Bacillus Calmette-Guerin vaccine promotes human dendritic cell miRNA-99b to regulate CD4 +initial T cells differentiation to Th17/Treg imbalance / 中华临床感染病杂志

ABSTRACT

Objective To investigate the effects of human dendritic cells ( DCs) infected by bovine Mycobacterium tuberculosis attenuated live bacteria ( BCG) on differentiation of CD4 +naive T cells from neonate cord blood .Methods After infected with BCG , human DCs were cultured with CD 4 +naive T cells from neonate cord blood, the expression of miRNA-99b in DCs and the expression of Foxp3, ROR-γt, IFN-γand IL-10 mRNAs in CD4+ T cells were detected by qRT-PCR.DCs were transfected with miRNA-99b antisense oligonucleotides and co-cultured with neonatal cord blood CD 4 +naive T cells , and the transcription level of CD4 +T cell-related genes was detected .SPSS 15.0 was used to analyze the data .Results The transcriptional activity of miRNA-99b gene in BCG-infected DCs was significantly higher than that in uninfected DCs (t=7.06,P<0.01).Compared with CD4 +T cells co-cultured with uninfected DCs, the mRNA expression of IFN-γ(45.61 ±4.46 vs.3.54 ±1.73, t=32.32, P<0.01), IL-10 (4.17 ±1.06 vs.1.26 ±0.67, t=2.24, P<0.05) in CD4 +T cells co-cultured with BCG-infected DCs was significantly increased, while the mRNA expression of ROR-γt was significantly decreased ( 0.08 ±0.02 vs.0.63 ± 0.10, t=0.42, P<0.01).Compared with CD4 +T cells co-cultured with DCs transfected with NC-siRNA, the miRNA-99b expression was blocked , the mRNA expression of Foxp3 (0.12 ±0.01 vs.1.57 ±0.90, t=1.06, P<0.05), IFN-γ(0.03 ±0.01 vs.0.64 ±0.35, t =0.44, P<0.05), IL-10(0.03 ±0.01 vs. 0.76 ±0.09, t=0.54,P<0.01) in CD4 +T cells was significantly decreased , while the expression ROR-γt mRNA was significantly increased (17.03 ±5.51 vs.1.32 ±0.14, t=11.54,P<0.01).Conclusion BCG induces the imbalance of initial CD 4 +T lymphocytes into Th17/Treg by regulating the expression of miRNA-99b in DCs, leading to the occurrence and development of infection .