Glucocorticoid pretreatment protects cardiac function and induces cardiac heat shock protein 72

Acute administration of glucocortiocoids reduces inflammation. Increasing knowledge of the mechanisms of action indicate that pretreatment with glucocorticoids could have organ-protective effects. We investigated whether pretreatment with methylprednisolone (MP) protected the heart against ischemia-reperfusion dysfunction, and we hypothetized that this protection might be due to induction of the cardioprotective heat shock protein 72 (HSP72). Rats were given vehicle or MP-40 mg/kg im as a double injection starting either 24 or 120 h (5 days) before their hearts were excised for Langendorff perfusion ( n = 6–11 hearts in each group). MP improved left ventricular function and coronary flow during reperfusion after 30 min of global ischemia and reduced infarct size. Cardiac HSP72 gradually increased in a 24-h time course after MP treatment, and the increase was sustained 5 days afterward (immunoblotting). HSP72 mRNA was either reduced or unchanged, indicating a posttranscriptional regulation. Pretreatment with hydrocortisone or dexamethasone ( n = 7–8 hearts of each) similarily increased cardiac HSP72 24 h afterward. This paper demonstrates that glucocorticoids increase cardiac HSP72 and protect organ function against ischemia-reperfusion injury.

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Heat Shock Protein 72 Enhances Manganese Superoxide Dismutase Activity During Myocardial Ischemia-Reperfusion Injury, Associated With Mitochondrial Protection and Apoptosis Reduction

Circulation ◽

10.1161/01.cir.0000032880.55215.92 ◽

2002 ◽

Vol 106 (12_suppl_1) ◽

Author(s):

Ken Suzuki ◽

Bari Murtuza ◽

Ivan A. Sammut ◽

Najma Latif ◽

Jay Jayakumar ◽

...

Keyword(s):

Superoxide Dismutase ◽

Heat Shock ◽

Heat Shock Protein ◽

Reperfusion Injury ◽

Manganese Superoxide Dismutase ◽

Ischemia Reperfusion Injury ◽

Ischemia Reperfusion ◽

Left Ventricular ◽

Heat Shock Protein 72 ◽

Manganese Superoxide

Background Heat shock protein 72 (HSP72) is known to provide myocardial protection against ischemia-reperfusion injury by its chaperoning function. Target molecules of this effect are presumed to include not only structural proteins but also other self-preservation proteins. The details, however, remain unknown. Manganese superoxide dismutase (Mn-SOD) is an enzyme that preserves mitochondria, a key organelle for cellular respiration, from reperfusion injury and limits mitochondria-related apoptosis. We hypothesized that Mn-SOD would play a role in HSP72-mediated cardioprotection. Methods and Results Rat hearts were transfected with human HSP72 by intra-coronary infusion of Hemagglutinating Virus of Japan-liposome, resulting in global myocardial overexpression of HSP72. After ischemia-reperfusion injury, cardiac function (left ventricular systolic pressure, maximum dP/dt, minimum dP/dt, and coronary flow) was improved in the HSP72-transfected hearts compared with control-transfected ones, corresponding with less leakage of creatine kinase and mitochondrial aspartate aminotransferase. Postischemic Mn-SOD content and activity in the HSP72-transfected hearts were enhanced in comparison with the controls (content: 96.9±4.1 versus 85.5±2.5% to the preischemic level, P =0.038; activity: 93.9±2.2 versus 82.2±3.7%, P =0.022), associated with improved mitochondrial respiratory function (postischemic percent respiratory control index; NAD + -linked: 81.3±3.8 versus 18.5±4.4%; FAD-linked: 71.8±5.5 versus 20.7±5.3%, P <0.001). In addition, incidence of postischemic cardiomyocyte apoptosis was attenuated in the HSP72-transfected hearts (4.0±1.1 versus 10.3±3.3%, P =0.036), correlating with an increased Bcl-2 level and reduced up-regulation of caspase-3. Conclusions These data suggest that the enhanced Mn-SOD activity during ischemia-reperfusion injury, which is associated with mitochondrial protection and apoptosis reduction, is a possible mechanism of HSP72-induced cardioprotection.

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