Kazunori Nishizaki

Strain-dependent induction of allergic rhinitis without adjuvant in mice

Background: To date, no murine models have been reported to show the induction of both antigen‐specific IgE and nasal eosinophilia, two of the major hallmarks of allergic rhinitis, after local sensitization in the absence of adjuvants, a phenomenon which reflects natural exposure. In this report, we attempted to establish a murine model representing an initiation of allergic rhinitis.

CRTH2 plays an essential role in the pathophysiology of Cry j 1-induced pollinosis in mice

PGD2 is the major prostanoid produced during the acute phase of allergic reactions. Two PGD2 receptors have been isolated, DP and CRTH2 (chemoattractant receptor-homologous molecule expressed on Th2 cells), but whether they participate in the pathophysiology of allergic diseases remains unclear. We investigated the role of CRTH2 in the initiation of allergic rhinitis in mice. First, we developed a novel murine model of pollinosis, a type of seasonal allergic rhinitis. Additionally, pathophysiological differences in the pollinosis were compared between wild-type and CRTH2 gene-deficient mice. An effect of treatment with ramatroban, a CRTH2/T-prostanoid receptor dual antagonist, was also determined. Repeated intranasal sensitization with Cry j 1, the major allergen of Cryptomeria japonica pollen, in the absence of adjuvants significantly exacerbated nasal hyperresponsive symptoms, Cry j 1-specific IgE and IgG1 production, nasal eosinophilia, and Cry j 1-induced in vitro production of IL-4 and IL-5 by submandibular lymph node cells. Additionally, CRTH2 mRNA in nasal mucosa was significantly elevated in Cry j 1-sensitized mice. Following repeated intranasal sensitization with Cry j 1, CRTH2 gene-deficient mice had significantly weaker Cry j 1-specific IgE/IgG1 production, nasal eosinophilia, and IL-4 production by submandibular lymph node cells than did wild-type mice. Similar results were found in mice treated with ramatroban. These results suggest that the PGD2-CRTH2 interaction is elevated following sensitization and plays a proinflammatory role in the pathophysiology of allergic rhinitis, especially pollinosis in mice.

Presence and characterization of prostaglandin D2-related molecules in nasal mucosa of patients with allergic rhinitis

Background Prostaglandin D2 (PGD2) is the major prostanoid produced in the acute phase of allergic reactions. However, its pathophysiological role in addition to the pathway of production in allergic rhinitis remains unclear. We sought to determine the expression of synthases and receptors for PGD2 in human nasal mucosa. These expressions were compared between allergic and nonallergic patients. Methods The expression and localization of hematopoietic-type (h)-PGD2 synthase (PGDS) and lipocalin-type (l)-PGDS were detected by immunohistochemistry. The expression of D prostanoid (DP) receptor and chemoattractant receptor–homologous molecule expressed on Th2 cells (CRTH2) was determined by quantitative real-time PCR. Results The h-PGDS but not l-PGDS was clearly expressed in nasal mucosa. The expression of h-PGDS in allergic patients was significantly higher than in control patients without mucosal hypertrophy. A variety of infiltrating cells including mast cells, eosinophils, macrophages, and lymphocytes as well as constitutive cells such as epithelial cells and fibroblasts expressed h-PGDS. The expression of both DP and CRTH2 was confirmed also. Although either the amount of DP or the amount of CRTH2 was not correlated with serum levels of IgE, the amount of CRTH2 but not DP was highly and significantly correlated with the number of eosinophils infiltrating into nasal musosa. Conclusion These results suggest that PGD2 is released via the action of h-PGDS from various cells, and the expression of h-PGDS may be associated with the hypertrophic inflammation in the nose. In addition, ligation of PGD2 to CRTH2 appears to be selectively involved in eosinophil recruitment into the nose regardless of atopic status.

Role of prostaglandin D2 and E2 terminal synthases in chronic rhinosinusitis

Background Prostaglandin (PG)D2 and E2, two major cyclooxygenase (COX) products, are generated by PGD2 synthase (PGDS) and PGE2 synthase (PGES), respectively, and appear to mediate airway inflammation.

Identification of a candidate tumor suppressor gene RHOBTB1 located at a novel allelic loss region 10q21 in head and neck cancer

Purpose: Aims of the study are to narrow-down the hotspot region on 10q21 defined by previous genome-wide loss of heterozygosity (LOH) analysis in head and neck squamous cell carcinomas (HNSCC) and to define candidate tumor suppressor genes (TSG) concerned with 10q21. Materials and methods: LOH analysis was carried out with ten polymorphic microsatellite markers. Expression analysis was performed by semi-quantitative RT-PCR, and mutation analysis by PCR and direct sequencing. Results: LOH analysis on 10q21 in 52 HNSCC indicated distinctive and frequent allelic loss at D10S589 (42%). Among flanking genes, we found the RHOBTB1 gene as a candidate TSG, since an intragenic marker demonstrated the highest LOH (44%). Expression analysis revealed down-regulation of RHOBTB1 mRNA in 37% of tumors. Interestingly, all the five tumors that showed decreased expression of RHOBTB1 were accompanied with LOH, supporting the haploinsufficiency and class 2 TSG characteristics of RHOBTB1. No pathogenic mutation of RHOBTB1 was found. Furthermore, another gene within the region, EGR2, was also taken under scope. LOH frequencies around the EGR2 gene were relatively low (23 and 33%). Albeit semi-quantitative expression analysis of EGR2 demonstrated downregulation in 45% of tumor samples, no relation was found between the expression levels and LOH status. Conclusion: Frequent allelic loss and decreased expression of RHOBTB1 suggested that this gene has a role in tumorigenesis of a subset of HNSCC.

Cochlear expression of a dominant-negative GJB2R75W construct delivered through the round window membrane in mice

Development of a gene-delivery method to the inner ear is an essential step for studies of hearing function and gene therapy. Application of liposomes or adenoviral vectors onto the intact round window membrane (RWM) offers the possibility of atraumatic exogenous gene transfer. GJB2 encodes the gap junction protein Connexin26, which plays a crucial role in potassium recycling in the inner ear. The R75W allele of GJB is a well-characterized mutation that causes deafness at the DFNA3 through a dominant-negative mechanism of action. In this study, a plasmid vector, pGJB2(R75W)-eGFP, was lipocomplexed with N-[1-(2,3-Dioleoloxy)propyl]N,N,N-trimethylammonium methylsulfate: cholesterol and applied onto mouse RWM. At 3 days (3d) post-treatment, immunohistochemistry demonstrated GJB2(R75W)-eGFP transgene expression in the cochlea in: inner and outer pillar cells, outer hair cells, Claudius cells and, in the spiral limbus and ligament. Significant hearing loss was detected by auditory brainstem response testing after 1, 2 and 3d post-treatment; hearing levels returned to control levels at 5d post-treatment. These data confirm that GJB2(R75W) induces functional impairment in the mature cochlea through a dominant negative effect, and importantly, that RWM application of exogenous genes is a feasible method to test their impact on hearing.

Nasal exposure to Staphylococcal enterotoxin enhances the development of allergic rhinitis in mice

Background Staphylococcal enterotoxins (SEs) appear to play a role in the pathogenesis of allergic disease. However, little is known whether the nasal exposure to SE affects the development of allergic rhinitis (AR).

Histamine H4 receptor agonists have more activities than H4 agonism in antigen‐specific human T‐cell responses

Histamine not only mediates immediate allergic reactions, it also regulates cellular immune responses. H4R is the most recently identified histamine receptor (HR). In the present study, we examined the in vitro effect of histamine and H4R agonists on the responses of human T cells to purified protein derivative from Mycobacteriumu2003tuberculosis (PPD) and to Cry j1, the major allergen of Cryptomeria japonica pollen. Dimaprit, clobenpropit and clozapine, which are H4R agonists, dose‐dependently blocked both PPD‐induced interferon‐γ and Cry j1‐induced interleukin‐5 production by both peripheral blood mononuclear cells (PBMCs) and antigen‐specific T‐cell lines. However, the addition of thioperamide, an H3R/H4R antagonist, as well as a mixture of d‐chlropheniramine, famotidine and thioperamide, did not reverse the inhibition. Pretreatment of PBMCs with SQ22536 and 8‐bromoadenosine‐3′,5′‐cyclic monophosphorothioate, Rp‐isomer, had varying abilities to reverse the inhibitory effects of H4R agonists, except for clobenpropit. Moreover, the addition of H4R agonists induced annexin‐V expression on PBMCs, especially in CD19+ and CD4+ cells. cDNA microarray analysis revealed that, among 16u2003600 genes tested, increased expression following treatment with clozapine was seen in 0·8% of the genes, whereas decreased expression was seen in 3·0% of the genes. These results suggest that H4R agonists inhibit antigen‐specific human T‐cell responses, although H4R does not appear to be important for this effect. In addition, the present study indicated that there may be orphan receptors or HR subtypes which can bind dimaprit, clobenpropit and clozapine, and that can exert an inhibitory effect on antigen‐specific cellular responses via a cAMP/cAMP‐dependent protein kinase‐dependent, apoptotic pathway.

Sudden hearing impairment combined with diabetes mellitus or hyperlipidemia.

The objective of this study was to delineate whether the presence of the risk factors of microvascular disorder (MD) contribute to the prognostic outcome in patients with idiopathic sudden deafness (ISD). Retrospective clinical record review was conducted with 106 patients of ISD. Pure tone hearing thresholds were compared among the groups with or without hyperglycemia and hypercholesterolemia. Significantly better hearing recoveries were observed in cases with hyperglycemia as compared with controls. There was a tendency that the magnitude of hearing recovery in hypercholesterolemia was greater than that of controls although there was no statistical difference. The presence of the risks in MD could be an indicator of better hearing prognosis of ISD if we choose appropriate treatments. Heterogeneity of the ISD makes the establishment of the relationship between the risk factors of MD and etiology of some cases of ISD. We may have to choose the treatments for ISD considering whether the patient has any risk factor of MD.

Expression and Characterization of PGD2 Receptors in Chronic Rhinosinusitis: Modulation of DP and CRTH2 by PGD2

Background: Prostaglandin D2 (PGD2) participates in airway inflammation. We reported that levels of hematopoietic-type PGD2 synthase (h-PGDS) in sinonasal tissues may play an important role in the pathophysiology of chronic rhinosinusitis (CRS). Two PGD2 receptors have been isolated, DP and CRTH2, but whether they participate in CRS remains unclear. We sought to determine the expression and characterization of DP and CRTH2 in CRS. Methods: Expression of DP and CRTH2 in nasal polyps (NP) and uncinate process mucosae (UPM) was examined by in situ hybridization and immunohistochemistry and evaluated by real-time quantitative PCR. h-PGDS, IL-5, eotaxin and RANTES expression was also determined. In addition, the effect of PGD2 on the expression of both receptors in UPM was assessed. Results: DP was widely expressed, not only in infiltrating inflammatory cells but also in constitutive cells such as vascular endothelial cells and ciliated columnar epithelia. CRTH2 was selectively expressed in inflammatory cells and some glands. Significantly greater levels of DP mRNA and conversely decreased levels of CRTH2 mRNA were observed in NP compared with UPM. DP and CRTH2 mRNA levels were not only positively and inversely correlated with levels of h-PGDS but also with eotaxin, respectively. Furthermore, addition of PGD2 significantly increased DP expression and conversely reduced CRTH2 expression in UPM. Conclusions: These results suggest that distinct expression of DP and CRTH2 is associated with the pathophysiology of CRS, including NP formation, and the expression of these receptors may be regulated by h-PGDS and PGD2.