SM22α cell-specific HIF stabilization mitigates hyperoxia-induced neonatal lung injury

Area of Science:

• Neonatal Physiology
• Pulmonary Medicine
• Molecular Biology

Background:

• Bronchopulmonary dysplasia (BPD) remains a significant challenge in preterm infant care, despite improved survival rates.
• The underlying mechanisms of BPD, particularly the role of cell-specific hypoxia-inducible factors (HIFs) in neonatal lung injury, are not fully understood.
• Histological hallmarks of BPD include alveolar simplification and reduced lung microvasculature.

Purpose of the Study:

• To investigate the protective effects of HIF stabilization specifically in SM22α-expressing cells against hyperoxia-induced neonatal lung injury.
• To determine the impact of cell-specific HIF-1α stabilization on lung development, microvascular integrity, and associated molecular pathways.

Main Methods:

• Generation of SM22α-specific HIF-1α-stabilized mice (SM22α-PHD1/2-/-) by genetic cross-breeding.
• Exposure of neonatal mice to normoxia (21% O2) or hyperoxia (80% O2) for 14 days, followed by a 10-week recovery period.
• Assessment of lung injury, microvessel density, cell proliferation, gene expression (Angiopoietin-2), and vascular structure in pulmonary artery endothelial cells (PAECs) and pulmonary artery smooth muscle cells (PASMCs).

Main Results:

• SM22α-specific HIF-1α stabilization significantly mitigated hyperoxia-induced lung injury and preserved microvessel density in both neonates and adults.
• Mice with stabilized HIF-1α in SM22α-expressing cells exhibited increased PAEC proliferation and collagen IV expression in pulmonary arteries.
• Enhanced Angiopoietin-2 (Ang2) mRNA expression was observed in PASMCs, and co-culture experiments demonstrated improved tube formation in pulmonary endothelial cells, further augmented by recombinant Ang2.

Conclusions:

• Cell-specific deletion of PHD1 and PHD2 selectively stabilizes HIF-1α in SM22α-expressing cells, offering protection against neonatal lung injury induced by prolonged hyperoxia.
• HIF stabilization in these specific cells preserves endothelial cell proliferation, microvascular density, and lung structure.
• Targeted HIF-1α stabilization presents a promising therapeutic strategy for preventing or mitigating neonatal lung injury and BPD.