Propofol increased the interleukin-6 to interleukin-10 ratio more than isoflurane after surgery in long-term alcoholic patients

Neutrophils and Anesthetic Drugs: Implications in Onco-Anesthesia

Apart from being a significant line of defense in the host defense system, neutrophils have many immunological functions. Although there are not many publications that accurately present the functions of neutrophils in relation to oncological pathology, their activity and implications have been studied a lot recently. This review aims to extensively describe neutrophils functions'; their clinical implications, especially in tumor pathology; the value of clinical markers related to neutrophils; and the implications of neutrophils in onco-anesthesia. This review also aims to describe current evidence on the influence of anesthetic drugs on neutrophils' functions and their potential influence on perioperative outcomes.

Effects of propofol on macrophage activation and function in diseases

Macrophages work with monocytes and dendritic cells to form a monocyte immune system, which constitutes a powerful cornerstone of the immune system with their powerful antigen presentation and phagocytosis. Macrophages play an essential role in infection, inflammation, tumors and other pathological conditions, but these cells also have non-immune functions, such as regulating lipid metabolism and maintaining homeostasis. Propofol is a commonly used intravenous anesthetic in the clinic. Propofol has sedative, hypnotic, anti-inflammatory and anti-oxidation effects, and it participates in the body’s immunity. The regulation of propofol on immune cells, especially macrophages, has a profound effect on the occurrence and development of human diseases. We summarized the effects of propofol on macrophage migration, recruitment, differentiation, polarization, and pyroptosis, and the regulation of these propofol-regulated macrophage functions in inflammation, infection, tumor, and organ reperfusion injury. The influence of propofol on pathology and prognosis via macrophage regulation is also discussed. A better understanding of the effects of propofol on macrophage activation and function in human diseases will provide a new strategy for the application of clinical narcotic drugs and the treatment of diseases.

Volatile anesthetics affect macrophage phagocytosis

Background

Perioperative infections, particularly surgical site infections pose significant morbidity and mortality. Phagocytosis is a critical step for microbial eradication. We examined the effect of commonly used anesthetics on macrophage phagocytosis and its mechanism.

Methods

The effect of anesthetics (isoflurane, sevoflurane, propofol) on macrophage phagocytosis was tested using RAW264.7 mouse cells, mouse peritoneal macrophages, and THP-1 human cells. Either opsonized sheep erythrocytes or fluorescent labeled Escherichia coli were used as phagocytic objects. The activation of Rap1, a critical protein in phagocytosis was assessed using the active Rap1 pull-down and detection kit. To examine anesthetic binding site(s) on Rap1, photolabeling experiments were performed using azi-isoflurane and azi-sevoflurane. The alanine scanning mutagenesis of Rap1 was performed to assess the role of anesthetic binding site in Rap1 activation and phagocytosis.

Results

Macrophage phagocytosis was significantly attenuated by the exposure of isoflurane (50% reduction by 1% isoflurane) and sevoflurane (50% reduction by 1.5% sevoflurane), but not by propofol. Photolabeling experiments showed that sevoflurane directly bound to Rap1. Mutagenesis analysis demonstrated that the sevoflurane binding site affected Rap1 activation and macrophage phagocytosis.

Conclusions

We showed that isoflurane and sevoflurane attenuated macrophage phagocytosis, but propofol did not. Our study showed for the first time that sevoflurane served as a novel small GTPase Rap1 inhibitor. The finding will further enrich our understanding of yet-to-be determined mechanism of volatile anesthetics and their off-target effects. The sevoflurane binding site was located outside the known Rap1 functional sites, indicating the discovery of a new functional site on Rap1 and this site would serve as a pocket for the development of novel Rap1 inhibitors.

Volatile Anesthetic Attenuates Phagocyte Function and Worsens Bacterial Loads in Wounds

BACKGROUND

Previously we have shown that volatile anesthetic isoflurane attenuated neutrophil recruitment and phagocytosis in mouse sepsis and skin inflammation models. The objectives of this study were to test ex vivo function of neutrophils in patients who underwent cardiac catheterization under volatile anesthesia versus intravenous anesthesia (IA), and also to assess the effect of anesthesia on surgical site infections (SSIs) using mouse model to understand the clinical relevance of anesthesia-induced immunomodulation.

METHODS

Whole blood from patients who underwent cardiac catheterization procedures either by volatile anesthesia or IA was collected and subjected to phagocytosis assay and a lipopolysaccharide-induced tumor necrosis factor-α assay. Mouse SSI with Staphylococcus aureus USA300 was created, and the effect of isoflurane and propofol exposure (short or long exposure) on bacterial loads was tested.

RESULTS

Neutrophil phagocytosis was significantly attenuated after the induction of volatile anesthesia in patients, but not by IA. Monocyte phagocytosis was not affected by the anesthesia regimen. Bacterial loads following SSIs were significantly higher in mice receiving long, but not short, isoflurane exposure. Propofol exposure did not affect bacterial loads.

DISCUSSION

Neutrophil phagocytosis can be affected by the type of anesthesia, and preclinical model of SSIs showed potential clinical relevance. The effects of anesthesia regimen on SSIs in patients needs to be studied extensively in the future.

From the Cover: Prolonged Exposure to Volatile Anesthetic Isoflurane Worsens the Outcome of Polymicrobial Abdominal Sepsis

Sepsis continues to result in high morbidity and mortality. General anesthesia is often administered to septic patients, but the impacts of general anesthesia on host defense are not well understood. General anesthesia can be given by volatile and intravenous anesthetics. Our previous in vitro study showed that volatile anesthetic isoflurane directly inhibits leukocyte function-associated antigen-1 (LFA-1) and macrophage-1 antigen (Mac-1), critical adhesion molecules on leukocytes. Thus, the role of isoflurane exposure on in vivo LFA-1 and Mac-1 function was examined using polymicrobial abdominal sepsis model in mice. As a comparison, intravenous anesthetic propofol was given to a group of mice. Wild type, LFA-1, Mac-1, and adhesion molecule-1 knockout mice were used. Following the induction of polymicrobial abdominal sepsis by cecal ligation and puncture, groups of mice were exposed to isoflurane for either 2 or 6 h, or to propofol for 6 h, and their outcomes were examined. Bacterial loads in tissues and blood, neutrophil recruitment to the peritoneal cavity and phagocytosis were studied. Six hours of isoflurane exposure worsened the outcome of abdominal sepsis (P < .0001) with higher bacterial loads in tissues, but 2 h of isoflurane or 6 h of propofol exposure did not. Isoflurane impaired neutrophil recruitment to the abdominal cavity by inhibiting LFA-1 function. Isoflurane also impaired bacterial phagocytosis via complement receptors including Mac-1. In conclusion, prolonged isoflurane exposure worsened the outcome of experimental polymicrobial abdominal sepsis and was associated with impaired neutrophil recruitment and bacterial phagocytosis via reduced LFA-1 and Mac-1 function.

Mechanisms of the Immunological Effects of Volatile Anesthetics: A Review

Volatile anesthetics (VAs) have been in clinical use for a very long time. Their mechanism of action is yet to be fully delineated, but multiple ion channels have been reported as targets for VAs (canonical VA targets). It is increasingly recognized that VAs also manifest effects outside the central nervous system, including on immune cells. However, the literature related to how VAs affect the behavior of immune cells is very limited, but it is of interest that some canonical VA targets are reportedly expressed in immune cells. Here, we review the current literature and describe canonical VA targets expressed in leukocytes and their known roles. In addition, we introduce adhesion molecules called β2 integrins as noncanonical VA targets in leukocytes. Finally, we propose a model for how VAs affect the function of neutrophils, macrophages, and natural killer cells via concerted effects on multiple targets as examples.

The Differential Effects of Anesthetics on Bacterial Behaviors

Volatile anesthetics have been in clinical use for a long period of time and are considered to be promiscuous by presumably interacting with several ion channels in the central nervous system to produce anesthesia. Because ion channels and their existing evolutionary analogues, ion transporters, are very important in various organisms, it is possible that volatile anesthetics may affect some bacteria. In this study, we hypothesized that volatile anesthetics could affect bacterial behaviors. We evaluated the impact of anesthetics on bacterial growth, motility (swimming and gliding) and biofilm formation of four common bacterial pathogens in vitro. We found that commonly used volatile anesthetics isoflurane and sevoflurane affected bacterial motility and biofilm formation without any effect on growth of the common bacterial pathogens studied here. Using available Escherichia coli gene deletion mutants of ion transporters and in silico molecular docking, we suggested that these altered behaviors might be at least partly via the interaction of volatile anesthetics with ion transporters.

Sepsis pathophysiology and anesthetic consideration

Sepsis remains to be a significant health care issue associated with high mortality and healthcare cost, despite the extensive effort to better understand the pathophysiology of the sepsis. Recently updated clinical guideline for severe sepsis and septic shock, "Surviving Sepsis Campaign 2012", emphasizes the importance of early goal-directed therapy, which can be implemented in intraoperative management of sepsis patients. Herein, we review the updates of current guideline and discuss its application to anesthesic management. Furthermore, we review the recent advance in knowledge of sepsis pathophysiology, focusing on immune modulation, which may lead to new clinical therapeutic approach to sepsis.

Propofol shares the binding site with isoflurane and sevoflurane on leukocyte function-associated antigen-1

BACKGROUND

We previously demonstrated that propofol interacted with the leukocyte adhesion molecule leukocyte function-associated antigen-1 (LFA-1) and inhibited the production of interleukin-2 via LFA-1 in a dependent manner. However, the binding site(s) of propofol on LFA-1 remains unknown.

METHODS

First, the inhibition of LFA-1's ligand binding by propofol was confirmed in an enzyme-linked immunosorbent assay (ELISA) ELISA-type assay. The binding site of propofol on LFA-1 was probed with a photolabeling experiment using a photoactivatable propofol analog called azi-propofol-m. The adducted residues of LFA-1 by this compound were determined using liquid chromatography-mass spectrometry. In addition, the binding of propofol to the ligand-binding domain of LFA-1 was examined using 1-aminoanthracene (1-AMA) displacement assay. Furthermore, the binding site(s) of 1-AMA and propofol on LFA-1 was studied using the docking program GLIDE.

RESULTS

We demonstrated that propofol impaired the binding of LFA-1 to its ligand intercellular adhesion molecule-1. The photolabeling experiment demonstrated that the adducted residues were localized in the allosteric cavity of the ligand-binding domain of LFA-1 called "lovastatin site." The shift of fluorescence spectra was observed when 1-AMA was coincubated with the low-affinity conformer of LFA-1 ligand-binding domain (wild-type [WT] αL I domain), not with the high-affinity conformer, suggesting that 1-AMA bound only to WT αL I domain. In the 1-AMA displacement assay, propofol decreased 1-AMA fluorescence signal (at 520 nm), suggesting that propofol competed with 1-AMA and bound to the WT αL I domain. The docking simulation demonstrated that both 1-AMA and propofol bound to the lovastatin site, which agreed with the photolabeling experiment.

CONCLUSIONS

We demonstrated that propofol bound to the lovastatin site in LFA-1. Previously we showed that the volatile anesthetics isoflurane and sevoflurane bound to this site. Taken together, the lovastatin site is an example of the common binding sites for anesthetics currently used clinically.

Isoflurane inhibits neutrophil recruitment in the cutaneous Arthus reaction model

PURPOSE

Neutrophil recruitment to the inflammatory sites is regulated by a variety of adhesion molecules including β2 integrins. The dependency of neutrophil recruitment on β2 integrins is variable in different tissues, but has not yet been verified in the cutaneous passive reverse Arthus reaction. We examined this question and also evaluated the impact of isoflurane on neutrophil recruitment to the skin because we previously showed in vitro that isoflurane binds and inhibits β2 integrins.

METHODS

The dependency on β2 integrins in neutrophil recruitment to the skin in the Arthus reaction was examined using αL, αM and β2 knockout mice. Then, we evaluated the effect of isoflurane on neutrophil recruitment to the skin. In addition, the effects of isoflurane on neutrophil binding to intercellular adhesion molecule-1 (ICAM-1), one of the β2 integrin ligands, were studied in vitro using cell adhesion assays.

RESULTS

Neutrophil recruitment to the skin in the Arthus reaction model was totally dependent on β2 integrins, as β2 knockout mice completely abolished it. However, the defect of only one of the β2 integrins was not sufficient to abolish neutrophil recruitment. Isoflurane reduced neutrophil recruitment to the skin by approximately 90 %. Also, isoflurane inhibited neutrophil adhesion to β2 integrin ligand ICAM-1.

CONCLUSIONS

We demonstrated that (1) neutrophil recruitment to the skin was totally dependent on β2 integrins, and (2) isoflurane significantly impaired neutrophil recruitment. Based on the previous studies on the contribution of other adhesion molecules in neutrophil recruitment, it is likely that isoflurane at least partially affects on β2 integrins in this model.

Isoflurane binds and stabilizes a closed conformation of the leukocyte function-associated antigen-1

We previously demonstrated that isoflurane targets lymphocyte function-associated antigen-1 (LFA-1), a critical adhesion molecule for leukocyte arrest. However, it remains to be determined how isoflurane interacts with the full ectodomain LFA-1 and modulates its conformation and function. Isoflurane binding sites on the full ectodomain LFA-1 were probed by photolabeling using photoactivatable isoflurane (azi-isoflurane). The adducted residues were determined by liquid chromatography/mass spectrometry analysis. Separately, docking simulations were performed to predict binding sites. Point mutations were introduced around isoflurane binding sites. The significance of isoflurane's effect was assessed in both intracellular adhesion molecule-1 (ICAM-1) binding assays and epitope mapping of activation-sensitive antibodies using flow cytometry. Two isoflurane binding sites were identified using photolabeling and were further validated by the docking simulation: one at the hydrophobic pocket in the ICAM-1 binding domain (the αI domain); the other at the βI domain. Mutagenesis of the α'1 helix showed that isoflurane binding sites at the βI domain were significantly important in modulating LFA-1 function and conformation. Epitope mapping using activation-sensitive antibodies suggested that isoflurane stabilized LFA-1 in the closed conformation. This study suggested that isoflurane binds to both the αI and βI domains allosteric to the ICAM-1 binding site, and that isoflurane binding stabilizes LFA-1 in the closed conformation.

Alcohol-use disorders in the critically ill patient

Alcohol abuse and dependence, referred to as alcohol-use disorders (AUDs), affect 76.3 million people worldwide and account for 1.8 million deaths per year. AUDs affect 18.3 million Americans (7.3% of the population), and up to 40% of hospitalized patients have AUDs. This review discusses the development and progression of critical illness in patients with AUDs. In contrast to acute intoxication, AUDs have been linked to increased severity of illness in a number of studies. In particular, surgical patients with AUDs experience higher rates of postoperative hemorrhage, cardiac complications, sepsis, and need for repeat surgery. Outcomes from trauma are worse for patients with chronic alcohol abuse, whereas burn patients who are acutely intoxicated may not have worse outcomes. AUDs are linked to not only a higher likelihood of community-acquired pneumonia and sepsis but also a higher severity of illness and higher rates of nosocomial pneumonia and sepsis. The management of sedation in patients with AUDs may be particularly challenging because of the increased need for sedatives and opioids and the difficulty in diagnosing withdrawal syndrome. The health-care provider also must be watchful for the development of dangerous agitation and violence, as these problems are not uncommonly seen in hospital ICUs. Despite studies showing that up to 40% of hospitalized patients have AUDs, relatively few guidelines exist on the specific management of the critically ill patient with AUDs. AUDs are underdiagnosed, and a first step to improving patient outcomes may lie in systematically and accurately identifying AUDs.

Sevoflurane binds and allosterically blocks integrin lymphocyte function-associated antigen-1

BACKGROUND

Volatile anesthetics have been shown to modify immune cell functions via several mechanisms, some of which have been only partially elucidated. We demonstrated that isoflurane inhibits primary leukocyte integrin lymphocyte function-associated antigen-1 (LFA-1) by binding to the allosteric cavity critical for conformational activation to its high-affinity form. It remains to be determined whether the allosteric inhibition of LFA-1 by isoflurane can be generalized to other anesthetics such as sevoflurane.

METHODS

The effects of sevoflurane on the ability of LFA-1 to bind to its counter-ligand, intercellular adhesion molecule-1, was studied in leukocytes by flow cytometry. To examine whether sevoflurane acts directly on LFA-1, we measured ligand-binding using beads coated with purified LFA-1 protein. To distinguish between competitive versus allosteric inhibition, we analyzed the effects of sevoflurane on both wild-type and mutant-locked high-affinity LFA-1. One-way analysis of variance was employed for statistical analysis of the data. Nuclear magnetic resonance spectroscopy was used to identify sevoflurane binding site(s).

RESULTS

Sevoflurane at clinically relevant concentrations inhibited the ligand-binding function of LFA-1 in leukocytes as well as in cell-free assays (P<0.05). Sevoflurane blocked wild-type but not locked high-affinity LFA-1, thereby demonstrating an allosteric mode of inhibition. Nuclear magnetic resonance spectroscopy revealed that sevoflurane bound to the allosteric cavity, to which LFA-1 allosteric antagonists and isoflurane also bind.

CONCLUSIONS

This study suggests that sevoflurane also blocks the activation-dependent conformational changes of LFA-1 to the high-affinity form. The allosteric mode of action exemplified by sevoflurane and isoflurane via LFA-1 might represent one of the underlying mechanisms of anesthetic-mediated immunomodulation.

Differential effects of propofol and isoflurane on the activation of T-helper cells in lung cancer patients

It is suggested that activation and differentiation of T-helper cells are required for peri-operative anti-tumor and anti-infection immunity. The present study aimed to evaluate whether propofol stimulates the activation and differentiation of these cells in patients undergoing pulmonary lobectomy for non-small-cell lung cancer. Thirty patients were randomly allocated to receive propofol or isoflurane throughout surgery. The CD4(+)CD28(+) percentage (p < 0.0001) and the ratio of interferon-gamma:interleukin-4 (p = 0.001) all increased with propofol but showed no change with isoflurane. In contrast, cortisol increased with isoflurane (p < 0.0001) but not with propofol over time (p = 0.06). We conclude that propofol promotes activation and differentiation of peripheral T-helper cells.

Propofol has anti-inflammatory effects on alveolar type II epithelial cells

BACKGROUND

We investigated whether lipopolysaccharide (LPS) induced inflammation in alveolar epithelial type II (ATII) cells is through cluster of differentiation 14 (CD14) and Toll-like receptor 4 (TLR4) and the effect of different dosages of propofol on the inflammation in primary cultured rat ATII cells.

METHODS

Cultured ATII cells were randomly assigned to one of the following five groups: Group C: untreated group (control) cultured in the absence of propofol and LPS; Group LPS: treated with 1 microg/ml LPS; Group P1: treated with 1 microg/ml LPS and 25 microM propofol; Group P2: treated with 1 microg/ml LPS and 50 microM propofol; Group P3: treated with 1 microg/ml LPS and 100 microM propofol. ATII cells in all groups were cultured at 37 degrees C for 3 h. CD14 and TLR4 mRNA was detected using real-time polymerase chain reaction. Western blot was used to detect CD14 and TLR4 protein expression. CD14 and TLR4 expression on the ATII cells was imaged using immunofluorescence. Tumor necrosis factor-alpha (TNF-alpha) production was determined using an ELISA kit.

RESULTS

LPS stimulation resulted in an increased CD14 and TLR4 expression and increased TNF-alpha production in ATII cells. Propofol, at concentrations > or = 50 microM, significantly (P<0.05) and dose-dependently decreased CD14 and TLR4 mRNA expression and protein expression in ATII cells. This was accompanied by a decrease in TNF-alpha production (P<0.05).

CONCLUSION

These results suggest that propofol, at clinically relevant concentrations, can reduce inflammatory responses in LPS-induced ATII cells injury through downregulation of CD14 and TLR4 expression.

Influence of vaccination and surgery on HLA-DR expression in patients with upper aerodigestive tract cancer

Major surgery is associated with an increased risk of post-operative immunosuppression and infections. We investigated the influence of influenza vaccination on cell-mediated immune responses in cancer patients undergoing either surgical or conservative therapy. Forty patients with an upper aerodigestive tract tumour were allocated to either a surgical or non-surgical treatment course. Patients within each group were randomized to the vaccination or non-vaccination group. Vaccination was performed twice before surgery or conservative treatment. Human leucocyte antigen receptor (HLA-DR) expression on monocytes was analysed by flow cytometry. In the surgical patients, HLA-DR expression on day 1 after surgery decreased in both the vaccinated and non-vaccinated groups. Vaccinated non-surgical patients showed significantly increased HLA-DR expression levels compared with the non-vaccinated patients. This pilot study demonstrated that vaccination increased monocyte HLA-DR expression in conservatively-treated cancer patients whereas surgery abrogated this response. Vaccination before surgery, therefore, might not help to maintain immune reactivity after surgery.

Serum levels of interleukin-1 receptor antagonist (IL-1ra) in thyroid cancer patients

BACKGROUND AND AIMS

There is growing evidence that cytokines and their antagonists are important in the pathogenesis of various malignancies. While there are several reports on interleukin-1 receptor antagonist (IL-1ra) gene polymorphism and tissue expression, there is only little data available on the impact of IL-1ra serum levels. Therefore, we performed a prospective study, analyzing IL-1ra in thyroid cancer patients.

MATERIALS AND METHODS

We measured preoperative IL-1ra serum levels of 52 consecutive patients with thyroid cancer, 15 with benign adenoma and 27 healthy volunteers. The final histological diagnosis revealed 21 patients with papillary and 8 patients with follicular carcinoma (FTC), while 12 cases of medullary and 11 cases of anaplastic carcinoma (ATC) were observed.

RESULTS

Compared to the control group, serum concentrations of IL-1ra were significantly higher in ATC and FTC patients. Concerning gender differences, this effect reached significance only in women with ATC and FTC. Except for the stage IV disease in ATC, there was no correlation between IL-1ra levels and International Union Against Cancer staging.

CONCLUSION

The findings of our study indicate that IL-1ra may play an important role in the development of ATC and FTC. Future efforts should focus on the possible application of IL-1ra as a biomarker for the above-mentioned thyroid malignancies.