Detection of benzo[a]pyrene-induced immunotoxicity in orange spotted grouper (Epinephelus coioides)

The detoxification ability of sex-role reversed seahorses determines the sexual dimorphism in immune responses to benzo[a]pyrene exposure

Sexual dimorphism in immune responses is an essential factor in environmental adaptation. However, the mechanisms involved remain obscure owing to the scarcity of data from sex-role-reversed species in stressed conditions. Benzo[a]pyrene (BaP) is one of the most pervasive and carcinogenic organic pollutants in coastal environments. In this study, we evaluated the potential effects on renal immunotoxicity of the sex-role-reversed lined seahorse (Hippocampus erectus) toward environmental concentrations BaP exposure. Our results discovered the presence of different energy-immunity trade-off strategies adopted by female and male seahorses during BaP exposure. BaP induced more severe renal damage in female seahorses in a concentration-dependent manner. BaP biotransformation and detoxification in seahorses resemble those in mammals. Benzo[a]pyrene-7,8-dihydrodiol-9,10-oxide (BPDE) and 9-hydroxybenzo[a]pyrene (9-OH-BaP) formed DNA adducts and disrupted Ca2+ homeostasis may together attribute the renal immunotoxicity. Sexual dimorphisms in detoxification of both BPDE and 9-OH-BaP, and in regulation of Ca2+, autophagy and inflammation, mainly determined the extent of renal damage. Moreover, the mechanism of sex hormones regulated sexual dimorphism in immune responses needs to be further elucidated. Collectively, these findings contribute to the understanding of sexual dimorphism in the immunotoxicity induced by BaP exposure in seahorses, which may attribute to the dramatic decline in the biodiversity of the genus.

Common contributing factors to COVID-19 and inflammatory bowel disease

The devastating complications of coronavirus disease 2019 (COVID-19) result from an individual's dysfunctional immune response following the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Multiple toxic stressors and behaviors contribute to underlying immune system dysfunction. SARS-CoV-2 exploits the dysfunctional immune system to trigger a chain of events ultimately leading to COVID-19. We have previously identified many contributing factors (CFs) (representing toxic exposure, lifestyle factors and psychosocial stressors) common to myriad chronic diseases. We hypothesized significant overlap between CFs associated with COVID-19 and inflammatory bowel disease (IBD), because of the strong role immune dysfunction plays in each disease. A streamlined dot-product approach was used to identify potential CFs to COVID-19 and IBD. Of the fifty CFs to COVID-19 that were validated for demonstration purposes, approximately half had direct impact on COVID-19 (the CF and COVID-19 were mentioned in the same record; i.e., CF---→COVID-19), and the other half had indirect impact. The nascent character of the COVID-19 core literature (∼ one year old) did not allow sufficient time for the direct impacts of many CFs on COVID-19 to be identified. Therefore, an immune system dysfunction (ID) literature directly related to the COVID-19 core literature was used to augment the COVID-19 core literature and provide the remaining CFs that impacted COVID-19 indirectly (i.e., CF---→immune system dysfunction---→COVID-19). Approximately 13000 potential CFs for myriad diseases (obtained from government and university toxic substance lists) served as the starting point for the dot-product identification process. These phrases were intersected (dot-product) with phrases extracted from a PubMed-derived IBD core literature, a nascent COVID-19 core literature, and the COVID-19-related immune system dysfunction (ID) core literature to identify common ID/COVID-19 and IBD CFs. Approximately 3000 potential CFs common to both ID and IBD, almost 2300 potential CFs common to ID and COVID-19, and over 1900 potential CFs common to IBD and COVID-19 were identified. As proof of concept, we validated fifty of these ∼3000 overlapping ID/IBD candidate CFs with biologic plausibility. We further validated 24 of the fifty as common CFs in the IBD and nascent COVID-19 core literatures. This significant finding demonstrated that the CFs indirectly related to COVID-19 -- identified with use of the immune system dysfunction literature -- are strong candidates to emerge eventually as CFs directly related to COVID-19. As discussed in the main text, many more CFs common to all these core literatures could be identified and validated. ID and IBD share many common risk/contributing factors, including behaviors and toxic exposures that impair immune function. A key component to immune system health is removal of those factors that contribute to immune system dysfunction in the first place. This requires a paradigm shift from traditional Western medicine, which often focuses on treatment, rather than prevention.

Shoaling, boldness, anxiety-like behavior and locomotion in zebrafish (Danio rerio) are altered by acute benzo[a]pyrene exposure

Environmental exposure to crude oil and/or its derivatives in fishes can negatively impact survival, morphology and physiology, but relatively little focus has been on behavior. Exposures can influence prey-predator interactions, courtship and other vital behaviors, leading to individual or population disruption at toxicant levels well below those producing morphological or physiological changes. The few behavioral studies of polycyclic aromatic hydrocarbons (PAHs) on fish behavior have yielded highly inconsistent results, likely relating to chronic vs. acute treatment. A few studies report lethargy and decreased exploratory behavior, while others indicate increased anxiety and greater exploratory behavior with PAH exposure. In our study on zebrafish (Danio rerio), we hypothesized that even relatively brief (30 min) exposure to the PAH benzo[a]pyrene (B[a]P) would impact group shoaling and individual behaviors in open field and novel object exploration tests. Exposures comprised measured concentrations of 1.0 μM, 10 μM, or 100 μM, B[a]P. Compared to controls, inter-individual distance (IID) was significantly increased by 100 μM B[a]P, but not by 1.0 μM or 10 μM B[a]P. Total distance moved by shoals was decreased significantly at B[a]P concentrations of 1.0 μM, 10 μM and 100 μM. In the open field test of individual locomotion and anxiety-like behavior, time spent in the thigmotaxis zone along the walls of the circular test arena (a proxy for anxiety-like behavior), was decreased at 100 μM. In the novel object approach test to investigate boldness, time spent near the object was significantly increased by both 10 μM and 100 μM B[a]P. Collectively, these data indicate a complex suite of changes in zebrafish including altered shoal dynamics, decreased anxiety, increased boldness, and decreased locomotion associated with exposure to B[a]P.

A review of human and animals exposure to polycyclic aromatic hydrocarbons: Health risk and adverse effects, photo-induced toxicity and regulating effect of microplastics

Polycyclic aromatic hydrocarbons (PAHs) are one of the most widely distributed persistent organic pollutants (POPs) in the environmental media. PAHs have been widely concerned due to their significant health risk and adverse effects to human and animals. Currently, the main sources of PAHs in the environment are the incomplete combustion of fossil fuels, as well as municipal waste incineration and agricultural non-surface source emissions. In this work, the scope of our attention includes 16 typical PAHs themselves without involving their metabolites and industrial by-products. Exposure of human and animals to PAHs can lead to a variety of adverse effects, including carcinogenicity and teratogenicity, genotoxicity, reproductive- and endocrine-disrupting effects, immunotoxicity and neurotoxicity, the type and severity of which depend on a variety of factors. On the other hand, the regulatory effect of microplastics (MPs) on the bio-toxicity and bioaccumulation capacity of PAHs has now gradually attracted attention. We critically reviewed the adsorption capacity and mechanisms of MPs on PAHs as well as the effects of MPs on PAHs toxicity, thus highlighting the importance of paying attention to the joint bio-toxicity caused by PAHs-MPs interactions. In addition, due to the extensive nature of the common exposure pathway of PAHs and ultraviolet ray, an accurate understanding of biological processes exposed to both PAHs and UV light is necessary to develop effective protective strategies. Finally, based on the above critical review, we highlighted the research gaps and pointed out the priority of further studies.

Oxidative stress in liver cell culture from mullet, Liza klunzingeri, induced by short-term exposure to benzo[a]pyrene and nonylphenol

The present investigation aimed to use primary liver cell culture obtained from mullet, Liza klunzingeri, to evaluate the toxic effects of benzo[a]pyrene (BaP) and nonylphenol (NP) on the antioxidant defense system. Liver samples taken from 20 L. klunzingeri were digested with 0.1% collagenase IV. The digested cells were then moved to Leibovitz L-15 culture medium and incubated at 25 °C for 2 weeks. 10^-5 mol/l of BaP and 10^-4 mol/l of NP were considered as the half maximal inhibitory concentration (IC50). Cells were then incubated with L-15 medium containing BaP (0[control], 10^-6,2 × 10^-6,3 × 10^-6 mol/l) and NP (0[control],10^-5,2 × 10^-5,3 × 10^-5 mol/l), and sampling was performed after 6, 12, and 24 h of incubation for measurement of catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), lipid peroxidation (LPO), total antioxidant power, and total protein. The lowest concentration of BaP and NP did not have considerable toxic effects on cultivated hepatocytes. The activities of SOD, CAT, GPx, LPO, total antioxidant power, and total protein changed dose-dependently in cells treated with BaP and NP. In conclusion, based on the results, short-term exposure to BaP and NP induced the oxidative stress in cultivated liver cells of L. klunzingeri. The toxicity of both pollutants is mainly because of the induction of the reactive oxygen species (ROS), which lead to cell membrane disruption, damage of cellular metabolism, and interference with cellular macromolecules.

Association between the Occurrence of Primary Hypothyroidism and the Exposure of the Population Near to Industrial Pollutants in São Paulo State, Brazil

Background: Environmental agents interfere with thyroid function at multiple levels. This study was to investigate the association between pollutant concentrations and the primary hypothyroidism (PH) occurrence odds in residents living in the Capuava Petrochemical Complex (CPC) influence area. Methods: This area was evaluated with the combination of the AERMOD dispersion model with the Weather Research Forecast (WRF) meteorological model (2016). The concentration of atmospheric pollutants were analyzed in 2017 using meteorological data on the period from 2005 to 2009, correlating this data with the research done in 2003 to 2005. A home-based questionnaire was applied to evaluate 2004 residents, of both sexes, aged from 8 to 72 years, based on their proximity to the industrial areas; were select residents with PH. Results: Volatile organic compounds (VOCs), carbon monoxide (CO), and nitrogen dioxide (NO₂) concentrations presented the highest correlations between the PH odds and pollutant concentrations. Conclusion: Air pollution associated with the presence of the CPC is an important environmental factor contributing to the development of PH in the nearby population. As the first study showing this association in Brazil, research should be continued to better understand the mechanisms and to find ways to compensate for or remedy to avoid health impacts in future populations.

Spatio-temporal variability of biomarker responses and lipid composition of Marphysa sanguinea, Montagu (1813) in the anthropic impacted lagoon of Tunis

In this study the Polychaeta Marphysa sanguinea, was tested to investigate the impact of metal pollution on the environmental state of a coastal Mediterranean lagoon, Tunis Lagoon (Tunisia). A multi-biomarker approach comprising glutathione-stransferase, cyclooxygenase, lysozyme activity, and lipid class composition of the Polychaeta was employed on a seasonal basis in the present investigation. The multivariate statistical approach (principal component analysis and Pearson correlation) clearly demonstrated different spatial patterns in biomarker values and lipid class concentrations. The phospholipids were the dominant lipid class in M. sanguinea, with the highest value found at the control station. The impact of pollution was most clearly observed on the main storage lipid class, triacylglycerol, which was lowest in the most impacted sites. Our work suggests that M. sanguinea can be used in warmer Mediterranean costal habitats as a sentinel species of contaminated ecosystems.

Sex-biased regulation of respiratory burst, phagocytic activity and plasma immune factors in lined seahorse (Hippocampus erectus) after subchronic benzo[a]pyrene exposure

Both wild and aquacultured seahorses are currently under great threat from marine pollution, notably from the potent contaminant and carcinogen benzo[a]pyrene (BaP). However, very little data are available regarding the immunomodulating effects of BaP in seahorses. Therefore, in this study, we exposed lined seahorses (Hippocampus erectus) for 7 d to BaP at three dosages (0.5, 5, and 50 μg/L) to evaluate sexual dimorphism in immune response. We measured eight immune parameters in the blood, including respiratory burst (RB), phagocytic activity (PA), monocytes/leucocytes, immunoglobulin M, complement 3, complement, interferon-a, and interleukin-2. Male seahorses had significantly higher parameters than females, except in terms of monocytes/leucocytes (P < 0.05). Although flow cytometry showed that RB and PA variation per BaP dose were roughly similar across sexes, RB and PA exhibited distinct patterns. Additionally, fluorescence intensity and leucocyte percentage were positively correlated in PA but not RB for all treatment and sex combinations. Through ELISA, we showed that the other six parameters had complex responses that nevertheless varied in a BaP-dosage and sex-dependent manner. Overall, adult male seahorses had higher immunocompetence than females before BaP exposure, and sexual dimorphism continued to be apparent during BaP exposure. Furthermore, all eight parameters were sensitive to BaP. Based on these results, we highly recommend H. erectus as a sentinel species for crude contamination, whereas PA and RB are valuable bioindicators of marine contaminants such as BaP.

Transcriptomic analysis revealing hepcidin expression in Oryzias melastigma regulated through the JAK-STAT signaling pathway upon exposure to BaP

Our previous study revealed that an antimicrobial peptide hepcidin, can be significantly up-regulated either with LPS challenge or upon exposure to Benzo[a]pyrene (BaP) in red sea bream, but the molecular mechanism involved in whether the transcriptional expression of hepcidin induced by LPS or BaP is regulated through a similar signaling pathway is not yet known. To elucidate the underlying molecular mechanism, the marine model fish Oryzias melastigma was exposed to 1 μg/L BaP as well as challenged with 5 μg of LPS per fish. Samples at 3 h post-LPS challenge, and 2 d and 3 d post-BaP exposure were separately collected for transcriptome analysis. General analysis of the predicted immune-associated unigenes based on the transcriptomic data showed that the percentages of modulated immune-associated genes were 7% with LPS challenge, and 3% and 7% with BaP exposure at 2 and 3 days, respectively. Genes involved in functions like antimicrobial activity, neutrophil activation, and leukocyte chemotaxis were up-regulated with LPS challenge, whereas more than half of the immune associated genes including the KLF family were down-regulated upon BaP exposure, indicating a difference in the modulated immune genes between LPS challenge and BaP exposure. Specific comparative analyses of the immune-associated signal pathways NOD, TOLL, NF-κB and JAK-STAT with LPS challenge or upon exposure to BaP, indicated that most of the modulated genes in association with the NOD, TOLL and NF-κB pathways were induced with LPS challenge but only a few after exposure to BaP, suggesting that BaP exposure was generally not associated with any of the three signal pathways. Interestingly, further transcriptomic analysis revealed that 5 of the 8 modulated genes associated with the JAK-STAT pathway were down-regulated, while 2 inhibiting genes were up-regulated after BaP exposure for 2 days whereas LPS challenge resulted in only less than half modulated, suggesting the possibility of down-regulation caused by BaP exposure through JAK-STAT pathway. Further testing using an EPC cell culture demonstrated that expression of the hepcidin1 gene was less involved in the known signal pathways, such as c/EBP, BMP, and NF-κB, but instead mostly in association with the JAK-STAT pathway upon BaP exposure.

Effects of the environmental endocrine disrupting compound benzo[a]pyrene on thyroidal status of abu mullet (Liza abu) during short-term exposure

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The half-life of BaP is 3–4 days and then it metabolized in the liver.

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BaP concentration in the muscle of treated fish reached a maximum level after 4 days.

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Exposure of fish to BaP resulted in a decrease in T3 and T4 plasma levels up to day 4.

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Exposure of fish to BaP resulted in an increase in TSH plasma level up to day 4.

Benzo[a]Pyrene (BaP) is a ubiquitous polycyclic aromatic hydrocarbon (PAH) that has been shown to disrupt the metabolism of thyroid hormone. Then, the present investigation aimed to study the effects of BaP on thyroid function in Liza abu. Fish were injected with 2, 10 and 25 mg/kg-bw of BaP. Samples were taken from blood, thyroid and muscle tissues at days 1, 2, 4, 7, and 14. Blood was evaluated for changes in the plasma levels of TSH, T3 and T4. Also, BaP bioaccumulation in the fish muscle was measured. Thyroid tissues were processed for routine histology. BaP concentration in the muscle of treated fish reached a maximum level after 4 days. Exposure of fish to BaP resulted in a significant decrease in T3 and T4 plasma level and increase in TSH concentration up to day 4. Also some pathological alterations were observed in BaP-exposed fish such as hemorrhage and increased number of large follicles with squamous epithelium. In conclusion, according to the results of the present investigation, short term exposure to sublethal concentrations of BaP significantly affected thyroid function in fish. The results revealed BaP ability to alter thyroid function.

Using cell apoptosis, micronuclei and immune alternations as biomarkers of phenanthrene exposure in yellowfin seabream (Acanthopagrus latus)

In the present study, the apoptosis and tissue changes in the spleen, as well as humoral immune-related parameters, micronuclei (MN) induction in blood cells and Ethoxyresorufin-O-deethylase (EROD) activity were investigated in yellowfin seabream (Acanthopagrus latus) after short-term exposure to phenanthrene (Phe). The fish were intraperitoneally injected with different concentrations (2, 20 and 40 mg kg^-1) of Phe and tissue and blood samples were collected 1, 4, 7 and 14 days after injection. The concentrations of Phe in the fish liver increased 4 days after the experiment. EROD activity showed a pattern consistent with Phe concentration in the liver. Apoptotic index in the spleen increased dose dependently in Phe-exposed fish. Exposure to Phe caused significant decrease in the plasma level of immunoglobulin M, phagocytic and respiratory burst activity after 4 days of exposure. The frequency of MN in the erythrocytes of the treated fish was significantly higher than control. The main pathological alterations in the spleen included the increase in melanomacrophage centers (MMCs), destroyed red blood cell and hemorrhage. The degree of tissue changes in the spleen of the exposed fish ranged from slight to moderate damage. The size and number of MMCs in the spleen were significantly higher in Phe-treated fish compared to the control. Our results showed that Phe could suppress immune responses in fish, induce cell apoptosis, histological changes in the spleen and MN formation. This may suggest those parameters consider as useful biomarkers for monitoring of the health status of fish during exposure to Phe.

Assessment of immune status of yellowfin seabream (Acanthopagrus latus) during short term exposure to phenanthrene

The aim of the present investigation was to assess the immune status in yellowfin seabream (Acanthopagrus latus) exposed to different concentrations of phenanthrene (Phe) for 14days. In addition, the Phe accumulation in the fish muscle was measured during the experiment. Fish were injected with different concentrations (0, 2, 20 and 40mg/kg) of Phe and samples were taken from tissue and blood of fish 1, 4, 7 and 14days after injection. Exposure of fish to Phe caused a significant decrease in white blood cells, C3 and C4 levels, lysosomal membrane stability, lysozyme activity after 4days and antibacterial activity after 7days of the experiment. In contrast, cortisol level significantly increased after 4days. The concentration of Phe in fish muscle increased rapidly after 4days. The main tissue changes observed in the head kidney including increase in melanomacrophage centers (MMCs), empty spaces between cells and hemorrhage. The degree of tissue changes ranged from normal to moderate in Phe-treated fish. The size and number of MMCs in treated fish were significantly higher than control. In conclusion, Phe toxicity in yellowfin seabream can induce increased cortisol level, tissue changes and immune suppression.