Effects of sevoflurane general anesthesia: immunological studies in mice

Intermittent fasting alleviates postoperative cognitive dysfunction by reducing neuroinflammation in aged mice

Elderly individuals undergoing surgical procedures are often confronted with the peril of experiencing postoperative cognitive dysfunction (POCD). Prior research has demonstrated the exacerbating effect of sevoflurane anesthesia on neuroinflammation, which can further deteriorate the condition of POCD in elderly patients. Intermittent fasting (IF) restricts food consumption to a specific time window and has been demonstrated to ameliorate cognitive dysfunction induced by neuropathic inflammation. We subjected 18-month-old male mice to 16 hours of fasting and 8 hours of unrestricted eating over a 24-hour period for 0, 1, 2, and 4 weeks, followed by abdominal exploration under sevoflurane anesthesia. In this study, we aim to explore the potential impact of IF on postoperative cognitive function in aged mice undergoing sevoflurane surgery through the preoperative implementation of IF measures. The findings indicate two weeks of IF leads to a significant enhancement of learning and memory capabilities in mice following surgery. The cognitive performance, as determined by the novel object recognition and Morris water maze tests, as well as the synaptic plasticity, as measured by in vivo electrophysiological recordings, has demonstrated marked improvements. Furthermore, the administration of IF markedly enhances the expression of synaptic-associated proteins in hippocampal neurons, concomitant with a decreasing expression of pro-inflammatory factors and a reduced density of microglial cells within the hippocampal brain region. To summarize, the results of this study indicate that IF may mitigate inflammation in the hippocampal area of the brain. Furthermore, IF appears to provide a safeguard against cognitive impairment and synaptic plasticity impairment brought on by sevoflurane anesthesia.

Systemic immune effects of anesthetics and their intracellular targets in tumors

According to the result released by the World Health Organization (WHO), non-communicable diseases have occupied four of the top 10 current causes for death in the world. Cancer is one of the significant factors that trigger complications and deaths; more than 80% cancer patients require surgical or palliative treatment. In this case, anesthetic treatment is indispensable. Since cancer is a heterogeneous disease, various types of interventions can activate oncogenes or mutate tumor suppressor genes. More and more researchers believe that anesthetics have a certain effect on the long-term recurrence and metastasis of tumors, but it is still controversial whether they promote or inhibit the progression of cancer. On this basis, a series of retrospective or prospective randomized clinical trials have been conducted, but it seems to be difficult to reach a conclusion within 5 years or longer. This article focuses on the effects of anesthetic drugs on immune function and cancer and reviews their latest targets on the tumor cells, in order to provide a theoretical basis for optimizing the selection of anesthetic drugs, exploring therapeutic targets, and improving the prognosis of cancer patients.

Sevoflurane Inhibits Metastasis in Hepatocellular Carcinoma by Inhibiting MiR-665-Induced Activation of the ERK/MMP Pathway

Recent evidence has indicated that inhalational anesthetics may affect the growth and malignant potential of tumor cells and ultimately influence tumor recurrence after surgery. Sevoflurane, a volatile anesthetic, is used extensively in hepatectomy. However, the effect of sevoflurane on the growth of hepatocellular carcinoma (HCC) cells remains unknown. The aim of this study was to explore the effects of sevoflurane on HCC metastasis and its potential mechanisms in the human HCC cell lines, HepG2 and SMMC7721. HepG2 and SMMC7721 cells were treated with 1.7%, 3.4%, and 5.1 % sevoflurane for 6 h. Cell migration was analyzed using invasion, migration, and scratch assays. Based on previous literature, several microRNAs (miRNAs) were screened to determine regulatory miRNA targets of sevoflurane in HepG2 and SMMC7721 cells; miR-665 was detected as a potential target and overexpressed or inhibited in HepG2 and SMMC7721 cells by a lentiviral system. The p-ERK/MMP pathway was also measured by western blotting. Sevoflurane inhibited the migration and invasion of HCC cells in a dose-dependent manner. It also inhibited miR-665 expression in HCC cells. We further observed that sevoflurane inhibited HCC metastasis via miR-665. Sevoflurane-induced downregulation of miRNA-665 led to phosphorylation of ERK and matrix metalloproteinase (MMP-9) via suppression of SPRED1. These results demonstrated that sevoflurane may inhibit invasion and migration via the p-ERK/MMP-9 signaling pathway in HCC cells.

Molecular Aspects of Volatile Anesthetic-Induced Organ Protection and Its Potential in Kidney Transplantation

Ischemia reperfusion injury (IRI) is inevitable in kidney transplantation and negatively impacts graft and patient outcome. Reperfusion takes place in the recipient and most of the injury following ischemia and reperfusion occurs during this reperfusion phase; therefore, the intra-operative period seems an attractive window of opportunity to modulate IRI and improve short- and potentially long-term graft outcome. Commonly used volatile anesthetics such as sevoflurane and isoflurane have been shown to interfere with many of the pathophysiological processes involved in the injurious cascade of IRI. Therefore, volatile anesthetic (VA) agents might be the preferred anesthetics used during the transplantation procedure. This review highlights the molecular and cellular protective points of engagement of VA shown in in vitro studies and in vivo animal experiments, and the potential translation of these results to the clinical setting of kidney transplantation.

Sedating Mechanically Ventilated COVID-19 Patients with Volatile Anesthetics: Insights on the Last-Minute Potential Weapons

Coronavirus Disease 2019 (COVID-19) has spread globally with the number of cases exceeding seventy million. Although trials on potential treatments of COVID-19 Acute Respiratory Distress Syndrome (ARDS) are promising, the introduction of an effective therapeutic intervention seems elusive. In this review, we explored the potential therapeutic role of volatile anesthetics during mechanical ventilation in the late stages of the disease. COVID-19 is thought to hit the human body via five major mechanisms: direct viral damage, immune overactivation, capillary thrombosis, loss of alveolar capillary membrane integrity, and decreased tissue oxygenation. The overproduction of pro-inflammatory cytokines will eventually lead to the accumulation of inflammatory cells in the lungs, which will lead to ARDS requiring mechanical ventilation. Respiratory failure resulting from ARDS is thought to be the most common cause of death in COVID-19. The literature suggests that these effects could be directly countered by using volatile anesthetics for sedation. These agents possess multiple properties that affect viral replication, immunity, and coagulation. They also have proven benefits at the molecular, cellular, and tissue levels. Based on the comprehensive understanding of the literature, short-term sedation with volatile anesthetics may be beneficial in severe stages of COVID-19 ARDS and trials to study their effects should be encouraged.

Which idea is better with regard to immune response? Opioid anesthesia or opioid free anesthesia

The stress of surgery is characterized by an inflammatory response with immune suppression resulting from many factors, including the type of surgery and the kind of anesthesia, linked with the drugs that are used and the underlying disease of the patient. The trauma of surgery triggers a cascade of reactions involving the immune response and nociception. As strong analgesics, opioids provide the analgesic component of general anesthesia with bi-directional effect on the immune system. Opioids influence almost all aspects of the immune response in regards to leukocytes, macrophages, mast cells, lymphocytes, and NK cells. The suppressive effect of opioids on the immune system is limiting their use, especially in patients with impaired immune response, so the possibility of using multimodal anesthesia without opioids, known as opioid-free anesthesia (OFA), is gaining more and more sympathizers. The idea of OFA is to eliminate opioid analgesia in the treatment of acute pain and to replace it with drugs from other groups that are assumed to have a comparable analgesic effect without affecting the immune system. Here, we present a review on the impact of anesthesia, with and without the use of opioids, on the immune response to surgical stress.

Nonexperimental Xenobiotics: Unintended Consequences of Intentionally Administered Substances in Terrestrial Animal Models

Review of the use of nonexperimental xenobiotics in terrestrial animal models and the potential unintended consequences of these compounds, including drug-related side effects and adverse reactions.

Sevoflurane Prevents Airway Remodeling via Downregulation of VEGF and TGF-β1 in Mice with OVA-Induced Chronic Airway Inflammation

Asthma is characterized by chronic airway inflammation, which is the underlying cause of airway remodeling featured by goblet cell hyperplasia, subepithelial fibrosis, and proliferation of smooth muscle. Sevoflurane has been used to treat life-threatening asthma and our previous study shows that sevoflurane inhibits acute lung inflammation in ovalbumin (OVA)-induced allergic mice. However, the effect of sevoflurane on airway remodeling in the context of chronic airway inflammation and the underlying mechanism are still unknown. Here, female C57BL/6 mice were used to establish chronic airway inflammation model. Hematoxylin and eosin (H&E), periodic acid-Schiff (PAS), and Sirius red (SR) staining were used to evaluate airway remodeling. Protein levels of α-SMA, VEGF, and TGF-β1 in lung tissues were detected by western blotting analyses and immunohistochemistry staining. Results showed that inhalation of sevoflurane inhibited chronic airway inflammation including inflammatory cell infiltration and pro-inflammatory cytokine production in BALF of the OVA-challenged mice. Meanwhile, sevoflurane suppressed airway thickening, goblet cell hyperplasia, smooth muscle hyperplasia, collagen deposition, and fiber hyperplasia in the lung tissues of the mice with airway remodeling. Most notably, sevoflurane inhibited the OVA-induced expressions of VEGF and TGF-β1. These results suggested that sevoflurane effectively inhibits airway remodeling in mouse model of chronic airway inflammation, which may be due to the downregulation of VEGF and TGF-β1in lung tissues. Therefore, our results indicate a potential role of sevoflurane in inhibiting airway remodeling besides its known suppression effect on airway inflammation, and support the use of sevoflurane in treating severe asthma in ICU.

Evaluation of Sevoflurane Anesthesia in Donkeys (Equus asinus) Premedicated With Xylazine and Induced With Thiopental

Sevoflurane is a volatile anesthetic agent that has become popular in the field of large animal anesthesia. The aim of this study was to evaluate the use of sevoflurane in adult healthy donkeys. Six male, adult, healthy donkeys were premedicated with xylazine (1 mg/kg IV), induced with thiopental (5 mg/kg IV), and then maintained for 90 minutes with sevoflurane in 100% oxygen at a flow rate of 6 L/min with spontaneous breathing. Rectal temperature (RT), respiratory rate, heart rate (HR), oxygen hemoglobin saturation (OHS), and mean arterial blood pressure (MBP) were measured before and 20 minutes after the administration of xylazine, 10 minutes after the injection of thiopental, and then continuously every 10 minutes until recovery. Times for various signs of recovery, total duration of recovery, and quality of recovery were recorded. Jugular blood samples were collected from each donkey and complete blood counts and venous blood gases including concentrations of oxygen (PO₂) and carbon dioxide (PCO₂) were measured. In addition, the concentrations of sodium, potassium, calcium, lactate, bicarbonate, and glucose in venous blood were measured. Results showed that during the anesthesia maintained with sevoflurane, there was a significant decrease in HR, MBP, RT, red blood corpuscles, hematocrit, total white blood cells, neutrophils, and lymphocytes, whereas the levels of OHS and glucose significantly increased. The concentrations of PO₂, PCO₂, and lactate in venous blood significantly increased, whereas the pH significantly decreased. The levels of calcium significantly decreased immediately following the recovery. Sternal recumbency and standing occurred 15.8 ± 2.6 minutes and 28.2 ± 2.2 minutes, respectively, after turning off the vaporizer. Overall, the quality of recovery was good and relatively quick. It was concluded that sevoflurane appears to provide safe and effective anesthesia in donkeys, with relatively rapid induction and recovery.

Decreased Protein Quality Control Promotes the Cognitive Dysfunction Associated With Aging and Environmental Insults

Background: Most neurodegenerative diseases are sporadic and develop with age. Degenerative neural tissues often contain intra- and extracellular protein aggregates, suggesting that the proteostasis network that combats protein misfolding could be dysfunctional in the setting of neurodegenerative disease. Binding immunoglobulin protein (BiP) is an endoplasmic reticulum (ER) chaperone that is crucial for protein folding and modulating the adaptive response in early secretory pathways. The interaction between BiP and unfolded proteins is mediated by the substrate-binding domain and nucleotide-binding domain with ATPase activity. The interaction facilitates protein folding and maturation. BiP has a recovery motif at the carboxyl terminus. The aim of this study is to examine cognitive function in model mice with an impaired proteostasis network by expressing a mutant form of BiP lacking the recovery motif. We also investigated if impairments of cognitive function were exacerbated by exposure to environmental insults, such as inhaled anesthetics.

Methods: We examined cognitive function by performing radial maze testing with mutant BiP mice and assessed the additional impact of general anesthesia in the context of proteostasis dysfunction. Testing over 8 days was performed 10 weeks, 6 months, and 1 year after birth.

Results: Age-related cognitive decline occurred in both forms of mice. The mutant BiP and anesthetic exposure promoted cognitive dysfunction prior to the senile period. After senescence, when mice were tested at 6 months of age and at 1 year old, there were no significant differences between the two genotypes in terms of the radial maze testing; furthermore, there was no significant difference when tested with and without anesthetic exposure.

Conclusion: Our data suggest that aging was the predominant factor underlying the impairment of cognitive function in this study. Impairment of the proteostasis network may promote age-related neurodegeneration, and this is exacerbated by external insults.

A time course study of glucose levels and innate immune response in gilthead seabream (Sparus aurata L.) after exposure to clove oil-eugenol derived anaesthetic

Clove oil is used as an anaesthetic for many species of fish worldwide; however, relatively few studies have assessed its effects on the innate immune response on these species. The present work aimed to investigate the effects of clove oil-eugenol derived anaesthetic on some humoral and cellular immune response in gilthead seabream (Sparus aurata L.). To compare with an unexposed control group, fish were exposed to 55 ppm clove oil for 5 min, before being sampled at 1, 24 and 48 h post-exposure. Serum glucose level was also measured to obtain information on the fish physiological response after clove oil anaesthesia. One hour after exposure the haemolytic complement activity of fish was lower than in the unexposed group. By contrast, the leucocyte peroxidase activity in head-kidney was significantly stimulated 24 h after exposure to clove oil-eugenol. The rest of innate immune parameters evaluated and the glucose levels not were affected by clove oil exposure at any sampling point. Overall, the use of clove oil at 55 ppm as anaesthetic did not seem to alter the innate immune response and neither did it trigger a stress response. The use of clove oil-eugenol derived had become common practice in aquaculture, and its use with gilthead seabream can be considered safe as it does not cause immunodepression in anesthetized fish.

Organ-specific responses during brain death: increased aerobic metabolism in the liver and anaerobic metabolism with decreased perfusion in the kidneys

Hepatic and renal energy status prior to transplantation correlates with graft survival. However, effects of brain death (BD) on organ-specific energy status are largely unknown. We studied metabolism, perfusion, oxygen consumption, and mitochondrial function in the liver and kidneys following BD. BD was induced in mechanically-ventilated rats, inflating an epidurally-placed Fogarty-catheter, with sham-operated rats as controls. A 9.4T-preclinical MRI system measured hourly oxygen availability (BOLD-related R2*) and perfusion (T1-weighted). After 4 hrs, tissue was collected, mitochondria isolated and assessed with high-resolution respirometry. Quantitative proteomics, qPCR, and biochemistry was performed on stored tissue/plasma. Following BD, the liver increased glycolytic gene expression (Pfk-1) with decreased glycogen stores, while the kidneys increased anaerobic- (Ldha) and decreased gluconeogenic-related gene expression (Pck-1). Hepatic oxygen consumption increased, while renal perfusion decreased. ATP levels dropped in both organs while mitochondrial respiration and complex I/ATP synthase activity were unaffected. In conclusion, the liver responds to increased metabolic demands during BD, enhancing aerobic metabolism with functional mitochondria. The kidneys shift towards anaerobic energy production while renal perfusion decreases. Our findings highlight the need for an organ-specific approach to assess and optimise graft quality prior to transplantation, to optimise hepatic metabolic conditions and improve renal perfusion while supporting cellular detoxification.

Sevoflurane preconditioning ameliorates lipopolysaccharide-induced cognitive impairment in mice

Systemic inflammation induces brain neuronal inflammation, in turn causing acute cognitive disorders. Furthermore, neuronal inflammation is one cause of postoperative cognitive disorder (POCD) and delirium. However, no sufficiently established pharmacological treatment is available for neurocognitive inflammation. This study evaluated the possible neuroprotective effects of preconditioning with sevoflurane anesthesia on cognition and neuroinflammatory changes in an animal model of lipopolysaccharide (LPS)-induced systemic inflammation. Adult mice were randomly divided into (1) control, (2) 2% sevoflurane preconditioning for 1 h, (3) intraperitoneal 5 mg/kg LPS injection, and (4) 2% sevoflurane preconditioning for 1 h + LPS injection groups. At 24 h after 5 mg/kg LPS injection, microglial activation based on ionized calcium-binding adapter molecule 1 (Iba-1) expression in the hippocampus was determined using immunostaining and immunoblotting. IL-1β and IL-6 immunoblotting were used as inflammation markers, and β-site of amyloid precursor protein cleaving enzyme 1 (BACE1) immunoblotting was performed to evaluate amyloid β-protein (Aβ) accumulation. Long-term cognitive impairment was evaluated using fear conditioning tests. Intraperitoneal LPS increased levels of Iba-1 (150%), inflammation markers (160%), and Aβ accumulation (350%), and sevoflurane preconditioning suppressed these increases. Systemic LPS caused learning deficits. Sevoflurane also maintained long-term memory in mice receiving LPS injection. Sevoflurane preconditioning prevented long-term memory impairment in the mouse model administered systemic LPS by decreasing excessive microglial activation, inflammation, and Aβ accumulation. This study supports the hypothesis that sevoflurane preconditioning might also be beneficial for neuronal inflammation. Sevoflurane might be beneficial for reducing delirium and POCD.

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.

Neonatal Repeated Exposure to Isoflurane not Sevoflurane in Mice Reversibly Impaired Spatial Cognition at Juvenile-Age

Inhalation anesthetics facilitate surgical procedures in millions of children each year. However, animal studies demonstrate that exposure to the inhalation anesthetic isoflurane may cause neuronal cell death in developing brains. The long-term cytotoxic effects of sevoflurane, the most popular pediatric anesthetic, have not been compared with isoflurane. Thus, this study was designed to compare the effects of equipotent doses of these two anesthetics on neonatal long-term neurotoxicity. Postnatal 7-day-old (P7) C57/BL male mice were exposed to 1.5% isoflurane or 2.2% sevoflurane 2 h a day for 3 days. Non-anesthetized mice served as controls. The effects of anesthesia on learning and memory were assessed using the Morris Water Maze (MWM) at Postnatal days 30 (P30) and P60 respectively. The hippocampal content of N-methyl-D-aspartate receptor subunits (NMDA), brain-derived neurotrophic factor (BDNF), and synaptophysin (Syn) were determined by Western Blot. Neuron structure and apoptosis were assessed via Nissl and TUNEL staining, respectively. The isoflurane group exhibited cognitive impairment at P30. Repeated inhalation of isoflurane or sevoflurane caused different degrees of apoptosis and damaged hippocampal neurons in neonatal mice, particularly isoflurane. In neonatal mice, repeated exposure to isoflurane, but not sevoflurane, caused spatial cognitive impairments in juvenile mice. Our findings suggest that isoflurane induces significantly greater neurodegeneration than an equipotent minimum alveolar concentration of sevoflurane.

General anesthesia exposure in early life reduces the risk of allergic diseases: A nationwide population-based cohort study

General anesthesia (GA) has been used for second line treatment strategy for status asthmaticus in pediatric patients. The association between GA in children and risk of followed-up allergic diseases is unclear. This study aims to assess the risk of allergic diseases after GA in children.We did a nationwide retrospective cohort study by analyzing data from the National Health Insurance Research Database (NHIRD) in Taiwan. The subsequent risks for allergic diseases, including asthma (ICD-9: 493.X), allergic rhinitis (AR; ICD-9 CM code 477.X), and atopic dermatitis (AD; ICD-9-CM code 691.X), were compared between exposure to GA and none before 1 year of age throughout the follow-up period using the Cox proportional hazards model.Insurance claims data for 32,742 children younger than 1 year old from all insured children in the NHIRD. Of those, 2358 subjects were exposed to GA; 414 and 1944 children exposed to mask and intubation ventilation, respectively, served as the study cohort, whereas the remaining 30,384 children made up the comparison cohort. Children in the GA group were at a lower risk of developing asthma, AR and AD, with adjusted hazard ratios of 0.67 (0.62-0.72, 95%CI), 0.72 (0.68-0.77, 95%CI), 0.60 (0.56-0.64, 95%CI), respectively.Children who were exposed to GA in early life before 1 year of age had reduced risk of subsequently developing allergic diseases such as asthma, AD, and AR, when compared with general population.

A Fatal Case of Fulminant Hepatic Necrosis Following Sevoflurane Anesthesia

Volatile anesthetics can elevate cytosolic free Ca2+ by releasing calcium from internal calcium stores and uptaking calcium from extracellular medium. Sevoflurane is an inhaled anesthetic used worldwide. A clear understanding of the exact mechanism of hepatic injury induced by sevoflurane remains elusive. A 69-year-old man with preexisting mild renal dysfunction, having undergone sevoflurane general anesthesia twice in 2 days, developed moderate jaundice. Liver enzymes strongly increased and remained elevated until death, which occurred on the 6th day after the first surgical intervention. The microscopic liver examination revealed an extensive and confluent hepatic necrosis, characterised by a large amount of calcium deposition in hepatic cell cytoplasm. These data were confirmed by confocal laser scanning microscopy and a 3-D visualization of calcium depositions was evident in hepatocytes cytoplasm. Our findings are suggestive with the previous experimental reports that consider elevation of cytoplasmic calcium may be the basis of sevoflurane – induced hepatotoxicity.

Repeated inhalation of sevoflurane inhibits airway inflammation in an OVA-induced mouse model of allergic airway inflammation

BACKGROUND AND OBJECTIVE

Repeated inhalation of sevoflurane (SVF) can benefit asthmatic patients by bronchodilation. However, the impact of repeated inhalation of SVF on allergic airway inflammation has not been clarified. This study was aimed at investigating the effects of repeated inhalation of SVF on airway inflammation in mice.

METHODS

Female C57BL/6 mice were sensitized with ovalbumin (OVA) and treated by inhalation with SVF or vehicle daily for seven consecutive days, immediately followed by OVA challenge. Airway inflammation was evaluated by counting the numbers of different types of inflammatory infiltrates in bronchoalveolar lavage fluid (BALF), histology, cytokine measurements and mucus production in individual mice.

RESULTS

In comparison with the OVA group, repeated inhalation of SVF significantly reduced the numbers of total cells, eosinophils, lymphocytes, macrophages and neutrophils (P < 0.05 to P < 0.01), and the levels of BALF tumour necrosis factor-α and lung high-mobility group box 1 (P < 0.01), accompanied by elevated levels of BALF interleukin-10 in allergic mice (P < 0.05). Repeat inhalation of SVF decreased the levels of serum OVA-specific immunoglobulin E (IgE) and mitigated allergic airway epithelial goblet cell hyperplasia and mucus hypersecretion in allergic mice (P < 0.01).

CONCLUSIONS

Repeated inhalation of SVF inhibits allergic airway inflammation by reducing inflammatory infiltrates, improving the imbalance of cytokine responses and mitigating allergen-specific IgE responses and goblet cell hyperplasia in mice.

Comparison of effects of low-flow sevoflurane and desflurane anesthesia on neutrophil and T-cell populations

BACKGROUND

Numerous transient effects of anesthesia on postoperative immune status have been documented in the literature.

OBJECTIVE

This study was performed to test the hypothesis that the effects on neutrophil and T-cell populations differ with use of low-flow sevoflurane- and desflurane-induced anesthesia during abdominal surgery.

METHODS

Fifty adult patients (American Society of Anesthesiologists physical status I or II) aged 20 to 60 years were recruited for the study. Patients were randomly assigned to one of two study groups. Anesthesia was induced using fentanyl, propofol, and vecuronium. After intubation, patients in group 1 received sevoflurane, oxygen, and nitrous oxide at a flow rate of 6 L/min, and those in group 2 received desflurane, oxygen, and nitrous oxide at a flow rate of 6 L/min. Ten minutes after induction of anesthesia, the flow rate was decreased to 1 L/min in both groups. Total leukocyte, lymphocyte, and neutrophil counts, percentage of T helper lymphocytes (CD4), cytotoxic T lymphocytes (CD8), natural killer lymphocytes, and active T lymphocyte, CD4/CD8 ratio, and plasma cortisol values were assessed before and at 2 and 24 hours after induction of anesthesia.

RESULTS

In the desflurane group, at 2 hours after induction of anesthesia, a significant decrease was observed in the lymphocyte count, percentage of CD4 cells, and CD4/CD8 ratio, and a significant increase was noted in the neutrophil count and percentage of CD8 cells (P < 0.05). At 24 hours after induction of anesthesia, a significant increase was observed in the leukocyte and neutrophil counts, percentage of CD4 cells, and CD4/CD8 ratio (P < 0.05). There was no change in the other parameters studied. In the sevoflurane group, a significant decrease was observed in the lymphocyte count and percentage of natural killer cells. In addition, a significant increase was noted in the leukocyte and neutrophil counts at 24 hours after induction of anesthesia (P < 0.01). The increase in the neutrophil count in the desflurane group compared with that in the sevoflurane group was statistically significant (P < 0.05).

CONCLUSIONS

With use of the low-flow anesthesia technique, compared with desflurane, sevoflurane exerts minimal effects on neutrophil and T-cell populations, which supports our hypothesis.

Effects of sevoflurane postconditioning on cell death, inflammation and TLR expression in human endothelial cells exposed to LPS

Background

Sevoflurane is an anesthetic agent which also participates in protective mechanisms in sepsis, likely due to anti-inflammatory properties. A key tissue in sepsis is the endothelium, which expresses TLR2 and TLR4 receptors, known regulators of inflammatory mechanisms and potential therapeutic targets for this pathology. In this context, we explored the effect of sevoflurane postconditioning in an in vitro sepsis model.

Methods

Primary cultures of human umbilical vein endothelial cells were used for two different experiments. In the first set, cultures were placed in an airtight incubation chamber and exposed to different concentrations of sevoflurane (0,1,3 or 7% vol,) for 1 hour. In the second set, lipopolysaccharide from Escherichia coli 0111:B4 (1 μg/mL) was added to culture medium for 3 hours and cells were subsequently exposed to sevoflurane (0,1,3 or 7% vol,) for 1 hour as explained before. In both cases, cell viability was measured by MTT and Trypan blue assays, TLR2 and TLR4 expression were analyzed by flow cytometry, and TNFα and IL-6 levels were quantified in cell culture media by an immunoassay immediately after exposure, at 6 and 24 hours.

Results

Exposure to 3% sevoflurane decreased TLR2 at 24 hours and TLR4 at 6 and 24 hours (both p<0.05), whereas exposure to 7% decreased TLR4 expression at 6 hours (p<0.05). Both 3 and 7% sevoflurane decreased TNF-α and IL-6 levels at 24 hours (both p<0.05). In LPS-stimulated cultures, exposure to 3% sevoflurane was cytoprotective at 6 and 24 hours (p<0.05) compared with control, and decreased TLR2 and TLR4 expression at 24 hours (p<0.05); whereas 7% decreased TLR4 expression at 24 hours (p<0.05). Both 3% and 7% sevoflurane decreased TNF-α and IL-6 levels at 24 hours (both p<0.05).

Conclusions

Postconditioning with the halogenated anesthetic agent sevoflurane after LPS stimulation shows a cytoprotective effect in an in vitro model, decreasing cell death and reducing TLR2 and TLR4 expression as well as levels of the inflammatory mediators TNF-α and IL-6 in human endothelial cells.

Sevoflurane reduces clinical disease in a mouse model of multiple sclerosis

Background

Inhalational anesthetics have been shown to influence T cell functions both in vitro and in vivo, in many cases inducing T cell death, suggesting that exposure to these drugs could modify the course of an autoimmune disease. We tested the hypothesis that in mice immunized to develop experimental autoimmune encephalomyelitis (EAE), a well established model of multiple sclerosis (MS), treatment with the commonly used inhalational anesthetic sevoflurane would attenuate disease symptoms.

Methods

C57Bl6 female mice were immunized with myelin oligodendrocyte glycoprotein (MOG) peptide residues 35 to 55 to induce a chronic demyelinating disease. At day 10 after immunization, the mice were subjected to 2 h of 2.5% sevoflurane in 100% oxygen, or 100% oxygen, alone. Following treatment, clinical scores were monitored up to 4 weeks, after which brain histology was performed to measure the effects on astrocyte activation and lymphocyte infiltration. Effects of sevoflurane on T cell activation were studied using splenic T cells isolated from MOG peptide-immunized mice, restimulated ex vivo with MOG peptide or with antibodies to CD3 and CD28, and in the presence of different concentrations of sevoflurane. T cell responses were assessed 1 day later by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay for proliferation, lactate dehydrogenase (LDH) release for cell death, and inflammatory activation by production of interleukin (IL)-17 and interferon (IFN)γ.

Results

Clinical scores in the oxygen-treated group increased until day 28 at which time they showed moderate to severe disease (average clinical score of 2.9). In contrast, disease progression in the sevoflurane-treated group increased to 2.1 at day 25, after which it remained unchanged until the end of the study. Immunohistochemical analysis revealed reduced numbers of infiltrating leukocytes and CD4⁺ cells in the CNS of the sevoflurane-treated mice, as well as reduced glial cell activation. In splenic T cells, low doses of sevoflurane reduced IFNγ production, cell proliferation, and increased LDH release.

Conclusions

These results are the first to show attenuation of EAE disease by an inhaled anesthetic and are consistent with previous reports that inhaled anesthetics, including sevoflurane, can suppress T cell activation that, in the context of autoimmune diseases such as MS, could lead to reduced clinical progression.

Effects of helium and air inhalation on the innate and early adaptive immune system in healthy volunteers ex vivo

BACKGROUND

Helium inhalation protects myocardium, brain and endothelium against ischemia/reperfusion injury in animals and humans, when applied according to specific "conditioning" protocols. Before widespread use of this "conditioning" agent in clinical practice, negative side effects have to be ruled out. We investigated the effect of prolonged helium inhalation on the responsiveness of the human immune response in whole blood ex vivo.

METHODS

Male healthy volunteers inhaled 30 minutes heliox (79%He/21%O(2)) or air in a cross over design, with two weeks between measurements. Blood was withdrawn at T0 (baseline), T1 (25 min inhalation) and T2-T5 (1, 2, 6, 24 h after inhalation) and incubated with lipopolysaccharide (LPS), lipoteichoic acid (LTA), T-cell stimuli anti-CD3/ anti-CD28 (TCS) or RPMI (as control) for 2, 4 and 24 hours or not incubated (0 h). An additional group of six volunteers inhaled 60 minutes of heliox or air, followed by blood incubation with LPS and RPMI. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), interferon-γ (IFN-γ) and interleukin-2 (IL-2) was analyzed by cytometric bead array. Statistical analysis was performed by the Wilcoxon test for matched samples.

RESULTS

Incubation with LPS, LTA or TCS significantly increased TNF-α, IL-1β, IL-6, IL-8, IFN-γ and IL-2 in comparison to incubation with RPMI alone. Thirty min of helium inhalation did not influence the amounts of TNF-α, IL-1β, IL-6, IL-8, IFN-γ and IL-2 in comparison to air. Sixty min of helium inhalation did not affect cytokine production after LPS stimulation.

CONCLUSIONS

We conclude that 79% helium inhalation does not affect the responsiveness of the human immune system in healthy volunteers.

TRIAL REGISTRATION

Dutch Trial Register: http://www.trialregister.nl/ NTR2152.

Blunt chest trauma induces mediator-dependent monocyte migration to the lung

OBJECTIVE

This study was designed to determine whether lung contusion induces an increased pulmonary recruitment of monocytes as a source of alveolar macrophages and which mediators are involved.

SETTING AND DESIGN

Prospective animal study.

SUBJECTS AND INTERVENTIONS

Male Sprague-Dawley rats were subjected to chest trauma by a single blast wave.

MEASUREMENTS

Chemokine concentrations in bronchoalveolar lavage fluids and supernatants of alveolar macrophages, chemokine and chemokine receptor mRNA expressions in monocytes, pulmonary interstitial macrophages, and alveolar macrophages isolated after trauma or sham procedure were evaluated. Immigration of monocytes was determined by staining alveolar macrophages with the fluorescent marker PKH26 before chest trauma. Chemotaxis of naïve monocytes in response to bronchoalveolar lavage or supernatants from alveolar macrophages isolated after trauma or sham procedure and the migratory response of monocytes isolated after trauma/sham to recombinant chemokines were measured.

MAIN RESULTS

Chemokine levels in bronchoalveolar lavage and alveolar macrophage supernatants and the percentage of monocytes migrated to the lungs were increased after chest trauma. Lung contusion enhanced the mRNA expression for CCR2 in monocytes and interstitial macrophages and for monocyte chemotactic protein-1 in alveolar macrophages. Migration of naïve monocytes vs. bronchoalveolar lavage or alveolar macrophage supernatants from traumatized animals was increased when compared with samples from shams. Monocytes isolated 2 hrs after trauma showed a reduced migration to CINC-1 or monocyte chemotactic protein-1 compared with sham.

CONCLUSIONS

Alveolar macrophages seem to contribute to increased chemokine concentrations in alveoli of animals subjected to blunt chest trauma. Mediators released by alveolar macrophage are potent stimuli for monocyte migration. Monocytes alter their chemokine receptor expression and are recruited to the lungs.

Isoflurane causes greater neurodegeneration than an equivalent exposure of sevoflurane in the developing brain of neonatal mice

BACKGROUND

We hypothesized that isoflurane has a greater potency to induce neurodegeneration than sevoflurane in the developing brains of neonatal mice based on our previous studies in cell culture.

METHODS

We treated 7-day-old mice with either 0.75% isoflurane or 1.1% sevoflurane ( approximately 0.5 minimum alveolar concentration) for 6 h and then obtained blood and brain samples at 2 h after the anesthesia treatment for determination of neuroapoptosis in different brain regions and the neurodegenerative biomarker S100beta in the blood. The mechanisms of neurodegeneration induced by isoflurane or sevoflurane were also compared by determining protein expressions of the cell cycle and apoptosis-related proteins. In separate groups, memory and learning ability were evaluated through the use of Morris Water Maze testing in mice at postnatal day 42 after anesthesia treatment at postnatal day 7.

RESULTS

Isoflurane but not sevoflurane significantly increased the neurodegenerative biomarker S100beta in the blood. Isoflurane treatments significantly increased apoptosis indicated by the activation of caspase-3 and elevation of poly-(ADP-ribose) polymerase in different brain regions. An equipotent exposure of sevoflurane tended to increase apoptosis in hippocampal and cortex areas but was significantly less potent than isoflurane. Neither isoflurane nor sevoflurane significantly changed protein levels of glyceraldehyde-3-phosphate dehydrogenase, beta-site amyloid beta-precursor protein-cleaving enzyme, and cell cycle regulatory proteins (CDK4, cyclin D1). Isoflurane and sevoflurane at the selected exposures did not significantly alter memory and learning ability.

CONCLUSION

At equipotent exposures, isoflurane has a greater potency than sevoflurane to cause neurodegeneration in the developing brains of neonatal mice.

Object memory in young and aged mice after sevoflurane anaesthesia

Learning and memory are cognitive functions commonly impaired after surgery, especially in elderly patients. Our aim was to evaluate the effect of sevoflurane anaesthesia on episodic-like memory in young and aged wild-type mice and mice with altered nicotinic cholinergic neurotransmission (beta2KO). Mice learned objects before randomization to control, anaesthesia or sham groups. Anaesthesia was maintained at 2.6% sevoflurane for 2 h, starting immediately after training. Object memory testing was performed after 24 h, when one familiar object was replaced by a nonfamiliar object. While nonanaesthetized mice showed memory retention of the familiar object, anaesthetized wild-type and beta2KO mice showed impaired memory. Sevoflurane anaesthesia thus causes memory impairment in mice regardless of beta2 receptor-mediated nicotinic cholinergic neurotransmission.

Fatal subacute liver failure after repeated administration of sevoflurane anaesthesia

Sevoflurane is a widely used halogenated inhalation anaesthetic. In comparison with other similar anaesthetics, it is not metabolized to potentially hepatotoxic trifluoroacetylated proteins. In this case report, we present a 66-year-old woman with breast carcinoma, who underwent sevoflurane general anaesthesia twice in 25 days. Soon after the second elective surgical procedure, jaundice and marked elevations in serum transaminases developed. The patient died 66 days thereafter. Autopsy results denied evidence of major cardiovascular abnormality, and histological examination confirmed massive liver cell necrosis with no feature of chronic liver injury. Sevoflurane anaesthesia was imputed as the cause after exclusion of other possible aetiological agents. Besides, coexistent malignant tumours found in the patient could have modulated the immunological response to the applied anaesthetic followed by fatal consequences.

Effects of sevoflurane on wound healing process

BACKGROUND

Wound healing process is a tissue response to trauma which leads to tissue repair through complex biological stages. Sevoflurane is a widely used inhalation anesthetic for surgery, but there has been no study about its effect on wound healing process. This study was undertaken to evaluate the effect of sevoflurane on wound healing process.

METHODS

Male Sprague-Dawley rats (200-300 g) were used. Two circular full-thickness skin defects of 8 mm in diameter were made on dorsum of rats. After wound formation, the animals were divided into 4 groups: 1, 2, 4, 8 hr exposure to sevoflurane, respectively. Wound sizes and regional blood flow around the wounds were measured. The expression of basic fibroblast growth factor (bFGF), transforming growth factor beta1 (TGFbeta1), collagen 1, and collagen 3 mRNA were detected 7 days after wound formation by real-time reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

Wound size was significantly increased in 8 hr group at 3 and 7 days after wound formation. Regional blood flow was significantly decreased in 4 hr and 8 hr groups at 3 days after wound formation. The bFGF, collagen 1 and 3 mRNA expressions were significantly decreased in 8 hr exposure group.

CONCLUSIONS

These results suggest that sevoflurane exposure influences the regional blood flow, wound size, expression of bFGF, and production of collagen 1 and 3 during the wound healing process.

Flow cytometric analysis of canine umbilical cord blood lymphocytes

Lymphocyte subsets in canine umbilical cord blood were flow cytometrically analyzed and compared with those of the dams' peripheral blood. The proportion of CD3+ T lymphocytes, CD21+CD3- B lymphocytes, and CD3-CD21- non-T non-B lymphocytes in umbilical cord blood was 52.9%, 30.4%, and 16.7%, respectively. T lymphocyte/B lymphocyte ratio was significantly lower in the umbilical cord blood than in the dams' peripheral blood (2.1 +/- 1.4 versus 11.0 +/- 8.1, P < 0.001). In contrast, CD4+ lymphocyte/CD8+ lymphocyte ratio was significantly higher in the umbilical cord blood than in the dams' peripheral blood (7.6 +/- 2.2 versus 1.8 +/- 0.6, P<0.001). These findings clarified the phenotypic characters of canine umbilical cord blood lymphocytes.

Increased γ-Aminobutyric Acid Levels in Mouse Brain Induce Loss of Righting Reflex, but Not Immobility, in Response to Noxious Stimulation

BACKGROUND

The general anesthetic state comprises behavioral and perceptual components, including amnesia, unconsciousness, and immobility. gamma-Aminobutyric acidergic (GABAergic) inhibitory neurotransmission is an important target for anesthetic action at the in vitro cellular level. In vivo, however, the functional relevance of enhancing GABAergic neurotransmission in mediating essential components of the general anesthetic state is unknown. Gabaculine is a GABA-transaminase inhibitor that inhibits degradation of released GABA, and consequently increases endogenous GABA in the central nervous system. Here, we examined, behaviorally, the ability of increased GABA levels to produce components of the general anesthetic state.

METHODS

All drugs were administered systemically in adult male ddY mice. To assess the general anesthetic components, two end-points were used. One was loss of righting reflex (LORR; as a measure of unconsciousness); the other was loss of movement in response to tail-clamp stimulation (as a measure of immobility).

RESULTS

Gabaculine induced LORR in a dose-dependent fashion with a 50% effective dose of 100 (75-134; 95% confidence limits) mg/kg. The behavioral and microdialysis studies revealed that the endogenous GABA-induced LORR occurred in a brain concentration-dependent manner. However, even larger doses of gabaculine (285-400 mg/kg) produced no loss of tail-clamp response. In contrast, all the tested volatile anesthetics concentration-dependently abolished both righting and tail-clamp response, supporting the evidence that volatile anesthetics act on a variety of molecular targets.

CONCLUSIONS

These findings indicate that LORR is associated with enhanced GABAergic neurotransmission, but that immobility in response to noxious stimulation is not, suggesting that LORR and immobility are mediated through different neuronal pathways and/or regions in the central nervous system.

Shock and hemorrhage: an overview of animal models

Shock resulting from life-threatening blood loss (hemorrhage) remains a common complication of traumatic injury. Intensive experimental efforts are needed if we are to understand the pathological effect(s) of hemorrhagic shock, alone or in association with traumatic tissue injury, and to reverse this deleterious process in trauma patients. Here, we overview selected studies that are representative of the different hemorrhagic shock models, considering their advantages and disadvantages from a scientific and clinical perspective. Fixed-pressure versus fixed-volume versus uncontrolled hemorrhage models, with or without tissue injury, will be discussed, as well as small versus large animal models. Most of these models are nonlethal in nature, and allow the researcher to understand the changes that contribute to increased susceptibility to subsequent infection or the development of multiple organ failure. We also consider some of the confounders in these models, including anesthesia, the nature of resuscitation, and the use of anticoagulants. The selection of model must take into consideration not only the need for experimental control but must also adequately reflect the clinical pathobiology of shock if we are to develop better pharmacological interventions.

Cardiopulmonary, histological, and inflammatory alterations after lung contusion in a novel mouse model of blunt chest trauma

Severe blunt chest trauma remains an important injury with high morbidity and mortality. However, the associated immunological alterations are poorly understood. Existing big animal models require large-scale settings, are often too expensive, and research products for immunological studies are limited. In this study we aimed to establish a new model of blunt, isolated and bilateral chest trauma in mice and to characterize its effects on physiological and inflammatory variables. Male C3H/HeN mice (n = 9-10/group) were anesthetized and a femoral artery was catheterized. The animals were subjected to trauma or sham procedure and monitored for 180 min. Blunt chest trauma was induced by a blast wave focused on the thorax. Trauma intensity was optimized by varying the exposure distance. Blood pressure, heart rate, respiratory rate, arterial blood gases and plasma cytokine levels were measured. Macroscopic and microscopic examinations were performed. In addition, outcome was evaluated in a 10-day survival study. Chest trauma caused a drop (P < 0.05) in blood pressure and heart rate, which partly recovered. Blood gases revealed hypoxemia and hypercarbia (P < 0.05) 180 min after trauma. There was marked damage to the lungs but none to abdominal organs. Histologically, the characteristic signs of a bilateral lung contusion with alveolar and intrabronchial hemorrhage were found. Plasma interleukin-6 and tumor necrosis factor alpha were considerably increased after 180 min. Blunt chest trauma resulted in an early mortality of 10% without subsequent death. On the basis of these findings, this novel mouse model of blunt chest trauma appears suitable for detailed studies on immunological effects of lung contusion.