Background IgG4 -related disease (IgG4 -RD) is a poorly understood, multiorgan, chronic inflammatory disease characterized by tumefactive lesions, storiform fibrosis, obliterative phlebitis, and ...accumulation of IgG4 -expressing plasma cells at disease sites. Objective The role of B cells and IgG4 antibodies in IgG4 -RD pathogenesis is not well defined. We evaluated patients with IgG4 -RD for activated B cells in both disease lesions and peripheral blood and investigated their role in disease pathogenesis. Methods B-cell populations from the peripheral blood of 84 patients with active IgG4 -RD were analyzed by using flow cytometry. The repertoire of B-cell populations was analyzed in a subset of patients by using next-generation sequencing. Fourteen of these patients were longitudinally followed for 9 to 15 months after rituximab therapy. Results Numbers of CD19+ CD27+ CD20− CD38hi plasmablasts, which are largely IgG4+ , are increased in patients with active IgG4 -RD. These expanded plasmablasts are oligoclonal and exhibit extensive somatic hypermutation, and their numbers decrease after rituximab-mediated B-cell depletion therapy; this loss correlates with disease remission. A subset of patients relapse after rituximab therapy, and circulating plasmablasts that re-emerge in these subjects are clonally distinct and exhibit enhanced somatic hypermutation. Cloning and expression of immunoglobulin heavy and light chain genes from expanded plasmablasts at the peak of disease reveals that disease-associated IgG4 antibodies are self-reactive. Conclusions Clonally expanded CD19+ CD27+ CD20− CD38hi plasmablasts are a hallmark of active IgG4 -RD. Enhanced somatic mutation in activated B cells and plasmablasts and emergence of distinct plasmablast clones on relapse indicate that the disease pathogenesis is linked to de novo recruitment of naive B cells into T cell–dependent responses by CD4+ T cells, likely driving a self-reactive disease process.
Immunoglobulin G4‐related disease (IgG4‐RD) is an uncommon disorder that demonstrates characteristic clinicopathologic features including sclerosing lesions with storiform fibrosis, increased IgG4+ ...plasma cells with an increased IgG4+/IgG+ plasma cell ratio, obliterative phlebitis, and often an increased serum IgG4 level. This review summarizes the characteristic histopathologic and clinical features of IgG4‐RD with detailed discussion of the histopathologic characteristics of the most commonly involved anatomic sites. We also present recent advances in our understanding of the pathophysiologic mechanisms of IgG4‐RD and discuss updates on the treatment, prognosis, and outcomes of this rare disease, including discussion of the possible association between IgG4‐RD and malignancy.
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.
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.
We examined the utility of circulating total and IgG4+ plasmablasts as biomarkers of diagnosis and disease activity in IgG4-related disease (IgG4-RD).
We evaluated patients with active, untreated, ...biopsy-proven IgG4-RD affecting various organs. Flow cytometry was used to measure total plasmablast and IgG4+ plasmablast counts by gating peripheral blood for CD19lowCD38+CD20-CD27+ cells and CD19lowCD38+CD20-CD27+IgG4+ cells. Serum IgG4 concentrations were measured by nephelometry. We compared 37 IgG4-RD patients to 35 controls, including healthy individuals (n=14) and patients with other inflammatory diseases before treatment (n=21).
The IgG4-RD patients' mean age was 59, and 68% were male. Fourteen patients (38%) had three or more organs involved. The IgG4-RD patients had substantially elevated total plasmablast counts (median 4698/mL, range 610-79524/mL) compared to both untreated disease controls (median 592/mL, range 19-4294/mL; p < 0.001) and healthy controls (median 94/mL, range 1-653/mL; p < 0.001). Thirteen IgG4-RD patients (36%) had normal serum IgG4 concentrations (mean 60 mg/dL, range 5-123 mg/dL, normal <135 mg/dL). However, the median plasmablast count was not significantly lower in that subset with normal serum IgG4 concentrations (3784/mL) compared to those with elevated serum IgG4 (5155/mL) (p = 0.242). Among the 12 rituximab (RTX)-treated patients, the median plasmablast level during disease flare was 6356/mL (range 1123-41589/mL), declining to 1419/mL (range 386/mL-4150/mL) during remission (p < 0.01).
Circulating plasmablasts are elevated in active IgG4-RD, even in patients with normal serum IgG4 concentrations. Plasmablast counts are a potentially useful biomarker for diagnosis, assessing response to treatment, and determining the appropriate time for re-treatment.
Objective
An unconventional population of CD4+ signaling lymphocytic activation molecule family member 7–positive (SLAMF7+) cytotoxic effector memory T (TEM) cells (CD4+ cytotoxic T lymphocytes CTLs) ...has been linked causally to IgG4‐related disease (IgG4‐RD). Glucocorticoids represent the first‐line therapeutic approach in patients with IgG4‐RD, but their mechanism of action in this specific condition remains unknown. We undertook this study to determine the impact of glucocorticoids on CD4+ CTLs in IgG4‐RD.
Methods
Expression of CD8α, granzyme A, perforin, and SLAMF7 within the effector memory compartment of CD45RO+ (TEM) and CD45RA+ effector memory T (TEMRA) CD4+ cells was quantified by flow cytometry in 18 patients with active IgG4‐RD, both at baseline and after 6 months of glucocorticoid treatment. Eighteen healthy subjects were studied as controls. Next‐generation sequencing of the T cell receptor α‐ and β‐chain gene was performed on circulating CD4+ CTLs from patients with IgG4‐RD before and after treatment and in affected tissues.
Results
Circulating CD4+ TEM and TEMRA cells were not expanded in IgG4‐RD patients compared to healthy controls. CD4+SLAMF7+ TEM cells (but not TEMRA cells) were significantly increased among IgG4‐RD patients. Within CD4+SLAMF7+ TEM cells, CD8α− cells but not CD8αlow cells were elevated in IgG4‐RD patients. The same dominant clones of CD8α−CD4+SLAMF7+ TEM cells found in peripheral blood were also identified in affected tissue. CD8α− and CD8αlowCD4+SLAMF7+ TEM cells both expressed cytolytic molecules. Clonally expanded CD8α− but not CD8αlowCD4+SLAMF7+ TEM cells decreased following glucocorticoid‐induced disease remission.
Conclusion
A subset of CD8α−CD4+SLAMF7+ cytotoxic TEM cells is oligoclonally expanded in patients with active IgG4‐RD. This TEM cell population contracts following glucocorticoid‐induced remission. Further characterization of this cell population may provide prognostic information and targets for therapeutic intervention.
•This is the first study comparing tocilizumab to standard of care in severe COVID-19•Tocilizumab in severe COVID-19 patients did influence 28-day clinical outcomes•Tocilizumab safety was ...satisfactory except for ICU-admitted patients
Tocilizumab (TCZ), a humanized monoclonal antibody targeting the interleukin-6 (IL-6) receptor, has been proposed for the treatment of COVID-19 patients; however, limited data are available on the safety and efficacy.
We performed a retrospective study on severe COVID-19 patients with hyper-inflammatory features admitted outside intensive care units (ICUs). Patients treated with intravenous TCZ in addition to standard of care were compared to patients treated with standard of care alone. Safety and efficacy were assessed over a 28-day follow-up.
65 patients were included. Among them, 32 were treated with TCZ. At baseline, all patients were on high-flow supplemental oxygen and most (78% of TCZ patients and 61% of standard treatment patients) were on non-invasive ventilation. During the 28-day follow-up, 69% of TCZ patients experienced a clinical improvement compared to 61% of standard treatment patients (p = 0.61). Mortality was 15% in the tocilizumab group and 33% in standard treatment group (p = 0.15). In TCZ group, at multivariate analysis, older age was a predictor of death, whereas higher baseline PaO2:FiO2 was a predictor of clinical improvement at day 28. The rate of infection and pulmonary thrombosis was similar between the two groups.
At day 28, clinical improvement and mortality were not statistically different between tocilizumab and standard treatment patients in our cohort. Bacterial or fungal infections were recorded in 13% of tocilizumab patients and in 12% of standard treatment patients. Confirmation of efficacy and safety will require ongoing controlled trials.
IgG4-related disease (IgG4-RD) is a rare fibro-inflammatory condition affecting multiple organs lacking standardized management. In this article, we review the evidence available to provide European ...expert-based statements on the management of IgG4-RD which were integrated in a final algorithm.
A panel of nine European experts in IgG4-RD from different specialties was asked to elaborate a set of consensus statements through a Delphi exercise. Three rounds of survey were taken. Consensus was reached when ≥75% of the responders agreed with a statement.
Thirty-one statements on induction treatment, maintenance treatment, non-pharmacological treatment, and general considerations were assessed. Patients should be treated promptly in situations when there is an immediate organ threatened, or when organ damage is anticipated. Glucocorticoids (GC) are considered the first line of treatment and should be progressively tapered. Maintenance treatment is recommended for patients with high disease activity or with risk factors for relapse. Rituximab is effective for induction and maintenance of remission, but its use can be limited by economics. Low dose GC with or without GC-sparing agents can be used for maintenance therapy. Stenting or surgery should be ancillary to pharmacological treatment. Follow up should be based on physical examination, blood works, and imaging studies. Furthermore, it should be tailored on individual patient clinical history. 18-fluorodeoxyglucose positron emission tomography/computerized tomography may provide additional information over other imaging modalities.
These new statements and algorithm reached a high degree of agreement and may help guiding the clinical management of IgG4-RD.
•IgG4-related disease (IgG4-RD) is a rare inflammatory condition which can affect multiple organs.•Treatment is classically based on glucocorticoids (GC) but novel studies provide new therapeutic options.•We provide an updated guidance on IgG4-RD management and treatment incorporating rituximab and disease-modifying antirheumatic drugs to the baseline treatment.•We reached a series of consensus statements to direct the treatment and management of patients with IgG4-RD.•Clinicians are provided with evidence-based recommendations and an integrative algorithm that might change their practice on IgG4-RD and homogenize it.
IgG4‐related disease (IgG4‐RD) is a fibroinflammatory disorder that can affect virtually every organ system. T‐helper type 2 responses have been presumed to be pathogenic in this disease, and a high ...proportion of patients with IgG4‐RD are reported to have longstanding allergies, peripheral blood eosinophilia, and serum IgE elevation. It has therefore been proposed that allergic mechanisms drive IgG4‐RD. However, no epidemiological assessment of atopy, peripheral blood eosinophilia, and serum IgE concentrations has ever been undertaken in patients with IgG4‐RD. In this study, we evaluated these parameters in a large cohort of patients with IgG4‐RD in whom a wide range of organs were affected by disease. Our results demonstrate that the majority of patients with IgG4‐RD are nonatopic. Nevertheless, a subset of nonatopic subjects exhibit peripheral blood eosinophilia and elevated IgE, suggesting that processes inherent to IgG4‐RD itself rather than atopy per se contribute to the eosinophilia and IgE elevation observed in the absence of atopy.
How T follicular (Tfh) cells contribute to many different B-cell class-switching events during T-cell–dependent immune responses has been unclear. Diseases with polarized isotype switching offer a ...unique opportunity for the exploration of Tfh subsets. Secondary and tertiary lymphoid organs in patients with elevated tissue expression levels of IgE (Kimura disease, KD) and those of IgG4 (IgG4-related disease, IgG4-RD) can provide important insights regarding cytokine expression by Tfh cells.
We sought to identify disease-specific Tfh cell subsets in secondary and tertiary lymphoid organs expressing IL-10 or IL-13 and thus identify different cellular drivers of class switching in 2 distinct types of fibrotic disorders: allergic fibrosis (driven by type 2 immune cells) and inflammatory fibrosis (driven by cytotoxic T lymphocytes).
Single-cell RNA sequencing, in situ sequencing, and multicolor immunofluorescence analysis were used to investigate B cells, Tfh cells, and infiltrating type 2 cells in lesion tissues from patients with KD or IgG4-RD.
Infiltrating Tfh cells in tertiary lymphoid organs from IgG4-RD were divided into 6 main clusters. We encountered abundant infiltrating IL-10–expressing LAG3+ Tfh cells in patients with IgG4-RD. Furthermore, we found that infiltrating AICDA+CD19+ B cells expressing IL-4, IL-10, and IL-21 receptors correlated with IgG4 expression. In contrast, we found that infiltrating IL-13–expressing Tfh cells were abundant in affected tissues from patients with KD. Moreover, we observed few infiltrating IL-13–expressing Tfh cells in tissues from patients with IgG4-RD, despite high serum levels of IgE (but low IgE in the disease lesions). Cytotoxic T cells were abundant in IgG4-RD; in contrast, type 2 immune cells were abundant in KD.
Our analysis revealed a novel subset of IL-10+LAG3+ Tfh cells infiltrating the affected organs of IgG4-RD patients. In contrast, IL-13+ Tfh cells and type 2 immune cells infiltrated those of KD patients.
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