A prospective randomized study of different height of operation table for tracheal intubation with videolaryngoscopy in ramped position.

BACKGROUND: Previous studies have reported that the ramped position provides a better laryngoscopic view, reduces tracheal intubation time, and increases the success rate of endotracheal intubation. However, the patient's head height changes while in the ramped position, which in turn changes the relative positions of the patient and intubator. Thus, making these changes may affect the efficiency of tracheal intubation; however, few studies have addressed this problem. This study analyzed intubation time and conditions during tracheal intubation using videolaryngoscope in the ramped position. METHODS: This prospective study included 144 patients who were scheduled to receive general anesthesia for surgeries involving orotracheal intubation. The participants were randomly allocated to either the nipple or umbilical group according to the table height. Mask ventilation was assessed using the Warters grading scale. Tracheal intubation was performed using a McGrath MAC laryngoscope. The total intubation time, laryngoscopy time, tube insertion time, and difficulty of intubation (IDS score) were measured. RESULTS: The umbilical group had a significantly shorter laryngoscopy time (10 ± 3 vs. 16 ± 4 s), tube insertion time (18 ± 4 vs. 24 ± 6 s), and total intubation time (28 ± 5 vs. 40 ± 7 s) compared to the nipple group. No significant difference in the difficulty of mask ventilation was observed between the two groups. The IDS score was higher in the nipple than umbilical group. CONCLUSION: The lower (umbilical) table level reduced the intubation time and difficulty of videolaryngoscopy compared to the higher (nipple) table level. TRIAL REGISTRATION: This study was registered at KCT0005987, 11/03/2021, Retrospectively registered.

Head-neck movement may predispose to the development of arytenoid dislocation in the intubated patient: a 5-year retrospective single-center study.

BACKGROUND: Arytenoid dislocation is a rare laryngeal injury that may follow endotracheal intubation. We aimed to determine the incidence and risk factors for arytenoid dislocation after surgery under general anaesthesia. METHODS: We reviewed the medical records of patients who underwent operation under general anaesthesia with endotracheal intubation from January 2014 to December 2018. Patients were divided into the non-dislocation and dislocation groups depending on the presence or absence of arytenoid dislocation. Patient, anaesthetic, and surgical factors associated with arytenoid dislocation were determined using Poisson regression analysis. RESULTS: Among the 25,538 patients enrolled, 33 (0.13%) had arytenoid dislocation, with higher incidence after anterior neck and brain surgery. Patients in the dislocation group were younger (52.6 ± 14.4 vs 58.2 ± 14.2 yrs, P = 0.025), more likely to be female (78.8 vs 56.5%, P = 0.014), and more likely to be intubated by a first-year anaesthesia resident (33.3 vs 18.5%, P = 0.048) compared to those in the non-dislocation group. Patient positions during surgery were significantly different between the groups (P = 0.000). Multivariable Poisson regression identified head-neck positioning (incidence rate ratio [IRR], 3.10; 95% confidence interval [CI], 1.50-6.25, P = 0.002), endotracheal intubation by a first-year anaesthesia resident (IRR, 2.30; 95% CI, 1.07-4.64, P = 0.024), and female (IRR, 3.05; 95% CI, 1.38-7.73, P = 0.010) as risk factors for arytenoid dislocation. CONCLUSION: This study showed that the incidence of arytenoid dislocation was 0.13%, and that head-neck positioning during surgery, less anaesthetist experience, and female were significantly associated with arytenoid dislocation in patients who underwent surgeries under general anaesthesia with endotracheal intubation.

Oral carbohydrate solution cause an inflammatory response when aspirated into the lungs in mice.

PURPOSE: Many studies have been published on the beneficial effects of oral carbohydrate solutions (OCS) administered prior to surgery. However, the risk of pulmonary aspiration cannot be excluded in all patients undergoing anesthesia. But, there are few studies on the safety of OCS at lung aspiration. METHODS: Experiments were conducted with mice (Nine- to ten-week-old male BALB/c mice weighted 23-26 g). Lung aspiration was performed by intratracheal administration of OCS and its major constituents, fructose and maltodextrin. Bronchoalveolar lavage fluid (BALF) was collected 3 and 24 h after lung aspiration. The level of Tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6) and macrophage inflammatory protein-2 (MIP-2) were measured in BALF. The total white blood cell, neutrophil counts, wet to dry ratio and histological examination were performed in BALF and lung tissue, respectively, at 24 h after aspiration. RESULTS: The OCS increased the level of TNF-α, IL-6 and MIP-2 at 3 h and the neutrophil count at 24 h in BALFs, compared to a phosphate-buffered saline (PBS) group. The increase in IL-6 level induced by OCS was maintained for 24 h. The OCS also increased the number of white blood cells and the percentage of neutrophils in BALFs. Compared to fructose, maltodextrin significantly increased the production of MIP-2 in BALFs. OCS and maltodextrin also increased neutrophil recruitment in lung tissue. CONCLUSION: Aspiration of OCS may cause inflammation of the lungs. The preoperative use of OCS may require caution under specific clinical conditions, such as patients at risk of lung aspiration.

Comparison of the effect of sevoflurane or propofol anesthesia on the regional cerebral oxygen saturation in patients undergoing carotid endarterectomy: a prospective, randomized controlled study.

BACKGROUND: The monitoring of regional cerebral oxygen saturation (SrO2) using near-infrared spectroscopy is useful method to detect cerebral ischemia during. Sevoflurane and propofol decrease cerebral metabolic rate (CMRO2) in a similar manner, but the effects on the cerebral blood flow (CBF) are different. We hypothesized that the effects of sevoflurane and propofol on SrO2 were different in patients with deficits of CBF. This study compared the effect of sevoflurane and propofol on SrO2 of patients undergoing cerebral endarterectomy (CEA). METHOD: Patients undergoing CEA were randomly assigned to the sevoflurane or propofol group (n = 74). The experiment was preceded in 2 stages based on carotid artery clamping. The first stage was from induction of anaesthesia to immediately before clamping of the carotid artery, and the second stage was until the end of the operation after clamping of the carotid artery. Oxygen saturation (SrO2, SpO2), haemodynamic variables (blood pressure, heart rate), respiratory parameters (end-tidal carbon dioxide tension, inspired oxygen tension), concentration of anesthetics, and anesthesia depth (bispectral index score) were recorded. RESULTS: During stage 1 period (before carotid artery clamping), the mean value of the relative changes in SrO2 was higher (P = 0.033) and the maximal decrease in SrO2 was lower in the sevoflurane group compared with the propofol group (P = 0.019) in the contralateral (normal) site. However, there is no difference in ipsilateral site (affected site). SrO2 decreased after carotid artery clamping and increased after declamping, but the difference was not significant between two groups. Changes in mean arterial blood pressure was lower in sevoflurane group than propofol group after the carotid artery declamping (P = 0.048). CONCLUSION: Propofol-remifentanil anesthesia was comparable with sevoflurane-remifentanil anesthesia in an aspect of preserving the SrO2 in patients undergoing carotid endarterectomy. TRIAL REGISTRATION: Clinical Trials.gov identifier: NCT02609087 , retrospectively registered on November 18, 2015.

A retrospective study of the relationship between postoperative urine output and one year transplanted kidney function.

BACKGROUND: Kidney transplantation (KT) is the most obvious method of treating a patient with end-stage renal disease. In the early stages of KT, urine production is considered a marker of successful reperfusion of the kidney after anastomosis. However, there is no clear conclusion about the relationship between initial urine output after KT and 1-year renal function. Thus, we investigated the factors that affect 1-year kidney function after KT, including urine output. METHODS: This retrospective study investigated the relationship between urine output in the 3 days after KT and transplanted kidney prognosis after 1-year. In total, 291 patients (129 living-donor and 162 deceased-donor transplant recipients) were analyzed; 24-h urine volume per body weight (in kilograms) was measured for 3 days postoperatively. The estimated glomerular filtration rate (eGFR), determined by the Modification of Diet in Renal Disease algorithm, was used as an index of renal function. Patients were grouped according to eGFR at 1-year after KT: a good residual function group, eGFR ≥60, and a poor residual function group, eGFR < 60. RESULT: Recipients' factors affecting 1-year eGFR include height (P = 0.03), weight (P = 0.00), and body mass index (P = 0.00). Donor factors affecting 1-year eGFR include age (P = 0.00) and number of human leukocyte antigen (HLA) mismatches (P = 0.00). The urine output for 3 days after KT (postoperative day 1; 2 and 3) was associated with 1-year eGFR in deceased-donor (P = 0.00; P = 0.00 and P = 0.01). And, postoperative urine output was associated with the occurrence of delayed graft function (area under curve (AUC) = 0.913; AUC = 0.984 and AUC = 0.944). CONCLUSION: Although postoperative urine output alone is not enough to predict 1-year GFR, the incidence of delayed graft function can be predicted. Also, the appropriate urine output after KT may differ depending on the type of the transplanted kidney. TRIAL REGISTRATION: Clinical Research Information Service of the Korea National Institute of Health in the Republic of Korea (KCT0003571).

Comparison of vocal cord view between neutral and sniffing position during orotracheal intubation using fiberoptic bronchoscope: a prospective, randomized cross over study.

BACKGROUND: In intubation using fiberoptic bronchoscope (FOB), partial or complete obstruction of upper airway makes the FOB insertion difficult. Thus, maneuvers to relieve such obstructions are recommended. There have been no studies to determine whether the sniffing or neutral position is superior for this purpose. Therefore, this study was performed to examine the effects of these two positions including vocal cord view. METHODS: Fifty-four patients scheduled to receive general anesthesia by orotracheal intubation were eligible for inclusion in the study with informed consent. After confirmation of proper head positioning depending on the group, the view of the vocal cord was acquired in each position. Images were reviewed using the percentage of glottic opening (POGO) score. RESULTS: A total of 106 images of vocal cords from 53 patients were obtained. The mean of difference of POGO score was 11.09, higher for the neutral position and standard deviation was 23.73 (p = 0.002). Neutral position increased POGO score in 31 patients and decreased POGO score in 13 patients compare to sniffing position (p = 0.017). There were no significant differences between the two head positions with regard to intubation time or degree of convenience during intubation. CONCLUSIONS: Neutral position improved the view of glottic opening than sniffing position during oral fiberoptic intubation. However, there was no difference in the difficulty of tube insertion between the two positions. TRIAL REGISTRATION: Clinical Trials.gov identifier: NCT02931019 , registered on October 12, 2016.

Anti-allodynic effect of intrathecal processed Aconitum jaluense is associated with the inhibition of microglial activation and P2X7 receptor expression in spinal cord.

BACKGROUND: For their analgesic and anti-arthritic effects, Aconitum species have been used in folk medicine in some East Asian countries. Although their analgesic effect is attributed to its action on voltage-dependent sodium channels, they also suppress purinergic receptor expression in dorsal root ganglion neurons in rats with neuropathic pain. In vitro study also demonstrated that the Aconitum suppresses ATP-induced P2X7 receptor (P2X7R)-mediated inflammatory responses in microglial cell lines. Herein, we examined the effect of intrathecal administration of thermally processed Aconitum jaluense (PA) on pain behavior, P2X7R expression and microglial activation in a rat spinal nerve ligation (SNL) model. METHODS: Mechanical allodynia induced by L5 SNL in Sprague-Dawley rats was measured using the von Frey test to evaluate the effect of intrathecal injection of PA. Changes in the expression of P2X7R in the spinal cord were examined using RT-PCR and Western blot analysis. In addition, the effect of intrathecal PA on microglial activation was evaluated by immunofluorescence. RESULTS: Intrathecal PA attenuated mechanical allodynia in a dose-dependent manner showing both acute and chronic effects with 65 % of the maximal possible effect. The expression and production of spinal P2X7R was increased five days after SNL, but daily intrathecal PA injection significantly inhibited the increase to the level of naïve animals. Immunofluorescence of the spinal cord revealed a significant increase in P2X7R expression and activation of microglia in the dorsal horn, which was inhibited by intrathecal PA treatment. P2X7R co-localized with microglia marker, but not neurons. CONCLUSIONS: Intrathecal PA exerts anti-allodynic effects in neuropathic pain, possibly by suppressing P2X7R production and expression as well as reducing microglial activation in the spinal cord.

Effect of curcumin (Curcuma longa extract) on LPS-induced acute lung injury is mediated by the activation of AMPK.

PURPOSE: Curcumin, a biphenolic compound extracted from turmeric (Curcuma longa), possesses potent anti-inflammatory activity. The present study investigated whether curcumin could increase 5' adenosine monophosphate-activated protein kinase (AMPK) activity in macrophages and modulate the severity of lipopolysaccharide (LPS)-induced acute lung injury. METHODS: Macrophages were treated with curcumin and then exposed (or not) to LPS. Acute lung injury was induced by intratracheal administration of LPS in BALB/c mice. RESULTS: Curcumin increased phosphorylation of AMPK and acetyl-CoA carboxylase (ACC), a downstream target of AMPK, in a time- and concentration-dependent manner. Curcumin did not increase phosphorylation of liver kinase B1, a primary kinase upstream of AMPK. STO-609, an inhibitor of calcium(2+)/calmodulin-dependent protein kinase kinase, diminished curcumin-induced AMPK phosphorylation, but transforming growth factor-beta-activated kinase 1 inhibitor did not. Curcumin also diminished the LPS-induced increase in phosphorylation of inhibitory κB-alpha and the production of tumor necrosis factor alpha (TNF-α), macrophage inflammatory protein (MIP)-2, and interleukin (IL)-6 by macrophages. Systemic administration of curcumin significantly decreased the production of TNF-α, MIP-2, and IL-6 as well as neutrophil accumulation in bronchoalveolar lavage fluid, and also decreased pulmonary myeloperoxidase levels and the wet/dry weight ratio in mice subjected to LPS treatment. CONCLUSION: These results suggest that the protective effect of curcumin on LPS-induced acute lung injury is associated with AMPK activation.

Vitronectin inhibits efferocytosis through interactions with apoptotic cells as well as with macrophages.

Effective removal of apoptotic cells, particularly apoptotic neutrophils, is essential for the successful resolution of acute inflammatory conditions. In these experiments, we found that whereas interaction between vitronectin and integrins diminished the ability of macrophages to ingest apoptotic cells, interaction between vitronectin with urokinase-type plasminogen activator receptor (uPAR) on the surface of apoptotic cells also had equally important inhibitory effects on efferocytosis. Preincubation of vitronectin with plasminogen activator inhibitor-1 eliminated its ability to inhibit phagocytosis of apoptotic cells. Similarly, incubation of apoptotic cells with soluble uPAR or Abs to uPAR significantly diminished efferocytosis. In the setting of LPS-induced ALI, enhanced efferocytosis and decreased numbers of neutrophils were found in bronchoalveolar lavage obtained from vitronectin-deficient (vtn(-/-)) mice compared with wild type (vtn(+/+)) mice. Furthermore, there was increased clearance of apoptotic vtn(-/-) as compared with vtn(+/+) neutrophils after introduction into the lungs of vtn(-/-) mice. Incubation of apoptotic vtn(-/-) neutrophils with purified vitronectin before intratracheal instillation decreased efferocytosis in vivo. These findings demonstrate that the inhibitory effects of vitronectin on efferocytosis involve interactions with both the engulfing phagocyte and the apoptotic target cell.

HMGB1 promotes neutrophil extracellular trap formation through interactions with Toll-like receptor 4.

Although neutrophil extracellular traps (NETs) form to prevent dissemination of pathogenic microorganisms, excessive release of DNA and DNA-associated proteins can also perpetuate sterile inflammation. In this study, we found that the danger-associated molecular pattern protein high-mobility group box 1 (HMGB1) can induce NET formation. NET formation was found after exposure of wild-type and receptor for advanced glycation end products-deficient neutrophil to HMGB1, whereas deficiency of Toll-like receptor (TLR)4 diminished the ability of neutrophils to produce NETs. Incubation of neutrophils with HMGB1 significantly increased the amount of DNA and histone 3 released as well as intracellular histone 3 citrullination, a signaling event that precedes chromatin decondensation. In vivo, neutrophils isolated from bronchoalveolar lavages of mice exposed to LPS and HMGB1 showed consistently greater ability to produce NETs compared with pulmonary neutrophils from mice that received LPS alone. In contrast, mice treated with LPS and neutralizing antibody to HMGB1 had decreased amounts of the inflammatory cytokines TNF-α and macrophage inflammatory protein 2, as well as of free DNA and histone 3 in bronchoalveolar lavage fluids. Airway neutrophils from LPS-exposed mice that had been treated with anti-HMGB1 antibodies showed decreased citrullination of histone 3. These results demonstrate that interactions between HMGB1 and TLR4 enhance the formation of NETs and provide a novel mechanism through which HMGB1 may contribute to the severity of neutrophil-associated inflammatory conditions.

Comparison of Postoperative Recovery between Balanced and Total Intravenous Anesthesia in Patients Undergoing Off-Pump Coronary Artery Bypass (OPCAB) Surgery: A Prospective, Single-Blind Randomized Study.

Recovery after anesthesia has a significant impact on a patient's return to daily life. This study was performed to compare the postoperative quality of recovery according to the method of anesthesia administered among patients undergoing OPCAB using the Korean version of the Quality of Recovery-40 (QoR-40K) questionnaire. This single-blind, prospective study (trial number: KCT0004726) was performed using a population of 102 patients undergoing OPCAB under general anesthesia. The patients were randomly assigned to one of two groups using a computer-generated list: a total intravenous anesthesia group (Group T) and a balanced anesthesia group (Group B). The QoR-40K score was measured preoperatively and at 24 and 48 h after extubation. There was no significant difference in the QoR-40K scores between the groups at 24 and 48 h after extubation. In addition, there were no significant differences between groups with respect to any of the five dimensions of QoR-40K at 24 and 48 h after extubation. Finally, there were no differences in the postoperative opioid consumption, time to extubation, or length of hospital stay. In this study, there was no difference in the QoR-40K score at 24 h after extubation between Groups T and B. Therefore, both methods of anesthesia are suitable for use when performing OPCAB.

Ramped versus sniffing position in the videolaryngoscopy-guided tracheal intubation of morbidly obese patients: a prospective randomized study.

BACKGROUND: Ramped positioning is recommended for intubating obese patients undergoing direct laryngoscopy. However, whether the use of the ramped position can provide any benefit in videolaryngoscopy-guided intubation remains unclear. This study assessed intubation time using videolaryngoscopy in morbidly obese patients in the ramped versus sniffing positions. METHODS: This is a prospective randomized study in patients with morbid obesity (n = 82; body mass index [BMI] ≥ 35 kg/m2). Patients were randomly allocated to either the ramped or the standard sniffing position groups. During the induction of general anesthesia, difficulty in mask ventilation was assessed using the Warters scale. Tracheal intubation was performed using a C-MAC® D-Blade videolaryngoscope, and intubation difficulty was assessed using the intubation difficulty scale (IDS). The primary endpoint was the total intubation time calculated as the sum of the laryngoscopy and tube insertion times. RESULTS: The percentage of difficult mask ventilation (Warters scale ≥ 4) was significantly lower in the ramped (n = 40) than in the sniffing group (n = 41) (2.5% vs. 34.1%, P < 0.001). The percentage of easy intubation (IDS = 0) was significantly higher in the ramped than in the sniffing group (70.0% vs. 7.3%, P < 0.001). The total intubation time was significantly shorter in the ramped than in the sniffing group (22.5 ± 6.2 vs. 40.9 ± 9.0, P < 0.001). CONCLUSIONS: Compared with the sniffing position, the ramped position reduced intubation time in morbidly obese patients and effectively facilitated both mask ventilation and tracheal intubation using videolaryngoscopy.

Comparison of the Nasal Cavity Guidance Methods' Effects during Nasotracheal Intubation Using a Preformed Nasotracheal Tube: A Prospective Randomized Controlled Trial.

Nasotracheal intubation is mainly performed to provide a safe airway during maxillofacial surgeries. Several guiding devices are suggested to facilitate nasotracheal intubation and reduce complications. We attempted to compare intubation conditions during nasotracheal intubation using a nasogastric tube and a suction catheter, which are readily available in operating rooms. In this study, 114 patients undergoing maxillofacial surgery were randomly divided into the nasogastric tube guidance group (NG group) and the suction catheter guidance group (SC group). The primary outcome was the total intubation time. Moreover, the incidence and degree of epistaxis, the position of the tube in the nasal cavity after intubation, and the number of manipulations during intubation in the nasal cavity were investigated. The insertion time from the nostril to the oral cavity and the total intubation time were significantly shorter in the SC group than in the NG group (p < 0.001). The incidence of epistaxis was lower at 35.1% in the NG group and 43.9% in the SC group than the previously reported 60-80%, but there was no statistical difference between the two groups. The use of a suction catheter aid during nasotracheal intubation can be used effectively because it shortens the intubation time and does not increase complications.

AMPK reduces macrophage endotoxin tolerance through inhibition of TGF-ß1 production and its signaling pathway.

Adenosine monophosphate-activated protein kinase (AMPK) is involved in suppression of the development of endotoxin tolerance, which is a driver of the immunosuppression induced by sepsis. However, the mechanism by which AMPK inhibits the development of endotoxin tolerance has not been clearly elucidated. Therefore, the present study was performed to investigate the mechanism by which the AMPK activator, metformin, inhibits the development of endotoxin tolerance. Lipopolysaccharide (LPS) increased the production of transforming growth factor (TGF)-ß1 in macrophages, which was inhibited by metformin and resveratrol. Knockdown of AMPKα1 inhibited the suppressive effect of metformin on LPS-induced TGF-ß1 production. TGF-ß neutralizing antibody and TGF-ß type I receptor inhibitor increased the production of TNF-α and IL-6 via LPS restimulation in tolerized macrophages. LPS increased Smad2 phosphorylation, but this was inhibited in cells treated with TGF-ß neutralizing antibody or metformin. Smad2 knockdown inhibited the development of endotoxin tolerance, as evidenced by increased TNF-α production in response to LPS restimulation in tolerized macrophages. TGF-ß1 expression was increased, and the levels of TNF-α and IL-6 production induced by LPS stimulation were decreased, in splenocytes of cecal ligation and puncture (CLP) model mice compared to sham-operated controls. However, metformin treatment suppressed the production of TGF-ß1, and enhanced the production of TNF-α and IL-6 induced by LPS stimulation in splenocytes of CLP mice. These results indicated that AMPK activation inhibits LPS-induced TGF-ß1 production and its signaling pathway, thus suppressing the development of endotoxin tolerance in macrophages.

Vitronectin inhibits neutrophil apoptosis through activation of integrin-associated signaling pathways.

Vitronectin is present in large concentrations in serum and the extracellular matrix. Although vitronectin is known to modulate neutrophil adhesion and chemotaxis, and to contribute to neutrophil-associated proinflammatory processes, a role in apoptosis has not been demonstrated. In the present studies, we found that neutrophils demonstrated more rapid progression to spontaneous or TNF-related apoptosis-inducing ligand-induced apoptosis when incubated under vitronectin-free conditions than when vitronectin was present. The ability of native vitronectin to delay neutrophil apoptosis was not recapitulated by the vitronectin somatomedin B domain. In contrast, inclusion of the cyclo[Arg-Gly-Asp-D-Phe-Val] peptide in cultures containing vitronectin resulted in enhanced neutrophil apoptosis, showing that the vitronectin RGD motif (Arg-Gly-Asp motif) was responsible for the antiapoptotic effects of vitronectin. Addition of antibodies to ß(1), ß(3), or ß(5), but not to ß(2) or ß(4) integrins, reversed the ability of vitronectin to diminish neutrophil apoptosis. The ability of vitronectin to enhance neutrophil viability was dependent on activation of phosphatidylinositol 3-kinase and extracellular signal-regulated kinase 1/2 kinases, but not on the p38 kinase. Increased numbers of apoptotic neutrophils were present in the lungs of LPS-treated transgenic vitronectin-deficient mice, as compared with control mice. These results demonstrate a novel antiapoptotic function for vitronectin.

Differential activation of RAGE by HMGB1 modulates neutrophil-associated NADPH oxidase activity and bacterial killing.

The receptor for advanced glycation end products (RAGE) plays an important role in host defense against bacterial infection. In the present experiments, we investigated the mechanisms by which RAGE contributes to the ability of neutrophils to eradicate bacteria. Wild-type (RAGE(+/+)) neutrophils demonstrated significantly greater ability to kill Escherichia coli compared with RAGE(-/-) neutrophils. After intraperitoneal injection of E. coli, increased numbers of bacteria were found in the peritoneal fluid from RAGE(-/-) as compared with RAGE(+/+) mice. Exposure of neutrophils to the protypical RAGE ligand AGE resulted in activation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and enhanced killing of E. coli, and intraperitoneal injection of AGE enhanced bacterial clearance during peritonitis. However, incubation of neutrophils with high mobility group box 1 protein (HMGB1), which also binds to RAGE, diminished E. coli-induced activation of NADPH oxidase in neutrophils and bacterial killing both in vitro and in vivo. Deletion of the COOH-terminal tail of HMGB1, a region necessary for binding to RAGE, abrogated the ability of HMGB1 to inhibit bacterial killing. Incubation of neutrophils with HMGB1 diminished bacterial or AGE-dependent activation of NADPH oxidase. The increase in phosphorylation of the p40(phox) subunit of NADPH oxidase that occurred after culture of neutrophils with E. coli was inhibited by exposure of the cells to HMGB1. These results showing that HMGB1, through RAGE-dependent mechanisms, diminishes bacterial killing by neutrophils as well as NADPH oxidase activation provide a novel mechanism by which HMGB1 can potentiate sepsis-associated organ dysfunction and mortality.

Toll-like receptor 4 engagement inhibits adenosine 5'-monophosphate-activated protein kinase activation through a high mobility group box 1 protein-dependent mechanism.

Despite the potent antiinflammatory effects of pharmacologically induced adenosine 5'-monophosphate kinase (AMPK) activation on Toll-like receptor 4 (TLR4)-induced cellular activation, there is little evidence that AMPK is activated during inflammatory conditions. In the present studies, we examined mechanisms by which TLR4 engagement may affect the ability of AMPK to become activated in neutrophils and macrophages under in vitro conditions and in the lungs during lipopolysaccharide (LPS)-induced acute lung injury. We found that incubation of neutrophils or macrophages with LPS diminished the ability of 5-aminoimidazole-4-carboxamide-1-ß-D-ribofuranoside (AICAR) or hydrogen peroxide (H(2)O(2)) to activate AMPK. Although ratios of AMP to adenosine 5'-triphosphate (ATP) were increased in LPS-treated neutrophils and in the lungs of LPS exposed mice, a condition that should result in AMPK activation, no activation of AMPK was found. Immunocytochemistry and Western blot analysis revealed that nuclear to cytosolic translocation of the proinflammatory mediator high mobility group box 1 protein (HMGB1) correlated with inhibition of AMPK activation in LPS-stimulated macrophages. Moreover, while induced overexpression of HMGB1 resulted in inhibition of AMPK activation, Small interfering RNA (siRNA)-induced knockdown of HMGB1 was associated with enhanced activation of AMPK in macrophages incubated with AICAR. Increased interaction between liver kinase B1 (LKB1), an upstream activator of AMPK, and HMGB1 was found in LPS-stimulated macrophages and in the lungs of mice exposed to LPS. These results suggest that nuclear to cytoplasmic translocation of HMGB1 in TLR4-activated cells potentiates inflammatory responses by binding to LKB1, thereby inhibiting the antiinflammatory effects of AMPK activation.

AMP-activated protein kinase enhances the phagocytic ability of macrophages and neutrophils.

Although AMPK plays well-established roles in the modulation of energy balance, recent studies have shown that AMPK activation has potent anti-inflammatory effects. In the present experiments, we examined the role of AMPK in phagocytosis. We found that ingestion of Escherichia coli or apoptotic cells by macrophages increased AMPK activity. AMPK activation increased the ability of neutrophils or macrophages to ingest bacteria (by 46 ± 7.8 or 85 ± 26%, respectively, compared to control, P<0.05) and the ability of macrophages to ingest apoptotic cells (by 21 ± 1.4%, P<0.05 compared to control). AMPK activation resulted in cytoskeletal reorganization, including enhanced formation of actin and microtubule networks. Activation of PAK1/2 and WAVE2, which are downstream effectors of Rac1, accompanied AMPK activation. AMPK activation also induced phosphorylation of CLIP-170, a protein that participates in microtubule synthesis. The increase in phagocytosis was reversible by the specific AMPK inhibitor compound C, siRNA to AMPKα1, Rac1 inhibitors, or agents that disrupt actin or microtubule networks. In vivo, AMPK activation resulted in enhanced phagocytosis of bacteria in the lungs by 75 ± 5% vs. control (P<0.05). These results demonstrate a novel function for AMPK in enhancing the phagocytic activity of neutrophils and macrophages.

Protective effect of sauchinone against regional myocardial ischemia/reperfusion injury: inhibition of p38 MAPK and JNK death signaling pathways.

Sauchinone has been known to have anti-inflammatory and antioxidant effects. We determined whether sauchinone is beneficial in regional myocardial ischemia/reperfusion (I/R) injury. Rats were subjected to 20 min occlusion of the left anterior descending coronary artery, followed by 2 hr reperfusion. Sauchinone (10 mg/kg) was administered intraperitoneally 30 min before the onset of ischemia. The infarct size was measured 2 hr after resuming the perfusion. The expression of cell death kinases (p38 and JNK) and reperfusion injury salvage kinases (phosphatidylinositol-3-OH kinases-Akt, extra-cellular signal-regulated kinases [ERK1/2])/glycogen synthase kinase (GSK)-3ß was determined 5 min after resuming the perfusion. Sauchinone significantly reduced the infarct size (29.0% ± 5.3% in the sauchinone group vs 44.4% ± 6.1% in the control, P < 0.05). Accordingly, the phosphorylation of JNK and p38 was significantly attenuated, while that of ERK1/2, Akt and GSK-3ß was not affected. It is suggested that sauchinone protects against regional myocardial I/R injury through inhibition of phosphorylation of p38 and JNK death signaling pathways.

Inhibition of neutrophil apoptosis by PAI-1.

Increased circulating and tissue levels of plasminogen activator inhibitor 1 (PAI-1) are often present in severe inflammatory states associated with neutrophil activation and accumulation and correlate with poor clinical outcome from many of these conditions. The mechanisms by which PAI-1 contributes to inflammation have not been fully delineated. In the present experiments, we found that addition of PAI-1 to neutrophil cultures diminished the rate of spontaneous and TNF-related apoptosis-inducing ligand-induced apoptotic cell death. The effects of PAI-1 on cell viability were associated with activation of antiapoptotic signaling pathways, including upregulation of PKB/Akt, Mcl-1, and Bcl-x(L). Although urokinase-plasminogen activator receptor, lipoprotein receptor-related protein, and vitronectin are primary ligands for PAI-1, these molecules were not involved in mediating its antiapoptotic properties. In contrast, blocking pertussis toxin-sensitive G protein-coupled receptors and selective inhibition of phosphatidylinositide 3-kinase reversed the ability of PAI-1 to extend neutrophil viability. The antiapoptotic effects of PAI-1 were also evident under in vivo conditions during LPS-induced acute lung injury, where enhanced apoptosis was present among neutrophils accumulating in the lungs of PAI-1(-/-) compared with PAI-1(+/+) mice. These results demonstrate a novel antiapoptotic role for PAI-1 that may contribute to its participation in neutrophil-associated inflammatory responses.