L2. TRPV4 Channel Inhibition Attenuates Lung Ischemia-Reperfusion Injury and Endothelial Barrier Disruption in a Porcine Lung Transplant Model

Objective: Primary graft dysfunction (PGD) is a major consequence of lung ischemia-reperfusion injury (IRI) and is a leading cause of early morbidity and mortality following lung transplantation. In vitro studies have associated transient receptor potential vanilloid 4 (TRPV4; calcium-permeable cation channel) activation with lung injury via endothelial barrier disruption. Using a murine model, we previously demonstrated that endothelial TRPV4 channels mediate lung IRI and that pretreatment of mice with a selective TRPV4 inhibitor, GSK2193874 (GSK), attenuated lung IRI. Thus, we tested the hypothesis that treatment of the recipient animal with GSK would attenuate lung IRI in a clinically relevant porcine lung transplant model.

Methods: A porcine left-lung transplant model of lung IRI was utilized. Animals were randomized in a blinded fashion to two treatment groups: vehicle or GSK. Donor lungs underwent 30 min of warm ischemia, 24 hrs of cold ischemia, left lung allotransplantation, and 4 hrs of reperfusion. Vehicle or GSK (1.0 mg/kg IV infusion) was administered to the recipient beginning at time of recipient lung explant. Left lung function, lung injury scores by H&E histology, edema (lung wet/dry weight), inflammatory markers (by ELISA), and neutrophil infiltration were compared.

Results: A total of 10 animals were utilized (n=5/group). After transplantation, the GSK group showed a significant improvement in left lung-specific pulmonary vein PO2 at both 3 and 4 hours of reperfusion (p<0.05; Figure). Lung compliance trended higher and wet/dry weight ratio trended lower in the GSK group but were not statistically significant. Expression of HMGB1 (damage-associated molecular pattern molecule) and P-selectin (endothelial cell adhesion molecule) in lungs, as well as Ang-2 (marker of endothelial activation or injury) in plasma, were significantly reduced in the GSK group (p=0.02). Neutrophil infiltration (p=0.01) and lung injury score (p=0.04) were significantly reduced in the GSK group.

Conclusions: In this pre-clinical, large animal model of lung transplant recipients treated with TRPV4 inhibitor at time of transplant significantly improved lung function, and attenuated lung injury and endothelial disruption after transplant. Iterative in vitro and in vivo studies conducted by our lab suggest that selective antagonism of TRPV4 channels may be an effective therapeutic strategy to prevent PGD after transplant, leading to improved long-term outcomes.

Raymond Strobel (1), Huy Ta (1), Andrew Young (2), Alex Wisniewski (3), Anthony Norman (1), Evan Rotar (4), Mark Stoler (1), Irving Kron (1), Swapnil Sonkusare (1), Mark Roeser (5), Victor Laubach (1), (1) University of Virginia, Charlottesville, VA, (2) University of Virginia, United States, (3) N/A, United States, (4) N/A, Perrysburg, OH, (5) UVA, Charlottesville, VA

Ankit Bharat

Commentator

Ankit Bharat is the Harold L. and Margaret N. Method Professor of Surgery, Chief of Thoracic Surgery, and the Executive Director of the Canning Thoracic Institute at Northwestern University in Chicago. He received medical training at Christian Medical College in India following which he joined Washington University in St Louis. There, he completed general surgery residency and cardiothoracic surgery fellowship as well as a post-doctoral research fellowship. At Northwestern, he treats patients with advanced thoracic diseases and provides therapies such as lung transplantation and extracorporeal membrane oxygenation to those with end-stage lung failure. In addition, he provides minimally invasive treatment to patients with thoracic malignancies including robotic and video-assisted thoracoscopic surgery. His NIH funded basic science laboratory investigates immunopathogenesis of lung disease with a focus on transplant immunobiology. Using research tools such as single cell transcriptomics, top-down proteomics, intravital imaging, and multichannel flow-cytometry, in combination with bioinformatics and computational biology, his research group is interested in identifying clinically actionable mechanisms underlying lung injury and utilizing models relevant to human disease. His laboratory is also interested in intravital imaging of immune responses after transplantation to determine the mechanisms of neutrophil recruitment into the lungs. He pursues problem-based surgical research by taking important clinical problems to the basic laboratory and their clinical lung transplant program allows his research team to validate their laboratory findings in humans.

Raymond Strobel

Abstract Presenter

Ray Strobel is a third-year integrated cardiothoracic surgery resident at the University of Virginia. His research focuses on the intersection of health policy and outcomes.

Specialties: Multi-Specialty, Thoracic