Effects of broad band electromagnetic fields on HSP70 expression and ischemia-reperfusion in rat hearts

Forcing the Antitumor Effects of HSPs Using a Modulated Electric Field

The role of Heat Shock Proteins (HSPs) is a “double-edged sword” with regards to tumors. The location and interactions of HSPs determine their pro- or antitumor activity. The present review includes an overview of the relevant functions of HSPs, which could improve their antitumor activity. Promoting the antitumor processes could assist in the local and systemic management of cancer. We explore the possibility of achieving this by manipulating the electromagnetic interactions within the tumor microenvironment. An appropriate electric field may select and affect the cancer cells using the electric heterogeneity of the tumor tissue. This review describes the method proposed to effect such changes: amplitude-modulated radiofrequency (amRF) applied with a 13.56 MHz carrier frequency. We summarize the preclinical investigations of the amRF on the HSPs in malignant cells. The preclinical studies show the promotion of the expression of HSP70 on the plasma membrane, participating in the immunogenic cell death (ICD) pathway. The sequence of guided molecular changes triggers innate and adaptive immune reactions. The amRF promotes the secretion of HSP70 also in the extracellular matrix. The extracellular HSP70 accompanied by free HMGB1 and membrane-expressed calreticulin (CRT) form damage-associated molecular patterns encouraging the dendritic cells’ maturing for antigen presentation. The process promotes killer T-cells. Clinical results demonstrate the potential of this immune process to trigger a systemic effect. We conclude that the properly applied amRF promotes antitumor HSP activity, and in situ, it could support the tumor-specific immune effects produced locally but acting systemically for disseminated cells and metastatic lesions.

Effects of radiofrequency electromagnetic radiation emitted from a mobile phone base station on the redox homeostasis in different organs of Swiss albino mice

This study was designed to investigate the possible effects of exposure to mobile phone base station (MPBS) emits 1800-MHz RF-EMR on some oxidative stress parameters in the brain, heart, kidney and liver of Swiss albino mice under exposures below thermal levels. Mice were randomly assigned to three experimental groups which were exposed to RF-EMR for 6 hr/day, 12 hr/day and 24 hr/day for 45 consecutive days, respectively, and a control group. The glutathione (GSH) levels and activities of glutathione-s-transferase (GST) and superoxide dismutase (SOD) were significantly reduced in mice brain after exposure to RF-EMR for 12 hr and 24 hr per day. Exposure of mice to RF-EMR for 12 hr and 24 hr per day also led to a significant increase in malondialdehyde (an index of lipid peroxidation) levels in mice brain. On the contrary, exposures used in this study did not induce any significant change in various oxidative stress-related parameters in the heart, kidney and liver of mice. Our findings showed no significant variations in the activities of aspartate amino-transferase (AST), alanine amino-transferase (ALT), and on the level of creatinine (CRE) in the exposed mice. This study also revealed a decrease in RBC count with an increase in WBC count in mice subjected to 12 hr/day and 24 hr/day exposures. Exposure to RF-EMR from MPBS may cause adverse effects in mice brain by inducing oxidative stress arising from the generation of reactive oxygen species (ROS) as indicated by enhanced lipid peroxidation, and reduced levels and activities of antioxidants.

Ethanol exposure in prenatal and early postnatal induced cardiac injury in rats: involvement of oxidative stress, Hsp70, ERK 1/2, JNK, and apoptosis in a 3-month follow-up study

Alcohol exposure during pregnancy induces a wide range of structural and functional abnormalities in the fetal heart. However, the underlying mechanism of this phenomenon is not well known. This study was undertaken to elucidate probable mechanisms of myocardial damage induced by prenatal and early postnatal ethanol treatment. Pregnant Wistar rats received ethanol 4.5 g/kg BW once per day from the seventh day of gestation (GD7) throughout lactation. The oxidative stress injury of the myocardium in pups was evaluated by measuring levels of oxidative stress biomarkers. Histopathological examinations and Western blot were performed to evaluate histological features, apoptosis, and molecular alterations in the myocardial tissue of male pups on the postnatal day 21 (PN-21) and postnatal day 90 (PN-90). The results showed that maternal ethanol consumption caused oxidative stress (impaired total antioxidant capacity and malondialdehyde), histological changes, and apoptosis of the myocardium in the pups on PN-21 and PN-90. At the molecular levels, Western blot analysis revealed that ethanol modulated the protein expression of p-ERK1/2, p-JNK, and Hsp70 in the myocardial tissue of the pups after 21 and 90 days of birth compared with the controls. These findings revealed that maternal ethanol intake induced cardiac toxicity in part, mediated by oxidative stress and apoptosis in the pups. A further mechanism study revealed that ethanol enhanced ERK1/2 and JNK phosphorylation and Hsp70 protein expression.

Tyrosol prevents ischemia/reperfusion-induced cardiac injury in H9c2 cells: involvement of ROS, Hsp70, JNK and ERK, and apoptosis

Ischemia-Reperfusion (I/R) injury causes ROS overproduction, creating oxidative stress, and can trigger myocyte death, resulting in heart failure. Tyrosol is an antioxidant abounded in diets and medicine. Our objective was to investigate the protective effect of tyrosol on I/R-caused mortality in H9c2 cardiomyocytes through its influence on ROS, Hsp70, ERK, JNK, Bcl-2, Bax and caspase-8. A simulated I/R model was used, myocytes loss was examined by MTT, and ROS levels were measured using DCFH-DA. Nuclear condensation and caspase-3 activity were assessed by DAPI staining and fluorometric assay. Phosphorylated ERK and JNK were determined by electrochemiluminescent ELISA, and Hsp70, Bcl-2, Bax and caspase-8 were examined by Western blotting. Results show that tyrosol salvaged myocyte loss, inhibited nuclear condensation and caspase-3 activity dose-dependently, indicating its protection against I/R-caused myocyte loss. Furthermore, tyrosol significantly inhibited ROS accumulation and activation of ERK and JNK, augmenting Hsp70 expression. Besides, tyrosol inhibited I/R-induced apoptosis, associated with retained anti-apoptotic Bcl-2 protein, and attenuated pro-apoptotic Bax protein, resulting in a preservation of Bcl-2/Bax ratio. Finally, tyrosol notably decreased cleaved caspase-8 levels. In conclusion, cytoprotection of tyrosol in I/R-caused myocyte mortality was involved with the mitigation of ROS, prohibition of the activation of ERK, JNK and caspase-8, and elevation of Hsp70 and Bcl-2/Bax ratio.

Molecular Biology of Apoptosis in Ischemia and Reperfusion

This study reviews the current understanding of the mechanisms that mediate the complex processes involved in apoptosis secondary to ischemia and reperfusion (I/R) and is not intended as a complete literature review of apoptosis. Several biochemical reactions trigger a cascade of events, which activate caspases. These caspases exert their effect through downstream proteolysis until the final effector caspases mediate the nuclear features characteristic of apoptosis, DNA fragmentation and condensation. Within the context of ischemia, the hypoxic environment initiates the expression of several genes involved in inflammation, the immune response, and apoptosis. Many of these same genes are activated during reperfusion injury in response to radical oxygen species generation. It is plausible that inhibition of specific apoptotic pathways via inactivation or downregulation of those genes responsible for the initiation of inflammation, immune response, and apoptosis may provide promising molecular targets for ameliorating reperfusion injury in I/R-related processes. Such inhibitory mechanisms are discussed in this review. Important targets in I/R-related pathologies include the brain during stroke, the heart during myocardial infarction, and the organs during harvesting and/or storage for transplantation. In addition, we present data from our ongoing research of specific signal transduction-related elements and their role in ischemia/reperfusion injury. These data address the potential therapeutic application of anti-inflammatory and anti-ischemic compounds in the prevention of I/R damage.

Mild exercise training, cardioprotection and stress genes profile

To improve current knowledge of the molecular mechanisms underlying exercise-induced cardioprotection in a rat model of mild exercise training, Sprague-Dawley rats were trained to run on a treadmill up to 55% of their maximal oxygen uptake for 1 h/day, 3 days/week, 14 weeks, with age-matched sedentary controls (n = 20/group). Rats were sacrificed 48 h after the last training session. Despite lack of cardiac hypertrophy, training decreased blood hemoglobin (7.94 +/- 0.21 mM vs. 8.78 +/- 0.23 mM, mean +/- SE, P = 0.01) and increased both plasma malondialdehyde (0.139 +/- 0.005 mM vs. 0.085 +/- 0.009 mM, P = 0.05) and the activity of Mn-superoxide dismutase (11.6 +/- 0.6 vs. 16.5 +/- 1.6 mU/microg, P = 0.01), whereas total superoxide dismutase activity was unaffected. When subjected to 30-min ischemia followed by 90-min reperfusion, hearts from trained rats (n = 5) displayed reduced infarct size as compared to controls (37.26 +/- 0.92% vs. 49.09 +/- 2.11% of risk area, P = 0.04). The biochemical analyses in the myocardium, which included gene expression profiles, real-time PCR, Western blot and determination of enzymatic activity, showed training-induced upregulation of the following mRNAs and/or proteins: growth-arrest and DNA-damage induced 153 (GADD153/CHOP), heme-oxygenase-1 (HO-1), cyclooxygenase-2 (Cox-2), heat-shock protein 70/72 (HSP70/72), whereas heat-shock protein 60 (HSP60) and glucose-regulated protein 75 (GRP75) were decreased. As a whole, these data indicate that mild exercise training activates a second window of myocardial protection against ischemia/reperfusion by upregulating a number of protective genes, thereby warranting further investigation in man.

The influence of extremely low frequency magnetic fields on cytoprotection and repair

Ischemia-reperfusion injuries, such as those suffered from various types of cardiovascular disease, are major causes of death and disability. For relatively short periods of ischemia, much of the damage is potentially reversible and in fact, does not occur until the influx of oxygen during the reperfusion stage. Because of this, there is a window of opportunity to protect the ischemic tissue. Here, we review several mechanisms of protection, such as heat shock proteins, opioids, collateral blood flow, and nitric oxide induction, and the evidence indicating that magnetic fields may be used as a means of providing protection via each of these mechanisms. While there are few studies demonstrating direct protection with magnetic field therapies, there are a number of published reports indicating that electromagnetic fields may be able to influence some of the biochemical systems with protective applications.