Effect of MWCNT on Lung Fibroblast gene expression

Multi-walled carbon nanotubes (MWCNT) cause lung fibrosis in rodents and exacerbate airway fibrosis in the mouse ovalbumin model of allergic asthma. Interleukin 13 (IL-13) is a key cytokine secreted by T helper type 2 (Th2) cells. IL-13 is up-regulated in human asthma and animal models that activate pro-fibrotic and pro-proliferative cell signaling cascades in human lung fibroblasts (HLF). This study tested the hypothesis that IL-13 alters the gene expression profile of HLF exposed to MWCNT. Carbon black nanoparticles (CBNP) were also compared to MWCNT as they are relatively inert nanoparticles that do not cause fibrosis. Confluent, quiescent cultures of HLF were treated with 10 ng/ml IL-13 or serum-free defined medium (vehicle) for 24 hours prior to treatment with 10 µg/cm2 MWCNT or CBNP. At 4, 24, or 48 hours following nanoparticle exposure, total RNA was isolated and gene expression was measured using the Affymetrix Human Genome U133A2.0 Array. The data were analyzed using the JMP Genomics statistical platform. IL-13 and MWCNT each caused changes in the expression of distinct gene subsets over the time-course investigated. The combination of IL-13 and MWCNT resulted in a gene expression profile that was distinct from patterns induced or suppressed by either IL-13 or MWCNT alone. CBNP caused changes in gene expression that were distinct from IL-13 or MWCNT. Interestingly, the combination of IL-13 and MWCNT increased the expression of IL-17A and increased collagen (Col1A1), while MWCNT alone increased interferon-inducible protein-27 (IFI27), suggesting that Th2 microenvironment containing IL-13 shifts MWCNT-induced gene expression from a Th1 to a Th17 gene expression profile. These data provide insight into the mechanisms by which MWCNT alter the biology of fibroblasts during normal and allergic inflammatory conditions. Adult Lung Fibroblasts were treated with 10 µg/cm2 MWCNT, CBNP, or vehicle with or without IL-13 for 4 hours, 24 hours, or 48 hours.