Mécanismes de Modulation par PAI-1 et aPC de l Oedeme Pulmonaire induit par le Pseudomonas aeruginosa

Une coagulopathie aigue endogène (EAC) est présente chez 25% des patients de traumatologie dès leur arrivée. Des résultats d études récentes montrent que cette EAC est liée à l activation de la voie de la protéine C (aPC). Quelques heures après, se développe un état pro-coagulant associant un niveau abaissé d aPC et un taux plasmatique élevé de l inhibiteur de l activateur du plasminogene (PAI-1). Nous trouvons que l incidence des pneumopathies associées à la ventilation est significativement augmentée chez ces patients sans toutefois connaître le rôle exact de ces anomalies de coagulation. Basé sur cette hypothèse central de susceptibilité augmentée a l infection et plus particulièrement aux pneumopathie a P.aeruginosa (PA) le but de ce travail est d identifier les mécanismes par lesquels PAI-1 et aPC peuvent moduler la perméabilité de la barrière alveolo capillaire et ceci a travers 3 objectifs spécifiques1 Objectif 1: déterminer les mécanismes par lequel PA augmente la perméabilité endothéliale. 2 Objectif 2: déterminer le rôle d aPC dans la modulation des effets de PA sur l œdème pulmonaire lésionnel.3 Objectif 3: déterminer le rôle de PAI-1 dans la modulation des effets de PA sur l œdème pulmonaire lésionnel.En utilisant un inhibiteur spécifique des petites GTPases nous démontrons le rôle centrale joué par RhoA dans le développement de l œdème pulmonaire induit par PA. PAI-1 et aPC sont impliquées dans le mécanisme lésionnel pulmonaire. aPC et l inhibition de la voie du RhoA attenue le développement de l œdème pulmonaire et diminue la dissémination systémique bactérienne. Cependant le blocage invivo de la voie de PAI-1 est associé à une surmortalité et à une augmentation de la charge bactérienne suggérant un rôle de PAI-1 dans l activation de la réponse inflammatoire nécessaire a l éradication de PAA clinically significant acute endogenous coagulopathy (EAC) is present in 25% of major trauma patients upon arrival in the emergency department, before any fluid resuscitation. Results from recent clinical studies indicate that EAC is primarily caused by the activation of the anticoagulant protein C pathway. Several hours later, there is the development of a systemic procoagulant activity associated with low plasma levels of activated protein C (aPC) and an inhibition of the fibrinolysis caused by elevated plasma levels of plasminogen activator inhibitor 1 (PAI-1). We have found that the incidence of ventilator-associated pneumonia (VAP) is significantly increased in trauma patients with these coagulation abnormalities [6, 9]. However, whether these coagulation abnormalities play a mechanistic role in the increased susceptibility to nosocomial lung infection observed after severe posttraumatic hemorrhage is unknown. Thus, the central hypothesis is that the increased susceptibility to P. aeruginosa (PA) pneumonia following severe trauma with tissue hypoperfusion is mediated in part by these posttraumatic coagulation abnormalities within the airspaces of the lung. Specifically, in this work, we will identify through 3 specific aims the mechanisms by which PAI-1 and aPC modulate PA mediated increase in alveolar-capillary barrier permeability.1 - Specific Aim 1: To determine the mechanisms by which PA increases lung endothelial permeability.2 - Specific Aim 2 : To determine the Role of aPC in modulating the effect of PA on the lung endothelial barrier function3 - Specific Aim 3 : To determine the Role of PAI-1 in modulating the effect of PA on the lung endothelial barrier functionIn the present work, we demonstrated the central role small GTPases RhoA plays in the increase of permeability induced by pseudomonas infection. PAI-1 and aPC are deeply involved in the control of early lung inflammation. aPC and inhibition of the RhoA pathway attenuates the development of pulmonary edema and decrease in the systemic dissemination of P. aeruginosa. However, in vivo disruption of PAI-1 signalling is associated with higher mortality at 24 h and significant increase in the bacterial burden suggesting that PAI-1 is required for the activation of the innate immune response necessary for the eradication of PA from the distal airspaces of the lungBORDEAUX2-Bib. électronique (335229905) / SudocSudocFranceF

Vascular Smooth Muscle Modulates Endothelial Control of Vasoreactivity via Reactive Oxygen Species Production through Myoendothelial Communications

BACKGROUND: Endothelial control of vascular smooth muscle plays a major role in the resulting vasoreactivity implicated in physiological or pathological circulatory processes. However, a comprehensive understanding of endothelial (EC)/smooth muscle cells (SMC) crosstalk is far from complete. Here, we have examined the role of gap junctions and reactive oxygen species (ROS) in this crosstalk and we demonstrate an active contribution of SMC to endothelial control of vasomotor tone. METHODOLOGY/PRINCIPAL FINDINGS: In small intrapulmonary arteries, quantitative RT-PCR, Western Blot analyses and immunofluorescent labeling evidenced connexin (Cx) 37, 40 and 43 in EC and/or SMC. Functional experiments showed that the Cx-mimetic peptide targeted against Cx 37 and Cx 43 ((37,43)Gap27) (1) reduced contractile and calcium responses to serotonin (5-HT) simultaneously recorded in pulmonary arteries and (2) abolished the diffusion in SMC of carboxyfluorescein-AM loaded in EC. Similarly, contractile and calcium responses to 5-HT were decreased by superoxide dismutase and catalase which, catabolise superoxide anion and H(2)O(2), respectively. Both Cx- and ROS-mediated effects on the responses to 5-HT were reversed by L-NAME, a NO synthase inhibitor or endothelium removal. Electronic paramagnetic resonance directly demonstrated that 5-HT-induced superoxide anion production originated from the SMC. Finally, whereas 5-HT increased NO production, it also decreased cyclic GMP content in isolated intact arteries. CONCLUSIONS/SIGNIFICANCE: These data demonstrate that agonist-induced ROS production in SMC targeting EC via myoendothelial gap junctions reduces endothelial NO-dependent control of pulmonary vasoreactivity. Such SMC modulation of endothelial control may represent a signaling pathway controlling vasoreactivity under not only physiological but also pathological conditions that often implicate excessive ROS production

0169 : Segregated calcium stores are important for stretch-induced calcium signaling in smooth muscle cells: Implication in pulmonary hypertension

Pulmonary arterial smooth muscle cells (PASMC) are submitted to stretch forces exerted by the blood pressure. They can transduce a mechanical stimulus of stretch into a biological response of contraction, a mechanism called myogenic tone which involves Ca2+ influx through stretch-activated channels (SAC). We investigate how the subcellular organization of Ca2+ stores in PASMC (sarcoplasmic reticulum (SR), lysosomes and mitochondria) is important for the Ca2+ response to stretch during PH.Studies were performed in freshly isolated PASMC from control rats and rats with a pulmonary hypertension induced by an injection of monocrotaline (MCT). Inward currents from SAC were recorded after a negative pressure applied by a patch-clamp pipette. Cytosolic Ca2+ was also measured with the fluo4 probe and mitochondrial Ca2+ with the rhod2 probe after an osmotic shock. A pharmacological approach coupled with different coimmunolabelings of ryanodine receptors (RyR) and SERCA2 pumps was used to investigate which RyR subtype is involved in Ca2+ response to stretch.PASMC exhibit segregated Ca2+ stores: a subplasmalemnal SR store with RyR1 and SERCA2b, associated to mitochondria and a perinuclear SR store with RyR3 and SERCA2a. We showed that a stretch of PASMC induces an inward Ca2+ influx through SAC that is amplified by a Ca2+ release by RyR1, which is buffered by mitochondria. In MCT rats, the subcellular organization of RyR subtypes is modified: RyR3 and SERCA2a are not only expressed in a perinuclear area but also in a subplasmalemnal level. This is correlated with a different organization of mitochondria. In MCT rats, this new organisation leads to a greater amplification by all RyR subtypes and to a higher Ca2+ increase induced by stretch. Furthermore, the Ca2+ response to stretch is enhanced by a mechanism independent on extracellular Ca2+, involving caveolae.The spatial organization of Ca2+ stores in PASMC is important for cell signaling and plays a causal role in PH

Positive early-late life-history trait correlations in elephant seals

Correlations between early- and late-life performance are a major prediction of life-history theory. Negative early–late correlations can emerge because biological processes are optimized for early but not late life (e.g., rapid development may accelerate the onset of senescence; “developmental theory of aging”) or because allocation to early-life performance comes at a cost in terms of late-life performance (as in the disposable soma theory). But variation in genetic and environmental challenges that each individual has to cope with during early life may also lead to positive early–late life-history trait correlations (the “fixed heterogeneity” or “individual quality” hypothesis). We analyzed individual life-history trajectories of 7,420 known-age female southern elephant seals (Mirounga leonina) monitored over 36 yr to determine how actuarial senescence (a proxy for late-life performance) correlate with age at first reproduction (a proxy for early-life performance). As some breeding events may not be detected in this field study, we used a custom “multievent” hierarchical model to estimate the age at first reproduction and correlate it to other life-history traits. The probability of first reproduction was 0.34 at age 3, with most females breeding for the first time at age 4, and comparatively few at older ages. Females with an early age of first reproduction outperformed delayed breeders in all aspects we considered (survival, rate of senescence, net reproductive output) but one: early breeders appeared to have an onset of actuarial senescence 1 yr earlier compared to late breeders. Genetics and environmental conditions during early life likely explain the positive correlation between early- and late-life performance. Our results provide the first evidence of actuarial senescence in female southern elephant seals.The South African National Research Foundation (NRF)http://www.esajournals.org/loi/ecolam2022Mammal Research InstituteZoology and Entomolog

Chronic hypoxia aggravates monocrotaline-induced pulmonary arterial hypertension: a rodent relevant model to the human severe form of the disease

International audienc

Impairment of NO-Dependent Relaxation in Intralobar Pulmonary Arteries: Comparison of Urban Particulate Matter and Manufactured Nanoparticles

International audienceBACKGROUND AND OBJECTIVES: Because pulmonary circulation is the primary vascular target of inhaled particulate matter (PM), and nitric oxide is a major vasculoprotective agent, in this study we investigated the effect of various particles on the NO-cyclic guanosine monophosphate (cGMP) pathway in pulmonary arteries. METHODS: We used intrapulmonary arteries and/or endothelial cells, either exposed in vitro to particles or removed from PM-instilled animals for assessment of vasomotricity, cGMP and reactive oxygen species (ROS) levels, and cytokine/chemokine release. RESULTS: Endothelial NO-dependent relaxation and cGMP accumulation induced by acetylcholine (ACh) were both decreased after 24 hr exposure of rat intrapulmonary arteries to standard reference material 1648 (SRM1648; urban PM). Relaxation due to NO donors was also decreased by SRM1648, whereas responsiveness to cGMP analogue remained unaffected. Unlike SRM1648, ultrafine carbon black and ultrafine and fine titanium dioxide (TiO2) manufactured particles did not impair NO-mediated relaxation. SRM1648-induced decrease in relaxation response to ACh was prevented by dexamethasone (an anti-inflammatory agent) but not by antioxidants. Accordingly, SRM1648 increased the release of proinflammatory mediators (tumor necrosis factor-alpha, interleukin-8) from intrapulmonary arteries or pulmonary artery endothelial cells, but did not elevate ROS levels within intrapulmonary arteries. Decreased relaxation in response to ACh was also evidenced in intrapulmonary arteries removed from rats intratracheally instilled with SRM1648, but not with fine TiO2. CONCLUSION: In contrast to manufactured particles (including nanoparticles), urban PM impairs NO but not cGMP responsiveness in intrapulmonary arteries. We attribute this effect to oxidative-stress-independent inflammatory response, resulting in decreased guanylyl cyclase activation by NO. Such impairment of the NO pathway may contribute to urban-PM-induced cardiovascular dysfunction

Effect of propofol and etomidate on normoxic and chronically hypoxic pulmonary artery

BACKGROUND: Chronic alveolar hypoxia results in sustained arterial constriction, and increase in pulmonary vascular resistance leading to pulmonary artery hypertension (PAHT). The aim of this study was to investigate the effect of propofol and etomidate on pulmonary artery (PA) reactivity in chronically hypoxic (CH) rats, a model of pulmonary arterial hypertension (PAHT), in normoxic animals, and human PA. METHODS: CH rats were maintained 14 days at 380 mmHg pressure in a hypobaric chamber. Human tissue was retrieved from histological lung pieces from patients undergoing resection for carcinoma. Cumulative concentrations of anaesthetics were tested on isolated vascular rings precontracted with phenylephrine (PHE) or 100 mM KCl. Statistical comparisons were done by ANOVA, followed, when needed, by Student t tests with Bonferroni correction as post-hoc tests. RESULTS: In normoxic rat PA, maximal relaxation (R(max)) induced by etomidate and propofol was 101.3 ± 0.8% and 94.0 ± 2.3%, respectively, in KCl-precontracted rings, and 63.3 ± 9.7% and 46.1 ± 9.1%, respectively, in PHE-precontracted rings (n = 7). In KCl-precontracted human PA, R(max )was 84.7 ± 8.6 % and 66.5 ± 11.8%, for etomidate and propofol, respectively, and 154.2 ± 22.4 % and 51.6 ± 15.1 %, respectively, in PHE-precontracted human PA (n = 7). In CH rat PA, the relaxant effect of both anaesthetics was increased in PHE-precontracted and, for etomidate only, in KCl-precontracted PA. In aorta, CH induced no change in the relaxant effect of anaesthetics. CONCLUSION: Propofol and etomidate have relaxant properties in PA from human and normoxic rat. The relaxant effect is specifically accentuated in PA from CH rat, mainly via an effect on the pharmacomechanical coupling. Etomidate appears to be more efficient than propofol at identical concentration, but, taking into account clinical concentrations, etomidate is less potent than propofol, which effect was in the range of clinical doses. Although these findings provide experimental support for the preferential use of etomidate for haemodynamic stability in patients suffering from PAHT, the clinical relevance of the observations requires further investigation

The retrospective analysis of Antarctic tracking data project

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through biodiversity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 individual animals, and over 2.9 million observed locations

The retrospective analysis of Antarctic tracking data project

The Retrospective Analysis of Antarctic Tracking Data (RAATD) is a Scientific Committee for Antarctic Research project led jointly by the Expert Groups on Birds and Marine Mammals and Antarctic Biodiversity Informatics, and endorsed by the Commission for the Conservation of Antarctic Marine Living Resources. RAATD consolidated tracking data for multiple species of Antarctic meso- and top-predators to identify Areas of Ecological Significance. These datasets and accompanying syntheses provide a greater understanding of fundamental ecosystem processes in the Southern Ocean, support modelling of predator distributions under future climate scenarios and create inputs that can be incorporated into decision making processes by management authorities. In this data paper, we present the compiled tracking data from research groups that have worked in the Antarctic since the 1990s. The data are publicly available through biodiversity.aq and the Ocean Biogeographic Information System. The archive includes tracking data from over 70 contributors across 12 national Antarctic programs, and includes data from 17 predator species, 4060 individual animals, and over 2.9 million observed locations.Supplementary Figure S1: Filtered location data (black) and tag deployment locations (red) for each species. Maps are Lambert Azimuthal projections extending from 90° S to 20° S.Supplementary Table S1: Names and coordinates of the major study sites in the Southern Ocean and on the Antarctic Continent where tracking devices were deployed on the selected species (indicated by their 4-letter codes in the last column).Online Table 1: Description of fields (column names) in the metadata and data files.Supranational committees and organisations including the Scientific Committee on Antarctic Research Life Science Group and BirdLife International. National institutions and foundations, including but not limited to Argentina (Dirección Nacional del Antártico), Australia (Australian Antarctic program; Australian Research Council; Sea World Research and Rescue Foundation Inc., IMOS is a national collaborative research infrastructure, supported by the Australian Government and operated by a consortium of institutions as an unincorporated joint venture, with the University of Tasmania as Lead Agent), Belgium (Belgian Science Policy Office, EU Lifewatch ERIC), Brazil (Brazilian Antarctic Programme; Brazilian National Research Council (CNPq/MCTI) and CAPES), France (Agence Nationale de la Recherche; Centre National d’Etudes Spatiales; Centre National de la Recherche Scientifique; the French Foundation for Research on Biodiversity (FRB; www.fondationbiodiversite.fr) in the context of the CESAB project “RAATD”; Fondation Total; Institut Paul-Emile Victor; Programme Zone Atelier de Recherches sur l’Environnement Antarctique et Subantarctique; Terres Australes et Antarctiques Françaises), Germany (Deutsche Forschungsgemeinschaft, Hanse-Wissenschaftskolleg - Institute for Advanced Study), Italy (Italian National Antarctic Research Program; Ministry for Education University and Research), Japan (Japanese Antarctic Research Expedition; JSPS Kakenhi grant), Monaco (Fondation Prince Albert II de Monaco), New Zealand (Ministry for Primary Industries - BRAG; Pew Charitable Trusts), Norway (Norwegian Antarctic Research Expeditions; Norwegian Research Council), Portugal (Foundation for Science and Technology), South Africa (Department of Environmental Affairs; National Research Foundation; South African National Antarctic Programme), UK (Darwin Plus; Ecosystems Programme at the British Antarctic Survey; Natural Environment Research Council; WWF), and USA (U.S. AMLR Program of NOAA Fisheries; US Office of Polar Programs).http://www.nature.com/sdataam2021Mammal Research Institut