Exposure to Fullerene C60 Nanoparticles Impairs Lung Mechanics and Mitochondrial Function

Abstract

C60 fullerene (C60) carbon‐based nanoparticles are widely used because of their physicochemical properties, and are released into the atmosphere from anthropogenic or natural sources. Due to its small size (0.65–0.7 nm) and electronegative chemical behavior, C60 can overcome natural biological barriers and deposit onto the respiratory system. However, the literature does not fully describe its putative pulmonary burden. C60 interaction with double membrane organelles like mitochondria, housing enzyme systems that convert metabolism by‐products into usable energy (ATP) and are an important source of oxygen‐derived free radicals, has been recently described. We hypothesized that C60 impairs lung function and alters its inflammatory status via mechanisms possibly involving mitochondria. Hence, we addressed pulmonary mechanics, histology and mitochondrial function after a single exposure to C60. Our Institutional Ethics Committee approved the study (code: 155/18). Thirty‐five male BALB/c mice were randomly divided into 2 groups intratracheally (it) instilled with vehicle (0.9% NaCl + 1% Tween 80, CTRL) or C60 (1.0 mg/kg, FUL). Twenty‐four hours after exposure, 15 FUL and 8 CTRL mice were anesthetized (10 mg/kg xylazine and 120 mg/kg ketamine), paralyzed (pancuronium bromide, 0.1 mg/kg) and mechanically ventilated for the determination of lung mechanics. They were then euthanized by sectioning of abdominal aorta and vena cava; the lungs were extracted at FRC for histological processing. Results are expressed as median, 25th and 75th percentiles. FUL group showed increased lung tissue elastance (FUL=38.21, 32.43, 39.83 vs CTRL=31.63, 29.31, 33.41 cmH2O/mL, p=0.0049) and viscance (FUL=4.44, 3.72, 4.76 vs CTRL=3.73, 3.36, 3.87 cmH2O/mL, p=0.0225). In addition, lung histology disclosed increased inflammatory cell number (FUL=16.0, 14.6, 18.8 vs CTRL=9.2, 8.8, 9.6 10−3/μm2 cells, p=0.0022) and alveolar collapse (FUL=11.33, 10.34, 13.79 vs CTRL=5.78, 4.69, 7.71%; p=0.0286), septal thickening and pulmonary edema. The remaining 6 FUL and 6 CTRL mice were expertly euthanized by cervical dislocation. Mitochondrial function expressed reduction in state 1 respiration in the presence of pyruvate‐malate substrates [FUL=3.0±1.14 vs CTRL=4.46±0.9 (SEM) nmol O2/min/mg protein, p=0.0210], ATP production (FUL=122.6±18 vs CTRL=154.5±14 μmol/100 μg protein, p=0.0340), and higher generation of reactive oxygen species (ROS) (FUL 733.1±169.32 vs CTRL=486.39±73.1 nmol/100 μg protein, p=0.0313). In conclusion, exposure to fullerene C60 impaired lung mechanics and mitochondrial function, increased ROS concentration, and triggered pulmonary tissue inflammation.Support or Funding InformationCNPq, FAPERJ, FINEP, CAPES