TGFB1 and asthma: Mepolizumab treatment in asthma patients has not only reduced the number of eosinophils in the bronchial passages, but has also decreased TGF-β1-positive eosinophils, the thickness and the tenascin immunoreactivity of the airways, and the levels of TGF-β1 in bronchoalveolar lavage fluid [166].