title: Effect of toluene diisocyanate and its corresponding amines on viability and growth of human lung fibroblasts in culture.
abstract: Toluene diisocyanate (TDI) is a highly volatile chemical known to cause occupational asthma in exposed workers. TDI-induced asthma is associated with airway epithelium injury and repair, and subepithelial fibrosis. We investigated the effect of TDI and its hydrolysis products, the 2,4- and 2,6-toluenediamines (TDA), on viability and growth of human lung fibroblasts (HLFs) in culture, using a tetrazolium-based cell viability assay. The effects of increasing concentrations of each of these chemicals were evaluated on quiescent cells seeded at two densities (2500 and 5000 cells/well) and treated for 24 or 48 h. TDI (10(-4)-10(-5) mol/L, as a mixture of 80% 2,4-TDI and 20% 2,6-TDI) exhibited a partial but significant cytotoxic effect (10-24%, p<0.05) on HLFs. This effect was observed at both cell densities, and was time- and concentration-dependent. 2,4-TDA, at lower concentrations (10(-8)-10(-6) mol/L) applied for 48 h, also partially reduced HLF viability (10-15%, p<0.05), whereas it tended to trigger cell growth at concentrations higher than 10(-5) mol/L. 2,6-TDA exhibited both a cytotoxic and a proliferative effect on HLFs that depended on concentration, time of exposure and cell culture density. Significant cytotoxicity was only observed after 24 h of treatment with 10(-7)-10(-6) mol/L 2,6-TDA, and reached greater intensity in cells cultured at the highest density. In contrast, 2,6-TDA stimulated HLF growth only after 48 h of incubation at 10(-4) mol/L on cells cultured at the lowest density. Taken together, our results showed that TDI and 2,4-TDA somewhat decreased HLF viability, whereas 2,6-TDA appeared to exhibit both a cytotoxic and a growth stimulatory effect on these cells. TDI and 2,4-TDA are thus suggested to contribute to airway epithelium damage associated with TDI-induced asthma, whereas 2,6-TDA might either trigger epithelial damage or induce cell proliferation that could contribute to epithelium repair or subepithelial fibrosis.
authors.affiliation: INSERM U425, Neuroimmunopharmacologie Pulmonaire, Faculté de Pharmacie, Illkirch, France. pons@pharma.u-strasbg.fr
authors.forename: F
authors.initials: F
authors.lastname: Pons
authors.forename: A
authors.initials: A
authors.lastname: Fischer
authors.forename: N
authors.initials: N
authors.lastname: Frossard
authors.forename: A
authors.initials: A
authors.lastname: Lugnier
mesh_terms: D001249:Asthma / Q000139:chemically induced; D002273:Carcinogens / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004396:Coloring Agents; D003603:Cytotoxins / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008168:Lung / Q000166:cytology*; D009784:Occupational Diseases / Q000139:chemically induced; D016877:Oxidants / Q000494:pharmacology; D010655:Phenylenediamines / Q000494:pharmacology*; D013778:Tetrazolium Salts; D013844:Thiazoles; D014051:Toluene 2,4-Diisocyanate / Q000494:pharmacology*
chemical_list: D002273:Carcinogens; D004396:Coloring Agents; D003603:Cytotoxins; D016877:Oxidants; D010655:Phenylenediamines; D013778:Tetrazolium Salts; D013844:Thiazoles; D014051:Toluene 2,4-Diisocyanate; D006861:Hydrogen Peroxide; C022616:thiazolyl blue; C010914:2,4-diaminotoluene