Hydrocortisone and the mitogen-activated protein kinase inhibitor U0126 acutely suppress reactive oxygen species generation from circulating granulocytes after gunshot injuries in the pig

Phosphorylation mechanisms in intensive care medicine

INTRODUCTION

The phosphorylation states of proteins, lipids, carbohydrates, amino acids, and nucleotides control the mechanisms behind nearly all cellular functions. Therefore, not surprisingly, recent findings have shown that alterations in these phosphorylation pathways play a central role in the development and progression of many disease states. This review provides a brief summary of the function and activity of various phosphorylation mechanisms, outlines some of the major phosphorylation signaling cascades, and describes the role of these phosphorylation mechanisms in intensive care medicine.

METHODS

This article will comprise a comprehensive review of the literature in the context of intensive care medicine. Specifically, we will discuss the involvement of phosphorylation in the pathogenesis, diagnosis, and treatment of heart failure, myocardial infarction, stroke, respiratory failure, ventilation-induced lung injury, traumatic brain injury, acute organ failure, systemic sepsis, and shock.

CONCLUSION

Phosphorylation mechanisms clearly play an important role in many pathologies and treatment strategies of intensive care and therefore further understanding of these mechanisms may lead to the development of novel therapies and improved patient care.

Early time course of altered leukocyte response to lipopolysaccharide and peptidoglycan in porcine gunshot injury

BACKGROUND

Penetrating injuries are frequently combined with polybacterial soiling. Clearance of the microorganisms depends on the ability to activate immune responses, but post-traumatic hyporeactivity of immune cells is almost universal. The aim of this study was to map the early time course of this altered leukocyte reactivity, and to compare the reactions to subsequent Gram-positive or Gram-negative challenges.

METHODS

Twelve juvenile pigs sustained two standardized rounds, one through the right femur and one through the left upper abdomen. First aid treatment and acute surgery were started immediately. Blood samples were drawn before trauma and after 10, 30, 60, and 90 min, and thereafter stimulated in ex vivo whole blood for 3 h with lipopolysaccharide (LPS, 10 ng/ml), peptidoglycan (PepG, 1 microg/ml), or an equivalent amount of normal saline. The leukocyte response was evaluated by measurement of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1 beta, IL-6, IL-8, and IL-10 in the supernatant.

RESULTS

In the post-traumatic in vivo serum, the concentration of TNF-alpha increased steadily (significant after 60 min). A reduced ex vivo reaction to LPS was evident after 10 min, and was statistically significant after 30 min. The lowest levels were reached after 90 min. The ex vivo synthesis of TNF-alpha after stimulation with PepG remained unaltered. A similar development was seen for IL-6. IL-1 beta levels did not change, while IL-8 increased significantly only after 60 and 90 min.

CONCLUSIONS

Trauma almost instantaneously reprogrammed circulating leukocytes. As measured with TNF-alpha, a profound hyporeactivity to LPS, but not to PepG, was induced. In addition, no global down-regulation of leukocyte function was found after stimulation with LPS.

Budesonide reduces superoxide and peroxynitrite anion chemiluminescence during human neutrophil bursts

Many lung disorders are characterized by airway inflammation involving the recruitment of inflammatory cells, and leading to the release of oxidant and inflammatory mediators. The overproduction of superoxide anion (O(2)(*-)) and nitric oxide (NO) during the respiratory bursts of neutrophils leads to production of peroxynitrite, a highly damaging oxidant with an important role in the inflammatory loop causing airway hyper-reactivity in respiratory diseases like asthma. The aim of this study was to investigate in vitro the effects of a 1-hour incubation with budesonide at 2.5 x 10(-7), 5 x 10(-7), 1 x 10(-6), 2 x 10(-6) and 4 x 10(-6) mol/l on O(2)(*-), NO, and peroxynitrite production during the respiratory burst of human neutrophils stimulated by N-formyl-methionyl-leucyl-phenylalanine (fMLP, 5 x 10(-7) mol/l) or phorbol 12-myristate 13-acetate (PMA, 2 x 10(-6) mol/l), as documented by luminol-amplified chemiluminescence (LACL). In absence of L-arginine, budesonide (5 x 10(-7) to 4 x 10(-6) mol/l) dose-dependently reduced both fMLP- and PMA-induced LACL (18.3-50.6%). In the presence of L-arginine (100 microg/ml), a NO donor increasing peroxynitrite production, LACL increased 3-5 times compared with baseline, but budesonide dose-dependently reduced LACL (25.5-59.6%). Mifepristone (4 x 10(-6) mol/l), a glucocorticoid receptor antagonist, inhibited the effect of budesonide on LACL, thus confirming that budesonide reacts with glucocorticoid receptors to exert an antioxidant activity. These results suggest that budesonide target rapidly human neutrophils leading to a fast reduction in both NO and peroxynitrite production, and are consistent with decrease in exhaled NO levels after treatment with budesonide in patients with asthma.

Response of circulating immune cells to major gunshot injury, haemorrhage, and acute surgery

PURPOSE

The purpose of this study was to use an established porcine model to investigate the effects on immune function of severe gunshot injury.

METHODS

Twelve pigs sustained two standardised rounds, one through right femur and one through left upper abdomen. First aid treatment and acute surgery was started immediately. Blood samples were drawn before shooting and after 75 min. Circulating neutrophils were isolated and reactive oxygen species (ROS) measured. Serum levels of tumour necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), IL-6, and IL-10 were determined at 0, 75 min, as well as 2h after incubation with 1 microg/ml endotoxin in an ex vivo whole blood model.

RESULTS

TNF-alpha, IL-1beta, and IL-6 significantly increased at 75 min. ROS in circulating granulocytes tended to increase (NS). Incubation with endotoxin led to a more than 100-fold increase of TNF-alpha pre-trauma, compared to a three-fold increase post-trauma (p<0.0001 between groups). A similar pattern was obtained for IL-1beta, and IL-6. IL-10 was below detection in all samples. The granulocytes maintained their ability to react to the protein kinase C activator phorbol myristate acetate (PMA) after trauma.

CONCLUSION

Severe gunshot injury and peritraumatic stress rapidly activate circulating immune cells, but reduce their capacity to react to a subsequent challenge to endotoxin.

A combination of budesonide and the SH-metabolite I of erdosteine acts synergistically in reducing chemiluminescence during human neutrophil respiratory burst

Activated neutrophils can release superoxide anion and nitric oxide (NO), which subsequently combine with each other to yield peroxynitrite anions, powerful and harmful oxidants that preferentially mediate the oxidation of the thiol groups in proteins and non-protein molecules. These oxidants play a direct role in the inflammatory process in chronic obstructive pulmonary disease and asthma by increasing the number of neutrophils and macrophages that induce a self-sustaining phlogogenic loop. Budesonide (BUD) and erdosteine (a muco-active drug which, after metabolization, produces an active metabolite (Met I) with a sulfhydryl group) are both active in reducing the release of superoxide anion, NO and peroxynitrite, and can be administered to patients with respiratory diseases. The aim of this study was to investigate the possible synergistic in vitro effect of BUD and Met I on chemiluminescence generation during fMLP-stimulated respiratory bursts of human neutrophils with the NO donor L-arginine, added to the incubating medium. The investigated BUD concentrations ranged from 6 x 10(-8) to 1 x 10(-6) mol/l in logarithmic scale and a significant and progressive reduction in luminol-amplified chemiluminescence (LACL) was observed at concentrations ranging from 2.5 x 10(-7) to 1 x 10(-6) mol/l. The investigated concentrations of Met I varied from 0.62 to 10 microg/ml. No significant changes were observed at 0.62, 1.25, and 2.5 microg/ml, but a significant decrease in LACL was observed at 5 and 10 microg/ml. When the two drugs were combined, there was a greater significant decrease in LACL versus the single drugs with the combinations of BUD 1 x 10(-6) mol/l plus Met I 10 microg/ml, BUD 5 x 10(-7) mol/l plus Met I 5 microg/ml, BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml, and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml. A further interesting finding was that the combination of BUD 2.5 x 10(-7) mol/l plus Met I 2.5 microg/ml and BUD 1.25 x 10(-7) mol/l plus Met I 1.25 microg/ml significantly decreased LACL, whereas the single concentrations had no significant effect, thus indicating the possibility of extending the duration of the effect. Our findings indicate a synergistic antioxidant effect when BUD and Met I are given together, which is of interest for counteracting the airway phlogosis involved in many respiratory diseases.

Modest protection of early hydrocortisone treatment in a rat model of volume-controlled haemorrhage

BACKGROUND

Major insults may trigger generalized inflammatory responses that contribute to progressive multiple organ dysfunction. The present study was performed to test the potential of early hydrocortisone treatment to influence these responses as well as organ function following an episode of rapid and profound blood loss.

METHODS

In isoflurane anaesthesia, 35 spontaneously breathing male Sprague-Dawley rats were bled 2.5 ml 100 g-1 body weight over 10 min. Immediately following withdrawal of blood, one group (n = 17) was given 2 mg of hydrocortisone, and the other (n = 18) had the same amount of normal saline. Seventy-five minutes after initiation of bleeding, two-thirds of the blood was retransfused, together with a new injection of hydrocortisone or saline. Thereafter the rats were observed for 2 h. Key mediators of systemic inflammation and plasma markers of organ function and integrity were measured. Internal organs were weighed and scored for visible pathology. Leukocyte infiltration of the liver was counted in a light microscope.

RESULTS

Hydrocortisone reduced the plasma levels of IL-6 (P < 0.05); non-significant reductions of TNF-alpha (P = 0.12) and IL-10 (P = 0.44) were noted. The synthesis of reactive oxygen species in peritoneal cells was unaffected. Relative organ weights and organ injury scores tended to be reduced, but only wet organ weight for the lungs reached statistical significance. Leukocyte infiltration of the liver was equal in both groups. Plasma levels of ALT, AST, alpha-GST and creatinine did not differ significantly between groups. Two of the hydrocortisone treated rats died compared with four controls.

CONCLUSION

Early treatment with hydrocortisone had a limited organ protective effect in this model of controlled haemorrhagic shock. Although a general tendency for better outcome in the hydrocortisone group was noted, clear-cut and significant advantages of the treatment were not obtained.