Tolerance and dose-response assessment of subchronic dietary ethoxyquin exposure in Atlantic salmon (Salmo salar L.)

Lateral flow immunochromatographic assay based on computational chemistry-assisted hapten screening for the detection of ethoxyquin in food samples

Ethoxyquin (EQ), widely used as a potent antioxidant in intensive agricultural, requires reliable analytical methods for rapid detection due to its toxicological risks and potential for widespread contamination. In this study, computer-assisted molecular simulations were utilized to screen for a novel hapten through conformational studies and electronic analyses. Monoclonal antibodies against EQ were prepared using hybridoma technology, exhibiting a half-maximal inhibitory concentration of 9.54 ng/mL. A gold nanoparticles-based lateral flow immunochromatographic assay (LFIA) was established for the analysis of EQ in apples, pears, and fish meat, with quantitative detection ranges of 0.03-0.42 mg/kg, 0.03-0.70 mg/kg, and 0.04-0.93 mg/kg, respectively. The spiking recoveries of LFIA for real samples ranged from 88.63 % to 106.90 %, with RSDs between 2.24 % and 7.93 %. These results align with the instrumental method, indicating that this immunoassay can accurately and efficiently detect EQ residues in foodstuffs in resource-limited areas.

Target and suspect screening approaches for the identification of emerging and other contaminants in fish feeds using high resolution mass spectrometry

Fish feed is essential in aquaculture fish production because, along with beneficial nutrients and components, many suspected compounds can be transferred to fish and ultimately to humans. In this context, a comprehensive analysis was conducted to monitor various pesticides and pharmaceutical compounds in aquaculture fish feed through target analysis and many other groups of chemicals via suspect screening approaches. In this study, the QuEChERS extraction method was optimized, validated, and applied to fifty-four fish feed samples collected from different production batches. This was followed by liquid chromatography-high-resolution linear ion trap/Orbitrap mass spectrometry (LC-HR-IT/Orbitrap-MS) for targeted and suspect screening purposes. In general, pesticides provided satisfactory recoveries (70-105.5 %), with quantification limits lower than 5 ng g-1, whereas pharmaceuticals displayed recoveries ranging from 70.5 to 120.2 %, with quantification limits below 25 ng g-1. In addition, the matrix effects and measurement uncertainty were assessed to provide more accurate and high-confidence results. Pirimiphos-methyl was detected and quantified in 20 of 54 fish feed samples (37 %) at concentrations <77 ng g-1. Finally, suspect screening revealed the occurrence of 10 mycotoxins (e.g., citrinin, aflatoxin G2, zearalenone, and alternariol), two pesticides excluding the target pesticides (tebuconazole and fenazaquin), perfluorooctane sulfonic acid (PFOS) in almost 2 % of the samples, and ethoxyquin (antioxidant), with 12 of its Transformation Products (TPs). Finally, suspect analysis incorporated in routine analyses have proven to have great potential for complete monitoring.

Ethoxyquin attenuates enteric oxidative stress and inflammation by promoting cytokine expressions and symbiotic microbiota in heat-stressed broilers

Intestinal oxidative stress in broilers is produced by chronic heat stress (HS) and has a negative impact on poultry performance as it induces intestinal inflammation and promotes the invasion of gram-negative bacteria, such as bacterial lipopolysaccharide (LPS). Therefore, dietary inclusion of the antioxidant compound, ethoxyquin (EQ), could improve enteric antioxidant capacity, immune responses, and the epithelial barrier, and maintain the symbiotic gut microbiota community. To investigate the effects of EQ supplementation on alleviating enteric oxidative stress in heat-stressed broilers, 200 one-day-old male Ross 308 broilers were randomly assigned to 4 groups (n = 50 chicks/group; n = 10 chicks/replicate) and fed a basal diet supplemented with 0 (CT), 50 (EQ-50), 100 (EQ-100), and 200 (EQ-200) mg EQ/ kg-1 for 5 wk. The chicks were raised in floor pens inside the broiler farm at a temperature and humidity index (THI) of 29 from d 21 to d 35. Growth performance traits, relative organ index, hepatic antioxidant enzymes, serum immunity, total adenylate, and cytokine activities were improved in the EQ-50 group (linear or quadratic P < 0.05), promoting the relative mRNA expression of cytokine gene-related anti-inflammatory and growth factors. A distinct microbial community colonised the gut microbiota in the EQ-50 group, with a high relative abundance of Lactobacillus, Ligilactobacillus, Limosilactobacillus, Pediococcus, Blautia, and Faecalibacterium compared to the other groups. Dietary supplementation with 50 mg EQ/ kg-1 for 5 wk attenuates enteric oxidative stress and intestinal inflammation by enhancing serum immune and cytokine content (IgG, IL-6, and TGF-β,) and symbiotic microbiota in heat-stressed broilers. EQ promotes the expression of Hsp70, SOD2, GPx 4, IL-6, and IGF-1 cytokine gene-related anti-inflammatory and growth factors in heat-stressed hepatic broilers. Collectively, EQ-50 could be a suitable feed supplement for attenuating enteric oxidative stress and intestinal inflammation, thereby promoting the productivity of heat-stressed broilers.

Dietary Resveratrol Ameliorates Hepatic Fatty Acid Metabolism and Jejunal Barrier in Offspring Induced by Maternal Oxidized Soybean Oil Challenge

Increasing evidence indicates that maternal exposure to oxidized soybean oil (OSO) causes damage to the mother and offspring. The antioxidant resveratrol (Res) has a variety of health benefits. However, the protective effect of Res on mitigating offspring damage after maternal exposure to OSO and its mechanism remains unclear. Therefore, this study aimed to investigate the effect of Res on hepatic fatty acid metabolism and the jejunal barrier in suckling piglets after maternal OSO exposure. A total of 18 sows in late gestation were randomly assigned to three treatments. The sows were fed with a fresh soybean oil (FSO) diet, an OSO diet, or the OSO diet supplemented with 300 mg/kg Res (OSO + Res), respectively. The results showed that maternal supplementation of Res restored the mRNA levels of genes related to fatty acid metabolism and increased the activities of catalase (CAT) and total superoxide dismutase (T-SOD) in suckling piglets' livers under the OSO challenge. Moreover, the OSO + Res group restored the mRNA levels of occludin and claudin 4 in suckling piglet jejunum compared with the results of the OSO challenges. In summary, supplementation with Res improves hepatic fatty acid metabolism and intestinal barrier function of suckling piglets after maternal OSO challenge during late gestation and lactation.

Multi-tissue proteogenomic analysis for mechanistic toxicology studies in non-model species

New approach methodologies (NAM), including omics and in vitro approaches, are contributing to the implementation of 3R (reduction, refinement and replacement) strategies in regulatory science and risk assessment. In this study, we present an integrative transcriptomics and proteomics analysis workflow for the validation and revision of complex fish genomes and demonstrate how proteogenomics expression matrices can be used to support multi-level omics data integration in non-model species in vivo and in vitro. Using Atlantic salmon as an example, we constructed proteogenomic databases from publicly available transcriptomic data and in-house generated RNA-Seq and LC-MS/MS data. Our analysis identified ∼80,000 peptides, providing direct evidence of translation for over 40,000 RefSeq structures. The data also highlighted 183 co-located peptide groups that supported a single transcript each, and in each case, either corrected a previous annotation, supported Ensembl annotations not present in RefSeq, or identified novel previously unannotated genes. Proteogenomics data-derived expression matrices revealed distinct profiles for the different tissue types analyzed. Focusing on proteins involved in defense against xenobiotics, we detected distinct expression patterns across different salmon tissues and observed homology in the expression of chemical defense proteins between in vivo and in vitro liver systems. Our study demonstrates the potential of proteogenomic analyses in extending our understanding of complex fish genomes and provides an advanced bioinformatic toolkit to support the further development of NAMs and their application in regulatory science and (eco)toxicological studies of non-model species.

Identification of the metabolic state of surviving cardiomyocytes in the human infarcted heart by spatial single-cell transcriptomics

The metabolic status of surviving cardiomyocytes (CM) in the myocardial tissues of patients who sustained myocardial infarction (MI) is largely unknown. Spatial single-cell RNA-sequencing (scRNA-seq) is a novel tool that enables the unbiased analysis of RNA signatures within intact tissues. We employed this tool to assess the metabolic profiles of surviving CM in the myocardial tissues of patients post-MI.

Methods

A spatial scRNA-seq dataset was used to compare the genetic profiles of CM from patients with MI and control patients; we analyzed the metabolic adaptations of surviving CM within the ischemic niche. A standard pipeline in Seurat was used for data analysis, including normalization, feature selection, and identification of highly variable genes using principal component analysis (PCA). Harmony was used to remove batch effects and integrate the CM samples based on annotations. Uniform manifold approximation and projection (UMAP) was used for dimensional reduction. The Seurat "FindMarkers" function was used to identify differentially expressed genes (DEGs), which were analyzed by the Gene Ontology (GO) enrichment pathway. Finally, the scMetabolism R tool pipeline with parameters method = VISION (Vision is a flexible system that utilizes a high-throughput pipeline and an interactive web-based report to annotate and explore scRNA-seq datasets in a dynamic manner) and metabolism.type = Kyoto Encyclopedia of Genes and Genomes (KEGG) was used to quantify the metabolic activity of each CM.

Results

Analysis of spatial scRNA-seq data showed fewer surviving CM in infarcted hearts than in control hearts. GO analysis revealed repressed pathways in oxidative phosphorylation, cardiac cell development, and activated pathways in response to stimuli and macromolecular metabolic processes. Metabolic analysis showed downregulated energy and amino acid pathways and increased purine, pyrimidine, and one-carbon pool by folate pathways in surviving CM.

Conclusions

Surviving CM within the infarcted myocardium exhibited metabolic adaptations, as evidenced by the downregulation of most pathways linked to oxidative phosphorylation, glucose, fatty acid, and amino acid metabolism. In contrast, pathways linked to purine and pyrimidine metabolism, fatty acid biosynthesis, and one-carbon metabolism were upregulated in surviving CM. These novel findings have implications for the development of effective strategies to improve the survival of hibernating CM within the infarcted heart.

Effects of oxidized soybean oil on the performance of sows and jejunum health of suckling piglets

Oils provide a considerable amount of energy to the swine diet, but they are prone to lipid oxidation if not properly preserved. Consumption of oxidized oils can adversely affect the animal organism and even the offspring. This study investigated the impact of oxidized soybean oil in the diets of sows from 107 days gestation to 21 days of lactation on the performance of sows and jejunum health of suckling piglets. Sixteen sows were randomly allocated into two groups: one group (n = 8) was fed with the fresh soybean oil (FSO) diet, and another group (n = 8) was treated with the oxidized soybean oil (OSO) diet. Dietary oxidized soybean oil does not affect sow performance. Antioxidant enzyme activity in the milk was reduced significantly in the OSO group, such as the superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and catalase (CAT) activities (p < 0.05). On Day 21, oxidized soybean oil increased tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), and interleukin 8 (IL-8) levels in sow milk and the concentrations of TNF-α and IL-8 cytokines in plasma (p < 0.05). Suckling piglets from sows fed on OSO showed a trend towards increased IL-6 and TNF-α in plasma (p < 0.1). The mRNA expression of interleukin 1β (IL-1β) was augmented, whereas interleukin 10 (IL-10) was decreased, and zonula occludens-1 (ZO-1) had a tendency to be down-regulated in OSO treatment. This study revealed that the OSO of feed decreased the antioxidant capacity of milk, further contributing to the inflammatory response in the jejunum of suckling piglets.

Use of (Q)SAR genotoxicity predictions and fuzzy multicriteria decision-making for priority ranking of ethoxyquin transformation products

Ethoxyquin (EQ; 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline) has been used as an antioxidant in feed for pets and food-producing animals, including farmed fish such as Atlantic salmon. In Europe, the authorization for use of EQ as a feed additive was suspended, due to knowledge gaps concerning the presence and toxicity of EQ transformation products (TPs). Recent analytical studies focusing on the detection of EQ TPs in farmed Atlantic salmon feed and fillets reported the detection of a total of 27 EQ TPs, comprising both known and previously not described EQ TPs. We devised and applied an in silico workflow to rank these EQ TPs according to their genotoxic potential and their occurrence data in Atlantic salmon feed and fillet. Ames genotoxicity predictions were obtained applying a suite of five (quantitative) structure-activity relationship ((Q)SAR) tools, namely VEGA, TEST, LAZAR, Derek Nexus and Sarah Nexus. (Q)SAR Ames genotoxicity predictions were aggregated using fuzzy analytic hierarchy process (fAHP) multicriteria decision-making (MCDM). A priority ranking of EQ TPs was performed based on combining both fAHP ranked (Q)SAR predictions and analytical occurrence data. The applied workflow prioritized four newly identified EQ TPs for further investigation of genotoxicity. The fAHP-based prioritization strategy described here, can easily be applied to other toxicity endpoints and groups of chemicals for priority ranking of compounds of most concern for subsequent experimental and mechanistic toxicology analyses.

Ethoxyquin and Butylated Hydroxy Toluene Distrub the Hematological Parameters and Induce Structural and Functional Alterations in Liver of Rats

The current experiment aimed to assess the effect of the synthetic antioxidants ethoxyquin (EQ) and/or butylated hydroxytoluene (BHT) on the liver function tests, hematological parameters, and liver histoarchitecture in rats. A total of 50 male Sprague-Dawley rats were divided into five groups of 10 animals per group. The first group served as the control and did not receive any treatments, and the second group served as the vehicle control and was orally administrated 1 ml of corn oil day after day for consecutive 45 and 90 days. The third group (EQ) was orally administered 1 ml of EQ dissolved in corn oil day after day for consecutive 45 and 90 days in a dose of 1/5 LD50, and the fourth group (BHT) was orally received 1 ml of BHT dissolved in corn oil day after day for consecutive 45 and 90 days in a dose of 1/5 LD50. The fifth group (combination group) was orally administered both EQ and BHT at the same doses and durations described above. The present results showed that the final body weight was significantly decreased in the EQ- or BHT-treated group particularly at 90 days of exposure to both compounds. Furthermore, the liver weight was significantly elevated in EQ, BHT, and co-exposed groups at 45 and 90 days of exposure, compared to the control group. Moreover, EQ, BHT, and their co-exposure caused a significant elevation in the levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) enzymes, as well as total bilirubin at 45 and 90 days of exposure. On the other hand, there was no significant change in the total albumin. Hemoglobin value, red blood cells, white blood cells, platelets, and differential leucocyte count at 45 and 90 days of exposure were significantly decreased. Histopathological significant findings in the liver were observed as vascular congestions, vacuolations, hydropic degenerations, lipidosis, and swelling, particularly in the co-exposed group for 90 days. These findings confirmed the hepatotoxic potential of EQ and BHT; therefore, it is recommended to control and limit the utilization of such chemicals.