Abstract
BackgroundSilica nanoparticles (SNPs) can easily enter in respiratory system via inhalation because of their low molecular weight and ease of dispersion. Toxicity and adverse effects of SNPs vary according to the physical characteristics of the particle.MethodsTo evaluate the toxic and adjuvant effects of 3 types of SNPs in the airway system, six-week-old female BALB/c mice were intranasally administered 3 types of SNPs (spherical [S-SNP], mesoporous [M-SNP], and polyethylene glycol-conjugated [P-SNP]) alone or SNPs/ovalbumin (OVA), three times weekly for 2 weeks. Airway hyper-responsiveness (AHR), bronchoalveolar lavage fluid (BALF), cytokine levels, and histology of the lungs were analyzed.ResultsThe S-SNPs/OVA group and M-SNPs/OVA group showed significant AHR, compared to the control group. Among all SNP-treated groups, the group administered SNPs/OVA showed greater inflammatory cell infiltration in BALF, extensive pathological changes, and higher cytokine levels (IL-5, IL-13, IL-1β, and IFN-γ) than those administered SNPs alone or saline/OVA.ConclusionExposure to SNPs alone and SNPs/OVA induced toxicity in the respiratory system. SNPs alone showed significant toxic effects on the airway system. Meanwhile, SNPs/OVA exerted adjuvant effects to OVA of inducing allergic airway inflammation. In particular, M-SNPs showed the most severe airway inflammation in both direct toxicity and adjuvant effect assays. P-SNPs induced less inflammation than the other types of SNPs in both models.
Highlights
Silica nanoparticles (SNPs) can enter in respiratory system via inhalation because of their low molecular weight and ease of dispersion
The mesoporous silica nanoparticles (M-silica nanoparticles (SNPs)) were globular in shape with multiple pores in each particle, compared to spherical silica nanoparticles (S-SNPs) which had no pores (Fig. 1a–c)
P-SNPs would aggregate after being diluted in saline, and P-SNP aggregates had significantly larger sizes, compared to other SNPs
Summary
Silica nanoparticles (SNPs) can enter in respiratory system via inhalation because of their low molecular weight and ease of dispersion. The prevalence of asthma has been rising recently in urban centers within industrialization regions of Africa, Latin America and Asia [11] This increase in the prevalence of asthma is thought to be induced by environmental contributors such as air pollutants and nanomaterials [12, 13]. Due to their small size, SNPs can enter the respiratory system via inhalation. Exposure to SNPs in manufacturing, managing, and packing through the use and discarding of SNPs may aggravate respiratory diseases, such as asthma, allergic rhinitis, and bronchitis [14] It is not well known whether SNPs exacerbate asthma in asthmatic mouse model or induce adjuvant effects. We aimed to evaluate the toxic and adjuvant effects of three types of SNPs in the mouse airway system
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