Τίτλος:
Inhaled activated protein C protects mice from ventilator-induced lung injury
Γλώσσες Τεκμηρίου:
Αγγλικά
Περίληψη:
Introduction: Activated Protein C (APC), an endogenous anticoagulant, improves tissue microperfusion and endothelial cell survival in systemic inflammatory states such as sepsis, but intravenous administration may cause severe bleeding. We have thus addressed the role of APC delivered locally by inhalation in preventing acute lung injury from alveolar overdistention and the subsequent ventilator-induced lung injury (VILI). We also assessed the effects of APC on the activation status of Extracellular- Regulated Kinase 1/2 (ERK) pathway, which has been shown to be involved in regulating pulmonary responses to mechanical stretch.Methods: Inhaled APC (12.5 μg drotrecogin-α × 4 doses) or saline was given to tracheotomized C57/Bl6 mice starting 20 min prior to initiation of injurious mechanical ventilation with tidal volume 25 mL/Kg for 4 hours and then hourly thereafter; control groups receiving inhaled saline were ventilated with 8 mL/Kg for 30 min or 4 hr. We measured lung function (respiratory system elastance H), arterial blood gases, surrogates of vascular leak (broncho-alveolar lavage (BAL) total protein and angiotensin-converting enzyme (ACE)-activity), and parameters of inflammation (BAL neutrophils and lung tissue myeloperoxidase (MPO) activity). Morphological alterations induced by mechanical ventilation were examined in hematoxylin-eosin lung tissue sections. The activation status of ERK was probed in lung tissue homogenates by immunoblotting and in paraffin sections by immunohistochemistry. The effect of APC on ERK signaling downstream of the thrombin receptor was tested on A549 human lung epithelial cells by immunoblotting. Statistical analyses were performed using ANOVA with appropriate post-hoc testing.Results: In mice subjected to VILI without APC, we observed hypoxemia, increased respiratory system elastance and inflammation, assessed by BAL neutrophil counts and tissue MPO activity. BAL total protein levels and ACE activity were also elevated by VILI, indicating compromise of the alveolo-capillary barrier. In addition to preserving lung function, inhaled APC prevented endothelial barrier disruption and attenuated hypoxemia and the inflammatory response. Mechanistically, we found a strong activation of ERK in lung tissues by VILI, which was prevented by APC, suggestive of pathogenetic involvement of the Mitogen-Activated Kinase pathway. In cultured human lung epithelial cells challenged by thrombin, APC abrogated the activation of ERK and its downstream effector, cytosolic Phospholipase A2.Conclusions: Topical application of APC by inhalation may effectively reduce lung injury induced by mechanical ventilation in mice. © 2010 Maniatis et al.; licensee BioMed Central Ltd.
Συγγραφείς:
Maniatis, N.A.
Letsiou, E.
Orfanos, S.E.
Kardara, M.
Dimopoulou, I.
Nakos, G.
Lekka, M.E.
Roussos, C.
Armaganidis, A.
Kotanidou, A.
Περιοδικό:
Critical Care and Resuscitation
Λέξεις-κλειδιά:
activated protein C; cytosolic phospholipase A2; dipeptidyl carboxypeptidase; drotrecogin; eosin; hematoxylin; mitogen activated protein kinase 1; mitogen activated protein kinase 3; myeloperoxidase; sodium chloride; thrombin; thrombin receptor; anticoagulant agent; protein C, analysis of variance; animal cell; animal experiment; animal model; animal tissue; arterial gas; article; artificial ventilation; C57BL 6 mouse; competitive inhibition; controlled study; drug dose increase; drug effect; enzyme activation; enzyme activity; human; human cell; hypoxemia; immunoblotting; immunohistochemistry; inflammation; lung alveolus epithelium; lung compliance; lung function; lung lavage; lung parenchyma; male; molecular dynamics; mouse; neutrophil; neutrophil count; nonhuman; positive end expiratory pressure; post hoc analysis; priority journal; protection; regulatory mechanism; signal transduction; tidal volume; tracheotomy; ventilator induced lung injury; animal; C57BL mouse; dose response; inhalational drug administration; ventilator induced lung injury, Administration, Inhalation; Animals; Anticoagulants; Dose-Response Relationship, Drug; Male; Mice; Mice, Inbred C57BL; Protein C; Ventilator-Induced Lung Injury
