Evaluation of serum levels of all the transforming growth factor β (TGF-β 1-3) isoforms in asthmatic patients

Introduction:
Asthma is a heterogeneous chronic inflammatory disease of the airways. Chronic inflammation leads to changes in the structure and stiffening of the bronchial wall, and irreversible disruption of airflow through the airways. One of the factors researchers consider important in the process of inflammation and fibrosis is the transforming growth factor β (TGF-β). Overexpression of TGF-β in the structural cells of the bronchial tree is thought to translate into excessive secretion of type I and III collagen, fibronectin, tenascin and proteoglycans, as well as inhibition of matrix metalloproteinases and collagenases, promoting the phenomenon of remodeling.

Aim:
To evaluate serum levels of all the TGF-β (TGF-β 1-3) isoforms in asthmatic patients, compare the obtained results with those of non-asthmatic subjects, and analyze potential correlations between particular isoforms.

Material and methods:
The study included 69 individuals, 41 asthmatic patients and 28 non-asthmatic volunteers recruited from the Department of Allergology and the Allergy and Pulmonology Outpatient Clinic of N. Barlicki University Teaching Hospital No. 1 in Lodz. The participants underwent a full medical examination and spirometry, and blood samples were collected from them for serum TGF-β levels. Individual isoforms, i.e., TGF-β1, TGF-β2 and TGF-β3, were determined by ELISA. The data obtained were then subjected to statistical analysis using Student’s t-test, the Mann-Whitney U-test, Fisher’s t-test and Pearson’s correlation method.

Results:
The obtained results show a significant increase in TGF-β1 and TGF-β2 levels, as well as a slight increase in TGF-β3 concentration among asthmatic patients compared to the general population. Additionally, there occurred a significant association between TGF-β1 and TGF-β2. TGF-β1 and TGF-β2 isoforms were found to be associated with the pathogenesis of asthma. Among the patients, serum TGF-β levels were significantly higher compared to the control group.

Conclusions:
The TGF-β1 and TGF-β2 isoforms appear to have a cumulative effect on remodeling processes in the airways.