Negative impact of hyperglycaemia on mouse alveolar development

Diabetes mellitus in pregnancy has been known to affect the embryonic development of various systems, including cardiovascular and nervous systems. However, whether this disease could have a negative impact on embryonic respiratory system remains controversial. In this study, we demonstrated that pregestational diabetes mellitus (PGDM)-induced defects in lung development in mice are mainly characterized by the changes in the morphological structure of the lung. Immunostaining and Western blotting showed that proliferation increased and apoptosis decreased in PGDM. Hyperglycaemia caused pulmonary tissue fibrationas manifested by an increase in Masson staining and decorin expression in PGDM lungs, and the immunofluorescent pro-SPC⁺ type II pulmonary epithelial cell number was decreased. The alteration of pulmonary epithelial cell differentiation might be due to hyperglycaemia-activated Wnt signalling and suppressed GATA6 expression in PGDM mouse lung tissues and MLE-12 cells. The treatment of MLE-12 cells with high glucose in the presence/absence of XAV939 or su5402 further proved that hyperglycaemia suppressed the expression of GATA6 and pro-SPC by activating Wnt signalling and induced the expression of decorin, α-SMA and TGF-β by activating Fgf signalling. Therefore, in this study, we revealed that hyperglycemia induced dysfunctional pulmonary cell apoptosis and proliferation, as well as pulmonary myofibroblast hyperplasia, which contributed to the formation of aberrant structure of alveolar walls. Furthermore, the hyperglycaemia also inhibited the differentiation of pulmonary epithelial cells through the canonical Wnt and Fgf signalling, and the alteration of Fgf and Wnt signalling activated TGF-β, which would promote the AECII EMT process.