ABSTRACT
Since the run off of microplastic and plastic additives into the aquatic environment through the disposal of plastic products, we investigated the adverse effects of co-exposure to microplastics and plastic additives on zebrafish embryonic development. To elucidate the combined effects between microplastic mixtures composed of microplastics and plastic additives in zebrafish embryonic development, polystyrene (PS), bisphenol S (BPS), and mono-(2-ethylhexyl) phthalate (MEHP) were chosen as a target contaminant. Based on non-toxic concentration of each contaminant in zebrafish embryos, microplastic mixtures which is consisted of binary and ternary mixed forms were prepared. A strong phenotypic toxicity to zebrafish embryos was observed in the mixtures composed with non-toxic concentration of each contaminant. In particular, the mixture combination with ≤ EC10 values for BPS and MEHP showed a with a strong synergistic effect. Based on phenotypic toxicity to zebrafish embryos, change of transcription levels for target genes related to cell damage and thyroid hormone synthesis were analyzed in the ternary mixtures with low concentrations that were observed non-toxicity. Compared with the control group, cell damage genes linked to the oxidative stress response and thyroid hormone transcription factors were remarkably down-regulated in the ternary mixture-exposed groups, whereas the transcriptional levels of cyp1a1 and p53 were significantly up-regulated in the ternary mixture-exposed groups (P < 0.05). These results demonstrate that even at low concentrations, exposure to microplastic mixtures can cause embryonic damage and developmental malformations in zebrafish, depending on the mixed concentration-combination. Consequently, our findings will provide data to examine the action mode of zebrafish developmental toxicity caused by microplastic mixtures exposure composed with microplastics and plastic additives.
Subject(s)
Diethylhexyl Phthalate , Embryo, Nonmammalian , Embryonic Development , Microplastics , Phenols , Plastics , Water Pollutants, Chemical , Zebrafish , Animals , Zebrafish/embryology , Water Pollutants, Chemical/toxicity , Microplastics/toxicity , Embryo, Nonmammalian/drug effects , Diethylhexyl Phthalate/toxicity , Diethylhexyl Phthalate/analogs & derivatives , Phenols/toxicity , Plastics/toxicity , Embryonic Development/drug effects , Sulfones/toxicity , Polystyrenes/toxicity , Gene Expression Regulation, Developmental/drug effectsABSTRACT
Weathered microplastics (MPs) exhibit different physicochemical properties compared to pristine MPs, thus, their effects on the environment and living organisms may also differ. In the present study, we investigated the gut-toxic effects of virgin polypropylene MPs (PP) and UV-weathered PP MPs (UV-PP) on zebrafish. The zebrafish were exposed to the two types of PP MPs at a concentration of 50 mg/L each for 14 days. After exposure, MPs accumulated primarily within the gastrointestinal tract, with UV-PP exhibiting a higher accumulation than PP. The ingestion of PP and UV-PP induced gut damage in zebrafish and increased the gene expression and levels of enzymes related to oxidative stress and inflammation, with no significant differences between the two MPs. Analysis of the microbial community confirmed alterations in the abundance and diversity of zebrafish gut microorganisms in the PP and UV-PP groups, with more pronounced changes in the PP-exposed group. Moreover, the Kyoto Encyclopedia of Genes and Genomes pathway analysis confirmed the association between changes in the gut microorganisms at the phylum and genus levels with cellular responses, such as oxidative stress, inflammation, and tissue damage. This study provides valuable insights regarding the environmental impact of MPs on organisms.
Subject(s)
Gastrointestinal Microbiome , Microplastics , Polypropylenes , Ultraviolet Rays , Water Pollutants, Chemical , Zebrafish , Animals , Microplastics/toxicity , Polypropylenes/toxicity , Gastrointestinal Microbiome/drug effects , Gastrointestinal Microbiome/radiation effects , Water Pollutants, Chemical/toxicity , Oxidative Stress/drug effects , Gastrointestinal Tract/drug effects , Gastrointestinal Tract/radiation effectsABSTRACT
With the advancement of cementitious material technologies, ultra-high performance concretes incorporating nano- and(or) micro-sized particle materials have been developed; however, their environmental risks are still poorly understood. This study investigates the ecotoxicological effects of ultra-high performance concrete (UC) leachate by comparing with that of the conventional concrete (CC) leachate. For this purpose, a dynamic leaching test and a battery test with algae, water flea, and zebrafish were performed using standardized protocols. The conductivity, concentration of inorganic elements (Al, K, Na, and Fe), and total organic concentration were lower in the UC leachate than in the CC leachate. The EC50 values of the CC and UC leachates were 44.9 % and >100 % in algae, and 8.0 % and 63.1 % in water flea, respectively. All zebrafish exposed to the CC and UC leachates survived. A comprehensive evaluation of the ecotoxicity of the CC and UC leachate based on the toxicity classification system (TCS) showed that their toxicity classification was "highly acute toxicity" and "acute toxicity", respectively. Based on the hazard quotient and principal component analysis, Al and(or) K could be significant factors determining the ecotoxicity of concrete leachate. Furthermore, the ecotoxicity of UC could not be attributed to the use of silica-based materials or multi-wall carbon nanotubes. This study is the first of its kind on the ecotoxicity of UC leachate in aquatic environments, and the results of this study can be used to develop environment-friendly UC.
Subject(s)
Aquatic Organisms , Construction Materials , Water Pollutants, Chemical , Zebrafish , Animals , Water Pollutants, Chemical/toxicity , Aquatic Organisms/drug effects , Ecotoxicology , Cladocera/drug effects , Toxicity TestsABSTRACT
Since the onset of the COVID-19 pandemic, there has been an increase in the use of disposable plastics and disinfectants. This study systematically investigated the adsorption behavior and mechanisms of benzalkonium chlorides (BACs), commonly used disinfectants, on polypropylene (PP) and polyethylene terephthalate (PET) microplastics (MPs), considering various factors, such as characteristics of MPs, alkyl chain length of BACs, and environmental conditions. Our results demonstrated a higher adsorption capacity for PP-MPs with relatively hydrophobic properties compared to PET-MPs, where longer alkyl chains in BACs (i.e., higher octanol-water partition coefficients, Kow) significantly enhanced adsorption through hydrophobic interactions. The inverse relationship between particle size of MPs and adsorption was evident. While changes in pH minimally affected adsorption on PP-MPs, adsorption on PET-MPs increased with rising pH, highlighting the influence of pH on electrostatic interactions. Moreover, MP aging with UV/H2O2 amplified BAC adsorption on PP-MPs due to surface oxidation and fragmentation, whereas the properties of PET-MPs remained unaltered, resulting in unchanged adsorption capacities. Spectroscopy studies and density functional theory (DFT) calculations confirmed hydrophobic and electrostatic interactions as the primary adsorption mechanisms. These findings improve our understanding of MPs and BACs behavior in the environment, providing insights for environmental risk assessments related to combined pollution.
ABSTRACT
Parabens, a group of alkyl esters of p-hydroxybenzoic acid, have been found in aquatic systems in particular, leading to concerns about their potential impact on ecosystems. This study investigated the effects of three commonly used parabens, methylparaben (MeP), ethylparaben (EtP), and propylparaben (PrP), on the brackish water flea Diaphanosoma celebensis. The results showed that PrP had the most adverse impact on survival rates, followed by EtP and MeP, while MeP and EtP induced significant adverse effects on reproductive performance. A transcriptome analysis revealed significant differential gene expression patterns in response to paraben exposure, with MeP associated with the most significant effects. MeP and EtP exposure produced greater disruption in the microbiota of D. celebensis than did PrP compared with control groups, and we identified eight key microbiota, including Ruegeria and Roseovarius. Correlation analysis between transcriptome and microbiome data revealed key interactions between specific microbiota and host gene expression. Certain microbial taxa were associated with specific genes (e.g. cuticle related genes) and toxicological pathways, shedding light on the complex molecular response and in vivo toxicity effects of parabens. These findings contribute to a deeper understanding of the molecular mechanisms underlying paraben toxicity and highlight the importance of considering the ecological impact of chemical contaminants in aquatic ecosystems.
Subject(s)
Cladocera , Parabens , Animals , Parabens/analysis , Transcriptome , Ecosystem , Saline WatersABSTRACT
A novel null HLA-A*24 allele, HLA-A*24:608N, was identified in five Korean subjects including three from a family and two separate individuals. This study was performed to discern its immunological function in transplantation settings. Because this null variant had deletions of approximately 12 k base pairs from intron 3 to 3' end of the HLA-A gene, low resolution HLA typing and amplicon-based next generation sequencing (NGS) typing methods had failed to assign it. Hybrid capture-based NGS method confirmed that this novel variant had a large deletion. T-lymphocyte crossmatching by complement-dependent lymphocytotoxicity and flow cytometry with a serum consisting anti-HLA-A24 antibody revealed negative results, implying that an individual with this allele would not carry a functioning A24 antigen. These findings highlight the importance of identifying a null HLA allele by employing appropriate molecular method and providing expected crossmatching outcomes in a real-world transplantation setting.
Subject(s)
HLA-A Antigens , High-Throughput Nucleotide Sequencing , Humans , Alleles , Histocompatibility Testing/methods , Introns , HLA-A Antigens/genetics , Republic of Korea , High-Throughput Nucleotide Sequencing/methodsABSTRACT
Perchlorate, a widespread environmental contaminant originating from various industrial applications, agricultural practices, and natural sources, poses potential risks to ecosystems and human health. While previous studies have highlighted its influence on the thyroid endocrine system and its impact on gonadal maturation, reproduction, and sex hormone synthesis, the specific interplay between thyroid and steroid hormones, in this context, remains largely unexplored. Therefore, this study was undertaken to investigate the adverse effects and underlying mechanisms triggered by exposure to sodium perchlorate (SP) on reproductive endocrine activity in zebrafish. For 21 d, the fish were exposed to test SP concentrations (0, 3, 30, 300 mg/L), which were determined based on the exposure concentrations that induced various toxic effects in the fish, considering naturally occurring concentrations. Exposure to SP, except at 3 mg/L in males, significantly decreased the production of thyroid hormone (TH) in both female and male zebrafish. Moreover, gonadal steroid levels were markedly reduced in both sexes. The expression of hepatic vitellogenin (VTG) mRNA in female zebrafish was significantly decreased, whereas aromatase activity in male zebrafish was significantly elevated in the SP exposure groups. The reduced levels of THs and gonadal steroid hormones were strongly correlated. Abnormal responses to SP exposure led to reduced reproductive success in the 300 mg/L SP exposure group. These findings indicate that prolonged and continuous exposure to a specific concentration of SP may lead to long-term reproductive problems in zebrafish, primarily through hormonal imbalances and suppression of hepatic VTG mRNA expression.
Subject(s)
Water Pollutants, Chemical , Zebrafish , Animals , Humans , Female , Male , Zebrafish/metabolism , Perchlorates/toxicity , Perchlorates/metabolism , Thyroid Gland/metabolism , Reproductive Health , Ecosystem , Gonads , Gonadal Steroid Hormones/metabolism , Reproduction , Steroids/metabolism , RNA, Messenger/metabolism , Vitellogenins/metabolism , Water Pollutants, Chemical/metabolismABSTRACT
The objective of this study was to assess the thyroid hormone disruption and reproductive dysfunction effects of the bioaccumulation and rate of mechanism in zebrafish exposed to tris(1,3-dichloro-2-propyl) phosphate (TDCPP), with stress responsiveness. The fish were exposed to test concentrations of TDCPP (0, 0.06, 0.3, 1.5 µg/mL) for 21 days, in accordance with no observed adverse effect level (i.e., < EC10) for zebrafish embryos. The bioaccumulation of TDCPP was found to be significantly higher in female zebrafish, while the metabolic rate was significantly higher in male zebrafish at all concentrations studied. The thyroid hormone (triiodothyronine [T3] and thyroxine [T4]) levels and sex steroid (i.e., estrogen, androgen, and progesterone) levels were significantly increased only in female zebrafish exposed to TDCPP, and no significant difference was observed in male zebrafish, although their cortisol levels increased. The response to TDCPP can, therefore, be considered sex-specific. The results of this study demonstrate for the first time, that the different response in the bioaccumulation and metabolic rate of TDCPP in males and females. The results also indicate that TDCPP alters thyroid hormone levels, furthermore, as steroidogenesis is related to reproductive function with differing response in males and females. TDCPP can be assumed to exert reproductive toxicity via disruption of thyroid and steroid synthesis through a slow metabolic rate in the whole body after exposure. Consequently, our proposed methodological approach to assess the interactions of thyroid and steroid biosynthesis and metabolic rate of TDCPP with reproductive toxicity will serve a testing strategy to examine the adverse outcomes of emerging environmental chemicals.
ABSTRACT
Recently, the environmental and agricultural impact of plastic waste has attracted considerable attention. Here, we investigated the impact of sub-micron polyethylene (PE) and polypropylene (PP) microplastics (MPs) on nitrogen cycling, with emphasis on bacterial abundance and diversity in a soil-soybean (Glycine max) system. Exposure to soil containing MPs (50 and 500 mg kg-1) did not affect soybean growth, but significantly increased plant nitrogen uptake, which was confirmed by increased activities of nitrogenase in the soil and glutamine synthetase in soybean root. Additionally, there was an increase in 16S gene copy number and carbon and nitrogen substrate utilization, indicating increased abundance and activity of rhizosphere microbial communities. Moreover, MP contamination affected the taxonomic profile of rhizosphere bacteria, especially the abundance of symbiotic and free-living bacteria involved in nitrogen cycling. Furthermore, qPCR analysis of nitrogen-related genes and Kyoto Encyclopedia of Genes and Genomes analysis of 16S rRNA gene sequencing data revealed an increased abundance of functional genes associated with nitrogen fixation and nitrification. However, the concentration and polymer type of MPs did not have a significant impact in our system. Overall, these results provide insights into the interactions between MPs and rhizosphere bacterial communities in the soil-legume system.
Subject(s)
Fabaceae , Microplastics , Plastics , Soil , RNA, Ribosomal, 16S/genetics , Vegetables , Glycine maxABSTRACT
Bisphenol S (BPS), an organic compound and bisphenol analog, is commonly used as a substitute for bisphenol A. BPS is widely used in epoxy glues, can coatings, and thermal receipt papers; however, its risks have not been fully determined and the probability of its toxicity has been continuously suggested. In this study, we conducted BPS toxicity tests on aquatic plants (acute), cladocerans (acute and chronic), and fish (chronic) to determine its adverse effects, and calculated the toxicity values. Additionally, we conducted an ecological risk assessment of BPS in freshwater ecosystems with toxicity data from previous studies using the species sensitivity distribution method and BPS exposure data from 14 rivers in four countries in Asia (China, Japan, India, and South Korea). The chronic-based risk quotient (RQ) values of BPS in one river in China and two rivers in India were > 1, indicating a high ecological risk of BPS to aquatic organisms. The other four rivers in China showed medium ecological risk (0.1 < RQ < 1) and those in Japan and South Korea showed negligible chronic risk (RQ < 0.1) to aquatic organisms. We also suggest sensitive indicators in the model organism Danio rerio and highlighted the importance of the development of new method of ecological risk assessment. This study could provide new information that will assist in managing BPS and bisphenol analogs in freshwater ecosystems.
Subject(s)
Water Pollutants, Chemical , Zebrafish , Animals , Ecosystem , Water Pollutants, Chemical/toxicity , Water Pollutants, Chemical/analysis , Aquatic Organisms , Asia , Risk Assessment , Benzhydryl Compounds/toxicity , Benzhydryl Compounds/analysisABSTRACT
This study aimed to examine the impact of chronic (30 days) exposure to polystyrene microplastics (PS-MPs) of different sizes (50â¯nm and 2⯵m) and at different concentrations (0.5⯵g/L and 100â¯mg/L) to marine copepod Tigriopus japonicus. Polystyrene microplastics affected survival rates in size- and concentration-dependent manners. The LC50s values of 50â¯nm and 2⯵m PS-MPs were 0.10â¯mg/L and 3.92â¯mg/L, respectively. The developmental time was delayed by 50â¯nm PS-MPs, and Usp expression was downregulated. Reproduction was negatively affected by 2⯵m PS-MPs even at environmentally relevant concentrations; however, the expression of Vtg was not altered. The production rates of reactive oxygen species and nitric oxide also increased after exposure to PS-MPs; but this effect was independent of particle size. The expression levels of Cat and Tnf, genes related to oxidative stress and inflammation, respectively, were upregulated by exposure to PS-MPs, independently of particle size. Meanwhile, the level of oxidative stress in T. japonicus was not significantly affected by PS-MPs at environmentally relevant concentrations. This study suggests that nano-sized PS-MPs are not always more toxic than micro-sized PS-MPs, and that oxidative stress is a key factor in determining the toxic effect on T. japonicus at high concentrations.
Subject(s)
Copepoda , Water Pollutants, Chemical , Animals , Microplastics , Plastics , Polystyrenes/toxicity , Reproduction , Water Pollutants, Chemical/toxicityABSTRACT
Biokinetic information on microplastics in bivalves is required to reduce the human exposure, but little is known about the time-course and size effect on tissue absorption and clearance. The biokinetics of fluorophore-labeled polystyrene microbeads with diameters 10 µm (PL10) and 90 µm (PL90) in Mytilus galloprovincialis marine mussels was investigated in the present study. It was found that both PL10 and PL90 showed a biphasic tissue distribution pattern in digestive and non-digestive tissues, highlighting the significant tissue distribution starting from 48 h post-treatment. The differential size effect on tissue distribution was observed only in the gills, which suggests that PL10 accumulates more than PL90. The depuration kinetics show that particles of both sizes can be cleared in any tissue, but non-digestive tissue requires a longer duration for depuration than digestive tissue. The differential size effect on depuration was observed for both digestive and non-digestive tissues, suggesting that PL10 needed a longer duration for depuration than PL90. More than seven days were needed for depuration of microplastics in mussels, which is an exceptionally longer period compared to conventional depuration of bivalves. The most significant improvement of this study is providing the biokinetics of two different-sized microplastics in mussels and the differential time for purging microplastics from mussels.
Subject(s)
Mytilus , Water Pollutants, Chemical , Animals , Humans , Microplastics , Plastics , Polystyrenes , Water Pollutants, Chemical/analysisABSTRACT
Hemopexin is a vital glycoprotein for processing excessive iron in blood and functions as an iron scavenger in mammals. Teleosts however, unlike mammals, have two known hemopexin paralogs called warm temperature acclimation-related 65 kDa protein (Wap65-1 and Wap65-2, collectively termed Wap65s). Although Wap65s in rainbow trout have been considered notable biomarkers with significantly higher and/or lower expression under conditions of stress or disease, the individual roles, similarities and differences between the two paralogs are not well known. The aim of this study was to gain an understanding of the characteristics and functions of trout Wap65s from the perspective of iron-metabolism, physiological roles, and relevant immunological responses. The expression of Wap65-1 and -2 in this study was determined in the face of challenges by Aeromonas salmonicida, infectious hematopoietic necrosis virus (IHNV), and iron-dextran. Immuno-histochemistry (IHC) was employed to localize the major cell types for Wap65-2 expression, and trout leukocytes were isolated and incubated with LPS and OxLDL for comprehending the immunological characteristics of Wap65-2. We demonstrate that Wap65-1 is expressed only in the liver but Wap65-2 is systemically expressed in most organs and tissues. Interestingly, Wap65-1 expression was not significantly changed under A. salmonicida and iron-dextran administration, but was significantly decreased under IHNV. In contrast, Wap65-2 was up-regulated in all challenged groups, however with different expression patterns in the blood and liver. These results suggested that the two paralogs may participate in different biological roles. IHC showed that Wap65-2 antibody had high affinity for leukocyte-like cells, and macrophages but not lymphocytes significantly increased expression under LPS and OxLDL stimulation. These results support the conclusion that trout Wap65-2, not Wap65-1 may have conventional hemopexin functions such as reported in mammals including effects on iron metabolism, inflammation, and acute-phase protein.
Subject(s)
Fish Diseases , Oncorhynchus mykiss , Acclimatization , Amino Acid Sequence , Animals , Dextrans , Fish Proteins/metabolism , Hemopexin/chemistry , Hemopexin/genetics , Hemopexin/metabolism , Iron , Lipopolysaccharides , Mammals , Phylogeny , TemperatureABSTRACT
The ingestion and accumulation of microplastics is a serious threat to the health and survival of humans and other organisms given the increasing use of daily-use plastic products, especially during the COVID-19 pandemic. However, whether direct microplastic contamination from plastic packaging is a threat to human health remains unclear. We analyzed the market demand for plastic packaging in Asia-Pacific, North America, and Europe and identified the commonly used plastic food packaging products. We found that food containers exposed to high-temperature released more than 10 million microplastics per mL in water. Recycled plastic food packaging was demonstrated to continuously leach micro- and nanoplastics. In vitro cell engulfing experiments revealed that both micro- and nanoplastic leachates are readily taken up by murine macrophages without any preconditioning, and that short-term microplastic exposure may induce inflammation while exposure to nanoplastic substantially suppressed the lysosomal activities of macrophages. We demonstrated that the ingestion of micro- and nanoplastics released from food containers can exert differential negative effects on macrophage activities, proving that the explosive growth in the use of plastic packaging can poses significant health risks to consumers.
Subject(s)
COVID-19 , Water Pollutants, Chemical , Animals , Food Packaging , Humans , Lysosomes , Macrophages , Mice , Microplastics/toxicity , Pandemics , Plastics/analysis , Plastics/toxicity , Water Pollutants, Chemical/analysisABSTRACT
As one of major types of microplastics (MPs), microfibers (MFs) are widely found in the marine ecosystem and can induce diverse impacts on various marine organisms. Sedentary species, such as mussels, can act as bioindicators for monitoring marine contamination. Hence, in this study, we used mussels (Mytilus galloprovincialis) to examine the toxicity of polyethylene terephthalate (PET) MFs of 100 µm size at concentrations of 0.0005, 0.1, 1, 10, and 100 mg/L for 32 days. PET MFs accumulated only in the stomachs and intestines of the mussels and caused digestive tubule atrophy. After exposure to PET MFs, no alteration in the mortality rate, shell height, length, and weight of the mussels was observed. However, the gonadal index decreased with increasing concentrations of PET MFs. This is because PET MFs decrease the sex hormones estradiol and testosterone in mussels, even at environmentally relevant concentrations. Furthermore, chronic exposure to PET MFs increased the activities of antioxidant-related (catalase and superoxide dismutase) and neurotoxicity-related (acetylcholine esterase) enzymes in the digestive gland and gill tissues of mussels. In addition, cellular immune parameters of apoptosis and DNA damage were observed in mussel hemocytes. Thus, this study demonstrates the risks of MPs in real marine environments by assessing how long-term exposure to low concentrations of PET MFs can cause potential sublethal impacts and reproductive failure in mussels.
Subject(s)
Mytilus , Water Pollutants, Chemical , Animals , Ecosystem , Microplastics , Plastics/toxicity , Polyethylene Terephthalates , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicityABSTRACT
This study investigates the adverse effects and the associated underlying mechanism of bisphenol S (BPS) exposure on reproductive endocrine activity in adult zebrafish. Fish were exposed for 21 days to different BPS concentrations (0, 8, 40, and 200 µg/mL) determined via the lowest observed adverse effect level (LOAEL, i.e., < EC15 = 250 µg/mL) for zebrafish embryos. Exposure to 200 µg/mL BPS in female zebrafish in the absence of vitellogenic oocytes or the presence of degenerated oocytes in the ovary significantly decreased the biosynthesis of hepatic vitellogenin (VTG) mRNA, while hepatic VTG mRNA in male fish abundance was significantly elevated (P < 0.05). The levels of gonadal steroids were significantly increased in female zebrafish, while in male zebrafish, the levels of endogenous androgens were reduced (P < 0.05). However, the activities of 17ß-estradiol and aromatase in male zebrafish were significantly elevated in all BPS exposure groups in male zebrafish (P < 0.05). Interestingly, thyroid hormone levels and residual whole-body BPS levels increased in female and male zebrafish with increasing exposure concentrations. A novel finding is that the response to BPS depends on zebrafish sex and tissue-specific responsiveness to the accumulation of BPS, suggesting that BPS may cause long-term environmental problems in adult zebrafish through tissue-specific suppression and hormonal imbalance.
Subject(s)
Water Pollutants, Chemical , Zebrafish , Animals , Female , Male , Phenols/toxicity , Sulfones , Vitellogenins/genetics , Water Pollutants, Chemical/toxicityABSTRACT
Mycobacterium abscessus is a difficult respiratory pathogen to treat, when compared to other nontuberculus mycobacteria (NTM), due to its drug resistance. In this study, we aimed to find a new clarithromycin partner that potentiated strong, positive, synergy against M. abscessus among current anti-M. abscessus drugs, including omadacycline, amikacin, rifabutin, bedaquiline, and cefoxitine. First, we determined the minimum inhibitory concentrations required of all the drugs tested for M. abscessus subsp. abscessus CIP104536T treatment using a resazurin microplate assay. Next, the best synergistic partner for clarithromycin against M. abscessus was determined using an in vitro checkerboard combination assay. Among the drug combinations evaluated, omadacycline showed the best synergistic effect with clarithromycin, with a fractional inhibitory concentration index of 0.4. This positive effect was also observed against M. abscessus clinical isolates and anti-M. abscessus drug resistant strains. Lastly, this combination was further validated using a M. abscessus infected zebrafish model. In this model, the clarithromycin-omadacyline regimen was found to inhibit the dissemination of M. abscessus, and it significantly extended the lifespan of the M. abscessus infected zebrafish. In summation, the synergy between two anti-M. abscessus compounds, clarithromycin and omadacycline, provides an attractive foundation for a new M. abscessus treatment regimen.
ABSTRACT
Mycobacterium abscessus is the one of the most feared bacterial respiratory pathogens in the world. Unfortunately, there are many problems with the current M. abscessus therapies available. These problems include misdiagnoses, high drug resistance, poor long-term treatment outcomes, and high costs. Until now, there have only been a few new compounds or drug formulations which are active against M. abscessus, and these are present in preclinical and clinical development only. With that in mind, new and more powerful anti-M. abscessus medicines need to be discovered and developed. In this study, we conducted an in vitro-dual screen against M. abscessus rough (R) and smooth (S) variants using a Pandemic Response Box and identified epetraborole as a new effective candidate for M. abscessus therapy. For further validation, epetraborole showed significant activity against the growth of the M. abscessus wild-type strain, three subspecies, drug-resistant strains and clinical isolates in vitro, while also inhibiting the growth of M. abscessus that reside in macrophages without cytotoxicity. Furthermore, the in vivo efficacy of epetraborole in the zebrafish infection model was greater than that of tigecycline. Thus, we concluded that epetraborole is a potential anti-M. abscessus candidate in the M. abscessus drug search.
Subject(s)
Anti-Bacterial Agents/pharmacology , Boron Compounds/pharmacology , Mycobacterium Infections, Nontuberculous/drug therapy , Mycobacterium abscessus/drug effects , Animals , Drug Evaluation, Preclinical , Drug Repositioning , ZebrafishABSTRACT
The necessity for the aquatic ecological risk assessment for benzophenone-3 (BP-3) is increasing due to its high toxic potential and high detection frequency in freshwater. The initial step in the ecological risk assessment is to determine predicted no-effect concentration (PNEC). This study derived PNEC of BP-3 in freshwater using a species sensitivity distribution (SSD) approach, whilst existing PNECs are derived using assessment factor (AF) approaches. A total of eight chronic toxicity values, obtained by toxicity testing and a literature survey, covering four taxonomic classes (fish, crustaceans, algae, and cyanobacteria) were used for PNEC derivation. Therefore, the quantity and quality of the toxicity data met the minimum requirements for PNEC derivation using an SSD approach. The PNEC derived in this study (73.3 µg/L) was far higher than the environmental concentration detected in freshwater (up to 10.4 µg/L) as well as existing PNECs (0.67~1.8 µg/L), mainly due to the difference in the PNEC derivation methodology (i.e., AF vs. SSD approach). Since the SSD approach is regarded as more reliable than the AF approach, we recommend applying the PNEC value derived in this study for the aquatic ecological risk assessment of BP-3, as the use of the existing PNEC values seems to unnecessarily overestimate the potential ecological risk of BP-3 in freshwater.
Subject(s)
Water Pollutants, Chemical , Animals , Aquatic Organisms , Benzophenones/toxicity , Fishes , Fresh Water , Risk Assessment , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicityABSTRACT
Many studies have investigated the toxic effects of microplastics in marine organisms, but most studied nano-sized round microplastics at high concentrations and were not environmentally relevant. To understand the cellular toxicity of polyethylene terephthalate microfibers (PET-MFs) by length (50 and 100 µm), Mediterranean mussels (Mytilus galloprovincialis) were exposed to environmental (0.5 µg/L) and high (100 mg/L) MF concentrations for four days. Short PET-MFs accumulated in the lower intestinal organs of the mussels, but long PET-MFs were only observed in the upper intestinal organs. Both sized PET-MFs affected necrosis, DNA damage, reactive oxygen species, nitric oxide, and acetylcholinesterase (AChE) activity. Significant MF length-dependent effects occurred at environmentally relevant concentrations for DNA damage (100 µm MFs) and AChE activity (50 µm MFs). However, length effects disappeared at the higher exposure concentration. The current study provides potentially sensitive indicators to detect MFs exposure and the ecotoxicological implications of MFs in marine ecosystems.