Influence of Human Papillomavirus E7 Oncoprotein on Maturation and Function of Plasmacytoid Dendritic Cells In Vitro

The major difficulties of human papillomavirus (HPV) treatment are its persistence and recurrence. The HPV E7 oncoprotein-loaded dendritic cells have been evaluated as cellular vaccine in previous reports. Plasmacytoid dendritic cells (pDCs) play an essential role of connecting the innate immune response and adaptive immune response in the immune system. But they function in HPV E7 loading is unclear. To investigate whether loading of the HPV type 6b, 11, and 16 E7 proteins affects the activity of pDCs, human peripheral blood-separated pDCs and mouse bone marrow-derived pDCs were pulsed with the HPV E7 proteins. The expression levels of CD40, CD80, CD86, and MHC II were significantly upregulated in pDCs upon HPV 6b/11 E7 protein pulse. The secretion and gene expression of type I IFN and IL-6 were both upregulated by HPV 6b/11 E7 proteins, more significant than HPV 16 E7 protein. The expression of essential factors of TLR signaling pathway and JNK/p38 MAP kinase signaling pathway were all increased in HPV 6b/11 E7 proteins pulsed pDCs. Our results suggest that HPV E7 proteins could promote the differentiation and maturation of pDCs and activate the TLR and MAPK pathway to induce host innate immune response. It might be conducive to explore novel immunotherapy targeting HPV infection with HPV E7 loaded pDC.