Chika Kawasaki

Ketamine suppresses proinflammatory cytokine production in human whole blood in vitro.

UNLABELLED The production of proinflammatory cytokines, such as tumor necrosis factor (TNF) a, interleukin (IL)-6, and IL-8, increases in patients with sepsis; marked production causes organ failure and septic shock. We previously reported that ketamine suppressed lipopolysaccharide (LPS)-induced TNF-alpha production in mice. However, there are no reports on the effect of ketamine on cytokine production in human whole blood. Therefore, in this study, we investigated the efficacy of ketamine on LPS-induced TNF-alpha, IL-6, and IL-8 production and recombinant human (rh) TNF-a-induced IL-6 and IL-8 production in human whole blood. After adding different doses of ketamine to whole blood, the blood was stimulated with LPS or rhTNF. After incubation, the plasma TNF-alpha activity and IL-6 and IL-8 concentrations were measured using the L929 cell cytotoxic assay or an enzyme-linked immunoassay. Ketamine significantly suppressed LPS-induced TNF-alpha production at concentrations >20 microg/mL. At concentrations >100 microg/mL, ketamine also significantly suppressed both LPS-induced and rhTNF-induced IL-6 and IL-8 production. In this study, we demonstrated that ketamine directly inhibits the production of proinflammatory cytokines such as TNF-alpha, IL-6, and IL-8 in human whole blood. IMPLICATIONS We found that ketamine suppressed lipopolysaccharide-induced tumor necrosis factor alpha, interleukin (IL)-6, and IL-8 production and recombinant human tumor necrosis factor-induced IL-6 and IL-8 production in human whole blood. Ketamine directly suppresses proinflammatory cytokine production.

Surgical stress induces endotoxin hyporesponsiveness and an early decrease of monocyte mCD14 and HLA-DR expression during surgery.

It is generally accepted that major surgery is associated with severe alterations of the host-defense mechanisms. We investigated the effect of surgical stress on the immune system. Specifically, we studied the relationship between perioperative lipopolysaccharide (LPS) hyporesponsiveness and monocyte human leukocyte antigen-DR (HLA-DR) and CD14 expression during the perioperative period in 20 patients who underwent partial gastrectomy. This study demonstrated that surgical stress rapidly depressed monocyte mCD14 and HLA-DR expression in comparison with preanesthesia levels. Monocyte mCD14 expression recovered to preoperative levels on the first postoperative day, and monocyte HLA-DR expression recovered by the seventh postoperative day. Consistent with our previous study, LPS-induced tumor necrosis factor (TNF)-&agr; production ex vivo was significantly suppressed from the beginning of the operation. On the contrary, the plasma interleukin-10 concentration started to increase after the surgical incision was made. LPS hyporesponsiveness was least at the end of the operation and returned to preoperative levels on the first postoperative day. In conclusion, the present study demonstrated that LPS responsiveness, plasma interleukin-10 concentration, and monocytes mCD14 and HLA-DR expression altered from the early period of surgery. These alterations may be related to the impairment of the immune system during the perioperative period.

Ketamine isomers suppress superantigen-induced proinflammatory cytokine production in human whole blood

PurposeTo investigate the efficacy of S(+)-ketamine and R(−)-ketamine on staphylococcal enterotoxin B (SEB)-induced tumour necrosis factor (TNF)-, interleukin (IL)-6, and IL-8 production in human whole bloodin vitro.MethodsAfter Ethics Committee approval and informed consent, blood samples were obtained from ten healthy volunteers and diluted with five volumes of RPMI 1640. After adding different doses of ketamine isomers (0–1000 μM), the blood was stimulated with SEB (10 ng·mL−1). After a six-hour incubation period, the plasma TNF-activity was determined by the L929 cell cytotoxic assay and IL-6 and IL-8 concentrations were measured using an enzyme-linked immunoassay.ResultsKetamine isomers significantly suppressed SEB-induced TNF-production at concentrations exceeding 50 μM. Ketamine isomers at concentrations exceeding 100 μM also significantly suppressed SEB-induced IL-6 production. Furthermore, ketamine isomers at concentrations exceeding 500 μM significantly suppressed SEB-induced IL-8 production. There were no significant differences between the suppressive effects of S(+)-ketamine and R(−)-ketamine on SEB-induced proinflammatory cytokine production.ConclusionThis study demonstrated that ketamine isomers suppressed SEB-induced TNF-, IL-6, and IL-8 production in human whole blood.RésuméObjectifVérifier l’efficacité de la S(+)-kétamine et de la R(−)-kétamine sur la production du facteur nécrosant des tumeurs (FNT)-a, de l’interleukine (IL)-6 et de l’IL-8, induits par l’entérotoxine B d’origine staphylococcique (EBS), dans le sang complet humain in vitro.MéthodeAprès avoir obtenu l’approbation du Comité d’éthique et le consentement éclairé des participants, nous avons recueilli des échantillons sanguins chez dix volontaires en santé et les avons dilué dans cinq volumes de RPMI 1640. Après l’addition de différentes doses d’isomères de kétamine (0–1000 μM), le sang a été stimulé avec l’EBS (10 ng·mL−1). À la suite d’une incubation de six heures, l’activité plasmatique de TNF-a a été déterminée par le dosage de la cytotoxicité cellulaire L929, et les concentrations d’IL-6 et d’IL-8 ont été mesurées au moyen d’un dosage immuno-enzymatique.RésultatsLes isomères de kétamine ont supprimé de façon significative la production du TNF-a induit par l’EBS à des concentrations dépassant 50 μM, la production d’IL-6 induite par l’EBS à des concentrations au delà de 100 μM et la production d’IL-8 induite par l’EBS à des concentrations de plus de 500 μM. Il n’y a pas eu de différence significative entre les effets suppresseurs de la S(+)-kétamine et de la R(−)-kétamine sur la production de cytokine pro-inflammatoire induite pas l’EBS.ConclusionCette étude démontre que les isomères de kétamine suppriment la production du FNT-a, d’IL-6 et d’IL-8, induits par l’EBS, dans le sang complet humain.

The effects of dexmedetomidine on inflammatory mediators after cardiopulmonary bypass

Cardiac surgery with cardiopulmonary bypass is associated with the development of a systemic inflammatory response that can often lead to dysfunction of major organs. We hypothesised that the highly selective α2‐adrenergic agonist, dexmedetomidine, attenuates the systemic inflammatory response. Forty‐two patients were randomly assigned to receive dexmedetomidine or saline after aortic cross‐clamping). The mean (SD) levels of the nuclear protein plasma high‐mobility group box 1 increased significantly from 5.1 (2.2) ng.ml−1 during (16.6 (7.3) ng.ml−1) and after (14.3 (8.2) ng.ml−1) cardiopulmonary bypass in the saline group. In the dexmedetomidine group, the levels increased significantly only during cardiopulmonary bypass (4.0 (1.9) ng.ml−1 baseline vs 10.8 (2.7) ng.ml−1) but not after (7.4 (3.8) ng.ml−1). Dexmedetomidine infusion also suppressed the rise in mean (SD) interleukin‐6 levels after cardiopulmonary bypass (a rise of 124.5 (72.0) pg.ml−1 vs 65.3 (30.9) pg.ml−1). These suppressive effects of dexmedetomidine might be due to the inhibition of nuclear factor kappa B activation and suggest that intra‐operative dexmedetomidine may beneficially inhibit inflammatory responses associated with ischaemia‐reperfusion injury during cardiopulmonary bypass.

Dexmedetomidine suppresses proinflammatory mediator production in human whole blood in vitro.

BACKGROUND: It has been demonstrated that proinflammatory mediators increase in patients with sepsis, trauma, and burns. These mediators are associated with the development of septic shock and organ dysfunction. Dexmedetomidine (DEX), a selective agonist of the [alpha]2‐adrenergic receptors, is used in intensive care units for sedation. However, it still remains unclear whether DEX administration has any effects on the production of proinflammatory mediators. In this study, we investigated the effects of DEX on lipopolysaccharide (LPS)–induced production of tumor necrosis factor [alpha], interleukin 6 (IL‐6), IL‐8, and high‐mobility group box 1 protein in human whole blood. METHODS: Human whole blood was cultured with LPS for up to 24 hours, and LPS‐induced proinflammatory mediator production was measured. Next, we tested the effect of DEX on whole blood proinflammatory mediator production. Human whole blood was cultured with LPS and various concentrations of DEX for 12 hours. Then, we investigated the influence of yohimbine, an antagonist of the [alpha]2‐adrenergic receptors, on the effects of DEX. The effect of DEX on necrosis factor [kappa]B (NF[kappa]B) activation was also investigated. RESULTS: DEX suppressed tumor necrosis factor [alpha], IL‐6, IL‐8, and high‐mobility group box 1 protein production in human whole blood. The suppressing effects of DEX on proinflammatory mediator production were reversed by yohimbine. The results suggested that the mechanism for the suppressive effects of DEX on proinflammatory mediator production is meditated via [alpha]2‐adrenergic receptors. These effects of DEX also include an inhibitory effect on NF[kappa]B activation. CONCLUSION: We demonstrate the suppressing effect of DEX on inflammatory mediator production in human whole blood after LPS stimulation. The mechanism for the suppressive effect of DEX on proinflammatory mediator production may be through the [alpha]2‐adrenergic receptors and NF[kappa]B inhibition.

Lidocaine Enhances Apoptosis and Suppresses Mitochondrial Functions of Human Neutrophil In Vitro

BACKGROUND Neutrophils play an essential role in innate immunity and against infection. Mitochondria are organelles that produce energy in the form of adenosine triphosphate (ATP), which is required for maintaining the function and structure of cells and organs. Although local anesthetics (LAs) are widely used in clinical practice, it remains unclear whether LAs such as lidocaine, ropivacaine, and bupivacaine affect neutrophil mitochondrial functions. The aim of this study was to examine whether LAs have any effects on human neutrophil mitochondrial functions. METHODS Freshly isolated human neutrophils were incubated with lidocaine, ropivacaine, or bupivacaine. The oxidative burst and phagocytic activity of neutrophils and apoptotic rate of neutrophils were measured to assess the effect of LAs on neutrophil functions. The ATP concentration, mitochondrial transmembrane potential (Deltapsim), and neutrophil mitochondrial morphology were also measured to evaluate the effect of LAs on mitochondrial functions. RESULTS Lidocaine (400 microm) induced a reduction in the oxidative burst and phagocytosis activity of neutrophils by approximately 20%. The ATP concentration was significantly lower in lidocain-treated neutrophils compared with control neutrophils (876 +/- 25 vs. 1,332 +/- 76 pmol/10(6) neutrophils; p < 0.05). Mitochondrial transmembrane potential (Deltapsim) was also significantly lower in lidocaine-treated neutrophils compared with control neutrophils (p < 0.05). Lidocaine also induced mitochondrial structural changes and induced apoptosis of neutrophils. Ropivacaine and bupivacaine had no effect on neutrophil functions including mitochondrial function. Furthermore, the study of mitochondrial function depletion demonstrated that neutrophil function requires active mitochondrial function. CONCLUSIONS Although ropivacaine and bupivacaine had no effect on neutrophil and mitochondrial functions, lidocaine suppressed neutrophil function, inhibited ATP synthesis, reduced mitochondrial membrane potential, and induced apoptosis.

The effect of local anesthetics on monocyte mCD14 and human leukocyte antigen-DR expression.

It has been demonstrated that local anesthetics have several effects on the immune system. Monocytes and macrophages are essential components of the host response to microbial infection; however, the effect of local anesthetics on monocyte surface receptor expression remains unclear. We designed this study to investigate the effects of local anesthetics on monocyte mCD14 and human leukocyte antigen (HLA)-DR expression and lipopolysaccharide (LPS)-induced or staphylococcal enterotoxin B (SEB)-induced tumor necrosis factor (TNF)-&agr; production. Blood samples were obtained from 10 healthy volunteers. The effects of local anesthetics on LPS- or SEB-induced TNF-&agr; production were determined by using an enzyme-linked immunosorbent assay. After different doses of local anesthetics were added, the blood was stimulated with LPS (10 ng/mL) or SEB (10 &mgr;g/mL) for 4 h. The effects of local anesthetics on monocyte mCD14 and HLA-DR expression were measured by dual monoclonal antibody staining and flow cytometry. Local anesthetics showed no effect on LPS- or SEB-induced TNF-&agr; production in human whole blood. Local anesthetics suppressed monocyte HLA-DR expression in a dose-dependent manner (P < 0.05) but had no effect on monocyte mCD14 expression. This study demonstrated that local anesthetics suppress HLA-DR expression on the surface of human monocytes.

Lidocaine suppresses mouse Peyer's Patch T cell functions and induces bacterial translocation

BACKGROUND The gastrointestinal mucosa is an important route of entry for microbial pathogens. The immune cells of Peyers patch (PP) compartments contribute to the active immune response against infection. Although local anesthetics are widely used in clinical practice, it remains unclear whether local anesthetics such as lidocaine affect PP T cell functions. METHODS The aim of this study was to examine if lidocaine has any effects on mouse PP T cell functions. To test this, freshly isolated mouse Peyers patch T cells were incubated with lidocaine. The effects of lidocaine on concanavalin A-stimulated PP T cell proliferation and cytokine production were assessed. The effect of lidocaine on PP T cell mitogen-activated protein kinase (MAPK) activation was also assessed. RESULTS The results indicate that lidocaine suppresses cell proliferation, cytokine production, and MAPK activation in PP T cells. Furthermore, we found that the chronic in vivo exposure to lidocaine increases bacterial accumulation in PP. CONCLUSION The enhanced immunosuppressive effects of lidocaine on PP T cell functions could contribute to the hosts enhanced susceptibility to infection.

Thrombomodulin improved liver injury, coagulopathy, and mortality in an experimental heatstroke model in mice.

BACKGROUND:Heatstroke is a life-threatening illness and causes high mortality due to multiple organ injuries. Thrombomodulin (TM) is an endothelial anticoagulant cofactor that plays an important role in the regulation of intravascular coagulation. In this study, we investigated the effect of TM on the inflammatory process, liver function, coagulation status, and mortality in experimental heatstroke. METHODS:Male C3H/HeN (8–10 weeks) mice were randomly assigned to the TM-treated group (TG-Pre) or nontreated heatstroke group (HS). In group TG-Pre, mice were treated with recombinant soluble TM (1 mg/kg, intraperitoneally) before heat exposure. In some experiments, recombinant soluble TM was administrated during heat exposure (TG-Delay). Heatstroke was induced by exposure to ambient temperature of 38°C for 4 hours. After heat exposure, the levels of tumor necrosis factor-&agr;, interleukin-6, and plasma high-mobility group box 1 (HMGB1), liver function, plasma aspartate aminotransferase and alanine aminotransferase concentrations, and immunohistochemical and histopathological characteristics of the livers were determined. The coagulation status, plasma protein C levels, and thrombin–antithrombin complex levels were also measured. RESULTS:In group HS, plasma cytokines and HMGB1 concentrations increased after heat exposure. Plasma aspartate aminotransferase and alanine aminotransferase concentrations increased after heat exposure. In group HS livers, strong and extensive immunostaining for HMGB1 was observed. In addition, there was extensive hepatocellular necrosis and collapse of nuclei observed. In group HS, plasma protein C levels were suppressed and plasma thrombin–antithrombin complex levels increased. In group TG-Pre, plasma cytokines and HMGB1 concentrations were suppressed after heat exposure compared with group HS. Liver injury, coagulopathy, and mortality also improved in group TG-Pre. Furthermore, recombinant soluble TM treatment decreased mortality even with delayed treatment. CONCLUSIONS:This study demonstrated that recombinant soluble TM suppressed plasma cytokines and HMGB1 concentrations after heat exposure. Recombinant soluble TM also improved liver injury and coagulopathy. Recombinant soluble TM treatment improved mortality even with delayed treatment. Recombinant soluble TM may be a beneficial treatment for heatstroke patients.