Polystyrene microplastics induced inflammation with activating the TLR2 signal by excessive accumulation of ROS in hepatopancreas of carp (Cyprinus carpio)

Protective effects of dietary additive quercetin: Nephrotoxicity and ferroptosis induced by avermectin pesticide

In recent years, contamination of aquatic systems with Avermectin (AVM) has emerged as a significant concern. This contamination poses substantial challenges to freshwater aquaculture. Plant-derived Quercetin (QUE), known for its anti-inflammatory, antioxidant, and ferroptosis-inhibiting properties, is commonly employed as a supplement in animal feed. However, its protective role against chronic renal injury in freshwater carp induced by AVM remains unclear. This study assesses the influence of dietary supplementation with QUE on the consequences of chronic AVM exposure on carp renal function. The carp were subjected to a 30-day exposure to AVM and were provided with a diet containing 400 mg/kg of QUE. Pathological observations indicated that QUE alleviated renal tissue structural damage caused by AVM. RT-QPCR study revealed that QUE effectively reduced the increased expression levels of pro-inflammatory factors mRNA produced by AVM exposure, by concurrently raising the mRNA expression level of the anti-inflammatory factor. Quantitative analysis using DHE tests and biochemical analysis demonstrated that QUE effectively reduced the buildup of ROS in the renal tissues of carp, activity of antioxidant enzymes CAT, SOD, and GSH-px, which were inhibited by AVM, and increased the content of GSH, which was induced by prolonged exposure to AVM. QUE also reduced the levels of MDA, a marker of oxidative damage. Furthermore, assays for ferroptosis markers indicated that QUE increased the mRNA expression levels of gpx4 and slc7a11, which were reduced due to AVM induction, and it caused a reduction in the mRNA expression levels of ftl, ncoa4, and cox2, along with a drop in the Fe2+ concentration. In summary, QUE mitigates chronic AVM exposure-induced renal inflammation in carp by inhibiting the transcription of pro-inflammatory cytokines. By blocking ROS accumulation, renal redox homeostasis is restored, thereby inhibiting renal inflammation and ferroptosis. This provides a theoretical basis for the development of freshwater carp feed formula.

Zinc supplementation alleviates oxidative stress to inhibit chronic gastritis via the ROS/NF-κB pathway in a mouse model

Zinc (Zn) is an important trace element; it is involved in the regulation and maintenance of many physiological functions in organisms and has anti-inflammatory and antioxidant properties. Chronic gastritis is closely associated with damage to the gastric mucosa, which is detrimental to the health of humans and animals. There are few studies on the effects of zinc on, for example, gastric mucosal damage, oxidative stress, inflammation and cell death in mice. Therefore, we established in vivo and in vitro models of inflammatory injury and investigated the effects of zinc supplementation in C57BL/6 mice and Ges-1 cells and examined the expression of factors associated with oxidative stress, inflammation and cell death. In this study, the results of in vivo and in vitro experiments showed that reactive oxygen species (ROS) levels increased after sodium salicylate exposure. Malondialdehyde levels increased, the activity of the antioxidant enzymes catalase and superoxide dismutase decreased, and the activity of glutathione decreased. The NF-κB signaling pathway was activated, the levels of proinflammatory factors (TNF-α, IL-1β, and IL-6) increased, and the expression of cell death-related factors (Bax, Bcl-2, Caspase3, Caspase7, Caspase9, RIP1, RIP3, and MLKL) increased. Zinc supplementation attenuated the level of oxidative stress and reduced the level of inflammation and cell death. Our study indicated that sodium salicylate induced the production of large amounts of reactive oxygen species and activated the NF-κB pathway, leading to inflammatory damage and cell death in the mouse stomach. Zinc supplementation modulated the ROS/NF-κB pathway, reduced the level of oxidative stress, and attenuated inflammation and cell death in the mouse stomach and Ges-1 cells.

Immunotoxicity of microplastics in fish

Plastic waste degrades slowly in aquatic environments, transforming into microplastics (MPs) and nanoplastics (NPs), which are subsequently ingested by fish and other aquatic organisms, causing both physical blockages and chemical toxicity. The fish immune system serves as a crucial defense against viruses and pollutants present in water. It is imperative to comprehend the detrimental effects of MPs on the fish immune system and conduct further research on immunological assessments. In this paper, the immune response and immunotoxicity of MPs and its combination with environmental pollutants on fish were reviewed. MPs not only inflict physical harm on the natural defense barriers like fish gills and vital immune organs such as the liver and intestinal tract but also penetrate cells, disrupting intracellular signaling pathways, altering the levels of immune cytokines and gene expression, perturbing immune homeostasis, and ultimately compromising specific immunity. Initially, fish exposed to MPs recruit a significant number of macrophages and T cells while activating lysosomes. Over time, this exposure leads to apoptosis of immune cells, a decline in lysosomal degradation capacity, lysosomal activity, and complement levels. MPs possess a small specific surface area and can efficiently bind with heavy metals, organic pollutants, and viruses, enhancing immune responses. Hence, there is a need for comprehensive studies on the shape, size, additives released from MPs, along with their immunotoxic effects and mechanisms in conjunction with other pollutants and viruses. These studies aim to solidify existing knowledge and delineate future research directions concerning the immunotoxicity of MPs on fish, which has implications for human health.

Multi-level toxicity assessment of polylactic acid (PLA) microplastics on the cladoceran Daphnia magna

The accumulation of plastics waste in the environment has raised a worrisome concern, moving the society to seek out for sustainable solutions, such as the transition from the use of fossil-based, conventional plastics to bioplastics (BPs). However, once in the environment bioplastics have the same probability to accumulate and experience weathering processes than conventional plastics, leading to the formation of microplastics (MPs). However, to date the information on the potential toxicity of MPs originated from the weathering of bioplastics is limited. Thus, this study aimed at investigating the adverse effects induced by the exposure to MPs made of a bioplastic polymer, the polylactic acid (PLA), towards the freshwater cladoceran Daphnia magna. Organisms were exposed for 21 days to three concentrations (0.125 µg/mL, 1.25 µg/mL and 12.5 µg/mL) of PLA microplastics (hereafter PLA-MPs). A multi-level approach was performed to investigate the potential effects through the biological hierarchy, starting from the sub-individual up to the individual level. At the sub-individual level, changes in the oxidative status (i.e., the amount of reactive oxygen species and the activity of antioxidant and detoxifying enzymes) and oxidative damage (i.e., lipid peroxidation) were explored. Moreover, the total caloric content as well as the content of protein, carbohydrate and lipid content assess were used to investigate the effects on energy reserves. At individual level the changes in swimming activity (i.e., distance moved and swimming speed) were assessed. Our results showed that the exposure to PLA-MPs induced a slight modulation in the oxidative status and energy reserves, leading to an increase in swimming behavior of treated individuals compared to control conspecifics. These results suggest that the exposure to MPs made of a bioplastic polymer can induce adverse effects similar to those caused by conventional polymers.

Ecotoxicological evaluation of chitosan biopolymer films particles in adult zebrafish (Danio rerio): A comparative study with polystyrene microplastics

To mitigate the environmental impact of microplastics (MPs), the scientific community has innovated sustainable and biodegradable polymers as viable alternatives to traditional plastics. Chitosan, the deacetylated form of chitin, stands as one of the most thoroughly investigated biopolymers and has garnered significant interest due to its versatile applications in both medical and cosmetic fields. Nevertheless, there is still a knowledge gap regarding the impact that chitosan biopolymer films (CBPF) may generate in aquatic organisms. In light of the foregoing, this study aimed to assess and compare the potential effects of CBPF on the gastrointestinal tract, gills, brain, and liver of Danio rerio against those induced by MPs. The findings revealed that both CBPF and MPs induced changes in the levels of oxidative stress biomarkers across all organs. However, it is essential to note that our star plots illustrate a tendency for CBPF to activate antioxidant enzymes and for MPs to produce oxidative damage. Regarding gene expression, our findings indicate that MPs led to an up-regulation in the expression of genes associated with apoptotic response (p53, casp3, cas9, bax, and bcl2) in all fish organs. Meanwhile, CBPF produced the same effect in genes related to antioxidant response (nrf1 and nrf2). Overall, our histological observations substantiated these effects, revealing the presence of plastic particles and tissue alterations in the gills and gastrointestinal tract of fish subjected to MPs. From these results, it can be concluded that CBPF does not represent a risk to fish after long exposure.

Protective effect of feed additive ferulic acid on respiratory depression and oxidation imbalance of carp induced by pesticide difenoconazole via ROS/NF-κB/NLRP3 axis

Difenoconazole (DFZ), classified as a "low-toxicity pesticide," has seen widespread application in recent years. Nevertheless, the non-target toxicity of the substance, particularly towards aquatic creatures, has generated considerable apprehension. The anti-inflammatory and antioxidant effects of Ferulic Acid (FA) have attracted considerable study in this particular setting. This study established a chronic exposure model to DFZ and investigated the protective effects of FA on chronic respiratory inhibition leading to gill damage in freshwater carp. Histological analyses via HE staining indicated that FA effectively alleviated gill tissue damage induced by chronic DFZ exposure. The qRT-PCR results showed that the addition of FA reduced the expression of IL-1β, IL-6 and TNF-α while boosting the expression of IL-10 and TGF-β1. Biochemical analyses and DHE staining revealed that FA reduced MDA levels and increased CAT and GSH activities, along with T-AOC, decreased ROS accumulation in response to chronic DFZ exposure. The results obtained from Western blotting analysis demonstrated that the addition of FA effectively suppressed the activation of the NF-κB signalling pathway and the NLRP3 inflammasome pathway in the gills subjected to prolonged exposure to DFZ. In summary, FA ameliorated gill tissue inflammation and blocked ROS accumulation in carp exposed to chronic DFZ, mitigating tissue inflammation and restoring redox homeostasis through the NF-κB-NLRP3 signaling pathway. Hence, the application of FA has been found to be efficacious for improving respiratory inhibition and mitigating gill tissue inflammation and oxidative stress resulting from DFZ pollution in aquatic habitats.

Microplastics and Oxidative Stress-Current Problems and Prospects

Microplastics (MPs) are plastic particles between 0.1 and 5000 µm in size that have attracted considerable attention from the scientific community and the general public, as they threaten the environment. Microplastics contribute to various harmful effects, including lipid peroxidation, DNA damage, activation of mitogen-activated protein kinase pathways, cell membrane breakages, mitochondrial dysfunction, lysosomal defects, inflammation, and apoptosis. They affect cells, tissues, organs, and overall health, potentially contributing to conditions like cancer and cardiovascular disease. They pose a significant danger due to their widespread occurrence in food. In recent years, information has emerged indicating that MPs can cause oxidative stress (OS), a known factor in accelerating the aging of organisms. This comprehensive evaluation exposed notable variability in the reported connection between MPs and OS. This work aims to provide a critical review of whether the harmfulness of plastic particles that constitute environmental contaminants may result from OS through a comprehensive analysis of recent research and existing scientific literature, as well as an assessment of the characteristics of MPs causing OS. Additionally, the article covers the analytical methodology used in this field. The conclusions of this review point to the necessity for further research into the effects of MPs on OS.

Selection, identification and evaluation of optimal reference genes in Chinese sturgeon (Acipenser sinensis) under polypropylene microplastics stress

Polypropylene microplastics (PP-MPs) are emerging environmental contaminants that have the potential to cause adverse effects on aquatic organisms. Reverse transcriptase quantitative real-time polymerase chain reaction (RT-qPCR) is a valuable tool for assessing the gene expression profiles under PP-MPs stress. To obtain an accurate gene expression profile of tissue inflammation and apoptosis that reflects the molecular mechanisms underlying the impact of PP-MPs on Chinese sturgeon, identifying reliable reference genes is crucial for RT-qPCR analysis. In this study, we constructed an experiment model of Chinese sturgeon exposed to PP-MPs, assessed the pathological injury, metabolic profile responses and oxidative stress in liver, evaluated the reliability of 8 reliable reference genes by 4 commonly used algorithms including GeNorm, NormFinder, BeatKeeper, Delta Ct, and then analyzed the performance of inflammatory response genes in liver, spleen and kidney with the best reference gene. HE staining revealed that the cytoplasm full small vacuoles and nucleus diameter increased were occurred in the liver cell of PP-MPs in treatment groups. Additionally, oxidative and biochemical parameters were significantly changes in the liver of treatment groups. For the reference genes in PP-MPs exposure experiments, this study screening the optimal reference genes including: EF1α and GAPDH for liver and spleen, and GAPDH and RPS18 for kidney. Besides, 2 inflammatory response genes (NLRP3, TNF-α) were chosen to assess the optimal reference genes using the least stable reference gene (TUB) as a control, verified the practicality of the select reference genes in different tissues. We also found that the low concentration of PP-MPs could induce the liver tissue damage and inflammatory response in Chinese sturgeon. Our study initially evaluated the impact of short-time exposure with PP-MPs in Chinese sturgeon and provided 3 sets of validated optimal reference genes in Chinese sturgeon exposure to PP-MPs.

Hazards of microplastics exposure to liver function in fishes: A systematic review and meta-analysis

Microplastics (5 mm - 1 μm) have become one of the major pollutants in the environment. Numerous studies have shown that microplastics can have negative impacts on aquatic organisms, affecting their liver function levels. However, the extent of these effects and their potential toxicological mechanisms are largely unknown. In this study, a meta-analysis and systematic review were conducted to assess the effects of microplastics on fish liver function and summarize the potential toxicological mechanisms of microplastic-induced liver toxicity. The meta-analysis results indicate that compared to the control group, exposure to microplastics significantly affects fish liver indicators: aspartate aminotransferase (AST) (p < 0.001), alanine aminotransferase (ALT) (p < 0.001), alkaline phosphatase (ALP) (p < 0.001), total protein (TP) (p < 0.001), and lactate dehydrogenase (LDH) (p < 0.001), including oxidative stress indicators: superoxide dismutase (SOD) (p < 0.001), glutathione S-transferase (GST) (p < 0.001), glutathione (GSH) (p < 0.001), and malondialdehyde (MDA) (p < 0.001) in fish liver. For fish living in different environments, the potential toxicological mechanisms of microplastics exposure on fish liver may exhibit some differences. For freshwater fish, the mechanism may be that microplastics exposure causes overproduction of reactive oxygen species (ROS) in fish hepatocyte mitochondria. ROS promotes the expression of toll-like receptor 2 (TLR2) and activates downstream molecules myeloid differentiation factor 88 (MyD88) and tumor necrosis factor receptor-associated factor 6 (TRAF6) of the TLR2 signaling pathway, leading to phosphorylation of NF-κB p65. This leads to the release of inflammatory factors and oxidative stress and inflammation in fish liver. In addition, for seawater fish, the mechanism may be that microplastics exposure can cause damage or death of fish hepatocytes, leading to continuous pathological changes, inflammation, lipid and energy metabolism disorders, thereby causing significant changes in liver function indexes.

Selenium yeast improve growth, serum biochemical indices, metabolic ability, antioxidant capacity and immunity in black carp Mylopharyngodnpiceus

This experiment was conducted to investigate the impacts of dietary selenium yeast (SeY) on the growth performance, fish body composition, metabolic ability, antioxidant capability, immunity and inflammatory responses in juvenile black carp (Mylopharyngodn piceus). The base diet was supplemented with 0.00, 0.30 and 0.60 g/kg SeY (0.04, 0.59 and 1.15 mg/kg of selenium) to form three isonitrogenous and isoenergetic diets for juvenile black carp with a 60-day. Adequate dietary SeY (0.30 and 0.60 g/kg) could significantly increase the weight gain (WG), special growth rate (SGR) compared to the SeY deficient groups (0.00 g/kg) (P < 0.05). Meanwhile, 0.30 and 0.60 g/kg SeY elevated the mRNA levels of selenoprotein T2 (SEPT2), selenoprotein H (SEPH), selenoprotein S (SEPS) and selenoprotein M (SEPM) in the liver and intestine compared with the SeY deficient groups (P < 0.05). Adequate dietary SeY could promote glucose catabolism and utilization through activating glucose transport (GLUT2), glycolysis (GCK, HK, PFK, PK, PDH), tricarboxylic acid cycle (ICDH and MDH), glycogen synthesis (LG, GCS and GBE) and IRS/PI3K/AKT signal pathway molecules (IRS2b, PI3Kc and AKT1) compared with the SeY deficient groups (P < 0.05). Similarly, adequate dietary SeY could improve lipid transport and triglycerides (TG) synthesis through increasing transcription amounts of CD36, GK, DGAT, ACC and FAS in the fish liver compared with the SeY deficient groups (P < 0.05). In addition, adequate SeY could markedly elevate activities of antioxidant enzymes (T-SOD, CAT, GR, GPX) and contents of T-AOC and GSH, while increased transcription amounts of Nrf2, Cu/Zn-SOD, CAT, and GPX in fish liver and intestine (P < 0.05). However, adequate SeY notably decreased contents of MDA, and the mRNA transcription levels of Keap1 in the intestine compared with the SeY deficient groups (P < 0.05). Adequate SeY markedly increased amounts or levels of the immune factors (ALP, ACP, LZM, C3, C4 and IgM) and the transcription levels of innate immune-related functional genes in the liver and intestine (LZM, C3 and C9) compared to the SeY deficient groups (P < 0.05). Moreover, adequate SeY could notably reduce levels of IL-8, IL-1β, and IFN-γ and elevate TGF-1β levels in fish intestine (P < 0.05). The transcription levels of MAPK13, MAPK14 and NF-κB p65 were notably reduced in fish intestine treated with 0.30 and 0.60 g/kg SeY (P < 0.05). In conclusion, these results suggested that 0.30 and 0.60 g/kg SeY could not only improve growth performance, increase Se, glucose and lipid metabolic abilities, enhance antioxidant capabilities and immune responses, but also alleviate inflammation, thereby supplying useful reference for producing artificial feeds in black carp.

Probabilistic risk assessment of microplastics in Tai Lake, China

Microplastics are a global environmental concern, especially in freshwater ecosystems. Despite the studies in specific regions of Tai lake, a gap persists in understanding the comprehensive risk of MPs across the entire watershed. Therefore, this study offers an overview of MPs abundance and assesses ecotoxicological risk by employing acute and chronic species sensitivity distributions, which consider the effects triggered by MPs. The concentrations of MPs ranged from 0 to 18.6 particles/L within the lake, 1.56 to 1.42 × 102 particles/L in the rivers, and 0.16 to 0.7 particles/L in the estuaries. Certain areas, particularly the northwest and southeast regions, exhibit higher concentrations. Using existing toxicity data, this study calculated predicted no effect concentrations for acute and chronic exposure of MPs to freshwater species, resulting in values of 11.5 and 31.72 particles/L, respectively. The probabilistic risk assessment indicates that the average risk possibility of MPs in Tai lake was 16 %. Moreover, the risk characterization ratio indicated that 22 % of the locations in Tai lake showed an acute ecological risk, while 7.4 % exhibit a chronic ecological risk. The assessment concluded that MPs reported in the literature could pose a considerable risk to Tai lake biota. However, the risk associated with MPs followed descending order: river >lake > estuary waters. Our research supplies valuable insights for the assessment of ecological risks associated with MPs on a whole watershed scale.

Chronic exposure to low concentrations of microplastics causing gut tissue damage but non-significant changes in the microbiota of marine medaka larvae (Oryzias melastigma)

Microplastics (MPs) have become a popular research topic due to their potential ramifications on aquatic organisms. To evaluate the ecotoxicological impacts of chronic exposure to different microplastics on marine medaka larvae, we exposed medaka larvae to 200 μg/L of polyethylene (PE-200) and polylactic acid (PLA-200) microplastics for 60 days, respectively. The results indicated that both exposures had no significant effect on fish length/weight and did not result in fish mortality. Notably, the structure of intestinal microbiota was not disrupted either. However, microscopy observations of intestinal tissue suggested that exposure to MPs resulted in inflammation of the intestinal tract of fish and significant atrophy and shedding of small intestinal villus. Linear discriminant analysis Effect Size (LEfSe) showed that intestinal enrichment of Streptomyces occurred in marine medaka larvae in both MPs treatments, while the PE-200 treatment exhibited a significant enrichment. In addition, the PICRUSt2 prediction indicated significant upregulation of the Novobiocin biosynthesis function in gut microbiota in the PE-200 treatment. Overall, multi-level assessment is necessary to determine the risk of exposure of aquatic organisms to MPs.

Non-negligible vector effect of micro(nano)plastics on tris(1,3-dichloro-2-propyl) phosphate in zebrafish quantified by toxicokinetic model

Micro(nano)plastics (MNPs) inevitably interact with coexisting contaminants and can act as vectors to affect their fate in organisms. However, the quantitative contribution of MNPs in the in vivo bioaccumulation and distribution of their coexisting contaminants remains unclear. Here, by selecting tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) as the typical coexisting contaminant, we quantified the contribution of MNPs to bioaccumulation and distribution of TDCIPP with toxicokinetic models. Results indicated that MNPs differentially facilitated TDCIPP bioaccumulation and distribution, and NPs slowed down TDCIPP depuration more significantly than MPs. Model analysis further revealed increasing contributions of MNPs to whole-fish TDCIPP bioaccumulation over time, with NPs (33-42%) contributing more than MPs (12-32%) at 48 h exposure. NPs contributed more than MPs to TDCIPP distribution in the liver (13-19% for MPs; 36-52% for NPs) and carcass (24-45% for MPs; 57-71% for NPs). The size-dependent vector effect might be attributed to the fact that MNPs promote contaminant transfer by damaging biofilm structure and increasing tissue membrane permeability, with NPs exerting stronger effects. This work demonstrated the effectiveness of using modeling tools to understand the relative importance of MNPs as contaminant vectors in the TK process and highlighted the higher contaminant transfer potential of NPs under combined exposure scenarios.

Polyethylene microplastics cause apoptosis via the MiR-132/CAPN axis and inflammation in carp ovarian

Microplastics (MPs) are widely distributed pollutants in the environment and accumulate in the aquatic environment due to human activities. Carp, a common edible aquatic organism, has been found to accumulate MPs in body. MicroRNA (miRNAs) is a non-coding short RNA that regulates protein expression by binding to target genes in various physiological processes such as proliferation, differentiation and apoptosis. The ovary is a crucial role in carp reproduction. In this study, we established a model of carp exposed to polyethylene microplastics (PE-MPs) in the aquatic environment to investigate the specific mechanism of PE-MPs causing ovarian injury and the involvement of miR-132/calpain (CAPN) axis. H&E stained sections revealed that PE-PMs induced inflammation in ovarian tissues and impaired oocyte development. TUNEL analysis showed an increased rate of apoptosis in ovarian cells treated with PE-PMs. RT-PCR and Western Blot assays confirmed that exposure to PE-MPs significantly decreased miR-132 expression while increasing CAPN expression at both mRNA and protein levels. The concentration of calcium ions was significantly increased in tissues, leading to CAPN enzyme activity increase. The expression of mitochondrial damage-related genes (bax, AIF, cyt-c, caspase-7, caspase-9, and caspase-3) was higher while the expression of anti-apoptotic genes (bcl-2 and bcl-xl) was lower. Protein levels of bax, AIF, caspase-3, bcl-2 and bcl-xl changed accordingly with the genetic alterations. Additionally, we discovered that PE-MPs can activate the p65 factor through the TRAF6/NF-kB pathway resulting in elevated production of pro-inflammatory factors IL-6, IL-1β and TNF-a which contribute to ovarian inflammation development. This study investigates the impact of PE-MPs on carp ovarian function and provides insights into miRNAs' role and their target genes.

Polystyrene microplastic alters the redox state and arsenic metabolization in the freshwater bivalve Limnoperna fortunei

Most organisms possess the capacity to metabolize arsenic (As) accumulating compounds to less toxic forms, thus minimizing the adverse effect induced by this metalloid. However, other contaminants may to interfere with As metabolism, contributing to the accumulation of more toxic compounds. Microplastics (MPs) are omnipresent in aquatic environment and may induce toxicological effects (alone or in combination with other contaminants) on living organisms. Therefore, the objective of the present study was to evaluate the effect of the exposure of the freshwater clam Limnoperna fortunei to a combination of MP (4 and 40 μg/L of polystyrene microbeads, 1.05 μm) and As (50 μg/L) for 48 h, evaluating the accumulation and metabolization of As and oxidative stress parameters, such as catalase (CAT), glutathione-S-transferase activities, total antioxidant competence, reduced glutathione (GSH), and lipid damage in the gills and digestive glands. Results revealed that low MP concentration disrupts the redox state of the digestive gland by a decrease in the antioxidant activity (CAT and total antioxidant capacity). GSH levels in the gills of animals exposed to MP (4 μg/L) alone and the combination of MP + As increased, concomitant with an increase in the percentage of toxic compounds, indicating the effect of MP on As metabolism. Although, few studies evaluated the effect of coexposure to MP + As by considering metabolization of metalloid in freshwater bivalve, our results revealed that exposure to MP reduced the metabolization capacity of As, favoring the accumulation of more toxic compounds besides the MP alone, which showed a pro-oxidant effect in L. fortunei.

Microplastics induced inflammation and apoptosis via ferroptosis and the NF-κB pathway in carp

Microplastics (MPs), a new class of pollutant that threatens aquatic biodiversity, are becoming increasingly prevalent around the world. Fish growth may be severely inhibited by microplastics, resulting in severe mortality. Exposure to microplastics increases the likelihood of intestinal injuries, but the underlying mechanisms remain equivocal. The objective of this study was to investigate the potential toxic mechanisms underlying microplastic-induced intestinal injury in fish and to assist researchers in identifying novel therapeutic targets. In this study, a model of carp exposed to microplastics was established successfully. Histological observation showed that exposure to polyethylene microplastics caused damage to the intestinal mucosal surface and a significant increase in goblet cells, which aggregated on the surface of the mucosa. The mucosal layer was observed to fall off. Lymphocytes in the intestinal wall proliferated and aggregated. TUNEL staining showed that apoptosis occurred in the group exposed to microplastics. The qPCR results showed that the expression of Ferroptosis apoptotic factors COX-2 and ACSL4 was upregulated, while the expression of TFRC, FIH1, SLC7A11, and GPX4 was downregulated. The NF-κB pathway (p-p65, IκBα), inflammatory cytokines (TNF-α, IL-8, IL-6) and apoptosis genes (Bax, Caspase3) were upregulated. Semi-quantitative detection of related proteins by Western blotting was consistent with the gene expression results. In addition, the ELISA assay showed that lipid peroxidation and inflammatory cytokines (TNF-α, IL-1β, IL-6) were increased in the microplastic exposed group. To conclude, lipid peroxidation induced by microplastics activates the NF-κB pathway and causes ferroptosis, ultimately resulting in intestinal damage and cellular apoptosis.

Evodiamine alleviates DEHP-induced hepatocyte pyroptosis, necroptosis and immunosuppression in grass carp through ROS-regulated TLR4 / MyD88 / NF-κB pathway

Di (2-ethylhexyl) phthalate (DEHP) is a neuroendocrine disruptor that can cause multi-tissue organ damage by inducing oxidative stress. Evodiamine (EVO) is an indole alkaloid with anti-inflammatory, antitumor, and antioxidant pharmacological activity. In this manuscript, the effects of DEHP and EVO on the pyroptosis, necroptosis and immunology of grass carp hepatocytes (L8824) were investigated using DCFH-DA staining, PI staining, IF staining, AO/EB staining, LDH kit, qRT-PCR and protein Western blot. The results showed that DEHP exposure upregulated reactive oxygen species (ROS) levels, promoted the expression of TLR4/MyD88/NF-κB pathway, increased the expression of genes involved in cell pyroptosis pathway (LDH, NLRP3, ASC, caspase1, IL-1β, IL-18 and GSDMD) and necroptosis-related genes (RIPK1, RIPK3 and MLKL). The expression of DEHP can also affect immune function, which can be demonstrated by variationsin the activation of antimicrobial peptides (LEAP2, HEPC, and β-defensin) and inflammatory cytokines (TNF-α, IL-2, IL-6 and IL-10). EVO regulates cellular antioxidant capacity by inhibiting ROS burst, reduces DEHP-induced cell pyroptosis and necroptosis to some extent, and restores cellular immune function, after co-exposure with EVO. The TLR4 pathway was inhibited by the co-treatment of TLR4 inhibitor TLR-IN-C34 and DEHP, which attenuated the expression of cell pyroptosis, necroptosis, and immunosuppression. Thus, DEHP induced pyroptosis, necroptosis and abnormal immune function in L8824 cells by activating TLR4/MyD88/NF-κB pathway. In addition, EVO has a therapeutic effect on DEHP-induced toxic injury. This study further provides a theoretical basis for the risk assessment of plasticizer DEHP on aquatic organisms.

Rosmarinic acid alleviates intestinal inflammatory damage and inhibits endoplasmic reticulum stress and smooth muscle contraction abnormalities in intestinal tissues by regulating gut microbiota

The host-bacterial interactions play the key role in inflammatory bowel disease (IBD). Dysbiosis of the intestinal flora can lead to pathological changes in the intestine. Rosmarinic acid (RA) is a natural phenolic acid compound with antioxidant, anti-cancer, anti-inflammatory, anti-apoptotic, anti-fibrotic, and anti-bacterial activities that has a palliative effect on acute IBD. We have established an in vivo model for mice. Histological staining was performed to directly observe RA alterations in the intestinal tract. The alteration of RA on mouse intestinal flora was observed by 16S rRNA high-throughput sequencing, and the effect of RA on intestinal mechanism of action was detected by qPCR and western blot. The results showed that RA had a significant protective effect on the intestine. RA upregulated the abundance of Lactobacillus johnsonii and Candidatus Arthromitus sp SFB-mouse-NL and downregulated the abundance of Bifidobacterium pseudolongum, Escherichia coli, and Romboutsia ilealis. RA downregulated the expressions of ROCK, RhoA, CaM, MLC, MLCK, ZEB1, ZO-1, ZO-2, occludin, E-cadherin, IL-1β, IL-6, TNF-α, GRP78, PERK, IRE1, ATF6, CHOP, Caspase12, Caspase9, Caspase3, Bax, Cytc, RIPK1, RIPK3, MLKL, and upregulated the expression of IL-10 and Bcl-2. These results displayed that RA inhibited the inflammation, which is caused by tight junction damage, by repairing intestinal flora dysbiosis, relieved endoplasmic reticulum stress, inhibited cell death, and corrected smooth muscle contractile dysregulation. The results of this study revealed RA could have a protective effect on the small intestine of mice by regulating intestinal flora. IMPORTANCE Inflammatory bowel disease (IBD) is a chronic, relapsing, remitting disorder of the gastrointestinal system. In this study, we investigated the protective effects of rosmarinic acid on the intestinal tract. The results showed that RA was effective in reducing inflammatory damage, endoplasmic reticulum stress, smooth muscle contraction abnormalities, and regulating intestinal flora disorders.

TBBPA causes inflammation and cell death via the ROS/NF-κB pathway in the gastric mucosa

Tetrabromobisphenol A (TBBPA) is a common brominated flame retardant that has a wide range of toxic effects on organisms. However, the mechanism of the toxic effects of TBBPA on the digestive system has rarely been studied. The purpose of this study was to investigate the mechanism of TBBPA toxicity on the gastric mucosa. In this study, TBBPA (mixed with corn oil) was administered by gavage at doses of 0 mg/kg (CG), 10 mg/kg and 20 mg/kg. The results showed that the levels of ROS, MDA and LPO were increased, and the activities of antioxidant enzymes were decreased. Large amounts of ROS activated the NF-κB pathway, leading to the development of an inflammatory response. The expression of BCL family and Caspase (Cas) family genes was increased, inducing apoptosis. The RIP3/MLKL pathway was activated, leading to cell necrosis. In summary, TBBPA can cause damage to the gastric mucosa through oxidative stress, leading to increased ROS activation of the NF-κB pathway. Treatment with the antioxidant NAC alleviated the damage to the gastric mucosa caused by TBBPA.

Effects of microplastics, pesticides and nano-materials on fish health, oxidative stress and antioxidant defense mechanism

Microplastics and pesticides are emerging contaminants in the marine biota, which cause many harmful effects on aquatic organisms, especially on fish. Fish is a staple and affordable food source, rich in animal protein, along with various vitamins, essential amino acids, and minerals. Exposure of fish to microplastics, pesticides, and various nanoparticles generates ROS and induces oxidative stress, inflammation, immunotoxicity, genotoxicity, and DNA damage and alters gut microbiota, thus reducing the growth and quality of fish. Changes in fish behavioral patterns, swimming, and feeding habits were also observed under exposures to the above contaminants. These contaminants also affect the Nrf-2, JNK, ERK, NF-κB, and MAPK signaling pathways. And Nrf2-KEAP1 signalling modulates redox status marinating enzymes in fish. Effects of pesticides, microplastics, and nanoparticles found to modulate many antioxidant enzymes, including superoxide dismutase, catalase, and glutathione system. So, to protect fish health from stress, the contribution of nano-technology or nano-formulations was researched. A decrease in fish nutritional quality and population significantly impacts on the human diet, influencing traditions and economics worldwide. On the other hand, traces of microplastics and pesticides in the habitat water can enter humans by consuming contaminated fish which may result in serious health hazards. This review summarizes the oxidative stress caused due to microplastics, pesticides and nano-particle contamination or exposure in fish habitat water and their impact on human health. As a rescue mechanism, the use of nano-technology in the management of fish health and disease was discussed.

Zinc deficiency causes oxidative stress, endoplasmic reticulum stress, apoptosis and inflammation in hepatocytes in grass carp

A lack of the trace element zinc (Zn) in freshwater environments causes slow growth and malnutrition and affects the normal biological functions of organisms. In this study, a Zn deficiency model of grass carp hepatocytes was established with TPEN. Acetylcysteine (NAC) was used as an inhibitor. TPEN was added to L8824 cell culture medium, and LDH, AST, ALT, and AKP activities were enhanced in a Zn-deficient environment, leading to abnormal hepatopancreas function. Fluorescence microscopy showed an increase in ROS levels, and antioxidant enzyme activity assays revealed that SOD, CAT, GSH-PX, and T-AOC activities were decreased, indicating oxidative stress caused by Zn deficiency. The RT‒PCR results showed that the mRNA expression of GRP78, PERK, EIF2α, ATF4, and Chop was increased due to the addition of TPEN. Calcium kits showed increased Ca²⁺ levels. The RT‒PCR results showed that the mRNA expression levels of Caspase-12, Caspase-9, Caspase-3, and PARP apoptotic were increased due to the addition of TPEN. RT‒PCR and ELISA showed that the expression levels of interleukin-1β (IL-1β), interleukin-8 (IL-8), tumour necrosis factor (TNF-α), and inducible nitric oxide synthase (iNOS) were increased. This led to the conclusion that Zn deficiency in the freshwater environment caused inflammation and apoptosis in hepatocytes in grass carp. For the first time, apoptosis caused by endoplasmic reticulum stress in grass carp hepatocytes due to Zn deficiency was studied in the context of Ca²⁺. The present study provided some insight into the adverse effects of Zn deficiency in freshwater environments on fish.

Performance of nitrification-denitrification and denitrifying phosphorus removal driven by in-situ generated biogenic manganese oxides in a moving bed biofilm reactor

Simultaneous removal of NH₄⁺-N, NO₃^--N, COD, and P by manganese redox cycling in nutrient wastewater was established with two moving bed biofilm reactors (MBBRs) with in-situ generated biogenic manganese oxides (BioMnOx) and non-BioMnOx. In-situ generated BioMnOx preferentially promoted the denitrification, and the average removal of NO₃^--N, NH₄⁺-N, and TN in the experimental MBBR with BioMnOx increased to 89.00%, 70.64%, and 76.06% compared with the control MBBR with non-BioMnOx. The relevant enzymes activity, extracellular polymeric substance (EPS), electron transport system activity (ETSA), and reactive oxygen species (ROS) were investigated. The element valence and morphology of purified BioMnOx were characterized by X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM), as well as the effect of BioMnOx on nitrogen and phosphorus removal. The results suggested that BioMnOx could improve nitrogen conversion. Electrochemical characteristic and microbial community were detected. This study provided a new strategy for nutrients removal in BioMnOx-mediated wastewater treatment.

Selenium deficiency induced inflammation and apoptosis via NF-κB and MAPKs pathways in muscle of common carp (Cyprinus carpio L.)

Selenium (Se), one of the essential trace elements of fish, regulates immune system function and maintains immune homeostasis. Muscle is the important tissue that generate movement and maintain posture. At present, there are few studies on the effects of Se deficiency on carp muscle. In this experiment, carps were fed with dietary with different Se content to successfully establish a Se deficiency model. Low-Se dietary led to the decrease of Se content in muscle. Histological analysis showed that Se deficiency resulted in muscle fiber fragmentation, dissolution, disarrangement and increased myocyte apoptosis. Transcriptome revealed a total of 367 differentially expressed genes (DEGs) were screened, including 213 up-regulated DEGs and 154 down-regulated DEGs. Bioinformatics analysis showed that DEGs were concentrated in oxidation-reduction process, inflammation and apoptosis, and were related to NF-κB and MAPKs pathways. Further exploration of the mechanism showed that Se deficiency led to excessive accumulation of ROS, decreased the activity of antioxidant enzymes, and also resulted in increased expression of the NF-κB and MAPKs pathways. In addition, Se deficiency significantly increased the expressions of TNF-α, IL-1β and IL-6, and the pro-apoptotic factors BAX, p53, caspase-7 and caspase-3, while decreased the expressions of anti-apoptotic factors Bcl-2 and Bcl-xl. In conclusion, Se deficiency reduced the activities of antioxidant enzymes and led to excessive accumulation of ROS, which caused oxidative stress and affected the immune function of carp, leading to muscle inflammation and apoptosis.

Comparative Transcriptome Analysis Reveals the Innate Immune Response to Mycoplasma gallisepticum Infection in Chicken Embryos and Newly Hatched Chicks

Mycoplasma gallisepticum (MG) is a major cause of chronic respiratory diseases in chickens, with both horizontal and vertical transmission modes and varying degrees of impact on different ages. The innate immune response is crucial in resisting MG infection. Therefore, this study aimed to investigate the innate immune response of chicken embryos and newly hatched chicks to MG infection using comparative RNA-seq analysis. We found that MG infection caused weight loss and immune damage in both chicken embryos and chicks. Transcriptome sequencing analysis revealed that infected chicken embryos had a stronger immune response than chicks, as evidenced by the higher number of differentially expressed genes associated with innate immunity and inflammation. Toll-like receptor and cytokine-mediated pathways were the primary immune response pathways in both embryos and chicks. Furthermore, TLR7 signaling may play an essential role in the innate immune response to MG infection. Overall, this study sheds light on the development of innate immunity to MG infection in chickens and can help in devising disease control strategies.

Polystyrene microplastics induce endoplasmic reticulum stress, apoptosis and inflammation by disrupting the gut microbiota in carp intestines

Microplastics have been recognized as a widespread new pollutant in nature and have induced an increase in the occurrence of a variety of diseases in carp. An animal model of microplastic ingestion was successfully established in an aqueous environment. The gut microbiota was analysed using a metagenomic approach. The results showed a significant reduction in the relative abundances of Lactococcus garvieae, Bacteroides_paurosaccharolyticus, and Romboutsia_ilealis after PS-MPs treatment. The 16S Silva database was used to predict and analyse the known genes. Intestinal flora disorders related to infectious diseases, cancers, neurodegenerative diseases, endocrine and metabolic diseases, cardiovascular diseases, and other diseases were found. The intake of PS-MPs resulted in damage to carp intestinal tissue and apoptosis of intestinal epithelial cells. The levels of the inflammatory cytokines IL-1β, IL-6, and TNF-α were significantly increased with the intake of PS-MPs. The gene and protein levels of GRP78, Caspase-3, Caspase-7, Caspase-9, Caspase-12, PERK, IRE1, and ATF6 were further examined in PS group. The occurrence of ERS and apoptosis in carp intestines was confirmed. These results suggest that the accumulation of PS-MPs in the aquatic environment can disturb the carp gut microbiota and induce ERS, apoptosis, and inflammation in the intestinal tissue.

Polystyrene microplastics induce myocardial inflammation and cell death via the TLR4/NF-κB pathway in carp

Microplastics (MPs) have attracted widespread attention as an emerging environmental pollutant. Especially in aquatic ecosystems, the harm of MPs to aquatic animals has increasingly become a severe environmental problem. In this study, we constructed a carp polystyrene microplastics (PS-MPs) exposure model to explore the damage and mechanism of PS-MPs exposure to carp myocardial tissue. The results of H&E, TUNEL, and AO/EB staining showed that PS-MPs exposure could induce inflammation, apoptosis, and necrosis in carp myocardial tissue and cardiomyocytes. In addition, our study explored the targeting relationship between PS-MPs and TLR4 and found that PS-MPs exposure could significantly increase the expression of TLR4 pathway-related factors. As the concentration of PS-MPs increased, the NF-κB pathway and inflammation-related factors increased dose-dependent. In addition, myocardial injury induced by exposure to PS-MPs was predominantly apoptotic, accompanied by necrosis. In short, our data suggest that PS-MPs cause damage to myocardial tissue via the TLR4\NF-κB pathway. The above findings enrich the theory of toxicological studies on PS-MPs and provide an essential reference for aquaculture.

TBBPA induced ROS overproduction promotes apoptosis and inflammation by inhibiting autophagy in mice lung

Tetrabromobisphenol A (TBBPA), a non-degradable environmental pollutant, was discharge into the air during the manufacture, use and recycling of plastic products. Respiratory exposure is the main way to inhalation of TBBPA. However, the research on the damage of TBBPA to the respiratory system is still extremely few. The aim of this experiment was to explore the mechanism of TBBPA toxicity to the lungs. Forty C57BL/6 J mice randomly divided into 4 groups, and the experimental groups with TBBPA at 10 n M/kg, 20 n M/kg and 40 n M/kg for 14 consecutive days. Histopathological and ultrastructural analysis showed that the inflammatory cells infiltrated and tissue structure damaged in the lung of mice with exposing to TBBPA. The ROS and MDA levels increase and the T-AOC, GSH-Px, CAT, SOD activities inhibition was found in lung tissue with TBBPA exposure. The expression of autophagy-related factors Beclin-1, P62, LC3-II, ATG5, and ATG7 decreased. The activation of NF-κB/TNF-α pathway indicates the occurrence of inflammation. The expression of Bax, caspase3, caspase7, caspase 9 increase, the expression of Bcl-2 decreased, and the apoptosis pathway activated. The autophagy inducer rapamycin can reverse the adverse effects of inflammation and apoptosis. Taken together, TBBPA inhibits autophagy-induced pneumonia and apoptosis by overproduction ROS.