TGFB1 and Chronic Obstructive Asthma: As a corollary, while the exact role of fibrocytes in asthma remains to be fully defined, in a previous study14 circulating fibrocytes are reported to have increased percentage in patients with chronic airway obstruction, while the serum levels of TGF-β1 were significantly higher in a group of ten patients with chronic obstructive asthma than in normal subjects and in asthmatic cases with normal lung function.