Guanylate binding protein-1-mediated epithelial barrier in human salivary gland duct epithelium.

Guanylate-binding protein-1 (GBP-1) is an interferon-inducible large GTPase involved in the epithelial barrier at tight junctions. To investigate the role of GBP-1 in the epithelial barrier, primary human salivary gland duct epithelial cells were treated with the the proinflammatory cytokines IFNγ, IL-1ß, TNFα and the growth factor TGF-ß. Treatment with IFNγ, IL-1ß, or TNFα markedly enhanced GBP-1 and the epithelial barrier function, and induced not only CLDN-7 but also the tricellular tight junction molecule lipolysis-stimulated lipoprotein receptor (LSR). Knockdown of GBP-1 by its siRNA induced endocytosis of tight junction molecules, and prevented the increases of CLDN-7 and LSR with the upregulation of the epithelial barrier function induced by treatment with IFNγ or TNFα. Treatment with a PKCα inhibitor induced expression of GBP-1, CLDN-7 and LSR and enhanced the epithelial barrier function. In almost intact salivary gland ducts from patients with IgG4-related disease (IgG4-RD) indicated significant infiltration of IgG-positive plasma cells, expression of GBP-1, CLDN-7 and LSR was increased. These findings indicated that GBP-1 might play a crucial role in barrier function of normal human salivary gland duct epithelium and perform a preventive role in the duct epithelium of IgG4-RD disease.

Irsogladine maleate regulates gap junctional intercellular communication-dependent epithelial barrier in human nasal epithelial cells.

The airway epithelium of the human nasal mucosa acts as the first physical barrier that protects against inhaled substances and pathogens. Irsogladine maleate (IM) is an enhancer of gastric mucosal protective factors via upregulation of gap junctional intercellular communication (GJIC). GJIC is thought to participate in the formation of functional tight junctions. However, the effects of IM on GJIC and the epithelial barrier in human nasal epithelial cells (HNECs) remain unknown. To investigate the effects of IM on GJIC and the tight junctional barrier in HNECs, primary cultures of HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs) were treated with IM and the GJIC inhibitors oleamide and 18ß-GA. Some cells were pretreated with IM before treatment with TLR3 ligand poly(I:C) to examine whether IM prevented the changes via TLR3-mediated signal pathways. In hTERT-HNECs, GJIC blockers reduced the expression of tight junction molecules claudin-1, -4, -7, occludin, tricellulin, and JAM-A. IM induced GJIC activity and enhanced the expression of claudin-1, -4, and JAM-A at the protein and mRNA levels with an increase of barrier function. GJIC blockers prevented the increase of the tight junction proteins induced by IM. Furthermore, IM prevented the reduction of JAM-A but not induction of IL-8 and TNF-α induced by poly(I:C). In conclusion, IM can maintain the GJIC-dependent tight junctional barrier via regulation of GJIC in upper airway nasal epithelium. Therefore, it is possible that IM may be useful as a nasal spray to prevent the disruption of the epithelial barrier by viral infections and exposure to allergens in human nasal mucosa.

Clinical Evaluation of Sinonasal Lesions in Patients With Immunoglobulin G4-Related Disease.

OBJECTIVES: Immunoglobulin G4-related disease (IgG4-RD) is a systemic disease entity characterized by elevated serum IgG4 and extensive IgG4-positive plasma cell infiltration of various organs. Patients with IgG4-RD show nasal manifestations with chronic rhinosinusitis. The objective of this study was to evaluate the clinical characteristics of sinonasal lesions in patients with IgG4-RD. METHODS: We evaluated radiological findings of sinonasal lesions in 79 patients with IgG4-RD who were divided into 3 groups according to severity. We also compared serological findings, including serum IgG4 and IgE levels, and eosinophil counts. RESULTS: Rhinosinusitis was found in 41 patients (51.9%). Although there were no significant differences in the serum IgG4 and IgE levels of the groups, there was a significant increase in eosinophil counts (445 ± 311.9/mm³) in Group C. Furthermore, 14 of the 41 patients with rhinosinusitis (34.1%) showed improvement after prednisolone administration. Patients with IgG4-RD and serum eosinophilia tend to also have sinonasal lesions. CONCLUSIONS: Rhinosinusitis is common in patients with IgG4-RD, and its pathogenesis can be similar to eosinophilic chronic rhinosinusitis.

Pseudomonas aeruginosa elastase causes transient disruption of tight junctions and downregulation of PAR-2 in human nasal epithelial cells.

BACKGROUND: Pseudomonas aeruginosa causes chronic respiratory disease, and the elastase enzyme that it produces increases the permeability of airway epithelial cells owing to the disruption of tight junctions. P. aeruginosa is also implicated in prolonged chronic rhinosinusitis. However, the effects of P. aeruginosa elastase (PE) against the barrier formed by human nasal epithelial cells (HNECs) remain unknown. METHODS: To investigate the mechanisms involved in the disruption of tight junctions by PE in HNECs, primary cultures of HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs) were used. The hTERT-HNECs were pretreated with inhibitors of various signal transduction pathways, PKC, MAPK, p38MAPK, PI3K, JNK, NF-κB, EGF receptor, proteasome, COX1 and COX2 before treatment with PE. Some cells were pretreated with siRNA and agonist of protease activated receptor-2 (PAR-2) before treatment with PE. Expression and structures of tight junctions were determined by Western blotting, real-time PCR, immunostaining and freeze-fracture. Transepithelial electrical resistance (TER) was examined as the epithelial barrier function. RESULTS: PE treatment transiently disrupted the epithelial barrier and downregulated the transmembrane proteins claudin-1 and -4, occludin, and tricellulin, but not the scaffold PDZ-expression proteins ZO-1 and -2 and adherens junction proteins E-cadherin and ß-catenin. The transient downregulation of tight junction proteins was controlled via distinct signal transduction pathways such as the PKC, MAPK, PI3K, p38 MAPK, JNK, COX-1 and -2, and NF-κB pathways. Furthermore, treatment with PE transiently decreased PAR-2 expression, which also regulated the expression of the tight junction proteins. Treatment with a PAR-2 agonist prevented the downregulation of the tight junction proteins after PE treatment in HNECs. CONCLUSIONS: PE transiently disrupts tight junctions in HNECs and downregulates PAR-2. The transient disruption of tight junctions by PE might occur repeatedly during chronic rhinosinusitis.

Regulation of tight junctions by sex hormones in normal human endometrial epithelial cells and uterus cancer cell line Sawano.

The number of patients with uterine endometrial carcinoma, the cause of which involves sex hormones, has recently been growing rapidly because of increases in life expectancy and obesity. Tight junction proteins claudin-3 and -4 are receptors of Clostridium perfringens enterotoxin (CPE) and increase during endometrial carcinogenesis. In the present study of normal human endometrial epithelial (HEE) cells and the uterus cancer cell line Sawano, we investigate changes in the expression of tight junction proteins including claudin-3 and -4, the fence and barrier functions of the tight junction and the cytotoxic effects of CPE by sex hormones. In primary cultured HEE cells, treatment with progesterone (P4) but not estradiol (E2), induced claudin-1, -3, -4 and -7 and occludin, together with the downregulation of the barrier function but not the fence function. In Sawano cells, claudin-3 and -4 were upregulated by E2 but not by P4, together with a disruption of both the barrier and fence function. In primary cultured HEE cells, claudin-3 and -4 were localized at the apicalmost regions (tight junction areas) and no cytotoxicity of CPE was observed. In Sawano cells, claudin-3 and -4 were found not only in the apicalmost regions but also at the basolateral membrane and the cytotoxicity of CPE was enhanced by E2. Thus, tight junctions are physiological regulated by sex hormones in normal HEE cells during the menstrual cycle suggesting that safer and more effective therapeutic methods targeting claudins in uterine cancer can be developed.

Marked induction of matrix metalloproteinase-10 by respiratory syncytial virus infection in human nasal epithelial cells.

Respiratory syncytial virus (RSV) is an important pathogen of bronchiolitis, asthma, and severe lower respiratory tract disease in infants and young children. Matrix metalloproteinases (MMPs) play key roles in viral infection, inflammation and remodeling of the airway. However, the roles and regulation of MMPs in human nasal epithelial cells (HNECs) after RSV infection remain unclear. To investigate the regulation of MMP induced after RSV infection in HNECs, an RSV-infected model of HNECs in vitro was used. It was found that mRNA of MMP-10 was markedly increased in HNECs after RSV infection, together with induction of mRNAs of MMP-1, -7, -9, and -19. The amount of MMP-10 released from HNECs was also increased in a time-dependent manner after RSV infection as was that of chemokine RANTES. The upregulation of MMP-10 in HNECs after RSV infection was prevented by inhibitors of NF-κB and pan-PKC with inhibition of RSV replication, whereas it was prevented by inhibitors of JAK/STAT, MAPK, and EGF receptors without inhibition of RSV replication. In lung tissue of an infant with severe RSV infection in which a few RSV antibody-positive macrophages were observed, MMP-10 was expressed at the apical side of the bronchial epithelial cells and alveolar epithelial cells. In conclusion, MMP-10 induced by RSV infection in HNECs is regulated via distinct signal transduction pathways with or without relation to RSV replication. MMP-10 may play an important role in the pathogenesis of RSV diseases and it has the potential to be a novel marker and therapeutic target for RSV infection.

Humulone suppresses replication of respiratory syncytial virus and release of IL-8 and RANTES in normal human nasal epithelial cells.

Respiratory syncytial virus (RSV) is the major infectious agent causing serious respiratory tract inflammation in infants and young children. However, an effective vaccine and anti-viral therapy for RSV infection have not yet been developed. Hop-derived bitter acids have potent pharmacological effects on inflammation. Therefore, we investigated the effects of humulone, which is the main constituent of hop bitter acids, on the replication of RSV and release of the proinflammatory cytokine IL-8 and chemokine RANTES in RSV-infected human nasal epithelial cells (HNECs). We found that humulone prevented the expression of RSV/G-protein, formation of virus filaments and release of IL-8 and RANTES in a dose-dependent manner in RSV-infected HNECs. These findings suggest that humulone has protective effects against the replication of RSV, the virus assembly and the inflammatory responses in HNECs and that it is a useful biological product for the prevention and therapy for RSV infection.

Epidermal growth factor modulates claudins and tight junctional functions in ovarian cancer cell lines.

Ovarian adenocarcinomas, like human ovarian surface epithelial cells, form functional tight junctions. Tight junction molecules claudin-3 and claudin-4, which are the receptors of Clostridium perfringens enterotoxin (CPE), are abnormally upregulated in epithelial ovarian cancers of all subtypes including, mucinous cystadenocarcinoma and serous cystadenocarcinoma. Clostridium perfringens enterotoxin may be a novel tumor-targeted therapy for ovarian cancers. In epithelial ovarian cancers, overexpression of epidermal growth factor receptor has been observed and the exogenous ligand EGF induces epithelial-mesenchymal transition in ovarian surface epithelium. Epidermal growth factor (EGF) signaling modulates expression of claudins with changes of fence and barrier functions in various cell types. However, the regulation of tight junctions by EGF in ovarian cancers remains unclear. In the present study, to investigate the mechanisms of the regulation of tight junctions in ovarian cancers, ovarian cancer cell lines mucinous cystadenocarcinoma (MCAS) and serous cystadenocarcinoma (HUOA) were treated with EGF. Epidermal growth factor downregulated claudin-3 in MCAS and claudin-4 in HUOA by inducing degradation of the proteins with changes in structures and functions of tight junctions via the MEK/ERK or PI3K/Akt signaling pathway. In addition, in HUOA but not MCAS, EGF downregulated the cytotoxic effect of CPE via claudin-4. Thus, there were different mechanisms for regulation of claudins by EGF between subtypes of epithelial ovarian cancer cells in vitro. These results indicate that EGF may affect claudins and tight junctional functions in ovarian cancer cells during cancer progression.

Telefitting of Nucleus Cochlear Implants: A Feasibility Study.

Purpose This study aims to describe the recommended equipment and procedures required for successful telefitting, based on our experience, document and evaluate patient satisfaction with telefitting, and assess its clinical usefulness and address the existing issues. Method Twenty (seven children and 13 adults) individuals who lived far from cochlear implant (CI) centers and who were Nucleus CI users underwent conventional face-to-face fitting and telefitting. We examined the participants' subjective satisfaction and cost and time saved with the telefitting experience. Results The telefitting sessions lasted for an average of 16 min. Majority of the participants responded positively to the telefitting experience. Eighty percent (16/20) of the participants were satisfied with the new procedure, and 85% of them agreed to use telefitting again. Conclusions The results of our feasibility study suggest that telefitting was well received by CI users and is a viable alternative to local MAPping, even in young children with CIs. Although there are some limitations in terms of adaptability, telefitting could be an effective means of delivering CI service to remote locations.

HDAC inhibitors suppress the proliferation, migration and invasiveness of human head and neck squamous cell carcinoma cells via p63­mediated tight junction molecules and p21­mediated growth arrest.

In human head and neck squamous cell carcinoma (HNSCC), the invasion and metastatic properties of cancer cells are promoted by junctional adhesion molecule­A (JAM­A) and claudin­1; these are epithelial tight junction molecules regulated by histone deacetylases (HDACs) and transcription factor p63. HDAC expression is reportedly upregulated in HNSCC, and HDAC inhibitors suppress cancer cell proliferation by initiating proliferative arrest or apoptosis. However, little is known of the anti­cancer mechanisms of HDAC inhibitors in HNSCC. Thus, in the present study, the HNSCC Detroit 562 cell line and primary cultured HNSCC cells were treated with HDAC inhibitors to investigate their effects in HNSCC. Higher expression of p63, HDAC1, JAM­A and claudin­1 was observed in HNSCC tissues compared with the adjacent dysplastic regions. In Detroit 562 cells, treatment with trichostatin A (TSA), an inhibitor of HDAC1 and 6, downregulated the expression of p63, JAM­A and claudin­1, and upregulated that of acetylated tubulin; conversely, p63 knockdown resulted in the downregulation of JAM­A and claudin­1. Collectively, inhibiting HDAC suppressed the migration and invasiveness of cancer cells. In addition, treatment with TSA suppressed cancer cell proliferation via G2/M arrest, as well as upregulating p21 and downregulating cyclin D1 expression. TSA also downregulated the expression of epidermal growth factor receptor (EGFR) and phospho­ERK1/2. p63 knockdown and treatment with an EGFR inhibitor induced G1 arrest and downregulated EGFR and phospho­ERK1/2 levels, respectively. HDAC inhibition also suppressed the migration and invasiveness of primary cultured HNSCC cells. Collectively, the results of the present study indicate that HDAC inhibitors suppress the proliferation, migration and invasiveness of HNSCC by downregulating the p63­mediated tight junction molecules JAM­A and claudin­1, and inducing p63 or p21­mediated growth arrest.

Mechanism of fibrogenesis in submandibular glands in patients with IgG4-RD.

The aim of this study was to investigate the mechanisms driving fibrosis in the submandibular glands (SMG) of patients with IgG4-related disease (IgG4-RD). Immunohistochemistry showed that many fibroblast-like cells expressing IL-6, IL-18, TSLP, IL-33, and MMP1 were present in SMG from the affected patients. SMG fibroblasts were derived from patients with or without IgG4-RD and were cultured in vitro. Expression of IL-6, IL-18, TSLP, IL-33 and MMP1, the secretion of IL-6 and G2/M phase were upregulated in the fibroblasts from the affected patients. By treatment with inflammatory cytokines IL-1ß, TNFα or TGF-ß after treatment with or without the NF-κB inhibitor curcumin, curucumin blocked the production and secretion of IL-6 upregulated by IL-1ß, TNFα, or TNFα/TGF-ß in all fibroblasts. Wnt1-inducible signaling protein 1 (WISP1), which can enhance fibroblasts proliferation, was also more abundantly expressed in affected fibroblasts, while treatment with IL-6 induced WISP1, treatment with WISP1 increased the G2/M phase, and curucumin inhibited WISP1 induced by TNFα/TGF-ß in unaffected fibroblasts. IL-33 in affected fibroblasts was induced by IL-1ß, TNFα, or TNFα/TGF-ß, while the effect of IL-1ß or TNFα/TGF-ß was blocked by curcumin. These results suggest fibrosis in the SMG of affected patients is closely linked to the proliferation of fibroblasts following induction of IL-6 and WISP1 by inflammatory cytokines. The Th2 cytokines TSLP and IL-33 are also upregulated in affected SMG, and thus may cause chronic inflammation and IgG4 accumulation.

Regulation of claudin-4 via p63 in human epithelial cells.

P63 is a regulator of cell-cell junction complexes in the epidermis. Claudin-4 is regulated via various factors in normal epithelial cells and diseases. We found that claudin-4 was directly regulated via p63 (TAp63 and ΔNp63) in human keratinocytes and nasal epithelial cells. In the epidermis of atopic dermatitis (AD), which contains ΔNp63-deficient keratinocytes, high expression of claudin-4 was observed. In primary keratinocytes, downregulation of ΔNp63 by treatment with short interfering RNA (siRNA)-p63 induced claudin-4 expression. In nasal epithelial cells in the context of rhinitis or nasal polyps, upregulation of TAp63 and downregulation of claudin-4 were observed. In primary nasal epithelial cells transfected with the human telomerase reverse transcriptase gene, knockdown of p63 by siRNAs induced claudin-4 expression. Taken together, these findings indicate that p63 is a negative regulator of claudin-4 expression. Understanding the regulation of claudin-4 via p63 in human epithelial cells may be important for developing therapies for allergies and drug delivery systems.

Clinicopathological analysis of salivary gland tissue from patients with IgG4-related disease.

Conclusion The diagnosis of immunoglobulin G4-related disease (IgG4-RD) should be based on the morphology of tissue biopsy, and this study recommends a submandibular gland (SMG) biopsy for accurate diagnosis and to exclude malignant disease. Objective To clarify which type of biopsy specimen (SMG or labial salivary gland [LSG]) should be taken from patients with IgG4-RD. Methods This study included 33 patients with IgG4-RD (21 women; 12 men) who were subjected to both SMG and LSG biopsies at Sapporo Medical University between 2011-2015. Tissues obtained from the SMG and LSG specimens were evaluated. Results All SMG specimens satisfied the diagnostic criteria for IgG4-RD, whereas 19 (57.6%) LSG specimens satisfied the diagnostic criteria for IgG4-RD. Histological evaluation showed fibrosis in all the SMG specimens and in eight LSG specimens (24.2%). Obliterative phlebitis was seen in nine SMG specimens (27.3%), but it was absent in all the LSG specimens.

Pneumolabyrinth with Labyrinthitis as the Suspected Cause.

Pneumolabyrinth is a rare condition with air bubbles existing in the vestibule and/or cochlea. We report a case of pneumolabyrinth without trauma that was suspected to be caused by labyrinthitis. A 65-year-old man presented with vertigo and hearing loss in the left ear after catching a cold. Computed tomography performed after there had been no improvement in the patient's symptoms showed the presence of air bubbles in the vestibule, semicircular canals and cochlea. The patient was transferred to our hospital with suspected perilymphatic fistula. Bacterial infection was suspected after the laboratory tests had indicated a severe inflammatory response, and the patient was treated with antibiotics. However, no bacteria were detected in a bacterial culture of the otorrhea. An exploratory tympanotomy was performed to improve the patient's staggering gait and to examine the middle ear, with no obvious fistula being observed. Subsequent fenestration of the round window revealed a white mass that appeared to contain bacteria which was collected from the cochlea and submitted for analysis and bacterial culture. However, no bacteria were detected and the mass contained white blood cells. We suspected pneumolabyrinth following labyrinth infection. However, the cause of air bubble formation remains unclear and needs to be validated with further research.

Junctional Adhesion Molecule-A in Head and Neck Squamous Cell Carcinoma.

Junctional adhesion molecule-A (JAM-A), which belongs to the IgG superfamily, is one of the tight junction molecules. JAM-A is dysregulated in various cancers and is closely associated with the invasion and metastasis of cancers such as breast cancer, lung cancer and pancreatic cancer. In the present study, we found a high expression of JAM-A in head and neck squamous cell carcinoma (HNSCC) as well as ß-catenin in immunohistochemistry. The expression of JAM-A and ß-catenin was of a low level in differentiation-induced cancer pearl regions of HNSCC. Real-time PCR showed the high expression of JAM-A mRNA through all differentiated stages (well, moderate, poor) of HNSCC. When we performed ELISA using the serum of HNSCC patients to measure plasma-soluble JAM-A, it was found to be higher in HNSCC patients than healthy subjects. These results indicate that JAM-A is one of the malignancy markers of HNSCC as well as ß-catenin in histopathology, and the plasma-soluble JAM-A may contribute to a serum diagnosis of HNSCC. JAM-A is a promising molecular target for diagnosis and therapy in HNSCC.

Radiological Assessment of the Anatomy of Frontal Recess Cells and the Anterior Ethmoidal Artery.

It is necessary for the surgeon to be familiar with frontal recess anatomy during an endoscopic approach to the frontal sinuses. The aim of this study was to evaluate the prevalence of frontal recess cells in Japanese adults as well as the association between the frontal recess and the location of the anterior ethmoidal artery (AEA). The frontal recess cells and the AEAs were retrospectively evaluated in CT scans of the nasal and paranasal sinuses for 89 patients. The prevalence of agger nasi cells was 90.7%. The frequency of frontal cell types 1, 2, 3 and 4 was 28.8, 0.6, 2.6 and 0%, respectively. Suprabullar cells (SBCs) and frontal bullar cells (FBCs) were identified in 78/96 sides (81.3%) and 24/96 sides (24%), respectively. The prevalence of the medial group of frontal recess cells (interfrontal sinus septal cells) was 12.4%. In 42/61 sides (68.9%), the AEAs were located within the posterior margin of the SBCs or the FBCs. Therefore, SBCs, FBCs and the vertical portion of the middle turbinate are reliable landmarks for the identification of AEAs.

A Novel Drug Delivery System for the Human Nasal Epithelium.

The epithelium of upper respiratory tissues such as the human nasal mucosa forms a continuous barrier via tight junctions (TJs). The development of a drug delivery system for use across the nasal mucosa is being reconsidered. In intranasal administration across the nasal mucosa, the paracellular pathway regulated by TJs is extremely important. It is known that the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) binds the TJ protein claudin and disrupts the tight junctional barrier without inducing a cytotoxic effect. We investigated the effects of C-CPE mutants on the function of TJs of human nasal epithelial cells (HNECs) and on the permeability of human recombinant insulin across HNECs treated with C-CPE 194 and C-CPE m19. We recently reported that C-CPE mutants 194 and m19 can regulate the permeability of insulin across HNECs via the MAPK pathway and may play a crucial role in therapy for various diseases via direct intranasal insulin administration. On the other hand, microRNAs (miRNAs) are known to regulate the expression of TJs as direct or indirect targets in genes to maintain barrier function. We investigated the effects of miRNAs on the epithelial barrier of HNECs and found that miRNA-146a plays crucial roles in the maintenance of the TJ barrier and innate immune response against invading pathogens. This chapter reviews a novel drug delivery system across the nasal mucosa from the point of view of the epithelial barrier function.

The Behavior and Role of Lipolysis-stimulated Lipoprotein Receptor, a Component of Tricellular Tight Junctions, in Head and Neck Squamous Cell Carcinomas.

BACKGROUND/AIM: Lipolysis-stimulated lipoprotein receptor (LSR) knockdown has also been reported to increase the motility and invasiveness of certain cancer cells. Here, we describe, for the first time, the behavior and role of LSR in head and neck squamous cell carcinoma (HNSCC) in vivo and in vitro. MATERIALS AND METHODS: Samples of HNSCC, normal palatine tonsils, the pharynx carcinoma cell line Detroit562 and primary cultured HNSCC were characterized by immunostaining, western blot, real-time polymerase chain reaction (PCR), Matrigel invasion and proliferation assays. RESULTS: Protein and mRNA of LSR were strongly expressed, as well as claudin-1 in HNSCC tissues than in normal tissues, especially in invasive tissues. Knock-down of LSR and claudin-1 (CLDN-1), but not tricellulin (TRIC) by siRNAs, markedly induced invasiveness of Detroit562 cells and primary cultured HNSCC. LSR inhibited the development and progression of HNSCC. CONCLUSION: LSR is a potential target for new forms of head and neck cancer therapy.

Interferon-gamma increased epithelial barrier function via upregulating claudin-7 expression in human submandibular gland duct epithelium.

Tight junctions (TJs) are necessary for salivary gland function and may serve as indicators of salivary gland epithelial dysfunction. IgG4-related disease (IgG4-RD) is a newly recognized fibro-inflammatory condition which disrupts the TJ associated epithelial barrier. The salivary glands are one of the most frequently involved organs in IgG4-RD, however, changes of the TJ associated epithelial barrier in salivary gland duct epithelium is poorly understood. Here, we investigated the regulation and function of TJs in human submandibular gland ductal epithelial cells (HSDECs) in normal and IgG4-RD. We examined submandibular gland (SMG) tissue from eight control individuals and 22 patients with IgG4-RD and established an HSDEC culture system. Immunohistochemistry, immunocytochemistry, western blotting, and measurement of transepithelial electrical resistance (TER) were performed. Claudin-4, claudin-7, occludin, and JAM-A were expressed at the apical side of the duct epithelium in submandibular gland (SMG) tissue and at the cell borders in HSDECs of normal and IgG4-RD. The expression and distribution of TJs in SMG tissue were not different in control individuals and patients with IgG4-RD in vivo and in vitro. Although interferon-gamma (IFNγ) generally disrupts the integrity and function of TJs, as manifested by decreased epithelial barrier function, IFNγ markedly increased the epithelial barrier function of HSDECs via upregulation of claudin-7 expression in HSDECs from patients with IgG4-RD. This is the first report showing an IFNγ-dependent increase in epithelial barrier function in the salivary gland duct epithelium. Our results provide insights into the functional significance of TJs in salivary gland duct epithelium in physiological and pathological conditions, including IgG4-RD.