Identification of a novel antibody associated with autoimmune pancreatitis

In vitro studies implicate an imbalanced activation of dendritic cells in the pathogenesis of murine autoimmune pancreatitis

Objectives

MRL/MpJ mice spontaneously develop an autoimmune pancreatitis (AIP) and are widely used as a model to study the genetic, molecular and immunological basis of the disease. Here, we have addressed the question whether distinctive features of their dendritic cells (DCs) may predispose MRL/MpJ mice to the chronic inflammation.

Methods

Pancreatic lesions were analyzed employing histological methods. Cohorts of young (healthy) MRL/MpJ mice, adult (sick) individuals, and AIP-resistant CAST/EiJ mice were used to establish cultures of bone marrow (BM)-derived conventional DCs (cDCs). The cells were subsequently characterized regarding the expression profile of CD markers and selected genes, proliferative activity as well as cytokine secretion.

Results

In pancreatic lesions, large numbers of cells expressing the murine DC marker CD11c were detected in close spatial proximity to CD3⁺ cells. A high percentage of BM-derived cDCs from adult MRL/MpJ mice expressed typical markers of DC maturation (such as CD83) already prior to a treatment with lipopolysaccharide (LPS). After LPS-stimulation, cDC cultures of both MRL/MpJ mouse cohorts contained more mature cells, proliferated at a higher rate and secreted less interleukin-10 (but also less pro-inflammatory cytokines) than cultures of CAST/EiJ mice. Compared with corresponding cultures of the control strain, LPS-free cultured cDCs from MRL/MpJ mice expressed less mRNA of the inhibitory receptor triggering receptor expressed on myeloid cells 2 (trem2).

Conclusions

BM-derived cDCs from AIP-prone MRL/MpJ mice display functional features that are compatible with the hypothesis of an imbalanced DC activation in the context of murine AIP.

Immunoglobulin G4-related disease: a rare disease with an unusual presentation

IgG4‐RD can also present in the skeletal muscle, mimicking several other diseases. It is unusual for this relatively new classification of diseases to present in the muscles and can be mistakenly diagnosed as other autoimmune diseases rendering a delay in the appropriate management and progression of the disease.

Helicobacter pylori is undetectable in intraductal papillary mucinous neoplasm

BACKGROUND

About half of the world population is infected with Helicobacter pylori (H. pylori), a bacterium associated with gastric cancer and considered to be a risk factor for pancreatic ductal adenocarcinoma. Whether the bacterium is associated with intraductal papillary mucinous neoplasm, believed to be a precursor of pancreatic ductal adenocarcinoma, is unknown. The aim of this study was to investigate the presence of H. pylori DNA in tissue sections of intraductal papillary mucinous neoplasm.

METHODS

The presence of H. pylori DNA was tested in a retrospective controlled study of formalin-fixed, paraffin-embedded pancreatic tissues from 24 patients who underwent surgery for intraductal papillary mucinous neoplasm. Histologically normal tissues surrounding neoplasms were used as control. H. pylori DNA was evaluated after deparaffinization, DNA extraction, and purification, and results were evaluated statistically.

RESULTS

Samples were collected from 13 males and 11 females with mean age 59 years (range 44-77), and consisted of 19 cases of main-duct and three cases of branched-duct intraductal papillary mucinous neoplasm. Two patients were diagnosed with pancreatic cancer and main-duct intraductal papillary mucinous neoplasm. H. pylori DNA was not detected either in intraductal papillary mucinous neoplasm tissue, or in surrounding normal tissue.

CONCLUSIONS

Although H. pylori has been implicated in pancreatic ductal adenocarcinoma, it may not play a key role in the development of intraductal papillary mucinous neoplasm.

A high-throughput sequence analysis of Japanese patients revealed 11 candidate genes associated with type 1 autoimmune pancreatitis susceptibility

The pathogenesis of autoimmune pancreatitis is unknown. In the present study we used high-throughput sequencing with next generation sequencing to identify the candidate genes associated with AIP. A total of 27 type 1 AIP patients and 30 healthy blood donors were recruited, and DNA samples were isolated from their mononuclear cells. A high-throughput sequencer with an original custom panel of 1031 genes was used to detect the genetic variants in each sample. Polymorphisms of CACNA1S (c.4642C>T), rs41554316, rs2231119, rs1042131, rs2838171, P2RX3 (c.195delG), rs75639061, SMAD7 (c.624delC) and TOP1 (c.2007delG), were identified as candidate genetic variants in patients with type 1 AIP. P2RX3 and TOP1 were significantly associated with AIP, even after adjusting bay means of Bonferroni's correction. In addition, we also identified eight candidate genetic variants that were associated with the relapse of type 1 AIP, namely: rs1143146, rs1050716, HLA-C (c.759_763delCCCCCinsTCCCG), rs1050451, rs4154112, rs1049069, CACNA1C (c.5996delC) and CXCR3 (c.630_631delGC). Finally polymorphisms of rs1050716 and rs111493987 were identified as candidate genetic variants associated with extra-pancreatic lesions in patients with type 1 AIP. These candidates might be used as markers of AIP susceptibility and could contribute to the pathogenesis of type 1 AIP.

A high number of IgG4-positive cells in gastric cancer tissue is associated with tumor progression and poor prognosis

IgG4-related disease is a newly defined disease characterized by elevated serum IgG4 levels and infiltration of affected organs by IgG4-positive plasma cells. Recently, increased IgG4 levels were reported to be closely related with malignancy. To assess the relationship between IgG4 and the progression of gastric cancer, we immunohistochemically stained in this study gastric cancer tissue samples for IgG4-positive cells using an anti-IgG4 antibody. In addition, pre- and postoperative serum concentrations of IgG4 were measured, using an enzyme-linked immunosorbent assay. In gastric cancer samples, the number of CD138-positive plasma cells was significantly lower and the number of IgG4-positive cells significantly higher than in non-cancerous gastric mucosa. The number of IgG4-positive cells was significantly correlated with gross tumor appearance, tumor depth, lymph node metastasis, venous invasion, and lymphatic invasion. Prognosis was significantly poorer in patients with a high number of IgG4-positive cells than in those with a low number. Multivariate analysis indicated that both the number of IgG4-positive cells and the depth of tumor invasion were independently prognostic of survival. In conclusion, in gastric cancer, the number of IgG4-positive cells is increased and this is closely associated with gastric cancer progression.

Autoimmune Pancreatitis: An Update on Diagnosis and Management

There is an evolving understanding that autoimmune pancreatitis (AIP) is an immunoglobulin (Ig) G4 systemic disease. It can manifest as primarily a pancreatic disorder or in association with other disorders of presumed autoimmune cause. Classic clinical characteristics include obstructive jaundice, abdominal pain, and acute pancreatitis. Thus, AIP can be difficult to distinguish from pancreatic malignancy. However, AIP may respond to therapy with corticosteroids, and has a strong association with other immune mediated diseases. Although primarily a pathologic diagnosis, attempts have been made to reliably diagnose AIP clinically. AIP can be classified as either type 1 or type 2.

New Thoughts on Immunoglobulin G4-Related Sclerosing Cholangitis

Immunoglobulin G4 (IgG4)-related sclerosing cholangitis (IgG4-SC) is the biliary manifestation of the multisystem IgG4-related disease. IgG4-SC presents with biliary strictures and/or masses that can bear a striking similarity to other malignant and inflammatory diseases. Diagnosis is based on a combination of clinical, biochemical, radiological, and histologic findings with careful exclusion of malignant disease. Corticosteroids are the mainstay of treatment with good clinical, biochemical, and radiological responses. This review provides a comprehensive overview of the current knowledge of the prevalence, clinical features, radiology and histology findings, diagnosis, treatment, natural history, and pathophysiology of IgG4-SC.

Biopsy-proven IgG4-related lung disease

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory disorder that may involve single or multiple organs. Biopsy-proven lung involvement of this disease is occasionally reported, but not well understood.

METHODS

Patients with the diagnosis of biopsy-proven IgG4-related lung disease (IgG4-RLD) from Peking Union Medical College Hospital between January 2011 and July 2015 were retrospectively analyzed. Age, sex, clinical symptoms, laboratory findings, pulmonary function test results, chest CT tests, positron emission tomography (PET) examinations, treatments and prognoses were retrieved from medical records and analyzed.

RESULTS

Seventeen patients were included in this study (mean age: 44.8 ± 15.0 years). Ten patients were diagnosed via surgery, and 7 patients were diagnosed via percutaneous transthoracic core-needle lung biopsy. Extrapulmonary involvement was observed in only one patient. The clinical symptoms included cough, fever, dyspnea, chest pain and hemoptysis. The serum IgG4 concentration was elevated in 7/13 patients (mean: 1955 ± 1968 mg/L). The chest CT findings included mainly nodules and masses with spiculated borders, alveolar consolidations with air bronchograms, and ground glass opacities with or without reticular opacities. PET scans indicated increased standardized uptake values, and 7/8 patients were correctly diagnosed with benign inflammation. Corticosteroids and immunosuppressants were administered to 14/17 patients and effectively alleviated the disease.

CONCLUSIONS

In biopsy-proven IgG4-RLD, a normal serum IgG4 concentration is commonly seen, while extrapulmonary involvement is infrequent. Alveolar consolidation with air bronchograms is an important imaging finding of IgG4-RLD, which has not been emphasized before.

Implication of Cytotoxic Helicobacter pylori Infection in Autoimmune Diabetes

Background. Type 1 diabetes (T1D) and type 2 diabetes (T2D) have been linked to Helicobacter pylori infection, although results are conflicting. No previous study addressed a possible link between H. pylori infection and latent autoimmune diabetes in adults (LADA). In this study, a correlation among H. pylori infection and the risk of autoimmune diabetes in comparison with T2D was investigated. Methods. Sera from 234 LADA patients, 105 patients with late-onset T1D, and 156 patients with T2D were analyzed for anti-H. pylori and the cytotoxin-associated antigen (CagA) IgG antibodies. Results. H. pylori seroprevalence was comparable in LADA (52%), late-onset T1D (45%), and T2D (49%) with no gender differences. The seroprevalence of CagA IgG was significantly higher in autoimmune diabetes (late-onset T1D: 45%, LADA: 40%) compared to T2D (25%; p < 0.028). Conclusions. Although H. pylori seroprevalence was similar in LADA, T1D, and T2D, anti-CagA positivity was significantly increased among patients with autoimmune diabetes, suggesting that more virulent H. pylori strains might be a trigger for immune mechanisms involved in their pathogenesis.

Overlap of IgG4-related Disease and Primary Biliary Cirrhosis Complicated with Autoimmune Thrombocytopenia

A 63-year-old woman was referred to Fukushima Red Cross Hospital with an enlargement of the left submandibular gland and subcutaneous bleeding in the chest and legs. A diffuse enlargement of the pancreas was also detected by abdominal computed tomography, and laboratory data showed severe thrombocytopenia. She was diagnosed with IgG4-related disease (IgG4-RD) complicated with autoimmune thrombocytopenia and was treated with methylprednisolone, after which the number of platelets favorably increased. Further investigation for liver dysfunction revealed underlying primary biliary cirrhosis (PBC). We herein report a rare case of IgG4-RD overlapping PBC complicated with autoimmune thrombocytopenia.

A Case of Extensive IgG4-Related Disease Presenting as Massive Pleural Effusion, Mediastinal Mass, and Mesenteric Lymphadenopathy in a 16-Year-Old Male

IgG4-related disease is an immune-mediated fibro-inflammatory disease, characterized by lymphoplasmacytic infiltration composed of IgG4-positive plasma cells of various organs with elevated circulating levels of IgG4. This disease is now reported with increasing frequency and usually affects middle-aged men. Massive pleural effusion in children is an uncommon feature in IgG4-related disease. Here, we report a case of a 16-year-old male patient with extensive IgG4-related disease presenting with massive pleural effusion, mediastinal mass, and mesenteric lymphadenopathy.

Role of Amylase-α2A Autoantibodies in the Diagnosis of Autoimmune Pancreatitis

OBJECTIVES

Several serological markers have been reported in autoimmune pancreatitis (AIP) patients. However, only serum IgG4 (sIgG4) is available in clinical practice for AIP diagnosis. Antiamylase α antibodies (AMY-α Abs) have been proposed to diagnose AIP. This study evaluates the utility of AMY-α Abs and sIgG4 for AIP diagnosis.

METHODS

Twenty-five AIP patients, 84 disease control groups (31 chronic pancreatitis, 30 acute pancreatitis, 23 pancreatic adenocarcinoma), and 59 healthy donors were prospectively studied. The AMY-α Abs were determined by homemade enzyme-linked immunosorbent assay and sIgG4 by nephelometry.

RESULTS

Increased sIgG4 were detected to be present in 52% of AIP, 5% in control groups, and 0% in healthy donors, and AMY-α Abs, respectively, in 76%, 36%, and 2%. sIgG4 was elevated in 92% of the 13 patients with type 1 AIP, but in none of 3 with type 2 and of 8 with not otherwise specified AIP. The AMY-α Abs were present in 79%, 67%, and 75% of type 1, type 2, and not otherwise specified AIP, respectively. Sensitivity and specificity of AMY-α Abs were 76% and 78%, and of sIgG4 50% and 94%. By combining the 2 serological markers, sensitivity was 41%, and specificity was 99%.

CONCLUSIONS

The AMY-α Abs may help to diagnosis of AIP and to differentiate AIP subtypes.

IgG4-related disease in Italy: clinical features and outcomes of a large cohort of patients

OBJECTIVES

To describe the clinical features, treatment response, and follow-up of a large cohort of Italian patients with immunoglobulin (Ig)G4-related disease (IgG4-RD) referred to a single tertiary care centre.

METHOD

Clinical, laboratory, histological, and imaging features were retrospectively reviewed. IgG4-RD was classified as 'definite' or 'possible' according to international consensus guidelines and comprehensive diagnostic criteria for IgG4-RD. Disease activity was assessed by means of the IgG4-RD Responder Index (IgG4-RD RI).

RESULTS

Forty-one patients (15 females, 26 males) were included in this study: 26 with 'definite' IgG4-RD and 15 with 'possible' IgG4-RD. The median age at diagnosis was 62 years. The median follow-up was 36 months (IQR 24-51). A history of atopy was present in 30% of patients. The pancreas, retroperitoneum, and major salivary glands were the most frequently involved organs. Serum IgG4 levels were elevated in 68% of cases. Thirty-six patients were initially treated with glucocorticoids (GCs) to induce remission. IgG4-RD RI decreased from a median of 7.8 at baseline to 2.9 after 1 month of therapy. Relapse occurred in 19/41 patients (46%) and required additional immunosuppressive drugs to maintain long-term remission. Multiple flares occurred in a minority of patients. A single case of orbital pseudotumour did not respond to medical therapy and underwent surgical debulking.

CONCLUSIONS

IgG4-RD is an elusive inflammatory disease to be considered in the differential diagnosis of isolated or multiple tumefactive lesions. Long-term disease control can be achieved with corticosteroids and immunosuppressive drugs in the majority of cases.

Recent developments in steroid-responsive pancreatitides (autoimmune pancreatitis)

PURPOSE OF REVIEW

There are two distinct steroid responsive chronic fibro-inflammatory diseases of the pancreas, called type 1 and type 2 autoimmune pancreatitis (AIP). We review recent progress in this field.

RECENT FINDINGS

It has recently been suggested that the term AIP be used to describe type 1 AIP and the term idiopathic duct-centric chronic pancreatitis (IDCP) be used for type 2 AIP. Clinical features and long-term outcomes of AIP and IDCP are well characterized and prognosis of both diseases is excellent. Diagnostic strategies tailored to regional practice patterns have emerged with the application of International Consensus Diagnostic Criteria for AIP. Although corticosteroids remain the mainstay of treatment, management of relapses and strategies for preventing multiple relapses are better understood, including the role of maintenance therapy and B-cell depletion therapy with rituximab. Association studies with malignancies have yielded conflicting results regarding risk of cancer in AIP.

SUMMARY

The treatment, follow-up guidelines and associations continue to evolve with our increasing experience with both AIP and IDCP. In AIP, rituximab can be used for both induction and maintenance of remission. IDCP responds to steroids without need for maintenance therapy. Both AIP and IDCP have excellent prognosis.

IgG4-related disease: case report and literature review

IgG4-related disease (IgG4-RD) is relatively a new growing entity of immune-mediated origin, characterized by a mass-forming lesion, the infiltration of IgG4-positive plasma cells and occasionally elevated serum IgG4. It is considered to be both a systemic inflammation and sclerosing disease. The most common manifestations are parotid and lacrimal swelling, lymphadenopathy and autoimmune pancreatitis. Sclerosing cholangitis and retroperitoneal fibrosis are among the other mentioned frequent manifestations. The diagnosis should be approved histo-pathologically but other conditions such as lymphoma should be carefully excluded. Patients with IgG4-RD respond beneficially to glucocorticoid therapy especially when given at early onset stages. In some cases, the combination of immunosuppressive agents is required.

Recent Advances in Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis that is characterized clinically by frequent presentation with obstructive jaundice, histologically by a dense lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to corticosteroid therapy. Two distinct diseases, type 1 and type 2 AIP, share these features. However, these 2 diseases have unique pancreatic histopathologic patterns and differ significantly in their demographic profiles, clinical presentation, and natural history. Recognizing the popular and long-standing association of the term "AIP" with what is now called "type 1 AIP," we suggest using "AIP" solely for type 1 AIP and to acknowledge its own distinct disease status by using "idiopathic duct-centric chronic pancreatitis" (IDCP) for type 2 AIP. AIP is the pancreatic manifestation of immunoglobulin G4-related disease (IgG4-RD). The etiopathogenesis of AIP and IgG4-RD is largely unknown. However, the remarkable effectiveness of B-cell depletion therapy with rituximab in patients with AIP and IgG4-RD highlights the crucial role of B cells in its pathogenesis. IDCP is less commonly recognized, and little is known about its pathogenesis. IDCP has no biomarker but is associated with inflammatory bowel disease in ~25% of patients. Recently, the international consensus diagnostic criteria for AIP identified combinations of features that are diagnostic of both diseases. Both AIP and IDCP are corticosteroid responsive; however, relapses are common in AIP and rare in IDCP. Therefore, maintenance therapy with either an immunomodulator (eg, azathioprine, 6-mercaptopurine, or mycophenolate mofetil) or rituximab is often necessary for patients with AIP. Long-term survival is excellent for both patients with AIP and patients with IDCP.

The changing faces of IgG4-related disease: Clinical manifestations and pathogenesis

Since the earliest reports in 2001, immunoglobulin G4 (IgG4)-related disease has been defined as an autoimmune systemic disease characterized by the lymphoplasmacytic infiltration of affected tissues leading to fibrosis and obliterative phlebitis along with elevated serum IgG4 levels. Prior to this unifying hypothesis, a plethora of clinical manifestations were considered as separate entities despite the similar laboratory profile. The pathology can be observed in virtually all organs and may thus be a challenging diagnosis, especially when the adequate clinical suspicion is not present or when obtaining a tissue biopsy is not feasible. Nonetheless, the most frequently involved organs are the pancreas and exocrine glands but these may be spared. Immunosuppressants lead to a prompt clinical response in virtually all cases and prevent histological sequelae and, as a consequence, an early differential diagnosis from other conditions, particularly infections and cancer, as well as an early treatment should be pursued. We describe herein two cases in which atypical disease manifestations were observed, i.e., one with recurrent neck lymph node enlargement and proptosis, and one with jaundice. Our understanding of the pathogenesis of IgG4-related disease is largely incomplete but data support a significant role for Th2 cytokines with the contribution of innate immunity factors such as Toll-like receptors, macrophages and basophils. Further, macrophages activated by IL4 overexpress B cell activating factors and contribute to chronic inflammation and the development of fibrosis. We cannot rule out the possibility that the largely variable disease phenotypes reflect different pathogenetic mechanisms and the tissue microenvironment may then contribute to the organ involvement.

Immunology of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition that derives its name from the characteristic finding of abundant IgG4(+) plasma cells in affected tissues, as well as the presence of elevated serum IgG4 concentrations in many patients. In contrast to fibrotic disorders, such as systemic sclerosis or idiopathic pulmonary fibrosis in which the tissues fibrosis has remained largely intractable to treatment, many IgG4-RD patients appear to have a condition in which the collagen deposition is reversible. The mechanisms underlying this peculiar feature remain unknown, but the remarkable efficacy of B cell depletion in these patients supports an important pathogenic role of B cell/T cell collaboration. In particular, aberrant T helper type 2 (Th2)/regulatory T cells sustained by putative autoreactive B cells have been proposed to drive collagen deposition through the production of profibrotic cytokines, but definitive demonstrations of this hypothesis are lacking. Indeed, a number of unsolved questions need to be addressed in order to fully understand the pathogenesis of IgG4-RD. These include the identification of an antigenic trigger(s), the implications (if any) of IgG4 antibodies for pathophysiology and the precise immunological mechanisms leading to fibrosis. Recent investigations have also raised the possibility that innate immunity might precede adaptive immunity, thus further complicating the pathological scenario. Here, we aim to review the most recent insights on the immunology of IgG4-RD, focusing on the relative contribution of innate and adaptive immune responses to the full pathological phenotype of this fibrotic condition. Clinical, histological and therapeutic features are also addressed.

Decreased Expression of Innate Immunity-Related Genes in Peripheral Blood Mononuclear Cells from Patients with IgG4-Related Disease

Background

IgG4-related disease (IgG4-RD) is a new clinical entity of unknown etiology characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. Although aberrancies in acquired immune system functions, including increases in Th2 and Treg cytokines observed in patients with IgG4-RD, its true etiology remains unclear. To investigate the pathogenesis of IgG4-RD, this study compared the expression of genes related to innate immunity in patients with IgG4-RD and healthy controls.

Materials and Methods

Peripheral blood mononuclear cells (PBMCs) were obtained from patients with IgG4-RD before and after steroid therapy and from healthy controls. Total RNA was extracted and DNA microarray analysis was performed in two IgG4-RD patients to screen for genes showing changes in expression. Candidate genes were validated by real-time RT-PCR in 27 patients with IgG4-RD and 13 healthy controls.

Results

DNA microarray analysis identified 21 genes that showed a greater than 3-fold difference in expression between IgG4-RD patients and healthy controls and 30 genes that showed a greater than 3-fold change in IgG4-RD patients following steroid therapy. Candidate genes related to innate immunity, including those encoding Charcot–Leyden crystal protein (CLC), membrane-spanning 4-domain subfamily A member 3 (MS4A3), defensin alpha (DEFA) 3 and 4, and interleukin-8 receptors (IL8R), were validated by real-time RT-PCR. Expression of all genes was significantly lower in IgG4-RD patients than in healthy controls. Steroid therapy significantly increased the expression of DEFA3, DEFA4 and MS4A3, but had no effect on the expression of CLC, IL8RA and IL8RB.

Conclusions

The expression of genes related to allergy or innate immunity, including CLC, MS4A3, DEFA3, DEFA4, IL8RA and IL8RB, was lower in PBMCs from patients with IgG4-RD than from healthy controls. Although there is the limitation in the number of patients applied in DNA microarray, impaired expression of genes related to innate immunity may be involved in the pathogenesis of IgG4-RD as well as in abnormalities of acquired immunity.

Prohibitin Is Involved in Patients with IgG4 Related Disease

Objective

IgG4-related disease (IgG4-RD) is a chronic systemic disease involved in many organs and tissues. As only limited autoantigens have been found since the beginning of this century, the aim of this study was to reveal new candidate autoantigens of IgG4-RD.

Methods

Multiple cell lines including HT-29, EA.hy926, HEK 293 and HepG2 were used to test the binding ability of circulating autoantibodies from IgG4-RD sera. The amino-acid sequence was then analyzed by matrix-assisted laser desorption/ionization time-of-flight tandem (MALDI-TOF/TOF) mass spectrometry. After the cloning and expression of recombinant putative autoantigen in a bacterial expression system, the corresponding immuno assay was set up and utilized to observe the prevalence of serum autoantibodies in a large set of confirmed clinical samples.

Results

One positive autoantigen was identified as prohibitin. ELISA analysis showed that a majority of patients with IgG4-RD have antibodies against prohibitin. Anti-prohibitin antibodies were present in the sera of patients with definite autoimmune pancreatitis (25/34; 73.5%), Mikulicz’s disease (8/15; 53.3%), retroperitoneal fibrosis (6/11; 54.5%), other probable IgG4-RD (26/29; 89.7%) and Sjögren’s syndrome (4/30; 13.3%) but not in apparently healthy donors (1/70; 1.4%).

Conclusions

An association between prohibitin and patients with some IgG4-RD was observed, although the results were quite heterogeneous among different individuals within autoimmune pancreatitis, Mikulicz’s disease and retroperitoneal fibrosis.

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.

[Autoimmune pancreatitis]

Autoimmune pancreatitis is a benign fibroinflammatory disease of the pancreas of probable autoimmune origin, which includes 2 different phenotypes: type 1 (lymphoplasmacytic sclerosing pancreatitis) and type 2 (idiopathic duct-centric pancreatitis). Its clinical presentation as obstructive jaundice in patients with a pancreatic mass is common and therefore it must be included in the differential diagnosis of pancreatic neoplasia. Many diagnostic criteria have been described throughout history. The most famous are the HISORT criteria of the Mayo Clinic and the international consensus criteria of 2011. One of the main features of autoimmune pancreatitis is its dramatic response to steroid therapy, without the need for surgical treatment. Knowledge of this disease can dramatically change the management of patients with obstructive jaundice, who would otherwise be subjected to a pancreaticoduodenectomy.

Comparison of neutrophil infiltration between type 1 and type 2 autoimmune pancreatitis

BACKGROUND

Characteristics of type 2 autoimmune pancreatitis (AIP) is granulocyte epithelial lesions, called idiopathic duct-centric pancreatitis (IDCP). To clarify pathogenesis of IDCP, we investigated mechanism of neutrophil infiltration in type 1 AIP, called lymphoplasmacytic sclerosing pancreatitis (LPSP) and IDCP.

METHOD

This study was performed on resected pancreata from patients with alcoholic chronic pancreatitis (ACP, n = 10), LPSP (n = 10) and IDCP (n = 12). The number of neutrophils around the pancreatic ducts was counted. The expression of neutrophils chemoattractants granulocyte chemotactic protein-2 (GCP-2) and interleukin-8 (IL-8) in the pancreatic duct epithelia was examined using immunohistochemistry. The cell staining intensity is scored as negative (0), weak (1), moderate (2) or strong (3).

RESULTS

The median number of neutrophils around the interlobular pancreatic ducts was significantly higher in IDCP (15.16; interquartile range [IQR]: 9.74-18.41) than in ACP (2.66; IQR: 1.33-4.33) (P < 0.05) and LPSP (3.16; IQR: 2.74-4.57) (P < 0.01). There was no significant difference in the median number of neutrophils around the intralobular pancreatic ducts among ACP (1.16; IQR: 0.33-3.41), LPSP (3.16; IQR: 0.74-5.5) and IDCP (3.00; IQR: 1.08-7.91). The median score of GCP-2 in the interlobular pancreatic duct epithelia was significantly higher in IDCP (1.5; IQR: 0.25-2) than in ACP (0; IQR: 0-0.75) (P < 0.05) and LPSP (0; IQR: 0-0.75) (P < 0.05). There was no significant difference in the median score of IL-8 in the interlobular pancreatic duct epithelia among ACP (0; IQR: 0-0.75), LPSP (1; IQR: 0-1.75) and IDCP (0.5; IQR: 0-1).

CONCLUSIONS

Significantly increased neutrophil infiltration around the interlobular pancreatic duct in IDCP may depend on GCP-2.

Incretin-based therapies and acute pancreatitis risk: a systematic review and meta-analysis of observational studies

Concerns raised by several animal studies, case reports, and pharmacovigilance warnings over incretin-based therapy potentially exposing type two diabetes patients to an elevated risk of pancreatitis have cast a shadow on the overall safety of this class of drugs. This systematic review evaluates the data from observational studies that compared treatment with or without incretins and the risk of pancreatitis. We searched PubMed for publications with the key terms incretins or GLP-1 receptor agonists or DPP-4 inhibitors or sitagliptin or vildagliptin or saxagliptin or linagliptin or alogliptin or exenatide or liraglutide AND pancreatitis in the title or abstract. Studies were evaluated against the following criteria: design (either cohort or case-control); outcome definition (incidence of pancreatitis); exposure definition (new or current or past incretins users); and comparison between patients receiving incretins or not for type 2 diabetes. Two authors independently selected the studies and extracted the data. Six studies meeting the inclusion criteria were reviewed. No difference was found in the overall risk of pancreatitis between incretin users and non-users (odds ratio 1.08; 95 % CI [0.84-1.40]). A risk increase lower than 35 % cannot be excluded according to the power calculation. This systematic review and meta-analysis suggests that type 2 diabetes patients receiving incretin-based therapy are not exposed to an elevated risk of pancreatitis. Limitations of this analysis are the low prevalence of incretin users and the lack of a clear distinction by the studies between therapy with DPP-4 inhibitors or with GLP-1 receptor agonists.

IgG4-related autoimmune diseases: Polymorphous presentation complicates diagnosis and treatment

BACKGROUND

IgG4-associated autoimmune diseases are systemic diseases affecting multiple organs of the body. Autoimmune pancreatitis, with a prevalence of 2.2 per 100,000 people, is one such disease. Because these multi-organ diseases present in highly variable ways, they were long thought just to affect individual organ systems. This only underscores the importance of familiarity with these diseases for routine clinical practice.

METHODS

This review is based on pertinent articles retrieved by a selective search in PubMed, and on the published conclusions of international consensus conferences.

RESULTS

The current scientific understanding of this group of diseases is based largely on case reports and small case series; there have not been any randomized controlled trials (RCTs) to date. Any organ system can be affected, including (for example) the biliary pathways, salivary glands, kidneys, lymph nodes, thyroid gland, and blood vessels. Macroscopically, these diseases cause diffuse organ swelling and the formation of pseudotumorous masses. Histopathologically, they are characterized by a lymphoplasmacytic infiltrate with IgG4-positive plasma cells, which leads via an autoimmune mechanism to the typical histologic findings--storiform fibrosis ("storiform" = whorled, like a straw mat) and obliterative, i.e., vessel-occluding, phlebitis. A mixed Th1 and Th2 immune response seems to play an important role in pathogenesis, while the role of IgG4 antibodies, which are not pathogenic in themselves, is still unclear. Glucocorticoid treatment leads to remission in 98% of cases and is usually continued for 12 months as maintenance therapy. Most patients undergo remission even if untreated. Steroid-resistant disease can be treated with immune modulators.

CONCLUSION

IgG4-associated autoimmune diseases are becoming more common, but adequate, systematically obtained data are now available only from certain Asian countries. Interdisciplinary collaboration is a prerequisite to proper diagnosis and treatment. Treatment algorithms and RCTs are needed to point the way to organ-specific treatment in the future.

A non-invasive screening technique for type 1 autoimmune pancreatitis

Introduction

Type 1 autoimmune pancreatitis (AIP) is the pancreatic manifestation of a systemic fibroinflammatory IgG4-related disease. Accurate diagnosis of AIP can avoid major hepatobiliary and pancreatic surgery as it respond dramatically to corticosteroid therapy.

Aim

This research investigated the feasibility of using peripheral blood cell immunohistochemistry, serum IgG4, T-cell receptor (TCR) and serum isoelectric focusing electrophoresis in the screening of type 1 autoimmune pancreatitis (AIP).

Material and methods

The peripheral blood from 3 type 1 AIP patients, 10 pancreatic cancer patients and 40 normal controls was collected. Sediment smears were jointly incubated with anti-IgG4 and anti-IgG. The percentage of IgG4/IgG positive cells was counted and serum TCR and IgG4 were detected through the whole process. After serum isoelectric focusing electrophoresis, anti-IgG4 and anti-IgG were used to confirm the components of serum.

Results

In the serum isoelectric focusing electrophoresis, IgG4 and IgG strips showed mirrored distribution in type 1 AIP patients, while there were no strips in the normal controls and pancreatic cancer. Compared with pancreatic tumor patients and healthy controls, serum TCR was significant increased in AIP. The percentage of IgG4/IgG positive cells of peripheral blood cell immunohistochemistry was related to serum IgG4 and hormone therapy reactions.

Conclusions

Peripheral blood cell immunohistochemistry, serum IgG4, TCR and serum isoelectric focusing electrophoresis is suitable for the screening of type 1 AIP and monitoring its response assessment.

The diagnostic utility of serum IgG4 concentrations in IgG4-related disease

OBJECTIVES

We evaluated the sensitivity, specificity and positive and negative predictive values of elevated serum IgG4 concentrations for the diagnosis of IgG4-RD.

METHODS

Between 2001 and 2011, 190 unique patients had elevated serum IgG4 measurements. We reviewed electronic medical records to determine the indication for IgG4 measurement and underlying clinical diagnosis. Additionally, we reviewed the records of 190 other randomly selected patients from a pool of 3360 with normal results, to evaluate test characteristics of the IgG4 measurement.

RESULTS

Among 380 patients analysed, 72 had either probable or definite IgG4-RD. Sixty-five of the 72 IgG4-RD patients had elevated serum IgG4 concentrations (mean: 405 mg/dL; range 140-2000 mg/dL), for a sensitivity of 90%. Among the 308 subjects without IgG4-RD, 125 had elevated IgG4 (mean: 234 mg/dL; range 135-1180 mg/dL) and 183 had normal IgG4 concentrations, for a specificity of 60%. The negative predictive value of a serum IgG4 assay was 96%, but the positive predictive value only 34%. Analysis of the serum IgG4/total IgG ratio did not improve these test characteristics. Doubling the cutoff for IgG4 improved specificity (91%) but decreased sensitivity to 35%.

DISCUSSION

Multiple non-IgG4-RD conditions are associated with elevated serum IgG4, leading to poor specificity and low positive predictive value for this test. A substantial subset of patients with biopsy-proven IgG4-RD do not have elevated serum IgG4. Neither doubling the cutoff for serum IgG4 nor examining the serum IgG4/IgG ratio improves the overall test characteristics for the diagnosis of IgG4-RD.

Roles of Commensal Microbiota in Pancreas Homeostasis and Pancreatic Pathologies

The pancreas plays a central role in metabolism, allowing ingested food to be converted and used as fuel by the cells throughout the body. On the other hand, the pancreas may be affected by devastating diseases, such as pancreatitis, pancreatic adenocarcinoma (PAC), and diabetes mellitus (DM), which generally results in a wide metabolic imbalance. The causes for the development and progression of these diseases are still controversial; therefore it is essential to better understand the underlying mechanisms which compromise the pancreatic homeostasis. The interest in the study of the commensal microbiome increased extensively in recent years, when many discoveries have illustrated its central role in both human physiology and maintenance of homeostasis. Further understanding of the involvement of the microbiome during the development of pathological conditions is critical for the improvement of new diagnostic and therapeutic approaches. In the present review, we discuss recent findings on the behavior and functions played by the microbiota in major pancreatic diseases and provide further insights into its potential roles in the maintenance of pancreatic steady-state activities.

[Helicobacter pylori infection and extragastroduodenal diseases]

At present, the clinical significance of Helicobacter pylori infection has been validly determined within the development of a diversity of gastroduodenal diseases, including chronic gastritis, gastroduodenal ulcer, MALT lymphoma, and gastric adenocarcinoma. The Expert Council's Maastricht IV consensus (2010) determining international standards for the diagnosis and treatment of H. pylori infection is that there is evidence that the latter may be associated with the development of a number of extragastroduodenal diseases (EGDDs) presented by iron-deficiency anemia of unspecified etiology, idiopathic thrombocytopenic purpura, and vitamin B12 deficiency. In these diseases, it is recommended that infection with H. pylori be diagnosed and, if the test is positive, this microorganism be eradicated. A large number of investigations have been recently conducted to examine the association of H. pylori infection with other EGDDs. This paper reviews theoretical and epidemiological data on the association of H. pylori with diseases of the cardiovascular (atherosclerosis, myocardial infarction) and central nervous (Alzheimer's disease, Parkinson's disease) systems, pancreas (autoimmune pancreatitis, pancreatic cancer), oncological (colonic adenomas, colorectal cancer, hepatocellular carcinoma), dermatological (chronic spontaneous urticaria), and other EGDDs. The review highlights the potential protective role of H. pylori in diseases with the atopic element of genesis and a complicated course of gastroesophageal reflux disease (Barrett's esophagus, esophageal adenocarcinoma).

Crossreactive autoantibodies directed against cutaneous and joint antigens are present in psoriatic arthritis

Background

Psoriatic arthritis (PsA) is a chronic inflammatory disease of unknown origin, characterized by erosions and new bone formation. Diagnosis of PsA is mainly clinical and there are no biomarkers available. Moreover in PsA autoantibodies have not been described so far. Indeed an autoimmune origin has been suggested but never proven. Aim of the study was to investigate the possible presence of autoantibodies typically associated with PsA.

Methods

We used pooled IgG immunoglobulins derived from 30 patients with PsA to screen a random peptide library in order to identify disease relevant autoantigen peptides.

Results

Among the selected peptides, one was recognised by nearly all the patients’ sera. The identified peptide (PsA peptide: TNRRGRGSPGAL) shows sequence similarities with skin autoantigens, such as fibrillin 3, a constituent of actin microfibrils, desmocollin 3, a constituent of the desmosomes and keratin 78, a component of epithelial cytoskeleton. Interestingly the PsA peptide shares homology with the nebulin-related anchoring protein (N-RAP), a protein localized in the enthesis (point of insertion of a tendon or ligament to the bone), which represents the first affected site during early PsA. Antibodies affinity purified against the PsA peptide recognize fibrillin, desmocollin, keratin and N-RAP. Moreover antibodies directed against the PsA peptide are detectable in 85% of PsA patients. Such antibodies are not present in healthy donors and are present in 13/100 patients with seroposive rheumatoid arthritis (RA). In seronegative RA these antibodies are detectable only in 3/100 patients.

Conclusions

Our results indicate that PsA is characterized by the presence of serum autoantibodies crossreacting with an epitope shared by skin and joint antigens.

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.

The emerging mysteries of IgG4-related disease

IgG4-related disease (IgG4-RD) is increasingly recognised in Western societies as a multi-system, inflammatory, fibrosing disease of unknown aetiology that typically, though not exclusively, presents in older men. The clinical manifestations are diverse and almost any organ may be affected. The cardinal histological features are a lymphoplasmacytic infiltrate, storiform fibrosis, obliterative phlebitis and an abundance of IgG4+ plasma cells in affected organs. Serum IgG4 levels are elevated in approximately 70% of patients and are a useful biomarker when present. IgG4-RD is frequently misdiagnosed as malignancy. Making the correct diagnosis is important as the disease is usually steroid responsive, although relapse rates are high. Second-line immunosuppressive agents and B-cell depletion therapy have also been used in retreatment strategies. Recent data suggests that the disease is associated with both progressive organ failure and malignancy. The biological mechanisms driving IgG4-RD remain unclear but this is currently an area of intense scientific investigation. Broadly, IgG4+ B cells are thought to exhibit a regulatory phenotype, but it is not known if these are pathogenic or simply represent a bystander effect. Extending our understanding of the role of IgG4 immunoglobulins in health and disease, the assessment of B and T cell immune phenotype, and large genetic studies of IgG4-RD may enhance our understanding of disease pathogenesis. Ultimately it may be that there is not a single, simple unifying aetiology and so careful stratification of disease by clinical phenotype will be required in multi-centre prospective clinical cohorts. These cohorts will also be essential for the study of treatment outcomes with novel therapies.

Helicobacter pylori and pancreatic diseases

A possible role for Helicobacter pylori (H. pylori) infection in pancreatic diseases remains controversial. H. pylori infection with antral predomination leading to an increase in pancreatic bicarbonate output and inducing ductal epithelial cell proliferation could contribute to the development of pancreatic cancer via complex interactions with the ABO genotype, dietary and smoking habits and N-nitrosamine exposure of the host. Although the individual study data available so far is inconsistent, several meta-analyses have reported an increased risk for pancreatic cancer among H. pylori seropositive individuals. It has been suggested that H. pylori causes autoimmune pancreatitis due to molecular mimicry between H. pyloriα-carbonic anhydrase (α-CA) and human CA type II, and between H. pylori plasminogen-binding protein and human ubiquitin-protein ligase E3 component n-recognin 2, enzymes that are highly expressed in the pancreatic ductal and acinar cells, respectively. Future studies involving large numbers of cases are needed in order to examine the role of H. pylori in autoimmune pancreatitis more fully. Considering the worldwide pancreatic cancer burden, as well as the association between autoimmune pancreatitis and other autoimmune conditions, a complete elucidation of the role played by H. pylori in the genesis of such conditions could have a substantial impact on healthcare.

A systematic review of acute pancreatitis as an adverse event of type 2 diabetes drugs: from hard facts to a balanced position

The question whether antidiabetes drugs can cause acute pancreatitis dates back to the 1970s. Recently, old concerns have re-emerged following claims that use of incretins, a new class of drugs for type 2 diabetes, might increase the relative risk of acute pancreatitis up to 30-fold. Given that diabetes is per se a potent risk factor for acute pancreatitis and that drug-related acute pancreatitis is rare and difficult to diagnose, we searched the medical databases for information linking acute pancreatitis and type 2 diabetes drugs. Among the biguanides, both phenformin and metformin (the latter in patients with renal insufficiency) have been cited in case reports as a potential cause of acute pancreatitis. Sulphonylureas, as both entire class and single compound (glibenclamide), have also been found in cohort studies to increase its risk. No direct link was found between pancreatic damage and therapy with metaglinide, acarbose, pramlintide or SGLT-2 inhibitors. In animal models, thiazolinediones have demonstrated proprieties to attenuate pancreatic damage, opening perspectives for their use in treating acute pancreatitis in humans. Several case reports and the US Food and Drug Administration pharmacovigilance database indicate an association between acute pancreatitis and incretins, dipeptidyl peptidase-4 (DPP-4) inhibitors, and GLP-1 receptor agonists. To date, however, a clear-cut odds ratio for this association has been reported in only one of eight pharmacoepidemiological studies. Finally, none of the intervention trials investigating these compounds, including two large randomized controlled trials with cardiovascular endpoints, confirmed the purportedly increased risk of acute pancreatitis with incretin use.

Republished: recent advances in autoimmune pancreatitis: type 1 and type 2

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis characterised clinically by frequent presentation with obstructive jaundice, histologically by a lymphoplasmacytic infiltrate with fibrosis, and therapeutically by a dramatic response to steroids. When so defined, AIP can be sub-classified into two subtypes, 1 and 2. Recent international consensus diagnostic criteria for AIP have been developed for diagnosis of both forms of AIP. Type 1 AIP is the pancreatic manifestation of a multiorgan disease, recently named IgG4-related disease. Little is known about the pathogenesis of either form of AIP. Despite frequent association of type 1 AIP with elevated serum IgG4 levels and infiltration with IgG4-positive plasma cells, it is unlikely that IgG4 plays a pathogenic role in AIP. Type 1 AIP responds to steroids, but there needs to be consensus on treatment regimens for induction and therapeutic end points. Relapses are common, but can be reduced by long-term use of low-dose steroids. Recent reports suggest that immunomodulators (azathioprine, 6-mercaptopurine and mycophenolate mofetil), as well biological agents (the antibody to CD20, rituximab) may have a role in maintaining remission in relapsing type 1 AIP. Future studies should clarify the best management options for treatment of relapses and maintenance of remission. Type 2 AIP is a pancreas-specific disorder not associated with IgG4. It presents in younger individuals equally with obstructive jaundice and pancreatitis. The inflammatory process responds to steroid therapy; relapses are uncommon. The clinical spectrum and long-term outcomes of medically treated type 2 AIP are still being evaluated.

Recent advances in the concept and pathogenesis of IgG4-related disease in the hepato-bilio-pancreatic system

Recent studies have proposed nomenclatures of type 1 autoimmune pancreatitis (AIP) (IgG4-related pancreatitis), IgG4-related sclerosing cholangitis (IgG4-SC), IgG4-related cholecystitis, and IgG4-related hepatopathy as IgG4-related disease (IgG4-RD) in the hepato-bilio-pancreatic system. In IgG4-related hepatopathy, a novel concept of IgG4-related autoimmune hepatitis (AIH) with the same histopathological features as AIH has been proposed. Among organs involved in IgG4-RD, associations with pancreatic and biliary lesions are most frequently observed, supporting the novel concept of “biliary diseases with pancreatic counterparts.” Targets of type 1 AIP and IgG4-SC may be periductal glands around the bile and pancreatic ducts. Based on genetic backgrounds, innate and acquired immunity, Th2-dominant immune status, regulatory T (Treg) or B cells, and complement activation via a classical pathway may be involved in the development of IgG4-RD. Although the role of IgG4 remains unclear in IgG4-RD, IgG4-production is upregulated by interleukin 10 from Treg cells and by B cell activating factor from monocytes/basophils with stimulation of toll-like receptors/nucleotide-binding oligomerization domain-like receptors. Based on these findings, we have proposed a hypothesis for the development of IgG4-RD in the hepato-bilio-pancreatic system. Further studies are necessary to clarify the pathogenic mechanism of IgG4-RD.

IgG4- related disease: an orphan disease with many faces

Immunoglobulin G4- related disease (IgG4-RD) is a rare systemic fibro-inflammatory disorder (ORPHA284264). Although patients have been described more than 100 years ago, the systemic nature of this disease has been recognized in the 21^st century only. Type 1 autoimmune pancreatitis is the most frequent manifestation of IgG4-RD. However, IgG4-RD can affect any organ such as salivary glands, orbits, retroperitoneum and many others. Recent research enabled a clear clinical and histopathological description of IgG4-RD. Typically, lymphoplasmacellular inflammation, storiform fibrosis and obliterative phlebitis are found in IgG4-RD biopsies and the tissue invading plasma cells largely produce IgG4. Elevated serum IgG4 levels are found in many but not all patients. Consequently, diagnostic criteria for IgG4-RD have been proposed recently. Treatment is largely based on clinical experience and retrospective case series. Glucocorticoids are the mainstay of therapy, although adjunctive immunosuppressive agents are used in relapsing patients. This review summarizes current knowledge on clinical manifestations, pathophysiology and treatment of IgG4-RD.

IgG4-related disease and its pathogenesis-cross-talk between innate and acquired immunity

IgG4-RD, a novel disease involving many immune-system components

IgG4-related disease (IgG4-RD) is a novel clinical entity proposed in Japan in the 21th century and is attracting strong attention over the world. The characteristic manifestations of IgG4-RD are increased serum IgG4 concentration and tumefaction by IgG4⁺ plasma cells. Although the clinical manifestations in various organs have been established, the pathogenesis of IgG4-RD is still unknown. Recently, many reports of aberrant acquired immunity such as T_h2-diminated immune responses have been published. However, many questions still remain, including questions about the pathogenesis of IgG4-RD and the roles of IgG4. In this review, we discuss the pathogenesis of IgG4-RD by focusing on the cross-talk between innate and acquired immunity.

Autoimmune pancreatitis: pathogenesis, latest developments and clinical guidance

Recently, autoimmune pancreatitis has been classified into two subtypes. Type 1 is related to immunoglobulin G4 and type 2 is related to granulocytic epithelial lesions, but pathogenetic mechanisms in both still remain unclear. Apart from type 2 autoimmune pancreatitis, the pathological features of type 1 autoimmune pancreatitis with increased serum immunoglobulin G4/immunoglobulin E levels, abundant infiltration of immunoglobulin G4+plasmacytes and lymphocytes, fibrosis, and steroid responsiveness are suggestive of abnormal immunity such as allergy or autoimmunity. Although pathophysiological conditions seem to be different in each, both respond well to steroid drugs. After remission, the patients with type 1 autoimmune pancreatitis show high relapse rates (30-50% within 6-12 months), whereas those with type 2 autoimmune pancreatitis seldom relapse. After remission, the steroid maintenance therapy and therapeutic strategy for relapsing patients with type 1 is different among local expertise. In this paper, recent advances in pathogenesis and clinical guidance for therapy are discussed.

Recent advances in the diagnosis and management of autoimmune pancreatitis

OBJECTIVE

Autoimmune pancreatitis (AIP) is a rare chronic relapsing steroid-responsive fibroinflammatory disorder of the pancreas that is likely caused by immune dysregulation. It is now thought that AIP consists of two distinct clinicopathologic syndromes currently designated as types 1 and 2.

CONCLUSION

A current update on etiopathogenesis, pathology, and clinical and imaging findings of AIP is provided with an emphasis on diagnosis and management.