Effects of polychlorinated biphenyls (PCB) on California sea lion (Zalophus californianus) lymphocyte functions upon in vitro exposure

Physiological values of phagocytic capacity in marine mammals and alterations during pathological situations

The study of the immune function in marine mammals is essential to understand their physiology and can help to improve their welfare in the aquariums. Dedicating efforts to studying marine mammal physiology, pathophysiology, and implementing new diagnostic and therapeutic tools promote progress towards preventive medicine in aquariums by facilitating early detection and treatment of diseases. However, biological and clinical research on marine mammals is currently very limited due to difficult access to these species and their biological samples. With this objective, our group has adapted to marine mammals a commercially available assay routinely used to evaluate the phagocytic capacity of monocytes and granulocytes in human whole blood samples. We adapted IngoflowEx kit to bottlenose dolphins (Tursiops truncatus), beluga whales (Delphinapterus leucas), walruses (Odobenus rosmarus), Patagonian sea lions (Otaria flavescens), and harbor (Phoca vitulina). In this paper, we report the modifications carried out on the original protocol for their correct functioning in marine mammals. We obtained physiological values of phagocytic capacity in each species after repeated sampling for 4 years in various individuals of each species. Specific results revealed that the % phagocytic cells that ingested E.coli in bottlenose dolphins were 59.6 ± 1.27, in walruses 62.6 ± 2.17, in sea lions 57.5 ± 4.3, and in beluga whales 61.7 ± 1.4. In the case of the % phagocytic cells producing respiratory burst in bottlenose dolphins were 34.2 ± 3.6, in walruses 36.3 ± 4.3, in sea lions 40.8 ± 10.2, and in beluga whales 26.3 ± 3.7. These preliminary results can be used as a reference to detect alterations in phagocytic capacity either by immunosuppression or by exacerbation of the response in infectious inflammatory processes. Clinical applicability of the assay was verified in two clinical cases in which Ingoflow was useful to detect immune alterations in two diseased individuals, before and after the onset of clinical signs.

The residues and health risk assessment of polychlorinated biphenyls (PCBs) in Pheretima (an earthworm-derived traditional medicine) from southeastern China

Minimal research exists on polychlorinated biphenyl (PCB) exposure from traditional Chinese medicines (TCMs), despite their significant contributions to domestic and international health protection. This study is the first to investigate the levels, profiles, and health risks of PCB residue in Pheretima, a typical TCM produced from earthworm. Seventy-seven Pheretima samples from different regions of China were analyzed for 45 PCB congeners. PCBs were found in all samples exhibiting species-dependent discrepancies. ∑45PCBs was ranging from 0.532 to 25.2 µg/kg (mean 4.46 µg/kg), with CB-11 being the most abundant congener contributing 71.8% ± 10.8% to ∑45PCBs, followed by CB-47, which were all non-Aroclor congeners called unintentionally produced PCBs (UP-PCBs). The average estimated daily intake of ∑45PCBs, ∑7ID-PCBs (indicative polychlorinated biphenyls), and CB-11 were 0.71, 0.04, and 0.51 ng/kg bw/d, respectively. The ∑HQ of PCBs in Pheretima samples was 2.97 × 10-4-2.46 × 10-2 (mean 2.77 × 10-3, 95th 4.21 × 10-3), while the ∑RQ ranged from 1.19 × 10-8 to 2.88 × 10-6 (mean 4.87 × 10-7, 95th 2.31 × 10-6). These findings indicate that Pheretima ingestion does not pose significant non-carcinogenic risks. However, certain individual samples exhibit an acceptable level of potential risks, particularly when considering that PCBs are recognized as endocrine disruptors and classified as probable carcinogens. These results contribute to the safety evaluation of traditional medicines and suggest the potential use of Pheretima as a bioindicator for PCB pollution. It is advisable to monitor UP-PCBs as indicator congeners and gather additional toxicological data.

Accumulation characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans and polychlorinated biphenyls in human breast milk from a seaside city of North China

Breast milk samples were collected from 51 mothers in a seaside city Dalian, where the residents usually have higher dietary exposure to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) due to the larger consumption of seafood. The lipid-basis concentrations of ∑Cl_2-8DD/Fs, ∑Cl_2-10Bs, and total toxicity equivalent (WHO-TEQ) were measured to be in the ranges of 35.7-2727.8 pg/g, 4.91-52.64 ng/g, and 2.27-36.30 pg/g, respectively. The average proportion of ∑Cl_2-3DD/Fs was higher than that of ∑Cl_4-7DD/Fs in the collected human breast milk samples, suggesting that the health risk of Cl_2-3DD/Fs should be especially concerned. The concentration data of PCDD/Fs and PCBs in human breast milk essentially followed a positive skew probability distribution. Women in high-level exposure scenarios exhibited a higher potential to accumulate homologues Cl₄DFs, Cl₇DFs, Cl₈DF, and Cl₆Bs in breast milk. Three PCDD/F congeners (1,2,3,6,7,8-Cl₆DF, 1,2,3,4,7,8-Cl₆DF, and 1,2,3,4,6,7,8-Cl₇DD) and three PCB congeners (PCB 126, PCB 138, and PCB 169) were identified as good indicators for the accumulation of PCDD/Fs and PCBs in human breast milk, respectively. The food-to-milk accumulation factors (FMAF) were calculated to evaluate the accumulation potentials of different PCDD/F and PCB congeners in human breast milk via dietary exposure. The calculated FMAF value presented a non-monotonic variation with the logarithm of n-octanol-water partition coefficient (log K_OW) with a peak at a log K_OW value of about 7.3 and a valley at a log K_OW value of about 8. The mean value of the estimated daily intake (EDI) of total WHO-TEQ for breast-fed infants in Dalian, predicted by Monte Carlo simulation, was 10 folds higher than the upper range of the tolerable daily intake (TDI) value (4 pg WHO-TEQ/kg bw/d), suggesting continued and enhanced efforts should be made to reduce the exposure risk of infants to PCDD/Fs and PCBs.

Immunohistochemical Analysis Using Monoclonal Antibody PMab-269 Against Steller Sea Lion Podoplanin

Monoclonal antibodies (mAbs) that specifically target podoplanin (PDPN), a marker for type I alveolar cells, are required for immunohistochemical analyses. Anti-PDPN mAbs are available for many species, including human, mouse, rat, rabbit, dog, cat, bovine, pig, Tasmanian devil, alpaca, tiger, whale, goat, horse, bear, sheep, and California sea lion PDPNs. However, no anti-Steller sea lion PDPN (stePDPN) antibody has been developed. Immunohistochemical analysis showed that an anti-California sea lion PDPN mAb (PMab-269) reacted with type I alveolar cells from the Steller sea lion lung, renal glomeruli and Bowman's capsules from kidney, and lymphatic endothelial cells from the colon, indicating that PMab-269 is useful for detecting stePDPN.

Predicting consequences of POP-induced disruption of blubber glucose uptake, mass gain rate and thyroid hormone levels for weaning mass in grey seal pups

Persistent organic pollutants (POPs) are endocrine disruptors that alter adipose tissue development, regulation and function. Top marine predators are particularly vulnerable because they possess large fat stores that accumulate POPs. However, links between endocrine or adipose tissue function disruption and whole animal energetics have rarely been investigated. We predicted the impact of alterations to blubber metabolic characteristics and circulating thyroid hormone (TH) levels associated with polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and organochlorine pesticides (OCPs) on suckling mass gain and weaning mass in wild grey seal pups. Glucose uptake by inner blubber was a strong predictor of whole animal mass gain rate, which in turn, resulted in heavier weaning mass. Weaning mass was predicted to increase by 3.7 ± 1.59 (sem) %, through increased mass gain rate, in the absence of the previously reported suppressive effect of dioxin-like PCB (DL-PCBs) on blubber glucose uptake. PBDEs were, conversely, associated with faster mass gain. Alleviation of this effect was predicted to reduce weaning mass by 6.02 ± 1.86% (sem). To better predict POPs effects on energy balance, it is crucial to determine if and how PBDEs promote mass gain in grey seal pups. Weaning mass was negatively related to total T3 (TT3) levels. A 20% (range = 9.3-31.7%) reduction in TT3 by DL-PCBs partially overcame the effect of DL-PCB -mediated reduction in blubber glucose uptake. Overall, DL-PCBs were thus predicted to reduce weaning mass by 1.86 ± 1.60%. Organohalogen impacts on whole-animal energy balance in grey seal pups appear to partially offset each other through opposing effects on different mechanisms. POP effects were generally minor, but the largest POP-induced reductions in weaning mass were predicted to occur in pups that were already small. Since weaning mass is positively related to first-year survival, POPs may disproportionately affect smaller individuals, and could continue to have population-level impacts even when levels are relatively low compared to historical values. Our findings show how in vitro experiments combined with measurements in vivo can help elucidate mechanisms that underpin energy balance regulation and help to quantify the magnitude of disruptive effects by contaminants and other stressors in wildlife.

Accumulation characteristics and estimated dietary intakes of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and polychlorinated biphenyls in plant-origin foodstuffs from Chinese markets

The levels and accumulation characteristics of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were investigated in nine pools of representative plant-origin foodstuffs randomly collected from markets located in five regions of the Chinese mainland during 2018-2019. The collected foodstuffs consisted of cereals, beans, potatoes, leafy vegetables, root and stem vegetables, melon vegetables, legume vegetables, edible fungi, and mixed vegetable oil. In the fresh plant food pools, the concentrations of toxic equivalency (WHO-TEQ) were in the ranges of 0.9-14.5 pg/kg in upperbound (UB) scenario and 0.002-7.3 pg/kg in lowerbound (LB) scenario on a fresh weight basis; and TriCDFs and TeCBs were the predominant PCDD/F and PCB homologues, respectively. In the mixed vegetable oil, the WHO-TEQ concentrations were 129.4 pg/kg and 103.6 pg/kg on a lipid weight basis in UB and LB scenarios, respectively; and high-chlorinated PCDD/F and PCB homologues were much more abundant. The estimated plant food-borne dietary intakes of WHO-TEQ by a standard adult in the five surveyed regions were in the ranges of 3.39-4.20 and 1.57-2.13 pg WHO-TEQ/kg body weight/month in UB and LB scenarios, respectively. Among all surveyed regions, consumption of cereals and vegetable oil made up the primary contributions to the estimated dietary intakes of WHO-TEQ. TriCDFs accounted for 41.1-83.9% of the PCDD/Fs dietary intakes via consumption of plant foods, and TeCBs made up 61.2-73.0% of the PCBs dietary intakes via consumption of plant foods, suggesting that the potential toxic effects of TriCDFs and TeCBs on human health should be concerned.

Risk assessment of potentially toxic elements accumulated in fish to Indo-Pacific humpback dolphins in the South China Sea

Indo-Pacific humpback dolphins (Sousa chinensis) reside in shallow coastal waters where they are exposed to potentially toxic elements (PTEs) through dietary intake. We quantitatively assessed the risk posed by eight PTEs to the health of S. chinensis by determining their concentration in 13 fish species. The fish species represented the primary prey of S. chinensis in the South China Sea. Zn and Mn were the most dominant elements in fish at all sampling locations with concentrations ranges of 19.93-67.63 mg kg ^-1 dry weight (dw) and 1.52-68.2 mg kg ^-1 dw, respectively. The highest Zn concentration in fish was found in Coilia mystus (72.65 mg kg^-1 dw) followed by Liza carinatus (62.57 mg kg^-1 dw). At Jiangmen, Zn concentration was significantly lower in benthopelagic fish than in pelagic fish (p < 0.05, one-way ANOVA), while no significant difference was observed in other metals. The health risk posed by dietary intake assessed using the toxicity reference value showed that PTEs did not significant health risk to S. chinensis. In contrast, the risk quotient (RQ) based on reference doses ranged from 2.17 to 54.63 in prey fish that were contaminated with Zn and Cr indicating a potential health risk to S. chinensis in the South China Sea. The number of PTEs that posed a health risk varied between sites with seven out of eight PTEs above threshold at Jiangmen and six out of eight at Zhanjiang and Qinzhou. This study showed fish niche and location may influence the health risk posed by consumption of PTE-contaminated fish.

Juvenile harbor porpoises in the UK are exposed to a more neurotoxic mixture of polychlorinated biphenyls than adults

Polychlorinated biphenyls (PCBs) are a group of 209 persistent and bio-accumulative toxic pollutants present as complex mixtures in human and animal tissues. Harbor porpoises accumulate some of the highest levels of PCBs because they are long-lived mammals that feed at a high trophic level. Studies typically use the sum of a suite of individual chlorobiphenyl congeners (CBs) to investigate PCBs in wildlife. However, toxic effects and thresholds of CB congeners differ, therefore population health risks of exposure may be under or over-estimated dependent on the congener profiles present. In this study, we found congener profiles varied with age, sex and location, particularly between adult females and juveniles. We found that adult females had the highest proportions of octa-chlorinated congeners whilst juveniles had the highest proportions of tri- and tetra-chlorinated congeners. This is likely to be a consequence of pollutant offloading between mothers and calves during lactation. Analysis of the individual congener toxicities found that juveniles were exposed to a more neurotoxic CB mixture at a time when they were most vulnerable to its effects. These findings are an important contribution towards our understanding of variation in congener profiles and the potential effects and threats of PCB exposure in cetaceans.

Organochlorine contaminant concentrations in blubber of young Steller sea lion (Eumetopias jubatus) are influenced by region, age, sex, and lipid stores

Contaminant exposure is particularly important for species and populations of conservation concern, such as the Steller sea lion (Eumetopias jubatus). We used blubber samples (n = 120) to determine organochlorine concentrations, including polychlorinated biphenyls (PCBs) and dichloro-diphenyl-trichloroethane (DDTs), and blood samples (n = 107) to estimate total body lipids based on the hydrogen isotope dilution method. We assessed the influence of age, sex, condition, and geographic area on contaminant concentrations in blubber and contaminant body load. The concentration of ΣPCBs was highest in pups (<6 months) from the Aleutian Islands, and the concentrations in males were higher than females in all regions. The ΣPCBs and ΣDDTs concentrations and loads decreased with increasing mass in pups, however, there were no regional or sex differences in contaminant load. Within each of the five age classes, the concentrations of ΣPCBs and ΣDDTs decreased with increasing mass, but overall these OCs increased with age. Further, accounting for the lipid content, a potential proxy for energy balance, in the animal load reduced or removed the regional and sex effects present in age models for contaminants. We propose, that adjusting OCs concentration by the lipid content of the blubber sample alone may not fully account for the variability in OC concentrations associated with differences in condition or energy states between young Steller sea lions.

Transcriptional Profiles of California Sea Lion Peripheral NK and CD+8 T Cells Reflect Ecological Regionalization and Infection by Oncogenic Viruses

The California sea lion is one of the few wild mammals prone to develop cancer, particularly urogenital carcinoma (UGC), whose prevalence is currently estimated at 25% of dead adult sea lions stranded along the California coastline. Genetic factors, viruses and organochlorines have been identified as factors that increase the risk of occurrence of this pathology. Given that no cases of UGC have as yet been reported for the species along its distribution in Mexican waters, the potential relevance of contaminants for the development of urogenital carcinoma is highlighted even more as blubber levels of organochlorines are more than two orders of magnitude lower in the Gulf of California and Mexican Pacific than in California. In vitro studies have shown that organochlorines can modulate anti-viral and tumor-surveillance activities of NK and cytotoxic T-cells of marine mammals, but little is known about the activity of these effectors in live, free-living sea lions. Here, we examine leukocyte transcriptional profiles of free-ranging adult California sea lions for eight genes (Eomes, Granzyme B, Perforin, Ly49, STAT1, Tbx21, GATA3, and FoxP3) selected for their key role in anti-viral and tumor-surveillance, and investigate patterns of transcription that could be indicative of differences in ecological variables and exposure to two oncogenic viruses: sea lion type one gammaherpesvirus (OtHV-1) and sea lion papillomavirus type 1 (ZcPV-1) and systemic inflammation. We observed regional differences in the expression of genes related to Th1 responses and immune modulation, and detected clear patterns of differential regulation of gene expression in sea lions infected by genital papillomavirus compared to those infected by genital gammaherpesvirus or for simultaneous infections, similar to what is known about herpesvirus and papillomavirus infections in humans. Our study is a first approach to profile the transcriptional patterns of key immune effectors of free-ranging California sea lions and their association with ecological regions and oncogenic viruses. The observed results add insight to our understanding of immune competence of marine mammals, and may help elucidate the marked difference in the number of cases of urogenital carcinoma in sea lions from US waters and other areas of their distribution.