Lnc-DC regulates cellular turnover and the HBV-induced immune response by TLR9/STAT3 signaling in dendritic cells

BACKGROUND: Lnc-DC is a specific group of long non-coding (Lnc) RNAs in dendritic cells (DCs). Its function has been previously studied, and includes roles in dendritic cell differentiation and the progression of some diseases. In this study, we observed the critical role of Lnc-DC in regulating the differentiation, growth, and apoptosis of dendritic cells. METHODS: We first isolated peripheral blood mononuclear cells to culture and induce into DCs, which were then co-cultured with hepatitis B virus (HBV)-secreting HepG2.2.15 cells for the detection of changes in Lnc-DC. The expression levels of TLR9, p-STAT3, and SOCS3 were tested with qPCR and western blot. MTT assays were used to analyze the cell proliferation, cell cycle, and apoptosis. We used ELISA to test the expression of TNF-α, IL-1β, IL-6, IL-12p40, and IFN-γ. RESULTS: Co-culture with HBV-secreting HepG2.2.15 cells increased the level of Lnc-DC and activated TLR9/STAT3 signaling. The HBV DNA level (IU/ml) was positively correlated with levels of Lnc-DC and TLR9, further demonstrating that Lnc-DC was associated with the immune response of HBV. Lnc-DC was shown to regulate TLR9/STAT3 signaling in dendritic cells. More interestingly, the regulation of Lnc-DC controlled the immune response by reducing the concentration of secreted TNF-α, IL-6, IL-12, and IFN-γ, as well as increasing the IL-1β concentration in dendritic cells. CONCLUSION: Lnc-DC is important in regulating the growth, apoptosis, and immune response of dendritic cells mediated by TLR9/STAT3 signaling, and was also activated by HBV. This study provides a previously unidentified mechanism underlying the immune response in dendritic cells.