Occurrence of glucocorticoids discharged from a sewage treatment plant in Japan and the effects of clobetasol propionate exposure on the immune responses of common carp (Cyprinus carpio) to bacterial infection

Exposure effects of synthetic glucocorticoid drugs on skeletal developmental and immune cell function in zebrafish

Synthetic glucocorticoids (GCs) are used to treat a wide range of human health conditions and as such are frequently detected in the aquatic environment. This, together with the highly conserved nature of the glucocorticoid system across vertebrates means that the potential for biological effects of GCs in fish is relatively high. Here, we found that exposure of zebrafish (Danio rerio) to environmentally relevant concentrations of 4 of the most widely used synthetic GCs (beclomethasone dipropionate, budesonide, fluticasone propionate, and prednisolone), from 0 to 4 days post fertilisation (dpf), resulted in no effects on embryo-larval development or bone and cartilage formation. However, after exposure to equivalents of human therapeutic plasma levels, developmental abnormalities were observed that included pericardial oedema, blood pooling and alterations in jaw cartilage. Furthermore, using a double transgenic zebrafish osteoblast and chondrocyte reporter line, exposure up to 10 dpf resulted in alterations to lower jaw cartilage and bone development for all compounds at, and above, human therapeutic plasma concentrations. In the case of beclomethasone dipropionate, a reduction in lower jaw intercranial distance was observed at the environmentally relevant concentration of 0.1 μg/L. Using further transgenic reporter lines with fluorescently tagged neutrophils and macrophages, we also show exposure of embryo-larvae (0-4 dpf) to the GCs tested resulted in altered immune cell migration, but only at relatively high exposure concentrations. Collectively, our findings show GC exposure impacts embryo-larval zebrafish development, immune function, and skeletal formation, but predominantly at concentrations greater than those currently reported for the aquatic environment. Despite this, however, it is suggested that studies with longer exposure times, and to mixtures of multiple GCs (many GCs act via the same mechanism of action) are warranted before we can confidently assert that these commonly detected contaminants do not pose a risk to fish in the wild.

Assessment of environmental exposure to betamethasone on the reproductive function of female Japanese medaka (Oryzias latipes)

Betamethasone has been extensively used in medicine in recent years and poses potential hazards to aquatic organisms. This study investigated the reproductive toxic effects of betamethasone exposure in fish, employing female Japanese medaka (Oryzias latipes) as a model. Betamethasone exposure at environmentally relevant concentrations (0, 20, 200, and 2000 ng/L) for a period of 15 weeks resulted in its high accumulation in the ovary, leading to abnormal oogenesis in female Japanese medaka. The production of gonadotropins (LH and FSH) in the pituitary gland was inhibited, and sex steroid biosynthesis in the ovary was significantly influenced at the transcriptional level. The imbalance of androgens and estrogens resulted in a decrease in the E2/T ratio and hepatic VTG synthesis, and the suppression of estrogen receptor signaling was also induced. Furthermore, betamethasone exposure delayed spawning and reduced fertility in the F0 generation, and had detrimental effects on the fertilization rate and hatchability of the F1 generation. Our results showed that environmental betamethasone had the potential to adversely affect female fertility and steroid hormone dynamics in fish.

Using cell culture systems from the Persian Gulf Arabian yellowfin sea bream, Acanthopagrus arabicus, to assess the effects of dexamethasone on gonad and brain aromatase activity and steroid production

Dexamethasone (DEX) is a synthetic glucocorticoid widely used as pharmaceutical and usually exists in effluents with varying degrees of concentrations. In this study, cultivated Brain, ovary and testis cells from Arabian Sea bream, Acanthopagrus arabicus, were treated by DEX at concentrations of 0, 0.3, 3.0, 30.0 and 300.0 μg/ml for 48 h. The aromatase activity and steroid (17-β-estradiol (E2), progesterone (P) and testosterone (T)) production by cells were measured at 12, 24 and 48 h of the experiment. The results showed that the sensitivity of cultivated ovarian, testicular and brain cells to DEX increased dose dependently. DEX was potent inhibitor of aromatase activity at specially 30.0 and 300.0 μg/ml in the cultivated ovarian and testicular cells at different sampling time. On the other hand, DEX was found to stimulate the aromatase activity of fish brain. DEX also decreased E2, P and T production by cultivated ovarian and testicular cells during the experiment. While, DEX caused an increase in the production of E2 and P by brain cells, which seems logical considering the stimulating effect of this drug on brain aromatase activity. In conclusion, results highlight that DEX is able to change the activity of aromatase, and disrupt the biosynthesis of estrogens and thus affect reproduction in fish.

Reproductive endocrine disruption and gonadal intersex induction in male Japanese medaka chronically exposed to betamethasone at environmentally relevant levels

The broad utilization of betamethasone in medical treatments may pose a significant ecotoxicological risk to aquatic organisms, yet its potential reproductive toxicity remains unclear. The present study examined the impacts of environmental exposure on male reproduction using Japanese medaka (Oryzias latipes). After 110 days of betamethasone exposure at environmentally relevant concentrations (0, 20 and 200 ng/L), LH/FSH synthesis and release in the pituitary was inhibited, and the production of sex hormones and their signaling pathways in the gonads of male medaka were greatly influenced. This synthetic glucocorticoid restrained testosterone (T) synthesis and gave rise to a significant increase in E₂/T and E₂/11-KT ratios. Furthermore, chronic betamethasone exposure (20 and 200 ng/L) led to the suppression of androgen receptor (AR) signaling and enhancement of estrogen receptors (ERs) signaling. An increase in hepatic vitellogenin contents was also detected, and testicular oocytes were observed in both 20 and 200 ng/L betamethasone-treated groups. It showed that 20 and 200 ng/L betamethasone could induce male feminization and even intersex, triggering abnormal spermatogenesis in medaka males. With its adverse effects on male fertility, betamethasone could potentially influence the fishery productivity and population dynamics in aquatic ecosystems.

Are synthetic glucocorticoids in the aquatic environment a risk to fish?

The glucocorticosteroid, or glucocorticoid (GC), system is largely conserved across vertebrates and plays a central role in numerous vital physiological processes including bone development, immunomodulation, and modification of glucose metabolism and the induction of stress-related behaviours. As a result of their wide-ranging actions, synthetic GCs are widely prescribed for numerous human and veterinary therapeutic purposes and consequently have been detected extensively within the aquatic environment. Synthetic GCs designed for humans are pharmacologically active in non-mammalian vertebrates, including fish, however they are generally detected in surface waters at low (ng/L) concentrations. In this review, we assess the potential environmental risk of synthetic GCs to fish by comparing available experimental data and effect levels in fish with those in mammals. We found the majority of compounds were predicted to have insignificant risk to fish, however some compounds were predicted to be of moderate and high risk to fish, although the dataset of compounds used for this analysis was small. Given the common mode of action and high level of inter-species target conservation exhibited amongst the GCs, we also give due consideration to the potential for mixture effects, which may be particularly significant when considering the potential for environmental impact from this class of pharmaceuticals. Finally, we also provide recommendations for further research to more fully understand the potential environmental impact of this relatively understudied group of commonly prescribed human and veterinary drugs.

Oxidation of Aqueous Dexamethasone Solution by Gas-Phase Pulsed Corona Discharge

The most widely used anti-inflammatory corticosteroid dexamethasone (DXM), frequently detected in waterbodies due to its massive consumption and incomplete removal in wastewater treatment processes, was experimentally studied for oxidation with gas-phase pulsed corona discharge (PCD) varied in pulse repetition frequency, pH, DXM initial concentration and additions of surfactant sodium dodecyl sulphate (SDS) and tert-butyl alcohol (TBA). The experimental study also included ozonation as compared to PCD in energy efficiency. The advantageous energy efficiency of PCD was observed in wide spans of pH and DXM initial concentrations surpassing ozonation by about 2.4 times. Identified transformation by- and end-products (fluoride and acetate), as well as the impact of radical scavengers, point to the prevalent radical oxidation of DXM. Somewhat increased toxicity observed on the course of PCD-treatment of high DXM concentrations presents a subject for further studies.

Effects of dexamethasone on the morphology, gene expression and hepatic histology in adult female mosquitofish (Gambusia affinis)

Glucocorticoids (GCs), including natural hormones as well as synthetic chemicals, can pose influences on physiological performance, development and reproduction of fish. Dexamethasone (DEX) is a synthetic glucocorticoid widely used as pharmaceutical and usually exists in effluents with varying degrees of concentrations. In this study, adult female mosquitofish (Gambusia affinis) were treated by DEX at concentrations of 0, 0.5, 5 and 50 μg/L for 60 days. Morphological parameters of anal fin and skeleton, mRNA expression abundance, and histological alterations of liver were investigated to assess effects of DEX on mosquitofish. The results showed that DEX increased number of sections of ray 3 in anal fin and decreased 16L, 15D and 16D in skeletal parameters, which indicates DEX could potentially lead to weak masculinization. Furthermore, transcriptional expression levels of ARα, ARβ, ERβ, VTGC and CYP19A genes were notably down-regulated by DEX, which will contribute to weak masculinization in females. In addition, the damage to liver tissue was also induced by DEX. Taken together, this research demonstrated that aquatic environments contaminated by DEX have negative effects on mosquitofish at a population level.

Effects of the glucocorticoid clobetasol propionate and its mixture with cortisol and different class steroids in adult female zebrafish

Ecotoxicological effects of glucocorticoids and steroid mixtures in the environment are not sufficiently known. Here we investigate effects of 11-14 days exposure of female zebrafish to the glucocorticoid clobetasol propionate (Clo), cortisol (Cs), their mixture and mixtures with five different class steroids (Clo + triamcinolone + estradiol + androstenedione + progesterone) in liver, brain and gonads. Cs showed little activity, while Clo reduced the condition factor at 0.57 and 6.35 μg/L. Clo induced differential expression of genes in the liver at 0.07-6.35 μg/L, which were related to circadian rhythm (per1, nr1d2), glucose metabolism (g6pca, pepck1), immune system response (fkbp 5, socs3, gilz), nuclear steroid receptors (pgr and pxr), steroidogeneses and steroid metabolism (hsd11b2, cyp2k22). Clo caused strong transcriptional down-regulation of vtg. Similar upregulations occurred in the brain for pepck1, fkbp5, socs3, gilz, hsd11b2, and nr1d2a, while cyp19b was down-regulated. Effects of Clo + Cs mixtures were similar to Clo alone. Transcriptional alterations were different in mixtures of five steroids with no alteration of vtg in the liver due to counteraction of Clo and estradiol. Induction of fkbp5 (brain) and sult2st3 (liver) and downregulation of cyp19a (gonads) occurred at 1 μg/L. Histological effects of the five steroids mixture in gonads were characterized by a decrease of mature oocytes. Our data indicate that effects of steroids of different classes sum up to an overall joint effect driven by the most potent steroid Clo.

Glucocorticoid mixtures of fluticasone propionate, triamcinolone acetonide and clobetasol propionate induce additive effects in zebrafish embryos

Many synthetic glucocorticoids from medical applications occur in the aquatic environment. Whether they pose a risk for fish health is poorly known. Here we investigate effects of glucocorticoids fluticasone propionate (FLU) and triamcinolone acetonide (TRI) as single steroids and as ternary mixtures with clobetasol propionate (CLO) in zebrafish embryos. Exposure to FLU and TRI in a range of concentrations between 0.099 and 120.08 μg/L led to concentration-related decrease in muscle contractions and increase in heart rate at 0.98 and 1.05 μg/L, respectively, and higher. Genes encoding for proteins related to glucose metabolism (g6pca, pepck1), immune system regulation (fkbp5, irg1l, socs3, gilz) and matrix metalloproteinases mmp-9 and mmp-13 showed expressional alterations, as well as genes encoding for the progestin receptor (pgr) and corticosteroid dehydrogenase (hsd11b2). FLU accelerated hatching and led to embryotoxicity (immobilization and edema). Ternary mixtures (FLU + TRI + CLO) induced the same physiological and toxicological effects at concentrations of individual glucocorticoids of 11.1-16.37 μg/L and higher. Heart rate was increased in the mixture at concentrations as low as 0.0885-0.11 μg/L of each steroid. Glucocorticoids in mixtures showed additive activity; the fold-changes of transcripts of 19 target genes were additive. Together, our data show that glucocorticoids act additively and their joint activity may be of concern for developing fish in contaminated environments.

Environmental glucocorticoids corticosterone, betamethasone and flumethasone induce more potent physiological than transcriptional effects in zebrafish embryos

Many glucocorticoids occur in the aquatic environments but their adverse effects to fish are poorly known. Here we investigate effects of the natural glucocorticoid corticosterone and the synthetic glucocorticoids betamethasone and flumethasone in zebrafish embryos. Besides studying the effects of each steroid, we compared effects of natural with synthetic glucocorticoids, used as drugs. Exposure at concentrations of 1 μg/L and higher led to concentration-related decrease in spontaneous muscle contractions at 24 h post fertilization (hpf) and increase in heart rate at 48 hpf. Betamethasone showed a significant increase at 0.11 μg/L in heart rate. Corticosterone also accelerated hatching at 60 hpf at 0.085 μg/L. Transcription of up to 24 genes associated with different pathways showed alterations at 96 and 120 hpf for all glucocorticoids, although with low potency. Corticosterone caused transcriptional induction of interleukin-17, while betamethasone caused transcriptional down-regulation of the androgen receptor, aromatase and hsd11b2, indicating an effect on the sex hormone system. Furthermore, transcripts encoding proteins related to immune system regulation (irg1l, gilz) and fkbp5 were differentially expressed by corticosterone and betamethasone, while flumethasone caused only little effects, mainly alteration of the irg1l transcript. Our study shows that these glucocorticoids caused more potent physiological effects in early embryos than transcriptional alterations in hatched embryos, likely due to increased metabolism in later developmental stages. Thus, these glucocorticoids may be of concern for early stages of fish embryos in contaminated aquatic environments.

Occurrence of Glucocorticoids, Mineralocorticoids, and Progestogens in Various Treated Wastewater, Rivers, and Streams

In the current study a high sensitive analytical method was developed for the determination of 60 steroids including glucocorticoids (GC), mineralocorticoids (MC), and progestogens (PG) in WWTP effluents and surface water using liquid chromatography with tandem mass spectrometry detection (LC-MS/MS). The limits of quantification (LOQ) ranged between 0.02 ng/L (cortisone) to 0.5 ng/L (drospirenone) in surface water and from 0.05 ng/L (betamethasone) to 5 ng/L (chlormadinone) in treated wastewater. After optimization, the developed method was applied to WWTP effluents, rivers, and streams around Germany. Numerous steroids have been detected during the sampling campaign and predominant analytes from all steroid types were determined. Moreover, the occurrence of dienogest, mometasone furoate, flumethasone pivalate, and the metabolites 6β-hydroxy dienogest, 6β-hydroxy triamcinolone acetonide, 7α-thiomethyl spironolactone, and 11α-hydroxy canrenone is reported for the first time. In addition, this study revealed the ubiquitous presence of topically applied GC monoesters betamethasone propionate, betamethasone valerate, and 6α-methylprednisolone propionate in WWTP effluents and surface water.

Use of common carp (Cyprinus carpio) and Aeromonas salmonicida for detection of immunomodulatory effects of chemicals on fish

To develop a test for assessing the immunomodulatory effects of chemical pollutants on fish, we evaluated the effects of dexamethasone on the natural host-pathogen interaction between common carp (Cyprinus carpio) and Aeromonas salmonicida. Carp were exposed to 1mgL^-1 dexamethasone for the entire experimental period. One week after the exposure test started, the exposed fish, as well as unexposed fish, were bath-infected with A. salmonicida. One hundred percent mortality was observed in bacteria-infected fish exposed to dexamethasone, whereas no infection-associated mortality was observed in infected fish in the absence of dexamethasone exposure. In a separate experiment, dexamethasone exposure significantly suppressed hemolytic complement activity in bacteria-infected fish. These results clearly indicate that exposure to a high concentration of dexamethasone suppressed the carp immune system and caused subsequent mortality. Thus, this proposed test method is likely to be useful for evaluating the immunomodulatory effects of chemicals in fish.

Tributyltin exposure increases mortality of nodavirus infected Japanese medaka Oryzias latipes larvae

We investigated the effect of combined exposure to nodavirus infection and TBT on medaka (Oryzias latipes). Medaka larvae were infected by immersion in medium containing nodavirus at titers of 10^2.5, 10^3.5, or 10^4.5 TCID₅₀/mL. Infected fish then were exposed to TBT at 0, 0.17, 0.52, 1.6, or 4.7μg/L. Of the 12 groups exposed to both stressors, the mortalities of 6 (10^2.5 TCID₅₀/mL+0.52, 1.6, or 4.7μg/L, 10^3.5 TCID₅₀/mL+4.7μg/L and 10^4.5 TCID₅₀/mL+1.6 or 4.7μg/L) were significantly higher than that of each TBT control. Specifically, mortality was 46±5.5% in the group exposed to both 10^2.5 TCID₅₀/mL virus and 0.52μg/L TBT, which represent the lowest observed effective dose and concentration, respectively, among the 6 groups with increased mortalities. Our results suggest that combined exposure to both stressors suppresses antiviral mechanisms in the fish, thus increasing mortality.

Kinetics of glucocorticoid exposure in developing zebrafish: A tracer study

In the current study the dynamics of glucocorticoid uptake by zebrafish chorionated embryos from the surrounding medium were studied, using 2.5 μM cortisol or dexamethasone solutions complemented with their tritiated variant. We measured the uptake of radioactive cortisol by embryos during a 1 h submersion. Interestingly, the signal in chorionated embryos was 85% (exposure: 1-2 hpf) or 78% (exposure: 48-49 hpf) of the signal present in an equal volume medium. By comparing embryos measured without chorion, we found that 18-20% of the radioactivity present in chorionated embryos is actually bound to the chorion or located in the perivitelline space. Consequently, embryonic tissue contains radioactivity levels of 60% of a similar volume of medium after 1 h incubation. During early developmental stages (1-48 hpf) exposure of more than 24 h in cortisol was needed to achieve radioactivity levels similar to an equal volume of medium within the embryonic tissue and more than 48 h for dexamethasone. In glucocorticoid-free medium, radioactivity dropped rapidly below 10% for both glucocorticoids, suggesting that the major portion of the embryonic radioactivity was a result of simple diffusion. During later developmental stages (48-96 hpf) initial uptake dynamics were similar, but showed a decrease of tissue radioactivity to 20% of an equal volume of medium after hatching, probably due to development and activation of the hypothalamic pituitary interrenal axis. Uptake is dependent on the developmental stage of the embryo. Furthermore, the presence of the chorion during exposure should be taken into account even when small lipophilic molecules are being tested.

Clobetasol propionate causes immunosuppression in zebrafish (Danio rerio) at environmentally relevant concentrations

Synthetic glucocorticoids (GCs) are potential endocrine disrupting compounds that have been detected in the aquatic environment around the world in the low ng/L (nanomolar) range. GCs are used as immunosuppressants in medicine. It is of high interest whether clobetasol propionate (CP), a highly potent GC, suppresses the inflammatory response in fish after exposure to environmentally relevant concentrations. Bacterial lipopolysaccharide (LPS) challenge was used to induce inflammation and thus mimic pathogen infection. Zebrafish embryos were exposed to ≤1000nM CP from ~1h post fertilization (hpf) to 96 hpf, and CP uptake, survival after LPS challenge, and expression of inflammation-related genes were examined. Our initial experiments were carried out using 0.001% DMSO as a solvent vehicle, but we observed that DMSO interfered with the LPS challenge assay, and thus masked the effects of CP. Therefore, DMSO was not used in the subsequent experiments. The internal CP concentration was quantifiable after exposure to ≥10nM CP for 96h. The bioconcentration factor (BCF) of CP was determined to be between 16 and 33 in zebrafish embryos. CP-exposed embryos showed a significantly higher survival rate in the LPS challenge assay after exposure to ≥0.1nM in a dose dependent manner. This effect is an indication of immunosuppression. Furthermore, the regulation pattern of several genes related to LPS challenge in mammals supported our results, providing evidence that LPS-mediated inflammatory pathways are conserved from mammals to teleost fish. Anxa1b, a GC-action related anti-inflammatory gene, was significantly down-regulated after exposure to ≥0.05nM CP. Our results show for the first time that synthetic GCs can suppress the innate immune system of fish at environmentally relevant concentrations. This may reduce the chances of fish to survive in the environment, as their defense against pathogens is weakened.

Balancing the Budget: Accounting for Glucocorticoid Bioactivity and Fate during Water Treatment

Numerous studies have identified the presence and bioactivity of glucocorticoid receptor (GR) active substances in water; however, the identification and activity-balance of GR compounds remained elusive. This study determined the occurrence and attenuation of GR bioactivity and closed the balance by determining those substances responsible. The observed in vitro GR activity ranged from 39 to 155 ng dexamethasone-equivalent/L (ng Dex-EQ/L) in the secondary effluents of four wastewater treatment plants. Monochromatic ultraviolet light of 80 mJ/cm(2) disinfection dose was efficient for GR activity photolysis, whereas chlorination could not appreciably attenuate the observed GR activity. Ozonation was effective only at relatively high dose (ozone/TOC 1:1). Microfiltration membranes were not efficient for GR activity attenuation; however, reverse osmosis removed GR activity to levels below the limits of detection. A high-sensitivity liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was then developed to screen 27 GR agonists. Twelve were identified and quantified in effluents at summed concentrations of 9.6-21.2 ng/L. The summed Dex-EQ of individual compounds based on their measured concentrations was in excellent agreement with the Dex-EQ obtained from bioassay, which demonstrated that the detected glucocorticoids can entirely explain the observed GR bioactivity. Four synthetic glucocorticoids (triamcinolone acetonide, fluocinolone acetonide, clobetasol propionate, and fluticasone propionate) predominantly accounted for GR activity. These data represent the first known publication where a complete activity balance has been determined for GR agonists in an aquatic environment.