Regulation of Endotoxin Tolerance and Compensatory Anti-inflammatory Response Syndrome by Non-coding RNAs

The onset and the termination of innate immune response must be tightly regulated to maintain homeostasis and prevent excessive inflammation, which can be detrimental to the organism, particularly in the context of sepsis. Endotoxin tolerance and compensatory anti-inflammatory response syndrome (CARS) describe a state of hypo-responsiveness characterized by reduced capacity of myeloid cells to respond to inflammatory stimuli, particularly those initiated by bacterial lipopolysaccharide (LPS). To achieve endotoxin tolerance, extensive reprogramming otherwise termed as “innate immune training”, is required that leads to both modifications of the intracellular components of TLR signaling and also to alterations in extracellular soluble mediators. Non-coding RNAs (ncRNAs) have been recognized as critical regulators of TLR signaling. Specifically, several microRNAs (miR-146, miR-125b, miR-98, miR-579, miR-132, let-7e and others) are induced upon TLR activation and reciprocally promote endotoxin tolerance and/or cross tolerance. Many other miRNAs have been also shown to negatively regulate TLR signaling. The long non-coding (lnc)RNAs (Mirt2, THRIL, MALAT1, lincRNA-21 and others) are also altered upon TLR activation and negatively regulate TLR signaling. Furthermore, the promotion or termination of myeloid cell tolerance is not only regulated by intracellular mediators but is also affected by other TLR-independent soluble signals that often achieve their effect via modulation of intracellular ncRNAs. In this article, we review recent evidence on the role of different ncRNAs in the context of innate immune cell tolerance and trained immunity, and evaluate their impact on immune system homeostasis

The potential of real-time analytics to improve care for mechanically ventilated patients in the intensive care unit

__Background:__ Mechanical ventilation services are an important driver of the high costs of intensive care. An optimal interaction between a patient and a ventilator is therefore paramount. Suboptimal interaction is present when patients repeatedly demand,

Uncoupling of IL-6 signaling and LC3-associated phagocytosis drives immunoparalysis during sepsis

Contains fulltext : 238107.pdf (Publisher’s version ) (Closed access)Immune deactivation of phagocytes is a central event in the pathogenesis of sepsis. Herein, we identify a master regulatory role of IL-6 signaling on LC3-associated phagocytosis (LAP) and reveal that uncoupling of these two processes during sepsis induces immunoparalysis in monocytes/macrophages. In particular, we demonstrate that activation of LAP by the human fungal pathogen Aspergillus fumigatus depends on ERK1/2-mediated phosphorylation of p47phox subunit of NADPH oxidase. Physiologically, autocrine IL-6/JAK2/Ninein axis orchestrates microtubule organization and dynamics regulating ERK recruitment to the phagosome and LC3(+) phagosome (LAPosome) formation. In sepsis, loss of IL-6 signaling specifically abrogates microtubule-mediated trafficking of ERK, leading to defective activation of LAP and impaired killing of bacterial and fungal pathogens by monocytes/macrophages, which can be selectively restored by IL-6 supplementation. Our work uncovers a molecular pathway linking IL-6 signaling with LAP and provides insight into the mechanisms underlying immunoparalysis in sepsis

Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

INTRODUCTION: Mechanical ventilation (MV) of mice is increasingly required in experimental studies, but the conditions that allow stable ventilation of mice over several hours have not yet been fully defined. In addition, most previous studies documented vital parameters and lung mechanics only incompletely. The aim of the present study was to establish experimental conditions that keep these parameters within their physiological range over a period of 6 h. For this purpose, we also examined the effects of frequent short recruitment manoeuvres (RM) in healthy mice. METHODS: Mice were ventilated at low tidal volume V(T) = 8 mL/kg or high tidal volume V(T) = 16 mL/kg and a positive end-expiratory pressure (PEEP) of 2 or 6 cm H(2)O. RM were performed every 5 min, 60 min or not at all. Lung mechanics were followed by the forced oscillation technique. Blood pressure (BP), electrocardiogram (ECG), heart frequency (HF), oxygen saturation and body temperature were monitored. Blood gases, neutrophil-recruitment, microvascular permeability and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and blood serum as well as histopathology of the lung were examined. RESULTS: MV with repetitive RM every 5 min resulted in stable respiratory mechanics. Ventilation without RM worsened lung mechanics due to alveolar collapse, leading to impaired gas exchange. HF and BP were affected by anaesthesia, but not by ventilation. Microvascular permeability was highest in atelectatic lungs, whereas neutrophil-recruitment and structural changes were strongest in lungs ventilated with high tidal volume. The cytokines IL-6 and KC, but neither TNF nor IP-10, were elevated in the BAL and serum of all ventilated mice and were reduced by recurrent RM. Lung mechanics, oxygenation and pulmonary inflammation were improved by increased PEEP. CONCLUSIONS: Recurrent RM maintain lung mechanics in their physiological range during low tidal volume ventilation of healthy mice by preventing atelectasis and reduce the development of pulmonary inflammation

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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MicroRNA and mRNA expression profiling in rat acute respiratory distress syndrome

Background: Acute respiratory distress syndrome (ARDS) is characterized by pulmonary epithelial injury and extensive inflammation of the pulmonary parenchyma. Systematic analyses of microRNA (miRNA) and mRNA expression profiling in ARDS provide insights into understanding of molecular mechanisms of the pathogenesis of ARDS. The objective of this study was to identify miRNA and mRNA interactions in a rat model of ARDS by combining miRNA and mRNA microarray analyses.Methods: Rat model of ARDS was induced by saline lavage and mechanical ventilation. The expression profiles of both mRNAs and miRNAs in rat ARDS model were performed by microarray analyses. Microarray data were further verified by quantitative RT-PCR. Functional annotation on dys-regulated mRNAs and miRNAs was carried out by bioinformatics analysis.Results: The expression of 27 miRNAs and 37 mRNAs were found to be significantly changed. The selected miRNAs and genes were further verified by quantitative real-time PCR. The down-regulated miRNAs included miR-24, miR-26a, miR-126, and Let-7a, b, c, f. The up-regulated miRNAs were composed of miR-344, miR-346, miR-99a, miR-127, miR-128b, miR-135b, and miR-30a/b. Gene ontology and functional annotation analyses indicated that up-regulated mRNAs, such as Apc, Timp1, and Sod2, were involved in the regulation of apoptosis. Bioinformatics analysis showed the inverse correlation of altered miRNAs with the expression of their predicted target mRNAs. While Sod2 was inversely correlated with Let-7a, b, c, f., Ebf1 and Apc were inversely correlated with miR-24 and miR-26a, respectively. miR-26a, miR-346, miR-135b, miR-30a/b, miR-344, and miR-18a targeted multiple altered mRNAs. Gabrb1, Sod2, Eif2ak1, Fbln5, and Tspan8 were targeted by multiple altered miRNAs.Conclusion: The expressions of miRNAs and mRNAs were altered in a rat model of ARDS. The identified miRNA-mRNA pairs may play critical roles in the pathogenesis of ARDS.Peer reviewedPathobiologyOklahoma Center for Respiratory and Infectious DiseasesPhysiological Science

Effect of hypoxia and hypercapnia on acute lung injury and contribution of TNF-a

Είναι γνωστό ότι τα κυψελιδικά επιθηλιακά κύτταρα τύπου ΙΙ παίζουν βασικό ρόλο σε παθολογικές καταστάσεις του πνεύμονα, κατά τις οποίες συχνά εκτίθενται σε συνθήκες υποξίας και υπερκαπνίας. Στο πρώτο μέρος αυτής της μελέτης εξετάσαμε την επίδραση της υποξίας και της υπερκαπνίας στη λειτουργία και ομοιόσταση των κυψελιδικών επιθηλιακών κυττάρων τύπου ΙΙ. Συγκεκριμένα εξετάσαμε την ικανότητα των κυττάρων για παραγωγή πρωτεϊνών του επιφανειοδραστικού παράγοντα και διαπιστώσαμε ότι η υποξία προκαλεί καταστολή της παραγωγής της πρωτεΐνης C του επιφανειοδραστικού παράγοντα μετά από έκθεση λίγων ωρών ενώ η υπερκαπνία μόνο μετά από πιο μακροχρόνια έκθεση έχει κατασταλτική δράση. Επίσης διαπιστώσαμε ότι η προφλεγμονώδης κυτταροκίνη TNFα μερικώς αναστέλλει αυτό το φαινόμενο. Επιπλέον εξετάσαμε την επίδραση της υποξίας και της υπερκαπνίας στην ικανότητα των κυττάρων για πολλαπλασιασμό και στην εμφάνιση αποπτωτικού θανάτου. Διαπιστώσαμε ότι η υποξία και όχι η υπερκαπνία επάγει απόπτωση και αναστολή του κυτταρικού πολλαπλασιασμού στα κυψελιδικά επιθηλιακά κύτταρα τύπου ΙΙ. Είναι γνωστό ότι ο μηχανικός αερισμός μπορεί να προκαλέσει βλάβη στον πνεύμονα που αποφεύγεται με τον περιορισμό του αναπνεόμενου όγκου. Θεωρείται πιθανό η χαμηλή αναπνευστική συχνότητα να είναι επίσης προστατευτική, αλλά η ασφάλεια της υπερκαπνίας στην οποία αναπόφευκτα θα οδηγήσει δεν έχει εξακριβωθεί. Στο πρώτο μέρος της μελέτης διαπιστώθηκε ότι η έκθεση των επιθηλιακών κυττάρων του πνεύμονα σε συνθήκες υπερκαπνίας είναι σχετικά ασφαλής. Έτσι στο δεύτερο μέρος της μελέτης εξετάσθηκε η επίδραση της χαμηλής συχνότητας του μηχανικού αερισμού στην εμφάνιση βλάβης πνεύμονα από μηχανικό αερισμό. Διαπιστώθηκε ότι η χαμηλή αναπνευστική συχνότητα έχει προστατευτικό ρόλο καθώς ελαττώνει δείκτες φλεγμονής στο βρογχοκυψελιδικό έκπλυμα, και συνοδεύεται από μικρότερη βλάβη ιστολογικά. Ο ΤΝFα δεν βρέθηκε να επηρεάζεται από τις συνθήκες αερισμού που μελετήθηκαν. Επίσης διαπιστώθηκε ότι ο μηχανικός αερισμός με χαμηλή συχνότητα σχετίζεται με επαγωγή προαποπτοτικών και καταστολή αντιαποπτωτικών πρωτεϊνών σε αντίθεση με τον συμβατικό μηχανικό αερισμό, όπως είναι γνωστό ότι συμβαίνει και σε προστατευτικό μηχανικό αερισμό με χαμηλό αναπνεόμενο όγκο. Συμπερασματικά, η παρούσα μελέτη έδειξε ότι in vitro η υποξία επηρεάζει σημαντικά την παραγωγή του επιφανειοδραστικού παράγοντα C, τον πολλαπλασιασμό και την απόπτωση επιθηλιακών κυττάρων του πνεύμονα ενώ η υπερκαπνία και ο ΤΝFα δεν έχουν τέτοια επίδραση. Επίσης διαπιστώθηκε in vivo ότι η αναπνευστική συχνότητα του μηχανικού αερισμού επηρεάζει την εμφάνιση βλάβης πνεύμονα χωρίς όμως τη συμμετοχή του TNFα