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Altered compartmentalization of transforming growth factor-beta in asthmatic airways
A Magnan1, F Retornaz, A Tsicopoulos
1Chest Medicine and Allergology Department, Ste-Marguerite Hospital, Lille, France.
Background:
Asthma is characterized by alterations of the bronchial epithelium associated with inflammatory cell infiltrates and sub-epithelial fibrosis. Transforming Growth Factor-beta (TGF-beta) is an anti-inflammatory and fibrosing cytokine normally present in bronchial epithelial cells and also potentially produced by inflammatory cells. Thus, TGF-beta could play a role in the asthmatic process, and its expression could be modified in asthmatic airways.
Objective:
To test this latter hypothesis, we studied the bronchial distribution of TGF-beta in asthmatic patients.
Methods:
TGF-beta 1, 2, 3 distribution was studied by immunohistochemistry in bronchial biopsies from 12 asthmatic patients and 10 non-asthmatic subjects.
Results:
Bronchial epithelial cells from asthmatics were negative or faintly positive while a bright staining was detected in these from non-asthmatics (P < 0.01). In both groups, when inflammatory cells were present beneath the basement membrane, they were stained by the anti-TGF-beta antibody.
Conclusion:
This study shows an altered compartimentalization of TGF-beta in asthma. (a) TGF-beta is scarse in asthmatic bronchial epithelial cells, which could favour the perennization of the bronchial inflammation, and (b) TGF-beta is present in inflammatory cells beneath the basement membrane, where it could be involved in the frequent sub-epithelial fibrosis.