RAD001-mediated mTOR targeting in human monocyte-derived dendritic cells shifts them toward an immunogenic phenotype.

Abstract

Dendritic cells (DCs) are essential for promoting T lymphocyte responses since they are specialist antigen-presenting cells. In order to maintain tolerance or initiate immune responses, DCs must be activated in a balanced and regulated manner via diverse signaling pathways. By using a variety of pharmacological components, we can interfere with their different signaling pathways such as the mammalian target of rapamycin (mTOR) to appropriately modulate DC activity. In the current study, we administered RAD001 to DCs to examine the impact of mTOR inhibition on both the maturation stage and the expression of inflammatory and anti-inflammatory molecules in DCs. Pure monocytes were cultivated and stimulated with GM-CSF and IL-4 to generate immature DCs, which were then treated with RAD001. The phenotype of the DCs was determined by labeling surface markers and analyzing them using flow cytometry. Afterward, real-time PCR was carried out to evaluate the expression of inflammatory and anti-inflammatory genes. The administration of RAD001 to DCs led to a significant upregulation in the gene expression of inflammatory molecules such as IL-12, IL-1β, tumor necrosis factor (TNF)-α, and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-KB). Conversely, RAD001 treatment resulted in a decrease in the gene expression of anti-inflammatory factors IL-10 and indoleamine 2,3-dioxygenase (IDO). However, the expression of differentiation and antigen presentation-related markers CD11c and human leukocyte antigens (HLA)-DR in RAD001-treated DCs was lower and higher compared to the control group that did not receive the treatment, respectively. Taken together, our findings indicated that RAD001 treatment of DCs can be a promising therapeutic approach for the generation of immunogenic DCs in order to barricade tumor growth. However, there is a need for further investigation to evaluate the impacts of mTOR inhibition by RAD001 in DCs on cellular immune responses in vitro and in vivo.