Lack of significant impact of deoxynivalenol (DON) on both swine dendritic cell activities and systemic infection caused by a virulent Streptococcus suis serotype 2 strain

Deoxynivalenol (DON) is a common mycotoxin in swine feed known for its immunomodulatory effects and potential to exacerbate infectious diseases. However, its impact on systemic bacterial infections remains unclear. This study investigated whether DON influences the interaction between porcine marrow-derived dendritic cells (DCs) and Streptococcus suis, a major swine and zoonotic pathogen, as well as the progression of systemic infection in weaned piglets. In vitro exposure of DCs to non-toxic concentrations of DON (0.5 and 1 µM) neither altered the phagocytic uptake or intracellular survival of S. suis, nor did it affect anti-inflammatory cytokine expression. However, a moderate downregulation of IL-6 and IL-8 mRNA expression was observed. In vivo, piglets fed diets naturally contaminated with DON (1 or 2 mg/kg) and challenged with S. suis serotype 2 showed no significant differences in clinical signs, survival rates, or weight gain compared to controls. Although transiently increased bacteremia was observed at early stages post-infection in DON-exposed groups, it did not translate into more severe disease. These results suggest that under the conditions tested, DON has limited impact on DC functionality and does not significantly enhance susceptibility to systemic S. suis infection. This work provides relevant data for swine health risk assessments related to feed contamination with DON.