Wnt/ß-catenin-YAP axis in the pathogenesis of primary intraosseous carcinoma NOS, deriving from odontogenic keratocyst.

Odontogenic tumors (OGTs), which originate from cells of odontogenic apparatus and their remnants, are rare entities. Primary intraosseous carcinoma NOS (PIOC), is one of the OGTs, but it is even rarer and has a worse prognosis. The precise characteristics of PIOC, especially in immunohistochemical features and its pathogenesis, remain unclear. We characterized a case of PIOC arising from the left mandible, in which histopathological findings showed a transition from the odontogenic keratocyst to the carcinoma. Remarkably, the tumor lesion of this PIOC prominently exhibits malignant attributes, including invasive growth of carcinoma cell infiltration into the bone tissue, an elevated Ki-67 index, and lower signal for CK13 and higher signal for CK17 compared with the non-tumor region, histopathologically and immunohistopathologically. Further immunohistochemical analyses demonstrated increased expression of ADP-ribosylation factor (ARF)-like 4c (ARL4C) (accompanying expression of ß-catenin in the nucleus) and yes-associated protein (YAP) in the tumor lesion. On the other hand, YAP was expressed and the expression of ARL4C was hardly detected in the non-tumor region. In addition, quantitative RT-PCR analysis using RNAs and dot blot analysis using genomic DNA showed the activation of Wnt/ß-catenin signaling and epigenetic alterations, such as an increase of 5mC levels and a decrease of 5hmC levels, in the tumor lesion. A DNA microarray and a gene set enrichment analysis demonstrated that various types of intracellular signaling would be activated and several kinds of cellular functions would be altered in the pathogenesis of PIOC. Experiments with the GSK-3 inhibitor revealed that ß-catenin pathway increased not only mRNA levels of ankyrin repeat domain1 (ANKRD1) but also protein levels of YAP and transcriptional co-activator with PDZ-binding motif (TAZ) in oral squamous cell carcinoma cell lines. These results suggested that further activation of YAP signaling by Wnt/ß-catenin signaling may be associated with the pathogenesis of PIOC deriving from odontogenic keratocyst in which YAP signaling is activated.

Extracellular vesicles of iPS cells highly capable of producing HGF and TGF-ß1 can attenuate Sjögren's syndrome via innate immunity regulation.

Previous studies have demonstrated that extracellular vesicles (EVs) from dental pulp stem cells (DPSCs), which release abundant hepatocyte growth factor (HGF) and transforming growth factor-ß1 (TGF-ß1), contribute to the pathogenesis of Sjögren's syndrome (SS). However, depending on the condition of DPSCs, this effect is often not achieved. In this study, we established induced pluripotent stem (iPS) cells highly capable of releasing HGF and TGF-ß1 and iPS cells barely capable of releasing them, and administered each EV to SS model mice to see if there was a difference in therapeutic effect. EVs were collected from each iPS cell and their characteristics and shapes were examined. When they were administered to SS model mice, the EVs from iPS cells with higher concentrations of HGF and TGF-ß1 showed significantly reduced inflammatory cell infiltration in salivary gland tissues, increased saliva volume, and decreased anti-SS-A and anti-SS-B antibodies. A comprehensive search of microRNA arrays for differences among those EVs revealed that EVs from iPS cells with higher concentrations of HGF and TGF-ß1 contained more of the let-7 family. Thereafter, we examined the expression of toll-like receptors (TLRs), which are said to be regulated by the let-7 family, by qPCR, and found decreased TLR4 expression. Focusing on MAPK, a downstream signaling pathway, we examined cytokine concentrations in mouse macrophage culture supernatants and Western blotting of murine splenic tissues and found higher concentrations of anti-inflammatory cytokines in the EVs-treated group and decreased TLR4, NF-κB and phosphorylation (p)-p-38 MAPK expression by Western blotting. Alternatively, p-Smad2/3 was upregulated in the EVs-treated group. Our findings suggest that the let-7 family in EVs may suppress the expression of TLR4 and NF-κB, which may be involved in the suppression of MAPK-mediated pro-inflammatory cytokine production.

Expansion of CD4+ cytotoxic T lymphocytes with specific gene expression patterns may contribute to suppression of tumor immunity in oral squamous cell carcinoma: single-cell analysis and in vitro experiments.

Background: Cancer immunotherapy targeting CD8+ T cells has made remarkable progress, even for oral squamous cell carcinoma (OSCC), a heterogeneous epithelial tumor without a substantial increase in the overall survival rate over the past decade. However, the therapeutic effects remain limited due to therapy resistance. Thus, a more comprehensive understanding of the roles of CD4+ T cells and B cells is crucial for more robust development of cancer immunotherapy. Methods: In this study, we examined immune responses and effector functions of CD4+ T cells, CD8+ T cells and B cells infiltrating in OSCC lesions using single-cell RNA sequencing analysis, T cell receptor (TCR) and B cell receptor (BCR) repertoire sequencing analysis, and multi-color immunofluorescence staining. Finally, two Kaplan-Meier curves and several Cox proportional hazards models were constructed for the survival analysis. Results: We observed expansion of CD4+ cytotoxic T lymphocytes (CTLs) expressing granzymes, which are reported to induce cell apoptosis, with a unique gene expression patterns. CD4+ CTLs also expressed CXCL13, which is a B cell chemoattractant. Cell-cell communication analysis and multi-color immunofluorescence staining demonstrated potential interactions between CD4+ CTLs and B cells, particularly IgD- CD27- double negative (DN) B cells. Expansion of CD4+ CTLs, DN B cells, and their contacts has been reported in T and B cell-activated diseases, including IgG4-related disease and COVID-19. Notably, we observed upregulation of several inhibitory receptor genes including CTLA-4 in CD4+ CTLs, which possibly dampened T and B cell activity. We next demonstrated comprehensive delineation of the potential for CD8+ T cell differentiation towards dysfunctional states. Furthermore, prognostic analysis revealed unfavorable outcomes of patients with a high proportion of CD4+ CTLs in OSCC lesions. Conclusion: Our study provides a dynamic landscape of lymphocytes and demonstrates a systemic investigation of CD4+ CTL effects infiltrating into OSCC lesions, which may share some pathogenesis reported in severe T and B cell-activated diseases such as autoimmune and infectious diseases.

Toll-like receptor 9-positive plasmacytoid dendritic cells promote Th17 immune responses in oral lichen planus stimulated by epithelium-derived cathepsin K.

Oral lichen planus (OLP) is a chronic inflammatory disease associated with T cell infiltration. The crosstalk between oral epithelium and mucosal T cells was considered to be crucial in the pathogenesis of OLP. Here, we selectively extracted the normal epithelium (NE) and lesional epithelium (LE) of buccal mucosa specimens from three patients with OLP by laser capture microdissection due to identify the pathogenic factors. Cathepsin K (CTSK) was identified as one of common upregulated genes in the LE by DNA microarray. Immunohistochemically, CTSK was distinctly detected in and around the LE, while it was rarely seen in the NE. Recent studies showed that CTSK enhanced Toll-like receptor 9 (TLR9) signaling in antigen-presenting cells, leading to Th17 cell differentiation. TLR9 expression mainly co-localized with CD123+ plasmacytoid dendritic cells (pDCs). The number of RORγt-positive cells correlated with that of CTSK-positive cells in OLP tissues. CD123+ pDCs induced the production of Th17-related cytokines (IL-6, IL-23, and TGF-ß) upon stimulation with TLR9 agonist CpG DNA. Moreover, single cell RNA-sequencing analysis revealed that TLR9-positive pDCs enhanced in genes associated with Th17 cell differentiation in comparison with TLR9-negative pDCs. CTSK could induce Th17-related production of CD123+ pDCs via TLR9 signaling to promote the pathogenesis of OLP.

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.

Id4 modulates salivary gland homeostasis and its expression is downregulated in IgG4-related disease via miR-486-5p.

Salivary glands are physiologically orchestrated by the coordinated balance between cell differentiation, proliferation, apoptosis, and interactions between epithelial, mesenchymal endothelial, and neuronal cells, and they are frequent sites of manifestations of Sjögren's syndrome (SS) or IgG4-related disease (IgG4-RD). However, little is known about salivary gland homeostasis and its involvement in those diseases. Inhibitor of DNA binding/differentiation 4 (Id4) is an Id protein involved in the transcriptional control of many biological events, including differentiation. Studies of Id4-deficient mice revealed that Id4-deficient submandibular glands were smaller and exhibited accelerated differentiation, compared with those from wild-type littermates. In addition, dry mouth symptoms and Th17 expansion in splenocytes were also observed in the absence of Id4. Furthermore, Id4 levels in the salivary glands of patients with IgG4-RD, but not SS, were significantly decreased compared with those of healthy controls. miRNA-mRNA integrated analysis demonstrated that miR-486-5p was upregulated in IgG4-RD patients and that it might regulate Id4 in the lesion sites. Together, these results provide evidence for the inhibitory role of Id4 in salivary differentiation, and a critical association between Id4 downregulation and IgG4-RD.

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

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

Lipomatous mixed tumor of the skin with cystic formation affecting the upper lip: A case report.

Mixed tumor of the skin (MTS) is a rare neoplasm derived from the sweat glands with a reported frequency of 0.01-0.098% among all primary skin tumors. MTS often occurs in the head and neck region and is characterized by a mixture of epithelial, myoepithelial and stromal components. MTS also shows various morphological patterns, thus the presence of variants with rare components and its rarity make the clinical diagnosis even more difficult. A 47-year-old man was referred due to a painless, slowly growing, exophytic swelling intracutaneous mass of the upper lip. Magnetic resonance imaging revealed that the mass was a solid tumor with a fatty component in the proximal portion, while the distal portion was cystic and possibly contained highly viscous fluid. The mass was located between the skin and the orbicularis oris muscle in the upper lip. Excisional biopsy was performed and the lesion showed two intriguing features: A tumor with extensive lipomatous stroma and some large cysts. It was histopathologically diagnosed as lipomatous MTS with cystic formation in the upper lip. No evident signs of recurrence were observed during follow-up. The present report describes this case and includes a brief literature review of reported cases in the lip, since MTS can be confused with various skin lesions in clinical settings due to this rarity. Recognition by clinicians of different variants of MTSs, including the present case, is important for preventing erroneous diagnosis and treatment.

The Therapeutic Potential of Secreted Factors from Dental Pulp Stem Cells for Various Diseases.

An alternative source of mesenchymal stem cells has recently been discovered: dental pulp stem cells (DPSCs), including deciduous teeth, which can thus comprise potential tools for regenerative medicine. DPSCs derive from the neural crest and are normally implicated in dentin homeostasis. The clinical application of mesenchymal stem cells (MSCs) involving DPSCs contains various limitations, such as high cost, low safety, and cell handling issues, as well as invasive sample collection procedures. Although MSCs implantation offers favorable outcomes on specific diseases, implanted MSCs cannot survive for a long period. It is thus considered that their mediated mechanism of action involves paracrine effects. It has been recently reported that secreted molecules in DPSCs-conditioned media (DPSC-CM) contain various trophic factors and cytokines and that DPSC-CM are effective in models of various diseases. In the current study, we focus on the characteristics of DPSC-CM and their therapeutic potential against various disorders.

Investigation of IgG4-positive cells in idiopathic multicentric Castleman disease and validation of the 2020 exclusion criteria for IgG4-related disease.

Patients with plasma cell type idiopathic multicentric Castleman disease (PC-iMCD) often show elevated serum IgG4 levels and IgG4-positive cell infiltration in tissues due to overproduction of interleukin-6, and may meet the diagnostic criteria for IgG4-related disease (IgG4-RD). Although PC-iMCD has been listed as a major exclusion disease for IgG4-RD, distinguishing between these diseases is challenging due to a lack of highly specific diagnostic biomarkers. In 2020, we proposed exclusion criteria of IgG4-RD mimickers. In this paper, we validated the accuracy of the criteria in excluding one of the mimickers, PC-iMCD, from IgG4-RD. Validation was performed on 57 PC-iMCD patients (39 presenting lymph node lesions and 19 with lung lesions) and 29 IgG4-RD patients (22 presenting lymph node lesions and seven with lung lesions). According to our results, 20.5% of the PC-iMCD patients with lymph node lesions and 42.1% of those with lung lesions met the diagnostic criteria for IgG4-RD. All these patients with PC-iMCD were excluded from a diagnosis of IgG4-RD by the proposed criteria. Additionally, 6.9% of IgG4-RD patients met the exclusion criteria. Thus, if the exclusion criteria are met, diagnosis should be made based on a combination of findings including organ distribution of disease, response to steroid therapy, and other pathological findings.

CD163+ M2 Macrophages Promote Fibrosis in IgG4-Related Disease Via Toll-like Receptor 7/Interleukin-1 Receptor-Associated Kinase 4/NF-κB Signaling.

OBJECTIVE: IgG4-related disease (IgG4-RD) is a fibro-inflammatory condition that can affect multiple organs. We previously demonstrated that TLR7-transgenic C57BL/6 mice showed elevated serum IgG1 levels and inflammation with fibrosis in the salivary glands (SGs), lungs, and pancreas. Moreover, we observed extensive Toll-like receptor 7 (TLR-7)-positive CD163+ M2 macrophage infiltration in SGs from IgG4-RD patients. We undertook this study to examine the fibrotic mechanism via the TLR-7 pathway. METHODS: Gene expression in SGs from human TLR7-transgenic mice and IgG4-RD patients was analyzed using DNA microarrays. We extracted the common up-regulated TLR-7-related genes in SGs from TLR7-transgenic mice and IgG4-RD patients. Finally, we investigated the interaction between CD163+ M2 macrophages and fibroblasts before and after stimulation with the TLR-7 agonist loxoribine. RESULTS: In TLR7-transgenic mice and IgG4-RD patients, IRAK3 and IRAK4 were significantly overexpressed. Real-time polymerase chain reaction validated the up-regulation of only IRAK4 in IgG4-RD patients compared with the other groups (P < 0.05). Interleukin-1 receptor-associated kinase 4 (IRAK4) was strongly detected in and around germinal centers in SGs from patients with IgG4-related dacryoadenitis and sialadenitis alone. Double immunofluorescence staining showed that IRAK4-positive cells were mainly colocalized with CD163+ M2 macrophages in SGs (P < 0.05). After stimulation with loxoribine, CD163+ M2 macrophages exhibited significantly enhanced expression of IRAK4 and NF-κB and increased supernatant concentrations of fibrotic cytokines. Finally, we confirmed that the number of fibroblasts was increased by culture with the supernatant of CD163+ M2 macrophages following stimulation with loxoribine (P < 0.05). CONCLUSION: CD163+ M2 macrophages promote fibrosis in IgG4-RD by increasing the production of fibrotic cytokines via TLR-7/IRAK4/NF-κB signaling.

Oral Squamous Cell Carcinoma Contributes to Differentiation of Monocyte-Derived Tumor-Associated Macrophages via PAI-1 and IL-8 Production.

Tumor-associated macrophages (TAMs) promote cancer cell proliferation and metastasis, as well as anti-tumor immune suppression. Recent studies have shown that tumors enhance the recruitment and differentiation of TAMs, but the detailed mechanisms have not been clarified. We thus examined the influence of cancer cells on the differentiation of monocytes to TAM subsets, including CD163+, CD204+, and CD206+ cells, in oral squamous cell carcinoma (OSCC) using immunohistochemistry, flow cytometry, and a cytokine array. Furthermore, we investigated the effect of OSCC cells (HSC-2, SQUU-A, and SQUU-B cells) on the differentiation of purified CD14+ cells to TAM subsets. The localization patterns of CD163+, CD204+, and CD206+ in OSCC sections were quite different. The expression of CD206 on CD14+ cells was significantly increased after the co-culture with OSCC cell lines, while the expressions of CD163 and CD204 on CD14+ cells showed no change. High concentrations of plasminogen activator inhibitor-1 (PAI-1) and interleukin-8 (IL-8) were detected in the conditioned medium of OSCC cell lines. PAI-1 and IL-8 stimulated CD14+ cells to express CD206. Moreover, there were positive correlations among the numbers of CD206+, PAI-1+, and IL-8+ cells in OSCC sections. These results suggest that PAI-1 and IL-8 produced by OSCC contribute to the differentiation of monocytes to CD206+ TAMs.

Dental pulp-derived stem cell-conditioned media attenuates secondary Sjögren's syndrome via suppression of inflammatory cytokines in the submandibular glands.

INTRODUCTION: Sjögren's syndrome (SS) is a chronic inflammatory autoimmune disease, which affects the exocrine glands. Its primary symptoms are decreased moisture in the mouth and eyes. Therapies are limited to treatment with steroids, which has unpleasant side effects, so new treatments would be beneficial. One possibility might be stem cells, such as bone marrow mesenchymal stem cells (BMMSCs) or dental pulp-derived stem cells (DPSCs); these have been reported to exert immunomodulatory effects on activated lymphoid cells. This study aimed to evaluate the effects of conditioned media from DPSCs (DPSC-CM) or BMMSCs (BMMSC-CM) on salivary functions in SS. METHODS: Cytokine array analysis was performed to assess the types of cytokines present in the media. DPSC-CM or BMMSC-CM was administered in an SS mouse model. Histological analysis of the salivary glands was performed, and gene expression levels of inflammatory and anti-inflammatory cytokines in the submandibular glands (SMGs) were evaluated. RESULTS: DPSC-CM contained more anti-inflammatory factors than BMMSC-CM. The mice that were given DPSC-CM had a lower number of inflammation sites in the SMGs than those in the other experimental groups, and their salivary flow rate increased. The expression levels of interleukin (IL)-10 and transforming growth factor-ß1 increased in the DPSC-CM group, while those of Il-4, Il-6, and Il-17a decreased. The mice that received DPSC-CM showed a significantly increased percentage of regulatory T cells and a significantly decreased percentage of type T helper 17 cells compared to other groups. CONCLUSIONS: These results indicate that DPSC-CM could be an effective therapy for SS-induced hyposalivation, since it decreases the number of inflammatory cytokines and regulates the local inflammatory microenvironment in the SMGs.

Secreted factors from dental pulp stem cells improve Sjögren's syndrome via regulatory T cell-mediated immunosuppression.

BACKGROUND: Sjögren's syndrome (SS) is a chronic autoimmune disease primarily characterized by inflammation in the salivary and lacrimal glands. Activated T cells contribute to disease pathogenesis by producing proinflammatory cytokines, which leads to a positive feedback loop establishment. The study aimed to evaluate the effects of secreted factors derived from dental pulp stem cells (DPSCs) or bone marrow mesenchymal stem cells (BMMSCs) on hyposalivation in SS and to investigate the mechanism involved. METHODS: Eighty percent confluent stem cells were replenished with serum-free Dulbecco's modified Eagle's medium and incubated for 48 h; following which, conditioned media from DPSCs (DPSC-CM) and BMMSCs (BMMSC-CM) were collected. Cytokine array analysis was performed to assess the types of cytokines present in the media. Flow cytometric analysis was performed to evaluate the number of activated T cells cultured in DPSC-CM or BMMSC-CM. Subsequently, DPSC-CM or BMMSC-CM was administered to an SS mouse model. The mice were categorized into the following groups (n = 6 each): non-treatment, Dulbecco's modified Eagle's medium (-), BMMSC-CM, and DPSC-CM. Histological analysis of the salivary glands was performed. The gene and protein expression levels of cytokines associated with T helper subsets in the submandibular glands (SMGs) were evaluated. RESULTS: DPSC-CM contained more secreted factors with tissue-regenerating mechanisms, such as cell proliferation, anti-inflammatory effects, and immunomodulatory effects. DPSC-CM was more effective in suppressing the activated T cells than other groups in the flow cytometric analysis. The stimulated salivary flow rate increased in SS mice with DPSC-CM compared with that in the other groups. In addition, the number of inflammation sites in SMGs of the mice administered with DPSC-CM was lower than that in the other groups. The expression levels of interleukin (Il)-10 and transforming growth factor-ß1 were upregulated in the DPSC-CM group, whereas those of Il-4 and Il-17a were downregulated. The DPSC-CM-administered group presented with a significantly increased percentage of regulatory T (Treg) cells and a significantly decreased percentage of type 17 Th (Th17) cells compared with the other groups. CONCLUSIONS: These results indicated that DPSC-CM ameliorated SS by promoting Treg cell differentiation and inhibiting Th17 cell differentiation in the mouse spleen.

CD4+ and CD8+ cytotoxic T lymphocytes may induce mesenchymal cell apoptosis in IgG4-related disease.

BACKGROUND: IgG4-related disease (IgG4-RD) is an immune-mediated fibrotic disorder that has been linked to CD4+ cytotoxic T lymphocytes (CD4+CTLs). The effector phenotype of CD4+CTLs and the relevance of both CD8+ cytotoxic T lymphocytes (CD8+CTLs) and apoptotic cell death remain undefined in IgG4-RD. OBJECTIVE: We sought to define CD4+CTL heterogeneity, characterize the CD8+CTL response in the blood and in lesions, and determine whether enhanced apoptosis may contribute to the pathogenesis of IgG4-RD. METHODS: Blood analyses were undertaken using flow cytometry, cell sorting, transcriptomic analyses at the population and single-cell levels, and next-generation sequencing for the TCR repertoire. Tissues were interrogated using multicolor immunofluorescence. Results were correlated with clinical data. RESULTS: We establish that among circulating CD4+CTLs in IgG4-RD, CD27loCD28loCD57hi cells are the dominant effector subset, exhibit marked clonal expansion, and differentially express genes relevant to cytotoxicity, activation, and enhanced metabolism. We also observed prominent infiltration of granzyme A-expressing CD8+CTLs in disease tissues and clonal expansion in the blood of effector/memory CD8+ T cells with an activated and cytotoxic phenotype. Tissue studies revealed an abundance of cells undergoing apoptotic cell death disproportionately involving nonimmune, nonendothelial cells of mesenchymal origin. Apoptotic cells showed significant upregulation of HLA-DR. CONCLUSIONS: CD4+CTLs and CD8+CTLs may induce apoptotic cell death in tissues of patients with IgG4-RD with preferential targeting of nonendothelial, nonimmune cells of mesenchymal origin.

Association of circulating SLAMF7+Tfh1 cells with IgG4 levels in patients with IgG4-related disease.

BACKGROUND: Follicular helper CD4+ T (Tfh) cells have a critical role in IgG4 production by B cells in IgG4-related disease (IgG4-RD). Recent studies including ours showed that SLAMF7+CD4+ T cells are an important pathological driver of IgG4-RD. In this study, we have sought to elucidate a relationship between helper CD4+ T (Th), particularly Tfh, cells and SLAMF7+ CD4+ T cells in IgG4-RD. RESULTS: The patients with IgG4-RD enrolled in this study were aged 66 ± 12 years and their titers of serum IgG4 were 372 ± 336 mg/dl. Th1 cells, activated circulating Tfh1 (cTfh1), and activated cTfh2 cells increased in IgG4-RD. SLAMF7 was mainly expressed on Th1 and cTfh1, but not cTfh2, cells in the patients. SLAMF7+ cTfh1 cells were PD-1/CD28 double-positive, whereas SLAMF7+ Th1 cells were CD28 negative. Positive correlations were noted between serum IgG4 levels and the number of activated cTfh2 cells and SLAMF7+ cTfh1 cells, but not SLAMF7+ Th1 cells. Intriguingly, among cTfh1 cells, activated SLAMF7+ cTfh1 cells were high producers of IL-10 along with IL-21. Blimp-1, but not Bcl-6, mRNA was expressed at high levels in activated SLAMF7+ cTfh1 cells. In addition to CD4+ T cells, the frequency of SLAMF7+ fraction was higher in memory B cells than naïve B cells in patients with IgG4RD. Finally, upon stimulation via B-cell receptor and CD40, Tfh1-associated cytokines, IL-21 and IFN-γ, most significantly induced SLAMF7 expression in memory B cells. CONCLUSIONS: Together, these results suggest that circulating SLAMF7+ Tfh1 cells, along with Tfh2 cells, play a pathologic role in IgG4 production in IgG4-RD.

Review of a novel disease entity, immunoglobulin G4-related disease.

Immunoglobulin G4 (IgG4)-related dacryoadenitis and sialoadenitis (IgG4-DS) are part of a multiorgan fibroinflammatory condition of unknown etiology termed IgG4-related disease (IgG4-RD), which has been recognized as a single diagnostic entity for less than 15 years. Histopathologic examination is critical for diagnosis of IgG4-RD. CD4+ T and B cells, including IgG4-expressing plasma cells, constitute the major inflammatory cell populations in IgG4-RD and are thought to cause organ damage and tissue fibrosis. Patients with IgG4-RD who have active, untreated disease exhibit significant increase of IgG4-secreting plasmablasts in the blood. Considerable insight into the immunologic mechanisms of IgG4-RD has been achieved in the last decade using novel molecular biology approaches, including next-generation and single-cell RNA sequencing. Exploring the interactions between CD4+ T cells and B lineage cells is critical for understanding the pathophysiology of IgG4-RD. Establishment of pathogenic T cell clones and identification of antigens specific to these clones constitutes the first steps in determining the pathogenesis of the disease. Herein, the clinical features and mechanistic insights regarding pathogenesis of IgG4-RD were reviewed.

Activated M2 Macrophages Contribute to the Pathogenesis of IgG4-Related Disease via Toll-like Receptor 7/Interleukin-33 Signaling.

OBJECTIVE: IgG4-related disease (IgG4-RD) is a unique inflammatory disorder in which Th2 cytokines promote IgG4 production. In addition, recent studies have implicated the Toll-like receptor (TLR) pathway. This study was undertaken to examine the expression of TLRs in salivary glands (SGs) from patients with IgG4-RD. METHODS: SGs from 15 patients with IgG4-RD, 15 patients with Sjögren's syndrome (SS), 10 patients with chronic sialadenitis, and 10 healthy controls were examined histologically. TLR family gene expression (TLR-1 through TLR-10) was analyzed by DNA microarray in the submandibular glands (SMGs). Up-regulation of TLRs was confirmed in SGs from patients with IgG4-RD. Finally, the phenotype of human TLR-7 (huTLR-7)-transgenic C57BL/6 mice was assessed before and after stimulation with TLR agonist. RESULTS: In patients with IgG4-RD, TLR-4, TLR-7, TLR-8, and TLR-9 were overexpressed. Polymerase chain reaction validated the up-regulation of TLR-7 in IgG4-RD compared with the other groups. Immunohistochemical analysis confirmed strong infiltration of TLR-7-positive cells in the SGs of patients with IgG4-RD. Double immunohistochemical staining showed that TLR-7 expression colocalized with CD163+ M2 macrophages. After in vitro stimulation with a TLR-7 agonist, CD163+ M2 macrophages produced higher levels of interleukin-33 (IL-33), which is a Th2-activating cytokine. In huTLR-7-transgenic mice, the focus and fibrosis scores in SMGs, pancreas, and lungs were significantly higher than those in wild-type mice (P < 0.05). Moreover, the concentration of serum IgG, IgG1, and IL-33 in huTLR-7-transgenic mice was distinctly increased upon stimulation with a TLR-7 agonist (P < 0.05). CONCLUSION: TLR-7-expressing M2 macrophages may promote the activation of Th2 immune responses via IL-33 secretion in IgG4-RD.

The diagnostic utility of submandibular gland sonography and labial salivary gland biopsy in IgG4-related dacryoadenitis and sialadenitis: Its potential application to the diagnostic criteria.

Objectives: In this study, we investigated the diagnostic utility of submandibular gland (SMG) sonography and labial salivary gland (LSG) biopsy as a less invasive procedure for diagnosing IgG4-related dacryoadenitis and sialadenitis (IgG4-DS)Methods: Sixty-eight patients with suspected IgG4-DS by presenting swelling of elevated serum IgG (>1747 mg/dl) and/or swelling glands underwent SMG sonography, LSG biopsy and measurement for serum IgG4. SMG sonographic diagnosis was determined by the following characteristic changes; 'hypoechoic areas of a nodal pattern with high vascularity' and/or 'hypoechoic areas of a reticular pattern in the superficial part'.Results: Thirty-one patients were diagnosed with IgG4-DS, 5 with IgG4-RD unaccompanied by lacrimal and salivary gland lesions, 28 with Sjögren's syndrome, and 4 with malignant lymphoma. The sensitivity, specificity, and accuracy of SMG sonography and LSG biopsy were 100%, 83.8%, 91.2% and 64.5%, 73.8%, 75.0%, respectively. Moreover, those of SMG sonography and LSG biopsy combined with serum IgG4 concentration (>135 mg/dl) were 100%, 94.6%, 97.1% and 64.5%, 91.9%, 79.4%, respectively.Conclusion: LSG biopsy needs to be extremely careful to diagnose IgG4-DS because of its low sensitivity. SMG sonography is sufficient for the diagnosis of IgG4-DS, especially when combined with serologic analysis. Thus, SMG sonography could adapt to the diagnostic criteria of IgG4-DS as a non-invasive method.

Upregulation and pathogenic roles of CCL18-CCR8 axis in IgG4-related disease.

Objectives: To determine the protein expression level, expressing cell types, and pathogenic roles of chemokine (C-C motif) ligand 18 (CCL18) and its receptor chemokine (C-C motif) receptor 8 (CCR8) in affected tissues of patients with IgG4-related disease (IgG4-RD).Methods: The protein expression levels of CCL18 in labial salivary glands (LSGs) assessed by immunofluorescence (IF) staining were compared among patients with IgG4-RD (n = 3), primary Sjögren's syndrome (pSS; n = 4), and control subjects (n = 5). CCL18 expression levels in macrophages, CD11c+ cells, B cells, and plasmacytes in LSGs were examined by double IF staining. The protein expression levels of CCR8 and expressing cells (T, B cells, and plasmacytes) in LSGs were also compared among patients with IgG4-RD, pSS, and control subjects by double IF staining. The effects of the CCL18-CCR8 axis on total IgG, IgG2, and IgG4 production by peripheral blood mononuclear cells (PBMCs) stimulated with CD40L, IL-4, IL-10, and IL-21 were examined by in vitro assays.Results: CCL18 was specifically upregulated in LSGs of patients with IgG4-RD, compared with only a few cells in pSS patients and none of the controls. The numbers of CCL18-producing macrophages, CD11c+ cells, and plasmacytes in LSGs were significantly higher in IgG4-RD patients than in pSS patients and control (p < .05, each). Many T and B cells and some plasmacytes expressed CCR8 in LSGs of IgG4-RD and pSS patients. CCL18 specifically enhanced IgG4 production by stimulated PBMCs.Conclusion: CCL18-CCR8 axis was upregulated in LSGs of patients with IgG4-RD, suggesting possible roles of this axis in the pathogenesis of IgG4-RD.Key messagesThe CCL18-CCR8 axis in labial salivary glands (LSGs) and lacrimal glands of IgG4-RD patients was specifically upregulated compared with primary Sjögren's syndrome and control subjects.This axis might be a potentially novel therapeutic target in IgG4-RD, based on its important etiopathogenic roles, such as chemotaxis of various cells, induction of fibrosis, and enhancement of IgG4 production.