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

Nivolumab Therapy in Lung Cancer Associated with IgG4-related Disease

A 75-year-old man with severe bilateral pleural thickening and dense soft tissue masses surrounding the abdominal aorta on computed tomography was diagnosed with IgG4-related disease (IgG4-RD) as a complication of lung cancer. He was started on nivolumab as second-line therapy along with low-dose prednisolone. Nivolumab was administered for 15 months until disease progression, during which time IgG4-RD did not relapse, and no problematic immune-related adverse events occurred. These results suggest that anti-programmed cell death protein-1 antibody may be used safely in lung cancer associated with IgG4-RD concomitantly with low-dose steroids.

A Review on The Role of Environmental Exposures in IgG4-Related Diseases

PURPOSE OF REVIEW

Immunoglobulin G4-related diseases (IgG4-RDs) are immune-mediated fibroinflammatory multisystemic conditions identified by the presence of tumefactive lesions with a rich infiltrate of IgG4-positive plasma cells, and often by a high IgG4 serum concentration. IgG-RDs have a prevalence of at least 1 case every 100,000 persons, and they are mostly diagnosed after age 50, with a male to female ratio of about 3:1. IgG4-RD pathophysiology is still uncertain: it has been proposed that both genetic predisposition and chronic environmental exposures may play a role by triggering abnormal immune activation that perpetuates the disease. The purpose of this review is to summarize the evidences supporting the hypothesis that certain environmental/occupational exposures can trigger IgG4-RDs, focusing on the possible role of asbestos in an emerging IgG4-RD called idiopathic retroperitoneal fibrosis (IRF).

RECENT FINDINGS

Although some studies suggested a relationship between tobacco smoking and IgG4-RD risk, occupational exposures seem to have the most interesting effects. Positive history of blue-collar work increases the risk of developing an IgG4-RD, and mineral dusts and asbestos were the most strongly associated industrial compounds. Asbestos has been found to be a risk factor for IRF years before its classification as IgG4-RD, and later in two large case-control studies. In the most recent one, conducted on 90 patients and 270 controls, asbestos exposure conferred an increased IRF risk, quantified by odds ratios from 2.46 to 7.07. Further structured studies including serum IgG4 evaluation should be conducted to clarify the effect of asbestos on patients with confirmed diagnosis of IgG4-related IRF. Environmental exposures, especially of occupational origin, appear to play a role in the development of different types of IgG-RDs. In particular, although first suggested very recently, the relationship between asbestos and IRF deserves to be explored in more structured studies, especially because of the biological plausibility of the role of asbestos in IRF pathogenesis.

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.

Characteristic cerebrospinal fluid findings in immune checkpoint inhibitor-related peripheral neuropathy: A case report

Although immune checkpoint inhibitors (ICIs) are widely used to treat unresectable malignant tumors, they can cause undesirable side effects called immune-related adverse events, including neurological toxicities. Here, we describe a case of ICI-related peripheral neuropathy (irPN) with characteristic cerebrospinal fluid (CSF) findings. In addition to pleocytosis and increased protein levels, the present case showed increased levels of CSF soluble interleukin-2 receptor (sIL-2R), IL-6, and IL-10, suggesting activated T cell-related autoimmunity. We believe that CSF cytokines and sIL-2R could be novel biomarkers of irPN.

IgG4-related brain pseudotumor mimicking CNS lymphoma. A case report

Here, we report a case of IgG4-related brain pseudotumor (IgG4-BP) in a 39-year-old woman, mimicking central nervous system (CNS) lymphoma. She presented with headache, fever, and fatigue. Her medical history was notable for appearance of a tumefactive brain lesion seven years before. Brain biopsy performed at the age of 32 revealed nonspecific inflammatory changes, and her condition improved with oral low-dose steroid therapy. Magnetic resonance imaging performed at the age of 39 identified a hyperintensity lesion with edema located at the medial temporal lobe region adjacent to the inferior horn of the left lateral ventricle on fluid-attenuated inversion recovery images, which showed gadolinium-contrast enhancement on T1-weighted images and a slightly hyperintensity signal on diffusion-weighted images. Methionine-positron emission tomography (PET) depicted a high methionine uptake in the lesion. Additionally, soluble levels of interleukin (IL)-2 receptor (sIL-2R) and IL-10 were increased in cerebrospinal fluid (CSF). Based on these findings, we suspected CNS lymphoma and performed partial resection of the brain lesion. Pathological examination revealed prominent lymphocytic infiltration associated with plasma cell infiltration. Most of the plasma cells were immunoreactive for IgG4. Storiform fibrosis and partially obliterative phlebitis were concomitantly observed. Thus, the patient was diagnosed as having IgG4-BP. To the best of our knowledge, this is the first case report of IgG4-BP with detailed findings obtained by CSF testing, methionine-PET, and pathological examination. Because IgG4-related diseases can present as a pseudotumor that mimics CNS lymphoma, it is essential to carefully differentiate IgG4-BP from CNS lymphoma.

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.

Human epididymis protein 4 (HE4) is a novel biomarker for fibrosis in IgG4-related disease and can predict poor prognosis

Objectives

IgG4-related disease (IgG4-RD) is an immune-mediated fibroinflammatory disorder with heterogeneous manifestations. This study aimed to investigate the utility of human epididymis protein 4 (HE4) as a potential clinical biomarker of fibrosis in IgG4-RD.

Methods

Plasma HE4 levels were estimated in 136 patients with IgG4-RD and 73 healthy individuals (controls) by electrochemical luminescence. HE4 expression levels and the degree of fibrosis in pancreatic tissues from 15 patients with IgG4-RD and 10 controls were compared using immunohistochemistry and Masson trichrome staining. Correlation between HE4 levels and laboratory parameters was determined, and the efficacy of HE4 as a biomarker of fibrosis and prognosis in IgG4-RD was also evaluated.

Results

Plasma HE4 levels were significantly higher in patients with IgG4-RD compared with controls. Optimal HE4 cut-off value for identifying patients with IgG4-RD was determined to be 50.8 pmol/L with an AUC (area under curve) of 0.791. HE4 levels were positively correlated with diverse laboratory parameters, and indicators of organ function impairment. Additionally, HE4 was highly expressed in the affected organs in patients with IgG4-RD and its plasma levels were closely correlated with degree of fibrosis, indicating the utility of HE4 in assessing internal organ damage and fibrosis. Further analysis showed that patients in the HE4 high expression group had poor prognosis.

Conclusions

Our results demonstrate that HE4 can be used as a biomarker for IgG4-RD as it is correlated with diverse baseline clinical features, internal organ damage and degree of fibrosis in affected organs, and can predict poor prognosis.

IgG4-Related Disease With Gastrointestinal Involvement: Case Reports and Literature Review

IgG4-related disease is an immune-mediated chronic, systemic, and autoinflammatory disease that can affect various organs throughout the body. The most commonly affected areas are the pancreas and biliary system. Due to the diverse clinical manifestations of the disease, it affects widely distributed organs. Thus, it is often easy to misdiagnose or miss. The digestive tract is a rarely affected system, and most IgG4-related gastric diseases manifest as tumors detected by endoscopy. This article reports two special cases with IgG4-related disease involving atrophic gastritis and intestinal polyps to provide a more empirical and theoretical basis for clinical diagnosis and treatment.

Orchestration of Immune Cells Contributes to Fibrosis in IgG4-Related Disease

This review summarizes recent progress in understanding the pathogenesis of IgG4-related disease (IgG4-RD), with a focus on fibrosis. Several studies reported that CD4+ T cells with cytotoxic activity promoted by the secretion of granzyme and perforin, cytotoxic CD4+ T cells (CD4+CTLs), and disease-specific activated B cells, infiltrated inflamed tissues and cooperated to induce tissue fibrosis in autoimmune fibrotic diseases such as IgG4-RD, systemic sclerosis, and fibrosing mediastinitis. An accumulation of cells undergoing apoptotic cell death induced by CD4+CTLs and CD8+CTLs followed by macrophage-mediated clearing and finally tissue remodeling driven by cytokines released by CD4+CTLs, activated B cells, and M2 macrophages may contribute to the activation of fibroblasts and collagen production. In IgG4-RD, this process likely involves the apoptosis of non-immune, non-endothelial cells of mesenchymal origin and subsequent tissue remodeling. In summary, CD4+CTLs infiltrate affected tissues where they may cooperate with activated B cells, CD8+CTLs, and M2 macrophages, to induce apoptosis by secreting cytotoxic cytokines. These immune cells also drive fibrosis by secreting pro-fibrotic molecules in IgG4-RD.

Fevers, Sweats, Weight Loss, Oh My! When IgG4 Related Disease Comes Knocking. .

Immunoglobulin G4-related systemic disease (IgG4-RSD) is a fibro-inflammatory immune condition characterized by IgG4 positive plasma cells, fibrosis, and frequently elevated serum IgG4 level. Akin to sarcoidosis, IgG4-RSD is a systemic disease with diverse organ manifestations linked by common histopathologic features. IgG4-RSD typically presents sub acutely without significant constitutional symptoms or fever. Hepatic Inflammatory pseudotumor (HIP) is a rare manifestation of IgG4-RSD composed of dense lymphoplasmacytic infiltrate and extensive fibrosis. We present an older Asian male who presented with acute onset of fever and weight loss found to have IgG4-RSD complicated by a HIP and concomitant MSSA abscess.

Significance of high serum IgG4 in complete or non-full-fledged IgG4-related disease-a retrospective investigation of 845 patients and its clinical relevance

OBJECTIVE

Immunoglobulin G4-related disease (IgG4-RD) is a recently recognized heterogeneous, subacute, and usually silent autoimmune disease involving many organs with protean manifestations. However, high IgG4 in serum is not necessarily indicating an IgG4-RD. The aims of this study were to investigate the clinical relevance of high serum IgG4 level in IgG4-RD or non IgG4-RD patients, and to see if IgG4-RD in Taiwan differs from that in other parts of the world.

METHODS

Eight hundred forty-five patients with high IgG4 were retrospectively reviewed from January 2002 to May 2020 in Taipei Veteran General Hospital. Two hundred sixty-seven patients fulfilled IgG4-RD criteria and were categorized into pancreato-hepato-biliary disease, retroperitoneal fibrosis and/or aortitis, head/neck-limited disease, classic Mikulicz syndrome with systemic involvement, CNS-limited disease, sclerosing vasculitis, skin-limited disease, and sensorineural hearing disease. These manifestations were correlated to smoking, atopy, hyper-IgE/eosinophilia, aging, malignancies, and hypocomplementemia. Five hundred seventy-eight patients were not fulfilling the criteria but were also analyzed for the prevalence of allergy, malignancy, connective tissue diseases, lung diseases, and infections.

RESULTS

In IgG4-RD patients, 124 (46.4%) smoked. Top 4 clinical subtypes included Mikulicz syndrome with systemic involvement (33.3%), pancreato-hepatobiliary disease (31.4%), head/neck disease (19.4%), and retroperitoneal fibrosis/aortitis (12.7%). Top 4 co-morbid conditions included high serum IgE/eosinophilia (46.2%), hypocomplementemia (34%), malignancies (13.4%), and allergy (13.4%). Pancreato-biliary disease was associated with high IgE/eosinophilia (r² = 0.380, P = 0.025) and malignancy (r² = 0.211, P = 0.027), Miculicz syndrome with allergy (r² = 0.396, P < 0.01) and high IgE/eosinophil (r² = 0.396, P < 0.01), CNS diseases (r² = 0.973, P = 0.035) and sclerosing vasculitis (r² = 1, P < 0.01) with advanced age respectively, with the latter being also related to atopy and high IgE/eosinophilia (r² = 1, p < 0.01).

CONCLUSION

Smoking may precipitate IgG4-RD. IgG4-RD with pancreato-hepatobiliary disease is closely related to allergy and neoplasm, and those with Mikulicz syndrome may result from atopy. Elderly IgG4-RD patients tend to develop CNS pathology parallel to advancing of age. The disease may probably be originated from an unknown mechanism that may sporadically evolve into malignancies.

Pericarditis as a manifestation of IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic, immune-mediated fibro-inflammatory disease that can affect virtually every organ system. It is usually insidious in onset and often mimics malignant or other inflammatory disorders. Diagnosis frequently requires a combination of clinical, serological, radiographic, and histopathological features, including increased serum-IgG4 levels and tissue infiltration of IgG4-positive plasma cells with associated fibrosis. Unlike more frequently affected sites, including the hepatobiliary system, salivary glands and retroperitoneum, pericardial involvement of IgG4-RD has only rarely been described. We report the case of a 76-year-old woman presenting with refractory pericarditis and imminent cardiac tamponade, successfully treated with therapeutic pericardiectomy. A diagnosis of IgG4-RD was made based on elevated serum-IgG4 levels and the presence of typical pericardial histopathological findings, meeting all 3 of the 2011 comprehensive diagnostic criteria for IgG4-RD. Following pericardiectomy, the patient remained in remission without a need for glucocorticoids or additional immunosuppressive therapy. Adding to this case, we reviewed the literature for previously described cases of IgG4-RD presenting with pericarditis and described their characteristics and the available treatment options. Our case-based literature review provides a clear overview of the diagnostic process for IgG4-RD and the need to apply classification criteria with the necessary caution, particularly in the case of rare disease manifestations, including pericarditis.

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

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