Changes in the Levels of Interferon-γ and Transforming Growth Factor-β Influence Bronchial Stenosis during the Treatment of Endobronchial Tuberculosis

Abstract

Background: Endobronchial tuberculosis (EBTB) has been shown to frequently complicate bronchial stenosis, a condition which can induce dyspnea as a result of airway obstruction, and is also frequently misdiagnosed as either bronchial asthma or lung cancer. Objectives: This study attempted to determine whether there was a correlation between interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) levels in the serum and bronchial washing fluid (BWF), and the results of the treatment of EBTB patients. Methods: Thirty patients, all of whom were diagnosed as EBTB, were enrolled, as were 10 healthy control subjects. IFN-γ and TGF-β levels were measured by the ELISA method in the serum and BWF of these 30 EBTB patients before and after treatment. The EBTB patients were divided into two groups: those who exhibited bronchial stenosis after treatment and those who did not. Chest computed tomography (CT) and pulmonary function test (PFT) were performed in 16 and 25 patients, respectively, at initial bronchoscopy. Results: IFN-γ and TGF-β levels in the BWF of the EBTB patients were elevated compared to the controls (p < 0.05). After 2 months of treatment, 13 of the 30 EBTB patients exhibited bronchial fibrostenosis and the other 17 cases had recovered without sequelae. In the bronchial stenosis group, the initial serum TGF-β levels were lower than in the patients without bronchial stenosis (p < 0.05). Moreover, the levels of serum TGF-β after treatment were shown to have decreased more than in the patients without bronchial stenosis (p < 0.05). On chest CT findings of 16 EBTB patients, bronchial narrowing was suspected except in 2 cases (1 edematous-hyperemic type, 1 actively caseating type of segmental bronchus). The common features of PFT in EBTB at the initial diagnosis were a restrictive pattern and normal ventilatory function. Conclusions: Elevated IFN-γ and TGF-β levels in the BWF of the EBTB patients may be related to EBTB pathogenesis. Lowered initial serum TGF-β levels as well as the observed changes in the levels of TGF-β in the serum after treatment have been implicated in bronchial fibrostenosis during the course of the disease.