PT  - JOURNAL ARTICLE
AU  - Pakatip Ruenraroengsak
AU  - Shu Cheng
AU  - Hu Sheng
AU  - Milo Shaffer
AU  - Alexandra Porter
AU  - Teresa Tetley
TI  - Translocation of carbon nanotubes across the alveolar epithelial barrier
DP  - 2014 Sep 01
TA  - European Respiratory Journal
PG  - P1098
VI  - 44
IP  - Suppl 58
4099  - http://erj.ersjournals.com/content/44/Suppl_58/P1098.short
4100  - http://erj.ersjournals.com/content/44/Suppl_58/P1098.full
SO  - Eur Respir J2014 Sep 01; 44
AB  - Inhalation of nano-sized material may pose a health risk. Carbon nanotubes (CNT) are amongst the most used nanomaterials, globally. We hypothesized that translocation of CNTs across alveolar epithelium would be size-dependent. We examined transport of 200 and 700nm 4-vinylpyridine carbon nanotubes (4VPCNTs) across monolayers of immortal, human type 1-like (TT1), and primary type 2 (AT2) alveolar epithelial cells.Methods: Cells were cultured in 12-well transwellÒ inserts until they formed tight junctions. Cells were exposed to 15-20 μg/ml CNTs for 24h. Cell viability was determined (WST assay). CNT distribution was analysed using spectrophotometry. Translocation and uptake was determined using confocal microscopy, SEM and TEM; transepithelial resistance (TEER) and dextran translocation indicated monolayer integrity.Results: 4VPCNTs were not cytotoxic. ∼3% of both CNT lengths were detected basally in the TT1 cell model, confirming 4VPCNT translocation; no CNTs translocated AT2 cells. CNTs caused reduced TT1 and AT2 TEER values; only TT1 cells exposed to 200nm 4VPCNT showed TEER recovery, CNT enhanced dextran transport to basal chamber. CNT uptake involved endocytosis, being located in endosomal, lysosomal and cytosolic compartments in TT1 cells. CNTs escaped from lysosomes into the cytoplasm.Conclusion: AT2 cells exhibited a strong barrier against 4VPCNTs. There was no difference in transportation of the two lengths of 4VPCNTs across TT1 cells; altered TEER values and dextran transport indicates possible interaction between CNTs and tight junction proteins. Compromised alveolar tight junction integrity and translocation of CNTs following inhalation of CNTs could impact on alveolar homeostasis.