NFkappaB activation during ischemia/reperfusion in heart: friend or foe?

Effect of cardiopulmonary bypass on cytokine network and myocardial cytokine production

BACKGROUND

In addition to the well-investigated proinflammatory cytokine expression, there is an ever increasing interest in the field of anti-inflammatory response to cardiopulmonary bypass (CPB). Evidence suggests that myocardium serves as an important source of cytokines during reperfusion and application of CPB. The effect of coronary artery bypass graft (CABG) without CPB on myocardial cytokine production has not as yet been investigated.

HYPOTHESIS

Cardiopulmonary bypass can cause long-term disturbance in pro- and anti-inflammatory cytokine balance, which may impede a patient's recovery following surgery. Therefore, the effect of CPB on the balance of the pro-/anti-inflammatory cytokines network and myocardial cytokine outflow was assessed throughout a longer period after surgery.

METHODS

Twenty patients were scheduled for CABG with CPB and 10 had off-pump surgery. Blood samples were taken before, during, and over the first week following surgery. Coronary sinus blood samples were collected during surgery. The ratio of pro- and anti-inflammatory cytokines was calculated and the cytokine concentration of peripheral and coronary sinus blood were compared in both groups.

RESULTS

Pro-/anti-inflammatory cytokine ratio decreased early after CPB followed by a delayed and marked increase. A more balanced ratio was present following off-pump surgery. Coronary sinus levels of certain cytokines exceeded the concentration of systemic blood in the course of CPB but not during off-pump operation.

CONCLUSION

Patients show pro-inflammatory predominant cytokine balance at a later stage after CPB in contrast to those without CPB. The heart produces a remarkable amount of cytokines only in the course of surgery with CPB.

Activation of nuclear factor-kappaB and its proinflammatory mediator cascade in the infarcted rat heart

Nuclear transcription factor (NF)-kappaB regulates inflammatory and immune responses by increasing the expression of specific inflammatory genes in various tissues. Whether the infarcted heart includes the activation of NF-kappaB and a proinflammatory mediator cascade that it regulates has not been fully explored. Herein, we monitored the temporal and spatial activation of NF-kappaB, together with expression of tumor necrosis factor (TNF)-alpha, vascular cell adhesion molecule-1 (VCAM-1), and transforming growth factor (TGF)-beta(1), in the infarcted rat heart at and remote to MI from day 3 to day 28 following left coronary artery ligation. Compared to the normal heart, we observed NF-kappaB activation, together with the elevated expression of VCAM-1 in endothelial cells, TNF-alpha and TGF-beta(1) in inflammatory cells at sites of repair in the infarcted heart, which started on day 3, peaked on day 7, and gradually declined thereafter. Our findings suggest NF-kappaB activation and its proinflammatory mediator cascade are contributory to the inflammatory response and remodeling that appear at various sites of repair in the infarcted rat heart.

Antioxidants in myocardial ischemia-reperfusion injury: therapeutic potential and basic mechanisms

Oxidative stress is a constant threat to all living organisms and an immense repertoire of cellular defense systems is being employed by most pro- and eukaryotic systems to eliminate or to attenuate oxidative stress. Ischemia and reperfusion is characterized by both a significant oxidative stress and characteristic changes in the antioxidant defense. By focusing on this antioxidant response of the cardiovascular system in the setting of ischemia-reperfusion injury, the aim of this review was threefold. First, based on recent animal experiments and clinical studies we shall discuss how endogenous antioxidants respond to oxidative stress during ischemia-reperfusion injury and highlight the results of recent trials on the ability of antioxidants to modulate ischemia-reperfusion injury. In this aspect, we will particularly focus on the emerging concept that various lines of antioxidant defenses do not act individually but are linked to each other in a systematic relationship as part of an antioxidant network. It is well known that enzymatic mechanisms are important components of the endogenous antioxidant repertoire; however, the relative importance of the different enzyme systems and isoforms has been much debated. The second part will focus on recent suggestions attributing a potentially key role of mitochondrial MnSOD in cardiac ischemia-reperfusion injury. Finally, the third part of the review will critically examine how endogenous antioxidants might regulate the complex signal transduction pathways of cellular activation with particular attention to the NF-kappaB and MAPK systems that appears to determine outcome of injury, survival, and adaptation.

Protein kinase C-delta mediates adenosine A3 receptor-induced delayed cardioprotection in mouse

We investigated the role of protein kinase C in adenosine A3 receptor (A3AR)-induced delayed cardioprotection in the mouse heart. Mice were treated with selective A3AR agonist N6-(3-iodobenzyl)adenosine-5'-N-methyluronamide (IB-MECA). Twenty-four hours later, hearts were perfused in the Langendorff mode and subjected to 30 min of global ischemia and 30 min of reperfusion. Infarct size was determined by computer morphometry of tetrazolium-stained sections, and ventricular function was monitored by inserting a fluid-filled balloon into the left ventricle (LV). Chelerythrine chloride (CHE, 5.0 mg/kg) and rottlerin (Rot, 0.3 mg/kg) were given 30 min before IB-MECA to block total and PKC-delta isoforms, respectively. IB-MECA caused postischemic reduction in necrosis and improvement in ventricular function, which was abolished by CHE. Western blot analysis demonstrated translocation of the PKC-delta isoform but not the alpha, epsilon, xi, eta isoform(s) from cytoplasm to the membrane fraction after 30 min of IB-MECA administration. A3AR antagonist MRS-1191 and CHE blocked the translocation of PKC-delta. Furthermore, IB-MECA-induced increase in nuclear factor-kappaB binding was diminished by CHE. These results provide direct evidence of an essential role of PKC, and more specifically, PKC-delta in A3AR-induced delayed cardioprotection.