Else-Carin Groeng

Fine particles of widely different composition have an adjuvant effect on the production of allergen-specific antibodies

Diesel exhaust particles (DEP) are reported to increase the specific IgE response to allergens, and results from our laboratory suggest that the particle core of DEP contribute to this adjuvant activity. The purpose of the present study was to explore further the adjuvant effect of particles per se, that is particles by themselves. NIH/Ola mice were given two intraperitoneal injections with ovalbumin (OVA; 10 microg) alone or OVA in combination with PSP, polytetrafluoroethylene (teflon), titanium dioxide (TiO(2)) or amorphous silica particles (2.8x10(10)-2.8x10(12)). Blood samples were drawn 7 days after the last injection, and serum levels of allergen-specific and total IgE and IgG2a were measured. All types of particles gave increased levels of allergen-specific IgE and IgG2a. Similar results were obtained after intranasal or intratracheal instillation with OVA plus PSP or silica. Our results indicate that fine particles of widely different composition may have an adjuvant effect on the production of allergen-specific antibodies.

Protective Effect of Plantago major L. Pectin Polysaccharide against Systemic Streptococcus pneumoniae Infection in Mice

The antibacterial effect of a soluble pectin polysaccharide, PMII, isolated from the leaves of Plantago major, was examined in inbred NIH/OlaHsd and Fox Chase SCID mice experimentally infected with Streptococcus pneumoniae serotype 6B. Serotype 6B is known to give a more protracted infection when injected intraperitoneally into susceptible mice than more virulent serotypes like type 4. PMII was administered i.p. either once 3 days before challenge or once to thrice from 3 to 48 h after challenge. The number of bacteria in blood and the mouse survival rate were recorded. Pre‐challenge administration of PMII and also lipopolysaccharide (LPS), included as a control, gave a dose‐dependent protective effect against S. pneumoniae type 6B infection. However, injection of PMII after establishment of the infection in NIH/OlaHsd mice had no effect. The data demonstrate that, firstly, the polysaccharide fraction PMII from P. major protects against pneumococcal infection in mice when administered systemically prechallenge, and secondly that the protective effect is owing to stimulation of the innate and not the adaptive immune system.

The fungal cell wall component β-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.

Maternal allergen immunization during pregnancy in a mouse model reduces adult allergy-related antibody responses in the offspring

Background The immune status and allergen exposure of the mother may influence the immune response in the offspring after birth. This relationship may be important both for allergen avoidance strategies and, alternatively, for allergy prophylaxis by allergen exposure of the mother.

The effect of endotoxin on the production of IgE, IgG1 and IgG2a antibodies against the cat allergen Fel d 1 in mice

BACKGROUND Endotoxin/LPS is ubiquitous in our environment. The question whether lipopolysaccharide (LPS) is beneficial or disease-promoting in relation to asthma and allergy has been raised in several recent studies. Some have reported a positive correlation between the level of LPS in house dust and the symptoms of asthmatic children. Others have found that exposure to LPS appears to protect against the development of atopic disease in children. OBJECTIVES We performed a study in mice to examine the antibody response after subcutaneous immunization with LPS and the cat allergen Fel d 1. We asked whether LPS would increase the response and direct the antibody production towards an allergic (IgE), or non-allergic (IgG2a) antibody profile. In rodents both IgE and IgG1 are antibodies produced under Th2-dependence and IgG2a antibodies under Th1-dependence. Also, when LPS and Fel d 1 are introduced to the immune system, we asked whether the timing of the two agents relative to each other is crucial. METHODS The mice were injected subcutaneously with LPS and/or Fel d 1 four times in various orders. IgE, IgG1 and IgG2a antibodies specific to Fel d 1 were measured in serum using ELISA. RESULTS A strong antibody response, both for IgE, IgG1 and IgG2a, was observed only when Fel d 1 and LPS were injected simultaneously, and in particular after repeated injections. CONCLUSION A strong specific antibody response was observed, both for IgE, IgG1 and IgG2a, only when LPS was introduced to the immune system together with the cat allergen Fel d 1. No such adjuvant effect was observed when LPS was introduced alone prior to or subsequent to the allergen. The resulting antibody response was not polarized in terms of Th1- or Th2-dependence.

Fine Ambient Particles from Various Sites in Europe Exerted a Greater IgE Adjuvant Effect than Coarse Ambient Particles in a Mouse Model

In the European Union (EU)-funded project Respiratory Allergy and Inflammation due to Ambient Particles (RAIAP), coarse and fine ambient particulate matter (PM) was collected at traffic dominated locations in Oslo, Rome, Lodz, and Amsterdam, in the spring, summer, and winter 2001/2002. PM was also collected in de Zilk, a rural seaside background location in the Netherlands. The aim of this study was to screen the ambient PM fractions for allergy adjuvant activity measured as the production of allergen- (ovalbumin-) specific immunoglobulin (Ig) E following subcutaneous (sc) injection into the footpad of mice. A second aim was to determine whether the 6-d popliteal lymph node (PLN) assay can be used to detect an allergy adjuvant activity. Allergy screening for IgE adjuvant activity showed that in the presence of ovalbumin (Ova) 12 out of 13 of the fine ambient PM fractions exerted a significant IgE adjuvant activity. In contrast, only 3 out of 13 of the coarse PM fractions had significant adjuvant activity. Overall, fine ambient PM exerted significantly greater IgE adjuvant activity per unit mass than coarse PM. No significant differences were observed between locations or seasons. Substantial higher levels of specific components of PM such as vanadium (V), nickel (Ni), zinc (Zn), ammonium (NH4), and sulfate (SO4) were present in the fine compared to coarse PM fractions. However, differences in the content of these components among fine PM fractions did not reflect the variation in the levels of IgE anti-Ova. Still, when comparing all seasons overall, positive correlations were observed between V, Ni, and SO4 and the allergen specific IgE levels. The PLN responses (weight and cell number) to Ova and ambient PM in combination were significantly higher than to Ova or PM alone. Still, the PLN assay appears not to be useful as a quantitative assay for screening of allergy adjuvant activity since no correlation was observed between PLN responses and allergen specific IgE levels. In conclusion, fine ambient PM fractions consistently were found to increase the allergen-specific IgE responses more than the coarse ones. Our finding is in agreement with the notion that traffic-related air pollution contributes to the disease burden in asthma and allergy, and points to fine and ultrafine ambient PM as the most important fractions in relation to allergic diseases.

Early life exposure to bisphenol A investigated in mouse models of airway allergy, food allergy and oral tolerance

The impact of early life exposure to bisphenol A (BPA) through drinking water was investigated in mouse models of respiratory allergy, food allergy and oral tolerance. Balb/c mice were exposed to BPA (0, 10 or 100 μg/ml), and the offspring were intranasally exposed to the allergen ovalbumin (OVA). C3H/HeJ offspring were sensitized with the food allergen lupin by intragastric gavage, after exposure to BPA (0, 1, 10 or 100 μg/ml). In separate offspring, oral tolerance was induced by gavage of 5 mg lupin one week before entering the protocol for the food allergy induction. In the airway allergy model, BPA (100 μg/ml) caused increased eosinophil numbers in bronchoalveolar lavage fluid (BALF) and a trend of increased OVA-specific IgE levels. In the food allergy and tolerance models, BPA did not alter the clinical anaphylaxis or antibody responses, but induced alterations in splenocyte cytokines and decreased mouse mast cell protease (MMCP)-1 serum levels. In conclusion, early life exposure to BPA through drinking water modestly augmented allergic responses in a mouse model of airway allergy only at high doses, and not in mouse models for food allergy and tolerance. Thus, our data do not support that BPA promotes allergy development at exposure levels relevant for humans.

Antibody response to pneumococcal polysaccharide vaccine in young, adult and old mice.

The anti‐pneumococcal antibody response was studied in young (5‐week‐old) and adult (10‐week‐old) BALB/c and CBA/J mice and in adult (9–10‐week‐old) and old (12‐, 18‐ and 24‐month‐old) AB6F1 and B6D2F1 mice after s.c. immunization with a 23‐valent pneumococcal polysaccharide vaccine. Both young and adult mice showed a significant IgM antibody response to the vaccine 6 days after immunization with 111 /ig antigen. There were significant immune responses to serotypes 1, 2, 4 and 7F in contrast to small responses to serotypes 14, 19F and 23F after immunization with the vaccine. One month after immunization, there were only marginal differences in IgM anti‐pneumococcal antibody levels to the vaccine (anti‐PPS) between immunized and unimmunized BALB/c mice, whereas in CBA/J mice the anti‐PPS remained higher in immunized than in unimmunized mice. Immunization of old mice induced a significant IgM antibody response 6 days after immunization, but the anti‐PPS thereafter decreased rapidly towards preimmunization values in AB6F1 mice. A significant IgG anti‐PPS was not detected in any of the mice studied. The IgA anti‐PPS tended to vary over time with no consistent pattern. It is important to carefully consider age and strain of the mice used when studying the immune response to pneumococcal polysaccharide antigens.

Suppression of allergen-specific IgE in offspring after preconceptional immunisation: maternal, paternal and genetic influences.

Immunisation of female mice with the allergen ovalbumin (OVA) during pregnancy reduces the OVA‐specific IgE response in adult offspring. To approach primary prevention strategies for allergy, we investigated to what extent genetic, paternal and maternal factors influence this suppressive effect on allergic sensitisation in offspring and investigated the possibility of pregestational immunisation. Maternal allergen immunisation reduced OVA‐specific IgE levels in immunised offspring, even after maternal immunisation up to 8 weeks before conception without further allergen exposure. Immunisation of immunodeficient BALB/c severe combined immune deficiency (SCID) dams mated with wild type males did not lead to IgE suppression in offspring, indicating the importance of a functional maternal immune system. Immunisation of male mice before the relevant spermatogenesis did not cause antibody suppression in offspring. OVA‐specific IgG1, presumably of maternal origin, was present in naïve offspring only from immunised dams and was associated with suppressed IgE responses after offspring immunisation. The IgE‐suppressive effect of maternal immunisation was demonstrated in all three immunocompetent strains tested (NIH/OlaHsd, BALB/cA and C57BL/6 mice). In conclusion, suppression of allergen‐specific IgE production in offspring could not be induced by paternal immunisation, and genetic factors were of minor importance. In contrast, we demonstrate the necessity of maternal factors, possibly allergen‐specific IgG1, resulting from a functional adaptive immune response, for the IgE‐suppressive effect in offspring. These maternal factors could be induced by immunisation of female mice even before conception.

Exposure to perfluoroundecanoic acid (PFUnDA) accelerates insulitis development in a mouse model of type 1 diabetes

Perfluoralkylated substances (PFAS) are classified as persistent, bioaccumulative and toxic substances and are widespread environmental contaminants. Humans are exposed through food, drinking water and air. We have previously reported that bisphenol A accelerates spontaneous diabetes development in non-obese diabetic (NOD) mice and observed in the present study that perfluoroundecanoic acid, PFUnDA, increased insulitis development, a prerequisite for diabetes development in NOD mice. We exposed NOD mice to PFUnDA in drinking water (3, 30 and 300 μg/l) at mating, during gestation and lactation and until 30 weeks of age. After 300 μg/l PFUnDA exposure, we report (i) increased pancreatic insulitis, (ii) increased number of apoptotic cells in pancreatic islets prior to insulitis and (iii) decreased phagocytosis in peritoneal macrophages. There was also a trend of decreased number of tissue resident macrophages in pancreatic islets prior to insulitis after exposure to 300 μg/l, and altered cytokine secretion in activated splenocytes after exposure to 3 μg/l PFUnDA. Although insulitis is a prerequisite for autoimmune diabetes, the accelerated insulitis was not associated with accelerated diabetes development. Instead, the incidence of diabetes tended to be reduced in the animals exposed to 3 and 30 μg/l PFUnDA, suggesting a non-monotonic dose response. The effects of PFUnDA exposure on increased apoptosis in pancreas and reduced macrophage function as well as accelerated insulitis development in NOD mice, may also be relevant for human insulitis. Further observational autoimmune diabetes clinical cohort studies and animal experiments for PFUnDA as well as other PFASs are therefore encouraged.