Recovery of Airway Cilia Following Lung Transplant

PURPOSE: Cilia are microscopic hair-like structures that line the surface of epithelial cells throughout the entire respiratory system, from nasal passages to terminal bronchioles. Cilia protect the airways and lungs from infections and damage through coordinated beating, which help clear debris and microorganisms. Following lung transplantation, cilia beat pattern (CBP) and frequency (CBF) can be compromised, which could potentially impair overall airway clearance, thereby contributing to increased respiratory infections. This study describes cilia recovery following lung transplantation. METHODS: Patients were recruited following lung transplantation at the Alfred Hospital, Melbourne. Assessment for cilia function was performed at 3 intervals post-transplant, as per usual clinical practice; 6 weeks, 12 weeks and 6 months. Brush samples were taken for each patient at each interval from both the upper airway (inferior nasal turbinate, patient's native cilia) and the lower airway (right or left lower lobe, donor's cilia). Samples were analysed for both CBP and CBF. Ciliated cells were analysed at 500 frames per second (fps) using high speed video microscopy. RESULTS: At time of writing, 16 patients were enrolled in the study, with enrollment ongoing. Bilateral lung transplant = 13, single lung transplant = 3. Transplant indication was varied. At 6 weeks post-transplant, the lower airways cilia beat 2.6 Hz slower than the upper airways cilia (4.88 ± 2.09 Hz vs. 7.48 ± 2.23 Hz, respectively). The lower airways cilia beat patterns were generally reduced in beating amplitude, with the appearance of ineffective clearance of debris in several patients. At 12 weeks post-transplant, the lower airways cilia showed recovery in CBF, with the overall difference between nasal and bronchial CBF reduced to 1.2 Hz (6.01 ± 1.38 Hz vs. 7.19 ± 1.07 Hz). The cilia beating pattern had also improved by 12 weeks, with more efficient clearance seen. In patients with complete data to 6 months, further improvement of lower airways CBF was seen. CONCLUSION: Following lung transplantation, donor cilia display reduced CBF and ineffective CBP when compared with the recipient's native cilia. This difference continues to improve up to and beyond 12 weeks post-transplant.