Preparation and characterization of curdlan-chitosan conjugate nanoparticles as mucosal adjuvants for intranasal influenza H1N1 subunit vaccine.

Intranasal vaccination offers crucial protection against influenza virus pandemics. However, antigens, especially subunit antigens, often fail to induce effective immune responses without the help of immune adjuvants. Our research has demonstrated that a polyelectrolyte complex, composed of curdlan sulfate/O-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (CS/O-HTCC), effectively triggers both mucosal and systemic immune responses when administrated intranasal. In this study, stable nanoparticles formed by curdlan-O-HTCC conjugate (CO NP) were prepared and characterized. Furthermore, the efficacy of CO NP was evaluated as a mucosal adjuvant in an intranasal influenza H1N1 subunit vaccine. The results revealed that CO NP exhibits uniform and spherical morphology, with a size of 190.53 ± 4.22 nm, and notably, it remains stable in PBS at 4 °C for up to 6 weeks. Biological evaluation demonstrated that CO NP stimulates the activation of antigen-presenting cells (APCs), including macrophages and dendritic cells (DCs), both in vitro and in vivo. Furthermore, intranasal administration of CO NP effectively elicits cellular and humoral immune responses, notably enhancing mucosal immunity. Thus, CO NP emerges as a promising mucosal adjuvant for influenza subunit vaccines.

Jiang H ，Zhang S ，Chen Y ，Wang F ，Jiang W ... -  《-》

Preparation and immunological activity evaluation of an intranasal protein subunit vaccine against ancestral and mutant SARS-CoV-2 with curdlan sulfate/O-linked quaternized chitosan nanoparticles as carrier and adjuvant.

Chitosan and its derivatives are ideal nasal vaccine adjuvant to deliver antigens to immune cells. Previously, we successfully used a chitosan derivative, O-(2-Hydroxyl) propyl-3-trimethyl ammonium chitosan chloride (O-HTCC), and a β-glucan derivative, curdlan sulfate (CS), to prepare a nanoparticle adjuvant CS/O-HTCC which could deliver ovalbumin to antigen presenting cells (APCs) through nasal inhalation. In this article, we used SARS-CoV-2 spike receptor binding domain (S-RBD) as the antigen and CS/O-HTCC nanoparticles as the adjuvant to develop a nasal mucosal protein subunit vaccine, CS/S-RBD/O-HTCC. The humoral immunity, cell-mediated immunity and mucosal immunity induced by vaccines were evaluated. The results showed that CS/S-RBD/O-HTCC could induce desirable immunization with single or bivalent antigen through nasal inoculation, giving one booster vaccination with mutated S-RBD (beta) could bring about a broad cross reaction with ancestral and different mutated S-RBD, and vaccination of the BALB/c mice with CS/S-RBD/O-HTCC containing S-RBD mix antigens (ancestral and omicron) could induce the production of binding and neutralizing antibodies against both of the two antigens. Our results indicate that CS/O-HTCC is a promising nasal mucosal adjuvant to prepare protein subunit vaccine for both primary and booster immunization, and the adjuvant is suitable for loading more than one antigen for preparing multivalent vaccines.

Chen Y ，Wang Y ，Li Z ，Jiang H ，Pan W ，Liu M ，Jiang W ，Zhang X ，Wang F ... -  《-》

Curdlan sulfate-O-linked quaternized chitosan nanoparticles: potential adjuvants to improve the immunogenicity of exogenous antigens via intranasal vaccination.

Zhang S ，Huang S ，Lu L ，Song X ，Li P ，Wang F ... -  《International Journal of Nanomedicine》

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

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.

Zhang S ，Jiang H ，Huang S ，Li P ，Wang F ... -  《-》

Development and characterization of chitosan coated poly-(ɛ-caprolactone) nanoparticulate system for effective immunization against influenza.

In this study surface coated poly-(ɛ-caprolactone) (PCL) nanoparticles with chitosan (CS) were developed as a carrier system for nasal immunization using recombinant Influenza A virus (A/California/07/2009) H1N1 hemagglutinin (HA) protein, for the induction of humoral, cellular and mucosal immunity. CS coated PCL (CS-PCL) nanoparticles were characterized in vitro for their percent yield, size, shape, entrapment efficiency, loading capacity and zeta potential. The in vitro release and antigen integrity were also evaluated. Particles were prepared by an emulsion-diffusion-solvent evaporation method. The coated cationic nanoparticles of average size 125.64±6.51 nm with a narrow size distribution (pdi: 0.185±0.032) and a positive surface charge (+22.88 mV) were obtained. HA antigen was efficiently entrapped in CS-PCL nanoparticles (entrapment efficiency 74.84±4.51%, loading capacity 14±2% (w/w)). The molecular weight and antigenicity of the entrapped HA was maintained as shown by polyacrylamide gel electrophoresis and Western blotting, respectively. In vitro release study of antigen showed that about 66.47% of entrapped antigen was released within 63 days. The immune-stimulating activity was studied by measuring hemagglutination inhibition (HAI) titer, IgG, IgG1 and IgG2a titer, secretory IgA level in nasal and lung lavage (mucosal secretions) following nasal administration of modified CS-PCL nanoparticles in Balb/c mice and compared with soluble HA antigen administered intramuscular (IM) and with PCL (uncoated) nanoparticles administered intranasal (IN). The numbers of IFN-γ or IL-4 secreting cells in spleen homogenates were also measured 21 day after third immunization. Single IN or IM immunization with antigen-loaded CS-PCL nanoparticles resulted in strong HAI and total IgG responses. These responses were higher than those achieved after booster IM administration of the subunit antigen, whereas the IgG1/IgG2a profile did not change substantially. The IN administered antigen-CS-PCL nanoparticles induced higher immune responses compared to the other IN antigen formulations, and these responses were enhanced by IN booster vaccinations. Moreover, IM administered soluble HA antigen did not elicit s-IgA in mucosal secretions as it was induced and measured in the case of nasal administration of CS-PCL nanoparticles. In contrast to IM administered antigen CS-PCL nanoparticles induced a balanced Th1 and Th2 response. CS-PCL nanoparticles (cationic nanoparticles) thus produced humoral (both systemic and mucosal) and cellular immune responses upon nasal administration. These findings demonstrate high potential of CS-PCL nanoparticles for their use as a carrier adjuvant for nasal administered influenza antigens.

Gupta NK ，Tomar P ，Sharma V ，Dixit VK ... -  《-》