The pyriproxyfen metabolite, 4'-OH-PPF, disrupts thyroid hormone signaling in neural stem cells, modifying neurodevelopmental genes affected by ZIKA virus infection

Prenatal Exposure to Herbicide 2,4-Dichlorophenoxyacetic Acid (2,4D) Exacerbates Zika Virus Neurotoxicity In Vitro and In Vivo

Zika virus (ZIKV) infection during pregnancy can lead to a set of congenital malformations known as Congenital ZIKV syndrome (CZS), whose main feature is microcephaly. The geographic distribution of CZS in Brazil during the 2015-2017 outbreak was asymmetrical, with a higher prevalence in the Northeast and Central-West regions of the country, despite the ubiquitous distribution of the vector Aedes aegypti, indicating that environmental factors could influence ZIKV vertical transmission and/or severity. Here we investigate the involvement of the most used agrochemicals in Brazil with CZS. First, we exposed human neuroblastoma SK-N-AS cells to the 15 frequently used agrochemical molecules or derivative metabolites able to cross the blood-brain barrier. We found that a derived metabolite from a widely used herbicide in the Central-West region, 2,4-dichlorophenoxyacetic acid (2,4D), exacerbates ZIKV neurotoxic effects in vitro. We validate this observation by demonstrating vertical transmission leading to microcephaly in the offspring of immunocompetent C57BL/6J mice exposed to water contaminated with 0.025 mg/L of 2,4D. Newborn mice whose dams were exposed to 2,4D and infected with ZIKV presented a smaller brain area and cortical plate size compared to the control. Also, embryos from animals facing the co-insult of ZIKV and 2,4D exposition presented higher Caspase 3 positive cells in the cortex, fewer CTIP2+ neurons and proliferative cells at the ventricular zone, and a higher viral load. This phenotype is followed by placental alterations, such as vessel congestion, and apoptosis in the labyrinth and decidua. We also observed a mild spatial correlation between CZS prevalence and 2,4D use in Brazil's North and Central-West regions, with R2 = 0.4 and 0.46, respectively. Our results suggest that 2,4D exposition facilitates maternal vertical transmission of ZIKV, exacerbating CZS, possibly contributing to the high prevalence of this syndrome in Brazil's Central-West region compared to other regions.

Pyriproxyfen, villain or good guy? A brief review

Pyriproxyfen (PPF) acts as a juvenile growth regulator, interfering with normal metamorphosis and blocking the development of insects into adulthood. Although the World Health Organization (WHO) considers the use of PPF at a concentration of 0.01 mg/L as unlikely to pose health risks, recent studies have unveiled potential risks associated with PPF exposure to non-target organisms. Exposure to PPF disrupts insect development primarily by mimicking juvenile hormones; therefore, concerns linger over its impact on unintended species. Studies have highlighted the adverse effects of PPF on aquatic invertebrates, fish, and amphibians and revealed mortality and developmental abnormalities in non-target mosquito species exposed to PPF-treated water. Moreover, PPF may act as an endocrine disruptor, interfering with hormonal pathways crucial for growth, reproduction, and behavior in exposed organisms. Amphibians, for instance, display altered reproductive physiology and developmental abnormalities due to disruptions in endocrine signaling pathways caused by PPF. The ecological ramifications of PPF extend beyond direct toxicity to non-target species. Indirect effects include shifts in food web dynamics and ecosystem functioning. Reductions in insect populations, induced by PPF, can disrupt food availability for higher trophic levels, potentially destabilizing community structure and ecosystem equilibrium. Given mounting evidence of unintended consequences, robust risk assessment and regulatory oversight are imperative. Accurate classification of PPF by regulatory bodies is essential to balancing its role in disease control and pest management benefits with the need to safeguard non-target species and maintain ecosystem health. Future research must prioritize comprehensive assessments of PPF's ecological impact across various habitats and taxa to inform evidence-based policymaking.

Female Mice Exposed to Pyriproxyfen Since Prepuberty Showed Reproductive Impairment During Sexual Maturity and Increased Fetal Death in Their Offspring

Pyriproxyfen (PPF) is an insecticide used in agriculture, which is approved for use in drinking water tanks for human consumption. However, some studies indicate that it may act as an endocrine disruptor and affect nontarget organisms. This study aimed to evaluate the effects of PPF on reproduction and general health status in female mice exposed from pre-puberty to adulthood. In the first experiment, females were treated by gavage from postnatal day (PND) 23 to (PND) 75 and were distributed into three experimental groups: control (vehicle), PPF 0.1 mg/kg, and PPF 1 mg/kg. Female mice were assessed for the age of puberty onset, body mass, water and food consumption, and the estrous cycle. On PDN 75, a subgroup was euthanized, when vital and reproductive organs were collected and weighed. The thyroid, ovary, and uterus were evaluated for histomorphometry. The other subgroup was assessed in relation to reproductive performance and fetal parameters. In a second experiment, the uterotrophic assay was performed with juvenile females (PND 18) using doses of 0.01, 0.1, or 1 mg/kg of PPF. PPF treatment reduced thyroid mass and increased liver mass. Furthermore, there was an increase in ovarian interstitial tissue and, in the uterus, a decrease in the thickness of the endometrial stroma with reduced content of collagen fibers. There was also a reduction of 30% in pregnancy rate in the treated groups and an increase in the frequency of fetal death. This study suggests that, based on this experimental model, the insecticide may pose a reproductive risk for females chronically exposed to the substance from the pre-pubertal period until adulthood. These results raise concerns about prolonged exposure of women to the same compound.

Cellular responses to developmental exposure to pyriproxyfen in chicken model: Contrasting embryos with and without exencephaly

The insecticide pyriproxyfen (PPF), commonly used in drinking water, has already been described as a potential neurotoxic agent in non-target organisms, particularly during embryonic development. Consequently, exposure to PPF can lead to congenital anomalies in the central nervous system. Therefore, understanding the impact of this insecticide on developing neural cells is a relevant concern that requires attention. Thus, this study aimed to investigate the effects of PPF on the proliferation, differentiation, migration, and cell death of neural cells by comparing embryos that develop exencephaly with normal embryos, after exposure to this insecticide. Chicken embryos, used as a study model, were exposed to concentrations of 0.01 and 10 mg/L PPF on embryonic day E1 and analyzed on embryonic day E10. Exposed embryos received 50 μL of PPF diluted in vehicle solution, and control embryos received exclusively 50 μL of vehicle solution. After exposure, embryos were categorized into control embryos, embryos with exencephaly exposed to PPF, and embryos without exencephaly exposed to PPF. The results showed that although the impact was differentiated in the forebrain and midbrain, both brain vesicles were affected by PPF exposure, and this was observed in embryos with and without exencephaly. The most evident changes observed in embryos with exencephaly were DNA damage accompanied by alterations in cell proliferation, increased apoptosis, and reduced neural differentiation and migration. Embryos without exencephaly showed DNA damage and reduced cell proliferation and migration. These cellular events directly interfered with the density and thickness of neural cell layers. Together, these results suggest that PPF exposure causes cellular damage during neurogenesis, regardless of whether embryos display or do not display external normal morphology. This nuanced understanding provides important insights into the neurotoxicity of PPF and its potential effects on inherent events in neurogenesis.

The role of neuropeptide prothoracicotropic hormone (PTTH) - Torso in pyriproxyfen-induced larval-pupal abnormal metamorphosis in silkworms

The neuropeptide prothoracicotropic hormone (PTTH) plays a key role in regulating ecdysone synthesis and promoting insect metamorphosis. Pyriproxyfen is a juvenile hormone analogue. We previously reported that pyriproxyfen disrupts ecdysone secretion and inhibits larval-pupal metamorphosis in silkworms. However, the specific molecular mechanisms by which pyriproxyfen interferes with ecdysone signaling remain to be elucidated. Herein, the RNA-seq analysis on the ecdysone-secretion organ prothoracic gland (PG) was conducted following pyriproxyfen exposure. A total of 3774 differentially expressed genes (DEGs) were identified, with 1667 up-regulated and 2107 down-regulated. KEGG analysis showed that DEGs were enriched in the MAPK signaling pathway, a conserved pathway activated by PTTH binding to Torso, which regulates the ecdysone synthesis. qRT-PCR results indicated a significant up-regulation in PTTH transcription level, while the transcription levels of torso and downstream MAPK pathway genes, Ras2, Raf and ERK, were down-regulated 24 h post-pyriproxyfen treatment. Consistent with these transcriptional changes, PTTH titers in the brain also increased following pyriproxyfen treatment. These results suggest that pyriproxyfen induces abnormal metamorphosis in silkworms by impairing PTTH-Torso signaling. This study enhances our understanding of the molecular mechanisms of pyriproxyfen-induced larval-pupal abnormal metamorphosis in silkworms, and also provides insights for developing detoxification strategies for juvenile hormone analog pesticides to non-target organisms.

A review of the influence of environmental pollutants (microplastics, pesticides, antibiotics, air pollutants, viruses, bacteria) on animal viruses

Microorganisms, especially viruses, cause disease in both humans and animals. Environmental chemical pollutants including microplastics, pesticides, antibiotics sand air pollutants arisen from human activities affect both animal and human health. This review assesses the impact of chemical and biological contaminants (virus and bacteria) on viruses including its life cycle, survival, mutations, loads and titers, shedding, transmission, infection, re-assortment, interference, abundance, viral transfer between cells, and the susceptibility of the host to viruses. It summarizes the sources of environmental contaminants, interactions between contaminants and viruses, and methods used to mitigate such interactions. Overall, this review provides a perspective of environmentally co-occurring contaminants on animal viruses that would be useful for future research on virus-animal-human-ecosystem harmony studies to safeguard human and animal health.

Thyroid Dysfunction Induced by Fungicide Famoxadone Exposure Contributes to Nonalcoholic Fatty Liver Disease in Male Mice: In Vivo, In Vitro, and In Silico Studies

Thyroid dysfunction has become a serious public health problem, which is considered a trigger of nonalcoholic fatty liver disease (NAFLD). Pesticide exposure could contribute to thyroid dysfunction and NAFLD, but the relationship between these factors remains unclear. In this study, the effects of subchronic famoxadone exposure on thyroid and liver at no observed adverse effect level (NOEL) related concentrations were investigated using in vivo, in vitro, and in silico models. Famoxadone caused hepatic steatosis, lipid metabolism disorder, and liver oxidative stress and induced NAFLD in male mice. The suppression of hepatic fatty acid β-oxidation was the key factor of NAFLD, which was highly associated with hypothalamic-pituitary-thyroid (HPT) axis hormones disorder. Famoxadone disrupted thyroid hormone biosynthesis by causing thyroid follicle aberrations and abnormal HPT axis-related gene expression. In vitro studies confirmed that famoxadone inhibited the transport of thyroxine (T4) into hepatocytes and the conversion of T4 to triiodothyronine (T3). In silico studies verified that famoxadone interfered with the binding of thyroid hormones to proteins mediating thyroid hormone transport, conversion, and activation. This study comprehensively reported the association between NAFLD and thyroid dysfunction caused by famoxadone, providing new perspectives for the health risk evaluation of pesticides with a similar structure in mammals.

Two Sides of The Same Coin: Normal and Tumoral Stem Cells, The Relevance of In Vitro Models and Therapeutic Approaches: The Experience with Zika Virus in Nervous System Development and Glioblastoma Treatment

Neural stem cells (NSCs) were described for the first time more than two decades ago for their ability to differentiate into all neural cell lineages. The isolation of NSCs from adults and embryos was carried out by various laboratories and in different species, from mice to humans. Similarly, no more than two decades ago, cancer stem cells were described. Cancer stem cells, previously identified in hematological malignancies, have now been isolated from several solid tumors (breast, brain, and gastrointestinal compartment). Though the origin of these cells is still unknown, there is a wide consensus about their role in tumor onset, propagation and, in particular, resistance to treatments. Normal and neoplastic neural stem cells share common characteristics, and can thus be considered as two sides of the same coin. This is particularly true in the case of the Zika virus (ZIKV), which has been described as an inhibitor of neural development by specifically targeting NSCs. This understanding prompted us and other groups to evaluate ZIKV action in glioblastoma stem cells (GSCs). The results indicate an oncolytic activity of this virus vs. GSCs, opening potentially new possibilities in glioblastoma treatment.

Cross-species applicability of an adverse outcome pathway network for thyroid hormone system disruption

Thyroid hormone system disrupting compounds are considered potential threats for human and environmental health. Multiple adverse outcome pathways (AOPs) for thyroid hormone system disruption (THSD) are being developed in different taxa. Combining these AOPs results in a cross-species AOP network for THSD which may provide an evidence-based foundation for extrapolating THSD data across vertebrate species and bridging the gap between human and environmental health. This review aimed to advance the description of the taxonomic domain of applicability (tDOA) in the network to improve its utility for cross-species extrapolation. We focused on the molecular initiating events (MIEs) and adverse outcomes (AOs) and evaluated both their plausible domain of applicability (taxa they are likely applicable to) and empirical domain of applicability (where evidence for applicability to various taxa exists) in a THSD context. The evaluation showed that all MIEs in the AOP network are applicable to mammals. With some exceptions, there was evidence of structural conservation across vertebrate taxa and especially for fish and amphibians, and to a lesser extent for birds, empirical evidence was found. Current evidence supports the applicability of impaired neurodevelopment, neurosensory development (eg, vision) and reproduction across vertebrate taxa. The results of this tDOA evaluation are summarized in a conceptual AOP network that helps prioritize (parts of) AOPs for a more detailed evaluation. In conclusion, this review advances the tDOA description of an existing THSD AOP network and serves as a catalog summarizing plausible and empirical evidence on which future cross-species AOP development and tDOA assessment could build.

Identifying potential thyroid hormone disrupting effects among diphenyl ether structure pesticides and their metabolites in silico

The environmental and dietary pesticide exposures can cause thyroid hormones (THs) disorders, which are associated with the high incidence of thyroid diseases worldwide. The structures of diphenyl ether pesticides and their metabolites are very similar to the structure of THs. Based on this, in silico molecular simulation approaches were used to predict, screen, evaluate and identify the binding interactions of 98 diphenyl ether structure pesticides and their metabolites (DEPMs) with 10 THs related proteins in the study. The research results indicated that these DEPMs such as fluoroglycofen (FOG), rafoxanide, diclofop, ethoxyfen and difenopenten were considered to have the greater potentials to interfere with the related proteins of THs biosynthesis, blood transport, receptor binding and metabolism. And FOG can interact with thyroid hormone receptor beta (TRβ) to form non-bond interactions. Furthermore, the results of molecular dynamics simulations showed that there were strong and stable interactions between FOG and TRβ. These results suggested that the herbicide FOG was likely to disturb THs nuclear receptor. And benzene rings and hydrophobic groups might be the characteristic chemical functional groups for DEPMs to disrupt TRβ. The relevant results of this study can be used to provide references for environmental toxicology evaluation, food safety risk assessment, and formulation and revision of pesticides and their metabolites residue limits in agricultural products and food.

Climate change, women's health, and the role of obstetricians and gynecologists in leadership

Climate change is one of the major global health threats to the world's population. It is brought on by global warming due in large part to increasing levels of greenhouse gases resulting from human activity, including burning fossil fuels (carbon dioxide), animal husbandry (methane from manure), industry emissions (ozone, nitrogen oxides, sulfur dioxide), vehicle/factory exhaust, and chlorofluorocarbon aerosols that trap extra heat in the earth's atmosphere. Resulting extremes of weather give rise to wildfires, air pollution, changes in ecology, and floods. These in turn result in displacement of populations, family disruption, violence, and major impacts on water quality and availability, food security, public health and economic infrastructures, and limited abilities for civil society to maintain citizen safety. Climate change also has direct impacts on human health and well-being. Particularly vulnerable populations are affected, including women, pregnant women, children, the disabled, and the elderly, who comprise the majority of the poor globally. Additionally, the effects of climate change disproportionally affect disadvantaged communities, including low income and communities of color, and lower-income countries that are at highest risk of adverse impacts when disasters occur due to inequitable distribution of resources and their socioeconomic status. The climate crisis is tilting the risk balance unfavorably for women's sexual and reproductive health and rights as well as newborn and child health. Obstetrician/gynecologists have the unique opportunity to raise awareness, educate, and advocate for mitigation strategies to reverse climate change affecting our patients and their families. This article puts climate change in the context of women's reproductive health as a public health issue, a social justice issue, a human rights issue, an economic issue, a political issue, and a gender issue that needs our attention now for the health and well-being of this and future generations. FIGO joins a broad coalition of international researchers and the medical community in stating that the current climate crisis presents an imminent health risk to pregnant people, developing fetuses, and reproductive health, and recognizing that we need society-wide solutions, government policies, and global cooperation to address and reduce contributors, including fossil fuel production, to climate change.