Peripheral blood and airway tissue expression of transforming growth factor beta by neutrophils in asthmatic subjects and normal control subjects

Background: Airway remodeling may play an important role in asthma pathophy siology, Transforming growth factor beta (TGF-beta) has a critical role in the remodeling process, Although cellular sources for TGF-beta have been pr eviously investigated in asthma airways, the expression, release, or both o f TGF-beta from asthmatic airways and blood neutrophils has not been report ed. Objective: The current study evaluated the TGF-beta protein and messenger ( m)RNA expression by airway and peripheral blood neutrophils in asthmatic an d normal subjects. Methods: TGF-beta protein expression by airway and peripheral blood neutrop hils was detected by using immunocytochemistry: TGF-beta protein levels in blood neutrophil supernatant were measured by using an enzyme immunoassay, TGF-beta mRNA expression was evaluated by using reverse transcription-PCR. Results: Higher numbers of TGF-beta (+) cells and neutrophils were found in airway tissue of asthmatic (n = 15) compared with normal subjects (n = 10) , Although neutrophils in both asthmatic and normal airway tissue expressed TGP-beta protein and the percentage of neutrophils expressing TGF-beta was similar between the two groups, the total number of TGF-beta (+) neutrophi ls was higher in the asthmatic subjects (P = .01). Peripheral blood neutrop hils from asthmatic (n = 5) and normal subjects: (n = 7) also expressed TGF -beta protein and mRNA, Blood neutrophils from asthmatic subjects spontaneo usly released significantly higher levels of TGF-beta than those from norma l subjects (P = .007). Conclusion: These data suggest that airway and blood neutrophils from both asthmatic and normal subjects can express and release TGF-beta. Higher leve ls of TGF-beta expression-release from asthmatic neutrophils indicate that neutrophils may be involved in the airway remodeling process of asthmatic s ubjects.