Rituximab (monoclonal anti-CD20 antibody) induced posterior reversible encephalopathy syndrome (PRES): A case report and literature review

Posterior reversible encephalopathy syndrome (PRES) is an uncommon neurological condition characterized by reversible subcortical vasogenic edema that primarily affects the posterior areas of the brain. Subcortical vasogenic edema resulting from endothelial injury and hypertension is the pathogenesis. Here, we present a 23-year-old female patient with systemic lupus erythematosus (SLE) and lupus nephritis who developed PRES following Rituximab (a monoclonal anti-CD-20 antibody) administration. The patient initially presented with severe headaches, visual disturbances, and an altered mental status. Neurological examination revealed bilateral cortical blindness, hyperreflexia, and seizures. Brain imaging, including MRI, demonstrated characteristic findings of PRES, with symmetric hyperintensities involving the occipital and parietal lobes on T2-weighted and FLAIR sequences, consistent with vasogenic edema. Rituximab is promptly discontinued, and the patient was managed with supportive care, including antiepileptic drugs and blood pressure control. Within days of Rituximab cessation, the patient showed gradual improvement in symptoms, with resolution of cortical blindness and normalization of MRI findings. Follow-up assessments revealed complete neurological recovery without residual deficits. This instance emphasizes how crucial it is to take into account PRES as a possible side effect in patients receiving Rituximab therapy, especially if those individuals have sudden neurological symptoms. The offending agent must be located and eliminated immediately for the best outcomes. Clinicians should maintain a high index of suspicion for PRES in patients receiving monoclonal anti-CD20 antibody therapies, immunosuppressants, and corticosteroids, facilitating timely diagnosis and intervention to prevent potentially life-threatening complications. More studies are necessary to clarify the pathophysiological mechanisms causing the PRES produced by Rituximab and to improve therapeutic approaches.

The Differential Complement, Fc and Chemokine Receptor Expression of B Cells in IgG4-Related Pancreatobiliary Disease and Primary Sclerosing Cholangitis and Its Relevance for Targeting B Cell Pathways in Disease

Background: Immune-mediated liver and biliary conditions, such as IgG4-related pancreatobiliary disease (IgG4-PB) and a subset of primary sclerosing cholangitis (PSC- high(h)IgG4), exhibit increased IgG4 levels in the blood. The relative expression of IgG4+ and IgG1+ B cells in the blood and the expression of complement and Fc receptors on these IgG1+ and IgG4+ B cells in IgG4-PB and PSC have not been previously described. We hypothesised that the patterns of expression of these cells and their receptors would differ, are relevant to disease pathogenesis and may represent therapeutic targets. Methods: CD19+ B cells were sorted from blood collected from patients with IgG4-PB, PSC-high(h)IgG4 and healthy volunteers. Cells were stained with fluorescent labelled antibodies specific to IgG1, IgG4, complement receptors (CR1 and CR2), Fc receptors (FcεRII and FcγRIIb) and chemokine receptors (CXCR3, CXCR4, CXCR5) and were analysed by flow cytometry. Findings: IgG4-PB, compared to healthy volunteers, showed decreased CR2 expression on IgG1+ B cells (MFI 416 (275-552) vs. 865 (515-3631), p = 0.04) and IgG4+ B cells (MFI 337 (231-353) vs. 571 (398-2521), p = 0.03). IgG4-PB, compared to healthy volunteers, showed increased FcεRII expression on IgG4+ B cells (MFI 296 (225-617) vs. 100 (92-138), p = 0.0145) and decreased FcγRIIb expression on IgG1+ B cells (134 (72-161) vs. 234 (175-291), p = 0.0262). FcγRIIb expression was also decreased in IgG1+ B cells in patients with PSC-hIgG4 compared to healthy volunteers. Conclusions: This exploratory study indicates that in IgG4-PB, B cells have decreased CR2 and FcγRIIb expression and increased FcεRII expression, suggesting altered sensitivity to complement, IgG-mediated inhibition and sensitisation by IgE, which may promote the relative expansion of IgG4+ B cells in this disease.

A clinical perspective on muscle specific kinase antibody positive myasthenia gravis

The discovery of autoantibodies directed against muscle-specific kinase (MuSK) in "seronegative" myasthenia gravis (MG) patients marked a milestone in MG research. In healthy muscle, MuSK regulates a phosphorylation pathway, which is essential for the development and maintenance of acetylcholine receptor (AChR) clusters at the neuromuscular junction. Autoantibodies directed against MuSK are predominantly of the IgG4 subclass, but there is increasing evidence that IgG1-3 could also contribute to the pathology underlying MuSK-MG. MuSK-IgG4 are monovalent and block the binding site for LRP4 on MuSK, thereby inhibiting the downstream phosphorylation pathway and compromising the formation of AChR clusters. Clinically, MuSK-MG is commonly associated with the predominant involvement of bulbar, facial, shoulder and neck muscles. Cholinesterase inhibitors should be avoided in MuSK-MG due to the risk of clinical impairment and cholinergic crisis. Corticosteroids and other non-steroidal immunosuppressants are less effective with the need for higher doses and prolonged treatment. Rituximab, by contrast, has been shown to be particularly effective and is now often used early in the disease course. Its use is associated with a significant improvement in the clinical outcome of MuSK-MG patients over time. This review aims to describe the pathophysiology underlying MuSK-MG and provide a comprehensive overview of the clinical features and therapeutic options.

Efficacy and safety of rituximab induction therapy and effect of rituximab maintenance for IgG4-related disease: a systematic review and meta-analysis

BACKGROUND

Previous studies have reported that rituximab (RTX) therapy might be beneficial in reducing relapse rates in patients with IgG4-related disease (IgG4-RD). Therefore, we aimed to systematically assess the efficacy and safety of RTX induction treatment and the effect of RTX maintenance in patients with IgG4-RD.

METHODS

The protocol was registered in the PROSPERO (CRD42023427352). PubMed, Embase, the Cochrane database, Scopus, and the Web of Science were interrogated to identify studies that evaluated the impact of RTX on prognosis in IgG4-RD. We explored the impact of various subgroups of factors on relapse outcomes and focused on the possible role of maintenance therapy in reducing relapse rates. The pooled incidence of adverse events of RTX therapy and the influencing factors have also been evaluated.

RESULTS

Eighteen studies comprising 374 patients (mean age 56.0 ± 8.7 years; male 73.7 %) with a mean follow-up duration of 23.4 ± 16.3 months were included. The pooled estimate of the response rate, complete remission rate, overall relapse rate, adverse event rate, and serious adverse event rate of RTX induction therapy were 97.3 % (95 % CI, 94.7 %-99.1 %), 55.8 % (95 % CI, 39.6 %-71.3 %), 16.9 % (95 % CI, 8.7 %-27.1 %), 31.6 % (95 % CI, 16.7 %-48.9 %) and 3.9 % (95 % CI, 0.8 %-8.9 %), respectively. In subgroup analysis, the pooled relapse rate was significantly lower in studies with maintenance than without maintenance (2.8% vs 21.5 %, p < 0.01). Pooled Kaplan-Meier relapse curves also demonstrated that RTX maintenance therapy provided a better prognosis.

CONCLUSIONS

RTX induction therapy appears to have satisfactory efficacy in the induction of remission in IgG4-RD. In addition, prophylactic RTX maintenance therapy after induction may be beneficial in preventing relapse of IgG4-RD.

Renal Manifestations of IgG4-Related Disease: A Concise Review

IgG4-related disease (IgG4-RD) is an immune-mediated disorder marked by fibro-inflammatory masses that can infiltrate multiple organ systems. Due to its relatively recent discovery and limited understanding of its pathophysiology, IgG4-related disease may be difficult to recognize and is consequently potentially underdiagnosed. Renal involvement is becoming regarded as one of the key features of this disease. To date, the most well-recognized renal complication of IgG4-related disease is tubulointerstitial nephritis, but membranous glomerulonephritis, renal masses, and retroperitoneal fibrosis have also been reported. This concise review has two objectives. First, it will briefly encapsulate the history, epidemiology, and presentation of IgG4-related disease. Second, it will examine the reported renal manifestations of IgG4-related disease, exploring the relevant histology, imaging, clinical features, and treatment considerations. This synthesis will be highly relevant for nephrologists, rheumatologists, general internists, and renal pathologists to raise awareness and help improve early recognition of IgG4-related kidney disease (IgG4-RKD).

Case report: Isolated immunoglobulin G4-related sclerosing cholangitis misdiagnosed as hilar cholangiocarcinoma

Background

Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) is frequently accompanied with type 1 autoimmune pancreatitis (AIP). Isolated IgG4-SC which is not accompanied with AIP is uncommon in clinical practice, and its manifestations are similar to those of hilar cholangiocarcinoma.

Case presentation

A 55-year-old male presented with persistent aggravation of icteric sclera and skin. He was initially diagnosed with hilar cholangiocarcinoma and underwent surgery. However, positive IgG4 plasma cells were found in the surgical specimens. Thus, a pathological diagnosis of IgG4-SC was established. After that, steroid therapy was given and initially effective. But he was steroid dependent, and then received rituximab therapy twice. Unfortunately, the response to rituximab therapy was poor.

Conclusion

It is crucial to differentiate isolated IgG4-SC from hilar cholangiocarcinoma to avoid unnecessary surgery. Future studies should further explore effective treatment strategy in patients who do not respond to steroids therapy. It is also required to develop novel and accurate diagnostic approaches to avoid unnecessary surgical procedures.

Differential effects of FcRn antagonists on the subcellular trafficking of FcRn and albumin

The homeostasis of IgG is maintained by the neonatal Fc receptor, FcRn. Consequently, antagonism of FcRn to reduce endogenous IgG levels is an emerging strategy for treating antibody-mediated autoimmune disorders using either FcRn-specific antibodies or an engineered Fc fragment. For certain FcRn-specific antibodies, this approach has resulted in reductions in the levels of serum albumin, the other major ligand transported by FcRn. Cellular and molecular analyses of a panel of FcRn antagonists have been carried out to elucidate the mechanisms leading to their differential effects on albumin homeostasis. These analyses have identified 2 processes underlying decreases in albumin levels during FcRn blockade: increased degradation of FcRn and competition between antagonist and albumin for FcRn binding. These findings have potential implications for the design of drugs to modulate FcRn function.

IgG4-related autoimmune pancreatitis and sclerosing cholangitis: A case report and literature review

RATIONALE

Immunoglobulin G4-related disease (IgG4-RD) can involve various organs throughout the body, primarily manifesting as endocrine dysfunction, visual impairment, jaundice, and limited sexual function. IgG4-related autoimmune pancreatitis is triggered by autoimmune reactions and characterized by structural changes in the pancreas and pancreatic ducts. The disease mainly affects middle-aged and elderly males, typically presenting as progressive painless jaundice and misdiagnosed as cholangiocarcinoma or pancreatic cancer.

PATIENT CONCERNS

This study reports a 54-year-old male who consulted with different institutions multiple times due to diabetes, pancreatitis, elevated liver enzymes, and jaundice.

DIAGNOSES

Magnetic resonance imaging revealed swollen head of the pancreas and atrophic tail. Liver and pancreatic tissue pathology showed IgG4 plasma cell infiltration, while liver biopsy indicated interface hepatitis, liver fibrosis, and pseudolobule formation, with no evidence of bile duct damage.

INTERVENTIONS

Following hormone therapy, the patient's serum IgG4 levels and liver enzyme levels returned to normal.

OUTCOMES

The disease relapsed 2 years after maintaining hormone therapy, and the patient underwent additional hormone-induced remission therapy combined with azathioprine.

LESSONS

The purpose of this research report is to enhance the awareness and understanding of IgG4-RD, emphasizing the necessity for personalized treatment strategies that take into account its recurrence, associations, and imaging features. This report provides valuable insights and guidance for clinicians in managing and diagnosing patients with IgG4-RD.

Successful remission induction of IgG4-related ophthalmic disease by obinutuzumab therapy: a retrospective study of 8 patients

OBJECTIVES

To evaluate the therapeutic efficacy and safety of obinutuzumab in remission induction for IgG4-related ophthalmic disease (IgG4-ROD) patients.

METHODS

Eight IgG4-ROD patients were retrospectively enrolled. They were intravenously administered 1000 mg obinutuzumab at baseline and examined for changes in physical signs, orbital structure imaging parameters, IgG4-related disease responder index (IgG4-RD RI), serological index, and adverse events during treatment. The number of treatment sessions was based on treatment response.

RESULTS

The mean IgG4-RD RI scores of all patients at baseline (7.75 ± 2.92) and after treatment (2.00 ± 0.76) were highly significantly different (P < 0.001). Six patients achieved complete remission (CR) (75%) and two patients achieved partial remission (25%). The mean serum IgG4 levels at baseline (9.45 ± 6.95 g/L) and after treatment (1.55 ± 1.09 g/L) showed a mean decrease of 83% (P = 0.0079). The serum IgG4 level correlated well with IgG4-RD RI at baseline and that after each treatment (r = 0.852, P < 0.01; r = 0.78, P < 0.001). In patients with CR, the serum IgG4 levels at baseline correlated positively with dose numbers required for CR (r = 0.86, P < 0.05). Five patients (62.5%) experienced infusion-related reactions (IRRs) during the first obinutuzumab infusion, while only one (12.5%) experienced IRRs during all subsequent eight infusions.

CONCLUSION

Obinutuzumab is a safe and promising therapeutic option for IgG4-ROD. It rapidly reduces ocular inflammation and serum IgG4 levels to avoid excessive corticosteroid usage and reduce potential risk of adverse events.

Single-cell RNA sequencing of submandibular gland reveals collagen type XV-positive fibroblasts as a disease-characterizing cell population of IgG4-related disease

OBJECTIVES

IgG4-related disease (IgG4-RD) is a systemic autoimmune disease with an unknown etiology, affecting single/multiple organ(s). Pathological findings include the infiltration of IgG4-producing plasma cells, obliterative phlebitis, and storiform fibrosis. Although immunological studies have shed light on the dysregulation of lymphocytes in IgG4-RD pathogenesis, the role of non-immune cells remains unclear. This study aimed to investigate the demographics and characteristics of non-immune cells in IgG4-RD and explore potential biomarkers derived from non-immune cells in the sera.

METHODS

We conducted single-cell RNA sequence (scRNA-seq) on non-immune cells isolated from submandibular glands of IgG4-RD patients. We focused on fibroblasts expressing collagen type XV and confirmed the presence of those fibroblasts using immunohistochemistry. Additionally, we measured the levels of collagen type XV in the sera of IgG4-RD patients.

RESULTS

The scRNA-seq analysis revealed several distinct clusters consisting of fibroblasts, endothelial cells, ductal cells, and muscle cells. Differential gene expression analysis showed upregulation of COL15A1 in IgG4-RD fibroblasts compared to control subjects. Notably, COL15A1-positive fibroblasts exhibited a distinct transcriptome compared to COL15A1-negative counterparts. Immunohistochemical analysis confirmed a significant presence of collagen type XV-positive fibroblasts in IgG4-RD patients. Furthermore, immune-suppressive therapy in active IgG4-RD patients resulted in decreased serum levels of collagen type XV.

CONCLUSIONS

Our findings suggest that collagen type XV-producing fibroblasts may represent a disease-characterizing non-immune cell population in IgG4-RD and hold potential as a disease-monitoring marker.

Autoantibody subclass predominance is not driven by aberrant class switching or impaired B cell development

A subset of autoimmune diseases is characterized by predominant pathogenic IgG4 autoantibodies (IgG4-AID). Why IgG4 predominates in these disorders is unknown. We hypothesized that dysregulated B cell maturation or aberrant class switching causes overrepresentation of IgG4+ B cells and plasma cells. Therefore, we compared the B cell compartment of patients from four different IgG4-AID with two IgG1-3-AID and healthy donors, using flow cytometry. Relative subset abundance at all maturation stages was normal, except for a, possibly treatment-related, reduction in immature and naïve CD5+ cells. IgG4+ B cell and plasma cell numbers were normal in IgG4-AID patients, however they had a (sub)class-independent 8-fold increase in circulating CD20-CD138+ cells. No autoreactivity was found in this subset. These results argue against aberrant B cell development and rather suggest the autoantibody subclass predominance to be antigen-driven. The similarities between IgG4-AID suggest that, despite displaying variable clinical phenotypes, they share a similar underlying immune profile.

Eosinophilic Angiocentric Fibrosis of the Orbit: A Clinicopathologic Review of 6 Novel Cases With Review of the Literature

PURPOSE

To describe 6 cases and review the current state of knowledge of eosinophilic angiocentric fibrosis (EAF) involving the orbit.

DESIGN

Retrospective clinicopathologic case series and review of the current literature METHODS: Clinical records and histopathologic data of orbit-involving EAF were gathered between 2004 and 2022 from a single academic institution. The patients' presenting clinical symptoms and signs, laboratory data, radiographic studies, and management documentation were collected.

RESULTS

Retrospective review identified 6 novel cases, totaling 31 cases of EAF involving the orbit described as of this writing. Fourteen patients were male, and the average age of presentation was 49.8 years (range 25-78 years). Eighteen patients had concurrent sinonasal involvement, whereas 13 had primary orbital involvement. The median duration of symptoms prior to evaluation was 24 months, with nasal symptoms, proptosis, periorbital swelling, and pain being the most common presenting symptoms. The majority of patients underwent surgical debulking, as well as treatment with glucocorticoids and steroid-sparing agents, such as rituximab, with varied results.

CONCLUSION

EAF involving the orbit is uncommon. The histopathologic findings include a perivascular, eosinophil-rich infiltrate and a pauci-inflammatory storiform type of fibrosis concentrated around small vessels. Orbital involvement usually results from local extension from adjacent sinuses, but primary orbital involvement has been described. Surgical debulking and immunosuppressive agents such as rituximab have been shown to stabilize disease.

Immune dysregulation in immunoglobulin G4-related disease

(IgG4-RD) is an immune-mediated fibrotic disorder characterized by severe resolution of inflammation and dysregulation of wound healing. IgG4-RD has been considered a unique disease since 2003, and significant progress has been achieved in the understanding of its essential features. The central role of B cells in IgG4-RD has been demonstrated by the robust clinical responsiveness of IgG4-RD to B cell depletion and the identification of multiple self-antigens that promote B cell expansion. Studies have increasingly revealed critical roles of these B cells and T cells in the pathogenesis of IgG4-RD, and we and other authors further identified CD4⁺ cytotoxic T lymphocytes as the main tissue-infiltrating CD4⁺ T cell subset in IgG4-RD tissues. Additionally, T follicular helper cell subsets that play a role in IgG4 isotype switching have been identified. In this review, we discuss research on IgG4-RD and the roles of B cell and T cell subsets, as well as the functions of CD4⁺ cytotoxic T cells in IgG4-RD pathogenesis. We highlight our findings from ongoing research using single-cell analysis of infiltrating CD4⁺ cytotoxic T cells, CD4⁺ follicular helper T cells, and infiltrating B cells in IgG4-RD and propose a model for the pathogenesis of IgG4-RD.

The spectrum of B cells in the pathogenesis, diagnosis and therapeutic applications of immunoglobulin G4-related disease

Immunoglobulin G4 (IgG4)-related disease is a chronic fibroinflammatory disease mediated by immune disorders. Given the challenging clinical diagnosis and treatment, knowledge of the pathogenesis of IgG4-related disease is important. The typical elevation of serum IgG4 concentrations and infiltration of IgG4-positive plasma cells in the involved tissues indicate the involvement of B lymphocytes in the pathogenesis of IgG4-related disease. Mass production of autoantibodies reflects abnormal activation of B cells, which causes tissue damage. Circulating plasmablasts are recently discovered markers that correlate with serum IgG4 concentration, the extent of organ involvement and disease activity. B-cell depletion therapy is an emerging curative strategy that can significantly alleviate clinical manifestations and achieve remission in patients with IgG4-related disease. These findings highlight the potential role of B cells in IgG4-related disease. In this review, we discuss the pathogenic impact of B lymphocytes on IgG4-related disease and describe novel therapies targeting B cells.

The unique properties of IgG4 and its roles in health and disease

IgG4 is the least abundant subclass of IgG in human serum and has unique functional features. IgG4 is largely unable to activate antibody-dependent immune effector responses and, furthermore, undergoes Fab (fragment antigen binding)-arm exchange, rendering it bispecific for antigen binding and functionally monovalent. These properties of IgG4 have a blocking effect, either on the immune response or on the target protein of IgG4. In this Review, we discuss the unique structural characteristics of IgG4 and how these contribute to its roles in health and disease. We highlight how, depending on the setting, IgG4 responses can be beneficial (for example, in responses to allergens or parasites) or detrimental (for example, in autoimmune diseases, in antitumour responses and in anti-biologic responses). The development of novel models for studying IgG4 (patho)physiology and understanding how IgG4 responses are regulated could offer insights into novel treatment strategies for these IgG4-associated disease settings.

IgG4-related digestive diseases: diagnosis and treatment

IgG4-related digestive diseases encompass a group of chronic inflammatory disorders characterized by autoimmune reactions and fibrosis affecting multiple digestive organs. These diseases are identified by elevated serum levels of IgG4 and the presence of IgG4-positive plasma cell infiltration in the affected sites, along with storiform fibrosis, obliterative phlebitis, and eosinophilic infiltration. Although extensive research has been conducted, a comprehensive understanding of these conditions remains elusive. Current clinical diagnosis often relies on the application of integrated diagnostic criteria for IgG4-related diseases, combined with specific organ involvement criteria. Distinguishing them from malignancies poses considerable challenges. Moreover, further investigations are required to elucidate the underlying pathogenic mechanisms and explore potential therapeutic interventions. This review provides a systematic classification of IgG4-related digestive diseases while discussing their diagnostic strategies, clinical presentations, and treatment modalities. The comprehensive insights shared herein aim to guide clinicians in their practice and contribute to the advancement of knowledge in this field.

Eosinophilic dermatosis of hematologic malignancy in patients with chronic lymphocytic leukemia/non-Hodgkin's B lymphoma: a single center prospective clinico-pathological study

Background

The pathogenesis of eosinophilic dermatosis of hematologic malignancy (EDHM) is poorly understood. Previously thought to be a hypersensitivity reaction to insect bites, immune dysregulation and cytokine imbalance are now thought to be responsible. Its prognostic significance is unclear.

Objective

To describe the clinical, pathological and immunological findings in a series of oncohematological patients with EDHM.

Methods

An observational prospective cohort study of oncohematological patients receiving a diagnosis of EDHM between April 2017 and December 2018.

Results

A total of 15 patients with EDHM (10 females and 5 males) were identified among 422 oncohematological patients. Disease presentation varied from firm erythematous papules to more polymorphic presentations. The lesions were most prevalent on the exposed sites, 8/15 patients recalled an insect bite. Lesion seasonality was reported in 13/15 patients. IgE levels were elevated in six patients, circulating IL-4 and IL-5 were within a normal range. Twelve out of 15 patients developed skin manifestations after chemotherapy. The infiltrate could be eosinophil-rich or lymphocytic-rich. Interestingly, the histopathologic findings were in accordance with arthropod bites.

Conclusion

A role for insect bites in EDHM is supported by our findings. EDHM may be related to aggressive hematologic disease.

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.

Immunotherapies in MuSK-positive Myasthenia Gravis; an IgG4 antibody-mediated disease

Muscle-specific kinase (MuSK) Myasthenia Gravis (MG) represents a prototypical antibody-mediated disease characterized by predominantly focal muscle weakness (neck, facial, and bulbar muscles) and fatigability. The pathogenic antibodies mostly belong to the immunoglobulin subclass (Ig)G4, a feature which attributes them their specific properties and pathogenic profile. On the other hand, acetylcholine receptor (AChR) MG, the most prevalent form of MG, is characterized by immunoglobulin (Ig)G1 and IgG3 antibodies to the AChR. IgG4 class autoantibodies are impotent to fix complement and only weakly bind Fc-receptors expressed on immune cells and exert their pathogenicity via interfering with the interaction between their targets and binding partners (e.g. between MuSK and LRP4). Cardinal differences between AChR and MuSK-MG are the thymus involvement (not prominent in MuSK-MG), the distinct HLA alleles, and core immunopathological patterns of pathology in neuromuscular junction, structure, and function. In MuSK-MG, classical treatment options are usually less effective (e.g. IVIG) with the need for prolonged and high doses of steroids difficult to be tapered to control symptoms. Exceptional clinical response to plasmapheresis and rituximab has been particularly observed in these patients. Reduction of antibody titers follows the clinical efficacy of anti-CD20 therapies, a feature implying the role of short-lived plasma cells (SLPB) in autoantibody production. Novel therapeutic monoclonal against B cells at different stages of their maturation (like plasmablasts), or against molecules involved in B cell activation, represent promising therapeutic targets. A revolution in autoantibody-mediated diseases is pharmacological interference with the neonatal Fc receptor, leading to a rapid reduction of circulating IgGs (including autoantibodies), an approach already suitable for AChR-MG and promising for MuSK-MG. New precision medicine approaches involve Chimeric autoantibody receptor T (CAAR-T) cells that are engineered to target antigen-specific B cells in MuSK-MG and represent a milestone in the development of targeted immunotherapies. This review aims to provide a detailed update on the pathomechanisms involved in MuSK-MG (cellular and humoral aberrations), fostering the understanding of the latest indications regarding the efficacy of different treatment strategies.

IgG4 Autoimmune Disease Masquerading As Oroantral Fistula

IgG4-related disease (IgG4-RD) is an immune-mediated disorder that involves multiple organs and is characterized by the infiltration of lymphoplasmacytic cells, including IgG4-positive plasma cells, along with storiform fibrosis and obliterative phlebitis in the inflamed organs. The primary sites affected by this condition include the pancreas, bile ducts, salivary glands, aorta, lungs, kidneys, meninges, lacrimal glands, mediastinal lymph nodes, and retroperitoneum. The pathogenesis is linked to a type 2 T-helper-cell cytokine profile and the involvement of regulatory T cells. However, the exact mechanism is still unknown. Patients with IgG4-related disease are frequently misdiagnosed as having malignancies due to the resemblance of the lesions to infections or other immune-mediated diseases and certain tumors, such as pancreatic cancer and pseudo-renal pelvis tumor. Prompt identification of IgG4-related disease is essential as a delayed diagnosis until advanced stages can result in severe organ damage and potentially fatal outcomes, despite the disease being highly responsive to treatment. This report presents a highly unusual case of IgG4-related disease (IgG4-RD) with an atypical presentation in a 38-year-old female patient. The patient sought medical attention in the emergency department due to nasal septal erosions and an oral-antral fistula. Nasal cultures were conducted and indicated the presence of Klebsiella ozaena. Subsequent investigations, including a nasal biopsy, confirmed the diagnosis of IgG4-related autoimmune disease.

A Case of Immunoglobulin G4-Related Disease Presenting as a Parapharyngeal Mass

Immunoglobulin G4-related disease (IgG4-RD) is a fibroinflammatory condition characterized by tissue infiltration with lymphocytes and IgG4-secreting plasma cells. The presentation of IgG4-RD is heterogenous, making it difficult to diagnose. IgG4-RD presenting as a parapharyngeal mass is extremely rare. This report discusses the case of a 69-year-old African American female presenting with intermittent bilateral frontal headaches. Initial imaging revealed an ill-defined parapharyngeal mass encasing the left internal carotid artery and left internal jugular vein. Subsequent biopsy and immunohistochemistry showed a high concentration of IgG4-positive plasma cells with storiform fibrosis, despite normal serum IgG4 levels. The patient opted for conservative management. The localized parapharyngeal mass has remained stable over two years on annual imaging. This case report highlights that IgG4-RD can have varied and nonspecific presentations requiring high clinical suspicion to diagnose. Histopathology and IgG4 staining are vital to confirm the diagnosis of IgG4-RD, particularly in atypical cases not meeting the standard inclusion criteria.

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.

B-Cell depletion therapy in IgG4-related disease: State of the art and future perspectives

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.

Recent progress on the treatment of type 1 autoimmune pancreatitis and IgG4-related disease

IgG4-related disease (IgG4-RD) is a fibroinflammatory disorder recognized as a novel clinical entity with either synchronous or metachronous multiorgan involvement. Autoimmune pancreatitis (AIP) is classified into two types: type 1 AIP as a pancreatic manifestation of IgG4-RD and type 2 AIP with granulocytic epithelial lesion and occasional association with ulcerative colitis. Although the pathogenic mechanism still remains unclear, possible multipathogenic factors such as genetic factors, disease-specific or related antigens, and abnormal innate or adaptive immunity may be involved in the development of IgG4-RD. Many immunocytes including M2 macrophages, plasmablasts, B cells, and T-cells (Th2-CD4+T, follicular helper T-cells, and CD4+SLAMF7+cytotoxic T-cells) play important roles in the pathogenesis. Conventional induction and maintenance therapies with glucocorticoid or rituximab are recommended in all symptomatic patients with active IgG4-RD. In those at risk for irreversible damage in any organs, this should be done urgently, regardless of symptoms. As no randomized clinical trials other than glucocorticoid maintenance therapy for type 1 AIP have been performed, the comprehensive management for IgG4-RD has not been established yet. Targeted treatment approaches against the plasmablast to B cell lineage and the CD4+ SLAMF7+ cytotoxic T-cell seem to be promising for the future-directed treatment.

Immune Mechanisms in Epileptogenesis: Update on Diagnosis and Treatment of Autoimmune Epilepsy Syndromes

Seizures and epilepsy can result from various aetiologies, yet the underlying cause of several epileptic syndromes remains unclear. In that regard, autoimmune-mediated pathophysiological mechanisms have been gaining attention in the past years and were included as one of the six aetiologies of seizures in the most recent classification of the International League Against Epilepsy. The increasing number of anti-neuronal antibodies identified in patients with encephalitic disorders has contributed to the establishment of an immune-mediated pathophysiology in many cases of unclear aetiology of epileptic syndromes. Yet only a small number of patients with autoimmune encephalitis develop epilepsy in the proper sense where the brain transforms into a state where it will acquire the enduring propensity to produce seizures if it is not hindered by interventions. Hence, the term autoimmune epilepsy is often wrongfully used in the context of autoimmune encephalitis since most of the seizures are acute encephalitis-associated and will abate as soon as the encephalitis is in remission. Given the overlapping clinical presentation of immune-mediated seizures originating from different aetiologies, a clear distinction among the aetiological entities is crucial when it comes to discussing pathophysiological mechanisms, therapeutic options, and long-term prognosis of patients. Moreover, a rapid and accurate identification of patients with immune-mediated epilepsy syndromes is required to ensure an early targeted treatment and, thereby, improve clinical outcome. In this article, we review our current understanding of pathogenesis and critically discuss current and potential novel treatment options for seizures and epilepsy syndromes of underlying or suspected immune-mediated origin. We further outline the challenges in proper terminology.

IgG4-related ophthalmic disease in association with adult-onset asthma and periocular xanthogranuloma: a case report

A 54-year-old male presented with a three-year history of bilateral upper eyelid and peri-orbital swelling and adult-onset asthma. Histopathology of a left orbital biopsy showed lymphoid follicles with foamy macrophages and Touton giant cells. Clinical, histological and radiological features were consistent with adult-onset asthma and periocular xanthogranuloma. Treatment with rituximab led to a complete clinical and radiological remission. Nine years later, his condition relapsed with a biopsy of the left orbit and lacrimal gland demonstrating features of IgG4-related disease and adult-onset asthma and periocular xanthogranuloma. Immunohistochemistry showed increased numbers of IgG4+ plasma cells (290 per high power field) and an elevated IgG4+/IgG+ plasma cell ratio of 480%. Involvement by both disorders in the orbit and ocular adnexa of a single patient has not previously been reported in the literature, to the best of our knowledge, and suggests a possible aetiologic or pathophysiologic association.

Pancreaticobiliary versus head and neck presentation of immunoglobulin G4-related disease: different sides of the same coin?

BACKGROUND AND STUDY AIM

Immunoglobulin G4-related disease (IgG4-RD) is a rare immune mediated fibroinflammatory condition. Pancreaticobiliary (PB) and head and neck (HN) are two of the most commonly involved anatomical sites. It has been postulated that PB IgG4-RD and HN IgG4-RD have distinct clinical phenotypes. Whether the optimum treatment regimen or response to therapy differs between them is unknown. We aimed to assess differences between PB and HN IgG4-RD in a cohort of IgG4 disease managed by an IgG4-RD multispecialty team.

METHODS

We performed a retrospective study of a prospectively maintained multidisciplinary IgG4-RD database to identify patients diagnosed with PB and HN IgG4-RD (based on initial presentation) between 2005 and 2019. The electronic patient records were reviewed. Use of immunosuppressive agents and clinical course was analysed.

RESULTS

60 patients with PB IgG4-RD and 14 with HN IgG4-RD were included in the study. PB IgG4-RD was associated with older age at diagnosis 64 versus 51 years (p<0.001), higher serum IgG4 level as a multiple of upper limit of normal median (IQR) 2 (1-3.75) vs 1 (1-2), (p=0.04) and greater proportion with more than one organ involved 68% vs 33% (p=0.03). HN IgG4-RD was more likely to receive second-line therapy 71% versus 36% (p=0.03). Persistent elevation of serum IgG4 after therapy was more common in PB IgG4-RD 84% versus 43% (p=0.03).

CONCLUSION

These findings support the contention that PB IgG4-RD and HN IgG4-RD have different clinical profiles and represent distinct subtypes of IgG4-RD.

Challenges for clinicians treating autoimmune pancreatitis: Current perspectives

Autoimmune pancreatitis (AIP) is a rare disease clinically characterized by obstructive jaundice, unintentional weight loss, acute pancreatitis, focal pancreatic mass, and diabetes. AIP is classified into two subtypes - type 1 and type 2 - according to pathological findings, clinical features, and serology test results, but some cases may be defined as type not otherwise in the absence of pathological findings and inflammatory bowel disease. To address the differences in diagnostic criteria by country, standard diagnostic criteria for AIP were proposed in 2011 by an international consensus of expert opinions. Differential diagnosis of AIP from pancreatic ductal adenocarcinoma is important but remains challenging for clinicians. Fortunately, all subtypes of AIP show dramatic response to steroid treatment. This review discusses the current perspectives on the diagnosis and management of AIP in clinical practice.

The impact of disease-modifying therapies on immunoglobulin blood levels in patients with multiple sclerosis: a retrospective cross-sectional study

Background

Although disease-modifying therapies (DMTs) in multiple sclerosis (MS) are known to target the immune system, mechanisms of action, efficacy, safety, and tolerability profiles differ. The long-term impact of DMTs on the immune system and its relation to infectious complications is still poorly understood.

Objectives

To analyze the effect of DMTs on serum immunoglobulin (Ig) levels under consideration of patient demographics and therapy duration.

Design

We included 483 patients on DMTs, 69 patients without DMTs, and 51 controls in this retrospective cross-sectional study.

Methods

IgG, IgM, and IgG subclass 1-4 levels of patients with MS under treatment with DMTs were compared with treatment naive MS patients and controls by multivariate linear regression. Further, Ig levels stratified by DMTs were analyzed regarding therapy duration.

Results

MS patients treated with fingolimod (FG), natalizumab, and B-cell depleting therapies (BCDT) demonstrated significantly lower IgG and IgM levels than healthy controls after a median treatment of 37, 31, and 23 months, respectively (p < 0.05). Treatment with dimethyl fumarate (DMF) and teriflunomide was associated with lower IgG, but not IgM levels. DMF and BCDT were also associated with lower IgG1 levels, while FG led to a reduction of IgG2. Treatment with interferon-beta (IFN) and glatiramer acetate (GA) had no impact on Ig levels. Analysis of subgroups by linear regression also showed a time-dependent decrease of Igs levels in patients treated with BCDT with a median annual reduction of IgG of 3.2% and IgM of 6.2%.

Conclusion

Treatment with DMTs, except GA and IFN, was associated with a decrease in Ig levels. DMTs differed in the extent of decreasing Ig levels but also in their differential effects on Ig subclasses. Monitoring of Ig levels should be considered in patients on long-term treatment with DMTs, particularly those on BCDT, to identify patients at risk of low immunoglobulin levels.

Immunoglobulin G4-related disease in the sigmoid colon in patient with severe colonic fibrosis and obstruction: A case report

BACKGROUND

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated condition characterized by abundant IgG4 positive plasma cells and fibrosis in the affected tissues. It affects most parts of the body; however, there are not many reports on IgG4-RD involving the colon.

CASE SUMMARY

A 50-year-old man complaining of intermittent fever for more than two years was referred to our hospital. Based on various investigations before surgery, we diagnosed him with chronic perforation of the sigmoid colon caused by inflammatory change or tumor. IgG blood tests before the operation suggested IgG4-RD, and postoperative pathology confirmed this prediction.

CONCLUSION

We present a patient with IgG4-RD with colon involvement, which is an uncommon site. This report will expand the understanding of IgG4-RD in unknown tissues.

Case report: IgG4-related intracranial lesions mimicking multiple sclerosis in a 14-year-old girl

Objectives

IgG4-related disease (IgG4-RD) is distinguished by the infiltration of IgG4-positive plasma cells in a variety of tissues and organs. Even so, central nervous system lesions associated with IgG4-RD are scarce. We present a case of IgG4-related brain parenchymal lesions that mimics multiple sclerosis in a young girl.

Methods

The patient was followed by our neurology and rheumatology teams. Clinical information was recorded, and the brain was screened using magnetic resonance imaging (MRI). During follow-up, we examined serum IgE, IgG and IgG4 and lymph node biopsy.

Results

Here, we presented details of a 14-year-old Chinese girl suffering from diplopia, left eyelid ptosis, right facial numbness, and right lower limb weakness admitted to our institute. Brain MRI revealed multiple sclerosis-like lesions in the brain parenchyma and spinal cord. During the follow-up, she developed lymphadenopathy. Elevation of serum, IgG, IgG4 and IgE and lymph node biopsy favors a diagnosis of IgG4-RD. The patient had a good response to glucocorticoids and mycophenolate mofetil. The literature review summarized eight previously reported IgG4-RD involving brain parenchyma.

Discussion

Our case expands the known age spectrum of IgG4-RD. The intracranial IgG4-RD is rare and could mimic multiple sclerosis. Careful examination and dynamic review of disease history are crucial in the differential diagnosis.

Imaging findings of immunoglobin G4-related hypophysitis: A case report

BACKGROUND

Immunoglobin G4 (IgG4)-related hypophysitis (IgG4-RH) is a rare form of IgG4-related disease (IgG4-RD), which often manifests as a single organ disease and is easily misdiagnosed as a pituitary tumor clinically and by imaging. There are few reports of imaging findings of IgG4-RH. Therefore, we describe a case of IgG4-RH, which mimicked a pituitary macroadenoma, that was detected by computed tomography (CT) and magnetic resonance imaging (MRI), and review the previous literature in order to further the understanding of IgG4-RH.

CASE SUMMARY

A 47-year-old man presented with a history of blurred vision for more than 2 mo, without other symptoms. A preoperative unenhanced CT scan revealed a slightly hyperdense mass in the sellar region measuring 2.5 cm × 2.3 cm × 1.8 cm, with a CT value of 45 HU. T1-weighted imaging (T1WI) and T2-weighted imaging showed iso-hypointensity, and gadolinium contrast-enhanced T1WI showed obvious homogeneous enhancement. The MRI revealed involvement of the pituitary gland and stalk. Preoperative laboratory tests revealed abnormal pituitary hormone levels, including an increased prolactin level, and decreased levels of insulin-like growth factor, dehydroepiandrosterone, and testosterone. The lesion was surgically resected. Postoperative histopathological examination of a tissue sample and an elevated serum IgG4 level confirmed the diagnosis of IgG4-RH. The patient was treated with cortisone acetate postoperatively and made a good recovery without developing any neurological deficit.

CONCLUSION

An elevated serum IgG4 concentration is the main clue for diagnosis of IgG4-RD. Imaging combined with laboratory testing is useful for preoperative diagnosis of IgG4-RH.

Relevance of Pathogenetic Mechanisms to Clinical Effectiveness of B-Cell-Depleting Monoclonal Antibodies in Multiple Sclerosis

Evidence of the effectiveness of B-cell-depleting monoclonal antibodies (mAbs) in multiple sclerosis (MS) prompted a partial revisitation of the pathogenetic paradigm of the disease, which was, so far, considered a T-cell-mediated autoimmune disorder. Mechanisms underlying the efficacy of B-cell-depleting mAbs in MS are still unknown. However, they likely involve the impairment of pleiotropic B-cell functions different from antibody secretion, such as their role as antigen-presenting cells during both the primary immune response in the periphery and the secondary response within the central nervous system (CNS). A potential impact of B-cell-depleting mAbs on inflammation compartmentalised within the CNS was also suggested, but little is known about the mechanism underlying this latter phenomenon as no definite evidence was provided so far on the ability of mAbs to cross the blood–brain barrier and reliable biomarkers of compartmentalised inflammation are lacking. The present paper briefly summarises the immunopathogenesis of MS with a focus on onset of autoimmunity and compartmentalisation of the immune response; mechanisms mediating B-cell depletion and underlying the effectiveness of B-cell-depleting mAbs are also discussed.

Single-Cell Sequencing of Immune Cell Heterogeneity in IgG4-Related Disease

Background

The IgG4-related disease (IgG4-RD) is an immune-mediated disorder with fibrotic manifestations. However, the transcriptional profiles of immune cell subsets at single-cell level are unknown. Herein, single-cell sequencing was used to assess the specific cell subpopulations and pathways in peripheral blood mononuclear cells (PBMCs) of IgG4-RD.

Methods

Single-cell sequencing was performed using the PBMCs from four patients with IgG4-RD and three healthy controls (HCs). Functional enrichment and cell analysis were performed through re-clustering of PBMCs to assess functional pathways and intercellular communication networks in IgG4-RD. Western blot and flow cytometry were used to verify sequencing and functional enrichment results.

Results

Four major cell types and 21 subtypes were identified. Further subclustering demonstrated that plasma B-cell proportions increased with increasing glycolysis/gluconeogenesis activity in IgG4-RD. Re-clustering of myeloid cells showed that EGR1 and CD36 expressions were significantly increased in CD14⁺ monocytes of IgG4-RD, as validated by Western blot analysis. Moreover, tumor necrosis factor (TNF) production pathways were positively regulated in CD14⁺ monocytes of IgG4-RD. In vitro stimulation showed that CD14⁺ monocytes of IgG4-RD could secrete higher levels of TNF-α . Notably, the proportions of CD8 central memory T (TCM) and TIGIT⁺ CD8 cytotoxic T (CTL) increased in patients with IgG4-RD compared with HCs. Further interaction analysis showed that B cell activation factor (BAFF) signaling pathways were enriched from myeloid cells subsets to B cells.

Conclusion

This study enhances the understanding of the cellular heterogeneity and transcriptional features involved in the pathogenesis of IgG4-RD, providing key clinical implications.

Long-Term Follow-Up and Immunomonitoring of Relapsing Type 1 Autoimmune Pancreatitis Treated With Rituximab

OBJECTIVES

To evaluate the efficacy and safety of rituximab in relapsing type 1 autoimmune pancreatitis  especially the long-term clinical and immunologic impacts.

METHODS

All consecutive patients with type 1 autoimmune pancreatitis were retrospectively included. The rituximab protocol was induction therapy of 375 mg·m -2 intravenous weekly for 4 weeks, followed by 500 mg intravenous every 6 months for 2 years. The follow-up included clinical examinations, biological tests, positron emission tomography scan, and immunomonitoring of lymphocyte CD 19+.

RESULTS

Among the 43 patients included, 15 received rituximab induction therapy, followed by maintenance in 10 cases because of 1 or more relapses after steroids (whether or not followed by immunosuppressants) and multiple organ involvement. All patients had a clinical, biological and morphological response, a deep and persistent drop in serum immunoglobulin G4 levels, an extinction of both pancreatic and extra pancreatic hypermetabolic positron emission tomography scan signals, and a depletion of B lymphocyte CD19+. No relapse occurred during the follow-up (62.8 ± standard error of the mean of 11.1 months).

CONCLUSIONS

Rituximab is an effective treatment for type 1 autoimmune pancreatitis that provides a rapid strong clinical, biological, and morphological response, which persists after discontinuation without any safety issues.

IgG4-related diseases of the digestive tract

IgG4-related conditions affecting the digestive tract are part of a multi-organ fibro-inflammatory disorder termed IgG4-related disease (IgG4-RD), with autoimmune pancreatitis and IgG4-related cholangitis being the most prominent manifestations. Gastrointestinal symptoms include jaundice, weight loss, abdominal pain, biliary strictures, and pancreatic and hepatic masses that mimic malignant diseases. IgG4-RD manifestations occur less frequently elsewhere in the digestive tract, namely in the oesophagus, retroperitoneum or intestine. Evidence-based European guidelines frame the current state-of-the-art in the diagnosis and management of IgG4-related digestive tract disease. Diagnosis is based on histology (if available), imaging, serology, other organ involvement and response to therapy (HISORt criteria). Few biomarkers beyond serum IgG4 concentrations are reliable. The first-line therapy (glucocorticoids) is swiftly effective but disease flares are common at low doses or after tapering. Second-line therapy might consist of other immunosuppressive drugs such as thiopurines or rituximab. Further trials, for example, of anti-CD19 drugs, are ongoing. Although an association between IgG4-RD and the development of malignancies has been postulated, the true nature of this relationship remains uncertain at this time.

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.

Update on classification, diagnosis, and management of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized chronic fibro-inflammatory autoimmune disease, and its recognition has been constantly increasing worldwide over the last few years. A correct and timely recognition, as well as appropriate intervention, is crucial for the treatment of IgG4-RD. For certain subtypes of IgG4-RD, organ-specific criteria are formulated to make the diagnosis more accurate. New biomarkers have emerged in the recent years to aid the disease diagnosis, its prognosis prediction, as well as therapy response monitoring. Although recurrence is very common in IgG4-RD, glucocorticoid is still the first-line treatment for the majority of patients. The factors that affect the likelihood of disease relapse are multifaceted. The selection strategy of various steroid-sparing agents is still being explored. Besides, when patients have special sites involvement leading to severe clinical conditions, surgical operation or interventional therapy should also be considered. An update on classification, diagnosis, and management of IgG4-RD is provided in the current study to fully elucidate the recommended clinical practice of this mysterious disease.

IgG4-Related Disease: A Clinical Case Series From a Tertiary Care Center in India

AIM

Immunoglobulin G4-related disease (IgG4-RD) is often an unrecognized, rare fibroinflammatory condition that can involve various organ systems. This study aimed to identify the different clinical patterns of this disease in a single center in North India.

METHODS

Patients were diagnosed on the basis of published diagnostic criteria for IgG4-RD. Patients' presenting complaints; epidemiologic profiles; and laboratory, radiologic, and histologic findings along with the treatment and outcomes were collected and analyzed.

RESULTS

In total, 70 patients were diagnosed with the disease. The female-to-male ratio was 0.94:1, and it increased with multiorgan involvement. The mean age of patients was 41.4 years, and the majority of the patients (65.7%) were younger than 50 years. Patients were diagnosed as possible (38.57%), probable (32.85%), and definite (28.57%) IgG4-RD. The incidence of the involvement of orbital and periorbital tissues was the highest (52.9%); however, 13% of the patients had multiple organ involvement. Patients with involvement of the retroperitoneal tissues and the lymph nodes were 8.5% and 5.7%, respectively. Increased serum IgG4 levels were found in 74.3% of the patients with single-organ involvement, whereas all patients with multiorgan involvement had increased IgG4 levels. The majority of patients (94.3%) required immunosuppressive medications along with corticosteroids. Azathioprine was the most commonly used (72.8%) immunosuppressive medication. Rituximab was used in 17.1% of the patients, of whom only one had multisystem involvement.

CONCLUSIONS

This study depicts the most common patterns of organ involvement, along with the epidemiologic, laboratory, histologic, and radiologic data and response to treatment, in IgG4-RD, with a definite ophthalmology referral bias.

Therapy of immunoglonuline IgG4 related disease (IgG4-RD)

Immunoglobulin IgG4 related disease (IgG4-RD) is a heterogeneous disorder with multi-organ involvement recognised as a separate entity at the beginning of this century only. Evolving therapy is reviewed in this paper. Glucocorticoids are first choice drug but long administration of glucocorticoids is connected with many adverse effects. In case of combination glucocorticoids and immunosuppressive agents lower doses of glucocorticoids are needed, the response rate is higher and therapy is better tolerated. Rituximab is drug, that is possible use as monotherapy or in combination with glucocorticoids and immunosuppressive drugs. Only one study compared two immunosuporessive drugs, mycophenolate mofetil and cyclophosphamide. The response rated was similar but remissions were longer after glucocorticoids with cyclophosphamide then glucocorticoids with mycofenolat mofetil. No other comparative study of combination of various imunossupressive drugs with glucocorticoids was published. Rituximab has high number (90 %) of response rate in monotherapy, but can be used in combination with glucocorticoids and immunosuppressives. Rituximab is now preferred and recommended for maintenance therapy administered in 6-month interval. In case of advanced disease, we prefer therefore combination of rituximab, cyclofosphamide and dexamethasone for initial therapy followed by maintenance with rituximab in 6 months interval. There are two new drugs under investigation abatacept and dupilimab with promising results. Although we have very intensive therapies for good results of therapy early diagnosis before irreversible fibrotic changes in IgG4-RD involved organs is still needed.

IgG4-Related Esophageal Disease Presenting as Esophagitis with Chronic Strictures

IgG4-related disease is a recently recognized autoimmune systemic disorder that has been described in various organs. The disease is characterized histologically by a dense lymphoplasmacytic infiltrate with IgG4-positive cells, storiform fibrosis, obliterative phlebitis, and can be associated with space-occupying lesions. IgG4-related disease involving the upper gastrointestinal tract is rare. We report the case of a 30-year-old female patient with a long-standing history of severe dysphagia and odynophagia. Symptoms persisted despite anti-acid therapy, and control esophagogastroduodenoscopy revealed endoscopic images consistent with a nontransposable stenosis in the proximal esophagus. An underlying autoimmune process was suspected, and topical immunosuppressants were tried to control her disease. The patient maintained disabling dysphagia secondary to chronic esophageal strictures. A diagnosis of probable IgG4-related disease was made after esophageal biopsies. Treatment attempts with topical corticosteroids was not associated with a significant improvement of the symptoms of dysphagia and odynophagia, possibly because of the chronic nature of the disease associated with a high fibrotic component. This report describes a case of IgG4-related esophageal disease presenting as chronic esophagitis with strictures. We also briefly review the main histopathological features and treatment options in IgG4-related disease.

Rituximab as Maintenance Therapy in Type 1 Autoimmune Pancreatitis: An Italian Experience

OBJECTIVE

Rituximab (RTX) has been proposed for the induction of remission and maintenance therapy in relapsing type 1 autoimmune pancreatitis (AIP). The aim of the study was to describe the use of RTX as maintenance therapy for patients with type 1 AIP.

METHODS

Patients with type 1 AIP based on the International Consensus Diagnostic Criteria and treated with RTX were selected from our database. Two doses of RTX (1000 mg each) were administered 15 days apart and repeated after 6 months.

RESULTS

Eighteen patients were treated with RTX as maintenance therapy. Of these, the involvement of other organs was observed in 16 patients (89%). Eight of the 18 patients (44%) relapsed during follow-up. Median time to relapse after the last infusion was 30 months (range, 12-35 months). No disease relapse was observed in the first year after the last infusion. Probability of disease relapse was 80% between 1 and 3 years from initial treatment. No adverse effects were observed.

CONCLUSIONS

Rituximab seems be safe and effective for maintenance therapy of type 1 AIP during the first year after completing RTX infusion. However, the probability of disease relapse is high within 1 and 3 years from the last infusion.

B-Cell-Depleting Therapy Improves Myocarditis in Seronegative Eosinophilic Granulomatosis with Polyangiitis

Cardiac involvement is a major mortality cause in eosinophilic granulomatosis with polyangiitis (EGPA), requiring novel therapeutics to spare the use of cyclophosphamide with known cardiotoxicity. Despite the observed efficacy of B-cell-depleting therapy in myocarditis of seropositive microscopic polyangiitis, it remains to be elucidated in seronegative EGPA. A retrospective study was performed in 21 hospitalized active patients aged 20 to 70 years with five-factor score 1 or 2, eosinophil counts 10,034 ± 6641/μL and vasculitis scores 27 ± 6. Overt myocarditis was identified in 10 cases, at disease onset in 6 and relapse in 4, with endomyocarditis in 4 and myopericarditis in 4. Five seronegative and one seropositive patient received rituximab with an induction regimen 375 mg/m² weekly × 4 for refractory or relapse disease, and the same regimen for annual maintenance therapy. All cases had lower eosinophil counts, improved cardiac dysfunction and clinical remission with a relapse-free follow-up, 48 ± 15 months after the induction treatment. One seronegative endomyocarditis patient had eosinophilia and disease relapse with asthma attack and worsening cardiac insufficiency 24 months after induction, achieving clinical remission under anti-IL-5 therapy. Our findings suggest the suppression of IL-5-mediated eosinophilia as an action mechanism of B-cell-depleting therapy in seronegative EGPA myocarditis.

IgG4 Related Disease is characterized by the overexpression of Immunomodulatory proteins

INTRODUCTION

IgG4 related disease (IgG4-RD) is a multisystem disease, characterized by tumefactive lesions and a swift response to immunosuppressive therapy. Although elevated serum and tissue IgG4 are characteristic, T-cells appear to be the primary driver of this immunologically mediated disease. The overarching goal was to examine the role of immunomodulatory cells in IgG4-RD.

METHODS

Biopsies from patients with IgG4-RD (n=39) and mimics of this disease (n=78) were evaluated for IgG4, IgG, CD8, PD-L1 and a subset (n=18) evaluated for CD4, PU.1, Foxp3, PD-L1, PD-1, IDO1 and LAG3. Data pertaining to demographics and laboratory findings at baseline evaluation was extracted from electronic medical records.

RESULTS

When compared to mimics, IgG4-RD showed increased numbers of PD-L1 (p=0.0001), PD-1 (p=0.001), IDO1 (p=0.03), LAG3 (p=0.04) and Foxp3 (p=0.04) positive immune cells. The PD-L1 positive cells were enriched within aggregates of CD4 and CD8 positive T-cells. 31 of 39 (80%) IgG4-RD cases showed greater than 5 PD-L1 positive cells per HPF, while 4 of 78 (5%) mimics of this disease exceeded this cut point. In IgG4-RD PD-L1 positive macrophages correlated with PD-1 (p=0.002), LAG3 (p=0.001) and IDO1 positive cells (p=0.001); a positive correlation was also noted between IgG4/IgG ratio and PD-L1, PD-1, and IDO1 positive cells.

CONCLUSIONS

IgG4-RD shows expansion of mechanisms that maintain peripheral tolerance. The spatial and temporal relationship between T-cells and the PD-L1-PD1 axis, and the upregulation of multiple immunomodulatory proteins suggests that these immunoregulatory mechanisms play a significant role in IgG4-RD.

Immunoglobulin G4 hypophysitis in a 63-year-old woman with no autoimmune history: a case report

Background

Immunoglobulin-G4-related hypophysitis is a rare inflammatory disease that can present as a tumefactive pituitary lesion mimicking hypophyseal neoplasms such as pituitary adenoma or craniopharyngioma. The literature on this entity is sparse, with fewer than 100 cases reported across 19 publications; a recent review found only 24 cases published from 2007 to 2018. Previous reports have described demographic differences, with immunoglobulin-G4-related hypophysitis in females tending to present in the second and third decades in association with other autoimmune disease, while males tend to present in the fifth and sixth decades of life without an autoimmune history.

Case presentation

In contrast to the reported demographic trends, here we describe a unique case of immunoglobulin-G4-related hypophysitis in a 63-year-old white female with no history of autoimmune disease who presented with a rapidly enlarging sellar and hypothalamic mass causing headaches and cranial nerve palsies, prompting biopsy for diagnosis. The patient experienced rapid response to treatment with high-dose steroids and rituximab.

Conclusion

The case contributes to the growing clinicopathologic description of immunoglobulin-G4-related hypophysitis and illustrates that this diagnosis should be a consideration even outside the conventional demographic setting.

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.