Co-delivery of CpG and antigen using hyaluronic acid bioconjugates-decorated nanoparticles to promote maturation and activation of dendritic cells

Objective To study the maturation and activation effects of hyaluronic acid (HA) modified polymer nanoparticles co-delivering adjuvants and antigens on mouse bone marrow dendritic cells (BMDCs). Methods HA-modified polylactic acid-glycolic acid copolymer (PLGA) and cationic lipid DOTAP were used as nanocarriers (DOTAP-PLGA) to co-deliver adjuvant CpG with model antigen ovalbumin (OVA). In the drug-loaded nanocarriers, CpG was covalently bound to the surface of HA, and OVA was physically blended into DOTAP-PLGA nanocarriers. The nanoparticles were characterized by transmission electron microscopy and dynamic light scattering. The in vitro release of CpG and OVA in the nanoparticles was investigated. The uptake and distribution of nanoparticles in mouse BMDCs were studied by flow cytometry and laser scanning confocal microscopy. The maturation and cytokine expression of mouse BMDCs were evaluated by flow cytometry and enzyme-linked immunosorbent assay, respectively. Results The CpG-HA-OVA-PLGA nanoparticles loading CpG and OVA were prepared. The average particle size was (305.1±2.2) nm and the polydispersity index was 0.203. A core-shell structure of the nanoparticles modified by HA was clearly observed by transmission electron microscopy. Cellular experiment results showed that CpG-HA-OVA-PLGA nanoparticles could be efficiently uptaken by mouse BMDCs, and promote lysosomal release of CpG and cytoplasmic delivery of antigen OVA. Compared with free OVA group and free OVA+CpG group, the CpG-HA-OVA-PLGA nanoparticles significantly up-regulated the expression of co-stimulatory molecules CD86 and CD40 (all P<0.01), major histocompatibility complex I (MHC-I) (P<0.01), and cytokine tumor necrosis factor-α (TNF-α) (P<0.01). Conclusions HA-modified CpG and OVA nanoparticle co-delivery vectors can effectively promote the maturation and activation of dendritic cells, which provides a basis for the development of novel vaccine vectors for the co-delivery of antigens and adjuvants. Key words: Nanoparticles; Co-delivery; CpG; Antigen; Dendritic cells