Histopathology and transcriptome reveals the tissue-specific hepatotoxicity and gills injury in mosquitofish (Gambusia affinis) induced by sublethal concentration of triclosan

Analysis of key circRNA events in the AOP framework of TCS acting on zebrafish based on the data-driven

Triclosan (TCS) is a broad-spectrum antibiotic widely used in various personal care products. Research has found that exposure to TCS can cause toxic effects on organisms including neurotoxicity, cardiotoxicity, disorders of lipid metabolism, and abnormal vascular development, and the corresponding toxic mechanisms are gradually delving into the level of abnormal expression of miRNA regulating gene expression. Although the downstream mechanism of TCS targeting miRNA abnormal expression to induce toxicity is gradually improving, its upstream mechanism is still in a fog. Starting from the abnormal expression data of circRNA in zebrafish larvae induced by TCS, this study conducted a hierarchical analysis of the expression levels of all circRNAs, differential circRNAs, and trend circRNAs, and identified 29 key circRNA events regulating miRNA abnormal expression. In combination with GO and KEGG, the effects of TCS exposure were analyzed from the function and signaling pathway of the corresponding circRNA host gene. Furthermore, based on existing literature evidence about the biological toxicity induced by TCS targeting miRNA as data support, a competing endogenous RNAs (ceRNA) network characterizing the regulatory relationship between circRNA and miRNA was constructed and optimized. Finally, a comprehensive Adverse Outcome Pathway (AOP) framework of multiple levels of events including circRNA, miRNA, mRNA, pathway, and toxicity endpoints was established to systematically elucidate the toxic mechanism of TCS. Moreover, the rationality of the AOP framework was verified from the expression level of miRNA and adverse outcomes such as neurotoxicity, cardiotoxicity, oxidative stress, and inflammatory response by knockdown of circRNA48. This paper not only provides the key circRNA events for exploring the upstream mechanism of miRNA regulating gene expression but also provides an AOP framework for comprehensively demonstrating the toxicity mechanism of TCS on zebrafish, which is a theoretical basis for subsequent hazard assessment and prevention and control of TCS.

Critical review on the environmental behaviors and toxicity of triclosan and its removal technologies

As a highly effective broad-spectrum antibacterial agent, triclosan (TCS) is widely used in personal care and medical disinfection products, resulting in its widespread occurrence in aquatic and terrestrial environments, and even in the human body. Notably, the use of TCS surged during the COVID-19 outbreak, leading to increasing environmental TCS pollution pressure. From the perspective of environmental health, it is essential to systematically understand the environmental occurrence and behavior of TCS, its toxicological effects on biota and humans, and technologies to remove TCS from the environment. This review comprehensively summarizes the current knowledge regarding the sources and behavior of TCS in surface water, groundwater, and soil systems, focusing on its toxicological effects on aquatic and terrestrial organisms. Effluent from wastewater treatment plants is the primary source of TCS in aquatic systems, whereas sewage application and/or wastewater irrigation are the major sources of TCS in soil. Human exposure pathways to TCS and associated adverse outcomes were also analyzed. Skin and oral mucosal absorption, and dietary intake are important TCS exposure pathways. Reducing or completely degrading TCS in the environment is important for alleviating environmental pollution and protecting public health. Therefore, this paper reviews the removal mechanisms, including adsorption, biotic and abiotic redox reactions, and the influencing factors. In addition, the advantages and disadvantages of the different techniques are compared, and development prospects are proposed. These findings provide a basis for the management and risk assessment of TCS and are beneficial for the application of treatment technology in TCS removal.

Dynamic alterations in physiological and biochemical indicators of Cirrhinus mrigala hatchlings: A sublethal exposure of triclosan

Triclosan (TCS), a biocide used in various day-to-day products, has been associated with several toxic effects in aquatic organisms. In the present study, biochemical and hematological alterations were evaluated after 14 d (sublethal) exposure of tap water (control), acetone (solvent control), 5, 10, 20, and 50 μg/L (environmentally relevant concentrations) TCS to the embryos/hatchlings of Cirrhinus mrigala, a major freshwater carp distributed in tropic and sub-tropical areas of Asia. A concentration-dependent increase in the content of urea and protein carbonyl, while a decrease in the total protein, glucose, cholesterol, triglycerides, uric acid, and bilirubin was observed after the exposure. Hematological analysis revealed a decrease in the total erythrocyte count, hemoglobin, and partial pressure of oxygen, while there was an increase in the total leucocyte count, carbon dioxide, and partial pressure of carbon dioxide and serum electrolytes. Comet assay demonstrates a concentration-dependent increase in tail length, tail moment, olive tail moment, and percent tail DNA. An amino acid analyzer showed a TCS-dose-dependent increase in various amino acids. Sodium dodecyl sulphate polyacrylamide gel electrophoresis analysis revealed different proteins ranging from 6.5 to 200 kDa, demonstrating TCS-induced upregulation. Fourier transform infrared spectra analysis exhibited a decline in peak area percents with an increase in the concentration of TCS in water. Curve fitting of amide I (1,700-1600 cm-1) showed a decline in α-helix and turns and an increase in β-sheets. Nuclear magnetic resonance study also revealed concentration-dependent alterations in the metabolites after 14 d exposure. TCS caused alterations in the biomolecules and heamatological parameters of fish, raising the possibility that small amounts of TCS may change the species richness in natural aquatic habitats. In addition, consuming TCS-contaminated fish may have detrimental effects on human health. Consequently, there is a need for the proper utilisation and disposal of this hazardous compound in legitimate quantities.

Triclosan and its alternatives, especially chlorhexidine, modulate macrophage immune response with distinct modes of action

Since European regulators restricted the use of bacteriocidic triclosan (TCS), alternatives for TCS are emerging. Recently, TCS has been shown to reprogram immune metabolism, trigger the NLRP3 inflammasome, and subsequently the release of IL-1β in human macrophages, but data on substitutes is scarce. Hence, we aimed to examine the effects of TCS compared to its alternatives at the molecular level in human macrophages. LPS-stimulated THP-1 macrophages were exposed to TCS or its substitutes, including benzalkonium chloride, benzethonium chloride, chloroxylenol, chlorhexidine (CHX) and cetylpyridinium chloride, with the inhibitory concentration (IC10-value) of cell viability to decipher their mode of action. TCS induced the release of the pro-inflammatory cytokine TNF and high level of IL-1β, suggesting the activation of the NLRP3-inflammasome, which was confirmed by non-apparent IL-1β under the NLRP3-inhibitor MCC950 treatment d. While IL-6 release was reduced in all treatments, the alternative CHX completely abolished the release of all investigated cytokines. To unravel the underlying molecular mechanisms, we used untargeted LC-MS/MS-based proteomics. TCS and CHX showed the strongest cellular response at the protein and signalling pathway level, whereby pathways related to metabolism, translation, cellular stress and migration were mainly affected but to different proposed modes of action. TCS inhibited mitochondrial electron transfer and affected phagocytosis. In contrast, in CHX-treated cells, the translation was arrested due to stress conditions, resulting in the formation of stress granules. Mitochondrial (e.g. ATP5F1D, ATP5PB, UQCRQ) and ribosomal (e.g. RPL10, RPL35, RPS23) proteins were revealed as putative key drivers. Furthermore, we have demonstrated the formation of podosomes by CHX, potentially involved in ECM degradation. Our results exhibit modulation of the immune response in macrophages by TCS and its substitutes and illuminated underlying molecular effects. These results illustrate critical processes involved in the modulation of macrophages' immune response by TCS and its alternatives, providing information essential for hazard assessment.

Triclosan exposure induces immunotoxic impacts by disrupting the immunometabolism, detoxification, and cellular homeostasis in blood clam (Tegillarca granosa)

Omnipresent presence of triclosan (TCS) in aqueous environment puts a potential threat to organisms. However, it's poorly understood about its immunometabolic impacts of marine invertebrates. In present study, we use a representative bivalve blood clam (Tegillarca granosa) as a model, investigating the effects of TCS exposure at 20 and 200 μg/L for 28 days on immunometabolism, detoxification, and cellular homeostasis to explore feasible toxicity mechanisms. Results demonstrated that the clams exposed to TCS resulting in evident immunotoxic impacts on both cellular and humoral immune responses, through shifting metabolic pathways and substances, as well as suppressing the expressions of genes from the immune- and metabolism-related pathways. In addition, significant alterations in contents (or activity) of detoxification enzymes and the expression of key detoxification genes were detected in TCS-exposed clams. Moreover, exposure to TCS also disrupted cellular homeostasis of clams through increasing MDA contents and caspase activities, and promoting activation of the apoptosis-related genes. These findings suggested that TCS might induce immunotoxic impacts by disrupting the immunometabolism, detoxification, and cellular homeostasis.

Effects of Mulberry Leaf Extract on the Liver Function of Juvenile Spotted Sea Bass (Lateolabrax maculatus)

In order to explore the effect of mulberry leaf extract (ELM) on the liver function of spotted sea bass, 360 fish with healthy constitution (average body weight 9.00 ± 0.02 g) were selected and randomly divided into six groups with three repetitions, and six groups of fish were randomly placed into 18 test tanks (200 L) with 20 fish per tank for the 52-day feeding test. Every day, the fish were fed the experimental feed with different concentrations (0, 3, 6, 9, 12, 15 g/kg) to the level of apparent satiation, with a crude protein content of 48.0% and a crude fat content of 8.6%. And the water temperature was maintained at 25-28°C with a salinity of 0.5%-1‰. After feeding, five fish were randomly selected to collect their livers and serum for detection of indicators. The results showed that, compared with the control group, ELM significantly increased the activities of lipase (LPS) and trypsin (TRS) in the liver, and reached the highest level when the amount of ELM added was 6 g/kg (P < 0.05). ELM significantly increased the activities of lactate dehydrogenase (LDH) and glutamic-oxaloacetic transaminase (GOT) involved in the metabolic process in liver tissue, and GOT activity reached the highest when ELM was added at 9 g/kg, and LDH activity reached the highest when ELM was added at 15 g/kg (P < 0.05). ELM had no significant effect on liver antioxidant enzymes (P > 0.05), but the content of malondialdehyde was significantly reduced (P < 0.05). Compared with the control group, ELM significantly increased the activities of AKP and ACP in the liver, and the AKP activity reached the highest when the ELM addition amount was 3 g/kg, and the ACP activity reached the highest when the ELM addition amount was 9 g/kg (P < 0.05). Through comparative transcriptomic analysis, it was indicated that ELM enhanced the hepatic lipids and carbohydrates metabolism ability, as manifested in the upregulation of expression of phosphatidate phosphatase, glucuronosyltransferase, inositol oxygenase, carbonic anhydrase, and cytochrome c oxidase subunit 2. ELM can also increase the expression of signal transducer and activator of transcription 1, ATP-dependent RNA helicase and C-X-C motif chemokine 9 involved in the immune process. The above results show that the ELM can enhance the digestion, metabolism, and immunity of the liver by increasing the activity of digestive enzymes, metabolic enzymes, and the expression of metabolism and immune regulation genes. This study provides a theoretical basis for the application of ELM in the cultivation of spotted sea bass by exploring the effect of ELM on the liver function of spotted sea bass.

Conventional Anthelmintic Concentration of Deltamethrin Immersion Disorder in the Gill Immune Responses of Crucian Carp

Current treatment strategies for parasitic infectious diseases in crucian carp primarily rely on chemotherapy. As a commonly used antiparasitic agent, deltamethrin (DEL) may have the potential adverse effects on external mucosa of fish such as gills. In this study, 180 healthy juvenile crucian carp (Carassius auratus) (average weight: 8.8 ± 1.0 g) were randomly divided into three groups for 28 days, which were immersed in 0 μg/L, 0.3 μg/L, and 0.6 μg/L of DEL, respectively. The results of histological analysis revealed that severe hyperplasia in the secondary lamellae of gills was observed, and the number of goblet (mucus-secreting) cells increased significantly after DEL immersion. TUNEL staining indicated that the number of apoptotic cells increased in crucian carp gill. At the molecular level, the mRNA expression analysis revealed significant upregulation of apoptosis (caspase 3, caspase 8, and bax), autophagy (atg5 and beclin-1), and immune response (lzm, muc5, il-6, il-8, il-10, tnfα, ifnγ, tgfβ, tlr4, myd88, and nf-kb), whereas tight junction-related genes (occludin and claudin12) were downregulated after DEL immersion, suggesting that DEL immersion altered innate immunity responses and promoted mucus secretion. Moreover, tandem mass tag (TMT)-based proteomics revealed that a total of 428 differentially expressed proteins (DEPs) contained 341 upregulated DEPs and 87 downregulated DEPs with function annotation were identified between the control and DEL groups. Functional analyses revealed that the DEPs were enriched in apoptotic process, phagosome, and lysosome pathways. Additionally, DEL immersion also drove gill microbiota to dysbiosis and an increase in potentially harmful bacteria such as Flavobacterium. Overall, this study showed that DEL elicited shifts in the immune response and changes in the surface microbiota of fish. These results provide new perspectives on the conventional anthelmintic concentration of DEL immersion disorder of the gill immune microenvironment in crucian carp and theoretical support for future optimization of their practical application.

Sublethal effects of niclosamide on the aquatic snail Pomacea canaliculata

Pomacea canaliculata is a malignant invasive aquatic snail found worldwide, and niclosamide (NS) is one of the primary agents used for its control. NS applied to water will exist in non-lethal concentrations for some time due to degradation or water exchange, thus resulting in sublethal effects on environmental organisms. To identify sublethal effects of NS on Pomacea canaliculata, we studied the aspects of histopathology, oxygen-nitrogen ratio (R_O∶N), enzyme activity determination, and gene expression. After LC₃₀ NS treatment (0.310 g/L), many muscle fibers of the feet degenerated and some acinar vesicles of the hepatopancreas collapsed and dissolved. The oxygen-nitrogen ratio (R_O∶N) decreased significantly from 15.0494 to 11.5183, indicating that NS had changed the metabolic mode of Pomacea canaliculata and shifted it primarily to protein catabolism. Transcriptome analysis identified the sublethal effects of LC₃₀ NS on the snails at the transcriptional level. 386, 322, and 583 differentially expressed genes (DEGs) were identified in the hepatopancreas, gills, and feet, respectively. GO (Gene Ontology) functional analysis and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway annotations showed that DEGs in the hepatopancreas were mainly enriched for sugar metabolism, protein biosynthesis, immune response, and amino acid metabolism functional categories; DEGs in the gills were mainly enriched for ion transport and amino acid metabolism; DEGs in the feet were mainly enriched for transmembrane transport and inositol biosynthesis. In the future, we will perform functional validation of key genes to further explain the molecular mechanism of sublethal effects.

Endocrine Disruption of Propylparaben in the Male Mosquitofish (Gambusia affinis): Tissue Injuries and Abnormal Gene Expressions of Hypothalamic-Pituitary-Gonadal-Liver Axis

Propylparaben (PrP) is a widely used preservative that is constantly detected in aquatic environments and poses a potential threat to aquatic ecosystems. In the present work, adult male mosquitofish were acutely (4d) and chronically (32d) exposed to environmentally and humanly realistic concentrations of PrP (0, 0.15, 6.00 and 240 μg/L), aimed to investigate the toxic effects, endocrine disruption and possible mechanisms of PrP. Histological analysis showed time- and dose-dependent manners in the morphological injuries of brain, liver and testes. Histopathological alterations in the liver were found in 4d and severe damage was identified in 32d, including hepatic sinus dilatation, cytoplasmic vacuolation, cytolysis and nuclear aggregation. Tissue impairments in the brain and testes were detected in 32d; cell cavitation, cytomorphosis and blurred cell boundaries appeared in the brain, while the testes lesions contained spermatogenic cell lesion, decreased mature seminal vesicle, sperm cells gathering, seminiferous tubules disorder and dilated intercellular space. Furthermore, delayed spermatogenesis had occurred. The transcriptional changes of 19 genes along the hypothalamus-pituitary-gonadal-liver (HPGL) axis were investigated across the three organs. The disrupted expression of genes such as Ers, Ars, Vtgs, cyp19a, star, hsd3b, hsd17b3 and shh indicated the possible abnormal steroidogenesis, estrogenic or antiandrogen effects of PrP. Overall, the present results provided evidences for the toxigenicity and endocrine disruptive effects on the male mosquitofish of chronic PrP exposure, which highlights the need for more investigations of its potential health risks.

Triclocarban and triclosan exacerbate high-fat diet-induced hepatic lipid accumulation at environmental related levels: The potential roles of estrogen-related receptors pathways

Triclosan (TCS) and triclocarban (TCC) have become ubiquitous pollutants detected in human body with concentrations up to hundreds of nanomolar levels. Previous studies about the hepatic lipid accumulation induced by TCS and TCC were focused on pollutant itself, which showed weak or no effects. High-fat diet (HFD), as a known environmental factor contributing to lipid metabolism-related disorders, its synergistic action with environmental pollutants deserves concern. The present study aimed to demonstrate the combined effects and potential molecular mechanisms of TCS and TCC with HFD at cellular and animal levels. The in vitro studies showed that TCC and TCS alone had negligible impact on lipid accumulation in HepG2 cells but induced lipid deposition at nanomolar levels when co-exposure with fatty acid. TCC exhibited much higher induction effects than TCS, which was related to their differential regulatory roles in adipogenic-related genes expression. The in vivo studies showed that TCC had little influence on hepatic lipid accumulation in mice fed with normal diet (ND) but could exacerbate the lipid accumulation in mice fed with HFD. Meanwhile, TCC-induced dyslipidemia in mice fed with HFD was more significant than that fed with ND. Therefore, we speculated that TCC might increase the risk of nonalcoholic fatty liver disease (NAFLD) and atherosclerosis in HFD humans. Molecular mechanism studies showed that TCC and TCS could bind to and activate estrogen-related receptor α (ERRα) and ERRγ as well as regulate their expression. TCC had higher activity on ERRα and ERRγ than TCS, which explained partly the differential regulatory roles of two receptors in the lipid accumulation induced by TCC and TCS. This work revealed synergistic effects and molecular mechanisms of TCC and TCS with excessive fatty acid on the hepatic lipid metabolism, which provided a novel insight into the toxic mechanism of pollutants from the perspective of dietary habits.

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.

Lipid metabolism disorders contribute to hepatotoxicity of ICR mice induced by nitrosamines exposure

Health risks caused by crucial environmental carcinogens N-nitrosamines triggered ubiquitous attention. As the liver exerted vital function through metabolic process, lipid metabolism disorders have been confirmed as potential drivers for toxicological effects, and the mechanisms of lipid regulation related to hepatotoxicity induced by N-nitrosamines remained largely unclear. In this study, we comprehensively explored the disturbance of hepatic lipid homeostasis in mice induced by nitrosamines. The results implied that nitrosamines exposure induced hepatotoxicity accompanied by liver injury, inflammatory infiltration, and hepatic edema. Lipidomics profiling analysis indicated the decreased levels of phosphatidic acids (PA), phosphatidylcholines (PC), phosphatidylethanolamines (PE), lyso-phosphatidylcholines (LPC), lyso-phosphatidylethanolamines (LPE), diacylglycerols (DAG) and triacylglycerols (TAG), the elevation of ceramides (Cer) and decomposition of free fatty acids (FFA) in high-dose nitrosamines exposure group. Importantly, nitrosamines exposure promoted fatty acid oxidation (FAO) by facilitating fatty acid uptake and decomposition, together with the upregulation of genes associated with FAO accompanied by the activation of inflammatory cytokines TNF-α, IL-1β and NLRP3. Furthermore, fatty acid translocase CD36-mediated fatty acid oxidation was correlated with the enhancement of oxidative stress in the liver caused by nitrosamines exposure. Overall, our results contributed to the new strategies to interpret the early toxic effects of nitrosamines exposure.

Caenorhabditis elegans deep lipidome profiling by using integrative mass spectrometry acquisitions reveals significantly altered lipid networks

Lipidomics coverage improvement is essential for functional lipid and pathway construction. A powerful approach to discovering organism lipidome is to combine various data acquisitions, such as full scan mass spectrometry (full MS), data-dependent acquisition (DDA), and data-independent acquisition (DIA). Caenorhabditis elegans (C. elegans) is a useful model for discovering toxic-induced metabolism, high-throughput drug screening, and a variety of human disease pathways. To determine the lipidome of C. elegans and investigate lipid disruption from the molecular level to the system biology level, we used integrative data acquisition. The methyl-tert-butyl ether method was used to extract L4 stage C. elegans after exposure to triclosan (TCS), perfluorooctanoic acid, and nanopolystyrene (nPS). Full MS, DDA, and DIA integrations were performed to comprehensively profile the C. elegans lipidome by Q-Exactive Plus MS. All annotated lipids were then analyzed using lipid ontology and pathway analysis. We annotated up to 940 lipids from 20 lipid classes involved in various functions and pathways. The biological investigations revealed that when C. elegans were exposed to nPS, lipid droplets were disrupted, whereas plasma membrane-functionalized lipids were likely to be changed in the TCS treatment group. The nPS treatment caused a significant disruption in lipid storage. Triacylglycerol, glycerophospholipid, and ether class lipids were those primarily hindered by toxicants. Finally, toxicant exposure frequently involved numerous lipid-related pathways, including the phosphoinositide 3-kinase/protein kinase B pathway. In conclusion, an integrative data acquisition strategy was used to characterize the C. elegans lipidome, providing valuable biological insights into hypothesis generation and validation.

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Multiple data acquisitions were used to profile the lipidome of C. elegans.

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940 detected lipids of 20 main classes involved in various pathways.

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Relevant hypotheses were generated using high-coverable lipidomics and pathways analysis.