Allergic manifestations in autoimmune pancreatitis

Isolated IgG4 related disease of the trachea

IgG4 related disease (IgG4-RD) is a multisystem inflammatory disease and can affect several organs including salivary glands, orbits, lungs, pancreas, kidneys and lymph nodes. Up to 40 % of patients have allergic manifestations including asthma, chronic rhinosinusitis, eczema and asthma. Commonly pulmonary manifestations include pulmonary nodules ranging from <1 to 5 cm in diameter, interstitial opacities and mediastinal lymphadenopathy. Rarely, IgG4-RD presents as isolated tracheal disease. Symptoms include dyspnea and stridor due to airway narrowing. Diagnosis of IgG4-RD including tracheal IgG4-RD requires a biopsy. The histologic specimen is characterized by lymphoplasmacytic infiltrate with high density of IgG4 positive plasma cells, and storiform fibrosis (a cartwheel appearance of fibroblasts and inflammatory cells). Up to 30 % of patients with IgG4-RD have normal serum IgG4 levels. The mainstay of therapy is glucocorticoids for those with systemic disease. Rituximab is an alternative for those who cannot tolerate glucocorticoids or those with disease recurrence. Patients with tracheal disease often require balloon dilation. Recurrence is common in patients and up to two thirds of patients have residual disease despite treatment. These patients often require surgical resection of affected area for symptomatic relief.

IgG4-related disease: an update on pathology and diagnostic criteria with a focus on salivary gland manifestations

Immunoglobulin G4-related disease (IgG4-RD) is a multi-organ disorder characterized by a highly variable clinical presentation depending on the affected organ/s, extent of tumefactive fibroinflammatory lesions, and associated functional impairment. The disease pursues a chronic, relapsing, often asymptomatic course and hence may pose a significant diagnostic challenge. Diagnostic delay can lead to progressive fibrosis and irreversible organ damage resulting into significant morbidity and even mortality. Given its broad clinical spectrum, physicians of all specialties may be the first clinicians facing this diagnostic challenge. Outside the pancreatobiliary system, the head and neck represents the major site of IgG4-RD with variable organ-specific diffuse or mass-forming lesions. In up to 75% of cases, elevated serum IgG4 levels are observed, but this figure possibly underestimates the fraction of seronegative cases, as the disease manifestations may present metachronously with significant intervals. Together with negative serology, this can lead to misdiagnosis of seronegative cases. A standardized nomenclature and diagnostic criteria for IgG4-RD were established in 2012 and revised in 2020 facilitating scientific research and expanding the range of diseases associated with IgG4 abnormalities. In addition to orbital pseudotumor, dacryoadenitis, Riedel thyroiditis, sinonasal manifestations, and rare miscellaneous conditions, IgG4-related sialadenitis is one of the most frequent presentations in the head and neck region. However, controversy still exists regarding the relationship between sialadenitis and IgG4-RD. This review focuses on the clinicopathological features of IgG4-related sialadenitis and its contemporary diagnostic criteria.

A Case of Castleman's Disease with a Marked Infiltration of IgG4-Positive Cells in the Renal Interstitium

Multicentric Castleman's disease (MCD) is a benign lymphoproliferative disorder with heterogenous clinical symptoms, and involves systemic organs in addition to lymph nodes. Herein, we present the case of a 55-year-old man with MCD characterized by an extensive infiltration of IgG4+ plasma cells in the kidneys. The patient presented to our hospital with a high fever and diarrhea. On admission, laboratory analysis revealed anemia, renal dysfunction (eGFR 30 mL/min/1.73 m2), polyclonal gammopathy (IgG 7130 mg/dL), elevated serum IgG4 level (2130 mg/dL), and increased C-reactive protein (8.0 mg/dL). An enlargement of lymph nodes in the axillary, mediastinal, para-aortic, and inguinal regions was observed on abdominal computed tomography. Axillary lymph node biopsy revealed interfollicular expansion due to dense plasma cell infiltration. Renal biopsy demonstrated significant plasma cell infiltration into the tubulointerstitium. Immunohistochemical analysis showed a 40% IgG4-positive/IgG-positive plasma cell ratio, meeting the diagnostic criteria for an IgG4-related disease. Amyloid A deposition was observed along vessel walls, and immunofluorescence analysis indicated granular positivity of IgG and C3 along the glomerular capillary wall. Elevated levels of interleukin-6 (21 pg/mL) and vascular endothelial growth factor (VEGF; 1210 pg/mL) were noted. Based on these findings, and the histological finding of the lymph node biopsy, idiopathic MCD was diagnosed. Corticosteroid monotherapy was only partially effective. Subsequently, tocilizumab administration was initiated, leading to sustained remission, even after discontinuation of prednisolone. Due to the diverse responses to steroid therapy and the varying prognoses observed in MCD and IgG4-related disease, it is essential to carefully diagnose MCD by thoroughly assessing the organ distribution of the disease, its response to steroid therapy, and any additional pathological findings.

Implication of allergy and atopy in IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a chronic multi-organic immune fibrosing disease. It affects preferentially men around middle age and almost any organs can be involved; however, lymph nodes, submandibular and lacrimal glands, pancreas, and retroperitoneum are the most affected. The mainstay treatment is corticosteroids, sometimes adjuncts with DMARDs or rituximab as steroid sparing agents. Th2 inflammation is implicated in the pathophysiology of the disease. Several reports indicate that allergy and/or atopy often affect patients with IgG4-RD. The frequency varies greatly between studies with allergies/allergic diseases reported in 18-76% while atopy is reported in 14-46%. In studies including both, they affect 42 and 62% of patients. Rhinitis and asthma are the most frequent allergic diseases. IgE and blood eosinophiles are often elevated and few studies report that basophils and mast cells could participate in the disease pathogenesis; however, the implication of allergy and atopy remain unclear. No common allergen has been identified and IgG4 production seems to be polyclonal. Although a direct causal effect is unlikely, they could potentially shape the clinical phenotype. Allergies/allergic diseases and/or atopy are reported to be more frequent in IgG4-RD patients presenting head, neck, and thoracic involvement, with higher IgE and eosinophils and less frequent in retroperitoneal fibrosis; however, studies regarding allergy and atopy in IgG4-RD are highly heterogenous. The aim of this article is to review what is currently known about the allergy and atopy in the context of Ig4-RD.

IgG4-related autoimmune liver disease

The term IgG4-related autoimmune liver disease (AILD) refers to hepato-biliary manifestations of Immunoglobin G4-related disease (IgG4-RD) including IgG4-related sclerosing cholangitis and IgG4-related pseudotumor. The association of some forms of autoimmune hepatitis to IgG4-RD remains controversial. Although autoimmune phenomena have not been clearly observed in IgG4-AILD, perturbation of the adaptive immune system and activation of the humoral response represent established pathophysiological hallmarks and potential therapeutic targets. Clinical manifestations of IgG4-AILD are virtually indistinguishable from bile duct cancer or primary sclerosing cholangitis and are due to mass forming lesions and thickening of the biliary tract that progressively lead to biliary ducts obstruction. There are no current reliable biomarkers for IgG4-AILD and diagnosis should rely on the integration of clinical, serological, radiological, and histological findings. In analogy to most IgG4-RD manifestations, and in contrast to its major mimickers, IgG4-AILD promptly responds to glucocorticoids but frequently relapses, thus requiring long-term maintenance therapy to avoid progressive fibrosclerotic disease and liver cirrhosis. Accumulating evidence on the efficacy of B-cell depletion therapy in patients with systemic IgG4-RD is gradually changing the treatment paradigm of IgG4-AILD and biologics will be increasingly used also for gastroenterological manifestations of IgG4-RD to spare glucocorticoids and traditional immunosuppressive agents. Looking ahead, identification of reliable biomarkers and of mini-invasive strategies to obtain informative biopsies from the biliary tree represent unavoidable priorities to optimize diagnosis and management of IgG4-AILD.

Autoimmune Pancreatitis: From Pathogenesis to Treatment

Autoimmune pancreatitis (AIP) is a rare disease. The diagnosis of AIP is difficult and should be made by a comprehensive evaluation of clinical, radiological, serological, and pathological findings. Two different types of AIP have been identified: autoimmune pancreatitis type 1 (AIP-1), which is considered a pancreatic manifestation of multiorgan disease related to IgG4, and autoimmune pancreatitis type 2 (AIP-2), which is considered a pancreas-specific disease not related to IgG4. Although the pathophysiological conditions seem to differ between type 1 and type 2 pancreatitis, both respond well to steroid medications. In this review, we focused on the pathogenesis of the disease to develop a tool that could facilitate diagnosis and lead to the discovery of new therapeutic strategies to combat autoimmune pancreatitis and its relapses. The standard therapy for AIP is oral administration of corticosteroids. Rituximab (RTX) has also been proposed for induction of remission and maintenance therapy in relapsing AIP-1. In selected patients, immunomodulators such as azathioprine are used to maintain remission. The strength of this review, compared with previous studies, is that it focuses on the clear difference between the two types of autoimmune pancreatitis with a clearly delineated and separate pathogenesis. In addition, the review also considers various therapeutic options, including biologic drugs, such as anti-tumor necrosis factor (TNF) therapy, a well-tolerated and effective second-line therapy for AIP type 2 relapses or steroid dependence. Other biologic therapies are also being explored that could provide a useful therapeutic alternative to corticosteroids and immunosuppressants, which are poorly tolerated due to significant side effects.

From Suspicion to Diagnosis: Analysis on the Clinical Characteristics of 37 Cases of IgG4-Related Disease (IgG4-RD) in Northeast China

Introduction

IgG4-related disease (IgG4-RD) mimics a variety of disorders, the final diagnosis is heavily dependent on the doctor’s familiarity with the disease, most patients are expected to get a good prognosis by early diagnosis and timely treatment.

Methods

Retrospective analysis was carried out on 147 patients tested for serum IgG4 because of suspected IgG4-RD. These cases were grouped as the IgG4-RD group and non-IgG4-RD group according to the diagnostic criteria proposed by the Japanese IgG4-RD research group and the American College of Rheumatology and the European Union of Rheumatology. Characteristics of these patients were investigated and analyzed.

Results

The onset age of IgG4-RD was 57.29 ± 14.03 years old, male to female ratio of IgG4-RD was 1.31:1. The most commonly affected organs were the pancreas (48.6%), lymph nodes (40.5%) and biliary tract (35.1%), the proportion of patients with simultaneous involvement of multiple organs is as high as 83.2%. A history of allergy is more common in IgG4-RD patients (32.4% vs 14.5%), the optimal critical value of serum IgG4/IgG ratio for diagnosis of IgG4-RD was 0.09 (sensitivity 94.7%, specificity 91.7%) and the optimal threshold for IgG diagnosis of IgG4-RD was 15.25g/L (sensitivity 73.7%, specificity 77.8%) in this study.

Conclusion

IgG4-RD is often manifested as multiple organ involvement, and is most likely to involve the pancreas, biliary tract and lymph nodes. Most patients were diagnosed in other departments instead of rheumatology. Serum IgG4 level, especially IgG4/IgG ratio has a higher predictive value for IgG4-RD. Early diagnosis is the key point to improve the prognosis.

T Cell Roles and Activity in Chronic Sclerosing Sialadenitis as IgG4-Related Disease: Current Concepts in Immunopathogenesis

IgG4-related disease is a multiorgan immunological fibroinflammatory disorder characterized by lymphoplasmacytic infiltration and fibrosis in multiple organs accompanied by high serum IgG4 levels. The salivary glands are the most common organs involved in this disease. Recently, chronic sclerosing sialadenitis affecting salivary glands, formerly known as Küttner's tumor, and Mikulicz's disease have been classified as a class of IgG4-related diseases. The etiopathobiology of IgG4-related disease is not fully understood. It has recently been hypothesized that the inflammatory and fibrotic process and the increased serum IgG4⁺ levels in IgG4-related disease are the result of an interaction between B cells and T helper cells, suggesting that T cells may play a key role in the pathogenesis of this disease. The aim of this review is to discuss the proposed roles of different T cell subsets in the pathogenesis of IgG4-related disease focusing on their roles in immunopathogenesis of IgG4-related sialadenitis.

The Clinical Utility of Soluble Serum Biomarkers in Autoimmune Pancreatitis: A Systematic Review

Autoimmune pancreatitis (AIP) is a rare etiological type of chronic pancreatitis. The clinical and radiological presentation of AIP often resembles that of pancreatic cancer. Identifying non-invasive markers for their early distinction is of utmost importance to avoid unnecessary surgery or a delay in steroid therapy. Thus, this systematic review was conducted to revisit all current evidence on the clinical utility of different serum biomarkers in diagnosing AIP, distinguishing AIP from pancreatic cancer, and predicting disease course, steroid therapy response, and relapse. A systematic review was performed for articles published up to August 2021 by searching electronic databases such as MEDLINE, Web of Science, and EMBASE. Among 5123 identified records, 92 studies were included in the qualitative synthesis. Apart from immunoglobulin (Ig) G4, which was by far the most studied biomarker, we identified autoantibodies against the following: lactoferrin, carboanhydrase II, plasminogen-binding protein, amylase-α2A, cationic (PRSS1) and anionic (PRSS2) trypsinogens, pancreatic secretory trypsin inhibitor (PSTI/SPINK1), and type IV collagen. The identified novel autoantigens were laminin 511, annexin A11, HSP-10, and prohibitin. Other biomarkers included cytokines, decreased complement levels, circulating immune complexes, N-glycan profile changes, aberrant miRNAs expression, decreased IgA and IgM levels, increased IgE levels and/or peripheral eosinophil count, and changes in apolipoprotein isoforms levels. To our knowledge, this is the first systematic review that addresses biomarkers in AIP. Evolving research has recognized numerous biomarkers that could help elucidate the pathophysiological mechanisms of AIP, bringing us closer to AIP diagnosis and its preoperative distinction from pancreatic cancer.

-IgE complex in patients with IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disease characterized by high IgE levels; however, the physiological significance of elevated IgE levels in patients with IgG4-RD is unclear. Previously, we reported the formation of IgG4-IgE complex in IgG4-RD patients with elevated IgE levels. In this study, we examined the frequency of this complex formation and its relationship with the clinical features in IgG4-RD patients.

METHODS

The IgG4-IgE complex was evaluated in 33 and 17 patients with and without IgG4-RD, respectively. The IgG4-IgE complex was evaluated by performing the immunoadsorption of IgG4 using anti-IgG4 antibody-conjugated matrices.

RESULTS

The frequency of IgG4-IgE complex formation in patients with IgG4-RD was significantly higher than that in those without IgG4-RD (21.2% vs. 0%). No significant differences were observed between the groups in terms of clinical characteristics and laboratory data. However, the IgG4-IgE complex-positive group had a significantly higher frequency of pancreatic lesions (85.7% vs. 42.3%) and a significantly lower rate of retroperitoneal fiber/periarterial lesions (0% vs. 38.5%) than the IgG4-IgE complex-negative group.

CONCLUSION

The IgG4-IgE complex was found only in patients with IgG4-RD which may provide some clues to the pathogenesis and etiology of IgG4-RD.

Autoimmune pancreatitis: What we know so far

Autoimmune pancreatitis (AIP) is a rare, often‐missed disease that involves inflammation of the pancreas and strictures of the pancreatic duct. Its prevalence and incidence in the United States remain scarce. The disease has a varied presentation and often mimics pancreatic malignancy, which can make the diagnosis challenging. Most patients have an excellent response to corticosteroid therapy. Immunomodulators may be used in some cases. Rituximab is an effective, emerging treatment in steroid‐refractory cases. This study aims to review the two distinct types of AIP and provide a detailed analysis of the diagnostic approach and treatment modalities.

Blue-collar work is a risk factor for developing IgG4-related disease of the biliary tract and pancreas

BACKGROUND & AIMS

Immunoglobulin G4-related disease (IgG4-RD) of the biliary tract and pancreas is a fibroinflammatory disease of unknown origin with striking male predominance. We aimed to investigate whether blue-collar work and occupational contaminant exposure are risk factors for IgG4-RD of the biliary tract and pancreas.

METHOD

We performed an age-/sex-matched case-control study in the largest academic medical centers of the Netherlands. Occupational history was surveyed by questionnaires. The International Standard Classification of Occupations (ISCO88) was used to classify jobs. Job exposure matrices ALOHA and DOM were utilized to assess the years individuals were exposed to compounds. The disease control cohort consisted of patients from 6 equally sized groups. Conditional logistic regression was used to assess effects of blue-collar work and exposure to occupational contaminants on developing IgG4-RD of the biliary tract and pancreas.

RESULTS

Overall, 101 patients with IgG4-RD of the biliary tract and pancreas were matched 1:3 to 303 controls. Patients with IgG4-RD had a lower level of education (p = 0.001). Individuals who at least once performed blue-collar work (>1 year), had higher odds of developing IgG4-RD than individuals that only performed white-collar work (odds ratio [OR] 3.66; CI 2.18-6.13; p <0.0001). Being ever exposed (>1 year) to industrial ALOHA (e.g. mineral dust; vapors-dust-gases-fumes) and DOM compounds (e.g. asbestos) resulted in higher odds of IgG4-RD (OR 2.14; 95% CI 1.26-3.16; p <0.001 and OR 2.95; 95% CI 1.78-4.90; p <0.001, respectively).

CONCLUSION

Blue-collar work is a risk factor for developing IgG4-RD of the biliary tract and pancreas putatively driven by exposure to selected industrial compounds; this may explain the striking male predominance among patients.

LAY SUMMARY

Immunoglobulin G4-related disease (IgG4-RD) causes tumor-like lesions and typically affects middle-aged to elderly men. The background and cause of this disease remain relatively unknown. In this study, we identified blue-collar work as a risk factor for developing IgG4-RD of the biliary tract and pancreas, which may explain the striking male predominance among patients. Furthermore, these results suggest that toxic exposure to occupational contaminants may drive autoimmunity in IgG4-RD of the biliary tract and pancreas.

Allergic manifestations in autoimmune gastrointestinal disorders

Allergic disorders target a young population, are increasing in both incidence and prevalence and are associated with significant disease burden. They result from the complex interplay between (epi)genetic and environmental factors, resulting in a Th2 inflammatory process targeting the epithelium of the respiratory tract (allergic rhinitis and asthma), skin (atopic dermatitis), and gastrointestinal tract (food allergy). Although the exact pathogenic mechanisms remain elusive, an altered immune system response in the gut is increasingly recognized as a relevant step. Allergic and gastrointestinal autoimmune disorders share several epidemiological, pathogenic and risk factors and several treatment modalities. Here we revise the current literature and show that allergic disorders are highly prevalent in gastrointestinal autoimmune diseases, including celiac disease, inflammatory bowel disease, autoimmune pancreatitis, and autoimmune cholangiopathies. No data are available for some autoimmune diseases, such as autoimmune gastritis and autoimmune enteropathy. To ensure the comprehensive care of patients with autoimmune gastrointestinal disorders, along with disease-specific factors, the presence of allergic disorders should be evaluated and treated when present, possibly targeting shared molecular pathways. Future studies are needed to define the exact pathogenic mechanisms underpinning the association between allergic and autoimmune diseases of the gastrointestinal tract.

Immune Dysregulation in IgG4-Related Disease

Immunoglobin G₄-related disease (IgG₄-RD) is one of the newly discovered autoimmune diseases characterized by elevated serum IgG₄ concentrations and multi-organ fibrosis. Despite considerable research and recent advances in the identification of underlying immunological processes, the etiology of this disease is still not clear. Adaptive immune cells, including different types of T and B cells, and cytokines secreted by these cells play a vital role in the pathogenesis of IgG₄-RD. Antigen-presenting cells are stimulated by pathogens and, thus, contribute to the activation of naïve T cells and differentiation of different T cell subtypes, including helper T cells (Th1 and Th2), regulatory T cells, and T follicular helper cells. B cells are activated and transformed to plasma cells by T cell-secreted cytokines. Moreover, macrophages, and some important factors (TGF-β, etc.) promote target organ fibrosis. Understanding the role of these cells and cytokines implicated in the pathogenesis of IgG₄-RD will aid in developing strategies for future disease treatment and drug development. Here, we review the most recent insights on IgG₄-RD, focusing on immune dysregulation involved in the pathogenesis of this autoimmune condition.

Allergic Aspects of IgG4-Related Disease: Implications for Pathogenesis and Therapy

IgG4-related disease (IgG4-RD) is a rare systemic fibroinflammatory disease frequently associated with allergy. The pathogenesis of IgG4-RD is poorly understood, and effective therapies are limited. However, IgG4-RD appears to involve some of the same pathogenic mechanisms observed in allergic disease, such as T helper 2 (Th2) and regulatory T cell (Treg) activation, IgG4 and IgE hypersecretion, and blood/tissue eosinophilia. In addition, IgG4-RD tissue fibrosis appears to involve activation of basophils and mast cells and their release of alarmins and cytokines. In this article, we review allergy-like features of IgG4-RD and highlight targeted therapies for allergy that have potential in treating patients with IgG4-RD.

IgG4 related lung disease- a rare and novel mimic of malignancy and infections-a case series of three patients with a brief review of updated literature

IgG4-related lung disease is an extremely rare and novel entity which is still poorly understood. We reviewed the 16 patients diagnosed with IgG4-related disease from October 2014 through December 2019 at our institution. The three cases that showed pulmonary involvement are included in this series. Of these, two patients had cavitary lung disease and developed aspergilloma and chronic cavitating aspergillosis after a prolonged course of steroid therapy, and one had isolated pulmonary nodule and ground glass opacity. We reviewed the updated literature and briefly described disease epidemiology, clinical characteristics, diagnostic approaches, and management strategies for IgG4-related lung disease.

IgG4-Related Disease and the Salivary Glands: A Review of Pathophysiology, Diagnosis, and Management

IgG4-related disease is a rare, immune-mediated, systemic disease that is characterized by soft tissue lymphocyte infiltration and resultant fibrosis. The salivary glands are among the most commonly affected organs. Patients present with subacute submandibular and/or parotid swelling and sialadenitis. Diagnosis incorporates clinical, serologic, radiologic, and pathologic findings. Most cases respond quickly to systemic glucocorticoids. IgG4-related disease mimics many infectious, inflammatory, and neoplastic diseases. Therefore, IgG4-related disease is frequently misdiagnosed. A knowledge of the pathophysiology, diagnosis, and management of IgG4-related disease is important for providers who treat salivary gland diseases.

Relapse predictors and serologically unstable condition of IgG4-related disease: a large Chinese cohort

OBJECTIVES

Patients with IgG4-related disease (IgG4-RD) typically respond well to initial glucocorticoid therapy, but always relapse with tapered or maintenance dosage of steroid. We aimed to identify the risk factors for relapse of IgG4-RD and explore the impact of active intervention on the serologically unstable condition.

METHODS

We performed a retrospective study of 277 IgG4-RD patients at Peking University People's Hospital from February 2012 through February 2019. They were all followed for >4 months. The primary outcome was patient relapse. Data on recurrence of IgG4-RD symptoms, laboratory and image findings were recorded, along with information on treatment in the serologically unstable condition.

RESULTS

The cumulative relapse rate was 12.86%, 27.84% and 36.1% at 12, 24 and 36 months, respectively. Younger age at onset, younger age at diagnosis, longer time from diagnosis to treatment and history of allergy were associated with relapse. Identified independent risk factors were longer time from diagnosis to treatment and history of allergy. When serum IgG4 level was 20%, 50% or 100% higher than that of the remission period, similar percentages of patients finally relapsed, regardless of whether they were in the immunosuppression intensified or non-intensified group. Median duration from serum IgG4 level instability to relapse in the intensified and non-intensified group was not statistically different.

CONCLUSION

The risk factors of relapse were longer time from diagnosis to treatment and history of allergy. Intervention in the serologically unstable condition was not helpful for reducing relapse rate.

IgG4-related disease manifesting as symptoms of appendicitis: Case report and literature review

Immunoglobulin G subclass 4 (IgG4)-related disease is a recently described fibroinflammatory condition. Reports of appendix involvement are extremely limited. A young man with abdominal pain and symptoms of acute appendicitis accompanied by the finding of an appendix-dependent tumor during surgery is presented. Histopathological study revealed lymphoplasmocytic infiltrate, storiform fibrosis and obliterative phlebitis. The number of IgG4-positive plasma cells was greater than 50 per high power field. Postsurgical steroid treatment and radiological findings are also described.

Mediastinal IgG4-Related Disease Manifesting as Superior Vena Cava Syndrome

Immunoglobulin G4 (IgG4)-related disease was first identified as a systemic condition in 2003 when extrapancreatic manifestations were identified in patients with autoimmune pancreatitis. Its peak incidence occurs in the fifth or sixth decades of life. Isolated extraaortic mediastinal involvement is extremely rare. This report describes a case of isolated extraaortic mediastinal IgG4-related disease encasing the superior vena cava (SVC) and manifesting as SVC syndrome in a 25-year-old man with no personal or family history of autoimmune disease. Resection with SVC reconstruction was performed.

[IgG4-related disease: about 3 cases]

IgG4-Related disease (IgG4-RD), formerly known as IgG4-related autoimmune polyexocrinopathy, is a new condition including Plasminogen Activator Inhibitor-1 (PAI-1). It can affect different organs (central nervous system, salivary glands, thyroid, lungs, pancreas, bile ducts, liver, digestive tract, kidneys, prostate, etc.) with symptoms depending on the organ that is affected. It is more common in men older than 50 years of age. Its incidence and prevalence are poorly known because it is an uncommon disease. It is most common in Asia, accounting for only 20-30% of PAI in the Western world. Diagnosis is based on histological examination which shows dense lymphoplasmocytic infiltration in the organ affected associated with IgG4-positive plasma cells (immunohistochemistry), organ fibrosis and obliterating venulitis, all this in the context of increased serum IgG4 levels in more than 80% of cases. Patients are sensitive to corticosteroid therapy, with a high risk of relapse after discontinuation of corticosteroid therapy. This leads to the use of immunomodulators, mainly: thiopurines (azathioprine or 6-mercaptopurine), methotrexate and more recently rituximab, which can also be used as induction therapy. Given recent advances, accurate histological and clinical criteria are currently known to limit inappropriate management such as surgery. However, knowledge gaps remain concerning: pathophysiology, identification of specific biomarkers other than IgG4, natural history of the disease and long-term cancer risk assessment, performances of diagnostic tools such as endoscopic ultrasound-guided pancreatic biopsy. As well, consensual international management should be defined in the early stages of the disease and when patients develop recurrences. The purpose of this study was to report 3 cases of IgG4-Related disease on the basis of clinical and radiological criteria as well as therapeutic response.

Immunoglobulin G4-Related Orbital Disease with Bilateral Optic Perineuritis and Maxillary Nerves Involvement: A Case Report

Immunoglobulin G4-related optic neuropathy caused by optic perineuritis is a rare complication of immunoglobulin G4-related disease (IgG4-RD). Herein, we report a 38-year-old Asian man with history of sinusitis who presented with painless blurred vision and proptosis for over 6 months. Examination with the Hertel exophthalmometer revealed 21.5 mm on both eyes. Magnetic resonance imaging revealed a doughnut sign encircling the right optic nerve, bilateral tram-track signs on both optic nerves, enlarged bilateral maxillary nerves with perineural spreading to the infraorbital nerves, hypertrophy of extraocular muscles, and pansinusitis. Visual evoked potentials displayed bilateral delayed P100 latency, indicating bilateral optic neuropathy. Biopsy with functional endoscopic sinus surgery demonstrated diffuse dense lymphoplasmacytic infiltrate and fibrosis. IgG4-positive plasma cells exceeded 50 cells per high-power field while the overall IgG4/IgG ratio was above 40%. Serological studies unveiled extremely high serum concentrations of IgG4 (2650 mg/dL), and the calculated serum IgG4/IgG ratio was 100%. These comprehensive features supported the diagnosis of IgG4-RD with bilateral optic perineuritis, branches of trigeminal nerve involvement, and pansinusitis. The visual acuity improved slightly following the initiation of treatment with corticosteroids, but it became worse again during the tapering course. Following another course of corticosteroids followed by subsequent immunosuppressant treatment with azathioprine, vision in both eyes ultimately improved during the 2-year follow-up period.

The Cellular and Molecular Bases of Allergy, Inflammation and Tissue Fibrosis in Patients with IgG4-related Disease

IgG4-related disease (IgG4-RD) is a spectrum of complex fibroinflammatory disorder with protean manifestations mimicking malignant neoplasms, infectious or non-infectious inflammatory process. The histopathologic features of IgG4-RD include lymphoplasmacytic infiltration, storiform fibrosis and obliterative phlebitis together with increased in situ infiltration of IgG4 bearing-plasma cells which account for more than 40% of all IgG-producing B cells. IgG4-RD can also be diagnosed based on an elevated serum IgG4 level of more than 110 mg/dL (normal < 86.5 mg/mL in adult) in conjunction with protean clinical manifestations in various organs such as pancreato–hepatobiliary inflammation with/without salivary/lacrimal gland enlargement. In the present review, we briefly discuss the role of genetic predisposition, environmental factors and candidate autoantibodies in the pathogenesis of IgG4-RD. Then, we discuss in detail the immunological paradox of IgG4 antibody, the mechanism of modified Th2 response for IgG4 rather than IgE antibody production and the controversial issues in the allergic reactions of IgG4-RD. Finally, we extensively review the implications of different immune-related cells, cytokines/chemokines/growth factors and Toll-like as well as NOD-like receptors in the pathogenesis of tissue fibro-inflammatory reactions. Our proposals for the future investigations and prospective therapeutic strategies for IgG4-RD are shown in the last part.

Occurrence of Immunoglobulin G4-related Disease during Chemotherapy for Advanced Breast Cancer

Immunoglobulin G4-related disease (IgG4-RD) is defined as an inflammatory lymphoproliferative disorder. The relationship between malignancies and IgG4-RD remains unclear. We herein present a case of IgG4-RD that occurred during chemotherapy for advanced breast cancer. In this case, it was challenging to determine which of these diseases was responsible for the patient's mediastinal lymphadenopathy. Lymphadenopathy with IgG4-RD was diagnosed by assessing the reactivity to corticosteroids, which were used as premedication in chemotherapy, over time. The administration of prednisolone, which was initiated to treat active IgG4-RD, led to stable systemic therapy for malignancy. It is imperative to assess the disease activity and consider each treatment.

IgG4 sclerosing disease of the esophagus: a case-based review

IgG4-related disease (IgG4-RD) is an inflammatory and fibrosing disease which causes tumor-like swelling of organs and commonly mimics symptoms of malignancy. It has been increasing in prevalence in the last decade, but esophageal involvement remains rare. IgG4-RD was first known to involve certain organs, such as the pancreas. It has, since, been described as a systemic disease process. IgG4-RD should be considered in patients presenting with dysphagia. Initiation of appropriate treatment with corticosteroids can avoid unnecessary procedures and improve outcomes. The aim of this review is to discuss 17 cases of IgG4-RD of the esophagus. Literature review was conducted using NCBI database (PMC and PubMed filters) using the keywords "IgG4 disease," "sclerosing," "esophagus" and "gastrointestinal." The search was narrowed to include cases describing IgG4 disease of the esophagus using the same filters. Literature review identified 16 documented cases of IgG4-RD involving the esophagus. Upon literature review, it remains clear that it is extremely rare for IgG4-RD to affect the esophagus. Sixteen cases have been reported. We present a 17th case and discuss the implications of IgG4-RD. It is important to keep a broad differential diagnosis that includes IgG4-RD for patients presenting with dysphagia, especially when symptoms are refractory.

Thymus and Activation-regulated Chemokine as a Biomarker for IgG4-related Disease

High serum concentrations of thymus and activation-regulated chemokine (TARC) are observed in allergic diseases such as atopic dermatitis and bronchial asthma. Frequent allergic symptoms have been reported in patients with IgG4-related disease (IgG4-RD). We investigated the pathogenic role of TARC as a biomarker in IgG4-RD patients. We evaluated the serum concentrations of TARC from 29 IgG4-RD patients, 28 primary Sjögren syndrome (pSS) patients, and 23 healthy controls (HCs) by enzyme-linked immunosorbent assay (ELISA). We analyzed the correlations between the TARC concentrations and the subjects’ clinical parameters. To investigate the biological effect of TARC on the pathogenesis of IgG4-RD, we evaluated the in vitro induction of plasmablasts from IgG4-RD patients by TARC. The serum concentrations of TARC in the IgG4-RD patients were significantly higher than those of the pSS patients and HCs. The serum TARC concentration of the IgG4-RD group was positively correlated with the IgG4-RD responder index (IgG4-RD RI) score and with the number of organs involved, but it was not correlated with the serum IgG4 level or eosinophil number in the IgG4-RD patients’ peripheral blood. The patients who had lung involvement had higher serum TARC concentrations. In vitro, TARC clearly induced the formation of plasmablasts from the IgG4-RD patients’ peripheral blood mononuclear cells. Collectively, our data suggest that a systemic increment of TARC may contribute to the development of IgG4-RD through an aberrant induction of plasmablasts.

Eosinophilic pancreatitis: a rare or unexplored disease entity?

Several case reports show accumulation of eosinophils in pancreatitis patients and term the disease as “eosinophilic pancreatitis (EP)”. EP usually presents with a pancreatic tumour and abdominal pain in obstructive jaundice, which is generally not diagnosed until the patient undergoes pancreatic resection. Histologically, EP reveals distinct patterns like diffused, periductal, acinar, and septal inflammatory infiltrates with eosinophils, eosinophilic phlebitis, and localised extreme eosinophilic infiltrates related with pseudocyst formation. EP patients also have elevated serum IgE levels with high eosinophil counts in the pancreas as well as in other organs such as the gastrointestinal tract, which is termed as eosinophilic gastroenteritis. Due to the lack of knowledge based on just a few case reports, it is considered that eosinophilic infiltration is quite rare in the pancreas; therefore, the significance of eosinophils in pancreatitis is not yet established. This review assesses the current understanding of eosinophilic pancreatitis and the important role of eosinophils in promoting pancreatic fibrosis including malignancy.

Different clinical patterns of IgG4-RD patients with and without eosinophilia

It has been reported that patients with IgG4-related disease (IgG4-RD) showed an elevated incidence of eosinophilia. We aim to explore the clinical patterns of IgG4-RD patients with and without eosinophilia. Four hundred and twenty-five IgG4-RD patients referred to Peking Union Medical College Hospital were enrolled. Blood eosinophil count higher than 0.5 × 10⁹/L was defined as eosinophilia. Clinical features of all the participants were collected and analyzed statistically. Eighty-seven patients (20%) with eosinophilia were found. As compared to those with a normal range of blood eosinophil count, male predominance, longer disease duration, increased prevalence of dacryoadenitis, sialadenitis, lymphadenopathy, and skin rash, higher IgG4-RD responder index, more organ involvement and higher levels of serum IgG4 (17.0 g/L vs 6.5 g/L, P < 0.001) was found in patients with eosinophilia. There was no significant difference in the incidence of allergic disease between the two groups. Peripheral eosinophil counts were positively correlated with disease duration, the number of involved organs, IgG4-RD responder index, and serum IgG4. Higher recurrence rate during follow-up period was found in patients with eosinophilia [28.6% (20/70) vs 17.1% (42/245), P = 0.034]. IgG4-RD patients with eosinophilia exhibited different clinical patterns from patients without. Eosinophilia appeared independent of allergies in IgG4-RD.

IgG4-related disease with tracheobronchial miliary nodules and asthma: a case report and review of the literature

Background

IgG4-related disease (IgG4-RD) is a systemic autoimmune disease that can affect multiple organs of the body. Pulmonary manifestations of IgG4-RD include pulmonary solid nodules, thickening of bronchovascular bundles, interstitial involvement, and ground glass opacities. Here we present a rare case of IgG4-RD with tracheobronchial nodules and review the relevant literature.

Case presentation

A 52-year-old man was admitted to our hospital with a history of intermittent cough for 27 months and recurrent wheezing for 17 months. He had been diagnosed with asthma prior to admission and was responsive to oral prednisone (30 mg/day, with gradual tapering). Bronchoscopy performed 2 years prior to admission showed tracheal and bronchial mucosal hyperemia, edema, and miliary nodules. Pathological tests showed chronic inflammation with focal lymphocytic infiltration in the bronchial mucosa. The patient had recurrent cough and wheezing after prednisone was stopped or the dose reduced. At the time of admission to our hospital, his serum immunoglobulin G4 (IgG4) level had increased to 7.35 g/L. Following bronchoscopy, the IgG4 expression in the bronchial mucosa was compared with that observed during the last two bronchoscopies. Bronchoscopy performed 7 months prior to admission revealed IgG4+ plasma cell infiltration in the bronchial tissue, with > 10 IgG4+ plasma cells per high power field and an IgG4+/IgG+ cell ratio of > 40%. The current bronchoscopy revealed a decrease in IgG4 expression in the bronchial tissue, probably because of the intermittent prednisone treatment. The case fulfilled the comprehensive clinical diagnostic criteria for IgG4-RD. He received prednisone and azathioprine, and he has never developed recurrence.

Conclusions

Our case exhibited three important clinical indication: First, tracheobronchial miliary nodules could be the presentation of IgG4-related disease. Second, IgG4-related disease with pulmonary involvement has close connection with asthma. Last, IgG4-related disease can be very sensitive to prednisone, the infiltration of IgG4 positive plasma cells decreased after prednisone treatment and symptoms significantly improved in our case. In conclusion, we reported the first case of IgG4-RD presenting with miliary nodules on the tracheal and bronchial tube walls combined with asthma. The findings will further our understanding of the characteristics of IgG4-RD.

Laminin 511 is a target antigen in autoimmune pancreatitis

Autoimmune pancreatitis (AIP), a major manifestation of immunoglobulin G4-related disease (IgG4-RD), is an immune-mediated disorder, but the target autoantigens are still unknown. We previously reported that IgG in patients with AIP induces pancreatic injuries in mice by binding the extracellular matrix (ECM). In the current study, we identified an autoantibody against laminin 511-E8, a truncated laminin 511, one of the ECM proteins, in patients with AIP. Anti-laminin 511-E8 IgG was present in 26 of 51 AIP patients (51.0%), but only in 2 of 122 controls (1.6%), by enzyme-linked immunosorbent assay. Because truncated forms of other laminin family members in other organs have been reported, we confirmed that truncated forms of laminin 511 also exist in human and mouse pancreas. Histologic studies with patient pancreatic tissues showed colocalization of patient IgG and laminin 511. Immunization of mice with human laminin 511-E8 induced antibodies and pancreatic injury, fulfilling the pathologic criteria for human AIP. Four of 25 AIP patients without laminin 511-E8 antibodies had antibodies against integrin α6β1, a laminin 511 ligand. AIP patients with laminin 511-E8 antibodies exhibited distinctive clinical features, as the frequencies of malignancies or allergic diseases were significantly lower in patients with laminin 511-E8 antibodies than in those without. The discovery of these autoantibodies should aid in the understanding of AIP pathophysiology and possibly improve the diagnosis of AIP.

Angioedema Masqueraders

Angioedema is a common reason for referral to immunology and allergy specialists. Not all cases are in fact angioedema. There are many conditions that may mimic its appearance, resulting in misdiagnosis. This may happen when a clinician is unfamiliar with conditions resembling angioedema or when there is a low index of clinical suspicion. In this article, we explore a list of differential diagnoses based on body parts, including the lips, the limbs, periorbital tissues, the face, epiglottis and uvula, as well as the genitalia, that may pose as a masquerader even to an experienced eye.

An update on IgG4-related lung disease

IgG4-related disease (IgG4-RD) is an autoimmune disorder characterized by substantial infiltration of plasma cells with IgG4 in target organs. Lung manifestations predominantly present as inflammatory pseudotumor, interstitial pneumonitis, organizing pneumonia, and lymphomatoid granulomatosis. There is no specific diagnostic test for IgG4-related lung disease (IgG4-RLD), and excluding diseases that mimic IgG4-RLD is important. Corticosteroids with or without disease-modifying anti-rheumatic drugs are recommended for treatment. The long-term prognosis of IgG4-RLD remains unknown. In this review, we summarized the current diagnostic algorithms and discussed potential biomarkers for future investigation.

Pancreatobiliary Versus Head and Neck Manifestations in Immunoglobulin G4-related Disease: Distinct Subsets of the Same Disease?

OBJECTIVES

We compared the clinical profiles and organ manifestations of the commonly encountered immunoglobulin G4-related diseases (IgG4-RDs) on either side of the diaphragm: head and neck (HN) versus pancreatobiliary (PB) in IgG4-RD.

METHODS

From the Mayo Clinic, Rochester, database, we identified 53 HN and 88 PB IgG4-RD based on the first affected organ manifestation.

RESULTS

Compared with HN IgG4-RD, subjects with PB IgG4-RD were likely to be older (median, 64.8 vs 50.2 years; P < 0.0001), male (83% vs 60.4%; P = 0.003), and with a shorter duration of follow-up (24.4 vs 48.7 months; P < 0.0001). In HN versus PB-IgG4-RD orbital, lacrimal gland, submandibular, parotid gland, asthma, and sinusitis manifestations were more common (77% vs 4.5%, 21% vs 0%, 32% vs 8%, 13% vs 0%, 36% vs 9%, and 51% vs 6.8%; P < 0.0001, respectively), whereas lung manifestations were similar (13.2% vs 5.6%; P = 0.12). In contrast, in PB versus HN IgG4-RD, pancreas and biliary were more frequent (98.8% vs 15%, 56.8% vs 3.7%; P < 0.0001), whereas renal lesions were similar (12.5% vs 7.5%; P = 0.36).

CONCLUSION

Pancreatobiliary and HN IgG4-RD have distinct clinical profiles. Proximity matters in other organ involvement in IgG4-RD, and organs involved tend to cluster close to each.

Activated T-Follicular Helper 2 Cells Are Associated With Disease Activity in IgG4-Related Sclerosing Cholangitis and Pancreatitis

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) and autoimmune pancreatitis (AIP) are characterized by an abundance of circulating and tissue IgG4-positive plasma cells. T-follicular helper (Tfh) cells are necessary for B-cell differentiation into plasma cells. We aimed at elucidating the presence and phenotype of Tfh cells and their relationship with disease activity in IgG4-SC/AIP.

Comparison of two subsets of Chinese patients with retroperitoneal fibrosis in terms of IgG4 immunohistochemical staining

OBJECTIVE

To identify clinical and pathological differences between IgG4-related retroperitoneal fibrosis (IgG4-RPF) and idiopathic RPF (iRPF) in a Chinese population.

METHOD

Clinical and pathological data of 50 RPF patients from 2006 to 2016 were retrospectively analysed. The presence of at least one characteristic histopathological feature, >30 IgG4+ plasma cells per high power field, and an IgG4+/IgG+ plasma cells ratio cutoff of >40% were used to define IgG4-RPF.

RESULTS

Patients with IgG4-RPF were significantly more likely to have pain (94.1 vs 68.8%, P = 0.048), elevated serum IgE concentration (166.1 vs 40.2 IU/ml, P = 0.029) and tissue eosinophilia (47.1 vs 12.5%, P = 0.018), compared with patients with iRPF. In the IgG4-RPF subgroup, patients with tissue eosinophilia demonstrated higher levels of CRP (4.3 vs 1.9 mg/dl, P = 0.027) and ESR (62.1 vs 22.8 mm/h, P = 0.001). Among the 50 patients with RPF, the average number of tissue IgG4+ plasma cells was positively correlated with the number of tissue eosinophils (r = 0.37, P = 0.009). Moreover, serum IgG4 concentration and serum IgE concentration showed positive correlation (r = 0.834, P = 0.000).

CONCLUSION

The distinct serological and histopathological features of Chinese patients with IgG4-RPF were elevated serum IgE concentration and tissue eosinophilia, which potentially can aid and support the diagnosis. As serum IgG4 concentration may be normal in patients with IgG4-RPF, serum IgE may represent a useful serological marker in distinguishing IgG4-RPF from iRPF.

The Clinicopathologic Spectrum of IgG4-Related Disease

Immunoglobulin G4-related disease is a fibroinflammatory systemic disease that is characterized by focal or diffuse organ infiltration by immunoglobulin G4-bearing plasma cells. Immunoglobulin G4-related disease may affect any organ, and a high index of suspicion is necessary for early detection to avoid irreversible fibrosis, organ dysfunction, and death. Tumor-forming lesions are common radiological features of immunoglobulin G4-related disease that need to be differentiated from malignancies. The diagnostic approach requires the integration of clinical, biochemical, and radiographic manifestations with classic histopathologic features, which remain crucial to diagnosis. The histology of immunoglobulin G4-related disease is determined by a dense lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis in the presence of increased immunoglobulin G4-positve plasma cells. Although immunoglobulin G4-related disease forms a distinct, clinically independent disease category, many questions and problems remain unanswered, especially on its pathogenesis and the role of immunoglobulin G4. Advances in the understanding of immunoglobulin G4-related disease are likely to change the diagnostic approach in the future and create potential targets for therapeutic purposes. Here we describe the concept of immunoglobulin G4-related disease and the most recent knowledge in the clinico-pathological characteristics on this emerging disease. This study can guide clinicians in early diagnosis and prevent unnecessary surgical resections.

IgG4-related pulmonary disease: the protean impersonator?

IgG4-related disease is an immune-mediated fibro-inflammatory disease, characterised by distinct pathological features. An increasing number of clinical phenotypes are described, from single-organ disease to a multisystem disorder, which can present to a variety of different specialities. Recognition is key; its protean manifestations can mimic other inflammatory diseases, infection and malignancy. Here, we present three cases to highlight the importance of being familiar with this condition in its various forms.

IgG4-related Disease - A Systemic Disease that Deserves Attention Regardless of One's Subspecialty

IgG4-related disease (IgG4-RD) is an inflammatory condition characterized by a high serum IgG4 concentration and the abundant infiltration of lymphocytes and IgG4-positive plasma cells in the tissue, as well as spatial (diverse clinical manifestations) and temporal (the possibility of recurrence) multiplicities. Since the initial documentation of IgG4-related disease in patients with autoimmune pancreatitis in 2001, a growing body of evidence has been accumulating to suggest that various-virtually all-organs can be affected by IgG4-RD. In general, steroid therapy is effective and is considered to be the first-line treatment for IgG4-RD. The precise mechanism underlying this systemic disorder has remained unknown. Considering that IgG4-RD was specified as being an intractable disease in 2015, further studies are needed to clarify whether IgG4-RD is indeed a distinct disease entity or a complex of disorders of different etiologies and clinical conditions.

A New Classification System for IgG4 Autoantibodies

IgG4 autoimmune diseases are characterized by the presence of antigen-specific autoantibodies of the IgG4 subclass and contain well-characterized diseases such as muscle-specific kinase myasthenia gravis, pemphigus, and thrombotic thrombocytopenic purpura. In recent years, several new diseases were identified, and by now 14 antigens targeted by IgG4 autoantibodies have been described. The IgG4 subclass is considered immunologically inert and functionally monovalent due to structural differences compared to other IgG subclasses. IgG4 usually arises after chronic exposure to antigen and competes with other antibody species, thus "blocking" their pathogenic effector mechanisms. Accordingly, in the context of IgG4 autoimmunity, the pathogenicity of IgG4 is associated with blocking of enzymatic activity or protein-protein interactions of the target antigen. Pathogenicity of IgG4 autoantibodies has not yet been systematically analyzed in IgG4 autoimmune diseases. Here, we establish a modified classification system based on Witebsky's postulates to determine IgG4 pathogenicity in IgG4 autoimmune diseases, review characteristics and pathogenic mechanisms of IgG4 in these disorders, and also investigate the contribution of other antibody entities to pathophysiology by additional mechanisms. As a result, three classes of IgG4 autoimmune diseases emerge: class I where IgG4 pathogenicity is validated by the use of subclass-specific autoantibodies in animal models and/or in vitro models of pathogenicity; class II where IgG4 pathogenicity is highly suspected but lack validation by the use of subclass specific antibodies in in vitro models of pathogenicity or animal models; and class III with insufficient data or a pathogenic mechanism associated with multivalent antigen binding. Five out of the 14 IgG4 antigens were validated as class I, five as class II, and four as class III. Antibodies of other IgG subclasses or immunoglobulin classes were present in several diseases and could contribute additional pathogenic mechanisms.

IgG4 and IgE co-positive group found in idiopathic orbital inflammatory disease

AIM

To reveal the cytokines involved in idiopathic orbital inflammatory disease (IOID) and the relationship between Th17 cells, IgE and IOID pathogenesis.

METHODS

Whole blood samples were processed immediately after collection and serological IgG4, IgG, and IgE antibodies were tested using ELISA. IOID and orbital cavernous hemangioma (CH) tissue samples underwent Bio-Plex multiplex cytokine detection. Hematoxylin-Eosin (HE) staining of all paraffin samples suggested the histological features of IOIDs, and expressions of IgG4 and IL-17A in affected tissues were detected by immunohistochemistry.

RESULTS

Among 40 IOID plasma samples, 52.5% (21/40) were positive for IgG4 and 25% (10/40) were positive for IgE. Overlapped IgG4 or IgE positive samples accounted for 22.5% (9/40). Therefore, IOID samples were separated into three groups. The IgE+/IgG4+ group had a relevantly lower level of pro-inflammatory cytokine expression. IL-4 (Th2 cell related), IL-10 and TGF-β1 (Treg cell immunity related) were elevated in all three groups. Some of the Th17 cell related cytokines (i.e. IL-17A/F, IL-25, IL-23, and IL-33) displayed higher expression levels in the IgE-/IgG4- group compared to the other two groups.

CONCLUSION

We discovered an IgG4-IgE co-positive group as well as Th17 cell immune involvement in IgG4-IgE co-negative subgtroup in IOID for the first time. The pathogenesis of IOID could differ from different subgroups according to the IgG4 and IgE detection. Therefore, we recommend that, Treatment stratagy should be made according to the clinical assessment of IgG4-IgE and Th17 profile detection.

IgG4-Related Disease: A Reminder for Practicing Pathologists

IgG4-related disease (IgG4-RD) is a systemic autoimmune fibroinflammatory disease that produces sclerotic, tumefactive masses containing dense lymphoplasmacytic infiltrates rich in immunoglobulin (Ig) G4+ plasma cells. Initially characterized as a form of autoimmune pancreatitis, the distinctive histopathology of IgG4-RD has now been described in almost every organ system. However, because the clinical manifestations of IgG4-RD are diverse and nonspecific, the disease may go unsuspected until a biopsy or resection specimen is obtained to diagnose a presumed malignancy. Pathologists thus play a key role in the diagnosis of IgG4-RD, and familiarity with its histopathologic features is essential to preventing the irreversible comorbidities associated with this treatable disease. This brief review outlines the epidemiology, clinical manifestations, and histopathology of IgG4-RD, with the aim of furthering pathologists' awareness of and ability to diagnose this disorder.

Increases in IgE, Eosinophils, and Mast Cells Can be Used in Diagnosis and to Predict Relapse of IgG4-Related Disease

BACKGROUND & AIMS

IgG subclass 4-related disease (IgG4-RD) is characterized by increased serum levels of IgG4 and infiltration of biliary, pancreatic, and other tissues by IgG4-positive plasma cells. We assessed the prevalence of allergy and/or atopy, serum, and tissue IgE antibodies, and blood and tissue eosinophils in patients with IgG4-RD. We investigated the association between serum IgE and diagnosis and relapse of this disease.

METHODS

We performed a prospective study of 48 patients with IgG4-RD, 42 patients with an increased serum level of IgG4 with other inflammatory and autoimmune conditions (disease control subjects), and 51 healthy individuals (healthy control subjects) recruited from Oxford, United Kingdom from March 2010 through March 2014, and followed for a median of 41 months (range, 3-73 months). Serum levels of immunoglobulin were measured at diagnosis, during steroid treatment, and at disease relapse for patients with IgG4-RD; levels at diagnosis were compared with baseline levels of control subjects. Allergen-specific IgEs were measured using the IgE ImmunoCAP. Levels and distribution of IgG4 and IgE antibodies in lymphoid, biliary, and pancreatic tissues from patients with IgG4-RD and disease control subjects were measured by immunohistochemistry. We analyzed data using the Spearman rank correlation and receiver operating characteristic curves.

RESULTS

Serum levels of IgG4 increased to 1.4 g/L or more, and IgE increased to 125 kIU/L or more, in 81% and 54% of patients with IgG4-RD, respectively, compared with 6% and 16% of healthy control subjects (P < .0001). Peripheral blood eosinophilia was detected in 38% of patients with IgG4-RD versus 9% of healthy control subjects (P = .004). Of patients with IgG4-RD, 63% had a history of allergy and 40% had a history of atopy with an IgE-specific response; these values were 60% and 53% in patients with increased serum levels of IgE (P < .05). Level of IgE at diagnosis >480 kIU/L distinguished patients with IgG4-RD from disease control subjects with 86% specificity, 36% sensitivity, and a likelihood ratio of 3.2. Level of IgE at diagnosis >380 kIU/L identified patients with disease relapse with 88% specificity, 64% sensitivity, and a likelihood ratio of 5.4. IgE-positive mast cells and eosinophilia were observed in lymphoid, biliary, and pancreatic tissue samples from 50% and 86% of patients with IgG4-RD, respectively.

CONCLUSIONS

In a prospective study, we associated IgG4-RD with allergy, atopy, eosinophilia, increased serum levels of IgE, and IgE-positive mast cells in lymphoid, biliary, and pancreatic tissue. An IgE-mediated allergic response therefore seems to develop in most patients with IgG4-RD; levels of IgE might be used in diagnosis and predicting relapse.

Distinct features distinguishing IgG4-related disease from multicentric Castleman's disease

Objectives

Differentiating IgG4-related disease (IgG4-RD) from multicentric Castleman’s disease (MCD) is challenging because both diseases present high serum IgG4. The objective of this study is to clarify the differences in characteristics and identify a clinically useful approach to differentiate these two diseases.

Methods

Forty-five consecutive patients with untreated active IgG4-RD and 33 patients with MCD were included in this study, who visited our institution from January 2000 to August 2016. The clinical and laboratory findings for the patients of the two diseases were compared. Various combinations of the distinctive findings were evaluated to identify the most efficient differentiating features between IgG4-RD and MCD.

Results

The levels of serum IgG4 were not different between the two diseases. Orbits, lacrimal glands, salivary glands or pancreas were involved in 88.9% of IgG4-RD cases and only in 3.0% of MCD cases. All MCD cases involved lymph nodes. Atopic history was characteristic for IgG4-RD. The levels of C reactive protein (CRP) with a cut-off of 0.80 mg/dL and IgA with a cut-off of 330 mg/dL were the most distinctive. The combination of ‘Orbits, lacrimal glands, salivary glands or pancreas involvement, atopic history, or non-involvement of lymph node’ and ‘CRP ≤ 0.8 mg/dL or IgA ≤ 330 mg/dL’ yielded the probability of 97.8% in IgG4-RD, while that of 3.0 % in patients with MCD.

Conclusions

Our study revealed distinct features between IgG4-RD and MCD. Differentiating between the diseases based on those distinct features, including distribution of organ involvement, atopic history, levels of IgA and CRP, was a useful approach.

Association of IgG4-Related Disease With History of Malignancy

OBJECTIVE

IgG4-related disease (IgG4-RD) is a fibroinflammatory disease of unclear etiology. Some studies suggest that IgG4-RD predisposes patients to malignancy or is a forme fruste of cancer, but we have frequently observed IgG4-RD patients who have a history of malignancy preceding the clinical onset of IgG4-RD. This study was undertaken to characterize IgG4-RD in the setting of previous malignancy diagnosis.

METHODS

We identified IgG4-RD patients with a history of invasive malignancy from a well-defined cohort of 125 patients and compared their malignancy history to those of 2 reference groups. First, we calculated a standardized prevalence ratio against general US population estimates from the Surveillance, Epidemiology, and End Results (SEER) database. Second, we identified up to 5 age- and sex-matched controls for each case and calculated the odds of malignancy among those with IgG4-RD compared to controls, using conditional logistic regression.

RESULTS

The mean ± SD age at IgG4-RD onset was 50.3 ± 14.9 years, and 61% of the patients were male. Twenty (16%) had been diagnosed as having malignancies (total 21 malignancies) before the diagnosis of IgG4-RD. The observed prevalence of malignancy in this cohort was 2.5 times higher (95% confidence interval [95% CI] 1.1-3.6) than expected compared to the SEER database. Compared to matched controls, the frequency of history of malignancy was >3-fold higher in IgG4-RD patients (95% CI 1.6-6.2).

CONCLUSION

Our findings suggest that, in a subset of patients with IgG4-RD, malignancy may be associated with subsequent IgG4-RD development. Potential explanations include shared risk factors for both IgG4-RD and cancer, the triggering by cancer of autoantigen expression leading to IgG4-RD, and an increased risk of IgG4-RD resulting from cancer treatment.

High Expression of Galectin-3 in Patients with IgG4-Related Disease: A Proteomic Approach

Objectives

Immunoglobulin G4-related disease (IgG4-RD) is a multiorgan condition manifesting itself in different forms. This study aimed to investigate protein expression profiles and to find the possible biomarker for IgG4-RD by liquid chromatography mass spectrometry (LC-MS) using tissue sections in IgG4-RD patients.

Methods

Protein expression profiles in five IgG4-related pancreatitis and three normal pancreatic samples were compared using LC-MS and were validated by quantitative real-time PCR (qRT-PCR), immunoblotting, and immunohistochemistry. ELISA was employed in the serum of 20 patients with systemic IgG4-RD before and during steroid treatment.

Results

LC-MS indicated that the levels of 17 proteins were significantly higher and 12 others were significantly lower in IgG4-related pancreatitis patients compared to controls. Among these proteins, galectin-3 levels were 13-fold higher in IgG4-related pancreatitis (P < 0.01). These results were confirmed by immunoblotting and qRT-PCR. The average number of galectin-3 + cells in various organs of IgG4-RD patients, including salivary glands, lungs, and lymph nodes, was higher than in controls. Galectin-3 was detectable in macrophages, dendritic cells, and stromal myofibroblast-like cells, but not in lymphocytes by immunofluorescence staining. Serum galectin-3 levels were higher in patients with IgG4-RD compared with healthy donors and remained high during steroid therapy.

Conclusion

Galectin-3 was overexpressed in IgG4-RD and the levels were indirectly related to clinical activity.