Free radicals and heat shock protein in the heart

Probiotics: multifarious oral vaccine against infectious traumas

Microorganisms have been used for a long time in food and alcoholic fermentation. In the last few years they have undergone scientific scrutiny of their preventative and therapeutic aspects. This has led to the discovery of a new term, probiotics. Lactic acid bacteria (LAB) are microbial communities normally present in the intestine of most animals. They play an important role in humans and other animals, and act as immunomodulators. They are helpful in the treatment and prevention of disease as well as improving the digestion and absorption of nutrients. Probiotic microorganisms include the LAB Lactobacillus acidophilus, Lactobacillus bulgaricus, Lactobacillus casei, Lactobacillus plantarum and Lactobacillus rhamnosus. Use of these live bacteria to elicit an immune response or to carry a vaccine component is a new invention in vaccine development. The advantage of live bacterial vaccines is that they mimic natural infection, have intrinsic adjuvant properties and can be given orally. Components of pathogenic and nonpathogenic food-related microorganisms are currently being evaluated as candidates for oral vaccines.

Oral administration of Lactobacillus induces cardioprotection

OBJECTIVES

Our goal was to investigate the potential of oral administration of Lactobacillus to induce cardioprotection against ischemia-reperfusion injury in rat hearts, and to determine whether this protection is associated with myocardial catalase activation and heat shock protein 70 expression.

DESIGN

Lactobacillus was administered orally to rats on a daily basis, from 1 to 21 days before global ischemia. Global ischemia was produced by full-stop flow in isolated Langendorff-perfused rat hearts for 20 minutes and was followed by reperfusion. Similarly, saline was administered to control animals.

RESULTS

Lactobacillus significantly reduced reperfusion tachyarrhythmia and improved functional recovery of the ischemic rat hearts. These cardioprotective effects were associated with reduction of norepinephrine release at the first minute of reperfusion, activation of myocardial catalase, and overexpression of 70 kd heat stress protein at ischemia and reperfusion (p < 0.05).

CONCLUSIONS

Oral administration of Lactobacillus produces marked cardioprotection against ischemia-reperfusion injury. This effect is attributed to activation of the cellular defense system, manifested by activation of the antioxidant pathway, and by expression of protective proteins. Norepinephrine is involved in this process. The results of this study suggest that Lactobacillus, which is generally considered safe, could serve as a basis for the development of a new agent for preventive therapy of various ischemic heart syndromes.

An essential role of the antioxidant gene Bcl-2 in myocardial adaptation to ischemia: an insight with antisense Bcl-2 therapy

Reperfusion of ischemic myocardium results in apoptotic cell death, which can be blocked by adapting the heart to ischemic stress induced by cyclic episodes of brief periods of ischemia and reperfusion. In concert, the antiapoptotic gene bcl-2 is decreased by ischemia/reperfusion, but increased in the ischemically adapted myocardium. To examine if bcl-2 plays a crucial role in cardioprotection, adaptive cardioprotection was further examined in the hearts treated with antisense bcl-2 oligodeoxynucleotides (ODN). Isolated Langendorff-perfused rat hearts were divided into three groups: control (perfused with Krebs-Henseleit bicarbonate buffer for 210 min); 30-min ischemia followed by 2-h reperfusion; ischemic adaptation followed by 30-min ischemia and 2-h reperfusion. The last (adapted heart) group was subdivided into another two groups: one was transfected 48 h earlier with antisense bcl-2 ODN, whereas the other group was transfected with sense bcl-2 ODN. Cardioprotection was examined by determining cardiomyocyte death due to necrosis and apoptosis. Antisense gene therapy almost completely abolished bcl-2 protein expression in the hearts. Bcl-2 mRNA was down-regulated in the ischemic/reperfused heart, but up-regulated in the adapted myocardium. Adapted myocardium showed decreased infarct size and reduced number of apoptotic cardiomyocytes. Ischemia/reperfusion resulted in increased oxidative stress as evidenced by increased malonaldehyde formation. Adapted myocardium had a reduced amount of malonaldehyde. Antisense bcl-2 ODN completely abolished the cardioprotective effects of adaptation by eliminating the antideath signal of bcl-2. In concert, reduced oxidative stress in the adapted myocardium no longer persisted. The results suggest an antioxidant role of bcl-2 that appeared to be essential for the cardioprotection achieved by ischemic adaptation.

Improved myocardial preservation with short hyperthermia prior to cold cardioplegic ischemia in immature rabbit hearts

OBJECTIVE

Recent observations have been shown that the induction and accumulation of heat shock proteins (HSPs) by short exposure to nonlethal whole-body hyperthermia with normothermic recovery are closely associated with transient resistance to subsequent ischemia-reperfusion challanges. Here, this study was performed to investigate whether a shortly heat shock pretreatment affects the left ventricular (LV) function after cold cardioplegic ischemia in reperfused neonatal rabbit hearts.

METHODS

Hearts from neonatal New Zealand White rabbits were isolated perfused (working heart preparation) and exposed to 2 h of cold cardioplegic ischemia followed by reperfusion for 60 min. To induce the heat shock response neonatal rabbits (n=5, HT-group) were subjected to whole-body hyperthermia at 42.0-42.5 degrees C for 15 min, followed by a normothermic recovery period of 60 min, before harvesting and the onset of global hypothermic cardioplegic arrest. Another set of hearts (n=5, control group) without a heat treatment underwent a similar perfusion and ischemia protocol served as control. The postischemic recovery was assessed by measuring several parameters of LV function. LV biopsies from all control and heat treated animals were taken before ischemia and at the end of reperfusion to examine myocardial HSP levels by Western blot analysis.

RESULTS

At 60 min of reperfusion the HT-group showed significant better recovery of ventricular function such as LV developed pressure (DP) (74.6+/-10 vs. 52.1+/-8.5%, P<0.05), LV positive dP/dt (910+/-170 vs. 530+/-58 mmHg/s, P<0.01) and LV end-diastolic pressure (LVEDP) (8+/-2 vs. 18.4+/-5 mmHg, P<0.05) than control. Myocardial oxygen consumption (MVO(2)) was significantly higher in the HT-group compared with control (0.054+/-0.006 vs. 0.041+/-0.002 ml/g per min, P<0.05). Significant postreperfusion lower level in lactate production was observed in the HT-group (0.83+/-0.11 vs. 1.67+/-0.8 mmol/l, P<0.05). Also, the recovery of hemodynamic parameters such as aortic flow, coronary flow and cardiac output was significantly superior (P<0.05) in the HT-group. Furthermore, high expression of HSP72(+)/73(+) were detected in the myocardial tissue samples of heat-treated rabbits by immunoblotting, appearing even at 60 min of normothermic recovery after heat stress.

CONCLUSIONS

These data in the immature rabbit heart indicate that previous shortly heat treatment with high level expression of heat shock proteins (HSP72(+)/73(+)) before hypothermic cardioplegic ischemia provides transient tolerance against myocardial injury and could be an improvement for the postischemic functional recovery of neonatal hearts.

A new method of long-term preventive cardioprotection using Lactobacillus

Potential long-term cardioprotection was investigated in an extensive experimental study. Lactobacillus cultivation components (LCC) were administered intravenously in anesthetized rats 1, 7, and 21 days before global ischemia (GI). GI was produced by full stop flow in isolated Langendorff-perfused hearts for 20 min and was followed by reperfusion. Control animals were injected with saline. LCC reduced reperfusion tachyarrhythmia significantly and improved functional recovery of the ischemized rat heart. These beneficial effects were associated with reduction of release of norepinephrine (NE) and prostacyclin at the first minute of reperfusion, activation of myocardial catalase, and overexpression of 70-kDa heat stress protein (HSP-70) at ischemia and reperfusion (P < 0.05). This cardioprotection was documented up to 21 days after a single injection of LCC. Thus Lactobacillus cultivation components are new nontoxic materials that produce marked long-term cardioprotection against ischemia-reperfusion damage. This effect is attributed to an activation of the cellular defense system, manifested by activation of the antioxidant pathway and by expression of protective proteins. NE is involved in this process, and the data also suggest a role for prostacyclin in this model of cardioprotection. The potential of LCC and related compounds working through similar mechanisms in the prevention and therapy of various ischemic heart syndromes should be explored.