Takuya Kakuki

Poly(I:C) induced microRNA-146a regulates epithelial barrier and secretion of proinflammatory cytokines in human nasal epithelial cells

Human nasal epithelial cells (HNECs) are important in the tight junctional barrier and innate immune defense protecting against pathogens invading via Toll-like receptors (TLRs). MicroRNAs (miRNAs) regulate expression of tight junctions as direct or indirect targeting genes and maintain the barrier function. However, the roles of miRNAs in the epithelial barrier of HNECs via TLRs remain unknown. In the present study, to investigate the effects of miRNAs on the epithelial barrier of HNECs via TLRs, primary cultured HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs), were treated with the TLR3 ligand poly(I:C) and miRNA array analysis was performed. In the miRNA array of the cells treated with poly(I:C), upregulation of miR-187, -146a, -574, -4274, -4433, -4455 and -4750, and downregulation of miR-4785 by more than twofold compared to the control were observed. When control HNECs were treated with mimics and inhibitors of these miRNAs, an miR-146a mimic induced expression of tight junction proteins claudin-1, occludin and JAM-A together with an increase of the epithelial barrier function. The poly(I:C)-induced miR-146a was regulated via the distinct TLR3-mediated signal pathways PI3K, JNK and NF-κB. Furthermore, the miR-146a mimic prevented downregulation of claudin-1 and JAM-A and the secretion of proinflammatory cytokines IL-8 and TNF-α induced by poly(I:C) by targeting TRAF6. These findings indicate that, in HNECs, miRNA-146a plays crucial roles in maintenance of the tight junction barrier and innate immune defense protecting against invading pathogens.

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.

Claudin-binder C-CPE mutants enhance permeability of insulin across human nasal epithelial cells

Abstract Objective: Intranasal insulin administration has therapeutic potential for Alzheimers disease and in intranasal administration across the nasal mucosa, the paracellular pathway regulated by tight junctions is important. The C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE) binds the tight junction protein claudin and disrupts the tight junctional barrier without a cytotoxic effect. The C-CPE mutant called C-CPE 194 binds only to claudin-4, whereas the C-CPE 194 mutant called C-CPE m19 binds not only to claudin-4 but also to claudin-1. Methods: In the present study, to investigate the effects of C-CPE mutants on the tight junctional functions of human nasal epithelial cells (HNECs) and on the permeability of human recombinant insulin across the cells, HNECs were treated with C-CPE 194 and C-CPE m19. Results: C-CPE 194 and C-CPE m19 disrupted the barrier and fence functions without changes in expression of claudin-1, -4, -7, and occludin or cytotoxicity, whereas they transiently increased the activity of ERK1/2 phosphorylation. The disruption of the barrier function caused by C-CPE 194 and C-CPE m19 was prevented by pretreatment with the MAPKK inhibitor U0126. Furthermore, C-CPE 194 and C-CPE m19 significantly enhanced the permeability of human recombinant insulin across HNECs and the permeability was also inhibited by U0126. Conclusion: These findings suggest 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 the diseases such as Alzheimers disease via the direct intranasal insulin administration.

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.

Clarithromycin prevents human respiratory syncytial virus-induced airway epithelial responses by modulating activation of interferon regulatory factor-3.

Macrolide antibiotics exert immunomodulatory activity by reducing pro-inflammatory cytokine production by airway epithelial cells, fibroblasts, vascular endothelial cells, and immune cells. However, the underlying mechanism of action remains unclear. Here, we examined the effect of clarithromycin (CAM) on pro-inflammatory cytokine production, including interferons (IFNs), by primary human nasal epithelial cells and lung epithelial cell lines (A549 and BEAS-2B cells) after stimulation by Toll-like receptor (TLR) and RIG-I-like receptor (RLR) agonists and after infection by human respiratory syncytial virus (RSV). CAM treatment led to a significant reduction in poly I:C- and RSV-mediated IL-8, CCL5, IFN-β and -λ production. Furthermore, IFN-β promoter activity (activated by poly I:C and RSV infection) was significantly reduced after treatment with CAM. CAM also inhibited IRF-3 dimerization and subsequent translocation to the nucleus. We conclude that CAM acts a crucial modulator of the innate immune response, particularly IFN production, by modulating IRF-3 dimerization and subsequent translocation to the nucleus of airway epithelial cells. This newly identified immunomodulatory action of CAM will facilitate the discovery of new macrolides with an anti-inflammatory role.

Dysregulation of junctional adhesion molecule-A via p63/GATA-3 in head and neck squamous cell carcinoma

Junctional adhesion molecule-A (JAM-A), which belongs to the IgG superfamily, is a tight junction molecule associated with epithelial and endothelial barrier function. Overexpression of JAM-A is also closely associated with invasion and metastasis of cancers such as breast cancer, lung cancer and pancreatic cancer. However, little is known about the mechanism in overexpression of JAM-A in head and neck squamous cell carcinoma (HNSCC). In the present study, we found high expression of JAM-A at the protein and mRNA levels in HNSCC tissues, including those of the oropharynx, larynx, and hypopharynx, together with high protein expression of β-catenin, p63, ΔNp63 and GATA-3. Furthermore, in ELISA, a significant increase of soluble JAM-A in the sera of HNSCC patients was observed compared to healthy subjects. Knockdown of JAM-A by siRNA inhibited cell proliferation, invasion and migration in the HNSCC cell line Detroit562 in vitro. JAM-A expression in Detroit562 was increased via a distinct signal transduction pathway including NF-κB. Expression of JAM-A, β-catenin, p63 and ΔNp63 in Detroit562 was decreased under hypoxia. Knockdown of p63, ΔNp63 or GATA-3 by siRNAs reduced JAM-A expression in Detroit562. In primary cultured HNSCC cells in which CK7, p63, ΔNp63 and GATA-3 were detected, JAM-A expression was decreased by knockdown of p63 or ΔNp63. These results indicate that JAM-A is a biomarker of malignancy in HNSCC and that plasma soluble JAM-A may contribute to serum-based diagnosis of HNSCC. The mechanism of dysregulation of JAM-A via p63/GATA-3 is important in possible molecular targeted therapy for HNSCC.

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.

Loss of tricellular tight junction protein LSR promotes cell invasion and migration via upregulation of TEAD1/AREG in human endometrial cancer.

Lipolysis-stimulated lipoprotein receptor (LSR) is a unique molecule of tricellular contacts of normal and cancer cells. We investigated how the loss of LSR induced cell migration, invasion and proliferation in endometrial cancer cell line Sawano. mRNAs of amphiregulin (AREG) and TEA domain family member 1 (TEAD1) were markedly upregulated by siRNA-LSR. In endometrial cancer tissues, downregulation of LSR and upregulation of AREG were observed together with malignancy, and Yes-associated protein (YAP) was present in the nuclei. siRNA-AREG prevented the cell migration and invasion induced by siRNA-LSR, whereas treatment with AREG induced cell migration and invasion. LSR was colocalized with TRIC, angiomotin (AMOT), Merlin and phosphorylated YAP (pYAP). siRNA-LSR increased expression of pYAP and decreased that of AMOT and Merlin. siRNA-YAP prevented expression of the mRNAs of AREG and TEAD1, and the cell migration and invasion induced by siRNA-LSR. Treatment with dobutamine and 2-deoxy-D-glucose and glucose starvation induced the pYAP expression and prevented the cell migration and invasion induced by siRNA-LSR. siRNA-AMOT decreased the Merlin expression and prevented the cell migration and invasion induced by siRNA-LSR. The loss of LSR promoted cell invasion and migration via upregulation of TEAD1/AREG dependent on YAP/pYAP and AMOT/Merlin in human endometrial cancer cells.

The role of transcriptional factor p63 in regulation of epithelial barrier and ciliogenesis of human nasal epithelial cells

Disruption of nasal epithelial tight junctions (TJs) and ciliary dysfunction are found in patients with chronic rhinosinusitis (CRS) and nasal polyps (NPs), along with an increase of p63-positive basal cells and histone deacetylase (HDAC) activity. To investigate these mechanisms, primary cultures of HNECs transfected with human telomerase reverse transcriptase (hTERT-HNECs) were transfected with siRNAs of TAp63 and ΔNp63, treated with the NF-kB inhibitor curucumin and inhibitors of HDACs, and infected with respiratory syncytial virus (RSV). In TERT-HNECs, knockdown of p63 by siRNAs of TAp63 and ΔNp63, induced claudin-1 and -4 with Sp1 activity and enhanced barrier and fence functions. The knockdown of p63 enhanced the number of microvilli with the presence of cilia-like structures. Treatment with curcumin and inhibitors of HDACs, or infection with RSV prevented expression of p63 with an increase of claudin-4 and the number of microvilli. The knockdown or downregulation of p63 inhibited phospho-p38MAPK, and the p38MAPK inhibitor downregulated p63 and upregulated the barrier function. Thus, epithelial barrier and ciliogenesis of nasal epithelium are regulated in a p63-negative manner in normal and upper airway diseases. Understanding of the regulation of p63/p38 MAPK/NF-κB may be important in the therapy for airway allergy and its drug delivery system.

Histone deacetylase inhibition prevents cell death induced by loss of tricellular tight junction proteins in temperature-sensitive mouse cochlear cells

Tricellular tight junctions (tTJs) are specialized structures that occur where the corners of three cells meet to seal adjacent intercellular space. The molecular components of tTJs include tricellulin (TRIC) and lipolysis-stimulated lipoprotein receptor (LSR) which recruits TRIC, are required for normal hearing. Although loss of TRIC causes hearing loss with degeneration of cochlear cells, the detailed mechanisms remains unclear. In the present study, by using temperature-sensitive mouse cochlear cells, US/VOT-E36 cell line, we investigated the changes of TRIC and LSR during cochlear cell differentiation and the effects of histone deacetylase (HDAC) inhibitors against cell degeneration induced by loss of TRIC and LSR. During cell differentiation induced by the temperature change, expression of TRIC and LSR were clearly induced. Treatment with metformin enhanced expression TRIC and LSR via AMPK during cell differentiation. Loss of TRIC and LSR by the siRNAs induced cell death in differentiated cells. Treatment with HDAC inhibitors trichostatin A and HDAC6 inhibitor prevented the cell death induced by loss of TRIC and LSR. Collectively, these findings suggest that both tTJ proteins TRIC and LSR have crucial roles for the differentiated cochlear cell survival, and that HDAC inhibitors may be potential therapeutic agents to prevent hearing loss.