Immunomodulatory Effects of Pure Cylindrospermopsin in Rats Orally Exposed for 28 Days

Cylindrospermopsin (CYN) is a ubiquitous cyanotoxin showing increasing incidence worldwide. CYN has been classified as a cytotoxin and, among its toxic effects, its immunotoxicity is scarcely studied. This work investigates for the first time the influence of oral CYN exposure (18.75; 37.5 and 75 mu g/kg b.w./day, for 28 days) on the mRNA expression of selected interleukin (IL) genes (IL-1 beta, IL-2, IL-6, Tumor Necrosis Factor alpha (TNF-alpha), Interferon gamma (IFN-gamma)) in the thymus and the spleen of male and female rats, by quantitative real-time polymerase chain reaction (RT-qPCR). Moreover, their serum levels were also measured by a multiplex-bead-based immunoassay, and a histopathological study was performed. CYN produced immunomodulation mainly in the thymus of rats exposed to 75 mu g CYN/kg b.w./day in both sexes. However, in the spleen only IL-1 beta and IL-2 (males), and TNF-alpha and IFN-gamma (females) expression was modified after CYN exposure. Only female rats exposed to 18.75 mu g CYN/kg b.w./day showed a significant decrease in TNF-alpha serum levels. There were no significant differences in the weight or histopathology in the organs studied. Further research is needed to obtain a deeper view of the molecular mechanisms involved in CYN immunotoxicity and its consequences on long-term exposures.

Automated summary

This study investigated the immunotoxicity of oral exposure to Cylindrospermopsin (CYN) in rats. The results showed that CYN mainly affected the immune modulation in the thymus and altered the expression of certain cytokines in the spleen. Additionally, CYN also had an impact on the serum levels of female rats.