Pulmonary effects of inhalation of spark-generated silver nanoparticles in Brown-Norway and Sprague–Dawley rats

Abstract

BackgroundThe increasing use of silver nanoparticles (AgNPs) in consumer products is concerning. We examined the potential toxic effects when inhaled in Brown-Norway (BN) rats with a pre-inflammatory state compared to Sprague–Dawley (SD) rats.MethodsWe determined the effect of AgNPs generated from a spark generator (mass concentration: 600–800 μg/mm3; mean diameter: 13–16 nm; total lung doses: 8 [Low] and 26–28 [High] μg) inhaled by the nasal route in both rat strains. Rats were sacrificed at day 1 and day 7 after exposure and measurement of lung function.ResultsIn both strains, there was an increase in neutrophils in bronchoalveolar lavage (BAL) fluid at 24 h at the high dose, with concomitant eosinophilia in BN rats. While BAL inflammatory cells were mostly normalised by Day 7, lung inflammation scores remained increased although not the tissue eosinophil scores. Total protein levels were elevated at both lung doses in both strains. There was an increase in BAL IL-1β, KC, IL-17, CCL2 and CCL3 levels in both strains at Day 1, mostly at high dose. Phospholipid levels were increased at the high dose in SD rats at Day 1 and 7, while in BN rats, this was only seen at Day 1; surfactant protein D levels decreased at day 7 at the high dose in SD rats, but was increased at Day 1 at the low dose in BN rats. There was a transient increase in central airway resistance and in tissue elastance in BN rats at Day 1 but not in SD rats. Positive silver-staining was seen particularly in lung tissue macrophages in a dose and time-dependent response in both strains, maximal by day 7. Lung silver levels were relatively higher in BN rat and present at day 7 in both strains.ConclusionsPresence of cellular inflammation and increasing silver-positive macrophages in lungs at day 7, associated with significant levels of lung silver indicate that lung toxicity is persistent even with the absence of airway luminal inflammation at that time-point. The higher levels and persistence of lung silver in BN rats may be due to the pre-existing inflammatory state of the lungs.

CEffect of Silver Nanoparticles Versus Titanium Dioxide Nanoparticles on the Lung of Adult Male Albino Rats: A histological and immunohistochemical study

“…Whereas, ultra-structural examination of TiO2-Nps group revealed pneumocyte type II with empty lamellar bodies and microvilli on its surface. Multiple red blood cells are detected in the alveolar space; these results were in agreement with other researchers [52] .…”

“…In agreement with previous authors [52] , thickened vessel wall with marked cellular infiltration were observed in the Ag-Nps injected lung. They proved that Ag-Nps induced pulmonary neutrophilic inflammation with the production of proinflammatory and pro-neutrophilic cytokines.…”

Current state of knowledge on the health effects of engineered nanomaterials in workers: a systematic review of human studies and epidemiological investigations

“…Concerning animal investigations, toxicity in the lungs, including inflammatory reactions and histopathological alterations (149)(150)(151)(152)(153)(154)(155)(156)(157)(158) were reported to be responsible for pulmonary functionality alterations (155,159) or allergic responses (160): however, other investigations have failed to detect hematological effects, systemic alterations, and pulmonary function test changes after Ag-ENM exposure (161,162). Histopathological changes in the kidney and liver (bile duct hyperplasia and necrosis) were identified after inhalation exposures, such as extra-pulmonary effects (155,158,159).…”

Silver Nanoparticles in the Lung: Toxic Effects and Focal Accumulation of Silver in Remote Organs

“…However, as Ag-NP can also occur as airborne dust, e.g., during nanoparticle (NP) fabrication processes, well-adapted occupational exposure levels are necessary, as well, and have been recently suggested [ 2 ]. These considerations are based on inhalation and instillation studies conducted with Ag-NP of different sizes and surface coatings [ 8 , 9 ]. These studies show that Ag-NP in the lung exhibit a high inflammatory potential and can lead to granulomatous lesions.…”