Lung bioactivity of vapor grown carbon nanofibers

Vapor grown carbon nanofibers (VGCF™-H) is an example of a two dimensional carbon based nanoparticle. In the present study, male C57Bl/6J mice were exposed to VGCF™-H (10–80 μg) by pharyngeal aspiration; dispersion medium (DM) was used as the vehicle. At 1, 7 and 28 days post-exposure, lung lavage and histopathology studies were conducted. VGCF™-H cytotoxicity was assessed by measuring acellular lavage fluid lactate dehydrogenase (LDH) activity, and determined that VGCF™-H exposure produced dose-dependent increases in LDH activity which decreased over time. Using polymorphonuclear leukocytes as a marker, VGCF™-H-exposure produced dose-dependent lung inflammation which decreased over time. Histologically, the incidence and severity of pulmonary inflammation was confirmed to be dose-dependent, and inflammatory infiltrates were characterized by increased numbers of alveolar macrophages with small numbers of neutrophils. VGCF™-H caused dose- and time-dependent increases in cathepsin activity and cytokines in the acellular lavage fluid, indicating activation of the NLRP3 inflammasome by VGCF™-H may contribute to lung inflammation. VGCF™-H exposure caused minimal to mild interstitial alveolar fibrosis, characterized by increased amounts of collagen fibers in the interstitium, and the incidence and severity of fibrosis tended to increase with the VGCF™-H dose. Accumulation of VGCF™-H fibers in the tracheobronchial lymph nodes was observed by 28 days after exposure at 40 and 80 μg doses.