Curdlan sulfate/O-linked quaternized chitosan nanoparticles acting as potential adjuvants promote multiple arms of immune responses.

Highlights • Nanoparticles enter macrophages and escape from lysosomes effectively. • Nanoparticles upregulate phenotypic and functional maturation of dendritic cells. • Nanoparticles induce activation of type Ⅰ interferons in dendritic cells. • Nanoparticles promote production of cytokines in immunocytes. • Nanoparticles induce lymphocytes proliferation. Abstract Nasal immunization to prevent and treat diseases caused by infection through the respiratory tract cannot be actualized because of the lack of effective adjuvants. We have proven that compared with antigens loaded on CS or O -HTCC alone in nasal vaccination, antigens loaded on the nanoparticles of curdlan sulfate/ O -(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (CS/ O -HTCC) can induce stronger systemic and mucosal immune responses. In this study, we evaluated the immunostimulatory activity and mechanisms of CS/ O -HTCC nanoparticles. The results showed that CS/ O -HTCC nanoparticles can improve the activation of antigen-presenting cells, upregulate the production of inflammatory factors and cytokines, induce cross-presentation, and simultaneously activate type I interferon-related genes. CS/ O -HTCC nanoparticles also activated the PI3K/AKT and MAPK pathways and significantly promoted IL-2 transcription to induce the proliferation of lymphocytes. The results revealed that CS/ O- HTCC nanoparticles as a type of multifunctional adjuvant can improve multiple arms of immune responses. [ABSTRACT FROM AUTHOR]