Maternal procymidone exposure has lasting effects on murine gut-liver axis and glucolipid metabolism in offspring

The toxicity and health risk of chlorothalonil to non-target animals and humans: A systematic review

Chlorothalonil (CTL), an organochloride fungicide applied for decades worldwide, has been found to be present in various matrixes and even accumulates in humans or other mammals through the food chain. Its high residue and diffusion in the environment have severely affected food security and public health. More and more research has considered CTL as a possible toxin to environmental non-target organisms, via influencing multiple systems such as metabolic, developmental, endocrine, genetic, and reproductive pathways. Aquatic organisms and amphibians are the most vulnerable species to CTL exposure, especially during the early period of development. Under experimental conditions, CTL can also have toxic effects on rodents and other non-target organisms. As for humans, CTL exposure is most often reported to be relevant to allergic reactions to the skin and eyes. We hope that this review will improve our understanding of the hazards and risks that CTL poses to non-target organisms and find a strategy for rational use.

Endocrine disrupting chemicals: gestational diabetes and beyond

Gestational Diabetes Mellitus (GDM) has been on the rise for the last two decades along with the growing incidence of obesity. The ubiquitous use of Endocrine-Disrupting Chemicals (EDCs) worldwide has been associated with this increase in GDM incidence. Epigenetic modifications such as DNA methylation, histone acetylation, and methylation have been associated with prenatal exposure to EDCs. EDC exposure can also drive a sustained disruption of the hypothalamus-pituitary-thyroid axis and various other signaling pathways such as thyroid signaling, PPARγ signaling, PI3K-AKT signaling. This disruption leads to impaired glucose metabolism, insulin resistance as well as β-cell dysfunction, which culminate into GDM. Persistent EDC exposure in pregnant women also increases adipogenesis, which results in gestational weight gain. Importantly, pregnant mothers transfer these EDCs to the fetus via the placenta, thus leading to other pregnancy-associated complications such as intrauterine growth restriction (IUGR), and large for gestational age neonates. Furthermore, this early EDC exposure of the fetus increases the susceptibility of the infant to metabolic diseases in early life. The transgenerational impact of EDCs is also associated with higher vascular tone, cognitive aberrations, and enhanced susceptibility to lifestyle disorders including reproductive health anomalies. The review focuses on the impact of environmental toxins in inducing epigenetic alterations and increasing the susceptibility to metabolic diseases during pregnancy needs to be extensively studied such that interventions can be developed to break this vicious cycle. Furthermore, the use of EDC-associated ExomiRs from the serum of patients can help in the early diagnosis of GDM, thereby leading to triaging of patients based on increasing risk factor of the clinicopathological condition.

Co-exposure to polystyrene microplastics and cypermethrin enhanced the effects on hepatic phospholipid metabolism and gut microbes in adult zebrafish

Microplastics (MPs) can absorb environmental pollutants from the aquatic environment to cause mixed toxicity, which has received widespread attention. However, studies on the joint effects of MPs and insecticides are limited. As one of the most widely used pyrethroids, there was a large amount of residual cypermethrin (CYP) in water due to insufficient decomposition. Here, adult female zebrafish were exposed to MPs, CYP, and their mixtures for 21 days, respectively. After exposures, the MPs and CYP caused tissue damage to the liver. Hepatic triglyceride (TG) level increased significantly after MPs + CYP exposure, and the expression of genes about glycolipids metabolism was significantly altered. Furthermore, metabolome results suggested that MPs + CYP exposure resulted in increased content of some glycerophospholipid, affecting phospholipid metabolism-related pathways. In addition, through 16 s rDNA sequencing, it was found that MPs + CYP led to significant changes in the proportion of dominant phyla. Interestingly, Cetobacterium which increased in CYP and the co-exposure group was positively correlated with most lipid metabolites. Our results suggested that co-exposure to MPs and CYP enhanced the disturbances in hepatic phospholipid metabolism by affecting the gut microbial composition, while these changes were not observed in separate treatment groups. These results emphasized the importance of studying the joint toxicity of MPs and insecticides.

Imazalil resulted in glucolipid metabolism disturbance and abnormal m6A RNA methylation in the liver of dam and offspring mice

As a fungicide with the characteristics of high effectiveness, internal absorption and broad spectrum, imazalil is widely used to prevent and treat in fruits and vegetables. Here, pregnant C57BL/6 mice were exposed to imazalil at dietary levels of 0, 0.025‰, and 0.25‰ through drinking water during pregnancy and lactation. We then analyzed the phenotype, metabolome, and expression of related genes and proteins in the livers of mice. There was a marked decrease in the body and liver weights of male offspring mice after maternal imazalil exposure, while this effect on the dam and female offspring was slight. Metabolomics analyses revealed that imazalil significantly altered the metabolite composition of liver samples from both dams and offspring. The preliminary results of the analysis indicated that glucolipid metabolism was the pathway most significantly affected by imazalil. We performed a coabundance association analysis of metabolites with significant changes in the pathway of glycolipid metabolism, and IMZ altered the networks of both dams and offspring compared with the network in control mice, especially in male offspring. The hepatic triglyceride, non-esterified fatty acid and glucose levels were increased significantly in the dams but decreased significantly in male offspring after maternal imazalil exposure. Furthermore, the expression levels of genes associated with glycolipid metabolism and m6A RNA methylation were significantly affected by maternal intake of imazalil. Imazalil-induced glucolipid metabolism disturbance was highly correlated with m6A RNA methylation. In conclusion, maternal imazalil exposure resulted in glucolipid metabolism disturbance and abnormal m6A RNA methylation in the livers of dams and offspring mice. We expected that the information acquired in this study will provide novel evidence for understanding the effect of maternal imazalil exposure on potential health risks.

Toxicologic effect and transcriptome analysis for sub-chronic exposure to carbendazim, prochloraz, and their combination on the liver of mice

Carbendazim (CBZ) and prochloraz (PCZ) are broad-spectrum fungicides used in agricultural peat control. Both fungicides leave large amounts of residues in fruits and are toxic to non-target organisms. However, the combined toxicity of the fungicides to non-target organisms is still unknown. Therefore, we characterized the toxic effects of dietary supplementation with CBZ, PCZ, and their combination for 90 days in 6-week-old male Institute of Cancer Research (ICR) mice. CBZ-H (100 mg/kg day), PCZ-H (10 mg/kg day), and their combination treatments increased the relative liver weights and caused liver injury. The serum total cholesterol (TC), triglyceride (TG), glucose (Glu), pyruvate (PYR), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were reduced, and synergistic toxicity was observed. Hepatic transcriptome revealed that 326 differentially expressed genes (DEGs) of liver were observed in the CBZ treatment group, 149 DEGs in the PCZ treatment group, and 272 DEGs in the combination treatment group. According to KEGG enrichment analysis, the fungicides and their combination affected lipid metabolism, amino acid metabolism, and ferroptosis. In addition, the relative mRNA levels of key genes involved in lipid metabolism were also examined. Compared with individual exposure, combined exposure to CBZ and PCZ caused a more obvious decrease in the expression of some genes related to glycolipid metabolism. Furthermore, the relative mRNA levels of some key genes in the combination treatment group were lower than those in the CBZ and PCZ treated groups. In summary, CBZ, PCZ, and their combination generally caused hepatotoxicity and glycolipid metabolism disorders, which could provide new insights for investigating the combined toxicity of multiple fungicides to animals.

Mefentrifluconazole exposure disrupted hepatic lipid metabolism disorder tightly associated with gut barrier function abnormal in mice

Mefentrifluconazole (MFZ) is an azole fungicide that is placed in agriculture for the control of fungal hazards. However, due to their non-biodegradability, azole fungicides can accumulate in plants, animals, and the environment, thus becoming a major health concern worldwide. In this study, we exposed 7-week-old C57BL/6 mice to 10, 30, and 100 mg/kg of MFZ for 28 d to assess the toxic effects of MFZ on the liver and gut tissues of the mice. Histopathological, biochemical indexes, and transcriptomic analyses revealed that MFZ exposure disrupted the liver structure and hepatic lipid metabolism as well as damaged gut barrier function and promoted inflammation in mice. Moreover, 16S rRNA sequencing demonstrated that MFZ exposure significantly increased the abundance of patescibacteria at the generic level. Also, MFZ exposure increased the abundance of bacterial genera associated with inhibition of glycolipid metabolism. These results suggested that the disruption of liver lipid metabolism caused by MFZ exposure may be caused by changes in gut microbiota function. This study provided a new disease occurrence study for risk assessment of MFZ and strengthened the focus on some novel fungicides.

Underestimated health risks: Dietary restriction magnify the intestinal barrier dysfunction and liver injury in mice induced by polystyrene microplastics

Microplastics (MPs) have gained significant attention due to their widespread presence in the environment. While studies have been conducted to investigate the risks associated with MPs, the potential effects of MPs on populations with varying dietary habits, such as dietary restriction (DR), remain largely undefined. The sensitivity of the body to invasive contaminants may increase due to insufficient food intake. Here, we aimed to investigate whether dietary restriction could affect the toxicity of MPs in mice. Following a 5-week exposure to 200 μg/L polystyrene microplastics (PSMPs), DR-PSMPs treatment group exhibited significant intestinal barrier dysfunction compared to ND-PSMPs treatment group, as determined by histopathological and biochemical analysis. Dietary restriction worsened liver oxidative stress and bile acid disorder in mice exposed to PSMPs. 16S rRNA sequencing analysis revealed that DR-PSMPs treatment caused alterations in gut microbiota composition, including the downregulation of probiotics abundance and upregulation of pathogenic bacteria abundance. The negative effects caused by PSMPs in mice with dietary restriction could attribute to increased MPs bioaccumulation, declined water intake, reduced probiotics abundance, and elevated pathogenic bacteria abundance, as well as the susceptibility of the dietary restriction individual. Our findings hint that the biological effects of contaminants could be affected by dietary habits.

Acute chlorothalonil exposure had the potential to influence the intestinal barrier function and micro-environment in mice

The intestinal barrier maintains intestinal homeostasis and metabolism and protects against harmful pollutants. Some environmental pollutants seriously affect intestinal barrier function. However, it remains unclear whether or how chlorothalonil (CTL) impacts the intestinal barrier function in animals. Herein, 6-week-old male mice were acutely exposed to different CTL concentrations (100 and 300 mg/kg BW) via intragastric administration once a day for 7 days. Histopathological examination revealed obvious inflammation in the mice' colon and ileum. Most notably, CTL exposure increased the intestinal permeability, particularly in the CTL-300 group. CTL exposure reduced the secretion of colonic epithelial mucus and changed the transcription levels of genes bound up with ion transport and ileal antimicrobial peptide (AMP) secretion, indicating intestinal chemical barrier damage. The results of terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay and Ki67 staining revealed abnormal apoptosis and increased intestinal epithelial cell proliferation, suggesting that CTL exposure led to cytotoxicity and inflammation. The results of 16S rRNA sequencing revealed that CTL exposure altered the intestinal microbiota composition and reduced its diversity and richness in the colon contents. Thus, acute CTL exposure affected the different intestinal barrier- and gut microenvironment-related endpoints in mice.

Oral exposure to polyethylene microplastics induces inflammatory and metabolic changes and promotes fibrosis in mouse liver

Accumulating evidence shows widespread contamination of water sources and food with microplastics. Although the liver is one of the main sites of bioaccumulation within the human body, it is still unclear whether microplastics produce damaging effects. In particular, the hepatic consequences of ingesting polyethylene (PE) microplastics in mammals are unknown. In this study, female mice were fed with food contaminated with 36 and 116 µm diameter PE microbeads at a dosage of 100 µg/g of food for 6 and 9 weeks. Mice were exposed to each type of microbead, or co-exposed to the 2 types of microbeads. Mouse liver showed altered levels of genes involved in uptake, synthesis, and β-oxidation of fatty acids. Ingestion of PE microbeads disturbed the detoxification response, promoted oxidative imbalance, increased inflammatory foci and cytokine expression, and enhanced proliferation in liver. Since relative expression of the hepatic stellate cell marker Pdgfa and collagen deposition were increased following PE exposure, we assessed the effect of PE ingestion in a mouse model of CCl4-induced fibrosis and showed that PE dietary exposure exacerbated liver fibrogenesis. These findings provide the first demonstration of the adverse hepatic effects of PE ingestion in mammals and highlight the need for further health risk assessment in humans.

Characterization of N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD)-induced cardiotoxicity in larval zebrafish (Danio rerio)

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) is a type of p-phenylenediamine (PPD), which is widely used in the manufacture of rubber tires owing to its excellent antiozonant properties. In this study, the developmental cardiotoxicity of 6PPD was evaluated in zebrafish larvae, and the LC50 was approximately 737 μg/L for the larvae at 96 h post fertilization (hpf). In the 6PPD treatment of 100 μg/L, the accumulation concentrations of 6PPD were up to 2658 ng/g in zebrafish larvae, and 6PPD induced significant oxidative stress and cell apoptosis in the early developmental stages of zebrafish. Transcriptome analysis showed that 6PPD exposure could potentially cause cardiotoxicity in larval zebrafish by affecting the transcription of the genes related to the calcium signal pathway and cardiac muscle contraction. The genes related to calcium signaling pathway (slc8a2b, cacna1ab, cacna1da, and pln) were verified by qRT-PCR, which were significantly downregulated in larval zebrafish after exposing to 100 μg/L of 6PPD. Simultaneously, the mRNA levels of the genes related to cardiac functions (myl7, sox9, bmp10, and myh71) also respond accordingly. H&E staining and heart morphology investigation indicated that cardiac malformation occurred in zebrafish larvae exposed to 100 μg/L of 6PPD. Furthermore, the phenotypic observation of transgenic Tg (myl7: EGFP) zebrafish also confirmed that 100 μg/L of 6PPD exposure could change the distance of atria and ventricles of the heart and inhibit some key genes (cacnb3a, ATP2a1l, ryr1b) related to cardiac function in larval zebrafish. These results revealed the toxic effects of 6PPD on the cardiac system of zebrafish larvae.

Insights into enhanced toxic effects by the binary mixture of carbendazim and procymidone on hepatic lipid metabolism in mice

Carbendazim (CBZ) and procymidone (PRO) are two widely used fungicides in agriculture. However, there are still gaps in knowledge regarding about the potential hazards of joint exposure to CBZ and PRO in animals. Here, 6-week-old ICR mice were exposed to CBZ, PRO and CBZ + PRO for 30 days, and metabolomics were performed to discover the mechanism by which the mixture enhanced the effects on lipid metabolism. Co-exposure to CBZ + PRO elevated the body weights, relative liver weights and relative epididymis fat weights, but not in the single exposure groups. Molecular docking analysis suggested that CBZ and PRO combined with peroxisome proliferator-activated receptor (PPARγ) at the same amino acid site as the agonist rosiglitazone. The RT-qPCR and WB results demonstrated that the levels of PPARγ were higher in the co-exposure group than in the single exposure groups. In addition, hundreds of differential metabolites were discovered by metabolomics and enriched in different pathways, such as pentose phosphate pathway and purine metabolism. A unique effect, a decrease in glucose-6-phosphate (G6P) that promoted more NADPH production, was observed in the CBZ + PRO group. These results demonstrated that exposure to CBZ + PRO caused more serious lipid metabolism disorder in the liver than exposure to a single fungicide, which could provide some new insight for the toxic effects after fungicides joint exposure.

Oral Exposure to Epoxiconazole Disturbed the Gut Micro-Environment and Metabolic Profiling in Male Mice

Epoxiconazole (EPX), a triazole fungicide, is widely used in agriculture to control pests and diseases. High residual and occupational exposure to EPX increases health risks, and evidence of potential harm to mammals remains to be added. In the present study, 6-week-old male mice were exposed to 10 and 50 mg/kg bw EPX for 28 days. The results showed that EPX significantly increased the liver weights. EPX also decreased the mucus secretion of the colon and altered intestinal barrier function in mice including a reduced expression of some genes (Muc2, meprinβ, tjp1). Moreover, EPX altered the composition and abundance of gut microbiota in the colon of mice. The alpha diversity indices (Shannon, Simpson) in the gut microbiota increased after exposure to EPX for 28 days. Interestingly, EPX increased the ratio of Firmicutes to Bacteroides and the abundance of other harmful bacteria including Helicobacter and Alistipes. Based on the untargeted metabolomic analysis, it was found that EPX altered the metabolic profiles of the liver in mice. KEGG analysis of differential metabolites revealed that EPX disrupted the pathway related to glycolipid metabolism, and the mRNA levels of related genes were also confirmed. In addition, the correlation analysis showed that the most altered harmful bacteria were associated with some significantly altered metabolites. The findings highlight that EPX exposure changed the micro-environment and lipid metabolism disturbance. These results also suggest that the potential toxicity of triazole fungicides to mammals cannot be ignored.