Functional disorder of primary immunity responding to respiratory syncytial virus infection in offspring mice exposed to a flame retardant, decabrominated diphenyl ether, perinatally

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

Tetrabromobisphenol A effects on differentiating mouse embryonic stem cells reveals unexpected impact on immune system

Tetrabromobisphenol A (TBBPA) is a potent flame retardant used in numerous appliances and a major pollutant in households and ecosystems. In vertebrates, it was shown to affect neurodevelopment, the hypothalamic-pituitary-gonadal axis and thyroid signaling, but its toxicity and modes of actions are still a matter of debate. The molecular phenotype resulting from exposure to TBBPA is only poorly described, especially at the level of transcriptome reprogramming, which further limits our understanding of its molecular toxicity. In this work, we combined functional genomics and system biology to provide a system-wide description of the transcriptomic alterations induced by TBBPA acting on differentiating mESCs, and provide potential new toxicity markers. We found that TBBPA-induced transcriptome reprogramming affect a large collection of genes loosely connected within the network of biological pathways, indicating widespread interferences on biological processes. We also found two hotspots of action: at the level of neuronal differentiation markers, and surprisingly, at the level of immune system functions, which has been largely overlooked until now. This effect is particularly strong, as terminal differentiation markers of both myeloid and lymphoid lineages are strongly reduced: the membrane T cell receptor (Cd79a, Cd79b), interleukin seven receptor (Il7r), macrophages cytokine receptor (Csf1r), monocyte chemokine receptor (Ccr2). Also, the high affinity IgE receptor (Fcer1g), a key mediator of allergic reactions, is strongly induced. Thus, the molecular imbalance induce by TBBPA may be stronger than initially realized.

Delineation of 3D dose-time-toxicity in human pulmonary epithelial Beas-2B cells induced by decabromodiphenyl ether (BDE209)

Due to frequent detection in environment as well as in the human body, the adverse effects of decabromodiphenyl ether (BDE209) have been extensively studied in the past few years. However, information regarding the inhalation toxicity of BDE209 to humans is currently limited. In this study, the cytotoxicity, cell damage, and inflammation markers including IL-6, IL-8, and TNF-α in the Beas-2B cell line induced by BDE209 were measured using a central composite design. Results showed that as BDE209 concentrations (5-65 μg mL^-1) and exposure time (6-30 h) were increased, cell viability sharply decreased from 99.7% to 29.7% and LDH activity increased from 0.1% to 13.1%. Furthermore, expression of IL-6, IL-8 and TNF-α transcripts were enhanced from 4.7 to 29.1 fold, 3.4-68.9 fold, and 2.8-47.0 fold, respectively, and the concentration of IL-6 and IL-8 proteins increased from 5.4 to 16.7 pg mL^-1 and 71.0-550.0 pg mL^-1, respectively. Results indicate that BDE209 exposure can inhibit cell viability, increase LDH leakage, and upregulate the transcript (mRNA) and protein levels of inflammatory markers of IL-6 and IL-8 in Beas-2B cells. Moreover, these effects were both dose- and time-dependent, and dose and time had a synergistic effect - enhancing toxicity when in combination. Cell density affected both LDH activity and IL-8 release but had little effect on cell activity and IL-6 release in the Beas-2B cells. In contrast, TNF-α protein was not detected but its mRNA expression level was upregulated. This study will provide a reference for human health risk assessment, especially for the toxic damage that BDE209 exposure can elicit in the respiratory tract.

Titanium dioxide nanoparticles exacerbate pneumonia in respiratory syncytial virus (RSV)-infected mice

To reveal the effects of TiO2 nanoparticles, used in cosmetics and building materials, on the immune response, a respiratory syncytial virus (RSV) infection mouse model was used. BALB/c mice were exposed once intranasally to TiO2 at 0.5mg/kg and infected intranasally with RSV five days later. The levels of IFN-γ and chemokine CCL5, representative markers of pneumonia, in the bronchoalveolar lavage fluids of RSV-infected mice had increased significantly in TiO2-exposed mice compared with the control on day 5 post-infection, but not in uninfected mice. While pulmonary viral titers were not affected by TiO2 exposure, an increase in the infiltration of lymphocytes into the alveolar septa in lung tissues was observed. Immunohistochemical analysis revealed aggregation of TiO2 nanoparticles near inflammatory cells in the severely affected region. Thus, a single exposure to TiO2 nanoparticles affected the immune system and exacerbated pneumonia in RSV-infected mice.

Perinatal exposure to insecticide methamidophos suppressed production of proinflammatory cytokines responding to virus infection in lung tissues in mice

Methamidophos, a representative organophosphate insecticide, is regulated because of its severe neurotoxicity, but it is suspected of contaminating agricultural foods in many countries due to illicit use. To reveal unknown effects of methamidophos on human health, we evaluated the developmental immunotoxicity of methamidophos using a respiratory syncytial virus (RSV) infection mouse model. Pregnant mice were exposed to methamidophos (10 or 20 ppm) in their drinking water from gestation day 10 to weaning on postnatal day 21. Offsprings born to these dams were intranasally infected with RSV. The levels of interleukin-6 (IL-6) and interferon-gamma in the bronchoalveolar lavage fluids after infection were significantly decreased in offspring mice exposed to methamidophos. Treatment with methamidophos did not affect the pulmonary viral titers but suppressed moderately the inflammation of lung tissues of RSV-infected offspring, histopathologically. DNA microarray analysis revealed that gene expression of the cytokines in the lungs of offspring mice exposed to 20 ppm of methamidophos was apparently suppressed compared with the control. Methamidophos did not suppress IL-6 production in RSV-infected J774.1 cell cultures. Thus, exposure of the mother to methamidophos during pregnancy and nursing was suggested to cause an irregular immune response in the lung tissues in the offspring mice.

Effect of brazilian propolis on exacerbation of respiratory syncytial virus infection in mice exposed to tetrabromobisphenol a, a brominated flame retardant

Tetrabromobisphenol A (TBBPA), a brominated flame retardant, has been found to exacerbate pneumonia in respiratory syncytial virus- (RSV-) infected mice. We examined the effect of Brazilian propolis (AF-08) on the exacerbation of RSV infection by TBBPA exposure in mice. Mice were fed a powdered diet mixed with 1% TBBPA alone, 0.02% AF-08 alone, or 1% TBBPA and 0.02% AF-08 for four weeks and then intranasally infected with RSV. TBBPA exposure increased the pulmonary virus titer and level of IFN-γ, a representative marker of pneumonia due to RSV infection, in the lungs of infected mice without toxicity. AF-08 was significantly effective in reducing the virus titers and IFN-γ level increased by TBBPA exposure. Also, AF-08 significantly reduced proinflammatory cytokine (TNF-α and IL-6) levels in the lungs of RSV-infected mice with TBBPA exposure, but Th2 cytokine (IL-4 and IL-10) levels were not evidently increased. Neither TBBPA exposure nor AF-08 treatment affected the anti-RSV antibody production in RSV-infected mice. In flow cytometry analysis, AF-08 seemed to be effective in reducing the ratio of pulmonary CD8a⁺ cells in RSV-infected mice with TBBPA exposure. TBBPA and AF-08 did not exhibit anti-RSV activity in vitro. Thus, AF-08 probably ameliorated pneumonia exacerbated by TBBPA exposure in RSV-infected mice by limiting excess cellular immune responses.

Effects of oral administration of probiotics from Mongolian dairy products on the Th1 immune response in mice

We investigated 10 lactic acid bacteria strains with probiotic potential prepared from Mongolian dairy products for their ability to induce T helper type-1 (Th1) cytokine production in mouse immune cells in vitro and in vivo. Among these strains, the Lactobacillus plantarum 06CC2 strain was effective in elevating the level of interleukin (IL)-12p40 in co-culture with J774.1 cells and the levels of IL-12 and interferon (IFN)-γ in co-culture with mouse spleen cells in vitro. Oral administration of this strain augmented the gene expression of IFN-γ and IL-12p40 and enlarged the population of CD4(+), CD25(+), and CD49b(+) cells in the spleens of normal mice. It also significantly elevated the gene expression of IL-12 receptor β2 as well as IL-12p40 and IFN-γ in Peyer's patches. Thus oral administration of strain 06CC2 was effective in inducing Th1 cytokine production activating the Th1 immune response associated with intestinal immunity in normal mice.

Cytokine dysregulation in autism spectrum disorders (ASD): possible role of the environment

Autism spectrum disorders (ASD) are neurodevelopmental diseases that affect an alarming number of individuals. The etiological basis of ASD is unclear, and evidence suggests it involves both genetic and environmental factors. There are many reports of cytokine imbalances in ASD. These imbalances could have a pathogenic role, or they may be markers of underlying genetic and environmental influences. Cytokines act primarily as mediators of immunological activity but they also have significant interactions with the nervous system. They participate in normal neural development and function, and inappropriate activity can have a variety of neurological implications. It is therefore possible that cytokine dysregulation contributes directly to neural dysfunction in ASD. Further, cytokine profiles change dramatically in the face of infection, disease, and toxic exposures. Imbalances in cytokines may represent an immune response to environmental contributors to ASD. The following review is presented in two main parts. First, we discuss select cytokines implicated in ASD, including IL-1Β, IL-6, IL-4, IFN-γ, and TGF-Β, and focus on their role in the nervous system. Second, we explore several neurotoxic environmental factors that may be involved in the disorders, and focus on their immunological impacts. This review represents an emerging model that recognizes the importance of both genetic and environmental factors in ASD etiology. We propose that the immune system provides critical clues regarding the nature of the gene by environment interactions that underlie ASD pathophysiology.

Immune function in female B(6)C(3)F(1) mice is modulated by DE-71, a commercial polybrominated diphenyl ether mixture

Polybrominated diphenyl ethers (PBDEs) are an important class of flame-retardants that are environmentally persistent and bioaccumulative. Toxicity of these compounds has become a concern because detectable levels of PBDEs are present in humans and wildlife and they are structurally similar to polychlorinated biphenyls (PCBs). This study examined the effects of the commercial penta-BDE mixture, DE-71, in adult female B(6)C(3)F(1) mice on hematology, serum clinical chemistry, thyroid hormones, tissue histology, and several immunotoxicity end-points (lymphocyte proliferation, NK cell activity, splenic immunophenotypes, and SRBC-specific-IgM production). Mice were exposed via oral gavage for 28 days to achieve total administered doses (TAD) of 0, 0.5, 5, 50, or 100 mg/kg. No changes in histology, clinical chemistry, body or organ weights were observed. Serum total T3 and T4 levels were not altered by any of the DE-71 treatments. Peripheral blood monocyte numbers were decreased by the 0.5, 5, and 50 mg/kg treatments, but not by the 100 mg/kg TAD concentration. Compared to controls, mitogen-stimulated T- and B-cell proliferation was increased by the 100 mg/kg TAD concentration (ED(50) = 60 mg/kg TAD [2.14 mg/kg/day] and 58 mg/kg TAD [2.57 mg/kg/day], respectively). NK cell activity was decreased compared to controls by the 100 mg/kg TAD concentration (ED(50) = 20 mg/kg TAD [0.7 mg/kg/day]). No alterations were noted in thymic T-cell populations or in SRBC-specific-IgM production. Numbers of CD19(+)CD21(-), CD19(+)CD21(+), CD4(+)CD8(-), CD4(-)CD8(+), CD4(-)CD8(-), and MHC-II(+) cells in the spleen were not affected. However, the numbers of splenic CD4(+)CD8(+) cells were decreased compared to the controls by 0.5, 5, and 100 mg/kg TAD. This study provides an assessment of the systemic toxicity and immunotoxicity of DE-71, and indicates that immune parameters are modulated at exposure concentrations lower than previously reported.

Efficacy of oral administration of heat-killed probiotics from Mongolian dairy products against influenza infection in mice: alleviation of influenza infection by its immunomodulatory activity through intestinal immunity

Some probiotics possess immunomodulatory activities and have been used as complementary and alternative medicines. We previously found that 10 lactic acid bacteria (LAB) strains isolated from traditional Mongolian dairy products showed probiotic potential in vitro. In this study, we assessed the immunomodulatory activity of 10 LABs on influenza virus (IFV) infection in relation to their efficacies in IFV-infected mice. In an intranasal IFV infection model in mice, oral administration of boiled Lactobacillus plantarum 06CC2 strain (20mg/mouse), one of the 10 LABs, twice daily for 10 days starting two days before infection was significantly effective in protecting the body weight loss of infected mice, reducing virus yields in the lungs on days 2, 4, and 6 after infection, and prolonging survival times without toxicity. The total numbers of infiltrated cells in the bronchoalveolar lavage fluid (BALF), especially macrophages and neutrophils, were significantly reduced by 06CC2 administration on day 2. On day 2, tumor necrosis factor (TNF)-α production in BALF was also reduced significantly, but interferon-α, interleukin-12, and interferon-γ productions were augmented and natural killer (NK) cell activity was significantly elevated. Furthermore, the gene expressions of interleukin-12 receptor and interferon-γ in Peyer's patches were augmented by 06CC2 administration on day 2. Thus, 06CC2 was suggested to alleviate influenza symptoms in mice in correlation with the augmentation of NK cell activity associated with the enhancement of interferon-α and Th1 cytokine productions through intestinal immunity and the reduction of TNF-α in the early stage of infection.