Th2 Cytokine Bias Induced by Silver Nanoparticles (AgNPs) in Peripheral Blood Mononuclear Cells (PBMCs) of Common Bottlenose Dolphins (Tursiops truncatus)
IAAAM 2018
Wen-Ta Li1*+; Lei-Ya Wang1; Hui-Wen Chang1; Wei-Cheng Yang2; Chieh Lo3; Victor Fei Pang1; Meng-Hsien Chen4; Chian-Ren Jeng1
1Graduate Institute of Molecular and Comparative Pathobiology, National Taiwan University, Taipei, Taiwan; 2College of Veterinary Medicine, National Chiayi University, Chiayi, Taiwan; 3Farglory Ocean Park, Hualien, Taiwan; 4Department of Oceanography and Asia-Pacific Ocean Research Center, National Sun Yat-sen University, Kaohsiung, Taiwan

Abstract

Silver nanoparticles (AgNPs) have been widely used in many commercial products due to their excellent antibacterial ability.1 The AgNPs are released into the environment, gradually accumulate in the ocean, and may affect the animals of high trophic level via food chain, such as cetacean and human.2 Hence, the negative health impacts caused by AgNPs in cetaceans are of concern. Cytokines play a major role in modulation of the immune system, and can be classified into Th1 (IL-12, IFN-γ, and IL-18) and Th2 (IL-4, IL-5, and IL-13).3,4,5 Th1/Th2 balance can be evaluated by the ratio of their polarizing cytokines (i.e., IFN-γ/IL-4), and animals with imbalanced Th1/Th2 response (Th1/Th2 polarization) may become more susceptive to certain kinds of infections.4,6,7 Therefore, the present study evaluated the in vitro cytokine responses of cetacean peripheral blood mononuclear cells (cPBMCs) to 20 nm citrate-AgNPs (C-AgNP20) by qRT-PCR. Blood samples of 6 common bottlenose dolphins (Tursiops truncatus) in Farglory Ocean Park. cPBMCs were isolated and utilized for evaluating the in vitro cytokine responses of cPBMCs to C-AgNP20 by quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). The selected cytokines included Interleukin (IL)-2, IL-4, IL-10, IL-12, interferon (IFN)-γ and tumor necrosis factor (TNF)-ɑ. The geometric means of two housekeeping genes (HKGs), glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and β2-microglobulin (B2M), of each samples were determined and used to normalize the mRNA expression levels of target genes. There was a significant increase in the ratio of late apoptotic/necrotic cells of cPBMCs with or without Con A stimulation after 24 h of 10 μg/ml C-AgNP20 treatment. At 4 h of culture, the mRNA expression level of IL-10 was significantly decreased with 1 μg/ml C-AgNP20. At 24 h of culture with 1 μg/ml C-AgNP20, the mRNA expression levels of all cytokines were significantly decreased with the exceptions of IL-4 and IL-10. IFN-γ/IL-4 was significantly decreased at 24 h of culture with 1 μg/ml C-AgNP20 treatments, and IL-12/IL-4 ratio was significantly decreased at 4 or 24 h of culture with 0.1 or 1 μg/ml C-AgNP20 treatments. Furthermore, the mRNA expression level of TNF-α was significantly decreased by 1 μg/ml C-AgNP20 after 24 h of culture. The present study demonstrated that the sublethal dose of C-AgNP20 on cPBMCs (≤1 μg/ml), and the inhibitory effect of C-AgNP20 on the mRNA expression levels of cytokines of cPBMCs with the evidence of Th2 cytokine bias and significantly decreased mRNA expression level of TNF-α. Th2 response is associated with enhanced immunity against to parasite but with decreased immunity to intracellular organisms.4,6 TNF-α is a contributing factor for the inflammatory response against the infection of intracellular pathogens.8 In summary, our data indicated that C-AgNP20 suppress the cell-mediated immune response, and thus may inhibit the immunity against intracellular organisms, such as Toxoplasma gondii, Brucella spp., and morbillivirus, in cetaceans.9,10

* Presenting author
+ Student presenter

Acknowledgements

We thank all the personnel of Farglory Ocean Park for blood sample collection and storage, the dolphins in Farglory Ocean Park for donating their blood, Dr. Bang-Yeh Liou for blood sample transportation, and Ministry of Science & Technology, Taiwan for financial support (Grant MOST 106-2313-B-002-054-).

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Speaker Information
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Wen-Ta Li
Graduate Institute of Molecular and Comparative Pathobiology
National Taiwan University
Taipei, Taiwan


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