Atsushi Harimaya

Protein Kinase C Enhances Tight Junction Barrier Function of Human Nasal Epithelial Cells in Primary Culture by Transcriptional Regulation

The epithelium of upper respiratory tissues such as human nasal mucosa forms a continuous barrier via tight junctions, which is thought to be regulated in part through a protein kinase C (PKC) signaling pathway. To investigate the mechanisms of the regulation of PKC-mediated tight junction barrier function of human nasal epithelium in detail, primary human nasal epithelial cells were treated with the PKC activator 12-O-tetradecanoylophorbol-13-acetate (TPA). In primary human nasal epithelial cells, treatment with TPA led not only to activation of phosphorylation of PKC, myristoylated alanine-rich C kinase substrate, and mitogen-activated protein kinase but also expression of novel PKC-δ, PKC-θ, and PKC-ϵ. Treatment with TPA increased transepithelial electrical resistance, with tight junction barrier function more than 4-fold that of the control, together with up-regulation of tight junction proteins, occludin, zona occludens (ZO)-1, ZO-2 and claudin-1 at the transcriptional level. Furthermore, it affected the subcellular localization of the tight junction proteins and the numbers of tight junction strands. The up-regulation of barrier function and tight junction proteins was prevented by a pan-PKC inhibitor, and the inhibitors of PKC-δ and PKC-θ but not PKC-ϵ. In primary human nasal epithelial cells, transcriptional factors GATA-3 and -6 were detected by reverse transcription-polymerase chain reaction. The knockdown of GATA-3 using RNA interference resulted in inhibition of up-regulation of ZO-1 and ZO-2 by treatment with TPA. These results suggest that TPA-induced PKC signaling enhances the barrier function of human nasal epithelial cells via transcriptional up-regulation of tight junction proteins, and the mechanisms may contribute to a drug delivery system.

Thymic stromal lymphopoietin enhances tight-junction barrier function of human nasal epithelial cells

Epithelial-derived thymic stromal lymphopoietin (TSLP) triggers dendritic cell (DC)-mediated Th2-type inflammatory responses and is a master switch for allergic inflammatory diseases. In the present study, the expression and induction of TSLP and the effects of TSLP on the tight-junctional barrier of human nasal epithelial cells (HNECs) have been investigated in order to elucidate the role of TSLP in allergic rhinitis. We have found high expression of TSLP in the epithelium from patients with allergic rhinitis with recruitment and infiltration of DCs. In vitro, TSLP is significantly produced in HNECs after treatment with a toll-like receptor 2 (TLR2) ligand, Pam3Cys-Ser-(Lys)4, and a mixture of interleukin-1β and tumor necrosis factor-α. Treatment with TSLP rapidly enhances the barrier function of cultured HNECs, together with an increase of tight-junction proteins claudin-1, -4, -7, and occludin. The nasal-epithelial-derived TSLP thus not only activates DCs but also preserves the epithelial barrier via the upregulation of tight-junction proteins, thereby regulating antigen sensitization during the early stage of allergic rhinitis.

High Incidence of Alloiococcus otitidis in Children with Otitis Media, Despite Treatment with Antibiotics

ABSTRACT Acute otitis media (AOM) and otitis media with effusion (OME) are common diseases in childhood. Alloiococcus otitidis is a newly recognized species of gram-positive bacterium which was recently discovered as a pathogen associated with OME. Although some studies show that A. otitidis is frequently detected in children with OME, no study is available concerning the clinical efficiency of antibiotics against this organism. The prevalence of A. otitidis in 116 middle ear effusion specimens from 36 AOM and 52 OME patients was examined by culture and PCR. In addition, the prevalence of the bacterium was retrospectively investigated in relation to antibiotic use. A. otitidis was detected in 20 (50%) AOM and 47 (61%) OME specimens. The organism was the most frequent bacterium in AOM as well as in OME and was highly detected even in patients who had been treated with antibiotics, such as beta-lactams or erythromycin. The incidence of A. otitidis in our study was higher than that in Western countries, and our results suggest that drug-resistant strains of A. otitidis may be frequently spread in Japanese children. Our study suggests that antibiotics such as beta-lactams or erythromycin may not be sufficiently effective to eliminate this organism. Further investigation is expected to reveal the clinical role of the organism in otitis media.

Preliminary study of proinflammatory cytokines and chemokines in the middle ear of acute otitis media due to Alloiococcus otitidis.

Alloiococcus otitidis is a newly discovered organism frequently detected in otitis media. However, the association of the organism with the development of otitis media has not been disclosed in detail yet. In the middle ear, proinflammatory cytokines and chemokines are released in association with infection by pathogens, and these cytokines contribute to the induction of an inflammatory reaction. To investigate the profile of inflammation-related cytokines in the acute phase of A. otitidis infection, we analyzed the release of proinflammatory cytokines and chemokines in middle ear effusions of acute otitis media due to A. otitidis, in comparison with acute otitis media due to the well-known Gram-positive middle ear pathogen Streptococcus pneumoniae. The amounts of proinflammatory cytokines (IL-8, IL-1beta, IL-6, TNF-alpha) and CXC chemokines (IP-10, I-TAC) were significantly increased in the A. otitidis group as well as in the S. pneumoniae group. Various inflammation-related cytokines/chemokines were induced in the A. otitidis-infected middle ear, and the profile of cytokines was very similar to that in S. pneumoniae infection. This preliminary study suggests that A. otitidis has the potential to induce these cytokines, contributing to the development of an inflammatory reaction in the middle ear cavity in a similar manner to S. pneumoniae.

Changes of Gap and Tight Junctions during Differentiation of Human Nasal Epithelial Cells Using Primary Human Nasal Epithelial Cells and Primary Human Nasal Fibroblast Cells in a Noncontact Coculture System

The epithelium of upper respiratory tissues such as nasal mucosa forms a continuous barrier to a wide variety of exogenous antigens. The epithelial barrier function is regulated in large part by the intercellular junctions, referred to as gap and tight junctions. However, changes of gap and tight junctions during differentiation of human nasal epithelial (HNE) cells are still unclear. In the present study, to investigate changes of gap and tight junctions during differentiation of HNE cells in vitro, we used primary human HNE cells cocultured with primary human nasal fibroblast (HNF) cells in a noncontact system. In HNE cells cocultured with HNF cells for 2 weeks, numerous elongated cilia-like structures were observed compared to those without HNF cells. In the coculture, downregulation of Cx26 and upregulation of Cx30.3 and Cx31 were observed together with extensive gap junctional intercellular communication. Furthermore, expression of the tight junction proteins claudin-1, claudin-4, occludin and ZO-2 was increased. These results suggest that switching in expression of connexins and induction of tight junction proteins may be closely associated with differentiation of HNE cells invitro and that differentiation of HNE cells requires unknown soluble factors secreted from HNF cells.

Colonization and Turnover of Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis in Otitis-Prone Children

Recurrent otitis media are frequently intractable during childhood. It is unclear whether recurrent otitis media is caused by etiological bacteria colonization or by new infections. Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis were isolated from the nasopharynx of 7 otitis‐prone and 2 non‐prone children with recurrent otitis media. Plural bacterial species and strains were found in all children while affected by otitis media. The same strain was repeatedly isolated from all otitis‐prone children even after administration of antibiotics but was not from the non‐prone children. Antibiotic susceptibility did not differ significantly among the same repeatedly isolated strains. This pilot study suggests that the etiological bacteria tend to colonize and is hard to eliminate in otitis‐prone children.

Alloiococcus otitidis is a ligand for collectins and Toll-like receptor 2, and its phagocytosis is enhanced by collectins.

Alloiococcus otitidis has been found to be associated with otitis media with effusion. In this study we investigated whether TLR2 and collectins, surfactant protein A (SP‐A) and mannose‐binding lectin (MBL), interacted with A. otitidis. Both SP‐A and MBL bound to A. otitidis in a Ca2+‐dependent manner. A. otitidis induced IL‐8 secretion from U937 cells and NF‐κB activation in TLR2‐transfected HEK293 cells. However, the cells transfected with the mutant TLR2P681H did not respond to A. otitidis. In addition, A. otitidis co‐sedimented a recombinant soluble form of the extracellular TLR2 domain, indicating direct binding of the bacterium to TLR2. SP‐A and MBL augmented the phagocytosis of A. otitidis by J774A.1 cells. The collectin‐stimulated phagocytosis of A. otitidis was significantly attenuated when fucoidan and polyinosinic acid were co‐incubated. Immunoblotting analysis revealed that MBL was present in the middle ear effusion from patients with otitis media. These results demonstrate that A. otitidis is a ligand for the collectins and TLR2, and that the collectins enhance the phagocytosis of A. otitidis by macrophages, suggesting important roles of the collectins and TLR2 in the innate immunity of the middle ear against A. otitidis infection.

Detection of Alloiococcus otitidis and three middle ear pathogens in the nasopharynx and the middle ear effusion of otitis-prone children

Abstract The three major pathogens of otitis media are Streptococcus pneumoniae, Haemophillus influenzae and Moraxella catarrhalis. Nasopharyngeal colonization of these pathogens is associated with the development of otitis media. A new species of bacterium, Alloiococcus otitidis, is detected with high frequency in the middle ear effusions (MEE) by polymerase chain reaction (PCR), however, the association of A. otitidis in the nasopharynx with the development of otitis media is still unclear. To clarify this point, we investigated the frequency of A. otitidis in MEE and nasopharyngeal swabs (NPS) of otitis-prone children, with culture and PCR. The frequency of A. otitidis in MEE was higher than that of the three major pathogens. Although our data suggest that A. otitidis colonization of the nasopharynx is associated with otitis media, the frequency of A. otitidis was higher in MEE than in NPS. This suggests that A. otitidis colonization may involve other sites as well as the nasopharynx.

Remarkably high prevalence of fts I gene mutations in Haemophilus influenzae isolates from upper respiratory tract infections in children of the Sapporo district, Japan

Recently, the frequency of isolation of beta-lactamase-negative ampicillin resistant (BLNAR) strains of Haemophilus influenzae in Japanese children has been increasing rapidly. Drug resistance in BLNAR strains is associated with mutations of the fts I gene, which encodes penicillin-binding protein 3. In the otolaryngological field, only a few reports have been available concerning fts I gene mutations in BLNAR. We investigated the prevalence of fts I gene mutations, by polymerase chain reaction (PCR) genotyping, in H. influenzae isolates from the upper respiratory tracts of children in the Sapporo district, Japan. When the isolates were classified according to PCR genotyping, 34 (44.2%) of 77 isolates were beta-lactamase-negative ampicillin-sensitive (g-BLNAS), 8 (10.4%) were g-low-BLNAR, 30 (39.0%) were g-high-BLNAR, 2 (2.6%) were beta-lactamase-positive ampicillin-resistant (g-BLPAR), and 3 (3.9%) were beta-lactamase-positive ampicillin/clavulanic acid-resistant (g-high-BLPACR). Mutations in the fts I gene were generally parallel to ampicillin susceptibility, and were frequently observed in children who were 7 years or younger. Of the beta-lactams tested, cefditoren showed the strongest inhibition of H. influenzae isolates, and it inhibited g-BLNAR and g-BLPACR. This study revealed a remarkably high prevalence of fts I gene mutations (g-BLNAR and g-BLPACR) in our district. Furthermore, a regional difference in the prevalence of fts I gene mutations was observed even at the district level.

Difference in cytokine production and cell activation between adenoidal lymphocytes and peripheral blood lymphocytes of children with otitis media.

ABSTRACT We evaluated the immunological potential of adenoidal lymphocytes from children with recurrent otitis media. Interleukin-4 release and CD69 expression were lower in adenoidal lymphocytes than in peripheral blood lymphocytes (PBL). Our results suggest that there may be a difference between the immunological potential of adenoidal lymphocytes and that of PBL in children with otitis.