Looking for protein expression signatures in European eel peripheral blood mononuclear cells after in vivo exposure to perfluorooctane sulfonate and a real world field study.

The decline of European eel population can be attributed to many factors such as pollution by xenobiotics present in domestic and industrial effluents. Perfluorooctane sulfonate (PFOS) is a ubiquitous compound of a particular concern in Europe. PFOS can reach high concentrations in tissues of organisms and many toxic effects have been reported in fish. This study aimed at evaluating the toxicological effects of PFOS in European eel peripheral blood mononuclear cells (PBMCs) at the protein expression level. To identify proteins whose expression was modified by PFOS, we performed a proteomic analysis on the post-nuclear fraction of PBMCs after a chronic exposure (28 days) of yellow eels to zero, 1 or 10 μg/L PFOS. This in vivo study was completed by a proteomic field study on eels sampled in Belgian rivers presenting different PFOS pollution degrees. Proteins were separated by two-dimensional in-gel electrophoresis (2D-DIGE) to compare the post-nuclear fraction of PBMCs from the reference group with cells from fish exposed to the pollutant of interest. On the 28 spots that were significantly (p < 0.05; ANOVA followed by a Dunnett post-hoc test) affected by PFOS in the in vivo experiment, a total of 17 different proteins were identified using nano-LC ESI-MS/MS and the Peptide and Protein Prophet of Scaffold software. In the field experiment, 18 significantly (p < 0.05; ANOVA followed by Dunnett's test) affected spots conducted to the identification of 16 different proteins. Interestingly, only three proteins were found in common between in vivo and in situ experiments: plastin-2, alpha-enolase and glyceraldehyde 3-phosphate dehydrogenase. Comparing the results with a previous study, plastin-2 and alpha-enolase were also been found to be affected after in vitro exposure of PBMCs during 48 h to either 10 μg or 1 mg PFOS/L. Potential use of these proteins as biomarkers of PFOS exposure in European eel could indicate early warning signals.