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A6327 - Association of Airway Smooth Muscle Deficiency with Congenital Pulmonary Airway Malformation
Author Block: W. Shi1, Y. Jiang1, Y. Luo2, R. Moats3, D. Warburton4, L. Wang1; 1Childrens Hosp Los Angeles, Los Angeles, CA, United States, 2Children hospital Los Angeles, Los Angeles, CA, United States, 3CHLA/USC, Los Angeles, CA, United States, 4Childrens Hosp Los Angles Rsch Inst, Los Angeles, CA, United States.
Congenital pulmonary airway malformation (CPAM) is the most common congenital lesion detected in neonatal lung, which may lead to respiratory distress, infection, and pneumothorax. CPAM is thought to result from abnormal branching morphogenesis during fetal lung development, arising from different locations of developing respiratory tracts. However, the pathogenic mechanisms are unknown, and related cellular and molecular changes are not fully investigated. We have analyzed 20 excised infant lung specimens with diagnosis of type I or type II CPAM. By immunofluorescence staining, a variety of cells and extracellular proteins were examined. We found that the smooth muscle layers underlining the airway cysts in these CPAM specimens were significantly decreased compared to those in normal bronchiolar walls of controls. Elastin fibers in cystic airway submucosal area were also reduced in airway cystic walls of CPAM. In addition, Club cells in cystic epithelia of some CPAM samples were increased compared to the bronchioles of normal controls. Thus, our data for the first time suggest that airway cystic lesions in CPAM is not only the abnormality in airway epithelial cells, but also alterations in surrounding mesenchymal cells including airway smooth muscle cells and their extracellular protein elements. This study also support that airway smooth muscle cells are important in normal lung branching morphogenesis in human.