Eosinophilic granulomatosis with polyangiitis exhibits T cell activation and IgG4 immune response in the tissue; comparison with IgG4-related disease

Pursuing Precision Medicine in Managing Rheumatoid Arthritis

Rheumatoid arthritis, characterized by immune dysregulation and joint destruction, is managed through a stepwise algorithm that combines methotrexate with biological and targeted synthetic disease-modifying antirheumatic drugs. Despite considerable advances, the lack of reliable biomarkers for selecting the most effective medication, especially in Phase II and beyond, remains a significant obstacle. As a result, achieving early clinical remission in all patients continues to be challenging. Rheumatoid arthritis demonstrates considerable clinical and molecular diversity, influenced by both genetic predispositions and environmental factors. Recent scientific and technological advances have shed light on the pathogenesis of rheumatoid arthritis, facilitating the stratification of patients into distinct phenotypic subgroups and potentially optimizing the choice of targeted therapies. However, persistent challenges include the high costs and logistical demands of these methodologies, as well as the complexities of conducting large-scale clinical trials. This review highlights the intricate pathogenesis of rheumatoid arthritis and underscores the need to address the disease's heterogeneity through precision medicine. Moving forward, a deeper investigation into rheumatoid arthritis pathogenesis, encompassing both genetic and environmental factors, is crucial. Pursuing precision medicine, grounded in accurate patient stratification, should be embraced as a "moonshot" objective in rheumatoid arthritis treatment, aiming to achieve transformative breakthroughs in management.

Peripheral blood immunophenotypic diversity in patients with rheumatoid arthritis and its impact on therapeutic responsiveness

OBJECTIVE

Considering the diverse aetiologies and immunodysregulatory statuses observed in each patient with rheumatoid arthritis (RA), stratification based on peripheral blood immunophenotyping holds the potential to enhance therapeutic responses to molecular targeted therapies, biological/targeted synthetic disease-modifying antirheumatic drugs (b/tsDMARDs).

METHODS

Immunophenotype analysis was conducted on a cohort of over 500 b/tsDMARDs-naïve patients using flow cytometry. Patients with RA were stratified based on their immunophenotypes, and the treatment response to each targeted therapy was evaluated. Validation was performed using an additional cohort of 183 b/tsDMARDs-naïve patients with RA.

RESULTS

Patients with RA were stratified into five clusters, two of which exhibited distinct RA phenotypes compared with controls, characterised by significant increases in CD4+ effector memory T cells re-expressing CD45RA. Notably, the effectiveness of different b/tsDMARDs varied across clusters. The group using promising b/tsDMARDs was labelled as 'expected' whereas the 'non-expected' group comprised those using others. The expected group outperformed the non-expected group with higher 26-week remission rates (39.9% vs 24.6%, p=0.0004) and low disease activity achievement (80.8% vs 60.2%, p<0.0001). Trajectory analysis showed the non-expected group's 26-week disease activity was influenced by Clinical Disease Activity Index at baseline unlike the expected group. Additionally, different molecular targeted therapies influenced the proportions of each immune cell subset variably. To validate, immunophenotyping was performed on a validation cohort. When 183 cases were grouped based on their b/tsDMARDs usage into expected/non-expected groups, the expected group had a higher remission rate (p=0.0021), further confirming the observed trend.

CONCLUSION

Our findings offer valuable insights into the diversity of RA and potential therapeutic strategies grounded in the molecular underpinnings.

Heterogeneity and individualized therapy for eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA), as a heterogeneous component of antineutrophil cytoplasmic antibody-associated vasculitis, may be induced by a series of environmental and genetic factors, involved with a variety of immune cells and immune components, and presented with various clinical manifestations, with multiple organs and systems (respiratory, skin, heart, kidney, nerve, etc.) involved. The choice of glucocorticoid (GC) dosage and immunosuppressant in traditional treatment strategies varies greatly from individual to individual and is not universally applicable in all the EGPA phenotype spectrum, especially in relapsing or refractory diseases. With the understanding of the heterogeneity of EGPA, a variety of therapeutic approaches are emerging and improving the traditional treatment model. In this review, we summarized the heterogeneity of EGPA etiology and pathogenesis. Clinical and pathological manifestations of the same organ involved also show significant differences and there are even gender differences. Biological treatments that mainly target type 2 inflammatory pathways are widely used in clinical practice for remission induction and maintenance of EGPA. Targeted biological therapy has shown excellent performance in reducing GC dosage and controlling symptoms and recurrence. However, a large number of high-quality randomized controlled studies are still under research for relapsing or refractory EGPA with special organ involvement. We believe that EGPA has a highly heterogeneous phenotype spectrum, and the treatment patterns targeting key molecules in the pathogenesis are of great value for individual treatment of EGPA.

IgG4-related disease for the hematologist

Immunoglobulin G4-related disease (IgG4-RD) is an immune-mediated disease with many important manifestations in hematopoietic and lymphoid tissue. IgG4 is the least naturally abundant IgG subclass, and the hallmark feature of IgG4-RD is markedly increased IgG4-positive plasma cells (with an IgG4 to IgG ratio >40%) in affected tissue, along with elevated polyclonal serum IgG and IgG4 in most patients. Histological diagnosis is essential, and other key features include storiform fibrosis, lymphoplasmacytic infiltrate, tissue eosinophilia, and obliterative phlebitis. The disease can present with predominantly proliferative features, such as swollen lacrimal and salivary glands, orbital pseudotumor, autoimmune pancreatitis, polyclonal hypergammaglobulinemia (PHGG), eosinophilia, and tubulointerstitial nephritis of the kidneys, or predominantly fibrotic disease, including mediastinal and retroperitoneal fibrosis, sclerosing mesenteritis, and hypertrophic pachymeningitis. This review focuses on 4 key hematological manifestations: PHGG, IgG4-positive plasma cell enriched lymphadenopathy (LAD), eosinophilia, and retroperitoneal fibrosis (RPF). These features are found in 70%, 60%, 40%, and 25% of IgG4-RD patients, respectively, but can also represent key hematological "mimickers" of IgG4-RD, including Castleman disease (PHGG, LAD), eosinophilic vasculitis (eosinophilia, PHGG, LAD), hypereosinophilic syndromes (eosinophilia, LAD, PHGG), and histiocyte disorders (PHGG, LAD, RPF). An organized approach to these 4 manifestations, and how to distinguish IgG4-RD from its mimickers, is explained. Proliferative manifestations typically respond very well to treatment corticosteroids, rituximab, and other immunosuppressives, whereas chronic fibrotic disease may not be reversible with current treatment modalities.

Literature review and case study of recurrent EPGA with elevated IgG4 and positive HBsAg successfully treated with rituximab

BACKGROUND

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare form of autoimmune vasculitis. The involvement of IgG4 and HBsAg in EGPA is less common but can occur and may present unique challenges in management.

CASE PRESENTATION

We present a case study of a 70-year-old female diagnosed with EGPA confirmed via renal biopsy. She initially presented with recurrent purpura, diarrhea and progressive numbness in the hands and feet, accompanied by general weakness. Complete remission was achieved with a one-year course of prednisone acetate and cyclophosphamide treatment. However, upon discontinuation of self-medication, the disease relapsed, manifesting as a generalized rash and weakness in the extremities.Skin biopsy revealed eosinophil infiltration, with inflammatory cells predominantly surrounding blood vessels. Notably, during treatment, the patient's hepatitis B markers transitioned from negative to positive for HBsAg. Subsequent administration of entecavir, along with monitoring for a decrease in HBV DNA levels, preceded the initiation of steroids and rituximab to attain remission once more. Among the remaining 15 patients analyzed, all exhibited elevated serum IgG4 levels, with none testing positive for hepatitis B. Notably, only one patient was diagnosed with immunoglobulin G4-related disease (IgG4-RD), suggesting that elevated IgG4 levels alone may not necessarily indicate IgG4-RD.

CONCLUSIONS

Our case report highlights the first instance of recurrent EGPA accompanied by elevated IgG4 and positivity for hepatitis B, which was successfully treated with rituximab. In cases of concurrent hepatitis B, rituximab treatment may be considered once viral replication is under control. However, emphasis on maintenance therapy is crucial following the induction of disease remission.

Multiple lymphadenopathies in eosinophilic granulomatosis with polyangiitis: Differentiating from IgG4-related lymphadenopathy

We report a case of eosinophilic granulomatosis with polyangiitis in a 75-year-old man who developed mononeuritis multiplex and purpura in the lower legs concomitantly presenting with lymphadenopathies. Biopsied lymph node tissue pathologically demonstrated fibrinoid necrotising vasculitis with perivascular eosinophil infiltration, resulting in eosinophilic granulomatosis with polyangiitis diagnosis. Additionally, abundant immunoglobulin (Ig) G4-positive plasma cell infiltration exhibiting >70% IgG4/IgG ratio, without storiform pattern fibrosis and obliterative phlebitis, was observed in the biopsied lymph node. Clinical improvement was observed after corticosteroid therapy. IgG4-related lymphadenopathy has been defined as a distinct clinical category regardless of fulfilling IgG4-related disease classification criteria. However, some autoimmune diseases, including eosinophilic granulomatosis with polyangiitis, can develop lymphadenopathy pathologically similar to IgG4-related lymphadenopathy.

Refractory Eosinophilic Granulomatosis with Polyangiitis Complicated with IgG4-related Disease Showing Different Treatment Responses for Each Organ

We herein report a 75-year-old woman who presented with dyspnea and purpura. She was diagnosed with eosinophilic granulomatosis with polyangiitis (EGPA) based on axonal damage observed in the left tibial nerve and skin and lung pathologies. Lung pathology showed IgG4-positive plasma cells, considered a complication of IgG4-related disease (IgG4-RD). Computed tomography revealed thickening of the abdominal aorta and a poor contrast area in the left kidney, which was indicative of IgG4-RD. Steroid administration improved the IgG4-RD. However, the EGPA resisted treatment; therefore, immunosuppressive drugs and mepolizumab were administered. Refractory EGPA complicated with IgG4-RD showed different treatment responses for each organ.

Renal involvement in eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is a necrotizing vasculitis, which typically affects small-to medium-sized blood vessels. It is characterized by the presence of tissue infiltrates rich in eosinophils, along with the formation of granulomatous lesions. About 40% of cases have positive anti-neutrophil cytoplasm antibodies (ANCA), with predominant perinuclear staining, and anti-myeloperoxidase (anti-MPO) specificity in about 65% of cases. Typical manifestations of EGPA include the late onset of asthma, nasal and sinus-related symptoms, peripheral neuropathy, and significant eosinophilia observed in the peripheral blood. In contrast to granulomatosis with polyangiitis and microscopic polyangiitis, renal involvement in EGPA is less frequent (about 25%) and poorly studied. Necrotizing pauci-immune crescentic glomerulonephritis is the most common renal presentation in patients with ANCA-positive EGPA. Although rarely, other forms of renal involvement may also be observed, such as eosinophilic interstitial nephritis, mesangial glomerulonephritis, membranous nephropathy, or focal sclerosis. A standardized treatment for EGPA with renal involvement has not been defined, however the survival and the renal outcomes are usually better than in the other ANCA-associated vasculitides. Nonetheless, kidney disease is an adverse prognostic factor for EGPA patients. Larger studies are required to better describe the renal involvement, in particular for patterns different from crescentic glomerulonephritis, and to favor the development of a consensual therapeutic approach. In this article, in addition to personal data, we will review recent findings on patient clinical phenotypes based on ANCA, genetics and the impact of biological drugs on disease management.

Eosinophilic granulomatosis with polyangiitis - Advances in pathogenesis, diagnosis, and treatment

Eosinophilic granulomatosis with polyangiitis (EGPA) is a rare disease characterized by eosinophil-rich granulomatous inflammation and necrotizing vasculitis, pre-dominantly affecting small-to-medium-sized vessels. It is categorized as a primary antineutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) but also shares features of hypereosinophilic syndrome (HES); therefore, both vessel inflammation and eosinophilic infiltration are suggested to cause organ damage. This dual nature of the disease causes variable clinical presentation. As a result, careful differentiation from mimicking conditions is needed, especially from HES, given the overlapping clinical, radiologic, and histologic features, and biomarker profile. EGPA also remains a diagnostic challenge, in part because of asthma, which may pre-dominate for years, and often requires chronic corticosteroids (CS), which can mask other disease features. The pathogenesis is still not fully understood, however, the interaction between eosinophils and lymphocytes B and T seems to play an important role. Furthermore, the role of ANCA is not clear, and only up to 40% of patients are ANCA-positive. Moreover, two ANCA-dependent clinically and genetically distinct subgroups have been identified. However, a gold standard test for establishing a diagnosis is not available. In practice, the disease is mainly diagnosed based on the clinical symptoms and results of non-invasive tests. The unmet needs include uniform diagnostic criteria and biomarkers to help distinguish EGPA from HESs. Despite its rarity, notable progress has been made in understanding the disease and in its management. A better understanding of the pathophysiology has provided new insights into the pathogenesis and therapeutic targets, which are reflected in novel biological agents. However, there remains an ongoing reliance on corticosteroid therapy. Therefore, there is a significant need for more effective and better-tolerated steroid-sparing treatment schemes.

Comparison of Clinical Manifestations and Pathology between Kimura Disease and IgG4-Related Disease: A Report of Two Cases and Literature Review

Kimura disease (KD) is a rare, chronic proliferative condition presenting as a subcutaneous mass predominantly located in the head and neck region; it is characterized by eosinophilia and elevated serum IgE levels. IgG4-related disease (IgG4RD) is a fibroinflammatory condition characterized by swelling in single or multiple organs and the infiltration of IgG4 plasma cells. Herein, we presented two cases. Case 1 is a 38-year-old man with a painless mass in his right postauricular region, and Case 2 is a 36-year-old man with painless lymphadenopathy in his bilateral postauricular region. After surgical excision, they showed good recovery with no relapse. Although Cases 1 and 2 shared several overlapping pathological manifestations, there were a few differences that allowed the differentiation of KD and IgG4RD.

[Immunoglobulin-G4-related disease]

After years of confusion about apparently distinct clinical disease symptoms, the term IgG4-related disease (IgG4-RD) has been coined in 2001, uniting these fibroinflammatory clinical entities with a tendency for tumorous enlargement and tissue fibrosis. Over the past two decades, experimental and clinical studies could make astounding progress in the understanding of this elusive disease. By now, we have a reasonable idea of the pathophysiological mechanisms, which opens up new avenues for therapeutic approaches. It seems like a dense lymphoplasmacytic cell infiltrate, consisting of B‑cells, IgG4⁺ plasma cells, follicular T‑helper cells, CD4⁺ cytotoxic T‑cells and M2 macrophages induces a smoldering inflammatory reaction with a fibrogenic cytokine milieu. This stimulates fibroblasts to secrete extracellular matrix components, leading to the histopathologically characteristic storiform fibrosis and obliterative phlebitis. Macroscopically, this reaction results in diffuse organ swelling and tumorous lesions. The macroscopic and histological differentiation from conditions mimicking IgG4-RD can be challenging. This is especially true for granulomatous diseases, such as antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV). The situation is further complicated by the fact that ANCAs can be positive in IgG4-RD and, vice versa IgG4 antibodies can be elevated in numerous differential diagnoses, such as infections, AAV, sarcoidosis, and malignancies. This article provides an overview of the multifaceted clinical condition of IgG4-RD with respect to the pathophysiology, diagnostic steps and treatment. Furthermore, an overview of the differential diagnoses is discussed especially with respect to granulomatous diseases.