ABSTRACTIgG4 related disease was recognized as a unified disease entity only 15 years ago. Awareness of IgG4 related disease has increased worldwide since then, and specialists are now familiar with ...most of its clinical manifestations. Involvement of the pancreato-biliary tract, retroperitoneum/aorta, head and neck, and salivary glands are the most frequently observed disease phenotypes, differing in epidemiological features, serological findings, and prognostic outcomes. In view of this multifaceted presentation, IgG4 related disease represents a great mimicker of many neoplastic, inflammatory, and infectious conditions. Histopathology remains key to diagnosis because reliable biomarkers are lacking. Recently released classification criteria will be invaluable in improving early recognition of the disease. IgG4 related disease is highly treatable and responds promptly to glucocorticoids, but it can lead to end stage organ failure and even death if unrecognized. Prolonged courses of corticosteroids are often needed to maintain remission because the disease relapses in most patients. Rapid advancement in our understanding of the pathophysiology of IgG4 related disease is leading to the identification of novel therapeutic targets and possible personalized approaches to treatment.
IgG4-related disease (IgG4-RD) can cause fibroinflammatory lesions in nearly any organ. Correlation among clinical, serological, radiological and pathological data is required for diagnosis. This ...work was undertaken to develop and validate an international set of classification criteria for IgG4-RD. An international multispecialty group of 86 physicians was assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). Investigators used consensus exercises; existing literature; derivation and validation cohorts of 1879 subjects (1086 cases, 793 mimickers); and multicriterion decision analysis to identify, weight and test potential classification criteria. Two independent validation cohorts were included. A three-step classification process was developed. First, it must be demonstrated that a potential IgG4-RD case has involvement of at least one of 11 possible organs in a manner consistent with IgG4-RD. Second, exclusion criteria consisting of a total of 32 clinical, serological, radiological and pathological items must be applied; the presence of any of these criteria eliminates the patient from IgG4-RD classification. Third, eight weighted inclusion criteria domains, addressing clinical findings, serological results, radiological assessments and pathological interpretations, are applied. In the first validation cohort, a threshold of 20 points had a specificity of 99.2% (95% CI 97.2% to 99.8%) and a sensitivity of 85.5% (95% CI 81.9% to 88.5%). In the second, the specificity was 97.8% (95% CI 93.7% to 99.2%) and the sensitivity was 82.0% (95% CI 77.0% to 86.1%). The criteria were shown to have robust test characteristics over a wide range of thresholds. ACR/EULAR classification criteria for IgG4-RD have been developed and validated in a large cohort of patients. These criteria demonstrate excellent test performance and should contribute substantially to future clinical, epidemiological and basic science investigations.
Objective
IgG4‐related disease (IgG4‐RD) can cause fibroinflammatory lesions in nearly any organ. Correlation among clinical, serologic, radiologic, and pathologic data is required for diagnosis. ...This work was undertaken to develop and validate an international set of classification criteria for IgG4‐RD.
Methods
An international multispecialty group of 86 physicians was assembled by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). Investigators used consensus exercises, existing literature, derivation and validation cohorts of 1,879 subjects (1,086 cases, 793 mimickers), and multicriterion decision analysis to identify, weight, and test potential classification criteria. Two independent validation cohorts were included.
Results
A 3‐step classification process was developed. First, it must be demonstrated that a potential IgG4‐RD case has involvement of at least 1 of 11 possible organs in a manner consistent with IgG4‐RD. Second, exclusion criteria consisting of a total of 32 clinical, serologic, radiologic, and pathologic items must be applied; the presence of any of these criteria eliminates the patient from IgG4‐RD classification. Third, 8 weighted inclusion criteria domains, addressing clinical findings, serologic results, radiology assessments, and pathology interpretations, are applied. In the first validation cohort, a threshold of 20 points had a specificity of 99.2% (95% confidence interval 95% CI 97.2–99.8%) and a sensitivity of 85.5% (95% CI 81.9–88.5%). In the second, the specificity was 97.8% (95% CI 93.7–99.2%) and the sensitivity was 82.0% (95% CI 77.0–86.1%). The criteria were shown to have robust test characteristics over a wide range of thresholds.
Conclusion
ACR/EULAR classification criteria for IgG4‐RD have been developed and validated in a large cohort of patients. These criteria demonstrate excellent test performance and should contribute substantially to future clinical, epidemiologic, and basic science investigations.
Abstract
Introduction
Four clinical phenotypes of IgG4-related disease (IgG4-RD) have been recently identified by latent class analysis (LCA): pancreato-biliary (group 1); retroperitoneum/aortitis ...(group 2); head and neck limited (group 3); and Mikulicz/systemic (group 4). The reproducibility of this classification in clinical practice and its relevance for patient management, however, remain unknown.
Methods
The study included 179 patients. Four IgG4-RD experts were asked to classify a validation cohort of 40 patients according to published LCA-derived phenotypes based on clinical judgement. Agreement between LCA and clinical clustering was calculated. To assess differences among disease phenotypes, the following variables were recorded on an additional 139 patients: serum IgG4 and IgE; inflammatory markers; eosinophils; plasmablasts; IgG4-RD responder index (RI); history of atopy, diabetes, osteoporosis, relapses and malignancy; cumulative dose of glucocorticoids; and use of rituximab.
Results
Clinical judgement replicated LCA classification with strong agreement among IgG4-RD experts (κ = 0.841, P < 0.0005). At disease onset, group 1 showed the highest levels of serum IgG4 and IgE. Groups 2 and 4 had the lowest and highest IgG4-RD RI, respectively. At 2 years’ follow-up, group 3 received the highest cumulative dose of glucocorticoids, but higher incidences of diabetes mellitus were observed in groups 1 and 4, consistent with the higher likelihood of pancreatic involvement in groups 1 and 4. No difference among the four groups was observed in terms of disease recurrence, time to relapse and frequency of rituximab infusion.
Conclusion
Clinical phenotypes of IgG4-RD reflect differences in epidemiological features and prognostic outcomes.
Objective
IgG4‐related disease (IgG4‐RD) can cause fibroinflammatory lesions in nearly any organ, leading to organ dysfunction and failure. The IgG4‐RD Responder Index (RI) was developed to help ...investigators assess the efficacy of treatment in a structured manner. The aim of this study was to validate the RI in a multinational investigation.
Methods
The RI guides investigators through assessments of disease activity and damage in 25 domains, incorporating higher weights for disease manifestations that require urgent treatment or that worsen despite treatment. After a training exercise, investigators reviewed 12 written IgG4‐RD vignettes based on real patients. Investigators calculated both an RI score as well as a physician's global assessment (PhGA) score for each vignette. In a longitudinal assessment, 3 investigators used the RI in 15 patients with newly active disease who were followed up over serial visits after treatment. We assessed interrater and intrarater reliability, precision, validity, and responsiveness.
Results
The 26 physician investigators included representatives from 6 specialties and 9 countries. The interrater and intrarater reliability of the RI was strong (0.89 and 0.69, respectively). Correlations (construct validity) between the RI and PhGA were high (Spearman's r = 0.9, P < 0.0001). The RI was sensitive to change (discriminant validity). Following treatment, there was significant improvement in the RI score (mean change 10.5 95% confidence interval (95% CI) 5.4–12, P < 0.001), which correlated with the change in the PhGA. Urgent disease and damage were captured effectively.
Discussion
In this international, multispecialty study, we observed that the RI is a valid and reliable disease activity assessment tool that can be used to measure response to therapy.
Immunoglobulin G4-related disease (IgG4-RD) promptly responds to glucocorticoids but relapses in a considerable fraction of patients. Reliable biomarkers of flare are currently lacking because the ...pathophysiology of IgG4-RD remains largely elusive. In the present work, we aimed to identify perturbations of B-cell subpopulations that might predict IgG4-RD relapse.
Thirty patients were treated with glucocorticoids according to international guidelines. Circulating CD19
and CD20
cells, naive B cells, memory B cells, plasmablasts, and plasma cells were measured by flow cytometry at baseline and every 6 months for 2 years after the initiation of corticosteroid therapy.
Patients with active untreated IgG4-RD showed significantly reduced CD19
B cells, CD20
B cells, and naive B cells compared with healthy subjects (p < 0.05), but significantly expanded plasmablasts and plasma cells (p < 0.01). After 6 months of corticosteroid treatment, all patients achieved clinical improvement. Naive B cells, plasmablasts, and plasma cells significantly decreased compared with disease onset, whereas memory B cells significantly increased compared with baseline (p < 0.01). Increase of memory B cells was observed only in patients who relapsed within 2 years of follow-up, however (HR, 12.24; 2.99 to 50.2; p = 0.0005). In these patients, the relapse rates at 12 and 24 months were 30% and 100%, respectively. No abnormalities of other B-cell subpopulations at disease onset or after 6 months of glucocorticoid treatment were found to predict IgG4-RD relapse at 2 years.
Increase of circulating memory B cells after 6 months of glucocorticoid treatment might predict IgG4-RD relapse.
High serum IgG4 concentrations are a striking feature of many patients with IgG4-related disease (IgG4-RD). Blood levels of IgG4 often reach ten, twenty, and even thirty or more times higher than the ...upper limit of normal. Under the proper clinical circumstances, the finding of an elevated serum IgG4 concentration serves as a useful biomarker for the diagnosis of this condition. This serum IgG4 elevation quickly called attention to the possibility of therapies targeting cells of the B lymphocyte lineage. In addition, a greater understanding of the cellular mechanisms that underpin IgG4-RD has identified peripheral blood plasmablasts as a promising biomarker for this disease. The roles of plasmablasts and B cells in IgG4-RD are discussed in this chapter.
IgG4-related disease (IgG4-RD) is an increasingly recognized immune-mediated fibroinflammatory disorder that promptly responds to glucocorticoids but commonly relapses during steroid tapering or ...after discontinuation. In the last few years, B-cell depletion therapy with rituximab (RTX) proved to be effective in the induction of remission and maintenance treatment of IgG4-RD, providing a new powerful tool in the management of this emerging condition. In this review, we outline the pathogenetic rationale for using B-cell depleting agents in IgG4-RD, we summarize available clinical experience with RTX in this disease, and we describe future possible therapies targeting B-lymphocytes that are now in the pipeline.
Abstract
Objectives
IgG4-related disease (IgG4-RD) is a systemic fibro-inflammatory disorder characterized by a dysregulated resolution of inflammation and wound healing response that might develop ...after an apoptotic insult induced by cytotoxic T lymphocytes (CTLs). Mer receptor tyrosine kinase (MerTK) and its ligand, protein S (ProS1), have a pivotal role in the resolution of inflammation, being implicated in the clearance of apoptotic cells, quenching of the immune response and development of tissue fibrosis. In the present work we aimed to investigate a possible involvement of the MerTK signalling pathway in the pathogenesis of IgG4-RD and development of tissue fibrosis.
Methods
MerTK and ProS1 expression patterns in IgG4-RD lesions were evaluated by immunohistochemistry and immunofluorescence studies. Circulating MerTK+ monocytes, soluble Mer and MerTK ligands were measured in the peripheral blood of IgG4-RD patients and healthy controls by flow cytometry and ELISA, respectively.
Results
MerTK was highly expressed by macrophages infiltrating IgG4-RD lesions. MerTK+ macrophages were more abundant in IgG4-RD than in Sjögren’s syndrome and interacted with apoptotic cells and ProS1-expressing T and B lymphocytes. Moreover, they expressed the pro-fibrotic cytokine TGF-β and their numbers declined following rituximab-induced disease remission. Circulating MerTK+ monocytes, soluble Mer and MerTK ligands were not increased in the peripheral blood of patients with IgG4-RD.
Conclusions
The MerTK–ProS1 axis is activated in IgG4-RD lesions, possibly leading to persistent stimulation of processes involved in the resolution of inflammation and tissue fibrosis.
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