Identification of a novel antibody associated with autoimmune pancreatitis

Recent concepts of autoimmune pancreatitis and IgG4-related disease

Recent studies suggested the existence of two subtypes of autoimmune pancreatitis (AIP): type 1 related with IgG4 (lymphoplasmacytic sclerosing pancreatitis; LPSP) and type 2 related with a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis; IDCP). Apart from type 2 AIP, the pathological features of type 1 AIP with increased serum IgG4/IgE levels, abundant infiltration of IgG4+ plasmacytes and lymphocytes, fibrosis, and steroid responsiveness are suggestive of abnormal immunity such as allergy or autoimmunity. Moreover, the patients with type 1 AIP often have extrapancreatic lesions such as sclerosing cholangitis, sclerosing sialadenitis, or retroperitoneal fibrosis showing similar pathological features. Based on these findings, many synonyms have been proposed for these conditions, such as "multifocal idiopathic fibrosclerosis", "IgG4-related autoimmune disease", "IgG4-related sclerosing disease", "IgG4-related plasmacytic disease", and "IgG4-related multiorgan lymphoproliferative syndrome", all of which may refer to the same conditions. Therefore, the Japanese Research Committee for "Systemic IgG4-related Sclerosing Disease" proposed a disease concept and clinical diagnostic criteria based on the concept of multifocal fibrosclerosis in 2009, in which the term "IgG4-related disease" was appointed as a minimal consensus on these conditions. Although the significance of IgG4 in the development of "IgG4-related disease" remains unclear, we have proposed a hypothesis for the development of type 1 AIP, one of the IgG4-related disease. The concept and diagnostic criteria of "IgG4-related disease" will be changed in accordance with future studies.

A case of IgG4-related tubulointerstitial nephritis with left hydronephrosis after a remission of urinary tract tuberculosis

IgG4-related systemic disease encompasses multi-organ disorders, including tubulointerstitial nephritis. This disease is accompanied by a high serum IgG4 concentration and IgG4-positive plasma cell infiltration. We herein describe a 63-year-old woman with renal failure and dryness of the eyes and mouth, who had been treated with antituberculosis agents for urinary tract tuberculosis. She had a negative finding for a PCR analysis for Mycobacterium tuberculosis, a positive QuantiFERON-TB test, high serum IgG4 concentrations (2,660 mg/dl), and low serum IgM and IgA concentrations (34 and 82 mg/dl, respectively). Imaging tests revealed swelling in the submandibular glands, pancreas, and right kidney. A renal biopsy showed IgG4-positive plasma cell infiltration in the interstitium and tubular atrophy. This case was diagnosed as IgG4-related systemic disease. Corticosteroid therapy improved renal failure and swelling in the submandibular glands, pancreas, and right kidney. The case suggests that an abnormal reaction to tuberculosis may be associated with a predominance of type-2 helper T-cell immunity, thus resulting in IgG4-related systemic disease.

IgG4 Cholangiopathy

IgG4 cholangiopathy can involve any level of the biliary tree which exhibits sclerosing cholangitis or pseudotumorous hilar lesions. Most cases are associated with autoimmune pancreatitis, an important diagnostic clue. Without autoimmune pancreatitis, however, the diagnosis of IgG4-cholangiopathy is challenging. Indeed such cases have been treated surgically. IgG4-cholangiopathy should be diagnosed based on serological examinations including serum IgG4 concentrations, radiological features, and histological evidence of IgG4(+) plasma cell infiltration. Steroid therapy is very effective even at disease relapse. A Th2-dominant immune response or the activation of regulatory T cells seems to be involved in the underlying immune reaction. It is still unknown why IgG4 levels are specifically elevated in patients with this disease. IgG4 might be secondarily overexpressed by Th2 or regulatory cytokines given the lack of evidence that IgG4 is an autoantibody.

IgG4-related sclerosing disease, an emerging entity: a review of a multi-system disease

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a recently defined emerging entity characterized by a diffuse or mass forming inflammatory reaction rich in IgG4-positive plasma cells associated with fibrosclerosis and obliterative phlebitis. IgG4-RSD usually affects middle aged and elderly patients, with a male predominance. It is associated with an elevated serum titer of IgG4, which acts as a marker for this recently characterized entity. The prototype is IgG4-related sclerosing pancreatitis or autoimmune pancreatitis (AIP). Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, however practically any organ can be involved, including upper aerodigestive tract, lung, aorta, mediastinum, retroperitoneum, soft tissue, skin, central nervous system, breast, kidney, and prostate. Fever or constitutional symptoms usually do not comprise part of the clinical picture. Laboratory findings detected include raised serum globulin, IgG and IgG4. An association with autoantibody detection (such as antinuclear antibodies and rheumatoid factor) is seen in some cases. Steroid therapy comprises the mainstay of treatment. Disease progression with involvement of multiple organ-sites may be encountered in a subset of cases and may follow a relapsing-remitting course. The principal histopathologic findings in several extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, along with atrophy and destruction of tissues. Immunohistochemical staining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). IgG4-RSD may potentially be rarely associated with the development of lymphoma and carcinoma. However, the nature and pathogenesis of IgG4-RSD are yet to be fully elucidated and provide immense scope for further studies.

Type 1 autoimmune pancreatitis

Before the concept of autoimmune pancreatitis (AIP) was established, this form of pancreatitis had been recognized as lymphoplasmacytic sclerosing pancreatitis or non-alcoholic duct destructive chronic pancreatitis based on unique histological features. With the discovery in 2001 that serum IgG4 concentrations are specifically elevated in AIP patients, this emerging entity has been more widely accepted. Classical cases of AIP are now called type 1 as another distinct subtype (type 2 AIP) has been identified. Type 1 AIP, which accounts for 2% of chronic pancreatitis cases, predominantly affects adult males. Patients usually present with obstructive jaundice due to enlargement of the pancreatic head or thickening of the lower bile duct wall. Pancreatic cancer is the leading differential diagnosis for which serological, imaging, and histological examinations need to be considered. Serologically, an elevated level of IgG4 is the most sensitive and specific finding. Imaging features include irregular narrowing of the pancreatic duct, diffuse or focal enlargement of the pancreas, a peri-pancreatic capsule-like rim, and enhancement at the late phase of contrast-enhanced images. Biopsy or surgical specimens show diffuse lymphoplasmacytic infiltration containing many IgG4⁺ plasma cells, storiform fibrosis, and obliterative phlebitis. A dramatic response to steroid therapy is another characteristic, and serological or radiological effects are normally identified within the first 2 or 3 weeks. Type 1 AIP is estimated as a pancreatic manifestation of systemic IgG4-related disease based on the fact that synchronous or metachronous lesions can develop in multiple organs (e.g. bile duct, salivary/lacrimal glands, retroperitoneum, artery, lung, and kidney) and those lesions are histologically identical irrespective of the organ of origin. Several potential autoantigens have been identified so far. A Th2-dominant immune reaction and the activation of regulatory T-cells are assumed to be involved in the underlying immune reaction. IgG4 antibodies have two unique biological functions, Fab-arm exchange and a rheumatoid factor-like activity, both of which may play immune-defensive roles. However, the exact role of IgG4 in this disease still remains to be clarified. It seems important to recognize this unique entity given that the disease is treatable with steroids.

Graves'-like orbitopathy in a patient with chronic autoimmune pancreatitis

BACKGROUND

Graves' orbitopathy is an inflammatory orbital disease that represents the commonest extrathyroidal manifestation of Graves' disease. Autoimmune pancreatitis (AIP) is a rare inflammatory disease characterized by prominent lymphocytic infiltration and fibrosis of the pancreas causing organ dysfunction.

SUMMARY

This report provides the first clinical description of severe Graves'-like orbitopathy occurring in association with AIP. Although there was no clear evidence of autoimmune thyroid disease or dysfunction in our patient, the clinical course of his orbitopathy was related to that of AIP, the relapses of orbital inflammation being temporally coincident.

CONCLUSIONS

Our data suggest that shared autoantigens between the pancreas and the orbit might be responsible for the unusual disorder observed in our patient.

Autoimmune pancreatitis versus pancreatic cancer: a comprehensive review with emphasis on differential diagnosis

BACKGROUND

Autoimmune pancreatitis (AIP) is a rare form of chronic pancreatitis with a discrete pathophysiology, occasional diagnostic radiological findings, and characteristic histological features. Its etiology and pathogenesis are still under investigation, especially during the last decade. Another aspect of interest is the attempt to establish specific criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer, entities that are frequently indistinguishable.

DATA SOURCES

An extensive search of the PubMed database was performed with emphasis on articles about the differential diagnosis between autoimmune pancreatitis and pancreatic cancer up to the present.

RESULTS

The most interesting outcome of recent research is the theory that autoimmune pancreatitis and its various extra-pancreatic manifestations represent a systemic fibro-inflammatory process called IgG4-related systemic disease. The diagnostic criteria proposed by the Japanese Pancreatic Society, the more expanded HISORt criteria, the new definitions of histological types, and the new guidelines of the International Association of Pancreatology help to establish the diagnosis of the disease types.

CONCLUSION

The valuable help of the proposed criteria for the differential diagnosis between autoimmune pancreatitis and pancreatic cancer may lead to avoidance of pointless surgical treatments and increased patient morbidity.

[IgG4-related systemic disease: emergence of a new systemic disease? Literature review]

Hyper-IgG4 syndrome, or IgG4-related systemic disease (IgG4-RSD), has been recently characterized by the association of a focal or diffuse enlargement in one or more organs, elevated levels of serum IgG4 and histopathological findings including "storiform" fibrosis and prominent infiltration of lymphocytes and IgG4-positive plasma cells. Pancreas was the first organ involved with sclerosing pancreatitis (or autoimmune pancreatitis). Since this first description, many extrapancreatic lesions have been described, even in the absence of pancreatitis and include sialadenitis, lacrimal gland inflammation, lymphadenopathy, aortitis, sclerosing cholangitis, tubulointerstitial nephritis, retroperitoneal fibrosis or inflammatory pseudotumors. Multiorgan lesions can occur synchronously or metachronously in a same patient, usually after 50 years of age. They all share common histopathological findings. The disease often responds well to corticosteroid therapy. In this literature review on IgG4-RSD, we present historical, epidemiological and clinical characteristics, and we review the biological and histological diagnostic criteria. To date there is no international validated diagnostic criteria. Pathophysiological hypothesis and therapeutic approaches are also discussed.

Differentiation of autoimmune pancreatitis from pancreas cancer: utility of anti-amylase and anti-carbonic anhydrase II autoantibodies

Purpose

To investigate the utility of different combinations of serum anti-carbonic anhydrase II antibodies (CA II Abs), anti-α amylase antibodies (AMY-α Abs) and IgG4 levels for the diagnosis of autoimmune pancreatitis (AIP).

Methods

We recruited 93 patients with clinical suspicion for AIP and 94 patients as control groups between June 2003 and October 2009. Serum antibodies were measured using homemade enzyme linked immunosorbent assay and IgG4 levels were determined by nephelometry.

Results

Both CA-II Abs and AMY-α Abs had the highest sensitivity (83%) although AMY-α Abs (89%) were more specific than CA-II Abs (75%). The presence of increased IgG4 levels was the most specific serological marker (94%), but it had the lowest sensitivity (58%). The combination of the three serological markers altogether had the highest specificity (99%) and positive predictive value (PPV) (86%), but they had a rather low sensitivity (50%). When we combined CA-II Abs and AMY-α Abs without IgG4 levels, we got the highest sensitivity (75%) and negative predictive value (98%) but the specificity and the PPV decreased to 93 and 50%, respectively. Importantly, AMY-α Abs were not detected in pancreas cancer.

Conclusions

The presence of serum CA-II and AMY-α Abs with increased IgG4 is useful in the differential diagnosis of AIP from pancreatic cancer.

An unusual case of autoimmune pancreatitis presenting as pancreatic mass and obstructive jaundice: a case report and review of the literature

Background

Autoimmune pancreatitis is a rare chronic inflammatory pancreatic disease that is increasingly being diagnosed worldwide. As a result of overlap in clinical and radiological features, it is often misdiagnosed as pancreatic cancer. We report the case of a patient with autoimmune pancreatitis that was initially misdiagnosed as pancreatic cancer.

Case presentation

A 31-year-old Caucasian man presented to our hospital with epigastric pain, jaundice and weight loss. His CA 19-9 level was elevated, and computed tomography and endoscopic ultrasound revealed a pancreatic head mass abutting the portal vein. Endoscopic retrograde cholangiopancreaticography showed narrowing of the biliary duct and poor visualization of the pancreatic duct. Fine-needle aspiration biopsy revealed atypical ductal epithelial cells, which raised clinical suspicion of adenocarcinoma. Because of the patient's unusual age for the onset of pancreatic cancer and the acuity of his symptoms, he was referred to a tertiary care center for further evaluation. His immunoglobulin G4 antibody level was 365 mg/dL, and repeat computed tomography showed features typical of autoimmune pancreatitis. The patient's symptoms resolved with corticosteroid therapy.

Conclusion

Autoimmune pancreatitis is a rare disease with an excellent response to corticosteroid therapy. Its unique histological appearance and response to corticosteroid therapy can reduce unnecessary surgical procedures. A thorough evaluation by a multidisciplinary team is important in rendering the diagnosis of autoimmune pancreatitis.

Management strategies for autoimmune pancreatitis

INTRODUCTION

Autoimmune pancreatitis (AIP) is a newly developed concept for a peculiar type of pancreatitis, and at present is recognized as a pancreatic lesion reflecting IgG4-related systemic disease. It is of utmost importance to differentiate AIP from pancreatic cancer to avoid unnecessary surgery.

AREAS COVERED

The current management strategies for AIP, including its clinical features, diagnostic criteria, clinical subtypes, steroid therapy and prognosis are discussed, based on our 66 AIP cases and papers searched in PubMed from 1992 to March 2011, using the term 'autoimmune pancreatitis'. A new clinicopathological entity, an 'IgG4-related sclerosing disease' is also mentioned.

EXPERT OPINION

AIP should be considered in the differential diagnosis in elderly male patients presented with obstructive jaundice and pancreatic mass. Steroids are a standard therapy for AIP, but their regimen including maintenance therapy should be evaluated in prospective trials.

Are dysregulated inflammatory responses to commensal bacteria involved in the pathogenesis of hepatobiliary-pancreatic autoimmune disease? An analysis using mice models of primary biliary cirrhosis and autoimmune pancreatitis

The etiopathogenesis of many autoimmune disorders has not been identified. The aim of this paper is to focus on the involvement of bacterial exposure in the pathogenesis of primary biliary cirrhosis (PBC) and autoimmune pancreatitis (AIP), both of which are broadly categorized as autoimmune disorders involving hepatobiliary-pancreatic lesions. Avirulent and/or commensal bacteria, which may have important role(s) as initiating factors in the pathogenesis of autoimmune disorders such as PBC and AIP, will be emphasized.

Ductal Adenocarcinoma of the Pancreas

Pancreatic ductal adenocarcinoma (PDAC) and its variants comprise between 80% and 90% of all tumors of the exocrine pancreas. Because of its silent course, late clinical manifestation, and rapid growth, it is considered a silent killer. Only 10% to 15% of cases are resectable and the 5-year survival rate remains lower than 5%. The differential diagnosis between PDAC and chronic pancreatitis is a challenge for pathologists. This article provides a guide for pathologic evaluation of PDAC specimens with the macroscopic and microscopic features of common PDAC and its variants and discusses the differential diagnosis and morphologic and immunophenotypical prognostic parameters.

Autoimmune pancreatitis: pancreatic and extrapancreatic MR imaging-MR cholangiopancreatography findings at diagnosis, after steroid therapy, and at recurrence

PURPOSE

To determine and describe the magnetic resonance (MR) imaging-MR cholangiopancreatographic pancreatic and extrapancreatic findings of autoimmune pancreatitis (AIP) and the probability, site, and MR features of recurrent AIP after steroid therapy.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, and the requirement for informed patient consent was waived. The data of 27 patients with AIP were included in the study. All patients had undergone MR imaging with MR cholangiopancreatography before and after steroid treatment and during follow-up (median follow-up period, 45 months). Image analysis included assessment of pancreatic parenchyma enlargement, signal intensity on T1- and T2-weighted MR images, contrast enhancement, and presence of bile duct and/or renal involvement. The probability of AIP recurrence was assessed by using Kaplan-Meier curves and the unadjusted Cox model.

RESULTS

At the time of diagnosis, the AIP-affected pancreatic parenchyma showed diffuse enlargement in 14 (52%) of the 27 patients and segmental enlargement in 13 (48%). The pancreatic parenchyma appeared hypointense on T1-weighted images in all 27 (100%) patients, hyperintense on T2-weighted images in 25 (93%), and isointense in two (7%). During the pancreatic phase of the dynamic contrast material-enhanced study, the affected pancreatic parenchyma appeared hypointense in 25 (93%) patients and isointense in two (7%). During the portal venous and delayed phases, the images of 19 (70%) patients showed delayed enhancement. Bile duct involvement was observed in 10 (37%) patients, and renal involvement was observed in two (7%). After steroid treatment, six (22%) patients had recurrent AIP, with a median disease-free interval of 20.6 months. The sites of recurrence were the pancreas and the kidneys in three of the six patients, solely the pancreas in two patients, and the biliary ducts in one patient.

CONCLUSION

MR imaging with MR cholangiopancreatography enables the diagnosis of pancreatic and extrapancreatic AIP and the assessment of changes after steroid therapy.

Identification of SNF2h, a chromatin-remodeling factor, as a novel binding protein of Vpr of human immunodeficiency virus type 1

Vpr, an accessory gene of human immunodeficiency virus type 1, encodes a virion-associated nuclear protein that plays an important role in the primary viral infection of resting macrophages. It has a variety of biological functions, including roles in a cell cycle abnormality at G(2)/M phase, apoptosis, nuclear transfer of preintegration complex, and DNA double-strand breaks (DSBs), some of which depend on its association with the chromatin of the host cells. Given that DSB signals are postulated to be a positive factor in the viral infection, understanding the mode of chromatin recruitment of Vpr is important. Here, we identified SNF2h, a chromatin-remodeling factor, as a novel binding partner of Vpr involved in its chromatin recruitment. When endogenous SNF2h protein was extensively downregulated by SNF2h small interfering RNA (siRNA), the amount of Vpr loaded on chromatin decreased to about 30% of the control level. Biochemical analysis using a mutant Vpr suggested that Vpr binds SNF2h via HFRIG (amino acids 71-75 depicted by single letters) and the Vpr mutant lacking this motif lost the activity to induce DSB-dependent signals. Consistently, Vpr-induced DSBs were attenuated by extensive downregulaion of endogenous SNF2h. Based on these data, we discuss the role of DSB and DSB signals in the viral infection.

Deposition of complement C3c, immunoglobulin (Ig)G4 and IgG at the basement membrane of pancreatic ducts and acini in autoimmune pancreatitis

AIMS

Autoimmune pancreatitis (AIP) is a type of pancreatitis whose immunopathogenesis is still unknown. It has been reported that renal biopsy specimens from patients diagnosed with both AIP and tubulointerstitial nephritis reveal deposits containing complement C3, immunoglobulin (Ig)G and IgG4 at the tubular basement membranes (BMs). The aim was to investigate the deposition of complement and immunoglobulins in pancreatic tissue from AIP patients compared to non-AIP patients.

METHODS

Double immunofluorescence microscopy for C3c, IgG4 and IgG together with CK7, trypsin, collagen IV, CD31 and CD79a, as well as immunofluorescence microscopy for C1q, IgA and IgM, were performed on frozen pancreatic tissue from AIP and alcoholic chronic pancreatitis (ACP) patients.

RESULTS

In AIP patients, complement C3c, IgG4 and IgG were deposited at the collagen IV-positive BMs of pancreatic and bile ducts and of acini. In a minority of the ACP patients, weak C3c-positive BM deposits were detected, but no IgG4- or IgG-positive BM deposits were present.

CONCLUSION

The deposition of C3c, IgG4 and IgG at the BM of small- and medium-sized ducts and acini of the pancreas is characteristic of AIP. This suggests that immune complex-mediated destruction of ducts and acini play a role in the pathogenesis of AIP.

Chronic pancreatitis

Chronic pancreatitis is a progressive fibroinflammatory disease that exists in large-duct (often with intraductal calculi) or small-duct form. In many patients this disease results from a complex mix of environmental (eg, alcohol, cigarettes, and occupational chemicals) and genetic factors (eg, mutation in a trypsin-controlling gene or the cystic fibrosis transmembrane conductance regulator); a few patients have hereditary or autoimmune disease. Pain in the form of recurrent attacks of pancreatitis (representing paralysis of apical exocytosis in acinar cells) or constant and disabling pain is usually the main symptom. Management of the pain is mainly empirical, involving potent analgesics, duct drainage by endoscopic or surgical means, and partial or total pancreatectomy. However, steroids rapidly reduce symptoms in patients with autoimmune pancreatitis, and micronutrient therapy to correct electrophilic stress is emerging as a promising treatment in the other patients. Steatorrhoea, diabetes, local complications, and psychosocial issues associated with the disease are additional therapeutic challenges.

International consensus diagnostic criteria for autoimmune pancreatitis: guidelines of the International Association of Pancreatology

OBJECTIVES

To achieve the goal of developing international consensus diagnostic criteria (ICDC) for autoimmune pancreatitis (AIP).

METHODS

An international panel of experts met during the 14th Congress of the International Association of Pancreatology held in Fukuoka, Japan, from July 11 through 13, 2010. The proposed criteria represent a consensus opinion of the working group.

RESULTS

Autoimmune pancreatitis was classified into types 1 and 2. The ICDC used 5 cardinal features of AIP, namely, imaging of pancreatic parenchyma and duct, serology, other organ involvement, pancreatic histology, and an optional criterion of response to steroid therapy. Each feature was categorized as level 1 and 2 findings depending on the diagnostic reliability. The diagnosis of type 1 and type 2 AIP can be definitive or probable, and in some cases, the distinction between the subtypes may not be possible (AIP-not otherwise specified).

CONCLUSIONS

The ICDC for AIP were developed based on the agreement of an international panel of experts in the hope that they will promote worldwide recognition of AIP. The categorization of AIP into types 1 and 2 should be helpful for further clarification of the clinical features, pathogenesis, and natural history of these diseases.

Pathogenesis of IgG4-related disease

PURPOSE OF REVIEW

To review studies that have examined underlying genetic and immunological aspects of IgG4-related disease.

RECENT FINDINGS

Genetic studies have suggested that several human leukocyte antigen (HLA) and non-HLA haplotypes/genotypes are associated with susceptibility to IgG4-related disease or to disease relapse after steroid therapy. Among several autoantibodies identified so far, autoantibodies against lactoferrin and carbonic anhydrase II are most frequently detected in serum of IgG4-disease patients. However, it has not been well clarified whether or not those autoantibodies belong to an IgG4 subclass. Studies that have demonstrated molecular mimicry between Helicobacter pylori and constituents of pancreatic epithelial cells suggest that gastric H. pylori infection triggers autoimmune pancreatitis in genetically predisposed individuals through antibody cross-reactivity. Recently, T-helper 2 immune reaction has been suggested to be predominant in IgG4-related disease. Interestingly, regulatory immune reactions are activated in IgG4-related disease, and regulatory cytokines interleukin-10 and transforming growth factor-b have been suggested, respectively, to play important roles in IgG4 class switch and fibroplasia.

SUMMARY

Autoimmunity has been considered the most probable pathogenesis of IgG4-related disease, but has not been completely proved so far. A breakthrough study to detect a specific autoantigen, autoantibody, or pathogen is necessary.

Serologic issues in IgG4-related systemic disease and autoimmune pancreatitis

PURPOSE OF REVIEW

IgG4-related systemic disease (ISD) is a recently recognized syndrome affecting multiple organs. Autoimmune pancreatitis (AIP) is the pancreatic manifestation of ISD and mimics pancreatic cancer. Current data show frequent association with serum IgG4 elevation and other serologic abnormalities. Here we explore the diagnostic and possible prognostic utility and pathogenetic implications of serologic abnormalities in ISD.

RECENT FINDINGS

Serum IgG4 elevations (>140 mg/dl) are seen in 70-80% of AIP patients and also in 5% of normal population and 10% of pancreatic cancer making it an unsuitable single marker for diagnosis. However, when combined with other features of AIP, it can be of great diagnostic value though its utility in monitoring of therapy or as a marker or predictor of relapse is limited. Several other antibodies have been identified in AIP against pancreas-specific antigens like trypsinogens I and II, pancreatic secretory trypsin inhibitor (PSTI) and plasminogen binding protein (PBP) and other nonpancreas-specific antigens. Anti-PBP antibodies appear to have potential diagnostic utility but require further validation.

SUMMARY

No single serologic marker is diagnostic of ISD. Serum IgG4 elevation has convincing diagnostic utility when combined with other disease features although its value in disease monitoring may be limited.

Recent advances in the concept and diagnosis of autoimmune pancreatitis and IgG4-related disease

Recent studies have suggested the existence of two subtypes of autoimmune pancreatitis (AIP): type 1 AIP, related to IgG4 (lymphoplasmacytic sclerosing pancreatitis); and type 2 AIP, related to a granulocytic epithelial lesion (idiopathic duct-centric chronic pancreatitis). Compared with type 2 AIP, the clinicopathological features of type 1 AIP, with increased serum IgG4/IgE levels, abundant infiltration of IgG4 + plasmacytes and lymphocytes, autoantibodies, and steroid responsiveness, are more suggestive of abnormal immunity such as allergy or autoimmunity. Moreover, patients with type 1 AIP often have extrapancreatic lesions, such as sclerosing cholangitis, sclerosing sialadenitis, or retroperitoneal fibrosis, showing pathological features similar to those of the pancreatic lesions. Based on these findings, an international concept of and diagnostic criteria for AIP have been proposed recently. Of interest, many synonyms have been proposed for the conditions of AIP and extrapancreatic lesions associated with IgG4, such as "multifocal idiopathic fibrosclerosis," "IgG4-related autoimmune disease," "IgG4-related sclerosing disease," "systemic IgG4-related plasmacytic syndrome (SIPS)," and "IgG4-related multiorgan lymphoproliferative syndrome," all of which may refer to the same conditions. Therefore, the Japanese Research Committee for "Systemic IgG4-Related Sclerosing Disease" proposed a disease concept and clinical diagnostic criteria based on the concept of multifocal fibrosclerosing disease, in 2009, in which the term "IgG4-related disease" was agreed upon as a minimal consensus to cover these conditions. Although the significance of IgG4 in the development of "IgG4-related disease" remains unclear, we have proposed a hypothesis for the development of type 1 AIP, one of the IgG4-related diseases. The concept and diagnostic criteria of "IgG4-related disease" will be changed in accordance with future studies.

Identification of candidate IgG biomarkers for Alzheimer's disease via combinatorial library screening

The adaptive immune system is thought to be a rich source of protein biomarkers, but diagnostically useful antibodies remain unknown for a large number of diseases. This is, in part, because the antigens that trigger an immune response in many diseases remain unknown. We present here a general and unbiased approach to the identification of diagnostically useful antibodies that avoids the requirement for antigen identification. This method involves the comparative screening of combinatorial libraries of unnatural, synthetic molecules against serum samples obtained from cases and controls. Molecules that retain far more IgG antibodies from the case samples than the controls are identified and subsequently tested as capture agents for diagnostically useful antibodies. The utility of this method is demonstrated using a mouse model for multiple sclerosis and via the identification of two candidate IgG biomarkers for Alzheimer's disease.

Outcome of patients with type 1 or 2 autoimmune pancreatitis

OBJECTIVES

Autoimmune pancreatitis (AIP) is better described than before, but there is still no international consensus for definition, diagnosis, and treatment. Our aims were to analyze the short- and long-term outcome of patients with focus on pancreatic endocrine and exocrine functions, to search for predictive factors of relapse and pancreatic insufficiency, and to compare patients with type 1 and type 2 AIP.

METHODS

All consecutive patients followed up for AIP in our center between 1999 and 2008 were included. Two groups were defined: (a) patients with type 1 AIP meeting HISORt (Histology, Imaging, Serology, Other organ involvement, and Response to steroids) criteria; (b) patients with definitive/probable type 2 AIP including those with histologically confirmed idiopathic duct-centric pancreatitis ("definitive") or suggestive imaging, normal serum IgG4, and response to steroids ("probable"). AIP-related events and pancreatic exocrine/endocrine insufficiency were looked for during follow-up. Predictive factors of relapse and pancreatic insufficiency were analyzed.

RESULTS

A total of 44 patients (22 males), median age 37.5 (19-73) years, were included: 28 patients (64%) with type 1 AIP and 16 patients (36%) with type 2 AIP. First-line treatment consisted of steroids or pancreatic resection in 59 and 27% of the patients, respectively. Median follow-up was 41 (5-130) months. Steroids were effective in all treated patients. Relapse was observed in 12 patients (27%), after a median delay of 6 months (1-70). Four patients received azathioprine because of steroid resistance/dependence. High serum IgG4 level, pain at time of diagnosis, and other organ involvement were associated with relapse (P<0.05). At the end point, pancreatic atrophy was observed in 35% of patients. Exocrine and endocrine insufficiencies were present in 34 and 39% of the patients, respectively. At univariate analysis, no factor was associated with exocrine insufficiency, although female gender (P=0.04), increasing age (P=0.006), and type 1 AIP (P=0.001) were associated with the occurrence of diabetes. Steroid/azathioprine treatment did not prevent pancreatic insufficiency. Type 2 AIP was more frequently associated with inflammatory bowel disease than type 1 AIP (31 and 3%, respectively), but relapse rates were similar in both groups.

CONCLUSIONS

Relapse occurs in 27% of AIP patients and is more frequent in patients with high serum IgG4 levels at the time of diagnosis. Pancreatic atrophy and functional insufficiency occur in more than one-third of the patients within 3 years of diagnosis. The outcome of patients with type 2 AIP, a condition often associated with inflammatory bowel disease, is not different from that of patients with type 1 AIP, except for diabetes.

Autoimmune pancreatitis complicated by carcinoma of the pancreatobiliary system: a case report and review of the literature

We present the case of a 67-year-old woman who developed a metastatic adenocarcinoma of the pancreatobiliary system shortly after the histologically confirmed diagnosis of autoimmune pancreatitis (AIP). This case highlights the need for increased alertness not only in differentiating AIP from pancreatic cancer at the time of diagnosis, but also to exclude concomitant malignancies of the pancreatobiliary system in the management of histologically confirmed AIP.

A mouse model of autoimmune pancreatitis with salivary gland involvement triggered by innate immunity via persistent exposure to avirulent bacteria

The pathogenesis of autoimmune pancreatitis (AIP) remains unknown. Here, we investigated the possible involvement of chronic, persistent exposure to avirulent bacteria in the pathogenesis of AIP. C57BL/6 mice were inoculated with heat-killed Escherichia coli weekly for 8 weeks. At 1 week and up to 12 months after the final inoculation, the mice were killed to obtain samples. At 1 week after the final E. coli inoculation, marked cellular infiltration with fibrosis was observed in the exocrine pancreas. Cellular infiltration in the exocrine pancreas was still observed up to 12 months after the completion of E. coli inoculation. At 10 months after the final inoculation, duct-centric fibrosis became obvious. Inflammation around the ducts in the salivary glands was also observed. Furthermore, sera from heat-killed E. coli-inoculated mice possessed anti-carbonic anhydrase, anti-lactoferrin, and antinuclear antibodies. Exposure to E. coli-triggered AIP-like pancreatitis in C57BL/6 mice. We propose a hypothetical mechanism for AIP pathogenesis. During the initiation phase, silently infiltrating pathogen-associated molecular patterns (PAMP) and/or antigen(s) such as avirulent bacteria might trigger and upregulate the innate immune system. Subsequently, the persistence of such PAMP attacks or stimulation by molecular mimicry upregulates the host immune response to the target antigen. These slowly progressive steps may lead to the establishment of AIP and associated extrapancreatic lesions. Our model might be useful for clarifying the pathogenesis of AIP.

The therapeutic strategy for autoimmune pancreatitis is subject to the endoscopic features of the duodenal papilla

Autoimmune pancreatitis (AIP) often presents with a swollen duodenal papilla, however, the clinical significance of the duodenal papilla in AIP has not been fully elucidated. Data have shown swollen duodenal papillae shaped like a pear and/or with a submucosal tumor having IgG4-bearing plasma cells. Immunohistopathology has potentially verified duodenal papillitis associated with AIP. FOXP3-positive lymphocytes are also recognized in AIP. AIP has shown spontaneous remission and relapse irrelevance to corticosteroid therapy. The results of a multivariate analysis revealed the absence of a swollen duodenal papilla as the only significant independent factor predictive of spontaneous remission in AIP cases. In addition, the results of another multivariate analysis revealed the presence of a swollen duodenal papilla and the presence of extrapancreatic lesions as the significant independent factors predictive of relapse in these cases. Results suggest that the lack of a swollen duodenal papilla is a predictive factor for spontaneous remission, and thus negates the need to administer corticosteroids in those AIP patients. In contrast, a swollen duodenal papilla and the presence of extrapancreatic lesions are risk factors for relapse, and those AIP patients are candidates for maintenance corticosteroid therapy to reduce relapse. Therefore, the therapeutic strategy such as the indication for corticosteroid administration is subject to the endoscopic features of the duodenal papilla.

Pathogenesis of cholestatic liver disease and therapeutic approaches

Cholestatic liver disorders are caused by genetic defects, mechanical aberrations, toxins, or dysregulations in the immune system that damage the bile ducts and cause accumulation of bile and liver tissue damage. They have common clinical manifestations and pathogenic features that include the responses of cholangiocytes and hepatocytes to injury. We review the features of bile acid transport, tissue repair and regulation, apoptosis, vascular supply, immune regulation, and cholangiocytes that are associated with cholestatic liver disorders. We now have a greater understanding of the physiology of cholangiocytes at the cellular and molecular levels, as well as genetic factors, repair pathways, and autoimmunity mechanisms involved in the pathogenesis of disease. These discoveries will hopefully lead to new therapeutic approaches for patients with cholestatic liver disease.

IgG₄-related sclerosing disease: a novel mimic of inflammatory bowel disease

High levels of IgG₄-positive plasma cells are commonly seen in autoimmune pancreatitis. It has recently become evident that autoimmune pancreatitis is one component of a larger multi-system disease. IgG₄-positive plasma cells have been identified in many extrapancreatic tissues, including the colon, biliary tract, liver, and lungs, and thus the term "IgG₄-related sclerosing disease" has been proposed. Awareness of IgG₄-related sclerosing disease is important, as it has been shown to mimic other conditions like malignancy. This review discusses IgG₄-related colitis and its potential for mimicking inflammatory bowel disease.

Riedel's thyroiditis and multifocal fibrosclerosis are part of the IgG4-related systemic disease spectrum

OBJECTIVE

Riedel's thyroiditis is a chronic fibrosing disorder of unknown etiology often associated with "multifocal fibrosclerosis." IgG4-related systemic disease is characterized by IgG4+ plasma cell infiltration and fibrosis throughout many organs. We hypothesized that Riedel's thyroiditis is part of the IgG4-related systemic disease spectrum.

METHODS

We searched our institution's pathology database using the terms "Riedel's," "struma," "thyroid," and "fibrosis," and identified 3 cases of Riedel's thyroiditis. Riedel's thyroiditis was diagnosed if there was a fibroinflammatory process involving all or a portion of the thyroid gland, with evidence of extension of the process into surrounding tissues. Immunohistochemical stains for IgG4 and IgG were performed. The histopathologic and immunohistochemical features of each involved organ were evaluated. The clinical features of one patient with multiple organ system disease were described.

RESULTS

All 3 thyroidectomy samples stained positively for IgG4-bearing plasma cells. One patient had extensive extrathyroidal involvement diagnostic of IgG4-related systemic disease, including cholangitis, pseudotumors of both the lung and lacrimal gland, and a lymph node contiguous to the thyroid that stained intensely for IgG4+ plasma cells. The histologic features of all organs involved were consistent with IgG4-related systemic disease. Patient 3 had 10 IgG4+ plasma cells per high-power field initially, but rebiopsy 2 years later demonstrated no IgG4+ plasma cells. That patient's second biopsy, characterized by fibrosis and minimal residual inflammation, further solidifies the link between IgG4-bearing plasma cells in tissue and the histologic evolution to Riedel's thyroiditis.

CONCLUSION

Riedel's thyroiditis is part of the IgG4-related systemic disease spectrum. In many cases, multifocal fibrosclerosis and IgG4-related systemic disease are probably the same entity.

Autoimmune pancreatitis--a new evolving pancreatic disease?

INTRODUCTION

Recent advances support the concept of autoimmune pancreatitis as a unique systemic disease because occasional extrapancreatic lesions such as sclerosing cholangitis, sclerosing sialoadenitis, and retroperitoneal fibrosis show similar pathological features with fibrosis and abundant infiltration of IgG4-positive plasma cells, and are steroid responsive. Based on these findings, several diagnostic criteria have been proposed.

MATERIALS AND METHODS

Although AIP is accepted worldwide as a unique clinical entity, pathogenetic mechanism still remains unclear. To clarify it, genetic background, humoral immunity, candidates of target antigens including self-antigens and molecular mimicry from microbes, cellular immunity including regulatory T cells, complement system, and experimental models are reviewed.

RESULTS

Based on these findings, we have proposed a hypothesis for the pathogenesis of AIP in the biphasic mechanism of "induction" and "progression." In the early stage, initial response to self-antigens (LF, CA-II, CA-IV, PSTI, or α-fodrin) or molecular mimicry (Helicobacter pylori) is induced by decreased naive regulatory T cells (Tregs), and Th1 cells release proinflammatory cytokines (IFN-γ, IL-1b, IL-2, and TNF-α).

DISCUSSION

In the chronic stage, progression is supported by increased memory Tregs and Th2 immune responses. The classical pathway of complement system may be activated by IgG1 immune complex.

CONCLUSION

As Tregs seem to take important roles in progression as well as induction of the disease, further studies are necessary to clarify the pathogenesis.

Diagnosis and treatment of autoimmune pancreatitis

PURPOSE OF REVIEW

To summarize the existing knowledge of autoimmune pancreatitis (AIP) and to review the progress made in the diagnosis and treatment of AIP in the past year.

RECENT FINDINGS

The term 'AIP' appears to encompass at least two distinct subtypes, type 1 and type 2. Type 1 AIP is the pancreatic manifestation of a systemic fibroinflammatory disease called immunoglobulin G4-associated systemic disease. Type 2 AIP affects younger patients, does not have a gender predilection and is associated with normal serum immunoglobulin G4 levels. Existing criteria are geared toward diagnosis of type 1; type 2 AIP can be definitively diagnosed only on pancreatic histology. Both subtypes respond to corticosteroid therapy. However, there are no standardized protocols for initial treatment or management and prevention of relapses in AIP. A novel antibody for AIP has recently been identified and its performance needs validation from other centers. Newly published strategies for differentiating AIP from pancreatic cancer are available.

SUMMARY

AIP is a rare disease whose recognition and understanding are evolving. Much needs to be elucidated with regard to its cause, pathogenesis, treatment of relapse and long-term outcomes. A multidisciplinary team, familiar with the disease, is critical in making the correct diagnosis.

Autoantibodies against the exocrine pancreas in autoimmune pancreatitis: gene and protein expression profiling and immunoassays identify pancreatic enzymes as a major target of the inflammatory process

OBJECTIVES

Autoimmune pancreatitis (AIP) is thought to be an immune-mediated inflammatory process, directed against the epithelial components of the pancreas. The objective was to identify novel markers of disease and to unravel the pathogenesis of AIP.

METHODS

To explore key targets of the inflammatory process, we analyzed the expression of proteins at the RNA and protein level using genomics and proteomics, immunohistochemistry, western blot, and immunoassay. An animal model of AIP with LP-BM5 murine leukemia virus-infected mice was studied in parallel. RNA microarrays of pancreatic tissue from 12 patients with AIP were compared with those of 8 patients with non-AIP chronic pancreatitis.

RESULTS

Expression profiling showed 272 upregulated genes, including those encoding for immunoglobulins, chemokines and their receptors, and 86 downregulated genes, including those for pancreatic proteases such as three trypsinogen isoforms. Protein profiling showed that the expression of trypsinogens and other pancreatic enzymes was greatly reduced. Immunohistochemistry showed a near-loss of trypsin-positive acinar cells, which was also confirmed by western blotting. The serum of AIP patients contained high titers of autoantibodies against the trypsinogens PRSS1 and PRSS2 but not against PRSS3. In addition, there were autoantibodies against the trypsin inhibitor PSTI (the product of the SPINK1 gene). In the pancreas of AIP animals, we found similar protein patterns and a reduction in trypsinogen.

CONCLUSIONS

These data indicate that the immune-mediated process characterizing AIP involves pancreatic acinar cells and their secretory enzymes such as trypsin isoforms. Demonstration of trypsinogen autoantibodies may be helpful for the diagnosis of AIP.

IgG4-related sclerosing disease: a critical appraisal of an evolving clinicopathologic entity

An elevated serum titer of immunoglobulin G4 (IgG4), the least common (3% to 6%) of the 4 subclasses of IgG, is a surrogate marker for the recently characterized IgG4-related sclerosing disease. The syndrome affects predominantly middle-aged and elderly patients, with male predominance. The patients present with symptoms referable to the involvement of 1 or more sites, usually in the form of mass lesions. The prototype is IgG4-related sclerosing pancreatitis (also known as autoimmune pancreatitis), most commonly presenting as painless obstructive jaundice with or without a pancreatic mass. Other common sites of involvement are the hepatobiliary tract, salivary gland, orbit, and lymph node, but practically any organ-site can be affected, such as retroperitoneum, aorta, mediastinum, soft tissue, skin, central nervous system, breast, kidney, prostate, upper aerodigestive tract, and lung. The patients usually have a good general condition, with no fever or constitutional symptoms. Common laboratory findings include raised serum globulin, IgG, IgG4, and IgE, whereas lactate dehydrogenase is usually not raised. Some patients have low titers of autoantibodies (such as antinuclear antibodies and rheumatoid factor). The disease often shows excellent response to steroid therapy. The natural history is characterized by the development of multiple sites of involvement with time, sometimes after many years. However, the disease can remain localized to 1 site in occasional patients. The main pathologic findings in various extranodal sites include lymphoplasmacytic infiltration, lymphoid follicle formation, sclerosis and obliterative phlebitis, accompanied by atrophy and loss of the specialized structures of the involved tissue (such as secretory acini in pancreas, salivary gland, or lacrimal gland). The relative predominance of the lymphoplasmacytic and sclerotic components results in 3 histologic patterns: pseudolymphomatous, mixed, and sclerosing. Immunostaining shows increased IgG4+ cells in the involved tissues (>50 per high-power field, with IgG4/IgG ratio >40%). The lymph nodes show multicentric Castleman disease-like features, reactive follicular hyperplasia, interfollicular expansion, or progressive transformation of germinal centers, with the unifying feature being an increase in IgG4+ plasma cells on immunostaining. The nature and pathogenesis of IgG4-related sclerosing disease are still elusive. Occasionally, the disease can be complicated by the development of malignant lymphoma and possibly carcinoma.

Autoimmune pancreatitis: the clinicopathological characteristics of the subtype with granulocytic epithelial lesions

Autoimmune pancreatitis (AIP) has been established as a distinct form of chronic pancreatitis that is distinguishable from other types such as alcoholic, hereditary or obstructive chronic pancreatitis. AIP seems to be a global disease, since it has been reported in many different countries, especially from Japan, USA and Europe (Germany, Italy, United Kingdom). Typical histopathological findings in the pancreas in AIP include a periductal lymphoplasmacytic infiltration with fibrosis, causing narrowing of the involved ducts. The typical clinical features include presentation with obstructive jaundice/pancreatic mass and a dramatic response to steroids. However, while the reports from Japan describe uniform changes called lymphoplasmacytic sclerosing pancreatitis (LPSP) in the pancreas from AIP patients, the reports from Europe and USA distinguish two histopathologic patterns in AIP patients: one with the characteristics of LPSP and another with slightly different histological features, called idiopathic duct centric pancreatitis (IDCP) or AIP with granulocytic epithelial lesions (GELs). This article reviews the evidence that GEL-positive AIP or IDCP is a second type of AIP, distinct from LPSP, in regard to pancreatic pathology, immunology and epidemiology.

Autoimmune pancreatitis and IgG4-related sclerosing disease

Autoimmune pancreatitis (AIP) is a unique form of pancreatitis in which the pathogenesis is suspected to involve autoimmune mechanisms. AIP sometimes mimics pancreatic cancer in its presentation, but as AIP responds dramatically to steroid therapy, accurate diagnosis is necessary. AIP is currently diagnosed on the basis of a combination of characteristic clinical, serological, morphological and histopathological features. However, its diagnosis remains a clinical challenge and there are no internationally agreed diagnostic criteria. Another type of AIP called 'idiopathic duct-centric chronic pancreatitis' or 'AIP with granulocytic epithelial lesion' has been reported in Western countries. IgG4-related sclerosing disease is a systemic disease in which IgG4-positive plasma cells and T lymphocytes extensively infiltrate various organs. Organs with tissue fibrosis and obliterative phlebitis, such as the pancreas, salivary gland and retroperitoneum, show clinical manifestations; AIP seems to represent one manifestation of IgG4-related sclerosing disease. As a mass is formed in most cases of IgG4-related sclerosing disease, a malignant tumor is frequently suspected on initial presentation. Clinicians should consider IgG4-related sclerosing disease in the differential diagnosis to avoid unnecessary surgery.

Differences in clinical profile and relapse rate of type 1 versus type 2 autoimmune pancreatitis

BACKGROUND & AIMS

Autoimmune pancreatitis (AIP) has been divided into subtypes 1 (lymphoplasmacytic sclerosing pancreatitis) and 2 (idiopathic duct centric pancreatitis). We compared clinical profiles and long-term outcomes of types 1 and 2 AIP.

METHODS

We compared clinical presentation, relapse, and vital status of 78 patients with type 1 AIP who met the original HISORt criteria and 19 patients with histologically confirmed type 2 AIP.

RESULTS

At presentation, patients with type 1 AIP were older than those with type 2 AIP (62 +/- 14 vs 48 +/- 19 years; P < .0001) and had a greater prevalence of increased serum levels of immunoglobulin G4 (47/59 [80%] vs 1/6 [17%]; P = .004). Patients with type 1 were more likely than those with type 2 to have proximal biliary, retroperitoneal, renal, or salivary disease (60% vs 0; P < .0001). Inflammatory bowel disease was associated with types 1 and 2 (6% vs 16%; P = .37). During median clinical follow-up periods of 42 and 29 months, respectively, 47% of patients with type 1 and none of those with type 2 experienced a relapse. In type 1 AIP, proximal biliary involvement (hazard ratio [HR], 2.12; P = .038) and diffuse pancreatic swelling (HR, 2.00; P = .049) were predictive of relapse, whereas pancreaticoduodenectomy reduced the relapse rate (vs the corticosteroid-treated group; HR, 0.15; P = .0001). After median follow-up periods of 58 and 89 months (types 1 and 2, respectively), the 5-year survival rates for both groups were similar to those of the age- and sex-matched US population.

CONCLUSIONS

Types 1 and 2 AIP have distinct clinical profiles. Patients with type 1 AIP have a high relapse rate, but patients with type 2 AIP do not experience relapse. AIP does not affect long-term survival.

Do incretin-based therapies cause acute pancreatitis?

In 2007 a question was raised about the causal relationship between the first of the glucagon-like peptide 1 receptor agonists, exenatide, and pancreatitis, as postmarketing reports of pancreatitis in patients treated with this agent had been received by the Food and Drug Administration (FDA). There had been six reports of hemorrhagic pancreatitis, with two of the cases resulting in death. An update of the package insert for Byetta was mandated. Sitagliptin entered the market about a year and a half later, and now there are similar reports of acute pancreatitis. As the number of patients treated with these agents increases, is it uncovering a risk not appreciated in the premarket phase or just what should be expected from the population treated with these agents? To date, 88 cases of acute pancreatitis have been reported to the FDA in patients taking sitagliptin (Januvia/Janumet). Of these, two cases have been hemorrhagic or necrotizing pancreatitis. A revision of the package insert for sitagliptin has been made recently. An examination of available data should help shed light on whether the relation is likely causal or merely incidental.