Identification of a novel antibody associated with autoimmune pancreatitis

Current and future advances in practice: IgG4-related disease

IgG4-related disease (IgG4-RD) is an increasingly recognized cause of fibroinflammatory lesions in patients of diverse racial and ethnic backgrounds and is associated with an increased risk of death. The aetiology of IgG4-RD is incompletely understood, but evidence to date suggests that B and T cells are important players in pathogenesis, both of which are key targets of ongoing drug development programmes. The diagnosis of IgG4-RD requires clinicopathological correlation because there is no highly specific or sensitive test. Glucocorticoids are highly effective, but their use is limited by toxicity, highlighting the need for studies investigating the efficacy of glucocorticoid-sparing agents. B cell-targeted therapies, particularly rituximab, have demonstrated benefit, but no randomized clinical trials have evaluated their efficacy. If untreated or under-treated, IgG4-RD can cause irreversible organ damage, hence close monitoring and consideration for long-term immunosuppression is warranted in certain cases.

Multimodality Imaging Features of Immunoglobulin G4-related Vessel Involvement

Immunoglobulin 4 (IgG4)-related disease is a chronic immune-mediated fibroinflammatory disorder. Involvement of the vascular system, including large- and medium-sized vessels, is increasingly recognized. The varied appearances of vascular involvement reflect the sequela of chronic inflammation and fibrosis and can include aortitis and periaortitis with resultant complications such as aneurysm formation and dissection. A diagnosis of IgG4-related large vessel involvement should be considered when there is known or suspected IgG4-related disease elsewhere. Other organs that are typically affected in IgG4-related disease include the lacrimal and salivary glands, thyroid, pancreas, biliary tree, lungs, kidneys, and meninges. Diagnosis typically requires careful correlation with clinical, imaging, serum, and pathologic findings. Patients may be managed with corticosteroid therapy or the anti-CD20 monoclonal antibody, rituximab, if needed. The varied clinical presentations and imaging features of large vessel involvement are discussed herein. Keywords: Vascular, Inflammation, Aorta, IgG4-related Vessel Involvement © RSNA, 2024.

Cardiovascular pathology in vasculitis

Vasculitides are diseases that can affect any vessel. When cardiac or aortic involvement is present, the prognosis can worsen significantly. Pathological assessment often plays a key role in reaching a definite diagnosis of cardiac or aortic vasculitis, particularly when the clinical evidence of a systemic inflammatory disease is missing. The following review will focus on the main histopathological findings of cardiac and aortic vasculitides.

IgG4 autoantibodies and autoantigens in the context of IgG4-autoimmune disease and IgG4-related disease

Immunoglobulins are an essential part of the humoral immune response. IgG4 antibodies are the least prevalent subclass and have unique structural and functional properties. In this review, we discuss IgG4 class switch and B cell production. We review the importance of IgG4 antibodies in the context of allergic responses, helminth infections and malignancy. We discuss their anti-inflammatory and tolerogenic effects in allergen-specific immunotherapy, and ability to evade the immune system in parasitic infection and tumour cells. We then focus on the role of IgG4 autoantibodies and autoantigens in IgG4-autoimmune diseases and IgG4-related disease, highlighting important parallels and differences between them. In IgG4-autoimmune diseases, pathogenesis is based on a direct role of IgG4 antibodies binding to self-antigens and disturbing homeostasis. In IgG4-related disease, where affected organs are infiltrated with IgG4-expressing plasma cells, IgG4 antibodies may also directly target a number of self-antigens or be overexpressed as an epiphenomenon of the disease. These antigen-driven processes require critical T and B cell interaction. Lastly, we explore the current gaps in our knowledge and how these may be addressed.

Plasma cells in human pancreatic ductal adenocarcinoma secrete antibodies against self-antigens

Intratumoral B cell responses are associated with more favorable clinical outcomes in human pancreatic ductal adenocarcinoma (PDAC). However, the antigens driving these B cell responses are largely unknown. We sought to discover these antigens by using single-cell RNA sequencing (scRNA-Seq) and immunoglobulin (Ig) sequencing of tumor-infiltrating immune cells from 7 primary PDAC samples. We identified activated T and B cell responses and evidence of germinal center reactions. Ig sequencing identified plasma cell (PC) clones expressing isotype-switched and hypermutated Igs, suggesting the occurrence of T cell-dependent B cell responses. We assessed the reactivity of 41 recombinant antibodies that represented the products of 235 PCs and 12 B cells toward multiple cell lines and PDAC tissues and observed frequent staining of intracellular self-antigens. Three of these antigens were identified: the filamentous actin (F-actin), the nucleic protein RuvB like AAA ATPase 2 (RUVBL2), and the mitochondrial protein heat shock protein family D (Hsp60) member 1 (HSPD1). Antibody titers against F-actin and HSPD1 were substantially elevated in the plasma of patients with PDAC compared with healthy donors. Thus, PCs in PDAC produce autoantibodies reacting with intracellular self-antigens, which may result from promotion of preexisting, autoreactive B cell responses. These observations indicate the chronic inflammatory microenvironment of PDAC can support the adaptive immune response.

Remission Induction of IgG4-related Membranous Nephropathy with Multitarget Therapy

IgG4-related membranous nephropathy (MN) is often refractory to glucocorticoid (GC) therapy, and treatment remains unclear. We herein report a 67-year-old Japanese man with IgG4-related MN and tubulointerstitial nephritis. A post-gastroscopy antibody test revealed Helicobacter pylori infection. After eradication, his proteinuria decreased indefinitely. We started prednisolone (30 mg/day), long-term GCs, and immunosuppressant therapy. However, remission proved challenging to achieve, with persistent proteinuria present at 1.0-2.0 g/gCr. We performed multitarget therapy for refractory IgG4-related MN, achieving proteinuria remission (<0.3 g/gCr). Multitarget therapy with low-dose GCs can resolve refractory IgG4-related MN through remission induction of proteinuria and minimize the risks associated with GC therapy.

Identification of the immunogenic membrane proteins, catalase, PgbA, and PgbB, as potential antigens against Helicobacter pylori

AIMS

This study aims to investigate the specific membrane antigens that are targeted by antibodies raised against Helicobacter pylori.

METHODS AND RESULTS

Bovine milk antibodies were prepared using whole H. pylori, purified membrane proteins, or both. Enzyme-linked immunosorbent assay and sodium dodecyl sulfate-polyacrylamide gel electrophoresis experiments revealed that these immunogens triggered anti-H. pylori antibody production in milk. The highest antibody titer was induced by the mixture of whole bacteria and purified membrane proteins. The antibodies induced by mixed immunogens significantly inhibited H. pylori growth in vitro and were used to identify catalase, plasminogen-binding protein A (PgbA), and PgbB via western blotting, immunoprecipitation, and two-dimensional western blotting followed by liquid chromatography with tandem mass spectrophotometry. The immunogenicity of PgbA and PgbB was verified in mice vaccinated with their B-cell epitope vaccines. Following prophylactic vaccination of C57BL/6 mice, each of the three antigens alone and their combination reduced the weight loss in mice, increased antibody titers, and relieved the inflammatory status of the gastric mucosa following H. pylori infection.

CONCLUSIONS

Catalase, PgbA, and PgbB could serve as valuable membrane antigens for the development of anti-H. pylori immunotherapies.

Single-cell transcriptome analysis and protein profiling reveal broad immune system activation in IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic autoimmune disease with unclear pathogenesis. We performed single-cell RNA-seq and surface proteome analyses on 61,379 PBMCs from 9 treatment-naive IgG4-RD patients and 7 age- and sex-matched healthy controls. Integrative analyses were performed for altered gene expression in IgG4-RD, and flow cytometry and immunofluorescence were used for validation. We observed expansion of plasmablasts with enhanced protein processing and activation, which correlated with the number of involved organs in IgG4-RD. Increased proportions of CD4+ cytotoxic T lymphocytes (CTLs), CD8+ CTLs-GNLY (granulysin), and γδT cells with enhanced chemotaxis and cytotoxicity but with suppressed inhibitory receptors characterize IgG4-RD. Prominent infiltration of lymphocytes with distinct compositions were found in different organs of IgG4-RD patients. Transcription factors (TFs), including PRDM1/XBP1 and RUNX3, were upregulated in IgG4-RD, promoting the differentiation of plasmablasts and CTLs, respectively. Monocytes in IgG4-RD have stronger expression of genes related to cell adhesion and chemotaxis, which may give rise to profibrotic macrophages in lesions. The gene activation pattern in peripheral immune cells indicated activation of multiple interaction pathways between cell types, in part through chemokines or growth factors and their receptors. Specific upregulation of TFs and expansion of plasmablasts and CTLs may be involved in the pathogenesis of IgG4-RD, and each of these populations are candidate targets for therapeutic interventions in this disease.

Serum IgG4-negative IgG4-related disease with a cardiac mass: A case report

RATIONALE

Although IgG4-related disease (IgG4-RD) can affect various organs, its association with a cardiac mass is exceptionally rare. Here, we report a case of a woman with IgG4-RD and a cardiac mass and discuss 10 similar cases reported previously.

PATIENT CONCERNS

A 65-year-old woman was referred to our hospital for chest discomfort and back pain.

DIAGNOSES

In accordance with the 2019 ACR/EULAR diagnostic criteria for IgG4-RD, she was diagnosed with IgG4-RD based on dense lymphocytic infiltration on histopathology, IgG/IgG4-positive cell ratio <40%, >10/hpf IgG4-positive cells on immunostaining, and paraspinal zone soft tissue lesions in the chest.

INTERVENTIONS

An external pacemaker was implanted for the complete atrioventricular block on the electrocardiogram. After the diagnosis of IgG4-RD, she was treated with glucocorticoids and rituximab.

OUTCOMES

She remains under observation without disease recurrence.

LESSONS

IgG4-RD are usually treated with glucocorticoids; however, in cases of a cardiac mass, life-threatening complications may occur and surgery is often needed. Combination therapy with glucocorticoids and rituximab may be effective even in patients with IgG4-RD and cardiac mass, which may avoid the need of invasive treatments, such as surgery.

IgG4 Antibodies Induced by Repeated Vaccination May Generate Immune Tolerance to the SARS-CoV-2 Spike Protein

Less than a year after the global emergence of the coronavirus SARS-CoV-2, a novel vaccine platform based on mRNA technology was introduced to the market. Globally, around 13.38 billion COVID-19 vaccine doses of diverse platforms have been administered. To date, 72.3% of the total population has been injected at least once with a COVID-19 vaccine. As the immunity provided by these vaccines rapidly wanes, their ability to prevent hospitalization and severe disease in individuals with comorbidities has recently been questioned, and increasing evidence has shown that, as with many other vaccines, they do not produce sterilizing immunity, allowing people to suffer frequent re-infections. Additionally, recent investigations have found abnormally high levels of IgG4 in people who were administered two or more injections of the mRNA vaccines. HIV, Malaria, and Pertussis vaccines have also been reported to induce higher-than-normal IgG4 synthesis. Overall, there are three critical factors determining the class switch to IgG4 antibodies: excessive antigen concentration, repeated vaccination, and the type of vaccine used. It has been suggested that an increase in IgG4 levels could have a protecting role by preventing immune over-activation, similar to that occurring during successful allergen-specific immunotherapy by inhibiting IgE-induced effects. However, emerging evidence suggests that the reported increase in IgG4 levels detected after repeated vaccination with the mRNA vaccines may not be a protective mechanism; rather, it constitutes an immune tolerance mechanism to the spike protein that could promote unopposed SARS-CoV2 infection and replication by suppressing natural antiviral responses. Increased IgG4 synthesis due to repeated mRNA vaccination with high antigen concentrations may also cause autoimmune diseases, and promote cancer growth and autoimmune myocarditis in susceptible individuals.

Effects of Fibulin-5 Gene Silencing on Proliferation and Apoptosis of IgG4-ROD Lacrimal Gland Fibroblasts

Objective

This study is aimed at discussing the value of RNA interference technology on inhibiting lacrimal gland fibrosis in IgG4-related ocular disease (IgG4-ROD).

Methods

Six patients with IgG4-ROD who came to the hospital for surgical treatment from October 2018 to August 2019 were selected, and their diseased lacrimal glands were taken for primary cell culture and fibroblast identification. High efficiency and specificity small interference RNA (siRNA) plasmid vector was constructed, its inhibitory effect on fibroblast proliferation was determined by CCK-8 assay, and the appropriate concentration was selected as the siRNA concentration for subsequent experiments. RT-PCR and Western blot detected the relative expression levels of Fibulin-5 mRNA and protein in the cells 48 hours after transfection. The apoptosis rate of each group of cells at 24 hours, 48 hours, and 72 hours after transfection was detected by flow cytometry, and the proliferation and apoptosis of cells after silencing Fibulin-5 were analyzed and compared.

Results

24 hours after transfection, there was no significant difference in the proliferation rate among the four groups (P > 0.05); 48 hours and 72 hours after Fibulin-5 siRNA transfection, the proliferation activity of the transfected cells was significantly decreased compared with the 0 nM group, and the inhibitory effect of 75 nM siRNA was the strongest. The expression of Fibulin-5 mRNA and protein in the siRNA-transfected cells was significantly decreased compared with the blank and empty vector negative siRNA groups, and the difference was statistically significant (P < 0.05). The apoptosis rate of cells in the Fibulin-5 siRNA transfection group was significantly higher than that of cells in the blank and empty vector negative siRNA groups, and the difference was statistically significant (P < 0.05).

Conclusion

Fibulin-5 siRNA recombinant plasmid can significantly downregulate the mRNA and protein expressions of target gene Fibulin-5 and promote apoptosis after transfection into IgG4-ROD lacrimal gland fibroblasts. It is speculated that Fibulin-5 can be used as a target to effectively inhibit the fibrosis of lacrimal gland tissues by RNAi technique.

Research Progress in Intestinal Microecology in Pancreatic Cancer Diagnosis and Treatment

The intestinal microbiota has an increasingly recognized role in the development of cancer, in which microbial interactions play a more important than expected role. Pancreatic cancer is a highly fatal disease, in which its mortality is closely related to its morbidity. Early detection is the best chance of improving survival. Through an in-depth understanding of the pancreatic cancer microbiota, we could establish screening or early diagnosis methods for pancreatic cancer, implement bacterial treatment, adjust the therapeutic effect, and even reduce adverse reactions. These would lead to new developments and provide hope for patients with pancreatic cancer. Herein, we review the progress in intestinal microbiology research to diagnose and treat pancreatic cancer.

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.

Immunoglobulin G4-related disease diagnosed by prostate biopsy: a case report

Background

Immunoglobulin G4-related disease is characterized by swelling of various organs throughout the body and nodules/hypertrophic lesions. However, its cause remains unknown. We report a case of immunoglobulin G4-related disease that was diagnosed based on the histopathological findings of prostate biopsy.

Case presentation

A 72-year-old Japanese man had been treated by a nearby doctor for hypertension, but subsequently developed lower urinary tract symptoms and was prescribed an α1 blocker for 1 year. However, the patient was subsequently referred to our department because his symptoms did not improve. Prostate-specific antigen was 1.258 ng/ml; however, the nodule was palpable in the right lobe on digital rectal examination, and magnetic resonance imaging suggested Prostate Imaging and Reporting and Data System category 3. Therefore, transrectal prostate needle biopsy (12 locations) under ultrasound was performed. Histopathological examination revealed no malignant findings, although infiltration of lymphocytes and plasma cells, and partial fibrosis were observed. No remarkable findings of obstructive phlebitis were observed. Immunoglobulin G4-related disease was suspected, and immunoglobulin and immunoglobulin G4 immunostaining was performed. Immunoglobulin G4 positive plasma cells were observed in a wide range, immunoglobulin G4 positive cells were noted at > 10 per high-power field, and the immunoglobulin G4 positive/immunoglobulin G positive cell ratio was > 40%. Serum immunoglobulin G4 levels were high at 1600 mg/dl. Enhanced abdominal computed tomography findings suggested periaortitis. Additionally, multiple lymphadenopathies were observed around the abdominal aorta. The patient was accordingly diagnosed with immunoglobulin G4-related disease definite, diagnosis group (definite). We proposed steroid treatment for periaortic soft tissue lesions and lower urinary tract symptoms; however, the patient was refused treatment. A computed tomography scan 6 months after diagnosis revealed no changes in the soft tissue lesions around the aorta. Follow-up computed tomography examinations will be performed every 6 months.

Conclusion

If immunoglobulin G4-related disease is suspected and a highly invasive examination is required for histopathological diagnosis, this can be performed by a relatively minimally invasive prostate biopsy for patients with lower urinary tract symptoms. Further evidence is needed to choose an optimal candidate for prostate biopsy for lower urinary tract symptoms patients with suspicion of immunoglobulin G4-related disease. For patients with lower urinary tract symptoms with immunoglobulin G4-related disease or a history, performing a prostate biopsy may avoid unnecessary treatment. However, if steroid therapy is ineffective, surgical treatment should be considered.

The role of serological biomarkers in the diagnosis and management of autoimmune pancreatitis

INTRODUCTION

Autoimmune pancreatitis (AIP) is a fibroinflammatory disease of the pancreas. Type 1 AIP is the pancreatic manifestation of a systemic IgG4-related disease and is associated with serum elevation of IgG4, tissue infiltration of IgG4-positive plasma cells, and multiorgan involvement. Although serum IgG4 elevation is considered a useful diagnostic tool, the concomitant presence of more diagnostic criteria is needed to achieve diagnosis. No other biomarkers have been approved in clinical practice in type 1 AIP. Type 2 AIP is a pancreatic-specific disease associated with inflammatory bowel disease. No specific biomarkers for type 2 AIP have been identified.

AREAS COVERED

The role of serum IgG4 in the diagnosis, management and follow-up of patients with type 1 AIP. Moreover, data on other emerging biomarkers for type 1 and 2 AIP have been reported.

EXPERT OPINION

The diagnosis of AIP is challenging in clinical practice, especially for focal forms without multiorgan involvement, where distinction from pancreatic cancer can be difficult. Despite the strong association with type 1 AIP, serum IgG4 should only be measured when the suspicion for the disease is high, considering its limited sensitivity. New biomarkers with high diagnostic yield for both type 1 and type 2 AIP are needed.

Inflammatory bowel disease and immune-mediated inflammatory diseases: looking at the less frequent associations

Patients with inflammatory bowel disease (IBD) often have other immune-mediated inflammatory diseases (IMIDs), and the prevalence of any IMID is higher in IBD patients than in the general population. IBD and other IMIDs involve alterations in innate and adaptive immune responses. Their co-occurrence depends on shared immune and inflammatory processes, pathogenic mechanisms, and genetic and environmental risk factors, including drugs, especially tumor necrosis factor inhibitors. The more common IMIDs associated with IBD have been widely described, so this review focuses on the less frequent associations. The IMIDs discussed here are skin disorders (psoriasis, atopic dermatitis, vitiligo, epidermolysis bullosa acquisita, cutaneous polyarteritis nodosa, and hidradenitis suppurativa), hepato-pancreatic diseases (autoimmune hepatitis, granulomatous hepatitis, and autoimmune pancreatitis), endocrine diseases (autoimmune thyroid diseases, and type 1 diabetes mellitus), multiple sclerosis, and respiratory diseases (asthma, bronchiectasis, and interstitial pneumonia). The early detection of IMIDs in IBD patients is important to prevent their deleterious clinical course and limit their psychological impact. Care for IBD patients with IMIDs should be multispecialist, with a single therapeutic strategy instead of treating each disease separately.

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.

Random peptides rich in small and disorder-promoting amino acids are less likely to be harmful

Proteins are the workhorses of the cell, yet they carry great potential for harm via misfolding and aggregation. Despite the dangers, proteins are sometimes born de novo from non-coding DNA. Proteins are more likely to be born from non-coding regions that produce peptides that do little to no harm when translated than from regions that produce harmful peptides. To investigate which newborn proteins are most likely to "first, do no harm", we estimate fitnesses from an experiment that competed Escherichia coli lineages that each expressed a unique random peptide. A variety of peptide metrics significantly predict lineage fitness, but this predictive power stems from simple amino acid frequencies rather than the ordering of amino acids. Amino acids that are smaller and that promote intrinsic structural disorder have more benign fitness effects. We validate that the amino acids that indicate benign effects in random peptides expressed in E. coli also do so in an independent dataset of random N-terminal tags in which it is possible to control for expression level. The same amino acids are also enriched in young animal proteins.

Sclerosing Mesenteritis as an Uncommon Site of Involvement of IgG4-Related Disease: A Case Report With an Updated Review of the Literature

Immunoglobulin G4-related disease (IgG4-RD) is an uncommon immune-mediated disorder most commonly involving the pancreas, lacrimal, and salivary glands. Immunoglobulin G4-related sclerosing mesenteritis (IgG4-RSM) is a rare site of involvement that usually mimics the imaging characteristics of mesenteric malignancies. Herein, we report a case of IgG4-RSM followed by an updated and comprehensive review of the literature. A 73-year-old woman presented with colicky abdominal pain in the right hypochondrium. The findings on contrast medium computed tomography (CMCT) showed a swelling of the mesenteric root with vascular structures surrounded by slightly contrast-impregnated tissue and irregular margins. The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET) showed an area of inhomogeneous and intense hypermetabolism of the mesenteric root. Hence, laparoscopic resection of the mesenteric root was performed to distinguish such masses from malignant tumors, obtaining specimens for histopathologic examination. The latter exhibited tissue infiltration with lymphocytes, IgG4-positive plasma cells, and fibrosis, indicating a diagnosis of IgG4-RSM in the presence of both elevated serum IgG4 levels and the aforementioned imaging findings. With steroid therapy, no clinical signs of re-exacerbation within a one-year follow-up were observed and serum IgG4 levels returned to normality. Aiming to evaluate the real frequency of IgG4-RSM in view of the 2017 Comprehensive Diagnostic Criteria (CDC) of IgG4-RD, we undertook a complete MEDLINE, EMBASE, Web of Science, and Scopus database search of all case reports of IgG4-RSM published so far. Such criteria were met in only six cases with a definite diagnosis. This case highlights the mesentery as a rare site of involvement of IgG-RD and allows us to advance knowledge of IgG4-RSM.

HLA-DRB1∗16 and -DQB1∗05 alleles are strongly associated with autoimmune pancreatitis in a cohort of hundred patients

BACKGROUND/OBJECTIVES

Autoimmune diseases are often associated with human leukocyte antigen (HLA) haplotypes, indicating that changes in major histocompatibility complex (MHC)-dependent self-peptide or antigen presentation contribute to autoimmunity. In our study, we aimed to investigate HLA alleles in a large European cohort of autoimmune pancreatitis (AIP) patients.

METHODS

Hundred patients with AIP, diagnosed and classified according to the International Consensus Diagnostic Criteria (ICDC), were prospectively enrolled in the study. Forty-four patients with chronic pancreatitis (CP) and 254 healthy subjects served as control groups. DNA was isolated from blood samples and two-digit HLA typing was performed with sequence-specific primer (SSP-) PCR. HLA allele association strength to AIP was calculated as odds ratio.

RESULTS

We uncovered a strong enrichment of HLA-DQB1 homozygosity in type 1 and type 2 AIP patients. Moreover, a significantly increased incidence of the HLA-DRB1∗16 and HLA-DQB1∗05 alleles and a concomitant lack of the HLA-DRB1∗13 allele was detected in AIP type 1 and type 2 patients. In contrast, the HLA-DQB1∗02 allele was underrepresented in the 'not otherwise specified' (NOS) AIP subtype. We detected no significant difference in the HLA-DRB3, HLA-DRB4 and HLA-DRB5 allele frequency in our cohort.

CONCLUSIONS

Although AIP type 1 and type 2 are characterized by distinct histopathological characteristics, both subtypes are associated with the same HLA alleles, indicating that the disease might rely on similar immunogenic mechanisms. However, AIP NOS represented another subclass of AIP.

IgG4-related diseases of the digestive tract

IgG4-related conditions affecting the digestive tract are part of a multi-organ fibro-inflammatory disorder termed IgG4-related disease (IgG4-RD), with autoimmune pancreatitis and IgG4-related cholangitis being the most prominent manifestations. Gastrointestinal symptoms include jaundice, weight loss, abdominal pain, biliary strictures, and pancreatic and hepatic masses that mimic malignant diseases. IgG4-RD manifestations occur less frequently elsewhere in the digestive tract, namely in the oesophagus, retroperitoneum or intestine. Evidence-based European guidelines frame the current state-of-the-art in the diagnosis and management of IgG4-related digestive tract disease. Diagnosis is based on histology (if available), imaging, serology, other organ involvement and response to therapy (HISORt criteria). Few biomarkers beyond serum IgG4 concentrations are reliable. The first-line therapy (glucocorticoids) is swiftly effective but disease flares are common at low doses or after tapering. Second-line therapy might consist of other immunosuppressive drugs such as thiopurines or rituximab. Further trials, for example, of anti-CD19 drugs, are ongoing. Although an association between IgG4-RD and the development of malignancies has been postulated, the true nature of this relationship remains uncertain at this time.

Respiratory Failure With Aspergillus submaranianii and Lymphoplasmacystic Vasculitis

Aspergillus subramanianii is a very rare form of Aspergillus in section Circumdati. Aspergillus subramanianii has been rarely reported or ever published. IgG4 disease is an emerging disease entity that can be a diagnostic challenge. We report a critically ill patient who had invasive A subramanianii pulmonary aspergillosis and posthumous diagnosis of IgG subclass 4 interstitial lung disease.

Neutralizing anti-IL-1 receptor antagonist autoantibodies induce inflammatory and fibrotic mediators in IgG4-related disease

BACKGROUND

IgG4-related disease (IgG4-RD) is a fibroinflammatory condition involving loss of B-cell tolerance and production of autoantibodies. However, the relevant targets and role of these aberrant humoral immune responses are not defined.

OBJECTIVE

Our aim was to identify novel autoantibodies and autoantigen targets that promote pathogenic responses in IgG4-RD.

METHODS

We sequenced plasmablast antibody repertoires in patients with IgG4-RD. Representative mAbs were expressed and their specificities characterized by using cytokine microarrays. The role of anti-IL-1 receptor antagonist (IL-1RA) autoantibodies was investigated by using in vitro assays.

RESULTS

We identified strong reactivity against human IL-1RA by using a clonally expanded plasmablast-derived mAb from a patient with IgG4-RD. Plasma from patients with IgG4-RD exhibited elevated levels of reactivity against IL-1RA compared with plasma from the controls and neutralized IL-1RA activity, resulting in inflammatory and fibrotic mediator production in vitro. IL-1RA was detected in lesional tissues from patients with IgG4-RD. Patients with anti-IL-1RA autoantibodies of the IgG4 subclass had greater numbers of organs affected than did those without anti-IL-1RA autoantibodies. Peptide analyses identified IL-1RA epitopes targeted by anti-IL-1RA antibodies at sites near the IL-1RA/IL-1R interface. Serum from patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) also had elevated levels of anti-IL-1RA autoantibodies compared with those of the controls.

CONCLUSION

A subset of patients with IgG4-RD have anti-IL-1RA autoantibodies, which promote proinflammatory and profibrotic meditator production via IL-1RA neutralization. These findings support a novel immunologic mechanism underlying the pathogenesis of IgG4-RD. Anti-IL-1RA autoantibodies are also present in a subset of patients with SLE and RA, suggesting a potential common pathway in multiple autoimmune diseases.

Intestinal flora and pancreatitis: Present and future

The role of intestinal flora in human health and diseases has attracted more and more attention. At present, there have been some reports on the relationship between intestinal flora and pancreatitis. These reports reveal that intestinal flora plays some important roles in the occurrence and development of pancreatitis. The specific mechanisms of action are unclear, but there is preliminary consensus that intestinal microbiome dysregulation promotes inflammatory changes in the pancreas. This paper summarizes the correlation between intestinal flora and pancreatitis, in order to provide some references and ideas for further research.

Histological features of autoimmune pancreatitis and IgG4-related sclerosing cholangitis with a correlation with imaging findings

Autoimmune pancreatitis (AIP) is characterized by a tumefactive inflammatory lesion resembling pancreatic carcinoma. Type 1 AIP is a pancreatic manifestation of IgG4-related disease characterized by unique histological features that can be identified on imaging. The capsule-like rim, which is a collar of hypertrophic lesion surrounding the pancreas, consists of lymphoplasmacytic infiltration and fibrosis, and storiform fibrosis is often identified. Hypertrophic lesions of various microscopic architectures such as the ducts, veins (obliterative phlebitis), arteries (periarteritis), and nerves are observed without parenchymal damage. The pancreatic lobules keep their contours, but the acinar cells are diminished and replaced by numerous inflammatory cells. These features provide clues to arrive at a diagnosis of type 1 AIP and to distinguish it from pancreatic carcinoma on imaging. In contrast, type 2 AIP is an epithelium-centered inflammation involving the ducts and lobules. Neutrophilic infiltration in the epithelium and/or lumens (granulocytic epithelial lesion) is a characteristic finding. Lobular swelling due to inflammation is the cause of pancreatic enlargement. IgG4-related sclerosing cholangitis is histologically similar to the hypertrophic ductal lesion in type 1 AIP and characterized by wall thickening due to inflammation and luminal stenosis. The epithelium is intact, which is different from bile duct carcinomas and primary sclerosing cholangitis, the latter of which is characterized by inflammation targeting the epithelium. Although the histological features of type 1 AIP and IgG4-related sclerosing cholangitis are unique, the biopsy diagnosis of these diseases has limitations, which should be recognized by clinicians.

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.

Helicobacter pylori infection and other bacteria in pancreatic cancer and autoimmune pancreatitis

Helicobacter pylori (H. pylori) is an infectious agent influencing as much as 50% of the world’s population. It is the causative agent for several diseases, most especially gastric and duodenal peptic ulcer, gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma of the stomach. A number of other, extragastric manifestations also are associated with H. pylori infection. These include neurological disorders, such as Alzheimer’s disease, demyelinating multiple sclerosis and Parkinson’s disease. There is also evidence for a relationship between H. pylori infection and such dermatological diseases as psoriasis and rosacea as well as a connection with infection and open-angle glaucoma. Generally little is known about the relationship between H. pylori infection and diseases of the pancreas. Most evidence about H. pylori and its potential role in the development of pancreatic diseases concerns pancreatic adenocarcinoma and autoimmune forms of chronic pancreatitis. There is data (albeit not fully consistent) indicating modestly increased pancreatic cancer risk in H. pylori-positive patients. The pathogenetic mechanism of this increase is not yet fully elucidated, but several theories have been proposed. Reduction of antral D-cells in H. pylori-positive patients causes a suppression of somatostatin secretion that, in turn, stimulates increased secretin secretion. That stimulates pancreatic growth and thus increases the risk of carcinogenesis. Alternatively, H. pylori, as a part of microbiome dysbiosis and the so-called oncobiome, is proven to be associated with pancreatic adenocarcinoma development via the promotion of cellular proliferation. The role of H. pylori in the inflammation characteristic of autoimmune pancreatitis seems to be explained by a mechanism of molecular mimicry among several proteins (mostly enzymes) of H. pylori and pancreatic tissue. Patients with autoimmune pancreatitis often show positivity for antibodies against H. pylori proteins. H. pylori, as a part of microbiome dysbiosis, also is viewed as a potential trigger of autoimmune inflammation of the pancreas. It is precisely these relationships (and associated equivocal conclusions) that constitute a center of attention among pancreatologists, immunologists and pathologists. In order to obtain clear and valid results, more studies on sufficiently large cohorts of patients are needed. The topic is itself sufficiently significant to draw the interest of clinicians and inspire further systematic research. Next-generation sequencing could play an important role in investigating the microbiome as a potential diagnostic and prognostic biomarker for pancreatic cancer.

The fecal microbiota of patients with pancreatic ductal adenocarcinoma and autoimmune pancreatitis characterized by metagenomic sequencing

BACKGROUND

The fecal microbiota in pancreatic ductal adenocarcinoma (PDAC) and in autoimmune pancreatitis (AIP) patients remains largely unknown. We aimed to characterize the fecal microbiota in patients with PDAC and AIP, and explore the possibility of fecal microbial biomarkers for distinguishing PDAC and AIP.

METHODS

32 patients with PDAC, 32 patients with AIP and 32 age- and sex-matched healthy controls (HC) were recruited and the fecal microbiotas were analyzed through high-throughput metagenomic sequencing. Alterations of fecal short-chain fatty acids were measured using gas chromatographic method.

RESULTS

Principal coordinate analysis (PCoA) revealed that microbial compositions differed significantly between PDAC and HC samples; whereas, AIP and HC individuals tended to cluster together. Significant reduction of phylum Firmicutes (especially butyrate-producing bacteria, including Eubacterium rectale, Faecalibacterium prausnitzii and Roseburia intestinalis) and significant increase of phylum Proteobacteria (especially Gammaproteobacteria) were observed only among PDAC samples. At species level, when compared with HC samples, we revealed 24 and 12 differently enriched bacteria in PDAC and AIP, respectively. Functional analysis showed a depletion of short-chain fatty acids synthesis associated KO modules (e.g. Wood-Ljungdahl pathway) and an increase of KO modules associated with bacterial virulence (e.g. type II general secretion pathway). Consistent with the downregulation of butyrate-producing bacteria, gas chromatographic analysis showed fecal butyrate content was significantly decreased in PDAC group. Eubacterium rectale, Eubacterium ventrisum and Odoribacter splanchnicus were among the most important biomarkers in distinguishing PDAC from HC and from AIP individuals. Receiver Operating Characteristic analysis showed areas under the curve of 90.74% (95% confidence interval [CI] 86.47-100%), 88.89% (95% CI 73.49-100%), and 76.54% (95% CI 52.5-100%) for PDAC/HC, PDAC/AIP and AIP/HC, respectively.

CONCLUSIONS

In conclusion, alterations in fecal microbiota and butyrate of patients with PDAC suggest an underlying role of gut microbiota for the pathogenesis of PDAC. Fecal microbial and butyrate as potential biomarkers may facilitate to distinguish patients with PDAC from patients with AIP and HCs which worth further validation.

Review of Diagnostic Biomarkers in Autoimmune Pancreatitis: Where Are We Now?

Autoimmune pancreatitis (AIP) is a pancreatic manifestation of an IgG4-related disease (IgG4-RD). AIP lacks disease-specific biomarkers, and therefore, it is difficult to distinguish AIP from malignancies, especially pancreatic cancer. In this review, we have summarized the latest findings on potential diagnostic biomarkers for AIP. Many investigations have been conducted, but no specific biomarkers for AIP are identified. Therefore, further studies are required to identify accurate diagnostic biomarkers for AIP.

IgG4-Related Disease With Tuberculosis: A Case Report and Retrospective Review of Patients in a Single Center

Background

IgG4-related disease (IgG4-RD) is a recently recognized systemic fibro-inflammatory disease of unknown cause involving many organs including pancreas, salivary glands, and lymph nodes. Chronic tuberculosis (TB) infection has been reported in IgG4-RD, but the prevalence of TB infection has not been evaluated in IgG4-RD.

Methods

Characterization of a patient with IgG4-RD by physical examination, laboratory tests, magnetic resonance imaging (MRI) and histological examination. TB infection was evaluated by medical history, radiological examinations, sputum examinations, tubercular skin test (TST) and interferon gamma (IFN-γ) release assay test (IGRA). Medical records of IgG4-RD patients were reviewed in our institute from February 2015 to September 2020 to explore the prevalence of TB infection in IgG4-RD.

Results

We described a 40-year-old Chinese man presented with headache and diplopia. Physical examination revealed bitemporal hemianopsia and limited abduction of both eyes. MRI revealed uniformly enhancing mass overlying clivus with dural tail sign. Laboratory data revealed elevation of IgG4 (1.9g/L), and TB-IGRA demonstrated significantly elevated IFN-γ (414.21 pg/ml). The clivus lesion was subtotally removed and IgG4 was strongly positive on immunohistochemical staining. The diagnosis of IgG4-RD was established, and the patient received treatment of corticosteroids, methotrexate, and cyclophosphamide with isoniazid prophylaxis. Consequently, the mass shrank remarkably within 3 months. A similar concurrence of TB disease or latent TB infection (LTBI) and IgG4-RD was present in 17/47 (36.2%) patients in our institute.

Conclusion

High frequency of TB/LTBI presented in patients with IgG4-RD. Patients with IgG4-RD and LTBI should be closely monitored for resurgence of TB. Whether TB represents a risk for IgG4-RD should be further investigated in prospective cohort.

Pancreatic Cancer Meets Human Microbiota: Close Encounters of the Third Kind

Simple Summary

The microorganisms colonizing the epithelial surfaces of the human body, called microbiota, have been shown to influence the initiation, progression and response to therapy of many solid tumors, including pancreatic ductal adenocarcinoma, the most prominent form of pancreatic cancer. Here, we summarize the current knowledge about the influence of oral, gut and intratumoral microbiota on pancreatic ductal adenocarcinoma development and chemoresistance.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal types of cancer with a dismal prognosis. The five-year survival rate has not changed significantly in over 40 years. Current first-line treatments only offer a modest increase in overall survival in unselected populations, and there is an urgent need to personalize treatment in this aggressive disease and develop new therapeutic strategies. Evolving evidence suggests that the human microbiome impacts cancerogenesis and cancer resistance to therapy. The mechanism of action and interaction of microbiome and PDAC is still under investigation. Direct and indirect effects have been proposed, and the use of several microbiome signatures as predictive and prognostic biomarkers for pancreatic cancer are opening new therapeutic horizons. In this review, we provide an overview for the clinicians of studies describing the influence and associations of oral, gastrointestinal and intratumoral microbiota on PDAC development, progression and resistance to therapy and the potential use of microbiota as a diagnostic, prognostic and predictive biomarker for PDAC.

IgG4-related disease: Changing epidemiology and new thoughts on a multisystem disease

IgG4-related disease (IgG4-RD) represents an immune-mediated fibroinflammatory condition with peculiar histopathologic changes that can affect various organs. In 2012 its unified nomenclature was published, which allows to abandon other synonymous names. Up to now, only little is known about its epidemiology around the world. However, although it is generally considered a rare condition, the number of patients with IgG4-RD is increasing enormously. Likewise, the annual number of publications on this subject has increased progressively. The spectrum of clinical manifestations in IgG4-RD is highly variable, depending on the severity of the disease as well as the presence of organ(s) involvement. This review gives an overview on changing epidemiology of IgG4-RD focusing the attention on the large cohorts of patients published in the literature.

The TEMPI syndrome

The TEMPI syndrome is a rare and acquired disorder characterized by 5 salient features, which compose its name: (1) telangiectasias; (2) elevated erythropoietin and erythrocytosis; (3) monoclonal gammopathy; (4) perinephric fluid collections; and (5) intrapulmonary shunting. Complete resolution of symptoms following treatment with plasma cell-directed therapy supports the hypothesis that the monoclonal antibody is causal and pathogenic. Understanding the basis of the TEMPI syndrome will depend on the identification of additional patients and a coordinated international effort.

Pancreatic Diseases and Microbiota: A Literature Review and Future Perspectives

Gut microbiota represent an interesting worldwide research area. Several studies confirm that microbiota has a key role in human diseases, both intestinal (such as inflammatory bowel disease, celiac disease, intestinal infectious diseases, irritable bowel syndrome) and extra intestinal disorders (such as autism, multiple sclerosis, rheumatologic diseases). Nowadays, it is possible to manipulate microbiota by administering prebiotics, probiotics or synbiotics, through fecal microbiota transplantation in selected cases. In this scenario, pancreatic disorders might be influenced by gut microbiota and this relationship could be an innovative and inspiring field of research. However, data are still scarce and controversial. Microbiota manipulation could represent an important therapeutic strategy in the pancreatic diseases, in addition to standard therapies. In this review, we analyze current knowledge about correlation between gut microbiota and pancreatic diseases, by discussing on the one hand existing data and on the other hand future possible perspectives.

IgG4-related disease: an update on pathophysiology and implications for clinical care

IgG4-related disease (IgG4-RD) has only existed as a unique disease entity since 2003, yet remarkable progress has already been achieved in describing the essential features of the disease. A framework for systematic clinical studies has been created by the development of a quantitative disease activity tool (the IgG4-RD Responder Index) and the validation of classification criteria, both of which were the products of international, multi-centre investigations. In addition, substantial strides have been made in understanding the pathophysiology of IgG4-RD. In particular, the central role of B cells in the disease has been demonstrated by both the robust clinical responsiveness of IgG4-RD to B cell depletion and by the identification of multiple self-antigens that promote B cell expansion. CD4⁺ T cells have also been investigated in detail; CD4⁺ cytotoxic T lymphocytes (suspected of promoting disease) and a specific T follicular helper cell subset that contributes to IgG4 isotype switching have both been defined by multiple groups. The mechanisms by which these immune cells converge on target tissues, interact with fibroblasts and promote tissue remodelling are beginning to be understood and will be an important research focus in the coming years.

Autoimmune pancreatitis - An ongoing challenge

Autoimmune pancreatitis is a rare form of chronic pancreatitis. The first descriptions of the disease date back to the 1990s. Etiology is multifactorial, with the use of genetic, environmental and complex immunological mechanisms. It is classified into two subtypes. Type 1 is part of a group of diseases called IgG4-related disease. Clinically is autoimmune pancreatitis manifested by icterus and abdominal discomfort. It can rarely present as acute pancreatitis. There is also a completely asymptomatic form of the disease. The diagnosis is based on abnormalities in histology, imaging methods, serology, the involvement of other organs in relation to IgG4-related disease, and a significant positive response to corticosteroid therapy. Differential diagnosis between the focal form of autoimmune pancreatitis and pancreatic cancer can be complicated, with endosonography playing an important role. In the treatment, we use corticosteroids and other immunosuppressants including biological therapy. Patients with the asymptomatic disease should also be treated to prevent late complications and exocrine and endocrine insufficiency. In addition to drug treatment, endoscopic and/or surgical treatment may be necessary. Even after recovery, the disease can relapse. The relationship between autoimmune pancreatitis and malignancies has not been clearly confirmed. The goal of this review is to provide a comprehensive look at autoimmune pancreatitis and translate latest scientific knowledge into clinical practice.

Steroid-responsive pancreatitides

Autoimmune pancreatitis has received considerable attention, especially due to the marked effect of corticosteroid therapy on its clinical course. Knowledge, especially regarding type 1 autoimmune pancreatitis, has significantly increased over the last decades, and despite significant differences in pathophysiology and outcomes, both type 1 and 2 autoimmune pancreatitis are still considered different types of the same disease. Some have proposed a different nomenclature reflecting these differences. Although the term steroid-responsive pancreatitides may be interpreted as synonymous to type 1 and 2 autoimmune pancreatitis, these are not the only pancreatic conditions that show a response to steroid therapy. Acute pancreatitis caused by vasculitis and connective tissue diseases and acute pancreatitis secondary to checkpoint inhibitors or programmed cell death receptor antibody-mediated blockage cancer therapy may also benefit from steroid treatment. This review presents current concepts on these disorders, aiming to increase awareness, analyze similarities and differences, and propose a new nomenclature that reflects their specific particularities, clustering them under the term “steroid-responsive pancreatitides”.

IgG4-related focal retroperitoneal fibrosis in ureter suggestive of colon cancer recurrence and resected laparoscopically: a case report

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is a novel disease concept of unknown cause that is characterized by abundant infiltration of IgG4-positive cells, mass-forming lesions, and elevated serum IgG4 levels. The infiltration of IgG4-positive plasma cells and lymphocytes causes swelling, inflammation, fibrosis, and obliterative phlebitis in multiple organs. On the other hand, IgG4-RD occurring in the ureters has rarely been reported. To our knowledge, this is the first report of laparoscopic partial ureteral resection for IgG4-related focal retroperitoneal fibrosis in a ureter with suspected colon cancer recurrence.

CASE PRESENTATION

A 72-year-old man with a history of sigmoid colon cancer visited Shiga University of Medical Science Hospital for regular follow-up in December 2019. Enhanced abdominal computed tomography revealed a mass involving the left ureter. Furthermore, fluorine-18 fluorodeoxyglucose positron emission tomography showed significant accumulation of fluorodeoxyglucose uptake in the same region. Due to the possibility of colon cancer recurrence, a laparoscopic excisional biopsy with partial ureteral resection was performed. Histologically, IgG4-positive plasma cell infiltration exceeding 10 cells per high-power field and a high ratio of IgG4-positive/IgG-positive cells exceeding 40% were observed. The postoperative serum IgG4 level was 384 mg/dL. With the application of these findings to the diagnostic algorithm in the comprehensive diagnostic criteria for IgG4-RD, the mass-forming lesion was diagnosed as definitive IgG4-related focal retroperitoneal fibrosis.

CONCLUSIONS

IgG4-RD should be considered in the differential diagnosis of retroperitoneal lesions. Moreover, laparoscopic surgery may be useful for making the diagnosis in difficult-to-biopsy cases.

IgG4-related disease in the abdomen and pelvis: atypical findings, pitfalls, and mimics

IgG4-related disease (IgG4-RD) is a systemic, autoimmune, fibroinflammatory disease that can cause multi-organ damage. Although there have been many trials and studies since its recognition in 2003, there is still much that is unknown. Furthermore, IgG4-RD can affect any organ in the body and often has many mimics and alternative diagnoses, which can make for a challenging workup. Imaging plays a substantial role in the diagnosis of IgG4-RD and is often the first occasion where IgG4-RD comes into consideration. Thus, knowledge about the imaging findings of various manifestations of IgG4-RD can aid in the diagnosis and have a significant impact on patient management. In this article, we review the wide array of imaging findings, both typical and atypical, as well as possible mimics of IgG4-RD in the abdomen and pelvis.

[IgG4-related disease: Diagnostic criteria evolution toward the 2019 ACR/EULAR classification criteria]

The concept of IgG4-related disease (IgG4-RD) has recently been individualized in the early 2000s, but most of the organ involvements are known since more than 100 years. IgG4-RD is a non-malignant fibroinflammatory disorder, characterized by peculiar immunological and pathological abnormalities, which can affect virtually all organs or tissues. Diagnostic criteria have been proposed and have evolved rapidly, with general or organ specific criteria. An international and multidisciplinary group assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR) has recently developed and validated a set of classification criteria called 2019 ACR/EULAR classification criteria for IgG4-related disease. The objective of this review is to discuss the evolution from organ specific and general diagnostic criteria toward the 2019 ACR/EULAR classification criteria, as well as respective benefits and limits of these criteria. The use of the 2019 ACR/EULAR classification criteria will help to better define homogeneous group of IgG4-RD patients in future clinical, epidemiological and basic science research studies on the disease.

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.

Association between Active Helicobacter pylori Infection and Glaucoma: A Systematic Review and Meta-Analysis

Background: Glaucoma is the second most common cause of blindness worldwide affecting almost 70 million individuals. Helicobacter pylori (H. pylori) is a widespread pathogen with systematic pathogenicity. This meta-analysis aimed to estimate the contradictory data regarding a potential association between active H. pylori infection and glaucoma. Materials and Methods: A research in MEDLINE/PubMed and Google Scholar was conducted and original studies investigating the relationship between H. pylori infection and glaucoma were included. Analysis was performed with random effects model. The main outcome was the odds ratio (OR) with 95% confidence intervals (CI) of H. pylori infection as a risk factor for glaucoma. A parallel analysis studied the role of active infection as indicated by histology and the titer of anti-H. pylori antibodies. For the anti-H. pylori antibody titers, weighted mean differences (WMD) were estimated between patients and controls. Results: Fifteen studies were included, with 2664 participants (872 patients with glaucoma and 1792 controls), divided into primary open-angle glaucoma (POAG), normal tension glaucoma (NTG) and pseudo-exfoliation glaucoma (PEG). The association between H. pylori infection and overall glaucoma was significant (OR = 2.08, CI 95% 1.48–2.93) with moderate heterogeneity (I² = 61.54%). After stratification by glaucoma subtype, heterogeneity was eliminated in the NTG subgroup. Studies with healthy controls, and controls with anemia yielded very low or no heterogeneity, respectively. Gastric biopsy to document active H. pylori infection yielded the highest OR (5.4, CI: 3.17–9.2, p < 0.001) and null heterogeneity. For anti-H. pylori antibody titers, there was a significant difference in WMD between patients and controls (WMD 15.98 IU/mL; 95% CI: 4.09–27.87; p = 0.008); values were greater in glaucoma patients, with high heterogeneity (I²: 93.8%). Meta-regression analysis showed that mean age had a significant impact on glaucoma (p = 0.037). Conclusions: Active H. pylori infection may be associated with glaucoma with null heterogeneity, as, beyond histology, quantified by anti-H. pylori titers and increases with age.

Oncobiosis and Microbial Metabolite Signaling in Pancreatic Adenocarcinoma

Pancreatic adenocarcinoma is one of the most lethal cancers in both men and women, with a median five-year survival of around 5%. Therefore, pancreatic adenocarcinoma represents an unmet medical need. Neoplastic diseases, such as pancreatic adenocarcinoma, often are associated with microbiome dysbiosis, termed oncobiosis. In pancreatic adenocarcinoma, the oral, duodenal, ductal, and fecal microbiome become dysbiotic. Furthermore, the pancreas frequently becomes colonized (by Helicobacter pylori and Malassezia, among others). The oncobiomes from long- and short-term survivors of pancreatic adenocarcinoma are different and transplantation of the microbiome from long-term survivors into animal models of pancreatic adenocarcinoma prolongs survival. The oncobiome in pancreatic adenocarcinoma modulates the inflammatory processes that drive carcinogenesis. In this review, we point out that bacterial metabolites (short chain fatty acids, secondary bile acids, polyamines, indole-derivatives, etc.) also have a role in the microbiome-driven pathogenesis of pancreatic adenocarcinoma. Finally, we show that bacterial metabolism and the bacterial metabolome is largely dysregulated in pancreatic adenocarcinoma. The pathogenic role of additional metabolites and metabolic pathways will be identified in the near future, widening the scope of this therapeutically and diagnostically exploitable pathogenic pathway in pancreatic adenocarcinoma.

Orbital inflammation and colitis in pediatric IgG4-related disease: A case report and review of the literature

IgG4-related disease (IgG4-RD) is an inflammatory disorder characterized by tumor-like swelling in one or more organs, elevated serum IgG4 levels, and histological alterations with infiltration of IgG4-positive plasma cells. IgG4-RD is rare and likely underdiagnosed in children. We report a case of a 16-year-old girl with IgG4-positive colitis that developed weeks after IgG4-related ophthalmic disease and discuss diagnosis and treatment in the context of the literature available. Since the pathophysiology of IgG4-RD is unknown, treatment options are empiric and, for the most part, untargeted. Systemic corticosteroid treatment is the basis of anti-inflammatory treatment in IgG4-RD and induced early remission in our patient. During corticosteroid taper, the patient developed weight loss and intestinal inflammation. Histopathological assessment of the intestinal walls confirmed IgG4-positive colitis. Immune-modulating treatment with non-biologic (e.g., methotrexate (MTX) and mycophenolate mofetil) or biologic (rituximab) disease-modifying antirheumatic drugs has been reported in treatment refractory or corticosteroid-dependent patients. The patient responded to treatment with anti-inflammatory therapy with food rich in TGF-β2 (modulen) and MTX. This is one of the first pediatric patients reported with IgG4-related colitis extending the phenotype of pediatric IgG4-RD. International collaboration to prospectively document clinical presentation and treatment responses may help to further establish the phenotype and treatment options and to raise awareness for IgG4-RD.

Tumefactive Inflammatory Diseases of the Pancreas

Advances in the past two decades have resulted in the recognition of several tumefactive pancreatic lesions that, on histologic evaluation, show a varying combination of inflammation and fibrosis. Autoimmune pancreatitis, the prototypic tumefactive pancreatic fibroinflammatory lesion, is composed of two distinct diseases, type 1 autoimmune pancreatitis and the less common type 2 autoimmune pancreatitis. Although designated as autoimmune pancreatitis, the two diseases show little morphologic or pathogenic overlap. In type 1 disease, subsets of T lymphocytes (type 2 helper T cells, regulatory T cells, and T follicular helper 2 cells) are hypothesized to drive the inflammatory reaction. The B-cell response is characterized by an oligoclonal expansion of plasmablasts, with dominant clones that vary among patients and distinct clones that emerge at the time of relapse. Although the precise role of IgG4 in this condition remains uncertain, recent studies suggest that other IgG subclasses (eg, IgG1) may mediate the immune reactions, whereas IgG4 represents a response to dampen excessive inflammation. A recent study of type 2 autoimmune pancreatitis highlights the role of CXCL8 (alias IL-8), with duct epithelium and infiltrating T lymphocytes expressing this chemokine; the latter may contribute to the distinct form of neutrophilic inflammation in this disease. The review also highlights other forms of mass-forming chronic pancreatitis: follicular pancreatitis, groove pancreatitis, and those associated with rheumatologic diseases.