Dataset Information

Airway fibroblasts in asthma manifest an invasive phenotype.

ABSTRACT:

Rationale

Invasive cell phenotypes have been demonstrated in malignant transformation, but not in other diseases, such as asthma. Cellular invasiveness is thought to be mediated by transforming growth factor (TGF)-β1 and matrix metalloproteinases (MMPs). IL-13 is a key T(H)2 cytokine that directs many features of airway remodeling through TGF-β1 and MMPs.

Objectives

We hypothesized that, in human asthma, IL-13 stimulates increased airway fibroblast invasiveness via TGF-β1 and MMPs in asthma compared with normal controls.

Methods

Fibroblasts were cultured from endobronchial biopsies in 20 subjects with mild asthma (FEV(1): 90 ± 3.6% pred) and 17 normal control subjects (FEV(1): 102 ± 2.9% pred) who underwent bronchoscopy. Airway fibroblast invasiveness was investigated using Matrigel chambers. IL-13 or IL-13 with TGF-β1 neutralizing antibody or pan-MMP inhibitor (GM6001) was added to the lower chamber as a chemoattractant. Flow cytometry and immunohistochemistry were performed in a subset of subjects to evaluate IL-13 receptor levels.

Measurements and main results

IL-13 significantly stimulated invasion in asthmatic airway fibroblasts, compared with normal control subjects. Inhibitors of both TGF-β1 and MMPs blocked IL-13-induced invasion in asthma, but had no effect in normal control subjects. At baseline, in airway tissue, IL-13 receptors were expressed in significantly higher levels in asthma, compared with normal control subjects. In airway fibroblasts, baseline IL-13Rα2 was reduced in asthma compared with normal control subjects.

Conclusions

IL-13 potentiates airway fibroblast invasion through a mechanism involving TGF-β1 and MMPs. IL-13 receptor subunits are differentially expressed in asthma. These effects may result in IL-13-directed airway remodeling in asthma.

SUBMITTER: Ingram JL

PROVIDER: S-EPMC3136991 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:BACKGROUND: Evaluation of the airway transcriptome may reveal patterns of gene expression that are associated with clinical phenotypes of asthma. To define transcriptomic endotypes of asthma (TEA) we analyzed gene expression in induced sputum that correlate with phenotypes of disease. METHODS: Gene expression was measured in sputum of subjects with asthma using Affymetrix HuGene ST 1.0 microarrays. Unsupervised clustering analysis of genes in pathways selected from the Kyoto Encyclopedia of Genes and Genomes (KEGG) identified TEA clusters. Clinical characteristics were compared and logistic regression analysis of matched blood samples defined an expression profile to determine the TEA cluster assignment in a cohort of children with asthma for validation. RESULTS: Three TEA clusters were identified. TEA cluster 1 had the most subjects with a history of intubation (P = 0.05), a lower pre-bronchodilator FEV1 (P = 0.006), a higher bronchodilator response (P = 0.03), and higher exhaled nitric oxide levels (P = 0.04), compared to the other TEA clusters. TEA cluster 2, the smallest cluster had the most subjects that were hospitalized for asthma (P = 0.04). Subjects in TEA cluster 3, the largest cluster, had normal lung function, low exhaled nitric oxide levels, and lower inhaled steroid requirements. Evaluation of TEA clusters in children confirmed that TEA clusters 1 and 2 are associated with a history of intubation (P = 5.58 x 10-06) and hospitalization (P = 0.01), respectively. CONCLUSIONS: Patterns of gene expression in the sputum and blood reveal TEA clusters that are associated with severe asthma phenotypes in children and adults. Gene expression was measured in sputum of subjects with asthma using Affymetrix HuGene ST 1.0 microarrays. Unsupervised clustering analysis of genes in pathways selected from the Kyoto Encyclopedia of Genes and Genomes (KEGG) identified TEA clusters. Clinical characteristics were compared and logistic regression analysis of matched blood samples defined an expression profile to determine the TEA cluster assignment in a cohort of children with asthma for validation.