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

Rare genetic variants provide a mechanistic basis for immune imbalance in IgG4-related disease

Autoimmune diseases are commonly associated with a polygenic inheritance pattern. In rare instances, causal monogenic variants have been identified. The study by Liu et al. in this issue of the JCI provides an example of monogenic variants occurring in patients with IgG4-related disease (IgG4-RD). The authors investigated a familial cluster of IgG4-RD that consisted of an affected father and two daughters; the mother was unaffected. Genome sequencing of this quad identified a variant in IKZF1 (encoding IKAROS) and another variant in UBR4 (encoding E3 ubiquitin ligase). Both variants were present in the father and both daughters but absent in the unaffected mother. Using multidimensional profiling of immune cells and functional experiments in primary cells, the authors determined a molecular pathway contributing to T cell activation in IgG4-RD. Importantly, the characterization of these variants provides insights into pathogenic mechanisms in IgG4-RD and, potentially, other autoimmune diseases.

Duodenal stricture secondary to IgG4-related chronic sclerosing duodenitis-A case report with review of the literature

Key Clinical Message

This case highlights the importance of a definite diagnosis of an IgG4-related chronic sclerosing duodenitis based on histological and radiological findings to rule out any malignancy in the mass. While dealing with patients having concentric duodenal thickening resulting in stricture formation, one should think of inflammatory etiology as well. IgG4-related disease is one of these inflammatory disorders where we see soft tissue thickening without a large mass or any associated lymphadenopathy as in our case.

Abstract

Immunoglobulin G4-related disease (IgG4-RD) is distinguished as an infiltration of IgG-4-positive plasmacytes involving inflammatory lesions across multiple organs which is accompanied by raised IgG4 levels in the serum. Several inflammatory disorders are recognized as part of the IgG4-RD family based on shared histopathological features, which include Mikulicz's disease, chronic sclerosing sialadenitis, or Riedel's thyroiditis. Our case highlights a distinctive presentation of IgG4-related diseases; a 58-year-old man presenting with duodenal stricture highly suspicious of a duodenal mass/ampullary mass later found to be due to IgG4-related sclerosing duodenitis with negative malignancy on biopsy. We present the diagnostic challenges faced and relevant findings noted.

Pathogenesis of Warthin's Tumor: Neoplastic or Non-Neoplastic?

Warthin's tumor is the second most frequent neoplasm next to pleomorphic adenoma in the salivary gland, mostly in the parotid gland. The epithelial cells constituting a tumor are characterized by the presence of mitochondria that undergo structural and functional changes, resulting in the development of oncocytes. In addition to containing epithelial cells, Warthin's tumors contain abundant lymphocytes with lymph follicles (germinal centers) that are surrounded by epithelial cells. The pathogenesis of Warthin's tumor is not fully understood, and several hypotheses have been proposed. The risk factors for the development of Warthin's tumor, which predominantly occurs in males, include aging, smoking, and radiation exposure. Recently, it has been reported that chronic inflammation and aging cells promote the growth of Warthin's tumor. Several reports regarding the origin of the tumor have suggested that (1) Warthin's tumor is an IgG4-related disease, (2) epithelial cells that compose Warthin's tumor accumulate mitochondria, and (3) Warthin's tumor is a metaplastic lesion in the lymph nodes. It is possible that the pathogenesis of Warthin's tumor includes mitochondrial metabolic abnormalities, accumulation of aged cells, chronic inflammation, and senescence-associated secretory phenotype (SASP). In this short review, we propose that DNA damage, metabolic dysfunction of mitochondria, senescent cells, SASP, human papillomavirus, and IgG4 may be involved in the development of Warthin's tumor.

The significant IgG4 infiltrate in autoimmune hepatitis is associated with a greater ductular reaction and more advanced liver disease

BACKGROUND

Sclerosing cholangitis is the typical IgG4-related disease digestive involvement. However, the role of the IgG4 liver expression in autoimmune hepatitis remains unknown.

AIMS

to assess whether the expression of IgG4 plasma cells in patients with autoimmune hepatitis (AIH) was associated with different outcomes.

METHODS

Retrospective study including patients diagnosed with AIH by biopsy from January-2009 to June-2021. At least mild IgG4 expression (>10 IgG4+-plasma cells per field) was considered as significant.

RESULTS

85 patients with AIH were included. Overall, 58.8% were women, mean age 54 years. Nine (10.6%) presented cirrhosis at diagnosis. Fifteen (17.6%) had significant IgG4 liver expression. Patients with IgG4 infiltrate were older (p = 0.021), presented liver cirrhosis more frequently (33.3% vs. 5.7%, p = 0.007), greater IgG plasma values (p = 0.008) and atypical ANCAs (p = 0.086); ductular reaction was also more common (p = 0.009). Complete remission rate was similar regardless of the IgG4 infiltrate. Time to corticosteroids discontinuation was longer in subjects with IgG4 infiltrate (p = 0.068), but second-line therapy tended to be less frequent (p = 0.187).

CONCLUSION

Significant IgG4 liver infiltrate in patients with autoimmune hepatitis is associated with more advanced liver disease. The greater ductular reaction mediated by the IgG4 infiltrate may be the cause for this finding, though this finding should be prospectively assessed.

IgG4-Related Disease of the Central Nervous System: A Case Series

IgG4-related disease (IgG4-RD) is a rare and often misdiagnosed disorder with limited literature that highlights the different neurological presentations of this treatable disease. The diagnosis of IgG4-RD could be challenging, while imaging is fundamental for the diagnosis, biopsy is considered the gold standard. Most cases respond well to steroids and immunosuppressive therapy. This is a case series study that illustrates the varied neurological presentations of IgG4-RD through three different patients that were followed at the Montreal Neurological Institute. This paper takes you through the diagnostic strategy that we followed to accurately diagnose and treat those patients.

Clinical features and relapse risks factors of IgG4 related disease: a single-center retrospective study

OBJECTIVE

The aim of this study was to observe the demographic and clinical characteristics of immunoglobulin (Ig) G4-related disease (IgG4-RD). We aimed to compare different treatment methods and to identify the risk factors for non-response and relapse after treatment.

METHODS

We performed a retrospective study of 201 IgG4-RD patients initially diagnosed and treated at the First Affiliated Hospital of China Medical University from January 2016 to December 2020. Patients' sex, age, clinical manifestations, baseline biochemical values, the number of organs involved, and the type of organ involvement were recorded. All patients received glucocorticoid (GC) monotherapy or GC + immunosuppressant combination therapy. The serum IgG4 concentration as well as the details of clinical response, relapse, and side effects were recorded at 1, 3, 6, and 12 months after treatment.

RESULTS

The incidence of IgG4-RD was primarily centered in the age group of 50-70 years old, and the proportion of affected male patients increased with age. The most common clinical symptom was swollen glands or eyes (42.79%). The rates of single- and double-organ involvement were 34.83% and 46.27%, respectively. The pancreas (45.77%) was the most frequently involved organ in cases of single-organ involvement, and the pancreas and biliary tract (45.12%) was the most common organ combination in cases of double-organ involvement. Correlation analysis showed that the number of organs involved was positively related to the serum IgG4 concentration (r = 0.161). The effective rate of GC monotherapy was 91.82%, the recurrence rate was 31.46%, and the incidence of adverse reactions was 36.77%. Meanwhile, the effective rate of GC + immunosuppressant combination therapy was 88.52%, the recurrence rate was 19.61%, and the adverse reaction rate was 41.00%. There were no statistically significant differences in response, recurrence, and adverse reactions. The overall response rate within 12 months was 90.64%. Age (< 50 years old) and aorta involvement were significantly associated with non-response. The overall recurrence rate within 12 months was 26.90%. Age (< 50 years old), low serum C4 concentration, a high number of involved organs, and lymph node involvement were significantly associated with recurrence.

CONCLUSION

The clinical features vary among different age groups and according to gender. The number of organs involved in IgG4-RD is related to the serum IgG4 concentration. Age (< 50 years old), low serum C4 concentration, a high number of involved organs, and lymph node involvement are risk factors for recurrence.

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.

Gastroenterological Manifestations of Immunoglobulin G Subclass 4-Related Disease-Epidemiology, Clinical Manifestations, Diagnosis and Treatment

Despite causing high morbidity, IgG4-related disease (IgG4-RD) and its gastroenterological manifestations lack better and greater theoretical contributions. Therefore, the objective of this work was to evaluate the clinical-epidemiological, diagnostic and treatment aspects of the gastrointestinal manifestations of this disease. A systematic review was carried out using the PubMed, Scopus and Embase databases between January 2012 and March 2023 with the following descriptors: "Immunoglobulin G4-Related Disease" (MeSH) AND #2 "Gastrointestinal Tract" (MeSH). Our data collection grouped a total of 3607 patients from mostly epidemiological cohort studies and cross-sectional follow-ups. In the subgroup analysis, IgG4-RD was associated with male gender, with an estimated prevalence between 54% and 80%. In our findings, the prevalence by topography was presented in the following ranges: lacrimal glands (17-57%); salivary glands (28-72%); pancreas (19-60%); biliary tract (5-40%); retroperitoneal cavity (9-43%). Longitudinal studies are needed to better map the natural history of the gastrointestinal manifestations of IgG4-RD and enable the formulation of individualized treatments.

Bile Duct Lithiasis Mimicking a Perihilar Cholangiocarcinoma-An Endless Dilemma: A Case Report

Hilar bile duct strictures are mostly caused by malignant lesions. The morphological appearance of perihilar cholangiocarcinomas in various imaging modalities have other malignant and even benign mimics, which pose challenges to an accurate diagnosis and treatment and drive to futile surgery. Herein, we present the case of a 50-year-old woman admitted with jaundice and abdominal pain, elevated bilirubin level, liver function tests and carbohydrate antigen 19-9 level. Magnetic resonance cholangio-pancreatography (MR-CP) and the computed tomography with contrast enhancement revealed a suspected extrahepatic cholangiocarcinoma of the common bile duct. Further spontaneous resolution of the scenario, confirmed by diagnostic assessment, changed the clinical hypothesis in favor of a non-oncological disease. Indeed, the multidisciplinary evaluation supported a diagnosis of transient cholangitis secondary to non-evident intrahepatic lithiasis rather than cholangiocarcinoma. After a 26-month follow-up, the patient was asymptomatic with normal tumor markers and laboratory data. Consecutive MR-CPs showed no suspicion of malignancy. This case report underlines the need for an accurate preoperative assessment in patients with suspected cholangiocarcinoma.

Focal IgG4-related periprostatic "PI-RADS 5" pseudotumor mimicking prostatic adenocarcinoma

Immunoglobulin G4-related disease (IgG4-RD) is a systemic fibroinflammatory disease characterized by raised serum IgG4 levels and tumefactive inflammation affecting multiple organ systems, typically involving the pancreas and biliary tree. Though rare, prostatic involvement has been reported in a few cases and is suspected to be an underreported entity. Our patient is a 63-year-old gentleman who has presented with an incidental "PI-RADS 5" (Prostate Imaging Reporting & Data System) prostate lesion and perivascular soft tissue cuffing of the superior rectal vessels on MRI rectum performed for surveillance of rectal neuroendocrine tumor. He had a history of lacrimal gland IgG4-RD. The lentiform prostate lesion subtly indents the prostate capsule, reminiscent of a periprostatic rather than an intraprostatic lesion. Perivascular cuffing of superior rectal vessels suggest inflammatory vasculitis of IgG4-RD. Differential diagnosis of periprostatic inflammatory IgG4-RD was considered, subsequently proven on MRI-ultrasound fusion targeted biopsy. Reported radiological findings of prostate IgG4-RD typically show diffuse chronic inflammation of the prostate, with a minority of the reports describing focal involvement, often mimicking focal prostate adenocarcinoma. Focal periprostatic involvement of IgG4-RD is an unusual manifestation which should be considered in patients with IgG4-RD who present with a periprostatic pseudotumor. IgG4-RD of the prostate usually responds well to steroid treatment without the need for surgery.

Basophils beyond allergic and parasitic diseases

Basophils bind IgE via FcεRI-αβγ2, which they uniquely share only with mast cells. In doing so, they can rapidly release mediators that are hallmark of allergic disease. This fundamental similarity, along with some morphological features shared by the two cell types, has long brought into question the biological significance that basophils mediate beyond that of mast cells. Unlike mast cells, which mature and reside in tissues, basophils are released into circulation from the bone marrow (constituting 1% of leukocytes), only to infiltrate tissues under specific inflammatory conditions. Evidence is emerging that basophils mediate non-redundant roles in allergic disease and, unsuspectingly, are implicated in a variety of other pathologies [e.g., myocardial infarction, autoimmunity, chronic obstructive pulmonary disease, fibrosis, cancer, etc.]. Recent findings strengthen the notion that these cells mediate protection from parasitic infections, whereas related studies implicate basophils promoting wound healing. Central to these functions is the substantial evidence that human and mouse basophils are increasingly implicated as important sources of IL-4 and IL-13. Nonetheless, much remains unclear regarding the role of basophils in pathology vs. homeostasis. In this review, we discuss the dichotomous (protective and/or harmful) roles of basophils in a wide spectrum of non-allergic disorders.

Unusual Manifestation of Immunoglobulin G4-Related Disease Involving the Upper Arm: A Case Report

Immunoglobulin G4 (IgG4)-related disease is a rare systemic fibroinflammatory condition characterized by organomegaly or tumefactive lesions associated with lymphoplasmacytic infiltration rich in IgG4 plasma cells. We report a case of IgG4-related disease involving the subcutaneous layer of the left upper arm in a 48-year-old female presenting with an unusual soft tissue mass. US and MRI showed an irregular infiltrative soft tissue mass, indicating possible malignancy or inflammation. We discuss the diagnostic criteria, histopathologic features, radiological features, and treatment of IgG4-related disease.

IgG4 related disease and aortitis: an up-to-date review

Aortic involvement in immunoglobulin G4-related disease (IgG4-RD) is extremely rare and is often overlooked during the aortitis work-up. IgG4-related aortitis differs from non-IgG4-related aortitis in its histopathological features, site of involvement, laboratory markers, and treatment options. The histopathological examination of the vessel walls characteristically reveals adventitial thickening with intimal sparing, typically affecting the infrarenal abdominal aorta. In addition, inadequate knowledge about the disease often leads to delayed or missed diagnosis and undermanagement of a potentially treatable condition. Hence, in this paper, we review the unique clinical manifestations, laboratory markers, diagnostic features, current treatment strategies, and novel experimental therapeutic options in the management of IgG4-related aortitis.

Bibliometric analysis of IgG4-related disease research from 2003 to 2022 based on Web of Science Core Collection Databases

This study aimed to perform a bibliometric analysis of the IgG4-related disease (IgG4-RD) research field over the past 20 years to explore its research hotspots and trends. The literature of IgG4-RD published in the Web of Science Core Collection databases was reviewed from January 1, 2003, to April 30, 2022. A bibliometric analysis was carried out using CiteSpace software to evaluate and visualize the evolving dynamics and hotspots in the field of IgG4-RD. A total of 3174 IgG4-RD articles were reviewed. Since 2011, there has been a rapid increase in published literature. Japan is the highest yielding country and Kanazawa University the highest yielding institution. The USA has the highest centrality (0.34) and plays a critical role in cooperation and communication of IgG4-RD research. Nine highly connected clusters of IgG4-RD were observed by keyword analysis. Research hotspots included IgG4-RD involved organs and differentiation from Rosai-Dorfman disease and primary sclerosing cholangitis. Further research topics include pathogenesis, relapse, and malignancy. As a cross-discipline systemic disease, IgG4-RD requires attention by clinicians in multiple fields. This bibliometric analysis can help researchers grasp trends and provide new perspectives for future research on IgG4-RD.

The unique diagnostic and management challenge of a patient with concomitant anti-interferon-gamma autoantibody associated immunodeficiency syndrome, IgG4-related disease, and treatment refractory, disseminated mycobacterium avium complex infection

BACKGROUND

Anti-interferon-gamma autoantibody-associated immunodeficiency syndrome is a rare and underrecognized adult onset immunodeficiency syndrome associated with severe opportunistic infections such as disseminated nontuberculous mycobacterium. Few cases have documented a relationship with IgG4-related disease. Concomitant diagnoses of these diseases present a diagnostic and management challenge.

CASE PRESENTATION

A 61 year old man of Southeast Asian descent with pulmonary mycobacterium avium complex infection presented to our hospital system with a new skin rash and worsening lymphadenopathy. He was eventually diagnosed with IgG4-related disease through excisional nodal biopsy. He was managed with immunosuppressive treatment with prednisone, rituximab and cyclophosphamide. He later re-presented with disseminated mycobacterium avium complex infiltration of his joints, bones and prostate. Original titers of anti-interferon-gamma autoantibodies were falsely negative due to being on immunosuppressive therapy for his IgG4-related disease. However, anti-interferon-gamma autoantibody titers were re-sent after immunosuppression was held and returned strongly positive.

CONCLUSIONS

This case reviews diagnostic criteria and discusses management strategies with existing challenges in treating a patient with concomitant adult onset immunodeficiency syndrome, IgG4-related disease and a disseminated mycobacterial avium complex infection.

Overview of autoimmune liver disease: Prevalence, risk factors, and role of autoantibodies

Content available: Author Interview and Audio Recording.

Recent advances in clinical practice: epidemiology of autoimmune liver diseases

Autoimmune liver diseases are chronic inflammatory hepatobiliary disorders that when classically defined encompass three distinctive clinical presentations; primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and autoimmune hepatitis (AIH). Meaningful changes in disease epidemiology are reported, with increasing incidence and prevalence of AIH and PSC in Europe, and rising prevalence of PBC across Europe, North America and the Asia-Pacific region. However, there appears to be very significant global variation with contemporary incidence rates of disease per 100 000 ranging from 0.84 to 2.75 for PBC, 0.1 to 4.39 for PSC and 0.4 to 2.39 for AIH. Prevalence corresponds, and per 100 000 estimates for PBC range from 1.91 to 40.2, for PSC between 0.78 and 31.7 and for AIH from 4.8 to 42.9. Population-based studies and multicentre observational cohort series provide improved understanding of the clinical course that patients experience, highlighting variations in presenting phenotypes geographically and temporally. Collectively, while autoimmune liver diseases are rare, the clinical burden is disproportionately high relative to population incidence and prevalence. Age, sex and race also impact clinical outcomes, and patient morbidity and mortality are reflected by high need for gastroenterology, hepatology and organ transplant services.

IgG4-Related Disease With Renal and Pulmonary Involvement

Immunoglobulin G4-related disease (IgG4-RD) is a rare immune-mediated disease affecting multiple organs and tissues. There is often the presence of elevated serum Ig4 subtype with histological evidence of lymphoplasmacytic infiltration, fibrosis, and phlebitis. The mainstay of treatment is steroids therapy. We report the case of a 66-year-old man presenting with acute on chronic renal failure and pulmonary nodules seen on PET-CT scan. He also had elevated serum IgG4 subclass and histological features in keeping with IgG4-RD. He failed steroid therapy but responded subsequently to rituximab with complete resolution of his symptoms.

Immunoglobulin G4 (IgG4)-related autoimmune hepatitis and IgG4-hepatopathy: A histopathological and clinical perspective

Immunoglobulin G4 (IgG4)-related disease (IgG4-RD) is a chronic inflammatory disease that simultaneously or consecutively involves multiple organs of the body. It is characterized by elevated serum IgG4 levels and massive infiltration of IgG4⁺ plasma cells in the damaged tissues. IgG4-related autoimmune hepatitis (IgG4-AIH) and IgG4-hepatopathy are relatively new entities that have been proposed as a phenotype of IgG4-RD in the liver. Immunoglobulin G4-AIH is defined as a disorder with serological, histopathological, and clinical features of both IgG4-RD and AIH, simultaneously satisfying the diagnostic criteria of both classical AIH and IgG4-RD. Although there are several case reports and studies of IgG4-AIH among the published works, no consensus regarding the histopathological characteristics of IgG4-AIH has been established, and its clinical implications remain obscure. Immunoglobulin G4-hepatopathy is defined as a comorbidity of IgG4-RD in the liver, and patients not meeting the diagnostic criteria of classical AIH could be diagnosed with IgG4-hepatopathy. Numerous issues regarding these diseases, especially their epidemiology, histopathological and clinical characteristics, and treatment response to corticosteroids, remain unsolved, and need to be determined to establish the disease concepts of IgG4-AIH and IgG4-hepathopathy.