In vitro immune-depression and anti-inflammatory activities of cantharidin on gilthead seabream (Sparus aurata) leucocytes activated by λ-carrageenan

Abstract

Cantharidin is a natural compound with known therapeutic applications in humans. However, its properties have hardly been studied in fish. The aim of this study was to investigate the in vitro effects of cantharidin on gilthead seabream (Sparus aurata) head kidney leucocytes (HKL) stimulated with λ-carrageenan. Thus, HKLs were incubated for 24 h with cantharidin (0, 2.5 and 5 μg mL-1) and λ-carrageenan (0 and 1,000 μg mL-1) and cell viability and morphology, immunological parameters and several selected genes related to inflammation and apoptosis were evaluated. The results showed that cantharidin only decreased HKL viability when incubated with the highest dose (5 μg mL-1) and in combination with λ-carrageenan. As for the immunological parameters studied, cantharidin increased the peroxidase activity of HKLs only when incubated in combination with λ-carrageenan, but inhibited the respiratory burst and phagocytic activities even after being previously increased by λ-carrageenan. Furthermore, cantharidin induced morphological changes in HKLs with apoptotic and vacuolization signs that were enhanced when incubated in combination with λ-carrageenan. Considering the analysis of gene expression in HKLs, although λ-carrageenan up-regulated the expression of the proinflammatory gene il1b, cantharidin down-regulated its expression in HKLs exposed to both λ-carrageenan and cantharidin. In addition, cantharidin up-regulated casp3 and casp9 expression, which was down-regulated in HKLs incubated with both molecules. This combination also up-regulated casp1 expression. The present results provide detailed insight into the immune-depressive and anti-inflammatory properties of cantharidin on immune cells, which could be of interest to the aquaculture sector.