Abstract
Background: Our previous work demonstrated that galectin-1 is enriched in the tips of developing secondary alveolar septa in neonatal mouse lung. Thus, we hypothesize that galectin-1 is a regulator and/or marker of alveologenesis, a process that is impaired in infants with bronchopulmonary dysplasia.
Objective: In order to further elucidate the role of galectin-1 in distal lung development, we characterized the localization of galectin-1 in the developing lung and evaluated the effects of retinoic acid, a known stimulator of alveolar formation, on galectin-1 expression.
Design/Methods: the lungs of postnatal day six mice were inflation fixed and immunostained for galectin-1, surfactant protein B (a marker of type II alveolar epithelial cells) and endoglin (an endothelial cell marker). In addition, fibroblasts were isolated from postnatal lung tissue, maintained in vitro, then treated with retinoic acid at a 1 micromolar concentration for 24 hours. Immunoblot analysis was used to evaluate the levels of galectin-1 protein in the cultured lung fibroblasts.
Results: The pattern of galectin-1 immunostaining in neonatal mouse lung differs markedly from that of surfactant protein B and endoglin, demonstrating that galectin-1 is localized to neither the type II alveolar cell nor the microvascular endothelium. The galectin-1 stained cells are located in the center of the secondary septal tips, making it likely that the galectin-1 is contained in fibroblasts. Fibroblasts isolated from neonatal mouse lung were found to contain galectin-1 protein, and galectin-1 levels were increased after treatment of the fibroblasts with retinoic acid.
Conclusions: In the neonatal mouse lung, galectin-1 is localized in secondary septal wall fibroblasts, a cell type which is important in the pathogenesis of bronchopulmonary dysplasia. The up-regulation of galectin-1 expression in lung fibroblasts represents a potential mechanism by which retinoic acid stimulates alveologenesis, since galectin-1 has been shown to promote the growth and differentiation of smooth muscle cells and endothelial cells, which are both important components of the developing alveolar wall.
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Foster, J., Snyder, J. 8 Galectin-1 is Located in Fibroblasts of Neonatal Mouse Lung and is up-Regulated by Retinoic Acid. Pediatr Res 58, 817 (2005). https://doi.org/10.1203/00006450-200510000-00038
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DOI: https://doi.org/10.1203/00006450-200510000-00038
