Organochloride pesticides induced hepatic ABCG5/G8 expression and lipogenesis in Chinese patients with gallstone disease

RISING STARS: Sex differences in toxicant-associated fatty liver disease

Based on biological sex, the consequential health outcomes from exposures to environmental chemicals or toxicants can differ in disease pathophysiology, progression, and severity. Due to basal differences in cellular and molecular processes resulting from sexual dimorphism of organs including the liver and additional factors influencing 'gene-environment' interactions, males and females can exhibit different responses to toxicant exposures. Associations between environmental/occupational chemical exposures and fatty liver disease (FLD) have been well-acknowledged in human epidemiologic studies and their causal relationships demonstrated in experimental models. However, studies related to sex differences in liver toxicology are still limited to draw any inferences on sex-dependent chemical toxicity. The purpose of this review is to highlight the present state of knowledge on the existence of sex differences in toxicant-associated FLD (TAFLD), discuss potential underlying mechanisms driving these differences, implications of said differences on disease susceptibility, and emerging concepts. Chemicals of interest include various categories of pollutants that have been investigated in TAFLD, namely persistent organic pollutants, volatile organic compounds, and metals. Insight into research areas requiring further development is also discussed, with the objective of narrowing the knowledge gap on sex differences in environmental liver diseases. Major conclusions from this review exercise are that biological sex influences TAFLD risks, in part due to (i) toxicant disruption of growth hormone and estrogen receptor signaling, (ii) basal sex differences in energy mobilization and storage, and (iii) differences in chemical metabolism and subsequent body burden. Finally, further sex-dependent toxicological assessments are warranted for the development of sex-specific intervention strategies.

Global footprints of organochlorine pesticides: a pan-global survey

Organochlorine pesticides (OCPs) are ubiquitous environmental contaminants widely used all over the world. These chlorinated hydrocarbons are toxic and often cause detrimental health effects because of their long shelf life and bioaccumulation in the adipose tissues of primates. OCP exposure to humans occurs through skin, inhalation and contaminated foods including milk and dairy products, whereas developing fetus and neonates are exposed through placental transfer and lactation, respectively. In 1960s, OCPs were banned in most developed countries, but because they are cheap and easily available, they are still widely used in most third world countries. The overuse or misuse of OCPs has been rising continuously which pose threats to environmental and human health. This review reports the comparative occurrence of OCPs in human and bovine milk samples around the globe and portrays the negative impacts encountered through the long history of OCP use.

Early-life perfluorooctanoic acid exposure induces obesity in male offspring and the intervention role of chlorogenic acid

Perfluorooctanoic acid (PFOA) is an emerging organic pollutant (EOP) hazardous to human health. Effects of maternal PFOA exposure on offspring as well as the underlying mechanisms remain unclear. In this study, ICR mouse models of gestational low PFOA exposure (0.05 mg/kg/day) were established to investigate the roles on metabolic disorders of offspring. Body weight, body composition, hepatic lipid levels, transcriptome and metabolome were analyzed. Expression of genes related to lipid metabolism, inflammasome formation and gut barrier integrity were measured. Furthermore, oral administration of chlorogenic acid (CGA) (100 mg/kg/day) was performed to observe the rescue effect on lipid disorders caused by PFOA exposure. Our findings demonstrated that gestational exposure to PFOA resulted in obesity, hepatic inflammation, disorders of lipid metabolism, and disruption of gut barrier integrity in male offspring. Notably, these adverse effects were attenuated by CGA supplementation. These data suggested that PFOA exposure during early life stage induced potential risks for later onset of obesity and metabolic disorder which could be ameliorated by CGA treatment.

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.

Insecticide and metal exposures are associated with a surrogate biomarker for non-alcoholic fatty liver disease in the National Health and Nutrition Examination Survey 2003-2004

Non-alcoholic fatty liver disease (NAFLD), the most common form of liver disease, affects over 30% of the US population. Our group and others have previously demonstrated that low-level environmental pollutant exposures were associated with increased odds ratios for unexplained alanine aminotransferase (ALT) elevation, a surrogate biomarker for NAFLD, in the adult National Health and Nutrition Examination Survey (NHANES). However, recently, more sensitive and lower ALT cutoffs have been proposed. The objective of this observational study is to utilize these ALT cutoffs to determine new associations between environmental chemicals and the surrogate NAFLD biomarker. Adult NHANES 2003-2004 participants without viral hepatitis, hemochromatosis, or alcoholic liver disease were analyzed in this cross-sectional study. ALT elevation was defined as > 30 IU/L in men and > 19 IU/L in women. Odds ratios adjusted for potential confounders for ALT elevation were determined across exposure quartiles for 17 pollutant subclasses comprised of 111 individual pollutants. The overall prevalence of ALT elevation was 37.6%. Heavy metal and organochlorine insecticide subclasses were associated with dose-dependent increased adjusted odds ratios for ALT elevation of 1.6 (95% CI 1.2-2.3) and 3.5 (95% CI 2.3-5.5) respectively, for the highest vs. lowest exposure quartiles (p_trend < 0.01). Within these subclasses, increasing whole blood levels of lead and mercury, and lipid-adjusted serum levels of dieldrin, and the chlordane metabolites, heptachlor epoxide, and trans-nonachlor, were associated with increased odds ratios for ALT elevation. In conclusion, organochlorine insecticide, lead, and mercury exposures were associated with ALT elevation and suspected NAFLD in adult NHANES 2003-2004.

Insecticide Exposure and Development of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is the prevalent liver disease resulting from metabolic disorder, which is highly associated with obesity and type 2 diabetes. Emerging evidence has shown that insecticide exposure disrupts lipid and glucose metabolism and results in obesity and type 2 diabetes. However, the potential impact of insecticide exposure on the liver functions related to NAFLD development is largely unknown. Thus, this perspective focused on the current knowledge of the effect of insecticides on the liver functions, particularly lipid and glucose metabolism, as well as other liver functions to correlate insecticide exposure and the development of NAFLD.

Recent advances in understanding and managing cholesterol gallstones

The high prevalence of cholesterol gallstones, the availability of new information about pathogenesis, and the relevant health costs due to the management of cholelithiasis in both children and adults contribute to a growing interest in this disease. From an epidemiologic point of view, the risk of gallstones has been associated with higher risk of incident ischemic heart disease, total mortality, and disease-specific mortality (including cancer) independently from the presence of traditional risk factors such as body weight, lifestyle, diabetes, and dyslipidemia. This evidence points to the existence of complex pathogenic pathways linking the occurrence of gallstones to altered systemic homeostasis involving multiple organs and dynamics. In fact, the formation of gallstones is secondary to local factors strictly dependent on the gallbladder (that is, impaired smooth muscle function, wall inflammation, and intraluminal mucin accumulation) and bile (that is, supersaturation in cholesterol and precipitation of solid crystals) but also to "extra-gallbladder" features such as gene polymorphism, epigenetic factors, expression and activity of nuclear receptors, hormonal factors (in particular, insulin resistance), multi-level alterations in cholesterol metabolism, altered intestinal motility, and variations in gut microbiota. Of note, the majority of these factors are potentially manageable. Thus, cholelithiasis appears as the expression of systemic unbalances that, besides the classic therapeutic approaches to patients with clinical evidence of symptomatic disease or complications (surgery and, in a small subgroup of subjects, oral litholysis with bile acids), could be managed with tools oriented to primary prevention (changes in diet and lifestyle and pharmacologic prevention in subgroups at high risk), and there could be relevant implications in reducing both prevalence and health costs.

Prevention of cholesterol gallstone disease by schaftoside in lithogenic diet-induced C57BL/6 mouse model

Schaftoside (SS) is a bioactive compound present in the Herba Desmodii Styracifolii (DS), a herb that has been used to treat cholelithiasis and urolithiasis in Chinese medicine. Whether SS inhibits cholesterol (Ch) gallstone formation has not been investigated. This study examined the effects of oral intake of SS on Ch gallstone formation in C57BL/6 mice fed a lithogenic diet. The rate of gallstone formation was recorded. Levels of Ch, triglycerides (TG) and bile salts (BS) were measured in the bile and serum. Liver histopathology was examined microscopically, and mRNA expression levels of key genes involved in cholesterol and bile metabolism were determined by qPCR. Mice fed SS were protected against gallstone formation, had increased biliary levels of BS, and reduced biliary Ch levels, resulting in a lower Ch saturation index (CSI). In addition, mice fed SS had lower serum TG and Ch levels, increased mRNA expression of liver X receptor α, ATP binding cassette transporter 5/8 (ABCG5/8), and ileal bile acid binding protein (IBABP) in the ileum, and of farnesoid X receptor and bile salt export protein (BSEP) in the liver and ileum. SS also protected against histologically determined liver damage. Overall, these data indicate that SS protects against Ch gallstone formation in mice, and that the effect is mediated by activation of ileal liver X receptor α and hepatic farnesoid X receptor.

Organochloride pesticides modulated gut microbiota and influenced bile acid metabolism in mice

Organochlorine pesticides (OCPs) can persistently accumulate in body and threaten human health. Bile acids and intestinal microbial metabolism have emerged as important signaling molecules in the host. However, knowledge on which intestinal microbiota and bile acids are modified by OCPs remains unclear. In this study, adult male C57BL/6 mice were exposed to p, p'-dichlorodiphenyldichloroethylene (p, p'-DDE) and β-hexachlorocyclohexane (β-HCH) for 8 weeks. The relative abundance and composition of various bacterial species were analyzed by 16S rRNA gene sequencing. Bile acid composition was analyzed by metabolomic analysis using UPLC-MS. The expression of genes involved in hepatic and enteric bile acids metabolism was measured by real-time PCR. Expression of genes in bile acids synthesis and transportation were measured in HepG2 cells incubated with p, p'-DDE and β-HCH. Our findings showed OCPs changed relative abundance and composition of intestinal microbiota, especially in enhanced Lactobacillus with bile salt hydrolase (BSH) activity. OCPs affected bile acid composition, enhanced hydrophobicity, decreased expression of genes on bile acid reabsorption in the terminal ileum and compensatory increased expression of genes on synthesis of bile acids in the liver. We demonstrated that chronic exposure of OCPs could impair intestinal microbiota; as a result, hepatic and enteric bile acid profiles and metabolism were influenced. The findings in this study draw our attention to the hazards of chronic OCPs exposure in modulating bile acid metabolism that might cause metabolic disorders and their potential to cause related diseases in human.

Organochloride pesticides impaired mitochondrial function in hepatocytes and aggravated disorders of fatty acid metabolism

p,p'-dichlorodiphenyldichloroethylene (p, p'-DDE) and β-hexachlorocyclohexane (β-HCH) were two predominant organochlorine pesticides (OCPs) metabolites in human body associated with disorders of fatty acid metabolism. However, the underlying mechanisms have not been fully clarified. In this study, adult male C57BL/6 mice were exposed to low dose of p, p'-DDE and β-HCH for 8 wk. OCPs accumulation in organs, hepatic fatty acid composition, tricarboxylic acid cycle (TCA) metabolites and other metabolite profiles were analyzed. Expression levels of genes involved in hepatic lipogenesis and β-oxidation were measured. Mitochondrial function was evaluated in HepG2 cells exposed to OCPs. High accumulation of p, p'-DDE and β-HCH was found in liver and damaged mitochondria was observed under electron microscopy. Expression of genes in fatty acid synthesis increased and that in mitochondrial fatty acid β-oxidation decreased in OCPs treatment groups. OCPs changed metabolite profiles in liver tissues, varied hepatic fatty acid compositions and levels of several TCA cycle metabolites. Furthermore, MitoTracker Green fluorescence, ATP levels, mitochondrial membrane potential and OCR decreased in HepG2 cells exposed to OCPs. In conclusion, chronic exposure to OCPs at doses equivalent to internal exposures in humans impaired mitochondrial function, decreased fatty acid β-oxidation and aggravated disorders of fatty acid metabolism.