Adverse Effect of Nano-Silicon Dioxide on Lung Function of Rats with or without Ovalbumin Immunization

Abstract

BackgroundThe great advances of nanomaterials have brought out broad important applications, but their possible nanotoxicity and risks have not been fully understood. It is confirmed that exposure of environmental particulate matter (PM), especially ultrafine PM, are responsible for many lung function impairment and exacerbation of pre-existing lung diseases. However, the adverse effect of nanoparticles on allergic asthma is seldom investigated and the mechanism remains undefined. For the first time, this work investigates the relationship between allergic asthma and nanosized silicon dioxide (nano-SiO2).Methodology/Principal FindingsOvalbumin (OVA)-treated and saline-treated control rats were daily intratracheally administered 0.1 ml of 0, 40 and 80 µg/ml nano-SiO2 solutions, respectively for 30 days. Increased nano-SiO2 exposure results in adverse changes on inspiratory and expiratory resistance (Ri and Re), but shows insignificant effect on rat lung dynamic compliance (Cldyn). Lung histological observation reveals obvious airway remodeling in 80 µg/ml nano-SiO2-introduced saline and OVA groups, but the latter is worse. Additionally, increased nano-SiO2 exposure also leads to more severe inflammation. With increasing nano-SiO2 exposure, IL-4 in lung homogenate increases and IFN-γ shows a reverse but insignificant change. Moreover, at a same nano-SiO2 exposure concentration, OVA-treated rats exhibit higher (significant) IL-4 and lower (not significant) IFN-γ compared with the saline-treated rats. The percentages of eosinophil display an unexpected result, in which higher exposure results lower eosinophil percentages.Conclusions/SignificanceThis was a preliminary study which for the first time involved the effect of nano-SiO2 to OVA induced rat asthma model. The results suggested that intratracheal administration of nano-SiO2 could lead to the airway hyperresponsiveness (AHR) and the airway remolding with or without OVA immunization. This occurrence may be due to the Th1/Th2 cytokine imbalance accelerated by the nano-SiO2 through increasing the tissue IL-4 production.

Surface modifications of silica nanoparticles are crucial for their inert versus proinflammatory and immunomodulatory properties

“…19,20,26 Our results showed sig nificant immunomodulatory effects exerted by SiO 2 NPs in OVAsensitized mice, with a significant increase in BALF inflammatory infiltrate, mainly comprising macrophages and eosinophils. Our data are in line with a previous study testing titanium dioxide and gold NPs in the elicitation phase of the allergic response.…”

“…The reason for this choice was that this time point is representative for the elicitation phase of the aller gic response in our mouse model, since it is characterized by strong recruitment of inflammatory cells into the lung. 27 Since the Th2adjuvant effects of SiO 2 NPs applied during the sensitization phase have been previously demonstrated, 19,20 we now can assume that SiO 2 NPs also exacerbate the elicitation phase of allergic airway inflammation. SiO 2 NPs showed a strong proinflammatory effect in NS mice, leading to neutrophil and lymphocyte recruitment after intratracheal instillation, which is in agreement with a previous work 16 showing neutrophil recruitment in the early inflammation stages (up to 1 week after instillation) following intratracheal instillation of SiO 2 NPs.…”

“…[16][17][18] Immunomodulatory effects by particle exposure during the sensitization phase have also been demonstrated. 19,20 Recently, surface modifications of SiO 2 NPs were synthe sized to study their influence on the biological activity of SiO 2 NPs. In vitro studies using various mammalian cells have demonstrated that unmodified SiO 2 NPs exhibit higher cytotoxic and genotoxic properties compared to surface modified NPs.…”

Enhanced bioavailability and efficiency of curcumin for the treatment of asthma by its formulation in solid lipid nanoparticles

“…The airway responsiveness was one of the most important clinical discoveries in asthma studies. 29 The methacholine challenge was a useful tool in diagnosis of allergic respiratory disorders, which had been widely used in assessing airway responsiveness. 45 In the present study, OVA sensitization and challenge evoked a significant hyperresponsiveness to methacholine challenge in sensitized rats.…”

“…29 These cells induced immunoglobulin E production and airway inflammation by producing Th2 cytokines, such as IL-4, IL-5, and IL-13. 30 In this work, we examined whether curcumin-SLNs suppressed the expression and secretion of Th2 cytokines more efficiently than curcumin.…”