Lactobacillus reuteri and Staphylococcus aureus differentially influence the generation of monocyte-derived dendritic cells and subsequent autologous T cell responses

We show that bacterial signals during DC differentiation have a profound impact on DC function and possibly also for shaping the T cell pool.

We exposed monocyte cultures to cell-free supernatants (CFS) from these bacteria during their differentiation to DC.

The presence of L. reuteri-CFS during DC differentiation resulted in DC with a more mature phenotype, in terms of up-regulated surface markers (HLA-DR, CD86, CD83, CCR7) and enhanced cytokine production (IL6, IL10, and IL23), but had a reduced phagocytic capacity compared with non-treated monocyte-derived DC (Mo-DC). However, upon LPS activation, L. reuteri-CFS-generated DC displayed a more regulated phenotype than control Mo-DC with notable reduction of cytokine responses both at mRNA and protein levels. In contrast, S. aureus-CFS-generated DC were more similar to control Mo-DC both without and after LPS stimulation, but they were still able to induce responses in autologous T cells, in the absence of further T cell stimulation. Conclusions: We show that bacterial signals during DC differentiation have a profound impact on DC function and possibly also for shaping the T cell pool.