Heme oxygenase-1 induction by the clinically used anesthetic isoflurane protects rat livers from ischemia/reperfusion injury

Protective effect of propofol compared with sevoflurane on liver function after hepatectomy with Pringle maneuver: A randomized clinical trial

While the Pringle maneuver reduces intraoperative blood loss in hepatectomies, this technique can also be hepatotoxic. Hepatectomies require general anesthesia with propofol or volatile anesthetics like sevoflurane, agents known to offer multi-organ protection. However, their clinical effect after liver resection is unclear. We aimed to assess the effect of the two anesthetics on post-hepatectomy liver damage via measuring liver function tests. Fifty-six patients who underwent elective hepatectomies with the Pringle maneuver due to metastatic hepatic masses were preoperatively randomized to be anesthetized by sevoflurane or propofol. The primary and secondary outcomes were the postoperative peak levels of aspartate transaminase (AST) and alanine transaminase (ALT), respectively. Patients anesthetized by propofol exhibited significantly lower transaminases than those given sevoflurane (AST, p = 0.005; ALT, p = 0.006). The former agent significantly affected postoperative transaminases (AST hazard ratio -192.2, 95% confidence interval [-332.1 to -52.4], p = 0.00; ALT hazard ratio -140.2, 95% confidence interval [-240.0 to -40.7], p = 0.007). In conclusion, propofol had a greater hepatoprotective effect than sevoflurane as assessed by postoperative transaminases after hepatectomy with Pringle maneuver for metastatic liver tumors.

Brain DNA damaging effects of volatile anesthetics and 1 and 2 Gy gamma irradiation in vivo: Preliminary results

Although both can cause DNA damage, the combined impact of volatile anesthetics halothane/sevoflurane/isoflurane and radiotherapeutic exposure on sensitive brain cells in vivo has not been previously analyzed. Healthy Swiss albino male mice (240 in total, 48 groups) were exposed to either halothane/sevoflurane/isoflurane therapeutic doses alone (2 h); 1 or 2 gray of gamma radiation alone; or combined exposure. Frontal lobe brain samples from five animals were taken immediately and 2, 6, and 24 h after exposure. DNA damage and cellular repair index were analyzed using the alkaline comet assay and the tail intensity parameter. Elevated tail intensity levels for sevoflurane/halothane were the highest at 6 h and returned to baseline within 24 h for sevoflurane, but not for halothane, while isoflurane treatment caused lower tail intensity than control values. Combined exposure demonstrated a slightly halothane/sevoflurane protective and isoflurane protective effect, which was stronger for 2 than for 1 gray. Cellular repair indices and tail intensity histograms indicated different modes of action in DNA damage creation. Isoflurane/sevoflurane/halothane preconditioning demonstrated protective effects in sensitive brain cells in vivo. Owing to the constant increases in the combined use of radiotherapy and volatile anesthetics, further studies should explore the mechanisms behind these effects, including longer and multiple exposure treatments and in vivo brain tumor models.

Short-term inhalation of isoflurane improves the outcomes of intraportal hepatocyte transplantation

Clinical hepatocyte transplantation (HTx) is only performed without general anesthesia, while inhalation anesthetics are usually used in animal experiments. We hypothesized that isoflurane may be a possible reason for the discrepancy between the results of animal experiments and the clinical outcomes of HTx. Syngeneic rat hepatocytes (1.0 × 10⁷) were transplanted to analbuminemic rats with (ISO group) and without (AW group) isoflurane. The serum albumin, AST, ALT, LDH levels and several inflammatory mediators were analyzed. Immunohistochemical staining and ex vivo imaging were also performed. The serum albumin levels of the ISO group were significantly higher in comparison to the AW group (p < 0.05). The serum AST, ALT, LDH levels of the ISO group were significantly suppressed in comparison to the AW group (p < 0.0001, respectively). The serum IL-1β, IL-10, IL-18, MCP-1, RNTES, Fractalkine and LIX levels were significantly suppressed in the ISO group. The ischemic regions of the recipient livers in the ISO group tended to be smaller than the AW group; however, the distribution of transplanted hepatocytes in the liver parenchyma was comparable between the two groups. Isoflurane may at least in part be a reason for the discrepancy between the results of animal experiments and the clinical outcomes of HTx.

DNA damage assessment in peripheral blood of Swiss albino mice after combined exposure to volatile anesthetics and 1 or 2 Gy radiotherapy in vivo

PURPOSE

Patient immobilization by general volatile anesthesia (VA) may be necessary during medical radiology treatment, and its use has increased in recent years. Although ionizing radiation (IR) is a well-known genotoxic and cytotoxic agent, and VA exposure has caused a range of side effects among patients and occupationally exposed personnel, there are no studies to date comparing DNA damage effects from combined VA and single fractional IR dose exposure.

MATERIAL AND METHODS

We investigate whether there is a difference in white blood cells DNA damage response (by the alkaline comet assay) in vivo in 185 healthy Swiss albino mice divided into 37 groups, anesthetized with isoflurane/sevoflurane/halothane and exposed to 1 or 2 Gy of IR. Blood samples were taken after 0, 2, 6 and 24 h after exposure, and comet parameters were measured: tail length, tail intensity and tail moment. The cellular DNA repair index was calculated to quantify the efficiency of cells in repairing and re-joining DNA strand breaks following different treatments.

RESULTS

In combined exposures, halothane caused higher DNA damage levels that were dose-dependent; sevoflurane damage increase did not differ significantly from the initial 1 Gy dose, and isoflurane even demonstrated a protective effect, particularly in the 2 Gy dose combined exposure. Nevertheless, none of the exposures reached control levels even after 24 h.

CONCLUSION

Halothane appears to increase the level of radiation-induced DNA damage, while sevoflurane and isoflurane exhibited a protective effect. DNA damage may have been even greater in target organs such as liver, kidney or even the brain, and this is proposed for future study.

Nanotheranostics for the Management of Hepatic Ischemia-Reperfusion Injury

Hepatic ischemia-reperfusion injury (IRI), in which an insufficient oxygen supply followed by reperfusion leads to an inflammatory network and oxidative stress in disease tissue to cause cell death, always occurs after liver transplantations and sections. Although pharmacological treatments favorably prevent or protect the liver against experimental IRI, there have been few successes in clinical applications for patient benefits because of the incomprehension of complicated IRI-induced signaling events as well as short blood circulation time, poor solubility, and severe side reactions of most antioxidants and anti-inflammatory drugs. Nanomaterials can achieve targeted delivery and controllable release of contrast agents and therapeutic drugs in desired hepatic IRI regions for enhanced imaging sensitivity and improved therapeutic effects, emerging as novel alternative approaches for hepatic IRI diagnosis and therapy. In this review, the application of nanotechnology is summarized in the management of hepatic IRI, including nanomaterial-assisted hepatic IRI diagnosis, nanoparticulate systems-mediated remission of reactive oxygen species-induced tissue injury, and nanoparticle-based targeted drug delivery systems for the alleviation of IRI-related inflammation. The current challenges and future perspectives of these nanoenabled strategies for hepatic IRI treatment are also discussed.

Isoflurane reduces septic neuron injury by HO‑1‑mediated abatement of inflammation and apoptosis

Sepsis-associated encephalopathy (SAE) frequently occurs in critically ill patients with severe systemic infections. Subanesthetic isoflurane (0.7% ISO) possesses anti-inflammatory, antioxidant and anti-apoptotic properties against a number of human diseases, including brain injury. The activation of heme oxygenase-1 (HO-1) impedes inflammation, oxidation and apoptosis, thus alleviating sepsis-induced brain damage. However, whether 0.7% ISO affords protection against septic neuronal injury involving HO-1 activation is unclear. The present study aimed to investigate the neuroprotective effects of 0.7% ISO and its potential underlying mechanisms in SAE using a mouse model established by cecal ligation and puncture (CLP). The results indicated that the expression and activity of HO-1 in the mouse hippocampus were increased by CLP, and further enhanced by ISO. ISO reduced the death rate, brain water content and blood-brain barrier disruption, but improved the learning and memory functions of CLP-treated mice. ISO significantly decreased the production of pro-inflammatory cytokines and the levels of oxidative indictors in the serum and hippocampus, as well as the number of apoptotic neurons and the expression of pro-apoptotic proteins in the hippocampus. Inversely, anti-inflammatory factors, antioxidative enzymes and anti-apoptotic proteins were markedly increased by ISO administration. However, the neuroprotective effects of ISO were abolished by a HO-1 inhibitor. Overall, these findings suggested that 0.7% ISO alleviated SAE via its anti-inflammatory, antioxidative and anti-apoptotic properties, which involved the activated form of HO-1.

Distinctive effect of anesthetics on the effect of limb remote ischemic postconditioning following ischemic stroke

Limb remote ischemic postconditioning (LRIP) has been reported as an effective method to reduce the induced experimental stroke damage after ischemic reperfusion (IR) injury. Studies suggest that anesthetics used during induction of ischemic stroke can reduce IR injury, which could affect the actual mechanisms of neuroprotection by LRIP. This study focuses on the comparative effects of anesthetics such as isoflurane and ketamine-xylazine on ischemic injury when used during LRIP. Adult C57BL/6 mice were anesthetized by isoflurane or halothane, and transient middle cerebral artery occlusion (MCAO) was induced through insertion of the filament. Under isoflurane or ketamine-xylazine anesthesia, LRIP was performed after 90 min of reperfusion by carrying out three cycles of 5 min ischemia/5 min reperfusion of the bilateral hind limbs for one session per day for a total of 3 days. Results showed that the use of different anesthetics—isoflurane or ketamine-xylazine—during LRIP had no effects on body weight. However, LRIP was able to improve neurological function as observed by the neurological deficit score in ischemic mice. Interestingly, the neurological deficit in the group where ketamine-xylazine was used was better than the group where isoflurane was used during LRIP. Furthermore, the LRIP was able to prolong the period of the ischemic mice on the rotarod and this effect was more significant in the groups where ketamine-xylazine was used during LRIP. Moreover, LRIP significantly attenuated the infarction volume; however, this effect was independent of the anesthetic used during LRIP. From these results, we conclude that ischemic mice that were subjected to LRIP under ketamine-xylazine anesthesia had better neurological deficit outcomes after stroke.

Heme oxygenase-1 regulates autophagy through carbon-oxygen to alleviate deoxynivalenol-induced hepatic damage

Deoxynivalenol (DON) cannot be totally removed due to its stable chemical characteristics and chronic exposure to low doses of DON causes significant toxic effects in humans and animals. However, the potential hazard of such low-dose exposure in target organs still remains not completely understood, especially in liver, which is mainly responsible for detoxification of DON. In the present study, we demonstrated for the first time that estimated human daily DON exposure (25 μg/kg bw) for 30 and 90 days caused low-grade inflammatory infiltration around hepatic centrilobular veins, elevated systemic IL-1β, IL-6 and TNF-α and impaired liver function evidenced by increased serum ALT activity. At the molecular level, expressions of autophagy-related proteins as well as Cleaved Caspase-3 and Cleaved Caspase-7 were upregulated during DON exposure, which indicated the activation of autophagy and apoptosis. Importantly, AAV-mediated liver-specific overexpression of HO-1 reversed DON-induced liver damages, upregulated autophagy and attenuated apoptosis in liver, while AAV-mediated HO-1 silence aggravated DON-induced liver damages, inhibited autophagy and increased apoptosis. Furthermore, in vitro experiments demonstrated that lentivirus-mediated HO-1 overexpression in Hepa 1-6 cells prolonged the duration of autophagy and delayed the onset of apoptosis. HO-1 silence in Hepa 1-6 cells inhibited activation of autophagy and accelerated occurrence of apoptosis, and these could be recovered by CO pre-treatment. Therefore, we suppose that HO-1 might be a potential research target to protect human and animal from liver injuries induced by low dose of DON exposure.

Protective Role of mTOR in Liver Ischemia/Reperfusion Injury: Involvement of Inflammation and Autophagy

Liver ischemia/reperfusion (IR) injury is a common phenomenon after liver resection and transplantation, which often results in liver graft dysfunction such as delayed graft function and primary nonfunction. The mammalian target of rapamycin (mTOR) is an evolutionarily highly conserved serine/threonine protein kinase, which coordinates cell growth and metabolism through sensing environmental inputs under physiological or pathological conditions, involved in the pathophysiological process of IR injury. In this review, we mainly present current evidence of the beneficial role of mTOR in modulating inflammation and autophagy under liver IR to provide some evidence for the potential therapies for liver IR injury.

The Role of Heme Oxygenase-1 in Remote Ischemic and Anesthetic Organ Conditioning

The cytoprotective effects of the heme oxygenase (HO) pathway are widely acknowledged. These effects are mainly mediated by degradation of free, pro-oxidant heme and the generation of carbon monoxide (CO) and biliverdin. The underlying mechanisms of protection include anti-oxidant, anti-apoptotic, anti-inflammatory and vasodilatory properties. Upregulation of the inducible isoform HO-1 under stress conditions plays a crucial role in preventing or reducing cell damage. Therefore, modulation of the HO-1 system might provide an efficient strategy for organ protection. Pharmacological agents investigated in the context of organ conditioning include clinically used anesthetics and sedatives. A review from Hoetzel and Schmidt from 2010 nicely summarized the effects of anesthetics on HO-1 expression and their role in disease models. They concluded that HO-1 upregulation by anesthetics might prevent or at least reduce organ injury due to harmful stimuli. Due to its clinical safety, anesthetic conditioning might represent an attractive pharmacological tool for HO-1 modulation in patients. Remote ischemic conditioning (RIC), first described in 1993, represents a similar secure option to induce organ protection, especially in its non-invasive form. The efficacy of RIC has been intensively studied herein, including on patients. Studies on the role of RIC in influencing HO-1 expression to induce organ protection are emerging. In the first part of this review, recently published pre-clinical and clinical studies investigating the effects of anesthetics on HO-1 expression patterns, the underlying signaling pathways mediating modulation and its causative role in organ protection are summarized. The second part of this review sums up the effects of RIC.

Sevoflurane Protects Hepatocytes From Ischemic Injury by Reducing Reactive Oxygen Species Signaling of Hepatic Stellate Cells: Translational Findings Based on a Clinical Trial

BACKGROUND

Randomized controlled trials (RCTs) data demonstrate that sevoflurane postconditioning improves clinical outcomes of liver resection with inflow occlusion, presumably due to hepatocyte protection from ischemic injury. However, mechanisms remain unclear. This study examines liver biopsy samples obtained in an RCT of sevoflurane postconditioning to test the hypothesis that sevoflurane attenuates hepatocyte apoptosis.

METHODS

Messenger ribonucleic acid (mRNA) of pro- and antiapoptotic regulators Bax and B-cell lymphoma 2 (Bcl2) was examined in hepatic biopsies obtained during the RCT. Hepatic stellate cells (HSCs) and hepatocytes were exposed to hypoxia/reoxygenation (H/R) in vitro to evaluate the effect of sevoflurane postconditioning on apoptosis. The role of HSC as a potential apoptosis trigger in hepatocytes through the production of reactive oxygen species induced by H/R was explored by transferring supernatants from H/R-exposed HSC to hepatocytes as target cells.

RESULTS

In patients of the RCT, the Bax/Bcl2 mRNA ratio in liver tissue was markedly decreased in the sevoflurane arm (25% ± 21% reduction; P = .001). In vitro, H/R increased reactive oxygen species production in HSC by 33% ± 16% (P = .025), while it was abolished in the presence of sevoflurane (P < .001). In hepatocytes, caspase was minimally activated by H/R. However, incubation of hepatocytes with supernatants of HSC, previously exposed to H/R, increased caspase activity by 28% ± 13% (P < .001). When exposed to supernatants from HSC undergoing sevoflurane postconditioning, caspase activation in hepatocytes was reduced by 20% ± 9% (P < .001), similarly to the sevoflurane effect on the BAX/Bcl2 mRNA ratio in the liver samples.

CONCLUSIONS

The study shows that sevoflurane postconditioning affects apoptosis of hepatocytes after ischemia-reperfusion injury in patients. It also demonstrates that HSC may be the effector cells of sevoflurane protection.

Impact of inflammation on brain subcellular energetics in anesthetized rats

Background

Emerging data suggests that volatile anesthetic agents may have organ protection properties in the setting of critical illness. The purpose of this study was to better understand the effect of inflammation on cerebral subcellular energetics in animals exposed to two different anesthetic agents—a GABA agonist (propofol) and a volatile agent (isoflurane).

Results

Forty-eight Sprague–Dawley rats were anesthetized with isoflurane or propofol. In each group, rats were randomized to celiotomy and closure (sham) or cecal ligation and puncture (inflammation [sepsis model]) for 8 h. Brain tissue oxygen saturation and the oxidation state of cytochrome aa₃ were measured. Brain tissue was extracted using the freeze-blow technique. All rats experienced progressive increases in tissue oxygenation and cytochrome aa₃ reduction over time. Inflammation had no impact on cytochrome aa₃, but isoflurane caused significant cytochrome aa₃ reduction. During isoflurane (not propofol) anesthesia, inflammation led to an increase in lactate (+ 0.64 vs. − 0.80 mEq/L, p = 0.0061). There were no differences in ADP:ATP ratios between groups. In the isoflurane (not propofol) group, inflammation increased the expression of hypoxia-inducible factor-1α (62%, p = 0.0012), heme oxygenase-1 (67%, p = 0.0011), and inducible nitric oxide synthase (31%, p = 0.023) in the brain. Animals exposed to inflammation and isoflurane (but not propofol) exhibited increased expression of protein carbonyls (9.2 vs. 7.0 nM/mg protein, p = 0.0050) and S-nitrosylation (49%, p = 0.045) in the brain. RNA sequencing identified an increase in heat shock protein 90 and NF-κβ inhibitor mRNA in the inflammation/isoflurane group.

Conclusions

In the setting of inflammation, rats exposed to isoflurane show increased hypoxia-inducible factor-1α expression despite a lack of hypoxia, increased oxidative stress in the brain, and increased serum lactate, all of which suggest a relative increase in anaerobic metabolism compared to propofol. Differences in oxidative stress as well as heat shock protein 90 and NF-κβ inhibitor may account for the differential expression of cerebral hypoxia-inducible factor-1α during inflammation.

Electronic supplementary material

The online version of this article (10.1186/s12868-019-0514-8) contains supplementary material, which is available to authorized users.

BM‑MSCs protect against liver ischemia/reperfusion injury via HO‑1 mediated autophagy

Ischemia/reperfusion (I/R) injury is considered to be a contributing factor in liver injury following major hepatic resection or liver transplantation. Bone marrow mesenchymal stem cells (BM‑MSCs) have the potential to protect against liver I/R injury; however, the precise mechanisms have not been completely elucidated. Autophagy serves an important role in protecting against various injuries, including I/R injury. The present study aimed to determine the role of autophagy and its potential regulatory mechanism in BM‑MSC‑mediated protection against liver I/R injury in rats. The results demonstrated that BM‑MSCs mitigated I/R injury and enhanced autophagy in vivo. In addition, inhibition of autophagy by 3‑methyladenine reversed the positive effects of BM‑MSCs. Furthermore, heme oxygenase‑1 (HO‑1) expression was promoted by BM‑MSCs. Using zinc protoporphyrin IX to inhibit HO‑1 demonstrated that HO‑1 was important for the promotion of autophagy. In conclusion, the present study revealed that BM‑MSCs protected against liver I/R injury via the promotion of HO‑1‑mediated autophagy.

Anti-inflammatory Effects of Heme Oxygenase-1 Depend on Adenosine A2A- and A2B-Receptor Signaling in Acute Pulmonary Inflammation

Acute pulmonary inflammation is still a frightening complication in intensive care units. In our previous study, we determined that heme oxygenase (HO)-1 had anti-inflammatory effects in pulmonary inflammation. Recent literature has emphasized a link between HO-1 and the nucleotide adenosine. Since adenosine A_2A- and A_2B-receptors play a pivotal role in pulmonary inflammation, we investigated their link to the enzyme HO-1. In a murine model of pulmonary inflammation, the activation of HO-1 by hemin significantly decreased polymorphonuclear leukocyte (PMN) migration into the lung. This anti-inflammatory reduction of PMN migration was abolished in A_2A- and A_2B-knockout mice. Administration of hemin significantly reduced chemokine levels in the BAL of wild-type animals but had no effects in A_2A^-/- and A_2B^-/- mice. Microvascular permeability was significantly attenuated in HO-1-stimulated wild-type mice, but not in A_2A^-/- and A_2B^-/- mice. The activity of HO-1 rose after LPS inhalation in wild-type animals and, surprisingly, also in A_2A^-/- and A_2B^-/- mice after the additional administration of hemin. Immunofluorescence images of animals revealed alveolar macrophages to be the major source of HO-1 activity in both knockout strains—in contrast to wild-type animals, where HO-1 was also significantly augmented in the lung tissue. In vitro studies on PMN migration further confirmed our in vivo findings. In conclusion, we linked the anti-inflammatory effects of HO-1 to functional A_2A/A_2B-receptor signaling under conditions of pulmonary inflammation. Our findings may explain why targeting HO-1 in acute pulmonary inflammation has failed to prove effective in some patients, since septic patients have altered adenosine receptor expression.

The anti-inflammatory effects of E-α-(p-methoxyphenyl)-2',3,4,4'-tetramethoxychalcone are mediated via HO-1 induction

Inflammation plays a central role in the pathophysiology of many diseases. The inducible enzyme heme oxygenase-1 (HO-1) protects cells against inflammation and can be induced by electrophilic compounds like the chalcones (1,3-diphenylprop-2-enones) from the class of α,β-unsaturated carbonyl compounds. We hypothesized that the synthetic chalcone E-α-(p-methoxyphenyl)-2',3,4,4'-tetramethoxychalcone (E-α-p-OMe-C6H4-TMC) exerts anti-inflammatory effects in RAW264.7, Jurkat lymphocytes and HK-2 cells via HO-1 induction. RAW264.7 cells were treated with lipopolysaccharide prior to E-α-p-OMe-C6H4-TMC treatment. Subsequently, HO-1 protein induction and activity were analyzed, as well as expression of pro- and anti-inflammatory mediators, transcription factors and mitogen-activated protein kinases to evaluate the possible molecular mechanism. These results were confirmed in human cell lines (Jurkat T-lymphocytes and HK-2 epithelial cells). We found that the E-α-p-OMe-C6H4-TMC exerts significant anti-inflammatory effects in a dose dependent manner, showing no toxic effects in LPS-treated RAW264.7 macrophages. E-α-p-OMe-C6H4-TMC induced HO-1 and SOD-1 protein expression and HO-1 enzyme activity, reduced the upregulation of COX-2 and iNOS, while inducing the translocation of Nrf2. NF-κB activity was attenuated following E-α-p-OMe-C6H4-TMC treatment accompanied by the downregulation of proinflammatory cytokines IL-1β, IL-6 and MCP-1. Pretreatment with E-α-p-OMe-C6H4-TMC revealed significant changes in phosphorylation of ERK and p38, but not JNK. These anti-inflammatory effects of E-α-p-OMe-C6H4-TMC were approved in Jurkat and HK-2 cells, furthermore revealing a downregulation of IL-8 and IL-10. In conclusion, it is tempting to speculate about E-α-p-OMe-C6H4-TMC as a new and non-toxic agent, inducing HO-1 in cells. This opens up new opportunities regarding the development of therapeutic agents using beneficial effects of HO-1 and its products.

Transduced Heme Oxygenase-1 Fusion Protein Reduces Renal Ischemia/Reperfusion Injury Through Its Antioxidant and Antiapoptotic Roles in Rats

INTRODUCTION

Heme oxygenase-1 (HO-1) has a protective role against ischemia/reperfusion (I/R) injury.

METHODS

We produced an HO-1 fusion protein mediated by cell penetrated peptide PEP-1, also known as PEP-1-HO-1 fusion protein, and investigated its role in renal I/R injury in rats. Male Sprague-Dawley rats were subjected to 45 minutes of ischemia by occluding the bilateral renal arteries and 6 hours of reperfusion to prepare the model of renal I/R. Animals were randomized to receive PEP-1-HO-1 fusion protein or equal volume of physiologic saline 30 minutes before ischemia.

RESULTS

Administration of PEP-1-HO-1 fusion protein resulted in a significant increase in HO-1 expression. His-probe expression (1 part of the PEP-1-HO-1 fusion protein) was only observed in PEP-1-HO-1-treated animals. I/R caused renal dysfunction and increases in malondialdehyde level and cell apoptosis, and decreased superoxide dismutase activity. Treatment of PEP-1-HO-1 fusion protein reversed these changes. Furthermore, administration of PEP-1-HO-1 inhibited the I/R-induced increase in nuclear factor-κB activation.

CONCLUSIONS

These findings suggest that transduction of PEP-1-HO-1 attenuates renal I/R injury in rats, which might be partly attributable to its antioxidant and antiapoptotic effects.

New drug delivery system for liver sinusoidal endothelial cells for ischemia-reperfusion injury

AIM: To investigate the cytoprotective effects in hepatic ischemia-reperfusion injury, we developed a new formulation of hyaluronic acid (HA) and sphingosine 1-phophate.

METHODS: We divided Sprague-Dawley rats into 4 groups: control, HA, sphingosine 1-phosphate (S1P), and HA-S1P. After the administration of each agent, we subjected the rat livers to total ischemia followed by reperfusion. After reperfusion, we performed the following investigations: alanine aminotransferase (ALT), histological findings, TdT-mediated dUTP-biotin nick end labeling (TUNEL) staining, and transmission electron microscopy (TEM). We also investigated the expression of proteins associated with apoptosis, hepatoprotection, and S1P accumulation.

RESULTS: S1P accumulated in the HA-S1P group livers more than S1P group livers. Serum ALT levels, TUNEL-positive hepatocytes, and expression of cleaved caspase-3 expression, were significantly decreased in the HA-S1P group. TEM revealed that the liver sinusoidal endothelial cell (LSEC) lining was preserved in the HA-S1P group. Moreover, the HA-S1P group showed a greater increase in the HO-1 protein levels compared to the S1P group.

CONCLUSION: Our results suggest that HA-S1P exhibits cytoprotective effects in the liver through the inhibition of LSEC apoptosis. HA-S1P is an effective agent for hepatic ischemia/reperfusion injury.

The Cytoprotective Effects of E-α-(4-Methoxyphenyl)-2',3,4,4'-Tetramethoxychalcone (E-α-p-OMe-C6H4-TMC)--A Novel and Non-Cytotoxic HO-1 Inducer

Cell protection against different noxious stimuli like oxidative stress or chemical toxins plays a central role in the treatment of many diseases. The inducible heme oxygenase isoform, heme oxygenase-1 (HO-1), is known to protect cells against a variety of harmful conditions including apoptosis. Because a number of medium strong electrophiles from a series of α-X-substituted 2’,3,4,4’-tetramethoxychalcones (α-X-TMCs, X = H, F, Cl, Br, I, CN, Me, p-NO₂-C₆H₄, Ph, p-OMe-C₆H₄, NO₂, CF₃, COOEt, COOH) had proven to activate Nrf2 resulting in HO-1 induction and inhibit NF-κB downstream target genes, their protective effect against staurosporine induced apoptosis and reactive oxygen species (ROS) production was investigated. RAW264.7 macrophages treated with 19 different chalcones (15 α-X-TMCs, chalcone, 2’-hydroxychalcone, calythropsin and 2’-hydroxy-3,4,4’-trimethoxychalcone) prior to staurosporine treatment were analyzed for apoptosis and ROS production, as well as HO-1 protein expression and enzyme activity. Additionally, Nrf2 and NF-κB activity was assessed. We found that amongst all tested chalcones only E-α-(4-methoxyphenyl)-2’,3,4,4'-tetramethoxychalcone (E-α-p-OMe-C₆H₄-TMC) demonstrated a distinct, statistically significant antiapoptotic effect in a dose dependent manner, showing no toxic effects, while its double bond isomer Z-α-p-OMe-C₆H₄-TMC displayed no significant activity. Also, E-α-p-OMe-C₆H₄-TMC induced HO-1 protein expression and increased HO-1 activity, whilst inhibition of HO-1 by SnPP-IX abolished its antiapoptotic effect. The only weakly electrophilic chalcone E-α-p-OMe-C₆H₄-TMC reduced the staurosporine triggered formation of ROS, while inducing the translocation of Nrf2 into the nucleus. Furthermore, staurosporine induced NF-κB activity was attenuated following E-α-p-OMe-C₆H₄-TMC treatment. Overall, E-α-p-OMe-C₆H₄-TMC demonstrated its effective cytoprotective potential via a non-toxic induction of HO-1 in RAW264.7 macrophages. The observed cytoprotective effect may partly be related to both, the activation of the Nrf2- and inhibition of the NF-κB pathway.

Effects of propofol and isoflurane on haemodynamics and the inflammatory response in cardiopulmonary bypass surgery

Cardiopulmonary bypass (CPB) causes reperfusion injury that when most severe is clinically manifested as a systemic inflammatory response syndrome. The anaesthetic propofol may have anti-inflammatory properties that may reduce such a response. We hypothesised differing effects of propofol and isoflurane on inflammatory markers in patients having CBR Forty patients undergoing elective CPB were randomised to receive either propofol or isoflurane for maintenance of anaesthesia. CRP, IL-6, IL-8, HIF-1α (ELISA), CD11 and CD18 expression (flow cytometry), and haemoxygenase (HO-1) promoter polymorphisms (PCR/electrophoresis) were measured before anaesthetic induction, 4 hours post-CPB, and 24 hours later. There were no differences in the 4 hours changes in CRP, IL-6, IL-8 or CD18 between the two groups, but those in the propofol group had higher HIF-1α (P = 0.016) and lower CD11 expression (P = 0.026). After 24 hours, compared to the isoflurane group, the propofol group had significantly lower levels of CRP (P < 0.001), IL-6 (P < 0.001) and IL-8 (P < 0.001), with higher levels CD11 (P = 0.009) and CD18 (P = 0.002) expression. After 24 hours, patients on propofol had increased expression of shorter HO-1 GT(n) repeats than patients on isoflurane (P = 0.001). Use of propofol in CPB is associated with a less adverse inflammatory profile than is isofluorane, and an increased up-regulation of HO-1. This supports the hypothesis that propofol has anti-inflammatory activity.

Variable Pringle Maneuvers and Effect on Intestinal Epithelium in Rats. A Pilot Experimental Study in Rats

Background

It is observed that combined liver and colon surgery especially when this includes major liver resection with Pringle maneuver (PM) performance does not have a favorable outcome. Aim of our experimental study is to investigate the impact of portal triad occlusion on the large bowel and intra-abdominal inflammation and potent protective effects of the variants of (PM) in the combined surgical cases.

Materials and Methods

Forty-four rats were divided into four groups. In group A (control group), 1cm of the left partial colon was resected and then an end-to-end anastomosis was performed. In group B, a continuous PM for 30 minutes was performed followed by resection of 1cm of the left colon and an end-to-end anastomosis. In group C, the left colonic resection and anastomosis was performed after intermittent PM (IPM), which was 10 minutes PM followed by 5 minutes reperfusion repeated for three circles. In group D, an ischemic preconditioning for 10 minutes was initially performed followed by 5 minutes reperfusion and then continuous PM for 30 minutes. Finally the rats in group D underwent a 1cm left colonic resection and an end-to-end anastomosis.

Results

The percentage of colitis was higher in the B group (P = 0,19). The percentage of inflammation was not significantly higher even when we compared all “occlusion” groups (B+C+D) with the sham group. No evidence of pancreatitis was found in the sham group whereas amylase and lipase levels were higher in Groups B, C and D together (P = 0,0267). The comparison of group A to group B showed a significant difference (P = 0,0014) caused by continuous PM for 30 minutes, but there was no such result after IPM.

Conclusions

Major liver resections are performed with PM in order to minimize intra-operative blood loss. In the combined cases of colon surgery and major liver resections where PM is needed our results showed that IPM presents with better outcome and could be preferred compared with the other PM variants.

Sevoflurane Induces DNA Damage Whereas Isoflurane Leads to Higher Antioxidative Status in Anesthetized Rats

Taking into account that there are controversial antioxidative effects of inhalational anesthetics isoflurane and sevoflurane and absence of comparison of genotoxicity of both anesthetics in animal model, the aim of this study was to compare DNA damage and antioxidant status in Wistar rats exposed to a single time to isoflurane or sevoflurane. The alkaline single-cell gel electrophoresis assay (comet assay) was performed in order to evaluate DNA damage in whole blood cells of control animals (unexposed; n = 6) and those exposed to 2% isoflurane (n = 6) or 4% sevoflurane (n = 6) for 120 min. Plasma antioxidant status was determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. There was no statistically significant difference between isoflurane and sevoflurane groups regarding hemodynamic and temperature variables (P > 0.05). Sevoflurane significantly increased DNA damage compared to unexposed animals (P = 0.02). In addition, Wistar rats anesthetized with isoflurane showed higher antioxidative status (MTT) than control group (P = 0.019). There were no significant differences in DNA damage or antioxidant status between isoflurane and sevoflurane groups (P > 0.05). In conclusion, our findings suggest that, in contrast to sevoflurane exposure, isoflurane increases systemic antioxidative status, protecting cells from DNA damage in rats.

Astrocyte overexpression of heme oxygenase-1 improves outcome after intracerebral hemorrhage

BACKGROUND AND PURPOSE

Heme oxygenase-1 (HO-1) catalyzes the rate-limiting reaction of heme breakdown and may have both antioxidant and pro-oxidant effects. In previous studies, HO-1 overexpression protected astrocytes from heme-mediated injury in vitro. In the present study, we tested the hypothesis that selective astrocyte overexpression of HO-1 improves outcome after intracerebral hemorrhage.

METHODS

Male and female transgenic mice overexpressing human HO-1 driven by the GFAP promoter (GFAP.HMOX1) and wild-type controls received striatal injections of autologous blood (25 μL). Blood-brain barrier disruption was assessed by Evans blue assay and striatal cell viability by methylthiazolyldiphenyl-tetrazolium bromide assay. Neurological deficits were quantified by digital analysis of spontaneous cage activity, adhesive removal, and elevated body swing tests.

RESULTS

Mortality rate for wild-type mice was 34.8% and was similar for males and females; all GFAP.HMOX1 mice survived. Striatal Evans blue leakage at 24 hours was 23.4±3.2 ng in surviving wild-type mice, compared with 10.9±1.8 ng in transgenics. Perihematomal cell viability was reduced to 61±4% of contralateral at 3 days in wild-type mice, versus 80±4% in transgenics. Focal neurological deficits were significantly reduced and spontaneous cage activity was increased in GFAP.HMOX1 mice.

CONCLUSIONS

Selective HO-1 overexpression in astrocytes reduces mortality, blood-brain barrier disruption, perihematomal cell injury, and neurological deficits in an autologous blood injection intracerebral hemorrhage model. Genetic or pharmacological therapies that acutely increase astrocyte HO-1 may be beneficial after intracerebral hemorrhage.

Efficacy of prophylactic flavan-3-ol in permanent focal ischemia in 12-mo-old mice

The consumption of flavan-3-ol-containing foods, including (-)-epicatechin (EC), has been linked to lower incidence of cardiovascular disease and stroke. We previously demonstrated nuclear transcription factor erythroid 2p45-related factor-2 (Nrf2) -dependent EC efficacy in reducing stroke-induced deficits in 2-mo-old mice; yet stroke is primarily a disease of the elderly. Because neuroinflammation, oxidative stress, and vascular dysfunction are hallmarks of aging, we tested whether Nrf2 mediates EC efficacy in aging mice through modulation of glial responses and blood brain barrier permeability. First, we compared anastomosis in naïve wild-type and C57BL/6 Nrf2(-/-) mice to identify potential differences in cerebrovascular architecture. Data showed no significant differences in the number of anastomoses or mean intersection points, indicating similar gross vascular physiology. To assess efficacy and mechanisms of protection, wild-type or Nrf2(-/-) mice were administered the minimum effective EC dose established in our previous studies before the permanent distal middle cerebral artery occlusion. Similar to previous results with young mice, 12-mo-old wild types also showed significant reductions in infarct volume (41.01 ± 29.57%) and improved performance in removing adhesive tape relative to vehicle-treated controls, whereas a trend toward protection was observed in Nrf2(-/-). However, EC did not reduce immunoreactivity for the microglia/macrophage marker anti-ionized calcium-binding adapter molecule 1, suggesting that dampened activation/recruitment did not account for EC protection. Furthermore, there were no differences in mouse IgG extravasation or spontaneous hemorrhage between EC-treated groups. These data demonstrate that EC protection occurs independent of microglia/macrophage modulation or blood brain barrier preservation, suggesting that the glial cell responses in young mice are compensatory to another, and potentially novel, protective mechanism.

No signs of inflammation during knee surgery with ischemia: a study involving inhaled nitric oxide

Nitric oxide donors and inhaled nitric oxide (iNO) may decrease ischemia/reperfusion injury as reported in animal and human models. We investigated whether the attenuation of reperfusion injury, seen by others, in patients undergoing knee arthroplasty could be reproduced when patients had spinal anesthesia. 45 consecutive patients were randomized into three groups (n = 15). Groups 1 and 3 were receiving iNO 80 ppm or placebo (nitrogen, N₂) throughout the entire operation, and group 2 only received iNO in the beginning and at the end of the operation. Blood samples were collected before surgery, at the end of the surgery, and 2 hours postoperatively. Muscle biopsies were taken from quadriceps femoris muscle before and after ischemia. There were no increases in plasma levels of soluble adhesion molecules: ICAM, VCAM, P-selectin, E-selectin, or of HMGB1, in any of the groups. There were low numbers of CD68+ macrophages and of endothelial cells expression of ICAM, VCAM, and P-selectin in the muscle analyzed by immunohistochemistry, prior to and after ischemia. No signs of endothelial cell activation or inflammatory response neither systemically nor locally could be detected. The absence of inflammatory response questions this model of ischemia/reperfusion, but may also be related to the choice of anesthetic method EudraCTnr.

Isoflurane preconditioning ameliorates renal ischemia-reperfusion injury through antiinflammatory and antiapoptotic actions in rats

Renal ischemia-reperfusion (I/R) injury is a major cause of acute kidney injury via inflammation and cell apoptosis. Volatile anesthetics have been shown to exert organ-protective effects against kidney damage in vivo and in vitro. In the present study, we investigated the effects of isoflurane, a commonly used volatile anesthetic, on renal I/R injury and the underlying mechanisms. Rats subjected to renal I/R displayed higher serum creatinine and blood urea nitrogen levels than sham rats as well as severe histopathological damage. Renal I/R also resulted in a nuclear factor-κB (NF-κB)-mediated inflammatory response and dysfunction of the p53-Bax-caspase-3 apoptotic pathway. Rats preconditioned with 1.5% isoflurane for 2 h had better renal function and less tubular apoptosis 24 h after I/R injury than control rats. Pretreatment with isoflurane suppressed renal NF-κB activation, leading to a reduction in proinflammatory molecules (high-mobility group box 1, interleukin-1β, and tumor necrosis factor-α) both in the kidneys and circulation. In addition, rats subjected to isoflurane preconditioning had a higher Bcl-2/Bax ratio and less cleaved caspase-3. Our findings suggest that preconditioning with a clinically relevant concentration of isoflurane attenuates renal I/R injury, based at least in part on its ability to modulate renal inflammation and apoptosis.

Vitamin A deficiency modulates iron metabolism via ineffective erythropoiesis

Vitamin A modulates inflammatory status, iron metabolism and erythropoiesis. Given that these factors modulate the expression of the hormone hepcidin (Hamp), we investigated the effect of vitamin A deficiency on molecular biomarkers of iron metabolism, the inflammatory response and the erythropoietic system. Five groups of male Wistar rats were treated: control (AIN-93G), the vitamin A-deficient (VAD) diet, the iron-deficient (FeD) diet, the vitamin A- and iron-deficient (VAFeD) diet or the diet with 12 mg atRA/kg diet replacing all-trans-retinyl palmitate by all-trans retinoic acid (atRA). Vitamin A deficiency reduced serum iron and transferrin saturation levels, increased spleen iron concentrations, reduced hepatic Hamp and kidney erythropoietin messenger RNA (mRNA) levels and up-regulated hepatic and spleen heme oxygenase-1 gene expression while reducing the liver HO-1 specific activity compared with the control. The FeD and VAFeD rats exhibited lower levels of serum iron and transferrin saturation, lower iron concentrations in tissues and lower hepatic Hamp mRNA levels compared with the control. The treatment with atRA resulted in lower serum iron and transferrin concentrations, an increased iron concentration in the liver, a decreased iron concentration in the spleen and in the gut, and decreased hepatic Hamp mRNA levels. In summary, these findings suggest that vitamin A deficiency leads to ineffective erythropoiesis by the down-regulation of renal erythropoietin expression in the kidney, resulting in erythrocyte malformation and the consequent accumulation of the heme group in the spleen. Vitamin A deficiency indirectly modulates systemic iron homeostasis by enhancing erythrophagocytosis of undifferentiated erythrocytes.

The effect of octreotide on hepatic ischemia-reperfusion injury in a rabbit model

BACKGROUND

Hepatic ischemic-reperfusion injury (HIRI) is a major cause of morbidity and mortality following liver surgery. Octreotide (Oct) has been reported to improve hepatocellular energy metabolism in a rat HIRI model. This study was designed to evaluate whether Oct could protect the liver of rabbits against ischemic-reperfusion (I/R) injury.

METHODS

Twenty-four adult New Zealand rabbits were randomly divided into a sham operated group (Control), an ischemia/reperfusion group (I/R), and an ischemia/reperfusion + Oct pretreatment group (I/R + Oct). The hemodynamic (mean arterial pressure [MAP] and heart rate [HR]) changes, liver enzymes (alanine aminotransferase [ALT], aspartate aminotransferase [AST], and lactate dehydrogenase [LDH]) release, inflammatory cytokines (tumor necrosis factor [TNF]α and interleukin [IL]-1β) levels, and endotoxin (ETX) levels were measured during I/R.

RESULTS

Compared with the Control group, the MAP decreased and HR increased in I/R and I/R + Oct groups at ischemia 15 minutes (P < .05) but were less in the I/R + Oct group relative to the I/R group (P < .05). ALT, AST, LDH, IL-1β, and ETX levels were increased in the I/R and I/R + Oct groups at ischemia 30 minutes (P < .05), however, the increase was lower in the I/R + Oct group relative to the I/R group (P < .05). Bcl-2 expression in the I/R + Oct group was higher compared with other groups (P < .05) and Bax expression in the I/R group was reduced compared with other groups (P < .05). Hepatocellular damage in the I/R + Oct group appeared to be less than in the I/R group by microscopy.

CONCLUSIONS

Oct pretreatment attenuated hemodynamic changes and decreased liver enzyme changes induced by HIRI in a rabbit model. The protection mechanisms of Oct may be related to reduced ETX levels, down-regulation of the inflammatory cytokines TNFα and IL-1β, and inhibition of hepatocellular apoptosis, as well as the modulation of the mitochondrion-mediated Bcl-2/Bax apoptosis pathway. Based on our study it appears that Oct may be useful in decreasing liver injury after liver surgery and/or transplantation and may serve as a promising agent against HIRI.

Biological evaluation of liposome-encapsulated hemoglobin surface-modified with a novel PEGylated nonphospholipid amphiphile

Traumatic injury is often associated with hemorrhagic shock. Liposome-encapsulated hemoglobin (LEH) is being developed as an artificial oxygen carrier to address post-hemorrhage oxygen and volume deficit. Here, we report a new composition of LEH based on the use of polyethylene glycol (PEG2K ) conjugated with nonphospholipid hexadecylcarbamoylmethylhexadecanoate (HDAS) to modify the surface of LEH particles. LEH was manufactured by the high-pressure homogenization method using dipalmitoylphosphatidylcholine (∼38 mol%), cholesterol (∼38 mol%), HDAS (∼20 mol%), and highly purified stroma-free human hemoglobin. HDAS-PEG2K was postinserted into the resultant LEH to generate HDAS-PEG2K -LEH. We investigated the potential immune response to HDAS-PEG2K -LEH in a mice model. At the same time, the preparation was tested in a rat model to study the effect of repeated HDAS-PEG2K -LEH injection over 4 weeks. We found that HDAS-PEG2K modification substantially reduced the circulating levels of anaphylatoxins C3a and C5a, as well as plasma levels of thromboxane B2, in mice. Repeated injections of HDAS-PEG2K -LEH in rats did not appear to alter its clearance profile after 4 weeks of treatment. No antibody response against human hemoglobin or PEG was detected in rat plasma. Histological observations of lung, liver, spleen, and kidney were not significantly different between saline-treated rats and HDAS-PEG2K -LEH-treated rats. Immunohistochemical staining for rat heme oxygenase-1 (HO-1) did not show induced expression of HO-1 in these organs. These results suggest that the new surface modification of LEH is immune-neutral and does not adversely affect histology even after repeated administration.

Ischemia-reperfusion injury and volatile anesthetics

Ischemia-reperfusion injury (IRI) is induced as a result of reentry of the blood and oxygen to ischemic tissue. Antioxidant and some other drugs have protective effect on IRI. In many surgeries and clinical conditions IRI is counteract inevitable. Some anesthetic agents may have a protective role in this procedure. It is known that inhalational anesthetics possess protective effects against IRI. In this review the mechanism of preventive effects of volatile anesthetics and different ischemia-reperfusion models are discussed.

Paradoxical effects of heme arginate on survival of myocutaneous flaps

Ischemia reperfusion injury (IRI) contributes to partial flap and solid organ transplant failure. Heme-oxygenase 1 (HO-1) is an inducible, cytoprotective enzyme which protects against IRI in solid organ transplant models. Heme arginate (HA), a HO-1 inducer, is a promising, translatable, preconditioning agent. This study investigated the effects of preconditioning with HA on the clinical outcome of a myocutaneous IRI model. Forty male Lewis rats were randomized to intravenously receive 1) Control-NaCl, 2) HA, 3) HA and tin mesoporphyrin (SnMP), a HO-1 inhibitor; and 4) SnMP alone. Twenty-four hours later, an in situ transverse rectus abdominis myocutaneous flap was performed under isoflurane anesthesia. Viability of flaps was measured clinically and by laser-Doppler perfusion scanning. In vitro work on human epidermal keratinocytes (HEKa) assessed the effects of HA, SnMP, and the iron chelator desferrioxamine on 1) cytotoxicity, 2) intracellular reactive oxygen species (ROS) concentration, and 3) ROS-mediated DNA damage. In contrast to our hypothesis, HA preconditioning produced over 30% more flap necrosis at 48 h compared with controls (P = 0.02). HA-containing treatments produced significantly worse flap perfusion at all postoperative time points. In vitro work showed that HA is cytotoxic to keratinocytes. This cytotoxicity was independent of HO-1 and was mediated by the generation of ROS by free heme. In contrast to solid organ data, pharmacological preconditioning with HA significantly worsened clinical outcome, thus indicating that this is not a viable approach in free flap research.

Oral administration of the flavanol (-)-epicatechin bolsters endogenous protection against focal ischemia through the Nrf2 cytoprotective pathway

Consumption of flavan-3-ols, notably (-)-epicatechin (EC), has been highly recommended in complementary and alternative medicine (CAM) due to reports that flavan-3-ols boost antioxidant activity, support vascular function, and prevent cardiovascular disease. To date, in vivo efficacy and mechanisms of action for many CAM therapies, including EC, remain elusive in brain ischemia. In contrast to its purported direct antioxidant role, we hypothesized protection through activation of the endogenous transcriptional factor Nrf2. To screen cellular protection and investigate Nrf2 activation, we adopted a pretreatment paradigm using enriched primary neuronal cultures from mice and washed out EC prior to oxygen glucose deprivation to attenuate direct antioxidant effects. EC protected primary neurons from oxygen glucose deprivation by increasing neuronal viability (40.2 ± 14.1%) and reducing protein oxidation, effects that occurred concomitantly with increased Nrf2-responsive antioxidant protein expression. We also utilized wildtype and Nrf2 C57BL/6 knockout mice in a permanent model of focal brain ischemia to evaluate glial cell regulation and complex sensorimotor functioning. EC-treated wildtype mice displayed a reduction or absence of forelimb motor coordination impairments that were evident in vehicle-treated mice. This protection was associated with reduced anatomical injury (54.5 ± 8.3%) and microglia/macrophage activation/recruitment (56.4 ± 13.0%). The protective effects elicited by EC in both model systems were abolished in tissues and neuronal cultures from Nrf2 knockout mice. Together, these data demonstrate EC protection through Nrf2 and extend the benefits to improved performance on a complex sensorimotor task, highlighting the potential of flavan-3-ols in CAM approaches in minimizing subsequent stroke injury.

Perioperative ischaemia-induced liver injury and protection strategies: An expanding horizon for anaesthesiologists

Liver resection is an effective modality of treatment in patients with primary liver tumour, metastases from colorectal cancers and selected benign hepatic diseases. Its aim is to resect the grossly visible tumour with clear margins and to ensure that the remnant liver mass has sufficient function which is adequate for survival. With the advent of better preoperative imaging, surgical techniques and perioperative management, there is an improvement in the outcome with decreased mortality. This decline in postoperative mortality after hepatic resection has encouraged surgeons for more radical liver resections, leaving behind smaller liver remnants in a bid to achieve curative surgeries. But despite advances in diagnostic, imaging and surgical techniques, postoperative liver dysfunction of varied severity including death due to liver failure is still a serious problem in such patients. Different surgical and non-surgical techniques like reducing perioperative blood loss and consequent decreased transfusions, vascular occlusion techniques (intermittent portal triad clamping and ischaemic preconditioning), administration of pharmacological agents (dextrose, intraoperative use of methylprednisolone, trimetazidine, ulinastatin and lignocaine) and inhaled anaesthetic agents (sevoflurane) and opioids (remifentanil) have demonstrated the potential benefit and minimised the adverse effects of surgery. In this article, the authors reviewed the surgical and non-surgical measures that could be adopted to minimise the risk of postoperative liver failure following liver surgeries with special emphasis on ischaemic and pharmacological preconditioning which can be easily adapted clinically.

Anaesthesia management for acute appendicitis in cases with Sjogren's syndrome accompanying autoimmune hepatitis

Characterised by lymphocytic infiltration of exocrine glands, Sjögren's syndrome (SS) is a chronic autoimmune disease. Symptoms belonging to the involved systems may occur owing to the fact that it affects multiple systems. While rheumatoid arthritis is observed concomitantly, its co-occurrence with autoimmune hepatitis is astonishingly common. Through this case report, we intended to review issues that should be attended to while administering anaesthesia to a patient with SS accompanying autoimmune hepatitis. In the light of literature, we aimed to discuss anaesthesia management to the patient with SS and issues stemming from the clinical features of SS. In SS, the expected issues are liver problems related autoimmune hepatitis and respiratory problems related pulmonary fibrosis. A careful preoperative evaluation, a comprehensive preparation against difficulty in intubation, a selective anaesthesia management in terms of autoimmune hepatitis and close monitoring of postoperative respiration may prevent or decrease possible complications.

Cobalt protoporphyrin accelerates TFEB activation and lysosome reformation during LPS-induced septic insults in the rat heart

Lipopolysaccharide (LPS)-induced myocardial dysfunction is caused, at least in part, by mitochondrial dysfunction. Mitochondrial dysfunction and the oxidative damage associated with it are scavenged through various cellular defense systems such as autophagy to prevent harmful effects. Our recent study has demonstrated that cobalt protoporphyrin IX (CoPPIX), a potent inducer of heme oxygenase-1 (HO-1), ameliorates septic liver injuries by enhancing mitochondrial autophagy in rats. In our current study, we show that CoPPIX (5 mg/kg s.c.) not only accelerates the autophagic response but also promotes lysosome reformation in the rat heart treated with LPS (15 mg/kg i.p.). Lysosomal membrane-associated protein-2 (LAMP2), which is essential to the maintenance of lysosomal functions in the heart, is depleted transiently but restored rapidly during LPS administration in the rat. Activation of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis and autophagy, was also observed, indicating a hyper consumption and subsequent reformation of the lysosome to meet the increased demand for autophagosome cleaning. CoPPIX was found to promote these processes and tended to restore the LPS-induced suppression of cardiac performances whilst chloroquine (CQ; 20 mg/kg i.p.), an inhibitor of lysosomes and autophagic protein degradation, abrogates these beneficial effects. The cardioprotective effect of CoPPIX against LPS toxicity was also observed via decreased levels of cardiac releasing enzymes in the plasma. Taken together, our current data indicate that lysosome reformation mediated by TFEB may be involved in cardioprotection against LPS-induced septic insults, and serve as a novel mechanism by which CoPPIX protects the heart against oxidative stress.

Does pharmacological conditioning with the volatile anaesthetic sevoflurane offer protection in liver surgery?

BACKGROUND

A recently published randomized control trial (RCT) showed a protection of the remnant liver from ischemia-reperfusion (I/R) injury by pharmacological pre-conditioning with a volatile anaesthetic in patients undergoing hepatic resection. Whether the continuous application of volatile anaesthetics (pharmacological conditioning) also protects against I/R injury is unknown.

METHODS

Consecutive patients undergoing liver resection with inflow occlusion from 2005-2007 were included in the trial. Two groups of anaesthesia regimens with either continuous application of the volatile anaesthetic sevoflurane (pharmacological conditioning) or continuous infusion of the intravenous (i.v.) anaesthetic propofol (control group) were compared. Endpoints were serum-peak-aspartate aminotransferase (AST)/ alanine aminotranferease (ALT) levels, length of stay (LOS) and intensive care unit (ICU) stays, and the occurrence of post-operative complications.

RESULTS

Two hundred and twenty-seven patients were included. Pharmacological conditioning did not protect the remnant liver from IR injury (adjusted difference for peak-AST:61.9 U/l, 95% confidence interval (CI): -151.7-275.4 U/l, P = 0.568; peak-ALT:136.1 U/l, 95% CI: -113.7-385.9 U/l, P = 0.284) nor reduce LOS (adjusted difference 0.9 days, 95% CI: -2.6-4.3 days, P = 0.622) or ICU stay (1.6 days, 95% CI: -0.2-3.3 days, P = 0.079), and was not associated with reduced complication rates (adjusted OR 1.12, 95% CI:0.6-2.3, P = 0.761) compared with the control group.

CONCLUSION

In this retrospective study, continuous volatile anaesthesia in liver resection does not provide protection of the remnant liver from IR injury compared with continuous i.v. anaesthesia.

Anesthetic considerations for the patient with liver disease

PURPOSE OF REVIEW

An increasing number of patients requiring surgery are presenting with chronic or end stage liver disease. The management of these patients demands anesthesiologists with in-depth knowledge of the consequences of hepatic dysfunction, the effects on other organs, the risk of surgery, and the impact of anesthesia.

RECENT FINDINGS

Chronic or end stage liver disease is associated with an increased risk of perioperative morbidity and mortality. It is essential to preoperatively assess possible hepatic encephalopathy, pleural effusions, hepatopulmonary syndrome, hepatopulmonary hypertension, hepatorenal syndrome, cirrhotic cardiomyopathy, and coagulation disorders. The application of two scoring systems, that is, Child-Turcotte-Pugh and model for end stage liver disease, helps to estimate the risk of surgery. The use of propofol is superior to benzodiazepines as intravenous narcotics. Although enflurane and halothane are discouraged for maintenance of anesthesia, all modern volatile anesthetics appear comparable with respect to outcome. Fentanyl, sufentanil, and remifentanil as opioids and cis-atracurium for relaxation may be the best choices in liver insufficency. Regional anesthesia is valuable for postoperative pain management.

SUMMARY

Current studies have employed different anesthetic approaches in the preoperative and intraoperative management in order to improve outcomes of patients with liver disease.

Current strategies to minimize hepatic ischemia-reperfusion injury by targeting reactive oxygen species

Ischemia-reperfusion is a major component of injury in vascular occlusion both during liver surgery and during liver transplantation. The pathophysiology of hepatic ischemia-reperfusion includes a number of mechanisms including oxidant stress that contribute to various degrees to the overall organ damage. A large volume of recent research has focused on the use of antioxidants to ameliorate this injury, although results in experimental models have not translated well to the clinic. This review focuses on critical sources and mediators of oxidative stress during hepatic ischemia-reperfusion, the status of current antioxidant interventions, and emerging mechanisms of protection by preconditioning. While recent advances in regulation of antioxidant systems by Nrf2 provide interesting new potential therapeutic targets, an increased focus must be placed on more in-depth mechanistic investigations in hepatic ischemia-reperfusion injury and translational research in order to refine current strategies in disease management.

The volatile anesthetic isoflurane prevents ventilator-induced lung injury via phosphoinositide 3-kinase/Akt signaling in mice

BACKGROUND

Mechanical ventilation leads to ventilator-induced lung injury in animals, and can contribute to acute lung injury/acute respiratory distress syndrome in humans. Acute lung injury/acute respiratory distress syndrome currently causes an unacceptably high rate of morbidity and mortality among critically ill patients. Volatile anesthetics have been shown to exert anti-inflammatory and organ-protective effects in vivo. We investigated the effects of the volatile anesthetic isoflurane on lung injury during mechanical ventilation.

METHODS

C57BL/6N mice were ventilated with a tidal volume of 12 mL/kg body weight for 6 hours in the absence or presence of isoflurane, and, in a second series, with or without the specific phosphoinositide 3-kinase/Akt inhibitor LY294002. Lung injury was determined by comparative histology, and by the isolation of bronchoalveolar lavage for differential cell counting and analysis of cytokine levels using enzyme-linked immunosorbent assays. Lung homogenates were analyzed for protein expression by Western blotting.

RESULTS

Mechanical ventilation caused increases in alveolar wall thickening, cellular infiltration, and an elevated ventilator-induced lung injury score. Neutrophil influx and cytokine (i.e., interleukin-1β, and macrophage inflammatory protein-2) release were enhanced in the bronchoalveolar lavage of ventilated mice. The expression levels of the stress proteins hemeoxygenase-1 and heat shock protein-70 were elevated in lung tissue homogenates. Isoflurane ventilation significantly reduced lung damage, inflammation, and stress protein expression. In contrast, phosphorylation of Akt protein was substantially increased during mechanical ventilation with isoflurane. Inhibition of phosphoinositide 3-kinase/Akt signaling before mechanical ventilation completely reversed the lung-protective effects of isoflurane treatment in vivo.

CONCLUSIONS

Inhalation of isoflurane during mechanical ventilation protects against lung injury by preventing proinflammatory responses. This protection is mediated via phosphoinositide 3-kinase/Akt signaling.

Hepatic steatosis prevents heme oxygenase-1 induction by isoflurane in the rat liver

AIM: To characterize the inductive effects of isoflurane (ISO) on hepatic heme oxygenase-1 (HO-1) in an animal model of hepatic steatosis.

METHODS: Lean (LEAN) and obese (FAT) Zucker rats were randomized into 4 groups: 1: LEAN + pentobarbital sodium (PEN); 2: LEAN + ISO; 3: FAT + PEN; 4: FAT + ISO. The animals were mechanically ventilated for 6 h. In vitro analyses of liver tissue included determination of HO-1 mRNA and protein expression as well as measurement of HO enzyme activity and immunohistochemical analyses.

RESULTS: Compared to PEN treatment, ISO administration profoundly induced hepatic HO-1 mRNA and protein expression and significantly increased HO enzyme activity in lean Zucker rats. In contrast, no difference in HO-1 gene expression was observed after ISO or PEN anesthesia in obese Zucker rats.

CONCLUSION: The present study demonstrates that ISO is an inducer of hepatic HO-1 gene expression in non-steatotic organs but failed to upregulate HO-1 in steatotic livers.

Isoflurane preconditioning at clinically relevant doses induce protective effects of heme oxygenase-1 on hepatic ischemia reperfusion in rats

Background

Activation of heme oxygenase-1 (HO-1) has been proved to reduce damages to the liver in ischemia reperfusion injury. The objective of present study was to determine whether clinic relevant doses of isoflurane treatment could be sufficient to activate HO-1 inducing, which confers protective effect against hepatic ischemia-reperfusion injury.

Methods

The hepatic artery and portal vein to the left and the median liver lobes of forty male Sprague-Dawley rats were occluded for 60 minutes. Reperfusion was allowed for 4 hours before the animal subjects were sacrificed. Six groups (n = 12) were included in the study. A negative control group received sham operation and positive control group a standard ischemia-reperfusion regimen. The third group was pretreated with isoflurane prior to the ischemia-reperfusion. The fourth group received an HO-1 inhibitor zinc protoporphyrin (Znpp) prior to the isoflurane pretreatment and the ischemia-reperfusion. The fifth group received Znpp alone before ischemia-reperfusion procedure, and the sixth group was administrated with a HO-1 inducer hemin prior to IR. HO-1 in the liver was measured using an enzymatic activity assay, a Western blot analysis, as well as immunohistochemical method. Extent of liver damage was estimated by determination of the serum transaminases, liver lipid peroxidation and hepatic histology. Infiltration of the liver by neutrophils was measured using a myeloperoxidase activity assay. TNFα mRNA in the liver was measured using RT-PCR.

Results

Isoflurane pretreatment significantly attenuated the hepatic injuries and inflammatory responses caused by the ischemia reperfusion. Selectively inhibiting HO-1 with ZnPP completed blocked the protective effects of isoflurane. Inducing HO-1 with hemin alone produced protective effects similar in magnitude to that of isoflurane.

Conclusions

Clinic relevant doses of isoflurane attenuate ischemia reperfusion injury in rats by increasing the HO-1 expression and activity.

Hepatic ischemia-reperfusion injury and therapeutic strategies to alleviate cellular damage

Warm hepatic ischemia-reperfusion injury is a significant medical problem in many clinical conditions such as liver transplantation, hepatic surgery for tumor excision, trauma and hepatic failure after hemorrhagic shock. Partial or, mostly, total interruption of hepatic blood flow is often necessary when liver surgery is performed. This interruption of blood flow is termed "warm ischemia" and upon revascularization, when molecular oxygen is reintroduced, the organ undergoes a process called "reperfusion injury" that causes deterioration of organ function. Ischemia reperfusion results in cellular damage and tissue injury associated with a complex series of events. Pathophysiological mechanisms leading to tissue injury following ischemia-reperfusion will be discussed and therapies targeted to reduce liver damage will be summarized within this review.

Hepatic organ protection: From basic science to clinical practice

Hepatic ischemia and reperfusion (I/R) injury during liver surgery is still the main cause of postoperative liver failure and the subsequent rise of mortality in these patients. During the last few years, a multitude of underlying mechanisms have been extensively characterized and many different protective approaches have been evaluated under experimental conditions. Some of them have already found their way into small sized clinical trials. In this Topic Highlight series of articles, we present recent insights into promising protective concepts including the regulation and optimization of hepatic blood flow, molecular mechanisms of preconditioning and pharmacological approaches with the aim of limiting hepatic I/R injury. Leading international experts present the latest experimental evidence in their fields stressing clinically relevant ideas, which are now on the edge of entering clinical practice.