Secondary Logo

Journal Logo

Sedative Drug Modulates T-Cell and Lymphocyte Function-Associated Antigen-1 Function

Yuki, Koichi, MD*,§; Soriano, Sulpicio G., MD*,§; Shimaoka, Motomu, MD, PhD*,†,‡,§

doi: 10.1213/ANE.0b013e31820dcabb
Anesthetic Pharmacology: Research Reports
Free
SDC

BACKGROUND: Sedative drugs modify immune cell functions via several mechanisms. However, the effects of sedatives on immune function have been primarily investigated in neutrophils and macrophages, and to the lesser extent lymphocytes. Lymphocyte function-associated antigen-1 (LFA-1) is an adhesion molecule that has a central role in regulating immune function of lymphocytes including interleukin-2 (IL-2) production and lymphocyte proliferation. Previous clinical studies reported that propofol and isoflurane reduced IL-2 level in patients, but midazolam did not. We previously demonstrated that isoflurane inhibited LFA-1 binding to its counter ligand, intercellular adhesion molecule-1 (ICAM-1), which might contribute to the reduction of IL-2 levels. In the current study, we examined the effect of propofol, midazolam, and dexmedetomidine on LFA-1/ICAM-1 binding, and the subsequent biological effects.

METHODS: The effect of sedative drugs on T-cell proliferation and IL-2 production was measured by calorimetric assays on human peripheral blood mononuclear cells. Because LFA-1/ICAM-1 binding has an important role in T-cell proliferation and IL-2 production, we measured the effect of sedative drugs on ICAM-1 binding to LFA-1 protein (cell-free assay). This analysis was followed by flow cytometric analysis of LFA-1 expressing T-cell binding to ICAM-1 (cell-based assay). To determine whether the drug/LFA-1 interaction is caused by competitive or allosteric inhibition, we analyzed the sedative drug effect on wild-type and high-affinity LFA-1 and a panel of monoclonal antibodies that bind to different regions of LFA-1.

RESULTS: Propofol at 10 to 100 μM inhibited ICAM-1 binding to LFA-1 in cell-free assays and cell-based assays (P < 0.05). However, dexmedetomidine and midazolam did not affect LFA-1/ICAM-1 binding. Propofol directly inhibits LFA-1 binding to ICAM-1 by binding near the ICAM-1 contact area in a competitive manner. At clinically relevant concentrations, propofol, but not dexmedetomidine or midazolam, inhibited IL-2 production (P < 0.05). Additionally, propofol inhibited lymphocyte proliferation (P < 0.05).

CONCLUSIONS: Our study suggests that propofol competitively inhibits LFA-1 binding to ICAM-1 on T-cells and suppresses T-cell proliferation and IL-2 production, whereas dexmedetomidine and midazolam do not significantly influence these immunological assays.

Published ahead of print March 8, 2011

From the *Department of Anesthesiology, Perioperative and Pain Medicine, and Program in Cellular and Molecular Medicine, Children's Hospital Boston; Immune Disease Institute, Boston; and §Department of Anesthesia, Harvard Medical School, Boston, Massachusetts.

Supported by National Institutes of Health grants HL048675 and CA139444 (MS), Children's Hospital Endowed Chair in Pediatric Neuroanesthesia (SGS), and CHMC Anesthesia Foundation (KY and SGS).

The authors declare no conflicts of interest.

Reprints will not be available from the authors.

Address correspondence to Koichi Yuki, MD, Department of Anesthesiology, Pain and Perioperative Medicine, Children's Hospital Boston, 300 Longwood Ave., Boston, MA 02115. Address e-mail to koichi.yuki@childrens.harvard.edu.

Accepted December 22, 2010

Published ahead of print March 8, 2011

The effects of sedative drugs on inflammation have been studied in laboratory and clinical settings.1 Propofol and midazolam have shown antiinflammatory properties in a variety of experimental models.1 Perturbation of leukocyte function by sedatives may impair the ability of surgical and critically ill patients to combat infections and sepsis. Likewise, suppression of inflammatory responses to tissue injury and noxious peripheral stimulation may have some benefit.2 The effects of sedatives on immune function have been primarily investigated in neutrophils and macrophages and to a lesser extent lymphocytes. Because propofol, midazolam, and dexmedetomidine are frequently used in the perioperative and the intensive care settings, the immunomodulatory effects of these drugs need to be examined more rigorously.

Integrin lymphocyte function-associated antigen-1 (LFA-1) is a heterodimeric cell adhesion molecule consisting of noncovalently associated α- and β-subunits, ubiquitously expressed on leukocytes.3 It is required for various intercellular functions that include T-cell interactions with antigen-presenting cells, B-cells, and costimulation of T-cell responses.3 The binding of the T-cell receptor with class II major histocompatibility complex is relatively weak and less stringent,4,5 so the engagement of LFA-1 seems indispensable in the formation of stable immunological synapse and activation for CD4+ T-cells.6 The production of interleukin-2 (IL-2) is predominantly made by activated CD4+ T-cells,7 and is inhibited by anti-LFA-1 blocking antibodies. T-cell proliferation was impaired in LFA-1 knockout mice, suggesting that LFA-1 is also important in this process.8 Clinical reports suggested that isoflurane and propofol may reduce IL-2 levels,911 but midazolam has no effect on IL-2 levels.9 However, the mechanism of anesthetic (sedative)-related change in IL-2 levels is unclear.

The LFA-1 α subunit (αL) contains the inserted (I) domain, which is located at the most distal part of its extracellular structure and functions as the ligand binding domain.12,13 The binding of LFA-1 to its major ligand intercellular adhesion molecule-1 (ICAM-1) is dynamically regulated by the conformational changes of the I domain from the low-affinity to the high-affinity form, and only the latter can tightly bind to ICAM-1.1214 The conformational changes involve the structural rearrangement of the allosteric (distinct from the ligand binding site) cavity at the bottom of the I domain, to which small-molecule LFA-1 antagonists bind.15 We previously showed that isoflurane and sevoflurane inhibited the activation-dependent conversion of LFA-1 to the high-affinity conformation by binding to the allosteric cavity, suggesting one of the underlying mechanisms of anesthetic-mediated immunomodulation.1618 The inhibition of LFA-1/ICAM-1 engagement may be one of the mechanisms of IL-2 reduction under isoflurane exposure. We hypothesized that propofol inhibits LFA-1 function, causing the reduction of IL-2 production by T-cells, whereas midazolam does not.

Back to Top | Article Outline

METHODS

Cells and Reagents

Jurkat (human T lymphoma), and CHO (Chinese hamster ovarian) cell lines were from ATCC (Manassas, VA) and cultured in RPMI 1640 (Sigma, St. Louis, MO), 10% fetal bovine serum (FBS) at 37°C in 5% CO2. Whole blood from healthy human individuals was purchased from Research Blood Components, LLC (Brighton, MA). Peripheral blood mononuclear cells (PBMCs) were purified using Ficoll/Paque gradient sedimentation (Amersham Pharmacia Biotech, Piscataway, NJ) from whole blood. Monoclonal antibodies for different epitopes of LFA-1 (TS1/22, TS2/14, CBR LFA-1/9, and MEM83) were used to identify specific binding sites on I domain (Immune Disease Institute, Boston, MA).19,20 (R)-5-(4-bromobenzyl)- 3-(3,5-dichlorophenyl)-1,5-dimethylimidazolidine-2,4-dione(BIRT377) is an LFA-1 small allosteric antagonist (Immune Disease Institute).21 Lipid-free propofol, midazolam, staphylococcal enterotoxin B (SEB), phorbol 12-myristate 13-acetate (PMA), and ionomycin were from Sigma. Dexmedetomidine was from Tocris (Ellisville, MO). Propofol, midazolam, and dexmedetomidine were dissolved in dimethyl sulfoxide (DMSO).

Back to Top | Article Outline

IL-2 Production Assays

To compare the effect of propofol, midazolam, and dexmedetomidine on IL-2 production, PBMC assays with either SEB (2 μg/mL) or PMA (10 ng/mL)/ionomycin (1 μg/mL) were performed as previously described.21 SEB induces LFA-1-dependent IL-2 production, whereas PMA/ionomycin does not. Purified human PBMCs suspended in RPMI 1640 and 10% FBS were plated in a 96-well plate at 2 × 105 cells/well. Several concentrations of propofol (10–100 μM), midazolam (1–50 μM), or dexmedetomidine (1–50 μM) were tested. All experiments included mock-treated samples containing equal volumes of DMSO (0.5%). The cells were incubated at 37°C for 16 hours. IL-2 levels were measured with a human IL-2 ELISA kit (R&D Systems, Minneapolis, MN). The LFA-1 blocking antibody TS1/22 was used as a control to demonstrate the LFA-1-dependent process.

Back to Top | Article Outline

The Effect of Sedative Drugs on Binding of Soluble ICAM-1 to the Immobilized Extracellular Part of LFA-1

To examine the effect of sedative drugs on LFA-1/ICAM-1 binding, the recombinant extracellular portion of wild-type (WT) and high-affinity (HA) LFA-1 protein was expressed in CHO cells and purified to homogeneity as previously described.22 The αL I domain of HA LFA-1 protein is locked in the constitutively high-affinity conformation by an engineered disulfide bond.23 Soluble LFA-1 WT or HA (5 μg/mL) was immobilized indirectly on anti-LFA-1 capturing antibody CBR LFA1/2 (Immune Disease Institute) on ELISA plates. Nonspecific binding was blocked with HEPES-buffered saline (HBS) and 2% bovine serum albumin (Sigma). Human ICAM-1-Fcα fusion protein (5 μg/mL)22,23 was then added to wells with HBS containing 1 mM MnCl2 and propofol, midazolam, or dexmedetomidine at various concentrations. All experiments included mock-treated samples containing equal volumes of DMSO (0.5%). After incubation for 1 hour at room temperature, unbound ICAM-1 was washed off. Bound ICAM-1 was detected by peroxidase-labeled goat antihuman immunoglobulin A (IgA) (KPL, Inc., Gaithersburg, MD) and substrate (BD, Franklin Lakes, NJ). After 15 minutes, absorbance was measured at 405 nm. ICAM-1 binding percentage was defined as [(optical density (OD) at various concentrations of sedatives)/(OD of mock treated)] × 100 (%).

Back to Top | Article Outline

Binding of Soluble ICAM-1 to Jurkat Cells

ICAM-1 binding to LFA-1 on Jurkat cells was measured by flow cytometry. Briefly, Jurkat cells expressing LFA-1 were harvested and washed once with HBS containing 10 mM EDTA and 3 times with HBS, and then resuspended in HBS. Cells (5 × 105) in 300 μL HBS were aliquoted to tubes and centrifuged. Cell pellets were given a 150-μL aliquot of HBS, 2 mM MnCl2 containing propofol at 2× final concentration; and another 150-μL aliquot of HBS containing 25 μg/mL fluorescein isothiocyanate–conjugated goat antihuman IgA antibody (Pierce, Rockford, IL), and either 10 μg/mL ICAM-1-Fcα fusion protein or control human IgA. Each experiment included mock-treated samples containing equal volumes of DMSO (0.5%). Cells were incubated for 30 minutes at room temperature. Bound ICAM-1 was detected by flow cytometry (FACScan; BD Bioscience, San Jose, CA). ICAM-1 binding percentage was defined as [mean fluorescence intensity at various concentrations of propofol/mean fluorescence intensity of mock treated] × 100 (%).

Back to Top | Article Outline

Inhibition of Antibody Binding to LFA-1

Soluble LFA-1 (10 μg/mL) was immobilized directly on ELISA plates overnight at 4°C. Wells were blocked with HBS, 2% bovine serum albumin for 1 hour at room temperature. LFA-1 antibodies (final concentration, 10 μg/mL) and propofol (final concentration, 100 μM) were added and allowed to bind for 1 hour at room temperature. Both propofol-treated and mock-treated samples contained 0.5% DMSO. Unbound antibodies were washed off and bound antibodies were detected using peroxidase-labeled goat antimouse IgG (Invitrogen, Carlsbad, CA) and substrate. After 15 minutes, absorbance was measured at 405 nm. Data were presented as [OD of propofol-treated sample/OD of mock-treated sample] × 100 (%) for each antibody.

Back to Top | Article Outline

Mixed Lymphocyte Reaction Proliferation Assay

To determine the effect of sedatives on lymphocyte proliferation, human PBMCs were purified in each experiment. PBMCs 1 × 105 were used as stimulators (nondividing cells) and responders (cells with proliferative response). Stimulator cells were incubated with mitomycin C (Sigma) 25 μg/mL for 30 minutes at 37°C, and washed 3 times before suspending in RPMI 1640, 10% FBS. The cells were incubated for 5 days with various concentrations of sedatives or BIRT377 (25 μM), an LFA-1 small-molecule antagonist.21 Sedatives up to supraclinical concentrations were tested. BIRT377 served as an internal control for the inhibition of both LFA-1/ICAM-1 binding and LFA-1-mediated cell adhesion. All experiments included mock-treated samples containing equal volumes of DMSO (0.1%). Four days after incubation, bromodeoxyuridine (BrdU) (Roche, Nutley, NJ) was added to each well. Cells were incubated for another 24 hours. The effect of sedatives on PBMC proliferation was assessed by using a BrdU incorporation-based cell proliferation ELISA (Roche Applied Science, Indianapolis, IN). OD was measured at 370 nm. Stimulation index percentage was defined as [OD of sample at given dose of sedative]/[OD of mock-treated sample] × 100 (%).

Back to Top | Article Outline

Statistical Analysis

Data are presented as mean ± SE and analyzed using a Student t test (2-tailed) or analysis of variance with Tukey post hoc pairwise comparisons. Significance was set at P < 0.05. All statistical calculations were performed using Prism 5 (GraphPad Software, La Jolla, CA).

Back to Top | Article Outline

RESULTS

Propofol at a Clinically Relevant Concentration Inhibits IL-2 Production by LFA-1 in a Dose-Dependent Manner

We measured the effect of sedative drugs on LFA-1-dependent and -independent IL-2 production from T-cells. SEB crosslinks class II major histocompatibility complex with the T-cell receptor. PBMCs containing T-cells (LFA-1) and antigen-presenting cells (ICAM-1) produce IL-2 in an LFA-1-dependent manner with SEB.21 However, PBMCs produce IL-2 in an LFA-1-independent manner with PMA/ionomycin.21 The dependency of LFA-1 in each assay was confirmed with the anti-LFA-1 blocking antibody TS1/22 (Fig. 1). Propofol at 10 and 50 μM (clinically relevant concentrations2426) attenuated SEB-mediated IL-2 production but not PMA/ionomycin-elicited IL-2 production (Fig. 1). Propofol at 100 μM (supraclinical concentration) showed some LFA-1-independent IL-2 inhibition, whereas LFA-1-dependent IL-2 production was almost completely inhibited. Dexmedetomidine (clinically relevant concentration <0.01 μM27,28) and midazolam (clinically relevant concentration <5 μM29,30) at up to 50 μM did not significantly affect IL-2 production (Fig. 1).

Figure 1

Figure 1

Back to Top | Article Outline

Propofol Inhibits the Binding of LFA-1 to ICAM-1 in the Cell-Free System

To examine the effect of the 3 sedatives on extracellular LFA-1/ICAM-1 binding, we performed LFA-1 binding assays in the cell-free system. In a control experiment, BIRT377 and TS1/22 inhibited WT LFA-1/ICAM-1 binding (data not shown). Propofol inhibited ICAM-1 binding to Mn2+-stimulated WT LFA-1 (Fig. 2). Dexmedetomidine and midazolam (up to 100 μM) did not inhibit LFA-1/ICAM-1 binding (Fig. 2). The lack of effect by dexmedetomidine and midazolam on LFA-1/ICAM-1 binding may explain their lack of effect on IL-2 production.

Figure 2

Figure 2

Back to Top | Article Outline

Propofol Inhibits the Binding of LFA-1 to ICAM-1 in Cells

Because propofol was the only drug to decrease LFA-1/ICAM-1 binding, we examined its effect using human T-cell line Jurkat cells that express LFA-1 at high levels. Propofol inhibited ICAM-1 binding to LFA-1 (Fig. 3A). The suppression of ICAM-1 binding by propofol is not attributable to its effects on LFA-1 expression, because LFA-1 surface expression detected by TS1/18 was not affected (Fig. 3B).

Figure 3

Figure 3

Back to Top | Article Outline

Propofol Inhibits ICAM-1 Binding to HA LFA-1

LFA-1/ICAM-1 binding can be blocked sterically and/or allosterically.22 To understand the mechanism of inhibition, we examined the binding of ICAM-1 using HA LFA-1. Whereas WT LFA-1 was blocked by both direct and allosteric inhibitors (TS1/22 and BIRT377, respectively), HA LFA-1 mutant was blocked only by direct inhibitors (data not shown). We previously showed that isoflurane and sevoflurane inhibited ICAM-1 binding to the allosteric cavity at the bottom of the I domain.1618 Whereas volatile anesthetics inhibited ICAM-1 binding only to WT LFA-1, propofol inhibited ICAM-1 binding to both WT and HA LFA-1 (Fig. 4).

Figure 4

Figure 4

Back to Top | Article Outline

The Effect of Propofol on the Binding of Anti-αL I Domain Antibodies to LFA-1

Because propofol inhibited the interaction of ICAM-1 with WT LFA-1 and HA LFA-1 similarly, we cannot exclude the possibility that propofol binds to ICAM-1, not LFA-1. Therefore, we examined the competitive binding of anti-LFA-1 antibodies to LFA-1 against propofol. We mapped the potential propofol binding site(s) within the I domain, using a panel of 4 LFA-1 antibodies that bind to different regions of the I domain: CBR LFA1/9, TS1/22, and TS2/14 map to different regions on the top of the I domain, just outside the ICAM-1 contacting area, at which those monoclonal antibodies inhibit ICAM-1 binding sterically.31 In contrast, MEM83 maps to the side of the I domain, distant from the ICAM-1 contact area.31 Propofol reduced only TS1/22 binding (Fig. 5). This suggests that propofol binds to or near the TS1/22 epitopes. Because TS1/22 blocks LFA-1 sterically, propofol may block it in a similar manner.

Figure 5

Figure 5

Back to Top | Article Outline

Propofol Inhibits Lymphocyte Proliferation

Mixed lymphocyte reaction (MLR) is an assay to study allo-recognition and cellular immunity.32 LFA-1/ICAM-1 interaction is involved in lymphocyte proliferation in MLR, because the inhibition of LFA-1 inhibits MLR.33,34 We investigated whether sedatives would block lymphocyte proliferation using 1-way MLR with a BrdU incorporation assay. BIRT377-mediated antagonism of LFA-1 resulted in a 60% reduction in lymphocyte proliferation. Propofol, but not midazolam or dexmedetomidine, attenuated lymphocyte proliferation in a dose-dependent manner to a lesser degree (Fig. 6).

Figure 6

Figure 6

Back to Top | Article Outline

DISCUSSION

We demonstrated that propofol inhibited the LFA-1/ICAM-1 interface sterically, which may be one of the mechanisms for the observed dose-dependent suppression of T-cell proliferation and IL-2 production by propofol. Midazolam and dexmedetomidine did not alter LFA-1/ICAM-1 binding and IL-2 production.

We previously demonstrated that isoflurane and sevoflurane bind to the binding site for LFA-1 allosteric antagonists and inhibit ligand binding allosterically.1618 The ability of sedatives to bind and inhibit LFA-1 has not been previously reported. Because propofol only inhibited LFA-1-dependent IL-2 production, we hypothesized that propofol would bind and inhibit LFA-1. LFA-1 enhances the binding to ICAM-1 by (1) strengthening affinity through the conformational changes of an individual LFA-1 molecule, and/or (2) lateral clustering of multiple LFA-1 molecules.35 To study the direct action of propofol on LFA-1, we measured the effect on LFA-1/ICAM-1 binding using a cell-free assay. Propofol significantly inhibited LFA-1/ICAM-1 binding and affinity. We also examined LFA-1/ICAM-1 binding in T-cells. Inhibition of LFA-1 by propofol was more potent in a cell assay than in a cell-free system. The actin regulates LFA-1 clustering.36 Because propofol affects actin function,3739 the higher inhibition observed in the cell-based assay suggests that clustering through intracellular processes may be inhibited. However, we also observed that the decreased LFA-1/ICAM-1 binding was not attributable to changes in LFA-1 surface expression, which is in line with the report in a rodent abdominal sepsis model.40 Therefore, propofol-induced inhibition of LFA-1/ICAM-1 binding is likely due to decreased affinity and clustering of LFA-1.

Interestingly, the mode of action of propofol on LFA-1 appeared to be different from that of isoflurane. Isoflurane inhibits WT, not HA LFA-1, implying an allosteric inhibition. Propofol inhibited both WT and HA LFA-1, thereby suggesting the direct inhibition. Using a panel of 4 monoclonal antibodies mapping to different regions of the I domain, we have shown that propofol specifically inhibited the TS1/22 binding. TS1/22 maps to Gln266 and Ser270, which are located in the β5-α6 loop and α6 helix of the I domain, the region near the ICAM-1 binding site (Fig. 7).31 Given that other antibodies did not affect propofol binding, it is unlikely that propofol globally perturbs the structural integrin of the I domain by inducing protein unfolding. Our findings support a direct mode of inhibition by propofol on/near the TS1/22 epitope(s). However, this dose not exclude the possibility that propofol binds to other sites including the allosteric cavity because our monoclonal antibodies mapping does not cover the entire I domain surface.

Figure 7

Figure 7

LFA-1 binding to ICAM-1 on antigen-presenting cells upregulates IL-2 gene expression4143 through protein kinase Cδ phosphorylation and c-Jun N-terminal kinase/mitogen-activated protein kinase (MAPK) activation.44 PMA/ionomycin directly activates protein kinase Cδ, leading to the activation of MAPK.44 Because propofol suppresses MAPK activity,45 it may penetrate the cell membrane and interact with intracellular signaling molecules at 100 μM. The proposed mechanism of IL-2 reduction by propofol is illustrated in Figure 8. IL-2 supports proliferation and survival of T-cells, differentiation of naïve T-cells into effector and memory cells, secondary expansion of memory T-cells when they reencounter an antigen.7,46 IL-2 has been used as an immunotherapy to restore T-cell functions in patients with acquired immune deficiency syndrome or cancer.4749 Anesthesia induction and maintenance with propofol were associated with a decrease in plasma IL-2 level in patients undergoing cholecystectomies.10 Forty-eight hours of continuous propofol infusion to surgical patients in the intensive care unit reduced serum IL-2 levels by 70%.9 Our results suggest that propofol directly acts on T-cells to inhibit IL-2 production. The suppression of IL-2 production potentially induces iatrogenic immune defects. Propofol also inhibited lymphocyte proliferation. These effects of propofol on lymphocytes could potentially impair innate immunity, because an adaptive immune system could affect innate immunity.50,51

Figure 8

Figure 8

We examined the effect of 3 sedatives at a concentration range of 0 to 100 μM. A clinically relevant plasma concentration of propofol is 3 to 11 μg/mL (17–62 μM) for the maintenance of anesthesia,24,25 and approximately 2 μg/mL (11.3 μM) for adequate sedation in the intensive care unit.26 The concentration of propofol at 10 to 50 μM is in the clinically relevant range, supporting the relevance of our in vitro findings to clinical practice. The clinically relevant plasma concentrations for midazolam and dexmedetomidine were within the lower end of the range used in our assays, where no changes in IL-2 production and LFA-1/ICAM-1 binding were detected. Because sedatives are often administered to immunocompromised and critically ill patients, our understanding of immunomodulation by sedation will be critical. For example, secondary analysis of data from the MENDS trial revealed a mortality benefit in septic patients sedated with dexmedetomidine relative to lorazepam.52 Based on our results, propofol infusion may lead to iatrogenic T-cell dysfunction. Because lipid emulsion itself can decrease lymphocyte proliferation,53 propofol emulsion infusion may be harmful to patients with impaired T-cell function. Its clinical significance remains to be determined. However, midazolam and dexmedetomidine may be preferable for this patient population.

In this study, we only examined the effect of sedatives on LFA-1/ICAM-1 binding. We did not examine the effects on downstream intracellular signaling. Direct interaction of sedatives on intracellular proteins could also attenuate LFA-1 activation. Further investigations into the effect of these sedative drugs on intracellular signaling and protein interactions are needed.

We demonstrated that propofol interacts with LFA-1 by inhibiting LFA-1/ICAM-1 binding, lymphocyte proliferation, and IL-2 production. Midazolam and dexmedetomidine do not significantly affect these in vitro assays. The competitive mode of propofol-induced inhibition of LFA-1 represents one of the underlying mechanisms of sedation-mediated immunomodulation.

Back to Top | Article Outline

DISCLOSURES

Name: Koichi Yuki, MD.

Contribution: Study design, conduct of study, data analysis, and manuscript preparation.

Name: Sulpicio G. Soriano, MD.

Contribution: Study design, data analysis, and manuscript preparation.

Name: Motomu Shimaoka, MD, PhD.

Contribution: Study design, data analysis, and manuscript preparation.

Back to Top | Article Outline

REFERENCES

1. Sanders RD, Hussell T, Maze M. Sedation & immunomodulation. Crit Care Clin 2009;25:551–70
2. Thacker MA, Clark AK, Marchand F, McMahon SB. Pathophysiology of peripheral neuropathic pain: immune cells and molecules. Anesth Analg 2007;105:838–47
3. Abram CL, Lowell CA. The ins and outs of leukocyte integrin signaling. Annu Rev Immunol 2009;27:339–62
4. Demotz S, Grey HM, Sette A. The minimal number of class II MHC-antigen complexes needed for T cell activation. Science 1990;249:1028–30
5. Harding CV, Unanue ER. Quantitation of antigen-presenting cell MHC class II/peptide complexes necessary for T-cell stimulation. Nature 1990;346:574–6
6. Wang Y, Li D, Nurieva R, Yang J, Sen M, Carreno R, Lu S, Mcintyre BW, Molldrem JJ, Legge GB, Ma Q. LFA-1 affinity regulation is necessary for the activation and proliferation of naïve T cells. J Biol Chem 2009;284:12645–53
7. Bachmann MF, Oxenius A. Interleukin 2: from immunostimulation to immunoregulation and back again. EMBO Rep 2007;8:1142–8
8. Ding ZM, Babensee JE, Simon SI, Lu H, Perrard JL, Bullard DC, Dai XY, Bromley SK, Dustin ML, Entman ML, Smith CW, Ballantyne CM. Relative contribution of LFA-1 and Mac-1 to neutrophil adhesion and migration. J Immunol 1999;163:5029–38
9. Helmy SA, Al-Attiyah RJ. The immunomodulatory effects of prolonged intravenous infusion of propofol versus midazolam in critically ill surgical patients. Anaesthesia 2001;56:4–8
10. Helmy SA, Wahby MA, El-Nawaway M. The effect of anaesthesia and surgery on plasma cytokine production. Anaesthesia 1999;54:733–8
11. Helmy SA, Al-Attiyah RJ. The effect of halothane and isoflurane on plasma cytokine levels. Anaesthesia 2000;55:904–10
12. Shimaoka M, Takagi J, Springer TA. Conformational regulation of integrin structure and function. Annu Rev Biophys Struct 2002;31:485–516
13. Shimaoka M, Springer TA. Therapeutic antagonists and conformational regulation of integrin function. Nat Rev Drug Discov 2003;2:703–16
14. Springer TA, Wang JH. The three-dimensional structure of integrins and their ligands, and conformational regulation of cell adhesion. Adv Protein Chem 2004;68:29–63
15. Kallen J, Welzenbach K, Ramage P, Geyl D, Kriwacki R, Legge G, Cottens S, Weitz-Schmidt G, Hommel U. Structural basis for LFA-1 inhibition upon lovastatin binding to the CD11a I-domain. J Mol Biol 1999;292:1–9
16. Yuki K, Astrof NS, Bracken C, Yoo R, Silkworth W, Soriano SG, Shimaoka M. The volatile anesthetic isoflurane perturbs conformational activation of integrin LFA-1 by binding to the allosteric regulatory cavity. FASEB J 2008;22:4109–16
17. Zhang H, Astrof NS, Liu JH, Wang JH, Shimaoka M. Crystal structure of isoflurane bound to integrin LFA-1 supports a unified mechanism of volatile anesthetic action in the immune and central nervous systems. FASEB J 2009;23:2735–40
18. Yuki K, Astrof NS, Bracken C, Soriano SG, Shimaoka M. Sevoflurane binds and allosterically blocks integrin lymphocyte function-associated antigen-1. Anesthesiology 2010;113: 600–9
19. Sanchez-Madrid F, Krensky AM, Ware CF, Robbins E, Strominger JL, Burakoff SJ, Springer TA. Three distinct antigens associated with human T lymphocyte-mediated cytolysis: LFA-1, LFA-2, and LFA-3. Proc Natl Acad Sci USA 1982;79: 7489–93
20. Petruzzelli L, Maduzia L, Springer TA. Activation of lymphocyte function-associated molecule-1 (CD11a/CD18) and Mac-1 (CD11b/CD18) mimicked by an antibody directed against CD18. J Immunol 1995;155:854–66
21. Kelly TA, Jeanfavre DD, McNeil DW, Woska JR Jr, Reilly PL, Mainolfi EA, Kishimoto KM, Nabozny GH, Zinter R, Bormann BJ, Rothlein R. Cutting edge: a small molecule antagonist of LFA-1-mediated cell adhesion. J Immunol 1999;163:5173–7
22. Shimaoka M, Salas A, Yang W, Weiz-Schmidt G, Springer TA. Small molecule integrin antagonists that bind to the β2 subunit I-like domain and activate signals in one direction and block them in another. Immunity 2003;19:391–402
23. Lu C, Shimaoka M, Ferzly M, Oxvig C, Takagi J, Springer TA. An isolated, surface-expressed I domain of the integrin aLb2 is sufficient for strong adhesive function when locked in the open conformation with a disulfide. Proc Natl Acad Sci USA 2001;98:2387–92
24. Short TG, Aun CS, Tan P, Wong J, Tam YH, Oh TE. A prospective evaluation of pharmacokinetic model controlled infusion of propofol in paediatric patients. Br J Anaesth 1994;72:302–6
25. Gepts E, Camu F, Cockshott ID, Douglas EJ. Disposition of propofol administered as constant rate intravenous infusions in humans. Anesth Analg 1987;66:1256–63
26. Albanese J, Martin C, Lacarelle B, Saux P, Durand A, Gouin F. Pharmacokinetics of long-term propofol infusion used for sedation in ICU patients. Anesthesiology 1990;73:214–7
27. Kishikawa H, Kobayashi K, Takemori K, Okabe T, Ito K, Sakamoto A. The effects of dexmedetomidine on human neutrophil apoptosis. Biomed Res 2008;29:189–94
28. Nishina K, Akamatsu H, Mikawa K, Shiga M, Maekawa N, Obara H, Niwa Y. The effects of clonidine and dexmedetomidine on human neutrophil functions. Anesth Analg 1999; 88:452–8
29. Nishina K, Akamatsu H, Mikawa K, Shiga M, Maekawa N, Obara H, Niwa Y. The inhibitory effects of thiopental, midazolam, and ketamine on human neutrophil functions. Anesth Analg 1998;86:159–65
30. Ho CM, Tarng GW, Su CK. Comparison of effects of propofol and midazolam at sedative concentrations on sympathetic tone generation in the isolated spinal cord of neonatal rats. Acta Anaesthesiol Scand 2007;51:708–13
31. Lu C, Shimaoka M, Salas A, Springer TA. The binding sites for competitive antagonistic, allosteric antagonistic, and agonistic antibodies to the I domain of integrin LFA-1. J Immunol 2004;173:3972–8
32. Bishara A, Malka R, Brautbar C, Barak V, Cohen I, Kedar E. Cytokine production in human mixed leukocyte reactions performed in serum-free media. J Immunol Methods 1998;215:187–90
33. McCabe SM, Riddle L, Nakamura GR, Prashad H, Mehta A, Berman PW, Jardieu P. sICAM-1 enhances cytokine production stimulated by alloantigen. Cell Immunol 1993;150: 364–75
34. Gadek TR, Burdick DJ, McDowell RS, Stanley MS, Marsters JC Jr, Paris KJ, Oare DA, Reynolds ME, Ladner C, Zioncheck KA, Lee WP, Gribling P, Dennis MS, Skelton NJ, Tumas DB, Clark KR, Keating SM, Beresini MH, Tilley JW, Presta LG, Bodary SC. Generation of an LFA-1 antagonist by the transfer of the ICAM-1 immunoregulatory epitope to a small molecule. Science 2002;295:1086–9
35. Kinashi T. Intracellular signaling controlling integrin activation in lymphocytes. Nat Rev Immunol 2005;5:546–59
36. van Kooyk Y, van Vliet SJ, Figdor CG. The actin cytoskeleton regulates LFA-1 ligand binding through avidity rather than affinity changes. J Biol Chem 1999;274:26869–77
37. Oscarsson A, Massoumi R, Sjolander A, Eintrei C. Reorganization of actin in neurons after propofol exposure. Acta Anaesthesiol Scand 2001;45:1215–20
38. Garib V, Lang K, Niggemann B, Zanker KS, Brandt L, Dittmar T. Propofol-induced calcium signaling and actin reorganization within breast carcinoma cells. Eur J Anaesthesiol 2005;22:609–15
39. Mammoto T, Mukai M, Mammoto A, Yamanaka Y, Hayashi Y, Mashimo T, Kishi Y, Nakamura H. Intravenous anesthetic, propofol inhibits invasion of cancer cells. Cancer Lett 2002;184:165–70
40. Inada T, Taniuchi S, Shingu K, Kobayasgi Y, Fujisawa J, Nakao S. Propofol depressed neutrophil hydrogen peroxide production more than midazolam, whereas adhesion molecule expression was minimally affected by both anesthetics in rats with abdominal sepsis. Anesth Analg 2001;92:437–41
41. Abraham C, Miller J. Molecular mechanisms of IL-2 gene regulation following costimulation through LFA-1. J Immunol 2001;167:193–201
42. Van Seventer GA, Shimizu Y, Horgan KJ, Horgan KJ, Shaw S. The LFA-1 ligand ICAM-1 provides an important costimulatory signal for T cell receptor-mediated activation of resting T cells. J Immunol 1990;144:4579–86
43. Shimizu Y. LFA-1: more than just T cell velcro. Nat Immunol 2003;4:1052–4
44. Kane LP, Andres PG, Howland KC, Abbas AK, Weiss A. Akt provides the CD28 costimulatory signal for up-regulation of IL-2 and IFN-gamma but not TH2 cytokines. Nat Immunol 2001;2:37–44
45. Nagata T, Kansha M, Irita K, Takahashi S. Propofol inhibits FMLP-stimulated phosphorylation of p42 mitogen-activated protein kinase and chemotaxis in human neutrophils. Br J Anaesth 2001;86:853–8
46. Hoyer KK, Dooms H, Barron L, Abbas AK. Interleukin-2 in the development and control of inflammatory disease. Immunol Rev 2008;226:19–28
47. Margolin KA. Interleukin-2 in the treatment of renal cancer. Semin Oncol 2000;27:194–203
48. Dutcher J. Current status of interleukin-2 therapy for metastatic renal cell carcinoma and metastatic melanoma. Oncology (Williston Park) 2002;16:4–10
49. Pahwa S, Morales M. Interleukin-2 therapy in HIV infection. AIDS Patient Care STDS 1998;12:187–97
50. Oberholzer A, Oberholzer C, Moldawer LL. Sepsis syndromes: understanding the role of innate and acquired immunity. Shock 2001;16:83–96
51. Hotchkiss RS, Nicholson DW. Apoptosis and caspases regulate death and inflammation in sepsis. Nat Rev Immunol 2006;6: 813–21
52. Pandharipande PP, Sanders RD, Girard TD, McGrane S, Thompson JL, Shintani AK, Herr DL, Maze M, Ely EW. Effect of dexmedetomidine versus lorazepam on outcome in patients with sepsis: an a priori-designed analysis of the MENDS randomized controlled trial. Crit Care 2010;14:R38
53. Cury-Boaventura M, Gorjao R, Martins de Lima T, Soriano F, Curi R. Toxicity of two lipid emulsions on human lymphocytes and neutrophils. Crit Care 2007;11:P408
© 2011 International Anesthesia Research Society