K-ras mutation in the major duodenal papilla and gastric and colonic mucosa in patients with autoimmune pancreatitis

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.

The risk of malignancy in patients with IgG4-related disease: a systematic review and meta-analysis

BACKGROUND

The relationship between IgG4-related disease (IgG4-RD) and the risk of malignancy is still controversial. This article focused on assessing the risk of cancer in patients with IgG4-RD by meta-analysis.

METHODS

We conducted a systematic review of the literature and meta-analysis characterizing the associated risk of overall malignancy and four site-specific malignancies (pancreas, lung, gastric and lymphoma) in patients with IgG4-RD. A search from 2003 to 2020 was performed using specified terms from PubMed, Embase, Web of Science and SinoMed. Random-effects model analysis was used to pool standardized incidence ratios (SIRs) and 95% confidence intervals (CIs). Subgroup and sensitivity analyses were conducted to clarify the heterogeneity of the included studies. Begg's funnel plot and Egger's linear regression test were used to evaluate the bias of the meta-analysis. A P value < 0.05 indicated the existence of publication bias.

RESULTS

A total of 10 studies were included in the article. The overall SIR estimates suggested an increased risk of overall cancer in IgG4-RD patients (SIR 2.57 95% CI 1.72-3.84) compared with the general population. The specific SIRs for pancreas and lymphoma were higher than those of the general population in IgG4-RD patients (SIR 4.07 95% CI 1.04-15.92, SIR 69.17 95% CI 3.91-1223.04, respectively). No significant associations were revealed in respiratory and gastric cancer (SIR 2.14 95% CI 0.97-4.75, SIR 0.95 95% CI 0.24-3.95, respectively). Four studies were found to be the major sources of heterogeneity by sensitivity analysis. There was no evidence of publication bias via Egger's test.

CONCLUSION

Compared with the general population, patients with IgG4-RD appear to have a higher risk of overall cancer, especially pancreatic and lymphoma. The risk of lung and gastric cancer was not different between IgG4-RD patients and the general population.

Focal IgG4-related autoimmune pancreatitis with distal choledochal adenocarcinoma: a rare case report

Background

Autoimmune pancreatitis (AIP) is a rare disease that manifests as pancreatic involvement in systemic IgG4-related disease (IgG4-RD), a special type of chronic pancreatitis caused by autoimmune abnormalities. The main imaging manifestations of IgG4-related AIP consist of diffuse or localized pancreatic enlargement and irregular pancreatic duct narrowing. The diagnosis of AIP is challenging because it can present with focal lesions, similar to radiologically bile duct cancer or pancreatic cancer.

Case presentation

A 55-year-old male patient was admitted with painless jaundice and multiple radiographic findings of pancreatic head mass, as well as intrahepatic and extrahepatic bile duct dilatation. Various imaging methods indicated pancreatic cancer. However, the endoscopic ultrasonography guided fine needle aspiration (EUS-FNA) and a laparoscopic pancreatic biopsy suggested an IgG4-related AIP. After one month, magnetic resonance imaging showed that the lesion had slightly grown. Combined with CA19-9 and other indexes, the possibility of malignancy was high and there were still surgical indications. The pathological analysis following a pancreaticoduodenectomy revealed poorly differentiated adenocarcinoma in the distal common bile duct.

Conclusion

To date, few reports have described pancreatic or extrapancreatic malignancies in AIP patients, and no association between AIP and bile duct adenocarcinoma has been previously confirmed. This case discuss the differentiation between AIP and malignancy, recent research progress, and the correlation between the two diseases, highlights the importance of carefully evaluating patients with AIP to rule out potential tumors, as well as the critical need for follow up treatment.

European Guideline on IgG4-related digestive disease - UEG and SGF evidence-based recommendations

The overall objective of these guidelines is to provide evidence-based recommendations for the diagnosis and management of immunoglobulin G4 (IgG4)-related digestive disease in adults and children. IgG4-related digestive disease can be diagnosed only with a comprehensive work-up that includes histology, organ morphology at imaging, serology, search for other organ involvement, and response to glucocorticoid treatment. Indications for treatment are symptomatic patients with obstructive jaundice, abdominal pain, posterior pancreatic pain, and involvement of extra-pancreatic digestive organs, including IgG4-related cholangitis. Treatment with glucocorticoids should be weight-based and initiated at a dose of 0.6-0.8 mg/kg body weight/day orally (typical starting dose 30-40 mg/day prednisone equivalent) for 1 month to induce remission and then be tapered within two additional months. Response to initial treatment should be assessed at week 2-4 with clinical, biochemical and morphological markers. Maintenance treatment with glucocorticoids should be considered in multi-organ disease or history of relapse. If there is no change in disease activity and burden within 3 months, the diagnosis should be reconsidered. If the disease relapsed during the 3 months of treatment, immunosuppressive drugs should be added.

Malignancy and IgG4-related disease: the incidence, related factors and prognosis from a prospective cohort study in China

This prospective cohort study aims to investigate the incidence, related factors and prognosis of IgG4-related disease (IgG4-RD) with malignancies in the Chinese cohort. We prospectively analyzed the IgG4-RD patients recruited in Peking Union Medical College Hospital from January 2011 to August 2018 and identified patients diagnosed with IgG4-RD complicating malignancies. Data regarding demographics, clinical features, treatment and prognosis of IgG4-RD patients complicating malignancies were collected and compared to those of age- and sex-matched controls. Among the 587 Chinese patients with IgG4-RD, 17 malignancies were identified. Ten of them developed malignancy after the diagnosis of IgG4-RD, given a standard incidence ratio (SIR) of 2.78 (95%CI 1.33-5.12). Multivariate logistic analysis indicated that autoimmune pancreatitis (OR = 6.230, 95%CI 1.559-24.907, p = 0.010) was positively associated with malignancy, whereas eosinophilia (OR = 0.094, 95%CI 0.010-0.883, p = 0.039) was negatively related with malignancies. During a median follow-up period of 61.4 ± 26.4 months, all patients with IgG4-RD and malignancies survived. We conclude that an increased incidence of malignancy was found in Chinese IgG4-RD cohort. Autoimmune pancreatitis is a potential risk factor, whereas eosinophilia is a possible protective factor for complicating malignancies.

Recent Updates on the Relationship between Cancer and Autoimmune Pancreatitis

Autoimmune pancreatitis (AIP) is now considered a pancreatic manifestation of a newly proposed disease condition, IgG4-related disease (IgG4-RD). IgG4-RD is characterized by enhanced IgG4 antibody responses and multiple organ involvements. Recent epidemiological studies have addressed the incidence of cancer in patients with AIP and/or IgG4-RD. Surprisingly, a significant number of AIP patients were detected with cancer at or within one year of the diagnosis of AIP. Furthermore, around 50% of all cancers detected in AIP patients comprised mainly 3 types (gastric, lung, and prostate cancer). Thus, AIP appears to be associated with cancer of other organs rather than the pancreas itself, which suggests that AIP is not a pre-cancerous condition of the pancreas. Moreover, the simultaneous occurrence of cancer and AIP in many patients has led to the establishment of an attractive concept that AIP might sometimes arise from co-existing cancers as a paraneoplastic syndrome.

Up-regulation of activation-induced cytidine deaminase and its strong expression in extra-germinal centres in IgG4-related disease

Immunoglobulin (Ig) G4-related disease (IgG4-RD) is a systemic disorder involving benign mass formation due to fibrosis and intense lymphoplasmacytosis; the chronic inflammation associated with the disease might also contribute to oncogenesis. Activation-induced cytidine deaminase (AID), normally expressed in germinal centre activated B-cells, is an enzyme that edits DNA/RNA and induces somatic hypermutation and Ig class switching. AID expression is strictly controlled under physiological conditions; however, chronic inflammation and some infectious agents induce its up-regulation. AID is overexpressed in various cancers and may be important in chronic inflammation-associated oncogenesis. We examined AID expression in IgG4-related sialadenitis (n = 14), sialolithiasis (non-specific inflammation, n = 13), and normal submandibular glands (n = 13) using immunohistochemistry and quantitative real-time polymerase chain reaction (qPCR). Immunohistochemistry revealed significantly more AID-expressing cells in IgG4-related sialadenitis than in sialolithiasis or normal submandibular gland samples (P = 0.02 and P < 0.01, respectively); qPCR yielded similar results. Thus, AID was significantly more up-regulated and had higher expression in extra-germinal centres in IgG4-RD than in non-specific inflammation or normal conditions. This report suggests that IgG4-RD has several specific causes of AID up-regulation in addition to inflammation. Furthermore, chronic inflammation-associated AID-mediated oncogenesis is possible in IgG4-RD.

Distinct cytokine mRNA expression pattern in immunoglobulin G4-related kidney disease associated with renal cell carcinoma

We treated a 61-year-old man with immunoglobulin (Ig)G4-related kidney disease (IgG4-RKD). He had a history of allergic diseases and an allergic reaction and had received a diagnosis of autoimmune pancreatitis (AIP). He had also received a diagnosis of renal cell carcinoma (RCC) and had undergone segmental resection of the left kidney at 59 years of age. His serum amylase level and number of peripheral eosinophils increased after RCC development. We hypothesized that the RCC may have induced AIP and IgG4-RKD and we therefore examined the excised RCC tissue; typical findings of IgG4-RKD associated with RCC were recognized. We next evaluated the mRNA expression of cytokines in the excised tissues of this case and ten other ordinary RCC cases. In all cases, notable levels of IL-10 mRNA and high levels of TGF-β mRNA were seen. Although prominent differences were not observed in the mRNA expression of Th1, Th17 and Treg cytokines in all cases, the present case alone showed increased production of the Th2 cytokines IL-4 and IL-5, which were not detected in ordinary RCC cases. Although the mechanism underlying IgG4-RKD development has not yet been determined, Th2 and Treg cells are thought to play a prominent role in the pathogenesis. It is therefore likely that in this case, the association of these two diseases was not coincidental, and a distinct immune response against RCC may trigger IgG4-RKD development.

Association between autoimmune pancreatitis and malignancy

Chronic inflammatory diseases are often associated with malignancy, and this phenomenon occurs even in the field of gastroenterology. For example, chronic pancreatitis has been reported to be highly associated with the occurrence of pancreatic cancer. However, the association between autoimmune pancreatitis (AIP) and pancreatic cancer is still an unsolved problem. As AIP is associated with immunoglobulin G4-related disease, which causes a variety of inflammatory and fibrotic lesions, the association between AIP and total malignancies is also a matter of interest. Here, we discuss the association between AIP and malignancy. As for the association between AIP and pancreatic cancer, there is no conclusive evidence, although several reports have suggested that the relative risk of pancreatic cancer is high in AIP. Concerning the association between AIP and total malignancies, there are two reports from Japan. Neither report supported the idea that chronic inflammation in AIP caused the increased risk of total malignancies. However, one report proposed the possibility that AIP might develop as a paraneoplastic syndrome in some patients because many cancers occurred within 1 year of AIP diagnosis, and thereby concluded that patients with AIP were at high risk of having various cancers. The paraneoplastic syndrome hypothesis should be tested in future studies.

Current status of research on autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a form of chronic pancreatitis characterized clinically by frequent presentation with obstructive jaundice, histologically by lymphoplasmacytic infiltration with fibrosis, and therapeutically by a dramatic response to steroids. AIP have recently been classified into two subtypes, lymphoplasmacytic sclerosing pancreatitis (LPSP) and idiopathic duct centric pancreatitis (IDCP). The pathogenesis of AIP may involve genetic susceptibility, autoantibodies, molecular mimicry, imbalance of T-cell-mediated immune regulation, and gene mutation. In this article, we will systematically review typical and atypical clinical, imaging and histopathological features of AIP, with an emphasis placed on the advances in the diagnosis and treatment of this disease.

A case of pancreatic ductal adenocarcinoma with marked infiltration with IgG4-positive cells

A 75-year-old man was diagnosed as having pancreatic ductal carcinoma containing remarkable lymphocytic and plasma cell infiltration, as revealed by the cytological examination of endoscopic ultrasound guided fine-needle aspiration (EUS-FNA) specimen. The EUS-FNA specimen showed small amounts of atypical epithelium with noticeable lymphocytes and plasma cells. A pancreatic resection was performed, and the histopathological features showed an invasive pancreatic ductal carcinoma with autoimmune pancreatitis (AIP) lymphoplasmacytic sclerosing pancreatitis (LPSP)-like lesions. Most of the plasma cells were immunoreactive to anti-IgG4 antibody. EUS-FNA may be necessary for the differential diagnosis of AIP and pancreatic cancer, and close attention should be given to the presence of marked lymphoplasmacytic cells in EUS-FNA specimens while making the diagnosis.

Management strategies for autoimmune pancreatitis

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Autoimmune pancreatitis and IgG4-related sclerosing cholangitis

PURPOSE OF REVIEW

Autoimmune pancreatitis (AIP) is a peculiar type of pancreatitis with a presumed autoimmune etiology. AIP is frequently associated with stenosis of the bile duct in the form of IgG4-related sclerosing cholangitis. This article reviews recent advances in clinicopathological findings for AIP and IgG4-related sclerosing cholangitis.

RECENT FINDINGS

AIP is currently diagnosed based on characteristic radiological findings (irregular narrowing of the main pancreatic duct and enlargement of the pancreas) in combination with serological findings (elevated serum IgG4 and presence of autoantibodies) and histopathological findings (dense infiltration of IgG4-positive plasma cells and lymphocytes with fibrosis and obliterative phlebitis in the pancreas). Other clinical characteristics include preponderance toward elderly men, common initial symptoms of obstructive jaundice, and favorable response to steroid therapy. Differentiation of AIP from pancreatic cancer is crucial. As AIP is frequently associated with various sclerosing extrapancreatic lesions showing the same peculiar histological findings seen in the pancreas, AIP is currently considered to represent a pancreatic manifestation of IgG4-related sclerosing disease. Considering the age of onset, associated diseases, cholangiography, serum IgG4 levels, and steroid responsiveness, IgG4-related sclerosing cholangitis differs from primary sclerosing cholangitis.

SUMMARY

AIP and associated extrapancreatic lesions are considered to represent clinical manifestations of IgG4-related sclerosing disease.

Autoimmune pancreatitis and IgG4-related sclerosing disease

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