Functional Testing of an Inhalable Nanoparticle Based Influenza Vaccine Using a Human Precision Cut Lung Slice Technique

Abstract

Annual outbreaks of influenza infections, caused by new influenza virus subtypes and high incidences of zoonosis, make seasonal influenza one of the most unpredictable and serious health threats worldwide. Currently available vaccines, though the main prevention strategy, can neither efficiently be adapted to new circulating virus subtypes nor provide high amounts to meet the global demand fast enough. New influenza vaccines quickly adapted to current virus strains are needed. In the present study we investigated the local toxicity and capacity of a new inhalable influenza vaccine to induce an antigen-specific recall response at the site of virus entry in human precision-cut lung slices (PCLS). This new vaccine combines recombinant H1N1 influenza hemagglutinin (HAC1), produced in tobacco plants, and a silica nanoparticle (NP)-based drug delivery system. We found no local cellular toxicity of the vaccine within applicable concentrations. However higher concentrations of NP (≥103 µg/ml) dose-dependently decreased viability of human PCLS. Furthermore NP, not the protein, provoked a dose-dependent induction of TNF-α and IL-1β, indicating adjuvant properties of silica. In contrast, we found an antigen-specific induction of the T cell proliferation and differentiation cytokine, IL-2, compared to baseline level (152±49 pg/mg vs. 22±5 pg/mg), which could not be seen for the NP alone. Additionally, treatment with 10 µg/ml HAC1 caused a 6-times higher secretion of IFN-γ compared to baseline (602±307 pg/mg vs. 97±51 pg/mg). This antigen-induced IFN-γ secretion was further boosted by the adjuvant effect of silica NP for the formulated vaccine to a 12-fold increase (97±51 pg/mg vs. 1226±535 pg/mg). Thus we were able to show that the plant-produced vaccine induced an adequate innate immune response and re-activated an established antigen-specific T cell response within a non-toxic range in human PCLS at the site of virus entry.

Evaluation of inflammatory and immune responses in long-term cultured human precision-cut lung slices

“…These processes are characterized by activation or suppression of certain mediators, which can be used as tools for evaluation of immune modulating effects of target products. 13,[16][17][18] In the current study, we characterize a human PCLS cultivation system that was established to assess the ability of human PCLS to develop inflammatory and immune responses to antigen stimulation. Results demonstrated that PCLS remained viable, structurally intact and able to elicit functional responses up to 14 d in culture.…”

Murine precision-cut lung slices exhibit acute responses following exposure to gasoline direct injection engine emissions

“…Comparison of the airway responses across ex vivo and in vivo exposure models suggests similar trends: diesel engine exhaust was found to induce increased protein expression of the pro-inflammatory marker TNFα in both PCLS prepared from rat lung tissue exposed at an air-liquid interface and in lavage samples collected from rat lungs following inhalation exposure (Morin et al, 2008). Studies have reported increased protein expression of TNFα in response to particulate pollutants, such as engineered silica nanoparticles (Neuhaus et al, 2013), cigarette smoke (Lauenstein et al, 2012) and diesel engine exhaust particulate matter (Bion et al, 2002).…”

“…The use of PCLS to measure inflammatory and immune responses induced by pollutants has also been well documented (Henjakovic et al, 2008). Previous studies have evaluated the pulmonary effects of particulate matter (Lauenstein et al, 2014;Neuhaus et al, 2013;Horev-Azaria et al, 2013) and gaseous (Switalla et al, 2010;Bion et al, 2002) pollutant exposure using PCLS maintained in a submerged or in an air-liquid interface tissue culture environment. Comparison of the airway responses across ex vivo and in vivo exposure models suggests similar trends: diesel engine exhaust was found to induce increased protein expression of the pro-inflammatory marker TNFα in both PCLS prepared from rat lung tissue exposed at an air-liquid interface and in lavage samples collected from rat lungs following inhalation exposure (Morin et al, 2008).…”

Preclinical safety and efficacy models for pulmonary drug delivery of antimicrobials with focus on in vitro models

“…Both approaches have been described for amphibian and mammalian lungs including humans. In contrast to in vitro models, they preserve the in vivo structure and include all cell types [18][19][20].…”