Immunophenotype involved in IgG4-related disease

A case of immunoglobulin G4-related disease complicated by atopic dermatitis responsive to upadacitinib treatment

Immunoglobulin G4-related disease (IgG4-RD) is mainly treated with glucocorticoids. In many cases, this disease is resistant to glucocorticoids, and their toxicity can be a problem. We encountered a patient with IgG4-RD affecting multiple organs (such as the skin, lung, and lacrimal gland), who had comorbidities, including atopic dermatitis and diabetes. In this case, while glucocorticoid tapering was difficult, the introduction of upadacitinib resulted in the remission of both atopic dermatitis and IgG4-RD without glucocorticoid dose escalation. Peripheral blood flow cytometry analysis showed that the proportions of activated non-Th1/Th17 cell subset (Th2 cells), follicular helper T cells, and plasmocytes were increased before upadacitinib therapy, but all normalised after treatment. Interleukin-4 and interleukin-21 signals are important for the differentiation of CD4+ T cells into type 2 helper T or B cells in the peripheral blood. Our case suggested that inhibition of Janus kinase 1, which mediates these signals, might have contributed to improved pathological conditions in IgG4-RD.

Extracting immunological and clinical heterogeneity across autoimmune rheumatic diseases by cohort-wide immunophenotyping

OBJECTIVE

Extracting immunological and clinical heterogeneity across autoimmune rheumatic diseases (AIRDs) is essential towards personalised medicine.

METHODS

We conducted large-scale and cohort-wide immunophenotyping of 46 peripheral immune cells using Human Immunology Protocol of comprehensive 8-colour flow cytometric analysis. Dataset consisted of >1000 Japanese patients of 11 AIRDs with deep clinical information registered at the FLOW study, including rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). In-depth clinical and immunological characterisation was conducted for the identified RA patient clusters, including associations of inborn human genetics represented by Polygenic Risk Score (PRS).

RESULTS

Multimodal clustering of immunophenotypes deciphered underlying disease-cell type network in immune cell, disease and patient cluster resolutions. This provided immune cell type specificity shared or distinct across AIRDs, such as close immunological network between mixed connective tissue disease and SLE. Individual patient-level clustering dissected patients with AIRD into several clusters with different immunological features. Of these, RA-like or SLE-like clusters were exclusively dominant, showing immunological differentiation between RA and SLE across AIRDs. In-depth clinical analysis of RA revealed that such patient clusters differentially defined clinical heterogeneity in disease activity and treatment responses, such as treatment resistance in patients with RA with SLE-like immunophenotypes. PRS based on RA case-control and within-case stratified genome-wide association studies were associated with clinical and immunological characteristics. This pointed immune cell type implicated in disease biology such as dendritic cells for RA-interstitial lung disease.

CONCLUSION

Cohort-wide and cross-disease immunophenotyping elucidate clinically heterogeneous patient subtypes existing within single disease in immune cell type-specific manner.

Development of targeted therapies in IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease characterized by high serum IgG4 levels, infiltration of lymphocytes and IgG4-positive plasma cells into affected tissues, and subsequent fibrosis, forming mass, nodular, and thickened lesions in organs. Although glucocorticoids (GCs) are the first-line treatment for IgG4-RD, the disease often relapses during dose reduction or after discontinuation of GC. Long-term treatment with GC is associated with adverse effects such as infection, osteoporosis, and atherosclerosis. Therefore, there is an urgent need to develop a treatment strategy that specifically addresses the pathogenesis of IgG4-RD. As immunocompetent cells and immune-related molecules involved in the pathogenesis of IgG4-RD are increasingly being identified, there is a growing demand for new molecular-targeted drugs that target them. In particular, favourable results have been reported for drugs that target B cells, such as anti-cluster of differentiation (CD)20 and anti-CD19 antibodies. In addition, clinical trials are underway for new therapeutic agents, such as anti-signalling lymphocytic activation molecule family 7 antibodies that target T cells and other cells.

Perspectives on current and emerging therapies for immunoglobulin G4-related disease

Understanding of the pathophysiology of immunoglobulin G4-related disease (IgG4-RD) over the last dozen years has opened the door to a variety of targeted treatment approaches. Glucocorticoids are an effective treatment for IgG4-RD if used at a sufficiently high dose, but disease flares are common during or after glucocorticoid tapers and these medications seldom lead to long-term, treatment-free remissions. Moreover, their long-term use in a disease that frequently affects middle-aged to elderly individuals and often causes major pancreatic damage leads to a narrow therapeutic index. Biological therapies offer the possibility of effective disease control with fewer treatment-associated side effects. Promising avenues of investigation include B-cell depletion, immunomodulation of B-cell subsets, interference with co-stimulation, Bruton's tyrosine kinase inhibition, and Signaling lymphocytic activation molecule F7-directed treatment.

Thoracic manifestations of IgG4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a recently described rare systemic fibroinflammatory disease with an estimated incidence of less than 1 in 100,000 persons per year. The disease can affect virtually any organ and is characterized by unifying histopathological findings. Recently, four subgroups of patients have been characterized: hepatobiliary, head and neck, Mikulicz syndrome and retroperitoneal fibrosis, who illustrate the mainly abdominal and ENT tropism of the disease. Yet, thoracic involvement is not uncommon. It can be detected in up to 30% of patients with systemic IgG4-RD and is the exclusive manifestation of the disease in about 10% of cases. Clinical symptoms are nonspecific and may include dyspnoea, cough or chest pain. Chest CT findings are heterogeneous and primarily include peribronchovascular thickening, nodules, ground-glass opacities and lymphadenopathy. There is no specific diagnostic test for IgG4-RD thoracic involvement, which may mimic malignancy or vasculitis. Therefore, a cautious approach is needed to make an accurate diagnosis: a search for extra-thoracic manifestations, elevated serum IgG4 levels, circulating levels of plasmablasts and pathologic evidence of disease is warranted. Although very suggestive, neither the presence of a polyclonal IgG4 lymphoplasmacytic infiltrate, storiform fibrosis or obliterative phlebitis are sufficient to confirm the histological diagnosis. Steroids are recommended as first-line therapy. Rituximab or disease-modifying antirheumatic drugs may be used in relapsed or rare cases of steroid-refractory disease. In this review, we summarize current knowledge regarding the pathophysiology, epidemiology, diagnostic modalities (clinical-biological-imaging-histopathology) and treatment of IgG4-RD thoracic involvement.

T Cell Roles and Activity in Chronic Sclerosing Sialadenitis as IgG4-Related Disease: Current Concepts in Immunopathogenesis

IgG4-related disease is a multiorgan immunological fibroinflammatory disorder characterized by lymphoplasmacytic infiltration and fibrosis in multiple organs accompanied by high serum IgG4 levels. The salivary glands are the most common organs involved in this disease. Recently, chronic sclerosing sialadenitis affecting salivary glands, formerly known as Küttner's tumor, and Mikulicz's disease have been classified as a class of IgG4-related diseases. The etiopathobiology of IgG4-related disease is not fully understood. It has recently been hypothesized that the inflammatory and fibrotic process and the increased serum IgG4⁺ levels in IgG4-related disease are the result of an interaction between B cells and T helper cells, suggesting that T cells may play a key role in the pathogenesis of this disease. The aim of this review is to discuss the proposed roles of different T cell subsets in the pathogenesis of IgG4-related disease focusing on their roles in immunopathogenesis of IgG4-related sialadenitis.

T helper cells expressing fractalkine receptor and bearing T follicular helper 1-like cell functions in patients with IgG4-related disease

OBJECTIVE

Since the pathological features of IgG4-related disease (IgG4-RD) include lymphocyte infiltration and fibrotic changes in the lesions, we investigated the significance of fractalkine (CX3CL1) and lymphocyte subsets in patients with IgG4-RD.

METHODS

Peripheral blood and biopsied samples were obtained from healthy controls (HCs, n = 10), rheumatoid arthritis (RA, n = 10), and IgG4-RD patients (n = 16) and were analyzed by flow cytometry, immunohistology and costimulation assays.

RESULTS

Peripheral CX3CR1+ CD4+ T cells had an approximately threefold increase in the IgG4-RD patients (15.4%), compared with the HCs (5.0%). In addition, CX3CR1+ CD4+ T cells were localized in the salivary glands of the IgG4-RD patients but not in those with Sicca syndrome. CX3CR1 was induced on 20% of CD4+ T cells after T cell receptor (TCR) simulation with IL-12 for five days-culture. CX3CR1+ T cells showed high expression of both CXCR5 and CXCR3. Moreover, they co-expressed Bcl-6 and T-bet, the master transcription factors for T helper 1 (Th1) and T follicular helper (Tfh) cells. After secondary stimulation, CX3CR1+ T cells produced both interferon-gamma (IFN-γ) and IL-21. Compared with their CX3CR1- counterparts, CX3CR1+ CD4+ T cells induced plasmablast differentiation from naïve B cells more efficiently (15.0 vs 5.0%) and increased the production of IgG2, IgG3, and IgG4 by B cells.

CONCLUSION

CX3CR1+ CD4+ T cells characteristically increased in the peripheral blood and the affected tissues and were associated with an increase in the serum IgG4 levels of patients with IgG4-RD. This CD4 subset has a Th1/Tfh-like phenotype and a B cell helper function.

Novel mechanism of hepatobiliary system damage and immunoglobulin G4 elevation caused by Clonorchis sinensis infection

Clonorchis sinensis infection is still a major public health problem. It is estimated that more than 15 million people worldwide are infected, especially in Northeast China, Taiwan, South Korea, and North Vietnam. The detection of Clonorchis sinensis eggs in feces and bile is still the only gold standard for the diagnosis of Clonorchis sinensis infection, and new detection methods are needed to improve the detection rate. After Clonorchis sinensis invades the human body, it mainly parasitizes the hepatobiliary tract. Therefore, it is closely related to hepatobiliary diseases such as cholangitis, bile duct stones, liver fibrosis, and cholangiocarcinoma. The increase in immunoglobulin G4 (IgG4) caused by Clonorchis sinensis infection is rare and there are few reports about the relevant mechanism. It may be related to the inflammatory factors interleukin (IL)-4, IL-10, and IL-13 produced by human phagocytes, T cells, B cells, and other immune cells in the process of resisting the invasion of Clonorchis sinensis. However, this finding still needs further clarification and confirmation. This article reviews the epidemiology, clinical manifestations, serology, imaging, pathogenic mechanism, and control measures of Clonorchis sinensis infection to help establish the diagnostic process for Clonorchis sinensis. We report novel mechanisms of IgG4 elevation due to Clonorchis sinensis infection to provide more experience and a theoretical basis for clinical diagnosis and treatment of this infection.

UPLC-MS based plasma metabolomics and lipidomics reveal alterations associated with IgG4-related disease

OBJECTIVE

The pathogenesis of IgG4-related disease (IgG4-RD) remains unclear. Metabolomic profiling of IgG4-RD patients offers an opportunity to identify novel pathophysiological targets and biomarkers. This study aims to identify potential plasma biomarkers associated with IgG4-RD.

METHODS

Thirty newly diagnosed IgG4-RD patients, age-matched healthy controls and post-treated IgG4-RD patients were enrolled. Patients' clinical data, laboratory parameters and plasma were collected. Plasma was measured for ultraperformance liquid chromatography-tandem mass spectrometry based metabolomics and lipidomics profiling. Multivariate and univariate statistical analyses were conducted to identify potential biomarkers. The receiver operating characteristic and the correlations between biomarkers and clinical parameters were investigated.

RESULTS

The plasma metabolites are altered among healthy controls, newly diagnosed IgG4-RD and post-treated IgG4-RD groups. Of the identified features, eight metabolites were significantly perturbed in the IgG4-RD group, including glyceric acid 1,3-biphosphate (1,3-BPG), uridine triphosphate (UTP), uridine diphosphate glucose (UDP-Glc) or uridine diphosphate galactose (UDP-Gal), lysophospholipids, linoleic acid derivatives and ceramides. Receiver operating characteristic analysis indicated that UTP, UDP-Glc/UDP-Gal and LysoPC (18:1) had high sensitivity and specificity in diagnosis of IgG4-RD. A Pearson correlation analysis showed that 1,3-BPG and UTP were strongly correlated with clinical parameters.

CONCLUSION

IgG4-RD patients have a unique plasma metabolomic profile compared with healthy controls. Our study suggested that metabolomic profiling may provide important insights into pathophysiology and testable biomarkers for diagnosis of IgG4-RD.

Serum checkpoint molecules in patients with IgG4-related disease (IgG4-RD)

Background

Immunoglobulin G4-related disease (IgG4-RD) is characterized by increased serum IgG4 concentration and infiltration of IgG4⁺ plasma cells in the affected organs. The present study aimed to characterize the serum levels of coinhibitory checkpoint molecule, T cell immunoglobulin and mucin-containing-molecule-3 (TIM-3), and its ligand, galectin-9 (Gal-9), among IgG4-related disease in patients with IgG4-RD patients with various organ involvements.

Methods

Serum samples were collected from untreated 59 patients with IgG4-RD, 13 patients with rheumatoid arthritis, and 37 healthy controls (HCs). HCs lacked chronic medical diseases or conditions and did not take prescription medications or over-the-counter medications within 7 days. Patients with IgG4-RD (n = 57) were subdivided into those with visceral involvement (n = 38) and those without visceral involvement (n = 21). Serum levels of Gal-9 and soluble TIM-3 (sTIM-3) were determined using enzyme-linked immunosorbent assay (ELISA). The results were compared with the clinical phenotypes of IgG4-RD.

Results

In untreated patients with IgG4-RD, serum levels of Gal-9 and sTIM-3 were significantly higher than in RA patients as well as in healthy controls. There were significant correlations between the serum levels of Gal-9 or sTIM-3 and serum levels of IgG, BAFF, or sIL-2R. However, there was no significant correlation between the serum levels of Gal-9 or sTIM-3 and serum IgG4 concentrations. Serum levels of sTIM-3 were significantly higher in a subset of patients with visceral involvements than in those without visceral involvements. However, there was no significant difference in the serum levels of Gal-9 between IgG4-RD patients with and without visceral involvements, although both Gal-9 and sTIM-3 were elevated in untreated IgG4-RD patients, and the levels of these checkpoint molecules remained unchanged after steroid therapy.

Conclusion

Serum levels of Gal-9 and sTIM-3 were significantly elevated in untreated patients with IgG4-RD. Furthermore, serum levels of sTIM-3 were significantly higher in IgG4-RD patients with visceral involvements. These checkpoint molecules could be a potentially useful biomarker for IgG4-RD and for assessing the clinical phenotypes of IgG4-RD.

Comprehensive Gene Analysis of IgG4-Related Ophthalmic Disease Using RNA Sequencing

High-throughput RNA sequencing (RNA-seq) uses massive parallel sequencing technology, allowing the unbiased analysis of genome-wide transcription levels and tumor mutation status. Immunoglobulin G4-related ophthalmic disease (IgG4-ROD) is a fibroinflammatory disease characterized by the enlargement of the ocular adnexal tissues. We analyzed RNA expression levels via RNA-seq in the biopsy specimens of three patients diagnosed with IgG4-ROD. Mucosa-associated lymphoid tissue (MALT) lymphoma, reactive lymphoid hyperplasia (RLH), normal lacrimal gland tissue, and adjacent adipose tissue were used as the controls (n = 3 each). RNA-seq was performed using the NextSeq 500 system, and genes with |fold change| ≥ 2 and p < 0.05 relative to the controls were defined as differentially expressed genes (DEGs) in IgG4-ROD. To validate the results of RNA-seq, real-time polymerase chain reaction (PCR) was performed in 30 IgG4-ROD and 30 orbital MALT lymphoma tissue samples. RNA-seq identified 35 up-regulated genes, including matrix metallopeptidase 12 (MMP12) and secreted phosphoprotein 1 (SPP1), in IgG4-ROD tissues when compared to all the controls. Many pathways related to the immune system were included when compared to all the controls. Expressions of MMP12 and SPP1 in IgG4-ROD tissues were confirmed by real-time PCR and immunohistochemistry. In conclusion, we identified novel DEGs, including those associated with extracellular matrix degradation, fibrosis, and inflammation, in IgG4-ROD biopsy specimens. These data provide new insights into molecular pathogenetic mechanisms and may contribute to the development of new biomarkers for diagnosis and molecular targeted drugs.

Untypical autoimmune pancreatitis and pancreatic cancer: differential diagnosis experiences extracted from misdiagnose of two cases

BACKGROUND

Differentiation between pancreatic cancer (PC) and focal form of autoimmune pancreatitis (AIP) is very challenging, with similar clinical presentations, laboratory results and morphologic imagings of US, CT, EUS, MRI, ERCP, PET-CT. Even serum IgG4 and biopsy sometimes cannot give clear-cut differential accurate diagnostis. Considering the totally different management strategy of the two diseases, accurate diagnostic value is urgently needed to remind the clinicians of the rare diagnosis of untypical AIP among frequent PC-suspected patients.

RESULTS

We present 2 laparotomy cases of AIP that had a high similar characteristic to PC and retrospectively extracted the warning signs that may help select untypical AIP in PC-suspected patients.

CONCLUSIONS

We find that mild fluctuating jaundice with abdominal pain, young age, tumor marker of TPS, TPA and diverse results between variable radiological tests can help to differentiate AIP mass from PC, through retrospectively analyzing work-up process of AIP in two patients who underwent laparotomy for suspected PC.

TNF-α Suppresses Autophagic Flux in Acinar Cells in IgG4-Related Sialadenitis

IgG4-related sialadenitis (IgG4-RS) is a newly recognized immune-mediated systemic fibroinflammatory disease that affects salivary glands and leads to hyposalivation. Tumor necrosis factor-α (TNF-α) is a critical proinflammatory cytokine involved in several salivary gland disorders, but its role and mechanism regarding acinar cell injury in IgG4-RS are unknown. Here, we found that TNF-α level was significantly increased in serum and submandibular gland (SMG) of patients and that serum TNF-α level was negatively correlated with saliva flow rate. Ultrastructural observations of IgG4-RS SMGs revealed accumulation of large autophagic vacuoles, as well as dense fibrous bundles, decreased secretory granules, widened intercellular spaces, swollen mitochondria, and expanded endoplasmic reticulum. Expression levels of LC3 and p62 were both increased in patients' SMGs. TNF-α treatment led to elevated levels of LC3II and p62 in both SMG-C6 cells and cultured human SMG tissues but did not further increase their levels when combined with bafilomycin A1 treatment. Moreover, transfection of Ad-mCherry-GFP-LC3B in SMG-C6 cells confirmed the suppression of autophagic flux after TNF-α treatment. Immunofluorescence imaging revealed that costaining of LC3 and the lysosomal marker LAMP2 was significantly decreased in patients, TNF-α-treated SMG-C6 cells, and cultured human SMGs, indicating a reduction in autophagosome-lysosome fusion. Furthermore, the ratio of pro/mature cathepsin D was elevated in vivo, ex vivo, and in vitro. TNF-α also appeared to induce abnormal acidification of lysosomes in acinar cells, as assessed by lysosomal pH and LysoTracker DND-26 fluorescence intensity. In addition, TNF-α treatment induced transcription factor EB (TFEB) redistribution in SMG-C6 cells, which was consistent with the changes observed in IgG4-RS patients. TNF-α increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2, and inhibition of ERK1/2 by U0126 reversed TNF-α-induced TFEB redistribution, lysosomal dysfunction, and autophagic flux suppression. These findings suggest that TNF-α is a key cytokine related to acinar cell injury in IgG4-RS through ERK1/2-mediated autophagic flux suppression.