Cutting Edge: A Critical Role of Lesional T Follicular Helper Cells in the Pathogenesis of IgG4-Related Disease.

IgG4-related disease (IgG4-RD) is a newly recognized systemic chronic fibroinflammatory disease. However, the pathogenesis of IgG4-RD remains unknown. To determine the pathophysiologic features of IgG4-RD, we examined T follicular helper (Tfh) cells in lesions and blood from patients with IgG4-RD. Patients with IgG4-related dacryoadenitis and sialadenitis (IgG4-DS) showed increased infiltration of Tfh cells highly expressing programmed death 1 and ICOS in submandibular glands. Tfh cells from IgG4-DS submandibular glands had higher expression of B cell lymphoma 6 and a greater capacity to help B cells produce IgG4 than did tonsillar Tfh cells. We also found that the percentage of programmed death 1hi circulating Tfh cells in IgG4-DS patients was higher than that in healthy volunteers and was well correlated with clinical parameters. Our findings indicate that anomalous Tfh cells in tissue lesions of IgG4-RD have features distinct from those in lymphoid counterparts or blood and potentially regulate local IgG4 production in IgG4-RD.

Loss of sorting nexin 5 stabilizes internalized growth factor receptors to promote thyroid cancer progression.

Thyroid carcinoma is the most common endocrine malignancy and its prevalence has recently been increasing worldwide. We previously reported that the level of sorting nexin 5 (Snx5), an endosomal translocator, is preferentially decreased during the progression of well-differentiated thyroid carcinoma into poorly differentiated carcinoma. To address the functional role of Snx5 in the development and progression of thyroid carcinoma, we established Snx5-deficient (Snx5-/- ) mice. In comparison to wild-type (Snx5+/+ ) mice, Snx5-/- mice showed enlarged thyroid glands that consisted of thyrocytes with large irregular-shaped vacuoles. Snx5-/- thyrocytes exhibited a higher growth potential and higher sensitivity to thyroid-stimulating hormone (TSH). A high content of early endosomes enriched with TSH receptors was found in Snx5-/- thyrocytes, suggesting that loss of Snx5 caused retention of the TSH receptor (TSHR) in response to TSH. Similar data were found for internalized EGF in primary thyrocytes. The increased TSH sensitivities in Snx5-/- thyrocytes were also confirmed by results showing that Snx5-/- mice steadily developed thyroid tumors with high metastatic potential under high TSH. Furthermore, a thyroid cancer model using carcinogen and an anti-thyroidal agent revealed that Snx5-/- mice developed metastasizing thyroid tumors with activation of MAP kinase and AKT pathways, which are postulated to be major pathways of malignant progression of human thyroid carcinoma. Our results suggest that thyrocytes require Snx5 to lessen tumorigenic signaling driven by TSH, which is a major risk factor for thyroid carcinoma. Copyright © 2017 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Keratinocytes in atopic dermatitis express abundant ΔNp73 regulating thymic stromal lymphopoietin production via NF-κB.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease that often cannot be completely controlled by modern medicine. Since multiple factors are intricately involved in the pathogenesis of AD, wide-ranging research is required for further advancement of AD treatment. Epidermal keratinocytes are the forefront to the external environment and play a pivotal role in the initiation of immune reaction against exogenous invasion. OBJECTIVE: Thymic stromal lymphopoietin (TSLP) is a keratinocyte-derived cytokine that induces differentiation and activation of type 2 helper T cells and innate lymphoid cells, cardinal effectors in pathophysiology of AD. We previously reported that ΔNp63, a p53-related molecule, regulates the expression of TSLP receptors and suggested the entity of a potential TSLP autocrine loop in the AD epidermis. In this study, we further explored the significance of p53 family transcription factors in TSLP production from human keratinocytes. METHOD: Expression profile of p73, a p53-related molecule, was evaluated in human AD tissue by immunohistochemistry. In addition, the function of p73 in producing TSLP was investigated with in vitro cultured keratinocytes via molecular biological analysis. RESULTS: ΔNp73 was abundantly expressed in the AD epidermis and increased the release of TSLP via NF-κB activation. Furthermore, the Toll-like receptor 3 signal enhanced ΔNp73 expression and thereby induced TSLP expression. CONCLUSION: Our results indicate that ΔNp73 is an additional participant in the mechanism of TSLP production. Amending the aberrant state of keratinocytes, represented by overexpression of ΔNp73, can be a novel therapeutic target of AD.

Lipid mediators foster the differentiation of T follicular helper cells.

Lipid mediators such as leukotrienes and lipoxines broadly regulate innate and acquired immunity, and their dysfunction causes various immune-mediated disorders. We previously reported a salient feature of arachidonate 5-lipoxyganase (Alox5), which is responsible for the production of such lipid mediators, in the regulation of high affinity antibodies in vivo. The aim of this study was to determine the functional significance of Alox5-related lipid mediators during the processes of acquired humoral responses. The results of in vitro experiments using lymphocytes in tonsils and blood specimens showed that lipoxin A4 (LXA4) and leukotriene B4 (LTB4) have the capacity to differentiate naïve CD4+ T cells into T follicular helper (Tfh) cells, which activate naïve B cells to form germinal centers. Such a function of LXA4 was further supported by results of in vitro studies using BML-111 and BOC-2, which are an agonist and an antagonist, respectively, of FPR2 of an LXA4-specific cell-surface receptor. The results suggest that such lipid mediators have a potential role in the development of lymphoid follicles through the regulation of Tfh cell differentiation.

Bob1 limits cellular frequency of T-follicular helper cells.

T follicular helper (Tfh) cells are involved in specific humoral immunity at initial and recall phases. The fact that the transcription repressors B-cell lymphoma-6 and Blimp-1 determine lineages of Tfh cells and other types of effector CD4(+) T cells, respectively, suggests that there are unique mechanisms to establish Tfh-cell identity. In this study, we found that Tfh cells preferentially express the transcriptional coactivator Bob1. Bob1 of Tfh cells was dispensable for the expression of B-cell lymphoma-6 and the functional property of the cells for B cell help. However, upon initial immunization of foreign antigens, the percentages of Tfh cells in Bob1(-/-) mice were much higher than those in wild-type (WT) mice. In addition, expansion of Tfh cells within Bob1(-/-) CD4(+) T cells transferred into WT mice revealed that the high frequency of Tfh cells was caused by a T-cell-intrinsic mechanism. These findings were further supported by the results of in vitro studies demonstrating that Bob1(-/-) Tfh cells had greater proliferative activity in response to stimuli by CD3/CD28 monoclonal antibody and were also refractory to CD3-induced cell death in comparison to WT Tfh cells. These results suggest that Tfh cells harbor a Bob1-related mechanism to restrict numerical frequency against stimulation of TCRs.

Expression and Localization of Human Defensins in Palatine Tonsils.

Defensins are small antimicrobial peptides and effector components of innate immune responses. Recent studies have shed light on their beneficial functions for the prevention of infection and potential for development of new drugs. Here, we showed the expression profiles of human defensins in palatine tonsils with 3 different diseases: tonsillar hypertrophy, recurrent tonsillitis and focal infection of the tonsil. RT-PCR analysis and immunofluorescence revealed that the expression of human α-defensin 4 and ß-defensin 3 (ß3) in palatine tonsils with tonsillar hypertrophy was lower than that in recurrent tonsillitis and focal infection of the tonsil, suggesting that chronic inflammation induces defensin expression. Interestingly, ß2 and ß3 mRNAs were specifically expressed by palatine tonsil tissues but not in human peripheral blood mononuclear cells and mucosa of the small intestine. Additionally, we observed that exposure to a Toll-like receptor 4 ligand, lipopolysaccharide, which is used as a bacterial infection model, increases the production of ß2 in culture supernatants from tonsillar epithelial cells in a dose-dependent manner. Taken together, these results indicate that ß2 produced by tonsillar epithelial cells plays an important role in the innate immune response for bacterial infections.

Studies of Tonsils in Basic and Clinical Perspectives: From the Past to the Future.

The tonsils are located at the entrance of the pharynx as a cardinal constituent of Waldeyer's ring, taking part not only in local immune responses, but also in systemic immunity. Functional deficits of tonsils primarily underlie the pathogenesis of various characteristic disorders, including tonsillar focal infections such as palmoplantar pustulosis and IgA nephropathy, in addition to the highly prevalent sleep disorder called obstructive sleep apnea syndrome. Although the mechanisms underlying these disorders remain unknown, the tonsils have long been postulated as a unique and enigmatic immune organ. Lymphoid cells and tissues from surgically resected tonsils are often employed to analyze the human immune response from a retrospective view. This approach has provided much new fundamental evidence for understanding innate and acquired immune responses, thereby facilitating further studies in the fields of mucosal immunity and specific humoral immunity originating in the germinal center. Future studies of the tonsils in basic and clinical research are expected to reveal the mechanisms of tonsil-related disorders as well as the nature of human immunity. In this review, which is primarily based on our original research over the past 3 decades, we summarize our findings and discuss the future prospects of studies focusing on the tonsils.

Role of Crosstalk between Epithelial and Immune Cells, the Epimmunome, in Allergic Rhinitis Pathogenesis.

Recently, the prevalence of allergic rhinitis has been dramatically increasing worldwide. As conventional therapies for allergic rhinitis, such as antihistamines, leukotriene receptor antagonists, nasal sprays and allergen immunotherapy, have limitations, the development of new drugs is required. Recent studies have revealed that epithelial cell-derived cytokines, including thymic stromal lymphopoietin, interleukin (IL)-25 and IL-33, are able to control immune cells, such as dendritic cells and T cells, thereby acting as 'master switches' in allergic disease. In addition, new roles have been identified for follicular helper T cells and regulatory B cells in allergic disease, and they are considered to be promising targets for new therapies. Thus, crosstalk between epithelial and immune cells, the epimmunome, underlies the pathogenesis of allergic rhinitis. Greater understanding of the epimmunome may lead to breakthroughs in the development of new treatments for allergic rhinitis and will help us cure many patients suffering from its severe symptoms in the future.

Clinical outcomes of tracheoesophageal diversion and laryngotracheal separation for aspiration in patients with severe motor and intellectual disability.

CONCLUSIONS: Tracheoesophageal diversion (TED) and laryngotracheal separation (LTS) can prevent aspiration pneumonia and improve the morbidity of patients with severe motor and intellectual disability (SMID). By improving hospitalization rates and care needs, the quality-of-life can be improved for the patients and their parents. OBJECTIVES: This study evaluated the clinical outcomes of TED and LTS in patients with intractable aspiration and SMID. METHODS: This study retrospectively reviewed patients with SMID and intractable aspiration pneumonia who underwent TED or LTS at the institution between January 2008 and January 2015. It assessed the frequency of sputum suctioning, the number of pre-operative and post-operative hospitalizations, the operative time, and complications. RESULTS: Forty patients were identified during the study period. After surgery, there were significant reductions in the frequency of secretion suctioning (from 165.0 times/day to 33.0 times/day) and the number of hospitalizations because of aspiration pneumonia (from 5.4 times/year to 0.2 times/year). A tracheocutaneous fistula occurred in one (2.5%) patient, and two (5.4%) patients developed tracheoinnominate artery fistulas. In the latter group, the innominate arteries were successfully ligated and endovascular embolization was performed.

Alteration of circulating type 2 follicular helper T cells and regulatory B cells underlies the comorbid association of allergic rhinitis with bronchial asthma.

Allergic rhinitis (AR), the most common allergic disorder of the airway, is often accompanied by bronchial asthma. However, little is known about the mechanism by which AR advances to AR comorbid with bronchial asthma (AR+Asthma). To determine the pathophysiologic features of AR and AR+Asthma, we examined subsets of follicular helper T (Tfh) cells and regulatory B (Breg) cells in peripheral blood from AR and AR+Asthma patients. The results showed polarization of Tfh2 cells within Tfh cell subsets in both AR and AR+Asthma cases. Interestingly, the %Breg cells in total B cells were decreased in AR cases and, more extensively, in AR+Asthma cases. Moreover, we found significant correlations of fractional exhaled nitric oxide and blood eosinophil levels with the index %Tfh2 cells per %Breg cells. Our findings indicate that relative decrease in Breg cells under the condition of Tfh2 cell skewing is a putative exaggerating factor of AR to bronchial asthma.

[Post-operative functional evaluation of accessory nerve reconstruction].

A nerve reconstruction was performed in 20 patients whose spinal accessory nerve was resected during total neck dissection. Re-anastomosis or a cable graft was performed between both cut ends of the accessory nerve in 14 patients (accessory nerve reconstruction group), and between the peripheral cut end of the accessory nerve and the central cut end of the cervical nerve (C2 or C3) in 6 patients (cervical/accessory nerve reconstruction group). There was no difference in the postoperative shoulder functions between the reconstruction groups, and both groups were significantly better than the group without reconstruction (n = 13), although they tended to be poorer than the nerve preservation group (n = 41).