The pyrethroids metabolite 3-phenoxybenzoic acid induces dopaminergic degeneration

An in silico investigation of the toxicological effects and biological activities of 3-phenoxybenzoic acid and its metabolite products

We aimed to elucidate the toxic effects and biological activities of 3-phenoxybenzoic acid (3PBA) and its metabolite products. Numerous in silico methods were used to identify the toxic effects and biological activities of 3PBA, including PASS online, molecular docking, ADMETlab 2.0, ADMESWISS, MetaTox, and molecular dynamic simulation. Ten metabolite products were identified via Phase II reactions (O-glucuronidation, O-sulfation, and methylation). All of the investigated compounds were followed by Lipinski's rule, indicating that they were stimulants or inducers of hazardous processes. Because of their high gastrointestinal absorption and ability to reach the blood-brain barrier, the studied compounds' physicochemical and pharmacokinetic properties matched existing evidence of harmful effects, including hematemesis, reproductive dysfunction, allergic dermatitis, toxic respiration, and neurotoxicity. The studied compounds have been linked to the apoptotic pathway, the reproductivity system, neuroendocrine disruptors, phospholipid-translocating ATPase inhibitors, and JAK2 expression. An O-glucuronidation metabolite product demonstrated higher binding affinity and interaction with CYP2C9, CYP3A4, caspase 3, and caspase 8 than 3PBA and other metabolite products, whereas metabolite products from methylation were predominant and more toxic. Our in silico findings partly meet the 3Rs principle by minimizing animal testing before more study is needed to identify the detrimental effects of 3PBA on other organs (liver, kidneys). Future research directions may involve experimental validation of in silico predictions, elucidation of molecular mechanisms, and exploration of therapeutic interventions. These findings contribute to our understanding of the toxicological profile of 3PBA and its metabolites, which has implications for risk assessment and regulatory decisions.

Assessing the contribution of the chemical exposome to neurodegenerative disease

Over the past few decades, numerous environmental chemicals from solvents to pesticides have been suggested to be involved in the development and progression of neurodegenerative diseases. Most of the evidence has accumulated from occupational or cohort studies in humans or laboratory research in animal models, with a range of chemicals being implicated. What has been missing is a systematic approach analogous to genome-wide association studies, which have identified dozens of genes involved in Alzheimer's disease, Parkinson's disease and other neurodegenerative diseases. Fortunately, it is now possible to study hundreds to thousands of chemical features under the exposome framework. This Perspective explores how advances in mass spectrometry make it possible to generate exposomic data to complement genomic data and thereby better understand neurodegenerative diseases.

Toxic effect and mechanism of β-cypermethrin and its chiral isomers on HTR-8/SVneo cells

Beta-cypermethrin (β-CYP) consists of four chiral isomers, acting as an environmental estrogen and causing reproductive toxicity, neurotoxicity, and dysfunctions in multiple organ systems. This study investigated the toxic effects of β-CYP, its isomers, metabolite 3-phenoxybenzoic acid (3-PBA), and 17β-estradiol (E2) on HTR-8/SVneo cells. We focused on the toxic mechanisms of β-CYP and its specific isomers. Our results showed that β-CYP and its isomers inhibit HTR-8/SVneo cell proliferation similarly to E2, with 100 μM 1S-trans-αR displaying significant toxicity after 48 h. Notably, 1S-trans-αR, 1R-trans-αS, and β-CYP were more potent in inducing apoptosis and cell cycle arrest than 1R-cis-αS and 1S-cis-αR at 48 h. AO/EB staining and flow cytometry indicated dose-dependent apoptosis in HTR-8/SVneo cells, particularly at 100 μM 1R-trans-αS. Scratch assays revealed that β-CYP and its isomers variably reduced cell migration. Receptor inhibition assays demonstrated that post-ICI 182780 treatment, which inhibits estrogen receptor α (ERα) or estrogen receptor β (ERβ), β-CYP, its isomers, and E2 reduced HTR-8/SVneo cell viability, whereas milrinone, a phosphodiesterase 3 A (PDE3A) inhibitor, increased viability. Molecular docking studies indicated a higher affinity of β-CYP, its isomers, and E2 for PDE3A than for ERα or ERβ. Consequently, β-CYP, its isomers, and E2 consistently led to decreased cell viability. Transcriptomics and RT-qPCR analyses showed differential expression in treated cells: up-regulation of Il24 and Ptgs2, and down-regulation of Myo7a and Pdgfrb, suggesting the PI3K-AKT signaling pathway as a potential route for toxicity. This study aims to provide a comprehensive evaluation of the cytotoxicity of chiral pesticides and their mechanisms.

Bifenthrin Caused Parkinson's-Like Symptoms Via Mitochondrial Autophagy and Ferroptosis Pathway Stereoselectively in Parkin-/- Mice and C57BL/6 Mice

It has been proposed that pyrethroid exposure contributes to the increasing prevalence of neurodegenerative diseases. However, the potential mechanisms remain unclear. The current study aimed to investigate the effects of the widely used pyrethroid bifenthrin on Parkinson's disease (PD) risk. Bifenthrin (1S-cis-bifenthrin, 1R-cis-bifenthrin, raceme) was administered to male Parkin-/- mice and C57BL/6 mice by oral gavage at a dose of 10 mg/kg bw/day for 28 days. Bifenthrin exposure significantly increased the time of pole climbing and decreased the period of rotarod running, indicating that bifenthrin decreased motor coordination in Parkin-/- mice, which was more evident by 1S-cis-bifenthrin. Furthermore, administration of bifenthrin induced obvious decreases in tyrosine hydroxylase (TH)+ cell count and the protein expression of TH. Increased protein of mitochondrial autophagy LC3B and p62 was observed after exposure to bifenthrin. Increased iron deposition and protein expression of iron transport transferrin (Tf) and transferrin receptor 2 (TfR2) was detected. 1S-cis-bifenthrin bound with Tf, TfR2, and GPX4 with lower binding energies than 1R-cis-bifenthrin, resulting in stronger interactions with these proteins. These results show structure-dependent PD-like effects of bifenthrin on motor activity and coordination associated with the disturbed mitochondrial autophagy and ferroptosis-related pathway. These data demonstrate that pyrethroid exposure increases the potential of Parkinson's-like symptoms via the ferroptosis pathway in Parkin-/- mice that is more pronounced than in C57BL/6 mice, providing a prospective enantioselective toxic effect of environmental neurotoxins on PD risk.

Parkinson's Disease Is Predominantly an Environmental Disease

Parkinson's disease is the world's fastest growing brain disorder, and exposure to environmental toxicants is the principal reason. In this paper, we consider alternative, but unsatisfactory, explanations for its rise, including improved diagnostic skills, aging populations, and genetic causes. We then detail three environmental toxicants that are likely among the main causes of Parkinson's disease- certain pesticides, the solvent trichloroethylene, and air pollution. All three environmental toxicants are ubiquitous, many affect mitochondrial functioning, and all can access humans via various routes, including inhalation and ingestion. We reach the hopeful conclusion that most of Parkinson's disease is thus preventable and that we can help to create a world where Parkinson's disease is increasingly rare.

The association between intermediate-term sulfur dioxide exposure and outpatient visits for Parkinson's disease: a time-series study in southwestern China

Parkinson's disease (PD) is the second most common human neurodegenerative disorder, and the pathogenesis of it remains poorly understood. Limited studies have shown that both long- and short-term exposure to air pollutants may be associated with increased risk of PD while lacking evidence on the effects of intermediate-term exposure. In this study, over-dispersed Poisson generalized additive models (GAMs) were applied to explore the association between intermediate-term sulfur dioxide (SO2) exposure and outpatient visits for PD in Chongqing, China, and further stratified analyses were performed by age and gender. A total of 39,984 PD cases from January 1, 2014, to December 31, 2019 (2191 days) were included. The association of intermediate-term SO2 exposure with outpatient visits for PD was statistically significant: per 1 μg/m3 increase of SO2 corresponded to 2.34% (95% CI: 0.88%, 3.80%) elevation in monthly PD outpatient visits at lag 0 (the concurrent month). Stratified analyses showed that the associations between SO2 and PD outpatient visits were stronger in younger (≤ 60 years) and female patients. In conclusion, intermediate-term SO2 exposure can be associated with an increased risk of PD outpatient visits. Our results highlight the importance of recognizing the role of intermediate-term SO2 exposure in the development of PD. In addition to focusing on the effects of long-term or short-term air pollutants, it is necessary to pay more attention to the health effects of intermediate-term exposure time windows of air pollutants, which will facilitate policy formulation and public health interventions for health risks.

Association of 3-Phenoxybenzoic Acid Exposure during Pregnancy with Maternal Outcomes and Newborn Anthropometric Measures: Results from the IoMum Cohort Study

The aims of this study were to characterize the exposure of pregnant women living in Portugal to 3-phenoxybenzoic acid (3-PBA) and to evaluate the association of this exposure with maternal outcomes and newborn anthropometric measures. We also aimed to compare exposure in summer with exposure in winter. Pregnant women attending ultrasound scans from April 2018 to April 2019 at a central hospital in Porto, Portugal, were invited to participate. Inclusion criteria were: gestational week between 10 and 13, confirmed fetal vitality, and a signature of informed consent. 3-PBA was measured in spot urine samples by gas chromatography with mass spectrometry (GC-MS). The median 3-PBA concentration was 0.263 (0.167; 0.458) µg/g creatinine (n = 145). 3-PBA excretion was negatively associated with maternal pre-pregnancy body mass index (BMI) (p = 0.049), and it was higher during the summer when compared to winter (p < 0.001). The frequency of fish or yogurt consumption was associated positively with 3-PBA excretion, particularly during the winter (p = 0.002 and p = 0.015, respectively), when environmental exposure is low. Moreover, 3-PBA was associated with levothyroxine use (p = 0.01), a proxy for hypothyroidism, which could be due to a putative 3-PBA-thyroid hormone antagonistic effect. 3-PBA levels were not associated with the anthropometric measures of the newborn. In conclusion, pregnant women living in Portugal are exposed to 3-PBA, particularly during summer, and this exposure may be associated with maternal clinical features.

Pesticides and the Microbiome-Gut-Brain Axis: Convergent Pathways in the Pathogenesis of Parkinson's Disease

The increasing global burden of Parkinson's disease (PD), termed the PD pandemic, is exceeding expectations related purely to population aging and is likely driven in part by lifestyle changes and environmental factors. Pesticides are well recognized risk factors for PD, supported by both epidemiological and experimental evidence, with multiple detrimental effects beyond dopaminergic neuron damage alone. The microbiome-gut-brain axis has gained much attention in recent years and is considered to be a significant contributor and driver of PD pathogenesis. In this narrative review, we first focus on how both pesticides and the microbiome may influence PD initiation and progression independently, describing pesticide-related central and peripheral neurotoxicity and microbiome-related local and systemic effects due to dysbiosis and microbial metabolites. We then depict the bidirectional interplay between pesticides and the microbiome in the context of PD, synthesizing current knowledge about pesticide-induced dysbiosis, microbiome-mediated alterations in pesticide availability, metabolism and toxicity, and complex systemic pesticide-microbiome-host interactions related to inflammatory and metabolic pathways, insulin resistance and other mechanisms. An overview of the unknowns follows, and the role of pesticide-microbiome interactions in the proposed body-/brain-first phenotypes of PD, the complexity of environmental exposures and gene-environment interactions is discussed. The final part deals with possible further steps for translation, consisting of recommendations on future pesticide use and research as well as an outline of promising preventive/therapeutic approaches targeted on strengthening or restoring a healthy gut microbiome, closing with a summary of current gaps and future perspectives in the field.