Controlled analysis of nanoparticle charge on mucosal and systemic antibody responses following pulmonary immunization

Abstract

Pulmonary immunization enhances local humoral and cell-mediated mucosal protection, which are critical for vaccination against lung-specific pathogens such as influenza or tuberculosis. A variety of nanoparticle (NP) formulations have been tested preclinically for pulmonary vaccine development, yet the role of NP surface charge on downstream immune responses remains poorly understood. We used the Particle Replication in Non-Wetting Templates (PRINT) process to synthesize hydrogel NPs that varied only in surface charge and otherwise maintained constant size, shape, and antigen loading. Pulmonary immunization with ovalbumin (OVA)-conjugated cationic NPs led to enhanced systemic and lung antibody titers compared with anionic NPs. Increased antibody production correlated with robust germinal center B-cell expansion and increased activated CD4(+) T-cell populations in lung draining lymph nodes. Ex vivo treatment of dendritic cells (DCs) with OVA-conjugated cationic NPs induced robust antigen-specific T-cell proliferation with ∼ 100-fold more potency than soluble OVA alone. Enhanced T-cell expansion correlated with increased expression of surface MHCII, T-cell coactivating receptors, and key cytokines/chemokine expression by DCs treated with cationic NPs, which were not observed with anionic NPs or soluble OVA. Together, these studies highlight the importance of NP surface charge when designing pulmonary vaccines, and our findings support the notion that cationic NP platforms engender potent humoral and mucosal immune responses.

Harnessing Nanoparticles for Immune Modulation

“…For instance, relative to anionic particles, cationic NPs appear to be taken up more readily via clathrin-mediated processes [21]. Furthermore, positively charged antigen-loaded NPs are significantly more effective at stimulating Th1 responses after either intradermal or mucosal (pulmonary) inoculation, whereas anionic particles stimulate T and B cell responses poorly under similar conditions [22,23]. The ability of cationic particles to stimulate Th1 responses has been associated with preferential DC uptake of such particles and the propensity of cationic particles to regulate positive costimulatory molecules [24].…”

Nanoparticle surface charge impacts distribution, uptake and lymph node trafficking by pulmonary antigen-presenting cells

“…These formulations follow design principles of pathogen mimicry, as the majority of both bacteria and viruses have surfaces with acidic isoelectric points (26, 27). However, recent work from our group has demonstrated that pulmonary vaccination with cationic NPs can enhance local and systemic antibody production to a model antigen, as compared to otherwise equivalent anionic NPs (8). While these results indicate that nanoparticle charge is a key variable to immune responses in the lung, the underlying cellular mechanisms responsible for this deviation in immune response remain unclear.…”

“…The next generation of vaccines can be achieved by pulmonary delivery of precision-engineered particles (1-8). Engineered micro- and nanoparticles (NP) offer elegant solutions for pathogen mimicry, while providing increased safety and efficacy over current vaccine strategies (2, 3, 6).…”

“…Engineered micro- and nanoparticles (NP) offer elegant solutions for pathogen mimicry, while providing increased safety and efficacy over current vaccine strategies (2, 3, 6). Additionally, engineered particles can be designed such that aerosol properties, lung deposition, and cellular interactions are independently taken into consideration (1, 2, 8, 9). While there is extensive literature describing how physical particle properties can influence aerodynamic diameter and thus pulmonary deposition, there is minimal understanding of how these same particle properties influence interactions with lung cells and their subsequent immune responses (1, 9).…”

Modulating the immune system through nanotechnology

“…Therefore, a way to passively target DCs is through the reduction of the nanocarriers’ size. On the other hand, it is also known that providing nanocarriers with a positive surface charge enhances the chances for them to interact with DCs and macrophages [75,79,101–103]. Nevertheless, irrespective of the influence of size and surface charge in the specific uptake of particles by dendritic cells, it seems clear that the most effective approach to precisely target DCs would be providing the nanocarriers with specific targeting ligands (Table 2B) [104].…”