Sex as a predictor of clinical phenotype and determinant of immune response in IgG4-related disease: a retrospective study of patients fulfilling the American College of Rheumatology-European League Against Rheumatism classification criteria.

BACKGROUND: IgG4-related disease is a multiorgan fibroinflammatory disease considered to have an autoimmune origin. Case series describing individual organ involvement have suggested differences in phenotypic expression between males and females. We aimed to characterise differences in IgG4-related disease manifestations between male and female patients in a large single-centre cohort. METHODS: In this retrospective, single-centre cohort study, patients were recruited from the Massachusetts General Hospital Rheumatology Clinic (Boston, MA, USA) and classified according to the American College of Rheumatology-European Alliance of Associations for Rheumatology (ACR-EULAR) classification criteria. Only patients satisfying the ACR-EULAR classification criteria were included in the study. Data on age at diagnosis, organ involvement at baseline, treatment status, and pre-treatment laboratory values were collected. Circulating plasmablasts and B-cell subsets were quantitated by flow cytometry. Active disease was defined by an IgG4-related disease Responder Index score of more than 0. Laboratory values were analysed for patients who were untreated at baseline and had active IgG4-related disease. The main outcomes were assessed in all participants with available data. FINDINGS: Of the 564 participants enrolled in the Massachusetts General Hospital Rheumatology Clinic IgG4-related disease Registry, 328 fulfilled ACR-EULAR classification criteria and were included between January, 2008, and May, 2023. There was a strong male predominance (male:female ratio 2·2:1) with 226 (69%) males and 102 (31%) females, which contrasted markedly with our general rheumatology clinic population (0·4:1; p<0·001). The male predominance increased with each decade of life starting at age 40 years. On average, male patients were 5·5 years older at diagnosis than female patients (63·7 years vs 58·2 years; p=0·0031). We observed male patients to have higher ACR-EULAR classification criteria scores at baseline with a median score of 35·0 (IQR 28·0-46·0), compared with 29·5 (25·0-39·0) for females (p=0·0010). The proportion of male patients with pancreatic and renal involvement was almost double the proportion observed in female patients (50% of the male patients had pancreatic involvement, compared with about 26% of the female patients; p<0·0001). Male patients were more likely to have serological abnormalities at baseline. The distribution of IgG4 values differed significantly between male an female sexes, favouring higher values in males. We found that male patients with IgG4-related disease were more likely to have active B-cell responses in the blood as defined by plasmablast expansions. INTERPRETATION: IgG4-related disease is unusual among autoimmune diseases in that it is more likely to affect males than females and to present with a striking sex-dependent organ distribution and degree of B-cell response. These findings highlight important variation between IgG4-related disease and other conditions generally believed to have an autoimmune basis. Most autoimmune diseases, by contrast to IgG4-related disease, demonstrate pronounced predilections for affecting females more frequently than males. Hypotheses surrounding the cause and pathophysiology of this condition need to consider this unusual sex distribution among patients with IgG4-related disease. FUNDING: National Institutes of Health, National Institute of Allergy and Infectious Diseases, Rheumatology Research Foundation, and the National Institute of Arthritis and Musculoskeletal and Skin Diseases.

Proliferative features of IgG4-related disease.

IgG4-related disease is an immune-mediated disease that can lead to substantial morbidity and organ damage. Capable of affecting nearly any organ system or anatomic site, and showing considerable overlap in clinical presentation with various other diseases, IgG4-related disease often poses a diagnostic challenge for clinicians. Furthermore, there are no diagnostic biomarkers with high specificity for IgG4-related disease, and histopathological examination is nuanced and requires clinical correlation for accurate diagnosis. Therefore, it is crucial for clinicians to recognise the clinical phenotypes of IgG4-related disease. The disease is generally considered to have predominantly fibrotic and proliferative (or inflammatory) manifestations, with distinct clinical, serological and histopathological findings associated with each manifestation. However, the fibrotic and proliferative manifestations of this disease frequently occur together, thereby blurring this dichotomous distinction. In this Series paper, we provide a detailed overview of the clinical manifestations typical of the proliferative features of IgG4-related disease, with an emphasis on the diagnostic evaluation and differential diagnosis of each proliferative disease manifestation. In addition, we summarise the immune mechanisms underlying IgG4-related disease, suggest a framework for how to approach management and monitoring after the diagnosis is established, and highlight current unmet needs for patient care surrounding this disease.

Multimodality Imaging Features of Immunoglobulin G4-related Vessel Involvement.

Immunoglobulin 4 (IgG4)-related disease is a chronic immune-mediated fibroinflammatory disorder. Involvement of the vascular system, including large- and medium-sized vessels, is increasingly recognized. The varied appearances of vascular involvement reflect the sequela of chronic inflammation and fibrosis and can include aortitis and periaortitis with resultant complications such as aneurysm formation and dissection. A diagnosis of IgG4-related large vessel involvement should be considered when there is known or suspected IgG4-related disease elsewhere. Other organs that are typically affected in IgG4-related disease include the lacrimal and salivary glands, thyroid, pancreas, biliary tree, lungs, kidneys, and meninges. Diagnosis typically requires careful correlation with clinical, imaging, serum, and pathologic findings. Patients may be managed with corticosteroid therapy or the anti-CD20 monoclonal antibody, rituximab, if needed. The varied clinical presentations and imaging features of large vessel involvement are discussed herein. Keywords: Vascular, Inflammation, Aorta, IgG4-related Vessel Involvement © RSNA, 2024.

Efficacy and Safety of Inebilizumab in IgG4-Related Disease: Protocol for a Randomized Controlled Trial.

INTRODUCTION: Immunoglobulin G4-related disease (IgG4-RD) is a debilitating multiorgan disease characterized by recurring flares leading to organ dysfunction, decreased quality of life, and mortality. Glucocorticoids, the standard of care for IgG4-RD, are associated with substantial treatment-related toxicity. Inebilizumab, an antibody directed against CD19, mediates the rapid and durable depletion of CD19+ B cells thought to be involved in IgG4-RD pathogenesis. We describe the first international, prospective, double-blind, placebo-controlled trial to evaluate the safety and efficacy of B-cell depletion for flare prevention in IgG4-RD (MITIGATE). METHODS: The study was designed by an international panel of physicians with expertise in IgG4-RD. Critical trial design decisions included the selection of participants, definition of clinically meaningful primary and secondary endpoints, accommodation of standard of care, and development of flare diagnostic criteria. The study is approved for conduct in 22 countries. PLANNED OUTCOMES: The primary efficacy endpoint is time from randomization to the occurrence of the first centrally adjudicated and investigator-treated disease flare during the 1-year randomized controlled period. A set of novel, organ-specific flare diagnostic criteria were developed specifically for this trial, incorporating symptoms and signs, laboratory findings, imaging study results, and pathology data. MITIGATE aims to accrue 39 flares for the primary endpoint, which provides sufficient power to detect a relative risk reduction of 65% in the inebilizumab group. It is anticipated that enrollment of 160 participants will achieve this goal. Additional endpoints include safety, annualized flare rate, flare-free complete remission, quality-of-life measures, and cumulative glucocorticoid use. MITIGATE represents the first randomized, double-blind, placebo-controlled trial of any treatment strategy conducted in IgG4-RD. Data from this study will provide insights into the natural history and pathophysiology of IgG4-RD and the efficacy and safety of B-cell depletion as a therapeutic avenue. TRIAL REGISTRATION: NCT04540497.

Assessment of patient-reported symptoms and distress in IgG4-related disease (IgG4-RD): Development, clinical validation, and content validation of the IgG4-RD Symptom Severity Index.

OBJECTIVE: IgG4-related disease (IgG4-RD), a multi-organ autoimmune disease, causes diverse manifestations that can lead to symptoms and distress. We developed and validated the Symptom Severity Index (SSI) to assess symptom burden. METHODS: A pilot SSI was tested in n = 5; several gaps were identified. Twenty semi-structured qualitative interviews were performed to expand the item set and identify missing symptoms. Subsequent changes resulted in the current SSI; it was administered with quality of life (QOL) measures to n = 136. We assessed symptom burden and the construct validity of the SSI. A distress score for each symptom is calculated by multiplying symptom frequency ("Never" [0 points] to "Every Day" [3 points]) by associated distress ("None" [0 points] to "Very Much" [4 points]). Each distress score is summed to calculate a total SSI score. RESULTS: The SSI assesses the frequency and distress of 24 symptoms. Among n = 136 with ≥ 1 SSI, 90% experienced ≥ 1 symptom and 88% had distress. The median SSI score was 6.5 (IQR 3.0, 18.0). Fear of more severe disease was observed in 49%. The SSI inversely correlated with the SF-36 (r= - 0.51, p<0.001), the feeling thermometer (r= - 0.28, p<0.001), and the EQ-5D (r= - 0.28, p<0.001). The median SSI score was higher during active vs non-active disease among n = 52 who completed >1 SSI (15 [6, 26] vs. 3 [2, 14], p = 0.008). CONCLUSIONS: Symptoms and distress are common in IgG4-RD and associated with worse health-related QOL. The SSI has face, content, and construct validity; it corresponds with QOL measures.

Extrafollicular IgD-CD27-CXCR5-CD11c- DN3 B cells infiltrate inflamed tissues in autoimmune fibrosis and in severe COVID-19.

Although therapeutic B cell depletion dramatically resolves inflammation in many diseases in which antibodies appear not to play a central role, distinct extrafollicular pathogenic B cell subsets that accumulate in disease lesions have hitherto not been identified. The circulating immunoglobulin D (IgD)-CD27-CXCR5-CD11c+ DN2 B cell subset has been previously studied in some autoimmune diseases. A distinct IgD-CD27-CXCR5-CD11c- DN3 B cell subset accumulates in the blood both in IgG4-related disease, an autoimmune disease in which inflammation and fibrosis can be reversed by B cell depletion, and in severe COVID-19. These DN3 B cells prominently accumulate in the end organs of IgG4-related disease and in lung lesions in COVID-19, and double-negative B cells prominently cluster with CD4+ T cells in these lesions. Extrafollicular DN3 B cells may participate in tissue inflammation and fibrosis in autoimmune fibrotic diseases, as well as in COVID-19.

IgG4-related disease as a variable-vessel vasculitis: A case series of 13 patients with medium-sized coronary artery involvement.

INTRODUCTION: IgG4-related disease (IgG4-RD) is a systemic autoimmune fibroinflammatory disease that can affect multiple organ systems. Although large-vessel vasculitis is a well-recognized manifestation of IgG4-RD, this condition is generally not regarded as a vasculitis. We aimed to describe coronary artery involvement (CAI), a vascular distribution about which little is known in IgG4-RD. MATERIAL AND METHODS: Patients with IgG4-related CAI were identified from a large, prospective IgG4-RD cohort. CAI was confirmed by imaging evidence of arterial or periarterial inflammation in any coronary artery. We extracted details regarding demographics, features of IgG4-RD, and manifestations of CAI. RESULTS: Of 361 cases in the cohort, 13 (4%) patients had IgG4-related CAI. All were male and all had highly-elevated serum IgG4 concentrations, with a median value of 955 mg/dL (interquartile range [IQR]: 510-1568 mg/dL; reference: 4-86 mg/dL). Median disease duration at the time of CAI diagnosis was 11 years (IQR: 8.23-15.5 years). Extensive disease in the coronary arteries was the rule: all three major coronary arteries were involved in 11 patients (85%). The coronary artery manifestations included wall thickening or periarterial soft tissue encasement (85%), stenosis (69%), calcification (69%), and aneurysms or ectasia (62%). Five patients (38%) had myocardial infarctions, 2 (15%) required coronary artery bypass grafting, and 2 (15%) developed ischemic cardiomyopathy. DISCUSSION: Coronary arteritis and periarteritis are important manifestations of IgG4-RD, which should be regarded as a variable-vessel vasculitis that is among the most diverse forms of vasculitis known. Potential complications of CAI include coronary artery aneurysms, myocardial infarction, and ischemic cardiomyopathy.

The Positive Predictive Value of a Very High Serum IgG4 Concentration for the Diagnosis of IgG4-Related Disease.

OBJECTIVE: Serum IgG4 concentrations are used to evaluate a diagnosis of IgG4-related disease (IgG4-RD), but the positive predictive value (PPV) of a very high IgG4 level is uncertain. This study evaluated the PPV of a very high IgG4 concentration for diagnosing IgG4-RD. METHODS: The data warehouses of 2 large academic healthcare systems were queried for IgG4 concentration test results. Cases with serum IgG4 concentrations > 5× the upper limit of normal (ULN) were included. Cases of IgG4-RD were determined using the American College of Rheumatology/European Alliance of Associations for Rheumatology (ACR/EULAR) classification criteria. The PPV for IgG4-RD of an IgG4 concentration > 5× ULN was estimated. Other conditions associated with very high IgG4 concentrations and specific features of IgG4-RD cases were characterized. RESULTS: IgG4 concentrations were available in 32,206 cases. Of these, 3039 (9.4%) had elevated IgG4 concentrations, and a final cohort of 191 (0.6%) cases had IgG4 concentrations > 5× ULN (median age 66 yrs, 72% male). The PPV of an IgG4 concentration > 5× ULN for a diagnosis of IgG4-RD was 75.4% (95% CI 68.7-81.3). In the remaining cases, elevated IgG4 concentrations were observed among patients with malignancies, autoimmune diseases, and infections. CONCLUSION: The majority of cases with serum IgG4 concentrations > 5× ULN in this study had IgG4-RD. These data support the high weight placed on very high serum IgG4 concentrations in the ACR/EULAR classification criteria. However, 25% of cases with very high IgG4 concentrations had an alternative diagnosis, underscoring the importance of considering the broad differential of etiologies associated with an elevated IgG4 concentration when evaluating a patient.

Evaluation of the safety, efficacy, and mechanism of action of obexelimab for the treatment of patients with IgG4-related disease: an open-label, single-arm, single centre, phase 2 pilot trial.

BACKGROUND: Obexelimab is a bifunctional, non-cytolytic, humanised monoclonal antibody that binds CD19 and Fc gamma receptor IIb to inhibit B cells, plasmablasts, and CD19-expressing plasma cells. We aimed to evaluate the safety, clinical efficacy, and pharmacodynamic effects of obexelimab in patients with active IgG4-related disease. METHODS: We conducted an open-label, single-arm, single centre, phase 2 pilot trial at the Massachusetts General Hospital in Boston, MA, USA. Eligible patients were aged 18-80 years and had active IgG4-related disease confirmed by an IgG4-related disease responder index score of 3 or more. Patients received 5 mg/kg of obexelimab intravenously every 2 weeks for 24 weeks. Patients on glucocorticoids at baseline were expected to discontinue usage within 2 months following enrolment. The primary endpoint was the proportion of patients with a decrease of 2 or more from baseline in the IgG4-related disease responder index at day 169 (ie, primary responders). Patients who achieved a decrease of 2 or more at any visit were designated as responders. Adverse events were graded on a scale of 1-5 (ie, mild, moderate, severe, life-threatening, or death) according to the Common Terminology Criteria for Adverse Events grading scale (version 4.3). Exploratory analyses were quantification of B-cell CD19 receptor occupancy, plasmablast, total B-cell and CD4+ cytotoxic T-cell count by flow cytometry, and immunoglobulin concentrations by nephelometry. This study is registered with ClinicalTrials.gov, NCT02725476. FINDINGS: Between Feb 24, 2016, and Dec 21, 2016, we enrolled 15 patients. The median age was 63 years (IQR 52-65). Ten (67%) of 15 patients were male, five (33%) were female, and 12 (80%) were White. At baseline, 12 (80%) of 15 patients had an elevated median serum IgG4 concentration of 220 mg/dL (IQR 124-441), and the median IgG4-related disease responder index score was 12 (IQR 7-13). 12 (80%) of 15 patients achieved the primary endpoint (ie, primary responders), 14 (93%) were defined as responders. Reductions from baseline in serum B cells and plasmablasts were observed following treatment with obexelimab. However, in most patients with follow-up data, serum B cells recovered to 75% of baseline concentrations within 42 days of the final obexelimab dose. 13 (87%) of 15 patients reported adverse events, one of which (an infusion reaction) resulted in treatment discontinuation. INTERPRETATION: All patients except for one had clinical responses to obexelimab treatment. Both reductions in circulating B cells without evidence of apoptosis during obexelimab treatment and their rapid rebound after treatment discontinuation suggest that obexelimab might lead to B-cell sequestration in lymphoid organs or the bone marrow. These results support the continued development of obexelimab for the treatment of IgG4-related disease. FUNDING: Xencor, Zenas BioPharma, National Institute of Arthritis and Musculoskeletal and Skin Diseases, and National Institute of Allergy and Infectious Diseases.

Cytotoxic CD8+ T cells may be drivers of tissue destruction in Sjögren's syndrome.

Sjögren's syndrome is a chronic autoimmune disorder whose pathogenesis is poorly understood and that lacks effective therapies. Detailed quantitative and spatial analyses of tissues affected by Sjögren's syndrome were undertaken, including the quantitation of the frequency of selected cell-cell interactions in the disease milieu. Quantitative analyses of CD4+ T cell subsets and of CD8+ T cells in the labial salivary glands from untreated patients with primary Sjögren's syndrome revealed that activated CD8+ cytotoxic T cells (CD8+CTLs) were the most prominent T cells in these infiltrates. An accumulation of apoptotic glandular epithelial cells, mainly ductal and acinar cells, was observed, consistent with the impaired salivary secretion often observed in patients with this disease. FasL expressing activated CD8+ T cells were seen to accumulate around Fas expressing apoptotic epithelial cells. Quantitative analyses of apoptotic cell types and of conjugates between cytotoxic T cells and epithelial cells undergoing apoptosis suggest that Sjögren's syndrome is primarily driven by CD8+CTL mediated execution of epithelial cells mainly represented by ductal and acinar cells.

Distinct disease-specific Tfh cell populations in 2 different fibrotic diseases: IgG4-related disease and Kimura disease.

BACKGROUND: 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. OBJECTIVE: 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). METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

Temporal changes in T cell subsets and expansion of cytotoxic CD4+ T cells in the lungs in severe COVID-19.

Many studies have been performed in severe COVID-19 on immune cells in the circulation and on cells obtained by bronchoalveolar lavage. Most studies have tended to provide relative information rather than a quantitative view, and it is a combination of approaches by various groups that is helping the field build a picture of the mechanisms that drive severe lung disease. Approaches employed to date have not revealed information on lung parenchymal T cell subsets in severe COVID-19. Therefore, we sought to examine early and late T cell subset alterations in the lungs and draining lymph nodes in severe COVID-19 using a rapid autopsy protocol and quantitative imaging approaches. Here, we have established that cytotoxic CD4+ T cells (CD4 + CTLs) increase in the lungs, draining lymph nodes and blood as COVID-19 progresses. CD4 + CTLs are prominently expanded in the lung parenchyma in severe COVID-19. In contrast CD8+ T cells are not prominent, exhibit increased PD-1 expression, and no obvious increase is seen in the number of Granzyme B+ CD8+ T cells in the lung parenchyma in severe COVID-19. Based on quantitative evidence for re-activation in the lung milieu, CD4 + CTLs may be as likely to drive viral clearance as CD8+ T cells and may also be contributors to lung inflammation and eventually to fibrosis in severe COVID-19.

The Association of Illness-related Uncertainty With Mental Health in Systemic Autoimmune Rheumatic Diseases.

OBJECTIVE: Patients with systemic autoimmune rheumatic diseases (SARDs) face illness-related uncertainty, but little is known about the psychological profiles and psychosocial and health needs associated with uncertainty among adults with SARDs. METHODS: Patients from the Massachusetts General Hospital with antineutrophil cytoplasmic antibody-associated vasculitis (AAV), IgG4-related disease (IgG4-RD), and systemic sclerosis (SSc) completed the Mishel Uncertainty in Illness Scale, 8-item Patient Health Questionnaire depression scale, 7-item General Anxiety Disorder scale, Sickness Impact Profile, and a survey of psychosocial needs. The associations of uncertainty and self-reported needs with depression, anxiety, and sickness impact were assessed. RESULTS: One hundred thirty-two patients with AAV (n = 41, 31%), IgG4-RD (n = 61, 46%), or SSc (n = 30, 23%) participated. The mean age was 64 years, 52% were female, and 83% were White. Greater illness-related uncertainty was positively correlated with higher levels of depression (r = 0.43, P < 0.001), anxiety (r = 0.33, P < 0.001), and sickness impact (r = 0.28, P = 0.001). We observed variations in these measures across SARDs, such that uncertainty was more strongly associated with depression and sickness impact in AAV or SSc compared to IgG4-RD. The primary needs that patients endorsed were services for managing physical symptoms (53%), self-care (37%), and emotional concerns (24%), with greater needs strongly associated with greater illness-related uncertainty. CONCLUSION: Among patients with SARDs, illness-related uncertainty is correlated with levels of depression, anxiety, and sickness impact, as well as psychosocial needs. Findings also implicate the need for targeted interventions to address uncertainty and needs among subgroups of patients with different illness profiles.

Abatacept in IgG4-related disease: a prospective, open-label, single-arm, single-centre, proof-of-concept study.

Background: There is strong rationale for interference with T cell co-stimulation in IgG4-related disease (IgG4-RD), but the literature to evaluate this is limited to a single case report. Methods: We conducted a ten-subject proof-of-concept trial of abatacept in active IgG4-RD. All subjects met the ACR/EULAR Classification Criteria for IgG4-RD. Subjects received subcutaneous abatacept 125 mg weekly for 24 weeks. Concurrent glucocorticoid treatment was permitted but if used had to be discontinued by week four. The primary endpoint, complete remission at 24 weeks, was defined as an IgG4-RD Responder Index score of 0. Peripheral blood mononuclear cells were collected at baseline, four weeks, and 12 weeks. B and T cell subsets were quantified using a 25-parameter flow cytometry panel. Findings: The subjects' median age was 68 years; seven subjects were male and nine were Caucasian. Baseline organ involvement was diverse with a median of 5 organs affected at the time of enrollment. The median serum IgG4 concentration was 597 mg/dL (IQR 304-913 mg/dL). Three subjects received concomitant prednisone at baseline. Six subjects (60%) had a disease response by week 12, five of whom maintained this response at week 24. Abatacept was stopped in the remaining five subjects (50%) due to flare (N = 1) or lack of response by week 12 (N = 4). Three subjects (30%) achieved the primary endpoint.Baseline proportions of unswitched memory B cells predicted responsiveness to abatacept. Reductions in serum IgE, circulating plasmablasts, and activated type 2 T follicular helper (TFH2) cells correlated with response to treatment. One adverse event (grade two thrombocytopenia) was attributed to abatacept. Interpretation: Abatacept was associated with variable treatment responses in IgG4-RD. Half of the subjects achieved sustained treatment responses to abatacept alone, without glucocorticoids. Correlates of clinical response included reductions in serum IgE, circulating plasmablasts, and activated TFH2 cells. Response to abatacept was predicted by higher proportions of unswitched memory B cells at baseline.

Derivation and Validation of Algorithms to Identify Patients With Immunoglobulin-G4-Related Disease Using Administrative Claims Data.

OBJECTIVE: Immunoglobulin-G4-related disease (IgG4-RD) is a systemic autoimmune disease that can affect nearly any organ, but its epidemiology remains poorly understood. Validated algorithms to identify cases in claims data will enable studies to describe IgG4-RD epidemiology in the general population. METHODS: Potential claims-based algorithms were developed by IgG4-RD experts using a combination of International Classification of Diseases, Ninth Revision (ICD-9) and International Classification of Diseases, 10th Revision (ICD-10) codes, dispensed medications, and procedure codes for immunoglobulin G (IgG) subclass testing. Algorithms were tested using Medicare Parts A, B, and D linked to medical records (2007-2017). Classification of cases as IgG4-RD was determined using the American College of Rheumatology (ACR) and European League Against Rheumatism (EULAR) classification criteria for IgG4-RD. We estimated the positive predictive value (PPV) of each algorithm; sensitivity was determined using a cohort of patients with IgG4-RD also enrolled in Medicare Parts A, B, and D during the study period. RESULTS: We identified seven algorithms that used a combination of ICD-9 and ICD-10 codes, medication prescriptions, and/or IgG subclass tests to identify patients with IgG4-RD. The PPV of algorithms in the derivation cohort ranged from 57% to 100%, and sensitivity ranged from 0% to 58%. The best performing algorithm in the validation cohort had a PPV of 81% and a sensitivity of 58%. Typical IgG4-RD manifestations were observed in the cohort (n = 36) assembled by this algorithm, including 50% with sialadenitis, 64% with pancreatic disease, 31% with renal disease, and 59% with an elevated IgG4 concentration. CONCLUSION: We derived and validated a well-performing algorithm to identify IgG4-RD cases with typical manifestations of the disease. The claims-based algorithm can be used in research studies of IgG4-RD.

Lifetime Allergy Symptoms in IgG4-Related Disease: A Case-Control Study.

OBJECTIVE: The etiology of IgG4-related disease (IgG4-RD) is unknown, and there has been controversy over the significance of allergic conditions in IgG4-RD. We examined the prevalence of lifetime allergy symptoms in IgG4-RD and the association between these and IgG4-RD. METHODS: We identified IgG4-RD patients and non-IgG4-RD controls without autoimmune conditions seen at a single center. IgG4-RD patients were classified using the American College of Rheumatology/European Alliance of Associations for Rheumatology classification criteria. Allergy symptoms were ascertained by questionnaire. We assessed the association of IgG4-RD features with allergy symptoms. We compared the proportion of cases and controls with allergy symptoms using conditional logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs) after matching cases and controls 1:1 by age and sex. RESULTS: Lifetime allergy symptoms were reported by 165 (71%) of 231 IgG4-RD patients. Aeroallergen symptoms were most commonly reported (n = 135, 58%), followed by skin allergy symptoms (n = 97, 42%) and food allergy symptoms (n = 47, 20%). IgG4-RD cases with a history of allergy symptoms were more likely to have head and neck involvement (OR 2.0 [95% CI 1.1-3.6]) and peripheral eosinophilia (OR 3.3 [95% CI 1.2-9.0]) than those without allergy symptoms. The prevalence of any allergy symptoms was similar between cases and controls (OR 0.7 [95% CI 0.4-1.1]); this remained consistent after stratifying by head and neck involvement. CONCLUSION: Lifetime allergy symptoms are common in IgG4-RD but are not reported more often in IgG4-RD compared to non-IgG4-RD patients without autoimmune conditions. These findings suggest that allergies are not uniquely associated with the pathogenesis or presentation of IgG4-RD.

Neutralizing anti-IL-1 receptor antagonist autoantibodies induce inflammatory and fibrotic mediators in IgG4-related disease.

BACKGROUND: IgG4-related disease (IgG4-RD) is a fibroinflammatory condition involving loss of B-cell tolerance and production of autoantibodies. However, the relevant targets and role of these aberrant humoral immune responses are not defined. OBJECTIVE: Our aim was to identify novel autoantibodies and autoantigen targets that promote pathogenic responses in IgG4-RD. METHODS: We sequenced plasmablast antibody repertoires in patients with IgG4-RD. Representative mAbs were expressed and their specificities characterized by using cytokine microarrays. The role of anti-IL-1 receptor antagonist (IL-1RA) autoantibodies was investigated by using in vitro assays. RESULTS: We identified strong reactivity against human IL-1RA by using a clonally expanded plasmablast-derived mAb from a patient with IgG4-RD. Plasma from patients with IgG4-RD exhibited elevated levels of reactivity against IL-1RA compared with plasma from the controls and neutralized IL-1RA activity, resulting in inflammatory and fibrotic mediator production in vitro. IL-1RA was detected in lesional tissues from patients with IgG4-RD. Patients with anti-IL-1RA autoantibodies of the IgG4 subclass had greater numbers of organs affected than did those without anti-IL-1RA autoantibodies. Peptide analyses identified IL-1RA epitopes targeted by anti-IL-1RA antibodies at sites near the IL-1RA/IL-1R interface. Serum from patients with systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) also had elevated levels of anti-IL-1RA autoantibodies compared with those of the controls. CONCLUSION: A subset of patients with IgG4-RD have anti-IL-1RA autoantibodies, which promote proinflammatory and profibrotic meditator production via IL-1RA neutralization. These findings support a novel immunologic mechanism underlying the pathogenesis of IgG4-RD. Anti-IL-1RA autoantibodies are also present in a subset of patients with SLE and RA, suggesting a potential common pathway in multiple autoimmune diseases.

Vaccine serologic responses among transplant patients associate with COVID-19 infection and T peripheral helper cells.

BACKGROUND: Therapeutically immunosuppressed transplant recipients exhibit attenuated responses to COVID-19 vaccines. To better understand the immune alterations that determined poor vaccine response, we correlated quantities of circulating T and B cell subsets at baseline with longitudinal serologic responses to SARS-CoV-2 mRNA vaccination in heart and lung transplant recipients. METHODS: Samples at baseline and at approximately 8 and 30 days after each vaccine dose for 22 heart and lung transplant recipients with no history of COVID-19, four heart and lung transplant recipients with prior COVID-19 infection, and 12 healthy controls undergoing vaccination were analyzed. Anti-spike protein receptor binding domain (RBD) IgG and pseudovirus neutralization activity were measured. Proportions of B and T cell subsets at baseline were comprehensively quantitated. RESULTS: At 8-30 days post vaccination, healthy controls displayed robust anti-RBD IgG responses, whereas heart and lung transplant recipients showed minimally increased responses. A parallel absence of activity was observed in pseudovirus neutralization. In contrast, three of four (75%) transplant recipients with prior COVID-19 infection displayed robust responses at levels comparable to controls. Baseline levels of activated PD-1 + HLA-DR + CXCR5 - CD4 + T cells (also known as T peripheral helper [T PH ] cells) and CD4+ T cells strongly predicted the ability to mount a response. CONCLUSIONS: Immunosuppressed patients have defective vaccine responses but can be induced to generate neutralizing antibodies after SARS-CoV-2 infection. Strong correlations of vaccine responsiveness with baseline T PH and CD4 + T cell numbers highlights a role for T helper activity in B cell differentiation into antibody secreting cells during vaccine response.