Journal of Immunotoxicology最新文献

The immunotoxicant bisphenol A (BPA) may produce toxic effects on organs and systems, in part, by altering the secretion of cytokines and chemokines. However, systematic studies of the effects of BPA, let alone of its analogs and in cases when there are interactions with other chemicals, on innate immunity and cytokine modulation are limited. The objectives of this study were to investigate the immunomodulatory effects of: (1) BPA and its analogs, BPS and BPAF; and (2) the interaction between BPA and genistein (GEN), a partial estrogen agonist or antagonist. BPA, BPS, and BPAF were incubated with PMA-differentiated-U937 cells (a widely used cell line for primary human macrophages) at concentrations of 0, 0.1, 1, 10, 100 µM for up to 96 h. BPA (0, 0.1, 1, 10 µM) and GEN (0, 1, 10 µM) were also applied at various combinations. Cell viability and 30 cytokines/chemokines were measured. The results showed that the cell viability-inhibiting effect of these three bisphenols was BPAF > BPA > BPS. At 0.1 µM, BPA and BPAF generally increased the secretion of cytokines/chemokines, while BPS had minimal effects. All three bisphenols generally suppressed the secretion of cytokines/chemokines at 1 µM, while increased their secretion at 10 µM. The most increased cytokines/chemokines were interferon (IFN)-γ, interleukin (IL)-1RA, IL-8 and MIP-1β, and the most decreased was IL-10. GEN increased cell viability at low BPA concentrations but had no effect when BPA levels were high. In general, GEN attenuated the BPA-induced secretion of cytokines/chemokines but enhanced it at low BPA concentrations. In conclusion, this study showed that BPA, BPS, and BPAF were immunotoxic to macrophages: BPS was the least toxic, while BPAF was the most toxic. Further, GEN reversed suppressive effects on macrophages that resulted from exposure to high concentrations of BPA and produced synergetic effects with BPA at low concentrations.

Benzo[a]pyrene (BaP) can induce developmental and reproductive toxicity; however, the full scope of its immunotoxic effects remains unknown. This study aimed to assess effects of lactational exposure to low-dose BaP (comparable to human exposure) on potential allergicnon-allergic immune responses in murine offspring. Lactating C3H/HeJ dams were orally dosed with BaP at 0, 0.25, 5.0, or 100 pmol/animal/week) at post-natal days [PND] 1, 8, and 15. Five-weeks-old pups then received intratracheally ovalbumin (OVA) every 2 weeks for 6 weeks. Following the final exposure, mice were processed to permit analyses of bronchoalveolar lavage (BAL) fluid cell profiles as well as levels of lung inflammatory cytokines and chemokines, serum OVA-specific immunoglobulin, and mediastinal lymph node (MLN) cell activation/proliferation. In OVA-sensitized male offspring, lactational low-dose BaP exposure led to enhanced (albeit not significantly) macrophage, neutrophil, and eosinophil infiltration to, and increased T-helper (T_H)-2 cytokine production in, the lungs. In females, BaP exposure, regardless of dose, led to slightly enhanced lung levels of macrophages and eosinophils, and of inflammatory molecules. Protein levels of interleukin (IL)-33 in the OVA + BaP (middle dose) group, and interferon (IFN)-γ in the OVA + BaP (low dose) group, were higher than that of the OVA (no BaP) group. Ex vivo studies showed lactational exposure to BaP partially induced activation of T-cells and antigen-presenting cells (APCs) in the MLN cells of both male and female offspring, with or without OVA sensitization. Further, IL-4 and IFNγ levels in MLN culture supernatants were elevated even without OVA-re-stimulation in OVA + BaP groups. In conclusion, lactational exposure to low-dose BaP appeared to exert slight effects on later allergic and non-allergic immune responses in offspring by facilitating development of modest T_H2 responses and activating MLN cells. In addition, lactational exposures to BaP might give rise to gender differences in allergic/non-allergic immune responses of offspring.

Poly- and perfluoroalkyl substances (PFAS) are chemically and thermally stable, hydrophobic, lipophobic compounds used in stain repellants and water and oil surfactants, and associated with immunosuppression and peroxisome proliferator activity. Perfluoro-n-decanoic acid (PFDA, (CF₃(CF₂)₈COOH), a fluorinated straight chain fatty acid compound, is reported to induce thymic atrophy and reversible bone marrow hypocellularity in rodent models. The objective of this study was to assess potential immunotoxicity of PFDA, due to its structural similarity to other immunosuppressive PFASs. Female Harlan Sprague-Dawley rats were exposed to 0-2.0 mg PFDA/kg by oral gavage daily for 28 d. Female B₆C₃F₁/N mice were exposed once/week to 0-5.0 mg PFDA/kg by gavage for 4 weeks. Animals were evaluated for effects on immune cell populations in spleen and bone marrow, and innate, humoral-, and cell-mediated immunity. Mice were also evaluated for resistance to Influenza virus. Treatment-related hepatocyte necrosis and hepatomegaly were observed in rats treated with 0.5 mg PFDA/kg/d. In mice, hepatomegaly (26-89%) was observed following exposure to ≥0.625 mg PFDA/kg/week, while splenic atrophy (20%) was observed at 5.0 mg PFDA/kg/week. At 5.0 mg PFDA/kg/week, total spleen cells, and Ig + and NK + cells were decreased (17.6-27%). At ≥ 1.25 mg PFDA/kg/week the numbers of splenic CD3⁺, CD4⁺, CD8⁺, and Mac3⁺ cells were decreased (10.5-39%). No changes were observed in leukocyte subpopulations in PFDA-exposed rats. Phagocytosis by fixed-tissue macrophages was decreased in liver (specific activity, 24-39%) at ≥0.25 mg PFDA/kg/d in rats. PFDA-induced effects on humoral- and cell-mediated immunity, host resistance, and bone marrow progenitor cells were limited. These data suggest that exposure to PFDA may induce adverse effects in rat liver in a manner consistent with the PFAS class, and may also alter the balance of immune cell populations in lymphoid tissues in mice.

With the rapid development of synthetic alternatives to mineral fibers, their possible effects on the environment and human health have become recognized as important issues worldwide. This study investigated effects of four fibrous materials, i.e. nanofibrillar/nanocrystalline celluloses (NCF and CNC), single-walled carbon nanotubes (CNTs), and crocidolite asbestos (ASB), on pulmonary inflammation and immune responses found in the lungs, as well as the effects on spleen and peripheral blood immune cell subsets. BALB/c mice were given NCF, CNC, CNT, and ASB on Day 1 by oropharyngeal aspiration. At 14 days post-exposure, the animals were evaluated. Total cell number, mononuclear phagocytes, polymorphonuclear leukocytes, lymphocytes, and LDH levels were significantly increased in ASB and CNT-exposed mice. Expression of cytokines and chemokines in bronchoalveolar lavage (BAL) was quite different in mice exposed to four particle types, as well as expression of antigen presentation-related surface proteins on BAL cells. The results revealed that pulmonary exposure to fibrous materials led to discrete local immune cell polarization patterns with a T_H2-like response caused by ASB and T_H1-like immune reaction to NCF, while CNT and CNC caused non-classical or non-uniform responses. These alterations in immune response following pulmonary exposure should be taken into account when testing the applicability of new nanosized materials with fibrous morphology.

Trichloroethylene (TCE) is known to induce skin disorders and multi-system dysfunction, but the mechanism of this multi-organ injury is not entirely clear. It was shown in a previous study that levels of pivotal end-products of the kallikrein-kinin system (KKS), i.e. bradykinin (BK) and BK receptors B1R/B2R, in the kidneys were increased by TCE exposure. Unfortunately, how BK and its receptors acted in the etiology of the induced renal injury is not clear. Thus, this study explored any correlation between BK receptors and immune renal injury in TCE-sensitized mice by blocking the BK receptors B1R/B2R. BALB/c mice were sensitized (via skin) by TCE, with or without pre-treatment with a B1R or B2R antagonist. Renal lesions, increased expressions of B1R, B2R, Kim-1, Lipocalin-2, and NF-κB p65 subunit on tubular epithelial cells were all observed in TCE-sensitized mice. Serum levels of creatinine (Cr), microglobulin α1 and β2, along with mRNA levels for inflammatory cytokines and NF- κB p65 in kidneys, were all increased by 72 h after a final challenge. Highly selective antagonist pre-treatment blocked B2R and significantly attenuated TCE-induced changes. Blocking B1R or B2R attenuated release of pro-inflammatory cytokines and activation of NF-κB signaling pathway (as reflected in lower up-regulation of pIκB and nuclear NF-κB p65 subunit, and down-regulation of IκB in the kidneys. These results provided evidence that TCE-sensitization caused KKS activation and enhanced the expression of B1R and B2R on tubular epithelial cells. This, in turn, accelerated NF-κB signaling pathway activation and amplified inflammatory cytokine release, which all likely contributed to TCE-induced immune renal injury.

Skeletal health consequences associated with inflammatory diseases of the airways significantly contribute to morbidity. Sex differences have been described independently for lung and bone diseases. Repetitive inhalant exposure to lipopolysaccharide (LPS) induces bone loss and deterioration in male mice, but comparison effects in females are unknown. Using an intranasal inhalation exposure model, 8-week-old C57BL/6 male and female mice were treated daily with LPS (100 ng) or saline for 3 weeks. Bronchoalveolar lavage fluids, lung tissues, tibias, bone marrow cells, and blood were collected. LPS-induced airway neutrophil influx, interleukin (IL)-6 and neutrophil chemoattractant levels, and bronchiolar inflammation were exaggerated in male animals as compared to female mice. Trabecular bone micro-CT imaging and analysis of the proximal tibia were conducted. Inhalant LPS exposures lead to deterioration of bone quality only in male mice (not females) marked by decreased bone mineral density, bone volume/tissue volume ratio, trabecular thickness and number, and increased bone surface-to-bone volume ratio. Serum pentraxin-2 levels were modulated by sex differences and LPS exposure. In proof-of-concept studies, ovarectomized female mice demonstrated LPS-induced bone deterioration, and estradiol supplementation of ovarectomized female mice and control male mice protected against LPS-induced bone deterioration findings. Collectively, sex-specific differences exist in LPS-induced airway inflammatory consequences with significant differences found in bone quantity and quality parameters. Male mice demonstrated susceptibility to bone loss and female animals were protected, which was modulated by estrogen. Therefore, sex differences influence the biologic response in the lung-bone inflammatory axis in response to inhalant LPS exposures.

Skin sensitization is an important occupational health problem and immunotoxicity endpoint. Considering animal welfare and time and cost savings, many alternative approaches, such as those conducted in vitro, in silico, and in chemo, have been proposed and applied to predict skin sensitization of compounds. Toxicologically, sensitizers can elicit excess toxicity at greater levels than non-sensitizers due to their capacity to react with proteins/peptides. Based on this understanding, calculated toxicity enhancements (T_e) of 65 organic compounds from three in vitro bioassays, i.e. 48-hr ciliate (Tetrahymena pyriformis) growth inhibition, and both 96-hr fathead minnow and 48-hr Daphnia magna acute lethal toxicities, were employed to qualitatively and quantitatively predict skin sensitization potencies of the test agents. The sensitivity, specificity, and accuracy reaching 80% strongly suggested toxicity enhancement was an excellent parameter for predicting skin sensitization. Linear regressions of skin sensitization against toxicity enhancement were fitted for each bioassay, and they were improved after the sensitizers were categorized into different reaction mechanistic domains, which, in decreasing order of contribution from T_e to sensitization, were S_NAr > S_N1 > MA. These results indicated that toxicity bioassays are useful tools and that T_e could be a useful parameter that might be applied to predict skin sensitization.

Immune cells are known as the most sensitive tissue for ionizing radiation. Numerous reports relating with the effect of low-dose ionizing radiation (LDIR) on immune activities showed that LDIR can induce immune-potentiation via modulating the activity of B-, T-, and NK cells, or macrophages, whereas high-dose radiation induces genome-wide apoptotic/necrotic tissue injury and immune suppression. Generally, CD4⁺ T-cells play pivotal roles in immune systems via cytokines and cell-surface molecules to activate other types of immune cells to eliminate the pathogen. In spite of the significance of CD4⁺ T-cells in the immune system, mechanism of how LDIR regulates CD4⁺ T-cell gene expression is poorly investigated. Thus, RNA-Seq and Gene-Set Enrichment Analysis (GSEA) analysis were done with low-dose irradiated (γ-radiation, 50 mGy, 204 mGy/h)/anti-CD3/CD28-stimulated CD4⁺ T-cells to explore the LDIR-specific regulation of CD4⁺ T-cell gene expression. The results indicated that the genes related to mRNA translation processes, mitochondrial function, cell cycle regulation, and cytokine induction were upregulated in irradiated cells. Moreover, this study showed that the expression of T-helper cell Type 1 (T_H1) or type 2 (T_H2) cytokine genes, such as those for interferon (IFN)-γ, interleukin (IL)-4, and IL-5 were increased by at least 1.4-fold in acute (204 mGy/h) or chronic (10 mGy/h) low-dose (10 or 50 mGy) irradiated/anti-CD3/CD28 stimulated CD4⁺ T-cells, whereas the T-regulatory (T_reg) cell cytokine gene, transforming growth factor (TGF)-β was decreased. Overall, these findings demonstrated that LDIR could cause an upregulation of selected immune product genes and, in turn, might modulate the activity of CD4⁺ T-cells undergoing activation via an impact on cytokine gene regulation.

Clinical evidence suggests that most idiosyncratic drug-induced liver injury (IDILI) is immune-mediated. The danger hypothesis suggests that liver injury and inflammation would increase the risk of an immune response leading to IDILI. Therefore, a reasonable hypothesis would be that an underlying chronic liver disease such as non-alcoholic steatohepatitis (NASH) would increase the risk of developing IDILI due to inflammation and release of danger signals from damaged cells. In order to test this hypothesis, mice were fed a methionine-/choline-deficient (MCD) diet that produces a consistent NASH phenotype, along with amodiaquine (AQ) - a drug known to cause IDILI in humans. This study employed both wild-type C57BL/6 mice and PD-1^-/- mice co-treated with anti-CTLA-4 antibodies. The PD-1^-/- + anti-CTLA-4 model produces an immune-mediated liver injury very similar to the idiosyncratic liver injury observed in humans. The liver injury observed in the present experiment was dominated by the injury caused by the MCD diet; there was no significant difference between mice treated with the MCD diet alone and those also treated with AQ, whether in wild-type mice of the PD-1^-/- model. Therefore, the MCD diet, which results in a state that mimics NASH, did not appear to increase the liver injury associated with AQ treatment. Ultimately, an animal model is just that - only a model, and cannot provide a definitive answer to clinical questions. However, given the difficulty of performing clinical studies with appropriate control populations, the present results provide important evidence to support a general clinical finding that underlying liver injury does not usually increase the risk of IDILI.

The immunotoxic potential of drug candidates is assessed through the examination of results from a variety of studies and endpoints. While the functional assessment of CD8⁺ cytotoxic T-lymphocytes (CTL) is well-characterized in the clinic, the lack of a robust macaque CTL functional assay has been an important hurdle in evaluating and accurately quantifying cell-mediated CD8⁺ T-cell effector responses in the nonclinical setting. This paper describes the development of an assay to measure CTL activity in peripheral blood mononuclear cells (PBMC) isolated from Cynomolgus macaques. A human EGFR/CD3 Bispecific T-cell Engager (BiTE^®) was used to mount a robust CD8⁺ T-cell response in the presence of target-expressing cells. Upon target engagement, degranulation of CD107a and production of interferon (IFN)-γ both reliably indicated a robust functional response in CD8⁺ T-cells. The BiTE^®-mediated stimulation method proved to be favorable when compared to other methods of stimulation in the absence of target cells. These studies demonstrated acceptable longitudinal variability of the functional assay and sensitivity to dexamethasone-mediated immunosuppression. Taken together, the results indicated an assay leveraging CD3-bispecific antibodies and target-expressing cells can provide a robust approach to the in vitro or ex vivo assessment of CTL function in Cynomolgus macaques. Because the impairment of CTL activity by immunomodulators is recognized to be an important contributor to decreased antiviral defense and increased carcinogenicity risk, we believe that this novel assay to be a valuable addition to the immunotoxicology assessment of therapeutic drug candidates.