Abstract:

Objective To investigate the effects of 1α，25-dihydroxyvitamin D3 [1,25 (OH)2D3] on the differentiation, maturation and apoptosis of cord blood monocyte-derived dendritic cells (DCs). Methods Cord blood monocytes were isolated from human umbilical cord, and were cultured in vitro in the presence of recombinant human granulocyte/macrophage colony-stimulating factor (rhGM-CSF), recombinant human interleukin-4 (rhIL-4) and recombinant human tumor necrosis factor-α (rhTNF-α) to obtain the immature DCs (iDCs) and mature DCs (mDCs), with addition of 1,25 (OH)2D3 or not (treatment group or control group). The differentiation and maturation surface markers on DCs were determined by immunofluorescence staining and flow cytometry. The expression of vitamin D receptor (VDR) mRNA and 1-α-hydroxylase (CYP27B1) mRNA was detected by Real-Time PCR. The apoptosis of DCs was measured using Annexin V-FITC and PI staining by flow cytometry. Results ①Compared with control group, the expression of CD14 on iDCs was significantly higher (40.05% vs 5.14%, P<0.001), the expression of CD1a and CD11c on iDCs was significantly lower (12.73% vs 30.07%, P<0.01；91.27% vs 95.94%，P<0.05), and the expression of CD80, CD86 and HLA-DR on mDCs was significantly lower in treatment group (3.52% vs 17.75%，P<0.01；51.10% vs 69.76%，P<0.01；69.38% vs 92.35%，P<0.01). ②With the differentiatiation and maturation of DCs, the expression of CYP27B1 in iDCs or mDC was significantly higher than that in monocytes (P=0.005, P=0.002), and the expression of CYP27B1 in mDCs was significantly higher than that in iDCs (P=0.01). The expression of VDR in iDCs or mDCs was significantly lower than that in monocytes (P=0.01，P=0.003), while there was no significant difference in the expression of VDR between iDCs and mDCs (P=0.43). ③The expression of CYP27B1 in iDCs in treatment group was significantly higher than that in control group (P<0.01), and the expression of VDR in iDCs in treatment group was significantly lower than that in control group (P<0.01), while 1,25 (OH)2D3 did not have effect on the expression of CYP27B1 and VDR in mDCs (P>0.05). ④The early apoptosis rate of mDCs stimulated by rhTNF-α for 48 h in treatment group was significantly higher than that in control group (20.8% vs 9.23%, P<0.01), and the late apoptosis rate of mDCs stimulated by rhTNF-α for 72 h was significantly higher than that in control group (19.39% vs 7.27%，P<0.01). Conclusion 1,25 (OH)2D3 inhibits the differentiation and maturation of DCs derived from cord blood monocytes, and promotes the apoptosis of DCs derived from cord blood monocytes.

Key words: 1α,25-dihydroxyvitamin D3, dendritic cells, differentiation, maturation, apoptosis, cord blood