Interaction between bone marrow-derived dendritic cells and miR-21 of tubular renal epithelial cells under hypoxia

OBJECTIVE: To investigate the intracellular response and role of microRNA 21 in the regulation of dendritic cell maturation and function. MATERIALS AND METHODS: Bone marrow-derived DCs (BMDCs) isolated from male C57BL/6J mice and primary renal tubular epithelial cells were used as primary cells to perform this study. Flow cytometry was used to determine BMDCs and analyze the apoptosis effect. Transmission electron microscopy was used for the identification of the diameter of exosomes. Reverse transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting were used to detect the effect after cells were transfected with oligo. ELISA was used to determine the tumor necrosis factor-alpha (TNF-alpha). interleukin-12 (IL-12). and IL-1beta in DC supernatants. RESULTS: We found that the upregulation of microRNA 21 in dendritic cells induced by physical hypoxia contributed to decreased expressions of CD80 (cluster of differentiation 80). CD86 (cluster of differentiation 86), and MHCII (major histocompatibility complex class II molecules) of dendritic cells and suppressed secretion of inflammatory cytokines and chemokine receptor type 7. Co-culture with tubular epithelial cells or hypoxia-pretreated tubular epithelial cell-derived conditional medium promoted bone marrow-derived dendritic cell maturation. Exosomes purified from the supernatant of cultured marrow-derived dendritic cells showed upregulated microRNA 21 under hypoxia, whereas anti-microRNA 21 treated tubular epithelial cells promoted co-cultured marrow-derived dendritic cell maturation. CONCLUSIONS: Both oxygen concentration and tubular epithelial cells participate in regulating dendritic cell maturation, directly or indirectly through the microRNA 21 signal pathway.