NADPH Oxidase in Bone Marrow–Derived Cells Mediates Pulmonary Ischemia-Reperfusion Injury

Abstract

Reactive oxygen species (ROS) play a crucial role in ischemiareperfusion (IR) injury after lung transplantation. We hypothesized that NADPH oxidase derived from bone marrow (BM) cells contributes importantly to lung IR injury. An in vivo mouse model of lung IR injury was employed. Wild-type C57BL/6 (WT) mice, p47 phox knockout (p47 phox 2/2) mice, or chimeras created by BM transplantation between WT and p47 phox 2/2 mice were assigned to either Sham (left thoracotomy) or six study groups that underwent IR (1 h left hilar occlusion and 2 h reperfusion). After reperfusion, pulmonary function was assessed using an isolated, buffer-perfused lung system. Lung injury was assessed by measuring vascular permeability (via Evans blue dye), edema, neutrophil infiltration (via myeloperoxidase [MPO]), lipid peroxidation (via malondialdyhyde [MDA]), and expression of proinflammatory cytokines. Lung IR resulted in significantly increased MDA in WT mice, indicative of oxidative stress. WT mice treated with apocynin (an NADPH oxidase inhibitor) and p47 phox 2/2 mice displayed significantly reduced pulmonary dysfunction and injury (vascular permeability, edema, MPO, and MDA). In BM chimeras, significantly reduced pulmonary dysfunction and injury occurred after IR in p47 phox 2/2/WT chimeras (donor/recipient) but not WT/p47 phox 2/2 chimeras. Induction of TNF-a, IL-17, IL-6, RANTES (CCL5), KC (CXCL1), MIP-2 (CXCL2), and MCP-1 (CCL2) was significantly reduced after IR in NADPH oxidase-deficient mice and p47 phox 2/2/WT chimeras but not WT/p47 phox 2/2 chimeras. These results indicate that NADPH oxidase-generated ROS specifically from BM-derived cells contributes importantly to lung IR injury. NADPH oxidase may represent a novel therapeutic target for the treatment of IR injury after lung transplantation.

Apocynin attenuates ventilator-induced lung injury in an isolated and perfused rat lung model

“…Use of apocynin blocks MAPK signal transduction and attenuates apoptotic cell death by blocking intrinsic and extrinsic signaling pathways during ischemia and reperfusion injury [30][31][32][33][34][35][36][37]. Several studies [21,38,39] have shown organ protective effects of apocynin by inhibition of cyclooxygenase metabolites in a variety of animal models.…”

NOX Enzymes and Pulmonary Disease

“…phox knockout mice, wildtype mice, and chimeras created by bone marrow transplantation indicate that NOX-generated ROS, specifically from bone marrow-derived cells, contribute to lung ischemia= reperfusion injury (148). Furthermore, recent studies indicate that activation of an EC-associated NOX may be the primary mechanism for ROS generation during reoxygenation after lung ischemia (5,152).…”

Models of Lung Transplant Research: a consensus statement from the National Heart, Lung, and Blood Institute workshop

“…neutrophil/mononuclear phagocyte activation and infiltration) (30), and proinflammatory cytokines and chemokines (7,8,15,20,24), all exemplifying multiple complex inflammatory pathways involved in PGD.…”