Isoflurane post-conditioning protects against intestinal ischemia-reperfusion injury and multiorgan dysfunction via transforming growth factor-β1 generation

The anesthesiologist's perspective on emergency aortic surgery: Preoperative optimization, intraoperative management, and postoperative surveillance

The management of emergencies related to the aorta requires a multidisciplinary approach involving various health care professionals. Despite technological advancements in treatment methods, the risks and mortality rates associated with surgery remain high. In the emergency department, definitive diagnosis is usually obtained through computed tomography angiography, and management focuses on controlling blood pressure and treating symptoms to prevent further deterioration. Preoperative resuscitation is the main focus, followed by intraoperative management aimed at stabilizing the patient's hemodynamics, controlling bleeding, and protecting vital organs. After the operation, factors such as organ protection, transfusion management, pain control, and overall patient care must be taken into account. Endovascular techniques are becoming more common in surgical treatment, but they also present new challenges in terms of complications and outcomes. It is recommended that patients with suspected ruptured abdominal aortic aneurysms be transferred to facilities with both open and endovascular treatment options and a track record of successful outcomes to ensure the best patient care and long-term results. To achieve optimal patient outcomes, close collaboration and regular case discussions between health care professionals are necessary, as well as participation in educational programs to promote a culture of teamwork and continuous improvement.

Inhaled Sedation with Volatile Anesthetics for Mechanically Ventilated Patients in Intensive Care Units: A Narrative Review

Inhaled sedation was recently approved in Europe as an alternative to intravenous sedative drugs for intensive care unit (ICU) sedation. The aim of this narrative review was to summarize the available data from the literature published between 2005 and 2023 in terms of the efficacy, safety, and potential clinical benefits of inhaled sedation for ICU mechanically ventilated patients. The results indicated that inhaled sedation reduces the time to extubation and weaning from mechanical ventilation and reduces opioid and muscle relaxant consumption, thereby possibly enhancing recovery. Several researchers have reported its potential cardio-protective, anti-inflammatory or bronchodilator properties, alongside its minimal metabolism by the liver and kidney. The reflection devices used with inhaled sedation may increase the instrumental dead space volume and could lead to hypercapnia if the ventilator settings are not optimal and the end tidal carbon dioxide is not monitored. The risk of air pollution can be prevented by the adequate scavenging of the expired gases. Minimizing atmospheric pollution can be achieved through the judicious use of the inhalation sedation for selected groups of ICU patients, where the benefits are maximized compared to intravenous sedation. Very rarely, inhaled sedation can induce malignant hyperthermia, which prompts urgent diagnosis and treatment by the ICU staff. Overall, there is growing evidence to support the benefits of inhaled sedation as an alternative for intravenous sedation in ICU mechanically ventilated patients. The indication and management of any side effects should be clearly set and protocolized by each ICU. More randomized controlled trials (RCTs) are still required to investigate whether inhaled sedation should be prioritized over the current practice of intravenous sedation.

Protective Effect of Oxygen and Isoflurane in Rodent Model of Intestinal Ischemia-Reperfusion Injury

Animal research in intestinal ischemia-reperfusion injury (IRI) is mainly performed in rodent models. Previously, intraperitoneal (I.P.) injections with ketamine-xylazine mixtures were used. Nowadays, volatile anesthetics (isoflurane) are more common. However, the impact of the anesthetic method on intestinal IRI has not been investigated. We aim to analyze the different anesthetic methods and their influence on the extent of intestinal IRI in a rat model. Male Sprague-Dawley rats were used to investigate the effect of I.P. anesthesia on 60 min of intestinal ischemia and 60 min of reperfusion in comparison to hyperoxygenation (100% O₂) and volatile isoflurane anesthesia. In comparison to I.P. anesthesia with room air (21% O₂), supplying 100% O₂ improved 7-day survival by cardiovascular stabilization, reducing lactic acidosis and preventing vascular leakage. However, this had no effect on the intestinal epithelial damage, permeability, and inflammatory response observed after intestinal IRI. In contrast to I.P. + 100% O₂, isoflurane anesthesia reduced intestinal IRI by preventing ongoing low-flow reperfusion hypotension, limiting intestinal epithelial damage and permeability, and by having anti-inflammatory effects. When translating the aforementioned results of this study to clinical situations, such as intestinal ischemia or transplantation, the potential protective effects of hyperoxygenation and volatile anesthetics require further research.

Inhaled Anesthetics for Sedation in ICU: Widening Horizons!

How to cite this article: Krishna B. Inhaled Anesthetics for Sedation in ICU: Widening Horizons! Indian J Crit Care Med 2022;26(8):889-891.

Dexmedetomidine reduces enteric glial cell injury induced by intestinal ischaemia-reperfusion injury through mitochondrial localization of TERT

This study was performed to uncover the effects of dexmedetomidine on oxidative stress injury induced by mitochondrial localization of telomerase reverse transcriptase (TERT) in enteric glial cells (EGCs) following intestinal ischaemia-reperfusion injury (IRI) in rat models. Following establishment of intestinal IRI models by superior mesenteric artery occlusion in Wistar rats, the expression and distribution patterns of TERT were detected. The IRI rats were subsequently treated with low or high doses of dexmedetomidine, followed by detection of ROS, MDA and GSH levels. Calcein cobalt and rhodamine 123 staining were also carried out to detect mitochondrial permeability transition pore (MPTP) and the mitochondrial membrane potential (MMP), respectively. Moreover, oxidative injury of mtDNA was determined, in addition to analyses of EGC viability and apoptosis. Intestinal tissues and mitochondria of EGCs were badly damaged in the intestinal IRI group. In addition, there was a reduction in mitochondrial localization of TERT, oxidative stress, whilst apoptosis of EGCs was increased and proliferation was decreased. On the other hand, administration of dexmedetomidine was associated with promotion of mitochondrial localization of TERT, whilst oxidative stress, MPTP and mtDNA in EGCs, and EGC apoptosis were all inhibited, and the MMP and EGC viability were both increased. A positive correlation was observed between different doses of dexmedetomidine and protective effects. Collectively, our findings highlighted the antioxidative effects of dexmedetomidine on EGCs following intestinal IRI, as dexmedetomidine alleviated mitochondrial damage by enhancing the mitochondrial localization of TERT.

HMGB1 signaling-regulated endoplasmic reticulum stress mediates intestinal ischemia/reperfusion-induced acute renal damage

BACKGROUND

Ischemia/reperfusion of the intestine often leads to distant organ injury, but the mechanism of intestinal ischemia/reperfusion-induced renal dysfunction is still not clear. The present study aimed to investigate the mechanisms of acute renal damage after intestinal ischemia/reperfusion challenge and explore the role of released high-mobility group box-1 in this process.

METHODS

Intestinal ischemia/reperfusion was induced in male Sprague-Dawley rats by clamping the superior mesenteric artery for 1.5 hours. At different reperfusion time points, anti-high-mobility group box-1 neutralizing antibodies or ethyl pyruvate were administered to neutralize or inhibit circulating high-mobility group box-1, respectively.

RESULTS

Significant kidney injury was observed after 6 hours of intestinal reperfusion, as indicated by increased serum levels of urea nitrogen and creatinine, increased expression of neutrophil gelatinase-associated lipocalin, interleukin-6, and MIP-2, and enhanced cell apoptosis, as indicated by cleaved caspase 3 levels in renal tissues. The levels of phosphorylated eIF2ɑ, activating transcription factor 4, and C/EBP-homologous protein (CHOP) were markedly elevated, indicating the activation of endoplasmic reticulum stress in the impaired kidney. High-mobility group box-1 translocated to cytoplasm in the intestine and serum concentrations of high-mobility group box-1 increased notably during the reperfusion phase. Both anti-high-mobility group box-1 antibodies and ethyl pyruvate treatment significantly reduced serum high-mobility group box-1 concentrations, attenuated endoplasmic reticulum stress in renal tissue and inhibited the development of renal damage. Moreover, the elevated expression of receptor for advanced glycation end products in the kidneys after intestinal ischemia/reperfusion was abrogated after high-mobility group box-1 inhibition.

CONCLUSION

These results suggested that high-mobility group box-1 signaling regulated endoplasmic reticulum stress and promoted intestinal ischemia/reperfusion-induced acute kidney injury. High-mobility group box-1 neutralization/inhibition might serve as a pharmacological intervention strategy for these pathophysiological processes.

The effect of ischaemic postconditioning on mucosal integrity and function in equine jejunal ischaemia

BACKGROUND

Ischaemic postconditioning (IPoC) has been shown to ameliorate ischaemia reperfusion injury in different species and tissues.

OBJECTIVES

To assess the feasibility of IPoC in equine small intestinal ischaemia and to assess its effect on histomorphology, electrophysiology and paracellular permeability.

STUDY DESIGN

Randomised in vivo experiment.

METHODS

Experimental jejunal ischaemia was induced for 90 min in horses under general anaesthesia. In the control group (C; n = 7), the jejunum was reperfused without further intervention. In the postconditioning group (IPoC; n = 7), reocclusion was implemented following release of ischaemia by clamping the mesenteric vessels in three cycles of 30 seconds. This was followed by 120 minutes of reperfusion in both groups. Intestinal microperfusion and oxygenation was measured during IPoC using spectrophotometry and Doppler flowmetry. Histomorphology and histomorphometry of the intestinal mucosa were assessed. Furthermore, electrophysiological variables and unidirectional flux rates of ³ H-mannitol were determined in Ussing chambers. Western blot analysis was performed to determine the tight junction protein levels of claudin-1, claudin-2 and occludin in the intestinal mucosa. Comparisons between the groups and time points were performed using a two-way repeated measures analysis of variance (ANOVA) or non-parametric statistical tests for the ordinal and not normally distributed data (significance P < .05).

RESULTS

IPoC significantly reduced intestinal microperfusion during all clamping cycles yet affected oxygen saturation only during the first cycle. After reperfusion, Group IPoC showed significantly less mucosal villus denudation (mean difference 21.5%, P = .02) and decreased mucosal-to-serosal flux rates (mean difference 15.2 nM/cm² /h, P = .007) compared to Group C. There were no significant differences between the groups for the other tested variables.

MAIN LIMITATIONS

Small sample size, long-term effects were not investigated.

CONCLUSIONS

Following IPoC, the intestinal mucosa demonstrated significantly less villus denudation and paracellular permeability compared to the untreated control group, possibly indicating a protective effect of IPoC on ischaemia reperfusion injury.

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.

Coculture With Ischemia/Reperfusion-Preconditioned Hepatocytes Improves Islet Function and Survival

In clinical islet transplantation, hepatic ischemia and insufficient neovascularization of transplanted islets are barriers to islet survival and function. However, hepatocytes have a potency to protect themselves against ischemia. We hypothesized that ischemia/reperfusion preconditioning (IRP) of hepatocytes might beneficially affect islet cells in a coculture system. Primary islets were cocultured with primary hepatocytes, and hepatocyte IRP was conducted by subjecting cells to hypoxic conditions for single 15-minute/30-minute hypoxia, or 2 tandem 15-minute/30-minute hypoxic treatments (hypoxic-normoxic-hypoxic). We show that gene expression levels of insulin-like growth factor 1 (IGF-1), hepatocyte growth factor (HGF), transforming growth factor-α (TGF-α), and TGF-β1 in hepatocytes were increased by IRP. IRP hepatocytes secreted hepatocyte growth factor and insulin-like growth factor-1. Coculture of islets with IRP hepatocytes enhanced islet insulin secretion in glucose challenge test and expression of the survival-related gene Bcl-2 and the regenerating gene-1α (Reg-1α). Islets cocultured with the 30-minute double-IRP hepatocytes displayed significantly higher viability in the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and terminal deoxynucleotidyl transferase dUTP nick end labeling stain compared with that of islets subjected to 30 minutes of hypoxia. These results suggest that islet coculture with IRP hepatocytes can improve islet survival and insulin secretion.

Transcription factors Nrf2 and NF-κB contribute to inflammation and apoptosis induced by intestinal ischemia-reperfusion in mice

Intestinal ischemia/reperfusion (IIR) is a common pathological event associated with intestinal injury and apoptosis with high mortality. Nuclear factor (NF)-E2-related factor-2 (Nrf2) is a key transcription factor that interacts with NF-κB and has a vital anti-inflammatory effect. However, whether Nrf2 has a role in IIR-induced apoptosis and the possible underlining mechanisms, such as modulation of the inflammation regulation pathway, have remained to be fully elucidated. In the present study, IIR was identified to cause significant intestinal injury and apoptosis, with high expression levels of inflammatory cytokines, as well as the apoptotic proteins B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-3, while simultaneously decreasing the protein levels of Bcl-2. The effect was more pronounced after pretreatment of the animals with all-trans retinoic acid or brusatol, potent inhibitors of Nrf2. t-Butylhydroquinone, an Nrf2 activator, significantly attenuated IIR-induced intestinal injury and apoptosis, with inhibition of the overexpression of the inflammatory cytokines, Bax and caspase-3 protein and partial restoration of Bcl-2 protein expression. Taken together, these results indicated that increased Nrf2 expression reduced IIR-induced intestinal apoptosis and that the protective function of Nrf2 may be based on its anti-inflammatory effects through the inhibition of the NF-κB pathway.

Inhaled anesthetic agent sedation in the ICU and trace gas concentrations: a review

There is a growing interest in the use of volatile anesthetics for inhalational sedation of adult critically ill patients in the ICU. Its safety and efficacy has been demonstrated in various studies and technical equipment such as the anaesthetic conserving device (AnaConDa™; Sedana Medical, Uppsala, Sweden) or the MIRUS™ system (Pall Medical, Dreieich, Germany) have significantly simplified the application of volatile anesthetics in the ICU. However, the personnel's exposure to waste anesthetic gas during daily work is possibly disadvantageous, because there is still uncertainty about potential health risks. The fact that average threshold limit concentrations for isoflurane, sevoflurane and desflurane either differ significantly between countries or are not even defined at all, leads to raising concerns among ICU staff. In this review, benefits, risks, and technical aspects of inhalational sedation in the ICU are discussed. Further, the potential health effects of occupational long-term low-concentration agent exposure, the staffs' exposure levels in clinical practice, and strategies to minimize the individual gas exposure are reviewed.

Immunomodulatory effects of anesthetics in obese patients

Anesthesia and surgery have an impact on inflammatory responses, which influences perioperative homeostasis. Inhalational and intravenous anesthesia can alter immune-system homeostasis through multiple processes that include activation of immune cells (such as monocytes, neutrophils, and specific tissue macrophages) with release of pro- or anti-inflammatory interleukins, upregulation of cell adhesion molecules, and overproduction of oxidative radicals. The response depends on the timing of anesthesia, anesthetic agents used, and mechanisms involved in the development of inflammation or immunosuppression. Obese patients are at increased risk for chronic diseases and may have the metabolic syndrome, which features insulin resistance and chronic low-grade inflammation. Evidence has shown that obesity has adverse impacts on surgical outcome, and that immune cells play an important role in this process. Understanding the effects of anesthetics on immune-system cells in obese patients is important to support proper selection of anesthetic agents, which may affect postoperative outcomes. This review article aims to integrate current knowledge regarding the effects of commonly used anesthetic agents on the lungs and immune response with the underlying immunology of obesity. Additionally, it identifies knowledge gaps for future research to guide optimal selection of anesthetic agents for obese patients from an immunomodulatory standpoint.

Volatile Anesthetics. Is a New Player Emerging in Critical Care Sedation?

Volatile anesthetic agent use in the intensive care unit, aided by technological advances, has become more accessible to critical care physicians. With increasing concern over adverse patient consequences associated with our current sedation practice, there is growing interest to find non-benzodiazepine-based alternative sedatives. Research has demonstrated that volatile-based sedation may provide superior awakening and extubation times in comparison with current intravenous sedation agents (propofol and benzodiazepines). Volatile agents may possess important end-organ protective properties mediated via cytoprotective and antiinflammatory mechanisms. However, like all sedatives, volatile agents are capable of deeply sedating patients, which can have respiratory depressant effects and reduce patient mobility. This review seeks to critically appraise current volatile use in critical care medicine including current research, technical consideration of their use, contraindications, areas of controversy, and proposed future research topics.

Immune Modulation by Volatile Anesthetics

Volatile general anesthetics continue to be an important part of clinical anesthesia worldwide. The impact of volatile anesthetics on the immune system has been investigated at both mechanistic and clinical levels, but previous studies have returned conflicting findings due to varied protocols, experimental environments, and subject species. While many of these studies have focused on the immunosuppressive effects of volatile anesthetics, compelling evidence also exists for immunoactivation. Depending on the clinical conditions, immunosuppression and activation due to volatile anesthetics can be either detrimental or beneficial. This review provides a balanced perspective on the anesthetic modulation of innate and adaptive immune responses as well as indirect effectors of immunity. Potential mechanisms of immunomodulation by volatile anesthetics are also discussed. A clearer understanding of these issues will pave the way for clinical guidelines that better account for the impact of volatile anesthetics on the immune system, with the ultimate goal of improving perioperative management.

p-JAK2 plays a key role in catalpol-induced protection against rat intestinal ischemia/reperfusion injury

Catalpol attenuated rat intestinal I/R injury by decreasing mitochondria-mediated apoptosis through blocking the JAK2/STAT3 signaling pathwayviaselective inhibition of p-JAK2.

Ischemic Preconditioning-Induced SOCS-1 Protects Rat Intestinal Ischemia Reperfusion Injury via Degradation of TRAF6

BACKGROUND

The inflammatory immune response plays an important role in mesenteric ischemia and ischemia-reperfusion injury. Toll-like receptor 4 (TLR4) is a critical receptor in transduction of the inflammatory response and plays an important role in intestinal homeostasis. Tumor necrosis factor receptor-associated factor 6 (TRAF6), known as a key adaptor protein downstream of TLR4, is involved in the inflammatory response by activating multiple apoptotic signaling pathways. However, mechanisms of the suppressor of cytokine signaling-1 (SOCS-1) in regulating cell inflammation and apoptosis are still obscure.

OBJECTIVES

To investigate the TLR4-TRAF6 signaling pathway in intestinal ischemia and reperfusion injury, as well as SOCS-1 expression after ischemic preconditioning in the rat intestine.

METHODS

The small bowel ischemia, ischemia-reperfusion, and preconditioning models were induced using ligation of the superior mesenteric artery in male Sprague-Dawley rats; then, the mRNA and protein levels of TLR4, TRAF6, and SOCS-1 were analyzed using real-time PCR, Western blot, and immunohistochemistry, respectively.

RESULTS

The expression of TLR4 and TRAF6 was gradually increased with increasing intestinal ischemia duration, but increased substantially after ischemia-reperfusion injury. After ischemic preconditioning, TLR4 and TRAF6 expressions decreased; however, expression of SOCS-1 and the TLR4-TRAF6 pathway inhibitor was increased.

CONCLUSION

These data show that ischemic preconditioning may induce the activation of SOCS-1 to inhibit the TLR4-TRAF6 signaling pathway, thereby playing a protective role in ischemia-reperfusion injury.

Resveratrol and curcumin as protective agents in an experimental rat model of intestinal ischemia and reperfusion

The aim of this study was to evaluate the protective effects of resveratrol and curcumin in an experimental rat model of intestinal ischemia–reperfusion (I/R). Forty-eight adult Wistar rats were used: 12 animals undergoing the sham surgery and 36 animals undergoing laparotomy, with 15 min of mesentric artery clamping. The animals from the latter group (n = 12) were pretreated, for 1 week, with vehicle (CTR), resveratrol (RES), and curcumin (CUR). After 1 h and 6 h of reperfusion, respectively, cyclooxigenase (COX)-2, mucin-1, E-cadherin, nuclear factor (NK)-κB expressions, and tumor necrosis factor related apoptosis-inducing ligand (TRAIL) were assessed in the small intestine. Oxidative stress markers were determined in tissue homogenate and serum, and histopathological analysis was performed. Pretreatment with RES decreased the expression of COX-2 and NF-κB at both intervals and increased E-cadherin (p < 0.05) and mucin-1 production after 1 h. CUR had a beneficial effect on COX-2, NF-κB, and E-cadherin expressions, both after 1 h and after 6 h (p < 0.0001). The two compounds increased TRAIL levels and had a protective effect on oxidative stress and histopathological lesions, both after 1 h and after 6 h. Our results suggested that RES and CUR had beneficial effects in intestinal I/R and may represent a promising option for complementary treatment of this pathological condition.

HDACi Valproic Acid (VPA) and Suberoylanilide Hydroxamic Acid (SAHA) Delay but Fail to Protect against Warm Hepatic Ischemia-Reperfusion Injury

BACKGROUND

Histone deacetylases (HDAC) catalyze N-terminal deacetylation of lysine-residues on histones and multiple nuclear and cytoplasmic proteins. In various animal models, such as trauma/hemorrhagic shock, ischemic stroke or myocardial infarction, HDAC inhibitor (HDACi) application is cyto- and organoprotective and promotes survival. HDACi reduce stress signaling, cell death and inflammation. Hepatic ischemia-reperfusion (I/R) injury during major liver resection or transplantation increases morbidity and mortality. Assuming protective properties, the aim of this study was to investigate the effect of the HDACi VPA and SAHA on warm hepatic I/R.

MATERIAL AND METHODS

Male Wistar-Kyoto rats (age: 6-8 weeks) were randomized to VPA, SAHA, vehicle control (pre-) treatment or sham-groups and underwent partial no-flow liver ischemia for 90 minutes with subsequent reperfusion for 6, 12, 24 and 60 hours. Injury and regeneration was quantified by serum AST and ALT levels, by macroscopic aspect and (immuno-) histology. HDACi treatment efficiency, impact on MAPK/SAPK-activation and Hippo-YAP signaling was determined by Western blot.

RESULTS

Treatment with HDACi significantly enhanced hyperacetylation of Histone H3-K9 during I/R, indicative of adequate treatment efficiency. Liver injury, as measured by macroscopic aspect, serum transaminases and histology, was delayed, but not alleviated in VPA and SAHA treated animals. Importantly, tissue destruction was significantly more pronounced with VPA. SAPK-activation (p38 and JNK) was reduced by VPA and SAHA in the early (6h) reperfusion phase, but augmented later on (JNK, 24h). Regeneration appeared enhanced in SAHA and VPA treated animals and was dependent on Hippo-YAP signaling.

CONCLUSIONS

VPA and SAHA delay warm hepatic I/R injury at least in part through modulation of SAPK-activation. However, these HDACi fail to exert organoprotective effects, in this setting. For VPA, belated damage is even aggravated.

miR-34a-5p Inhibition Alleviates Intestinal Ischemia/Reperfusion-Induced Reactive Oxygen Species Accumulation and Apoptosis via Activation of SIRT1 Signaling

AIMS

Reactive oxygen species (ROS) generation and massive epithelial apoptosis are critical in the pathogenesis of intestinal ischemia/reperfusion (I/R) injury. We previously found that the Sirtuin 1 (SIRT1)-mediated antioxidant pathway was impaired in the intestine after I/R. Here, we investigate the potential role of SIRT1-targeting microRNAs (miRNAs) in regulating ROS accumulation and apoptosis in intestinal I/R, and the important role SIRT1 involved in.

RESULTS

C57BL/6 mice were subjected to intestinal I/R induced by occlusion of the superior mesenteric artery followed by reperfusion. Caco-2 cells were incubated under hypoxia/reoxygenation condition to mimic I/R in vivo. We find that SIRT1 is gradually repressed during the early reperfusion, and that this repression results in intestinal ROS accumulation and apoptosis. Using bioinformatics analysis and real-time PCR, we demonstrate that miR-34a-5p and miR-495-3p are significantly increased among the 41 putative miRNAs that can target SIRT1. Inhibition of miR-34a-5p, but not miR-495-3p, attenuates intestinal I/R injury, as demonstrated by repressing p66shc upregulation, manganese superoxide dismutase repression, and the caspase-3 activation in vitro and in vivo; it further alleviates systemic injury, as demonstrated by reducing inflammatory cytokine release, attenuating lung and liver lesions, and improving survival. Interestingly, SIRT1 plays an indispensable role in the protection afforded by miR-34a-5p inhibition.

INNOVATION

This study provides the first evidence of miRNAs in regulating oxidative stress and apoptosis in intestinal I/R.

CONCLUSION

miR-34a-5p knockdown attenuates intestinal I/R injury through promoting SIRT1-mediated suppression of epithelial ROS accumulation and apoptosis. This may represent a novel prophylactic approach to intestinal I/R injury. Antioxid. Redox Signal. 24, 961-973.

TGF-β1 improves mucosal IgA dysfunction and dysbiosis following intestinal ischaemia-reperfusion in mice

Intestinal ischaemia/reperfusion (I/R) severely disrupts gut barriers and leads to high mortality in the critical care setting. Transforming growth factor (TGF)-β1 plays a pivotal role in intestinal cellular and immune regulation. However, the effects of TGF-β1 on intestinal I/R injury remain unclear. Thus, we aimed to investigate the effects of TGF-β1 on gut barriers after intestinal I/R and the molecular mechanisms. Intestinal I/R model was produced in mice by clamping the superior mesenteric artery for 1 hr followed by reperfusion. Recombinant TGF-β1 was intravenously infused at 15 min. before ischaemia. The results showed that within 2 hrs after reperfusion, intestinal I/R disturbed intestinal immunoglobulin A class switch recombination (IgA CSR), the key process of mucosal IgA synthesis, and resulted in IgA dysfunction, as evidenced by decreased production and bacteria-binding capacity of IgA. Meanwhile, the disruptions of intestinal microflora and mucosal structure were exhibited. Transforming growth factor-β1 activated IgA CSR as evidenced by the increased activation molecules and IgA precursors. Strikingly, TGF-β1 improved intestinal mucosal IgA dysfunction, dysbiosis and epithelial damage at the early stage after reperfusion. In addition, SB-431542, a specific inhibitor of activating mothers against decapentaplegic homologue (SMAD) 2/3, totally blocked the inductive effect of TGF-β1 on IgA CSR and almost abrogated the above protective effects on intestinal barriers. Taken together, our study demonstrates that TGF-β1 protects intestinal mucosal IgA immunity, microbiota and epithelial integrity against I/R injury mainly through TGF-β receptor 1/SMAD 2/3 pathway. Induction of IgA CSR may be involved in the protection conferred by TGF-β1.

Transforming growth factor-β1 protects against intestinal epithelial barrier dysfunction caused by hypoxia-reoxygenation

Intestinal epithelia regulate barrier integrity when challenged by inflammation, oxidative stress, and microbes. Transforming growth factor-β1 (TGF-β1) is a cytokine with known beneficial effects on intestinal epithelia, including barrier enhancement, after exposure to proinflammatory cytokines and infectious agents. The aim of this study was to determine whether TGF-β1 directly protects intestinal epithelia during hypoxia-reoxygenation (HR). Intestinal epithelial monolayers (T84, Caco-2) were exposed to either hypoxia (1% O2, 1 h) or oxidative stress (hydrogen peroxide, 1 mM), followed by normoxic atmosphere for different time points in the absence and presence of varying concentrations of TGF-β1. Transepithelial electrical resistance (TER) assessed barrier function, with RNA extracted for reverse transcription polymerase chain reaction analysis of GPx-1, HIF-1, heme-oxygenase-1 (HO-1), and NOX-1. In some experiments, intestinal epithelia were exposed to enterohemorrhagic Escherichia coli (EHEC) O157:H7 during the reoxygenation period and TER recorded 7 h after the infectious challenge. Hypoxia-reoxygenation significantly decreased TER in intestinal epithelia compared with normoxic controls. Transforming growth factor-β1 pretreatment ameliorated HR-induced epithelial barrier dysfunction in T84 (at 1 - 3 h) and Caco-2 (1 h) monolayers. Transforming growth factor-β1 preserved barrier integrity for up to 16 h after challenge with hydrogen peroxide. In TGF-β1-treated epithelial monolayers, only HO-1 mRNA significantly increased after HR (P < 0.05 vs. normoxic controls). The EHEC-induced epithelial barrier dysfunction was significantly worsened by intestinal HR (P < 0.05 vs. normoxia-EHEC-infected cells), but this was not protected by TGF-β1 pretreatment. Transforming growth factor-β1 preserves loss of epithelial barrier integrity caused by the stress of HR via a mechanism that may involve the upregulation of HO-1 transcription. Targeted treatment with TGF-β could lead to novel therapies in enteric diseases characterized by HR injury.

Protection of rat intestinal epithelial cells from ischemia/reperfusion injury by (D-Ala2, D-Leu5)-enkephalin through inhibition of the MKK7-JNK signaling pathway

Previous studies have demonstrated that (D‑Ala2, D‑Leu5)‑enkephalin (DADLE) protects rats from hepatic ischemia/reperfusion (I/R) injury. In the present study, DADLE was also observed to alleviate IR‑induced intestinal epithelial cell injury in rats by inhibiting mitogen‑activated protein kinase kinase 7 (MKK7)‑c‑Jun N‑terminal kinase (JNK) pathway signaling. To investigate the protective effect of DADLE on hypoxia/reoxygenation injury in rat intestinal epithelial cells, rat intestinal epithelial cells were treated with different concentrations of DADLE, following which the cell survival rate was determined using a tetrazolium (MTT) colorimetric assay, and apoptosis was determined using flow cytometry. To confirm whether the protective effect of DADLE was due to its effect on MKK7‑JNK signaling, the phosphorylation levels of MKK7 and JNK were analyzed using western blot analysis following treatment with different concentrations of DADLE. The results demonstrated that, following treatment with DADLE, the survival rate of the rat intestinal cells subjected to I/R‑induced injury increased significantly and the apoptotic rate decreased in a concentration‑dependent manner. In addition, the levels of phosphorylated MKK7 and JNK decreased in a concentration‑dependent manner following treatment with DADLE. Silencing the gene expression of MKK7 using small interfering RNA prior to DADLE treatment resulted in a reduction in the protective effects of DADLE on the rat intestinal epithelial cells subjected to I/R injury. Collectively, the results of the present study demonstrated that the protective effects of DADLE in I/R injury in rat intestinal cells occurred through inhibition of the MKK7‑JNK pathway.

Improving Research Practice in Rat Orthotopic and Partial Orthotopic Liver Transplantation: A Review, Recommendation, and Publication Guide

Background: Due to a worldwide shortage of donor organs for liver transplantation, alternative approaches, such as split and living donor liver transplantations, were introduced to increase the donor pool and reduce mortality on liver transplant waiting lists. Numerous details concerning the mechanisms and pathophysiology of liver regeneration, small-for-size syndrome, rejection, and tolerance in partial liver transplantation facilitated the development of various animal models. The high number of preclinical animal studies contributed enormously to our understanding of many clinical aspects of living donor and partial liver transplantations. Summary: Microsurgical rat models of partial orthotopic liver transplantation are well established and widely used. Nevertheless, several issues regarding this procedure are controversial, not clarified, or not yet properly standardized (graft rearterialization, size reduction techniques, etc.). The major aim of this literature review is to give the reader a current overview of rat orthotopic liver transplantation models with a special focus on partial liver transplantation. The aspects of model evolution, microsurgical training, and different technical problems are analyzed and discussed in detail. Our further aim in this paper is to elaborate a detailed publication guide in order to improve the quality of reporting in the field of rat liver transplantation according to the ARRIVE guidelines and the 3R principle. Key Messages: Partial orthotopic liver transplantation in rats is an indispensable, reliable, and cost-efficient model for transplantation research. A certain consensus on different technical issues and a significant improvement in scientific reporting are essential to improve transparency and comparability in this field as well as to foster refinement.

Variations in the risk of acute kidney injury across intraabdominal surgery procedures

BACKGROUND

The literature on perioperative acute kidney injury (AKI) focuses mainly on cardiac and major vascular surgery. Among noncardiac general surgery procedures, intraabdominal general surgery has been identified as high risk for developing AKI, but variations in AKI risk and its impact on 30-day mortality among different types of abdominal surgeries are not well characterized.

METHODS

We used the American College of Surgeons National Surgical Quality Improvement Program (2005-2010) to identify patients in 15 intraabdominal general surgery procedure categories (n = 457,656). AKI was defined as an increase in the creatinine level of >2 mg/dL above baseline and/or dialysis. Relative risk regression modeling was used to assess the relative risks of AKI across the procedures. The relationships among surgical procedure, AKI, and 30-day mortality stratified by procedure type were assessed using relative risk regression.

RESULTS

The overall incidence of AKI among intraabdominal surgery patients was 1.1%, which varied from 0.2% in appendectomy and 0.3% in gastric bypass patients to 2.6% in small bowel resection and 3.5% in exploratory laparotomy patients. Of the patients who developed AKI, 31.3% died within 30 days, compared with 1.9% of those who did not develop AKI. After adjusting for comorbidities and operative factors, AKI was associated with a 3.5-fold increase in the risk of 30-day mortality (adjusted risk ratio, 3.51, 95% confidence interval [CI], 3.29-3.74). Among individual procedures, the estimated adjusted risk ratio of 30-day mortality associated with AKI ranged from 1.87 (95% CI, 1.62-2.17) in exploratory laparotomy to 31.6 (95% CI, 17.9-55.9) in gastric bypass.

CONCLUSIONS

The incidence of AKI and the impact of AKI on 30-day mortality vary markedly across procedures within intraabdominal general surgery. This highlights the importance of preoperative risk stratification and identifies procedure type as a significant risk factor for AKI and 30-day mortality.

Optimizing anesthetic regimen for surgery in mice through minimization of hemodynamic, metabolic, and inflammatory perturbations

The role of anesthetics in animal research models is crucial, yet often ignored, and is almost never the primary focus of examination. Here, we investigated the impact of anesthetic regimens on different parameters of hemodynamics (blood pressure (BP) and heart rate (HR)), metabolism (glucose, insulin, and free fatty acids (FFA)), and inflammation (IL-6 and TNF-α) in two frequently used mouse strains (C57BL/6 and FVB). All animals were at a similar surgical plane of anesthesia, mechanically ventilated, and monitored for 60 min. The following anesthetic regimens were studied: (1) fentanyl-ketamine-midazolam (FKM), (2) fentanyl-midazolam-haldol (FMH), (3) pentobarbital (P), (4) fentanyl-fluanisone-midazolam (FFM), (5) fentanyl-midazolam-acepromazine (FMA), (6) ketamine-medetomidine-atropine (KMA), (7) isoflurane (ISO), and (8) propofol-fentanyl-midazolam (PFM). Metabolic and inflammatory parameters were compared with those obtained from non-anesthetized animals. Hemodynamics: BP >80 mm Hg were only obtained with KMA, whereas hypotension (BP <60 mm Hg) was observed with FKM and P. HR >500 beats/min was observed with ISO and PFM, whereas HR <400 beats/min was induced with KMA, FMH (BL/6), P (BL/6), and FKM (FVB). Metabolism: Glucose and insulin were most disturbed by KMA and ISO and mildly disturbed by FMA, whereas FFM, PFM, and P did not have any effect. FFA increased largely by FMA, with ISO and FKM having no effects. Inflammation: Cytokines were increased least with ISO/FFM/FMA, whereas FKM and KMA induced the largest increases in cytokines. When aiming at achieving surgical anesthesia without large disturbances in hemodynamic, metabolic, and inflammatory profiles, FFM, ISO, or PFM may be the most neutral anesthetic regimens in mice.

Role of Hydrogen Sulfide in Ischemia-Reperfusion Injury

Ischemia-reperfusion (I/R) injury is one of the major causes of high morbidity, disability, and mortality in the world. I/R injury remains a complicated and unresolved situation in clinical practice, especially in the field of solid organ transplantation. Hydrogen sulfide (H₂S) is the third gaseous signaling molecule and plays a broad range of physiological and pathophysiological roles in mammals. H₂S could protect against I/R injury in many organs and tissues, such as heart, liver, kidney, brain, intestine, stomach, hind-limb, lung, and retina. The goal of this review is to highlight recent findings regarding the role of H₂S in I/R injury. In this review, we present the production and metabolism of H₂S and further discuss the effect and mechanism of H₂S in I/R injury.

A role of microRNA-370 in hepatic ischaemia-reperfusion injury by targeting transforming growth factor-β receptor II

BACKGROUND & AIMS

MicroRNAs (miRNAs) are a group of small non-coding RNAs with modulator activity of gene expression. The role of miRNAs in hepatic ischaemia-reperfusion (IR) injury is currently largely unknown. The aim of this study was to investigate the potential role of miR-370 in hepatic IR injury.

METHODS

The expression levels of hepatic miR-370 in male C57BL/6 mice subjected to hepatic IR injury or ischaemia preconditioning were assessed by quantitative real-time PCR. The effect of miR-370 on hepatic IR injury was investigated by serum enzyme analysis and histological examination of liver following treatment of mice with antagomir-370 or control. The levels of proinflammatory cytokines and apoptosis- and proliferation-related genes were also determined by quantitative real-time PCR. Furthermore, the potential targets of miR-370 in this injury were studied by bioinformatics analysis, luciferase assays, quantitative real-time PCR and Western blot.

RESULTS

The results showed that miR-370 expression was significantly upregulated in the mice subjected to hepatic IR injury as compared with the sham-operated mice. Inhibition of miR-370 led to the downregulation of serum aminotransferase and proinflammatory cytokines, as well as the improvement of hepatic histological damage. Reporter assays confirmed that miR-370 directly targeted the 3' untranslated region of transforming growth factor-β receptor II (TβRII). Inhibition of miR-370 was sufficient to reinstate the expression of TβRII and its downstream target phosphorylated Smad3.

CONCLUSION

Our data suggest that miR-370 acting via TβRII might play a potential role in hepatic IR injury, and inhibition of miR-370 efficiently attenuated the damage to the liver.

Circulating levels of platelet α-granule cytokines in trauma patients

OBJECTIVE AND DESIGN

To elucidate whether platelets differentiate cytokine release following trauma, we prospectively measured three major platelet-derived cytokines in 213 trauma patients on hospital arrival.

METHODS

We measured plasma levels of the anti-inflammatory β-thromboglobulins (βTGs), transforming growth factor-β1 (TGFβ1) and the pro-inflammatory platelet factor 4 (PF4) cytokines. We also measured soluble glycoprotein VI (sGPVI), procoagulant platelet microparticles (PMPs) and white blood cell (WBC) counts, and evaluated in vitro platelet function in primary and secondary haemostasis by aggregometry and thromboelastometry, respectively. We evaluated associations of each cytokine by multivariate regression including injury severity score (ISS), WBC counts, sGPVI and platelet counts as explanatory variables.

RESULTS

Severely injured patients (ISS > 15) had higher levels of βTGs and TGFβ1 (both p < 0.01) but lower levels of PF4 (p = 0.02). GPVI and PMPs levels correlated with TGFβ1 and PF4 whereas we found no significant association between cytokine levels and measures of haemostasis. By multivariate regression, a high WBC count was associated with high levels of TGFβ1 (p = 0.01) and βTGs (p < 0.01) but with low levels of PF4 (p = 0.03).

CONCLUSION

Severely injured patients had higher levels of βTGs and TGFβ1 but lower levels of the PF4; a high WBC count predicted this anti-inflammatory profile of platelet cytokines.

Propofol increases morbidity and mortality in a rat model of sepsis

INTRODUCTION

Severe sepsis is associated with approximately 50% mortality and accounts for tremendous healthcare costs. Most patients require ventilatory support and propofol is commonly used to sedate mechanically ventilated patients. Volatile anesthetics have been shown to attenuate inflammation in a variety of different settings. We therefore hypothesized that volatile anesthetic agents may offer beneficial immunomodulatory effects during the course of long-term intra-abdominal sepsis in rats under continuous sedation and ventilation for up to 24 hours.

METHODS

Sham operation or cecal ligation and puncture (CLP) was performed in adult male Wistar rats followed by mechanical ventilation. Animals were sedated for 24 hours with propofol (7 to 20 mg/kg/h), sevoflurane, desflurane or isoflurane (0.7 minimal alveolar concentration each).

RESULTS

Septic animals sedated with propofol showed a mean survival time of 12 hours, whereas >56% of all animals in the volatile groups survived 24 hours (P <0.001). After 18 hours, base excess in propofol + CLP animals (-20.6 ± 2.0) was lower than in the volatile groups (isoflurane + CLP: -11.7 ± 4.2, sevoflurane + CLP: -11.8 ± 3.5, desflurane + CLP -14.2 ± 3.7; all P <0.03). Plasma endotoxin levels reached 2-fold higher levels in propofol + CLP compared to isoflurane + CLP animals at 12 hours (P <0.001). Also blood levels of inflammatory mediators (tumor necrosis factor-α, interleukin-1β, interleukin-10, CXCL-2, interferon-γ and high mobility group protein-1) were accentuated in propofol + CLP rats compared to the isoflurane + CLP group at the same time point (P <0.04).

CONCLUSIONS

This is the first study to assess prolonged effects of sepsis and long-term application of volatile sedatives compared to propofol on survival, cardiovascular, inflammatory and end organ parameters. Results indicate that volatile anesthetics dramatically improved survival and attenuate systemic inflammation as compared to propofol. The main mechanism responsible for adverse propofol effects could be an enhanced plasma endotoxin concentration, leading to profound hypotension, which was unresponsive to fluid resuscitation.

Significance of changes in Toll-like receptor 4 and TRAF6 expression in intestinal ischemic injury in rats

AIM: To investigate the changes in the expression of Toll-like receptor 4 (TLR4) and tumor necrosis factor receptor associated-factor 6 (TRAF6) in intestinal ischemic injury in rats and to analyze their significance.

METHODS: Thirty-two adult male SD rats were randomly and equally divided into four groups: a sham operation group, and 1-, 3- and 6-h ischemia groups. Superior mesenteric artery ligation was performed in SD rats to induce intestinal ischemia. Real-time quantitative PCR (qPCR) and Western blot were carried out to detect the expression of TLR4 and TRAF6 in intestinal tissues. Meanwhile, the level of myeloperoxidase (MPO) was measured.

RESULTS: Compared with the sham operation group (20.65 U/L ± 6.88 U/L), MPO level was slightly elevated in the intestine in the 1-h ischemia group (23.27 U/L ± 3.00 U/L), but significantly increased in the 3-h (35.73 U/L ± 5.04 U/L, P < 0.01) and 6-h ischemia groups (51.79 U/L ± 2.27 U/L, P < 0.01). TLR4 expression gradually increased in the three ischemia groups (P < 0.01), while TRAF6 expression decreased in the intestine in the 1-h ischemia group, but rapidly increased in the 3- and 6-h groups (P < 0.05).

CONCLUSION: TLR4 and TRAF6 may be involved in regulating intestinal damage and inflammatory processes in rats with intestinal ischemic injury.

The immune response to anesthesia: part 1

OBJECTIVE

To review the immune response to anesthesia including mechanical ventilation, inhaled anesthetic gases, and injectable anesthetics and sedatives.

STUDY DESIGN

Review.

METHODS AND DATABASES

Multiple literature searches were performed using PubMed and Google Scholar from spring 2012 through fall 2013. Relevant anesthetic and immune terms were used to search databases without year published or species constraints. The online database for Veterinary Anaesthesia and Analgesia and the Journal of Veterinary Emergency and Critical Care were searched by issue starting in 2000 for relevant articles.

CONCLUSION

Recent research data indicate that commonly used volatile anesthetic agents, such as isoflurane and sevoflurane, may have a protective effect on vital organs. With the lung as the target organ, protection using an appropriate anesthetic protocol may be possible during direct pulmonary insults, including mechanical ventilation, and during systemic disease processes, such as endotoxemia, generalized sepsis, and ischemia-reperfusion injury.

The volatile anesthetic isoflurane increases endothelial adenosine generation via microparticle ecto-5'-nucleotidase (CD73) release

Endothelial dysfunction is common in acute and chronic organ injury. Isoflurane is a widely used halogenated volatile anesthetic during the perioperative period and protects against endothelial cell death and inflammation. In this study, we tested whether isoflurane induces endothelial ecto-5′-nucleotidase (CD73) and cytoprotective adenosine generation to protect against endothelial cell injury. Clinically relevant concentrations of isoflurane induced CD73 activity and increased adenosine generation in cultured human umbilical vein or mouse glomerular endothelial cells. Surprisingly, isoflurane-mediated induction of endothelial CD73 activity occurred within 1 hr and without synthesizing new CD73. We determined that isoflurane rapidly increased CD73 containing endothelial microparticles into the cell culture media. Indeed, microparticles isolated from isoflurane-treated endothelial cells had significantly higher CD73 activity as well as increased CD73 protein. In vivo, plasma from mice anesthetized with isoflurane had significantly higher endothelial cell-derived CD144+ CD73+ microparticles and had increased microparticle CD73 activity compared to plasma from pentobarbital-anesthetized mice. Supporting a critical role of CD73 in isoflurane-mediated endothelial protection, a selective CD73 inhibitor (APCP) prevented isoflurane-induced protection against human endothelial cell inflammation and apoptosis. In addition, isoflurane activated endothelial cells Rho kinase evidenced by myosin phosphatase target subunit-1 and myosin light chain phosphorylation. Furthermore, isoflurane-induced release of CD73 containing microparticles was significantly attenuated by a selective Rho kinase inhibitor (Y27632). Taken together, we conclude that the volatile anesthetic isoflurane causes Rho kinase-mediated release of endothelial microparticles containing preformed CD73 and increase adenosine generation to protect against endothelial apoptosis and inflammation.

Osthole prevents intestinal ischemia-reperfusion-induced lung injury in a rodent model

BACKGROUND

Intestinal ischemia-reperfusion (II/R) is associated with high morbidity and mortality. The aim of this study was to investigate the effects of osthole on lung injury and mortality induced by II/R.

METHODS

A rat model of II/R was induced by clamping the superior mesenteric artery for 90 min followed by reperfusion for 240 min. Osthole was administrated intraperitoneally at 30 min before intestinal ischemia (10 or 50 mg/kg). The survival rate and mean arterial pressure were observed. Blood samples were obtained for blood gas analyses. Lung injury was assessed by the histopathologic changes (hematoxylin and eosin staining), lung wet-to-dry weight ratio, and pulmonary permeability index. The levels of reactive oxygen species, malondialdehyde, interleukin 6, and tumor necrosis factor α, as well as the activities of superoxide dismutase and myeloperoxidase in lung were measured.

RESULTS

The survival rate, ratio of arterial oxygen tension to fraction of inspired oxygen, and mean arterial pressure decreased significantly after II/R. Results also indicated that II/R-induced severe lung injury evidenced by increase in pathologic scores, lung wet-to-dry weight ratio, and pulmonary permeability index, which was accompanied by increases in the levels of pulmonary reactive oxygen species, malondialdehyde, interleukin 6, tumor necrosis factor α, and the pulmonary myeloperoxidase activity and a decrease in superoxide dismutase activity. Osthole could significantly ameliorate lung injury and improve the previously mentioned variables.

CONCLUSIONS

These findings indicated that osthole could attenuate the lung injury induced by II/R in rats, at least in part, by inhibiting inflammatory response and oxidative stress.

Preconditioning renoprotective effect of isoflurane in a rat model of virtual renal transplant

BACKGROUND

The development of warm-cold ischemia-reperfusion (IR) injury of the kidney grafts is inevitable during renal transplantation. However, there is currently no definite renoprotective strategy available in the protection of the graft tissue. In the present study, we compared the renal protection of preconditioning isoflurane with N-acetylcysteine (NAC) in a novel rat model of warm-cold renal IR injury.

MATERIALS AND METHODS

Adult Sprague-Dawley rats were randomly assigned to receive inhaled isoflurane (1.5% for 2 h), NAC (1 g/kg, intra-arterial injection) or placebo before the induction of brief warm ischemia (10 min) followed by cold ischemia (45 min) periods. Plasma levels of creatinine and tissue inflammatory reaction in the kidney were analyzed 72 h after reperfusion.

RESULTS

Elevated plasma level of creatinine and urea indicated the development of acute renal injury secondary to IR injury. The creatinine levels were reduced in animals pretreated with inhaled isoflurane and NAC, and the level was more significantly decreased in the isoflurane-treated group. Preconditioning with volatile isoflurane also significantly suppressed the tissue myeloperoxidase activity and expression of the inducible nitric oxide synthase. Immunostaining confirmed that myeloperoxidase expression was most significantly attenuated in the glomerulus and peritubular capillaries of rats pre-exposed to isoflurane.

CONCLUSIONS

We present the first study demonstrating that the administration of volatile isoflurane before induction of experimental warm-cold renal IR injury provides preconditioning renoprotective effect, which is superior to the treatment with NAC. The beneficial renoprotective effect of isoflurane is most likely mediated by attenuation of proinflammatory reaction in the injured kidney.

Impact of Anesthetics on Immune Functions in a Rat Model of Vagus Nerve Stimulation

Vagus nerve stimulation (VNS) has been successfully performed in animals for the treatment of different experimental models of inflammation. The anti-inflammatory effect of VNS involves the release of acetylcholine by vagus nerve efferent fibers inhibiting pro-inflammatory cytokines (e.g. TNF-α) produced by macrophages. Moreover, it has recently been demonstrated that splenic lymphocytic populations may also be involved. As anesthetics can modulate the inflammatory response, the current study evaluated the effect of two different anesthetics, isoflurane and pentobarbital, on splenic cellular and molecular parameters in a VNS rat model. Spleens were collected for the characterization of lymphocytes sub-populations by flow cytometry and quantification of cytokines secretion after in vitro activation. Different results were observed depending on the anesthetic used. The use of isoflurane displayed a non-specific effect of VNS characterized by a decrease of most splenic lymphocytes sub-populations studied, and also led to a significantly lower TNF-α secretion by splenocytes. However, the use of pentobarbital brought to light immune modifications in non-stimulated animals that were not observed with isoflurane, and also revealed a specific effect of VNS, notably at the level of T lymphocytes’ activation. These differences between the two anesthetics could be related to the anti-inflammatory properties of isoflurane. In conclusion, pentobarbital is more adapted than isoflurane in the study of the anti-inflammatory effect of VNS on an anesthetized rat model in that it allows more accurate monitoring of subtle immunomodulatory processes.

Remifentanil ameliorates intestinal ischemia-reperfusion injury

Background

Intestinal ischemia-reperfusion injury (IRI) can occur in clinical scenarios such as organ transplantation, trauma and cardio-pulmonary bypass, as well as in neonatal necrotizing enterocolitis or persistent ductus arteriosus. Pharmacological protection by pretreating (“preconditioning”) with opioids attenuates IRI in a number of organs. Remifentanil appears particularly attractive for this purpose because of its ultra-short duration of action and favorable safety profile. To date, little is known about opioid preconditioning of the intestine.

Methods

Young adult C57BL/6J mice were randomly assigned to receive tail vein injections of 1 μg/kg of remifentanil or normal saline and underwent either ischemia-reperfusion of the intestine or a sham laparotomy. Under isoflurane anesthesia, the mice were subjected to intestinal ischemia-reperfusion by occlusion (clamping) of the superior mesenteric artery for 30 min, followed by unclamping and 60 min of reperfusion. After completion of this protocol, tissue injury and lipid peroxidation in jejunum and ileum were analyzed by histology and malondialdehyde (MDA), respectively. Systemic interleukin (IL)-6 was determined in the plasma by ELISA.

Results

Pretreatment with remifentanil markedly reduced intestinal IRI (P < 0.001): In the ileum, we observed a more than 8-fold decrease in injured villi (4% vs 34% in saline-pretreated animals). In fact, the mucosa in the remifentanil group was as healthy as that of sham-operated animals. This protective effect was not as pronounced in the jejunum, but the percentage of damaged villi was still reduced considerably (18% vs 42%). There was up to 3-fold more tissue MDA after intestinal ischemia-reperfusion than after sham laparotomy, but this increase in lipid peroxidation was prevented by preconditioning with remifentanil (P < 0.05). The systemic inflammatory response triggered by intestinal IRI was significantly attenuated in mice pretreated with remifentanil (159 vs 805 pg/ml of IL-6 after saline pretreatment, with 92 pg/ml in the sham groups). After sham operations, no difference was detected between the saline- and remifentanil-pretreatments in any of the parameters investigated.

Conclusion

Preconditioning with remifentanil attenuates intestinal IRI and the subsequent systemic inflammatory response in mice. We therefore suggest that prophylaxis with this ultra-short-acting opioid may be advantageous in various clinical scenarios of human IRI.

Effective neuroprotection by ischemic postconditioning is associated with a decreased expression of RGMa and inflammation mediators in ischemic rats

Whether ischemic postconditioning (IPC) can significantly alleviate ischemic injury hinges on the appropriate measure. In this study, the expression RGMa and IL-1β, IL-6 are investigated to estimate the therapeutic benefits of various postconditioning strategies after cerebral ischemia/reperfusion. The study consists of the sham-operated group and five treatment groups: ischemia/reperfusion (I/R), two proximate ischemic postconditioning (IPC-S and IPC-M), remote postconditioning (RIPC) and delayed postconditioning (DIPC) groups. We find that rats in IPC and RIPC groups exhibit significantly less neural deficit and lower infarct volume than that in I/R and DIPC groups after ischemia/reperfusion. Moreover, in ischemic cortex and hippocampus, the mRNA level of RGMa is much lower in IPC and RIPC groups. Immunohistochemical analysis indicates that the expression of RGMa, IL-1β and IL-6 are reduced in IPC and RIPC groups (especially in IPC-S group). Furthermore, neurofilament staining reveals that the rats in IPC and RIPC groups have less axonal injury than that in I/R and DIPC groups. Our studies suggest that the optimal strategy to attenuate cerebral ischemia/reperfusion is achieved by early, short-term, and multiple cycles of proximal IPC. The cerebral protective effect of IPC may be associated with the decreased expression of RGMa and inflammation mediators.

Critical role of interleukin-17A in murine intestinal ischemia-reperfusion injury

Intestinal ischemia-reperfusion (I/R) injury causes severe illness frequently complicated by remote multiorgan dysfunction and sepsis. Recent studies implicated interleukin-17A (IL-17A) in regulating inflammation, autoimmunity, and I/R injury. Here, we determined whether IL-17A is critical for generation of intestinal I/R injury and subsequent liver and kidney injury. Mice subjected to 30 min of superior mesenteric artery ischemia not only developed severe small intestinal injury (necrosis, apoptosis, and neutrophil infiltration) but also developed significant renal and hepatic injury. We detected large increases in IL-17A in the small intestine, liver, and plasma. IL-17A is critical for generating these injuries, since genetic deletion of IL-17A- or IL-17A-neutralizing antibody treatment markedly protected against intestinal I/R injury and subsequent liver and kidney dysfunction. Intestinal I/R caused greater increases in portal plasma and small intestine IL-17A, suggesting an intestinal source for IL-17A generation. We also observed that intestinal I/R caused rapid small intestinal Paneth cell degranulation and induced murine α-defensin cryptdin-1 expression. Furthermore, genetic or pharmacological depletion of Paneth cells significantly attenuated the intestinal I/R injury as well as hepatic and renal dysfunction. Finally, Paneth cell depletion significantly decreased small intestinal, hepatic, and plasma IL-17A levels after intestinal I/R. Taken together, we propose that Paneth cell-derived IL-17A may play a critical role in intestinal I/R injury as well as extraintestinal organ dysfunction.

[Postconditioning -- effective method against distant organ dysfunction?]

INTRODUCTION

The ischemia-reperfusion injury of the small intestine is a condition of high mortality, which occurs following superior mesenteric artery (SMA) embolization or circulatory redistribution. The aim of the study was to evaluate the local and systemic effects of postconditioning in a rat model of small intestine ischemia-reperfusion.

METHODS

Male Wistar rats underwent 60 min ischemia by the clamping of the SMA, followed by 6 hrs of reperfusion. The animals (n = 30) were randomized into three groups: sham-operated, control-, and postconditioned. Postconditioning was performed at the very onset of reperfusion by 6 alternating cycles of 10-10 seconds reperfusion/reocclusion, for a total of 2 min. At the end of the reperfusion blood and tissue (small intestine, lungs, kidney, liver) samples were taken for histological examination. The antioxidant status of small intestine was measured from intestinal homogenates.

RESULTS

Histologic results revealed increased damage in control-group lungs, kidney, liver and small intestine in comparison with the postconditioned group. The injury was supported by significantly higher wet/dry weight ratio (p = 0.026), and serum levels of creatinine (p = 0.013), ASAT (p = 0.038), LDH (p = 0.028) and CK (p = 0.038) in the control group. The postconditioned group showed lower serum IL-6 levels (420 pg/ml vs. 188 pg/ml), as well as significantly higher mucosal antioxidant concentration.

CONCLUSIONS

Postconditioning was able to decrease not only local, but the systemic damage intensity also, after a small intestinal ischemic-reperfusion episode.

Isoflurane protects against human endothelial cell apoptosis by inducing sphingosine kinase-1 via ERK MAPK

Endothelial dysfunction is a major clinical problem affecting virtually every patient requiring critical care. Volatile anesthetics are frequently used during the perioperative period and protect the heart and kidney against ischemia and reperfusion injury. We aimed to determine whether isoflurane, the most commonly used volatile anesthetic in the USA, protects against endothelial apoptosis and necrosis and the mechanisms involved in this protection. Human endothelial EA.hy926 cells were pretreated with isoflurane or carrier gas (95% room air + 5% CO₂) then subjected to apoptosis with tumor necrosis factor-α or to necrosis with hydrogen peroxide. DNA laddering and in situ Terminal Deoxynucleotidyl Transferase Biotin-dUTP Nick-End Labeling (TUNEL) staining determined EA.hy926 cell apoptosis and percent LDH released determined necrosis. We also determined whether isoflurane modulates the expression and activity of sphingosine kinase-1 (SK1) and induces the phosphorylation of extracellular signal regulated kinase (ERK MAPK) as both enzymes are known to protect against cell death. Isoflurane pretreatment significantly decreased apoptosis in EA.hy926 cells as evidenced by reduced TUNEL staining and DNA laddering without affecting necrosis. Mechanistically, isoflurane induces the phosphorylation of ERK MAPK and increased SK1 expression and activity in EA.hy926 cells. Finally, selective blockade of SK1 (with SKI-II) or S1P₁ receptor (with W146) abolished the anti-apoptotic effects of isoflurane. Taken together, we demonstrate that isoflurane, in addition to its potent analgesic and anesthetic properties, protects against endothelial apoptosis most likely via SK1 and ERK MAPK activation. Our findings have significant clinical implication for protection of endothelial cells during the perioperative period and patients requiring critical care.