Pulmonary Inflammation Induced by Single Walled Carbon Nanotubes in Golden Syrian Hamsters

Abstract

Single-walled carbon nanotubes (SWCNTs) have a broad range of applications; however, they may present a potential health hazard. The current study was undertaken to evaluate the effects of inhalation exposure of aerosolized SWCNTs on hamster lungs. Golden Syrian Hamsters were divided in to 2 groups: a control group that was exposed to an aerosol of distilled water, and a treated group exposed to aerosolized SWCNTs at concentrations of 1, 2 or 4mg/m3 for 2hrs/day for 4 consecutive days. Additional groups were used to investigate longer inhalation periods (8 and 14 days) with exposures of 4hrs/day to 2mg/m3 SWCNTs. One day post exposure, hamsters were euthanized. Tissue sections were evaluated by TUNEL assay to determine apoptosis and tissue homogenates were used to measure endothelin-1 (ET-1) levels. Bronchoalveolar lavage fluid (BALF) was used to determine total leukocyte cell numbers, tumor necrosis factor receptor type 1 (TNFR1) counts and endothelin receptor subtypes A (ETA) levels on alveolar macrophages. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were carried out on lung tissue sections. The current study demonstrates inhalation exposures to SWCNTs in hamster induce pulmonary inflammation. Results from histological analysis of tissue sections indicated increase in inflammatory cells predominantly macrophages in airways and hyperplasia of airway epithelial cells. SWCNTs treatment significantly increased total BAL leukocyte counts, TNFR1 and lung ET-1 levels. SWCNTs treatment caused an increase in ETA levels and evidence of lung toxicity was demonstrated by apoptosis. SWCNTs deposition in alveolar airspaces along with changes to alveolar epithelium was observed in tissue sections examined by TEM.