Tazuko Fujiwara

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.

E prostanoid 2 (EP2)/EP4‐mediated suppression of antigen‐specific human T‐cell responses by prostaglandin E2

Prostaglandin E2 (PGE2) is a lipid mediator that displays important immunomodulatory properties, such as polarization of cytokine production by T cells. Recent investigations have revealed that the effect of PGE2 on cytokine production is greatly influenced by external stimuli; however, it is unclear whether PGE2 plays a significant role in major histocompatibility complex‐mediated antigen‐specific T‐cell responses via binding to one of four subtypes of E prostanoid (EP) receptor alone or in combination. In the present study, we sought to determine the effect of PGE2 on antigen‐specific CD4+ T‐cell responses in humans, especially in terms of receptor specificity. We used purified protein derivative (PPD) and Cry j 1 as T helper type 1 (Th1) and Th2‐inducing antigens, respectively. We generated several different Cry j 1‐ and PPD‐specific T‐cell lines (TCLs). PGE2 significantly and dose‐dependently inhibited the proliferation and subsequent production of interleukin‐4 by Cry j 1‐specific TCLs and of interferon‐γ by PPD‐specific TCLs upon antigen stimulation. Administration of EP2 receptor agonist and EP4 receptor agonist suppressed these responses in an adenylate cyclase‐dependent manner, while EP1 and EP3 receptor agonists did not. Messenger RNA for EP2, EP3 and EP4, but not EP1, receptors were detected in Cry j 1‐ and PPD‐specific TCLs, and no differences in EP receptor expression were observed between them. Furthermore, PGE2 and EP2 receptor agonist significantly inhibited interleukin‐5 and interferon‐γ production by peripheral blood mononuclear cells in response to Cry j 1 and PPD stimulation, respectively. These results suggest that PGE2 suppresses both Th1‐ and Th2‐polarized antigen‐specific human T‐cell responses via a cAMP‐dependent EP2/EP4‐mediated pathway.

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.

Prostaglandin E2 suppresses staphylococcal enterotoxin-induced eosinophilia-associated cellular responses dominantly through an E-prostanoid 2-mediated pathway in nasal polyps

BACKGROUND Recent investigations have revealed that staphylococcal enterotoxins (SEs), COX metabolism, or both might participate in the pathogenesis of eosinophilic airway diseases, such as chronic rhinosinusitis with nasal polyposis. OBJECTIVE We sought to determine whether COX metabolism, especially prostaglandin (PG) E(2), plays a significant role in SE-induced cellular responses in nasal polyps. METHODS Dispersed nasal polyp cells (DNPCs) were prepared from nasal polyps by means of enzymatic digestion. DNPCs were cultured with SEB in the presence or absence of COX inhibitors (diclofenac and indomethacin) for 72 hours; then the levels of IL-5, IL-13, RANTES, and eotaxin in the supernatants were measured. The effect of PGE(2) on SEB-induced responses by diclofenac-treated DNPCs was examined, especially in terms of receptor specificity. RESULTS DNPCs produced significant amounts of IL-5, IL-13, and RANTES in response to SEB. COX inhibitors significantly increased the production of these cytokines. The degree of local eosinophilia was significantly and positively correlated with the changes in IL-5 production induced by diclofenac treatment. PGE(2) significantly and dose-dependently inhibited SEB-induced IL-5, IL-13, and RANTES production by diclofenac-treated DNPCs. E-prostanoid (EP) 2 receptor-selective agonist strongly inhibited the production of all 3 cytokines. EP3 and EP4 receptor-selective agonists partially suppressed these responses, whereas EP1 receptor-selective agonist did not. Interestingly, all of the combined treatments with 2 of the 4 EP receptor-selective agonists significantly inhibited the SEB-induced responses by diclofenac-treated DNPCs. CONCLUSIONS These results suggest that PGE(2) inhibits the pathogenesis of SEB-induced eosinophilic inflammation primarily through the EP2-mediated pathway in patients with chronic rhinosinusitis with nasal polyposis.

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 Mycobacterium tuberculosis (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 16 600 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.

Functional expression of Fas and Fas ligand on human intestinal intraepithelial lymphocytes.

Intestinal intraepithelial lymphocytes (IEL) constitute the first lymphoid compartment to encounter dietary antigens and intestinal pathogens. IEL are proposed to be involved in the defence against bacterial and viral invasion and to play an important role in mucosal immunity. Fas (CD95/APO‐1) is a surface receptor that induces apoptotic cell death upon ligation with Fas ligand (FasL). The aim of this study was to examine the expression and function of Fas and FasL on freshly isolated normal human colonic IEL. The expression and function of Fas and FasL on IEL isolated from 40 normal colonic specimens were examined by flow cytometry, reverse transcriptase‐polymerase chain reaction, immunohistochemistry, and DNA‐release cytotoxicity assay. Virtually all CD3+ IEL (95.2 ± 4.3%) expressed Fas and were sensitive to agonistic anti‐Fas antibody, whereas only 56.6 ± 8.4% of peripheral T lymphocytes expressed Fas and were resistant to the antibody. We also detected FasL mRNA and protein (40.1 ± 4.2%) on IEL, and found that IEL exerted FasL‐mediated cytotoxicity against Fas‐expressing target cells. These findings suggest that human IEL are activated in situ but are tightly regulated by the constitutive expression of functional Fas and FasL to maintain homeostasis of the mucosal immune system.

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.

Early interventional treatment with intranasal mometasone furoate in Japanese cedar/cypress pollinosis: a randomized placebo-controlled trial.

BACKGROUND Little is known about the safety and effectiveness of early interventional treatment (EIT) with intranasal corticosteroids for seasonal allergic rhinitis. We designed a double-blinded, randomized, placebo-controlled 12-week trial of EIT with mometasone furoate nasal spray (MFNS) for Japanese cedar/cypress pollinosis (JCCP). METHODS A total of 50 JCCP patients received MFNS (200μg once daily: n = 25) or placebo (n = 25) starting on February 1, 2010. Treatments continued until the end of April. The primary endpoint was the comparison of the total nasal symptom score (TNSS) between the MFNS and placebo groups. The secondary endpoints included comparisons of QOL, daytime sleepiness, nasal ECP levels, and safety. RESULTS Continuous dispersion of Japanese cedar pollen began on February 22. Although the placebo group showed a significant worsening of symptoms after the start of the continuous dispersion, no worsening occurred in the MFNS group. A significant difference in the TNSS between the two groups was seen starting at 4 weeks after the treatment. Similar results were seen for QOL and sleepiness. Nasal ECP levels in March were significantly lower in the MFNS group. A total of 56% of the MFNS group progressed to a persistent allergic rhinitis state in accordance with the ARIA classification, as opposed to 84% of the placebo group. MFNS was well tolerated, and the plasma cortisol concentrations were similar between the two groups. CONCLUSIONS EIT with MFNS for JCCP is both safe and effective. This treatment can potentially lessen symptoms and help pollinosis patients remain in the intermittent state.