Inhibition of c-Jun NH2-Terminal Kinase Activity Improves Ischemia/Reperfusion Injury in Rat Lungs

Abstract

Although c-Jun NH2-terminal kinase (JNK) has been implicated in the pathogenesis of transplantation-induced ischemia/reperfusion (I/R) injury in various organs, its significance in lung transplantation has not been conclusively elucidated. We therefore attempted to measure the transitional changes in JNK and AP-1 activities in I/R-injured lungs. Subsequently, we assessed the effects of JNK inhibition by the three agents including SP600125 on the degree of lung injury assessed by means of various biological markers in bronchoalveolar lavage fluid and histological examination including detection of apoptosis. In addition, we evaluated the changes in p38, extracellular signal-regulated kinase, and NF-κB-DNA binding activity. I/R injury was established in the isolated rat lung preserved in modified Euro-Collins solution at 4°C for 4 h followed by reperfusion at 37°C for 3 h. We found that AP-1 was transiently activated during ischemia but showed sustained activation during reperfusion, leading to significant lung injury and apoptosis. The change in AP-1 was generally in parallel with that of JNK, which was activated in epithelial cells (bronchial and alveolar), alveolar macrophages, and smooth muscle cells (bronchial and vascular) on immunohistochemical examination. The change in NF-κB qualitatively differed from that of AP-1. Protein leakage, release of lactate dehydrogenase and TNF-α into bronchoalveolar lavage fluid, and lung injury were improved, and apoptosis was suppressed by JNK inhibition. In conclusion, JNK plays a pivotal role in mediating lung injury caused by I/R. Therefore, inhibition of JNK activity has potential as an effective therapeutic strategy for preventing I/R injury during lung transplantation.

Constitutive Activity of JNK2α2 Is Dependent on a Unique Mechanism of MAPK Activation

“…Many of the commercially available JNK inhibitors are small molecule, ATP competitive inhibitors such as SP600125. This particular inhibitor was found to reduce lung injury caused by ischemia/reperfusion and alleviate damage from smoke inhalation, illustrating the potential of JNK inhibitors as therapeutic drugs (28). Although there has been some success with the ATP competitive inhibitors, some problems have arisen because of their promiscuous nature.…”

SP600125, a selective JNK inhibitor, aggravates hepatic ischemia-reperfusion injury

“…For example, the attenuation of hepatic I/R injury by a p38 MAPK inhibitor identifies p38 M APK as a therapeutic target in I/R injury (Kobayashi et al, 2002). JNK has also been suggested as a therapeutic target in reperfusion injury of major organs, such as the brain (Gao et al, 2005) and the lung (Ishii et al, 2004) because it was found that chemical JNK inhibitors attenuate reperfusion injury in these organs. Uehara et al, (2005) recently reported that several novel JNK inhibitors successfully attenuated hepatic I/R injury and increased the survival rate of rats subjected to partial hepatic I/R and resectioning of the remaining non-ischemic lobes.…”

“…SP600125, a reversible ATP-competitive inhibitor, selectively inhibits JNK activity (Bennett et al, 2001), reduces ischemia-reperfusion injury in the brain (Gao et al, 2005) and the lungs (Ishii et al, 2004), and protects hepatocytes from apoptosis due to TNF- (Marderstein et al, 2003). Therefore, we attempted to determine whether SP600125 attenuates hepatic I/R injury in vivo using a partial hepatic I/R model in mice.…”

Regulation of Lipopolysaccharide-Induced Lung Inflammation by Plasminogen Activator Inhibitor-1 through a JNK-Mediated Pathway

“…The MAPK JNK is activated upon exposure to a broad range of stimuli, including osmotic stress (34), heat shock (34), IL-1␤ (35), and TNF-␣ (36), and we have shown recently that JNK is activated in LPS-stimulated neutrophils (37). In addition, a role for JNK in regulating pulmonary inflammation has been suggested recently by our group and others, in that systemic inhibition of JNK decreased acute inflammation after LPS (38), stretch (39), or ischemia-reperfusioninduced lung injury (40). Activation of JNK increases PAI-1 expression in vitro (41,42), and although other mechanisms were proposed for the decrease in acute inflammation with JNK inhibition in the above studies, the role of JNK in mediating PAI-1 expression suggests that JNK activation may increase PAI-1 expression in vivo, and that an increase in PAI-1 levels may be one mechanism regulating pulmonary neutrophil recruitment in models of lung inflammation.…”