Triclosan leads to dysregulation of the metabolic regulator FGF21 exacerbating high fat diet-induced nonalcoholic fatty liver disease

Effects of triclosan on lipid metabolism and underlying mechanisms in the cyprinid fish Squalidus argentatus

The ubiquitous presence of the disinfectant triclosan (TCS) has raised global concerns regarding its potential threat to aquatic organisms. However, the effects of TCS on lipid metabolism in fish and its underlying mechanisms remain unclear. This study investigated the effect of environmentally relevant levels of TCS on the lipid metabolism in the cyprinid fish Squalidus argentatus. Our results showed that the lipid metabolism in the cyprinid fish S. argentatus was perturbed by 28-day exposure to TCS, as evidenced by higher levels of lipid accumulation in both the liver and blood. To elucidate the mechanisms underlying toxicity, we evaluated oxidative stress, inflammatory status, and lipase activity in the liver. Our findings indicated increased ROS-specific fluorescence intensity, superoxide dismutase (SOD) activity, and malondialdehyde (MDA) content in the livers of S. argentatus exposed to TCS, suggesting oxidative damage. Additionally, TCS treatment induced the production of proinflammatory cytokines in the liver of S. argentatus exposed to TCS, which suppressed hepatic lipase activity. Intestinal tissue morphology, inflammation, and blood lipopolysaccharide (LPS) levels were also examined. Significant increases in goblet cell count and MDA levels were observed in the intestinal tract. After 28 days of TCS exposure, the serum LPS levels were significantly elevated. 16S rRNA sequencing was conducted to analyze the effects of TCS on the diversity and composition of the intestinal microbiota. Transcriptomic analysis was performed to reveal global molecular alterations following TCS exposure. In conclusion, our results indicate that TCS may disrupt the lipid metabolism in S. argentatus by (i) inducing hepatic oxidative stress and inflammation, which suppress lipoprotein lipase activity, (ii) affecting the production of beneficial metabolites and endotoxins by dysregulating gut microbiota composition, and (iii) altering the expression levels of lipid metabolism-related pathways.

Triclosan exposure causes abnormal bile acid metabolism through IL-1β-NF-κB-Fxr signaling pathway

Triclosan (TCS) is an eminent antibacterial agent. However, extensive usage causes potential health risks like hepatotoxicity, intestinal damage, kidney injury, etc. Existing studies suggested that TCS would disrupt bile acid (BA) enterohepatic circulation, but its toxic mechanism remains unclear. Hence, the current study established an 8-week TCS exposure model to explore its potential toxic mechanism. The results discovered 8 weeks consecutive administration of TCS induced distinct programmed cell death, inflammatory cell activation and recruitment, and excessive BA accumulation in liver. Furthermore, the expression of BA synthesis and transport associated genes were significantly dysregulated upon TCS treatment. Additional mechanism exploration revealed that Fxr inhibition induced by TCS would be the leading cause for unusual BA biosynthesis and transport. Subsequent Fxr up-stream investigation uncovered TCS exposure caused pyroptosis and its associated IL-1β would be the reason for Fxr reduction mediated by NF-κB. NF-κB blocking by dimethylaminoparthenolide ameliorated TCS induced BA disorder which confirmed the contribution of NF-κB in Fxr repression. To sum up, our findings conclud TCS-caused BA disorder is attributed to Fxr inhibition, which is regulated by the IL-1β-NF-κB signaling pathway. Hence, we suggest Fxr would be a potential target for abnormal BA stimulated by TCS and its analogs.

Approaches to nutritional research using organoids; fructose treatment induces epigenetic changes in liver organoids

Nutritional researches have successfully used animal models to gain new insights into nutrient action. However, comprehensive descriptions of their molecular mechanisms of action remain elusive as appropriate in vitro evaluation systems are lacking. Organoid models can mimic physiological structures and reproduce in vivo functions, making them increasingly utilized in biomedical research for a better understand physiological and pathological phenomena. Therefore, organoid modeling can be a powerful approach for to understand the molecular mechanisms of nutrient action. The present study aims to demonstrate the utility of organoids in nutritional research by further investigating the molecular mechanisms responsible for the negative effects of fructose intake using liver organoids. Here, we treated liver organoids with fructose and analyzed their gene expression profiles and DNA methylation levels. Microarray analysis demonstrated that fructose-treated organoids exhibited increased selenoprotein p (Sepp1) gene expression, whereas pyrosequencing assays revealed reduced DNA methylation levels in the Sepp1 region. These results were consistent with observations using hepatic tissues from fructose-fed rats. Conversely, no differences in Sepp1 mRNA and DNA methylation levels were observed in two-dimensional cells. These results suggest that organoids serve as an ideal in vitro model to recapitulate in vivo tissue responses and help to validate the molecular mechanisms of nutrient action compared to conventional cellular models.

Addressing chemically-induced obesogenic metabolic disruption: selection of chemicals for in vitro human PPARα, PPARγ transactivation, and adipogenesis test methods

Whilst western diet and sedentary lifestyles heavily contribute to the global obesity epidemic, it is likely that chemical exposure may also contribute. A substantial body of literature implicates a variety of suspected environmental chemicals in metabolic disruption and obesogenic mechanisms. Chemically induced obesogenic metabolic disruption is not yet considered in regulatory testing paradigms or regulations, but this is an internationally recognised human health regulatory development need. An early step in the development of relevant regulatory test methods is to derive appropriate minimum chemical selection lists for the target endpoint and its key mechanisms, such that the test method can be suitably optimised and validated. Independently collated and reviewed reference and proficiency chemicals relevant for the regulatory chemical universe that they are intended to serve, assist regulatory test method development and validation, particularly in relation to the OECD Test Guidelines Programme. To address obesogenic mechanisms and modes of action for chemical hazard assessment, key initiating mechanisms include molecular-level Peroxisome Proliferator-Activated Receptor (PPAR) α and γ agonism and the tissue/organ-level key event of perturbation of the adipogenesis process that may lead to excess white adipose tissue. Here we present a critical literature review, analysis and evaluation of chemicals suitable for the development, optimisation and validation of human PPARα and PPARγ agonism and human white adipose tissue adipogenesis test methods. The chemical lists have been derived with consideration of essential criteria needed for understanding the strengths and limitations of the test methods. With a weight of evidence approach, this has been combined with practical and applied aspects required for the integration and combination of relevant candidate test methods into test batteries, as part of an Integrated Approach to Testing and Assessment for metabolic disruption. The proposed proficiency and reference chemical list includes a long list of negatives and positives (20 chemicals for PPARα, 21 for PPARγ, and 11 for adipogenesis) from which a (pre-)validation proficiency chemicals list has been derived.

Triclosan administration to humanized UDP-glucuronosyltransferase 1 neonatal mice induces UGT1A1 through a dependence on PPARα and ATF4

Triclosan (TCS) is an antimicrobial toxicant found in a myriad of consumer products and has been detected in human tissues, including breastmilk. We have evaluated the impact of lactational TCS on UDP-glucuronosyltransferase 1A1 (UGT1A1) expression and bilirubin metabolism in humanized UGT1 (hUGT1) neonatal mice. In hUGT1 mice, expression of the hepatic UGT1A1 gene is developmentally delayed resulting in elevated total serum bilirubin (TSB) levels. We found that newborn hUGT1 mice breastfed or orally treated with TCS presented lower TSB levels along with induction of hepatic UGT1A1. Lactational and oral treatment by gavage with TCS leads to the activation of hepatic nuclear receptors constitutive androstane receptor (CAR), peroxisome proliferator-activated receptor alpha (PPARα), and stress sensor, activating transcription factor 4 (ATF4). When CAR-deficient hUGT1 mice (hUGT1/Car-/-) were treated with TCS, TSB levels were reduced with a robust induction of hepatic UGT1A1, leaving us to conclude that CAR is not tied to UGT1A1 induction. Alternatively, when PPARα-deficient hUGT1 mice (hUGT1/Pparα-/-) were treated with TCS, hepatic UGT1A1 was not induced. Additionally, we had previously demonstrated that TCS is a potent inducer of ATF4, a transcriptional factor linked to the integrated stress response. When ATF4 was deleted in liver of hUGT1 mice (hUGT1/Atf4ΔHep) and these mice treated with TCS, we observed superinduction of hepatic UGT1A1. Oxidative stress genes in livers of hUGT1/Atf4ΔHep treated with TCS were increased, suggesting that ATF4 protects liver from excessive oxidative stress. The increase oxidative stress may be associated with superinduction of UGT1A1. The expression of ATF4 in neonatal hUGT1 hepatic tissue may play a role in the developmental repression of UGT1A1.

Triclosan induces liver injury in long-life exposed mice via activation of TLR4/NF-κB/NLRP3 pathway

Triclosan (TCS) is a widely used synthetic, with broad-spectrum antibacterial properties found in both pharmaceuticals and personal care products. More specifically, it is hepatotoxic in rodents and exhibits differential effects in mice and humans. However, the mechanisms underlying TCS-induced liver toxicity have not been elucidated. This study examined the role of the toll-like receptor 4 (TLR4)/ nuclear factor kappa B (NF-κB)/ nod-like receptor protein 3 (NLRP3) pathway in TCS-exposed liver toxicity by established a long-life TCS-exposed mice liver injury model. The 24 C57BL/6 pregnant mice exposed to TCS (0, 50 and 100 mg/kg) every day during the gestation and nursing period. After weaning, the male mice were left to continue administrate with TCS until 8 weeks of age. Then, mice in each group were sacrificed for investigation. Long-life exposure to TCS resulted in a reduction of body weight in growth mice. TCS exposure caused the increase of serum ALT, AST and ALP. The situation of inflammatory cell infiltration, macrophage recruitment and collagen fiber deposition in TCS-exposed mice liver tissues were performed by histological analysis including hematoxylin-eosin, Masson, Sirius red, and immunohistochemistry staining. Protein expression levels in TLR4/NF-κB/NLRP3 pathway was measured through Western blot, and the NLRP3 inflammasome activation was measured using real-time quantitative PCR (RT-qPCR). The results showed that exposure to TCS elevated TLR4, myeloid differentiation factor 88 (Myd88), TNF receptor associated factor 6 (TRAF6), enhanced NF-κB activation, and affected NLRP3 inflammasome activation in mice liver. Collectively, these findings indicate that long-life exposure to TCS-induced mice by upregulating the TLR4-Myd88-TRAF6 pathway, activating the NF-κB signaling cascade, initiating the NLRP3 inflammasome pathway, and ultimately leading to liver injury, including inflammation, hepatocyte pyroptosis and hepatofibrosis. Henceforth, the TLR4/NF-κB/NLRP3 pathway may now provide a theoretical basis and valuable therapeutic targets for overcoming TCS-induced liver toxicity.

Conceptualizing the Role of the Microbiome as a Mediator and Modifier in Environmental Health Studies: A Scoping Review of Studies of Triclosan and the Microbiome

PURPOSE OF REVIEW

Triclosan is an endocrine-disrupting antimicrobial additive that is suspected of contributing to antibiotic resistance and altering the microbiome. In this scoping review, we summarize what is known about the association between triclosan exposure and the microbiome using evidence from in vivo and epidemiologic studies.

RECENT FINDINGS

Our review includes 11 rodent studies, seven fish studies, and five human studies. Evidence from animal studies suggests that triclosan decreases the diversity of the microbiome, although only one epidemiologic study agreed. Most studies suggest that triclosan alters the microbial community beta diversity, but disagree on which taxa contributed to compositional differences. Taxa in the Bacteroidetes, Firmicutes, and Proteobacteria may be more influenced by triclosan than those in other phyla. Studies on triclosan and the microbiome were scarce and were inconclusive as to the effects of triclosan on the microbiome. Additional research is needed to clarify windows of heightened susceptibility of the microbiome to triclosan. We recommend guidelines for future microbiome research in environmental health to increase comparability across studies.

Chronic administration of triclosan leads to liver fibrosis through hepcidin-ferroportin axis-mediated iron overload

Triclosan (TCS) has been manufactured as an antibacterial compound for half a century. Currently, it is widely used in various personal care products; however, its potential adverse effects raise a lot of attention. Here, we create a long-term oral administration mouse model and identify the corresponding hepatotoxicity of TCS. We discover that daily intragastric administration of 10 mg/kg TCS to mice for 12 weeks results in severe hepatic fibrosis. Further study displays that hepatic iron increased 18%, 23% and 29% upon oral TCS treatment for 4, 8 and 12 weeks, respectively. Accompanied by hepatic iron variation, splenic and duodenal iron are increased, which indicates systemic iron disorder. Not only excessive iron accumulated in the liver, abnormal hepatic malondialdehyde, prostaglandin synthase 2 and glutathione peroxidase 4 are pointed to ferroptosis. Additional study uncovers that hepcidin expression increases 7%, 10%, 4% in serum and 2.4-, 4.8-, and 2.3-fold on transcriptional levels upon TCS exposure for 4, 8 and 12 weeks, individually. Taken together, the mice in the TCS-treated group show disordered systemic iron homeostasis via the upregulated hepatic hepcidin-ferroportin axis. Meanwhile, both hepatic iron overload (systemic level) and hepatocyte ferroptosis (cellular level) are accused of TCS-induced liver fibrosis. Ferriprox®, an iron scavenger, significantly ameliorates TCS-induced liver fibrosis. In summary, this study confirms the impact of TCS on liver fibrosis; a critical signal pathway is also displayed. The significance of the current study is to prompt us to reevaluate the "pros and cons" of TCS applications.

Effects of chronic triclosan exposure on nephrotoxicity and gut microbiota dysbiosis in adult mice

Triclosan (TCS), a broad-spectrum, lipophilic, and antibacterial agent, has been commonly used in cosmetics, medical devices, and household products. The toxicity of TCS has recently become a research hotspot. Emerging evidence has shown that TCS can easily migrate to humans and animals and cause adverse effects on various target organs. However, the effects of TCS exposure on nephrotoxicity and underlying mechanisms remain unknown. The aim of the present study was to explore TCS-induced nephrotoxicity. Therefore, we establish a mouse model based on adult male mice to explore the effects of 10-week TCS exposure (50 mg/kg) on kidney. After mice were sacrificed, their blood, feces, and renal tissues were harvested for further analysis. We found that TCS treatment dramatically caused kidney structural damage, and increased blood urea nitrogen (BUN) and creatinine (Cr) expression levels, which indicated renal dysfunction. In addition, TCS exposure increased the malondialdehyde (MDA) and decreased superoxide dismutase (SOD) and total cholesterol (TCHO) expression levels, which indicated oxidative stress and lipid metabolism changes. The RNA sequencing (RNA-seq) of kidney tissue identified 221 differentially expressed genes (DEGs) enriched in 50 pathways, including drug metabolism-other enzymes, oxidative phosphorylation, glutathione metabolism, and inflammatory mediator regulation of TRP channels signaling pathways. The full-length 16S rRNA gene sequencing results showed that TCS exposure altered the community of gut microbiota, which was closely related to renal function damage. The above findings provide new insights into the mechanism of TCS-induced nephrotoxicity.

Chronic triclosan exposure induce impaired glucose tolerance by altering the gut microbiota

Triclosan (TCS) is an antimicrobial compound incorporated into more than 2000 consumer products. This compound is frequently detected in the human body and causes ubiquitous contamination in the environment, thereby raising concerns about its impact on human health and environmental pollution. Here, we demonstrated that 20 weeks' exposure of TCS drove the development of glucose intolerance by inducing compositional and functional alterations in intestinal microbiota in rats. Fecal-transplantation experiments corroborated the involvement of gut microbiota in TCS-induced glucose-tolerance impairment. 16S rRNA gene-sequencing analysis of cecal contents showed that TCS disrupted the gut microbiota composition in rats and increased the ratio of Firmicutes to Bacteroidetes. Cecal metabolomic analyses detected that TCS altered host metabolic pathways that are linked to host glucose and amino acid metabolism, particularly branched-chain amino acid (BCAA) biosynthesis. BCAA measurement confirmed the increase in serum BCAAs in rats exposed to TCS. Western blot and immunostaining results further confirmed that elevated BCAAs stimulated mTOR, a nutrient-sensing complex, and following IRS-1 serine phosphorylation, resulted in insulin resistance and glucose intolerance. These results suggested that TCS may induce glucose metabolism imbalance by regulating BCAA concentration by remodeling the gut microbiota.

Gut microbes in metabolic disturbances. Promising role for therapeutic manipulations?

The prevalence of overweight, obesity, type 2 diabetes, metabolic syndrome and steatotic liver disease is rapidly increasing worldwide with a huge economic burden in terms of morbidity and mortality. Several genetic and environmental factors are involved in the onset and development of metabolic disorders and related complications. A critical role also exists for the gut microbiota, a complex polymicrobial ecology at the interface of the internal and external environment. The gut microbiota contributes to food digestion and transformation, caloric intake, and immune response of the host, keeping the homeostatic control in health. Mechanisms of disease include enhanced energy extraction from the non-digestible dietary carbohydrates, increased gut permeability and translocation of bacterial metabolites which activate a chronic low-grade systemic inflammation and insulin resistance, as precursors of tangible metabolic disorders involving glucose and lipid homeostasis. The ultimate causative role of gut microbiota in this respect remains to be elucidated, as well as the therapeutic value of manipulating the gut microbiota by diet, pre- and pro- synbiotics, or fecal microbial transplantation.

Contribution of the microbiome for better phenotyping of people living with obesity

Obesity has reached epidemic proportion worldwide and in all ages. Available evidence points to a multifactorial pathogenesis involving gene predisposition and environmental factors. Gut microbiota plays a critical role as a major interface between external factors, i.e., diet, lifestyle, toxic chemicals, and internal mechanisms regulating energy and metabolic homeostasis, fat production and storage. A shift in microbiota composition is linked with overweight and obesity, with pathogenic mechanisms involving bacterial products and metabolites (mainly endocannabinoid-related mediators, short-chain fatty acids, bile acids, catabolites of tryptophan, lipopolysaccharides) and subsequent alterations in gut barrier, altered metabolic homeostasis, insulin resistance and chronic, low-grade inflammation. Although animal studies point to the links between an "obesogenic" microbiota and the development of different obesity phenotypes, the translational value of these results in humans is still limited by the heterogeneity among studies, the high variation of gut microbiota over time and the lack of robust longitudinal studies adequately considering inter-individual confounders. Nevertheless, available evidence underscores the existence of several genera predisposing to obesity or, conversely, to lean and metabolically health phenotype (e.g., Akkermansia muciniphila, species from genera Faecalibacterium, Alistipes, Roseburia). Further longitudinal studies using metagenomics, transcriptomics, proteomics, and metabolomics with exact characterization of confounders are needed in this field. Results must confirm that distinct genera and specific microbial-derived metabolites represent effective and precision interventions against overweight and obesity in the long-term.

ATF4 suppresses hepatocarcinogenesis by inducing SLC7A11 (xCT) to block stress-related ferroptosis

BACKGROUND & AIMS

Hepatocellular carcinoma (HCC), a leading cause of cancer-related death, is associated with viral hepatitis, non-alcoholic steatohepatitis (NASH), and alcohol-related steatohepatitis, all of which trigger endoplasmic reticulum (ER) stress, hepatocyte death, inflammation, and compensatory proliferation. Using ER stress-prone MUP-uPA mice, we established that ER stress and hypernutrition cooperate to cause NASH and HCC, but the contribution of individual stress effectors, such as activating transcription factor 4 (ATF4), to HCC and their underlying mechanisms of action remained unknown.

METHODS

Hepatocyte-specific ATF4-deficient MUP-uPA mice (MUP-uPA/Atf4Δhep) and control MUP-uPA/Atf4F/F mice were fed a high-fat diet to induce NASH-related HCC, and Atf4F/F and Atf4Δhep mice were injected with diethylnitrosamine to model carcinogen-induced HCC. Histological, biochemical, and RNA-sequencing analyses were performed to identify and define the role of ATF4-induced solute carrier family 7a member 11 (SLC7A11) expression in hepatocarcinogenesis. Reconstitution of SLC7A11 in ATF4-deficient primary hepatocytes and mouse livers was used to study its effects on ferroptosis and HCC development.

RESULTS

Hepatocyte ATF4 ablation inhibited hepatic steatosis, but increased susceptibility to ferroptosis, resulting in accelerated HCC development. Although ATF4 activates numerous genes, ferroptosis susceptibility and hepatocarcinogenesis were reversed by ectopic expression of a single ATF4 target, Slc7a11, coding for a subunit of the cystine/glutamate antiporter xCT, which is needed for glutathione synthesis. A ferroptosis inhibitor also reduced liver damage and inflammation. ATF4 and SLC7A11 amounts were positively correlated in human HCC and livers of patients with NASH.

CONCLUSIONS

Despite ATF4 being upregulated in established HCC, it serves an important protective function in normal hepatocytes. By maintaining glutathione production, ATF4 inhibits ferroptosis-dependent inflammatory cell death, which is known to promote compensatory proliferation and hepatocarcinogenesis. Ferroptosis inhibitors or ATF4 activators may also blunt HCC onset.

IMPACT AND IMPLICATIONS

Liver cancer or hepatocellular carcinoma (HCC) is associated with multiple aetiologies. Most HCC aetiologies cause hepatocyte stress and death, as well as subsequent inflammation, and compensatory proliferation, thereby accelerating HCCdevelopment. The contribution of individual stress effectors to HCC and their underlying mechanisms of action were heretofore unknown. This study shows that the stress-responsive transcription factor ATF4 blunts liver damage and cancer development by suppressing iron-dependent cell death (ferroptosis). Although ATF4 ablation prevents hepatic steatosis, it also increases susceptibility to ferroptosis, due to decreased expression of the cystine/glutamate antiporter SLC7A11, whose expression in human HCC and NASH correlates with ATF4. These findings reinforce the notion that benign steatosis may be protective and does not increase cancer risk unless accompanied by stress-induced liver damage. These results have important implications for prevention of liver damage and cancer.

Long-term percutaneous triclosan exposure induces thyroid damage in mice: Interpretation of toxicity mechanism from metabolic and proteomic perspectives

Triclosan (TCS) is an antiseptic incorporated in consumer goods and personal care products that can be absorbed via the skin, raising public health concerns for its continuous detection in human biofluids and tissues. Epidemiology has associated TCS exposure with thyroid function disturbances and decreasing serum thyroid hormone (TH) levels, but the underlying mechanism remains unclear. In this study, we revealed hypothyroidism and histological alternation in the thyroid of mice with chronic percutaneous exposure to TCS, indicating a TCS-caused thyroid impairment. Subsequently, multi-omics approaches were performed to investigate the molecular mechanism of the thyroid in response to long-term dermal TCS exposure. We discovered that TCS interfered with the TH synthesis as indicated by the changes in the levels of the synthetic materials for TH (iodide, Tg, and H2O2) and affected TH release by the downregulation of lysosomal enzymes. The upregulation of glycolysis, tricarboxylic acid cycle, fatty acid, amino acid metabolism, and adenine salvage in the thyroid was also observed after TCS exposure. All these changes led to the elevation of ATP, serving as a rescue for the decreasing thyroid functions. Together, our study demonstrated TCS-induced thyroid damage and identified the interrupted pathways, providing meaningful insight into the molecular mechanisms underpinning the potential health influence of TCS in humans.

Adverse effects of triclosan exposure on health and potential molecular mechanisms

With the COVID-19 pandemic, the use of disinfectants has grown significantly around the world. Triclosan (TCS), namely 5-chloro-2-(2,4-dichlorophenoxy) phenol or 2,4,4'-trichloro-2'-hydroxydiphenyl ether, is a broad-spectrum, lipophilic, antibacterial agent that is extensively used in multifarious consumer products. Due to the widespread use and bioaccumulation, TCS is frequently detected in the environment and human biological samples. Accumulating evidence suggests that TCS is considered as a novel endocrine disruptor and may have potential unfavorable effects on human health, but studies on the toxic effect mediated by TCS exposure as well as its underlying mechanisms of action are relatively sparse. Therefore, in this review, we attempted to summarize the potential detrimental effects of TCS exposure on human reproductive health, liver function, intestinal homeostasis, kidney function, thyroid endocrine, and other tissue health, and further explore its mechanisms of action, thereby contributing to the better understanding of TCS characteristics and safety. Moreover, our work suggested the need to further investigate the biological effects of TCS exposure at the metabolic level in vivo.

Chlorothalonil induces obesity in mice by regulating host gut microbiota and bile acids metabolism via FXR pathways

As the most commonly used organochlorine pesticide nowadays, chlorothalonil (CHI), is ubiquitous in a natural environment and poses many adverse effects to organisms. Unfortunately, the toxicity mechanisms of CHI have not been clarified yet. This study found that the CHI based on ADI level could induce obesity in mice. In addition, CHI could induce an imbalance in the gut microbiota of mice. Furthermore, the results of the antibiotic treatment and gut microbiota transplantation experiments showed that the CHI could induce obesity in mice in a gut microbiota-dependent manner. Based on the results of targeted metabolomics and gene expression analysis, CHI could disturb the bile acids (BAs) metabolism of mice, causing the inhibition of the signal response of BAs receptor FXR and leading to glycolipid metabolism disorders in liver and epiWAT of mice. The administration of FXR agonist GW4064 and CDCA could significantly improve the CHI-induced obesity in mice. In conclusion, CHI was found to induce obesity in mice by regulating the gut microbiota and BAs metabolism via the FXR signaling pathway. This study provides evidence linking the gut microbiota and pesticides exposure with the progression of obesity, demonstrating the key role of gut microbiota in the toxic effects of pesticides.

Dachaihu decoction inhibits hypernutrition-induced liver metastasis from colorectal cancer by maintaining the gut vascular barrier

Background

Colorectal cancer (CRC) is the third most common malignancy and the second deadliest cancer worldwide. Metastasis to the liver, the most common metastatic site in CRC, is the leading cause of death in patients with CRC. Hyperlipidemia, which is common in patients with CRC, promotes CRC progression and metastasis. Hyperlipidemia is commonly observed in obese patients and is often induced by hypernutrition. The underlying mechanism of hypernutrition-induced hyperlipidemia in promoting CRC liver metastasis remains unclear, and there is an unmet need for effective and low-cost treatments for patients with CRC.

Methods

A mouse cecum orthotopic CRC model combined with high-fat diet (HFD) feeding, was established to mimic liver metastasis in CRC in obese patients. The effects of Dachaihu decoction (DCHD), a traditional herbal medicine used to treat inflammation and nonalcoholic fatty liver disease, and of the conventional prescription medicine obeticholic acid (OCA) were evaluated. HFD-induced obesity, hyperlipidemia, and CRC liver metastasis were assessed, along with the histology and pathology of the liver and intestine and the expression of metabolic genes in these tissues. The effects of DCHD and OCA on HFD-induced outcomes were evaluated, and human umbilical vein endothelial cells (HUVECs) treated with bile acids (BAs) and DCHD were used to study the underlying mechanisms in vitro.

Results

HFD-mediated obesity and hyperlipidemia promoted CRC metastasis, accompanied by disruption of the gut vascular barrier (GVB) and altered bile acid (BA) metabolism. DCHD decreased HFD-induced hyperlipidemia and liver metastasis in CRC, improving overall survival. Those effects of DCHD were equivalent to or better than those of OCA. DCHD regulated the expression of genes of BA metabolism and tight junctions (TJ) to prevent HFD-induced disruption of the GVB. In HUVECs, DCHD prevented the increases in intracellular Ca2+ and accumulation of reactive oxygen species induced by primary conjugated BAs, assisting in the maintenance of redox homeostasis and preventing the downregulation of TJ proteins, thereby maintaining the integrity of the endothelial barrier.

Conclusions

The data provide a link between hypernutrition and GVB disruption, which contributes to high liver metastasis in patients with CRC. DCHD may represent a novel therapy in CRC, and targeting abnormal lipid metabolism could be a promising therapeutic strategy for avoiding hypernutrition-associated CRC metastasis.

Association between environmental phenols and all-cause and cancer mortality

To study the association between environmental phenols exposure, including benzophenone-3 (BP3) and triclosan, and all-cause mortality and cancer mortality in adults. A total of 8035 participants were included from the National Health and Nutrition Examination Survey (2003-2012). Urinary BP3 and triclosan were measured with liquid chromatography-tandem mass spectrometry. The associations between urinary BP3 and triclosan with cancer and all-cause mortality were explored by multivariable logistic regressions and restricted cubic splines. During an average of 7.25-year follow-up, 696 cases (8.7%) of all-cause mortality and 137 cases (1.71%) of cancer mortality occurred. The average levels of BP3 and triclosan were 12.2 and 10.3 ng/mL, respectively. Compared with the lowest quartile, the multivariable-adjusted hazard ratio of the highest quartile was 0.64 (95% confidence interval: 0.50 to 0.81; P < 0.001) for BP3 and 0.76 (0.61 to 0.94; P = 0.011) for triclosan. However, no significant associations between urinary BP3 and triclosan and cancer mortality were observed. BP3 and triclosan exposure decreased the risk of all-cause mortality while they were not associated with cancer mortality.

Single-cell transcriptomic dissection of the cellular and molecular events underlying the triclosan-induced liver fibrosis in mice

BACKGROUND

Triclosan [5-chloro-2-(2,4-dichlorophenoxy) phenol, TCS], a common antimicrobial additive in many personal care and health care products, is frequently detected in human blood and urine. Therefore, it has been considered an emerging and potentially toxic pollutant in recent years. Long-term exposure to TCS has been suggested to exert endocrine disruption effects, and promote liver fibrogenesis and tumorigenesis. This study was aimed at clarifying the underlying cellular and molecular mechanisms of hepatotoxicity effect of TCS at the initiation stage.

METHODS

C57BL/6 mice were exposed to different dosages of TCS for 2 weeks and the organ toxicity was evaluated by various measurements including complete blood count, histological analysis and TCS quantification. Single cell RNA sequencing (scRNA-seq) was then carried out on TCS- or mock-treated mouse livers to delineate the TCS-induced hepatotoxicity. The acquired single-cell transcriptomic data were analyzed from different aspects including differential gene expression, transcription factor (TF) regulatory network, pseudotime trajectory, and cellular communication, to systematically dissect the molecular and cellular events after TCS exposure. To verify the TCS-induced liver fibrosis, the expression levels of key fibrogenic proteins were examined by Western blotting, immunofluorescence, Masson's trichrome and Sirius red staining. In addition, normal hepatocyte cell MIHA and hepatic stellate cell LX-2 were used as in vitro cell models to experimentally validate the effects of TCS by immunological, proteomic and metabolomic technologies.

RESULTS

We established a relatively short term TCS exposure murine model and found the TCS mainly accumulated in the liver. The scRNA-seq performed on the livers of the TCS-treated and control group profiled the gene expressions of > 76,000 cells belonging to 13 major cell types. Among these types, hepatocytes and hepatic stellate cells (HSCs) were significantly increased in TCS-treated group. We found that TCS promoted fibrosis-associated proliferation of hepatocytes, in which Gata2 and Mef2c are the key driving TFs. Our data also suggested that TCS induced the proliferation and activation of HSCs, which was experimentally verified in both liver tissue and cell model. In addition, other changes including the dysfunction and capillarization of endothelial cells, an increase of fibrotic characteristics in B plasma cells, and M2 phenotype-skewing of macrophage cells, were also deduced from the scRNA-seq analysis, and these changes are likely to contribute to the progression of liver fibrosis. Lastly, the key differential ligand-receptor pairs involved in cellular communications were identified and we confirmed the role of GAS6_AXL interaction-mediated cellular communication in promoting liver fibrosis.

CONCLUSIONS

TCS modulates the cellular activities and fates of several specific cell types (including hepatocytes, HSCs, endothelial cells, B cells, Kupffer cells and liver capsular macrophages) in the liver, and regulates the ligand-receptor interactions between these cells, thereby promoting the proliferation and activation of HSCs, leading to liver fibrosis. Overall, we provide the first comprehensive single-cell atlas of mouse livers in response to TCS and delineate the key cellular and molecular processes involved in TCS-induced hepatotoxicity and fibrosis.

Comprehensive insight into triclosan-from widespread occurrence to health outcomes

Humans are exposed to the variety of emerging environmental pollutant in everyday life. The special concern is paid to endocrine disrupting chemicals especially to triclosan which could interfere with normal hormonal functions. Triclosan could be found in numerous commercial products such as mouthwashes, toothpastes and disinfectants due to its antibacterial and antifungal effects. Considering the excessive use and disposal, wastewaters are recognized as the main source of triclosan in the aquatic environment. As a result of the incomplete removal, triclosan residues reach surface water and even groundwater. Triclosan has potential to accumulate in sediment and aquatic organisms. Therefore, the detectable concentrations of triclosan in various environmental and biological matrices emerged concerns about the potential toxicity. Triclosan impairs thyroid homeostasis and could be associated with neurodevelopment impairment, metabolic disorders, cardiotoxicity and the increased cancer risk. The growing resistance of the vast groups of bacteria, the evidenced toxicity on different aquatic organisms, its adverse health effects observed in vitro, in vivo as well as the available epidemiological studies suggest that further efforts to monitor triclosan toxicity at environmental levels are necessary. The safety precaution measures and full commitment to proper legislation in compliance with the environmental protection are needed in order to obtain triclosan good ecological status. This paper is an overview of the possible negative triclosan effects on human health. Sources of exposure to triclosan, methods and levels of detection in aquatic environment are also discussed.

Optimized Antimicrobial Peptide Jelleine-I Derivative Br-J-I Inhibits Fusobacterium Nucleatum to Suppress Colorectal Cancer Progression

Colorectal cancer (CRC) is a major health burden worldwide due to its high morbidity, mortality, and complex etiology. Fusobacterium nucleatum (Fn), a Gram-negative anaerobe found in 30% of CRC patients, promotes CRC carcinogenesis, metastasis, and chemoresistance. Effective antimicrobial treatment is an unmet need for the rising CRC burden. Antimicrobial peptides (AMPs) represent a new class of antimicrobial drugs. In our previous study, we did the structure-activity study of Jelleine-I (J-I) and identified several halogenated J-I derivatives Cl-J-I, Br-J-I, and I-J-I. To determine whether those J-I derivatives can be a new therapy for bacterial-associated CRC, here we tested the antibacterial activities of these AMPs against Fn and their effects on CRC development. We found that Br-J-I showed the highest anti-Fn activity and Br-J-I may target membrane-associated FadA for Fn membrane disruption. More importantly, Fn promoted the growth of CRC cells-derived xenograft tumors. Br-J-I suppressed Fn load, colon inflammation, and Fn-induced CRC growth. Of note, Br-J-I induced better anti-CRC effects than common antibiotic metronidazole and Br-J-I sensitized the cancer-killing effect of chemotherapy drug 5-fluorouracil. These results suggest that Br-J-I could be considered as an adjunctive agent for CRC treatment and AMPs-based combination treatment is a new strategy for CRC in the future.

Triclosan is associated with breast cancer via oxidative stress and relative telomere length

Introduction

Triclosan (TCS), a widely prescribed broad-spectrum antibacterial agent, is an endocrine-disrupting chemical. The relationship and biological mechanisms between TCS exposure and breast cancer (BC) are disputed. We aimed to examine the correlation between urinary TCS exposure and BC risk and estimated the mediating effects of oxidative stress and relative telomere length (RTL) in the above association.

Methods

This case-control study included 302 BC patients and 302 healthy individuals in Wuhan, China. We detected urinary TCS, three common oxidative stress biomarkers [8-hydroxy-2-deoxyguanosine (8-OHdG), 8-iso-prostaglandin F_2α (8-isoPGF_2α), 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)], and RTL in peripheral blood mononuclear cells.

Results

Significant associations were observed between log-transformed urinary concentrations of TCS, 8-OHdG, HNE-MA, 8-isoPGF_2α, RTL, and BC risk, with the odds ratios (95% confidence intervals) being 1.58 (1.32-1.91), 3.08 (1.55-6.23), 3.39 (2.45-4.77), 3.99 (2.48-6.54), and 1.67 (1.35-2.09), respectively. Continuous TCS exposure was significantly positively correlated with RTL, HNE-MA, and 8-isoPGF_2α (all p<0.05) but not with 8-OHdG (p = 0.060) after adjusting for covariates. The mediated proportions of 8-isoPGF2_2α and RTL in the relationship between TCS and BC risk were 12.84% and 8.95%, respectively (all p<0.001).

Discussion

In conclusion, our study provides epidemiological evidence to confirmed the deleterious effects of TCS on BC and indicated the mediating effect of oxidative stress and RTL on the correlation between TCS and BC risk. Moreover, exploring the contribution of TCS to BC can clarify the biological mechanisms of TCS exposure, provide new clues for the pathogenesis of BC, which is of great significance to improving public health systems.

Occurrence and distribution of triclosan and its transformation products in Taihu Lake, China

The transformation products of triclosan (5-chloro-2-(2,4-dichlorophenoxy)phenol) may be more persistent and toxic than their parent compound, yet their occurrence in aquatic environments is poorly understood. In this study, we identified three transformation products in sediment samples from Taihu Lake and compared their concentrations with the parent compound triclosan. Triclosan in Taihu Lake was at low level, ranging from 0.086 to 1.1 ng/L in surface water and 0.0058-8.3 ng/g in sediments. The three detected transformation products included methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives. Those transformation products constituted 0.73-87.5% of the total triclosan (total triclosan is the sum of triclosan, methyl triclosan, chlorinated triclosan derivatives, and methyl chlorinated triclosan derivatives on a molar basis), indicating that the ecological risk of transformation products should be considered in addition to the parent compound. Different transformation products had distinct spatial distributions. Chlorinated triclosan derivatives had the highest concentration in samples from the northwest region (0.016-0.21 ng/g) of the lake and were positively correlated with triclosan, which may indicate the possible transformation from triclosan to chlorinated triclosan derivatives. Methyl triclosan and methyl chlorinated triclosan derivatives were generally higher in samples from the center of the lake (0.22-0.28 ng/g for methyl triclosan and 0.017-0.021 ng/g for methyl chlorinated triclosan derivatives, respectively), indicating the possible occurrence of in situ microbial methylation of triclosan and chlorinated triclosan derivatives and the accumulation of those methylated analogues in Taihu Lake.

Effects of chemical mixtures on liver function biomarkers in the Korean adult population: thresholds and molecular mechanisms for non-alcoholic fatty liver disease involved

There is a scarcity of research on the effects of a mixture of chemicals on liver function biomarkers and non-alcoholic fatty liver disease (NAFLD) indices, including FSI, HIS, and FBI-4. Thus, we aimed to explore whether there is an association between chemical mixtures, including 26 chemicals found in blood and urine, liver function biomarkers, and non-alcoholic fatty liver disease (NAFLD) indices in Korean adults. The effects of exposure to chemical mixtures on liver function biomarkers and NAFLD indices were investigated using linear regression models, weighted quantile sum (WQS) regression, quantile g-computation (qgcomp), and Bayesian kernel machine regression (BKMR) among 3669 adults. In silico toxicogenomic data-mining, we evaluated molecular mechanisms associated with NAFLD, including pathways, diseases, genes, miRNAs, and biological processes. The linear regression models showed blood or urine Hg levels were the most important factors associated with AST, ALT, GGT, FSI, and HSI levels, and significant trends were observed for these chemical quartiles (p < 0.01). The WQS index was significantly associated with ALT, GGT, FSI, and HSI. The qgcomp index also found an association between chemicals and AST, ALT, GGT, and FSI. In the BKMR model, the overall effect of the mixture was significantly related to ALT, GGT, FSI, and HSI. In silico analysis, we found mixed chemicals interacted with the CYP1A2 gene and were associated with NAFLD. Seventy-eight percent of interactions were identified as physical interactions in the CYP1A2 gene related to NAFLD. Transcription factor regulation in adipogenesis and lipid metabolic processes are fundamental molecular mechanisms that could be influenced by NAFLD-related mixed chemicals. Cutoff thresholds for chemical exposure levels associated with liver function indicators and NAFLD indices were also reported. The strongest interactions and expression of miRNAs involved in NAFLD development were also identified.

Three-Dimensional Mass Spectrometry Imaging Reveals Distributions of Lipids and the Drug Metabolite Associated with the Enhanced Growth of Colon Cancer Cell Spheroids Treated with Triclosan

The application of mass spectrometry imaging (MSI) to explore the responses of cancer cell spheroids (CCS) after treatment of exogenous molecules has attracted growing attention. Increasing studies have utilized MSI to image the two-dimensional distributions of exogenous and endogenous molecules in planar CCS sections. However, because CCS are volumetric and heterogenous, maintaining their three-dimensional (3D) information is essential for acquiring a better understanding of the tumor microenvironment and mechanisms of action of exogenous molecules. Here, an established method of 3D MSI was applied to distinguish the distributions of triclosan sulfate and endogenous lipids in three microregions of colon CCS with an enhanced growth induced by the treatment of triclosan, a common antimicrobial agent. The results of 3D MSI showed that triclosan sulfate gradually accumulated from the periphery to the entire structure of CCS and finally localized in the core region. Spatial lipidomics analysis revealed that the upregulated phosphatidylethanolamine (fold change (FD) = 1.26, p = 0.0021), phosphatidylinositol (FD = 1.17, p = 0.0180), and phosphatidylcholine (FD = 1.22, p = 0.0178) species mainly distributed in the outer proliferative region, while the upregulated sphingomyelin (FD = 1.18, p = 0.024) species tended to distribute in the inner necrotic region. Our results suggest that a competitive mechanism between inhibiting and promoting CCS growth might be responsible for the proliferation of CCS treated with triclosan.

Characterization of triclosan-induced hepatotoxicity and triclocarban-triggered enterotoxicity in mice by multiple omics screening

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether, TCS) and triclocarban (3,4,4'-trichloro-carbanilide, TCC) are two antimicrobial agents commonly used for personal care products. Previous studies primarily focused on respective harmful effects of TCS and TCC. In terms of their structural similarities and differences, however, the structure-toxicity relationships on health effects of TCS and TCC exposure remain unclear. Herein, global ¹H NMR-based metabolomics was employed to screen the changes of metabolic profiling in various biological matrices including liver, serum, urine, feces and intestine of mice exposed to TCS and TCC at chronic and acute dosages. Metagenomics was also applied to analyze the gut microbiota modulation by TCS and TCC exposure. Targeted MS-based metabolites quantification, histopathological examination and biological assays were subsequently conducted to supply confirmatory information on respective toxicity of TCS and TCC. We found that oral administration of TCS mainly induced significant liver injuries accompanied with inflammation and dysfunction, hepatic steatosis fatty acids and bile acids metabolism disorders; while TCC exposure caused marked intestine injuries leading to striking disruption of colonic morphology, inflammatory status and intestinal barrier integrity, intestinal bile acids metabolism and microbial community. These comparative results provide novel insights into structure-dependent mechanisms of TCS-induced hepatotoxicity and TCC-triggered enterotoxicity in mice.

Bibliometric Analysis: The Effects of Triclosan on Human Health

Triclosan (TCS) is a widely used chemical whose effects on human health remains elusive. TCS may play a role in a variety of health issues, including endocrine dysfunction, irregular embryonic development, and immune suppression. It is possible that TCS's penetrative abilities across all body barriers, including the blood-brain barrier, may make bioaccumulation the primary driver of these issues. In addition, chronic overuse of this chemical in everyday life may further contribute to the already increasing problem of antibiotic resistance. TCS research has steadily increased since its transition from medical to commercial use over the last 50 years. However, there are some clear gaps in the depth of this research as the safety of this agent is not fully agreed upon. The Food and Drug Administration recently issued regulatory rules regarding TCS in some commercial products; however, it is still found in a variety of goods marketed as "antimicrobial" or "antibacterial". The purpose of this bibliometric study is to analyze research trends in this field and determine the amount of global attention TCS has received as to its relevancy in human health. Documenting and determining research concentration trends related to this field may outline where additional research is most necessary, as well as demonstrate the most valuable research produced and its relation to the advancement of our understanding of TCS. We found there to be a shift in research from TCS and its role in medical environments, to research based on the indirect effects of TCS through environmental contaminations, such as the propagation of antibiotic resistance. This shift was coupled with an increase in global research related to this field and identified China as a significant contributor. Although TCS has received notice, the simple fact of its continued use in so many common products, as well as the unclear understanding of its direct health impacts, reinforces the need for additional and more conclusive research before it has possible irreversible effects on our environment and health.

Lactational delivery of Triclosan promotes non-alcoholic fatty liver disease in newborn mice

Here we show that Triclosan (TCS), a high-volume antimicrobial additive that has been detected in human breastmilk, can be efficiently transferred by lactation to newborn mice, causing significant fatty liver (FL) during the suckling period. These findings are relevant since pediatric non-alcoholic fatty liver disease (NAFLD) is escalating in the United States, with a limited mechanistic understanding. Lactational delivery stimulated hepatosteatosis, triglyceride accumulation, endoplasmic reticulum (ER) stress, signs of inflammation, and liver fibrosis. De novo lipogenesis (DNL) induced by lactational TCS exposure is shown to be mediated in a PERK-eIF2α-ATF4-PPARα cascade. The administration of obeticholic acid (OCA), a potent FXR agonist, as well as activation of intestinal mucosal-regenerative gp130 signaling, led to reduced liver ATF4 expression, PPARα signaling, and DNL when neonates were exposed to TCS. It is yet to be investigated but mother to child transmission of TCS or similar toxicants may underlie the recent increases in pediatric NAFLD.

Candidate Proficiency Test Chemicals to Address Industrial Chemical Applicability Domains for in vitro Human Cytochrome P450 Enzyme Induction

Cytochrome P450 (CYP) enzymes play a key role in the metabolism of both xenobiotics and endogenous chemicals, and the activity of some CYP isoforms are susceptible to induction and/or inhibition by certain chemicals. As CYP induction/inhibition can bring about significant alterations in the level of in vivo exposure to CYP substrates and metabolites, CYP induction/inhibition data is needed for regulatory chemical toxicity hazard assessment. On the basis of available human in vivo pharmaceutical data, a draft Organisation for Economic Co-operation and Development Test Guideline (TG) for an in vitro CYP HepaRG test method that is capable of detecting the induction of four human CYPs (CYP1A1/1A2, 2B6, and 3A4), has been developed and validated for a set of pharmaceutical proficiency chemicals. However to support TG adoption, further validation data was requested to demonstrate the ability of the test method to also accurately detect CYP induction mediated by industrial and pesticidal chemicals, together with an indication on regulatory uses of the test method. As part of "GOLIATH", a European Union Horizon-2020 funded research project on metabolic disrupting chemical testing approaches, work is underway to generate supplemental validated data for an additional set of chemicals with sufficient diversity to allow for the approval of the guideline. Here we report on the process of proficiency chemical selection based on a targeted literature review, the selection criteria and considerations required for acceptance of proficiency chemical selection for OECD TG development (i.e. structural diversity, range of activity, relevant chemical sectors, global restrictions etc). The following 13 proposed proficiency chemicals were reviewed and selected as a suitable set for use in the additional validation experiments: tebuconazole, benfuracarb, atrazine, cypermethrin, chlorpyrifos, perfluorooctanoic acid, bisphenol A, N,N-diethyl-m-toluamide, benzo-[a]-pyrene, fludioxonil, malathion, triclosan, and caffeine. Illustrations of applications of the test method in relation to endocrine disruption and non-genotoxic carcinogenicity are provided.

The role of microbiota in nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is the most frequent liver disease worldwide. Gut microbiota can play a role in the pathogenesis of NAFLD since dysbiosis is associated with reduced bacterial diversity, altered Firmicutes/Bacteroidetes ratio, a relative abundance of alcohol-producing bacteria, or other specific genera. Changes can promote disrupted intestinal barrier and hyperpermeability, filtration of bacterial products, activation of the immune system, and pro-inflammatory changes in the intestine, in the liver, and at a systemic level. Microbiota-derived molecules can contribute to the steatogenic effects. The link between gut dysbiosis and NAFLD, however, is confused by several factors which include age, BMI, comorbidities, dietary components, and lifestyle. The role of toxic chemicals in food and water requires further studies in both gut dysbiosis and NAFLD. We can anticipate that gut microbiota manipulation will represent a potential therapeutic tool to delay or reverse the progression of NAFLD, paving the way to primary prevention measures.

Triclosan activates c-Jun/miR-218-1-3p/SLC35C1 signaling to regulate cell viability, migration, invasion and inflammatory response of trophoblast cells in vitro

BACKGROUND

Spontaneous abortion is considered as the commonest complication of pregnancy. Triclosan (TCS) is an antimicrobial agent, which participates in the process of multiple human diseases, including spontaneous abortion. Our study aimed to evaluate the effect of TCS on spontaneous abortion and disclose the possible regulatory mechanism in vitro.

RESULTS

RT-qPCR analyzed that miR-218-1-3p derived from abortion-associated factor slit guidance ligand 2 (SLIT2) was up-regulated in trophoblast cells under TCS treatment. Supported by western blot analysis, functional experiments demonstrated that miR-218-1-3p overexpression impeded the proliferation, migration and invasion while exacerbating the inflammatory response of trophoblast cells. Moreover, mechanism assays revealed that TCS modulated c-Jun production to promote MIR218-1 transcription and enhance miR-218-1-3p expression. Moreover, solute carrier family 35 member C1 (SLC35C1) was validated as a target gene of miR-218-1-3p, and miR-218-1-3p was sustained to negatively modulate SLC35C1 expression in trophoblast cells. Rescue assays validated the role of TCS/miR-218-1-3p/SLC35C1 axis in regulating the viability, migration, invasion and inflammatory response of trophoblast cells.

CONCLUSIONS

TCS regulated miR-218-1-3p/SLC35C1 axis to modulate the proliferation, migration, invasion and inflammatory response of trophoblast cells in vitro, which might provide novel insights for spontaneous abortion prevention.

Comparison of toxicological effects and exposure levels between triclosan and its structurally similar chemicals using in vitro tests for read-across case study

Read-across based on structural and biological similarities is expected to be a promising alternative method for assessing systemic toxicity. A concrete strategy for quantitative chemical risk assessment would be to stack read-across case studies and extract key considerations from them. Thus, we developed a read-across case study by comparing the toxicological effects based on adverse outcome pathways and exposure levels of different structurally similar chemicals for a target organ. In this study, we selected the hepatotoxicity of triclosan and its structurally similar chemicals including diclosan and 1-chloro-3-(4-chlorophenoxy)benzene. The results of in vitro toxicogenomics showed that disorders of cholesterol synthesis were commonly detected with both triclosan and diclosan. The decrease in hepatocellular cholesterol levels was similar in the cells treated with triclosan and diclosan. Furthermore, the exposure levels of triclosan and diclosan for the liver were similar. Collectively, these results suggest that triclosan and diclosan show similar toxicological effects and severity of hepatotoxicity. Considering the existing repeated dose toxicity data, our prediction results are reasonable regarding the toxicological effect and its severity. Thus, the present study demonstrated the usability of comparing toxicological effects and exposure levels using read-across for quantitative chemical risk assessment.

Obesity II: Establishing causal links between chemical exposures and obesity

Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.

Triclosan targeting of gut microbiome ameliorates hepatic steatosis in high fat diet-fed mice

Antibiotic use provides a promising strategy for the treatment of non-alcoholic fatty liver disease (NAFLD) by regulating the gut microbiota composition. Triclosan, a widely used antibiotic, may improve gut microbiome dysbiosis associated with NAFLD through the suppression of pathogenic gram-negative bacteria. However, the effects of triclosan on gut microbiota and hepatic steatosis and have not been explored in NAFLD mouse model. In this study, C57BL/6J mice were fed with high fat diet (HFD) for continuous 20 weeks and treated with triclosan at 400 mg/kg/d for 8 weeks from week 13. We explored the effects of triclosan on hepatic lipid accumulation and gut microbiome in HFD-fed mice by histological examination and 16 S ribosomal RNA sequencing, respectively. Analysis on the composition of gut microbiota indicated that triclosan suppressed pathogenic gram-negative bacteria, including Helicobacter, Erysipelatoclostridium and Citrobacter, and increased the ratio of Bacteroidetes/Firmicutes in HFD-fed mice. Meanwhile, triclosan increased the relative abundance of beneficial gut microbiomes including Lactobacillus, Bifidobacterium and Lachnospiraceae, which protected against metabolic abnormality. The results of alpha-diversity and beta-diversity also showed the improvement of triclosan on bacterial diversity and richness in HFD-fed mice. Pathway analysis further confirmed that triclosan can regulate nutrient and energy metabolism through the elimination of deleterious bacteria. As a result, triclosan intervention significantly reduced lipid accumulation and alleviated hepatic steatosis in HFD-fed mice. In conclusion, our results suggest that triclosan can alleviate liver steatosis in HFD-fed mice by targeting the gut microbiome.

The Presence of Triclosan in Human Hair Samples in Poland-A Pilot Study

Triclosan (TCS) is an organic substance showing antibacterial action, which is commonly used in many branches of industry, including, among others, cosmetics, pharmaceuticals and the food industry. TCS may penetrate into living organisms and negatively affect the health of humans and animals. The majority of previous investigations on TCS biomonitoring in humans have been performed on urine, but currently, studies on hair samples are becoming increasingly important. The aim of this study was to evaluate TCS concentration levels in residents of Olsztyn, a city in northeastern Poland, using a liquid chromatography-mass spectrometry technique. The presence of TCS was observed in 96.7% of samples tested, with concentration levels from 37.9 pg/mg to 3386.5 pg/mg. The mean concentration level of TCS in the present study was 402.6 (±803.6) pg/mg, and the median value was 103.3 pg/mg. Although there were some differences in TCS concentration levels between males and females, humans of various ages and humans with colored and natural hair had no statistically significant differences in TCS concentration levels. The obtained results have clearly indicated that people living in northeastern Poland are exposed to TCS to a large degree, and hair analysis, despite some limitations, is a suitable method for TCS biomonitoring in humans.

A Mixture of Endocrine Disrupting Chemicals Associated with Lower Birth Weight in Children Induces Adipogenesis and DNA Methylation Changes in Human Mesenchymal Stem Cells

Endocrine Disrupting Chemicals (EDCs) are man-made compounds that alter functions of the endocrine system. Environmental mixtures of EDCs might have adverse effects on human health, even though their individual concentrations are below regulatory levels of concerns. However, studies identifying and experimentally testing adverse effects of real-life mixtures are scarce. In this study, we aimed at evaluating an epidemiologically identified EDC mixture in an experimental setting to delineate its cellular and epigenetic effects. The mixture was established using data from the Swedish Environmental Longitudinal Mother and child Asthma and allergy (SELMA) study where it was associated with lower birth weight, an early marker for prenatal metabolic programming. This mixture was then tested for its ability to change metabolic programming of human mesenchymal stem cells. In these cells, we assessed if the mixture induced adipogenesis and genome-wide DNA methylation changes. The mixture increased lipid droplet accumulation already at concentrations corresponding to levels measured in the pregnant women of the SELMA study. Furthermore, we identified differentially methylated regions in genes important for adipogenesis and thermogenesis. This study shows that a mixture reflecting human real-life exposure can induce molecular and cellular changes during development that could underlie adverse outcomes.

Effects of chronic triclosan exposure on social behaviors in adult mice

Triclosan (TCS), a newly identified environmental endocrine disruptor (EED) in household products, has been reported to have toxic effects on animals and humans. The effects of TCS exposure on individual social behaviors and the potential underlying mechanisms are still unknown. This study investigated the behavioral effects of 42-day exposure to TCS (0, 50, 100 mg/kg) in drinking water using the open field test (OFT), social dominance test (SDT), social interaction test (SIT), and novel object recognition task (NOR). Using 16S rRNA sequencing analysis and transmission electron microscopy (TEM), we observed the effects of TCS exposure on the gut microbiota and ultrastructure of hippocampal neurons and synapses. Behavioral results showed that chronic TCS exposure reduced the social dominance of male and female mice. TCS exposure also reduced social interaction in male mice and impaired memory formation in female mice. Analysis of the gut microbiota showed that TCS exposure increased the relative abundance of the Proteobacteria and Actinobacteria phyla in female mice. Ultrastructural analysis revealed that TCS exposure induced ultrastructural damage to hippocampal neurons and synapses. These findings suggest that TCS exposure may affect social behaviors, which may be caused by altered gut microbiota and impaired plasticity of hippocampal neurons and synapses.

Gut microbiota exaggerates triclosan-induced liver injury via gut-liver axis

Triclosan (TCS) is an antimicrobial ingredient that has been widely incorporated in consumer products. TCS can cause hepatic damage by disturbing lipid metabolism, which is often accompanied with gut microbiota dysbiosis. However, the effects of gut microbiota on the TCS-induced liver injury are still unknown. Therefore, we constructed a mouse model based on five-week-old male C57BL/6 mice to investigate the effects of dietary TCS exposure (40 ppm) on liver injury. We found that TCS treatment for 4 weeks dramatically disturbed gut microbiota homeostasis, resulting in overproduction of lipopolysaccharides (LPS) and deficiency of secondary bile acids such as deoxycholic acid (DCA) and lithocholic acid (LCA). In addition, TCS considerably increased intestinal permeability by reducing mucus excretion and expression of tight junction proteins (ZO-1, occludin and claudin 4), which facilitated translocation of LPS. The LPS accumulation in blood contributed to liver injury by triggering the inflammatory response via TLR4 pathway. In summary, this study provides novel insights into the underlying mechanisms of TCS-associated liver injury induced by gut microbiota via the gut-liver axis, and contributes to better interpretation of the health impact of the environmentally emerging contaminant TCS.

Pathogenic mitochondrial dysfunction and metabolic abnormalities

Herein we trace links between biochemical pathways, pathogenesis, and metabolic diseases to set the stage for new therapeutic advances. Cellular and acellular microorganisms including bacteria and viruses are primary pathogenic drivers that cause disease. Missing from this statement are subcellular compartments, importantly mitochondria, which can be pathogenic by themselves, also serving as key metabolic disease intermediaries. The breakdown of food molecules provides chemical energy to power cellular processes, with mitochondria as powerhouses and ATP as the principal energy carrying molecule. Most animal cell ATP is produced by mitochondrial synthase; its central role in metabolism has been known for >80 years. Metabolic disorders involving many organ systems are prevalent in all age groups. Progressive pathogenic mitochondrial dysfunction is a hallmark of genetic mitochondrial diseases, the most common phenotypic expression of inherited metabolic disorders. Confluent genetic, metabolic, and mitochondrial axes surface in diabetes, heart failure, neurodegenerative disease, and even in the ongoing coronavirus pandemic.

Primary Human Hepatocyte Spheroids as Tools to Study the Hepatotoxic Potential of Non-Pharmaceutical Chemicals

Drug-induced liver injury, including cholestasis, is an important clinical issue and economic burden for pharmaceutical industry and healthcare systems. However, human-relevant in vitro information on the ability of other types of chemicals to induce cholestatic hepatotoxicity is lacking. This work aimed at investigating the cholestatic potential of non-pharmaceutical chemicals using primary human hepatocytes cultured in 3D spheroids. Spheroid cultures were repeatedly (co-) exposed to drugs (cyclosporine-A, bosentan, macitentan) or non-pharmaceutical chemicals (paraquat, tartrazine, triclosan) and a concentrated mixture of bile acids for 4 weeks. Cell viability (adenosine triphosphate content) was checked every week and used to calculate the cholestatic index, an indicator of cholestatic liability. Microarray analysis was performed at specific time-points to verify the deregulation of genes related to cholestasis, steatosis and fibrosis. Despite the evident inter-donor variability, shorter exposures to cyclosporine-A consistently produced cholestatic index values below 0.80 with transcriptomic data partially supporting its cholestatic burden. Bosentan confirmed to be hepatotoxic, while macitentan was not toxic in the tested concentrations. Prolonged exposure to paraquat suggested fibrotic potential, while triclosan markedly deregulated genes involved in different types of hepatotoxicity. These results support the applicability of primary human hepatocyte spheroids to study hepatotoxicity of non-pharmaceutical chemicals in vitro.

Triclosan-induced glycolysis drives inflammatory activation in microglia via the Akt/mTOR/HIF 1α signaling pathway

Exposure to triclosan (TCS) has been implicated in neurotoxicity including autism spectrum disorders in vivo and oxidative stress and cell apoptosis in vitro. Thus, the molecular mechanisms underlying TCS-induced neurotoxicity warrants further research. In this study, we try to address the mode of action that TCS induced the expression of inflammatory cytokines by shifting metabolism to glycolysis. BV-2 cells were treated with 20 μM TCS for 24 h, and the conditional medium from TCS-induced activated microglia reduced the viability of the murine hippocampal neurons cell line HT22. Protein expression levels in the nuclear factor kappa B (NF-κB) signaling pathway were measured through Western blotting, and the expression levels of inflammatory cytokine were measured using quantitative real-time PCR. The results showed that exposure to TCS enhanced NF-κB activation, increased inflammatory cytokine expression including interleukin (IL) 1β, IL-6, and tumor necrosis factor (TNF) α in the BV-2 cells. The glucose consumption and lactate production in BV2 cell increased sharply after exposure to TCS for 24 h. Based on our qPCR and Western blotting results, the expression of the key glycolysis enzymes-namely hexokinase 1, pyruvate kinase M2, and lactate dehydrogenase A-increased after treatment with 20 μM TCS. Furthermore, inhibiting glycolysis by 2-deoxy-D-glucose reduced the activation of NF-κB and the mRNA expression of the inflammatory cytokines in the TCS-activated BV-2 microglia. The expression of the proteins of the Akt/mTOR/HIF1α pathway examined through Western blotting, which regulates glycolysis, also increased in the BV2 cells exposed to TCS. Moreover, Akt and mTOR inhibition by using LY294002 and rapamycin, respectively, blocked inflammatory cytokine overexpression induced by TCS. In conclusion, TCS can induce glycolysis and directly drive inflammatory activation in microglia; with the mediation of the Akt/mTOR/HIF1α pathway.

From Liver Fat to Cancer: Perils of the Western Diet

Hepatocellular carcinoma (HCC), the most common type of primary liver cancer provides the prototypical example of an obesity-related cancer. The obesity epidemic gave rise to an enormous increase in the incidence of non-alcoholic fatty liver disease (NAFLD), a condition that affects one third of American adults. In about 20% of these individuals, simple liver steatosis (hepatosteatosis) progresses to non-alcoholic steatohepatitis (NASH) characterized by chronic liver injury, inflammation, and fibrosis. In addition to liver failure, NASH greatly increases the risk of HCC. Here we discuss the metabolic processes that control the progression from NAFLD to NASH and from NASH to HCC, with a special emphasis on the role of free-non-esterified cholesterol in the process.