Blueberry anthocyanin alleviate perfluorooctanoic acid-induced toxicity in planarian (Dugesia japonica) by regulating oxidative stress biomarkers, ATP contents, DNA methylation and mRNA expression

Toxicity of microplastics polystyrene to freshwater planarians and the alleviative effects of anthocyanins

It is impossible to overlook the effects of microplastics (MPs) on aquatic organisms as they continuously accumulate in water environment. Freshwater planarians, which exist in the benthic zone of water bodies and come into contact with the deposited MPs particles, provide a highly representative model for studying the effects of MPs on aquatic organisms. Anthocyanins (ANTs) have gained significant popularity in recent years for their diverse health benefits. In the current study, the median lethal concentration (LC50) of polystyrene (PS) to planarian Dugesia japonica was determined for the first time. Based on this, multiple toxic effects of single PS and PS in combination with ANTs on planarians were explored. The results showed that PS exposure disrupted the redox homeostasis and induced oxidative damage in planarians. Also, PS stress affected the neuromorphology, aggravated cell apoptosis in planarians probably by altering neural gene expressions as well as promoting the expression of apoptosis-related genes while inhibiting stem cell marker genes. In addition, the results also suggested that co-exposure of ANTs could effectively alleviate the toxicity of PS on planarians. Particularly, long-term environmentally relevant concentration PS exposure exhibited a higher propensity for inducing toxicity on planarians than short-term high concentration acute exposure, indicating that the harm of environmental MPs to humans and wildlife exposed to them should not be underestimated. Therefore, considering the recently rising and rapid development of ecotoxicomics, more in-depth research on the toxicity mechanism of environmentally relevant concentration PS-MPs to freshwater planarians from multi-omics levels will be our future work.

Impact of diethyl phthalate on freshwater planarian behaviour, regeneration, and antioxidant defence

Diethyl phthalate (DEP) has been widely used as a plasticiser in various consumer products, including cosmetics, personal care items, and pharmaceuticals, and recent studies reported a higher abundance of this priority phthalate in the aquatic environment. DEP is a potential endocrine disruptor, affecting immune systems in humans and wildlife even at low-level chronic exposure. As concern over phthalates increases globally, regulatory bodies focus more on their environmental impact. However, limited research is available, particularly using model organisms like planarians. Planarians are ideal for toxicological studies and may provide insightful information on pollutants' neurotoxic, developmental, and ecological effects, especially in freshwater environments where planarians play a vital role in ecosystem balance. Therefore, the objective of the current study was to examine the toxicity of DEP using the freshwater Dugesia sp., as an experimental animal. The LC50 for the test organism was calculated using DEP concentrations of 800, 400, 200, 100, and 50 µM, with an estimated LC50 of 357.24 µM. Furthermore, planarians were exposed to sub-lethal DEP concentration (178.62 µM) for one day as well as eight days to evaluate the impact of DEP on planarian locomotion, feeding behaviour, and regeneration ability. At sub-lethal concentration, locomotion and feeding ability were decreased, and regeneration was delayed. Furthermore, neuro-transmittance in planaria was altered by sub-lethal DEP concentration, as indicated by a reduced acetylcholinesterase (AChE) activity. DEP exposure induced oxidative damage in the tested planarians as shown by a marked increase in stress biomarkers, including lipid peroxidation levels and antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), and glutathione S-transferase (GST). Our study revealed that DEP exposure may prove fatal to freshwater organisms, such as planarians. The observed alterations in behaviour and regeneration ability demonstrate the severity of the effects exerted by DEP as a toxicant in aquatic ecosystems, thereby indicating the need to restrict its usage to protect aquatic environments.

Itaconic Acid Alleviates Perfluorooctanoic Acid-Induced Oxidative Stress and Intestinal Damage by Regulating the Keap1/Nrf2/Ho-1 Pathway and Reshaping the Gut Microbiota

Itaconic acid (IA) is recognized for its potential application in treating intestinal diseases owing to the anti-inflammatory and antioxidant properties. Perfluorooctanoic acid (PFOA) can accumulate in animals and result in oxidative and inflammatory damages to multi-tissue and organ, particularly in the intestinal tract. This study aimed to explore whether IA could mitigate intestinal damage induced by PFOA exposure in laying hens and elucidate its potential underlying mechanisms. The results showed that IA improved the antioxidant capacity of laying hens and alleviated the oxidative damage induced by PFOA, as evidenced by the elevated activities of T-SOD, GSH-Px, and CAT, and the decreased MDA content in both the jejunum and serum. Furthermore, IA improved the intestinal morphological and structural integrity, notably attenuating PFOA-induced villus shedding, length reduction, and microvillus thinning. IA also upregulated the mRNA expression of ZO-1, Occludin, Claudin-1, and Mucin-2 in the jejunum, thereby restoring intestinal barrier function. Compared with the PF group, IA supplementation downregulated the gene expression of Keap1 and upregulated the HO-1, NQO1, SOD1, and GPX1 expression in the jejunum. Meanwhile, the PF + IA group exhibited lower expressions of inflammation-related genes (NF-κB, IL-1β, IFN-γ, TNF-α, and IL-6) compared to the PF group. Moreover, IA reversed the PFOA-induced imbalance in gut microbiota by reducing the harmful bacteria such as Escherichia-Shigella, Clostridium innocuum, and Ruminococcus torques, while increasing the abundance of beneficial bacteria like Lactobacillus. Correlation analysis further revealed a significant association between gut microbes, inflammatory factors, and the Keap1/Nrf2/HO-1 pathway expression. In conclusion, dietary IA supplementation could alleviate the oxidative and inflammatory damage caused by PFOA exposure in the intestinal tract by reshaping the intestinal microbiota, modulating the Keap1/Nrf2/HO-1 pathway and reducing oxidative stress and inflammatory response, thereby promoting intestinal homeostasis.

Tissue Bioconcentration Pattern and Biotransformation of Per-Fluorooctanoic Acid (PFOA) in Cyprinus carpio (European Carp)—An Extensive In Vivo Study

The perfluoroalkyl substances (PFAS) represent a persistent class of synthetic chemicals that spread in the environment as a result of industrialization. Due to their bioaccumulative and endocrine disruption implications, these chemicals can affect food quality and human health, respectively. In the present study, the bioconcentration and biotransformation of perfluorooctanoic acid (PFOA) in common carp (Cyprinus carpio) were evaluated in a biphasic system (exposure and depuration). Carp were continuously exposed, under laboratory conditions, to 10 (Experiment 1) and 100 (Experiment 2) µg/L PFOA for 14 weeks, followed by a wash out period of 3 weeks. Fish organs and tissues were collected at 8, 12, 14 weeks of exposure and at week 17, after the depuration period. The results obtained from the LC-MS/MS analysis showed the presence of PFOA in all studied organs. The highest values of PFOA were identified in the gallbladder (up to 2572 ng/g d.w.) in Experiment 1 and in the gallbladder (up to 18,640 ng/g d.w.) and kidneys (up to 13,581 ng/g d.w.) in Experiment 2. The average BCF varied between 13.4 and 158 L/Kg in Experiment 1 and between 5.97 and 80.3 L/Kg in Experiment 2. Four biotransformation products were identified and quantified in all organs, namely: PFBA, PFPeA, PFHxA, and PFHpA. PFBA was proven to be the dominant biotransformation product, with the highest values being determined after 8 weeks of exposure in the kidney, gallbladder, brain, liver, and gonads in both experiments. Because freshwater fish are an important food resource for the human diet, the present study showed the fishes’ capacity to accumulate perfluoroalkyl substances and their metabolites. The study revealed the necessity of monitoring and risk studies of new and modern synthetic chemicals in aquatic resources.

Toxicity of ceria nanoparticles to the regeneration of freshwater planarian Dugesia japonica: The role of biotransformation

Cerium oxide nanoparticles (n-CeO₂) have wide applications ranging from industrial to consumer products, which would inevitably lead to their release into the environment. Despite the toxicity of n-CeO₂ on aquatic organisms has been largely reported, research on developing organisms is still lacking. In this study, we investigate the toxic effects of n-CeO₂ on the stem cells, tissue- and neuro-regeneration, using freshwater planarian Dugesia japonica as a model. Effects of bulk sized (μ-) CeO₂ and ionic Ce (Ce³⁺) were compared with that of n-CeO₂ to explore the origin of the toxic effects of n-CeO₂. No overt toxicity was observed in μ-CeO₂ treatment. n-CeO₂ not only impaired the homeostasis of normal planarians, but also inhibited the regeneration processes of regenerated planarians, demonstrated by the inhibited blastema growth, disturbed antioxidant defense system at molecular levels, elevated DNA-damage and decreased stem cell proliferation. Regenerating organisms are more susceptible to n-CeO₂ than the normal ones. Ce³⁺ exhibited significantly higher toxicity than n-CeO₂, even though the total Ce uptake is 0.2 % less in Ce³⁺ than in n-CeO₂ treated in planarian. X-ray absorption near edge spectroscopy (XANES) analysis revealed that 12.8 % of n-CeO₂ (5.95 mg/kg Ce per planarian) was transformed to Ce³⁺ after interaction with planarian, suggesting that biotransformation at the nano-bio interface might play an important role in the observed toxicity. Since the biotransformation of n-CeO₂ is a slow process, it may cause long-term chronic toxicity to planarians due to the slow while sustained release of toxic Ce³⁺ ions.

Combined exposure to di(2-ethylhexyl) phthalate and polystyrene microplastics induced renal autophagy through the ROS/AMPK/ULK1 pathway

Di(2-ethylhexyl) phthalate (DEHP) and polystyrene microplastics (PS-MPs) are new environmental pollutants that attracted increased attention. At present, the effects and underlying mechanisms of action of combined exposure of DEHP and PS-MPs on the kidney have not been elucidated. To investigate the renal toxicity of DEHP and PS-MPs exposure, we established single and combined DEHP and PS-MPs exposure models in mice and HEK293 cells, respectively. Hematoxylin and eosin staining, transmission electron microscopy, monodansylcadaverine staining, immunofluorescence, real-time quantitative PCR, Western blot analysis and other methods were used to detect relevant indicators. The results showed that the expression levels of ROS/AMPK/ULK1 and Ppargc1α/Mfn2 signaling pathway-related genes were significantly increased in the DEHP and PS-MPs exposure models. The mRNA and protein expression levels of autophagy markers were also upregulated. In addition, we found that the expression levels of mRNAs and proteins in the combined exposure group were more significantly increased than those in the single exposure group. In conclusion, combined exposure to DEHP and PS-MPs caused oxidative stress and activated the AMPK/ULK1 pathway, thereby inducing renal autophagy. Our results enhance the field of nephrotoxicity studies of plasticizers and microplastics and provide new light on combined toxicity studies of DEHP and PS-MPs.

Quercetin protects human liver cells from o,p'-DDT-induced toxicity by suppressing Nrf2 and NADPH oxidase-regulated ROS production

Epidemiologic studies have revealed that Dichlorodiphenyltrichloroethane (DDT) and its metabolites are associated with liver diseases. However, there has been little emphasis on the mechanism underlying liver toxicity of o,p'-DDT and relevant effective inhibitors investigation. This study indicated o,p'-DDT exposure significantly decreased cell viability and promoted lactate dehydrogenase (LDH) release based on the investigation of cytotoxicity by trypan blue exclusion counts, MTT, and lactate dehydrogenase (LDH) assays. Comet, micronuclei, and DNA-protein crosslinks (DPC) assays demonstrated o,p'-DDT exposure increased the comet parameters, micronuclei frequency, and DPC coefficient. Meanwhile, we found o,p'-DDT induced mitochondria-dependent apoptosis, which is characterized by the loss of of mitochondrial membrane potential (Δψm), decreased Bcl-2 expression, and increased protein levels of Bax, cytochrome c, activated-caspase-9, and activated-caspase-3. Furthermore, o,p'-DDT induced reactive oxygen species (ROS) overproduction, decreased the protein levels of nuclear factor erythroid-derived 2-like 2 (Nrf2) in the nuclear, and enhanced the expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. However, quercetin treatment significantly antagonized o,p'-DDT-induced cytotoxicity, genotoxicity, and apoptosis as well as effects on ROS, Nrf2, and NADPH oxidase. Taken together, these findings suggested quercetin could alleviate o,p'-DDT-induced toxicity in HL-7702 cells via inhibiting ROS production, which is modulated by down-regulating nuclear Nrf2 levels and NADPH oxidase expression.

Epigenetic changes by per- and polyfluoroalkyl substances (PFAS)

Increasing studies are examining per- and polyfluoroalkyl substances (PFAS) induced toxicity and resulting health outcomes, including epigenetic modifications (e.g., DNA methylation, histone modification, microRNA expression). We critically reviewed current evidence from human epidemiological, in vitro, and animal studies, including mammalian and aquatic model organisms. Epidemiological studies identified the associations between perfluorooctane sulfonate (PFOS) or perfluorooctanoic acid (PFOA) exposure and epigenetic changes in both adult populations and birth cohorts. For in vitro studies, various cell types including neuroblasts, preadipocytes, and hepatocytes have been employed to understand epigenetic effects of PFAS. In studies with animal models, effects of early life exposure to PFAS have been examined using rodent models, and aquatic models (e.g., zebrafish) have been more frequently used in recent years. Several studies highlighted oxidative stress as a key mediator between epigenetic modification and health effects. Collectively, previous research clearly suggest involvement of epigenetic mechanisms in PFAS induced toxicity, though these efforts have primarily focused on specific PFASs (i.e. mainly PFOS and PFOA) or endpoints (i.e. cancer). Additional studies are necessary to define specific linkages among epigenetic mechanisms and related biomarkers or phenotypical changes. In addition, future research is also needed for understudied PFAS and complex mixtures. Studies of epigenetic effects elicited by individual PFAS and mixtures are needed within an adverse outcome pathways framework, which will advance an understanding of PFAS risks to public health and the environment, and support efforts to design less hazardous chemicals.

Fluorotelomer Alcohols' Toxicology Correlates with Oxidative Stress and Metabolism

Fluorotelomer alcohols (FTOHs) are widely used as industrial raw materials due to their unique hydrophobic and oleophobic properties. However, because of accidental exposure to products containing FTOHs or with the widespread use of FTOHs, they tend to contaminate the water and the soil. There are reports demonstrating that FTOHs can cause various harmful effects in animals and humans (for example, neurotoxicity, hepatotoxicity, nephrotoxicity, immunotoxicity, endocrine-disrupting activity, and developmental and reproductive toxicities). Oxidative stress is related to a variety of toxic effects induced by FTOHs. To date, few reviews have addressed the relationship between the toxicity of FTOHs and oxidative stress. This article summarises research demonstrating that the toxicity induced by FTOHs correlates with oxidative stress and metabolism. Furthermore, during the metabolic process of FTOHs, a number of cytochrome P450 enzymes (CYP450) are involved and many metabolites are produced by these enzymes, which can induce oxidative stress. This is also reviewed.

Neurotoxicity of perfluorooctanoic acid and post-exposure recovery due to blueberry anthocyanins in the planarians Dugesia japonica

Perfluorooctanoic acid (PFOA) is a widely used synthetic industrial chemical which accumulates in ecosystems and organisms. Our study have investigated the neurobehavioral effects of PFOA and the alleviation effects of PFOA-induced neurotoxicity by blueberry anthocyanins (ANT) in Dugesia japonica. The planarians were exposed to PFOA and ANT for ten days. Researchs showed that exposure to PFOA affected locomotor behavior and ANT significantly alleviated the reduction in locomotion induced by PFOA. The regeneration of eyespots and auricles was suppressed by PFOA and was promoted by ANT. Following exposure to PFOA, acetylcholinesterase activity continually decreased and was unaffected in the ANT group, but was elevated after combined administration of PFOA and ANT. Oxidative DNA damage was found in planarians exposed to PFOA and was attenuated after administration of ANT by the alkaline comet assay. Concentrations of three neurotransmitters increased following exposure to PFOA and decreased after administration of ANT. Furthermore, ANT promoted and PFOA inhibited neuronal regeneration. DjotxA, DjotxB, DjFoxG, DjFoxD and Djnlg associated with neural processes were up-regulated following exposure to PFOA. Our findings indicate that PFOA is a neurotoxicant while ANT can attenuate these detrimental effects.

Effects of ciprofloxacin exposure on the earthworm Eisenia fetida

The widespread use of the antibiotic ciprofloxacin (CIP) poses a serious risk to soil organisms. Here, earthworms (Eisenia fetida) were used to explore the effect of CIP exposure on growth, reproduction, mortality, antioxidant enzyme activity, DNA damage, and mRNA levels. The results showed that mortality, weight, and reproduction did not change in response to CIP exposure. The antioxidant enzymes superoxide dismutase (SOD), peroxidase (POD), and glutathione (GSH) were inhibited after 10 mg/kg CIP exposure on day 21, and catalase (CAT) activity increased significantly on day 14. High concentrations (1-2 g/kg) of CIP pollution caused DNA damage in E. fetida on days 7 and 14. At a dose of 10 mg/kg, CIP altered antioxidant enzymes and gene expression, but was not harmful to the growth and reproduction of E. fetida. Moreover, mRNA expression of annetocin, metallothionein, heat shock protein 70, and translationally controlled tumor protein were significantly upregulated on day 28. These findings indicate that antioxidant enzymes, DNA damage, and mRNA levels of biomarkers are more sensitive than mortality, growth, and reproduction for detecting CIP pollution in the soil environment.

Polydatin attenuates cadmium-induced oxidative stress via stimulating SOD activity and regulating mitochondrial function in Musca domestica larvae

Cadmium (Cd) is a widespread environment contaminant due to the development of electroplating and metallurgical industry. Cd can be enriched by organisms via food chain, causing the enlarged environmental problems and posing threats to the health of humans. Polydatin (PD), a natural stilbenoid compound derived from Polygonum cuspidatum, shows pronouncedly curative effect on oxidative damage. In this work, the protective effects of PD on oxidative damage induced by Cd in Musca domestica (housefly) larvae were evaluated. The larvae were exposed to Cd and/or PD, subsequently, the oxidative stress status, mitochondria activity, oxidative phosphorylation efficiency, and survival rate were assessed. Cd exposure generated significant increases of malondialdehyde (MDA), reactive oxygen species (ROS) and 8-hydroxy-2-deoxyguanosine (8-oxoG) in the housefly larvae, causing mitochondrial dysfunction and survival rate decline. Interestingly, pretreatment with PD exhibited obviously mitochondrial protective effects in the Cd-exposed larvae, as evidenced by reduced MDA, ROS and 8-oxoG levels, and increased activities of superoxide dismutase (SOD), mitochondrial electron transfer chain, and mitochondrial membrane potential, as well as respiratory control ratio. These results suggested that PD could attenuate Cd-induced damage via maintaining redox balance, stimulating SOD activity, and regulating mitochondria activity in housefly larvae. As a natural polyphenolic chemical, PD can act as a potential candidate compounds to relieve Cd injury.

Green tea polyphenols and epigallocatechin-3-gallate protect against perfluorodecanoic acid induced liver damage and inflammation in mice by inhibiting NLRP3 inflammasome activation

Perfluorodecanoic acid (PFDA) is a highly toxic food contaminant that is extensively used in food applications as surface antifouling agent. In this present study, we aimed to assess whether green tea polyphenols (GTPs) and epigallocatechin-3-gallate (EGCG) exert protective effects against PFDA-induced liver damage and inflammation in mice. A mouse model to evaluate liver toxicity was established by giving mice drinking water containing different concentrations of PFDA. GTPs or EGCG (0.32%, w/v) were co-administered to mice exposed to PFDA in drinking water. Overall, GTPs and EGCG extended the survival time and inhibited weight loss among mice who received a lower dose of PFDA. Moreover, GTPs and EGCG ameliorated hepatic oxidative stress, cell apoptosis, necrosis, steatosis, edema, and degeneration, reduced hepatic inflammation and NLRP3 inflammasome activation caused by a moderate dose of PFDA. Taken together, these results show that GTPs or EGCG (or green tea intake) supplements can be beneficial for people exposed to PFDA.