LTBP1 and chronic obstructive pulmonary disease: LTBP-1 is the only LTBP that both interacts with latent TGF-βs48 and is predominantly expressed in the lungs.49, 50, 51, 52, 53 LTBP-1 immunostaining was increased in the bronchial lamina propria of patients with COPD compared with control smokers with normal lung function.