Glyphosate-based herbicides: Evidence of immune-endocrine alteration

Glyphosate (G) is the active ingredient of the most widely used herbicide products. It targets the enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS), which lacks in humans, suggesting to confer a low mammalian toxicity to G-based herbicides (GBHs). Despite this, the use of G is currently under intense debate. Many studies indicating its hazard and toxicity on non-target organisms are emerging, and associations between GBHs and immune-endocrine disturbances have been described. This review aims to investigate, based on recent epidemiological studies and studies performed in vitro and in vivo in animals, the possible association between GBHs and immune-endocrine alterations. Published data suggest that GBHs have endocrine disrupting potentiality targeting sex and thyroid hormones, although its relevance for humans will require further investigations. Evidence of immunotoxicity are limited compared to those on endocrine effects, but overall highlight possible noxious effects, including lung inflammation and rhinitis. An attractive hypothesis could be the one that connects microbiota dysbiosis with possible immune-endocrine outcomes. Indeed, several intestinal microorganisms express the enzyme EPSPS and, studies are emerging that highlight a possible G-induced dysbiosis. Considering the wide use of GBHs in agriculture, further studies investigating their noxious effects at levels relevant for human exposure should be performed. A critical analysis of emerging evidence of G toxicity is required to better characterize its safety profile. In addition, attention should be paid to the differences between G alone and its formulations, which, containing substances able to increase G absorption, may present a different toxicity profile.

Triazophos and its metabolite diethyl phosphate have different effects on endocrine hormones and gut health in rats

Organophosphorus pesticide (OP) residues present in food can be metabolized into diethylphosphate (DEP) in vivo. Epidemiological studies of OPs have usually focused on these metabolites, while animal studies mainly assessed the OPs. Here, we compared the health risks of a frequently detected OP, triazophos (TAP), and its major metabolite, DEP, in rats. Levels of serum lipids and, sex hormones were measured using immunoassay kits. Gut hormones and inflammatory cytokines were assessed using a multiplexing kit, and the gut microbiota was evaluated by 16S rRNA gene sequencing. After a 24-week exposure period, both TAP and DEP significantly decreased serum levels of triglycerides, cholesterol, low-density lipoprotein cholesterol, and IL-6 (p < 0.05). However, DEP exposure had a stronger effect on serum estradiol (p < 0.05) than TAP, whereas only TAP inhibited the secretion of gut hormones. Both TAP and DEP enriched the pathogenic genera Oscillibacter, Peptococcus and Paraprevotella in the gut, and TAP also enriched enteritis-related genera Roseburia and Oscillibacter, which may affect the secretion of gut hormones. These findings indicate that the use of dialkyl phosphates as markers of OPs to examine the correlations of OP exposure with diseases may only provide partial information, especially for diseases related to gut health and the endocrine system.

Toxicology and Microbiota: How Do Pesticides Influence Gut Microbiota? A Review

In recent years, new targets have been included between the health outcomes induced by pesticide exposure. The gastrointestinal tract is a key physical and biological barrier and it represents a primary site of exposure to toxic agents. Recently, the intestinal microbiota has emerged as a notable factor regulating pesticides’ toxicity. However, the specific mechanisms related to this interaction are not well known. In this review, we discuss the influence of pesticide exposure on the gut microbiota, discussing the factors influencing gut microbial diversity, and we summarize the updated literature. In conclusion, more studies are needed to clarify the host–microbial relationship concerning pesticide exposure and to define new prevention interventions, such as the identification of biomarkers of mucosal barrier function.

Perturbation of gut microbiota plays an important role in micro/nanoplastics-induced gut barrier dysfunction

The widespread occurrence of microplastics (MPLs) and nanoplastics (NPLs), collectively abbreviated as M/NPLs, has markedly affected the ecosystem and has become a global threat to human health. Multiple investigations have shown that the chronic ingestion of M/NPLs negatively affects gut barrier function but the mechanism remains unclear. Herein, this research has investigated the toxic effects of pristine polystyrene (PS) M/NPLs, negatively charged carboxylated polystyrene M/NPLs (PS-COOH) and positively charged aminated polystyrene M/NPLs (PS-NH2) of two sizes (70 nm and 5 μm in diameter) in mice. Gavage of these PS M/NPLs for 28 days caused obvious injuries to the gut tract, leading to the decreased expression of tight junction proteins. The toxicity of the M/NPLs was ranked as PS-NH2 > PS-COOH > pristine PS. Oral administration of these M/NPLs resulted in marked gut microbiota dysbiosis. The M/NPLs-enriched genera generally contained opportunistic pathogens which are accompanied by a deteriorated intestinal barrier function, while most M/NPLs-decreased bacteria were beneficial microbes with known tight junction-promoting functions, implicating an important indirect toxic effect of gut microbiota dysbiosis in M/NPLs-induced gut barrier dysfunction. In conclusion, this research highlights the importance of gut microbiota in the toxicity of M/NPLs exposure on gut barrier function, providing novel insights into the adverse effects of M/NPLs exposure on human health.

Impacts of radiation exposure on the bacterial and fungal microbiome of small mammals in the Chernobyl Exclusion Zone

Environmental impacts of the 1986 Chernobyl Nuclear Power Plant accident are much debated, but the effects of radiation on host microbiomes have received little attention to date. We present the first analysis of small mammal gut microbiomes from the Chernobyl Exclusion Zone in relation to total absorbed dose rate, including both caecum and faeces samples. We provide novel evidence that host species determines fungal community composition, and that associations between microbiome (both bacterial and fungal) communities and radiation exposure vary between host species. Using ambient versus total weighted absorbed dose rates in analyses produced different results, with the latter more robust for interpreting microbiome changes at the individual level. We found considerable variation between results for faecal and gut samples of bank voles, suggesting faecal samples are not an accurate indicator of gut composition. Associations between radiation exposure and microbiome composition of gut samples were not robust against geographical variation, although we identified families of bacteria (Lachnospiraceae and Muribaculaceae) and fungi (Steccherinaceae and Strophariaceae) in the guts of bank voles that may serve as biomarkers of radiation exposure. Further studies considering a range of small mammal species are needed to establish the robustness of these potential biomarkers.

Chronic oral exposure to pesticides and their consequences on metabolic regulation: role of the microbiota

Pesticides have long been used in agriculture and household treatments. Pesticide residues can be found in biological samples for both the agriculture workers through direct exposure but also to the general population by indirect exposure. There is also evidence of pesticide contamination in utero and trans-generational impacts. Whilst acute exposure to pesticides has long been associated with endocrine perturbations, chronic exposure with low doses also increases the prevalence of metabolic disorders such as obesity or type 2 diabetes. Dysmetabolism is a low-grade inflammation disorder and as such the microbiota plays a role in its etiology. It is therefore important to fully understand the role of microbiota on the genesis of subsequent health effects. The digestive tract and mostly microbiota are the first organs of contact after oral exposure. The objective of this review is thus to better understand mechanisms that link pesticide exposure, dysmetabolism and microbiota. One of the key outcomes on the microbiota is the reduced Bacteroidetes and increased Firmicutes phyla, reflecting both pesticide exposure and risk factors of dysmetabolism. Other bacterial genders and metabolic activities are also involved. As for most pathologies impacting microbiota (including inflammatory disorders), the role of prebiotics can be suggested as a prevention strategy and some preliminary evidence reinforces this axis.

Subchronic exposure to concentrated ambient PM2.5 perturbs gut and lung microbiota as well as metabolic profiles in mice

Exposure to ambient fine particular matter (PM2.5) are linked to an increased risk of metabolic disorders, leading to enhanced rate of many diseases, such as inflammatory bowel disease (IBD), cardiovascular diseases, and pulmonary diseases; nevertheless, the underlying mechanisms remain poorly understood. In this study, BALB/c mice were exposed to filtered air (FA) or concentrated ambient PM2.5 (CPM) for 2 months using a versatile aerosol concentration enrichment system(VACES). We found subchronic CPM exposure caused significant lung and intestinal damage, as well as systemic inflammatory reactions. In addition, serum and BALFs (bronchoalveolar lavage fluids) metabolites involved in many metabolic pathways in the CPM exposed mice were markedly disrupted upon PM2.5 exposure. Five metabolites (glutamate, glutamine, formate, pyruvate and lactate) with excellent discriminatory power (AUC = 1, p < 0.001) were identified to predict PM2.5 exposure related toxicities. Furthermore, subchronic exposure to CPM not only significantly decreased the richness and composition of the gut microbiota, but also the lung microbiota. Strong associations were found between several gut and lung bacterial flora changes and systemic metabolic abnormalities. Our study showed exposure to ambient PM2.5 not only caused dysbiosis in the gut and lung, but also significant systemic and local metabolic alterations. Alterations in gut and lung microbiota were strongly correlated with metabolic abnormalities. Our study suggests potential roles of gut and lung microbiota in PM2.5 caused metabolic disorders.

Gut microbiota of animals living in polluted environments are a potential resource of anticancer molecules

Cancer is a prominent cause of morbidity and mortality worldwide, in spite of advances in therapeutic interventions and supportive care. In 2018 alone, there were 18·1 million new cancer cases and 9·6 million deaths indicating the need for novel anticancer agents. Plant-based products have often been linked with protective effects against communicable and non-communicable diseases. Recently, we have shown that animals such as crocodiles thrive in polluted environments and are often exposed to carcinogenic agents, but still benefit from prolonged lifespan. The protective mechanisms shielding them from cancer could be attributed to the immune system, and/or it is possible that their gut microbiota produce anticancer molecules. In support, several lines of evidence suggest that gut microbiota plays a critical role in the physiology of its host. Here, we reviewed the available literature to assess whether the gut microbiota of animals thriving in polluted environment possess anticancer molecules.

Can probiotics win the battle against environmental endocrine disruptors?

Compounds that have negative effects on the endocrine system are called endocrine disrupting compounds (EDCs). There are several different types of compounds, with several different usage areas in the environment, which can be classified as EDCs. These chemicals have a wide range of negative health effects in organisms, depending on their target hormone system. EDCs are among the most popular topics of scientific research, as they are widely used and organisms are frequently exposed to these chemicals. There are various exposure routes for EDCs, such as oral, inhalation and dermal exposure. Parabens, phenolic compounds, phthalates, and pesticides are the most common EDCs. Nowadays, intestinal microorganism distribution, probiotics, and food supplements that regulate these microorganisms and their protective effects against various harmful chemicals attract attention. For this reason, many studies have been carried out in this field and certain diet schemes have been created according to the results of these studies. In fact, probiotics are preferred in order to reduce and eliminate the negative effects of harmful chemicals and to ensure that the organism reacts strongly in these conditions. In this review, we will focus on EDCs, their health effects and positive effects of probiotics on EDCs exposure conditions.

Synthetic gut microbiome: Advances and challenges

An exponential rise in studies regarding the association among human gut microbial communities, human health, and diseases is currently attracting the attention of researchers to focus on human gut microbiome research. However, even with the ever-growing number of studies on the human gut microbiome, translation into improved health is progressing slowly. This hampering is due to the complexities of the human gut microbiome, which is composed of >1,000 species of microorganisms, such as bacteria, archaea, viruses, and fungi. To overcome this complexity, it is necessary to reduce the gut microbiome, which can help simplify experimental variables to an extent, such that they can be deliberately manipulated and controlled. Reconstruction of synthetic or established gut microbial communities would make it easier to understand the structure, stability, and functional activities of the complex microbial community of the human gut. Here, we provide an overview of the developments and challenges of the synthetic human gut microbiome, and propose the incorporation of multi-omics and mathematical methods in a better synthetic gut ecosystem design, for easy translation of microbiome information to therapies.

The fungicide thiram perturbs gut microbiota community and causes lipid metabolism disorder in chickens

Fungicide thiram, a representative dithiocarbamate pesticide can cause potential health hazards to humans and animal health due to the residues in various agricultural products. However, the effects of thiram on lipid metabolism by perturbing gut microbiota of chickens are not clear. Our study was aimed to explore the protective of polysaccharide extracted from Morinda officinalis (MOP) on acute thiram-exposed chickens, and to analyze the association between alteration of gut microbiota and lipid metabolism. Three hundred chicks are fed with a normal diet, thiram-treated diet (100 mg/kg), and a thiram-treated diet supplemented with 250, 500, or 1000 mg/kg MOP was used in this study, respectively. The results showed that thiram exposure prominently elevated liver index, changed liver function by histopathological examination and serum biochemistry diagnoses, and increased blood lipid parameters. Meanwhile, the expression level of some key genes in hepatic lipid metabolism dysregulated significantly in the thiram-exposed chickens. Furthermore, 16S rRNA gene sequencing indicated that thiram exposure can significantly alter the richness, diversity, and composition of the broiler fecal microbiota, and the relative abundance of Firmicutes and Proteobacteria was also affected at the phylum level. In addition, some microbial populations including Lactobacillus, Ruminococcus, Oscillospira, Blautia, and Butyricicoccus significantly decreased at the genus level, whereas the Klebsiella was opposite. Correlation analysis further revealed a significant association between microorganisms and lipid metabolism-related parameters. Optimistically, 500 mg/kg MOP can alleviate the damage of thiram in the gut and liver. Together, these data suggest that thiram exposure causes the imbalance of the gut microbiota and hepatic lipid metabolism disorder in chickens.

The protective effects of melatonin on survival, immune response, digestive enzymes activities and intestinal microbiota diversity in Chinese mitten crab (Eriocheir sinensis) exposed to glyphosate

Glyphosate is one of the most widely used pesticides, which can cause toxicity to aquatic animals. In this study, the survival rate, immune response, digestive enzyme activities, and the intestinal microbiota diversity of Chinese mitten crab (Eriocheir sinensis) were evaluated after 14 days of exposure to glyphosate (48.945 mg/L from 50% 96 h LC50 value) and melatonin feeding (80 mg/kg). The results showed that MT significantly improved the survival rate, antibacterial capacity of E. sinensis (P < 0.05). After exposure to glyphosate, the expression of Hsp60, Hsp70 and Hsp90 in cranial ganglia and thoracic ganglia was decreased significantly, but MT significantly raised the expression of these proteins (P < 0.05). Glyphosate significantly decreased lipase activity compared with the control group (P < 0.05), while melatonin significantly increased the lipase, amylase and trypsin activities (P < 0.05). Melatonin significantly increased the Chao1 and Shannon index and the relative abundance of Proteobacteria and Bacteroidetes (P < 0.05). This study shows that melatonin has a protective effect on the glyphosate exposed E. sinensis.

Gut microbiome alterations induced by tributyltin exposure are associated with increased body weight, impaired glucose and insulin homeostasis and endocrine disruption in mice

Tributyltin (TBT), an organotin compound once widely used in agriculture and industry, has been reported to induce obesity and endocrine disruption. Gut microbiota has a strong connection with the host's physiology. Nevertheless, the influences of TBT exposure on gut microbiota and whether TBT-influenced gut microbiota is related to TBT-induced toxicity remain unclear. To fill these gaps, ICR (CD-1) mice were respectively exposed to TBT at NOEL (L-TBT) and tenfold NOEL (H-TBT) daily by gavage for 8 weeks in the current study. The results showed that TBT exposure significantly increased body weight as well as epididymal fat, and led to adipocyte hypertrophy, dyslipidemia and impaired glucose and insulin homeostasis in mice. Additionally, TBT exposure significantly decreased the levels of T4, T3 and testosterone in serum. Also of note, TBT exposure changed gut microbiota composition mainly by decreasing Bacteroidetes and increasing Firmicutes proportions. To confirm the role of gut microbiota in TBT-induced overweight and hormonal disorders, fecal microbiota transplantation was performed and the mice receiving gut microbiota from H-TBT mice had similar phenotypes with their donor mice including significant body weight and epididymal fat gain, glucose and insulin dysbiosis and hormonal disorders. These results suggested that gut microbiome altered by TBT exposure was involved in the TBT-induced increased body weight, impaired glucose and insulin homeostasis and endocrine disruption in mice, providing significant evidence and a novel perspective for better understanding the mechanism by which TBT induces toxicity.

Sub-chronic carbendazim exposure induces hepatic glycolipid metabolism disorder accompanied by gut microbiota dysbiosis in adult zebrafish (Daino rerio)

Carbendazim (CBZ) as a broad spectrum fungicide is widely used in the whole world to contorl plant diseases. With the application of CBZ in the agriculture, it has been detected in vegetables and fruits. Nowadays, it even has been detected in the watercourse and indoor dust. However, the toxic effects of CBZ on aquatic organisms have received limited attention. In this study, male adult zebrafish were exposed at 0, 30 and 100 μg/L CBZ for 21 days to assess its effects on hepatic glycolipid metabolism. After exposure, the body weight and length decreased, but the condition factor increased significantly. Some hepatic biochemical parameters including the levels of glucose, pyruvate, low density lipoprotein (LDL) and triglyceride (TG) decreased significantly in the liver of zebrafish after exposure with CBZ. Two transaminases alanine transaminase (ALT) and aspartate transaminase (AST) also increased significantly, indicating that subchronic CBZ exposure influenced the liver function. Moreover, the relative mRNA levels of some key genes related to the glycolysis and lipid metabolism in the liver also changed significantly. Furthermore, the transcriptome analysis showed that the carbon metabolism, lipid metabolism and detoxification metabolism were also affected in the liver of CBZ exposed zebrafish. Interestingly, we also found the amounts of the Firmicutes, Bacteroidetes, Actinobacteria, α-Proteobacteria, γ-Proteobacteria and Verrucomicrobia at phylum level significantly decreased in the gut. Sequencing V3-V4 region of 16S rRNA also demonstrated gut microbiota composition changed significantly according to weighted UniFrac distance analysis. Consequently, subchronic CBZ exposure induced hepatic metabolic disorder accompanied by gut microbiota dysbiosis in adult male zebrafish.

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.

Global trends in pesticides: A looming threat and viable alternatives

Pesticides are widely used chemical compounds in agriculture to destroy insects, pests and weeds. In modern era, they form an indispensable part of agricultural and health practices. Globally, nearly 3 billion kg of pesticides are used every year with a budget of ~40 billion USD. This extensive usage has increased the crop yield as well as led to significant reduction in harvest losses and thereby, enhanced food availability. On the other hand, indiscriminate usage of these chemicals has led to several environmental implications and caused adverse effects on human health. Epidemiological evidences have revealed the harmful effects of pesticides exposure on various organs including liver, brain, lungs and colon. Recent investigations have shown that pesticides can also lead to fatal consequences such as cancer among individuals. These chemicals enter ecosystem, thus hampering the sensitive environmental equilibrium through bio-accumulation. Due to their non-biodegradable nature, they can persist in nature for years and are regarded as potent biohazard. Worldwide, very few surveillance methods have been considered, which can bring awareness among the individuals, therefore the present review is an attempt to delineate consequences induced by various types of pesticide exposure on the environment. Further, the prospective of biopesticides use could facilitate the increase of crop production without compromising human health.

Pesticides-induced energy metabolic disorders

Metabolic disorders have become a heavy burden on society. Recently, through excessive use, pesticides have been found to be present in environmental matrixes and sometimes even accumulate in humans or other mammals through the food chain, which then causes health concerns. Evidence has indicated that pesticides have the potential to induce energy metabolic disorders by disturbing the physical process of energy absorption in the intestine and energy storage in the liver, adipose tissue and skeletal muscle in humans or other mammals. In addition, the homeostasis of energy regulation by the pancreas and immune cells is also affected by pesticides. These pesticide-induced disruptions ultimately cause abnormal levels of blood glucose and lipids, which in turn induce the development of related metabolic diseases, including overweight, underweight, insulin resistance and even diabetes. In this review, the results of previous studies focused on the induction of metabolic disorders by pesticides are summarized. We hope that this work will facilitate the discovery of a potential strategy for the treatment of diseases caused by pesticides.

Endocrine Disruptors in Food: Impact on Gut Microbiota and Metabolic Diseases

Endocrine disruptors (EDCs) have been associated with the increased incidence of metabolic disorders. In this work, we conducted a systematic review of the literature in order to identify the current knowledge of the interactions between EDCs in food, the gut microbiota, and metabolic disorders in order to shed light on this complex triad. Exposure to EDCs induces a series of changes including microbial dysbiosis and the induction of xenobiotic pathways and associated genes, enzymes, and metabolites involved in EDC metabolism. The products and by-products released following the microbial metabolism of EDCs can be taken up by the host; therefore, changes in the composition of the microbiota and in the production of microbial metabolites could have a major impact on host metabolism and the development of diseases. The remediation of EDC-induced changes in the gut microbiota might represent an alternative course for the treatment and prevention of metabolic diseases.

Polystyrene microplastic exposure disturbs hepatic glycolipid metabolism at the physiological, biochemical, and transcriptomic levels in adult zebrafish

Microplastics (MPs), which are new types of environmental pollutants, have recently received widespread attention worldwide. MPs can accumulate in the bodies of animals and in plants, and they can also enter the human body through the food chain. However, knowledge of the effects of MPs on the health of animals is still limited. In this experiment, adult male zebrafish were exposed to 20 or 100 μg/L of 5 μm polystyrene MP for 21 days in an attempt to determine the hepatic effects related to glycolipid metabolism at the biochemical and transcriptomic levels. It was found that body weight and condition factor decreased significantly in zebrafish after exposure to 20 and 100 μg/L polystyrene MP for 21 days. The transcription levels of major genes related to glycolipid metabolism decreased significantly in the liver. Correspondingly, the levels of major biochemical parameters, including Glu, pyruvic acid, α-ketoglutaric acid and IDH, were also decreased in the livers of exposed zebrafish, especially those in the 100 μg/L polystyrene MP-treated group. Moreover, the data on the hepatic transcriptome also confirmed that some genes related to fatty acid metabolism, amino acid metabolism and carbon metabolism tended to be decreased in the livers of exposed zebrafish. Taken together, our data confirmed that polystyrene PS-MP can induce hepatic glycolipid metabolism disorder at the physiological, biochemical, and transcriptomic levels in adult zebrafish after 21 days of exposure.

A novel and sensitive ratiometric fluorescence assay for carbendazim based on N-doped carbon quantum dots and gold nanocluster nanohybrid

A novel fluorescence "turn on" ratiometric fluorescent sensor was employed to determine carbendazim. The sensing process was achieved through the strong fluorescence resonance energy transfer (FRET) between nitrogen doped carbon quantum dots (N-CQDs) and gold nanocluster (AuNCs). The photoluminescence intensity of N-CQDs can be deactivated by AuNCs through FRET effect and recovered by the addition of carbendazim. The ratiometric detection of carbendazim is achieved by recording the photoluminescence and second-order Rayleigh scattering (SRS) signal of N-CQDs/AuNCs system. With the introduction of carbendazim to the sensing platform resulted in the photoluminescence and SRS signal of N-CQDS/AuNCs enhancing. UV-vis absorption, Zeta potential and fluorescence lifetime analyses indicate that the fluorescence turn on process can be attributed to the aggregation of AuNCs breaks the FRET process and increases SRS intensity. N-CQDs/AuNCs probe present a good sensitivity and selectivity for carbendazim detection, with two linear response ranges (1-100 μM, 150-1000 μM), low detection limit of 0.83 μM and 37.25 μM. Furthermore, real sample analyses indicate that the as-presented sensor has potentials in carbendazim determination in real sample analyses.

Gut Microbiome Toxicity: Connecting the Environment and Gut Microbiome-Associated Diseases

The human gut microbiome can be easily disturbed upon exposure to a range of toxic environmental agents. Environmentally induced perturbation in the gut microbiome is strongly associated with human disease risk. Functional gut microbiome alterations that may adversely influence human health is an increasingly appreciated mechanism by which environmental chemicals exert their toxic effects. In this review, we define the functional damage driven by environmental exposure in the gut microbiome as gut microbiome toxicity. The establishment of gut microbiome toxicity links the toxic effects of various environmental agents and microbiota-associated diseases, calling for more comprehensive toxicity evaluation with extended consideration of gut microbiome toxicity.

Different effects of exposure to penconazole and its enantiomers on hepatic glycolipid metabolism of male mice

(±) - PEN is a chiral fungicide widely used to control powdery mildew in agriculture. Currently, only a few studies have investigated the toxic effects of (±) - penconazole ((±) - PEN) on non-target organisms, and whether (±) - PEN from the enantiomeric level have toxic effects remains unclear. In this study, we systematically evaluated the effects of exposure to (±) - PEN, (+) - PEN and (-) - PEN on liver function in mice. Biochemical and histopathological analyses showed that exposure to (±) - PEN and (-) - PEN led to significant liver damage and inflammation. However, exposure to (+) - PEN treatment did not cause no adverse effects on liver function and inflammation. ¹H-NMR-based metabolomics revealed that exposure to (±) - PEN, (+) - PEN and (-) - PEN led to the animals developing liver metabolic disorder that was caused by changes in glycolipid metabolism. Quantitative analysis of genes regulating glycolipid metabolism revealed that expression of gluconeogenesis and glycolytic pathway genes were altered in individuals exposed to (±) - PEN, (+) - PEN and (-) - PEN. We also found that (±) - PEN, (+) - PEN and (-) - PEN have different effects on lipid metabolism of the liver. Exposure to (±) - PEN and (-) - PEN resulted in significant accumulation of lipids by regulating fatty acid synthesis, triglyceride synthesis, and fatty acid β oxidation pathways. In summary, we found different toxicological effects in individuals exposed to (±) - PEN, (+) - PEN and (-) - PEN. The results of this study are important for assessing the potential health risks of (±) - PEN.

Insights into a Possible Mechanism Underlying the Connection of Carbendazim-Induced Lipid Metabolism Disorder and Gut Microbiota Dysbiosis in Mice

Carbendazim (CBZ), a systemic, broad-spectrum benzimidazole fungicide, is widely used to control fungal diseases and has been regarded as an endocrine disruptor that causes mammalian toxicity in different target organs. Here, we discovered that chronic administrations of CBZ at 0.2, 1, and 5 mg/kg body weight for 14 weeks not only changed the composition of gut microbiota but also induced significant increases in body, liver, and epididymal fat weight in mice. At the biochemical level, the serum triglyceride (TG) and glucose levels also increased after CBZ exposure. Moreover, the level of serum lipoprotein lipase (LPL), which plays an important role in fatty acid release from TG, was decreased significantly. For gut microbiota, 16S rRNA gene sequencing and real-time qPCR revealed that CBZ exposure significantly perturbed the mice gut microbiome, and gas chromatography found that the production of short-chain fatty acids were altered. Moreover, CBZ exposure increased the absorption of exogenous TG in the mice intestine and inhibited the TG consumption, eventually leading the serum triglyceride to maintain higher levels. The increase of lipid absorption in the intestine direct caused hyperlipidemia and the multi-tissue inflammatory response. In response to the rise of lipid in blood, the body maintains the balance of lipid metabolism in mice by reducing lipid synthesis in the liver and increasing lipid storage in the fat. Chronic CBZ exposure induced the gut microbiota dysbiosis and disturbed lipid metabolism, which promoted the intestinal absorption of excess triglyceride and caused multiple tissue inflammatory responses in mice.

The effects of benzo[a]pyrene on the composition of gut microbiota and the gut health of the juvenile sea cucumber Apostichopus japonicus Selenka

The gut microbiota is essential for health and physiological functions in the host organism. However, the toxicological evaluation of environmental pollutants on the gut microbiota is still insufficient. In the present study, the juvenile sea cucumber Apostichopus japonicus was exposed for 14 days to Benzo[a]pyrene (BaP), which is a model polycyclic aromatic hydrocarbon (PAH), at four different concentrations (0, 0.5, 5, and 25 μg/L). We analyzed the intestinal microbial community of A. japonicas using 16S rRNA gene amplicon sequencing. Our results demonstrate that BaP exposure caused alterations to the microbiome community composition in sea cucumbers. At the phylum level, Planctomycetes were significantly more abundant in BaP exposure groups at 14 d compared with the control group, and the abundance of Proteobacteria and Bacteroidetes increased while the abundance of Firmicutes decreased following BaP exposure. At the genus level, multiple beneficial and autochthonous genera declined in the BaP treatment groups compared to the control, including Lactococcus, Bacillus, Lactobacillus, Enterococcus, Leuconostoc and Weissella; however, a bloom of alkane-degrading bacteria was found in BaP-exposed guts and included Lutibacter, Pseudoalteromonas, Polaribacter, Rhodopirellula and Blastopirellula. Furthermore, histological morphology, enzymatic activity and gene expression analysis revealed that BaP exposure also negatively impacted gut structure and function and presented as inflammation or atrophy, oxidative stress and immune suppression in sea cucumber intestines. Collectively, these findings provide insights into the toxic effects of BaP exposure on A. japonicas associated with intestinal microbiota and health.

Maternal Polystyrene Microplastic Exposure during Gestation and Lactation Altered Metabolic Homeostasis in the Dams and Their F1 and F2 Offspring

Microplastics (MPs) are considered as a pollutant of marine environments and have become a global environmental problem in recent years. A number of studies have demonstrated that MPs can enter the human food chain, and MPs have even been detected in human stools. Therefore, there is increasing concern about the potential risks of MPs to human and animal health. Here, we investigated maternal polystyrene MPs exposure during gestation and lactation and evaluated the potential effects on dams and the F1 (both PND 42 and 280) and F2 (PND 42) generations. The results of transcriptome and 16S rRNA sequencing indicated that MPs caused the metabolic disorder in maternal MPs associated with gut microbiota dysbiosis and gut barrier dysfunction. Simultaneously, maternal MPs exposure also had the intergenerational effects and even caused long-term metabolic consequences in the F1 and F2 generations. In addition, in F1 (PND 42), the composition of gut microbiota did not change significantly, while the hepatic transcriptome and serum metabolite changes showed the potential risk in metabolic disorder. Then, the potential of hepatic lipid accumulation was observed in adult F1 mice (PND 280), especially in the female mice. Our results demonstrated that maternal MPs exposure during gestation and lactation increases the risk of metabolic disorder, and these results provide new insight into the potential long-term hazards of MPs.

Effects of the glyphosate-based herbicide roundup on the survival, immune response, digestive activities and gut microbiota of the Chinese mitten crab, Eriocheir sinensis

Glyphosate is one of the most widely used pesticides in the world and can be transported easily by surface runoff, air, and rivers, potentially affecting aquaculture. In this study, the survival rate, intestinal and hepatopancreatic immune and digestive functions, and the intestinal microbial diversity of Chinese mitten crab (Eriocheir sinensis) were evaluated after 7 days of exposure to glyphosate (48.945 mg/L from 1/2 96-h LC50 value). The results showed that glyphosate significantly reduced the survival rate of E. sinensis. After exposure to glyphosate, the totoal antioxidant capacity (T-AOC) in the midgut and hindgut of E. sinensis was significantly decreased, and malondialdehyde (MDA) content in the midgut was significantly increased (P < 0.05). After glyphosate exposure, the activities of digestive enzymes (including lipase and amylase) in the intestinal tract were significantly decreased and trypsin was significantly increased, while three enzymes in the hepatopancreas were significantly increased (P < 0.05). Using high-throughput sequencing analysis of the gut microbiota, the results showed that glyphosate significantly decreased the diversity of E. sinensis gut microbiota, while significantly increasing the taxonomic richness of Bacteroidetes and Proteobacteria (P < 0.05). This study suggested that these bacteria may be involved in glyphosate effects on survival by regulation of immune and digestive function.

Bioaccumulation in the gut and liver causes gut barrier dysfunction and hepatic metabolism disorder in mice after exposure to low doses of OBS

The compound sodium ρ-perfluorous nonenoxybenzene sulfonate (OBS), a new kind of perfluoroalkyl and polyfluoroalkyl compound, is a surfactant for increasing oil production, and it has been widely detected in various organisms. Because of its wide use, OBS is detectable in the environment. However, knowledge about the biological toxicity of OBS to animals is very limited. Here, male mice were exposed to 0, 0.1, 1 or 10 μg/L of OBS for 6 weeks via drinking water. It was demonstrated that OBS was highly bioaccumulated both in the liver and gut in the mice after low doses of OBS exposure. Curiously, a low dose of OBS exposure also caused gut barrier dysfunction by decreasing mucus secretion and altering Ionic transport in the gut via the CFTR pathway. In addition, liver function was influenced by OBS at both the histopathological and physiological levels. Hepatic transcriptomics and metabolomics analysis showed a total of 1157 genes, and multiple metabolites changed significantly in the livers of mice exposed to low-dose OBS for 6 weeks. The functions of these changed genes and metabolites are tightly related to glycolysis, fatty acid synthesis, fatty acid transport, and β-oxidation. All these results indicate that the liver and gut are important target tissues for OBS exposure. Importantly, it is possible that high levels of bioaccumulation of OBS in the gut and liver might directly cause gut barrier dysfunction and hepatic metabolism disorder in mice.

Gut microbiota: An underestimated and unintended recipient for pesticide-induced toxicity

Pesticide pollution residues have become increasingly common health hazards over the last several decades because of the wide use of pesticides. The gastrointestinal tract is the first physical and biological barrier to contaminated food and is therefore the first exposure site. Interestingly, a number of studies have shown that the gut microbiota plays a key role in the toxicity of pesticides and has a profound relationship with environmental animal and human health. For instance, intake of the pesticide of chlorpyrifos can promote obesity and insulin resistance through influencing gut and gut microbiota of mice. In this review, we discussed the possible effects of different kinds of widely used pesticides on the gut microbiota in different experimental models and analyzed their possible subsequent effects on the health of the host. More and more studies indicated that the gut microbiota of animals played a very important role in pesticides-induced toxicity, suggesting that gut micriobita was also the unintended recipient of pesticides. We hope that more attention can focus on the relationship between pesticides, gut microbiota and environmental health risk assessment in near future.

Lactobacillus plantarum TW1-1 Alleviates Diethylhexylphthalate-Induced Testicular Damage in Mice by Modulating Gut Microbiota and Decreasing Inflammation

Diethylhexylphthalate (DEHP), acting as an endocrine disruptor, disturbed reproductive health. Here, we evaluated the effects of Lactobacillus plantarum TW1-1 (L. plantarum TW1-1) on DEHP-induced testicular damage in adult male mice. Results showed that oral supplementation of L. plantarum TW1-1 significantly increased the serum testosterone concentration, enhanced the semen quality, and attenuated gonad development defects in DEHP-exposed mice. L. plantarum TW1-1 also alleviated DEHP-induced oxidative stress and inflammatory responses by decreasing the mRNA expression and serum protein concentration of different inflammatory factors [tumor necrosis factor-α, interleukin (IL)-1β and IL-6]. Furthermore, L. plantarum TW1-1 significantly reduced DEHP-induced intestinal hyper-permeability and the increase in the serum lipopolysaccharide level. Gut microbiota diversity analysis revealed that L. plantarum TW1-1 shifted the DEHP-disrupted gut microbiota to that of the control mice. At phylum level, L. plantarum TW1-1 reversed DEHP-induced Bacteroidetes increase and Firmicutes decrease, and restored Deferribacteres in DEHP-exposed mice. Spearman's correlation analysis showed that Bacteroidetes, Deferribacteres, and Firmicutes were associated with DEHP-induced testicular damage. In addition, the ratio of Firmicutes to Bacteroidetes (Firm/Bac ratio) significantly decreased from 0.28 (control group) to 0.13 (DEHP-exposed group), which was restored by L. plantarum TW1-1 treatment. Correlation analysis showed that the Firm/Bac ratio was negatively correlated with testicular damage and inflammation. These findings suggest that L. plantarum TW1-1 prevents DEHP-induced testicular damage via modulating gut microbiota and decreasing inflammation.

Interaction between microplastics and microorganism as well as gut microbiota: A consideration on environmental animal and human health

Microplastics (MPs) has gradually become a global environmental pollution problem and may harm human and animal health. In recent years, a large number of studies had shown that MPs had various toxicological effects on different organisms. At the same time, a number of studies had also shown that gut microbiota was closely related to host health and as a toxicity target for certain environmental pollutants including MPs. The fact is that more and more studies proved that MPs not only could interact with microorganism directly but also serve as a carrier for other pollutants and interacted with microorganism indirectly. In this review, we summarized the interactions between MPs and microorganisms as well as gut microbiota, and considered the possible impacts of MPs on environmental animal and human health, suggesting that the environmental microorganisms and the gut microbiota of animals were also the very important target for MPs. We hope that more studies pay more attention to focus on the relationship between MPs, gut microbiota, and environmental animals and human health in the future.

Effects of Diethyl Phosphate, a Non-Specific Metabolite of Organophosphorus Pesticides, on Serum Lipid, Hormones, Inflammation, and Gut Microbiota

Organophosphorus pesticides (OPs) can be metabolized to diethyl phosphate (DEP) in the gut environment, which may affect the immune and endocrine systems and the microbiota. Correlations between OPs and diseases have been established by epidemiological studies, mainly based on the contents of their metabolites, including DEP, in the serum or urine. However, the effects of DEP require further study. Therefore, in this study, adult male rats were exposed to 0.08 or 0.13 mg/kg DEP for 20 weeks. Serum levels of hormones, lipids, and inflammatory cytokines as well as gut microbiota were measured. DEP significantly enriched opportunistic pathogens, including Paraprevotella, Parabacteroides, Alloprevotella, and Helicobacter, leading to a decrease in interleukin-6 (IL-6). Exposure to the high dose of DEP enriched the butyrate-producing genera, Alloprevotella and Intestinimonas, leading to an increase in estradiol and a resulting decrease in total triglycerides (TGs) and low-density lipoprotein cholesterol (LDL-C); meanwhile, DEP-induced increases in peptide tyrosine‒tyrosine (PYY) and ghrelin were attributed to the enrichment of short-chain fatty acid-producing Clostridium sensu stricto 1 and Lactobacillus. These findings indicate that measuring the effects of DEP is not a proxy for measuring the effects of its parent compounds.

Effects of single and combined toxic exposures on the gut microbiome: Current knowledge and future directions

Human populations are chronically exposed to mixtures of toxic chemicals. Predicting the health effects of these mixtures require a large amount of information on the mode of action of their components. Xenobiotic metabolism by bacteria inhabiting the gastrointestinal tract has a major influence on human health. Our review aims to explore the literature for studies looking to characterize the different modes of action and outcomes of major chemical pollutants, and some components of cosmetics and food additives, on gut microbial communities in order to facilitate an estimation of their potential mixture effects. We identified good evidence that exposure to heavy metals, pesticides, nanoparticles, polycyclic aromatic hydrocarbons, dioxins, furans, polychlorinated biphenyls, and non-caloric artificial sweeteners affect the gut microbiome and which is associated with the development of metabolic, malignant, inflammatory, or immune diseases. Answering the question 'Who is there?' is not sufficient to define the mode of action of a toxicant in predictive modeling of mixture effects. Therefore, we recommend that new studies focus to simulate real-life exposure to diverse chemicals (toxicants, cosmetic/food additives), including as mixtures, and which combine metagenomics, metatranscriptomics and metabolomic analytical methods achieving in that way a comprehensive evaluation of effects on human health.

Impacts of polystyrene microplastic on the gut barrier, microbiota and metabolism of mice

Microplastics (MPs), which are new environmental pollutants with a diameter of <5 mm, have received wide attention in recent years. However, there are still very limited data regarding the risks of MPs to animals, especially higher mammals. In this study, we exposed male mice to 5 μm pristine and fluorescent polystyrene MP for six weeks. The results showed that the polystyrene MP was observed in the guts of mice and could reduce the intestinal mucus secretion and cause damage the intestinal barrier function. In addition, high-throughput sequencing of the V3-V4 region of the 16S rRNA gene was used to explore the change of the gut microbiota composition in the cecal content. At the phylum level, the content of Actinobacteria decreased significantly in the polystyrene MP-treated group. The PD whole-tree indexes of the alpha diversity and principal component analysis (PCA) of the beta diversity indicated that the diversity of gut microbiota was altered after polystyrene MP exposure. At the genus level, a total of 15 types of bacteria changed significantly after exposure to polystyrene MP. Furthermore, the predicted KEGG (Kyoto Encyclopedia of Genes and Genomes) metabolic pathway differences indicated that the main metabolic pathways of the functional genes in the microbial community were significantly influenced by the polystyrene MP. In addition, indexes of amino acid metabolism and bile acid metabolism in the serum were analyzed after polystyrene MP exposure. These results indicated that polystyrene MP caused metabolic disorders. In conclusion, the polystyrene MP induced gut microbiota dysbiosis, intestinal barrier dysfunction and metabolic disorders in mice. This study provided more data on the toxicity of MPs in a terrestrial organism to aid in the assessment of the health risks of polystyrene MP to animals.

Effects of polystyrene microplastics on the composition of the microbiome and metabolism in larval zebrafish

Microplastics are major pollutants in marine environment and may have health effects on aquatic organisms. In this study, we used two sizes (5 and 50 μm diameter) of fluorescent and virgin polystyrene microplastics to analyze the adverse effects on larval zebrafish. In our study, we evaluated the effects on larval zebrafish after exposure to 100 and 1000 μg/L of two sizes of polystyrene microplastics for 7 days. Our results show that polystyrene microplastics could cause alterations in the microbiome at the phylum and genus levels in larval zebrafish, including changes in abundance and diversity of the microbiome. In addition, metabolomic analysis suggested that exposure to polystyrene microplastics induced alterations of metabolic profiles in larval zebrafish, and differential metabolites were involved in energy metabolism, glycolipid metabolism, inflammatory response, neurotoxic response, nucleic acid metabolism, oxidative stress. Polystyrene microplastics also significantly decreased the activities of catalase and the content of glutathione. In addition, the results of gene transcription analysis showed that exposure to polystyrene microplastics induced changes in glycolysis-related genes and lipid metabolism-related genes, confirming that polystyrene microplastics disturbed glycolipid and energy metabolism. Taken together, the results obtained in the present study indicated that the potential effects of environmental microplastics on aquatic organisms should not be ignored.

Propamocarb exposure decreases the secretion of neurotransmitters and causes behavioral impairments in mice

Propamocarb (PM) is a type of fungicide, which is widely used in the greenhouse-based production of vegetables and fruits globally. It has been considered to have generally low toxicity. However, the teratogenicity or neurotoxicity for mammals remains unclear. In this study, we aimed to explore its effect on the secretion of neurotransmitters and behavioral impairments. Male adult mice were exposed to 10 and 40 mg/L PM for 2 weeks (acute exposure) or 3 and 10 mg/L PM for 10 weeks (chronic exposure). It was observed that acute or chronic exposure to PM changed the levels of serotonin (5-HT) and dopamine in the serum and colon and the transcription of TPH2 and DRD2 in the colons of mice. In addition, the locomotor test, the open field test, and the Morris water maze analysis also showed that acute exposure to PM caused behavioral impairments to some extent. The results obtained in the present study indicated that PM has the potential to induce neurotoxicity in animals.

Lactobacillus plantarum TW1-1 Alleviates Diethylhexylphthalate-Induced Testicular Damage in Mice by Modulating Gut Microbiota and Decreasing Inflammation

Diethylhexylphthalate (DEHP), acting as an endocrine disruptor, disturbed reproductive health. Here, we evaluated the effects of Lactobacillus plantarum TW1-1 (L. plantarum TW1-1) on DEHP-induced testicular damage in adult male mice. Results showed that oral supplementation of L. plantarum TW1-1 significantly increased the serum testosterone concentration, enhanced the semen quality, and attenuated gonad development defects in DEHP-exposed mice. L. plantarum TW1-1 also alleviated DEHP-induced oxidative stress and inflammatory responses by decreasing the mRNA expression and serum protein concentration of different inflammatory factors [tumor necrosis factor-α, interleukin (IL)-1β and IL-6]. Furthermore, L. plantarum TW1-1 significantly reduced DEHP-induced intestinal hyper-permeability and the increase in the serum lipopolysaccharide level. Gut microbiota diversity analysis revealed that L. plantarum TW1-1 shifted the DEHP-disrupted gut microbiota to that of the control mice. At phylum level, L. plantarum TW1-1 reversed DEHP-induced Bacteroidetes increase and Firmicutes decrease, and restored Deferribacteres in DEHP-exposed mice. Spearman's correlation analysis showed that Bacteroidetes, Deferribacteres, and Firmicutes were associated with DEHP-induced testicular damage. In addition, the ratio of Firmicutes to Bacteroidetes (Firm/Bac ratio) significantly decreased from 0.28 (control group) to 0.13 (DEHP-exposed group), which was restored by L. plantarum TW1-1 treatment. Correlation analysis showed that the Firm/Bac ratio was negatively correlated with testicular damage and inflammation. These findings suggest that L. plantarum TW1-1 prevents DEHP-induced testicular damage via modulating gut microbiota and decreasing inflammation.

Pubertal exposure to the endocrine disruptor mono-2-ethylhexyl ester at body burden level caused cholesterol imbalance in mice

Metabolic disturbance is the prerequisite to developing metabolic disease. An increasing number of reports have shown that exposure to environmental endocrine-disrupting chemicals (EDCs) can cause metabolic syndrome and may be related to metabolic disease. However, the potential mechanism of EDC-related lipid metabolism disruption in the endocrine organs (especially gut microbiome) during pubertal exposure remains elusive at the body burden level. We observed that male mice fed with 0.05 mg/kg b.w. MEHP under a high-fat diet caused enhancement in the fat mass, total cholesterol, high- and low-density lipoprotein cholesterol. MEHP intake induced a significant shift in microbiota composition, including the relative abundance of Firmicutes and reduction of Verrucomicrobia. Statistical analysis showed a positive correlation between several bacterial taxa and cholesterol body burden. Also, MEHP intake induced adipocyte hypertrophy and cholesterol overloading, which sense cholesterol synthesis genes such as Srebp2 and Hmgcr. That caused adipocyte dysfunction. Finally, cholesterol deposition and transportation was imbalance in the mice liver. Conclusively, by targeting the endocrine organs, EDCs would increase the risk of cholesterol burden even at a low concentration when coupled with a high-fat diet during pubertal period in male mice.

A Review on Gut Remediation of Selected Environmental Contaminants: Possible Roles of Probiotics and Gut Microbiota

Various environmental contaminants including heavy metals, pesticides and antibiotics can contaminate food and water, leading to adverse effects on human health, such as inflammation, oxidative stress and intestinal disorder. Therefore, remediation of the toxicity of foodborne contaminants in human has become a primary concern. Some probiotic bacteria, mainly Lactobacilli, have received a great attention due to their ability to reduce the toxicity of several contaminants. For instance, Lactobacilli can reduce the accumulation and toxicity of selective heavy metals and pesticides in animal tissues by inhibiting intestinal absorption of contaminants and enhancing intestinal barrier function. Probiotics have also shown to decrease the risk of antibiotic-associated diarrhea possibly via competing and producing antagonistic compounds against pathogenic bacteria. Furthermore, probiotics can improve immune function by enhancing the gut microbiota mediated anti-inflammation. Thus, these probiotic bacteria are promising candidates for protecting body against foodborne contaminants-induced toxicity. Study on the mechanism of these beneficial bacterial strains during remediation processes and particularly their interaction with host gut microbiota is an active field of research. This review summarizes the current understanding of the remediation mechanisms of some probiotics and the combined effects of probiotics and gut microbiota on remediation of foodborne contaminants in vivo.

Chronic exposure to fungicide propamocarb induces bile acid metabolic disorder and increases trimethylamine in C57BL/6J mice

Propamocarb (PM) is a widely used fungicide that affects lipid biosynthesis in fungi. In this study, we explored the effects of PM on mouse metabolism and gut microbiota-related pathways by exposing C57BL/6J mice to 1, 3, and 10 mg/L PM through drinking water for a duration of 10 weeks. We found that hepatic bile acids (BAs) were considerably increased in the PM-treated group. The transcription of genes related to BA synthesis and transportation were also markedly altered in the liver and the ileum; accordingly, serous BA profiles were changed. BAs are tightly associated with energy metabolism and the gut microbiota; as expected, we observed that hepatic glycolysis; β-oxidation; fatty acid transportation, release and synthesis; and triacylglycerol synthesis and transportation were significantly altered at the transcriptional level. Gut microbial community structures were significantly changed both in cecal contents and feces. Using Linear discriminant analysis Effect Size (LEfSe), we found that Chloroflexi, Bacteroidetes and Actinobacteria phyla; Prevotellaceae, Odoribacteraceae and Porphyromonadaceae families; and Butyricimonas, Oscillospira, Parabacteroides, Prevotella and Dorea genera enriched in PM-treated mice. Fecal metabolites involved in energy metabolism were likewise altered. In addition, the atherosclerosis-promoting molecule trimethylamine was significantly increased in feces, which induced a disturbance in the cardiac NO/NOS pathway and an increase in NF-κB transcriptional levels. Our findings indicated that chronic PM exposure induced disorders in enterohepatic metabolism and had potential to increase the risk of cardiovascular disease.

Acute exposure to PBDEs at an environmentally realistic concentration causes abrupt changes in the gut microbiota and host health of zebrafish

Contamination from lower brominated PBDEs is ubiquitous in the environments. However, their effects on gut microbiota and intestinal health have not yet been investigated. This study exposed adult zebrafish to an environmentally realistic concentration of pentaBDE mixture (DE-71) at 5.0 ng/L for 7 days, after which metagenomic sequencing of the intestinal microbiome was conducted and host physiological activities in the intestine and liver were also examined. The results showed that acute exposure to DE-71 significantly shifted the gut microbial community in a sex-specific manner. Certain genera (e.g., Mycoplasma, Ruminiclostridium, unclassified Firmicutes sensu stricto, and Fusobacterium) disappeared from the DE-71-exposed intestines, resulting in decreased bacterial diversity. Bacterial metabolic functions in guts were also affected by DE-71, namely those covering energy metabolism, virulence, respiration, cell division, cell signaling, and stress response. In addition, measurement of diverse sensitive biomarkers showed that the health of male intestines was remarkably compromised by the DE-71 exposure, as indicated by the disruption to its neural signaling (serotonin), epithelial barrier integrity (tight junction protein 2), inflammatory response (interleukin 1β), oxidative stress and antioxidant capacity, as well as detoxifying potential (ethoxyresorufin-O-deethylase activity). However, female intestines maintained intact physiological activities. Compared to the direct impact on intestines, a latent effect of DE-71 was observed in livers. Co-occurrence network analysis demonstrated that the gut bacteria vigorously interacted to establish the fittest community under DE-71 stress by promoting the reproduction of favorable genera, while diminishing the survival of unfavorable ones. Significant correlations between the zebrafish gut microbiota and physiological activities (e.g., oxidative stress, detoxification, neurotransmission, and epithelial integrity) were also observed. Overall, this study has demonstrated, for the first time, the high susceptibility of gut microbiota and intestinal health of zebrafish to DE-71, thus warranting more work to reveal its mode of toxicity.

Chronic exposure to low concentrations of lead induces metabolic disorder and dysbiosis of the gut microbiota in mice

Lead (Pb) is one of the most prevalent toxic, nonessential heavy metals that can contaminate food and water. In this study, effects of chronic exposure to low concentrations of Pb on metabolism and gut microbiota were evaluated in mice. It was observed that exposure of mice to 0.1mg/L Pb, supplied via drinking water, for 15weeks increased hepatic TG and TCH levels. The levels of some key genes related to lipid metabolism in the liver increased significantly in Pb-treated mice. For the gut microbiota, at the phylum level, the relative abundance of Firmicutes and Bacteroidetes changed obviously in the feces and the cecal contents of mice exposed to 0.1mg/L Pb for 15weeks. In addition, 16s rRNA gene sequencing further discovered that Pb exposure affected the structure and richness of the gut microbiota. Moreover, a ¹H NMR metabolic analysis unambiguously identified 31 metabolites, and 15 metabolites were noticeably altered in 0.1mg/L Pb-treated mice. Taken together, the data indicate that chronic Pb exposure induces dysbiosis of the gut microbiota and metabolic disorder in mice.

CAPSULE

Chronic Pb exposure induces metabolic disorder, dysbiosis of the gut microbiota and hepatic lipid metabolism disorder in mice.

Polystyrene microplastics induce gut microbiota dysbiosis and hepatic lipid metabolism disorder in mice

Microplastic (MP) has become a concerning global environmental problem. It is toxic to aquatic organisms and can spread through the food chain to ultimately pose a threat to humans. In the environment, MP can interact with microbes and act as a microbial habitat. However, effects of polystyrene MP on the gut microbiota in mammals remain unclear. Here, male mice were exposed to two different sizes of polystyrene MP for 5 weeks to explore its effect. We observed that oral exposure to 1000 μg/L of 0.5 and 50 μm polystyrene MP decreased the body, liver and lipid weights in mice. Mucus secretion in the gut decreased in both sizes of polystyrene MP-treated groups. Regarding the gut microbiota, at the phylum level, polystyrene MP exposure decreased the relative abundances of Firmicutes and α-Proteobacteria in the feces. Furthermore, high throughput sequencing of the V3-V4 region of the 16S rRNA gene revealed significant changes in the richness and diversity of the gut microbiota in the cecums of polystyrene MP-treated mice. At the genus level, a total of 6 and 8 types of bacteria changed in the 0.5 and 50 μm polystyrene MP-treated groups, respectively. Furthermore, an operational taxonomic unit (OTU) analysis identified that 310 and 160 gut microbes were changed in the 0.5 and 50 μm polystyrene MP-treated groups, respectively. In addition, the hepatic triglyceride (TG) and total cholesterol (TCH) levels decreased in both 1000 μg/L 0.5 and 50 μm polystyrene MP-treated groups. Correspondingly, the relative mRNA levels of some key genes related to lipogenesis and TG synthesis decreased in the liver and epididymal fat. These results indicated that polystyrene MP could modify the gut microbiota composition and induce hepatic lipid disorder in mice; while the mouse is a common mammal model, consequently, the health risks of MP to animals should not be ignored.

Exposure to the fungicide propamocarb causes gut microbiota dysbiosis and metabolic disorder in mice

Propamocarb (PM) is a widely used fungicide with property of affecting fatty acid and phospholipid biosynthesis in funguses. In this study, we explored its effects on mice gut microbiota and metabolism by exposing mice to 3, 30, and 300 mg/L PM through drinking water for a duration of 28 days. We observed that the transcription of hepatic genes related to regulate lipid metabolism were perturbed by PM exposure. The microbiota in the cecal contents and feces changed during or after PM exposure at phylum or genus levels. 16S rRNA gene sequencing for the cecal content revealed shifted in overall microbial structure after PM exposure, and operational taxonomic unit (OTU) analysis indicated that 32.2% of OTUs changed by 300 mg/mL PM exposure for 28 days. In addition, based on ¹H NMR analysis,a total of 20 fecal metabolites mainly including succinate, short chain fatty acids, bile acids and trimethylamine were found to be significantly influenced by exposure to 300 mg/L PM.,. These metabolites were tightly correlated to host metabolism. Our findings indicated that high doses of PM exposure could disturb mice metabolism through, or partly through, altering the gut microbiota and microbial metabolites.

Tributyltin exposure induces gut microbiome dysbiosis with increased body weight gain and dyslipidemia in mice

Gut microbiome dysbiosis plays a profound role in the pathogenesis of obesity and tributyltin (TBT) has been found as an environmental obesogen. However, whether TBT could disturb gut microbiome and the relationship between obesity induced by TBT exposure and alteration in gut microbiota are still unknown. In order to assess the association between them, mice were exposed to TBTCl (50 μg kg^-1) once every three days from postnatal days (PNDs) 24 to 54. The results demonstrated that TBT exposure resulted in increased body weight gain, lager visceral fat accumulation and dyslipidemia in male mice on PND 84. Correspondingly, 16S rRNA gene sequencing revealed that TBT treatment decreased gut microbial species and perturbed the microbiome composition in mice. Furthermore, Pearson's corelation coefficient analysis showed a significantly negative correlation between the body weight and the alpha diversity of gut microbiome. These results suggested that TBT exposure could induce gut microbiome dysbiosis in mice, which might contribute to the obesity pathogenesis.

Enantioselective Effects of Metalaxyl Enantiomers in Adolescent Rat Metabolic Profiles Using NMR-Based Metabolomics

More than 30% of the registered pesticides are chiral with one or more chiral centers and exist as two or more enantiomers. The frequency of chiral chemicals and their environmental safety has been considered in their risk assessment in recent decades. Despite the fact that metabolic disturbance is an important sensitive molecular initiating event of toxicology effects, the potential mechanisms of how chiral compounds affect metabolism phenotypes in organisms remain unclear. As a typical chiral pesticide, metalaxyl is an acylalanine fungicide with systemic function. Although the fungicidal activity almost comes from the R-enantiomer, the toxicity of both enantiomers in animals and human beings is not yet clear. In this study, a nuclear magnetic resonance (NMR)-based metabolomics approach was adopted to evaluate the enantioselectivity in metabolic perturbations in adolescent rats. On the basis of multivariate statistical results, stable and evident metabolic profiles of the enantiomers were obtained. When rats were exposed to R-metalaxyl, the significantly perturbed metabolic pathways were biosynthesis of valine, leucine, and isoleucine, synthesis and degradation of ketone bodies, and metabolism of glycerolipid. In contrast, more significantly perturbed metabolic pathways were obtained when the rats were exposed to S-metalaxyl, including glycolysis, biosynthesis of valine, leucine, and isoleucine, metabolism of glycine, serine, and threonine, synthesis and degradation of ketone bodies, metabolism of glycerophospholipid and glycerolipid. These abnormal metabolic pathways were closely related to liver metabolism. These results offer more detailed information about the enantioselective metabolic effects of metalaxyl in adolescent development and provide data for the health risk assessment of metalaxyl at molecular level.

Glyphosate based- herbicide exposure affects gut microbiota, anxiety and depression-like behaviors in mice

Recently, a number of studies have demonstrated the profound relationship between gut microbiota (GM) alterations and behavioral changes. Glyphosate-based herbicides (GBH) have been shown to induce behavioral impairments, and it is possible that they mediate the effects through an altered GM. In this study, we investigated the toxic effects of GBH on GM and its subsequent effects on the neurobehavioral functions in mice following acute, subchronic and chronic exposure to 250 or 500 mg/kg/day. The effect of these acute and repeated treatments was assessed at the behavioral level using the open field, the elevated plus maze, the tail suspension and splash tests. Then, mice were sacrificed and the intestinal samples were collected for GM analysis. Subchronic and chronic exposure to GBH induced an increase of anxiety and depression-like behaviors. In addition, GBH significantly altered the GM composition in terms of relative abundance and phylogenic diversity of the key microbes. Indeed, it decreased more specifically, Corynebacterium, Firmicutes, Bacteroidetes and Lactobacillus in treated mice. These data reinforce the essential link between GM and GBH toxicity in mice and suggest that observed intestinal dysbiosis could increase the prevalence of neurobehavioral alterations.

Polystyrene microplastics induce microbiota dysbiosis and inflammation in the gut of adult zebrafish

Microplastic (MP) are environmental pollutants and have the potential to cause varying degrees of aquatic toxicity. In this study, the effects on gut microbiota of adult male zebrafish exposed for 14 days to 100 and 1000 μg/L of two sizes of polystyrene MP were evaluated. Both 0.5 and 50 μm-diameter spherical polystyrene MP increased the volume of mucus in the gut at a concentration of 1000 μg/L (about 1.456 × 10¹⁰ particles/L for 0.5 μm and 1.456 × 10⁴ particles/L for 50 μm). At the phylum level, the abundance of Bacteroidetes and Proteobacteria decreased significantly and the abundance of Firmicutes increased significantly in the gut after 14-day exposure to 1000 μg/L of both sizes of polystyrene MP. In addition, high throughput sequencing of the 16S rRNA gene V3-V4 region revealed a significant change in the richness and diversity of microbiota in the gut of polystyrene MP-exposed zebrafish. A more in depth analysis, at the genus level, revealed that a total of 29 gut microbes identified by operational taxonomic unit (OTU) analysis were significantly changed in both 0.5 and 50 μm-diameter polystyrene MP-treated groups. Moreover, it was observed that 0.5 μm polystyrene MP not only increased mRNA levels of IL1α, IL1β and IFN but also their protein levels in the gut, indicating that inflammation occurred after polystyrene MP exposure. Our findings suggest that polystyrene MP could induce microbiota dysbiosis and inflammation in the gut of adult zebrafish.

Dysregulation of Intestinal Health by Environmental Pollutants: Involvement of the Estrogen Receptor and Aryl Hydrocarbon Receptor

To determine how environmental pollutants induce dysbiosis of the gut microbiota, we exposed adult zebrafish to model pollutants with varied modes of action (atrazine, estradiol, polychlorinated biphenyl [PCB]126, and PCB153) for 7 days. Subsequently, metagenomic sequencing of the intestines was performed to compare the gut microbiomes among the groups. We observed clear compound- and sex-specific responses to xenobiotic stress. Principal component analysis revealed involvement of the aryl hydrocarbon receptor (AhR) and, to a lesser extent, the estrogen receptor (ER) in the dysregulation of the intestinal microbiota. The model pollutants differentially impaired intestinal and hepatic physiological activities, as indicated by assessments of gut motility, epithelial permeability, inflammation, and oxidative stress. Correlation analysis showed that abnormal Aeromonas reproduction, especially in the PCB126 groups, was significantly positively associated with oxidative damage. Aeromonas closely interacted with Mannheimia and Blastococcus to regulate intestinal permeability. In summary, we demonstrated that ER and AhR signaling regulated the dynamics of the gut microbiota. Our findings provide new mechanistic insight into the complex interactions between the host metabolism and gut microbiota, which may contribute to the grouped assessment of environmental pollutants in future.