Alveolar Epithelial Damage and Dysfunction as Common Features of Ischemia/Reperfusion Injury and Primary Graft Dysfunction in Lung Transplants

• Published in: The Journal of heart and lung transplantation Vol. 40; no. 4; p. S379
• Main Authors: Landry, C., Adam, D., Privé, A., Bégin, S., Menaouar, A., Cailhier, J., Ferraro, P., Brochiero, E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2021
• ISSN: 1053-2498; 1557-3117
• DOI: 10.1016/j.healun.2021.01.1066

Ischemia reperfusion injury (I/R) is the major cause of primary graft dysfunction (PGD) after lung transplantation. I/R and PGD feature alveolar epithelial and endothelial damage, lung edema and inflammation. Edema resorption then depends on the restoration of alveolar epithelial integrity and the ability of alveolar cells to reabsorb Na+ (through ENaC channels) and fluid. We hypothesized that alveolar epithelial damage, and repair, are critical in PGD pathophysiology and resolution. Therefore, our aim was to identify novel biomarkers and therapeutic targets associated with I/R using cellular and animal models as well as human samples from lung transplants. The impact of a protocol mimicking hypothermic ischemia and warm reperfusion was first tested on primary rat alveolar epithelial cell cultures. Then, the impact of I/R was studied in vivo using models of inflammatory stress induced by LPS infusion or after unilateral lung transplantation in pigs. Finally, lung biopsies from donor grafts were collected during lung transplantations. After defining PGD grades within the recipients, alveolar alterations were finally analyzed within donor graft tissues. In primary rat cell cultures, the I/R mimicking protocol impaired tight junction proteins (ZO-1), transepithelial resistance, wound repair capacity as well as expression in ENaC and CFTR channels. Treatment with a KvLQT1 K+ channel activator (R-L3) accelerated the repair rates and enhanced barrier integrity (ZO-1 staining) as well as ENaC and CFTR protein expressions. In the porcine models, an exacerbated inflammatory response was observed along with alveolar damage, lung edema and decreased ZO-1, ENaC and CFTR expressions. Our preliminary analyses also indicated that among lung transplants subsequently developing PGD, an inflammatory response and reduced ENaC, CFTR and ZO-1 expressions were already observed within biopsies from donor grafts, collected before transplantation. Altogether our data support the hypothesis of alveolar epithelial dysfunction, after I/R injury. Based on these observations, our goal is to investigate a potential relationship between donor phenotypic factors, markers of epithelial damage/dysfunction within the grafts, inflammatory levels and the subsequent development of PGD in lung recipients.