Remote ischemic preconditioning: a novel protective method from ischemia reperfusion injury--a review. J Surg Res. 2008;150:304-330. [PMID: 19040966 DOI: 10.1016/j.jss.2007.12.747]

Heme oxygenase-1 mediates the protective effects of ischemic preconditioning on mitigating lung injury induced by lower limb ischemia-reperfusion in rats

BACKGROUND

Lower limb ischemia-reperfusion (I/R) imposes oxidative stress, elicits inflammatory response, and subsequently induces acute lung injury. Ischemic preconditioning (IP), a process of transient I/R, mitigates the acute lung injury induced by I/R. We sought to elucidate whether the protective effects of IP involve heme oxygenase-1 (HO-1).

METHODS

Adult male rats were randomized to receive I/R, I/R plus IP, I/R plus IP plus the HO-1 inhibitor tin protoporphyrin (SnPP) (n = 12 in each group). Control groups were run simultaneously. I/R was induced by applying rubber band tourniquet high around each thigh for 3 h followed by reperfusion for 3 h. To achieve IP, three cycles of bilateral lower limb I/R (i.e., ischemia for 10 min followed by reperfusion for 10 min) were performed. IP was performed immediately before I/R. After sacrifice, degree of lung injury was determined.

RESULTS

Histologic findings, together with assays of leukocyte infiltration (polymorphonuclear leukocytes/alveoli ratio and myeloperoxidase activity) and lung water content (wet/dry weight ratio), confirmed that I/R induced acute lung injury. I/R also caused significant inflammatory response (increases in chemokine, cytokine, and prostaglandin E(2) concentrations), imposed significant oxidative stress (increases in nitric oxide and malondialdehyde concentrations), and up-regulated HO-1 expression in lung tissues. IP significantly enhanced HO-1 up-regulation and, in turn, mitigated oxidative stress, inflammatory response, and acute lung injury induced by I/R. In addition, the protective effects of IP were counteracted by SnPP.

CONCLUSIONS

The protective effects of IP on mitigating acute lung injury induced by lower limb I/R are mediated by HO-1.

Methods for studying redox cycling of thioredoxin in mediating preconditioning-induced survival genes and proteins

Recent advances in molecular biology provide methods and tools for studying cell signaling pathways underlying hormetic mechanisms produced by radiation hormesis, ischemic, remote ischemic, and chemical preconditioning as well as withholding of nutrients and/or trophic factors. Most of the proposed key signaling pathways of hormetic mechanisms remain to be elucidated. For the investigation of possible role of thiol redox signaling systems in hormesis, a serum deprivation preconditioned human cell model, free radical assays, and molecular biological methods are employed for studying whether free radicals, the NO-cGMP-PKG cell signaling pathway, and the redox protein thioredoxin (Trx) play any roles in the hormetic mechanism against cytotoxicity caused by serum deprivation and also neurotoxin 1-methyl-4-phenyltetrahydropyridinium ion (MPP(+)). This NO-dependent cell signaling pathway of the redox protein Trx may play a key role in the cellular protective mechanism of several potential neuroprotective agents such as S-nitrosoglutathione (GSNO), 17beta-estradiol, selegiline as well as ebeselen, sildenafil, and rasagiline. Consistently, exogenously administrated Trx (<1 microM) provides a concentration-dependent protection for human neuroblasts against MPP(+)-induced oxidative injury. This newly discovered role of the redox protein of Trx in preconditioning-induced cell signaling and protection could lead to the development of new lead compounds for upregulation of Trx and related thiol redox proteins for cell survival, repair, proliferation, and neuronal plasticity.

Hydrogen sulfide and oxygen sensing in the cardiovascular system

Vertebrate cardiorespiratory homeostasis is inextricably dependent upon specialized cells that provide feedback on oxygen status in the tissues, blood, and on occasion, environment. These "oxygen sensing" cells include chemoreceptors and oxygen-sensitive chromaffin cells that initiate cardiorespiratory reflexes, vascular smooth muscle cells that adjust perfusion to metabolism or ventilation, and other cells that condition themselves in response to episodic hypoxia. Identification of how these cells sense oxygen and transduce this into the appropriate physiological response has enormous clinical applicability, but despite intense research there is no consensus regarding the initial hypoxia-effector coupling mechanism. This review examines an alternative mechanism of oxygen sensing using oxidation of endogenously produced hydrogen sulfide (H(2)S) as the O(2)-sensitive couple. Support for this hypothesis includes the similarity of effects of hypoxia and H(2)S on a variety of tissues, augmentation of hypoxic responses by precursors of H(2)S production and their inhibition by inhibitors of H(2)S synthesis, and the rapid consumption of H(2)S by O(2) in the range of intracellular/mitochondrial Po(2). These studies also indicate that, under normoxic conditions, it is doubtful that free H(2)S has longer than a transient existence in tissue or extracellular fluid.

Effects of remote ischemic preconditioning on biochemical markers and neurologic outcomes in patients undergoing elective cervical decompression surgery: a prospective randomized controlled trial

BACKGROUND

Remote ischemic preconditioning (RIPC) may protect the spinal cord from ischemic injury. This randomized clinical trial was designed to assess whether a large clinical trial testing the effect of RIPC on neurologic outcome in patients undergoing spine surgery is warranted. This trial was registered with ClinicalTrials.gov, number NCT00778323.

METHODS

Forty adult cervical spondylotic myelopathy patients undergoing elective decompression surgery were randomly assigned to either the RIPC group (n=20) or the control group (n=20). Limb RIPC consisted of three 5-minutes cycles of upper right limb ischemia with intervening 5-minute periods of reperfusion. Neuron-specific enolase and S-100B levels were measured in serum at set time points. Median nerve somatosensory-evoked potentials (SEPs) were also recorded. Neurologic recovery rate was evaluated using a Japanese Orthopaedic Association scale.

RESULTS

RIPC significantly reduced serum S-100B release at 6 hours and 1 day after surgery, and reduced neuron-specific enolase release at 6 hours, and then at 1, 3, and 5 days after surgery. No differences were observed in SEP measurements or the incidence of SEP changes during surgery between the control and RIPC groups. Recovery rate at 7 days, and at 1 and 3 months after surgery was higher in the RIPC group than in the control group (P<0.05).

CONCLUSIONS

Our results for markers of neuronal ischemic injury and rate of recovery suggest that a clinical trial with sufficient statistical power to detect an effect of RIPC on the incidence of neurologic complications (paresis, palsy, etc) due to spinal cord ischemia-reperfusion injury after spine surgery is warranted [corrected].

Remote ischemic preconditioning by hindlimb occlusion prevents liver ischemic/reperfusion injury: the role of High Mobility Group-Box 1

INTRODUCTION

Hepatocellular injury caused by ischemia-reperfusion of the liver occurs in a number of clinical situations including major trauma, elective surgery of the liver, and liver transplantation. Several strategies have been used to prevent liver injury following ischemia-reperfusion (I/R). Among these, ischemic preconditioning has shown promise as a preventative approach. In this manuscript, we hypothesized that use of remote ischemic preconditioning by brief hindlimb ischemia might prevent liver dysfunction in a mouse model of liver I/R.

METHODS

C57/B mice were subjected to 60 minutes of partial liver ischemia with or without antecedent hindlimb vascular I/R. Blood was drawn for serum alanine aminotransferase levels at times following liver reperfusion. Liver inflammation was assessed by measuring serum and liver tumor necrosis factor (TNF)-alpha protein and mRNA. The role of toll-like receptor 4 (TLR4) in mediating protection was determined using the mouse strain HeJ, which has a mutated TLR4.

RESULTS

Antecedent hindlimb ischemia (10 minutes) lessened I/R-induced elevation of serum alanine aminotransferase compared with untreated I/R animals. This protection correlated with a reduction in serum TNF-alpha protein levels as well as liver TNF-alpha mRNA and apoptosis. High Mobility Group-Box 1 (HMG-B1) levels in the blood were elevated after hindlimb ischemia and injection of HMG-B1 prior to liver recapitulated the protective effect of hindlimb occlusion. TLR4-mutant HeJ mice did not demonstrate protection with hindlimb preconditioning.

CONCLUSIONS

Brief hindlimb occlusion prevents liver I/R injury. This effect appears to be related to release of HMG-B1 and is dependent on the presence of a functional TLR4. Remote ischemia preconditioning represents a novel approach to preventing distant organ injury.

Translation of remote ischaemic preconditioning into clinical practice

Reduction of the burden of ischaemia-reperfusion injury is the aim of most treatments for cardiovascular and cerebrovascular disease. Although many strategies have proven benefit in the experimental arena, few have translated to clinical practice. Scientific and practical reasons might explain this finding, but the unpredictability of acute ischaemic syndromes is one of the biggest obstacles to timely application of novel treatments. Remote ischaemic preconditioning-which is a powerful innate mechanism of multiorgan protection that can be induced by transient occlusion of blood flow to a limb with a blood-pressure cuff-could be close to becoming a clinical technique. Several proof-of-principle and clinical trials have been reported, suggesting that the technique has remarkable promise. We examine the history, development, and present state of remote preconditioning in cardiovascular disease.

Hind limb ischemic preconditioning induces an anti-inflammatory response by remote organs in rats

Ischemic preconditioning (IPC), a strategy used to attenuate ischemia-reperfusion injury, consists of brief ischemic periods, each followed by reperfusion, prior to a sustained ischemic insult. The purpose of the present study was to evaluate the local and systemic anti-inflammatory effects of hind limb IPC in male Wistar rat (200-250 g) models of acute inflammation. IPC was induced with right hind limb ischemia for 10 min by placing an elastic rubber band tourniquet on the proximal part of the limb followed by 30 min of reperfusion. Groups (N = 6-8) were submitted to right or left paw edema (PE) with carrageenan (100 microg) or Dextran (200 microg), hemorrhagic cystitis with ifosfamide (200 mg/kg, ip) or gastric injury (GI) with indomethacin (20 mg/kg, vo). Controls received similar treatments, without IPC (Sham-IPC). PE is reported as variation of paw volume (mL), vesical edema (VE) as vesical wet weight (mg), vascular permeability (VP) with Evans blue extravasation (microg), GI with the gastric lesion index (GLI; total length of all erosions, mm), and neutrophil migration (NM) from myeloperoxidase activity. The statistical significance (P < 0.05) was determined by ANOVA, followed by the Tukey test. Carrageenan or Dextran-induced PE and VP in either paw were reduced by IPC (42-58.7%). IPC inhibited VE (38.8%) and VP (54%) in ifosfamide-induced hemorrhagic cystitis. GI and NM induced by indomethacin were inhibited by IPC (GLI: 90.3%; NM: 64%). This study shows for the first time that IPC produces local and systemic anti-inflammatory effects in models of acute inflammation other than ischemia-reperfusion injury.

Partial hindlimb occlusion reduced the susceptibility to sustained ventricular tachycardia in conscious rats

Remote conditioning induced by ischemia in distant organs protects the heart from ischemia/reperfusion injury; however, its effect on ischemia-induced ventricular arrhythmias is unknown. Therefore, we tested the hypothesis that partial hindlimb occlusion during coronary artery occlusion increases the ventricular arrhythmia threshold (VAT) induced by coronary artery occlusion. Rats (n = 7) were instrumented with a radio-telemetry device for recording arterial pressure, electrocardiogram (ECG), and body temperature. A Doppler ultrasonic flow probe and vascular occluder were placed around the terminal aorta. Finally, a snare was placed around the left main coronary artery. The VAT was determined without and, on an alternate day, during partial hindlimb occlusion (remote conditioning) in conscious rats. Without remote conditioning, the VAT was 4.56 + 0.15 minutes. Importantly, remote conditioning significantly increased the VAT (6.29 + 0.49 minutes), suggesting that ischemia in a distant organ may delay the development of ischemia-induced ventricular arrhythmias.

Signaling pathways of cardioprotective ischemic preconditioning

BACKGROUND

Ischemia/reperfusion (I/R) injury is a major contributory factor to cardiac dysfunction and infarct size that determines patient prognosis after acute myocardial infarction. During the last 20 years, since the appearance of the first publication on ischemic preconditioning (IP), our knowledge of this phenomenon has increased exponentially.

RESULTS AND CONCLUSION

Basic scientific experiments and preliminary clinical trials in humans suggest that IP confers resistance to subsequent sustained ischemic insults not only in the regional tissue but also in distant organs (remote ischemic preconditioning), which may provide a simple, cost-effective means of reducing the risk of perioperative myocardial ischemia. The mechanism may be humoral, neural, or a combination of both, and involves adenosine, bradykinin, protein kinases and K(ATP) channels, although the precise end-effector remains unclear. This review describes different signaling pathways involved in acute ischemic preconditioning in detail.