Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8987
Title: Transcriptional changes in innate immunity genes in head kidneys from Aeromonas salmonicida-challenged rainbow trout fed a mixture of polycyclic aromatic hydrocarbons
Author: L. R. Curtis, Claudia Bravo, Christopher J. Bayne, Fred Tilton, M. R. Arkoosh, Elisabetta Lambertini, F. J. Loge, Tracy K. Collier, James P. Meador, Susan C. Tilton
Publication Year: In press
Journal: Ecotoxicology and Environmental Safety
Volume: 142
Pages: 157-163
DOI: 10.1016/j.ecoenv.2017.03.044

We previously observed that exposure to a complex mixture of high molecular weight polycyclic aromatic hydrocarbons (PAHs) increased sensitivity of rainbow trout (Oncorhynchus mykiss) to subsequent challenge with Aeromonas salmonicida, the causative agent of furunculosis.  In this study, we evaluate potential mechanisms associated with disease susceptibility from combined environmental factors of dietary PAH exposure and pathogen challenge.  Rainbow trout were fed a mixture of ten high molecular weight PAHs at an environmentally relevant concentration (400ppm) or control diet for 50 days. After 50 days of PAH exposure, fish were challenged with either Aeromonas salmonicida at a lethal concentration 30 (LC30) or growth media without the pathogen (mock challenge). Head kidneys were collected 2, 4, 10 and 20 days after challenge and gene expression was evaluated among treatments. In animals fed the PAH contaminated diet, we observed down-regulation of expression for innate immune system genes for the terminal steps of the complement cascade (complement component C6) and other bacteriolytic processes (lysozyme type II) potentially underlying increased disease susceptibility after pathogen challenge. Increased expression of genes associated with hemorrhage/tissue remodeling/inflammation was likely related to more severe head kidney damage due to infection in PAH-fed compared to control-fed fish.  This study is the first to evaluate transcriptional signatures associated with the impact of chronic exposure to an environmentally relevant mixture of PAHs in disease susceptibility and immunity.

Theme: Habitats to Support Sustainable Fisheries and Recovered Populations
Foci: Characterize the interaction of human use and habitat distribution, quantity and quality.
Assess the impacts of toxic chemicals and other pollutants across biological scales, and identify pollution reduction strategies that improve habitat quality.
Official Citation:

Ecotoxicol Environ Saf. 2017 Aug;142:157-163. doi: 10.1016/j.ecoenv.2017.03.044. Epub 2017 Apr 11