Dual platelet inhibition in cases of severe retrobulbar hemorrhage following retrobulbar and peribulbar anesthesia.

PURPOSE: To evaluate the prevalence of dual platelet inhibition in cases of severe retrobulbar hemorrhage following retrobulbar and peribulbar anesthesia. SETTING: Department of Ophthalmology, Ludwig-Maximilans Universität, München, Germany. DESIGN: Retrospective study. METHODS: Two groups of patients were screened retrospectively over a 5-year period for the inclusion criterion of severe retrobulbar hematoma after retrobulbar or parabulbar injection. The first group consisted of emergency cases referred to the clinic. A second group of patients had received retrobulbar block at the hospital. All cases were collected and screened for the presence of antiplatelet therapy. RESULTS: Among roughly 160 000 patient records screened, 3 patients with grade IV retrobulbar hematoma were identified. Two of these patients were taking dual antiplatelet medications and 2 were on anticoagulation therapy during the time of retrobulbar or peribulbar anesthesia. None of the cases showed single medication platelet inhibition. The visual acuity of all patients stayed low at the 6-month follow-up (1.2 logMAR in 1 patient and no light perception in 2 patients). CONCLUSIONS: Retrobulbar hematoma is a rare but severe complication of retrobulbar anesthesia. With the high prevalence of dual platelet inhibition found in these cases, a prospective controlled trial seems unethical. In these high-risk patients, surgery should be performed under topical anesthesia if possible or general anesthesia if necessary. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Comparing hemodynamics, blood gas analyses and proinflammatory cytokines in endotoxemic and severely septic rats.

Lipopolysaccharide (LPS) is often used in short-term models of inflammation. Since endotoxemia and sepsis are different entities we have recently established a short-term sepsis model in rats induced by cecal ligation and incision (CLI). This retrospective study was conducted in order to identify similarities and differences between both experimental approaches. 32 anesthetized/ventilated male rats from the following four groups were analysed (each n=8): CTRL-group (0.9% NaCl i.v.); LPS-group (5mg/kg i.v.); SHAM-group (laparotomy); CLI-group (1.5 cm blade incision). Mean arterial blood pressure (MAP) and blood gas parameters (arterial base excess (BE) and pH) were continuously recorded. Total observation time was 300 min. Plasma samples were obtained afterwards. LPS and CLI induced significant arterial hypotension and metabolic acidosis compared to CTRL- or SHAM-group, respectively. Yet, between the LPS- and CLI-groups, there were no differences in MAP, BE and pH. LPS significantly induced IL-1ß, IL-6 and TNF-α in the plasma. In contrast, CLI showed a clear tendency towards increased IL-1ß and IL-6 plasma levels and did not affect TNF-α. Our results indicate that the CLI sepsis model is suitable for short-term investigations on hemodynamic alterations and blood gas analyses during sepsis. 300 min after the proinflammatory insult, plasma concentrations of IL-1ß and IL-6 in the plasma remain considerably lower after CLI compared to endotoxemia. Low TNF-α concentrations 300 min after sepsis induction could be interpreted as considerable immunosuppression during CLI sepsis.

Effects of short-term infusion of lipid emulsions on pro-inflammatory cytokines and lymphocyte apoptosis in septic and non-septic rats.

Long-term administration of PUFA is known to modulate immune functions and apoptotic pathways depending on the respective amount of n-6 and n-3 fatty acids (FA). Data on short-term effects on apoptotic pathways are rare. Apoptosis of splenic lymphocytes is the hallmark of detrimental sepsis. Therefore, we aimed to compare the immediate effects of parenterally administered n-6-enriched soyabean oil (SO)- and n-3-enriched fish oil (FO)-based lipid emulsions after laparotomy (LAP; sham procedure) and after induction of acute, severe sepsis by caecal ligation and incision. After 390 min of observation time, plasma was analysed for IL-1ß, IL-6 and NEFA. Apoptosis in splenic lymphocytes was quantified by Annexin-V expression. After LAP, infusion of both FO and SO did not change cytokine concentrations. Sepsis increased both cytokines. FO but not SO further augmented the rise. After LAP, SO increased NEFA, and both lipid emulsions reduced free arachidonic acid (AA). Sepsis resulted in a dramatic decrease in NEFA and AA. The drop in NEFA and AA was prevented by both SO and FO. In addition, FO resulted in an increased concentration of n-3 FA under both conditions. Infusion of both lipid emulsions induced apoptosis in splenic lymphocytes after LAP. Sepsis-induced apoptosis was not further enhanced by FO or SO. The present study shows that short-term administration of FO as opposed to SO caused pro-inflammatory effects during sepsis. Moreover, short-term administration of both SO and FO suffices to induce apoptosis in splenic lymphocytes. Finally, SO and FO do not further enhance sepsis-induced splenic apoptosis.

Sevoflurane and isoflurane decrease TNF-alpha-induced gene expression in human monocytic THP-1 cells: potential role of intracellular IkappaBalpha regulation.

The nuclear factor (NF)-kappaB/inhibitory (I)kappaBalpha pathway is one of the most important intracellular signal transduction pathways during inflammation which is induced by a variety of major early response cytokines. Recent studies suggest that volatile anesthetics interfere with inflammatory cytokine production through inhibition of intracellular signal transduction pathways. We, therefore, aimed to investigate the effects of the volatile anesthetics sevoflurane and isoflurane on NF-kappaB/IkappaBalpha-dependent intracellular signal transduction in human monocytic THP-1 cells induced by tumor necrosis factor-alpha (TNF-alpha) and production of interleukin-8 (IL-8) and downstream heme oxygenase-1 (HO-1). THP-1 cells, a human monocytic cell line, were used in an in vitro model which enables the exposure to volatile anesthetics. Using this model, THP-1 cells were subjected to sevoflurane or isoflurane exposure (1 MAC each) and were stimulated with TNF-alpha (50 or 100 ng/ml). Compared to untreated cells, expression of intracellular HO-1-protein and release of IL-8 into cell culture supernatants and corresponding mRNA expression were attenuated in THP-1 cells exposed to sevoflurane and isoflurane, respectively. Moreover, translocation of NF-kappaB and degradation of IkappaBalpha were markedly reduced by both anesthetics. Notably, under unstimulated conditions, exposure to sevoflurane induced a sustained upregulation of the IkappaBalpha content in THP-1 cells. We demonstrated inhibition of TNF-alpha-induced gene expression and release of IL-8 and HO-1 in human monocytic THP-1 cells exposed to both volatile anesthetics. This was associated with an upregulated intracellular IkappaBalpha content followed by decreased NF-kappaB translocation. This was more sustained during exposure to sevoflurane and may provide an additional intracellular mechanism for the anti-inflammatory effects associated with sevoflurane administration.

Effects of intravenous and inhaled levosimendan in severe rodent sepsis.

PURPOSE: We aimed at comparing the effects of intravenous (i.v.) and inhaled (inh.) levosimendan (LEVO) on survival, inflammatory cytokines and the apoptotic mediator caspase-3 in a rat model of severe sepsis induced by cecal ligation and incision (CLI). METHODS: Twenty-eight anesthetized/ventilated male Sprague-Dawley rats (body weight 528 +/- 20 g) underwent laparotomy. Cecal mobilisation served as control (SHAM, n = 7). In all other groups, severe sepsis was induced by CLI. No further intervention occurred in the CLI-group (n = 7). 180 min after CLI, 24 microg/kg i.v. LEVO was administered in the CLI + LEVO-IV-group (n = 7), and 24 microg/kg inh. LEVO was administered via jet nebulizer in the CLI + LEVO-INH-group (n = 7). RESULTS: CLI induced arterial hypotension, with i.v. and inh. LEVO attenuating blood pressure decrease over 390 min [CLI 34(31/50), CLI + LEVO-IV 82(69/131)*, CLI + LEVO-INH 78(62/85)* mmHg; median(25/75% quartile), *P < 0.05]. CLI induced metabolic acidosis. I.v. and inh. LEVO avoided arterial pH [CLI 7.18(7.16/7.2), CLI + LEVO-IV 7.27(7.24/7.31)*, CLI + LEVO-INH 7.26(7.24/7.28)*] and base excess deterioration [CLI -19(-21.8/-17.9), CLI + LEVO-IV -13(-14.8/-12)*, CLI + LEVO-INH -12.7(-14/-12.2)* mmol/l]. Overall mortality in the CLI-group was 57% compared to 0%* in both LEVO-treated groups after 390 min. LEVO administration significantly attenuated the increase in proinflammatory interleukin (IL)-1beta [CLI 896(739/911), CLI + LEVO-IV 302(230/385)*, CLI + LEVO-INH 346(271/548) pg/ml] and IL-6 [CLI 35651(31413/35816), CLI + LEVO-IV 21156(18397/28026), CLI + LEVO-INH 13674(10105/24843) pg/ml] in the plasma and reduced cleaved caspase-3 expression in the spleen. CONCLUSIONS: In a rat model of severe sepsis induced by CLI, i.v. and inh. LEVO equally attenuated arterial hypotension, metabolic acidosis and prolonged survival. Moreover, i.v. and inh. LEVO inhibited proinflammatory mediator release and reduced splenic caspase-3 expression.

Inhaled IL-10 reduces biotrauma and mortality in a model of ventilator-induced lung injury.

BACKGROUND: High-pressure ventilation induces barotrauma and pulmonary inflammation, thus leading to ventilator-induced lung injury (VILI). By limiting the pulmonal inflammation cascade the anti-inflammatory cytokine interleukin (IL)-10 may have protective effects. Via inhalation, IL-10 reaches the pulmonary system directly and in high concentrations. METHODS: Thirty six male, anesthetized and mechanically ventilated Sprague-Dawley rats were randomly assigned to the following groups (n=9, each): SHAM: pressure controlled ventilation with p(max)=20cmH(2)O, PEEP=4; VILI: ventilator settings were changed for 20min to p(max)=45cmH(2)O, PEEP=0; IL-10(high): inhalation of 10microg/kg IL-10 prior to induction of VILI; and IL-10(low): inhalation of 1microg/kg IL-10 prior to induction of VILI. All groups were ventilated and observed for 4h. RESULTS: High-pressure ventilation increased the concentrations of macrophage inflammatory protein (MIP)-2 and IL-1beta in bronchoalveolar lavage fluid (BALF) and plasma. This effect was reduced by the inhalation of IL-10 (10microg/kg). Additionally, IL-10 increased the animal survival time (78% vs. 22% 4-h mortality rate) and reduced NO-release from ex vivo cultured alveolar macrophages. Moreover, VILI-induced pulmonary heat shock protein-70 expression was reduced by IL-10 aerosol in a dose-dependent manner. Similarly, the activation of matrix metalloproteinase (MMP)-9 in BALF was reduced dose-dependently by IL-10. IL-10-treated animals showed a lower macroscopic lung injury score and less impairment of lung integrity and gas exchange. CONCLUSIONS: Prophylactic inhalation of IL-10 improved survival and reduced lung injury in experimental VILI. Results indicate that this effect may be mediated by the inhibition of stress-induced inflammation and pulmonary biotrauma.

Cecal ligation and incision: an acute onset model of severe sepsis in rats.

BACKGROUND: Sepsis is a leading cause of death among critically ill patients. Up to now, severe sepsis with acute onset in animals has been induced mainly through injection of single bacteria species or endotoxin and not through a surgical procedure, which might adequately mirror the situation in septic patients. We therefore aimed to establish a surgical model of severe sepsis in rodents fulfilling international sepsis criteria. MATERIALS AND METHODS: Twenty-eight anesthetized/ventilated Sprague Dawley rats underwent laparotomy and cecal mobilization. The cecum was either replaced into the abdomen (SHAM, n = 14) or the cecum and the mesenteric blood vessels were ligated, and the cecum was opened through a 1.5 cm blade incision (cecal ligation and incision, CLI, n = 14). RESULTS: Within 390 min, mortality was 0% (SHAM) and 50% (CLI), respectively. Compared with SHAM, CLI resulted in a 43% reduction of mean arterial blood pressure and in severe metabolic acidosis as measured by arterial base excess and pH. CLI led to a 15-fold increase in mononuclear cell population and to a 5-fold accumulation of nitrite in peritoneal lavage. Abdominal swabs from the Douglas cavity in CLI-animals showed gram-positive and gram-negative bacterial growth on agar compared with sterile swabs from SHAM-animals. In CLI-animals, plasma IL-1beta level was increased to 435 pg/mL (SHAM: 10 pg/mL) and plasma IL-6 level to 19718 pg/mL (SHAM: 832 pg/mL). CONCLUSIONS: CLI causes bacterial peritonitis with subsequent systemic inflammation and organ dysfunction. Thus, CLI mimics clinical sepsis and provides a surgical short term model of severe sepsis in rodents.

IFN-gamma impairs release of IL-8 by IL-1beta-stimulated A549 lung carcinoma cells.

BACKGROUND: Production of interferon (IFN)-gamma is key to efficient anti-tumor immunity. The present study was set out to investigate effects of IFNgamma on the release of the potent pro-angiogenic mediator IL-8 by human A549 lung carcinoma cells. METHODS: A549 cells were cultured and stimulated with interleukin (IL)-1beta alone or in combination with IFNgamma. IL-8 production by these cells was analyzed with enzyme linked immuno sorbent assay (ELISA). mRNA-expression was analyzed by real-time PCR and RNase protection assay (RPA), respectively. Expression of inhibitor-kappa Balpha, cellular IL-8, and cyclooxygenase-2 was analyzed by Western blot analysis. RESULTS: Here we demonstrate that IFNgamma efficiently reduced IL-8 secretion under the influence of IL-1beta. Surprisingly, real-time PCR analysis and RPA revealed that the inhibitory effect of IFNgamma on IL-8 was not associated with significant changes in mRNA levels. These observations concurred with lack of a modulatory activity of IFNgamma on IL-1beta-induced NF-kappaB activation as assessed by cellular IkappaB levels. Moreover, analysis of intracellular IL-8 suggests that IFNgamma modulated IL-8 secretion by action on the posttranslational level. In contrast to IL-8, IL-1beta-induced cyclooxygenase-2 expression and release of IL-6 were not affected by IFNgamma indicating that modulation of IL-1beta action by this cytokine displays specificity. CONCLUSION: Data presented herein agree with an angiostatic role of IFNgamma as seen in rodent models of solid tumors and suggest that increasing T helper type 1 (Th1)-like functions in lung cancer patients e.g. by local delivery of IFNgamma may mediate therapeutic benefit via mechanisms that potentially include modulation of pro-angiogenic IL-8.

Inhaled levosimendan reduces mortality and release of proinflammatory mediators in a rat model of experimental ventilator-induced lung injury.

OBJECTIVES: Mechanical ventilation during critical care can cause structural and functional disturbances in the lung with subsequent release of proinflammatory mediators, termed ventilator-induced lung injury (VILI). VILI progressively provokes decreased efficiency of gas exchange with subsequent hypoxic pulmonary vasoconstriction leading to cardiopulmonary alterations, such as pulmonary hypertension and right heart failure. We therefore aimed to evaluate whether inhalation therapy with levosimendan, a calcium-sensitizer with pulmonary vasodilating properties, could attenuate VILI and improve short-term survival in a rat experimental model. DESIGN: Experimental animal model. SETTING: University hospital. SUBJECTS: Forty male Sprague-Dawley rats. INTERVENTIONS: Rats were randomly treated as follows (n = 8, each group): 1) inhalation of the solvent only before induction of VILI, no further intervention; 2) inhalation of 240 microg of levosimendan before VILI induction; 3) inhalation of 24 microg of levosimendan before VILI induction; 4) intravenous administration of 24 microg/kg levosimendan before VILI induction; 5) control group with surgical preparation only. All groups were observed for 4 hrs. MEASUREMENTS AND MAIN RESULTS: After 4 hrs following induction of VILI, levels of interleukin-1beta and macrophage inflammatory protein-2 in plasma and bronchoalveolar lavage fluid were analyzed by enzyme-linked immunosorbent assay. Nitric oxide release from alveolar macrophages was measured by Griess assay. Content of matrix metalloproteinase-2 and matrix metalloproteinase-9 in bronchoalveolar lavage fluid was analyzed by gelatin zymography. Inhalation of 240 microg of levosimendan significantly improved survival after 4 hrs and mean arterial blood pressure compared with VILI only. Additionally, inhalation of 240 microg and infusion of 24 microg/kg levosimendan significantly reduced the release of interleukin-1beta, the nitric oxide release from alveolar macrophages, macrophage inflammatory protein-2 in plasma, and the macrophage inflammatory protein-2 and matrix metalloproteinase-9 content in bronchoalveolar lavage fluid compared with VILI only. CONCLUSIONS: Our study demonstrates that prophylactic inhalation of 240 microg of levosimendan improves survival and reduces release of inflammatory mediators in our experimental model of VILI. This might affect the clinical prophylaxis and treatment of VILI.

Autocrine stimulation of human hepatocytes triggers late DNA synthesis and stabilizes long-term differentiation in vitro.

Isolated human hepatocytes are of great value in investigating cell transplantation, liver physiology, pathology, and drug metabolism. Though hepatocytes possess a tremendous proliferative capacity in vivo, their ability to grow in culture is severely limited. We postulated that repeated medium change, common to most in vitro systems, may prevent long-term maintenance of hepato-specific functions and growth capacity. To verify our hypotheses we compared the DNA synthesis and differentiation status of isolated human hepatocytes, cultured in medium which was renewed every day or was not changed for 3 weeks ('autocrine' setting). Daily medium change led to rapid hepatocellular de-differentiation without any signs of DNA replication. In contrast, the autocrine setting allowed hepatocytes to become highly differentiated, demonstrated by an elevated ASGPr expression level, and increased albumin and fibrinogen synthesis and release. Cytokeratin 18 filaments were stably expressed, whereas cytokeratin 19 remained undetectable. Hepatocytes growing in an autocrine fashion were activated in the presence of hepatocyte growth factor (HGF), evidenced by c-Met phosphorylation. However, HGF response was not achieved when the culture medium was renewed daily. Furthermore, the autocrine setting evoked a late but strong interleukin 6 release into the culture supernatant, reaching maximum values after a 10-day cultivation period, and intense BrdU incorporation after a further 5-day period. Our data suggest that preservation of the same medium creates environmental conditions which allow hepatocytes to control their differentiation status and DNA synthesis in an autocrine fashion. Further studies are necessary to identify the key mediators involved in autocrine communication and to design the optimal culture configuration for clinical application.

Short-term exposure to high-pressure ventilation leads to pulmonary biotrauma and systemic inflammation in the rat.

Though often lifesaving, mechanical ventilation itself bears the risk of lung damage [ventilator-induced lung injury (VILI)]. The underlying molecular mechanisms have not been fully elucidated, but stress-induced mediators seem to play an important role in biotrauma related to VILI. Our purpose was to evaluate an animal model of VILI that allows the observation of pathophysiologic changes along with parameters of biotrauma. For VILI induction, rats (n=16) were ventilated with a peak airway pressure (pmax) of 45 cm H2O and end-expiratory pressure (PEEP) of 0 for 20 min, followed by an observation time of 4 h. In the control group (n=8) the animals were ventilated with a pmax of 20 cm H2O and PEEP of 4. High-pressure ventilation resulted in an increase in paCO2 and a decrease in paO2 and mean arterial pressure. Only 4 animals out of 16 survived 4 h and VILI lungs showed severe macroscopic and microscopic damage, oedema and neutrophil influx. High-pressure ventilation increased the cytokine levels of macrophage inflammatory protein-2 and IL-1beta in bronchoalveolar lavage and plasma. VILI also induced pulmonary heat shock protein-70 expression and the activity of matrix metalloproteinases. The animal model used enabled us to observe the effect of high-pressure ventilation on mortality, lung damage/function and biotrauma. Thus, by combining barotrauma with biotrauma, this animal model may be suitable for studying therapeutical approaches to VILI.

Norepinephrine and vasopressin counteract anti-inflammatory effects of isoflurane in endotoxemic rats.

Volatile anesthetics such as isoflurane have been shown to offer anti-inflammatory effects during experimental endotoxemia whereas the alpha-adrenergic vasopressor norepinephrine exhibits proinflammatory properties on systemic cytokine release under the same conditions. However, during major surgery and in patients with systemic inflammatory response syndrome or sepsis both agents are frequently administered concurrently. We therefore aimed to investigate the influence of preexisting i.v. administration of noradrenaline or vasopressin on the anti-inflammatory effects of isoflurane during experimental endotoxemia. Anesthetized, ventilated Sprague-Dawley rats (n=7 per group) were randomly treated. In the LPS-only group, animals received lipopolysaccharide (LPS, 5 mg/kg, i.v.) with no further specific treatment. In the LPS-isoflurane group, isoflurane inhalation at 1 MAC was initiated simultaneously with induction of endotoxemia (LPS 5 mg/kg, i.v.). Animals in the LPS-isoflurane-norepinephrine group received norepinephrine infusion at 50 microg/kg/h 10 min prior to injection of LPS and inhalation of isoflurane. In the LPS-isoflurane-vasopressin group, vasopressin was administered at 0.5 IE/kg/h 10 min prior to LPS and isoflurane. In the LPS-norepinephrine and the LPS-vasopressin groups the infusion of each vasopressor was started prior to LPS injection without any application of isoflurane. A Sham group served as the control. After 4 h of endotoxemia, plasma levels of TNFalpha, IL-1beta and IL-10 were measured. Alveolar macrophages (AM) were cultured ex vivo for nitrite assay. Induction of endotoxemia resulted in a significant rise in measured plasma cytokines and nitrite production from cultured AM. Inhalation of isoflurane significantly attenuated plasma levels of TNFalpha (-65%) and IL-1beta (-53%) compared to the LPS-only group whereas it had no effect on nitrite production from cultured AM. Preexisting infusions of norepinephrine or vasopressin abolished the anti-inflammatory effects of isoflurane. The data demonstrate that the administration of norepinephrine or vasopressin both counteracted the anti-inflammatory effects of inhaled isoflurane on proinflammatory cytokine release during experimental endotoxemia in rats.

Long-term production of major coagulation factors and inhibitors by primary human hepatocytes in vitro: perspectives for clinical application.

BACKGROUND/AIMS: Patients with coagulation factor disorders require lifelong symptomatic treatment. This is associated with limited efficacy and transmission risks. From a clinical point of view, hepatocyte transplantation offers a rational alternative but is currently being hampered by lack of functional stability of engrafted cells. It was the aim of our study to devise culture conditions providing stable cell polarity, attachment and growth factor stimulation to improve longevity and coagulation factor production. METHODS: Human hepatocytes (HC) were plated on different extracellular matrices, inside collagen gel or Matrigel. HC were grown inside growth factor-enriched serum-free medium (SFM) or exposed to media switching from differentiation (DM) to dedifferentiation (DeDM). RESULTS: Over more than 30 days in vitro human HC synthesized coagulation factors (factors VII, VIII, IX, fibrinogen) and coagulation inhibitors (antithrombin III, protein C). Protein synthesis was augmented when HC were grown inside a 3D collagen type I matrix, while Matrigel showed no additional benefit. Soluble growth factors improved coagulation factor production when applied in SFM or in sequential DM/DeDM. Coagulation factor levels ranged from 3% to 12% in the first week to 2.5-5% after 4 weeks, reaching biologically relevant levels. CONCLUSION: Preserved synthesis and secretion of coagulation factors in balanced proportion by human HC in this model may offer new perspectives for HC transplantation in coagulation defects of patients.

Targeting caspase-1 by inhalation-therapy: effects of Ac-YVAD-CHO on IL-1 beta, IL-18 and downstream proinflammatory parameters as detected in rat endotoxaemia.

OBJECTIVE: We set out to investigate whether the nebulized and inhaled specific caspase-1 inhibitor Ac-YVAD-CHO has the potential to attenuate the pulmonary and systemic release of the caspase-1-dependent cytokines interleukin-1 beta (IL-1 beta) and interleukin-18 (IL-18) as well as their downstream enzymes iNOS and COX-2 in rat experimental endotoxaemia. DESIGN AND SETTING: Controlled, randomized animal study in a university research facility. SUBJECT: Male Sprague-Dawley rats (n=32) were randomly treated as follows: Inhaled Ac-YVAD-CHO was administered in eight rats at a inhaled total dosage of 5 mg and in eight rats at a inhaled total dose of 0.5 mg before infusion of lipopolysaccharide (LPS; 5 mg/kg, i.v.). Eight animals received LPS only. Eight animals served as controls without endotoxaemia. MEASUREMENTS AND RESULTS: After 4h of endotoxaemia, levels of IL-1 beta, IL-18 and TNF-alpha in plasma and bronchoalveolar fluid (BALF) were analyzed. Nitric oxide (NO) release from alveolar macrophages was measured by Griess assay. Amounts of iNOS protein in alveolar macrophages and COX-2 protein in lung homogenates were determined by Western blotting. Significant reductions in release of IL-1 beta (-58%, p<0.05) and IL-18 (-51%, p<0.05) in plasma and IL-1 beta (-59%, p<0.05) in BALF were found in animals pretreated with inhaled caspase-1 inhibitor compared with animals without therapy. Expression of iNOS in alveolar macrophages and COX-2 in lung tissue was concurrently decreased in the treatment groups compared with control animals. CONCLUSIONS: Our data demonstrate that administration of the caspase-1 inhibitor Ac-YVAD-CHO by inhalation is able to reduce the pulmonary and systemic release of proinflammatory mediators in rat endotoxaemia. These results further underscore that inhalation may constitute an effective route of anti-inflammatory drug administration, beneficial in the clinical setting of ARDS.

Desflurane differentially affects the release of proinflammatory cytokines in plasma and bronchoalveolar fluid of endotoxemic rats.

Previous studies have indicated that volatile anaesthetics can attenuate the inflammatory response to lipopolysaccharide (LPS) and other proinflammatory stimuli in vitro and in vivo. Thus far, no studies are available on the influences of desflurane on the cytokine-release. We therefore aimed to investigate the effects of desflurane on the systemic and pulmonary release of proinflammatory cytokines in endotoxemic rats. Eighteen anaesthetized and ventilated Sprague-Dawley rats were randomly assigned to the following groups: LPS-only: Six animals received LPS (5 mg/kg, i.v.) with no further intervention. LPS-Desflurane: Six animals received continuous inhalation of 1MAC Desflurane before and during endotoxemia with LPS (5 mg/kg, i.v.). Sham: Six animals served as control without inhalation of desflurane and endotoxemia. After 4 h, levels of tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta) and interleukin-6 (IL-6) in plasma and bronchoalveolar fluid were analyzed. Nitrite production as a readout for nitric oxide (NO) release from alveolar macrophages was measured by Griess assay. IkappaB-alpha degradation and iNOS-protein in macrophage homogenates were determined by Western Blotting. Inhalation of desflurane during endotoxemia showed a significant decrease in release of the proinflammatory cytokines TNF-alpha (-61%, P< or =0.05) and IL-1beta (-47%, P< or =0.05) in plasma as compared to LPS-only group, whereas the release of IL-6 was not significantly affected by desflurane. Within the lung, the NO-release was notably increased in supernatants of cultured alveolar macrophages from desflurane-group compared to both LPS-only and Sham group. IkappaB-alpha degradation in alveolar macrophages was impaired in the Desflurane-group as compared to the LPS-only group. Our data implicate that inhalation of 1MAC Desflurane during experimental endotoxemia differentially affects the inflammatory response in rats.

c-Met responsiveness of isolated hepatocytes evaluated in an in vitro de-differentiation model.

Hepatocyte growth factor (HGF) accelerates tissue regeneration and ameliorates tissue fibrosis through its ligand c-Met receptor tyrosine kinase. Hence, HGF is currently discussed as an attractive therapeutic candidate for fatal liver diseases. However, it remains unclear whether c-Met of de-differentiated hepatocytes adequately responds to HGF in an impaired liver. Therefore, we investigated c-Met expression and c-Met responsiveness to HGF in an experimental de-differentiation cell culture system. Primary rat hepatocytes were seeded on a two-dimensional collagen matrix or embedded within a three dimensional collagen gel to guarantee intact cell geometry. Cells were cultivated in a growth factor enriched extracellular milieu (de-differentiation medium), or in a chemically defined differentiation medium, representing physiologically intact hepatocytes. c-Met surface expression was determined by flow cytometry. Receptor localisation was examined by confocal microscopy, c-Met and phosphorylated c-Met protein were determined by western blotting. Hepatocyte-specific asialoglycoprotein receptor (ASGPr) was examined to control the differentiation status of the cells. Growth factor enriched milieu induced a rapid loss of ASGPr with a significant increase of c-Met surface level and a decrease in c-Met protein level. Surprisingly, the increased amount of c-Met surface expression was associated with its loss of responsiveness to HGF. The addition of bile acids into the culture medium had significantly delayed the process of de-differentiation and restrained the drastic elevation of c-Met (tauroursodeoxycholic acid > ursodeoxycholic acid). Application of the three-dimensional hepatocellular architecture stabilized the c-Met surface receptor level and rendered c-Met activation. We have demonstrated that growth factor enriched extracellular milieu and loss of intact liver architecture seems to be accompanied by an up-regulation of c-Met surface level. Our findings suggest that irresponsiveness of c-Met to soluble HGF was possibly caused by an excessive HGF production and receptor over-stimulation. Both events should be considered when establishing an HGF-based therapy for fibrosis/cirrhosis.

A brief exposure to isoflurane (50 s) significantly impacts on plasma cytokine levels in endotoxemic rats.

Induction of anesthesia by inhalation of isoflurane is a frequently used procedure in models of immunological diseases. Here we investigated effects of a brief exposure to isoflurane on cytokine production by endotoxemic rats. Anesthesia was either performed by pentobarbital/fentanyl without or accompanied by a 50-s inhalation pretreatment with isoflurane. After 4 h of endotoxemia, plasma levels of TNFalpha, IL-1beta, and RANTES were determined. Isoflurane significantly inhibited plasma levels of TNFalpha and IL-1beta by 69.3% and 61.8%, respectively. Levels of RANTES were similarly reduced by 43.1% (n.s.). Moreover, isoflurane significantly attenuated basal nitrite production by alveolar macrophages isolated from endotoxemic rats (by 59.4%). Thus, we confirm anti-inflammatory properties of isoflurane and beyond that clearly demonstrate that even a short exposure (<1 min) can profoundly affect pro-inflammatory parameters in experimental endotoxemia. These unforeseen observations suggest that short-term inhalation of isoflurane for induction of anesthesia may be an unsuitable procedure particularly in animal models of acute inflammation.

Controlled and reversible induction of differentiation and activation of adult human hepatocytes by a biphasic culture technique.

AIM: Clinical application of human hepatocytes (HC) is hampered by the progressive loss of growth and differentiation in vitro. The object of the study was to evaluate the effect of a biphasic culture technique on expression and activation of growth factor receptors and differentiation of human adult HC. METHODS: Isolated HC were sequentially cultured in a hormone enriched differentiation medium (DM) containing nicotinamide, insulin, transferrin, selenium, and dexame-thasone or activation medium (AM) containing hepatocyte growth factor (HGF), epidermal growth factor (EGF), and granulocyte-macrophage colony-stimulating factor (GM-CSF). Expression, distribution and activation of the HC receptors (MET and EGFR) and the pattern of characteristic cytokeratin (CK) filaments were measured by fluorometry, confocal microscopy and Western blotting. RESULTS: In the biphasic culture system, HC underwent repeated cycles of activation (characterized by expression and activation of growth factor receptors) and re-differentiation (illustrated by distribution of typical filaments CK-18 but low or absent expression of CK-19). In AM increased expression of MET and EGFR was associated with receptor translocation into the cytoplasm and induction of atypical CK-19. In DM low expression of MET and EGFR was localized on the cell membrane and CK-19 was reduced. Receptor phosphorylation required embedding of HC in collagen type I gel. CONCLUSION: Control and reversible modulation of growth factor receptor activation of mature human HC can be accomplished in vitro, when defined signals from the extracellular matrix and sequential growth stimuli are provided. The biphasic technique helps overcome de-differentiation, which occurs during continuous stimulation by means of growth factors.

Phosphorylation of hepatocyte growth factor receptor and epidermal growth factor receptor of human hepatocytes can be maintained in a (3D) collagen sandwich culture system.

In vitro culture models that employ human liver cells could be potent tools for predictive studies on drug toxicity and metabolism in the pharmaceutical industry. However, an adequate receptor responsiveness is necessary to allow intracellular signalling and metabolic activity. We tested the ability of three-dimensionally arranged human hepatocytes to respond to the growth factors hepatocyte growth factor (HGF) or epidermal growth factor (EGF). Isolated adult human hepatocytes were cultivated within a three-dimensional collagen gel (sandwich) or on a two-dimensional collagen matrix. Cells were treated with HGF or EGF and expression and phosphorylative activity of HGF receptors (HGFr, c-met) or EGF receptors (EGFr) were measured by flow cytometry and Western blot. Increasing HGFr and EGFr levels were detected in hepatocytes growing two-dimensionally. However, both receptors were not activated in presence of growth factors. In contrast, when hepatocytes were plated within a three-dimensional matrix, HGFr and EGFr levels remained constantly low. However, both receptors became strongly phosphorylated by soluble HGF or EGF. We conclude that cultivation of human hepatocytes in a three-dimensionally arranged in vitro system allows the maintenance of specific functional activities. The necessity of cell dimensionality for HGFr and EGFr function should be considered when an adequate in vitro system has to be introduced for drug testing.