Impact of rapamycin and tacrolimus on the differentiation and maturation of monocyte-derived dendritic cells and their interactions with T cells

G.D. Dahlqvist, F.C. Conti, Y.H. Horsmans

Friday 16 march 2018

10:00 - 10:05h at Willem Burger Foyer

Categories: Basic, Session (poster)

Parallel session: Poster session 8: Basic translational research

Background

Immunosuppressive drugs are needed after solid organ transplantation. However the patients have to face severe side effects such as kidney failure, metabolic syndrome, elevated risk of infections and cancers. Understanding the alloimmune response is a critical step to develop possibilities of modulating it to achieve graft operational tolerance. Dendritic cells (DCs), as professional antigen presenting cells play a critical role in the initiation and regulation of the alloimmune response.

The aim of this study was to better understand the effect of tacrolimus, a calcineurin inhibitor, and rapamycin, an m-tor inhibitor, on the differenciation, maturation and function of monocyte derived DCs in vitro.

Material and methods

DCs were cultured from monocytes of healthy donors with GM-CSF and IL-4 with rapamycin (Rapa-DC) or tacrolimus (Tac-DC). The phenotype and functional properties were then evaluated using FACS analysis of surface markers, ELISA of IL-10 and IL-12 in the supernatants and leukocyte mixed reactions.

Results

Rapa-DC were characterised by a lower expression in co-stimulatory molecules CD80 and CD86 than control-DCs (CTR-DC) (p< 0.05). The expression of CD83, a dendritic cell maturation marker was also reduced in Rapa-DC. Tacrolimus had no effect on the expression of surface markers CD80, CD83 and CD86 compared to CTR-DCs. Rapamycin reduced both IL-12 and IL-10 secretions (p<0.05) while tacrolimus reduced IL-12 secretion (p<0,05) compared to controls. CTR-DCs increased IL-12 secretion after LPS stimulation. Rapa-DCs had a reduced capacity to secrete IL-12 confirming the lower capacity of dendritic cells to respond to LPS stimulation. Rapa-DCs have a suppressive activity on CD4⁺ allogeneic T compared to CTR-DCs (p<0.05) Rapamycin or tacrolimus-treated DCs did not favour the emergence of a CD4⁺CD25^highFoxp3⁺ population compared to CTR-DCs.

Conclusion

The immature phenotype and the reduction of IL-10 and IL-12 secretion in Rapa-DC lead to allogeneic T-cell hyporesponsiveness and can lead to a tolerogenic pattern in vitro in contrast to Tac-DC.