Integrative study of diet-induced mouse models of NAFLD identifies PPARα as a sexually dimorphic drug target.

OBJECTIVE: We evaluated the influence of sex on the pathophysiology of non-alcoholic fatty liver disease (NAFLD). We investigated diet-induced phenotypic responses to define sex-specific regulation between healthy liver and NAFLD to identify influential pathways in different preclinical murine models and their relevance in humans. DESIGN: Different models of diet-induced NAFLD (high-fat diet, choline-deficient high-fat diet, Western diet or Western diet supplemented with fructose and glucose in drinking water) were compared with a control diet in male and female mice. We performed metabolic phenotyping, including plasma biochemistry and liver histology, untargeted large-scale approaches (liver metabolome, lipidome and transcriptome), gene expression profiling and network analysis to identify sex-specific pathways in the mouse liver. RESULTS: The different diets induced sex-specific responses that illustrated an increased susceptibility to NAFLD in male mice. The most severe lipid accumulation and inflammation/fibrosis occurred in males receiving the high-fat diet and Western diet, respectively. Sex-biased hepatic gene signatures were identified for these different dietary challenges. The peroxisome proliferator-activated receptor α (PPARα) co-expression network was identified as sexually dimorphic, and in vivo experiments in mice demonstrated that hepatocyte PPARα determines a sex-specific response to fasting and treatment with pemafibrate, a selective PPARα agonist. Liver molecular signatures in humans also provided evidence of sexually dimorphic gene expression profiles and the sex-specific co-expression network for PPARα. CONCLUSIONS: These findings underscore the sex specificity of NAFLD pathophysiology in preclinical studies and identify PPARα as a pivotal, sexually dimorphic, pharmacological target. TRIAL REGISTRATION NUMBER: NCT02390232.

Prospective association between dietary pesticide exposure profiles and type 2 diabetes risk in the NutriNet-Santé cohort.

BACKGROUND: Studies focusing on dietary pesticides in population-based samples are scarce and little is known about potential mixture effects. We aimed to assess associations between dietary pesticide exposure profiles and Type 2 Diabetes (T2D) among NutriNet-Santé cohort participants. METHODS: Participants completed a Food Frequency Questionnaire at baseline, assessing conventional and organic food consumption. Exposures to 25 active substances used in European Union pesticides were estimated using the Chemisches und Veterinäruntersuchungsamt Stuttgart residue database accounting for farming practices. T2D were identified through several sources. Exposure profiles were established using Non-Negative Matrix Factorization (NMF), adapted for sparse data. Cox models adjusted for known confounders were used to estimate hazard ratios (HR) and 95% confidence interval (95% CI), for the associations between four NMF components, divided into quintiles (Q) and T2D risk. RESULTS: The sample comprised 33,013 participants aged 53 years old on average, including 76% of women. During follow-up (median: 5.95 years), 340 incident T2D cases were diagnosed. Positive associations were detected between NMF component 1 (reflecting highest exposure to several synthetic pesticides) and T2D risk on the whole sample: HRQ5vsQ1 = 1.47, 95% CI (1.00, 2.18). NMF Component 3 (reflecting low exposure to several synthetic pesticides) was associated with a decrease in T2D risk, among those with high dietary quality only (high adherence to French dietary guidelines, including high plant foods consumption): HRQ5vsQ1 = 0.31, 95% CI (0.10, 0.94). CONCLUSIONS: These findings suggest a role of dietary pesticide exposure in T2D risk, with different effects depending on which types of pesticide mixture participants are exposed to. These associations need to be confirmed in other types of studies and settings, and could have important implications for developing prevention strategies (regulation, dietary guidelines). TRIAL REGISTRATION: This study is registered in ClinicalTrials.gov ( NCT03335644 ).

Pre- and Postnatal Dietary Exposure to a Pesticide Cocktail Disrupts Ovarian Functions in 8-Week-Old Female Mice.

Female infertility has a multifactorial origin, and exposure to contaminants, including pesticides, with endocrine-disrupting properties is considered to be involved in this reproductive disorder, especially when it occurs during early life. Pesticides are present in various facets of the environment, and consumers are exposed to a combination of multiple pesticide residues through food intake. The consequences of such exposure with respect to female fertility are not well known. Therefore, we aimed to assess the impact of pre- and postnatal dietary exposure to a pesticide mixture on folliculogenesis, a crucial process in female reproduction. Mice were exposed to the acceptable daily intake levels of six pesticides in a mixture (boscalid, captan, chlorpyrifos, thiacloprid, thiophanate and ziram) from foetal development until 8 weeks old. Female offspring presented with decreased body weight at weaning, which was maintained at 8 weeks old. This was accompanied by an abnormal ovarian ultrastructure, a drastic decrease in the number of corpora lutea and progesterone levels and an increase in ovary cell proliferation. In conclusion, this study shows that this pesticide mixture that can be commonly found in fruits in Europe, causing endocrine disruption in female mice with pre- and postnatal exposure by disturbing folliculogenesis, mainly in the luteinisation process.

Estimated dietary pesticide exposure from plant-based foods using NMF-derived profiles in a large sample of French adults.

PURPOSE: This study, conducted in participants of the NutriNet-Santé cohort, aims to identify dietary pesticide exposure profiles (derived from Non-negative Matrix Factorization) from conventional and organic foods among a large sample of general population French adults. METHODS: Organic and conventional dietary intakes were assessed using a self-administered semi-quantitative food frequency questionnaire. Exposure to 25 commonly used pesticides was evaluated using food contamination data from Chemisches und Veterinäruntersuchungsamt Stuttgart accounting for farming system (organic or conventional). Dietary pesticide exposure profiles were identified using Non-Negative Matrix factorization (NMF), especially adapted for non-negative data with excess zeros. The NMF scores were introduced in a hierarchical clustering process. RESULTS: Overall, the identified clusters (N = 34,193) seemed to be exposed to the same compounds with gradual intensity. Cluster 1 displayed the lowest energy intake and estimated dietary pesticide exposure, high organic food (OF) consumption (23.3%) and a higher proportion of male participants than other groups. Clusters 2 and 5 presented intermediate energy intake, lower OF consumption and intermediate estimated pesticide exposure. Cluster 3 showed high conventional fruits and vegetable (FV) intake, high estimated pesticide exposure, and fewer smokers. Cluster 4 estimated pesticide exposure varied more across compounds than for other clusters, with highest estimated exposures for acetamiprid, azadirachtin, cypermethrin, pyrethrins, spinosad. OF proportion in the diet was the highest (31.5%). CONCLUSION: Estimated dietary pesticide exposures appeared to vary across the clusters and to be related to OF proportion in the diet. TRIAL REGISTRATION: Clinical Trial Registry: NCT03335644.

Gene Expression Profiling Reveals that PXR Activation Inhibits Hepatic PPARα Activity and Decreases FGF21 Secretion in Male C57Bl6/J Mice.

The pregnane X receptor (PXR) is the main nuclear receptor regulating the expression of xenobiotic-metabolizing enzymes and is highly expressed in the liver and intestine. Recent studies have highlighted its additional role in lipid homeostasis, however, the mechanisms of these regulations are not fully elucidated. We investigated the transcriptomic signature of PXR activation in the liver of adult wild-type vs. Pxr-/- C57Bl6/J male mice treated with the rodent specific ligand pregnenolone 16α-carbonitrile (PCN). PXR activation increased liver triglyceride accumulation and significantly regulated the expression of 1215 genes, mostly xenobiotic-metabolizing enzymes. Among the down-regulated genes, we identified a strong peroxisome proliferator-activated receptor α (PPARα) signature. Comparison of this signature with a list of fasting-induced PPARα target genes confirmed that PXR activation decreased the expression of more than 25 PPARα target genes, among which was the hepatokine fibroblast growth factor 21 (Fgf21). PXR activation abolished plasmatic levels of FGF21. We provide a comprehensive signature of PXR activation in the liver and identify new PXR target genes that might be involved in the steatogenic effect of PXR. Moreover, we show that PXR activation down-regulates hepatic PPARα activity and FGF21 circulation, which could participate in the pleiotropic role of PXR in energy homeostasis.

Activation of the Constitutive Androstane Receptor induces hepatic lipogenesis and regulates Pnpla3 gene expression in a LXR-independent way.

The Constitutive Androstane Receptor (CAR, NR1I3) has been newly described as a regulator of energy metabolism. A relevant number of studies using animal models of obesity suggest that CAR activation could be beneficial on the metabolic balance. However, this remains controversial and the underlying mechanisms are still unknown. This work aimed to investigate the effect of CAR activation on hepatic energy metabolism during physiological conditions, i.e. in mouse models not subjected to metabolic/nutritional stress. Gene expression profiling in the liver of CAR knockout and control mice on chow diet and treated with a CAR agonist highlighted CAR-mediated up-regulations of lipogenic genes, concomitant with neutral lipid accumulation. A strong CAR-mediated up-regulation of the patatin-like phospholipase domain-containing protein 3 (Pnpla3) was demonstrated. Pnpla3 is a gene whose polymorphism is associated with the pathogenesis of nonalcoholic fatty liver disease (NAFLD) development. This observation was confirmed in human hepatocytes treated with the antiepileptic drug and CAR activator, phenobarbital and in immortalized human hepatocytes treated with CITCO. Studying the molecular mechanisms controlling Pnpla3 gene expression, we demonstrated that CAR does not act by a direct regulation of Pnpla3 transcription or via the Liver X Receptor but may rather involve the transcription factor Carbohydrate Responsive Element-binding protein. These data provide new insights into the regulation by CAR of glycolytic and lipogenic genes and on pathogenesis of steatosis. This also raises the question concerning the impact of drugs and environmental contaminants in lipid-associated metabolic diseases.

Ameliorative effect of vitamin E to mouse dams and their pups following exposure of mothers to chlorpyrifos during gestation and lactation periods.

Pesticides are omnipresent in environment, water, fruits, and vegetables and are considered as risk factors for human health. Consumers are mainly exposed to pesticides through diet, and the main question to be answered concerns the impact of such exposure on health. In this study, we developed a mouse model to mimic consumer exposure. During gestation and lactation periods, the experimental mouse dams (M) received one of the following treatments: (a) diet-free of pesticides; (b) diet enriched with chlorpyrifos (CPF; 44.0 µg kg(-1)); c) diet + oral vitamin E (vit. E; α-tocopherol; 200 mg/kg/mouse); and (d) diet enriched with CPF (44.0 µg/kg + oral vit. E (200 mg/kg/mouse). At weaning, pups (P) and dams were killed, and organs as well as blood samples were collected. Compared with control results, CPF induced alteration of measured parameters (e.g. organ weight, alkaline phosphatase, urea, malondialdehyde, superoxide dismutase, and cholinesterase) either in mouse dams or in their offspring. Also, CPF induced histological impairment in kidney, liver, and ovary. Administration of vit. E in conjunction with CPF clearly alleviated deviation of these parameters than those of control ones. In conclusion, a dietary exposure of mice during gestation and lactation to low dose of CPF led to significant changes in the mother but also in the weaned animals that have not been directly exposed to this pesticide. These biological and histological modifications could be reversed by an oral supplementation of vit. E.

Irreversible thyroid disruption induced after subchronic exposure to hexachlorobenzene in male rats.

Thyroid hormones play a complex role in the toxicity of hexachlorobenzene (HCB) and related compounds. Time-course and dose-response experiments for free- and total thyroxine (T4) and triiodothyronine (T3) plasma levels for thyroid-stimulating hormone (TSH) and thyroid gland histomorphology were determined in male Wistar rats. Also, we examined the possible reversibility of changes noted after removal of HCB. Rats treated with this organochlorine compound resulted in a hypertrophy of the thyroid gland and altered thyroid function by decreasing significantly the levels of total- and free T4 in a dose-dependent manner (total T4: 28 and 51%; free T4: 21 and 37%), and this decrease was seen as early as 21 days and thereafter. Free T3 was also decreased by 21% with the highest dose starting from day 21. No significant changes were observed in the circulating levels of total T3 In response to the decrease of thyroid hormones, a dose-dependent increase of TSH levels (27 and 31%, respectively, for 4 mg and 16 mg/kg of HCB body weight) was observed after 21 days of HCB treatment. We have observed a hypertrophy and hyperplasia of follicular cells and a decrease in colloid volume in histological picture. When HCB was removed and changed by vehicle, the thyroid relative weight and plasma TSH continued to rise and serum thyroid hormones remained suppressed. These findings suggest that subchronic exposure of rats to HCB induced an irreversible hypothyroidism state.

DNA damage and oxidative stress induced at low doses by the fungicide hexachlorobenzene in human intestinal Caco-2 cells.

CONTEXT: Hexachlorobenzene (HCB), a persistent chlorinated organic chemical, could be detected in human tissues in several countries of the world. Human exposure to Persistent Organic Pollutants (POPs) occurring primarily through diet, HCB and its metabolites are therefore supposed to interact directly with intestinal mucosa. OBJECTIVE: The aim of this study was to investigate the possible effects of low doses of HCB on DNA integrity, cellular viability, differentiation and oxidative status in vitro in human colonic carcinoma cell line Caco-2. MATERIALS AND METHODS: Cells were exposed to increasing doses of HCB for 14 days to assess the cytotoxic, genotoxic and oxidative properties of this compound. The involvement of oxidative stress in the observed effects was evaluated by co exposure of Caco-2 cells with HCB and α-tocopherol. RESULTS: Exposure of Caco-2 cells to HCB resulted in a dose-dependent cytotoxicity, DNA damages and alterations of the cell layer integrity and the barrier function. Moreover, exposure of Caco-2 cells to HCB led to an enhancement of H(2)O(2) production and to an increased activity of antioxidant enzymes. In addition, Co exposure of Caco-2 cells to HCB and α-tocopherol reversed the effects observed in cells exposed to HCB alone. CONCLUSION: These results suggested that HCB effects on Caco-2 cells could be linked, at least in part, to its pro-oxidative potential.

Dietary Amino Acid Source Elicits Sex-Specific Metabolic Response to Diet-Induced NAFLD in Mice.

SCOPE: Non-alcoholic fatty liver disease (NAFLD) is a sexually dimorphic disease influenced by dietary factors. Here, the metabolic and hepatic effects of dietary amino acid (AA) source is assessed in Western diet (WD)-induced NAFLD in male and female mice. METHODS AND RESULTS: The AA source is either casein or a free AA mixture mimicking the composition of casein. As expected, males fed a casein-based WD display glucose intolerance, fasting hyperglycemia, and insulin-resistance and develop NAFLD associated with changes in hepatic gene expression and microbiota dysbiosis. In contrast, males fed the AA-based WD show no steatosis, a similar gene expression profile as males fed a control diet, and a distinct microbiota composition compared to males fed a casein-based WD. Females are protected against WD-induced liver damage, hepatic gene expression, and gut microbiota changes regardless of the AA source. CONCLUSIONS: Free dietary AA intake prevents the unhealthy metabolic outcomes of a WD preferentially in male mice.

Pharmacological activation of constitutive androstane receptor induces female-specific modulation of hepatic metabolism.

Background & Aims: The constitutive androstane receptor (CAR) is a nuclear receptor that binds diverse xenobiotics and whose activation leads to the modulation of the expression of target genes involved in xenobiotic detoxification and energy metabolism. Although CAR hepatic activity is considered to be higher in women than in men, its sex-dependent response to an acute pharmacological activation has seldom been investigated. Methods: The hepatic transcriptome, plasma markers, and hepatic metabolome, were analysed in Car+/+ and Car-/- male and female mice treated either with the CAR-specific agonist 1,4-bis[2-(3,5-dichloropyridyloxy)]benzene (TCPOBOP) or with vehicle. Results: Although 90% of TCPOBOP-sensitive genes were modulated in a sex-independent manner, the remaining 10% showed almost exclusive female liver specificity. These female-specific CAR-sensitive genes were mainly involved in xenobiotic metabolism, inflammation, and extracellular matrix organisation. CAR activation also induced higher hepatic oxidative stress and hepatocyte cytolysis in females than in males. Hepatic expression of flavin monooxygenase 3 (Fmo3) was almost abolished and was associated with a decrease in hepatic trimethylamine-N-oxide (TMAO) concentration in TCPOBOP-treated females. In line with a potential role in the control of TMAO homeostasis, CAR activation decreased platelet hyper-responsiveness in female mice supplemented with dietary choline. Conclusions: More than 10% of CAR-sensitive genes are sex-specific and influence hepatic and systemic responses such as platelet aggregation. CAR activation may be an important mechanism of sexually-dimorphic drug-induced liver injury. Impact and implications: CAR is activated by many drugs and pollutants. Its pharmacological activation had a stronger impact on hepatic gene expression and metabolism in females than in males, and had a specific impact on liver toxicity and trimethylamine metabolism. Sexual dimorphism should be considered when testing and/or prescribing xenobiotics known to activate CAR.

Dual-Hit: Glyphosate exposure at NOAEL level negatively impacts birth and glia-behavioural measures in heterozygous shank3 mutants.

The omnipresence of environmental contaminants represents a health danger with ramifications for adverse neurological trajectories. Here, we tested the dual-hit hypothesis that continuous exposure to non-observable adverse effect level (NOAEL) glyphosate from pre-natal to adulthood represents a risk factor for neurological-associated adaptations when in the presence of the heterozygote or homozygote mutation of the Shank3 synaptic gene. Ultrasound analysis of pregnant dams revealed patterns of pre-natal mortality with effects dependent on wild-type, Shank3ΔC/+, or Shank3ΔC/ΔC genotypes exposed to NOAEL glyphosate (GLY) compared to unexposed conditions. The postnatal survival rate was negatively impacted, specifically in Shank3ΔC/+ exposed to GLY. Next, the resulting six groups of pups were tracked into adulthood and analyzed for signs of neuroinflammation and neurological adaptions. Sholl's analysis revealed cortical microgliosis across groups exposed to GLY, with Shank3ΔC/+ mice presenting the most significant modifications. Brain tissues were devoid of astrocytosis, except for the perivascular compartment in the cortex in response to GLY. Distinct behavioral adaptations accompanied these cellular modifications, as locomotion and social preference were decreased in Shank3ΔC/+ mice exposed to GLY. Notably, GLY exposure from weaning did not elicit glial or neurological adaptations across groups, indicating the importance of pre-natal contaminant exposure. These results unveil the intersection between continuous pre-natal to adulthood environmental input and a pre-existing synaptic mutation. In an animal model, NOAEL GLY predominantly impacted Shank3ΔC/+ mice, compounding an otherwise mild phenotype compared to Shank3ΔC/ΔC. The possible relevance of these findings to neurodevelopmental risk is critically discussed, along with avenues for future research.

Obesity promotes fumonisin B1 hepatotoxicity.

Obesity, which is a worldwide public health issue, is associated with chronic inflammation that contribute to long-term complications, including insulin resistance, type 2 diabetes and non-alcoholic fatty liver disease. We hypothesized that obesity may also influence the sensitivity to food contaminants, such as fumonisin B1 (FB1), a mycotoxin produced mainly by the Fusarium verticillioides. FB1, a common contaminant of corn, is the most abundant and best characterized member of the fumonisins family. We investigated whether diet-induced obesity could modulate the sensitivity to oral FB1 exposure, with emphasis on gut health and hepatotoxicity. Thus, metabolic effects of FB1 were assessed in obese and non-obese male C57BL/6J mice. Mice received a high-fat diet (HFD) or normal chow diet (CHOW) for 15 weeks. Then, during the last three weeks, mice were exposed to these diets in combination or not with FB1 (10 mg/kg body weight/day) through drinking water. As expected, HFD feeding induced significant body weight gain, increased fasting glycemia, and hepatic steatosis. Combined exposure to HFD and FB1 resulted in body weight loss and a decrease in fasting blood glucose level. This co-exposition also induces gut dysbiosis, an increase in plasma FB1 level, a decrease in liver weight and hepatic steatosis. Moreover, plasma transaminase levels were significantly increased and associated with liver inflammation in HFD/FB1-treated mice. Liver gene expression analysis revealed that the combined exposure to HFD and FB1 was associated with reduced expression of genes involved in lipogenesis and increased expression of immune response and cell cycle-associated genes. These results suggest that, in the context of obesity, FB1 exposure promotes gut dysbiosis and severe liver inflammation. To our knowledge, this study provides the first example of obesity-induced hepatitis in response to a food contaminant.

The hepatocyte insulin receptor is required to program the liver clock and rhythmic gene expression.

Liver physiology is circadian and sensitive to feeding and insulin. Food intake regulates insulin secretion and is a dominant signal for the liver clock. However, how much insulin contributes to the effect of feeding on the liver clock and rhythmic gene expression remains to be investigated. Insulin action partly depends on changes in insulin receptor (IR)-dependent gene expression. Here, we use hepatocyte-restricted gene deletion of IR to evaluate its role in the regulation and oscillation of gene expression as well as in the programming of the circadian clock in the adult mouse liver. We find that, in the absence of IR, the rhythmicity of core-clock gene expression is altered in response to day-restricted feeding. This change in core-clock gene expression is associated with defective reprogramming of liver gene expression. Our data show that an intact hepatocyte insulin receptor is required to program the liver clock and associated rhythmic gene expression.

ATGL-dependent white adipose tissue lipolysis controls hepatocyte PPARα activity.

In hepatocytes, peroxisome proliferator-activated receptor α (PPARα) orchestrates a genomic and metabolic response required for homeostasis during fasting. This includes the biosynthesis of ketone bodies and of fibroblast growth factor 21 (FGF21). Here we show that in the absence of adipose triglyceride lipase (ATGL) in adipocytes, ketone body and FGF21 production is impaired upon fasting. Liver gene expression analysis highlights a set of fasting-induced genes sensitive to both ATGL deletion in adipocytes and PPARα deletion in hepatocytes. Adipose tissue lipolysis induced by activation of the ß3-adrenergic receptor also triggers such PPARα-dependent responses not only in the liver but also in brown adipose tissue (BAT). Intact PPARα activity in hepatocytes is required for the cross-talk between adipose tissues and the liver during fat mobilization.

Exposure to pesticides and risk of childhood cancer: a meta-analysis of recent epidemiological studies.

OBJECTIVES: The authors performed a meta-analysis of case-control and cohort studies to clarify the possible relationship between exposure to pesticides and childhood cancers. METHODS: Two cohort and 38 case-control studies were selected for the first meta-analysis. After evaluating homogeneity among studies using the Cochran Q test, the authors calculated a pooled meta-OR stratified on each cancer site. The authors then constructed a list of variables believed to play an important role in explaining the relation between parental exposure to pesticide and childhood cancer, and performed a series of meta-analyses. The authors also performed a distinct meta-analysis for three cohort studies with RR data. RESULTS: Meta-analysis of the three cohort studies did not show any positive links between parental pesticide exposure and childhood cancer incidence. However, the meta-analysis of the 40 studies with OR values showed that the risk of lymphoma and leukaemia increased significantly in exposed children when their mother was exposed during the prenatal period (OR=1.53; 95% CI 1.22 to 1.91 and OR=1.48; 95% CI 1.26 to 1.75). The risk of brain cancer was correlated with paternal exposure either before or after birth (OR=1.49; 95% CI 1.23 to 1.79 and OR=1.66; 95% CI 1.11 to 2.49). The OR of leukaemia and lymphoma was higher when the mother was exposed to pesticides (through household use or professional exposure). Conversely, the incidence of brain cancer was influenced by the father's exposure (occupational activity or use of household or garden pesticides). CONCLUSION: Despite some limitations in this study, the incidence of childhood cancer does appear to be associated with parental exposure during the prenatal period.

Differential impact of dose-range glyphosate on locomotor behavior, neuronal activity, glio-cerebrovascular structures, and transcript regulations in zebrafish larvae.

The presence of glyphosate represents a debated ecotoxicological and health risk factor. Here, zebrafish larvae were exposed, from 1.5 to 120 h post-fertilization, to a broad concentration range (0.05-10.000 µg/L) of glyphosate to explore its impact on the brain. We evaluated morphology, tracked locomotor behavior and neurophysiological parameters, examined neuro-glio-vascular cell structures, and outlined transcriptomic outcomes by RNA sequencing. At the concentration range tested, glyphosate did not elicit gross morphological changes. Behavioral analysis revealed a significant decrease in locomotor activity following the exposure to 1000 µg/L glyphosate or higher. In parallel, midbrain electrophysiological recordings indicated abnormal, and variable, spike activity in zebrafish larvae exposed to 1000 µg/L glyphosate. Next, we asked whether the observed neurophysiological outcome could be secondary to brain structural modifications. We used transgenic zebrafish and in vivo 2-photon microscopy to examine, at the cellular level, the effects of the behavior-modifying concentration of 1000 µg/L, comparing to low 0.1 µg/L, and control. We ruled out the presence of cerebrovascular and neuronal malformations. However, microglia morphological modifications were visible at the two glyphosate concentrations, specifically the presence of amoeboid cells suggestive of activation. Lastly, RNAseq analysis showed the deregulation of transcript families implicated in neuronal physiology, synaptic transmission, and inflammation, as evaluated at the two selected glyphosate concentrations. In zebrafish larvae, behavioral and neurophysiological defects occur after the exposure to high glyphosate concentrations while cellular and transcript signatures can be detected in response to low dose. The prospective applicability to ecotoxicology and the possible extension to brain-health vulnerability are critically discussed.

Prospective association between dietary pesticide exposure profiles and postmenopausal breast-cancer risk in the NutriNet-Santé cohort.

BACKGROUND: Some pesticides, used in large quantities in current agricultural practices all over Europe, are suspected of adverse effects on human reproductive health (breast and prostate cancers), through mechanisms of endocrine disruption and possible carcinogenic properties, as observed in agricultural settings. However, evidence on dietary pesticide exposure and breast cancer (BC) is lacking for the general population. We aimed to assess the associations between dietary exposure to pesticides and BC risk among postmenopausal women of the NutriNet-Santé cohort. METHODS: In 2014, participants completed a self-administered semi-quantitative food-frequency questionnaire distinguishing conventional and organic foods. Exposures to 25 active substances used in EU plant-protection products were estimated using a pesticide-residue database accounting for farming practices, from Chemisches und Veterinäruntersuchungsamt Stuttgart, Germany. Non-negative matrix factorization (NMF), adapted for data with excess zeros, was used to establish exposure profiles. The four extracted NMF components' quintiles were introduced into Cox models estimating hazard ratio (HR) and 95% confidence interval (95% CI), adjusted for known confounding factors. RESULTS: A total of 13 149 postmenopausal women were included in the analysis (169 BC cases, median follow-up = 4.83 years). Negative associations between Component 3, reflecting low exposure to synthetic pesticides, and postmenopausal BC risk were found [HRQ5 = 0.57; 95% CI (0.34; 0.93), p-trend = 0.006]. Positive association between Component 1 score (highly correlated to chlorpyrifos, imazalil, malathion, thiabendazole) and postmenopausal BC risk was found specifically among overweight and obese women [HRQ5 = 4.13; 95% CI (1.50; 11.44), p-trend = 0.006]. No associations were detected for the other components. CONCLUSION: These associations suggest a potential role of dietary pesticide exposure on BC risk. Further research is needed to investigate the mechanisms and confirm these results in other populations.

Varying modalities of perinatal exposure to a pesticide cocktail elicit neurological adaptations in mice and zebrafish.

Epidemiological indications connect maternal and developmental presence or exposure to pesticides with an increased risk for a spectrum of neurological trajectories. To provide pre-clinical data in support of this hypothesis, we used two distinct experimental models. First, female and male mice were fed immediately prior to mating, and the resulting pregnant dams were continously fed during gestation and lactation periods using chow pellets containing a cocktail of six pesticides at tolerable daily intake levels. Male and female offspring were then tracked for behavioral and in vivo electrophysiological adaptations. Second, a zebrafish model allowed us to screen toxicity and motor-behavior outcomes specifically associated with the developmental exposure to a low-to-high concentration range of the cocktail and of each individual pesticide. Here, we report anxiety-like behavior in aging male mice maternally exposed to the cocktail, as compared to age and gender matched sham animals. In parallel, in vivo electrocorticography revealed a decrease in gamma (40-80 Hz) and an increase of theta (6-9 Hz) waves, delineating a long-term, age-dependent, neuronal slowing. Neurological changes were not accompanied by brain structural malformations. Next, by using zebrafish larvae, we showed an increase of all motor-behavioral parameters resulting from the developmental exposure to 10 µg/L of pesticide cocktail, an outcome that was not associated with midbrain structural or neurovascular modifications as assessed by in vivo 2-photon microscopy. When screening each pesticide, chlorpyrifos elicited modifications of swimming parameters at 0.1 µg/L, while other components provoked changes from 0.5 µg/L. Ziram was the single most toxic component inducing developmental malformations and mortality at 10 µg/L. Although we have employed non-equivalent modalities and timing of exposure in two dissimilar experimental models, these outcomes indicate that presence of a pesticide cocktail during perinatal periods represents an element promoting behavioral and neurophysiological modifications. The study limitations and the possible pertinence of our findings to ecotoxicology and public health are critically discussed.

The pregnane X receptor drives sexually dimorphic hepatic changes in lipid and xenobiotic metabolism in response to gut microbiota in mice.

BACKGROUND: The gut microbiota-intestine-liver relationship is emerging as an important factor in multiple hepatic pathologies, but the hepatic sensors and effectors of microbial signals are not well defined. RESULTS: By comparing publicly available liver transcriptomics data from conventional vs. germ-free mice, we identified pregnane X receptor (PXR, NR1I2) transcriptional activity as strongly affected by the absence of gut microbes. Microbiota depletion using antibiotics in Pxr+/+ vs Pxr-/- C57BL/6J littermate mice followed by hepatic transcriptomics revealed that most microbiota-sensitive genes were PXR-dependent in the liver in males, but not in females. Pathway enrichment analysis suggested that microbiota-PXR interaction controlled fatty acid and xenobiotic metabolism. We confirmed that antibiotic treatment reduced liver triglyceride content and hampered xenobiotic metabolism in the liver from Pxr+/+ but not Pxr-/- male mice. CONCLUSIONS: These findings identify PXR as a hepatic effector of microbiota-derived signals that regulate the host's sexually dimorphic lipid and xenobiotic metabolisms in the liver. Thus, our results reveal a potential new mechanism for unexpected drug-drug or food-drug interactions. Video abstract.