Intratracheal administration of p38α short-hairpin RNA plasmid ameliorates lung ischemia-reperfusion injury in rats

BACKGROUND: Lung ischemia-reperfusion injury (LIR1) remains a significant problem after lung transplantation. A crucial signaling enzyme involved in inflammation and apoptosis during LIR1 is p38 mitogen-activated protein kinase (MAPK). Gene silencing of p38 alpha by short hairpin RNA (shRNA) can downregulate p38 alpha expression. The lungs have an extremely large surface area, which makes the absorption of shRNA highly effective. Therefore, we evaluated the therapeutic efficacy of p38 alpha shRNA plasmids in a rat model of lung transplantation. METHODS: The delivery of p38 alpha shRNA plasmid was performed by intratracheal administration 48 hours before transplantation into donor rats. Control animals received scrambled shRNA plasmids. Reverse-trariscription polymerase chain reaction and Western blots were used to assess gene silencing efficacy. The therapeutic effects of shRNA plasmids were evaluated by lung function tests. We determined the levels of inflammatory cytokines, the level of intercellular adhesion molecule 1 (ICAM-1), c-Myc mRNA expression, and ICAM-1 protein expression, and the presence of cell apoptosis. RESULTS: Rats administered p38 alpha shRNA plasmids showed a significant downregulation in lung expression of p38 alpha transcripts and protein levels. Compared with the control group, the p38 alpha shRNA group showed a higher pulmonary vein oxygen level, lower wet weight-to-dry weight ratio, lower lung injury score, and lower serum levels of tumor necrosis factor-alpha, interleukin-6, and interleukin-8. Messenger RNA levels of ICAM-1 and c-Myc in the p38 alpha shRNA group were dramatically lower than in the control group. Levels of ICAM-1 protein expression exhibited a similar trend. Cell apoptosis decreased in the p38 alpha shRNA group vs the control group. CONCLUSION: Intratracheal administration of p38 alpha shRNA plasmids provided therapeutic effects in a rat model of lung transplantation. J Heart Lung Transplant 2012;31:655-62 Crown Copyright (C) 2012 Published by Elsevier Inc. on behalf of the International Society for Heart and Lung Transplantation. All rights reserved.