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Background: Modulation of the inflammatory stress response by anesthesia may be responsible for an increased susceptibility to infectious complications, such as wound infection or pneumonia. Sevoflurane, a specific inhibitor of activator protein-1, an immediate early transcription factor, induces apoptosis in T-cells. Because p38 can be involved either in pro- or antiapoptotic processes, we examined whether the sevoflurane-induced apoptosis is mediated by p38 activation in Jurkat T-cells., Methods: Jurkat T-cells were exposed to different concentrations of sevoflurane, isoflurane, or desflurane in vitro. Phosphorylation of mitogen-activated protein (MAP) kinases, upstream kinases, downstream activating transcription factor 2 ATF-2, and caspase-3 processing were evaluated by Western blot. p38 kinase activity was evaluated after immunoprecipitation and phosphorylation of the substrate ATF-2 using Western blot. Apoptosis was assessed using flow cytometry after staining with green fluorescent protein-annexin V., Results: While desflurane had no effect, sevoflurane and isoflurane induced p38 phosphorylation with sevoflurane inducing p38 kinase activity. Sevoflurane did not affect the MAP kinases ERK and JNK. Sevoflurane exposure also induced phosphorylation of apoptosis signal-regulating kinase-1 (ASK1), MAP kinase kinases 3 and 6 (MKK3/MKK6), and ATF-2. Pretreatment of cells with the general caspase inhibitor Z-VAD.fmk did not prevent the sevoflurane-induced phosphorylation of p38. Isoflurane- and sevoflurane-mediated caspase-3 processing and apoptosis could not be abolished by pretreatment with the specific p38 inhibitors SB202190 and SB203580., Conclusions: Sevoflurane is a specific activator of the apoptosis signal-regulating kinase-1-, MKK3/MKK6-p38 MAP kinase cascade in Jurkat T-cells. Our data suggest that sevoflurane-induced p38 activation is not affected by caspase activation. Furthermore, sevoflurane-induced apoptosis is not dependent on p38 MAP kinase activation.

Adrenergic drugs are often used for hemodynamic support of cardiac output and vasomotor tone in critically ill patients. Recent evidence shows that the administration of these vasoactive drugs may affect cytokine release and could influence the inflammatory response. However, the mechanism of this immunomodulatory effect remains unknown. The nuclear transcription factor-kappaB (NF-kappaB) regulates the expression of many cytokines and plays a central role in the immune response. Therefore, we examined the effects of various adrenergic drugs (dobutamine, xamoterol, clenbuterol, epinephrine, norepinephrine, and phenylephrine) on the activation of NF-kappaB, on the NF-kappaB-driven reporter gene activity, and on the expression of the NF-kappaB target gene interleukin (IL)-8. In addition, we quantified the amount of the NF-kappaB inhibitors IkappaBalpha and IL-10. Here we report that dobutamine inhibited the activation of NF-kappaB in primary human CD3(+) T lymphocytes. Suppression of NF-kappaB involved the stabilization of its inhibitor, IkappaBalpha. The effect appears to be beta(2)-receptor specific, because beta(1)-adrenergic and alpha-adrenergic substances (i.e., xamoterol, epinephrine, norepinephrine, and phenylephrine) did not affect NF-kappaB activation and because dobutamine-mediated inhibition of NF-kappaB could be prevented by a specific beta(2)-antagonist. Our results demonstrate that dobutamine is a potent and specific inhibitor of NF-kappaB, and they thus provide a possible molecular mechanism for the immunomodulation associated with beta-adrenergic therapy.

Background: Modulation of immune defense mechanisms by volatile anesthetics during general anesthesia may compromise postoperative immune competence and healing reactions and affect the infection rate and the rate of tumor metastases disseminated during surgery. Several mechanisms have been suggested to account for these effects. The current study was undertaken to examine the molecular mechanisms underlying these observations., Methods: Effects of sevoflurane, isoflurane, and desflurane were studied in vitro in primary human CD3 T-lymphocytes. DNA-binding activity of the transcription factor activator protein-1 (AP-1) was assessed using an electrophoretic mobility shift assay. Phorbol-myristate-acetate-dependent effects of sevoflurane on the phosphorylation of the mitogen-activated protein kinases were studied using Western blots, the trans-activating potency of AP-1 was determined using reporter gene assays, and the cytokine release was measured using enzyme-linked immunosorbent assays., Results: Sevoflurane inhibited activation of the transcription factor AP-1. This effect was specific, as the activity of nuclear factor kappabeta, nuclear factor of activated T cells, and specific protein-1 was not altered and several other volatile anesthetics studied did not affect AP-1 activation. Sevoflurane-mediated suppression of AP-1 could be observed in primary CD3 lymphocytes from healthy volunteers, was time-dependent and concentration-dependent, and occurred at concentrations that are clinically achieved. It resulted in an inhibition of AP-1-driven reporter gene activity and of the expression of the AP-1 target gene interleukin-3. Suppression of AP-1 was associated with altered phosphorylation of p38 mitogen-activated protein kinases., Conclusion: The data demonstrate that sevoflurane is a specific inhibitor of AP-1 and may thus provide a molecular mechanism for the antiinflammatory effects associated with sevoflurane administration.

Background: Thiopental is frequently used for the treatment of intracranial hypertension after severe head injury and is associated with immunosuppressive effects. The authors have recently reported that thiopental inhibits activation of nuclear factor (NF) kappaB, a transcription factor implicated in the expression of many inflammatory genes. Thus, it was the aim of the current study to examine the molecular mechanism of this inhibitory effect., Methods: The authors tested gamma-aminobutyric acid (GABA), the GABA(A) antagonist bicuculline, and the GABA(B) antagonist dichlorophenyl-methyl-amino-propyl-diethoxymethyl-phosphinic acid (CGP 52432) in combination with thiopental for their influence on the activation of NF-kappaB. In addition, they investigated the direct effect of thiopental on activated NF-kappaB DNA binding activity. These experiments were conducted in Jurkat T lymphocytes using electrophoretic mobility shift assays. The presence of the phosphorylated and dephosphorylated NF-kappaB inhibitor IkappaBalpha (Western blotting) and IkappaB kinase activity were studied in Jurkat T cells and human CD3+ T lymphocytes. In addition, the authors tested the effect of the structural barbiturate analog pairs thiopental-pentobarbital and thiamylal-secobarbital and of thiopental in combination with the thio-group containing chemical dithiothreitol on the activation of NF-kappaB., Results: GABA did not inhibit NF-kappaB activation, and the GABA(A) and GABA(B) antagonists bicuculline and CGP did not diminish the thiopental-mediated inhibitory effect on NF-kappaB activation. Thiopental did not inhibit activated NF-kappaB directly in a cell-free system. The phosphorylation of IkappaBalpha was prevented after incubation with 1,000 microg/ml thiopental. The same concentration of thiopental also inhibited IkappaB kinase activity in tumor necrosis factor-stimulated Jurkat T cells and human CD3+ T lymphocytes (60% suppression, P < 0.05 vs. tumor necrosis factor alpha alone). Thiobarbiturates (4 x 10(-3) m) inhibited NF-kappaB activity, whereas equimolar concentrations of the structural oxyanalogs did not. Preincubation of thiopental with dithiothreitol diminished the inhibitory effect., Conclusion: Thiopental-mediated inhibition of NF-kappaB activation is due to the suppression of IkappaB kinase activity and depends at least in part on the thio-group of the barbiturate molecule.

Background: Thiopental is frequently used for the treatment of intracranial hypertension after severe head injury. Its long-term administration increases the incidence of nosocomial infections, which contributes to the high mortality rate of these patients. However, the mechanism of its immunosuppressing effect remains unknown., Methods: The effect of thiopental (200-1000 microg/ml) on the activation of the nuclear transcription factor kappaB (NF-kappaB; electrophoretic mobility shift assays), on NF-kappaB-driven reporter gene activity (transient transfection assays), on the expression of NF-kappaB target genes (enzyme-linked immunoassays), on T-cell activation (flow cytometric analyses of CD69 expression), and on the content of the NF-kappaB inhibitor IkappaB-alpha (Western blotting) was studied in human T lymphocytes in vitro., Results: Thiopental inhibited the activation of the transcription factor NF-kappaB but did not alter the activity of the cyclic adenosine monophosphate response element binding protein. Other barbiturates (methohexital), anesthetics (etomidate, propofol, ketamine), or opioids (fentanyl, morphine) did not affect NF-kappaB activation. Thiopental-mediated suppression of NF-kappaB could be observed in Jurkat cells and in primary CD3+ lymphocytes from healthy volunteers, was time- and concentration-dependent, occurred at concentrations that are clinically achieved, and persisted for hours after the incubation. It was associated with an inhibition of NF-kappaB-driven reporter gene activity, of the expression of interleukin-2, -6, and -8, and interferon gamma, and of the activation of CD3+ lymphocytes. Suppression of NF-kappaB appeared to involve reduced degradation of IkappaB-alpha., Conclusion: The results demonstrate that thiopental inhibits the activation of NF-kappaB and may thus provide a molecular mechanism for some of the immunosuppressing effects associated with thiopental therapy.