Cellular redox homeostasis and environmental toxicity

Nowadays human beings are exposed to a wide variety of man-made substances used as pesticides and plasticizers whose intermediate or final products are released in the environment mainly resulting in food and water contamination. Such contaminants of emerging concern, belonging to the classes of: herbicides ~ GP and PHEN; insecticides ~ IMI; industrially widely used BPA, PFOA and alkylphenols ~ NP and OP, were characterized intracellularly using 24h incubations in HepG2 and Hacat cell lines as appropriate in vitro models. A sub-lethal concentration of each contaminant, defined through MTT assay, also based on the range of concentrations typically found in human body fluids and tissues, was used for all the biochemical parameters herein evaluated, including several components of human metabolism as ROS/RONS production, mitochondrial membrane potential, oxygen consumption rate, NOS isoforms expression, together with Mn-SOD and Cyt c. All substances showed an increase of iNOS expression, more marked in HepG2 cell line and an increase in nitrate/nitrate accumulation in both cell lines. Interestingly OP and NP, also classified as xenoestrogens showed significant increase in ROS production, NO oxides and peroxynitrated protein-derivatives. The mitochondrial proton electrochemical potential gradient instead was decreased, as the oxygen consumption by Complex IV, particularly following incubation with NP. Consistently the RT-PCR and western blot analyses proved that the OP and NP can modulate to a different extent the expression of the inducible NOS (p NP vs CTR ≤ 0.01) and the endothelial NOS (p OP vs CTR ≤ 0.05), with a significant variation of the coupling efficiency of the latter (p NP vs CTR ≤ 0.05, a finding that may provide a novel clue to understand the specific xenoestrogenic properties of OP and NP.