Data management and protection in occupational and environmental exposome research - A case study from the EU-funded EXIMIOUS project

Within collaborative projects, such as the EU-funded Horizon 2020 EXIMIOUS project (Mapping Exposure-Induced Immune Effects: Connecting the Exposome and the Immunome), collection and analysis of large volumes of data pose challenges in the domain of data management, with regards to both ethical and legal aspects. However, researchers often lack the right tools and/or accurate understanding of the ethical/legal framework to independently address such challenges. With the guidance and support within and between the partner institutes (the researchers and the ethical and legal teams) in the EXIMIOUS project, we have been able to understand and solve most challenges during the first two project years. This has fed into the development of a Data Management Plan and the establishment of data management platforms in accordance with the ethical and legal framework laid down by the EU and the different national regulations of the partners involved. Through this elaborate exercise, we have acquired tools which allow us to make our research data FAIR (Findable, Accessible, Interoperable, and Reusable), while at the same time ensuring data privacy and security (GDPR compliant). Herein we share our experience of creating and managing the data workflow through an open research communication, with the aim of helping other researchers build their data management framework in their own projects. Based on the measures adopted in EXIMIOUS to ensure FAIR data management, we also put together a checklist "DMP CHECK" containing a series of recommendations based on our experience.

Exposure to persistent organic pollutants alters the serum metabolome in non-obese diabetic mice

INTRODUCTION

Autoimmune disorders such as type 1 diabetes (T1D) are believed to be caused by the interplay between several genetic and environmental factors. Elucidation of the role of environmental factors in metabolic and immune dysfunction leading to autoimmune disease is not yet well characterized.

OBJECTIVES

Here we investigated the impact of exposure to a mixture of persistent organic pollutants (POPs) on the metabolome in non-obese diabetic (NOD) mice, an experimental model of T1D. The mixture contained organochlorides, organobromides, and per- and polyfluoroalkyl substances (PFAS).

METHODS

Analysis of molecular lipids (lipidomics) and bile acids in serum samples was performed by UPLC-Q-TOF/MS, while polar metabolites were analyzed by GC-Q-TOF/MS.

RESULTS

Experimental exposure to the POP mixture in these mice led to several metabolic changes, which were similar to those previously reported as associated with PFAS exposure, as well as risk of T1D in human studies. This included an increase in the levels of sugar derivatives, triacylglycerols and lithocholic acid, and a decrease in long chain fatty acids and several lipid classes, including phosphatidylcholines, lysophosphatidylcholines and sphingomyelins.

CONCLUSION

Taken together, our study demonstrates that exposure to POPs results in an altered metabolic signature previously associated with autoimmunity.

Immune responses in Omicron SARS-CoV-2 breakthrough infection in vaccinated adults

The SARS-CoV-2 Omicron variant has more than 15 mutations in the receptor binding domain of the Spike protein enabling increased transmissibility and viral escape from antibodies in vaccinated individuals. It is unclear how vaccine immunity protects against Omicron infection. Here we show that vaccinated participants at a super-spreader event have robust recall response of humoral and pre-existing cellular immunity induced by the vaccines, and an emergent de novo T cell response to non-Spike antigens. Individuals with Omicron SARS-CoV-2 breakthrough infections have significantly increased activated SARS-CoV-2 wild type Spike-specific cytotoxic T cells, activated follicular helper (T_FH) cells, functional T cell responses, boosted humoral responses, and rapid release of Spike and RBD-specific IgG⁺ B cell plasmablasts and memory B cells into circulation. Omicron breakthrough infection affords significantly increased de novo memory T cell responses to non-Spike viral antigens. Concerted T and B cell responses may provide durable and broad immunity.

The SARS-CoV-2 Omicron variant possess many mutations within the receptor binding domain of the Spike protein, which confer increased transmissibility and higher antibody escape. Here, the authors carry out analysis of the serological and cellular immune responses of individuals with Omicron breakthrough infection.

Dibutyl phthalate exposure alters T-cell subsets in blood from allergen-sensitized volunteers

Phthalates are ubiquitous environmental contaminants associated with allergic disease in epidemiological and animal studies. This investigation aims to support these associations by interrogating systemic immune effects in allergen-sensitized volunteers after controlled indoor air exposure to a known concentration of dibutyl phthalate (DBP). The phthalate-allergen immune response (PAIR) study enrolled 16 allergen-sensitized participants to a double-blinded, randomized, crossover exposure to two conditions (DBP or control air for 3 hr), each followed immediately by inhaled allergen challenge. Peripheral blood immune cell composition and activation along with inflammatory mediators were measured before and after exposure. DBP exposure prior to the inhaled allergen challenge increased the percentage of CD4⁺ T helper cells and decreased the percentage of regulatory T cells (3 hr and 20 hr post-exposure), while only modest overall effects were observed for inflammatory mediators. The cells and mediators affected by the phthalate exposure were generally not overlapping with the endpoints affected by allergen inhalation alone. Thus, in distinction to our previously published effects on lung function, DBP appears to alter endpoints in peripheral blood that are not necessarily enhanced by allergen alone. Further studies are needed to clarify the role of phthalate-induced systemic effects in disease pathogenesis.

Lipidomic Analyses Reveal Modulation of Lipid Metabolism by the PFAS Perfluoroundecanoic Acid (PFUnDA) in Non-Obese Diabetic Mice

Exposure to Per- and polyfluoroalkyl substances (PFAS) has been linked to multiple undesirable health outcomes across a full lifespan, both in animal models as well as in human epidemiological studies. Immunosuppressive effects of PFAS have been reported, including increased risk of infections and suppressed vaccination responses in early childhood, as well as association with immunotoxicity and diabetes. On a mechanistic level, PFAS exposure has been linked with metabolic disturbances, particularly in lipid metabolism, but the underlying mechanisms are poorly characterized. Herein we explore lipidomic signatures of prenatal and early-life exposure to perfluoroundecanoic acid (PFUnDA) in non-obese diabetic (NOD) mice; an experimental model of autoimmune diabetes. Female NOD mice were exposed to four levels of PFUnDA in drinking water at mating, during gestation and lactation, and during the first weeks of life of female offspring. At offspring age of 11–12 weeks, insulitis and immunological endpoints were assessed, and serum samples were collected for comprehensive lipidomic analyses. We investigated the associations between exposure, lipidomic profile, insulitis grade, number of macrophages and apoptotic, active-caspase-3-positive cells in pancreatic islets. Dose-dependent changes in lipidomic profiles in mice exposed to PFUnDA were observed, with most profound changes seen at the highest exposure levels. Overall, PFUnDA exposure caused downregulation of phospholipids and triacylglycerols containing polyunsaturated fatty acids. Our results show that PFUnDA exposure in NOD mice alters lipid metabolism and is associated with pancreatic insulitis grade. Moreover, the results are in line with those reported in human studies, thus suggesting NOD mice as a suitable model to study the impacts of environmental chemicals on T1D.

Maternal gestational mercury exposure in relation to cord blood T cell alterations and placental gene expression signatures

The immunotoxic impacts of mercury during early life is poorly understood. We investigated the associations between gestational mercury exposure and frequency of cord blood T cells as well as placental gene expression. Frequency of natural Treg cells was positively associated with prenatal and postpartum mercury toenail concentrations. Frequency of NKT and activated naïve Th cells was positively associated with prenatal toenail mercury concentrations and number of maternal silver-mercury dental amalgams, respectively. Placental gene expression analyses revealed distinct gene signatures associated with mercury exposure. Decreased placental expression of a histone demethylase, KDM4DL, was associated with both higher prenatal and postpartum maternal toenail mercury levels among male infants and remained statistically significant after adjustment for fish and seafood consumption. The results suggest that gestational exposure to mercury concentrations contribute to alterations in both T cells and gene expression in placenta at birth. These alterations may inform mechanisms of mercury immunotoxicity.

Improved diet quality is associated with decreased concentrations of inflammatory markers in adults with uncontrolled asthma

BACKGROUND

Asthma has become one of the major public health challenges, and recent studies show promising clinical benefits of dietary interventions, such as the Dietary Approaches to Stop Hypertension (DASH) diet.

OBJECTIVE

The objective of this study was to examine whether changes in diet quality are associated with changes in inflammatory markers important in asthma pathophysiology.

METHODS

In this exploratory study in patients with poorly controlled asthma participating in a randomized controlled trial of a DASH intervention study, changes in concentrations of a broad panel of serum proteins (51-plex Luminex assay, Affymetrix) were determined, and their relation to diet quality (DASH score) assessed by combining data of both intervention and usual-care control groups. Second, the relation between the serum proteins, other biomarkers of inflammation and nutrition, and Asthma Control Questionnaire (ACQ) was assessed.

RESULTS

During the first 3 mo, diet quality (DASH scores) were inversely associated (P < 0.05, false discovery rate P < 0.09) with serum concentrations of a large number serum proteins, reflecting not only general proinflammatory markers such as IL-1β, transforming growth factor α (TGF-α), and IL-6 (r = -0.31 to -0.39) but also a number of proteins associated with asthmatic conditions, specifically several T-helper (Th) 2 (Th2; r = -0.29 to -0.34) and Th17 (r = -0.4) associated cytokines and growth factors. Monokine induced by gamma/chemokine (C-X-C motif) ligand 9 (CXCL9) (MIG/CXCL9), a T-cell attractant induced by IFN-γ previously linked to asthma exacerbations, appeared to be the marker most consistently associated with DASH diet quality for the entire 6-mo study period (r = -0.40 and -0.30 for 0-3 and 3-6 mo, respectively, and standardized coefficient loadings -0.13 in the partial least squares analyses). Decreases in 19 serum protein concentrations were also correlated with improved asthma control during the 6-mo study period.

CONCLUSIONS

Our data in adult patients with poorly controlled asthma suggest that dietary changes, like the introduction of DASH, may have beneficial effects on reducing inflammatory status. This trial was registered at http://www.clinicaltrials.gov as NCT01725945.

Aging and CMV discordance are associated with increased immune diversity between monozygotic twins

Background

Broadly, much of variance in immune system phenotype has been linked to the influence of non-heritable factors rather than genetics. In particular, two non-heritable factors: aging and human cytolomegavirus (CMV) infection, have been known to account for significant inter-individual immune variance. However, many specific relationships between them and immune composition remain unclear, especially between individuals over narrower age ranges. Further exploration of these relationships may be useful for informing personalized intervention development.

Results

To address this need, we evaluated 41 different cell type frequencies by mass cytometry and identified their relationships with aging and CMV seropositivity. Analyses were done using 60 healthy individuals, including 23 monozygotic twin pairs, categorized into young (12–31 years) and middle-aged (42–59 years). Aging and CMV discordance were associated with increased immune diversity between monozygotic twins overall, and particularly strongly in various T cell populations. Notably, we identified 17 and 11 cell subset frequencies as relatively influenced and uninfluenced by non-heritable factors, respectively, with results that largely matched those from studies on older-aged cohorts. Next, CD4+ T cell frequency was shown to diverge with age in twins, but with lower slope than in demographically similar non-twins, suggesting that much inter-individual variance in this cell type can be attributed to interactions between genetic and environmental factors. Several cell frequencies previously associated with memory inflation, such as CD27- CD8+ T cells and CD161+ CD4+ T cells, were positively correlated with CMV seropositivity, supporting findings that CMV infection may incur rapid aging of the immune system.

Conclusions

Our study confirms previous findings that aging, even within a relatively small age range and by mid-adulthood, and CMV seropositivity, both contribute significantly to inter-individual immune diversity. Notably, we identify several key immune cell subsets that vary considerably with aging, as well as others associated with memory inflation which correlate with CMV seropositivity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12979-021-00216-1.

Immune cell profiles associated with measured exposure to phthalates in the Norwegian EuroMix biomonitoring study - A mass cytometry approach in toxicology

BACKGROUND

Phthalate exposure has been associated with immune-related diseases such as asthma and allergies, but there is limited knowledge on mechanisms, effect biomarkers and thus biological support of causality.

OBJECTIVES

To investigate associations between exposure to the phthalates DEHP (di(2-ethylhexyl) phthalate) and DiNP (diisononyl phthalate) and functional immune cell profiles.

METHODS

Peripheral blood mononuclear cells (PBMCs) from 32 healthy adult Norwegian participants in the EuroMix biomonitoring study were selected based on high or low (n = 16) levels of urine metabolites of DEHP and DiNP. High-dimensional immune cell profiling including phenotyping and functional markers was performed by mass cytometry (CyTOF) using two broad antibody panels after PMA/ionomycin-stimulation. The CITRUS algorithm with unsupervised clustering was used to identify group differences in cell subsets and expression of functional markers, verified by manual gating.

RESULTS

The group of participants with high phthalate exposure had a higher proportion of some particular innate immune cells, including CD11c positive NK-cell and intermediate monocyte subpopulations. The percentage of IFNγ TNFα double positive NK cells and CD11b expression in other NK cell subsets were higher in the high exposure group. Among adaptive immune cells, however, the percentage of IL-6 and TNFα expressing naïve B cell subpopulations and the percentage of particular naïve cytotoxic T cell populations were lower in the high exposure group.

DISCUSSION

Cell subset percentages and expression of functional markers suggest that DEHP and DiNP phthalate exposure may stimulate subsets of innate immune cells and suppress adaptive immune cell subsets. By revealing significant immunological differences even in small groups, this study illustrates the promise of the broad and deep information obtained by high-dimensional single cell analyses of human samples to answer toxicological questions regarding health effects of environmental exposures.

Maternal use of nicotine products and breastfeeding 3 months postpartum

AIM

We aimed to determine the prevalence of and factors associated with maternal use of nicotine products in relation to breastfeeding.

METHODS

Nicotine use 3 months postpartum was determined in the Scandinavian PreventADALL mother-child birth cohort study recruiting 1837 women from 2014 to 2016. Electronic questionnaires at 18 weeks pregnancy and 3 months postpartum provided information on snus use, smoking or other nicotine use, infant feeding and socio-economic factors. The risk of nicotine use in relation to breastfeeding was analysed with logistic regression.

RESULTS

Overall, 5.6% of women used snus (2.9%), smoked (2.7%) or both (n = 2) 3 months postpartum, while one used other nicotine products. Among the 1717 breastfeeding women, 95.1% reported no nicotine use, while 2.4% used snus, 2.5% smoked and one dual user. Compared to 3.7% nicotine use in exclusively breastfeeding women (n = 1242), the risk of nicotine use increased by partly (OR 2.26, 95% CI 1.45-3.52) and no breastfeeding (OR 4.58, 95% CI 2.57-8.21). Nicotine use before (14.5% snus, 16.4% smoking) or in pregnancy (0.2% snus, 0.4% smoking) significantly increased the risk of using nicotine during breastfeeding.

CONCLUSION

Few breastfeeding women used snus or smoked 3 months postpartum, with increased risk by nicotine use before or during pregnancy.

Prenatal exposure to perfluoroalkyl substances modulates neonatal serum phospholipids, increasing risk of type 1 diabetes

In the last decade, increasing incidence of type 1 diabetes (T1D) stabilized in Finland, a phenomenon that coincides with tighter regulation of perfluoroalkyl substances (PFAS). Here, we quantified PFAS to examine their effects, during pregnancy, on lipid and immune-related markers of T1D risk in children. In a mother-infant cohort (264 dyads), high PFAS exposure during pregnancy associated with decreased cord serum phospholipids and progression to T1D-associated islet autoantibodies in the offspring. This PFAS-lipid association appears exacerbated by increased human leukocyte antigen-conferred risk of T1D in infants. Exposure to a single PFAS compound or a mixture of organic pollutants in non-obese diabetic mice resulted in a lipid profile characterized by a similar decrease in phospholipids, a marked increase of lithocholic acid, and accelerated insulitis. Our findings suggest that PFAS exposure during pregnancy contributes to risk and pathogenesis of T1D in offspring.

Perfluoroalkyl substances, airways infections, allergy and asthma related health outcomes - implications of gender, exposure period and study design

INTRODUCTION

Exposure to perfluoroalkyl substances (PFASs) has been inconsistently associated with asthma, allergic diseases and airways infections in early childhood. The aim of the study was, therefore, to investigate the effect of childhood exposure to PFASs on asthma and allergy related outcomes and on airways infections before and during puberty using the prospective birth cohort Environment and Childhood Asthma (ECA) Study. Aspects of gender, exposure period and study design (cross-sectional and longitudinal) were also taken into consideration.

MATERIAL AND METHODS

Included in the study was 378 participants with PFAS measurements at age 10 years and follow-up data at ages 10 years (cross sectional data) and 16 years (longitudinal data). Eight PFASs with at least 70% of measurements above the limit of quantification (LOQ) in the child's serum were included in the present study: perfluoroheptanoate (PFHpA), perfluorooctanoate (PFOA), perfluourononanoate (PFNA), perfluorodecanoate (PFDA), perfluoroundecanoate (PFUnDA), perfluorohexane sulfonate (PFHxS), perfluoroheptane sulfonate (PFHpS) and perfluorooctane sulfonate (PFOS). The PFAS levels were converted into interquartile range (IQR). In addition, perfluorooctane sulfonamide (PFOSA) detected in 60% of the samples, was recoded into "not detected /detected". Binomial, multinomial and linear regression were used, followed by Bonferroni adjustment to correct for multiple comparisons. Sensitivity analyses evaluating the effect of extreme PFAS values and gender were performed.

RESULTS

In the cross sectional data at 10 years a positive statistically significant association was seen between PFHpA and asthma in girls. In the longitudinal data, PFNA, PFDA and PFUnDA were inversely associated with atopic dermatitis (AD) in girls and with PFHxS in all participants and in boys. Further, PFNA and PFHpS were positively associated with rhinitis in girls and with PFOA in all participants. There seems to be a suggestive pattern of increased risk of allergic sensitisation in all participants and a decreased risk in boys, but due to different results in main and sensitivity analyses these findings should be interpreted with caution. No associations were found between PFASs and lung function. For airways infections and longitudinal data, PFDA was inversely associated with common cold, while positive association was found for PFHpA, PFOA, PFHpS and PFOS and lower respiratory tract infections (LRTI).

DISCUSSION AND CONCLUSION

Our results lend further support for an immunosuppressive effect of PFASs on AD and LRTI. Gender seems to be important for some exposure-health associations. No clear pattern in exposure-health associations was observed with regard to exposure period or study design, with the exception of asthma where significant findings have mostly been reported in cross-sectional studies.

Maternal levels of perfluoroalkyl substances (PFASs) during pregnancy and childhood allergy and asthma related outcomes and infections in the Norwegian Mother and Child (MoBa) cohort

INTRODUCTION

Prenatal exposure to perfluoroalkyl substances (PFASs) has been inconsistently associated with asthma and allergic diseases and increased number of infections in early childhood. We examined the association of PFASs measured in pregnancy with childhood asthma, allergies and common infectious diseases in a prospective pregnancy cohort followed to age 7 years.

MATERIAL AND METHODS

Six PFASs (out of 19 measured) with at least 80% of measurements above the limit of quantification (LOQ) in maternal plasma during pregnancy in two subcohorts of the Norwegian Mother and Child Cohort Study (MoBa) were analyzed in relation to health outcomes: perfluorooctane sulfonic acid (PFOS), acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), perfluoroundecanoic acid (PFUnDA), and perfluoroheptane sulfonic acid (PFHpS). Follow-up questionnaires were completed at 3 years by 1270 women and at 7 years by 972 women among the 1943 with pregnancy questionnaire and PFAS measures. Health outcomes included parent reports of child's symptoms or doctor diagnosed asthma and allergic conditions at age 7 years and parent-reported frequency of various infections at 3 and 7 years of age. Logistic and Poisson regression were used. The false discovery rate was controlled at 5%. Sensitivity analyses on gender were performed.

RESULTS

Among the allergy and asthma outcomes, a statistically significant inverse association was seen between PFUnDA concentrations and ever having atopic eczema in girls. PFUnDA also tended to be inversely associated with both wheeze and asthma. For infections from 0 to 3 and 6 to 7 years, 11 significant positive associations were seen between PFASs and airways infections (bronchitis/pneumonia, throat infection, pseudocroup), ear infection and gastric flu/diarrhea; whereas 6 inverse associations were seen for pseudocroup, ear infections and urinary tract infections. The majority of the findings with respect to infectious diseases were found in girls only.

DISCUSSION

With the exception of an inverse association between PFUnDA and eczema, and a tendency of a similar association for wheeze and asthma, maternal PFAS levels during pregnancy showed little association with asthma or allergy related outcomes. Findings from the present study suggest immunosuppressive effects of PFASs on airways infections, such as bronchitis/pneumonia and throat infections, as well as diarrhea/gastric flu. Our results indicate a possible role of gender in the PFAS-health outcome associations.

Feasibility of desensitizing children highly allergic to peanut by high-dose oral immunotherapy

BACKGROUND

There are limited data on the feasibility, efficacy and safety of high-dose oral immunotherapy (OIT) in children highly allergic to peanuts.

OBJECTIVE

In children highly allergic to peanut, we primarily aimed to determine the feasibility of reaching the maximum maintenance dose (MMD) of 5000 mg peanut protein or, alternatively, a lower individual maintenance dose (IMD), by OIT up-dosing. Secondarily, we aimed to identify adverse events (AEs) and determine factors associated with reaching a maintenance dose.

METHODS

The TAKE-AWAY peanut OIT trial enrolled 77 children 5-15 years old, with a positive oral peanut challenge. Fifty-seven were randomized to OIT with biweekly dose step-up until reaching MMD or IMD and 20 to observation only. Demographic and biological characteristics, AEs, medication and protocol deviations were explored for associations with reaching maintenance dose.

RESULTS

All children had anaphylaxis defined by objective symptoms in minimum two organ systems during baseline challenge. The MMD was reached by 21.1%, while 54.4% reached an IMD of median (minimum, maximum) 2700 (250, 4000) mg peanut protein, whereas 24.5% discontinued OIT. During up-dosing, 19.4% experienced anaphylaxis. Not reaching the MMD was caused by distaste for peanuts (66.7%), unacceptable AEs (26.7%) and social reasons (6.7%). Increased peanut s-IgG₄ /s-IgE ratio (OR [95% CI]: 1.02 [1.00, 1.04]) was associated with reaching MMD.

CONCLUSION

Although 75.5% of children with peanut anaphylaxis reached a maintenance dose of 0.25-5 g, only 21.1% reached the MMD. Distaste for peanuts and AEs, including high risk of anaphylaxis, limited the feasibility of reaching MMD.

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.

Prenatal exposure to perfluoralkyl substances (PFASs) associated with respiratory tract infections but not allergy- and asthma-related health outcomes in childhood

BACKGROUND

Prenatal exposure to perfluoralkyl substances (PFASs) has been reported to be associated with immunosuppression in early childhood, but with contradictory findings related to atopic and lung diseases.

AIM

We aimed to determine if prenatal exposure to PFASs is associated with asthma or other allergic diseases or respiratory tract infections in childhood.

METHODS

Nineteen PFASs were measured in cord blood available from 641 infants in the Environment and Childhood Asthma (ECA) prospective birth cohort study. The six most abundant PFASs were perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorooctanesulfonamide (PFOSA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUnDA). Health outcomes were assessed at two and ten years of age, and included reported obstructive airways disease (wheeze by 10 years; asthma by 2 and 10 years; reduced lung function at birth; allergic rhinitis by 10 years), atopic dermatitis (AD) by 2 and 10 years, allergic sensitization by 10 years, and episodes of common respiratory tract infections (common cold by 2 years, lower respiratory tract infections (LRTI) by 10 years). The associations between exposure and health outcomes were examined using logistic and Poisson regression.

RESULTS

The number of reported airways infections were significantly associated with cord blood concentrations of PFAS; common colds by two years with PFUnDA (β = 0.11 (0.08-0.14)) and LRTIs from 0 to 10 years of age with PFOS (β = 0.50 (0.42-0.57)), PFOA (β = 0.28 (0.22-0.35)), PFOSA (β = 0.10 (0.06-0.14)), PFNA (β = 0.09 (0.03-0.14)) and PFUnDA (β = 0.18 (0.13-0.23)) concentrations. Neither reduced lung function at birth, asthma, allergic rhinitis, AD nor allergic sensitization were significantly associated with any of the PFASs.

CONCLUSION

Although prenatal exposure to PFASs was not associated with atopic or lung manifestations by 10 years of age, several PFASs were associated with an increased number of respiratory tract infections in the first 10 years of life, suggesting immunosuppressive effects of PFASs.

Mineral oil saturated hydrocarbons (MOSH) in female Fischer 344 rats; accumulation of wax components; implications for risk assessment

Female Fischer 344 rats were exposed to three MOSH mixtures: oils largely below and above C₂₅ (S-C25 and L-C25) and a 1:1 mixture of L-C25 with a wax; doses of 400, 1000 and 4000mg/kg feed were administered during 120days. MOSH were determined by on-line HPLC-GC-FID in liver, spleen, adipose tissue and the carcass. The composition of the hydrocarbons accumulated in the tissues was further analyzed by comprehensive two-dimensional GC (GC×GC). MOSH in the mass range of C_26-30 were more strongly accumulated than those between C_20-25, which does not support the present classification of MOSH differentiating at n-C₂₅ for risk assessment. Compared to the total of the MOSH, n-alkanes and n-alkyl monocyclic naphthenes were generally enriched in adipose tissue. In liver and spleen, n-alkanes up to C₂₅ were eliminated, but strongly accumulated at around C₃₀. Based on this profile, poor solubility and the melting points, it is hypothesized that crystallization protects these wax components against metabolism and elimination. In the liver, relative retention of n-alkanes decreased again beyond C₃₀, accentuated at high exposure, suggesting reduced absorption. Compared to the animal data, accumulation of n-alkanes from food sources, such as apples, into human tissues seems low, perhaps because of low absorption due to their presence in crystalline form. A series of dominant isoalkanes, accumulated in all tissues analyzed, was characterized, though without proposing a structure. Implications on present regulation of white mineral oil products are discussed.

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.

Accumulation of mineral oil saturated hydrocarbons (MOSH) in female Fischer 344 rats: Comparison with human data and consequences for risk assessment

Female Fischer 344 rats were orally exposed to a mixture of mineral oil saturated hydrocarbons (MOSH) of broad molecular mass range at doses of 40, 400 and 4000mg/kg feed. Amounts and compositions of the MOSH were analyzed in liver, spleen, adipose tissue and the carcass after exposure during 30, 60, 90 and 120d as well as after 90d exposure followed by 30d depuration. At 40mg/kg in the feed, after 30d of exposure, 10.9% of the ingested MOSH were recovered from the animal body; after 90d plus 30d depuration it was 3.9%. In liver and spleen, the maximum retention in terms of molecular mass (simulated distillation) was at n-C₂₉; in adipose tissue and carcass it was at n-C_15/16. The differentiation between MOSH below and above n-C₂₅ (Class I versus Class II and III oils), used for present regulation, is not supported by the present data on accumulation; structural characteristics seem more pertinent than molecular mass. Concentrations in the tissues increased far less than proportionally with the dose, rendering linear extrapolation to low doses questionable. No steady state was reached after 120d. In fact, comparing with the concentrations in human tissues at the estimated exposure, extrapolation from animal experiments seems to grossly underestimate human internal exposure. Comprehensive two-dimensional gas chromatography (GCxGC) was used to characterize the MOSH residues in the tissues with the aim of identifying the most strongly accumulated types. In the liver and spleen, the highly branched hydrocarbons dominated, whereas in the adipose tissue it was the n-alkanes and species with main n-alkyl moieties. Strong MOSH accumulation is not of concern per se, but the safety at the high concentrations in human tissues needs to be re-evaluated, possibly taking into account also end points other than granuloma formation.

Exposure of Norwegian toddlers to perfluoroalkyl substances (PFAS): The association with breastfeeding and maternal PFAS concentrations

High exposure to perfluoroalkyl substances (PFASs) has been associated with adverse health effects in children. PFASs exposure pathways of toddlers might differ from those of infants and adults, and the investigations on determinants of PFASs exposure in early childhood are scarce. Our aims were to examine the PFAS blood concentrations in Norwegian toddlers and to assess their relationship with maternal PFAS concentrations in pregnancy and breastfeeding duration. We determined PFAS concentrations in 112 plasma samples of 3-year-old children collected at 2010-2011 and 99 maternal serum samples collected around delivery at 2007-2008. PFAS concentrations in children were regressed on duration of breastfeeding, and the effect modification by maternal prenatal PFAS concentrations was examined in 55 mother-child pairs. Six PFASs were quantifiable in >50% of both maternal and children samples. Positive and significant correlations ranging between 0.50 and 0.66 were found between maternal and child concentrations of the same PFAS congeners. Nevertheless, toddlers had higher total PFAS blood concentrations than their mothers, due to higher concentrations of PFOA, PFNA and PFHxS. Every month of breastfeeding was associated with an increase of 3.3% (95% Confidence Intervals (CI): 0.8-5.8) for PFOS, 4.7% (95%CI: 2.8-6.6) for PFOA and 6.1% (95% CI: 2.6-9.7) for PFHpS in toddlers' plasma and a dose-response association was found, after adjustment for confounders. However, PFNA and PFUnDA concentrations in children were not associated with either maternal concentrations or breastfeeding duration. Our findings suggest that transplacental transfer, prenatally, and breastfeeding, postanatally, are among the main determinants of PFOS, PFOA, PFHxS and PFHpS concentrations in toddlers, while that was not the case for PFNA and PFUnDA. Nevertheless, due to the small number of mother child-pairs in our study, our results should be interpreted with caution.

Cord blood gene expression supports that prenatal exposure to perfluoroalkyl substances causes depressed immune functionality in early childhood

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a class of synthetic compounds that have widespread use in consumer and industrial applications. PFAS are considered environmental pollutants that have various toxic properties, including effects on the immune system. Recent human studies indicate that prenatal exposure to PFAS leads to suppressed immune responses in early childhood. In this study, data from the Norwegian BraMat cohort was used to investigate transcriptomics profiles in neonatal cord blood and their association with maternal PFAS exposure, anti-rubella antibody levels at 3 years of age and the number of common cold episodes until 3 years. Genes associated with PFAS exposure showed enrichment for immunological and developmental functions. The analyses identified a toxicogenomics profile of 52 PFAS exposure-associated genes that were in common with genes associated with rubella titers and/or common cold episodes. This gene set contains several immunomodulatory genes (CYTL1, IL27) as well as other immune-associated genes (e.g. EMR4P, SHC4, ADORA2A). In addition, this study identified PPARD as a PFAS toxicogenomics marker. These markers can serve as the basis for further mechanistic or epidemiological studies. This study provides a transcriptomics connection between prenatal PFAS exposure and impaired immune function in early childhood and supports current views on PPAR- and NF-κB-mediated modes of action. The findings add to the available evidence that PFAS exposure is immunotoxic in humans and support regulatory policies to phase out these substances.

Polycyclic aromatic hydrocarbons, tobacco smoke, and epigenetic remodeling in asthma

Environmental determinants including aerosolized pollutants such as polycyclic aromatic hydrocarbons (PAHs) and tobacco smoke have been associated with exacerbation and increased incidence of asthma. The influence of aerosolized pollutants on the development of immune dysfunction in asthmatics has been suggested to be mediated through epigenetic remodeling. Genome accessibility and transcription are regulated primarily through DNA methylation, histone modification, and microRNA transcript silencing. Epigenetic remodeling has been shown in studies to be associated with Th2 polarization and associated cytokine and chemokine regulation in the development of asthma. This review will present evidence for the contribution of the aerosolized pollutants PAH and environmental tobacco smoke to epigenetic remodeling in asthma.

Pulmonary phthalate exposure and asthma - is PPAR a plausible mechanistic link?

Due to their extensive use as plasticisers in numerous consumer products, phthalates have become ubiquitous environmental contaminants. An increasing number of epidemiological studies suggest that exposure to phthalates may be associated with worsening or development of airway diseases. Peroxisome Proliferation Activated Receptors (PPAR)s, identified as important targets for phthalates in early studies in rodent liver, have been suggested as a possible mechanistic link. In this review we discuss the likelihood of an involvement of PPARs in asthma development and exacerbation due to pulmonary phthalate exposure. First, we go through the literature on indoor air levels of phthalates and pulmonary phthalate kinetics. These data are then used to estimate the pulmonary phthalate levels due to inhalation exposure. Secondly, the literature on phthalate-induced activation or modulation of PPARs is summarized. Based on these data, we discuss whether pulmonary phthalate exposure is likely to cause PPAR activation, and if this is a plausible mechanism for adverse effects of phthalates in the lung. It is concluded that the pulmonary concentrations of some phthalates may be sufficient to cause a direct activation of PPARs. Since PPARs mainly mediate anti-inflammatory effects in the lungs, a direct activation is not a likely molecular mechanism for adverse effects of phthalates. However, possible modulatory effects of phthalates on PPARs deserve further investigation, including partial antagonist effects and/or cross talk with other signalling pathways. Moreover other mechanisms, including interactions between phthalates and other receptors, could also contribute to possible adverse pulmonary effects of phthalates.

Offspring IgE responses are influenced by levels of maternal IgG transferred in early life

PROBLEM

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.

METHOD OF STUDY

Pregnant mice were immunized (IMM) with ovalbumin (OVA) or immunized and airway-challenged (IMM+AI). At different ages, airway allergy to OVA was induced in offspring by intranasal sensitization.

RESULTS

Maternal IgG1 was found at higher levels in IMM+AI than in IMM offspring. After sensitization, the suppression of OVA-specific IgE and IgG1 was complete in juvenile offspring but waned with age concurrently with maternal IgG1 levels. Cytokine secretion, lung inflammation, and B cell priming were not suppressed although IgE responses were.

CONCLUSIONS

High compared with low levels of maternal IgG1 were associated with lower TH 2 antibody production after adult offspring were re-exposed to OVA. Thus, offspring allergy-related responses appeared to be shaped by maternal antibody levels.

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.

Pre-natal exposure to perfluoroalkyl substances may be associated with altered vaccine antibody levels and immune-related health outcomes in early childhood

Perfluoroalkyl substances (PFAS) are suggested to have immunosuppressive effects; exposure in utero and in the first years of life is of special concern as fetuses and small children are highly vulnerable to toxicant exposure. The objective of this study was to investigate the effect of pre-natal exposure to PFAS on responses to pediatric vaccines and immune-related health outcomes in children up to 3 years of age. In the prospective birth-cohort BraMat, a sub-cohort of the Norwegian Mother and Child Cohort Study (MoBa), pregnant women from Oslo and Akershus, Norway, were recruited during 2007-2008. Three annual questionnaire-based follow-ups were performed. Blood samples were collected from the mothers at the time of delivery and from the children at the age of 3 years. As a measure of pre-natal exposure to PFAS, the concentrations of perfluorooctanoate (PFOA), perfluorononanoate (PFNA), perfluorohexane sulfonate (PFHxS), and perfluorooctane sulfonate (PFOS) were determined in maternal blood from 99 BraMat participants. Main outcome measures were anti-vaccine antibody levels, common infectious diseases and allergy- and asthma-related health outcomes in the children up to the age of 3 years. There was an inverse association between the level of anti-rubella antibodies in the children's serum at age 3 years and the concentrations of the four PFAS. Furthermore, there was a positive association between the maternal concentrations of PFOA and PFNA and the number of episodes of common cold for the children, and between PFOA and PFHxS and the number of episodes of gastroenteritis. No associations were found between maternal PFAS concentrations and the allergy- and asthma-related health outcomes investigated. The results indicate that pre-natal exposure to PFAS may be associated with immunosuppression in early childhood.

Early Combination of Material Characteristics and Toxicology Is Useful in the Design of Low Toxicity Carbon Nanofiber

This paper describes an approach for the early combination of material characterization and toxicology testing in order to design carbon nanofiber (CNF) with low toxicity. The aim was to investigate how the adjustment of production parameters and purification procedures can result in a CNF product with low toxicity. Different CNF batches from a pilot plant were characterized with respect to physical properties (chemical composition, specific surface area, morphology, surface chemistry) as well as toxicity by in vitro and in vivo tests. A description of a test battery for both material characterization and toxicity is given. The results illustrate how the adjustment of production parameters and purification, thermal treatment in particular, influence the material characterization as well as the outcome of the toxic tests. The combination of the tests early during product development is a useful and efficient approach when aiming at designing CNF with low toxicity. Early quality and safety characterization, preferably in an iterative process, is expected to be efficient and promising for this purpose. The toxicity tests applied are preliminary tests of low cost and rapid execution. For further studies, effects such as lung inflammation, fibrosis and respiratory cancer are recommended for the more in-depth studies of the mature CNF product.

Toxicogenomic profiles in relation to maternal immunotoxic exposure and immune functionality in newborns

A crucial period for the development of the immune system occurs in utero. This results in a high fetal vulnerability to immunotoxic exposure, and indeed, immunotoxic effects have been reported, demonstrating negative effects on immune-related health outcomes and immune functionality. Within the NewGeneris cohort BraMat, a subcohort of the Norwegian Mother and Child Cohort Study (MoBa), immunotoxicity was demonstrated for polychlorinated biphenyls and dioxins, showing associations between estimated maternal intake levels and reduced measles vaccination responses in the offspring at the age of 3. The present study aimed to investigate this link at the transcriptomic level within the same BraMat cohort. To this end, whole-genome gene expression in cord blood was investigated and found to be associated with maternal Food Frequency Questionnaires-derived exposure estimates and with vaccination responses in children at 3 years of age. Because the literature reports gender specificity in the innate, humoral, and cell-mediated responses to viral vaccines, separate analysis for males and females was conducted. Separate gene sets for male and female neonates were identified, comprising genes significantly correlating with both 2,3,7,8-tetrachlorodibenzodioxin (TCDD) and polychlorinated biphenyls (PCB) exposure and with measles vaccination response. Noteworthy, genes correlating negatively with exposure in general show positive correlations with antibody levels and vice versa. For both sexes, these included immune-related genes, suggesting immunosuppressive effects of maternal exposure to TCDD and PCB at the transcriptomic level in neonates in relation to measles vaccination response 3 years later.

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.

Determinants of experimental allergic responses: interactions between allergen dose, sex and age

The prevalence of allergic diseases is influenced by sex and age. Although mouse models are widely used in allergy research, few experimental studies have examined the interaction effects of sex and age on allergy outcomes. Our aim was to investigate the individual and combined effects of sex and age on allergic sensitization and inflammation in two mouse models: an intraperitoneal (i.p.) and an intranasal (i.n.) sensitization model. We also investigated how the allergen immunization dose interacted with age and sex in the i.p. model. Female and male mice were immunized i.p. or i.n. with ovalbumin when 1, 6 or 20 weeks old. In both models, allergen challenges were performed by i.n. delivery. Serum antibodies, draining lymph node cytokine release and airway inflammatory responses were assessed. In the i.p. model, the antibody and cytokine levels and airway inflammation were highly influenced by immunization dose and age. The responses increased with age when using a low immunization dose, but decreased with age when using a high immunization dose. In the i.n. model, antibody production and airway tissue inflammation increased with age. Female compared with male mice generally developed more pronounced antibody and inflammatory responses. Relative to older mice, juvenile mice had augmented airway inflammation to allergen exposures. The study demonstrates that immunization dose, sex and age are highly influential on allergy outcomes. To better mimic different life stages of human allergic airway disease, murine models, therefore, require careful optimization.

In vitro cytokine release from human peripheral blood mononuclear cells in the assessment of the immunotoxic potential of chemicals

Alternative methods to the use of animals in testing of chemicals are needed. We investigated if the immunotoxic potential of 12 dietary toxicants could be predicted from effects on cytokine release from human peripheral blood mononuclear cells (PBMC) after in vitro exposure. Nine cytokines were selected to reflect different types of immune responses. The toxicants were classified as immunotoxic or non-immunotoxic substances according to the published in vivo data. Isolated human PBMC were exposed for 20 h to three concentrations of each of the 12 substances in the presence of human liver S9 fraction. After further incubation of PBMC in fresh medium containing the mitogen phytohemagglutinin (PHA, 10 μg/ml) for 48 h, release of the nine selected cytokines into the supernatant as well as cell proliferation were measured by Luminex technology™ and the BrdU incorporation assay, respectively. All 12 substances investigated affected the release of one or more cytokines, and each of the substances showed different cytokine release patterns. Within the limitations of the study design, the present study suggests that the effect of the substances on mitogen-induced cytokine release from PBMC cannot predict their immunotoxic potential, but may be useful in mechanistic studies.

Transcriptomic profile indicative of immunotoxic exposure: in vitro studies in peripheral blood mononuclear cells

Investigating the immunotoxic effects of exposure to chemicals usually comprises evaluation of weight and histopathology of lymphoid tissues, various lymphocyte parameters in the circulation, and immune function. Immunotoxicity assessment is time consuming in humans or requires a high number of animals, making it expensive. Furthermore, reducing the use of animals in research is an important ethical and political issue. Immunotoxicogenomics represents a novel approach to investigate immunotoxicity able of overcoming these limitations. The current research, embedded in the European Union project NewGeneris, aimed to retrieve gene expression profiles that are indicative of exposure to immunotoxicants. To this end, whole-genome gene expression was investigated in human peripheral blood mononuclear cells in response to in vitro exposure to a range of immunotoxic chemicals (4-hydroxy-2-nonenal, aflatoxin B1, benzo[a]pyrene, deoxynivalenol, ethanol, malondialdehyde, polychlorinated biphenyl 153, and 2,3,7,8-tetrachlorodibenzo-p-dioxin) and nonimmunotoxic chemicals (acrylamide, dimethylnitrosamine, 2-amino-3-methyl-3H-imidazo[4,5-F]quinoline, and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). Using Agilent oligonucleotide microarrays, whole-genome gene expression profiles were generated, which were analyzed using Genedata's Expressionist software. Using Recursive Feature Elimination and Support Vector Machine, a set of 48 genes was identified that distinguishes the immunotoxic from the nonimmunotoxic compounds. Analysis for enrichment of biological processes showed the gene set to be highly biologically and immunologically relevant. We conclude that we have identified a promising transcriptomic profile indicative of immunotoxic exposure.

Maternal allergen immunisation to prevent sensitisation in offspring: Th2-polarising adjuvants are more efficient than a Th1-polarising adjuvant in mice

Background

Allergy has been an increasing problem in several parts of the world. Prenatal exposure to allergen and microbial components may affect the development of allergies in childhood, as indicated by epidemiological and experimental studies. We investigated the capacity for allergic sensitisation in offspring after induction of a Th1- or a Th2-polarised immune response to the same allergen in mothers during pregnancy.

Results

During pregnancy, mice were immunised with ovalbumin (OVA) given with either one of the Th2-adjuvants pertussis toxin (PT) or Al(OH)₃ (aluminium hydroxide), or with the Th1 adjuvant CpG. Offspring were immunised with OVA in Al(OH)₃ as young adults. Serum and supernatants from ex vivo stimulated or non-stimulated spleen cells from mothers and offspring were analysed for OVA-specific antibodies and cytokines, respectively. Mothers immunised with OVA together with either Al(OH)₃ or PT had increased levels of OVA-specific IgE and IgG1 compared to naive mothers, whereas mothers immunised with OVA together with CpG had increased levels of OVA-specific IgG2a compared to naive mothers. In general the highest levels of IL-5, IL-10, and IFNγ were observed in spleen cells from mothers immunised with PT and OVA. Upon immunisation, offspring from mothers immunised with OVA and either PT or Al(OH)₃ showed reduced levels of OVA-specific IgE and IgG1 and increased levels of OVA-specific IgG2a antibodies compared to offspring from naive mothers. Maternal immunisation with CpG and OVA did not affect antibody responses in offspring.

Conclusion

Allergic sensitisation in the offspring was affected by the type of adjuvant used for immunisation of the mothers with the same allergen. Th2 polarisation of the immune response in the mothers was found to give reduced IgE levels upon sensitisation of the offspring, whereas no reduction was achieved with Th1 polarisation in the mothers.

Particle size determines activation of the innate immune system in the lung

Our knowledge about particle size in relation to activation of the innate immune system is limited. Therefore, the acute effect of particle exposure on the innate immune system was studied in a lung model using the intracellular bacterium Listeria monocytogenes. Female Balb/cA mice were instilled intratracheally with polystyrene particles (PSP) of different diameters (0.064, 0.202, 1.053 and 4.646 mum) simultaneously with or 1 day prior to inoculation of 10(5) bacteria. Mice were sacrificed 1 day after Listeria challenge, and the numbers of viable bacteria in the lungs and the spleen were determined as a measure of cellular activation. In separate experiments, bronchoalveolar lavage (BAL) fluid was collected. Only mice exposed to the smallest PSP (0.064 and 0.202 mum) had significantly reduced bacterial numbers in the lung after particles and Listeria were given simultaneously. When particles were given 1 day prior to Listeria challenge also the largest 4.646 mum PSP, but not the medium size 1.053 mum PSP, reduced bacterial numbers. The number of neutrophils in BAL fluid was increased for all PSP-exposed groups after 24 h, and tended to be highest in the group exposed to 4.646 mum PSP. TNF-alpha, IL-1beta and MIP-2 were significantly increased in BAL fluid after exposure to the largest compared with the smallest PSP. In conclusion, activation of the innate immune system by chemical-free particles was size-dependent. Ultrafine and coarse particles appeared to activate cells by different mechanisms, which implies qualitative differences between the health effects of ambient air particulate matter size fractions.