Lymphatic function is required prenatally for lung inflation at birth

Area of Science:

• Developmental Biology
• Respiratory Physiology
• Vascular Biology

Background:

• Neonatal lung inflation is critical for survival, primarily regulated by pulmonary surfactant.
• The role of other developmental processes, like lymphatic function, in preparing lungs for breathing remains unclear.

Purpose of the Study:

• To investigate the role of prenatal lymphatic vascular function in neonatal lung inflation and respiration.

Main Methods:

• Analysis of mouse models lacking lymphatic vessels (CCBE1 or VEGFR3 deficiency).
• Assessment of lung inflation, respiratory function, lung compliance, and tissue hydration (wet/dry ratio).
• Examination of embryonic lung lymphatic function and mechanics in late gestation.

Main Results:

• Mice lacking lymphatic vessels exhibited cyanosis and died post-birth due to failed lung inflation.
• Failure was linked to lung edema (elevated wet/dry ratio), not surfactant deficiency or developmental defects.
• Late gestation embryos lacking lymphatics showed significantly reduced lung compliance.

Conclusions:

• Prenatal lymphatic function is a critical, previously unrecognized mechanical factor in preparing the lung for air breathing.
• This finding explains respiratory failure in congenital pulmonary lymphangiectasia.
• Inadequate lymphatic function in late gestation may contribute to respiratory distress in premature infants.