Adjuvant activities of CTAB-modified Polygonatum sibiricum polysaccharide cubosomes on immune responses to ovalbumin in mice

Recently, the cubosomes have been widely studied as drug carriers. It has been described that cubosomes could further stimulate the immune response after carrying the immune enhancer. Polygonatum sibiricum polysaccharide (PSP), one of the most important biologically active ingredients of Polygonatum sibiricum, has been reported as an immunostimulant to improve immune responses. This study was aimed to observe the immunomodulation effects of ovalbumin (OVA) absorbed cetyltrimethylammonium bromide-modified Polygonatum sibiricum polysaccharide cubosomes (CTAB-modified PSP-Cubs/OVA). Firstly, the antigen uptake of CTAB-modified PSP-Cubs/OVA by macrophages was determined in vitro. After that, mice were immunized with CTAB-modified PSP-Cubs/OVA. The activation of dendritic cells in lymph nodes, activation of lymphocyte, ratios of CD4+ to CD8+, the concentrations of OVA-specific IgG in serum and the cytokines concentrations were analyzed. As the results showed, CTAB-modified PSP-Cubs/OVA could promote the production of OVA-specific IgG in serum. The ratio of CD4+ to CD8+ in CTAB-modified PSP-Cubs/OVA group was significantly increased compared with other groups. CTAB-modified PSP-Cubs/OVA could significantly activate dendritic cells and promote lymphocyte proliferation. The results indicated that CTAB-modified PSP-Cubs/OVA could promote the secretion of related cytokines and the proliferation of lymphocytes, stimulate the cellular immune response and increase the level of humoral immunity. Above all, CTAB-modified PSP-Cubs had good adjuvant activity.