Monica Andreassen

Humoral and cellular immune responses in mice after airway administration of Bacillus thuringiensis Cry1Ab and MON810 cry1Ab-transgenic maize

Genetically modified (GM) crops may bring new proteins with immunogenic and allergenic properties into the food and feed chains. The most commonly grown GM maize, MON810, expresses a modified version of the insecticidal Cry1Ab protein originating in the soil bacterium Bacillus thuringiensis (Bt). Immune reactions following inhalation of pollen and debris from such plants have been scarcely studied. We exposed BALB/c mice to purified Cry1Ab proteins and Cry1Ab-containing MON810 plant materials by intranasal installation. No anti-Cry1Ab antibodies were detected following exposure to the plant materials. Exposure to purified Cry1Ab resulted in specific anti-Cry1Ab IgG1 and IgE production, indicating inherent immunogenicity and allergenicity. Mice exposed to leaf extracts from both MON810 and unmodified maize demonstrated influx of lymphocytes and eosinophils in the broncho-alveolar lavage, and increased cytokine release in mediastinal lymph node cells. The results indicate that the airway exposure to Cry1Ab proteins may be a route of practical relevance.

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.

Cry1Ab Protein from Bacillus thuringiensis and MON810 cry1Ab-transgenic Maize Exerts No Adjuvant Effect After Airway Exposure

The genetically modified (GM) maize event MON810 has been inserted with a processed version of the transgene, cry1Ab, derived from the soil bacterium Bacillus thuringiensis (Bt) to express proteins with insecticidal properties. Such proteins may introduce new allergens and also act as adjuvants that promote allergic responses. While focus has been on safe consumption and hence the oral exposure to GM food and feed, little is known regarding inhalation of pollen and desiccated airborne plant material from GM crops. The aim of this study was to investigate whether plant material from the Cry1Ab‐expressing maize variety MON810, or trypsin‐activated Cry1Ab (trypCry1Ab) protein produced in recombinant bacteria, may act as adjuvants against the allergen ovalbumin (OVA) in a mouse model of airway allergy. A clear proallergic adjuvant effect of the mucosal adjuvant cholera toxin (CT) was demonstrated, determined as increased specific IgE, eosinophils and Th2 cytokines in MLN cell supernates, while no elevation in OVA‐specific antibodies or cytokine release from MLN cells after stimulation with OVA were observed in mice receiving Cry1Ab‐containing plant materials or the trypCry1Ab protein. Our data suggest that Cry1Ab proteins had no detectable systemic adjuvant effect in mice after airway exposure. Further experiments with purified plant proteins, as well as long‐term exposures needs be conducted to further evaluate exposures experienced in real‐life situations.

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.

Offspring IgE Responses are Influenced by Levels of Maternal IgG Transferred in Early Life

Maternal immune responses may interfere with offspring allergy development as maternal immunization may suppress IgE development, while maternal allergy may promote allergy. Therefore, we investigated the effect of two different maternal treatments on airway allergy in female and male offspring.

Allergen Immunization Induces Major Changes in Microbiota Composition and Short-Chain Fatty Acid Production in Different Gut Segments in a Mouse Model of Lupine Food Allergy

Background: The incidence of food allergies in western countries has increased in recent decades. Objectives: To study the association between gut bacterial microbiota composition, short-chain fatty acids (SCFAs) and food allergy in a mouse model. Methods: After oral immunizations with the human food allergen lupine with the adjuvant cholera toxin (CT) (or buffer in controls), sensitization and anaphylactic responses were determined. Gastrointestinal content was collected from the distal ileum, cecum, colon, and fecal pellets, and the bacterial diversity and composition was determined by deep sequencing of the 16S rRNA gene. SCFAs in gastrointestinal content supernatants were determined by gas chromatography. Results: The microbiota signatures were profoundly affected by allergen immunization. Ten operational taxonomic units (OTUs) were significantly different between immunized and control animals for at least one of the intestinal segments; eight of these OTUs belonged to the Clostridia class. Although consistent across all four gut segments, the colon showed the highest number of OTUs significantly associated with allergic immunization. SCFA levels in the cecum were also altered by immunization. Conclusions: Allergen immunization with CT in the present food allergy model induced profound changes in the microbiome composition and SCFA production. The result suggests that the colon may be the most sensitive gut segment for investigating changes in the gut microbiome.

Effect of dietary pristane and other saturated mineral oils (MOSH) on autoimmune arthritis in rats

Pristane and other adjuvants based on mineral oil saturated hydrocarbons (MOSH) may induce autoimmunity in rodents after intradermal injection; however there is a lack of information on immune effects after oral MOSH exposure. The aim of our study was to determine the impact of dietary exposure to pristane and other MOSH on the development of autoimmune arthritis. Dark Agouti (DA) rats were given feed containing 4000 mg/kg pristane or a broad MOSH mixture in various concentrations (0–4000 mg/kg) for 90 days, or a single intradermal injection of 200 μl pristane (positive control). Arthritis scores, and serum and splenocyte markers previously associated with arthritis development, were determined. All rats injected with pristane displayed arthritis symptoms and higher levels of certain serum markers. None of the rats fed pristane or MOSH developed arthritis symptoms or demonstrated clear changes in any measured arthritis-associated biological markers in serum or splenocytes. The absence of clinical arthritis symptoms or any increase in common arthritis-associated biological markers in sera and spleen following dietary exposure to pristane or a broad MOSH mixture in a sub-chronic rat model of arthritis suggest that dietary MOSH have low capacity to promote development of autoimmunity.