Hypoxic gene expression of donor bronchi linked to airway complications after lung transplantation

Rationale: 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. Objectives: To evaluate large airway oxygenation and hypoxic gene expression during the first month after lung transplantation and their relation to airway complications. Methods: 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. Measurements and Main Results: 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 23.9 ± 1.5 and 24.8 ± 2.1, respectively; P < 0.05) at 30 days. Upregulation 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). Conclusions: 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.