[Activation of NOD2 signalling pathway stimulates the function of human dendritic cells loaded with leukemia cell...

The purpose of this study was to explore the effect of NOD2 signalling pathway activated by muramyl dipeptide (MDP) on the immunomodulation effect of human monocyte-derived dendritic cells (DC) loaded with leukemia cell lysates. Peripheral blood mononuclear cells (PBMNC) were isolated by density gradient centrifugation, These cells were cultured with three cytokines for 7 days to induce their maturation. On the 5th day, cells were loaded with leukemia cell HL-60 lysates. NOD2 expression was detected by RT-PCR and Western blot. The phenotype of DC were analyzed by flow cytometry, and ELISA was used to assay levels of IL-12 (p40) . The results showed that MDP could trigger NOD2 mRNA and protein expression in different groups of DC, especially in sensitized DC+MDP group, which was significantly higher than that in the DC+MDP group and sensitized DC without MDP stimulation, the difference was statistically significant (P < 0.05). Besides, the expression of surface molecules (HLA-DR, CD80, CD83, CD86, CD40) in the group of DC loaded with leukemia cell lysate and stimulated by MDP (sensitized DC+MDP) reached the highest level, followed by the group of DC loaded with leukemia cell lysate without MDP and DC only stimulated by MDP, non-treated DC were the lowest (P < 0.05). Similarly, compared with untreated unstimulated DC, after loading with HL-60 lysates or only stimulating with MDP, the secretion of IL-12p40 increased, but IL-12p40 level (573.86 ± 32.09 pg/ml) in DC+MDP group was higher than that in group of sensitized DC (365.03 ± 28.86 pg/ml) (P < 0.05), and it in sensitized DC+MDP group reached the highest (898.30 ± 61.08) pg/ml, compared to other groups (P < 0.05). It is concluded that MDP can significantly enhance the NOD2 mRNA and protein expression in sensitized DC, promote the expression of HLA-DR, synergistic costimulatory molecules and adhesion molecules of DC, at the same time, MDP can increase secretion of inflammatory factors IL-12p40. This study will provide a new ideas for DC application in leukemia immunotherapy.