Cardiac macrophage migration inhibitory factor inhibits JNK pathway activation and injury during ischemia/reperfusion
Dake Qi, … , Richard Bucala, Lawrence H. Young
Dake Qi, … , Richard Bucala, Lawrence H. Young
Published November 16, 2009
Citation Information: J Clin Invest. 2009;119(12):3807-3816. https://doi.org/10.1172/JCI39738.
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Research Article Cardiology

Cardiac macrophage migration inhibitory factor inhibits JNK pathway activation and injury during ischemia/reperfusion

Abstract

Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine that also modulates physiologic cell signaling pathways. MIF is expressed in cardiomyocytes and limits cardiac injury by enhancing AMPK activity during ischemia. Reperfusion injury is mediated in part by activation of the stress kinase JNK, but whether MIF modulates JNK in this setting is unknown. We examined the role of MIF in regulating JNK activation and cardiac injury during experimental ischemia/reperfusion in mouse hearts. Isolated perfused Mif–/– hearts had greater contractile dysfunction, necrosis, and JNK activation than WT hearts, with increased upstream MAPK kinase 4 phosphorylation, following ischemia/reperfusion. These effects were reversed if recombinant MIF was present during reperfusion, indicating that MIF deficiency during reperfusion exacerbated injury. Activated JNK acts in a proapoptotic manner by regulating BCL2-associated agonist of cell death (BAD) phosphorylation, and this effect was accentuated in Mif–/– hearts after ischemia/reperfusion. Similar detrimental effects of MIF deficiency were observed in vivo following coronary occlusion and reperfusion in Mif–/– mice. Importantly, excess JNK activation also was observed after hypoxia-reoxygenation in human fibroblasts homozygous for the MIF allele with the lowest level of promoter activity. These data indicate that endogenous MIF inhibits JNK pathway activation during reperfusion and protects the heart from injury. These findings have clinical implications for patients with the low-expression MIF allele.

Authors

Dake Qi, Xiaoyue Hu, Xiaohong Wu, Melanie Merk, Lin Leng, Richard Bucala, Lawrence H. Young

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Figure 5

JNK pathway activation and myocardial injury in WT and Mif–/– mice following ischemia/reperfusion in vivo.

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JNK pathway activation and myocardial injury in WT and Mif–/– mice follo...
WT and Mif–/– mice were subjected to sham thoracotomy (sham) or 20 minutes of left coronary artery ligation, followed by 3 hours of reperfusion. (A) Plasma MIF concentration after reperfusion was measured by ELISA. (B) The cardiac content of MIF was assessed by immunoblots. Quantification of the immunoblot is shown in the graphs below the blot. (C) JNK, c-Jun, cleaved PARP, and Bad were assessed in homogenates from the ischemia/reperfusion region by immunoblotting with phospho-specific and total antibodies. (D) WT and Mif–/– mice were pretreated with SP600125 (SP) (1 mg/kg) (ischemia/reperfusion plus SP600125) or vehicle (ischemia/reperfusion) intravenously, 15 minutes prior to coronary occlusion-reperfusion. Hearts were fixed and apoptotic nuclei were identified by TUNEL staining (original magnification, ×40). Additional hearts were dual stained with TTC and blue dye to identify viable myocardium versus necrosis within the ischemic region. (E) The ischemic risk area was expressed as percentage of the heart; infarct size was expressed as percentage of ischemic risk area. (F) Plasma troponin I was measured at the end of control or ischemia/reperfusion experiments. n = 4 per group; *P < 0.05 versus sham; #P < 0.05 versus WT.