The Effect Of Disturbed Elastin Fiber Structures In Bronchopulmonary Dysplasia

Objective: To observe the expressions elastin fiber and its relatedproteins in normal newborn mice and hyperoxia exposed newborn mice, toinvestigate the effect of disturbed elastin fiber structures inbronchopulmonary dysplasia (BPD).Methods: Postnatal24hours C57BL/6mice, which were randomlydivided into control group exposed in air and BPD group hyperoxia exposedrespectively. Using hematoxylin and eosin(HE)staining, radical alveolarcounts(RAC), elastic fiber staining, Secondary Crest counts, electronmicroscope, immunofluorescence and Q-PCR to estimate at postnatal1,3,7,14,21day of two groups the changes of lung morphology and the expressingof tropoelastin and fibulin-5protein, tropoelastin, fibrillin-1, fibrillin-2,fibulin-4, fibulin-5, lysyl oxidase, Neutrophil elastase, Integrin alpha VmRNA.Results: The control group mice formed secondary crest from3d,increased and elongated with the lung development. The elastin fiber orderlydeposition at the tips of secondary crest. Contrasted the control group, BPDgroup showed failure to formed secondary crest at3d, at21d there are fewer and larger alveoli, secondary crest disappeared and distributed elastic fibersdisplayed thickened, tortuous, and irregularly in the connective tissue matrix.Tropoelastin and its related proteins: fibrillin-1, fibrillin-2, fibulin-4,fibulin-5, integrinαv and neutrophil elastase mRNA were expressing incontrol group from postnatal1d, frist increased and then decreased.Contrasted the control group, BPD group showed tropoelastin, fibrillin-1,fibrillin-2, fibulin-4, fibulin-5mRNA increased at14d and21d; neutrophilelastase mRNA was significantly increased at1d,3d,7d,14d and decreasedat21d.In control group, tropoelastin and fibulin-5protein were depositionon secondary crest, airway and great vessels, contrasted the control group,BPD group were irregularly deposition on alveolar septum.Conclusion: The balance elastin fiber is an important mechanism ofalveoli development; disturbed elastin fiber structures is an importantpathologic process of BPD.