Aqueous extract of peanut skin and its main constituent procyanidin A1 suppress serum IgE and IgG1 levels in mice-immunized with ovalbumin

In this study, we investigated the effects of an aqueous extract of peanut (Arachis hypogaea L.) seed skin (PSE) and its main constituent procyanidin A1 (PA) on the allergic response to allergen ovalbumin (OVA) in a mouse model. Mice immunized interaperitoneally with OVA dramatically increased anti-OVA IgE and total IgG1 levels in serum compared with non-treated control mice. Oral injection of PSE at doses ranging from 10 to 100 mg/kg/d (for 21 consecutive days) decreased anti-OVA IgE and IgG1 levels 21 d after OVA-immunization. OVA-induced increments in spleen weight and peripheral white blood cell count were also suppressed by this PSE administration. Polyphenol-enriched fractions from apple (30 mg/kg) and grape seed (30 mg/kg) also decreased anti-OVA IgE level but did not affect total IgG1 levels. Oral injection of PA (1 to 10 mg/kg/d) purified from PSE resulted in a suppression of IgE and total IgG1 levels in serum. An increment of serum interleukin-4 level in mice that were immunized with OVA was reduced by all tested samples, whereas PSE and PA were the only compounds that could reverse the reduced interferon-gamma level by OVA. These findings suggest that intake of PSE or its main active constituent PA may prevent an allergic reaction by inhibiting immunoglobulin synthesis, and the mechanism of this action of PSE and PA is in part due to their regulation of T helper cytokine production.     

Dichotomous effect of a traditional Japanese medicine, bu-zhong-yi-qi-tang on allergic asthma in mice

To determine the potentiality of prophylactic and/or therapeutic approaches using a traditional herbal medicine, Bu-zhong-yi-qi-tang (Japanese name: Hochu-ekki-to, HOT), for the control of allergic disease, we examined the effects of oral administration of HOT on a murine model of asthma allergic responses. When oral administration of HOT was begun at the induction phase immediately after OVA sensitization, eosinophilia and Th2-type cytokine production in the airway were reduced in OVA-sensitized mice following OVA inhalation. The serum levels of OVA-specific immunoglobulin (Ig)E and IgG1 were significantly decreased, whereas the level of OVA-specific IgG2a was increased. Interleukin (IL)-4 production by spleen T cells in response to OVA was significantly suppressed, while Interferon (IFN)-gamma production was increased in mice treated with HOT in the induction phase. On the other hand, HOT given in the eliciting phase induced a predominant Th2 response with increased IgE production in OVA-sensitized mice following OVA inhalation. These results suggest that the oral administration of HOT dichotomously modulates allergic inflammation in a murine model for asthma, thus offering a different approach for the treatment of allergic disorders.     

Surface-linked liposomal antigen induces IgE selective unresponsiveness in a T-cell independent fashion

We previously reported that surface-linked liposomal antigen induced IgE-selective unresponsiveness. The results were consistent even when different coupling procedures for antigen with liposomes, or for liposomes with different lipid components, were employed. During the course of an investigation intended to clarify the mechanism of IgE-selective unresponsiveness induced by surface-coupled liposomal antigens, we discovered an alternative approach to regulate the production of IgE, one that is independent of the activity of T-cells. Immunization of mice with OVA-liposome conjugates induced IgE- selective unresponsiveness without apparent Th1 polarization. Neither interleukin-12 (IL-12), IL-10, nor CD8(+) T-cells participated in the regulation. Further, CD4(+) T-cells of mice immunized with OVA-liposome were capable of inducing antigen-specific IgE synthesis in athymic nude mice immunized with alum-adsorbed OVA. On the other hand, immunization of the recipient mice with OVA-liposome did not induce anti-OVA IgE production, even when CD4(+) T-cells of mice immunized with alum-adsorbed OVA were transferred. In the secondary immune response, OVA-liposome enhanced anti-OVA IgG antibody production but not the ongoing IgE production, suggesting that the IgE-selective unresponsiveness induced by the liposomal antigen involved direct effects on IgE but not IgG switching in vivo. These results suggest the role of an alternative mechanism, one not involving T-cells, in the regulation of IgE synthesis, and raise the possibility that surface-linked liposomal antigen is potentially applicable for the development of a novel vaccine that induces the least IgE synthesis. Moreover, given the relatively low allergic response to and increased antigenicity of the allergen, this form of antigen preparation would be applicable to allergen immunotherapy.     

Airway inflammation and adjuvant effect after repeated airborne exposures to di-(2-ethylhexyl)phthalate and ovalbumin in BALB/c mice

BACKGROUND: Epidemiological studies have suggested an association between exposure to phthalate plasticizers, including di-(2-ethylhexyl)phthalate (DEHP), and increased prevalence of asthma, rhinitis or wheezing. Furthermore, studies in mice have demonstrated an adjuvant effect from DEHP after parenteral administration with the model allergen ovalbumin (OVA). OBJECTIVE: Exposures to DEHP were investigated for adjuvant effects and airway inflammation in a mouse inhalation model. METHODS: BALB/cJ mice were exposed to aerosols of 0.022-13 mg/m(3) DEHP and 0.14 mg/m(3) OVA 5 days/week for 2 weeks and thereafter weekly for 12 weeks. Mice exposed to OVA alone or OVA+Al(OH)(3) served as control groups. Finally, all groups were exposed to a nebulized 1% OVA solution on three consecutive days. Serum, bronchoalveolar lavage (BAL) fluid, and draining lymph nodes were collected 24h later. RESULTS: In the OVA+Al(OH)(3) group, significantly increased levels of OVA-specific IgE and IgG1 in serum as well as of eosinophils in BAL fluid were observed. DEHP affected OVA-specific IgG1 production in a concentration-dependent manner, whereas little effect was seen on IgE and IgG2a. Dose-dependent increases in inflammatory cells were observed in BAL fluids, leading to significantly higher lymphocyte, neutrophil and eosinophil numbers in the OVA+13 mg/m(3) DEHP group. Ex vivo cytokine secretion by cultures of draining lymph nodes suggested that DEHP has a mixed Th1/Th2 cytokine profile. CONCLUSION: Airborne DEHP is able to increase serum IgG1 and lung inflammatory cell levels, but only at very high concentrations. Realistic DEHP levels do not have an adjuvant effect or induce allergic lung inflammation in the present mouse model.     

The fungal cell wall component beta-1,3-glucan has an adjuvant effect on the allergic response to ovalbumin in mice

The polyglucose beta-1,3-D-glucan is a major structural component of the cell wall of yeasts and fungi. In the present study, the adjuvant activity of beta-1,3-glucan from the fungus Sclerotinia sclerotiorum (SSG) on the response to the model allergen ovalbumin (OA) was studied, using the popliteal lymph node assay (PLNA) in BALB/c mice. The adjuvant activity on the local cellular response was determined by measuring the weight, cell number, and proliferation of the extracted PLNs. The levels of OA-specific immunoglobulin (Ig)E, IgG1, and IgG2a in serum were measured by enzyme-linked immunosorbent assay (ELISA). Groups of 8 mice were given either SSG + OA, SSG alone, or OA alone on d 0. Thereafter they were exsanguinated on d 20, or reinjected with OA on d 21, before exsanguination on d 26 or 33. Only on d 26 was SSG + OA found to significantly increase the PLN weight and cell numbers, but not cell proliferation (thymidine incorporation), compared with OA or SSG alone. SSG + OA was also found to significantly increase both the anti-OA IgE and IgG1 levels on d 20, 26, and 33 compared to OA alone. Compared to SSG alone, SSG + OA increased the OA-specific IgE and IgG 1 levels significantly on d 26 and 33, but not on d 20. A similar increase was not found for IgG2a. Our results show that beta-1,3-D-glucan provides a clear Th2-dependent (allergic) immune response to OA, indicated by elevated levels of IgE and IgG1 and not IgG2a, in the mouse model used.     

THE FUNGAL CELL WALL COMPONENT b-1,3-GLUCAN HAS AN ADJUVANT EFFECT ON THE ALLERGIC RESPONSE TO OVALBUMIN IN MICE

The polyglucose b -1,3-D-glucan is a major structural component of the cell wall of yeasts and fungi. In the present study, the adjuvant activity of b-1,3-glucan from the fungus Sclerotinia sclerotiorum (SSG) on the response to the model allergen ovalbumin (OA) was studied, using the popliteal lymph node assay (PLNA) in BALB/c mice. The adjuvant activity on the local cellular response was determined by measuring the weight, cell number, and proliferation of the extracted PLNs. The levels of OA-specific immunoglobulin (Ig)E, IgG1, and IgG2a in serum were measured by enzyme-linked immunosorbent assay (ELISA). Groups of 8 mice were given either SSG + OA, SSG alone, or OA alone on d 0. Thereafter they were exsanguinated on d 20, or reinjected with OA on d 21, before exsanguination on d 26 or 33. Only on d 26 was SSG + OA found to significantly increase the PLN weight and cell numbers, but not cell proliferation (thymidine incorporation), compared with OA or SSG alone. SSG + OA was also found to significantly increase both the anti-OA IgE and IgG1 levels on d 20, 26, and 33 compared to OA alone. Compared to SSG alone, SSG + OA increased the OA-specific IgE and IgG1 levels significantly on d 26 and 33, but not on d 20. A similar increase was not found for IgG2a. Our results show that b -1,3-D-glucan provides a clear Th2-dependent (allergic) immune response to OA, indicated by elevated levels of IgE and IgG1 and not IgG2a, in the mouse model used.     

Divergent antibody isotype responses induced in mice by systemic exposure to proteins: a comparison of ovalbumin with bovine serum albumin.

Whereas many foreign proteins are immunogenic, only a proportion is associated commonly with allergy, having the potential to induce the quality of immune response necessary for IgE antibody production and the development of immediate type hypersensitivity reactions in the gastrointestinal and/or respiratory tracts. In the context of toxicological evaluations there is a need to identify those properties that confer on proteins the ability to provoke allergic reactions. The characteristics of antibody responses induced in BALB/c strain mice following administration of ovalbumin (OVA), a significant human allergen, have been compared with those provoked by bovine serum albumin (BSA), a protein considered to have more limited allergenic potential. Intranasal or intraperitoneal (ip) administration of BSA or OVA elicited vigorous IgG and IgG1 antibody responses. Differential IgE antibody production was observed, however, with OVA stimulating relatively high IgE antibody titres at all doses tested whereas no or low titre IgE antibody was detected following exposure to BSA. Furthermore, a differential capacity for IgG2a antibody responses was observed, with only BSA provoking high titres of this IgG subclass. The relative quality of induced responses was equivalent following administration of these proteins via mucosal (in) tissue or via a non-mucosal (ip) route of exposure. IgG2a antibody production is promoted by the type 1 cytokine interferon gamma (IFN-gamma), whereas IFN-gamma and the type 2 cell product interleukin 4 exert reciprocal antagonistic effects on IgE antibody responses. Although cytokine expression patterns were not analysed in this series of experiments, the differential IgE and IgG subclass antibody responses induced by BSA and OVA are consistent with the preferential activation of T helper (Th) 1- and Th2-type cells, respectively. These data indicate that proteins can provoke in mice characteristic antibody (IgE and IgG) isotype profiles suggestive of discrete T lymphocyte responses and that such differences may be associated with variable allergenic activity.     

Adjuvant effect of quaternary ammonium compounds in a murine model

It has been suggested that occupational exposure to quaternary ammonium compounds (QACs) may promote the development of allergic airway diseases. In this study, hazard identifications of the adjuvant effect of cetylpyridinium chloride (CPC), dimethyldioctadecylammonium bromide (DDA), hexadecyltrimethylammonium bromide (HTA), and tetraethylammonium chloride (TEA) were performed in a screening bioassay. Female BALB/c mice were injected subcutaneously with the model allergen ovalbumin (OVA) alone or together with different quantities of one of the QAC test compounds. After one or two boosters, levels of OVA-specific IgE, IgG1 and IgG2a antibodies were measured in sera. CPC and DDA increased IgE and IgG1 antibody production, respectively, compared to the OVA control group, whereas HTA and TEA showed no adjuvant effect. Nevertheless, when TEA was given in combination with DDA, the adjuvant effect was up to six-fold higher than the adjuvant effect of DDA alone. Only DDA had a statistically significant adjuvant effect on IgG2a antibody levels.     

CpG ODN mediated prevention from ovalbumin-induced anaphylaxis in mouse through B cell pathway

Allergic inflammation is induced by type 2 T helper cell (Th2) and Th2 cytokines such as interleukin (IL)-4, IL-5 and IL-13. These cytokines induce the production of allergen-specific immunoglobulin (Ig)E by B cells, and the ensuing degranulation of mast cells via IgE cross-linking leads to most clinical manifestations of allergic diseases. We examined the ability of immunomodulatory unmethylated CpG oligodeoxynucleotides (ODN), which are potent inducers of Th1 cytokines, to prevent allergic symptoms in mice immunized and sensitized with allergen. Coadministration of CpG ODN with ovalbumin (OVA) before OVA sensitization substantially prevented mice from allergic anaphylaxis representing enhanced circulating concentrations of OVA-specific IgE and histamine, and decreased body temperature. Although CpG ODN provokes an abundance of Th1-skewing cytokines, including IL-12, interferon (IFN)-alpha and IFN-gamma, administration of CpG ODN in IFN-gamma deficient mice inhibited IgE production and prevented from OVA-induced anaphylaxis, indicating a dispensable role of IFN-gamma in mediating these protective effects. In vitro analysis revealed that CpG ODN inhibited class switching from IgM to IgE and IgG1 in response to CD40 and IL-4 in B cells, and this effect did not correlate with up-regulation of IFN-alpha production. These results imply a B cell-intrinsic, T cell-independent mechanism by which CpG ODN directly acts on B cells and inhibits IgE and IgG1 production leading to cause prevention from allergic symptoms.     

Nitrogen dioxide: no influence on allergic sensitization in an intranasal mouse model with ovalbumin and diesel exhaust particles

The role of traffic-related air pollution in the development of allergic diseases is still unclear. We therefore investigated if NO?, an important constituent of traffic-related air pollution, promotes allergic sensitization to the allergen ovalbumin (OVA). We also examined if NO? influenced the allergy adjuvant activity of diesel exhaust particles (DEP). For this purpose, mice were exposed intranasally to OVA with or without DEP present, immediately followed by exposure to NO? (5 or 25 parts per million [ppm]) or room air for 4?h in whole body exposure chambers. Eighteen hours after the last of three exposures, the lungs of half of the animals were lavaged with saline and markers of lung damage and lung inflammation in the bronchoalveolar lavage fluid (BALF) were measured. Three weeks later, after intranasal booster immunizations with OVA, the levels of OVA-specific IgE and IgG2a antibodies in serum were determined. Both NO? (25 ppm) and DEP gave lung damage, measured as increased total protein concentration in BALF, whereas only NO? seemed to stimulate release of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). In contrast, only DEP significantly increased the number of neutrophils. Furthermore, DEP in combination with OVA stimulated the production of serum allergen-specific IgE antibodies. NO?, however, neither increased the production of allergen-specific IgE antibodies, nor influenced the IgE adjuvant activity of DEP. Thus, based on our findings, NO? seems to be of less importance than combustion particles in the development of allergic diseases after exposure to traffic-related air pollution.     

Allergy adjuvant effect of particles from wood smoke and road traffic

There is growing evidence that in addition to augmenting the severity of asthma and allergic diseases, particulate air pollution also increases the incidence of allergy and asthma. We studied the adjuvant effect of particles from wood smoke and road traffic on the immune response to the allergen ovalbumin (OVA). OVA with and without particles was injected into one hind footpad of Balb/cA mice. All particles together with OVA significantly increased the level of OVA-specific immunoglobulin E (IgE) in serum, compared to groups given OVA or particles alone. Reference diesel exhaust particles (DEP) with OVA induced the highest levels of IgE, whereas no clear difference was observed between particles from road traffic and wood smoke. Road traffic particles collected in the autumn induced higher IgE values with OVA than corresponding particles collected during the winter season when studded tires are used, suggesting that studded tire-generated road pavement particles have less allergy adjuvant activity than exhaust particles. Compared to OVA or particles alone, all particles with OVA increased popliteal lymph node cell numbers, cell proliferation, ex vivo secretion of IL-4 and IL-10 after ConA stimulation, and the expression of several cell surface molecules (CD19, MHC class II, CD86 and CD23). Wood smoke particles with OVA induced somewhat higher cellular responses than road traffic particles, but less than DEP with OVA which seemed to be the most potent particle in inducing cellular as well as antibody responses. Thus, wood smoke particles had about the same capacity to enhance allergic sensitization as road traffic particles, but less than diesel exhaust particles.     

ortho-Phthalaldehyde enhances allergen-specific IgE production without allergen-specific IgG in ovalbumin-sensitized mice

ortho-Phthalaldehyde (OPA) is commonly used as a safer and more effective chemical disinfectant for use with medical devices in hospitals. However, the cases of patients with occupational bronchial asthma or contact dermatitis are recently reported among workers in the medical professions who were exposed to OPA disinfectant. Mechanism of allergic reaction associated with OPA is poorly understood. The purpose of this study is that OPA may act as an immunological adjuvant in the allergic reaction accompanied by enhanced specific-IgE production in response to allergen challenge in OVA-sensitized mice. OPA induced increase of total cell numbers, and reflected infiltration of neutrophils in BAL fluid after allergen challenge in sensitized mice, dose-dependently. However, total protein concentration in BAL fluid did not change in the all of groups. The OPA induced up-regulation of eotaxin and monocyte chemotactic protein-1 mRNAs in the lung as well as the increase in OVA-specific IgE in sensitized mice compared with non-sensitized controlled mice without increase in the level of OVA-specific IgG. Cytokines IL-4 and IL-5 mRNA were expressed by allergen (OVA) challenge in both lungs collected from OPA-administrated-sensitized and OPA-administrated-nonsensitized mice. From these data, we concluded that low concentration of OPA that enhanced the OVA-induced recruitment of neutrophils to the lung and the production of allergen-specific IgE, suggesting that OPA acts as an immunological adjuvant.     

Nitrogen dioxide: no influence on allergic sensitization in an intranasal mouse model with ovalbumin and diesel exhaust particles

The role of traffic-related air pollution in the development of allergic diseases is still unclear. We therefore investigated if NO₂, an important constituent of traffic-related air pollution, promotes allergic sensitization to the allergen ovalbumin (OVA). We also examined if NO₂ influenced the allergy adjuvant activity of diesel exhaust particles (DEP). For this purpose, mice were exposed intranasally to OVA with or without DEP present, immediately followed by exposure to NO₂ (5 or 25 parts per million [ppm]) or room air for 4?h in whole body exposure chambers. Eighteen hours after the last of three exposures, the lungs of half of the animals were lavaged with saline and markers of lung damage and lung inflammation in the bronchoalveolar lavage fluid (BALF) were measured. Three weeks later, after intranasal booster immunizations with OVA, the levels of OVA-specific IgE and IgG2a antibodies in serum were determined. Both NO₂ (25?ppm) and DEP gave lung damage, measured as increased total protein concentration in BALF, whereas only NO₂ seemed to stimulate release of the proinflammatory cytokine tumor necrosis factor alpha (TNF-α). In contrast, only DEP significantly increased the number of neutrophils. Furthermore, DEP in combination with OVA stimulated the production of serum allergen-specific IgE antibodies. NO₂, however, neither increased the production of allergen-specific IgE antibodies, nor influenced the IgE adjuvant activity of DEP. Thus, based on our findings, NO₂ seems to be of less importance than combustion particles in the development of allergic diseases after exposure to traffic-related air pollution.     

The IgE adjuvant effect of particles: characterisation of the primary cellular response in the draining lymph node

Diesel exhaust particles, and polystyrene particles (PSP) as a model for the insoluble particle core, have an adjuvant effect on allergen-specific IgE production in mice. We therefore examined the primary immune response in the draining popliteal lymph node (PLN) to the allergen ovalbumin (OVA) injected together with polystyrene particles into the footpad of BALB/cA mice. Similar numbers of particle-containing cells were observed in the draining lymph node on day 1 after injection of PSP alone or OVA + PSP, the numbers increasing continuously until day 21. The total lymph node cell numbers increased three to four times in the OVA + PSP group compared to both OVA and PSP groups, peaking on day 5. The increase in B cell numbers was twice the increase in T cell numbers. On day 5, OVA + PSP increased the expression of most surface markers measured (MHC class II, CD86, CD23, CD69) compared to OVA and PSP. Further, the ex vivo production of IL-4 and IL-10 by PLN cells from OVA + PSP-injected animals was increased. In conclusion, whereas PSP alone did not influence any of the immunologic markers studied, the adjuvant effect of PSP on the IgE antibody response to OVA was associated with an early increased primary cellular response in the draining lymph node.     

Butyl benzyl phthalate: effects on immune responses to ovalbumin in mice

During recent decades the prevalence of IgE-mediated (atopic) allergic diseases in Western Europe and the USA has been increasing dramatically. It has been suggested that one possible cause is the presence in the environment of chemicals that may act as adjuvants, enhancing immune and allergic responses. Certain commonly used phthalate plasticizers such as butyl benzyl phthalate (BBP) have been implicated in this way. In the current experiments, the impact of BBP, applied by a physiologically relevant exposure route, on the vigour of immune responses induced in BALB/c strain mice has been examined. Mice were immunized via subcutaneous injection with the reference allergen ovalbumin (OVA) and received concurrent topical treatment with doses of BBP that induced significant changes in liver weight. The generation of specific anti-OVA IgE and IgG1 antibodies was measured by passive cutaneous anaphylaxis and by enzyme-linked immunosorbant assays, respectively. Topical administration of BBP was without impact on anti-OVA IgE antibody responses, regardless of whether BBP was applied locally or distant to the site of OVA immunization. However, same-site treatment with high-dose BBP (100 mg) did result in a modest elevation in anti-OVA IgG1 antibody production, a subclass of antibody used as a surrogate marker of IgE responses. Taken together with human exposure data, these results suggest that the doses of phthalate encountered in the home environment are unlikely to be a major factor contributing to the increased incidence of asthma and allergy in the developed world.     

Effects of gasoline engine emissions on preexisting allergic airway responses in mice

Gasoline-powered vehicle emissions contribute significantly to ambient air pollution. We hypothesized that exposure to gasoline engine emissions (GEE) may exacerbate preexisting allergic airway responses. Male BALB/c mice were sensitized by injection with ovalbumin (OVA) and then received a 10-min aerosolized OVA challenge. Parallel groups were sham-sensitized with saline. Mice were exposed 6 h/day to air (control, C) or GEE containing particulate matter (PM) at low (L), medium (M), or high (H) concentrations, or to the H level with PM removed by filtration (high-filtered, HF). Immediately after GEE exposure mice received another 10-min aerosol OVA challenge (pre-OVA protocol). In a second (post-OVA) protocol, mice were similarly sensitized but only challenged to OVA before air or GEE exposure. Measurements of airway hyperresponsiveness (AHR), bronchoalveolar lavage (BAL), and blood collection were performed approximately 24 h after the last exposure. In both protocols, M, H, and HF GEE exposure significantly decreased BAL neutrophils from nonsensitized mice but had no significant effect on BAL cells from OVA-sensitized mice. In the pre-OVA protocol, GEE exposure increased OVA-specific IgG(1) but had no effect on BAL interleukin (IL)-2, IL-4, IL-13, or interferon (IFN)-gamma in OVA-sensitized mice. Nonsensitized GEE-exposed mice had increased OVA-specific IgG(2a), IgE, and IL-2, but decreased total IgE. In the post-OVA protocol, GEE exposure reduced BAL IL-4, IL-5, and IFN-gamma in nonsensitized mice but had no effect on sensitized mice. These results suggest acute exposure to the gas-vapor phase of GEE suppressed inflammatory cells and cytokines from nonsensitized mice but did not substantially exacerbate allergic responses.     

IgE adjuvant effect caused by particles - immediate and delayed effects

Diesel exhaust particles are reported to increase the specific IgE response to ovalbumin (OVA) and pollen. Evidence has been provided that the particle core contributes to this adjuvant activity. The purpose of our study was to investigate the effect of well-defined simple particles, polystyrene particles (PSP), on the production of allergen-specific IgE in a mouse model. The IgE adjuvant effect of PSP was investigated in experiments using intranasal (i.n.) instillation, intratracheal (i.t.) instillation or intraperitoneal (i.p.) injection. Delayed and cumulative adjuvant effects were investigated by giving mice i.p. injections with PSP 1-3 days, or on 4 consecutive days before OVA, respectively. The levels of allergen-specific and total IgE were measured. Irrespectively of immunisation route and protocol, OVA in combination with PSP elicited increased levels of both allergen-specific and total IgE when compared with OVA alone. Therefore, in the experimental model, particles were found to augment the specific IgE response to an allergen even when the allergen was introduced several days after the particles. These findings imply that individuals exposed to particulate air pollution at one point of time may develop an increased reaction towards allergens inhaled later that day or even several days after the particle exposure.     

Modulation of ovalbumin-induced Th2 responses by second-generation immunomodulatory oligonucleotides in mice

Oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG DNAs) prevent development of T-helper type 2 (Th2) immune responses and reverse established allergic responses in mouse models. We recently reported that second-generation immunomodulatory oligonucleotides (IMOs) containing novel structures (immunomers) and a synthetic immunostimulatory CpR (R=2'-deoxy-7-deazguanosine) motif induce the production of distinct cytokine secretion profiles in vitro and in vivo. In the present study, we evaluated IMOs containing CpG and CpR motifs to modulate allergen-induced Th2 immune responses in prevention and treatment models. Mice sensitized and challenged with ovalbumin (OVA) were treated with a CpG DNA or an IMO by administration either at the time of OVA sensitization (co-administration; prevention) or after establishment of an allergic response (treatment). Spleens, blood, and lungs were collected and analyzed for immune responses. Spleen-cell cultures harvested from OVA-sensitized mice showed a significant decrease in Th2 cytokine levels with a concomitant increase in Th1 cytokine levels only when CpG DNA or IMOs were co-administered with OVA. The co-administration of CpG DNA or IMOs during OVA sensitization significantly reduced serum OVA-specific and total IgE levels in mice. The mice who received CpG DNA or IMOs co-administered with OVA showed a small reduction in serum OVA-specific and total IgG1 levels and a significant increase in serum OVA-specific and total IgG2a levels. Similar results were found in mice with established allergic responses who received IMO treatment. IMO treatment also resulted in strong inhibition of inflammatory cell infiltration and goblet cell hyperplasia in the lungs compared with untreated mice lungs. These data demonstrate that IMOs prevent antigen-induced Th2 immune responses when co-administered to mice during OVA sensitization and that IMOs reverse established allergic responses induced by OVA.     

A BALB/c mouse model for assessing the potential allergenicity of proteins: Comparison of allergen dose,sensitization frequency,timepoint and sex

The present study was to investigate the possibility of using the BALB/c mouse as an animal model for assessing the potential allergenicity of proteins.Specific IgE and IgG1 against ovalbumin were induced by dosing BALB/c mice via intraperitoneal injection (absence of adjuvant). The effects of various allergen doses (5 mg, 0.5 mg or 0.05 mg OVA), sensitization times (twice or five times), timepoints (day 14 or day 28) and sex (male or female) were studied. IL-4, IFN-γ, OVA-specific IgE and IgG1 were measured by enzyme-linked immunosorbent assay (ELISA).A general finding was that mice treated with 0.05 mg OVA had the highest OVA-specific IgE and IgG1, statistically significant higher specific IgE and IgG1 were observed in groups sensitized five times than twice, OVA-specific IgE and IgG1 on day 28 were statistically higher than day 14, and higher IL-4 was observed in OVA-allergic mice than control mice.These results demonstrate that the BALB/c mouse model treated with 0.05 mg OVA intraperitoneally on days 0, 3, 6, 9, 12 might be used for further experiments. OVA-specific IgE and IgG1 should be detected on day 28. Further studies including reproducibility and other conditions were required before using the BALB/c mouse model for assessing the potential allergenicity of proteins.     

Adjuvant effects of inhaled mono-2-ethylhexyl phthalate in BALB/cJ mice

Phthalates, including di(2-ethylhexyl) phthalate (DEHP), are widely used and have been linked with the development of wheezing and asthma. The main metabolite of DEHP, mono-2-ethylhexyl phthalate (MEHP), was investigated for adjuvant effects in a mouse inhalation model. BALB/cJ mice were exposed to aerosols of 0.03 or 0.4 mg/m(3) MEHP 5 days/week for 2 weeks and thereafter weekly for 12 weeks together with a low dose of ovalbumin (OVA) as a model allergen. Mice exposed to OVA alone or OVA+Al(OH)(3) served as negative and positive controls, respectively. Finally, all groups were exposed to a nebulized 1% OVA solution on 3 consecutive days to investigate the development of an inflammatory response. Serum, bronchoalveolar lavage (BAL) fluid, and draining lymph nodes were collected 24h later. In the OVA+Al(OH)(3) group, significantly increased levels of OVA-specific IgE and IgG1 in serum as well as of eosinophils in BAL fluid were observed. OVA-specific IgG1 production in both MEHP groups was significantly increased. OVA-specific IgE and IgG2a were not increased significantly. A dose-dependent increase in inflammatory cells was observed in BAL fluid, leading to significantly higher lymphocyte and eosinophil numbers in the OVA+0.4 mg/m(3) MEHP group. Ex vivo cytokine secretion by cultures of draining lymph nodes suggested a T(H)2 profile of MEHP. In conclusion, MEHP acted as a T(H)2 adjuvant after inhalation. However, it is suggested that the inflammation in the MEHP groups was primarily mediated by an IgG1-dependent mechanism. To address implications for humans, a margin-of-exposure was estimated based on the lack of significant effects on IgE production and inflammation after exposures to 0.03 mg/m(3) MEHP observed in the present study and estimated human exposure levels.