Administration Of Ovalbumin Research Articles

Enhanced Immune Response of T-cell Independent or Dependent Antigens in SIGN-R1 Knock-Out Mice

Dextran was used to explore a novel method of enhancing an immune response against T-cell independent type 2 (TI-2) polysaccharide antigens, because of its suitability as a model for the immunogenecity of many TI-2 polysaccharide antigens and its high affinity to SIGN-R1. Here we showed that the primary immune response of IgM, IgG3, and IgG2b was enhanced by dextran in SIGN-R1 knock-out (KO) mice, further evoking the induction of a secondary immune response to IgG2b in parallel. On the other hand, an immune response of IgG1 and IgG2b against T-cell dependent (TD) antigen was strongly enhanced by the administration of ovalbumin (OVA) in SIGN-R1 KO mice. These results indicate that SIGN-R1 is critical in the regulation of immune responses. Therefore, our study suggests that inhibition of TI-2 polysaccharide antigen uptake in SIGN-R1(+) macrophages contributes to the development of novel vaccination strategies against TI-2 polysaccharide antigens.

Anti-inflammatory effects of tilmicosin in a noninfectious mouse model of allergic asthma

Tilmicosin, a semi-synthetic tylosin-derived macrolide antibiotic commonly used by veterinarians, has been shown to possess anti-inflammatory activity. However, possible use in asthma treatment has not yet been studied. In this study, we investigated the anti-inflammatory properties of tilmicosin using a murine asthma model. BALB/c mice were sensitized and challenged by intraperitoneal (i.p.) or nasal administration of ovalbumin. Tilmicosin (10 and 20 mg/kg) treatment resulted in a marked reduction in the presence of several types of immune cells and cytokines in the bronchoalveolar lavage fluids of mice. Levels of ovalbumin-specific Immunoglobulin E (IgE) were significantly decreased following treatment with tilmicosin (10 and 20 mg/kg). Histological studies using H&E (haematoxylin and eosin) and AB-PAS (alcian blue-periodic acid-Schiff) staining demonstrated that tilmicosin substantially inhibited both ovalbumin-induced inflammatory cells in lung tissues and goblet cell hyperplasia in the airway. These findings provided new insight into the immunopharmacological role of tilmicosin in terms of its effects in a murine model of asthma.

Rectal Administration of Lipopolysaccharide and Ovalbumin Ameliorates Acute Murine Colitis

Repeated challenges of lipopolysaccharide (LPS) could reduce the expression of proinflammatory cytokines in vitro, and oral administration of ovalbumin (OVA) induces mucosal tolerance in vivo. However, the effect of local administration of LPS and OVA on experimental colitis in vivo remains unknown. This study was performed to elucidate the effect of rectal administration of LPS and OVA on an acute murine colitis induced by dextran sulfate sodium (DSS). BALB/c mice were rectally administered LPS with or without OVA followed by 3% DSS. Colitis was assessed by disease activity index (DAI) including weight loss, stool consistency and rectal bleeding, and histopathology. Primary colon epithelial cells were isolated and the expression of Toll-like receptor 4 (TLR4) was examined using the Western blot analysis. IL-6, IFN-γ and IL-10 mRNA levels in colonic tissue were assessed using real-time RT-PCR. LPS administration significantly attenuated the severity of acute DSS-induced colitis as assessed by DAI and histopathologic scoring compared with the control group. Combined treatment of LPS and OVA restored body weight loss and further ameliorated the severity of acute DSS colitis. LPS pretreatment regardless of OVA administration decreased TLR4 expression. LPS and OVA pretreatment reduced IL-6 and IFN-γ mRNA expression and increased IL-10 mRNA expression compared with controls. Rectal administration of LPS attenuated acute murine colitis, possibly through TLR4 down-regulation, and combined treatment of OVA additionally ameliorated colonic inflammation associated with up-regulation of IL-10.

Effects of appendectomy and oral tolerance on dextran sulfate sodium colitis

To evaluate the concomitant effects of appendectomy and oral tolerance on colitis. Delayed-type hypersensitivity (DTH) was investigated at a 7-d interval after ovalbumin (OVA) administration and immunization under normal and colitis conditions in appendectomized or sham-operated mice. Pathological scores for the colon were graded after ingestion of colon-extracted protein (CEP) and induction of dextran sulfate sodium (DSS) colitis in appendectomized or sham-operated mice. Thereafter, Th1 and Th2 in Peyer's patches and spleen lymphocytes were detected in CEP-treated and bovine serum albumin (BSA)-treated control mice. In appendectomized mice, DTH was not inhibited at day 7 after OVA administration and at the initial phase of DSS colitis, whereas it was inhibited at day 14 and day 21. However, in sham-operated mice, it was inhibited during the whole procedure and the onset of DSS colitis. The protective role of CEP against DSS colitis was present in sham-operated mice, with predominant improvement of colonic pathological changes, while vanished in the appendectomized mice. A shift from Th1 to Th2 in Peyer's patches resulted from a decrease of Th1 cells with the ingestion of CEP. Compared with BSA in the sham-operated group, no predominant changes were observed in the appendectomized mice. Appendectomy interferes with the protective role of CEP in DSS colitis via a shift from Th2 to Th1 during oral tolerance induction.

Role of Cdk4 in lymphocyte function and allergen response

We recently described a new adhesion pathway in lymphocytes that is dependent on Cyclin-dependent kinase (Cdk) 4 activity and mediates lymphocyte interactions with endothelial matrix. We showed that Cdk4-/- mice had impaired recruitment of lymphocytes following bleomycin model of acute lung injury. In this study, we characterized the development and function of hematopoietic cells in Cdk4-/- mice and assessed the response of Cdk4-/- mice to allergen challenge. Cdk4-/- mice had hypoplastic thymuses with decreased total thymocyte cell numbers and increased CD4/CD8 double negative cells. Cdk4-/- bone marrow (BM) chimeric mice showed similar findings. Thymocytes from either Cdk4-/- or Cdk4-/- BM chimeric mice proliferated equally well as wild type controls in response to IL-2 activation. However Cdk4-/- thymocytes had decreased adhesion to both endothelial cell matrix and fibronectin compared to wildtype (WT) controls, whereas Cdk4-/- and WT splenocytes had similar adhesion. When Cdk4-/- BM chimeric mice and wild type BM chimeric mice were sensitized and challenged by intranasal administration of ovalbumin, we found no differences in allergic responses in the lung and airways between the two groups, as measured by inflammatory cell infiltrate, airway hyperreactivity, IgE levels and cytokine levels. In summary, we show that Cdk4 plays a previously unrecognized role in thymocyte maturation and adhesion, but is not required for thymocyte proliferation. In addition, Cdk4 is not required for lymphocyte trafficking to the lung following allergen sensitization and challenge.

Gut colonization byCandida albicansaggravates inflammation in the gut and extra-gut tissues in mice

We examined whether Candida albicans gut colonization aggravates immune diseases in mice. Chronic and latent C. albicans gut colonization was established by the intragastric inoculation of C. albicans in mice fed as part of a purified diet. Allergic diarrhea was induced by repetitive intragastric administration of ovalbumin in sensitized BALB/c mice. Contact hypersensitivity was evaluated by measuring ear swelling after topical application of 2, 4-dinitrofluorobenzene in NC/Nga mice. Arthritis was induced by intradermal injection of bovine type-II collagen emulsified with complete Freund's adjuvant in DBA/1J mice. C. albicans gut colonization increased the incidence of allergic diarrhea, which was accompanied by gut hyperpermeability, as well as increased infiltration of inflammatory cells in the colon. Contact hypersensitivity was also exacerbated by C. albicans gut colonization, as demonstrated by increased swelling, myeloperoxidase activity, and proinflammatory cytokines in ear auricles. Furthermore, C. albicans gut colonization promoted limb joint inflammation in collagen-induced arthritis, in an animal model of rheumatoid arthritis. These findings suggest that C. albicans gut colonization in mice aggravates inflammation in allergic and autoimmune diseases, not only in the gut but also in the extra-gut tissues and underscores the necessity of investigating the pathogenic role of C. albicans gut colonization in immune diseases in humans.

Effect of ultrafine zinc oxide (ZnO) nanoparticles on induction of oral tolerance in mice

Ultrafine nanoparticles of zinc oxide (ZnO) recently became available as a substitute for larger-size fine ZnO particles. However, the biological activity of ultrafine ZnO currently remains undefined. In the present study, we investigated the effect of ultrafine ZnO on oral tolerance that plays an important role in the prevention of food allergy. Oral tolerance was induced in mice by a single oral administration (i.e., gavage) of 25 mg of ovalbumin (OVA) 5 days prior to a subcutaneous immunization with OVA (Day 0). Varying doses of ultrafine (diameter: ≈ 21 nm) as well as fine (diameter: < 5 µm) ZnO particles were given orally at the same time during the OVA gavage. The results indicated that a single oral administration of OVA was followed by significant decreases in serum anti-OVA IgG, IgG1, IgG2a, and IgE antibodies and in the proliferative responses to the antigen by these hosts’ spleen cells. The decreases in these immune responses to OVA were associated with a marked suppression of secretion of interferon (IFN)γ, interleukin (IL)-5, and IL-17 by these lymphoid cells. Treatment with either ultrafine or fine ZnO failed to affect the oral OVA-induced suppression of antigen-specific IgG, IgG1, IgG2a, and IgE production or lymphoid cell proliferation. The suppression induced by the oral OVA upon secretion of IFNγ, IL-5, and IL-17 was also unaffected by either size of ZnO. These results indicate that ultrafine particles of ZnO do not appear to modulate the induction of oral tolerance in mice.

The phosphodiesterase 4 inhibitor AWD 12–281 is active in a new guinea-pig model of allergic skin inflammation predictive of human skin penetration and suppresses both Th1 and Th2 cytokines in mice

The selective phosphodiesterase 4 (PDE4) inhibitor AWD 12-281 is structurally optimized for topical administration. It has potent effects in models of lung inflammation if administered as a dry powder inhalation. It has also demonstrated its anti-inflammatory property in a mouse model of cutaneous inflammation after topical administration. The aim of this study was to evaluate whether AWD 12-281 may be capable of penetrating human skin. Therefore a new guinea-pig model of allergic skin inflammation had to be developed. In ovalbumin-sensitized guinea-pigs, intracutaneous administration of ovalbumin results in a rapid development of allergic skin wheals. Topically administered AWD 12-281 was capable of reducing the development of wheals, indicating that this compound can penetrate the stratum corneum of guinea-pig skin as a predictor of human skin penetration. A secondary aim was the evaluation of a T cell subtype preference of AWD 12-281 since PDE4 inhibitors are said to preferentially inhibit Th2-type cytokines. Therefore, the effects of AWD 12-281 on a broad spectrum of Th1- and Th2-type cytokines were studied in tissue homogenates after allergen challenge in sensitized mice and in supernatants of anti CD3/anti-CD28-stimulated peripheral blood mononuclear cells (PBMCs). In both models, AWD 12-281 suppressed both T cell subtype cytokines indicating a broad spectrum activity of AWD 12-281. A further issue was to determine the duration of action and the concentration-response relationship of the topical activity of AWD 12-281 using a model of acute local inflammation--the arachidonic-acid-induced mouse ear oedema. The compound exhibited a dose-dependent effect with a minimally effective concentration of 0.3%; after repeated administration the minimally effective concentration was found to be 0.03%. A single administration of a 3% solution resulted in significant suppression of inflammation even 48 h after treatment. In conclusion, our results indicate that AWD 12-281 is a very promising drug candidate not only for the treatment of lung inflammation using inhalative administration but also for the treatment of atopic dermatitis.

Expression of the Foxp3 Gene in Spleen Mononuclear Cells of a Mouse Model with Allergic Rhinitis

Objective: There is growing speculation that the impairment inregulatory-T-cell (Treg)-mediated dominant tolerance may play an important role in the pathogenesis of allergic rhinitis (AR). The aim of this study was to investigate whether the changes in the forkhead transcription factor 3 (Foxp3) gene expression may aggravate nasal mucosal inflammation in allergic mice, and whether or not these features result from the loss of Tregs. Methods: AR was induced by both intraperitoneal injection and intranasal administration of ovalbumin in BALB/c mice, while the control mice were treated with saline. A comparison of the frequency of CD4⁺CD25⁺Foxp3⁺ Tregs in peripheral blood mononuclear cells of the AR and control mice was made by flow cytometry. Spleen mononuclear cells were used for RNA extraction and RT-PCR was used to measure Foxp3 mRNA expression. Results: The expression of the Foxp3 gene was significantly reduced in spleen mononuclear cells in AR mice compared with the control. Moreover, a significant decrease in the percentage of CD4⁺CD25⁺Foxp3⁺ Tregs was exhibited in peripheral blood mononuclear cells of AR mice compared with the control mice. Conclusion: The insufficiency of Tregs and the Foxp3 gene may contribute to the development of AR in mice.

Adjuvant effect of zinc oxide on Th2 but not Th1 immune responses in mice

Background and aim: We investigated the effect of zinc oxide (ZnO) on Th1 and Th2 immune responses in mice.Material and methods: Mice were intraperitoneally administered with ovalbumin (OVA) with or without varying doses of ZnO (day 0). On day 21, anti-OVA IgG, IgG2a, IgG1, and IgE antibodies in sera, OVA-specific proliferative responses of spleen cells, and production of Th1 cytokines including IFN-γ as well as Th2 cytokines such as IL-4 and IL-5 were measured.Results: The results showed that administration of OVA with ZnO was followed by greater increases in anti-OVA IgG and the antigen-specific splenocyte proliferation compared to that of OVA alone. The production of anti-OVA IgG1 and IgE and secretion of IL-4 and IL-5 were markedly enhanced by ZnO. The enhancing effect of ZnO on these Th2 responses was as strong as aluminium hydroxide (Alum) that was widely used as an adjuvant. In contrast, treatment with OVA plus ZnO failed to affect production of anti-OVA IgG2a as well as IFN-γ. It was also observed that ZnO had a stimulating effect on the secretion of the proinflammatory cytokine IL-17 from a new lineage of effector Th cells.Conclusion: These results suggest that ZnO appears to have an adjuvant effect on the immune system, especially Th2 but not Th1 immune responses.

Therapeutic effects of mucosal tolerance on experimental colitis in rats

To analyze the therapeutic effect of oral tolerance and nasal tolerance singly and in combination with mucosal adjuvant on experimental colitis in rats. Rat models were established using trinitrobenzenesulphonic acid enemas. Ovalbumin was used as inducing antigen and lipopolysaccharide as adjuvant. Colonic scores, splenic mononuclear cell proliferation, and expressions of Toll-like receptors (TLR) and regulatory T cells were determined. Colonic scores decreased most significantly after ovalbumin and lipopolysaccharide nasal administration (P<0.05). Colonic expression of forkhead box P3 in rats after ovalbumin and lipopolysaccharide oral (P<0.05) and nasal administration (P<0.01) were both significantly higher than untreated rats. TLR2 expression on CD4(+)CD25(+) T cells decreased most significantly after ovalbumin and lipopolysaccharide nasal therapies (P<0.01). TLR4 colonic expression decreased significantly after ovalbumin and lipopolysaccharide oral administration (P<0.05) and lipopolysaccharide oral administration (P<0.05). Although experimental colitis prevented oral tolerance, nasal tolerance was successfully induced. The therapeutic effect of nasal tolerance combined with adjuvant produced the best results. TLR downregulation and CD4(+)CD25(+) T cells upregulation were involved in mucosal tolerance.

Comparison of gut microbiota and allergic reactions in BALB/c mice fed different cultivars of rice

Our preliminary clinical trial showed that consumption of cooked rice of a Japanese common cultivar Yukihikari improved atopic dermatitis associated with a suspected rice allergy, although the underlying mechanisms remain unclear. We hypothesised that the ameliorating effect of Yukihikari on atopic dermatitis is associated with the gut microbiota. BALB/c mice were fed a synthetic diet supplemented with uncooked and polished white rice powder prepared from one of four different cultivars: Yukihikari, rice A (common rice), rice B (brewery rice) and rice C (waxy rice). Denaturing gradient gel electrophoresis of PCR-amplified 16S rRNA gene fragments showed that the composition of faecal microbiota was different between mice fed Yukihikari and those fed rice A. Analysis of the 16S rRNA clone library and species-specific real-time PCR showed that the abundance of Akkermansia muciniphila, a mucin degrader, tended to be lower in mice fed Yukihikari. The incidence of allergic diarrhoea induced by oral administration of ovalbumin in systemically immunised mice was lower in mice fed Yukihikari, albeit with no difference in serum antibodies specific to ovalbumin. In a separate experiment, serum antibody levels specific to orally administered ovalbumin were lower in mice fed Yukihikari. Additionally, the translocation of horseradish peroxidase in isolated segments of ileum and colon tended to be lower in mice fed Yukihikari, suggesting a reduction in gut permeability in mice fed Yukihikari. These data indicate that changes in the gut microbiota of mice fed Yukihikari could be advantageous in the prevention of food allergy.

Topical resiquimod promotes priming of CTL to parenteral antigens

We explored the topical use of resiquimod (R-848), a Toll-like receptor (TLR) 7/8 agonist, in gel formulation, to enhance cross-priming to subcutaneously administered protein antigen in a murine model. Resiquimod application at the time of subcutaneous administration of ovalbumin generated robust antigen-specific CTL as detected by tetramers, IFN-γ ELISPOT assays and standard cytotoxicity assays. Induced CTL were capable of mediating antigen-specific killing in vivo as measured by in vivo cytotoxicity assays and an ability to protect against B16-OVA tumor challenge. Multiple serial applications of topical resiquimod increased the frequency of antigen-specific CTL when compared to single application. This enhanced frequency was noted despite a marked inhibition of adjuvant mediated pro-inflammatory cytokine release following repeated administration. Topical resiquimod is a potent adjuvant for locally administered subcutaneous vaccines, inducing clinically relevant CTL responses following single application at the time of subcutaneous vaccination.

Basophils contribute to TH2-IgE responses in vivo via IL-4 production and presentation of peptide–MHC class II complexes to CD4+ T cells

Basophils express major histocompatibility complex class II, CD80 and CD86 and produce interleukin 4 (IL-4) in various conditions. Here we show that when incubated with IL-3 and antigen or complexes of antigen and immunoglobulin E (IgE), basophils internalized, processed and presented antigen as complexes of peptide and major histocompatibility complex class II and produced IL-4. Intravenous administration of ovalbumin-pulsed basophils into naive mice 'preferentially' induced the development of naive ovalbumin-specific CD4+ T cells into T helper type 2 (T(H)2) cells. Mice immunized in this way, when challenged by intravenous administration of ovalbumin, promptly produced ovalbumin-specific IgG1 and IgE. Finally, intravenous administration of IgE complexes rapidly induced T(H)2 cells only in the presence of endogenous basophils, which suggests that basophils are potent antigen-presenting cells that 'preferentially' augment T(H)2-IgE responses by capturing IgE complex.

Targeting nanoparticles to M cells with non-peptidic ligands for oral vaccination

The presence of RGD on nanoparticles allows the targeting of β1 integrins at the apical surface of human M cells and the enhancement of an immune response after oral immunization. To check the hypothesis that non-peptidic ligands targeting intestinal M cells or APCs would be more efficient for oral immunization than RGD, novel non-peptidic and peptidic analogs (RGD peptidomimitic (RGDp), LDV derivative (LDVd) and LDV peptidomimetic (LDVp)) as well as mannose were grafted on the PEG chain of PCL–PEG and incorporated in PLGA-based nanoparticles. RGD and RGDp significantly increased the transport of nanoparticles across an in vitro model of human M cells as compared to enterocytes. RGD, LDVp, LDVd and mannose enhanced nanoparticle uptake by macrophages in vitro. The intraduodenal immunization with RGDp-, LDVd- or mannose-labeled nanoparticles elicited a higher production of IgG antibodies than the intramuscular injection of free ovalbumin or intraduodenal administration of either non-targeted or RGD-nanoparticles. Targeted formulations were also able to induce a cellular immune response. In conclusion, the in vitro transport of nanoparticles, uptake by macrophages and the immune response were positively influenced by the presence of ligands at the surface of nanoparticles. These targeted-nanoparticles could thus represent a promising delivery system for oral immunization.

Effects of umbelliferone in a murine model of allergic airway inflammation

The therapeutic effects of umbelliferone (30, 60 and 90 mg/kg), a coumarin isolated from Typha domingensis (Typhaceae) were investigated in a mouse model of bronchial asthma. BALB/c mice were immunized and challenged by nasal administration of ovalbumin. Treatment with umbelliferone (60 and 90 mg/kg) caused a marked reduction of cellularity and eosinophil numbers in bronchoalveolar lavage fluids from asthmatic mice. In addition, a decrease in mucus production and lung inflammation were observed in mice treated with umbelliferone. A reduction of IL-4, IL-5, and IL-13, but not of IFN-γ, was found in bronchoalveolar lavage fluids of mice treated with umbelliferone, similar to that observed with dexamethasone. The levels of ovalbumin-specific IgE were not significantly altered after treatment with umbelliferone. In conclusion, our results demonstrate that umbelliferone attenuates the alteration characteristics of allergic airway inflammation. The investigation of the mechanisms of action of this molecule may contribute for the development of new drugs for the treatment of asthma.

Antigen-primed splenic CD8+ T cells impede the development of oral antigen–induced allergic diarrhea

Although CD4+ T-cell populations are thought to be involved in the pathophysiology of food allergy and oral tolerance, the role of CD8+ T cells remains uncertain. We analyzed regulatory effects of adoptively transferred CD8+ T cells on the development of allergic diarrhea in antigen-sensitized mice that had a significantly reduced number of conventional TCRalphabeta+ CD8+ T cells. Ovalbumin-specific T-cell receptor transgenic mice were systemically sensitized to ovalbumin. Splenic CD8+ T cells purified from ovalbumin-sensitized or nonsensitized wild-type mice or IL-10 knockout mice were adoptively transferred to ovalbumin-sensitized ovalbumin-specific T-cell receptor transgenic mice. Allergic diarrhea induced by oral administration of ovalbumin, ovalbumin-specific immunoglobulin production, and cytokine production in intestines and mesenteric lymph nodes were assessed. Adoptive transfer of splenic CD8+ T cells from ovalbumin-primed mice, but not from nonprimed mice, suppressed the development of allergic diarrhea, which was associated with in vivo increased IL-10 mRNA expression and in vitro antigen-specific IL-10 production by mesenteric lymph node cells. Upregulation of serum ovalbumin-specific IgE was not suppressed by ovalbumin-primed CD8+ T-cell transfer. Although administration of IL-10 before ovalbumin challenge failed to alleviate allergic diarrhea, transfer of splenic CD8+ T cells from IL-10 knockout mice showed diminished preventive effects. Systemic immunization with allergen simultaneously induces regulatory CD8+ T cells that can inhibit the development of allergic diarrhea. IL-10 production by regulatory CD8+ T cells appears to be partially involved in these inhibitory mechanisms.

Impairing oral tolerance promotes allergy and anaphylaxis: A new murine food allergy model

Food allergy is a disorder in which antigenic food proteins elicit immune responses. Animal models of food allergy have several limitations that influence their utility, including failure to recapitulate several key immunologic hallmarks. Consequently, little is known regarding the pathogenesis and mechanisms leading to food allergy. Staphylococcus aureus-derived enterotoxins, a common cause of food contamination, are associated with antigen responses in atopic dermatitis. We hypothesized that S aureus-derived enterotoxins might influence the development of food allergy. We examined the influence of administration of staphylococcal enterotoxin B (SEB) with food allergens on immunologic responses and compared these responses with those elicited by a cholera toxin-driven food allergy model. Oral administration of ovalbumin or whole peanut extract with or without SEB was performed once weekly. After 8 weeks, mice were challenged with oral antigen alone, and the physiologic and immunologic responses to antigen were studied. SEB administered with antigen resulted in immune responses to the antigen. Responses were highly T(H)2 polarized, and oral challenge with antigen triggered anaphylaxis and local and systemic mast cell degranulation. SEB-driven sensitization induced eosinophilia in the blood and intestinal tissues not observed with cholera toxin sensitization. SEB impaired tolerance specifically by impairing expression of TGF-beta and regulatory T cells, and tolerance was restored with high-dose antigen. We demonstrate a new model of food allergy to oral antigen in common laboratory strains of mice that recapitulates many features of clinical food allergy that are not seen in other models. We demonstrate that SEB impairs oral tolerance and permits allergic responses.

Oral dendritic cells mediate antigen-specific tolerance by stimulating T H1 and regulatory CD4 + T cells

A detailed characterization of oral antigen-presenting cells is critical to improve second-generation sublingual allergy vaccines. To characterize oral dendritic cells (DCs) within lingual and buccal tissues from BALB/c mice with respect to their surface phenotype, distribution, and capacity to polarize CD4(+) T-cell responses. In situ analysis of oral DCs was performed by immunohistology. Purified DCs were tested in vitro for their capacity to capture, process, and present the ovalbumin antigen to naive CD4(+) T cells. In vivo priming of ovalbumin-specific T cells adoptively transferred to BALB/c mice was analyzed by cytofluorometry in cervical lymph nodes after sublingual administration of mucoadhesive ovalbumin. Three subsets of oral DCs with a distinct tissue distribution were identified: (1) a minor subset of CD207(+) Langerhans cells located in the mucosa itself, (2) a major subpopulation of CD11b(+)CD11c(-) and CD11b(+)CD11c(+) myeloid DCs at the mucosal/submucosal interface, and (3) B220(+)120G8(+) plasmacytoid DCs found in submucosal tissues. Purified myeloid and plasmacytoid oral DCs capture and process the antigen efficiently and are programmed to elicit IFN-gamma and/or IL-10 production together with a suppressive function in naive CD4(+) T cells. Targeting the ovalbumin antigen to oral DCs in vivo by using mucoadhesive particles establishes tolerance in the absence of cell depletion through the stimulation of IFN-gamma and IL-10-producing CD4(+) regulatory T cells in cervical lymph nodes. The oral immune system is composed of various subsets of tolerogenic DCs organized in a compartmentalized manner and programmed to induce T(H)1/regulatory T-cell responses.

Allergen-induced Lung Inflammation in Actively Sensitized Mice Assessed with MR Imaging

To demonstrate the feasibility of using proton magnetic resonance (MR) imaging to noninvasively detect extravascular and luminal fluid in a murine model of allergen-induced airway inflammation. The Basel Veterinary Authority approved this experiment. Actively sensitized female Balb/c mice received ovalbumin or saline and underwent MR imaging (a) once 24 hours after the fourth administration of ovalbumin or saline (n = 25) or (b) several times between and after ovalbumin or saline administrations (n = 22) to determine the volume of fluid signal induced by an allergen. Images were acquired in spontaneously breathing animals, without cardiac or respiratory gating. Signal detected with a gradient-echo sequence was compared with bronchoalveolar lavage (BAL) fluid parameters and with perivascular and peribronchial edema and mucus observed at histologic analysis. Up to 24 hours after the fourth administration of ovalbumin, intense and continuous fluid signals (volume, 40-50 microL) were detected in proximal lung regions. At 72 hours after the fourth administration of ovalbumin, remaining signals (21.1 microL +/- 3.8) had a discontinuous texture. The number of eosinophils in the BAL fluid at 24 and 72 hours and their activation were higher in mice that received ovalbumin than in those that received saline. Histologic analysis revealed edema and secreted mucus in the early phase, whereas only mucus was encountered in the late phase. These findings suggest that the main component of the early response was plasma leakage (edema), while the main component of the late response was secreted mucus. With the technique validated, the basis for pharmacologic studies in this murine model of lung inflammation with use of MR imaging as a noninvasive readout was provided.