Sex-related differences in the initiation of allergic rhinitis in mice

BACKGROUND: Several clinical and epidemiologic studies have investigated sex differences in the prevalence of allergic rhinitis. At present, however, no reports have demonstrated such differences in experimental models with local, but not parenteral, sensitization with antigens that may reflect natural exposure to allergens. We have recently developed murine models of allergic rhinitis after repeated intranasal sensitization with antigens in the absence of adjuvants. In this study, we investigated the role of sex in the initiation of the disease in vivo. METHODS: Male and female CBA/J and BALB/c mice were sensitized intranasally with phospholipase A2 (PLA2) and Schistosoma mansoni egg antigen (SEA), respectively, in the absence of adjuvants. After the repeated sensitization, serum Ab titers against the sensitizing antigen and nasal eosinophilia were determined. In addition, the involvement of androgen in IgE synthesis was investigated in castrated CBA/J male mice with or without testosterone administration. RESULTS: Females produced significantly higher levels of PLA2-specific IgE than males in CBA/J mice sensitized with PLA2. On the other hand, both titers of PLA2-specific IgG1 and nasal eosinophilia did not significantly differ between the two groups. Castrated male mice produced significantly higher amounts of PLA2-specific IgE than sham-treated male mice. In addition, PLA2-specific IgE production decreased in castrated mice treated with testosterone. Sexual differences in the production of Ag-specific IgE were not seen in BALB/c mice after the sensitization with SEA. CONCLUSION: These results suggest that sex is responsible for the production of Ag-specific IgE, but not IgG1 or nasal eosinophilia, and that androgen appears to be involved in the in vivo production of specific IgE in male mice.     

Intranasal application of purified protein derivative suppresses the initiation but not the exacerbation of allergic rhinitis in mice

BACKGROUND: Several epidemiological and experimental studies have demonstrated that exposure to pathogens such as those from the genus Mycobacterium leads to the suppression of allergic sensitization and inflammation. However, little is known as to whether pathogen-derived soluble antigens have the potential to modulate the pathogenesis of allergic rhinitis. OBJECTIVE: We sought to determine whether application of purified protein derivative (PPD) from Mycobacterium tuberculosis can suppress the initiation and/or exacerbation of allergic rhinitis using a recently developed murine model. METHODS: First, we investigated whether a single intranasal application of PPD could elicit cytokine production in the nose by RT-PCR. BALB/c mice were repeatedly sensitized with Schistosoma mansoni egg antigen (SEA) intranasally without an adjuvant. PPD was applied through different routes either before or after sensitization. The production of SEA-specific antibodies, nasal eosinophilia and cytokines by nasal lymphocytes was compared among mice that had or had not received PPD treatment. RESULTS: IFN-gamma, but not IL-4, was detected in the nasal tissue 12 to 48 h after a single intranasal application of 10 microg PPD. Repeated intranasal application of PPD prior to and during sensitization with SEA significantly inhibited the production of both SEA-specific IgE/IgG1 and nasal eosinophilia. Moreover, it partially inhibited the production of IL-4 by nasal lymphocytes in response to SEA. Conversely, this treatment led to a significant increase in IFN-gamma production. On the other hand, PPD applied through the footpad had no effect over the same period. Repeated intranasal application of PPD after sensitization with SEA had no exacerbative effect on allergic inflammation. CONCLUSION: These results indicate that the local application of PPD, and the subsequent induction of IFN-gamma, inhibits the initiation, but not the exacerbation, of allergic rhinitis in mice. This suggests that pathogen-derived antigens have potential for use in the prevention and prophylaxis of allergic rhinitis.     

Interleukin-4-independent production of Th2 cytokines by nasal lymphocytes and nasal eosinophilia in murine allergic rhinitis

BACKGROUND: Interleukin (IL)-4 is believed to play an important role in the atopic pathogenesis. However, the precise role of IL-4 in the in vivo initiation of allergic rhinitis is not fully understood. We have recently found that BALB/c mice sensitized intranasally with Schistosoma mansoni egg antigen (SEA) mount a Th2 response that initiates allergic rhinitis. Thus, we sought to determine the role of IL-4 in the initiation of allergic rhinitis in vivo with this model. METHODS: IL-4 gene-deficient (IL-4 -/-) BALB/c and wild-type (IL-4 +/+) control mice were sensitized by intranasal SEA administration, and their immunologic responses were examined both in vivo and in vitro. RESULTS: IL-4 +/+ mice sensitized with SEA displayed significantly higher titers of SEA-specific IgG1 and IgE antibodies than IL-4-/- mice, while the latter produced significantly more SEA-specific IgG2a. Antigen-stimulated nasal lymphocytes from SEA-sensitized IL-4 -/- and IL-4 +/+ mice produced similar amounts of IL-5 and IL-10, but neither produced IFN-gamma. Furthermore, the severity of nasal eosinophilia was similar in both groups. CONCLUSIONS: These results indicate that although IL-4 is necessary for the production of Th2-associated antibodies--in particular, IgE--it is not required for either the production of the Th2-associated cytokines IL-5 and IL-10, or the induction of nasal eosinophilia.     

Immunosuppressive effect of restraint stress on the initiation of allergic rhinitis in mice

BACKGROUND: Exposure to acute stressors modulates both innate and acquired immune function. However, little is known about whether stress has the potential to modulate the pathogenesis of allergic rhinitis. OBJECTIVES: To determine the effects of acute restraint stress on the initiation of allergic rhinitis in a murine model. METHODS: CBA/J mice were repeatedly intranasally sensitized with phospholipase A2 (PLA2) from honeybee venom without adjuvant. Restraint stress was applied using uniform cylinders once a week for a continuous 8-hour period, on five occasions in total. Production of PLA2-specific antibodies and degree of nasal and blood eosinophilia were compared between stressed and control mice. RESULTS: Repeated intranasal sensitization with PLA2 induced PLA2-specific IgE and marked eosinophilia in both the nose and blood in CBA/J mice. Exposure to restraint stress significantly inhibited production of PLA2-specific IgE, IgG1 and IgG2a. Conversely, the stress exerted no significant effect on eosinophilia. CONCLUSIONS: Exposure to acute restraint stress inhibits antigen-specific antibody production, but not local or systemic eosinophilia. The results of this study suggest that acute stress has the potential to modulate the initiation of allergic rhinitis.     

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). OBJECTIVE: We sought to determine the in vivo effect of nasal exposure to SE on the development of AR using mouse model. METHODS: BALB/c mice were intranasally sensitized with Schistosoma mansoni egg antigen (SmEA) in the presence or absence of staphylococcal enterotoxin B (SEB). Control mice were intranasally sensitized with either SEB or SmEA alone. The production of antigen-specific antibodies including IgE, nasal eosinoplilia and cytokines by nasal mononuclear cells was compared among mice that had or had not received SEB treatment. RESULTS: Nasal exposure to SEB enhanced the development of AR in SmEA-sensitized mice, as manifested by SmEA-specific IgE production, nasal eosinophilia, and IL-4 and IL-5 production by nasal mononuclear cells after Ag challenge. This treatment also elicited IFN-gamma production by SmEA-primed cells. In addition, these mice produced SEB-specific IgE whereas mice treated with SEB without SmEA sensitization did not produce SEB-specific IgE or demonstrate nasal eosinophilia. CONCLUSION: These results suggest that the nasal exposure to SEB enhances susceptibility to AR although the exposure to SE solely does not induce AR.     

Vβ8+ T lymphocytes are essential in the regulation of airway hyperresponsiveness and bronchoalveolar eosinophilia but not in allergen-specific IgE in a murine model of allergic asthma

BACKGROUND: There is increasing evidence that in allergic asthma the inflammatory process is regulated by T lymphocytes. In BALB/c mice the majority of ovalbumin responsive T lymphocytes express the Vbeta8.1+ and Vbeta8.2+ T-cell receptor. OBJECTIVE: We analysed the contribution of Vbeta8+ T lymphocytes during the sensitization and challenge phase in the regulation of antigen-specific IgE, airway hyperresponsiveness and cellular infiltration in the airways in a murine model of allergic asthma. METHODS: Mice strains genetically lacking (SJL/J and SJA/9) and expressing (BALB/c) the Vbeta8+ T cell receptor were used. In addition, prior to the sensitization and prior to the challenge BALB/c mice were treated with antibodies to Vbeta8. Mice were sensitized with ovalbumin, followed by repeated challenge with ovalbumin or saline aerosols. RESULTS: In ovalbumin challenged BALB/c mice treated with control antibody a significant increase in eosinophils in the bronchoalveolar lavage, airway hyperresponsiveness and increased serum levels of ovalbumin-specific IgE were observed compared to control mice. Treatment of BALB/c mice with antibodies to Vbeta8 prior to the sensitization or prior to the challenge period completely inhibited the ovalbumin induced infiltration of eosinophils and airway hyperresponsiveness, while ovalbumin-specific IgE was slightly decreased. In SJA/9 and SJL/J mice ovalbumin challenge did not induce eosinophilic infiltration and airway hyperresponsiveness. In SJL/J mice ovalbumin challenge induced an upregulation of ovalbumin-specific IgE, however, in SJA/9 mice no upregulation was observed. CONCLUSION: It is demonstrated that Vbeta8+ T lymphocytes are essential for infiltration of eosinophils in the airways and development of airway hyperresponsiveness in a murine model of allergic asthma. In contrast, although Vbeta8+ T lymphocytes seem to be important for the extent of IgE levels, no essential role for Vbeta8+ T lymphocytes in the induction of antigen-specific IgE was observed.     

Differential rates of apoptosis and recruitment limit eosinophil accumulation in the lungs of asthma-resistant CBA/Ca mice

The accumulation of eosinophils is a common feature of allergic airway inflammation and correlates with disease severity. In an ovalbumin (OVA)-induced murine model of allergic lung disease, CBA/Ca mice develop much lower levels of lung eosinophilia, lung oedema, mucus hypersecretion and airways obstruction than BALB/c and C57BL/6 strains. In this study these strains have been examined to identify mechanisms that control the recruitment and survival of eosinophils in the allergic lung. Following immunization with OVA, CBA/Ca mice developed a robust systemic allergic response, with high levels of total and OVA-specific IgE and increases in peripheral blood eosinophils. Lung eotaxin-1 levels and expression of CD18 on eosinophils recovered by bronchoalveolar lavage (BAL) were least pronounced in CBA/Ca mice, whereas mRNA for L-selectin was highest in eosinophils from C57BL/6 mice. Apoptosis of BAL eosinophils ex vivo was most pronounced in the CBA/Ca strain. BALB/c mice expressed the highest levels of the eosinophil growth and survival factor interleukin (IL)-5 in the lungs and BAL eosinophils from these animals expressed more of the anti-apoptotic proteins Bcl-xL and Bcl-2 than cells from the other strains. A combination of lower levels of recruitment and rapid apoptosis may therefore limit the accumulation of eosinophils and pathology in the lungs of CBA/Ca mice. In addition, although the level of pathology that developed in C57BL/6 and BALB/c mice was similar, some of the underlying mechanisms are likely to differ.     

Blockade of CTLA-4 enhances allergic sensitization and eosinophilic airway inflammation in genetically predisposed mice

CTLA-4 (CD152) expression is restricted to subsets of activated T lymphocytes and shares homology with CD28. CTLA-4 and CD28 molecules both bind to B7 molecules on antigen-presenting cells. Whereas CD28-B7 interaction enhances T cell activation, cytokine production and survival, CTLA-4 signaling down-regulates T cell responses. Here, we studied the involvement of CTLA-4 triggering in the pathogenesis of allergen-induced airway inflammation in mice. Anti-CTLA-4 mAb were injected during i.p. sensitization with ovalbumin (OVA). This treatment favored OVA-specific IgE production and augmented blood eosinophilia in BALB/c mice. In BALB/c mice, enhanced Th2 sensitization after anti-CTLA-4 mAb injections resulted in more severe airway inflammation, and increased airway hyperresponsiveness to metacholine, bronchial eosinophilia and IL-4 and IL-5 levels in broncho-alveolar lavage (BAL) fluid following repeated allergen inhalations. Importantly, aggravation of airway inflammation and enhancement of Th2 responses were accompanied by a significant reduction of pulmonary TGF-beta levels at protein level in BAL fluid as well as on mRNA level in inflamed lung tissue. In contrast to BALB/c mice, blockade of CTLA-4 did not alter IgE production nor the phenotype of airway inflammation or TGF-beta production in C57BL/6 mice. Our data suggest that CTLA-4 triggering represents an important regulatory mechanism for Th2 sensitization in genetically predisposed mice by modulating TGF-beta production.     

Toll样受体9配体CpG-ODN鼻内应用对变应性联合气道疾病炎性反应的影响

目的:探讨免疫刺激序列Cp G寡聚脱氧核苷酸(Cp G-ODN)鼻内应用与皮下注射对变应性联合气道疾病(ACAD)模型小鼠下气道炎性反应的影响。方法:30只清洁级雌性BALB/c鼠随机分为正常对照组(control组)、变应性鼻炎组(AR组)、变应性联合气道疾病组(ACAD组)、变应性联合气道疾病Cp G-ODN鼻内滴入组(Cp G i.n.组)和变应性联合气道疾病Cp G-ODN皮下注射组(Cp G i.d.组)。实验组动物依次进行腹腔卵白蛋白(OVA)和氢氧化铝凝胶基础致敏和3次鼻腔激发,此后OVA或生理盐水(NS)雾化气道激发,正常对照组则给予NS。Cp G i.n.组和Cp G i.d.组分别给予10.0μg Cp G-ODN滴鼻和皮下注射,其它组给予NS滴鼻或皮下注射。观察Cp GODN干预后对鼻腔及下气道病理变化及评分,并对支气管肺泡灌洗液(BALF)行白细胞分类及嗜酸性粒细胞计数,ELISA法测定BALF和脾脏中细胞因子IL-4、IL-5、IL-13和IFN-γ,以及血清OVA特异性Ig E。结果:炎症细胞浸润评分示ACAD组小鼠肺部的病理改变程度高于control组和AR组(P0.01);Cp G i.n.组炎症评分较ACAD组下降,差异有统计学显著性(P0.05),而Cp G i.d.组炎症评分较ACAD组略有下降,但差异无统计学意义。Cp G i.n.组BALF中的白细胞总数、EOS绝对值计数、EOS百分比、BALF和脾脏淋巴细胞上清液中Th2细胞因子较ACAD组降低,差异具有统计学显著性(P0.01)。Cp G i.d.组上述指标略低于ACAD组,但差异无统计学显著性。Cp G i.n.组血清的OVA特异性Ig E较ACAD组下降,差异有统计学显著性(P0.05),而Cp G i.d.组与ACAD组比较有所下降,但差异无统计学显著性。结论:Cp G-ODN可通过抑制变应性鼻炎而抑制变应性联合气道疾病小鼠的下气道炎性反应,鼻内应用可能较皮下注射更有效。     

Systemic Administration of Olygodeoxynucleotides with CpG Motifs at Priming Phase Reduces Local Th2 Response and Late Allergic Rhinitis in BALB/c Mice

Oligodeoxynucleotides (ODN) with CpG motifs (CpG ODN) induce T helper (Th)1-type reaction. We aimed to evaluate the therapeutic effect of CpG ODN in the development of late allergic rhinitis induced by ovalbumin (OVA), which is one of Th2 diseaes, in BALB/c mice. Effects of a single dose of synthetic CpG-ODN (50 μg) intraperitoneally (i.p.) at the priming phase (on day 0) by OVA on the development of late eosinophilic rhinitis at respiratory areas were compared to the control mice treated with its vehicle (ODN without CpG motifs; 50 μg). Animals were again sensitized by OVA (on day 10) i.p., and 4 days after second sensitization animals were challenged by OVA intranasally (on day 14). Four days after challenge, eosinophilic reactions, nasal lesions and local cytokine values were examined. Compared to the control group, the CpG ODN-administration increased production of OVA-specific Th1 cytokine (interferon-γ) and decreased productions of ovalubmin-specific Th2 cytokines [interleukin (IL)-5 and IL-13] in nasal cavity fluids, supernatants of splenocytes and/or sera. Also, eosinophilia and increased total IgE values were decreased in mice treated with the CpG ODN compared to the control group. Moreover, nasal lesions with infiltration of eosinophils were prominently reduced by the CpG ODN-treatment compared to the control mice. The present study suggests that the systemic administration of CpG ODN at the priming phase may reduce local OVA-specific Th2 responses, resulting in decreased nasal pathology in the late allergic eosinophilic rhinitis. The authors wish it to be known, in their opinion, Toshiharu Hayashi and Keiko Hasegawa contributed equally to this work.     

An Antagonist for CCR4 Alleviates Murine Allergic Rhinitis by Intranasal Administration

Background: CCR4 is highly expressed on Th2 cells. These cells play an important role in acute inflammatory responses, including those involved in allergic rhinitis. We determined whether disrupting the CCR4 ligand interaction with CCR4 antagonist could alleviate allergic rhinitis in a mouse model. Methods: BALB/c mice were sensitized with ovalbumin and alum by intraperitoneal injection and challenged with intranasally administered ovalbumin. Compound 22, which has been reported as a novel small-molecule antagonist of CCR4, was also administered intranasally. In addition, budesonide, an efficient glucocorticoid, was used as a positive control. The effects of compound 22 were quantified by multiple parameters of allergic responses in both nasal and pulmonary tissues. Results: Compound 22 significantly improved symptoms of allergic rhinitis and suppressed levels of total IgE of serum. It dramatically reduced the levels of IL-4 in bronchoalveolar lavage fluid and also decreased the number of inflammatory cells in the fluid. The infiltration of inflammatory cells, especially eosinophils, was markedly reduced in the nasal and pulmonary tissues. The number of IL-4+ cells was also significantly reduced in these tissues. Moreover, the numbers of Foxp3+ cells and IL-17+ cells were reduced, though not to a statistically significant degree. Conclusions: In our research, CCR4 antagonists such as compound 22 were proven for the first time to alleviate murine allergic rhinitis when administered nasally. CCR4 antagonists may have therapeutic potential for the treatment of allergic rhinitis.     

Topical CTLA4-Ig suppresses ongoing mucosal immune response in presensitized murine model of allergic rhinitis.

Allergic rhinitis is thought to be mediated by CD4+ T cells producing Th2-associated cytokines. Optimal Ag-specific T-cell activation requires the engagement of T-cell receptor with antigen (Ag) in the context of MHC, and the engagement of appropriate costimulatory molecules. One of the most well-characterized costimulatory pathways is the interaction of B7/CD28-CTLA4 molecules. Recent studies have suggested that the costimulatory pathway may influence the development of Th2 immune responses. The objective of this study was the examination of the role of B7/CD28-CTLA4 costimulatory pathway in the pathogenesis of ovalbumin (OVA)-induced immune response in presensitized murine model of allergic rhinitis. Systemically presensitized BALB/c mice significantly developed Ag-induced early phase nasal symptoms, nasal hyperresponsiveness to histamine, nasal eosinophilia, serum levels of OVA- specific IgE and Th2-associated cytokines following repeated topical Ag challenges. Topical administration of CTLA4-Ig during nasal challenges inhibited Ag-induced nasal symptoms and histamine hyperresponsiveness. We also found a significant reduction in nasal lavage eosinophilia and serum levels of OVA-specific IgE. Furthermore, CTLA4-Ig treatment significantly decreased interleukin (IL)-4 content in nasal tissue, while there was no significant change in IL-5 or IFN-gamma levels. These results suggest that B7/CD28-CTLA4 costimulatory pathway mediates the development of ongoing Th2 immune responses and plays a major role in regulating allergic disease, such as allergic rhinitis.     

Dissociation of airway hyperresponsiveness from immunoglobulin E and airway eosinophilia in a murine model of allergic asthma.

Nonspecific airway hyperresponsiveness (AHR) is a hallmark of human asthma. Both airway eosinophilia and high serum levels of total and antigen-specific immunoglobulin E (IgE) are associated with AHR. It is unclear, however, whether either eosinophilia or increased IgE levels contribute directly to, or predict, the development of AHR. Investigations conducted with various murine models of asthma and different mouse strains have resulted in conflicting evidence about the roles that IgE and airway eosinophilia play in the manifestation of AHR. We show that systemic priming with ovalbumin (OVA) in alum, followed by a single day of OVA aerosol challenge, is sufficient to induce AHR, as measured by increased pulmonary resistance in response to intravenously delivered methacholine in BALB/c, but not C57BL/6 or B6D2F1, mice. This was observed despite the fact that OVA-challenged BALB/c mice had less airway eosinophilia and smaller increases in total IgE than either C57BL/6 or B6D2F1 mice, and had less pulmonary inflammation and OVA-specific IgE than B6D2F1 mice. We conclude that airway eosinophilia, pulmonary inflammation, and high serum levels of total or OVA-specific IgE are all insufficient to induce AHR in C57BL/6 and B6D2F1 mice, whereas BALB/c mice demonstrate AHR in the absence of airway eosinophilia. These data confirm that the development of AHR is genetically determined, not only in naive mice, but also in actively immunized ones, and cannot be predicted by levels of airway eosinophilia, pulmonary inflammation, total IgE, or antigen-specific IgE.     

Upon prolonged allergen exposure IL-4 and IL-4Ralpha knockout mice produce specific IgE leading to anaphylaxis

BACKGROUND: IL-4 and IL-13 are key regulators in atopic disorders and both signal through the receptor chain IL-4Ralpha. IL-4 and IL-13 are also the only cytokines known to induce class switching to IgE. We sought to compare allergen-specific IgE responses and allergic reactivity of wild-type (wt) mice with IL-4-/- and IL-4Ralpha-/- mice, which lack both IL-4 and IL-13 functions. METHODS: BALB/c wt, IL-4-/- and IL-4Ralpha-/- mice were immunized with ovalbumin intranasally or intraperitoneally and specific antibody titers were measured by ELISA. Bronchoalveolar lavage fluids and lung tissue were analyzed cytologically and histologically. Allergic reactivity was determined by active cutaneous anaphylaxis and anaphylactic shock. RESULTS: wt mice immunized intranasally or intraperitoneally showed high titers of specific IgE 3 and 6 weeks after primary sensitization, resulting in cutaneous anaphylaxis and anaphylactic shock upon challenge. Intranasal sensitization resulted in airway eosinophilia and goblet cell metaplasia. In contrast, IL-4-/- and IL-4Ralpha-/- mice showed no specific IgE after 3 weeks, but produced high titers after 6 weeks. At this time cutaneous anaphylaxis and anaphylactic shock could be induced as in wt mice, but lung pathology was absent. CONCLUSIONS: We conclude that upon long-term allergen exposure, alternative switch mechanisms independent of IL-4 and IL-4Ralpha may induce IgE but not asthma-like lung pathology. This may be relevant for the development of allergic disease, since long-term allergen exposure is a frequent condition during allergic sensitization.     

IL-15 prevents allergic rhinitis through reactivation of antigen-specific CD8+ cells

BACKGROUND: Allergic rhinitis is one of the most common allergic inflammatory diseases characterized by a predominant TH2 response with antigen-specific IgE synthesis. IL-15 plays important roles in activation and maintenance of memory CD8+T cells capable of producing IFN-gamma, which regulates TH2 responses. OBJECTIVE: To investigate the roles of endogenous IL-15 in allergic inflammation, we examined allergic rhinitis in IL-15 knockout (KO) mice sensitized with ovalbumin followed by intranasal rechallenge with ovalbumin. METHODS: IL-15KO mice were sensitized intraperitoneally with ovalbumin/complete Freund's adjuvant on day 0 and ovalbumin/IFA on day 7, and then were intranasally challenged with ovalbumin on days 21, 22, 23, 24, and 25. Nasal symptoms and histologic changes were examined. IgE production and TH2 responses were measured by ELISA. Purified CD8+T cells or recombinant IL-15 were administered into ovalbumin-sensitized mice. RESULTS: The levels of IgE production and TH2 responses in IL-15KO mice were comparable to those in control mice after ovalbumin sensitization. However, sneezing, infiltration of eosinophils into the nasal mucosa, and TH2 cytokine production were aggravated in ovalbumin-sensitized IL-15KO mice after intranasal challenge with ovalbumin. Adoptive transfer of CD8+6 T cells from ovalbumin-sensitized mice suppressed the TH2 responses in mice but not in IL-15KO mice. Administration of IL-15 with ovalbumin significantly prevented the development of allergic rhinitis in ovalbumin-sensitized mice. CONCLUSION: We demonstrate with IL-15KO mice that endogenous IL-15 plays an important role in suppression of allergic rhinitis at effector phase. Intranasal administration of IL-15 is useful as a therapeutic approach to control allergic rhinitis. CLINICAL IMPLICATIONS: Intranasal administration of recombinant IL-15 might become new immunotherapy for allergic rhinitis.     

TNF-alpha contributes to the development of allergic rhinitis in mice

BACKGROUND: Allergic rhinitis is an inflammation involving T(H)2-type cytokine production, with pathologic eosinophil infiltration in the nasal mucosa. Although TNF-alpha is thought to be a pro-inflammatory cytokine, the relationship between TNF-alpha and allergic rhinitis has not been clarified. OBJECTIVES: The role of TNF-alpha in a murine model of ovalbumin (OVA)-sensitized allergic rhinitis was investigated by using mice deficient in the gene encoding TNF-alpha (TNF-alpha(-/-) mice). METHODS: Both wild-type (TNF-alpha(+/+)) and TNF-alpha(-/-) mice were sensitized with OVA by means of intraperitoneal injection. They were then challenged with intranasal OVA, and various allergic responses were assessed. RESULTS: The production of OVA-specific IgE in the serum (P <.05) and the frequency of sneezes (P <.05) and nasal rubs (P <.05) decreased significantly in TNF-alpha(-/-) mice after OVA sensitization compared with that in TNF-alpha(+/+) mice (P <.05). The mRNA expression of IL-4, IL-10, and eotaxin in nasal mucosa in TNF-alpha(-/-) mice was also significantly suppressed compared with that in TNF-alpha(+/+) mice after OVA sensitization (P <.05). Furthermore, the expression of both endothelial-leukocyte adhesion molecule 1 and vascular cell adhesion molecule 1 mRNA in the nasal mucosa was significantly suppressed (P <.05), although intercellular adhesion molecule 1 mRNA expression did not decrease significantly in TNF-alpha(-/-) mice compared with that in TNF-alpha(+/+) mice after OVA sensitization. In addition, the effect of TNF-alpha on endothelial-leukocyte adhesion molecule 1 and vascular cell adhesion molecule 1 expression by means of Western blot analysis was compatible with the mRNA results. Pathologically, eosinophil infiltration in nasal mucosa was significantly restricted in TNF-alpha(-/-) mice compared with in TNF-alpha(+/+) mice after OVA sensitization (P <.05). CONCLUSION: TNF-alpha is necessary for antigen-specific IgE production and for the induction of T(H)2-type cytokines and chemokines. Furthermore, TNF-alpha might be important for the expression of adhesion molecules to recruit eosinophils to the allergic inflammatory site. We conclude that the lack of TNF-alpha inhibited the development of allergic rhinitis.     

An essential role for dendritic cells in human and experimental allergic rhinitis

BACKGROUND: In allergic rhinitis (AR) CD4(+) T(H)2 lymphocytes control inflammation by secreting T(H)2 cytokines, but little is known about how these cells are activated to cause disease. OBJECTIVE: We sought to study the contribution of antigen-presenting dendritic cells (DCs) in activating T(H)2 cells and controlling allergic inflammation. METHODS: Nasal mucosal biopsy specimens were taken from patients with house dust mite allergy and perennial AR and healthy control subjects. DC numbers were evaluated by using immunohistochemistry. The functional role of DCs was studied in a novel mouse model for AR using BALB/c mice and CD11c-diphtheria toxin (DT) receptor transgenic mice. RESULTS: In symptomatic patients with perennial AR, the number of CD1a(+) and CD11c(+) MHCII(+) DCs was higher in the epithelium and lamina propria of the nasal mucosa compared with that seen in healthy control subjects. In patients with AR, DCs had a more mature (CD86(+)) phenotype and were found in close approximation with T lymphocytes. Similarly, in a mouse model of ovalbumin (OVA)-induced AR, CD11c(+) DCs accumulated in areas of nasal eosinophilic inflammation and clustered with CD4(+) T lymphocytes. CD11c(+) DCs were conditionally depleted during allergen challenge by means of systemic administration of DT to CD11c-diphtheria toxin receptor transgenic mice to address the functional role of DCs in maintaining inflammation. In the absence of CD11c(+) DCs, nasal OVA challenge in OVA-sensitized mice did not induce nasal eosinophilia and did not boost OVA-specific IgE levels or T(H)2 cytokine production in the cervical lymph nodes. Conversely, when OVA-pulsed DCs were administered intranasally to sensitized mice, they strongly enhanced OVA-induced nasal eosinophilia and T(H)2 cytokine production. CONCLUSIONS: These data in human subjects and mice suggest an essential role for nasal DCs in activation of effector T(H)2 function leading to AR. CLINICAL IMPLICATIONS: Nasal DCs play an essential role in AR and therefore constitute a novel target for therapeutic intervention.     

The effects of montelukast on tissue inflammatory and bone marrow responses in murine experimental allergic rhinitis: interaction with interleukin-5 deficiency

The cysteinyl leukotrienes (cysLTs) are potent lipid mediators in allergic disease, acting through the receptors, cysLT1R and cysLTR2, and are produced by eosinophils derived from eosinophil/basophil (Eo/B) bone marrow (BM) progenitors. We have demonstrated the suppressive effects of either interleukin-5 (IL-5) deficiency or montelukast on eosinophil recruitment in murine allergic rhinitis, but neither of them fully abrogated the symptoms caused by residual inflammation and cytokine redundancy in eliciting BM Eo/B responses. We hypothesized that IL-5 deficiency and montelukast act synergistically to suppress tissue inflammatory and BM responses. Our objective was to investigate the effects of the cysLT1R antagonist, montelukast, on in vivo tissue inflammatory and BM responses in murine experimental allergic rhinitis with or without IL-5 deficiency. Three groups of age-matched BALB/c mice with or without IL-5 deficiency were tested: controls (ovalbumin sensitization and challenge, placebo treatment) and two montelukast-treated groups (2.5 mg/kg or 5 mg/kg). Nasal symptoms, BM and nasal mucosal eosinophils, basophils, and BM Eo/B colony-forming units (CFU) were evaluated. Montelukast decreased nasal symptoms in a dose-dependent manner, and significantly decreased the number of eosinophils in both BM and nasal tissue in IL-5-replete mice compared to controls. In IL-5-deficient mice, in which eosinophilia was absent, montelukast significantly decreased both nasal symptoms and basophils in BM and nasal mucosal tissue, and lowered IL-5-responsive Eo/B-CFU ex vivo, compared to controls. The addition of cysLT1R blockade to IL-5 deficiency more fully attenuates symptoms and upper airway inflammation than either factor alone, providing evidence of systemic, BM mechanisms in allergic rhinitis.     

Comparison of adjuvant and adjuvant-free murine experimental asthma models

Introduction The most widely used protocol for the induction of experimental allergic airway inflammation in mice involves sensitization by intraperitoneal (i.p.) injections of the antigen ovalbumin (OVA) used in conjunction with the adjuvant aluminium hydroxide (alum). Although adjuvants are frequently used, there are questions regarding the necessity of alum for murine asthma studies due to the non‐physiological nature of this chemical. Objective The objective of this study was to compare experimental asthma phenotypes between adjuvant and adjuvant‐free protocols of murine allergic airway inflammation in an attempt to develop a standardized alternative to adjuvant use. Method An adjuvant‐free OVA model of experimental asthma was investigated in BALB/c mice using i.p. or subcutaneous (s.c.) sensitization routes. For the s.c. sensitization, β‐galactosidase (β‐gal) was also tested as an antigen. In addition, OVA adjuvant and adjuvant‐free sensitization protocols were compared in BALB/c and C57BL/6 mice. Open‐field testing was performed to assess the effect of alum on mouse behaviour. Results Comparison of adjuvant vs. adjuvant‐free and i.p. vs. s.c. protocols revealed that both adjuvant use and route of antigen application significantly influenced OVA‐specific antibody production. Comparison of adjuvant and adjuvant‐free protocols in this study clearly demonstrated the non‐requirement of alum for the induction of acute allergic airway inflammation, as both protocols induce a similar disease phenotype. BALB/c mice were significantly more susceptible than C57BL/6 mice to sensitization. Using the improved s.c. adjuvant‐free protocol, it was demonstrated that alternative antigens such as β‐gal can also be utilized. Behavioural studies indicated severe distress in mice treated with alum. Conclusion The OVA s.c. adjuvant‐free protocol used in this study generates a phenotype comparable to the benchmark adjuvant protocol widely used in the literature. The adjuvant‐free alternative avoids the added complication of non‐physiological adjuvants that may interfere with asthma treatment or prevention strategies.