In Vitro Detection of Biochemical Effect in Human CaCo-2 Cell Line after Exposure to a Low Concentration of a Deltamethrin-Based Pesticide

Pesticide residues are chemicals frequently found in food as contaminants. Pesticides may have adverse health effects, particularly when the digestive tract is concerned, as a consequence of food ingestion. Deltamethrin is a pyrethroid pesticide widely used in various fields, such as agriculture, veterinary and in the household, so the ingestion of a small amount of this chemical may occasionally occur. To assess whether exposure to pesticide residues may have a biological effect at the intestinal level, it is primarily necessary to perform in vitro exposure experiments about cell lines models of the intestinal barrier at low concentrations of the chemical. In the present study, CaCo-2 cells were exposed to different concentrations of a Deltamethrin-based commercial pesticide, which was diluted in the cell medium. An MTT viability test indicated that the cytotoxic concentration value of the pesticide inside 1 mL of medium is between 10⁻⁶ and 10⁻⁵ mL. However, the analysis of Raman spectra found that biochemical changes occur inside cells exposed to a non-cytotoxic concentration of 10⁻⁶ mL of the pesticide inside 1 mL of the medium. Such changes involve mainly an increase in the ratio between the amount of lipid with respect to that of the protein components in the cell cytoplasm. The results obtained by Raman micro-spectroscopy were confirmed by fluorescence images obtained by using a fluorophore staining neutral lipids. Overall, the obtained results suggest that Raman micro-spectroscopy can be successfully used to monitor the cellular modifications due to exposure at low concentrations of pesticides, as those values that can be found inside food are residuals.