Expression of CD55 and ACTA2 in Bronchopulmonary Dysplasia

(BPD) disease exchange and suggests differential expression of certain lung proteins in BPD lungs, recovered lungs, and control lungs. In an effort to validate some of the proteomic data from PNNL, we chose to study the spatial location of smooth muscle alpha actin (ACTA2) to substantiate the proteomic findings that ACTA2 is more highly expressed in BPD lungs, using immunofluorescence microscopy. CD55—an inhibitor of complement activation, previously noted to be expressed in alveolar epithelial cells—was also assessed, because its role in lung development is not well described. Methods: Formalin-fixed, paraffin embedded sections from the proximal lung and alveolar region for each donor were deparaffinized, rehydrated, and subjected to optimal antigen retrieval conditions for CD55 and ACTA2 multiplex. Each slide was blocked for 60 minutes, incubated overnight with antibodies for ACTA2 and CD55, then incubated with fluorophore conjugated secondary antibodies. A slide with no antibodies added and a second slide with secondary antibodies only were kept as negative controls. All slides were imaged with a Keyence BZ-X810 inverted epifluorescence microscope. Results: Epithelial marker CD55 outlines structural differences in alveolar regions. Alveolarization is much less prominent in BPD tissue versus control, with fewer secondary crests and less