title: Imogolite: an aluminosilicate nanotube endowed with low cytotoxicity and genotoxicity.
abstract: High-aspect-ratio nanomaterials (HARN) (typically, single-walled carbon nanotubes (SWCNT) or multiwalled carbon nanotubes (MWCNT)) impair airway barrier function and are toxic to macrophages. Here, we assess the biological effects of nanotubes of imogolite (INT), a hydrated alumino-silicate [(OH)3Al2O3SiOH] occurring as single-walled NT, on murine macrophages and human airway epithelial cells. Cell viability was assessed with resazurin. RT-PCR was used to study the expression of Nos2 and Arg1, markers of classical or alternative macrophage activation, respectively, and nitrite concentration in the medium was determined to assess NO production. Epithelial barrier integrity was evaluated from the trans-epithelial electrical resistance (TEER). Potential genotoxicity of INT was assessed with comet and cytokinesis-block micronucleus cytome assays. Compared to MWCNT and SWCNT, INT caused much smaller effects on RAW264.7 and MH-S macrophage viability. The incubation of macrophages with INT at doses as high as 120 μg/cm(2) for 72 h did not alter either Nos2 or Arg1 expression nor did it increase NO production, whereas IL6 was induced in RAW264.7 cells but not in MH-S cells. INT did not show any genotoxic effect in RAW264.7 and A549 cells except for a decrease in DNA integrity observed in epithelial A549 cells after treatment with the highest dose (80 μg/cm(2)). No significant change in permeability was recorded in Calu-3 epithelial cell monolayers exposed to INT, whereas comparable doses of both SWCNT and MWCNT lowered TEER. Thus, in spite of their fibrous nature, INT appear not to be markedly toxic for in vitro models of lung-blood barrier cells.
authors.affiliation: Department of Biomedical, Biotechnological and Translational Sciences (SBiBiT) and ‡Department of Clinical and Experimental Medicine, University of Parma , 43125 Parma, Italy.
authors.forename: Bianca Maria
authors.initials: BM
authors.lastname: Rotoli
authors.forename: Patrizia
authors.initials: P
authors.lastname: Guidi
authors.forename: Barbara
authors.initials: B
authors.lastname: Bonelli
authors.forename: Margherita
authors.initials: M
authors.lastname: Bernardeschi
authors.forename: Massimiliano G
authors.initials: MG
authors.lastname: Bianchi
authors.forename: Serena
authors.initials: S
authors.lastname: Esposito
authors.forename: Giada
authors.initials: G
authors.lastname: Frenzilli
authors.forename: Paolo
authors.initials: P
authors.lastname: Lucchesi
authors.forename: Marco
authors.initials: M
authors.lastname: Nigro
authors.forename: Vittoria
authors.initials: V
authors.lastname: Scarcelli
authors.forename: Maura
authors.initials: M
authors.lastname: Tomatis
authors.forename: Pier Paolo
authors.initials: PP
authors.lastname: Zanello
authors.forename: Bice
authors.initials: B
authors.lastname: Fubini
authors.forename: Ovidio
authors.initials: O
authors.lastname: Bussolati
authors.forename: Enrico
authors.initials: E
authors.lastname: Bergamaschi
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry / Q000633:toxicity*; D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D020552:Comet Assay; D005561:Formates / Q000737:chemistry; D005609:Free Radicals / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D051379:Mice; D015162:Micronucleus Tests; D043942:Nanotubes / Q000737:chemistry / Q000633:toxicity*; D037742:Nanotubes, Carbon / Q000633:toxicity; D009569:Nitric Oxide / Q000378:metabolism
chemical_list: D000538:Aluminum Silicates; D005561:Formates; D005609:Free Radicals; D037742:Nanotubes, Carbon; C030544:formic acid; C049037:aluminosilicate; D009569:Nitric Oxide; D006861:Hydrogen Peroxide