Assessment of potential immunotoxic effects caused by cypermethrin, fluoxetine, and thiabendazole using heat shock protein 70 and interleukin-1β mRNA expression in the anuran Xenopus laevis

The current study describes the effect of cypermethrin, fluoxetine, and thiabendazole, at environmentally relevant concentrations, on the expression of heat shock protein 70 (HSP70) and interleukin 1β (IL-1β), using Xenopus laevis larvae as animal model. Cytokines and interleukins are considered good predictors of the immunotoxic potential of xenobiotics. Tadpoles at stage 47 (normal tables of X. laevis) were exposed under static conditions to: 0.3 and 30 µg/L fluoxetine, 0.7 µg/L thiabendazole, and 0.24 µg/L cypermethrin. The effects were evaluated at 7, 24, and 72 h, and 6 and 9 d. Randomly chosen tadpoles were used as genetic material for detection of hsp70 and IL-1β mRNA induction through reverse transcription PCR. Tadpoles exposed to 30 µg/L fluoxetine showed mRNA expression of both genes at all exposure times, whereas at 0.3 µg/L a peak response for hsp70 was observed after 24 h, and the increase in IL-1β mRNA was statistically significant with respect to the control 72 h after exposure. Thiabendazole induced a high expression of mRNA for both hsp70 and IL-1β at all exposure times. Cypermethrin increased the hsp70 mRNA levels, with a peak at 24 h, and provoked high expression of IL-1β mRNA at all exposure times. Considering the relationship between HSP70 and IL-1β and their involvement (mainly of IL-1β) in immune responses, certain changes observed in their expression could be considered warning indicators of potential immunotoxic effects of these substances on Xenopus.