Roles of Regulatory T and B Cells in IgG4-Related Disease

Immune phenotype changes in IgG4-related disease: CD161 + Treg and Foxp3 + Treg

OBJECTIVE

We aimed to characterize the alterations in the immune phenotypes and explore the potential relevance to pathogenesis in IgG4-RD.

METHODS

Forty-two IgG4-RD patients and thirty-eight healthy controls were recruited in this study. Peripheral immunocompetent cells including T cells, CD4 + T cells, CD8 + T cells, B cells, NK cells CD4 + CD45RA + T cells (naïve T cells), CD4 + CD25 - / + Foxp3 - T cells (Teff), CD4 + CD25hiCD127lowCD161 + T cells (CD161 + Treg), CD4 + CD25hiFoxp3 + T cells (Foxp3 + Treg), CD4 + CD4RA-CXCR5 + PD1 + CCR7low T cells (pTfh), T helper (Th) 1, Th2, and Th17 before and after treatment were immunophenotyped by flow cytometry.

RESULTS

Compared with healthy controls, IgG4-RD patients showed higher proportions of NK (20.1% vs 13.6%, p < 0.01), Th1 (CD4 + IFN-γ + : 17.9% vs 14.2%, p = 0.061; TNF-α: 43.7% vs 36.7%, p < 0.05), Th2 (CD4 + IL-4 + : 2.4% vs 1.3%, p < 0.0001), CD161 + Treg (14.9% vs 11.6%, p < 0.01), pTfh (3.2% vs 2.4%, p < 0.05), and Foxp3 + Treg (8.3% vs 7.0%, p < 0.01) and lower proportions of B lymphocytes (8.4% vs 13.1%, p < 0.001), Teff (91.6% vs 92.6%, p < 0.01), and naïve Th cells (19.9% vs 32.1%, p < 0.01) before treatment. Foxp3 + Treg percentage decreased significantly after treatment (8.6% vs 6.9%, p < 0.05). Both serum C3 (r =  - 0.6374, p < 0.01) and C4 (r =  - 0.6174, p < 0.01) levels were in negative correlation with CD161 + Treg. The eosinophil percentage was positively correlated with Foxp3 + Treg (r = 0.5435, p < 0.05). Serum IgE level was positively correlated with Th2 (r = 0.5545, p < 0.05). There was a positive correlation between CD161 + Treg and pTfh (r = 0.4974, p < 0.05) while a negative correlation between Th2 and B cells (r =  - 0.4925, p < 0.05).

CONCLUSION

Immune phenotypes were altered in IgG4-RD. Treg/Teff balance was shifted toward Treg in IgG4-RD. CD161 + Treg was likely to be involved in the pathogenesis of IgG4-RD. Key Points •Immune phenotypes were altered in B cells, T cells, and NK cells in IgG4-RD. •Treg/Teff balance was shifted toward Treg in IgG4-RD. •CD161+ Treg maybe play a proinflammatory role in IgG4-RD.

IgG4-related disease with kidney and lymph nodes involvement: a case-based review

IgG4-related disease (IgG4-RD), a rare immune-mediated chronic fibro-inflammatory condition, has various initial symptoms, thus posing diagnostic and therapeutic challenges. Here, we report a case of IgG4-RD in a 35-year-old man with initial clinical symptoms of facial edema and recent onset of proteinuria. It took more than 1 year from the onset of clinical symptoms to diagnosis. Pathological examination of renal biopsy revealed significant renal interstitial lymphoid tissue hyperplasia simulating growth pattern of lymphoma. Immunohistochemical (IHC) staining results showed that CD4 + T lymphocyte hyperplasia was dominant. There was no significant deletion of CD2/CD3/CD5/CD7. No monoclone was detected in TCR gene rearrangement. IHC staining showed that the number of IgG4-positive cells was greater than 100/HPF. The ratio of IgG4/IgG was greater than 40%. Combined with clinically examinations, IgG4-related tubulointerstitial nephritis was considered. Further cervical lymph node biopsy results suggested IgG4-related lymphadenopathy. He received methylprednisolone 40 mg/day intravenously for 10 days, leading to normal results of laboratory tests and clinical manifestations. The patient had a good prognosis without recurrence during 14 months of follow-up. This case report can be used as a reference for early diagnosis and treatment of such patients in the future.

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.

Effects of Fibulin-5 Gene Silencing on Proliferation and Apoptosis of IgG4-ROD Lacrimal Gland Fibroblasts

Objective

This study is aimed at discussing the value of RNA interference technology on inhibiting lacrimal gland fibrosis in IgG4-related ocular disease (IgG4-ROD).

Methods

Six patients with IgG4-ROD who came to the hospital for surgical treatment from October 2018 to August 2019 were selected, and their diseased lacrimal glands were taken for primary cell culture and fibroblast identification. High efficiency and specificity small interference RNA (siRNA) plasmid vector was constructed, its inhibitory effect on fibroblast proliferation was determined by CCK-8 assay, and the appropriate concentration was selected as the siRNA concentration for subsequent experiments. RT-PCR and Western blot detected the relative expression levels of Fibulin-5 mRNA and protein in the cells 48 hours after transfection. The apoptosis rate of each group of cells at 24 hours, 48 hours, and 72 hours after transfection was detected by flow cytometry, and the proliferation and apoptosis of cells after silencing Fibulin-5 were analyzed and compared.

Results

24 hours after transfection, there was no significant difference in the proliferation rate among the four groups (P > 0.05); 48 hours and 72 hours after Fibulin-5 siRNA transfection, the proliferation activity of the transfected cells was significantly decreased compared with the 0 nM group, and the inhibitory effect of 75 nM siRNA was the strongest. The expression of Fibulin-5 mRNA and protein in the siRNA-transfected cells was significantly decreased compared with the blank and empty vector negative siRNA groups, and the difference was statistically significant (P < 0.05). The apoptosis rate of cells in the Fibulin-5 siRNA transfection group was significantly higher than that of cells in the blank and empty vector negative siRNA groups, and the difference was statistically significant (P < 0.05).

Conclusion

Fibulin-5 siRNA recombinant plasmid can significantly downregulate the mRNA and protein expressions of target gene Fibulin-5 and promote apoptosis after transfection into IgG4-ROD lacrimal gland fibroblasts. It is speculated that Fibulin-5 can be used as a target to effectively inhibit the fibrosis of lacrimal gland tissues by RNAi technique.

Gut microbiota: A target for prebiotics and probiotics in the intervention and therapy of food allergy

Food allergy has become a major public health problem all over the world. Evidence showed that allergic reactions induced by food proteins often lead to disturbances in the gut microbiota (symbiotic bacteria). Gut microbiota plays an important role in maintaining the balance between intestinal immune tolerance and allergic reactions. Dietary intervention has gradually become an important method for the prevention and treatment of allergic diseases, and changing the composition of gut microbiota through oral intake of prebiotics and probiotics may serve as a new effective adjuvant treatment measure for allergic diseases. In this paper, the main mechanism of food allergy based on intestinal immunity was described firstly. Then, the clinical and experimental evidence showed that different prebiotics and probiotics affect food allergy by changing the structure and composition of gut microbiota was summarized. Moreover, the molecular mechanism in which the gut microbiota and their metabolites may directly or indirectly regulate the immune system or intestinal epithelial barrier function to affect food immune tolerance of host were also reviewed to help in the development of food allergy prevention and treatment strategies based on prebiotics and probiotics.

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.

Clinical Characteristics of Patients With IgG4-Related Disease Complicated by Hypocomplementemia

Background

A proportion of patients with immunogloblin G (IgG) 4-related disease (IgG4-RD) have hypocomplementemia. We aimed to identify characteristics of such patients.

Methods

We analyzed the demographic and clinical data and complement levels of 85 patients with IgG4-RD. We defined hypocomplementemia as serum C3 and/or C4 levels below the lower limit of normal at diagnosis. We also compared the characteristics of patients with and without IgG4-RD.

Results

Thirty-two (38%) patients had hypocomplementemia at diagnosis. Patients with hypocomplementemia had more lymph node (p < 0.01), lung (p < 0.01), and kidney (p = 0.02) involvement and a higher IgG4-RD responder index than those without (p = 0.05). Additionally, patients with hypocomplementemia had significantly higher IgG (p < 0.01), IgG4 (p < 0.01), and soluble interleukin 2-receptor (sIL-2R) (p < 0.01) levels and total IgG minus IgG4 (p < 0.01). C3 and C4 levels negatively correlated with IgG, IgG4, and sIL-2R levels, total IgG minus IgG4, and number of IgG4-RD responder index: a measure of the disease activity in IgG4-RD. Patients with hypocomplementemia at diagnosis had a significantly higher frequency of relapse (p = 0.024), as determined using the log-rank test. A multivariate logistic regression analysis showed the presence of hypocomplementemia was independently associated with relapse (OR, 6.842; 95% confidence interval [95%CI], 1.684–27.79; p = 0.007).

Conclusions

Patients with IgG4-RD with hypocomplementemia have a more active clinical phenotype, suggesting contributions of the complement system in the pathophysiology of IgG4-RD.

Peripheral B-Cell Immunophenotyping Identifies Heterogeneity in IgG4-Related Disease

Objectives

To elucidate heterogeneity of IgG4-related disease (IgG4-RD) based on B cell immunophenotyping.

Methods

Immunophenotyping of 4 B-cell subsets in peripheral blood from patients with active IgG4-RD (aIgG4-RD, n=105) was performed using flow cytometry to get preliminary B-cell heterogeneity spectrum. Then 10 B-cell subsets were characterized in aIgG4-RD (n = 49), remissive IgG4-RD (rIgG4-RD, n = 49), and healthy controls (HCs, n = 47), followed by principal components analysis (PCA) and cluster analysis to distinguish B-cell immunophenotypes and classify IgG4-RD patients into subgroups.

Results

Cluster analysis identified two endotypes in 105 aIgG4-RD patients based on 4 B-cell subsets: Group1 with higher Breg and naive B cells (n = 48), and Group2 with higher plasmablasts and memory B cells (MBCs) (n = 57). PCA indicated that aIgG4-RD consisted of plasmablast-naive B cell and MBCs-Breg axes abnormalities. There was a negative relationship between naive B cells and disease activity. Both plasmablasts and MBCs were positively associated with serological biomarkers. Cluster analysis stratified aIgG4-RD patients into 3 subgroups based on 10 B-cell subsets: subgroup1 with low MBCs and normal Breg, subgroup2 with high MBCs and low Breg, and subgroup3 with high plasmablasts and low naive B cells. Patients in subroup2 and subgroup3 were more likely to be resistant to treatment.

Conclusion

Patients with aIgG4-RD can be divided into 3 subgroups based on B cell heterogeneity. The B cell immunophenotyping could help elucidate the pathogenesis of IgG4-RD, identify patients with potential refractory IgG4-RD, and provide important information for the development of new therapies.

Interleukin-35 Promotes Th9 Cell Differentiation in IgG4-Related Disorders: Experimental Data and Review of the Literature

IgG4-related disease (IgG4-RD) is characterized by intense infiltration of IgG4-positive plasma cells in affected organs. However, the mechanisms acting in the immune responses in IgG4-RD are not fully understood. The aim of this study was to dissect the mechanism underlying the immunoglobulin class switch in IgG4-RD by addressing the crosstalk between IL-35-producing and Th9 cells. The expression level of IL-35 was examined in plasma samples from patients with hepatobiliary and/or pancreatic manifestations of IgG4-RD. Our data demonstrate that IgG4-RD patients exhibit significantly high-level productions of IL-35 as compared to disease and healthy controls. We detected the two subunits of IL-35, EBI3 and IL-12p35, in the two major affected organs, liver and pancreatic tissue, from IgG4-RD. The EBI3- and IL-12p35-positive cells were significantly higher in affected organs in IgG4-RD as compared to disease controls. The colocalization of EBI3 with CD19 and CD38, markers for B cells, suggest the presence of IL-35-producing B cells in affected organs in IgG4-RD. The effects of IL-35 in Th9 differentiation and IL-9 in production of immunoglobulin were then assessed. Surprisingly, IL-35 treatment promoted naïve CD4 T cell differentiating towards Th9 cells through IRF4 signaling. As a consequence, IL-9 secreted by Th9 cells promoted the differentiation of plasma cells and production of IgG1 and IgG4, predominantly IgG4. In conclusion, our data demonstrate that IL-35 actively participates in the process of inflammation and plays an important role in Th9 differentiation resulting in an immunoglobulin class switch towards IgG4.

Immune Dysregulation in IgG4-Related Disease

Immunoglobin G₄-related disease (IgG₄-RD) is one of the newly discovered autoimmune diseases characterized by elevated serum IgG₄ concentrations and multi-organ fibrosis. Despite considerable research and recent advances in the identification of underlying immunological processes, the etiology of this disease is still not clear. Adaptive immune cells, including different types of T and B cells, and cytokines secreted by these cells play a vital role in the pathogenesis of IgG₄-RD. Antigen-presenting cells are stimulated by pathogens and, thus, contribute to the activation of naïve T cells and differentiation of different T cell subtypes, including helper T cells (Th1 and Th2), regulatory T cells, and T follicular helper cells. B cells are activated and transformed to plasma cells by T cell-secreted cytokines. Moreover, macrophages, and some important factors (TGF-β, etc.) promote target organ fibrosis. Understanding the role of these cells and cytokines implicated in the pathogenesis of IgG₄-RD will aid in developing strategies for future disease treatment and drug development. Here, we review the most recent insights on IgG₄-RD, focusing on immune dysregulation involved in the pathogenesis of this autoimmune condition.

Retroperitoneal Fibrosis Diagnosed as IgG4-related Disease after 35 Years

In 1982, we reported a case of retroperitoneal fibrosis (RPF) exhibiting various clinical manifestations. Our current understanding of immunoglobulin G4 (IgG4)-related disease led us to consider it as a possible diagnosis because all of the patient's clinical features could be explained by this disease entity. To confirm our hypothesis, were investigated the histopathological findings of resected specimens that had been stored for 35 years postoperatively. Typical pathological findings together with predominant IgG4⁺ plasma cell infiltration confirmed a potential diagnosis of IgG4-related RPF. Furthermore, we observed positive immunohistochemical staining for several molecules associated with T regulatory and T follicular helper cells.