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Increased expectations from a number of regulatory agencies, e.g., Environmental Protection Agency (EPA), Food and Drug Administration (FDA), European Medicines Agency (EMEA), and the Ministry of Health, Labour and Welfare (MHLW) of Japan, call for the evaluation of potential adverse effects on the immune system. As recently summarized in the ICH S8 guideline, the T-cell-dependent antibody response (TDAR) has been identified in a regulatory context as a main functional test of immunotoxicity. While the characterization of immunotoxic potential is pertinent to both the chemical and pharmaceutical industries, the use of immunotoxicology data for hazard identification and/or risk assessment in each case is different. Therefore, multiple approaches to immunotoxicity testing have evolved. The assays that evaluate TDAR function include both well-established tests, e.g., anti-sheep red blood cell plaque-forming cell (PFC) assay, and newer models, e.g., anti-keyhole limpet hemocyanin (KLH) antibody ELISA. These tests vary in the study design, antigen application and analytical methods. However, they all evaluate the same endpoint - a competent immune (e.g., antibody) response to an antigen. Numerous issues have been identified in the application of TDAR tests, including high animal to animal variability; differences in antigen source and potency; a lack of established "normal range" of the immune response and uncertainty about the degree of inhibition of the TDAR to be considered toxicologically important. As such, the need for a forum to discuss these issues was recognized by the immunotoxicology community, and was addressed at the 2006 Society of Toxicology (SOT) Workshop. A series of papers will summarize that forum with the ultimate objectives being to build a consensus among immunotoxicologists on the implications of these factors on using TDAR results in hazard identification and/or risk assessment, and to establish a criteria to classify compounds as immunotoxicants. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Prebiotics are known as the ‘food’ for beneficial gut microbiota that are capable of promoting host health. Their effects depend on the product of gut fermentation or metabolites. This paper discusses the role of prebiotics on cytotoxicity, genotoxicity, and cell integrity. Metabolites produced from the fermentation of prebiotics can be used to understand gut diseases such as colorectal cancer. Fecal water fromin vivoorin vitrostudies can be used to understand the relationship between prebiotics and gut diseases because of its close contact with colon epithelium. Besides, fecal water has compounds that are capable of modifying colonocytes. [ABSTRACT FROM AUTHOR]

Plant protection products (PPPs) and the active substance(s) contained within them are rigorously and comprehensively tested prior to registration to ensure that human health is not impacted by their use. In recent years, there has been a widespread drive to have more relevant testing strategies (e.g., ILSI/HESI-ACSA and new EU Directives), which also take account of animal welfare, including the 3R (replacement, refinement, and reduction) principles. The toxicity potential of one such new active substance, sulfoxaflor, a sulfoximine insecticide (CAS #946578-00-3), was evaluated utilizing innovative testing strategies comprising: (1) an integrated testing scheme to optimize information obtained from as few animals as possible (i.e., 3R principles) through modifications of standard protocols, such as enhanced palatability study design, to include molecular endpoints, additional neurotoxicity and immunotoxicity parameters in a subchronic toxicity study, and combining multiple test guidelines into one study protocol; (2) generation of toxicokinetic data across dose levels, sexes, study durations, species, strains and life stages, without using satellite animals, which was a first for PPP development, and (3) addition of prospective mode of action (MoA) endpoints within repeat dose toxicity studies as well as proactive inclusion of specific MoA studies as an integral part of the development program. These novel approaches to generate key data early in the safety evaluation program facilitated informed decision-making on the need for additional studies and contributed to a more relevant human health risk assessment. This supplement also contains papers which describe in more detail the approach taken to establish the MoA and human relevance framework related to toxicities elicited by sulfoxaflor in the mammalian toxicology studies: [ABSTRACT FROM AUTHOR]

Deleterious health effects induced by inorganic vanadium compounds are linked with carcinogenic, immunotoxic and neurotoxic insults. The goal of this review is to provide a summary of mammalian cell culture studies (from the 1990s to most recent) looking into the mode of the above-mentioned adverse actions of vanadium. Regarding the carcinogenicity potential, the key cell-based studies have evidenced the ability of vanadium to induce genotoxic lesions, cell morphological transformation and anti-apoptotic effects in a certain type of cells. Two contradictory effects of vanadium on the immune functions of cells have been observed in cell culture studies. The first effect involves reduction of cell immune responses such as vanadium-dependent inhibition of cytokine-inducible functions, which may underlie the mechanism of vanadium-induced immunosuppression. The second one involves stimulation of immune activity, for example, a vanadium-mediated increase in cytokine production, which may contribute to vanadium-related inflammation. So far, an in vitro evaluation of vanadium neurotoxicity has only been reported in few articles. These papers indicate probable cytotoxic mechanisms resulting from exposure of neurons and glial cells to vanadium. In summary, this literature review collects in vitro reports on adverse vanadium effects and thus provides vanadium researchers with a single, concise source of data. [ABSTRACT FROM AUTHOR]

Suitable assays and test strategies are needed to analyze potential genotoxic and immunotoxic health effects caused by nanoparticle exposure. The development and validation of such methods is challenging because nanoparticles may show unexpected behavior, like aggregation or interference with optical measurements, when routine in vitro assays are performed. In our interdisciplinary study, the effects of inorganic gold (4.5 nm) and iron oxide (7.3 nm) nanoparticles with a narrow size distribution were tested on human cells using different assay systems. The results show that cytotoxicity as well as immunotoxicity and genotoxicity induced by these two inorganic nanoparticles was low or absent when using a panel of cell-based tests in different laboratories. However, several technical issues had to be tackled that were specific for working with nanoparticles. The methods used, their suitability for nanotoxicity testing, and the technical problems encountered are carefully described and discussed in this paper. [ABSTRACT FROM AUTHOR]

The number of anti-inflammatory and immunomodulatory drugs being developed in the pharmaceutical industry has increased considerably in the past decade. This increase in research and development has been paralleled by questions from both regulatory agencies and industry on how best to assess decreased host resistance to infections or adverse immunostimulation caused by immunomodulatory agents such as anti-cytokine antibodies (e.g., the tumor necrosis factor-α inhibitors), anti-adhesion molecule antibodies (e.g., anti-α-4 integrin inhibitors) and immunostimulatory molecules (e.g., anti-CD28 antibodies). Although several methods have been developed for nonclinical assessment of immunotoxicity, highly publicized adverse events have brought to light significant gaps in the application of nonclinical immunotoxicity testing in assessing potential risk in humans. Confounding this problem is inconsistent application of immunotoxicology methods for risk assessment within the scientific community, limited understanding of appropriate immunotoxicity testing strategy for immunomodulators and inconsistent testing requests by regulatory agencies. To address these concerns, The Immunotoxicology Technical Committee (ITC) of the International Life Science Institute (ILSI) Health and Environmental Sciences Institute (HESI) organized a workshop on Immunomodulators and Clinical Immunotoxicology in May 2007. The Workshop was convened to identify key gaps in nonclinical and clinical immunotoxicity testing of anti-inflammatory and immunomodulatory agents and to begin to develop consistent approaches for immunotoxicity testing and risk assessment. This paper summarizes the outcome of the HESI ITC Immunomodulators and Clinical Immunotoxicology Workshop. Topics not discussed at the Workshop were outside the scope of this report. Although more work is needed to develop consistent approaches for immunotoxicity assessment of immunomodulators, this Workshop provided the foundation for future discussion. [ABSTRACT FROM AUTHOR]

It has long been known that the developing immune system is more sensitive and susceptible than the adult immune system to some drugs and environmental contaminants. However, notable advances have been made in the database of studies supporting developmental immunotoxicity (DIT) over the past 5 years. There is considerable evidence that responses of the immune system can be quantitatively or qualitatively different from normal adult responses when xenobiotic exposure occurs during critical periods of immune system development. Qualitative differences of DIT relative to adult exposures include examples of more persistent effects, a latency of effects, and immune dysfunction that is fundamentally different than effects observed when adults are exposed. A symposium was presented at the Society of Toxicology annual meeting to provide an update on advances in the maturing field of developmental immunotoxicology and to facilitate discussion on the range of DIT and later life effects following developmental exposure. In particular, presentations focused on implications of neuroendocrine cross-talk for DIT, the association between developmental air pollutant exposure and asthma, and recent evidence that developmental exposure to 2,3,7,8-tetrachlorodibenzo- p-dioxin may increase the risk of autoimmune responses. Several important concepts relative to DIT assessment were illustrated, i.e., (1) Screening for immunosuppression alone is not sufficient to identify all potential immunotoxic effects; (2) DIT cannot be reliably predicted from studies that only utilize adult exposures; (3) Functional testing protocols are preferred in the assessment of DIT; (4) Gender-related differences should be routinely assessed; (5) Latency (i.e., later-life adverse outcomes resulting from developmental exposures) is an important consideration that cannot be detected in adult exposure studies; and, (6) There is increasing support for DIT testing protocols with continuous exposure throughout development until the immune assay is performed. [ABSTRACT FROM AUTHOR]

Micro- and nanoplastics (MNP) are ubiquitously present in the environment due to their high persistence and bioaccumulative properties. Humans get exposed to MNP via various routes and consequently, they will encounter dendritic cells (DC) which are antigen-presenting cells involved in regulating immune responses. The consequences of DC exposure to MNP are an important, yet understudied, cause of concern. Therefore, this study aimed to assess the uptake and effect of MNP in vitro by exposing human monocyte-derived dendritic cells (MoDC) to virgin and environmentally weathered polystyrene (PS) particles of different sizes (0.2, 1, and 10 µm), at different concentrations ranging from 1 to 100 µg/ml. The effects of these particles were examined by measuring co-stimulatory surface marker (i.e. CD83 and CD86) expression. In addition, T-cell proliferation was measured via a mixed-leukocyte reaction (MLR) assay. The results showed that MoDC were capable of absorbing PS particles, and this was facilitated by pre-incubation in heat-inactivated (HI) plasma. Furthermore, depending on their size, weathered PS particles in particular caused increased expression of CD83 and CD86 on MoDC. Lastly, weathered 0.2 µm PS particles were able to functionally activate MoDC, leading to an increase in T-cell activation. These in vitro data suggest that, depending on their size, weathered PS particles might act as an immunostimulating adjuvant, possibly leading to T-cell sensitization. [ABSTRACT FROM AUTHOR]

In development of peptide therapeutics, rodents are commonly-used preclinical models when screening compounds for efficacy endpoints in the early stages of discovery projects. During the screening process, some peptides administered subcutaneously to rodents caused injection site reactions manifesting as localized swelling. Screening by postmortem evaluations of injection site swelling as a marker for local subcutaneous histamine release, were conducted in rats to select drug candidates without this adverse effect. Histological analysis of skin samples revealed that the injection site reactions were concurrent with mast cell degranulation, resulting in histamine release. Mast cell activation can be mediated by MRGPRX2, a GPCR that induces a pseudo-allergenic immune response. The present study demonstrates that a commercially-available cell-based MRGPRX2 assay reliably identifies compounds that induce histamine release or localized edema in ex vivo human and rodent skin samples. In vitro screening was subsequently implemented using the MRGPRX2 assay as a substitute for postmortem injection site evaluation, thus achieving a significant reduction in animal use. Thus, in cases where injection site reactions are encountered during in vivo screening, to enable faster screening during the early drug discovery process, an MRGPRX2 in vitro assay can be used as an efficient, more ethical tool with human translational value for the development of safer pharmacotherapies for patients. [ABSTRACT FROM AUTHOR]

Endocrine-disrupting chemicals (EDCs) refer to a group of chemicals that cause adverse effects in human health, impairing hormone production and regulation, resulting in alteration of homeostasis, reproductive, and developmental, and immune system impairments. The immunotoxicity of EDCs involves many mechanisms altering gene expression that depend on the activation of nuclear receptors such as the aryl hydrocarbon receptor (AHR), the estrogen receptor (ER), and the peroxisome proliferator-activated receptor (PPAR), which also results in skin and intestinal disorders, microbiota alterations and inflammatory diseases. This systematic review aims to review different mechanisms of immunotoxicity and immunomodulation of T cells, focusing on T regulatory (Treg) and Th17 subsets, B cells, and dendritic cells (DCs) caused by specific EDCs such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), bisphenols (BPs) and polyfluoroalkyl substances (PFASs). To achieve this objective, a systematic study was conducted searching various databases including PubMed and Scopus to find in-vitro, in-vivo, and biomonitoring studies that examine EDC-dependent mechanisms of immunotoxicity. While doing the systematic review, we found species- and cell-specific outcomes and a translational gap between in-vitro and in-vivo experiments. Finally, an adverse outcome pathway (AOP) framework is proposed, which explains mechanistically toxicity endpoints emerging from different EDCs having similar key events and can help to improve our understanding of EDCs mechanisms of immunotoxicity. In conclusion, this review provides insights into the mechanisms of immunotoxicity mediated by EDCs and will help to improve human health risk assessment. Overview of the mechanisms of immunotoxicity of EDCs for T, B, and Dendritic cells and the main outcomes of exposure that result in immunotoxicity: imbalance of Treg/Th17 lymphocyte populations; a decrease of antibodies production; an increase of DCs maturation. [ABSTRACT FROM AUTHOR]

Introduces a series of articles related to the use of immunotoxicology in health risk assessment, which was presented at the Annual Aquatic Toxicity Workshop on October 3-6, 1999 in Canada.

Bisphenols are common chemicals found in plastics and epoxy resins. Over the past decades, many studies have shown that bisphenol A (BPA) is a potential endocrine-disrupting chemical that may cause multisystem toxicity. However, the relative safety of BPA analogues is a controversial subject. Herein, we conducted a review of the reproductive toxicity, neurotoxicity, immunotoxicity, metabolic toxicity and gut microbiome toxicity of the BPA analogues in various species, including Caenorhabditis elegans, zebrafish, turtles, sheep, rodents, and humans. In addition, the mechanisms of action were discussed with focus on bisphenol S and bisphenol F. It was found that these BPA analogues exert their toxic effects on different organs and systems through various mechanisms including epigenetic modifications and effects on cell signaling pathways, microbiome, and metabolome in different species. More research is needed to study the relative toxicity of the lesser-known BPA analogues compared to BPA, both systemically and organ specifically, and to better define the underlying mechanisms of action, in particular, the potentials of disrupting microbiome and metabolism. [ABSTRACT FROM AUTHOR]

Resveratrol is a naturally occurring polyphenol that is being investigated to treat and prevent various diseases, both experimentally and in the clinic. Despite increased use and interest in resveratrol due to its immunomodulatory properties, there is a lack of studies evaluating potential toxicities, particularly immunotoxicity, associated with resveratrol use. A previous 2-week study found decreasing thymus weight in male B6C3F1/N mice with increasing exposure to trans-resveratrol. This study is a follow-up on those findings by evaluating immune function. Male adult B6C3F1/N mice were given trans-resveratrol (0, 156, 312, 625, 1250, 2500 mg/kg/day) via oral gavage for 28 days and functional immune tests and histopathology were evaluated. There were no treatment-related effects on body weight during the study. Humoral, cell-mediated, and innate immune function were not altered after 28 days of trans-resveratrol treatment. There were also no changes in organ weight or microscopic alterations in immune organs. Overall, under the conditions of this study, there was no evidence of immunotoxicity or improvements in immune function associated with oral exposure to trans-resveratrol in male mice. Importantly, the immunomodulatory benefits of resveratrol may require a prerequisite level of inflammatory activity and may not be observable in healthy individuals. [ABSTRACT FROM AUTHOR]

Modified nanoparticles (NPs) can interact with the immune system by causing its activation to fight tumors or for vaccination. During this activation, dendritic cells (DCs) are effective in generating robust immune response. However, the effect of nanomaterials on dendritic cell (DC) maturation, and the associated adjuvant effect, should be assessed as a novel biocompatibility criteria for biomaterials since immune consequences may constitute potential complications in nanomedicine. Among emerging biomaterials, poly(lactic-co-glycolic acid) NPs (PLGA NPs) are widely explored for various applications in which the degree of desired adjuvant effect may vary. As contradictory results are reported regarding their effects on DCs, we aimed at clarifying this point with particular emphasis on the relative impact of particle surface properties. To that end, NP uptake and effects on the viability, phenotype, and secretory activity of DC primary cultures. Intracellular signaling pathways were explored and evaluated. Immature human and murine DCs were exposed to cationic, neutral, or anionic PLGA NPs. Particle uptake was assessed by both confocal microscopy and flow cytometry. Cell viability was then evaluated prior to the study of maturation by examination of both surface marker expression and cytokine release. Our results demonstrate that PLGA NPs are rapidly engulfed by DCs and do not exert cytotoxic effects. However, upon exposure to PLGA NPs, DCs showed phenotypes and cytokine secretion profiles consistent with maturation which resulted, at least in part, from the transient intracellular activation of mitogen-activated protein kinases (MAPKs). Interestingly, NP-specific stimulation patterns were observed since NP surface properties had a sensible influence on the various parameters measured. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In vertebrates, many studies verified the immunomodulatory effect of melatonin in various tissues. Its exact role in lower organisms like insects has been very sketchy. The present study deals with understanding the immunomodulatory effect of melatonin in pesticide exposed insects. Total hemocyte count, Differential hemocyte count, Prophenoloxidase activity, and nodulation mechanism at different time intervals were studied. Results showed the abamectin results in significant increase (p < 0.01) in haemocytes numbers at 6, 48, and 72 h. Abamectin toxicity was counteracted by melatonin, with decreasing the hemocytes at 2, 4, and 12 h. Prophenoloxidase activity and protein content (p < 0.001) at 48 and 72 h of Melatonin + abamectin were slightly decreased. There was a significant decrease in nodule formation in 12-24 h in melatonin treated groups and it was clearly visible at 6 h. Increased Prohemocytes, Plasmatocytes, and Oenocytoids numbers decline in melatonin treatment. Melatonin treatment increased the survival rate on pesticide exposed insects. Results suggest that melatonin exposure significantly reduces the toxicity in pesticide exposed larvae which in turn brings back immunological profile in a time dependent manner. [ABSTRACT FROM AUTHOR]

Cytotoxicity evaluation of hemocytes (lysosomal membrane stability [LMS] assay) fromMytilus galloprovincialis Lamarck, exposed to a sublethal dose (100 μg/L) of two size of silver nanoparticles (AgNPs: <50 nm and <100 nm) – prior to and after inhibition of potential uptake pathways (i.e., clathrin- and caveolae-mediated endocytosis) within different times of exposure (3, 6, 12 h) – showed that there was a significant cytotoxic effect on immune cells of mussels exposed for different times to either AgNP size (p < 0.01); the greater effect was with the smaller size. However, hemocytes seemed more sensitive to the larger AgNP after clathrin-mediated endocytosis was blocked (p < 0.01); this was not so with inhibition of caveolae-mediated endocytosis. Dimethyl-sulfoxide (DMSO) did not impart a carrier-mediated effect despite an enhanced cytotoxicity when DMSO was present with AgNP. From these results, it is concluded that the immunotoxicity of AgNP in mussels was size-dependent as well as length of exposure-dependent. It was also clear that nanoparticles (NP) internalization mechanisms were a major factor underlying any toxicity. [ABSTRACT FROM PUBLISHER]

Environmentally induced perturbation of health parameters lead to morphological changes associated to the inflammatory response. Hematoxyline and eosin (H&E)-stained gill filaments sections were examined for such changes and inflammation intensity was scored according to a quantitative model in order to evaluate the health status ofin vivoexposed (for 3, 6, and 12 h) mussels to silver nanoparticles (Ag-NPs <50 nm and Ag-NPs <100 nm) prior and after the inhibition of two potential uptake pathways (clathrin- and caveolae-mediated endocytosis) with the aid of pharmaceutical inhibitors (amantadine and nystatin). The impacts of the nanoparticles (NPs) size, as well as their uptake routes within different time of exposure on the inflammatory response were assessed. The results showed that Ag-NPs clearly induced morphological changes associated to the inflammatory response in gill tissues (Mann–Whitneypvalues were <.05). It is also clear that the length of the exposure as well as the NP size highly impacted inflammation intensity (highest histopathological indices recorded with Ag-NPs <100 nm). Also, the routes of NPs entry noticed to be major factor underlying inflammatory response (significant inflammation intensity reported with Ag-NPs <50 nm after blockade of uptake routes;p <.05). Throughout, it was concluded that inflammation intensity was related to NPs size and exposure time. Overall, uptake routes are shown to be the major factor underlying nanotoxicity. [ABSTRACT FROM AUTHOR]

Despite frequent field observations of impaired immune response and increased disease incidence in contaminant-exposed wildlife populations, immunotoxic effects are rarely considered in ecotoxicological risk assessment. The aim of this study was to review the literature on immunotoxic effects of chemicals in fish to quantitatively evaluate (i) which experimental approaches were used to assess immunotoxic effects, (ii) whether immune markers exist to screen for potential immunotoxic activities of chemicals, and (iii) how predictive those parameters are for adverse alterations of fish immunocompetence and disease resistance. A total of 241 publications on fish immunotoxicity were quantitatively analyzed. The main conclusions included: (i) To date, fish immunotoxicology focused mainly on innate immune responses and immunosuppressive effects. (ii) In numerous studies, the experimental conditions are poorly documented, as for instance age or sex of the fish or the rationale for the selected exposure conditions is often missing. (iii) Although a broad variety of parameters were used to assess immunotoxicity, the rationale for the choice of measured parameters was often not given, remaining unclear how they link to the suspected immunotoxic mode of action of the chemicals. (iv) At the current state of knowledge, it is impossible to identify a set of immune parameters that could reliably screen for immunotoxic potentials of chemicals. (v) Similarly, in fish immunotoxicology there is insufficient understanding of how and when chemical-induced modulations of molecular/cellular immune changes relate to adverse alterations of fish immunocompetence, although this would be crucial to include immunotoxicity in ecotoxicological risk assessment. [ABSTRACT FROM PUBLISHER]

Mercury (Hg) is toxic and hazardous metal that causes natural disasters in the earth's crust. Exposure to Hg occurs via various routes; like oral (fish), inhalation, dental amalgams, and skin from cosmetics. In this review, we have discussed the sources of Hg and its potential for causing toxicity in humans. In addition, we also review its bio-chemical cycling in the environment; its systemic, immunotoxic, genotoxic/carcinogenic, and teratogenic health effects; and the dietary influences; as well as the important considerations in risk assessment and management of Hg poisoning have been discussed in detail. Many harmful outcomes have been reported, which will provide more awareness. [ABSTRACT FROM PUBLISHER]

Humans could become exposed to carbon black nanoparticles (CBNPs) in consumer products or an occupational setting. In rodent models, acute respiratory, subcutaneous, and direct immune cell exposure to CBNPs has been shown to enhance allergic sensitization to co-administered ovalbumin (OVA) protein from chicken egg. However, little is known about the effects of ingested CBNPs on immunological responses and oral tolerance to food antigens. We hypothesized that ingestion of CBNPs would enhance the development of food allergy to OVA. Allergy prone DO11.10 mice were orally exposed to CBNPs every second day for 2 weeks (total dose 10.8 (LOW) or 108 μg (HI)), with and without (±) co-administered OVA. Systemic immune parameters were measured at necropsy. Exposure to OVA resulted in significant increases in serum anti-OVA IgG1, anti-OVA IgM, and anti-OVA IgA antibodies relative to vehicle control. Immunophenotyping revealed a reduction in the number of OVA-specific CD4+ T helper cells upon OVA ± CBNPHItreatment in the spleen. Yet, secretion of the allergy-associated Th2 cytokines IL-4, IL-9, and IL-13 was greater in OVA323-339peptide-pulsed splenocytes from OVA + CBNPHI-treated mice compared with control. Transcriptome analysis at necropsy of splenocytes from OVA + CBNPHIdose mice compared with OVA mice revealed increases in the allergy associated genesIl4andStat6and decreases inCsf3randRetnlg. Although oral exposure to high-dose CBNPs did not impact OVA-specific antibody production relative to OVA, we did observe increased expression of genes and cytokines associated with allergy in peripheral splenocytes. This work suggests that CBNP gastrointestinal exposure may potentiate allergy pathways. [ABSTRACT FROM AUTHOR]

The aim of the present study was to explore the potential hematotoxic and immunotoxic effects of melamine (MA) in the absence and presence of formaldehyde (FA) in mice. Forty adult Swiss mice were equally allocated into four groups and daily treated with water, MA (50 mg/kg), FA (25 mg/kg), and MA + FA respectively via feeding needle for 60 consecutive days. Hematological status was evaluated using erythrogram and leukogram profiling. Innate immune functions were assessed by measuring white blood cells lysozyme and phagocytic activities. Serum immunoglobulin levels were evaluated as indicators of humoral immunity. In addition, histologic and immunohistochemical evaluations of splenic tissues were performed. The results indicated that either MA or FA treatment resulted in significant decreases in RBCs, Hb, MCHC, total WBC, lymphocyte, and basophile levels as well as in WBCs phagocytosis and lysozyme activity. In contrast, MCV, PCV%, and reticulocyte levels were significantly increased in these hosts. The total IgM level was significantly reduced in the MA-only-exposed mice but markedly increased in the FA-only-treated ones. A significant decrease in serum IgG levels was detected following either MA or FA treatment. The combined exposure to MA and FA, compared to levels of either toxicant alone, was revealed to evoke a significant improvement in Hb, PCV%, MCV, MCHC, neutrophil, eosinophil, total IgM level, and lysozyme activity; however these values did not reach that of the controls. Furthermore, compared to control mice, both MA-only- and FA-only-treated mice showed a strong distribution of CD4+and CD8+cells in their spleens, while a moderate presence of the former cells was obvious at their co-exposure. Taken together, these findings revealed that exposure to MA or FA resulted in significant alterations in hemato-immune parameters at variable degrees while a co-exposure resulted in the mitigation of most effects of either toxicant alone. [ABSTRACT FROM AUTHOR]

The potential to engineer extracellular vesicles (EV) that target specific cells and deliver a therapeutic payload has propelled a growing interest in their development as promising therapeutics. These EV are often produced from cultured cells. Very little is known about the interaction of cell culture-derived EV with cells of the immune system and their potential immunomodulatory effects. The present study evaluated potential immunotoxic effects of HEK293T-derived EV on the human monocytic cell lines THP-1 and U937. Incubation of cells with different doses of EV for 16–24 h was followed by assessment of cytotoxicity and cell function by flow cytometry. Changes in cell functionality were evaluated by the capacity of cells to phagocytize fluorescent microspheres. In addition, the internalization of labeled EV in THP-1 and U937 cells was evaluated. Exposure to EV did not affect the viability of THP-1 or U937 cells. Although lower doses of the EV increased phagocytic capacity in both cell lines, phagocytic efficiency of individual cells was not affected by EV exposure at any of the doses evaluated. This study also demonstrated that THP-1 and U937 monocytic cells are highly permissive to EV entry in a dose-response manner. These results suggest that, although HEK293T-derived EV are efficiently internalized by human monocytic cells, they do not exert a cytotoxic effect or alter phagocytic efficiency on the cell lines evaluated. [ABSTRACT FROM AUTHOR]

The development of immune-dependent drug hypersensitivity reactions (IDHR) is likely to involve activation of the innate immune system to stimulate neo-antigen specific T-cells. Previously it has been shown that, upon oral exposure to several drugs with immune-adjuvant capacity, mice developed T-cell-dependent responses to TNP-OVA. These results were indicative of the adjuvant potential of these drugs. The present study set out to evaluate the nature of this adjuvant potential by focusing on early immune changes in the spleen, by testing several drugs in the same experimental model. Mice were exposed to one or multiple oral doses of previously-tested drugs: the non-steroidal-anti-inflammatory drug (NSAID) diclofenac (DF), the analgesic acetaminophen (APAP), the anti-epileptic drug carbamazepine (CMZ) or the antibiotic ofloxacin (OFLX). Within 24 h after the final dosing, early innate and also adaptive immune parameters in the spleen were examined. In addition, liver tissue was also evaluated for damage. Exposure to APAP resulted in severe liver damage, increased levels of serum alanine aminotransferase (ALT) and local MIP-2 expression. DF exposure did not cause visible liver damage, but did increase liver weight. DF also elicited clear effects on splenic innate and adaptive immune cells, i.e. increased levels of NK cells and memory T-cells. Furthermore, an increase in plasma MIP-2 levels combined with an influx of neutrophils into the spleen was observed. OFLX and CMZ exposure resulted in increased liver weights, MIP-2 expression and up-regulation of co-stimulatory molecules on antigen-presenting cells (APC). The data suggested that multiple immune parameters were altered upon exposure to drugs known to elicit immunosensitization and that broad evaluation of immune changes in straightforward short-term animal models is needed to determine whether a drug may harbor the hazard to induce IDHR. The oral exposure approach as used here may be applied in the future as an immunotoxicological research tool in this type of evaluation. [ABSTRACT FROM AUTHOR]

Vanadium (V) is a transition metal often adhered to particulate matter and released into the atmosphere as vanadium pentoxide (V2O5) by the burning of fossil fuels. This air pollutant causes adverse effects in the immune system. Lymphocytosis and splenomegaly have been reported with increased white pulp in mice after V inhalation. The effect of V on the immune system as related to sex has been poorly investigated. This study sought to determine if V inhalation (a) produced lymphoproliferation that could explain the changes previously observed in the spleen and in peripheral blood lymphocyte counts and (b) whether any observed effects differed due to gender. Immunohistochemical analyses of Ki-67, a specific proliferation marker, was made in the spleens of CD-1 male and female mice exposed for 1 h, twice a week, over a 12-week period to V2O5(at 1.4 mg V2O5/m3) by whole-body inhalation; similar analyses were performed on spleens of control mice exposed to vehicle (filtered air). The results showed that in male mice there was a significant increase in percentage of Ki-67 immunopositive lymphocytes starting from the second week and until the end of the exposure. The Ki-67 signal was cytoplasmic and nuclear in the exposed males, while in controls the signal was only nuclear. In female mice, V inhalation singificantly increased the percentage of proliferating lymphocytes only after 1 week of exposure. Ki-67 signal was observed only in the nucleus of lymphocytes from the control and exposed females. The results here help to explain the splenomegaly and lymphocytosis observed previously in male mice and support the lymphoproliferative effect induced by V. Lastly, the finding that there was a sex difference in the effect of vanadium on lymphocyte proliferation suggests a role for sex hormones in potential protection against V immunotoxicity; however, further studies are needed to support this hypothesis. [ABSTRACT FROM AUTHOR]

The objective of this study was to characterize the variability of rat lymphoid organ weights and morphology following treatment with a known immunotoxicant, with a focus on the usefulness of evaluating popliteal lymph node weight and histology. Cyclophosphamide was administered to male Sprague-Dawley rats by oral gavage at doses of 2, 7 or 12 mg/kg/day for 10 consecutive days. Left and right popliteal lymph nodes (PLN), spleen and thymus were collected at necropsy, weighed, fixed and processed for histopathology. Femoral bone marrow was also collected, fixed and processed for histology. Organ weight variability was greater for PLN than for either spleen or thymus in control animals. There was a significant but weak correlation between paired left and right PLN weights (p < 0.005;r2 = 0.2774). Significant treatment-related decreases in lymphoid organ weights were observed in spleen and thymus at ≥ 7 mg/kg/day (p < 0.01), whereas in PLN a significant decrease (p < 0.05) was noted only at 12 mg/kg/day. The inclusion of PLN did not enhance the sensitivity of detection of systemic treatment-related changes in lymphoid organs in a rat cyclophosphamide model. [ABSTRACT FROM AUTHOR]

The hallmark of the extended one-generation reproductive toxicity study (EOGRTS) is that, based on certain criteria or triggers, selected offspring are assigned at weaning to different cohorts for further investigation of sexual maturation, reproductive organ integrity and function, neuropathological and behavioral endpoints, and/or immune function. The triggers allow for a more customizable design based directly on the data, while minimizing animal usage. Compared to the two-generation reproductive toxicity study, the EOGRTS design increases the number, extent, and duration of F1-offspring assessments resulting in more thorough and efficient utilization of the first generation while excluding the second generation of offspring unless triggered. Therefore, the EOGRTS has the potential to reduce the number of rats required by nearly 1200 animals per study. When performing the EOGRTS, the complexity of this study should not be underestimated and experienced flexible testing laboratories with sufficient resources and historical control data for all parameters are essential. The aim of this review is to discuss the important aspects of this challenging study design and to share our knowledge on the implementation of this study in our laboratories. In addition, we elaborate on the type of criteria for expansion of the study and logistical considerations. Altogether, this review can be used as guidance by other labs, study monitors, and registration officers. [ABSTRACT FROM AUTHOR]

Whether perfluorooctanoate (PFOA) and perfluorooctanesulfonate (PFOS), two widely used and biopersistent synthetic chemicals, are immunotoxic in humans is unclear. Accordingly, this article systematically and critically reviews the epidemiologic evidence on the association between exposure to PFOA and PFOS and various immune-related health conditions in humans. Twenty-four epidemiologic studies have reported associations of PFOA and/or PFOS with immune-related health conditions, including ten studies of immune biomarker levels or gene expression patterns, ten studies of atopic or allergic disorders, five studies of infectious diseases, four studies of vaccine responses, and five studies of chronic inflammatory or autoimmune conditions (with several studies evaluating multiple endpoints). Asthma, the most commonly studied condition, was evaluated in seven studies. With few, often methodologically limited studies of any particular health condition, generally inconsistent results, and an inability to exclude confounding, bias, or chance as an explanation for observed associations, the available epidemiologic evidence is insufficient to reach a conclusion about a causal relationship between exposure to PFOA and PFOS and any immune-related health condition in humans. When interpreting such studies, an immunodeficiency should not be presumed to exist when there is no evidence of a clinical abnormality. Large, prospective studies with repeated exposure assessment in independent populations are needed to confirm some suggestive associations with certain endpoints. [ABSTRACT FROM AUTHOR]

Polymerized porcine hemoglobin (pPolyHb), which was synthesized from chemically modified porcine hemoglobin, can carry and deliver oxygen to tissues in addition to restoring intravascular volume. Assessment of the inflammatory response generated in the host is a part of the overall safety evaluation of pPolyHb. In this study, we measured the levels of IL-1β, IL-10, and CD11b/CD18 in response to pPolyHb stimulation, both in vivo (in rats) and in vitro. Our results suggest that the levels of these indicators are not statistically changed by pPolyHb, indicating that pPolyHb is not immunotoxic to cells and animals in this respect. [ABSTRACT FROM AUTHOR]

The immunotoxic effects of the isoquinoline alkaloid berberine (BBR) were investigated in Balb/c mice. Here, BBR was administered daily by intraperitoneal injection at doses of 5 and 10 mg/kg for 14 days. Following the exposure, host spleen weight, cellularity and histopathology, as well as delayed-type hypersensitivity (DTH) responses, hemagglutination titers (HA), spleen cell subtype profiles, splenocyte cytokine production and lymphocyte proliferation were studied in all of the test groups of animals. The results showed that the high dose of BBR (10 mg/kg) could suppress both cellular and humoral immune functions in the treated hosts. BBR at 5 mg/kg only appeared to impact on DTH responses and lymphoproliferation. Based on the finding here, it would seem that BBR has effective immunosuppressive properties. Mechanistic studies are required to determine exactly how this material is acting to impart many of the immunotoxic effects demonstrated here. At the same time, further research should also be performed on BBR to further develop its potential use as an effective immunosuppressant or co-adjuvant for the treatment of diseases caused by an exaggerated or unwanted immune response. [ABSTRACT FROM AUTHOR]

An important component of safety assessment of new pharmaceuticals is evaluation of their potential to increase the risk of developing cancer in humans. The traditional 2-year rodent bioassay often is not feasible or scientifically applicable for evaluation of biotherapeutics. Additionally, it has poor predictive value for non-genotoxic immunosuppressive compounds. Thus, there is a need for alternative testing strategies. A novel 3-stage tumor model in syngeneic C3H/HeN mice was evaluated here to study the effects of immunosuppressive drugs on tumor promotion and progressionin vivo. The model employed a skin squamous cell carcinoma cell line (SCC VII) due to the increased prevalence of squamous cell carcinoma (SCC) in humans associated with immunosuppression after transplants. Local invasion, colonization and tumor progression were evaluated. The validation set of immunosuppressive drugs included: Cyclosporin (CSA), cyclophosphamide (CTX), azathioprine, etanercept, abatacept and prednisone. Local invasion was evaluated by histological assessment as well as fluorescence trafficking from Qdot®-labeled tumor cells from the site of inoculation to the draining lymph node. Colonization was evaluated by lung colony counts following intravenous inoculation. Tumor progression was assessed by morphometric analysis of lesion area, angiogenesis and growth fraction of established metastatic neoplasia. Immunosuppressive drugs in the validation set yielded mixed results, including decreased progression. The methods and results described herein using anin vivosyngeneic mouse tumor model can provide insight about the assessment of immunosuppressive drugs in carcinogenicity risk assessment. [ABSTRACT FROM AUTHOR]

Triclosan is an antimicrobial chemical commonly used occupationally and by the general public. Using select immune function assays, the purpose of these studies was to evaluate the immunotoxicity of triclosan following dermal exposure using a murine model. Triclosan was not identified to be a sensitizer in the murine local lymph node assay (LLNA) when tested at concentrations ranging from 0.75–3.0%. Following a 28-day exposure, triclosan produced a significant increase in liver weight at concentrations of ≥ 1.5%. Exposure to the high dose (3.0%) also produced a significant increase in spleen weights and number of platelets. The absolute number of B-cells, T-cells, dendritic cells and NK cells were significantly increased in the skin draining lymph node, but not the spleen. An increase in the frequency of dendritic cells was also observed in the lymph node following exposure to 3.0% triclosan. The IgM antibody response to sheep red blood cells (SRBC) was significantly increased at 0.75% – but not at the higher concentrations – in the spleen and serum. These results demonstrate that dermal exposure to triclosan induces stimulation of the immune system in a murine model and raise concerns about potential human exposure. [ABSTRACT FROM AUTHOR]

Aflatoxins (AF) are important foodborne mycotoxins implicated in human health and have immunocytotoxic effects. The aims of this study were to evaluate a new aflatoxin B1(AFB1) and fumonisin B1(FB1)-binding/degrading micro-organism for biological detoxification, to examine its ability to degrade AFB1and FB1in liquid medium, and to evaluate its potentialin vivoprotective role against any combined effects from AFB1and FB1on host splenocyte caspase-3 activity (reflecting DNA damage/cell death) and mRNA levels of select inflammation-regulating cytokines. Balb/c mice were divided into groups (10/group) and treated daily for 2 weeks by oral gavage with AFB1(80 µg/kg BW), FB1(100 µg/kg), AFB1 + FB1, or lactic acid bacteria (Lactobacillus paracaseiBEJ01, 2 × 109 CFU/L, ∼2 mg/kg) – alone or in combination with the AFB1and/or FB1. After the exposures, spleens were collected for measures of caspase-3 activity, lipid peroxidation (LP), and glutathione (GSH) content, expression of anti-oxidation protective enzymes (GPx and SOD), and mRNA levels of inflammation-regulating cytokines (e.g.IL-10, IL-4, IFNγ, TNFα). Thymii were also removed for analysis of apoptosis. The results indicated that, in the spleen, exposure to the mycotoxins led to increased caspase-3 activity, LP, andIL-10andIL-4mRNA levels, but decreased GSH content and down-regulated expression of GPx and SOD, and ofIFNγandTNFαmRNA. Co-treatment using Lactic Acid Bacteria (LAB) with AFB1or FB1suppressed levels of DNA fragmentation, normalized splenic LP and increased GSH levels, up-regulated expression of GPx and SOD, and normalized mRNA levels of the analyzed cytokines. It is concluded that AFB1and FB1might have combinational (synergistic moreso than additive) toxic effectsin situ. Further, it can be seen that use of LAB induced protective effects against the oxidative stress and (immuno)toxicity of these agents in part through adhesion (and so likely diminished bioavalability). [ABSTRACT FROM PUBLISHER]

Signaling networks are essential elements that are involved in diverse cellular processes. One group of fundamental components in various signaling pathways concerns protein tyrosine kinases (PTK). Various toxicants have been demonstrated to exert their toxicity via modulation of tyrosine kinase activity. The present study aimed to identify common cellular signaling pathways that are involved in chemical-induced direct immunotoxicity. To this end, an antibody array-based profiling approach was applied to assess effects of five immunotoxicants, two immunosuppressive drugs and two non-immunotoxic control chemicals on the phosphorylation of 28 receptor tyrosine kinases and 11 crucial signaling nodes in Jurkat T-cells. The phosphorylation of ribosomal protein S6 (RPS6) and of kinases Akt, Src and p44/42 were found to be commonly regulated by immunotoxicants and/or immunosuppressive drugs (at least three compounds), with the largest effect observed upon RPS6. Flow cytometry and Western blotting were used to further examine the effect of the model immunotoxicant TBTO on the components of the mTOR-p70S6K-RPS6 pathway. These analyses revealed that both TBTO and the mTOR inhibitor rapamycin inactivate RPS6, but via different mechanisms. Finally, a comparison of the protein phosphorylation data to previously obtained transcriptome data of TBTO-treated Jurkat cells resulted in a good correlation at the pathway level and indicated that TBTO affects ribosome biogenesis and leukocyte migration. The effect of TBTO on the latter process was confirmed using a CXCL12 chemotaxis assay. [ABSTRACT FROM PUBLISHER]

The potential immunotoxicity of tabalumab was assessed as a component of standard pre-clinical toxicology studies in cynomolgus monkeys. To evaluate potential tabalumab-associated immunosuppression after antigen challenge, cynomolgus monkeys were administered placebo control or tabalumab in three immunotoxicological safety studies. Study 1, a 4-week pilot study, evaluated biweekly intravenous (IV) control, and 0.3, 1.0, 5.0, and 15.0 mg/kg tabalumab doses. Study 2 evaluated IV control, and 0.1, 1.0, and 30.0 mg/kg tabalumab doses biweekly for 6 weeks. Study 3 evaluated IV control and 0.1, 1.0, 30.0 mg/kg, and subcutaneous (SC) 30.0 mg/kg tabalumab biweekly for 6 months, with recovery (16 weeks) to monitor standard immunotoxicity endpoints. T-cell dependent primary and secondary antibody responses to tetanus toxoid antigen challenge (4-week and 6-week studies) or keyhole limpet hemocyanin (KLH; 6-week and 6-month studies) were evaluated as a measure of immunocompetence, together with quantitation of T- and B-cell subsets. In addition, anti-tabalumab antibody formation (6-week and 6-month studies) was assessed. The results indicated that, despite expected decreases in circulating B-cell populations, no changes in follicle histopathology or organ weights, except decreases in spleen weight (after 6-months of 30 mg/kg IV/SC treatment only), were attributed to tabalumab. Non-adverse microscopic decreases in size or number of germinal centers in spleen, mesenteric, and mandibular lymph nodes occurred, but without an effect on antibody responses to KLH or tetanus. At 16-weeks recovery, microscopic compound-related changes observed after 6 months of treatment were completely reversed (0.1 mg/kg group) and partially reversed (1.0 and 30.0 mg/kg groups), while peripheral blood B cells remained 66–72% reduced from baseline. Despite reduced germinal centres in lymphoid organs, and reductions in circulating B cells, T-cell-dependent humoral immunity was maintained following tabalumab administration in three safety studies in cynomolgus monkeys. [ABSTRACT FROM PUBLISHER]

In vitrogene profiling studies have associated the molecular pathways of Nrf2-Keap1 and Toll-like receptor (TLR) signaling with skin sensitization. In this study, the role of these pathways in the regulation of protein biomarkers for skin sensitization was further elucidated using transient gene knock-down of key components of the signaling cascades in HaCaT cells after exposure to dinitrochlorobenzene (DNCB). The effect of targeting these pathways was established through evaluation of heme oxygenase1 (HMOX1) and interleukin (IL)-8 production. These experiments showed that Nrf2 is not involved in regulating HMOX1 after exposure to DNCB, but that activation of TLR signaling moderates the expression of HMOX1. The regulation of IL-8 depended on Nrf2, but also on the Toll/interleukin-1 receptor (TIR)-domain-containing adapter-inducing interferon-β(TRIF) adaptor protein in TLR signaling. This study provides new insights into the regulation of HMOX1 and IL-8, but the exact regulating mechanisms remain to be further elucidated. [ABSTRACT FROM PUBLISHER]

Diazinon (DZN) has been used for several years in agriculture and urban applications leading to a variety of negative effects on health. Hesperidin (HDN) and garlic oil are naturally occurring compounds present in fruits and vegetables, which have been reported to have antioxidants and anti-inflammatory actions. This study was undertaken to throw light on the modulatory effect of HDN or garlic oil against hemato- and immunotoxicity induced by DZN in Wistar rats. Oral administration of DZN for 30 days resulted in significant decrease in RBCs count, Hb content, Ht value, platelet count, and relative lymphocyte and monocyte counts when compared with control groups. Moreover, DZN reduced significantly the serum total immunoglobulin concentration, hemagglutination titer, quantitative hemolysis of SRBCs, delayed type hypersensitivity, blood mononuclear cell proliferation, phagocytic index and blood T-cell subtypes (CD4+and CD8+) in comparison with vehicle treatment. Co-administration of HDN or garlic oil, 30 min before DZN was able to normalize most of the hematological and immunological parameters. These results suggested that HDN or garlic oil, the natural antioxidants, can alleviate DZN induced hemato- and immunotoxicity. [ABSTRACT FROM AUTHOR]

Paraquat (PQ), one of the most widely used herbicides, has been used for several decades in agriculture. Some studies suggest that PQ has effects on the immune system. Moreover, previous studies have shown that PQ imparted some immunosuppressive effects. In the present study, cytotoxicity assays using splenic NK cells from mice treated for 28 days with PQ (at 0.2, 1, and 5 mg/kg) were performed to determine whether PQ altered the function of NK cells. Given that PQ was expected to induce an immunosuppressive effect, it was hypothesized that a gene involved in cellular metal ion homeostasis, metallothionein-1 (MT-1), could play an important role in this outcome. This belief was based on the fact thatMT1encodes a protein responsible for zinc ion homeostasis, and that a reduction in free zinc ion levels impairs NK cell function. The results showed that PQ treatments led to increased MT expression in several organs (liver, kidneys, testes) and in splenocytes, caused a reduction of both free zinc ions in sera and in free intracellular zinc, and reduced the expression of GATA-3, a zinc-finger transcription factor important for maturation and activity of T-cells and NK cells. These results provide a basis for a new molecular mechanism to describe potential immunosuppressive effects of PQin vivo. [ABSTRACT FROM PUBLISHER]

Delayed-type hypersensitivity (DTH) is a T-cell-mediated immune response that may be used for immunotoxicity testing in non-clinical species. However, in some cases DTH assays using T-dependent antigens may be confounded by the production of antibodies to the antigen. The authors have previously modified a DTH assay, initially validated in the mouse, for use in juvenile rats to assess the effect of immunosuppressive drugs on the developing rat immune system. The assay measures footpad swelling induced by subcutaneous footpad injection ofCandida albicans(C. albicans) derived-chitosan in rats previously sensitized withC. albicans. Antibodies to chitosan are not produced in this model. However, considerable inter-animal variability inherent in the footpad swelling assay can make it difficult to precisely quantify the magnitude of the immune response and inhibition by immunosuppressants, particularly if complete suppression is not observed. This report describes the development of anex vivoassay to assess DTH in rats using interferon (IFN)-γ production by splenocytes, obtained from rats sensitized withC. albicans, as the quantifiable measure of the DTH response. Adult and neonatal rats administered dexamethasone (DEX), a known immunosuppressant, exhibited immunosuppression as evidenced by a reduction inex vivoIFNγ production from splenocytes challenged withC. albicans-derived chitosan. Current data indicate that theex vivobased DTH assay is more sensitive than the conventional footpad swelling assay due to a lower background response and the ability to detect a response as early as post-natal day (PND) 12. Theex vivobased rat DTH assay offers a highly sensitive and quantitative alternative to the footpad swelling assay for the assessment of the immunotoxic potential of drugs. The increased sensitivity of theex vivoDTH assay may be useful for identifying smaller changes in response to immunotoxic drugs, as well as detecting responses earlier in animal development. [ABSTRACT FROM PUBLISHER]

Deoxynivalenol (DON) is one of the most abundant mycotoxins worldwide and mostly detected in cereals and grains. As such, DON poses a risk for many adverse health effects to human and animals. In particular, immune cells are very sensitive to DON, with the initiating step leading to toxicity being a binding to the eukaryotic 60S ribosomal subunit and induction of ribotoxic stress. The present study aimed to: (1) extend insight into the mechanism of action (MOA) of DON in immune cells; and (2) understand why immune cells are more sensitive to DON than most other cell types. Previously published microarray studies have described the effects of DON on immune cells. To build upon these findings, here, immunocytological and biochemical studies were performed using human T-lymphocyte Jurkat cells that were exposed for 3 h to 0.5 µM DON. Induction of ER stress by DON was confirmed by immunocytology demonstrating increased protein expression of two major ER stress markers ATF3 and DDIT3. T-cell activation was confirmed by induction of phosphorylation of protein kinases JNK and AKT, activation of NF- κB (p65), and increased expression of NFAT target gene NUR77; each of these are known inducers of the T-cell activation response. Induction of an oxidative stress response was also confirmed by monitoring the nuclear translocation of major oxidative stress markers NRF2 and KEAP1, as well as by changes (i.e. decreases) in cell levels of reduced glutathione. Lastly, this study showed that DON induced cleavage of caspase-3, an event known to mediate apoptosis. Taken together, these results allowed us to formulate a potential mechanism of action of DON in immune cells, i.e. binding to eukaryotic 60S ribosomal subunit → ribotoxic stress → ER stress → calcium release from the ER into cytoplasm → T-cell activation and oxidative stress → apoptosis. It is proposed that immune cells are more sensitive to DON than other cell types due to the induction of a T-cell activation response by increased intracellular calcium levels. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1) and M1 (AFM1) are mycotoxins produced by numerous Aspergillus species in pre- or post-harvest cereals and milk. AFB1 and AFM1 display a potent economic loss in livestock and also cause severe immunological problems. The aims of this study were to: evaluate a new AFB1 and AFM1-binding/degrading micro-organism for biological detoxification; examine its ability to degrade AFB1 and AFM1 in liquid medium; and evaluate its potential for in vivo preventative effects against AFB1- and AFM1-induced immunomodulation in mice. Lactobacillus plantarum MON03 (LP) isolated from Tunisian artisanal butter was found to display significant binding ability to AFB1 and AFM1 in PBS (i.e. 82% and 89%, respectively) within 24 h of incubation and able to tolerate gastric acidity, have strongly hydrophilic cells surface properties, and adhere efficacy to Caco-3 cells in vitro. The in vivo study was conducted using Balb/c mice that received by oral gavage vehicle (control), LP only (2 × 109 CFU/L, ∼2 g/kg BW), AFB1 or AFM1 alone (0.25 and 0.27 mg/kg, respectively), or AFB1 + LP or AFM1 + LP daily for 15 days. Compared to in control mice, treatments with AFB1 and AFM1 led to significantly decreased body weight gains, histopathological changes, and decrements in all hematologic and immune parameters assessed. Co-treatment with LP strongly reduced the adverse effects of each mycotoxin. In fact, the mice receiving AFB1 + LP or AFM1 + LP co-treatment displayed no significant differences in the assayed parameters as compared to the control mice. By itself, the bacteria alone had no adverse effects in the mice. From these data, it is concluded that the tested bacteria could be beneficial in biotechnology detoxification of contaminated food and feed for humans and animals. [ABSTRACT FROM AUTHOR]

A human blood cell model for immunotoxicity and genotoxicity testing was used to measure the response to polylactic-co-glycolic acid (PLGA-PEO) nanoparticle (NP) (0.12, 3, 15 and 75 μg/cm2 exposure in fresh peripheral whole blood cultures/isolated peripheral blood mononuclear cell cultures from human volunteers ( n = 9-13). PLGA-PEO NPs were not toxic up to dose 3 μg/cm2; dose of 75 μg/cm2 displays significant decrease in [3H]-thymidine incorporation into DNA of proliferating cells after 4 h (70% of control) and 48 h (84%) exposure to NPs. In non-cytotoxic concentrations, in vitro assessment of the immunotoxic effects displayed moderate but significant suppression of proliferative activity of T-lymphocytes and T-dependent B-cell response in cultures stimulated with PWM > CON A, and no changes in PHA cultures. Decrease in proliferative function was the most significant in T-cells stimulated with CD3 antigen (up to 84%). Cytotoxicity of natural killer cells was suppressed moderately (92%) but significantly in middle-dosed cultures (4 h exposure). On the other hand, in low PLGA-PEO NPs dosed cultures, significant stimulation of phagocytic activity of granulocytes (119%) > monocytes (117%) and respiratory burst of phagocytes (122%) was recorded. Genotoxicity assessment revealed no increase in the number of micronucleated binucleated cells and no induction of SBs or oxidised DNA bases in PLGA-PEO-treated cells. To conclude on immuno- and genotoxicity of PLGA-PEO NPs, more experiments with various particle size, charge and composition need to be done. [ABSTRACT FROM AUTHOR]

The toxic effects of highly carcinogenic mycotoxins, especially aflatoxins (AF), on key antigen-presenting cells, such as dendritic cells (DC), are largely unknown. To elucidate the effect of AF on DC function, porcine monocyte-derived DC (MoDC) were treated with a mixture of several AF (i.e., AFB1, AFB2, AFG1, and AFG2) and the phagocytic capacity, the membrane expression level of several DC activation markers, the T-cell proliferation-inducing capacity, and the cytokine secretion pattern were assessed. As compared to untreated MoDC, AF significantly up-regulated the expression of the co-stimulatory molecules CD25 and CD80/86. However, the phagocytic activity of MoDC was not affected by AF treatment. While the cytokine secretion pattern of AF-treated MoDC was similar to control MoDC, the T-cell proliferation-inducing capacity of MoDC was increased upon aflatoxin treatment. The results indicate that a mixture of naturally occurring AF enhances the antigen-presenting capacity of DC, which could explain the observed immunotoxicity of AF by breaking down tolerance and further emphasizes the need to reduce the admissible level of AF in agricultural commodities. [ABSTRACT FROM AUTHOR]

Aflatoxin M1 (AFM1) is a mycotoxin produced by numerous Aspergillus species in pre- or post-harvest cereals and milk. Exposure to AFM1 imparts potent economic losses in the livestock industry. Toxicologically, it also causes severe immune system problems. The aims of this study were to evaluate a new AFM1-binding/degrading microorganism for biologic detoxification, to examine its ability to degrade AFM1 in liquid medium, and to evaluate its potential for in vivo preventative effects against AFM1-induced immunotoxicity and genotoxicity in mice. Lactobacillus plantarum MON03 (LP) isolated from Tunisian artisanal butter was found to display significant binding ability to AFM1 in PBS (93%) within 24 h of incubation. Further, the LP was able to tolerate gastric acidity, bile salts, and adhere efficiently to Caco-3 cells in vitro. The in vivo study used Balb/c mice that received either vehicle (control), LP only (at 1 × 109 CFU/L, ∼1 mg/kg bw), AFM1 (100 mg/kg bw), or AFM1 + LP daily for 15 days (by gavage); two other groups received a single dose of colchicine (4 mg/kg) or mitomycin C (1 mg/kg) as positive controls for induction of micronuclei and chromosomal aberrations, respectively. The results showed that, compared to in control mice, AFM1 treatment led to significantly decreased body weight gains, and caused cytotoxic/genotoxic effects as indicated by increases in frequencies of polychromatic erythrocytes, as well as those with micronucleation (PCEMN) and chromosomal aberrations, among bone marrow cells. The concurrent administration of LP with AFM1 strongly reduced the adverse effects of AFM1 on each parameter. Mice receiving AFM1 + LP co-treatment displayed no significant differences in the assayed parameters as compared to the control mice. By itself, the bacteria caused no adverse effects. Based on the data, it is concluded that the test bacteria could potentially be beneficial in the detoxification of AFM1-contaminated foods and feeds for humans and animals. [ABSTRACT FROM AUTHOR]

Ochratoxins are fungal secondary metabolites produced during storage by fungus of the genera Aspergillus, mainly in tropical and warmer regions and by Penicillium verrucosum, in temperate and colder areas. Ochratoxin A (OTA) displays a multiple toxicity, including immunotoxicity. Until present, there have been very few, sometimes contrasting, reports on the mechanisms underlying OTA immunotoxicity. In this review, we have summarized the researches done until present concerning the interaction between OTA and the immune response. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), a known carcinogen and potent immunotoxicant in humans and animals, is dispersed throughout the environment as a result of pollution from a variety of sources. Tunisian radish ( Raphanus sativus) extract (TRE) is a known anti-oxidant and free radical scavenger that has been shown to help alleviate immune system disorders, including some induced by environmental toxicants. The present study was undertaken to investigate potential protective effects of TRE against Cd-induced immunotoxicities (and general toxicities) in situ. Cadmium chloride (at 2.5 mg CdCl2/kg BW) and TRE (5, 10, or 15 mg/kg BW) were given (alone or in combination [actually, in sequence of Cd and then TRE]) to rats daily by oral gavage for 2 weeks. Results indicated that treatment with CdCl2 alone resulted in significant decreases in plasma levels of total protein, triglycerides, creatine kinase, creatinine, IgG and IgA, T-lymphocyte sub-types (CD4+, CD3+, CD56+, and CD8+), and in thymic and hepatic indices (relative weights). In contrast, CdCl2 treatment caused significant increases in serum LDH, AST, and ALT, in the formation/release of pro-inflammatory cytokines (IL-1 and TNF α), and in the relative weights of host spleen and kidneys. Rats treated with TRE alone had no discernable changes compared to the controls with regard to all test parameters. Combined treatment of CdCl2 and TRE-at any dose-resulted in a significant improvement of all test parameters compared to those seen with Cd alone. These results illustrated (and provided further support for a continuing belief in) the beneficial effects of TRE in reducing the harmful outcomes of commonly encountered toxicants (like Cd) on the immune system and on overall host health status. [ABSTRACT FROM AUTHOR]

5-Fluorouracil (5-FU) is a widely used anti-cancer agent; however, it induces immunosuppression in patients undergoing a chemotherapy regime. The mode of action by which 5-FU induces immunosuppression is primarily via inhibition of hematopoietic growth factors. In the present study, immunoprotective effects of a semiquinone glucoside derivative (SQGD), a bacterial metabolite isolated from Bacillus sp. INM-1, were evaluated in a model of 5-FU-induced immunotoxicity in C57Bl/6 male mice. The evaluation was done by analyzing G-CSF, GM-CSF, and M-CSF expression in the serum, spleen, and bone marrow cells of the mice at different timepoints after 5-FU treatment. Mice received a single intraperitoneal injection of either 5-FU (75 mg/kg) alone, SQGD (50 mg/kg) alone, or SQGD 2 h prior to the 5-FU treatment. Control mice received saline vehicle only. The results demonstrated that 5-FU treatment significantly inhibited G-CSF, GM-CSF, and M-CSF expression in all three sites at all timepoints from 6-72 h post 5-FU. In SQGD treated mice, up-regulation of factor expression was observed in each compartment, and significantly so most often after 12 h. SQGD treatment prior to 5-FU administration to the mice significantly increased in all sites evaluated - relative to values in both control mice and 5-FU only-treated mice - G-CSF, M-CSF, and GM-CSF expression at almost every timepoint. The present findings suggest that SQGD provides protection against 5-FU-induced immunotoxicity in mice and could protect bone marrow progenitor cells against the effects of cytotoxic drugs used for treatment of cancer. The findings also suggested to us that SQGD is a potential immunomodulator and could protect hematopoiesis against toxic assault caused by anti-cancer drugs in the clinical setting. [ABSTRACT FROM AUTHOR]