Surviving Sepsis Campaign: international guidelines for management of severe sepsis and septic shock: 2008.

OBJECTIVE: To provide an update to the original Surviving Sepsis Campaign clinical management guidelines, "Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock," published in 2004. DESIGN: Modified Delphi method with a consensus conference of 55 international experts, several subsequent meetings of subgroups and key individuals, teleconferences, and electronic-based discussion among subgroups and among the entire committee. This process was conducted independently of any industry funding. METHODS: We used the GRADE system to guide assessment of quality of evidence from high (A) to very low (D) and to determine the strength of recommendations. A strong recommendation indicates that an intervention's desirable effects clearly outweigh its undesirable effects (risk, burden, cost), or clearly do not. Weak recommendations indicate that the tradeoff between desirable and undesirable effects is less clear. The grade of strong or weak is considered of greater clinical importance than a difference in letter level of quality of evidence. In areas without complete agreement, a formal process of resolution was developed and applied. Recommendations are grouped into those directly targeting severe sepsis, recommendations targeting general care of the critically ill patient that are considered high priority in severe sepsis, and pediatric considerations. RESULTS: Key recommendations, listed by category, include: early goal-directed resuscitation of the septic patient during the first 6 hrs after recognition (1C); blood cultures prior to antibiotic therapy (1C); imaging studies performed promptly to confirm potential source of infection (1C); administration of broad-spectrum antibiotic therapy within 1 hr of diagnosis of septic shock (1B) and severe sepsis without septic shock (1D); reassessment of antibiotic therapy with microbiology and clinical data to narrow coverage, when appropriate (1C); a usual 7-10 days of antibiotic therapy guided by clinical response (1D); source control with attention to the balance of risks and benefits of the chosen method (1C); administration of either crystalloid or colloid fluid resuscitation (1B); fluid challenge to restore mean circulating filling pressure (1C); reduction in rate of fluid administration with rising filing pressures and no improvement in tissue perfusion (1D); vasopressor preference for norepinephrine or dopamine to maintain an initial target of mean arterial pressure > or = 65 mm Hg (1C); dobutamine inotropic therapy when cardiac output remains low despite fluid resuscitation and combined inotropic/vasopressor therapy (1C); stress-dose steroid therapy given only in septic shock after blood pressure is identified to be poorly responsive to fluid and vasopressor therapy (2C); recombinant activated protein C in patients with severe sepsis and clinical assessment of high risk for death (2B except 2C for post-operative patients). In the absence of tissue hypoperfusion, coronary artery disease, or acute hemorrhage, target a hemoglobin of 7-9 g/dL (1B); a low tidal volume (1B) and limitation of inspiratory plateau pressure strategy (1C) for acute lung injury (ALI)/acute respiratory distress syndrome (ARDS); application of at least a minimal amount of positive end-expiratory pressure in acute lung injury (1C); head of bed elevation in mechanically ventilated patients unless contraindicated (1B); avoiding routine use of pulmonary artery catheters in ALI/ARDS (1A); to decrease days of mechanical ventilation and ICU length of stay, a conservative fluid strategy for patients with established ALI/ARDS who are not in shock (1C); protocols for weaning and sedation/analgesia (1B); using either intermittent bolus sedation or continuous infusion sedation with daily interruptions or lightening (1B); avoidance of neuromuscular blockers, if at all possible (1B); institution of glycemic control (1B) targeting a blood glucose < 150 mg/dL after initial stabilization ( 2C ); equivalency of continuous veno-veno hemofiltration or intermittent hemodialysis (2B); prophylaxis for deep vein thrombosis (1A); use of stress ulcer prophylaxis to prevent upper GI bleeding using H2 blockers (1A) or proton pump inhibitors (1B); and consideration of limitation of support where appropriate (1D). Recommendations specific to pediatric severe sepsis include: greater use of physical examination therapeutic end points (2C); dopamine as the first drug of choice for hypotension (2C); steroids only in children with suspected or proven adrenal insufficiency (2C); a recommendation against the use of recombinant activated protein C in children (1B). CONCLUSION: There was strong agreement among a large cohort of international experts regarding many level 1 recommendations for the best current care of patients with severe sepsis. Evidenced-based recommendations regarding the acute management of sepsis and septic shock are the first step toward improved outcomes for this important group of critically ill patients.

Lung fluid movements in hypoxia.

Pulmonary edema is a problem of major clinical importance resulting from a persistent imbalance between forces that drive water into the airspace of the lung and the biological mechanisms for its removal. Here, we will first review the fundamental mechanisms implicated in the regulation of lung fluid homeostasis, namely, the Starling forces and the respiratory transepithelial sodium transport. Second, we will discuss the contribution of hypoxia to the perturbation of this fine balance and the role of such perturbations in the development of high-altitude pulmonary edema, a disease characterized by a very high morbidity and mortality. Finally, we will review possible interventions aimed to maintain/restore lung fluid homeostasis and their importance for the prevention/treatment of pulmonary edema.

Effects of paralysis with pancuronium bromide on joint mobility in premature infants.

To study the effects of muscle paralysis on joint mobility, we compared eight premature infants treated with pancuronium bromide with a control group. A significant reduction was observed in hip and knee flexion, and in ankle dorsal extension, which tended to resolve in time. We conclude that muscle paralysis reduces the mobility of selected joints; spontaneous activity appears to prevent long-term contractures.

Surfactant palmitoylmyristoylphosphatidylcholine is a marker for alveolar size during disease.

Two common lung-related complications in the neonate are respiratory distress syndrome, which is associated with a failure to generate low surface tension at the air-liquid interface because of pulmonary surfactant insufficiency, and bronchopulmonary dysplasia (BPD), a chronic lung injury with reduced alveolarization. Surfactant phosphatidylcholine (PC) molecular species composition during alveolarization has not been examined. Mass spectrometry analysis of bronchoalveolar lavage fluid of rodents and humans revealed significant changes in surfactant PC during alveolar development and BPD. In rats, total PC content rose during alveolarization, which was caused by an increase in palmitoylmyristoyl-PC (16:0/14:0PC) concentration. Furthermore, two animal models of BPD exhibited a specific reduction in 16:0/14:0PC content. In humans, 16:0/14:0PC content was specifically decreased in patients with BPD and emphysema compared with patients without alveolar pathology. Palmitoylmyristoyl-PC content increased with increasing intrinsic surfactant curvature, suggesting that it affects surfactant function in the septating lung. The changes in acyl composition of PC were attributed to type II cells producing an altered surfactant during alveolar development. These data are compatible with extracellular surfactant 16:0/14:0PC content being an indicator of alveolar architecture of the lung.

La douleur prolongée chez le nouveau-né: étude de cas [Prolonged pain in neonates: retrospective analysis].

INTRODUCTION: infants hospitalised in neonatology are inevitably exposed to pain repeatedly. Premature infants are particularly vulnerable, because they are hypersensitive to pain and demonstrate diminished behavioural responses to pain. They are therefore at risk of developing short and long-term complications if pain remains untreated. CONTEXT: compared to acute pain, there is limited evidence in the literature on prolonged pain in infants. However, the prevalence is reported between 20 and 40 %. OBJECTIVE : this single case study aimed to identify the bio-contextual characteristics of neonates who experienced prolonged pain. METHODS : this study was carried out in the neonatal unit of a tertiary referral centre in Western Switzerland. A retrospective data analysis of seven infants' profile, who experienced prolonged pain ,was performed using five different data sources. RESULTS : the mean gestational age of the seven infants was 32weeks. The main diagnosis included prematurity and respiratory distress syndrome. The total observations (N=55) showed that the participants had in average 21.8 (SD 6.9) painful procedures that were estimated to be of moderate to severe intensity each day. Out of the 164 recorded pain scores (2.9 pain assessment/day/infant), 14.6 % confirmed acute pain. Out of those experiencing acute pain, analgesia was given in 16.6 % of them and 79.1 % received no analgesia. CONCLUSION: this study highlighted the difficulty in managing pain in neonates who are exposed to numerous painful procedures. Pain in this population remains underevaluated and as a result undertreated.Results of this study showed that nursing documentation related to pain assessment is not systematic.Regular assessment and documentation of acute and prolonged pain are recommended. This could be achieved with clear guidelines on the Assessment Intervention Reassessment (AIR) cyclewith validated measures adapted to neonates. The adequacy of pain assessment is a pre-requisite for appropriate pain relief in neonates.

Successful bilateral lung transplantation after previous pneumonectomy

Objective: To present the feasibility of bilateral lung transplantation after previously performed pneumonectomy.Methods: A 32 years old women underwent right pneumonectomy for bronchiectasis-related destroyed lung. Eight months later, she developed a vascular post-pneumonectomy syndrome and underwent realigning of the mediastinum by an intrathoracic expander that was complicated by an adult respiratory distress syndrome of the left lung requiring mechanical ventilation, arterio-venous CO2 removal (Novalung) and finally bilateral lung transplantation. Via clamshell incision, the post-pneumonectomy cavity was dissected and the superior vena cava (SVC) and carina were exposed. The pulmonary vessel stumps were dissected intrapericardically after realization of a right-sided hemi-pericardectomy. Extracorporeal circulation was started after central cannulation of the aorta and the inferior vena cava. A right upper lobe sleeve resection of the donor lung was performed. The intermediate bronchus was then implanted in the dissected recipient carina after realization of a hilar release maneuver. The right pulmonary artery was clamped between SVC andthe ascending aorta followed by end -to-end anastomosis of the donor and recipient artery and left atrial cuffs, respectively. Satisfactory graft function allowed decanulation and standard transplantation of the left lung without extracorporeal circulation.Results: Bronchoscopy and trans-esophageal echocardiography demonstrated a patent airway and vascular anastomoses without stenosis. Follow-up revealed excellent gas exchanges, no airway complications and well-functioning grafts on both sides with right-sided ventilation and perfusion two months after transplantation of 37% and 22%, respectively.Conclusion: This is to our knowledge the first report of successful bilateral lung transplantation after previous pneumonectomy unrelated to transplantation.

Moderate hypercapnia exerts beneficial effects on splanchnic energy metabolism during endotoxemia.

PURPOSE: Low tidal volume ventilation and permissive hypercapnia are required in patients with sepsis complicated by ARDS. The effects of hypercapnia on tissue oxidative metabolism in this setting are unknown. We therefore determined the effects of moderate hypercapnia on markers of systemic and splanchnic oxidative metabolism in an animal model of endotoxemia. METHODS: Anesthetized rats maintained at a PaCO(2) of 30, 40 or 60 mmHg were challenged with endotoxin. A control group (PaCO(2) 40 mmHg) received isotonic saline. Hemodynamic variables, arterial lactate, pyruvate, and ketone bodies were measured at baseline and after 4 h. Tissue adenosine triphosphate (ATP) and lactate were measured in the small intestine and the liver after 4 h. RESULTS: Endotoxin resulted in low cardiac output, increased lactate/pyruvate ratio and decreased ketone body ratio. These changes were not influenced by hypercapnia, but were more severe with hypocapnia. In the liver, ATP decreased and lactate increased independently from PaCO(2) after endotoxin. In contrast, the drop of ATP and the rise in lactate triggered by endotoxin in the intestine were prevented by hypercapnia. CONCLUSIONS: During endotoxemia in rats, moderate hypercapnia prevents the deterioration of tissue energetics in the intestine.

Is pulse oximetry reliable in detecting hyperoxemia in the neonate?

We tested the hypothesis that hyperoxemia defined as arterial PO2 above 12 kPa can be detected by pulse oximetry using 95% oxygen saturation as the upper limit. Thirty artificially ventilated neonates with an indwelling arterial catheter were studied registrating transcutaneous oxygen saturation (Ohmeda Biox 3700 Pulse Oximeter) and transcutaneous PO2 continuously during a 4-hour period and measuring arterial oxygen saturation and PO2 intermittently. 46 episodes of arterial hyperoxemia were observed. Pulse oximetry had a sensitivity of 30%, detecting 14 of these 46 hyperoxemic episodes, and a specificity of 93%. The accuracy for separating hyperoxemia from normoxemia by pulse oximetry could be improved by shifting the cut-off point from 95% to 92%. With this optimal cut-off point sensitivity was 70% and specificity 62%. We conclude that pulse oximetry is not reliable for detection of hyperoxemia.

A prospective, randomized, and controlled study of fluid management in children with severe head injury: lactated Ringer's solution versus hypertonic saline.

OBJECTIVES: Resuscitation in severe head injury may be detrimental when given with hypotonic fluids. We evaluated the effects of lactated Ringer's solution (sodium 131 mmol/L, 277 mOsm/L) compared with hypertonic saline (sodium 268 mmol/L, 598 mOsm/L) in severely head-injured children over the first 3 days after injury. DESIGN: An open, randomized, and prospective study. SETTING: A 16-bed pediatric intensive care unit (ICU) (level III) at a university children's hospital. PATIENTS: A total of 35 consecutive children with head injury. INTERVENTIONS: Thirty-two children with Glasgow Coma Scores of <8 were randomly assigned to receive either lactated Ringer's solution (group 1) or hypertonic saline (group 2). Routine care was standardized, and included the following: head positioning at 30 degrees; normothermia (96.8 degrees to 98.6 degrees F [36 degrees to 37 degrees C]); analgesia and sedation with morphine (10 to 30 microg/kg/hr), midazolam (0.2 to 0.3 mg/kg/hr), and phenobarbital; volume-controlled ventilation (PaCO2 of 26.3 to 30 torr [3.5 to 4 kPa]); and optimal oxygenation (PaO2 of 90 to 105 torr [12 to 14 kPa], oxygen saturation of >92%, and hematocrit of >0.30). MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure and intracranial pressure (ICP) were monitored continuously and documented hourly and at every intervention. The means of every 4-hr period were calculated and serum sodium concentrations were measured at the same time. An ICP of 15 mm Hg was treated with a predefined sequence of interventions, and complications were documented. There was no difference with respect to age, male/female ratio, or initial Glasgow Coma Score. In both groups, there was an inverse correlation between serum sodium concentration and ICP (group 1: r = -.13, r2 = .02, p < .03; group 2: r = -.29, r2 = .08, p < .001) that disappeared in group 1 and increased in group 2 (group 1: r = -.08, r2 = .01, NS; group 2: r = -.35, r2 =.12, p < .001). Correlation between serum sodium concentration and cerebral perfusion pressure (CPP) became significant in group 2 after 8 hrs of treatment (r = .2, r2 = .04, p = .002). Over time, ICP and CPP did not significantly differ between the groups. However, to keep ICP at <15 mm Hg, group 2 patients required significantly fewer interventions (p < .02). Group 1 patients received less sodium (8.0 +/- 4.5 vs. 11.5 +/- 5.0 mmol/kg/day, p = .05) and more fluid on day 1 (2850 +/- 1480 vs. 2180 +/- 770 mL/m2, p = .05). They also had a higher frequency of acute respiratory distress syndrome (four vs. 0 patients, p = .1) and more than two complications (six vs. 1 patient, p = .09). Group 2 patients had significantly shorter ICU stay times (11.6 +/- 6.1 vs. 8.0 +/- 2.4 days; p = .04) and shorter mechanical ventilation times (9.5 +/- 6.0 vs. 6.9 +/- 2.2 days; p = .1). The survival rate and duration of hospital stay were similar in both groups. CONCLUSIONS: Treatment of severe head injury with hypertonic saline is superior to that treatment with lactated Ringer's solution. An increase in serum sodium concentrations significantly correlates with lower ICP and higher CPP. Children treated with hypertonic saline require fewer interventions, have fewer complications, and stay a shorter time in the ICU.

Stress oxydant chez l'enfant prématuré : causes, biomarqueurs et possibilités thérapeutiques [Oxidative stress after preterm birth: Origins, biomarkers, and possible therapeutic approaches].

The survival of preterm babies has increased over the last few decades. However, disorders associated with preterm birth, known as oxygen radical diseases of neonatology, such as retinopathy, bronchopulmonary dysplasia, periventricular leukomalacia, and necrotizing enterocolitis are severe complications related to oxidative stress, which can be defined by an imbalance between oxidative reactive species production and antioxidant defenses. Oxidative stress causes lipid, protein, and DNA damage. Preterm infants have decreased antioxidant defenses in response to oxidative challenges, because the physiologic increase of antioxidant capacity occurs at the end of gestation in preparation for the transition to extrauterine life. Therefore, preterm infants are more sensitive to neonatal oxidative stress, notably when supplemental oxygen is being delivered. Furthermore, despite recent advances in the management of neonatal respiratory distress syndrome, controversies persist concerning the oxygenation saturation targets that should be used in caring for preterm babies. Identification of adequate biomarkers of oxidative stress in preterm infants such as 8-iso-prostaglandin F2α, and adduction of malondialdehyde to hemoglobin is important to promote specific therapeutic approaches. At present, no therapeutic strategy has been validated as prevention or treatment against oxidative stress. Breastfeeding should be considered as the main measure to improve the antioxidant status of preterm infants. In the last few years, melatonin has emerged as a protective molecule against oxidative stress, with antioxidant and free-radical scavenger roles, in experimental and preliminary human studies, giving hope that it can be used in preterm infants in the near future.

Role of gelatinases MMP-2 and MMP-9 in tissue remodeling following acute lung injury

Acute lung injury is characterized by a severe disruption of alveolo-capillary structures and includes a variety of changes in lung cell populations. Evidence suggests the occurrence of rupture of the basement membranes and interstitial matrix remodeling during acute lung injury. The dynamic equilibrium of the extracellular matrix (ECM) under physiological conditions is a consequence of the balance between the regulation of synthesis and degradation of ECM components. Matrix metalloproteinases (MMPs) represent a group of enzymes involved in the degradation of most of the components of the ECM and therefore participate in tissue remodeling associated with pathological situations such as acute lung injury. MMP activity is regulated by proteolytic activation of the latent secreted proenzyme and by interaction with specific tissue inhibitors of metalloproteinases. This review details our knowledge of the involvement of MMPs, namely MMP-2 and MMP-9, in acute lung injury and acute respiratory distress syndrome.

Connections: can the 20th century coronary heart disease epidemic reveal something about the 1918 influenza lethality?

This essay proposes that the ecologic association shown between the 20th century coronary heart disease epidemic and the 1918 influenza pandemic could shed light on the mechanism associated with the high lethality of the latter. It suggests that an autoimmune interference at the apoB-LDL interface could explain both hypercholesterolemia and inflammation (through interference with the cellular metabolism of arachidonic acid). Autoimmune inflammation, then, would explain the 1950s-60s acute coronary events (coronary thrombosis upon influenza re-infection) and the respiratory failure seen among young adults in 1918. This hypothesis also argues that the lethality of the 1918 pandemic may have not depended so much on the 1918 virus as on an immune vulnerability to it, possibly resulting from an earlier priming of cohorts born around 1890 by the 1890 influenza pandemic virus.

Glomerular filtration is reduced by high tidal volume ventilation in an in vivo healthy rat model

Mechanical ventilation has been associated with organ failure in patients with acute respiratory distress syndrome. The present study examines the effects of tidal volume (V T) on renal function using two V T values (8 and 27 mL/kg) in anesthetized, paralyzed and mechanically ventilated male Wistar rats. Animals were randomized into two groups of 6 rats each: V T8 (V T, 8 mL/kg; 61.50 ± 0.92 breaths/min; positive end-expiratory pressure, 3.0 cmH2O; peak airway pressure (PAW), 11.8 ± 2.0 cmH2O), and V T27 (V T, 27 mL/kg; 33.60 ± 1.56 breaths/min; positive end-expiratory pressure, none, and PAW, 22.7 ± 4.0 cmH2O). Throughout the experiment, mean PAW remained comparable between the two groups (6.33 ± 0.21 vs 6.50 ± 0.22 cmH2O). For rats in the V T27 group, inulin clearance (mL·min-1·body weight-1) decreased acutely after 60 min of mechanical ventilation and even more significantly after 90 min, compared with baseline values (0.60 ± 0.05 and 0.45 ± 0.05 vs 0.95 ± 0.07; P < 0.001), although there were no differences between groups in mean arterial pressure or gasometric variables. In the V T8 group, inulin clearance at 120 min of mechanical ventilation remained unchanged in relation to baseline values (0.72 ± 0.03 vs 0.80 ± 0.05). The V T8 and V T27 groups did not differ in terms of serum thiobarbituric acid reactive substances (3.97 ± 0.27 vs 4.02 ± 0.45 nmol/mL) or endothelial nitric oxide synthase expression (94.25 ± 2.75 vs 96.25 ± 2.39%). Our results show that glomerular filtration is acutely affected by high tidal volume ventilation but do not provide information about the mechanism.

Étude multicentrique sur les stratégies de ventilation mécanique employées chez les enfants avec un œdème pulmonaire lésionnel

Des études adultes sur l’œdème pulmonaire lésionnel et le Syndrome de Détresse Respiratoire Aiguë ont mené à l’établissement de recommandations sur les stratégies de ventilation mécanique à employer chez ces patients. Cependant, il n’est pas clair si les recommandations adultes sont également bénéfiques pour l’enfant. Objectif Décrire les stratégies de ventilation mécanique employées chez les enfants atteints d’un œdème pulmonaire lésionnel. Méthodes Étude épidémiologique transversale tenue dans 59 unités de Soins Intensifs Pédiatriques de 12 pays en Amérique du Nord et en Europe. Six jours d’étude ont eu lieu entre juin et novembre 2007. Les enfants atteints d’un œdème pulmonaire lésionnel étaient inclus et des données sur la sévérité de leur maladie, les paramètres de ventilation mécanique et les thérapies adjuvantes employées ont été recueillies. Résultats Des 3823 enfants dépistés, 414 (10.8%) avaient un œdème pulmonaire lésionnel et 165 (40%) ont été inclus dans l’étude (124 étaient sous ventilation mécanique conventionnelle, 27 sous ventilation à haute fréquence par oscillation et 14 sous ventilation non invasive). Dans le groupe sous ventilation conventionnelle, 43.5% étaient ventilés avec un mode contrôlé à pression, le volume courant moyen était de 8.3±3.3 ml/kg et l’utilisation de la PEP et FiO2 était hétérogène. Conclusions Cette étude démontre une hétérogénéité dans les stratégies de ventilation mécanique employées chez les enfants souffrant d’un œdème pulmonaire lésionnel. Celle-ci pourrait être en partie reliée à la robustesse des critères diagnostiques actuellement utilisés pour définir l’ALI/SDRA. Une évaluation rigoureuse de ces stratégies est nécessaire pour guider la standardisation des soins et optimiser l’issue de ces patients.

Modulation de la stabilité de l'ARNm alphaENaC dans les cellules épithéliales alvéolaires : détermination du rôle des séquences 3' non traduites

Le transport actif de sodium par les cellules épithéliales alvéolaires est le principal mécanisme impliqué dans la régulation du niveau de liquide dans le poumon distal. Le canal épithélial sodique (ENaC) exprimé par les cellules épithéliales alvéolaires est essentiel à la résorption du liquide des poumons à la naissance ainsi que la résolution de l'œdème pulmonaire chez l'adulte. L'activité et l'expression du canal ENaC sont modulées par de nombreux stress pathophysiologiques. L'inflammation pulmonaire constitue un facteur important dans l'inhibition de l'expression du canal ENaC et pourrait favoriser la formation d'œdème pulmonaire. Nous avons précédemment démontré que différentes cytokines pro-inflammatoires, ainsi que les lipopolysaccharides (LPS) de Pseudomonas aeruginosa, inhibent l'expression de l'ARNm αENaC par des mécanismes de régulation transcriptionnelle et post-transcriptionnelle. Ces résultats suggèrent que les mécanismes qui modulent la stabilité des ARNm αENaC pourraient jouer un rôle important dans la régulation du niveau d’expression du transcrit en condition inflammatoire. Le principal objectif de mes travaux était de caractériser les mécanismes de modulation de l’ARNm αENaC dans les cellules épithéliales alvéolaires lors de différents stress pathophysiologiques et déterminer si cette modulation pouvait s’expliquer en partie par une régulation de la stabilité du transcrit. Mes travaux montrent que les LPS et la cycloheximide inhibent l’expression de l’ARNm αENaC de façon similaire via l’activation des voies de signalisation des MAPK ERK1/2 et p38. Cependant, les mécanismes de modulation de l’expression de l'ARNm αENaC sont différents puisque les LPS répriment la transcription du gène, alors que la cycloheximide diminuerait la stabilité du transcrit via des mécanismes post-transcriptionnels impliquant la région 3' non traduite (3'UTR) de l'ARNm αENaC. Pour mieux étudier le rôle du 3'UTR dans ce processus, nous avons développé un modèle Tet-Off nous permettant de mesurer la demi-vie de l’ARNm αENaC indépendamment de l’utilisation d’un inhibiteur de la transcription comme l'actinomycine D (Act. D). Nous avons montré que la demi-vie de l’ARNm αENaC était de 100min, un temps beaucoup plus court que celui rapporté dans la littérature. Nous avons démontré que l’Act. D a un effet stabilisateur important sur l’ARNm αENaC et qu’il ne peut être utilisé pour évaluer la stabilité du transcrit. À l’aide de différents mutants de délétion, nous avons entrepris de déterminer la nature des régions du 3’UTR impliquées dans la modulation de la stabilité du transcrit. Nous avons trouvé que le 3’UTR joue un rôle à la fois de stabilisation (région 3’UTR proximale) et de déstabilisation (région 3’UTR distale) du transcrit. Notre système nous a finalement permis de confirmer que la diminution de l’ARNm αENaC observée en présence de TNF-α s’expliquait en partie par une diminution importante de la stabilité du transcrit induite par cette cytokine. Enfin, nous avons identifié la nature des protéines pouvant se lier au 3’UTR de l’ARNm αENaC et déterminé lesquelles pouvaient moduler la stabilité du transcrit. Des trois protéines candidates trouvées, nous avons confirmé que la surexpression de DHX36 et TIAL1 diminue le niveau de transcrit par un mécanisme impliquant la stabilité du messager. Les travaux présentés ici montrent la complexité des voies de signalisation induites par différents stress sur les cellules épithéliales alvéolaires et montrent comment la stabilité de l’ARNm αENaC et en particulier, les séquences du 3’UTR jouent un rôle important dans la modulation du niveau de transcrit. Le modèle Tet-Off que nous avons développé permet d’estimer le temps de demi-vie réel de l’ARNm αENaC et montre que le 3’UTR du messager joue un rôle complexe dans la stabilisation du messager en condition de base ainsi qu’en condition pro-inflammatoire. Enfin, nous avons identifié deux protéines liant l’ARNm qui pourraient jouer un rôle important dans la modulation de la stabilité du transcrit.