Hypoxic Gene Expression of Donor Bronchi Linked to Airway Complications after Lung Transplantation

Central airway stenosis (CAS) after lung transplantation has been attributed in part to chronic airway ischemia; however, little is known about the time course or significance of large airway hypoxia early after transplantation.

To evaluate large airway oxygenation and hypoxic gene expression during the first month after lung transplantation and their relation to airway complications.

Subjects who underwent lung transplantation underwent endobronchial tissue oximetry of native and donor bronchi at 0, 3, and 30 days after transplantation (n = 11) and/or endobronchial biopsies (n = 14) at 30 days for real-time polymerase chain reaction of hypoxia-inducible genes. Patients were monitored for 6 months for the development of transplant-related complications.

Compared with native endobronchial tissues, donor tissue oxygen saturations (Sto2) were reduced in the upper lobes (74.1 ± 1.8% vs. 68.8 ± 1.7%; P < 0.05) and lower lobes (75.6 ± 1.6% vs. 71.5 ± 1.8%; P = 0.065) at 30 days post-transplantation. Donor upper lobe and subcarina Sto2 levels were also lower than the main carina (difference of -3.9 ± 1.5 and -4.8 ± 2.1, respectively; P < 0.05) at 30 days. Up-regulation of hypoxia-inducible genes VEGFA, FLT1, VEGFC, HMOX1, and TIE2 was significant in donor airways relative to native airways (all P < 0.05). VEGFA, KDR, and HMOX1 were associated with prolonged respiratory failure, prolonged hospitalization, extensive airway necrosis, and CAS (P < 0.05).

These findings implicate donor bronchial hypoxia as a driving factor for post-transplantation airway complications. Strategies to improve airway oxygenation, such as bronchial artery re-anastomosis and hyperbaric oxygen therapy merit clinical investigation.