Immunotoxicity of pyrethroid metabolites in an in vitro model

Studies on immunotoxicity induced by emamectin benzoate in zebrafish embryos based on metabolomics

Emamectin benzoate (EMB) is an insecticide for the control of agricultural lepidoptera pests, and also an anti-parasiticide for the control of exoparasites in aquaculture industry. Increased studies suggest that EMB could cause toxicity to non-targeted organisms, but its immunotoxicity to human remains unclear. In this study, zebrafish were used to investigate the immunotoxic effects induced by environmentally relevant doses of EMB. We observed that EMB exposure led to embryo mortality and delayed hatching, as well as increased malformations. Meanwhile, zebrafish exposed to EMB exhibited a significant decrease in the number of neutrophils and macrophages. In addition, untargeted metabolomics approach was developed to elucidate the mechanism of EMB-induced immunotoxicity. We found that a total of 10 shared biomarkers were identified in response to EMB exposure. Furthermore, pathway analysis identified glycerophospholipid metabolism was the most relevant pathway. Within this pathway, it was observed abnormal increases in glycerol 3-phosphate content, which could be attributed to the increased expression of GK5 and decreased expression of GPAT3. Our study provided novel and robust perspectives, which showed that EMB exposure to zebrafish embryos could cause metabolic disturbances that adversely affected development and immune system.

Investigation on the immunotoxicity induced by Emamectin benzoate on THP-1 macrophages based on metabolomics analysis

Emamectin benzoate (EMB) is an insecticide extensively used in agricultural area. Assessing the toxic effects of EMB in mammals or humans and its endogenous metabolites alteration are the appropriate means of evaluating its risks to human health. In the study, THP-1 macrophage, a human immune model, was applied to investigate the immunotoxicity of EMB. A global metabolomics approach was developed to analyze metabolic perturbation on macrophages and discover the potential biomarkers of EMB-induced immunotoxicity. The results indicated that EMB could inhibit immune functions of macrophages. Based on metabolomics analysis, our results illustrated that EMB caused significant alterations in metabolic profiles on macrophages. 22 biomarkers associated with immune response were screened by pattern recognition and multivariate statistical analysis. Furthermore, pathway analysis identified purine metabolism was the most relevant pathway in the metabolic process and the abnormal conversion of AMP to xanthosine regulated by NT5E might be a potential mechanism of immunotoxicity induced by EMB. Our study provides important insights for understanding and underlying mechanism of immunotoxicity exposed to EMB.

Microbial elimination of pyrethroids: specific strains and involved enzymes

Pyrethroids, which are synthetic organic insecticides, are widely used in agriculture and households to resist pests and control disease transmission. However, pyrethroids have inevitably caused environmental pollution, leading to concerns for food safety and human health. Bioremediation has emerged as one of the most promising methods to eliminate pyrethroids compounds. Pyrethroid-degrading microorganisms and the relevant enzymes have shown an efficient ability in degrading pyrethroids by hydrolyzing the ester linkage. In this review, a wide variety of pyrethroid-degrading strains were presented and classified from different sources, such as wastewater, soils, and oceans. In addition, the recombinant expression, enzyme identification, and molecular modification of these microbial pyrethroid-degrading enzymes were also compared and discussed in detail. Moreover, the potential applications of pyrethroid-degrading enzymes, including immobilization and biodegradation towards a series of pyrethroids, were also presented. All of the positive results obtained from this review could be a good guideline for the other research in this field. KEY POINTS: • Distribution of pyrethroid-degrading strains in different sources was summarized. • Enzymatic properties including pH, temperature, and substrate specificity were compared. • Promising molecular modification and immobilization of hydrolases were present.

Unraveling the metabolic effects of benzophenone-3 on the endosymbiotic dinoflagellate Cladocopium goreaui

As a well-known pseudo-persistent environmental pollutant, oxybenzone (BP-3) and its related organic ultraviolet (UV) filters have been verified to directly contribute to the increasing mortality rate of coral reefs. Previous studies have revealed the potential role of symbiotic Symbiodiniaceae in protecting corals from the toxic effects of UV filters. However, the detailed protection mechanism(s) have not been explained. Here, the impacts of BP-3 on the symbiotic Symbiodiniaceae Cladocopium goreaui were explored. C. goreaui cells exhibited distinct cell growth at different BP-3 doses, with increasing growth at the lower concentration (2 mg L^-1) and rapid death at a higher concentration (20 mg L^-1). Furthermore, C. goreaui cells showed a significant BP-3 uptake at the lower BP-3 concentration. BP-3 absorbing cells exhibited elevated photosynthetic efficiency, and decreased cellular carbon and nitrogen contents. Besides, the derivatives of BP-3 and aromatic amino acid metabolism highly responded to BP-3 absorption and biodegradation. Our physiological and metabolic results reveal that the symbiotic Symbiodiniaceae could resist the toxicity of a range of BP-3 through promoting cell division, photosynthesis, and reprogramming amino acid metabolism. This study provides novel insights into the influences of organic UV filters to coral reef ecosystems, which urgently needs increasing attention and management.

β-cyclodextrin improve the tolerant of freshwater algal Spiny Scenedesmus to chiral drugs venlafaxine and its metabolite

This study based on the freshwater algae Spiny scenedesmus (S. scenedesmus) with tolerance to venlafaxine aiming to investigate algae removal abilities. Here presented for the first time to evaluate the effect of β-cyclodextrin (β-CD) on reduce toxicity and enhance removal ability of venlafaxine and O-desmethylvenlafaxine to S. scenedesmus. Based on dose-response results, the toxicity of R-venlafaxine (EC₅₀ = 6.81 mg·L ^-1) and R-O-desmethylvenlafaxine (EC₅₀ = 3.36 mg·L ^-1) to algae were more than two times than those in the presence of β-CD treatment (10.64 mg L ^-1 for R-venlafaxine and 11.87 mg L ^-1 for R-O-desmethylvenlafaxine). The significant differences were observed between S-venlafaxine (11.07 mg L ^-1) and S-O-desmethylvenlafaxine (10.24 mg L ^-1), which were more toxic than R-forms. The half-lives of R- and S-venlafaxine were 0.8 d and 0.5 d in the presence of β-CD, which were obvious shorter than those in alone treatments. In addition, our experiments not only demonstrated that β-CD performed particularly well for removal of venlafaxine and O-desmethylvenlafaxine, it significantly reduces the toxicity of venlafaxine to alga. These results highlight advantages of β-CD relevant to chiral drugs removal and protection of aquatic organisms, which may have a better application for environmental and ecological safety in future.

Gut Microbiota: A Key Factor in the Host Health Effects Induced by Pesticide Exposure?

In the past few decades, a large number of pesticides have been widely used for plant protection. Pesticides may enter non-target organisms through multiple ways and bring potential health risks. There is a dense and diverse microbial community in the intestines of mammals, which is called the gut microbiota. The gut microbiota and its metabolites play vital roles in maintaining the health of the host. Interestingly, many studies have shown that exposure to multiple pesticides could affect the gut microbiota of the host. However, the roles of gut microbiota and its related metabolites in the host health effects induced by pesticide exposure of non-target organisms need further study. We reviewed the relationships between pesticide exposure and host health effects as well as between the gut microbiota and host health effects. Importantly, we reviewed the latest research on the gut microbiota and its metabolites in the host health effects induced by pesticide exposure.

An epigenome-wide association study of ambient pyrethroid pesticide exposures in California's central valley

BACKGROUND

Pyrethroid pesticide use is increasing worldwide, although the full extent of associated health effects is unknown. An epigenome-wide association study (EWAS) with exploratory pathway analysis may help identify potential pyrethroid-related health effects.

METHODS

We performed an exploratory EWAS of chronic ambient pyrethroid exposure using control participants' blood in the Parkinson's Environment and Genes Study in the Central Valley of California (N = 237). We estimated associations of living and working near agricultural pyrethroid pesticide applications in the past 5 years (binary) with site-specific differential methylation, and used a false discovery rate (FDR) cut off of 0.05 for significance. We controlled for age, sex, education, cell count, and an ancestral marker for Hispanic ethnicity. We normalized methylation values for Type I/II probe bias using Beta-Mixture Quantile (BMIQ) normalization, filtered out cross-reactive probes, and evaluated for remaining bias with Surrogate Variable Analysis (SVA). We also evaluated the effects of controlling for cell count and normalizing for Type I/II probe bias by comparing changes in effect estimates and p-values for the top hits across BMIQ and GenomeStudio normalization methods, and controlling for cell count. To facilitate broader interpretation, we annotated genes to the CpG sites and performed gene set overrepresentation analysis, using genes annotated to CpG sites that were associated with pyrethroids at a raw p < 0.05, and controlling for background representation of CpG sites on the chip. We did this for both a biological process context (Gene Ontology terms) using missMethyl, and a disease set context using WebGestalt. For these gene set overrepresentation analyses we also used an FDR cut off of 0.05 for significance of gene sets.

RESULTS

After controlling for cell count and applying BMIQ normalization, 4 CpG sites were differentially methylated in relation to pyrethroid exposures. When using GenomeStudio's Illumina normalization, 415 CpG sites were differentially methylated, including all four identified with the BMIQ method. In the gene set overrepresentation analyses, we identified 6 GO terms using BMIQ normalization, and 76 using Illumina normalization, including the 6 identified by BMIQ. For disease sets, we identified signals for Alzheimer's disease, leukemia and several other cancers, diabetes, birth defects, and other diseases, for both normalization methods. We identified minimal changes in effect estimates after controlling for cell count, and controlling for cell count generally weakened p-values. BMIQ normalization, however, resulted in different beta coefficients and weakened p-values.

CONCLUSIONS

Chronic ambient pyrethroid exposure is associated with differential methylation at CpG sites that annotate to a wide variety of disease states and biological mechanisms that align with prior research. However, this EWAS also implicates several novel diseases for future investigation, and highlights the relative importance of different background normalization methods in identifying associations.

New Insights in the Endocrine Disrupting Effects of Three Primary Metabolites of Organophosphate Flame Retardants

Despite the ubiquity of organophosphate flame retardants (OPFRs) metabolites in the biota, the endocrine disrupting potency has not been well examined. Herein, we chose three primary metabolites of OPFRs (BCIPP, BDCIPP, and DPHP) to investigate their potential endocrine disrupting effects by in vitro, in vivo, and in silico assays. Three metabolites were agonistic to rat estrogenic receptor alpha (ERα) and antagonists to human mineralocorticoid receptor (MR). BCIPP exerted endocrine disrupting effect contrasting to the negative response of its parental compound. It also poses the strongest binding capacity to ERα among the tested compounds. Both BCIPP and BDCIPP upregulated the genes encoded for estrogenic synthesis enzymes in H295R cells, including 17βHSD and CYP19. All three compounds stimulated the transcription of CYP11B1, whereas BCIPP and DPHP also triggered CYP11B2, encoding for corticoid production. BDCIPP inhibits genes for progesterone synthesis including CYP11A1, STAR, and 3-βHSD. The induction of mortality and low hatchability of zebrafish embryo were ranked as BCIPP ≥ BDCIPP > DPHP. All compounds lead to malformation of zebrafish larvae. Both of the hypothalamic-pituitary-adrenocortical and hypothalamic-pituitary-gonadal axes were disrupted, with the highest impact by BCIPP. Altogether, the data clarified OPFRs metabolites may produce comparable or even higher endocrine disrupting effects than OPFRs.

Co-metabolic enzymes and pathways of 3-phenoxybenzoic acid degradation by Aspergillus oryzae M-4

As an intermediate metabolite of pyrethroids, 3-phenoxybenzoic acid (3-PBA) is more toxic than its parent compounds and has been detected in milk, soil, and human urine. 3-PBA can be metabolized through microbial degradation, but the microbial co-metabolic enzymes and pathways involved in 3-PBA degradation are unclear. This study investigated the enzymes types and possible pathways in the co-metabolic degradation of 3-PBA by Aspergillus oryzae M-4. The enzymes involved in co-metabolic degradation of 3-PBA and its intermediate metabolites were induced, and existed extracellularly and intracellularly except the catechol-degrading enzyme. Inhibitors and inducers of these oxidases were used to examine the enzymes required for co-metabolic degradation of 3-PBA and its intermediate metabolites. 3-PBA is hydroxylated to produce 3-hydroxy-5-phenoxy benzoic acid through the catalytic actions of lignin peroxidase (LiP). Phenol and gallic acid, the metabolites of 3-PBA, are produced via cleavage of an ether bond under the catalytic actions of cytochrome P450 (CYP450) and LiP. Phenol can be converted to catechol by LiP; catechol and gallic acid are cleaved to form long-chain olefin acid or olefin aldehyde by dioxygenase and LiP. In corn flour, some of these enzyme activators such as FeCl₃, 4-cumaric acid, veratryl alcohol and sodium periodate appeared to improve 3-PBA degradation. The results provide a reliable pathway and characteristics for co-metabolic microbial degradation of 3-PBA in food and the environment.

Early life exposure of zebrafish (Danio rerio) to synthetic pyrethroids and their metabolites: a comparison of phenotypic and behavioral indicators and gene expression involved in the HPT axis and innate immune system

Ecotoxicological studies have revealed the association between synthetic pyrethroid (SP) exposure and aquatic toxicity in fish; however, research on the toxic effects of SP metabolites is still limited. In this study, the toxicity of two SPs (permethrin (PM) and β-cypermethrin (β-CP)) and their three metabolites (3-phenoxybenzoic alcohol (PBCOH), 3-phenoxybenzaldehyde (PBCHO), and 3-phenoxybenzoic acid (PBCOOH)) towards zebrafish embryos and larvae was evaluated. Both SPs and their metabolites exhibited significant developmental toxicities, caused abnormal vascular development, and changed locomotor activities in larvae. The alteration of gene expression involved in the thyroid system and the innate immune system indicated that SPs and their three metabolites have the potency to induce thyroid disruption and trigger an immune response. The results from the present study suggest that SP metabolites could induce multiple toxic responses similar to parent compounds, and their toxicity should be considered for improving the understanding of environmental risks of SPs.

β-Cypermethrin and its metabolite 3-phenoxybenzoic acid exhibit immunotoxicity in murine macrophages

β-Cypermethrin (β-CYP), one of most important pyrethroids, is widely used to control insects, and has been detected in organisms, including human. Pyrethroids have been shown to pose neurotoxicity, hepatotoxicity, endocrine disruption and reproductive risks in mammals. However, research in immunotoxicity of pyrethroids, especially their metabolites, is limited. A common metabolite of pyrethroids is 3-phenoxybenzoic acid (3-PBA) in mammals. Thus, in this study, we evaluated the immunotoxicity of β-CYP and 3-PBA in mouse macrophages, RAW 264.7 cells. MTT assays showed that both β-CYP and 3-PBA reduced cell viability in a concentration- and time-dependent manner. Flow cytometry with Annexin-V/PI staining demonstrated that both β-CYP and 3-PBA induced RAW 264.7 cell apoptosis. Furthermore, our results also showed that N-acetylcysteine partially blocked β-CYP- and 3-PBA-induced cytotoxicity and apoptosis. Intrinsic apoptotic pathway was stimulated by both β-CYP and 3-PBA exposure. In addition, we found that β-CYP and 3-PBA inhibited mRNA levels of pro-inflammatory cytokines with or without LPS stimulation. Phagocytosis assay showed that both β-CYP and 3-PBA inhibited phagocytic ability of macrophages. Moreover, it was also found that both β-CYP and 3-PBA increased reactive oxygen species (ROS) levels in RAW 264.7 cells. Accordingly, both β-CYP and 3-PBA were found to regulate the mRNA levels of oxidative stress-related genes in RAW 264.7 cells. Taken together, the results obtained in this study demonstrated that β-CYP and 3-PBA may have immunotoxic effect on macrophages and that elevated ROS may underlie the mechanism. The present study will help to understand the health risks caused by β-CYP and other pyrethroids.

Cis-bifenthrin causes immunotoxicity in murine macrophages

Synthetic pyrethroids (SPs) are commonly used insecticides that have been detected in mammals, including humans, indicating a potential threat to human health. Bifenthrin (BF), as well as other pyrethroids, has been shown to possess neurotoxic, reproductive, hepatotoxic and nephrotoxic potential in mammals. However, studies regarding the immunotoxicity of BF and its mechanism are limited. In this study, we aim to exam the immunotoxicity of cis-BF on the murine macrophage cell line, RAW 264.7. MTT assay results demonstrated that cis-BF exposure induced apoptosis in RAW 264.7 cells in a concentration-dependent manner. We found that the expression of p53 and caspase-3 was up-regulated, while the expression of Bcl-2 was down-regulated during cis-BF-induced apoptosis. In addition, we also found that cis-BF exposure caused oxidative stress in RAW 264.7 cells in a dose-dependent manner. Interestingly, cis-BF exposure was found to inhibit the increase in transcription levels of IL-1β, IL-6 and TNF-α responding to LPS stimulation. We also found that the induced increase in IFN-β mRNA levels upon Sendai virus infection was blocked with cis-BF exposure. Finally, we found that cis-BF exposure increased ROS levels and dysregulated mRNA levels of oxidative stress-related genes in RAW 264.7 cells. The present study elucidates the immunotoxicity effect of cis-BF on macrophages and its possible underlying mechanism. The results from this study support the necessity to evaluate immune dysfunction in the risk assessment of cis-BF exposure.

The identification of the metabolites of chlorothalonil in zebrafish (Danio rerio) and their embryo toxicity and endocrine effects at environmentally relevant levels

Chlorothalonil is a broad spectrum fungicide with high annual production and environmental contamination. Despite its high consumption, studies regarding the potential ecological risks of chlorothalonil, especially its metabolites, to aquatic organisms are still limited. In this study, we selected the zebrafish (Danio rerio) as the in vivo model and first identified the metabolite (4-hydroxychlorothalonil) of chlorothalonil in zebrafish by tandem quadrupole/orthogonal-acceleration time-of-flight (Q-TOF). Then, the in vivo and in vitro models were applied to comprehensively estimate the embryo toxicity and potential endocrine effect of chlorothalonil and 4-hydroxychlorothalonil. The data from zebrafish embryo toxicity showed that the lowest observed effect concentrations of both chlorothalonil and 4-hydroxychlorothalonil were 50 μg/L after 96 h of exposure. The mortality rate of the 4-hydroxychlorothalonil was 2.6-fold higher than that of the parent compound at the concentration of 50 μg/L. Dual-luciferase reporter gene assays indicated that both chlorothalonil and 4-hydroxychlorothalonil exerted estrogen receptor α (ERα) agonist activity with REC₂₀ values of 2.4 × 10^-8 M and 3.6 × 10^-8 M, respectively. However, only 4-hydroxychlorothalonil exhibited both thyroid receptor β (TRβ) agonistic and antagonistic activities. Lastly, we employed molecular docking to predict the binding affinity of chlorothalonil and 4-hydroxychlorothalonil with ERα or TRβ. The results revealed that the potential endocrine effect of chlorothalonil and 4-hydroxychlorothaloni might be attributed to the different binding affinities with the receptors. In conclusion, our studies revealed that 4-hydroxychlorothalonil exhibited potent endocrine-disrupting effects compared to its parent compound, chlorothalonil. The results provided here remind us that the assessment of the potential ecological and health risks of the metabolites of fungicides in addition to their parent compounds should arouse great concerns.

A comprehensive review of pesticides and the immune dysregulation: mechanisms, evidence and consequences

Nowadays, in many communities, there is a growing concern about possible adverse effects of pesticides on human health. Reports indicate that during environmental or occupational exposure, pesticides can exert some intense adverse effects on human health through transient or permanent alteration of the immune system. There is evidence on the relation between pesticide-induced immune alteration and prevalence of diseases associated with alterations of the immune response. In the present study, direct immunotoxicity, endocrine disruption and antigenicity have been introduced as the main mechanisms working with pesticides-induced immune dysregulation. Moreover, the evidence on the relationship between pesticide exposure, dysregulation of the immune system and predisposition to different types of psychiatric disorders, cancers, allergies, autoimmune and infectious diseases are criticized.

Endocrine disrupting potential of fipronil and its metabolite in reporter gene assays

There is a rising concern about the ecological safety and potential health risks caused by pesticides that are commonly present in the environment. Previous studies have shown that metabolites of pesticides sometimes possess more potent endocrine activity than the parent compounds. However very little efforts had been devoted to evaluate the environmental risks of pesticide metabolites. In the present study, we evaluated the agonistic and antagonistic activities of fipronil and its metabolite, fipronil sulfone, and compared by in vitro reporter gene assays using CHO-K1 cells. For estrogenic and antiestrogenic activities, both fipronil and fipronil sulfone showed no agonistic activities but exhibited the similarly antagonistic activities via estrogen receptor α (ERα), with the RIC20 of 6.4 × 10(-7)M and 9.8 × 10(-7)M, respectively. In the thyroid hormone receptor (TR) assay, only fipronil sulfone showed anti-thyroid hormone activity with the RIC20 of 8.2 × 10(-7)M. Furthermore, molecular docking was employed to support the results in TR assay with lower MolDock score for fipronil sulfone. Data provided here suggested that it is of great significance to study the endocrine-disrupting effects of pesticide's metabolites, especially those with persistence in environment and high toxicity to non-targeted organisms.

Prevention of cyclophosphamide-induced hemorrhagic cystitis by resveratrol: a comparative experimental study with mesna

PURPOSE

Hemorrhagic cystitis (HC) is the most common urotoxic side effect of cyclophosphamide (CP). The aim of this study was to compare the classical efficacy of mesna (2-mercaptoethane sulfonate sodium) with three different doses of resveratrol (RES) on cyclophosphamide-induced HC in rats.

METHODS

Forty-six male Sprague-Dawley rats were divided into six groups. Group 1 served as a negative control (sham). Five groups received a single dose of cyclophosphamide (150 mg/kg) intraperitoneally at the same time. Groups 2, 3, 4, 5, and 6 received only CP, CP + 20 mg/kg RES, CP + 40 mg/kg RES, CP + 80 mg/kg RES, and CP + classical protocol of three doses of mesna (30 mg/kg three times), respectively. Antioxidants, cytokines, and malondialdehyde levels were measured in all groups. In addition, histopathological alterations in tissues were examined.

RESULTS

CP administration induced severe HC with marked edema, hemorrhage, and inflammation in group 2. RES 20 mg/kg showed meaningful protection against bladder damage compared to the control group. It was seen that RES 40 mg/kg gave weaker protection but RES 80 mg/kg was not found to be effective.

CONCLUSION

In conclusion, marked bladder protection was found in 20 and 40 mg/kg RES applications compared to the control group, but this protection was weaker than with mesna.

Cytokine patterns in greenhouse workers occupationally exposed to α-cypermethrin: an observational study

The immunotoxicity of the synthetic pyrethroid α-cypermethrin (αCYP) was assessed in 30 occupationally exposed greenhouse workers and 30 non-exposed controls by comparing plasma levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12p70, TNF-α, TNF-β and INF-γ. Urinary 3-phenoxybenzoic acid was used as an exposure biomarker. Exposed workers showed neither clinical signs of immunosuppression nor alterations in total leukocytes or leukocyte subpopulations, whereas significant differences (p<0.05) were found for IL-12p70 and highly significant differences (p<0.001) for INF-γ, IL-2 and IL-8, which are involved in antitumor immunity and response to infection. Proinflammatory cytokines IL-2, IL-8, IL-12p70 and IFN-γ play a significant role against infection and cancer. We report the first data on the ability of αCYP to reduce proinflammatory cytokine levels in an exposed healthy human population. Findings support the hypothesis that pyrethroid exposure may reduce host defenses against infection and cancer, particularly in subjects with impaired immune capacity.

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.

Pesticide induced immunotoxicity in humans: a comprehensive review of the existing evidence

The immune system can be the target of many chemicals, with potentially severe adverse effects on the host's health. In Western countries pesticides, together with new and modified patterns of exposure to chemicals, have been implicated in the increasing prevalence of diseases associated with alterations of the immune response, such as hypersensitivity reactions, certain autoimmune diseases and cancers. Xenobiotics may initiate, facilitate or exacerbate pathological immune processes, resulting in immunotoxicity by induction of mutations in genes coding for immunoregulatory factors, modifying immune tolerance and activation pathways. The purpose of this article is to update the evidence of pesticide immunotoxicity. Even if experimental data as well as sporadic human studies indicate that some pesticides can affect the immune system, overall, existing epidemiological studies are inadequate to raise conclusions on the immunotoxic risk associated to pesticide exposure. The available studies on the effects of pesticides on human immune system have several limitations including poor indication on exposure levels, multiple chemical exposures, heterogeneity of the approach, and difficulty in giving a prognostic significance to the slight changes often observed. Further studies are necessary, and they should be preferably carried out through comparison of pre and post-exposure findings in the same group of subjects with a matched control group. Attempt should be made to define the prognostic significance of slight changes often observed. Animal and in vitro studies are also important and necessary to scientifically support epidemiological evidences on pesticide-induced immunotoxicity.