Use of the Microparticle Nanoscale Silicon Dioxide as an Adjuvant To Boost Vaccine Immune Responses against Influenza Virus in Neonatal Mice

Abstract

Neonates are at a high risk of infection, but vaccines are less effective in this age group; tailored adjuvants could potentially improve vaccine efficacy. Increased understanding about danger sensing by the innate immune system has led to the rational design of novel adjuvants. But differences in the neonatal innate immune response, for example, to Toll-like receptor (TLR) agonists, can reduce the efficacy of these adjuvants in early life. We therefore targeted alternative danger-sensing pathways, focusing on a range of compounds described as inflammasome agonists, including nanoscale silicon dioxide (NanoSiO2), calcium pyrophosphate dihydrate (CPPD) crystals, and muramyl tripeptide (M-Tri-DAP), for their ability to act as adjuvants. In vitro, these compounds induced an interleukin 1-beta (IL-1␤) response in the macrophage-like cell line THP1. In vivo, adult CB6F1 female mice were immunized intramuscularly with H1N1 influenza vaccine antigens in combination with NanoSiO2, CPPD, or M-Tri-DAP and subsequently challenged with H1N1 influenza virus (A/England/195/2009). The adjuvants boosted anti-hemagglutinin IgG and IgA antibody levels. Both adult and neonatal animals that received NanoSiO2-adjuvanted vaccines lost significantly less weight and recovered earlier after infection than control animals treated with antigen alone. Administration of the adjuvants led to an influx of activated inflammatory cells into the muscle but to little systemic inflammation measured by serum cytokine levels. Blocking IL-1␤ or caspase 1 in vivo had little effect on NanoSiO2 adjuvant function, suggesting that it may work through pathways other than the inflammasome. Here we demonstrate that NanoSiO2 can act as an adjuvant and is effective in early life. IMPORTANCEVaccines can fail to protect the most at-risk populations, including the very young, the elderly, and the immunocompromised. There is a gap in neonatal immunity between the waning of maternal protection and routine infant immunization schedules, exacerbated by the failure of vaccines to work in the first months of life. One approach is to design age-specific formulations, with more-effective adjuvants, based on our understanding of the nature of the neonatal immune response. We chose to target the inflammasome, a molecular complex capable of detecting infection and cell damage and of triggering IL-1␤-driven inflammation. We screened a range of compounds in vitro and in vivo and identified three lead candidates: NanoSiO2, CPPD, and MTri-DAP. Of these, NanoSiO2 was the most effective and boosted the anti-influenza virus response in both adult and neonatal mice. This finding is important for the development of age-specific vaccines, designed using our knowledge of the neonatal immune response. Infants bear the brunt of mortality and morbidity from infectious diseases, with 36% of the annual 3.3 million deaths in newborn children caused by infections (1). Influenza virus infection is especially prevalent in early life, with high rates of hospitalization (50 to 100 cases ...

Inflammatory responses to influenza vaccination at the extremes of age

“…Antibodies (IgG) specific to influenza H1N1 in the sera were measured using a standardized ELISA . Briefly, MaxiSorp 96‐well plates (Nunc, Roskilde, Denmark) were coated with 1 μg/ml surface proteins or a combination of anti‐murine λ and κ light‐chain‐specific antibodies (AbDSerotec, Oxford, UK) and incubated overnight at 4°.…”

“…Another study using CpG as an experimental adjuvant has also shown reduced effect of the adjuvant in aged mice . Based on our previous studies, we know that antibody is a critical correlate of protection in mouse models of influenza . But we have recently confirmed the role of CD8 T cells in the resolution of influenza infection, and there are known age‐dependent effects on T cells, so targeting T cells may be more effective in the elderly; for example a peptide vaccine coupled to flagellin that induced T cells was protective in aged mice.…”

“…Our data support the idea that the neonatal response is different not deficient, with higher IL‐1 α , CRP, GM‐CSF, G‐CSF and MCP‐1 than other ages of mice. We and others have previously investigated adjuvants specifically for use in early life and have shown that MF59 is protective even after a single dose…”

Mouse Models of Influenza Infection with Circulating Strains to Test Seasonal Vaccine Efficacy

“…While we didnot dissect the correlates of protection in the current study, in other studies the strongest correlate protection is IgG and we observed that immunization induced an influenza-specific IgG response. In addition to IgG, we have recently observed a role for IgA in both human ( 24 ) and mouse ( 28 ) challenge studies.…”

Evaluation of different chemical adjuvants on an avian influenza H6 DNA vaccine in chickens

“…Recently, nanoparticles have been used as adjuvants for enhancing the immunogenicity of protein-based influenza vaccines in mice (Petukhova et al 2013;Neuhaus et al, 2014;Ross et al, 2014;Russell et al, 2016) and chickens (Asl Najjari et al, 2015;Khalili et al, 2015). Sliver nanoparticles with polyethylene glycol were also used to formulate plasmid DNA encoding H5N1 influenza virus hemagglutinin (HA) gene to assess humoral and cellular immune responses in chickens (Jazayeri, et al, 2012).…”