Type 1 and Type 2 cytokines imbalance in adult male C57BL/6 mice following a 7-day oral exposure to perfluorooctanesulfonate (PFOS)

Immune cell profiles associated with human exposure to perfluorinated compounds (PFAS) suggest changes in natural killer, T helper, and T cytotoxic cell subpopulations

Per- and polyfluoroalkyl substances (PFAS) constitutes a group of highly persistent man-made substances. Recent evidence indicates that PFAS negatively impact the immune system. However, it remains unclear how different PFAS are associated with alterations in circulating leukocyte subpopulations. More detailed knowledge of such potential associations can provide better understanding into mechanisms of PFAS immunotoxicity in humans. In this exploratory study, associations of serum levels of common PFAS (perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS)) and immune cell profiles of peripheral blood mononuclear cells, both with and without immunostimulation, were investigated. High-dimensional single cell analysis by mass cytometry was done on blood leukocytes from fifty participants in the Norwegian human biomonitoring EuroMix study. Different PFAS were associated with changes in various subpopulations of natural killer (NK), T helper (Th), and cytotoxic T (Tc) cells. Broadly, PFAS concentrations were related to increased frequencies of NK cells and activated subpopulations of NK cells. Additionally, increased levels of activated T helper memory cell subpopulations point to Th2/Th17 and Treg-like skewed profiles. Finally, PFAS concentrations were associated with decreased frequencies of T cytotoxic cell subpopulations with CXCR3+ effector memory (EM) phenotypes. Several of these observations point to biologically plausible mechanisms that may contribute to explaining the epidemiological reports of immunosuppression by PFAS. Our results suggest that PFAS exposures even at relatively low levels are associated with changes in immune cell subpopulations, a finding which should be explored more thoroughly in a larger cohort. Additionally, causal relationships should be confirmed in experimental studies. Overall, this study demonstrates the strength of profiling by mass cytometry in revealing detailed changes in immune cells at a single cell level.

Asthma and decreased lung function in children exposed to perfluoroalkyl and polyfluoroalkyl substances (PFAS): An updated meta-analysis unveiling research gaps

BACKGROUND AND OBJECTIVE

Associations between exposure to per- and polyfluoroalkyl substances (PFAS) and pediatric asthma and reduced lung function in children are mixed and inconclusive. The study objective was to examine the extant research on exposure to PFAS and the diagnosis of asthma or decreased lung function in children <17 years of age to highlight what is known and to identify research gaps for future investigations.

METHODS

The present review was registered on the PROSPER database (CRD42023407172). We systematically searched several bibliographic databases (Scopus, Embase, Web of Science (core Collection), Medline, and CINAHL) along with grey literature sources in January 2023 to find relevant studies before this date. The National Toxicology Program's Office of Health Assessment and Translation (NTP OHAT) tool was applied to assess the risk of bias (RoB) assessment. We used a random-effects meta-analysis to assess the associations. From 12 observational epidemiological studies (out of 513) explored for qualitative analyses, 4 studies were included in quantitative analyses.

RESULTS

The meta-analysis revealed a significant association between exposures to perfluorooctanoate (PFOA) with the prevalence of children's asthma [Odds Ratios (OR) = 1.162 (95% CI: 1.004-1.321)] whereas the association for perfluorooctane sulfonate (PFOS) was not statistically significant [OR = 1.03 (95%CI: 0.806-1.265]. The narrative synthesis results of the four included studies that examined the effects of PFAS exposure on lung function did not demonstrate significant associations between exposure to PFAS and decreased lung function. The RoB for most included studies was assessed as probably low without serious limitations. However, two studies were at high risk of biases.

CONCLUSION

Our findings suggest that children who are exposed to PFOA are at a higher risk of developing asthma as well as the association between exposure to PFOS with impaired lung function. Large longitudinal studies with homogeneous PFAS exposures and standardized outcome measures are needed to ascertain these outcomes with improved certainty as well as toxicological studies to investigate the underlying mechanisms.

Associations between prenatal exposure to per- and polyfluoroalkyl substances and plasma immune molecules in three-year-old children in China

BACKGROUND

Many studies have reported that prenatal exposure to Per- and Polyfluoroalkyl Substances (PFASs) can disrupt immune function. However, little is known about the effects of PFASs on immune molecules. The study analyzed the association between prenatal exposure to mixed and single PFASs and plasma immune molecules in three-year-old children.

METHODS

Ten PFASs were measured in umbilical cord serum, while peripheral blood samples were collected at age three to measure immune molecules. Associations between exposure to individual and combined PFASs and immune molecules were analyzed using Generalized Linear Models and Weighted Quantile Sum (WQS) regression.

RESULTS

(1) Interleukin-4 (IL-4) increased by 23.85% (95% CI:2.99,48.94) with each doubling of Perfluorooctanoic Acid (PFOA), and Interleukin-6 (IL-6) increased by 39.07% (95%CI:4.06,85.86) with Perfluorotridecanoic Acid (PFTrDA). Elevated PFOA and Perfluorononanoic Acid (PFNA) were correlated with increases of 34.06% (95% CI: 6.41, 70.28) and 24.41% (95% CI: 0.99, 53.27) in Eotaxin-3, respectively. Additionally, the doubling of Perfluorohexane Sulfonic Acid (PFHxS) was associated with a 9.51% decrease in Periostin (95% CI: -17.84, -0.33). (2) The WQS analysis revealed that mixed PFASs were associated with increased IL-6 (β = 0.37, 95%CI:0.04,0.69), mainly driven by PFTrDA, PFNA, and 8:2 Chlorinated Perfluoroethyl Sulfonamide (8:2 Cl-PFESA). Moreover, mixed PFASs were linked to an increase in Eotaxin-3 (β = 0.32, 95% CI: 0.09,0.55), primarily influenced by PFOA, PFTrDA, and Perfluorododecanoic Acid (PFDoDA).

CONCLUSIONS

Prenatal PFASs exposure significantly alters the levels of immune molecules in three-year-old children, highlighting the importance of understanding environmental impacts on early immune development.

Associations of per- and polyfluoroalkyl substances (PFAS) and their mixture with risk of rheumatoid arthritis in the U.S. adult population

BACKGROUND

Per- and polyfluoroalkyl substances (PFAS) are known environmental contaminants with immunosuppressive properties. Their connection to rheumatoid arthritis (RA), a condition influenced by the immune system, is not well studied. This research explores the association between PFAS exposure and RA prevalence.

METHODS

This research utilized data from the NHANES, encompassing a sample of 10,496 adults from the 2003-2018 cycles, focusing on serum levels of several PFAS. The presence of RA was determined based on self-reports. This study used multivariable logistic regression to assess the relationship between individual PFAS and RA risk, adjusting for covariates to calculate odds ratios (ORs). The combined effects of PFAS mixtures were evaluated using BKMR, WQS regression, and quantile g-computation. Additionally, sex-specific associations were explored through stratified analysis.

RESULTS

Higher serum PFOA (OR = 0.88, 95% CI: 0.79, 0.98), PFHxS (OR = 0.91, 95% CI: 0.83, 1.00), PFNA (OR = 0.87, 95% CI: 0.77, 0.98), and PFDA (OR = 0.89, 95% CI: 0.81, 0.99) concentration was related to lower odds of RA. Sex-specific analysis in single chemical models indicated the significant inverse associations were only evident in females. BKMR did not show an obvious pattern of RA estimates across PFAS mixture. The outcomes of sex-stratified quantile g-computation demonstrated that an increase in PFAS mixture was associated with a decreased odds of RA in females (OR: 0.76, 95% CI: 0.62, 0.92). We identified a significant interaction term of the WQS*sex in the 100 repeated hold out WQS analysis. Notably, a higher concentration of the PFAS mixture was significantly associated with reduced odds of RA in females (mean OR = 0.93, 95% CI: 0.88, 0.98).

CONCLUSIONS

This study indicates potential sex-specific associations of exposure to various individual PFAS and their mixtures with RA. Notably, the observed inverse relationships were statistically significant in females but not in males. These findings contribute to the growing body of evidence indicating that PFAS may have immunosuppressive effects.

Systemic and immunotoxicity induced by topical application of perfluorohexane sulfonic acid (PFHxS) in a murine model

Per- and polyfluoroalkyl substances (PFAS) are a large group of stable synthetic surfactants that are incorporated into numerous products for their water and oil resistance and have been associated with adverse health effects. The present study evaluated the systemic and immunotoxicity of sub-chronic 28- or 10-day dermal exposure of PFHxS (0.625-5% or 15.63-125 mg/kg/dose) in a murine model. Elevated levels of PFHxS were detected in the serum and urine, suggesting that absorption is occurring through the dermal route. Liver weight (% body) significantly increased and spleen weight (% body) significantly decreased with PFHxS exposure, which was supported by histopathological changes. Additionally, PFHxS significantly reduced the humoral immune response and altered immune subsets in the spleen, suggesting immunosuppression. Gene expression changes were observed in the liver, skin, and spleen with genes involved in fatty acid metabolism, necrosis, and inflammation. Immune-cell phenotyping identified significant decreases in B-cells, NK cells, and CD11b+ monocyte/macrophages in the spleen along with increases in CD4+ and CD8+ T-cells, NK cells, and neutrophils in the skin. These findings support dermal PFHxS-induced liver damage and immune suppression. Overall, data support PFHxS absorption through the skin and demonstrate immunotoxicity via this exposure route, suggesting the need for further examination.

Prenatal exposure to poly- and perfluoroalkyl substances and the incidence of asthma in early childhood

EXPOSURE TO POLY: and perfluoroalkyl substances (PFAS) in early life may increase the risk of childhood asthma, but evidence has been inconsistent. We estimated associations between maternal serum concentrations of PFAS during pregnancy and clinician-diagnosed asthma incidence in offspring through age eight. We included 597 mother-child pairs with PFAS quantified in mid-pregnancy serum and childhood medical records reviewed for asthma diagnoses. We used separate Cox proportional hazards models to assess the relationship between log-transformed concentrations of five PFAS and the incidence of asthma. We estimated associations between the PFAS mixture and clinician-diagnosed asthma incidence using quantile-based g-computation. PFAS concentrations were similar to those among females in the US general population. Seventeen percent of children (N = 104) were diagnosed with asthma during follow-up. Median (interquartile range) duration of follow-up was 4.7 (4.0, 6.2) years, and median age at asthma diagnosis was 1.7 (0.9, 2.8) years. All adjusted hazard ratios (HRs) were elevated, but all 95% confidence intervals (CI) included the null. The HR (95% CI) of asthma for a one-quartile increase in the PFAS mixture was 1.17 (0.86, 1.61). In this cohort of children followed to eight years of age, prenatal PFAS concentrations were not significantly associated with incidence of clinician-diagnosed asthma.

Legacy and emerging per- and polyfluoroalkyl substances suppress the neutrophil respiratory burst

Per- and polyfluoroalkyl substances (PFASs) are used in a multitude of processes and products, including nonstick coatings, food wrappers, and fire-fighting foams. These chemicals are environmentally-persistent, ubiquitous, and can be detected in the serum of 98% of Americans. Despite evidence that PFASs alter adaptive immunity, few studies have investigated their effects on innate immunity. The report here presents results of studies that investigated the impact of nine environmentally-relevant PFASs [e.g. perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid potassium salt (PFOS-K), perfluorononanoic acid (PFNA), perfluorohexanoic acid (PFHxA), perfluorohexane sulfonic acid (PFHxS), perfluorobutane sulfonic acid (PFBS), ammonium perfluoro(2-methyl-3-oxahexanoate) (GenX), 7H-perfluoro-4-methyl-3,6-dioxa-octane sulfonic acid (Nafion byproduct 2), and perfluoromethoxyacetic acid sodium salt (PFMOAA-Na)] on one component of the innate immune response, the neutrophil respiratory burst. The respiratory burst is a key innate immune process by which microbicidal reactive oxygen species (ROS) are rapidly induced by neutrophils in response to pathogens; defects in the respiratory burst can increase susceptibility to infection. The study here utilized larval zebrafish, a human neutrophil-like cell line, and primary human neutrophils to ascertain whether PFAS exposure inhibits ROS production in the respiratory burst. It was observed that exposure to PFHxA and GenX suppresses the respiratory burst in zebrafish larvae and a human neutrophil-like cell line. GenX also suppressed the respiratory burst in primary human neutrophils. This report is the first to demonstrate that these PFASs suppress neutrophil function and support the utility of employing zebrafish larvae and a human cell line as screening tools to identify chemicals that may suppress human immune function.

Impact of endocrine disruptors on peripheral blood mononuclear cells in vitro: role of gender

Humans can be exposed to endocrine disruptors (EDs) in numerous ways. EDs can interfere with endogenous hormones at different levels, resulting in numerous adverse human health outcomes, including immunotoxicity. In this regard, this study aimed to investigate in vitro the possible effects of EDs on immune cells and possible gender differences. Peripheral blood mononuclear cells from healthy humans, both males and females, were exposed to 6 different EDs, namely atrazine (herbicide), cypermethrin (insecticide), diethyl phthalate (plasticizer), 17α-ethynylestradiol (contraceptive drug), perfluorooctanesulfonic acid (persistent organic pollutant), and vinclozolin (fungicide). We evaluated the effect of EDs on RACK1 (receptor for activated C kinase 1) expression, considering it as a bridge between the endocrine and the immune system, and putatively used as screening tool of immunotoxic effects of EDs. The exposure to EDs resulted at different extent in alteration in RACK1 expression, pro-inflammatory activity, natural killer lytic ability, and lymphocyte differentiation, with sex-related differences. In particular, diethyl phthalate and perfluorooctanesulfonic acid resulted the most active EDs tested, with gender differences in terms of effects and magnitude. The results from our study evidenced the ability of EDs to directly affect immune cells.

Impact of PFAS exposure on prevalence of immune-mediated diseases in adults in the Czech Republic

BACKGROUND

Per- and polyfluoroalkyl substances (PFASs) are emerging environmental contaminants with multiple hazardous properties including immunomodulation potency. Human exposure to PFASs has been associated with various immune-mediated diseases and outcomes. This study aimed to investigate the association between PFAS exposure and immune-mediated diseases such as allergies, eczemas, and autoimmune diseases in a population of adults in the Czech Republic.

METHODS

This study included 309 adults from the Central European Longitudinal Study of Parents and Children: Young Adults (CELSPAC: YA). 12 PFASs were measured in participants' serum by HPLC-MS/MS, 3 PFASs were removed from the subsequent analyses due to low detection frequency. The associations of 9 PFASs with 9 immune-mediated diseases were assessed by logistic regression. Furthermore, Bayesian kernel machine regression (BKMR) was used to estimate the effect of the PFAS mixture on immune-mediated diseases. All analyses were adjusted for sex, age, BMI, smoking, education, and family history of immune-mediated diseases. In cases of a statistically significant interaction of PFASs and sex, stratified analyses were performed for men and women.

RESULTS

Perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) were negatively associated with both atopic eczema (OR per IQR increase 0.58 (95% CI 0.37-0.90) for PFOA and 0.56 (0.32-0.95) for PFOS) and contact dermatitis (0.37 (0.16-0.85) for PFOA and 0.33 (0.11-0.94) for PFOS). Perfluoroundecanoate (PFUnDA) was negatively associated with pollen, dust, and mite allergy (0.62 (0.43-0.89)). BKMR modelling showed a negative tendency in the overall effect of PFAS mixture on immune-health outcomes. Based on the stratified analysis, sex was suggested to be an effect modifier in the association of PFOS and atopic eczema.

CONCLUSION

Our results contribute to the body of literature that observes the immunosuppressive effect of PFAS exposure during eczemas and allergies, both for PFASs individually and as a mixture.

Blood transcriptome responses to PFOA and GenX treatment in the marsupial biomedical model Monodelphis domestica

Introduction: Perfluoroalkyl and poly-fluoroalkyl substances (PFASs) are widely used in industrial and consumer products. Due to their environmental persistence and bioaccumulation, PFASs can be found in the blood of humans and wild animals all over the world. Various fluorinated alternatives such as GenX have been developed to replace the long-chain PFASs, but there is limited information about their potential toxicity. Methods:The current study developed blood culture protocols to assess the response to toxic compounds in the marsupial, Monodelphis domestica. After whole-blood culture conditions were tested and optimized, changes in gene expression in response to PFOA and GenX treatment were assessed. Results: More than 10,000 genes were expressed in the blood transcriptomes with and without treatment. Both PFOA and GenX treatment led to significant changes in the whole blood culture transcriptomes. A total of 578 and 148 differentially expressed genes (DEGs) were detected in the PFOA and GenX treatment groups, 32 of which overlapped. Pathway enrichment analysis revealed that DEGs involved in developmental processes were upregulated after PFOA exposure, while those enriched for metabolic and immune system processes were downregulated. GenX exposure upregulated genes associated with fatty acid transport pathways and inflammatory processes, which is consistent with previous studies using rodent models. Discussion: To our knowledge, this study is the first to investigate the effect of PFASs in a marsupial model. The findings provide supportive evidence for significant transcriptomic alterations, suggesting that this mammalian model may provide a mechanism for exploring the potential toxicity of PFOA and GenX.

Perfluoroalkyl substances (PFASs) decrease the expression of recombination-activating genes (RAG1 and RAG2) in human B lymphoma Namalwa cells

Per- and polyfluoroalkyl substances (PFASs) are omnipresent and have been shown to induce a wide range of adverse effects, including hepatotoxicity, developmental toxicity and immunotoxicity. So far, little information is available about the mechanisms underlying the toxicity of PFASs, including those related to their immunotoxicity. Reported immunotoxic effects of PFASs include decreased antibody responses in experimental animals and humans, indicating that PFASs may, among others, affect B cell function. In the present study, we first assessed the effects of PFOA on the transcriptome of the human Namalwa B cell line using RNA seq analysis. Gene expression changes, analyzed using Ingenuity Pathway Analysis, pointed to various cellular processes affected by PFOA, including 'B cell development' and 'Primary immunodeficiency signaling'. Interestingly, PFOA decreased the expression of RAG1 and RAG2, genes involved in immunoglobulin and T cell receptor V(D)J recombination. As a next step, time- and concentration-dependent changes in the expression of RAG1 and RAG2 upon exposure to PFOA, PFNA, PFHxS and PFOS were studied through RT-qPCR analysis. Analysis with the concentration-response modeling software PROAST resulted in the following potency ranking: PFNA > PFOA > PFOS > PFHxS. Altogether, the present in vitro study provides insights into the effects of selected PFASs on B cells, identifying RAG1 and RAG2 expression as possible relevant targets that may play a role in the immunotoxicity of PFASs.

Immunomodulation and exposure to per- and polyfluoroalkyl substances: an overview of the current evidence from animal and human studies

Per- and polyfluoroalkyl substances (PFAS) have been widely used and represent a class of environmental persistent chemicals. An association of a reduction of vaccination efficacy with PFAS serum levels in humans was used by the European Food Safety Authority as a key effect for PFAS risk assessment. The data support for using this association is reviewed by a critical analysis of the respective human epidemiology and the available animal studies on the immunomodulation of PFAS. Based on an analysis of the available human epidemiology, the overall level of evidence regarding associations between PFAS serum levels and reduced antibody response remains weak. Absence of an association between an increase in clinical infections and PFAS serum levels and the limited understanding of the importance of antibody levels as an isolated data point further support this conclusion. Animal toxicity studies with PFAS focusing on immunomodulation also provide only limited support for immunomodulation as an important endpoint in PFAS toxicity. While immunomodulation is observed after PFAS administration, generally at blood concentrations several orders of magnitude above those seen in environmentally exposed humans, the relevance of these observation is hampered by the high doses required to influence immune endpoints, the limited number of endpoints assessed, and inconsistent results. The limitations of the current database on associations of human PFAS exposures outlined here indicate that more evidence is required to select immunomodulation as a critical endpoint for human PFAS risk assessment.

Allergy from perspective of environmental pollution effects: from an aspect of atopic dermatitis, immune system, and atmospheric hazards-a narrative review of current evidences

Environmental pollution has become more diversified in recent years as technologies for urbanization is increasingly more advanced. Several environmental factors such as air and water pollutants have been linked to allergic symptoms. For instance, because of industrialization for city development in many countries, polluted soil or tiny particles in the air could result in an even more hazardous environment for people to reside. Aside from the aspects of environmental issues, other newly emerging factors such as the electromagnetic field (EMF) also require further investigation. Here, in this narrative review, we focused on allergens from atmospheric and water pollution, hygiene improvement, changes in food trend, and residential environmental pollution. Current evidences regarding the association between various pollutants and the potential clinical diseases could be induced. For people with high skin exposure to air pollutants such as PM 2.5, PM 10, or sulfur dioxide, potential onset of dermatological allergic events should be alerted. The mechanisms involved in allergic diseases are being discussed and summarized. Interactions between immunological mechanisms and clinical implications could potentially provide clearer view to the association between allergic status and pollutants. Moreover, understanding the mechanistic role of allergens can raise awareness to global environment and public health.

Epigenetics at the Intersection of COVID-19 Risk and Environmental Chemical Exposures

PURPOSE OF REVIEW

Several environmental contaminants have been implicated as contributors to COVID-19 susceptibility and severity. Immunomodulation and epigenetic regulation have been hypothesized as mediators of this relationship, but the precise underlying molecular mechanisms are not well-characterized. This review examines the evidence for epigenetic modification at the intersection of COVID-19 and environmental chemical exposures.

RECENT FINDINGS

Numerous environmental contaminants including air pollutants, toxic metal(loid)s, per- and polyfluorinated substances, and endocrine disrupting chemicals are hypothesized to increase susceptibility to the SARS-CoV-2 virus and the risk of severe COVID-19, but few studies currently exist. Drawing on evidence that many environmental chemicals alter the epigenetic regulation of key immunity genes and pathways, we discuss how exposures likely perturb host antiviral responses. Specific mechanisms vary by contaminant but include general immunomodulation as well as regulation of viral entry and recognition, inflammation, and immunologic memory pathways, among others. Associations between environmental contaminants and COVID-19 are likely mediated, in part, by epigenetic regulation of key immune pathways involved in the host response to SARS-CoV-2.

Plasma concentrations of perfluoroalkyl substances and risk of inflammatory bowel diseases in women: A nested case control analysis in the Nurses' Health Study cohorts

BACKGROUND

Perfluoroalkyl substances (PFASs) are synthetic compounds used in a wide variety of industrial and consumer applications. An association between PFAS exposure and risk of ulcerative colitis (UC) has been reported in a highly exposed population. However, data are limited on risk of inflammatory bowel diseases (IBD) among individuals with background population levels of PFAS exposure.

OBJECTIVES

We set out to examine the association between plasma PFAS concentrations and risk of IBD among women in two population-based, prospective cohort studies in which pre-diagnostic blood specimens were available.

METHODS

We conducted a nested case-control study in the Nurses' Health Study and Nurses' Health Study II cohorts. We identified 73 participants with incident Crohn's disease (CD) and 80 participants with incident UC who had provided blood samples before diagnosis. Cases were matched 1:2 to IBD-free controls. Plasma concentrations of five major PFASs were measured by liquid chromatography and tandem mass spectrometry. We used conditional logistic models to estimated odds ratios for risk of IBD according to log10-transformed PFAS concentrations, adjusting for potential confounders.

RESULTS

In multivariable models, we observed inverse associations between plasma concentrations of three PFASs and risk of CD (all P ≤ 0.012 for a standard deviation increase in log10PFAS). The inverse association with CD was strongest for perfluorodecanoate, where, compared to the lowest tertile, the odds ratio (OR) for the highest tertile was 0.39 (95% confidence interval, 0.17-0.92). No associations were observed between PFAS concentrations and UC risk.

DISCUSSION

Our results do not support the hypothesis that elevated PFAS exposure is associated with higher risk of UC. Contrary to expectation, our data suggest that circulating concentrations of some PFASs may be inversely associated with CD development.

SARS-CoV-2 and helminth co-infections, and environmental pollution exposure: An epidemiological and immunological perspective

Soil-transmitted helminths infect billions of people globally, particularly those residing in low- and middle-income regions with poor environmental sanitation and high levels of air and water pollution. Helminths display potent immunomodulatory activity by activating T helper type 2 (Th2) anti-inflammatory and Th3 regulatory immune responses. The Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus that causes Coronavirus disease 2019 (COVID-19), can exacerbate Th1/Th17 pro-inflammatory cytokine production in humans, leading to a cytokine storm. Air pollutants (particulate matter, oxygen radicals, hydrocarbons and volatile organic compounds) and water pollutants (metals and organic chemicals) can also intensify Th1/Th17 immune response and could exacerbate SARS-CoV-2 related respiratory distress and failure. The present review focused on the epidemiology of SARS-CoV-2, helminths and fine particulate matter 2.5 µm or less in diameter (PM2.5) air pollution exposure in helminth endemic regions, the possible immunomodulatory activity of helminths against SARS-CoV-2 hyper-inflammatory immune response, and whether air and water pollutants can further exacerbate SARS-CoV-2 related cytokine storm and in the process hinder helminths immunomodulatory functionality. Helminth Th2/Th3 immune response is associated with reductions in lung inflammation and damage, and decreased expression levels of angiotensin-converting enzyme 2 (ACE2) receptors (SARS-CoV-2 uses the ACE2 receptors to infect cells and associated with extensive lung damage). However, air pollutants are associated with overexpression of ACE2 receptors in the epithelial cell surface of the respiratory tract and exhaustion of Th2 immune response. Helminth-induced immunosuppression activity reduces vaccination efficacy, and diminishes vital Th1 cytokine production immune responses that are crucial for combating early stage infections. This could be reversed by continuous air pollution exposure which is known to intensify Th1 pro-inflammatory cytokine production to a point where the immunosuppressive activities of helminths could be hindered. Again, suppressed activities of helminths can also be disadvantageous against SARS-CoV-2 inflammatory response. This "yin and yang" approach seems complex and requires more understanding. Further studies are warranted in a cohort of SARS-CoV-2 infected individuals residing in helminths and air pollution endemic regions to offer more insights, and to impact mass periodic deworming programmes and environmental health policies.

Exposure, health effects, sensing, and remediation of the emerging PFAS contaminants - Scientific challenges and potential research directions

Per- and polyfluoroalkyl substances (PFAS) make up a large group of persistent anthropogenic chemicals which are difficult to degrade and/or destroy. PFAS are an emerging class of contaminants, but little is known about the long-term health effects related to exposure. In addition, technologies to identify levels of contamination in the environment and to remediate contaminated sites are currently inadequate. In this opinion-type discussion paper, a team of researchers from the University of Connecticut and the University at Albany discuss the scientific challenges in their specific but intertwined PFAS research areas, including rapid and low-cost detection, energy-saving remediation, the role of T helper cells in immunotoxicity, and the biochemical and molecular effects of PFAS among community residents with measurable PFAS concentrations. Potential research directions that may be employed to address those challenges and improve the understanding of sensing, remediation, exposure to, and health effects of PFAS are then presented. We hope our account of emerging problems related to PFAS contamination will encourage a broad range of scientific experts to bring these research initiatives addressing PFAS into play on a national scale.

Effect of Perfluorooctanesulfonic acid (PFOS) on immune cell development and function in mice

Perfluoroctanesulfonate (PFOS) belongs to a larger family of compounds known as Per- and polyfluoroalkyl substances (PFAS). The strength of the carbon-fluorine bond makes PFOS extremely resistant to environmental degradation. Due to its persistent nature, research has been directed to elucidating possible health effects of PFOS on humans and laboratory animals. Here we have explored the effects of PFOS exposure on immune development and function in mice. We exposed adult mice to 3 and 1.5 μg/kg/day of PFOS for 2 and 4 weeks, respectively, and examined the effects of PFOS exposure on populations of T cells, B cells, and granulocytes. These doses of PFOS resulted in serum levels of approximately 100 ng/mL with no weight loss during exposure. We find that PFOS does not affect T-cell development during this time. However, while PFOS exposure reduced immune cell populations in some organs, it also led to an increase in the numbers of cells in others, suggesting possible relocalization of cells. We also examined the effect of PFOS on the response to influenza virus infection. We find that exposure to PFOS at 1.5 μg/kg/day of PFOS for 4 weeks does not affect weight loss or survival, nor is viral clearance affected. Analysis of antibody and T cell specific antiviral responses indicate that at this concentration, PFOS does not suppress the immune cell development or antigen specific immune response.

Drinking water pollutants may affect the immune system: concerns regarding COVID-19 health effects

The current coronavirus pandemic is leading to significant impacts on the planet, changing our way of life. Although the COVID-19 virus mechanisms of action and pathogenesis are still under extensive research, immune system effects are evident, leading, in many cases, to respiratory distress. Although apparent pollution reduction has been noticed by the population, environmental and human health impacts due to the increased use of plastic waste and disinfectants is concerning. One of the main routes of human exposure to pollutants is through drinking water. Thus, this point of view discusses some major contaminants in drinking water known to be immunotoxic, exploring sources and drinking water routes and emphasizing the known mechanisms of action that could likely compromise the effective immune response of humans, particularly raising concerns regarding people exposed to the COVID-19 virus. Based on a literature review, metals, plastic components, plasticizers, and per- and polyfluoroalkyl substances may display the potential to exacerbate COVID-19 respiratory symptoms, although epidemiological studies are still required to confirm the synergistic effects between these pollutants and the virus.

Association between prenatal exposure to perfluoroalkyl substances and respiratory tract infections in preschool children

BACKGROUND

Prenatal exposure to perfluoroalkyl substances (PFAS) is considered to affect adversely the immune function. However, the effect of prenatal PFAS exposure on respiratory tract infections (RTIs) in children is unclear. Thus, we evaluated whether cord blood PFAS levels were associated with RTI in the first 5 years of life.

METHODS

The Shanghai Prenatal Cohort is an on-going birth cohort, which included all the mothers during pregnancy. Children were followed by paediatricians once a year after birth. The levels of 10 PFAS in cord blood were tested using liquid chromatography-mass spectrometry. RTIs were diagnosed based on face-to-face interviews with the parents and review of medical records. Immunoglobulin G (IgG) and immunoglobulin E (IgE) levels, as biomarkers of humoral immunity, were assessed using enzyme-linked immunosorbent assay at age 5 years. Multivariable logistic and linear regression models were applied to study the association between prenatal PFAS exposure and RTIs.

RESULTS

A total of 743 children completed the follow-up, 344 of them had detail information of cord blood PFAS, IgG, and IgE concentrations. Eight PFAS were detected in more than 90% of the cord blood samples, except for perfluoroheptanoic acid (PFHpA) and perfluorooctane sulfonamide (FOSA). During the 5-year follow-up period, the frequency of RTIs increased with age, reaching a peak at age 4. Moreover, 20.6% of the children were diagnosed with recurrent RTIs. Children with recurrent RTIs had higher prenatal perfluorobutane sulfonic acid (PFBS) concentration. Higher prenatal PFBS concentration was positively associated with total RTI frequency (β = 6.05, 95% CI [0.84, 11.26]) in first 5 years of life and negatively associated with IgG level (β = -0.82, 95% CI [-1.67, -0.01]) at age 5.

CONCLUSIONS

Children with higher prenatal PFBS were more vulnerable to RTIs in early life, which may be attributed to immunosuppression of IgG production. These findings need to be further verified in larger prospective studies.

Risk to human health related to the presence of perfluoroalkyl substances in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluoroalkyl substances (PFASs) in food. Based on several similar effects in animals, toxicokinetics and observed concentrations in human blood, the CONTAM Panel decided to perform the assessment for the sum of four PFASs: PFOA, PFNA, PFHxS and PFOS. These made up half of the lower bound (LB) exposure to those PFASs with available occurrence data, the remaining contribution being primarily from PFASs with short half-lives. Equal potencies were assumed for the four PFASs included in the assessment. The mean LB exposure in adolescents and adult age groups ranged from 3 to 22, the 95th percentile from 9 to 70 ng/kg body weight (bw) per week. Toddlers and 'other children' showed a twofold higher exposure. Upper bound exposure was 4- to 49-fold higher than LB levels, but the latter were considered more reliable. 'Fish meat', 'Fruit and fruit products' and 'Eggs and egg products' contributed most to the exposure. Based on available studies in animals and humans, effects on the immune system were considered the most critical for the risk assessment. From a human study, a lowest BMDL 10 of 17.5 ng/mL for the sum of the four PFASs in serum was identified for 1-year-old children. Using PBPK modelling, this serum level of 17.5 ng/mL in children was estimated to correspond to long-term maternal exposure of 0.63 ng/kg bw per day. Since accumulation over time is important, a tolerable weekly intake (TWI) of 4.4 ng/kg bw per week was established. This TWI also protects against other potential adverse effects observed in humans. Based on the estimated LB exposure, but also reported serum levels, the CONTAM Panel concluded that parts of the European population exceed this TWI, which is of concern.

Association between prenatal exposure to perfluoroalkyl substances and asthma in 5-year-old children in the Odense Child Cohort

BACKGROUND

Asthma is the most common non-communicable disease in children. Prenatal exposure to perfluoroalkyl substances (PFASs), a group of persistent environmental chemicals with endocrine disrupting abilities, has been associated with immunomodulation and may contribute to the aetiology of asthma. We investigated the associations between prenatal exposure to five PFASs and asthma in 5-year-old children.

METHODS

We studied 981 mother-child pairs within the Odense Child Cohort (OCC), Denmark. We measured perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) in maternal serum donated in early pregnancy. A standardized questionnaire based on the International Study of Asthma and Allergies in Childhood (ISAAC) was used to assess wheeze, self-reported asthma and doctor-diagnosed asthma among children at age 5 years. Associations were examined using logistic regression analyses adjusting for parity, maternal educational level, maternal pre-pregnancy BMI, asthma predisposition and child sex.

RESULTS

Among the 5-year-old children 18.6% reported wheeze and 7.1% reported asthma. We found no association between prenatal exposure to PFAS and doctor-diagnosed asthma or wheeze. Prenatal PFAS exposure was associated with self-reported asthma, although only significant for PFNA (OR = 1.84, 95% CI 1.03,3.23).

CONCLUSION

Our findings support the suggested immunomodulatory effects of PFASs, however, additional studies are warranted. In order to verify our findings, it is important to re-examine the children with postnatal measurements of serum PFAS concentrations and additional clinical diagnostic testing at an older age where an asthma diagnosis is more valid.

Prenatal exposure to perfluoroalkyl substances, immune-related outcomes, and lung function in children from a Spanish birth cohort study

BACKGROUND

Prenatal exposure to perfluoroalkyl substances (PFASs) has been associated with impaired immune and respiratory health during childhood but the evidence is inconsistent and limited for lung function. We studied the association between prenatal PFASs exposure and immune and respiratory health, including lung function, up to age 7 years in the Spanish INMA birth cohort study.

METHODS

We assessed four PFASs in maternal plasma samples collected during the 1st trimester of pregnancy (years: 2003-2008): perfluorohexane sulfonate (PFHxS), perfluorooctane sulfonate (PFOS), perfluorooctanoate (PFOA), and perfluorononanoate (PFNA). Mothers reported the occurrence (yes/no) of lower respiratory tract infections, wheezing, asthma, and eczema in the previous 12 months at 1.5 and 4 years of the child (n = 1188) and at 7 years (n = 1071). At ages 4 (n = 503) and 7 (n = 992) years lung function was assessed using spirometry tests.

RESULTS

The most abundant PFASs were PFOS and PFOA (geometric means: 5.80 and 2.31 ng/mL, respectively). The relative risk of asthma during childhood per each doubling in PFNA concentration was 0.74 (95 CI%: 0.57, 0.96). The relative risk of eczema during childhood per every doubling in PFOS concentration was 0.86 (95 CI%: 0.75, 0.98). Higher PFOA concentrations were associated with lower forced vital capacity and lower forced expiratory volume in 1 s z-scores at 4 years [β (95 CI %): -0.17 (-0.34, -0.01) and -0.13 (-0.29, 0.03), respectively], but not at 7 years.

CONCLUSION

This longitudinal study suggests that different PFASs may affect the developing immune and respiratory systems differently. Prenatal exposure to PFNA and PFOS may be associated with reduced risk of respiratory and immune outcomes, particularly asthma and eczema whereas exposure to PFOA may be associated with reduced lung function in young children. These mixed results need to be replicated in follow-up studies at later ages.

Serum perfluoroalkyl substances and lung function in adolescents exposed to the World Trade Center disaster

The effects of childhood exposure to perfluoroalkyl substances (PFASs) on lung function remain mostly unknown. Previous research indicates that children living or going to school near the World Trade Center (WTC) disaster were exposed to high levels of PFASs, among other toxic chemicals. To explore the effects of PFAS exposure on lung function, we measured serum PFASs in a cohort of children from the WTC Health Registry and a matched control group. Perfluorooctanesulfonate had the highest median concentrations in both groups (WTCHR = 3.72 ng/mL, Comparison = 2.75 ng/mL), while the lowest median concentrations were seen for perfluoroundecanoic acid (WTCHR = 0.12 ng/mL, Comparison = 0.01 ng/mL). Lung function outcomes were measured by spirometry, plethysmography, and oscillometry. Asthma diagnosis and serum eosinophil count were also recorded. We examined the relationships of each PFAS with lung function parameters and eosinophil count using linear regressions. Odds ratios for asthma were obtained for each PFAS using logistic regression. The effect of total PFASs on these outcomes was also assessed. All regression models were adjusted for sex, race/ethnicity, age, body mass index (BMI) and tobacco smoke exposure. We found that serum PFASs were not statistically associated with the measured lung function parameters, asthma diagnosis, or eosinophil count in this cohort (p < 0.05). These findings highlight the need for more longitudinal studies to explore the long-term effects of childhood PFAS exposure on lung function past adolescence and early adulthood.

8:2 Fluorotelomer alcohol causes immunotoxicity and liver injury in adult male C57BL/6 mice

8:2 Fluorotelomer alcohol (8:2 FTOH) is widely used in houseware and industrial goods and is ubiquitous in the surrounding environment. 8:2 FTOH has been linked to hepatoxicity, nephrotoxicity, and reproductive toxicity, as well as endocrine-disrupting effects. However, as of yet, the research regarding immunotoxicity of 8:2 FTOH remains largely limited. In the present study, adult male C57BL/6 mice were administered with 10, 30, and 100 mg/kg/d 8:2 FTOH by gavage for 28 days to investigate its immunotoxicity in vivo. The results showed that exposure to 8:2 FTOH caused increases in liver weight and histological changes in the liver, including vacuolation, cell swelling, immune cell infiltration, karyopyknosis and nuclear swelling. No histological change in either the spleen or the thymus was observed after administration of 8:2 FTOH. In addition, exposure to 8:2 FTOH reduced the concentration of IL-1β in serum, and mRNA levels of IL-1β, IL-6, and TNF-α in both the thymus and spleen. CXCL-1 mRNA expression was downregulated in both the liver and thymus after 8:2 FTOH administration, while only IL-1β mRNA expression was upregulated in the liver. Moreover, the exposure of primary cultured splenocytes to 8:2 FTOH inhibited the ConA-stimulated proliferation of splenocytes at concentrations of 30 and 100 μM, and the LPS-stimulated proliferation of splenocytes at 100 μM. Furthermore, 8:2 FTOH inhibited the level of secreted IFN-γ in ConA-stimulated splenocytes. The results obtained in the study demonstrated that 8:2 FTOH posed potential immunotoxicity and liver injury in mice. Our findings will provide novel data for the health risk assessment of 8:2 FTOH.

Risk to human health related to the presence of perfluorooctane sulfonic acid and perfluorooctanoic acid in food

The European Commission asked EFSA for a scientific evaluation on the risks to human health related to the presence of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in food. Regarding PFOS and PFOA occurrence, the final data set available for dietary exposure assessment contained a total of 20,019 analytical results (PFOS n = 10,191 and PFOA n = 9,828). There were large differences between upper and lower bound exposure due to analytical methods with insufficient sensitivity. The CONTAM Panel considered the lower bound estimates to be closer to true exposure levels. Important contributors to the lower bound mean chronic exposure were 'Fish and other seafood', 'Meat and meat products' and 'Eggs and egg products', for PFOS, and 'Milk and dairy products', 'Drinking water' and 'Fish and other seafood' for PFOA. PFOS and PFOA are readily absorbed in the gastrointestinal tract, excreted in urine and faeces, and do not undergo metabolism. Estimated human half-lives for PFOS and PFOA are about 5 years and 2-4 years, respectively. The derivation of a health-based guidance value was based on human epidemiological studies. For PFOS, the increase in serum total cholesterol in adults, and the decrease in antibody response at vaccination in children were identified as the critical effects. For PFOA, the increase in serum total cholesterol was the critical effect. Also reduced birth weight (for both compounds) and increased prevalence of high serum levels of the liver enzyme alanine aminotransferase (ALT) (for PFOA) were considered. After benchmark modelling of serum levels of PFOS and PFOA, and estimating the corresponding daily intakes, the CONTAM Panel established a tolerable weekly intake (TWI) of 13 ng/kg body weight (bw) per week for PFOS and 6 ng/kg bw per week for PFOA. For both compounds, exposure of a considerable proportion of the population exceeds the proposed TWIs.

Bonding of Butylparaben, Bis(2-ethylhexyl)-phthalate, and Perfluorooctanesulfonic Acid to DNA: Comparison with Benzo[a]pyrene Shows Low Probability for Strong Noncovalent DNA Intercalation

Parabens, phthalates, and perfluorinated compounds are pollutant compounds used in cosmetics, plastics, and fire-fighting foams. All three compounds have been studied over several years for toxicity mechanism; however, a clear view of their ability to bind to DNA has not been supplied empirically. In this work, a simulation study is done to reveal the interaction of three of these pollutants, bis(2-ethylhexyl)-phthalate (DEHP), butylparaben (BPRB), and the protonated form of perfluorooctanesulfonic acid (PFOS(H)), with DNA. The results show that the DEHP, PFOS(H), and BPRB bind with a probability of 1/5 to DNA, with respective bonding energies -23.96 kJ/mol (PFOS(H)), -94.92 kJ/mol (BPRB), and -216.52 kJ/mol (DEHP). The positive control, benzo[a]pyrene diol epoxide (BAP), which is known for its notorious DNA intercalation, binds at a rate of 3/5 simulations, with bonding energies of -6544.52, -7034.66, and -7578.67 kJ/mol. The results are compared to empirical studies and conclusively show that all these pollutants can interfere with transcription and DNA related mechanisms by forming noncovalent interactions with DNA. The results show also that these pollutants are unlikely to undergo strong noncovalent intercalation to DNA, such as BAP, and do not possess the frontier orbital profiles to undergo adduct formation. After many years of research and several unanswered questions on the action of these pollutants on DNA, a calculation on their properties hence to the DNA confirms that there is a low probability for these to undergo a strong intercalation with DNA. Literature shows however that the pollutants are strongly interfering with the protein machinery and receptors on the cell surface and are therefore still priority pollutants for ecotoxicity research.

Perfluorooctane sulfonate affects intestinal immunity against bacterial infection

Perfluorooctane sulfonate (PFOS) is an environmental contaminant that has been manufactured to be used as surfactants and repellents in industry. Due to long half-life for clearance and degradation, PFOS is accumulative in human body and has potential threat to human health. Previous studies have shown the development and function of immune cells can be affected by PFOS. Although PFOS has a high chance of being absorbed through the oral route, whether and how PFOS affects immune cells in the gut is unknown. Using mouse model of Citrobacter rodentium infection, we investigated the role of PFOS on intestinal immunity. We found at early phase of the infection, PFOS inhibited the expansion of the pathogen by promoting IL-22 production from the group 3 innate lymphoid cell (ILC3) in an aryl hydrocarbon receptor dependent manner. Nevertheless, persistent PFOS treatment in mice finally led to a failure to clear the pathogen completely. At late phase of infection, enhanced bacterial counts in PFOS treated mice were accompanied by increased inflammatory cytokines, reduced mucin production and dysbiosis, featured by decreased level of Lactobacillus casei, Lactobacillus johnsonii and increased E. coli. Our study reveals a deleterious consequence in intestinal bacterial infection caused by PFOS accumulation.

Association of perfluoroalkyl substances exposure with impaired lung function in children

Previous studies have demonstrated associations between serum levels of perfluoroalkyl substances (PFASs) and asthma or asthma related-biomarkers. However, no studies have reported a possible relationship between PFASs exposure and lung function among children. The objective of the present study is to test the association between PFASs exposure and lung function in children from a high exposure area by using a cross-sectional case-control study, which included 132 asthmatic children and 168 non-asthmatic controls recruited from 2009 to 2010 in the Genetic and Biomarkers study for Childhood Asthma. Structured questionnaires were administered face-to-face. Lung function was measured by spirometry. Linear regression models were used to examine the influence of PFASs on lung function. The results showed that asthmatics in our study had significantly higher serum PFAS concentrations than healthy controls. Logistic regression models showed a positive association between PFASs and asthma, with adjusted odds ratios (ORs) ranging from 0.99 (95% confidence interval [CI]: 0.80-1.21) to 2.76 (95% CI: 1.82-4.17). Linear regression modeling showed serum PFASs levels were significantly negatively associated with three pulmonary function measurements (forced vital capacity: FVC; forced expiratory volume in 1s: FEV₁; forced expiratory flow 25-75%: FEF_25-75) among children with asthma, the adjusted coefficients between lung function and PFASs exposure ranged from -0.055 (95%CI: -0.100 to -0.010) for FVC and perfluorooctane sulfonate (PFOS) to -0.223 (95%CI: -0.400 to -0.045) for FEF_25-75 and perfluorooctanoic acid (PFOA). PFASs were not, however, significantly associated with pulmonary function among children without asthma. In conclusion, this study suggests that serum PFASs are associated with decreased lung function among children with asthma.

Environmental perfluorooctane sulfonate exposure drives T cell activation in bottlenose dolphins

Perfluoroalkyl acids (PFAAs) are highly stable compounds that have been associated with immunotoxicity in epidemiologic studies and experimental rodent models. Lengthy half-lives and resistance to environmental degradation result in bioaccumulation of PFAAs in humans and wildlife. Perfluorooctane sulfonate (PFOS), the most prevalent PFAA detected within the environment, is found at high levels in occupationally exposed humans. We have monitored the environmental exposure of dolphins in the Charleston, SC region for over 10 years and levels of PFAAs, and PFOS in particular, were significantly elevated. As dolphins may serve as large mammal sentinels to identify the impact of environmental chemical exposure on human disease, we sought to assess the effect of environmental PFAAs on the cellular immune system in highly exposed dolphins. Herein, we utilized a novel flow cytometry-based assay to examine T cell-specific responses to environmental PFAA exposure ex vivo and to exogenous PFOS exposure in vitro. Baseline PFOS concentrations were associated with significantly increased CD4⁺ and CD8⁺ T cell proliferation from a heterogeneous resident dolphin population. Further analysis demonstrated that in vitro exposure to environmentally relevant levels of PFOS promoted proinflammatory cytokine production and proliferation in a dose-dependent manner. Collectively, these findings indicate that PFOS is capable of inducing proinflammatory interferon-gamma, but not immunoregulatory interleukin-4 production in T cells, which may establish a state of chronic immune activation known to be associated with susceptibility to disease. These findings suggest that PFOS directly dysregulates the dolphin cellular immune system and has implications for health hazards. Copyright © 2017 John Wiley & Sons, Ltd.

Perfluorodecanoic acid stimulates NLRP3 inflammasome assembly in gastric cells

Perfluorodecanoic acid (PFDA), a perfluorinated carboxylic acid, presents in the environment and accumulates in human blood and organs, but its association with tumor promotion are not clear. Given that inflammation plays a significant role in the development of gastric malignancies, we evaluated the effects of PFDA on activation of the inflammasome and inflammation regulation in the gastric cell line AGS. When added to cell cultures, PFDA significantly stimulated IL-1β and IL18 secretion and their mRNA levels compared with control cells. By RT-PCR and western-blot we found that up-regulation of NLRP3 were associated with promotion of IL-1β and IL-18 production. Then expression variation of cIAP1/2, c-Rel and p52 were analyzed, the results demonstrated raised mRNA expression in all the tested genes concomitant with enhanced inflammasome activity after exposure to PFDA. Assays with cIAP2 siRNA and NFκB reporter provided additional evidence that these genes were involved in PFDA-induced inflammasome assembly. Furthermore, increased secretion of IL-1β and IL-18 were detected in stomach of PFDA-treated mice, disorganized alignment of epithelial cells and inflammatory cell infiltration were also observed in the stomach tissues upon PFDA treatment. This study reports for the first time that PFDA regulates inflammasome assembly in human cells and mice tissues.

Effects of prenatal exposure to perfluoroalkyl acids on prevalence ofallergic diseases among 4-year-old children

Perfluoroalkyl acids (PFAAs) are ubiquitous chemicals extremely resistant and widespread throughout the environment, frequently being detected in human blood samples. Animal studies have revealed that exposure to PFAAs results in immunotoxicity. However, the association between PFAAs, especially long-chain PFAAs, and allergies in humans is not well established. We examined whether prenatal exposure to PFAAs is associated with allergic diseases among 4-year-old children in a large-scale prospective birth cohort in Hokkaido, Japan. In total, 1558 mother-child pairs were included in this study and prenatal levels of eleven PFAAs were measured in maternal plasma samples obtained between 28 and 32weeks of pregnancy by using ultra-performance liquid chromatography-tandem mass spectrometry. Participant demographic and characteristic information were obtained from self-administered pre- and postnatal questionnaires and medical birth records. Infant allergies were assessed using the Japanese version of the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three questionnaire, which was administered 4years post-delivery. Symptoms included eczema, wheezing and rhinoconjunctivitis with a prevalence of 19.0%, 18.7%, and 5.4%, respectively. Associations of PFAA quartiles with allergic outcomes were examined using logistic models. Adjusted odds ratios (ORs) in the 4th quartile vs. 1st quartile (Q4 vs. Q1) for total allergic diseases (including at least one allergic outcome) significantly decreased for perfluorododecanoic acid (PFDoDa) (Q4 vs. Q1 OR: 0.621; 95% confidence interval (CI): 0.454, 0.847) and perfluorotridecanoic acid (PFTrDA) (Q4 vs. Q1 OR: 0.712; 95% CI: 0.524, 0.966) in all children. We obtained similar results when examining the association between PFAAs and eczema. The adjusted OR (Q4 vs. Q1) for wheezing in relation to higher maternal PFHxS levels was 0.728 (95% CI: 0.497, 1.06) in all children. In conclusion, prenatal exposure to long-chain PFAAs, such as PFDoDa and PFTrDA may have an immunosuppressive effect on allergic diseases in 4-year-old children.

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.

This can't be stressed enough: The contribution of select environmental toxicants to disruption of the stress circuitry and response

Integration of the hypothalamic-pituitary-adrenal (HPA) axis and the limbic system through glucocorticoid signaling is imperative in initiating and regulating a suitable stress response following real or perceived threats. Dysfunction of these circuits that results in a persistent or inhibited glucocorticoid secretion can severely affect processing of stressful experiences and lead to risk for developing further psychiatric pathology. Exposure to toxic chemicals found in our environment, including pesticides, metals, and industrial compounds, have been shown to have significant impact on neurological health and disease. Indeed, studies have begun to identify the HPA axis and limbic system as potential targets of many of these environmental chemicals, suggesting a possible environmental risk for damage to the stress circuit and response to stressful stimuli. This review will focus on our current understanding of the impact exposure to environmental toxicants, including bisphenol A and lead, has on the synaptic physiology of the HPA axis and limbic system and how this contributes to an alteration in behavior output. Further, this discussion will provide a starting point to continue to couple novel toxicological and neurological approaches to elaborate our understanding of the influence of environmental chemicals on the stress response and pathology.

In vivo immunotoxicity of perfluorooctane sulfonate in BALB/c mice: Identification of T-cell receptor and calcium-mediated signaling pathway disruption through gene expression profiling of the spleen

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant that is used worldwide and is continuously being detected in biota and the environment, thus presenting potential threats to the ecosystem and human health. Although PFOS is highly immunotoxic, its underlying molecular mechanisms remain largely unknown. The present study examined PFOS-induced immunotoxicity in the mouse spleen and explored its underlying mechanisms by gene expression profiling. Oral exposure of male BALB/c mice for three weeks followed by one-week recovery showed that a 10 mg/kg/day PFOS exposure damaged the splenic architecture, inhibited T-cell proliferation in response to mitogen, and increased the percentages of T helper (CD3(+)CD4(+)) and cytotoxic T (CD3(+)CD8(+)) cells, despite the decrease in the absolute number of these cells. A delayed type of PFOS immunotoxicity was observed, which mainly occurred during the recovery period. Global gene expression profiling of mouse spleens and QRT-PCR analyses suggest that PFOS inhibited the expression of genes involved in cell cycle regulation and NRF2-mediated oxidative stress response, and upregulated those in TCR signaling, calcium signaling, and p38/MAPK signaling pathways. Western blot analysis confirmed that the expressions of CAMK4, THEMIS, and CD3G, which were involved in the upregulated pathways, were induced upon PFOS exposure. Acute PFOS exposure modulated calcium homoeostasis in splenocytes. These results indicate that PFOS exposure can activate TCR signaling and calcium ion influx, which provides a clue for the potential mechanism of PFOS immunotoxicity. The altered signaling pathways by PFOS treatment as revealed in the present study might facilitate in better understanding PFOS immunotoxicity and explain the association between immune disease and PFOS exposure.

Perfluoroalkyl chemicals and asthma among children 12-19 years of age: NHANES (1999-2008)

BACKGROUND

Perfluoroalkyl chemicals (PFCs) are a family of commonly used industrial chemicals whose persistence and ubiquity in human blood samples has led to concern about possible toxicity. Several animal studies and one recent human study have suggested a link between exposure to PFCs and asthma, although few epidemiologic studies have been conducted.

OBJECTIVES

We investigated children's PFC serum concentrations and their associations with asthma-related outcomes.

METHODS

We evaluated the association between serum concentrations of eight PFCs, including perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS), with self-reported lifetime asthma, recent wheezing, and current asthma using data from participants 12-19 years of age from the 1999-2000 and 2003-2008 National Health and Nutrition Examination Surveys.

RESULTS

In multivariable-adjusted models, PFOA was associated with higher odds of ever having received a diagnosis of asthma [odds ratio (OR) = 1.18; 95% CI: 1.01, 1.39 for a doubling in PFOA], whereas for PFOS there were inverse relationships with both asthma and wheezing (OR = 0.88; 95% CI: 0.74, 1.04, and OR = 0.83; 95% CI: 0.67, 1.02, respectively). The associations were attenuated after accounting for sampling weights. No associations were seen between the other PFCs and any outcome.

CONCLUSIONS

This cross-sectional study provides some evidence for associations between exposure to PFCs and asthma-related outcomes in children. The evidence is inconsistent, however, and prospective studies are needed.

Perfluorooctane sulfonate effects on the reproductive axis in adult male rats

Perfluorooctane sulfonate (PFOS) is a neurotoxic agent and it can disrupt the endocrine system activity. This work was undertaken to evaluate the possible effects of PFOS exposure on the hypothalamic-pituitary-testicular axis (HPT) in adult male rats, and to evaluate the possible morphological alterations induced by PFOS in the endocrine tissues of this axis. Adult male rats were orally treated with 0.5; 1.0; 3.0 and 6.0 mg of PFOS/kg/day for 28 days. After PFOS exposure, hypothalamic noradrenaline concentration increased in the anterior hypothalamus and in the median eminence, not changing in the mediobasal hypothalamus. PFOS treated rats presented a decrease of the gonadotropin releasing hormone (GnRH) gene expression, increasing the mRNA levels of the luteinizing hormone (LH) in rats treated with all doses administered except with the dose of 6 mg/kg/day. PFOS also induced a raise of the follicle stimulating hormone (FSH) gene expression in the animals exposed to 0.5 and 1.0 mg of PFOS/kg/day. After PFOS exposure, hypothalamic GnRH concentration was modified, LH and testosterone release was inhibited and FSH secretion was stimulated. Moreover, PFOS induced several histopathological alterations in the hypothalamus, pituitary gland and testis. The results obtained in the present study suggest in general terms that PFOS can inhibit the physiological activity of the reproductive axis in adult male rats, which could be explained, at least in part, by the structural alterations showed in the animals exposed to this chemical: very dense chromatin, condensed ribosomes and a loss of the morphology in the hypothalamus; a degeneration of the gonadotrophic cells, as well as a loss and degeneration of the spermatozoids and a very marked edema in the testis.

In vitro evaluation of the effects of perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) on IL-2 production in human T-cells

Perfluorinated compounds, such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been shown to alter various immune functions suggesting they are immunotoxic. This study assessed the effects of PFOS and PFOA on interleukin (IL)-2 production in the human Jurkat T-cell line and PFOS in healthy human primary T cells. Jurkat cells were stimulated with phytohemagglutinin (PHA)/phorbol myristate acetate (PMA), anti CD-3/anti CD-28, or anti CD-3, and dosed with 0, 0.05, 0.1, 0.5, 1, 5, 10, 50, 75, or 100 µg ml(-1) PFOS or 0, 0.005, 0.01, 0.05, 0.1, 0.5, 1, 5, or 10 µg ml(-1) PFOA. Jurkat cells stimulated with PHA/PMA or anti CD-3 exhibited decreased IL-2 production beginning at 50 µg PFOS ml(-1) and 5 µg PFOS ml(-1) respectively, but stimulation with anti-CD3/anti-CD28 resulted in no changes compared with the control. Addition of the PPAR-alpha antagonist GW6471 to PFOS-dosed cells stimulated with PHA/PMA resulted in decreases in IL-2 production starting at 50 µg PFOS ml(-1), which suggests PFOS affected T-cell IL-2 production via PPAR-alpha-independent mechanisms. Exposure to PFOA, PFOA + GW6471, or PFOS + PFOA in Jurkat cells resulted in no significant differences in IL-2 production. In vitro dosing studies using healthy primary human CD4+ T cells were consistent with the Jurkat results. These data demonstrated that PFOA did not impact IL-2 production, but PFOS suppressed IL-2 production in both a human cell line and human primary cells at dose levels within the high end of the human exposure range. A decrease in IL-2 production is characteristic of autoimmune diseases such as systemic lupus erythematosus and should be further investigated.

Perfluorinated compounds: emerging POPs with potential immunotoxicity

Perfluorinated compounds (PFCs) have been recognized as an important class of environmental contaminants commonly detected in blood samples of both wildlife and humans. These compounds have been in use for more than 60 years as surface treatment chemicals, polymerization aids, and surfactants. They possess a strong carbon-fluorine bond, which leads to their environmental persistence. There is evidence from both epidemiology and laboratory studies that PFCs may be immunotoxic, affecting both cell-mediated and humoral immunity. Reported effects of PFCs include decreased spleen and thymus weights and cellularity, reduced specific antibody production, reduced survival after influenza infection, and altered cytokine production. Immunosuppression is a critical effect associated with exposure to PFCs, as it has been reported to reduce antibody responses to vaccination in children. Mounting evidence suggests that immunotoxicity in experimental animals can occur at serum concentrations below, within, or just above the reported range for highly exposed humans and wildlife. Considering bioaccumulation and exposure to multiple PFCs, the risk of immunotoxicity for humans and wildlife cannot be discounted. This review will discuss current and recently published work exploring the immunomodulatory effects of PFCs in experimental animals and humans.

Regulation of corticosterone secretion is modified by PFOS exposure at different levels of the hypothalamic-pituitary-adrenal axis in adult male rats

Perfluorooctane sulfonate (PFOS) is a fluorinated compound and a Persistent Organic Pollutant which can disrupt the endocrine system. This work was undertaken to evaluate the possible effects of PFOS exposure on the regulation of corticosterone secretion in adrenal and pituitary glands and at hypothalamic level in adult male rat, and to evaluate the possible morphological alterations induced by PFOS in this endocrine tissue. Adult male rats were orally treated with 0.5, 1.0, 3.0 and 6.0 mg of PFOS/kg/day for 28 days. Corticosterone, adrenocorticotropic hormone (ACTH) and corticotrophin-releasing hormone (CRH) secretion decreased in PFOS-treated rats. After PFOS exposure, relative expression of adrenocorticotropic hormone receptor (ACTHr) and proopiomelanocortin (POMC) genes was increased in adrenal and in pituitary glands, respectively; while relative expression of ACTHr and CRH genes decreased in hypothalamus with the doses of 0.5 and 1.0 mg/kg/day. PFOS treatment increased relative nitric oxide synthase 1 and 2 (NOS1 and NOS2) gene expression in the adrenal gland, and incremented superoxide dismutase activity. PFOS exposure induces a global inhibition of the hypothalamic-pituitary-adrenal (HPA) axis activity, and small morphological changes were observed in adrenal zona fasciculata cells.

Allergic diseases and air pollution

The prevalence of allergic diseases has been increasing rapidly, especially in developing countries. Various adverse health outcomes such as allergic disease can be attributed to rapidly increasing air pollution levels. Rapid urbanization and increased energy consumption worldwide have exposed the human body to not only increased quantities of ambient air pollution, but also a greater variety of pollutants. Many studies clearly demonstrate that air pollutants potently trigger asthma exacerbation. Evidence that transportation-related pollutants contribute to the development of allergies is also emerging. Moreover, exposure to particulate matter, ozone, and nitrogen dioxide contributes to the increased susceptibility to respiratory infections. This article focuses on the current understanding of the detrimental effects of air pollutants on allergic disease including exacerbation to the development of asthma, allergic rhinitis, and eczema as well as epigenetic regulation.

A DNA prime-protein boost vaccination strategy targeting turkey coronavirus spike protein fragment containing neutralizing epitope against infectious challenge

The present study was undertaken to determine immune response and protection efficacy of a spike (S) protein fragment containing neutralizing epitopes (4F/4R) of turkey coronavirus (TCoV) by priming with DNA vaccine and boosting with the recombinant protein from the corresponding DNA vaccine gene segment. Turkeys were vaccinated by priming with either one dose (G1-750DP) or two doses (G3-750DDP) of 750 μg DNA vaccine expressing 4F/4R S fragment and boosting with one dose of 200 μg 4F/4R S fragment. One dose of 100 μg DNA vaccine mixed with polyethyleneimine (PEI) and sodium hyaluronate (HA) followed by one dose of 750 μg DNA vaccine and one dose of 200 μg 4F/4R S fragment were given to the turkeys in group G2-100DPH. After infectious challenge by TCoV, clinical signs and TCoV detected by immunofluorescence antibody (IFA) assay were observed in less number of turkeys in vaccination groups than that in challenge control groups. TCoV viral RNA loads measured by quantitative real-time reverse transcription-PCR were lower in vaccinated turkeys than those in challenge control turkeys. The turkeys in G3-750DDP produced the highest level of TCoV S protein-specific antibody and virus neutralization (VN) titer. Comparing to the turkeys in G1-750DP, significantly less TCoV were detected by IFA in the turkeys in G2-100DPH receiving an extra dose of 100 μg DNA mixed with PEI and HA. The results indicated that DNA-prime protein-boost DNA vaccination regimen targeting TCoV S fragment encompassing neutralizing epitopes induced humoral immune response and partially protected turkeys against infectious challenge by TCoV.

The epigenetic lorax: gene-environment interactions in human health

Over the last decade, we have witnessed an explosion of information on genetic factors underlying common human diseases and disorders. This 'human genomics' information revolution has occurred as a backdrop to a rapid increase in the rates of many human disorders and diseases. For example, obesity, Type 2 diabetes, asthma, autism spectrum disorder and attention deficit hyperactivity disorder have increased at rates that cannot be due to changes in the genetic structure of the population, and are difficult to ascribe to changes in diagnostic criteria or ascertainment. A likely cause of the increased incidence of these disorders is increased exposure to environmental factors that modify gene function. Many environmental factors that have epidemiological association with common human disorders are likely to exert their effects through epigenetic alterations. This general mechanism of gene-environment interaction poses special challenges for individuals, educators, scientists and public policy makers in defining, monitoring and mitigating exposures.

Differential inflammatory responses triggered by toxic small molecules

PURPOSE

The aim of this study is to determine whether exposure to hazardous chemicals alters chemokine or cytokine production in macrophages and link these events to changes in intracellular signaling pathways and activation of specific gene promoters.

METHODS

RAW 264.7 mouse macrophages were treated with selected toxic industrial chemicals (TICs) and examined for changes in immune function. Luminex multiplex technology was used to assess changes in cytokine/chemokine expression and activation of kinase signaling pathways. In addition, a panel of macrophage cell lines with promoter-specific luciferase reporter genes were generated and treated with the TICs, and transcriptional responses to these chemicals were detected by changes in luminescence.

RESULTS

Changes in expression of cytokines and chemokines were linked to changes in the activation state of intracellular signaling pathways. Overall, the findings reveal that sublytic levels of TICs can alter the profile of cytokines and chemokines expressed by macrophages, with a pattern that suggests immunosuppression. The data demonstrate that critical changes in immune function correlate with activation of kinase signaling pathways in macrophages.

CONCLUSIONS

These data provide insight into the effects of sublytic doses of selected TICs on macrophage function, with a particular emphasis on identifying changes in expression of cytokines and chemokines. These altered patterns in immune function were linked to changes in the activation state of intracellular signaling pathways. The data strongly suggest that small amounts of TICs can have subtle, yet very critical, effects on macrophages.