Evaluation of Recovery From Acute Lung Injury Induced by Intratracheal Instillation of Zinc Oxide Nanoparticles

Abstract

Abstract. Zinc oxide nanoparticles (ZnO-NPs) can potentially cause adverse health effects because they are highly soluble and widely used. We evaluated the effect of ZnO-NPs in rat lung. ZnO-NPs were administered via intratracheal instillation to Sprague Dawley rats at three different dosages (1, 5, and 10 mg/kg body weight). Macrophage numbers, total cell count, and total protein concentrations in bronchoalveolar lavage fluid (BALF) highly increased at day 1 in a dose-dependent manner relative to those in the control. Macrophage numbers and total protein concentrations were still elevated at day 14 relative to baseline, whereas total cell number continued to increase. These results indicate that inflammation had not fully resolved by day 14 in rat lungs. Furthermore, a significant increase in IL-6 (but not TNF-α) was observed in 5 and 10 mg/kg dose groups at day 1, which was likely caused by a ZnO-NP-treatment-induced increase in polymorphonuclear leukocytes. Histological examination indicated that multifocal acute inflammation occurred in the ZnO-NP-treated groups and progressed to chronic inflammation by day 14. A partial recovery of lung injury was observed within 14 days after exposure. In conclusion, the results of this study were consistent with those of previous sub-chronic exposure studies.

Anatomical and Histopathological Effects of Zinc Oxide Nanoparticles on Lungs in Adult Male Albino Rats

“…Signs included evidence of phagocytosis by macrophage, lymphocytic perivasculitis and pribronchiolitis and interstitial inflammation [7]. The findings of previous studies suggested that other routes of exposure to ZnO-NPs as intratracheal instillation could lead also to severe tissue damage and could progress to chronicpathological conditions [14,15]. The oxidative stress is a known contributor to…”

“…The lungs are particularly susceptible to ZnO-NPs because of its high vascularity and ability to concentrate toxins [11,12]. Up to our knowledge, the vast majority of the previous studies on lung toxicity of ZnO-NPs were addressing the short term exposure to it, and mostly the exposure was through inhalation and intratracheal instillation [13][14][15]. The toxic effect of short duration exposure to orally ingested ZnO-NPs on lungs was assessed in previous studies [10,12].…”

A distinct pattern of sterile inflammation induced by zinc oxide nanowires.

“…The intra-tracheal instillation of ZnONP in mice induced acute lung inflammation and lung injury with a significant increase in the LDH level detected in bronchial alveolar lavage fluids (BALF) [157,158]. Moreover, ZnONP induced the recruitment of macrophages and neutrophils with high levels of proinflammatory cytokines, such as IL-6 in BALF, after pulmonary exposure in mice [159][160][161]. Furthermore, ZnONP appears to have an adjuvant-like response to allergen ovalbumin (OVA) and induce Th2 responses in mice [154].…”