltration for IgG4-related diseases: a PRISMA-compliant systematic review and meta-analysis

This article aims to perform a meta-analysis to evaluate the diagnostic value of the immunoglobulin G (IgG)4/IgG ratio of plasmacytic infiltration for IgG4-related diseases.Four databases-EMBASE, ISI Web of Knowledge, PubMed, and the Cochrane Library-were systematically searched. Approximately 200 participants from several studies were included in this research. STATA 11.2 software (Stata Corporation, College Station, TX) and Meta-DiSc 1.4 (Unit of Clinical Biostatistics, Ramon y Cajal Hospital, Madrid, Spain) were used to perform the meta-analysis.Nine studies were included in the meta-analysis. The pooled diagnostic odds ratio was 18.94 [95% confidence interval (CI), 2.89-124.30]. The sensitivity was 58.80% (95% CI, 50.90-66.30) and the specificity was 90.20% (95% CI, 81.20-95.80). The positive and negative likelihood ratios were 3.12 (95% CI, 1.07-9.16) and 0.26 (95% CI, 0.09-0.70), respectively. The area under the curve of the summary receiver-operating characteristic was 0.88.To conclude, the IgG4/IgG ratio of plasmacytic infiltration is modestly effective in diagnosing IgG-related disease.

Increased IgG4 responses to multiple food and animal antigens indicate a polyclonal expansion and differentiation of pre-existing B cells in IgG4-related disease

Background

IgG4-related disease (IgG4-RD) is a systemic fibroinflammatory condition, characterised by an elevated serum IgG4 concentration and abundant IgG4-positive plasma cells in the involved organs. An important question is whether the elevated IgG4 response is causal or a reflection of immune-regulatory mechanisms of the disease.

Objectives

To investigate if the IgG4 response in IgG4-RD represents a generalised polyclonal amplification by examining the response to common environmental antigens.

Methods

Serum from 24 patients with IgG4-RD (14 treatment-naive, 10 treatment-experienced), 9 patients with primary sclerosing cholangitis and an elevated serum IgG4 (PSC-high IgG4), and 18 healthy controls were tested against egg white and yolk, milk, banana, cat, peanut, rice and wheat antigens by radioimmunoassay.

Results

We demonstrated an elevated polyclonal IgG4 response to multiple antigens in patients with IgG4-RD and in PSC-high IgG4, compared with healthy controls. There was a strong correlation between serum IgG4 and antigen-specific responses. Responses to antigens were higher in treatment-naive compared with treatment-experienced patients with IgG4-RD. Serum electrophoresis and immunofixation demonstrated polyclonality.

Conclusions

This is the first study to show enhanced levels of polyclonal IgG4 to multiple antigens in IgG4-RD. This supports that elevated IgG4 levels reflect an aberrant immunological regulation of the overall IgG4 response, but does not exclude that causality of disease could be antigen-driven.

Isolated intrapancreatic IgG4-related sclerosing cholangitis

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is frequently associated with type 1 autoimmune pancreatitis (AIP). Association with AIP can be utilized in the diagnosis of IgG4-SC. However, some cases of IgG4-SC are isolated from AIP, which complicates the diagnosis. Most of the reported cases of isolated IgG4-SC displayed hilar biliary strictures, whereas isolated IgG4-SC with intrapancreatic biliary stricture is very rare. Recently, we have encountered 5 isolated intrapancreatic IgG4-SC cases that were not associated with AIP, three of which were pathologically investigated after surgical operation. They all were males with a mean age of 74.2 years. The pancreas was not enlarged in any of these cases. No irregular narrowing of the main pancreatic duct was found. Bile duct wall thickening in lesions without luminal stenosis was detected by abdominal computed tomography in all five cases, by endoscopic ultrasonography in two out of four cases and by intraductal ultrasonography in all three cases. In three cases, serum IgG4 levels were within the normal limits. The mean serum IgG4 level measured before surgery was 202.1 mg/dL (4 cases). Isolated intrapancreatic IgG4-SC is difficult to diagnose, especially if the IgG4 level remains normal. Thus, this type of IgG4-SC should be suspected in addition to cholangiocarcinoma and pancreatic cancer if stenosis of intrapancreatic bile duct is present.

Biliary and hepatic involvement in IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a multi-systemic disorder. IgG4-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the disease, often in association with autoimmune pancreatitis (AIP). Hepatic manifestations of IgG4-RD are less well described within the literature.

AIM

To examine and present an overview of IgG4-RD with a focus on the biliary and hepatic manifestations.

METHODS

An electronic search using Medline was performed. Search items included 'IgG4 multi-system disease, IgG4 associated cholangitis, IgG4 associated liver disease and autoimmune pancreatitis (AIP)'.

RESULTS

IgG4-RD is characterised by an IgG4-positive lymphoplasmacytic tissue infiltrate, storiform fibrosis and an obliterative phlebitis. The HISORt criteria may be used to establish the diagnosis and incorporate a multi-disciplinary approach involving histology, radiology, serum IgG4 levels and response to steroid therapy. IgG4-SC is the commonest extrapancreatic manifestation of type-1 AIP, while the hepatic manifestations remain poorly defined. Important differential diagnoses include primary sclerosing cholangitis, secondary sclerosing cholangitis, cholangiocarcinoma and pancreatic carcinoma. Current treatment regimens remain ill defined although steroid therapy is used first line unless contraindicated. Patients with relapsing disease or multifocal disease should be considered for azathioprine. Available data would also suggest a role for rituximab.

CONCLUSIONS

IgG4-related sclerosing cholangitis is a common manifestation of IgG4-related disease which requires a multi-disciplinary approach to establish the diagnosis. Differentiating IgG4-related sclerosing cholangitis from other conditions, both benign and malignant, is challenging, but vital. Steroids remain the mainstay of treatment. Our understanding of the pathogenesis of the hepatic manifestations of IgG4-related disease continues to evolve.