Hydrogen Sulfide Confers Lung Protection During Mechanical Ventilation via Cyclooxygenase 2, 15-deoxy Δ12,14-Prostaglandin J2, and Peroxisome Proliferator-Activated Receptor Gamma.

OBJECTIVES: Hydrogen sulfide reduces ventilator-induced lung injury in mice. Here, we have examined the underlying mechanisms of hydrogen sulfide-mediated lung protection and determined the involvement of cyclooxygenase 2, 15-deoxy Δ-prostaglandin J2, and peroxisome proliferator-activated receptor gamma in this response. DESIGN: Randomized, experimental study. SETTING: University medical center research laboratory. SUBJECTS: C57BL/6 mice and in vitro cell catheters. INTERVENTIONS: The effects of hydrogen sulfide were analyzed in a mouse ventilator-induced lung injury model in vivo as well as in a cell stretch model in vitro in the absence or presence of hydrogen sulfide. The physiologic relevance of our findings was confirmed using pharmacologic inhibitors of cyclooxygenase 2 and peroxisome proliferator-activated receptor gamma. MEASUREMENTS AND MAIN RESULTS: Mechanical ventilation caused significant lung inflammation and injury that was prevented in the presence of hydrogen sulfide. Hydrogen sulfide-mediated protection was associated with induction of cyclooxygenase 2 and increases of its product 15-deoxy Δ-prostaglandin J2 as well as cyclooxygenase 2/15-deoxy Δ-prostaglandin J2-dependent activation of peroxisome proliferator-activated receptor gamma. Hydrogen sulfide-dependent effects were mainly observed in macrophages. Applied mechanical stretch to RAW 264.7 macrophages resulted in increased expression of interleukin receptor 1 messenger RNA and release of macrophage inflammatory protein-2. In contrast, incubation of stretched macrophages with sodium hydrosulfide prevented the inflammatory response dependent on peroxisome proliferator-activated receptor gamma activity. Finally, application of a specific peroxisome proliferator-activated receptor gamma inhibitor abolished hydrogen sulfide-mediated protection in ventilated animals. CONCLUSIONS: One hydrogen sulfide-triggered mechanism in the protection against ventilator-induced lung injury involves cyclooxygenase 2/15-deoxy Δ-prostaglandin J2-dependent activation of peroxisome proliferator-activated receptor gamma and macrophage activity.

Inhaled Anesthetics Exert Different Protective Properties in a Mouse Model of Ventilator-Induced Lung Injury.

BACKGROUND: Mechanical ventilation is an important perioperative tool in anesthesia and a lifesaving treatment for respiratory failure, but it can lead to ventilator-associated lung injury. Inhaled anesthetics have demonstrated protective properties in various models of organ damage. We compared the lung-protective potential of inhaled sevoflurane, isoflurane, and desflurane in a mouse model of ventilator-induced lung injury (VILI). METHODS: C57BL/6N mice were randomized into 5 groups (n = 8/group). One group served as a control and 4 groups were subjected to mechanical ventilation with air (12 mL/kg tidal volume) for 6 hours. Ventilated animals were anesthetized with either ketamine and acepromazine, or 1 of 3 inhaled anesthetics: isoflurane, sevoflurane, or desflurane. Lung injury was assessed by lung histology, neutrophil counts, and interleukin-1ß concentrations in bronchoalveolar lavage fluid. Antioxidant effects were explored by evaluation of production of reactive oxygen species (ROS) and glutathione content in lung tissue by immunofluorescence staining and confocal laser scanning microscopy. Changes in intercellular adhesion molecule-1 and src-protein-tyrosine-kinase levels were determined by real-time polymerase chain reaction and Western blot. RESULTS: Compared with nonventilated controls, ventilated mice anesthetized with ketamine had thickened alveolar walls, elevated VILI scores, higher polymorph neutrophil counts, and increased ROS production. Mice anesthetized with isoflurane and sevoflurane showed thinner alveolar septa, lower VILI scores, lower polymorph neutrophil counts, and lower interleukin-1ß concentrations than ketamine mice. The expression of intercellular adhesion molecule-1/src-protein-tyrosine-kinase was neither affected by mechanical ventilation nor affected by administration of inhaled anesthetics. Mice anesthetized with isoflurane and sevoflurane showed less ROS production and higher glutathione contents compared with ketamine mice. Unexpectedly, desflurane-ventilated mice showed similar signs of lung injury compared with mice ventilated with air alone and receiving ketamine anesthesia. Desflurane failed to inhibit inflammatory responses and ROS production in lung tissue and developed no antioxidant potential. CONCLUSIONS: Although isoflurane and sevoflurane prevent ventilator-associated lung injury, desflurane does not. As an underlying mechanism, both inhaled anesthetics exert major anti-inflammatory and antioxidative effects.

Kinetic effects of carbon monoxide inhalation on tissue protection in ventilator-induced lung injury.

Mechanical ventilation causes ventilator-induced lung injury (VILI), and contributes to acute lung injury/acute respiratory distress syndrome (ALI/ARDS), a disease with high morbidity and mortality among critically ill patients. Carbon monoxide (CO) can confer lung protective effects during mechanical ventilation. This study investigates the time dependency of CO therapy with respect to lung protection in animals subjected to mechanical ventilation. For this purpose, mice were ventilated with a tidal volume of 12 ml/kg body weight for 6 h with air in the absence or presence of CO (250 parts per million). Histological analysis of lung tissue sections was used to determine alveolar wall thickening and the degree of lung damage by VILI score. Bronchoalveolar lavage fluid was analyzed for total cellular influx, neutrophil accumulation, and interleukin-1ß release. As the main results, mechanical ventilation induced pulmonary edema, cytokine release, and neutrophil recruitment. In contrast, application of CO for 6 h prevented VILI. Although CO application for 3 h followed by 3-h air ventilation failed to prevent lung injury, a further reduction of CO application time to 1 h in this setting provided sufficient protection. Pre-treatment of animals with inhaled CO for 1 h before ventilation showed no beneficial effect. Delayed application of CO beginning at 3 or 5 h after initiation of ventilation, reduced lung damage, total cell influx, and neutrophil accumulation. In conclusion, administration of CO for 6 h protected against VILI. Identical protective effects were achieved by limiting the administration of CO to the first hour of ventilation. Pre-treatment with CO had no impact on VILI. In contrast, delayed application of CO led to anti-inflammatory effects with time-dependent reduction in tissue protection.

The volatile anesthetic isoflurane prevents ventilator-induced lung injury via phosphoinositide 3-kinase/Akt signaling in mice.

BACKGROUND: Mechanical ventilation leads to ventilator-induced lung injury in animals, and can contribute to acute lung injury/acute respiratory distress syndrome in humans. Acute lung injury/acute respiratory distress syndrome currently causes an unacceptably high rate of morbidity and mortality among critically ill patients. Volatile anesthetics have been shown to exert anti-inflammatory and organ-protective effects in vivo. We investigated the effects of the volatile anesthetic isoflurane on lung injury during mechanical ventilation. METHODS: C57BL/6N mice were ventilated with a tidal volume of 12 mL/kg body weight for 6 hours in the absence or presence of isoflurane, and, in a second series, with or without the specific phosphoinositide 3-kinase/Akt inhibitor LY294002. Lung injury was determined by comparative histology, and by the isolation of bronchoalveolar lavage for differential cell counting and analysis of cytokine levels using enzyme-linked immunosorbent assays. Lung homogenates were analyzed for protein expression by Western blotting. RESULTS: Mechanical ventilation caused increases in alveolar wall thickening, cellular infiltration, and an elevated ventilator-induced lung injury score. Neutrophil influx and cytokine (i.e., interleukin-1ß, and macrophage inflammatory protein-2) release were enhanced in the bronchoalveolar lavage of ventilated mice. The expression levels of the stress proteins hemeoxygenase-1 and heat shock protein-70 were elevated in lung tissue homogenates. Isoflurane ventilation significantly reduced lung damage, inflammation, and stress protein expression. In contrast, phosphorylation of Akt protein was substantially increased during mechanical ventilation with isoflurane. Inhibition of phosphoinositide 3-kinase/Akt signaling before mechanical ventilation completely reversed the lung-protective effects of isoflurane treatment in vivo. CONCLUSIONS: Inhalation of isoflurane during mechanical ventilation protects against lung injury by preventing proinflammatory responses. This protection is mediated via phosphoinositide 3-kinase/Akt signaling.

Anesthetic considerations for the patient with liver disease.

PURPOSE OF REVIEW: An increasing number of patients requiring surgery are presenting with chronic or end stage liver disease. The management of these patients demands anesthesiologists with in-depth knowledge of the consequences of hepatic dysfunction, the effects on other organs, the risk of surgery, and the impact of anesthesia. RECENT FINDINGS: Chronic or end stage liver disease is associated with an increased risk of perioperative morbidity and mortality. It is essential to preoperatively assess possible hepatic encephalopathy, pleural effusions, hepatopulmonary syndrome, hepatopulmonary hypertension, hepatorenal syndrome, cirrhotic cardiomyopathy, and coagulation disorders. The application of two scoring systems, that is, Child-Turcotte-Pugh and model for end stage liver disease, helps to estimate the risk of surgery. The use of propofol is superior to benzodiazepines as intravenous narcotics. Although enflurane and halothane are discouraged for maintenance of anesthesia, all modern volatile anesthetics appear comparable with respect to outcome. Fentanyl, sufentanil, and remifentanil as opioids and cis-atracurium for relaxation may be the best choices in liver insufficency. Regional anesthesia is valuable for postoperative pain management. SUMMARY: Current studies have employed different anesthetic approaches in the preoperative and intraoperative management in order to improve outcomes of patients with liver disease.

Profiling Distinctive Inflammatory and Redox Responses to Hydrogen Sulfide in Stretched and Stimulated Lung Cells.

Hydrogen sulfide (H2S) protects against stretch-induced lung injury. However, the impact of H2S on individual cells or their crosstalk upon stretch remains unclear. Therefore, we addressed this issue in vitro using relevant lung cells. We have explored (i) the anti-inflammatory properties of H2S on epithelial (A549 and BEAS-2B), macrophage (RAW264.7) and endothelial (HUVEC) cells subjected to cycling mechanical stretch; (ii) the intercellular transduction of inflammation by co-culturing epithelial cells and macrophages (A549 and RAW264.7); (iii) the effect of H2S on neutrophils (Hoxb8) in transmigration (co-culture setup with HUVECs) and chemotaxis experiments. In stretched epithelial cells (A549, BEAS-2B), the release of interleukin-8 was not prevented by H2S treatment. However, H2S reduced macrophage inflammatory protein-2 (MIP-2) release from unstretched macrophages (RAW264.7) co-cultured with stretched epithelial cells. In stretched macrophages, H2S prevented MIP-2 release by limiting nicotinamide adenine dinucleotide phosphate oxidase-derived superoxide radicals (ROS). In endothelial cells (HUVEC), H2S inhibited interleukin-8 release and preserved endothelial integrity. In neutrophils (Hoxb8), H2S limited MIP-2-induced transmigration through endothelial monolayers, ROS formation and their chemotactic movement. H2S induces anti-inflammatory effects in a cell-type specific manner. H2S limits stretch- and/or paracrine-induced inflammatory response in endothelial, macrophage, and neutrophil cells by maintaining redox homeostasis as underlying mechanism.

Carbon monoxide releasing molecule-2 inhibits pancreatic stellate cell proliferation by activating p38 mitogen-activated protein kinase/heme oxygenase-1 signaling.

Proliferation of pancreatic stellate cells (PSCs) plays a cardinal role during fibrosis development. Therefore, the suppression of PSC growth represents a therapeutic option for the treatment of pancreatic fibrosis. It has been shown that up-regulation of the enzyme heme oxygenase-1 (HO-1) could exert antiproliferative effects on PSCs, but no information is available on the possible role of carbon monoxide (CO), a catalytic byproduct of the HO metabolism, in this process. In the present study, we have examined the effect of CO releasing molecule-2 (CORM-2) liberated CO on PSC proliferation and have elucidated the mechanisms involved. Using primary rat PSCs, we found that CORM-2 inhibited PSC proliferation at nontoxic concentrations by arresting cells at the G(0)/G(1) phase of the cell cycle. This effect was associated with activation of p38 mitogen-activated protein kinase (MAPK) signaling, induction of HO-1 protein, and up-regulation of the cell cycle inhibitor p21(Waf1/Cip1). The p38 MAPK inhibitor 4-(4-flurophenyl)-2-(4-methylsulfinylphenyl)-5-(4-pyridyl)imidazole (SB203580) abolished the inhibitory effect of CORM-2 on PSC proliferation and prevented both CORM-2-induced HO-1 and p21(Waf1/Cip1) up-regulation. Treatment with tin protoporphyrin IX, an HO inhibitor, or transfection of HO-1 small interfering RNA abolished the inductive effect of CORM-2 on p21(Waf1/Cip1) and reversed the suppressive effect of CORM-2 on PSC growth. The ability of CORM-2 to induce cell cycle arrest was abrogated in p21(Waf1/Cip1)-silenced cells. Taken together, our results suggest that CORM-2 inhibits PSC proliferation by activation of the p38/HO-1 pathway. These findings may indicate a therapeutic potential of CO carriers in the treatment of pancreatic fibrosis.

Inhaled hydrogen sulfide protects against ventilator-induced lung injury.

BACKGROUND: Mechanical ventilation still causes an unacceptably high rate of morbidity and mortality because of ventilator-induced lung injury (VILI). Therefore, new therapeutic strategies are needed to treat VILI. Hydrogen sulfide can induce hypothermia and suspended animation-like states in mice. Hydrogen sulfide can also confer antiinflammatory and antiapoptotic effects. This study investigates the organ-protective effects of inhaled hydrogen sulfide during mechanical ventilation. METHODS: Mice were ventilated with a tidal volume of 12 ml/kg body weight for 6 h with synthetic air in the absence or presence of hydrogen sulfide (80 parts per million) and, in a second series, at either mild hypothermia or normothermia. Staining of lung sections determined the degree of lung damage by VILI score and apoptotic cells. Bronchoalveolar lavage fluid was analyzed for the cytokines interleukin-1beta and macrophage inflammatory protein-1beta and for neutrophil accumulation. Heme oxygenase-1 and heat shock protein 70 expression were assessed in the lung tissue by Western immunoblot analysis. RESULTS: Mechanical ventilation at both hypothermia and normothermia led to a profound development of VILI, characterized by pulmonary edema, increased apoptosis, cytokine release, neutrophil recruitment, and up-regulation of the stress proteins such as heme oxygenase-1 and heat shock protein 70. In contrast, the application of hydrogen sulfide during ventilation at either mild hypothermia or normothermia prevented edema formation, apoptosis, proinflammatory cytokine production, neutrophil accumulation, and inhibited heme oxygenase-1 expression. CONCLUSIONS: Inhalation of hydrogen sulfide during mechanical ventilation protects against VILI by the inhibition of inflammatory and apoptotic responses. Hydrogen sulfide confers lung protection independently of its ability to induce mild hypothermia during ventilation.

Carbon monoxide prevents ventilator-induced lung injury via caveolin-1.

OBJECTIVES: Carbon monoxide (CO) can confer anti-inflammatory protection in rodent models of ventilator-induced lung injury (VILI). Caveolin-1 exerts a critical role in cellular responses to mechanical stress and has been shown to mediate cytoprotective effects of CO in vitro. We sought to determine the role of caveolin-1 in lung susceptibility to VILI in mice. Furthermore, we assessed the role of caveolin-1 in the tissue-protective effects of CO in the VILI model. DESIGN: Prospective experimental study. SETTING: University laboratory. SUBJECTS: Wild type (wt) and caveolin-1 deficient (cav-1) mice. INTERVENTIONS: Mice were subjected to tracheostomy and arterial cannulation. Wt and cav-1 mice were ventilated with a tidal volume of 12 mL/kg body weight and a frequency of 80/minute for 5 minutes as control or for 8 hours with air in the absence or presence of CO (250 parts per million). Bronchoalveolar lavage and histology were used to determine lung injury. Lung sections or homogenates were analyzed for caveolin-1 expression by immunohistochemical staining or Western blotting, respectively. MEASUREMENTS AND MAIN RESULTS: Ventilation led to an increase in bronchoalveolar lavage protein concentration, cell count, neutrophil recruitment, and edema formation, which was prevented in the presence of CO. Although ventilation alone slightly induced caveolin-1 expression in epithelial cells, the application of CO during the ventilation significantly increased the expression of caveolin-1. In comparison with wt mice, mechanical ventilation of cav-1 mice led to a significantly higher degree of lung injury when compared with wt mice. In contrast to its effectiveness in wt mice, CO administration failed to reduce lung-injury markers in cav-1 mice. CONCLUSIONS: Caveolin-1 null mice are more susceptible to VILI. CO executes lung-protective effects during mechanical ventilation that are dependent, in part, on caveolin-1 expression.

Carbon monoxide protects against ventilator-induced lung injury via PPAR-gamma and inhibition of Egr-1.

RATIONALE: Ventilator-induced lung injury (VILI) leads to an unacceptably high mortality. In this regard, the antiinflammatory properties of inhaled carbon monoxide (CO) may provide a therapeutic option. OBJECTIVES: This study explores the mechanisms of CO-dependent protection in a mouse model of VILI. METHODS: Mice were ventilated (12 ml/kg, 1-8 h) with air in the absence or presence of CO (250 ppm). Airway pressures, blood pressure, and blood gases were monitored. Lung tissue was analyzed for inflammation, injury, and gene expression. Bronchoalveolar lavage fluid was analyzed for protein, cell and neutrophil counts, and cytokines. MEASUREMENTS AND MAIN RESULTS: Mechanical ventilation caused significant lung injury reflected by increases in protein concentration, total cell and neutrophil counts in the bronchoalveolar lavage fluid, as well as the induction of heme oxygenase-1 and heat shock protein-70 in lung tissue. In contrast, CO application prevented lung injury during ventilation, inhibited stress-gene up-regulation, and decreased lung neutrophil infiltration. These effects were preceded by the inhibition of ventilation-induced cytokine and chemokine production. Furthermore, CO prevented the early ventilation-dependent up-regulation of early growth response-1 (Egr-1). Egr-1-deficient mice did not sustain lung injury after ventilation, relative to wild-type mice, suggesting that Egr-1 acts as a key proinflammatory regulator in VILI. Moreover, inhibition of peroxysome proliferator-activated receptor (PPAR)-gamma, an antiinflammatory nuclear regulator, by GW9662 abolished the protective effects of CO. CONCLUSIONS: Mechanical ventilation causes profound lung injury and inflammatory responses. CO treatment conferred protection in this model dependent on PPAR-gamma and inhibition of Egr-1.

Heme oxygenase-1 inhibits the proliferation of pancreatic stellate cells by repression of the extracellular signal-regulated kinase1/2 pathway.

Activation of pancreatic stellate cells (PSCs) is the key process in the development of pancreatic fibrosis, a common feature of chronic pancreatitis and pancreatic cancer. In recent studies, curcumin has been shown to inhibit PSC proliferation via an extracellular signal-regulated kinase (ERK)1/2-dependent mechanism. In addition, curcumin is a potent inducer of the cytoprotective enzyme heme oxygenase-1 (HO-1) in other cell types. Therefore, the aims of this study were to 1) characterize the effect of curcumin on HO-1 gene expression in PSCs, 2) explore whether HO-1 induction contributes to the inhibitory effect of curcumin on PSC proliferation, and 3) clarify the involvement of the mitogen-activated protein kinase (MAPK) family in this context. Cultured rat PSCs were incubated with curcumin and assessed for HO-1 up-regulation by Northern blot analysis, immunoblotting, and activity assays. The effect of HO-1 on platelet-derived growth factor (PDGF)-induced PSC proliferation and MAPK activation was determined by immunoblotting, cell proliferation assays, and cell count analyses. Curcumin induced HO-1 gene expression in PSCs in a time- and dose-dependent manner and inhibited PDGF-mediated ERK1/2 phosphorylation and PSC proliferation. These effects were blocked by treatment of PSCs with tin protoporphyrin IX, an HO inhibitor, or transfection of HO-1 small interfering RNA. Our data provide evidence that HO-1 induction contributes to the inhibitory effect of curcumin on PSC proliferation. Therefore, therapeutic up-regulation of HO-1 could represent a mode for inhibition of PSC proliferation and thus may provide a novel strategy in the prevention of pancreatic fibrosis.

[Persistent intractable hiccup in the perioperative period]. / Kasuistik--Unstillbarer Schluckauf beim Patienten in der perioperativen Phase.

We describe a case of hiccup in an awakening patient. Since there was no success in stopping the hiccup by deepening anaesthesia with Desflurane, we used Propofol 1.3 mg/kg BW as a short acting i.v. anaesthetic with a fast onset to provide early recovery after eliminating hiccup in the awakening patient. Recommendations for the therapy of hiccup range from breathing exercises to the implantation of a phrenic nerve stimulator. The small number of comparable patients and the lack of controlled studies prevent evidence-based recommendations for therapy. Currently patients profit mostly from the exchange of personal experiences.

Sevoflurane posttreatment prevents oxidative and inflammatory injury in ventilator-induced lung injury.

Mechanical ventilation is a life-saving clinical treatment but it can induce or aggravate lung injury. New therapeutic strategies, aimed at reducing the negative effects of mechanical ventilation such as excessive production of reactive oxygen species, release of pro-inflammatory cytokines, and transmigration as well as activation of neutrophil cells, are needed to improve the clinical outcome of ventilated patients. Though the inhaled anesthetic sevoflurane is known to exert organ-protective effects, little is known about the potential of sevoflurane therapy in ventilator-induced lung injury. This study focused on the effects of delayed sevoflurane application in mechanically ventilated C57BL/6N mice. Lung function, lung injury, oxidative stress, and inflammatory parameters were analyzed and compared between non-ventilated and ventilated groups with or without sevoflurane anesthesia. Mechanical ventilation led to a substantial induction of lung injury, reactive oxygen species production, pro-inflammatory cytokine release, and neutrophil influx. In contrast, sevoflurane posttreatment time dependently reduced histological signs of lung injury. Most interestingly, increased production of reactive oxygen species was clearly inhibited in all sevoflurane posttreatment groups. Likewise, the release of the pro-inflammatory cytokines interleukin-1ß and MIP-1ß and neutrophil transmigration were completely prevented by sevoflurane independent of the onset of sevoflurane administration. In conclusion, sevoflurane posttreatment time dependently limits lung injury, and oxidative and pro-inflammatory responses are clearly prevented by sevoflurane irrespective of the onset of posttreatment. These findings underline the therapeutic potential of sevoflurane treatment in ventilator-induced lung injury.

Hydrogen sulfide limits neutrophil transmigration, inflammation, and oxidative burst in lipopolysaccharide-induced acute lung injury.

Transmigration and activation of neutrophils in the lung reflect key steps in the progression of acute lung injury (ALI). It is known that hydrogen sulfide (H2S) can limit neutrophil activation, but the respective mechanisms remain elusive. Here, we aimed to examine the underlying pathways in pulmonary inflammation. In vivo, C57BL/6N mice received the H2S slow releasing compound GYY4137 prior to lipopolysaccharide (LPS) inhalation. LPS challenge led to pulmonary injury, inflammation, and neutrophil transmigration that were inhibited in response to H2S pretreatment. Moreover, H2S reduced mRNA expression of macrophage inflammatory protein-2 (MIP-2) and its receptor in lung tissue, as well as the accumulation of MIP-2 and interleukin-1ß in the alveolar space. In vitro, GYY4137 did not exert toxic effects on Hoxb8 neutrophils, but prevented their transmigration through an endothelial barrier in the presence and absence of MIP-2. In addition, the release of MIP-2 and reactive oxygen species from LPS-stimulated Hoxb8 neutrophils were directly inhibited by H2S. Taken together, we provide first evidence that H2S limits lung neutrophil sequestration upon LPS challenge. As proposed underlying mechanisms, H2S prevents neutrophil transmigration through the inflamed endothelium and directly inhibits pro-inflammatory as well as oxidative signalling in neutrophils. Subsequently, H2S pretreatment ameliorates LPS-induced ALI.

Hydrogen Sulfide Exerts Anti-oxidative and Anti-inflammatory Effects in Acute Lung Injury.

Acute lung injury (ALI) caused by septic stimuli is still a major problem in critical care patients. We have shown previously that hydrogen sulfide (H2S) mediates anti-inflammatory and lung protective effects. In the present study, we aimed to investigate the underlying mechanisms. C57BL/6N mice were instilled with lipopolysaccharide (LPS) intranasally in the absence or presence of inhaled H2S for 6 h. LPS instillation led to alveolar wall thickening, an elevated ALI score, increased neutrophil transmigration, and elevated interleukin-1ß cytokine release into the bronchoalveolar lavage fluid. In contrast, H2S inhalation prevented lung injury and inflammation despite LPS treatment. Moreover, H2S inhalation significantly inhibited protein expression of cystathionine-ß-synthetase, heat shock protein 70, phosphorylated p38 MAP kinase, NADPH oxidase 2, and the formation of reactive oxygen species (ROS) in LPS-challenged animals. In conclusion, H2S prevents LPS-induced ALI by inhibition of pro-inflammatory and oxidative responses via the concerted attenuation of stress protein, MAP kinase, and ROS signaling pathways.

Repression of T-cell function by thionamides is mediated by inhibition of the activator protein-1/nuclear factor of activated T-cells pathway and is associated with a common structure.

Treatment of hyperthyroidism by thionamides is associated with immunomodulatory effects, but the mechanism of thionamide-induced immunosuppression is unclear. Here we show that thionamides directly inhibit interleukin-2 cytokine expression, proliferation, and the activation (CD69 expression) of primary human T lymphocytes. Inhibition of immune function was associated with a repression of DNA binding of the cooperatively acting immunoregulatory transcription factors activator protein 1 (AP-1) and nuclear factor of activated T-cells (NFAT). Likewise, thionamides block the GTPase p21Ras, the mitogen-activated protein kinases, and impair the calcineurin/calmodulin-dependent NFAT dephosphorylation and nuclear translocation. The potency of inhibition correlated with the chemical reactivity of the thionamide-associated sulfur group. Taken together, our data demonstrate that thio-derivates with a common heterocyclic thioureylene-structure mediate a direct suppression of immune functions in T-cells via inhibition of the AP-1/NFAT pathway. Our observations may also explain the clinical and pathological resolution of some secondary, calcineurin, and mitogen-activated protein kinase-associated diseases upon thionamide treatment in hyperthyroid patients. This offers a new therapeutic basis for the development and application of heterocyclic thio-derivates.

The mitogen-activated protein kinase p38 regulates activator protein 1 by direct phosphorylation of c-Jun.

The involvement of p38 in fundamental physiological processes and the fact that deregulation often leads to disease indicates the potential impact of p38 dependent mechanisms. Here we demonstrate a new pathway that includes the induction of the mitogen activated protein kinase p38 by protein kinase C and results in a specific phosphorylation of c-Jun in T-lymphocytes. P38 directly phosphorylates c-Jun within its transactivation domain at serine 63 and serine 73 and thus posttranscriptionally affects the presence of DNA-bound phosphorylated c-Jun, a prerequisite for activator protein 1 dependent gene transcription. Moreover, DNA-binding activity of c-Fos, FosB, and JunB were also dependent on the p38 protein kinase activity, whereas JunD, Fra-1 and Fra-2 were not affected. Although we show that stress induced mitogen activated protein kinases share c-Jun as a substrate for phosphorylation, p38 mediated effects could not be rescued by the c-Jun N-terminal kinases. This demonstrates that the protein kinase p38 plays a unique and non-redundant role in posttranslational c-Jun regulation. The induction of a p38 dependent c-Jun phosphorylation was comparable in both CD4(+) and CD8(+) T-cells, proposing a ubiquitous pathway that is not linked to T-cell subtype and effector function. In contrast, ATF-2 was predominantly phosphorylated in CD8(+) T-cells. Different cell lines show p38-dependent c-Jun phosphorylation upon phorbol ester induction but there is evidence that the simian virus 40 large T-antigen may interfere with this pathway.

Carbon monoxide in sepsis.

Despite modern practices in critical care medicine, sepsis or systemic inflammatory response syndrome remains a leading cause of morbidity and mortality in the intensive care unit. Thus, the need to identify new therapeutic tools for the treatment of sepsis is urgent. In this context, carbon monoxide has become a promising therapeutic molecule that can potentially prevent uncontrolled inflammation in sepsis. In humans, carbon monoxide arises endogenously from the degradation of heme by heme oxygenase enzymes. Both endogenously synthesized and exogenously applied carbon monoxide can exert antiinflammatory and antiapoptotic effects in cells and tissues. Based on these properties, carbon monoxide, when applied at low concentration, conferred protection in a variety of cellular and rodent models of sepsis, and furthermore reduced morbidity and mortality in vivo. Therefore, application of carbon monoxide may have a major impact on the future of sepsis treatment. This review summarizes evidence for salutary effects of carbon monoxide in sepsis of various organs, including lung, heart, kidney, liver, and intestine, and discusses the potential translation of the data into human clinical trials.

Mechanisms of cell death in oxidative stress.

Reactive oxygen or nitrogen species (ROS/RNS) generated endogenously or in response to environmental stress have long been implicated in tissue injury in the context of a variety of disease states. ROS/RNS can cause cell death by nonphysiological (necrotic) or regulated pathways (apoptotic). The mechanisms by which ROS/RNS cause or regulate apoptosis typically include receptor activation, caspase activation, Bcl-2 family proteins, and mitochondrial dysfunction. Various protein kinase activities, including mitogen-activated protein kinases, protein kinases-B/C, inhibitor-of-I-kappaB kinases, and their corresponding phosphatases modulate the apoptotic program depending on cellular context. Recently, lipid-derived mediators have emerged as potential intermediates in the apoptosis pathway triggered by oxidants. Cell death mechanisms have been studied across a broad spectrum of models of oxidative stress, including H2O2, nitric oxide and derivatives, endotoxin-induced inflammation, photodynamic therapy, ultraviolet-A and ionizing radiations, and cigarette smoke. Additionally ROS generated in the lung and other organs as the result of high oxygen therapy or ischemia/reperfusion can stimulate cell death pathways associated with tissue damage. Cells have evolved numerous survival pathways to counter proapoptotic stimuli, which include activation of stress-related protein responses. Among these, the heme oxygenase-1/carbon monoxide system has emerged as a major intracellular antiapoptotic mechanism.

Pre- and posttreatment with hydrogen sulfide prevents ventilator-induced lung injury by limiting inflammation and oxidation.

Although essential in critical care medicine, mechanical ventilation often results in ventilator-induced lung injury. Low concentrations of hydrogen sulfide have been proven to have anti-inflammatory and anti-oxidative effects in the lung. The aim of this study was to analyze the kinetic effects of pre- and posttreatment with hydrogen sulfide in order to prevent lung injury as well as inflammatory and oxidative stress upon mechanical ventilation. Mice were either non-ventilated or mechanically ventilated with a tidal volume of 12 ml/kg for 6 h. Pretreated mice inhaled hydrogen sulfide in low dose for 1, 3, or 5 h prior to mechanical ventilation. Posttreated mice were ventilated with air followed by ventilation with hydrogen sulfide in various combinations. In addition, mice were ventilated with air for 10 h, or with air for 5 h and subsequently with hydrogen sulfide for 5 h. Histology, interleukin-1ß, neutrophil counts, and reactive oxygen species formation were examined in the lungs. Both pre-and posttreatment with hydrogen sulfide time-dependently reduced or even prevented edema formation, gross histological damage, neutrophil influx and reactive oxygen species production in the lung. These results were also observed in posttreatment, when the experimental time was extended and hydrogen sulfide administration started as late as after 5 h air ventilation. In conclusion, hydrogen sulfide exerts lung protection even when its application is limited to a short or delayed period. The observed lung protection is mediated by inhibition of inflammatory and oxidative signaling.