Gout and pseudo-gout-related crystals promote GLUT1-mediated glycolysis that governs NLRP3 and interleukin-1β activation on macrophages

Objective Macrophage activation by monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals mediates an interleukin (IL)-1β-dependent inflammation during gout and pseudo-gout flare, respectively. Since metabolic reprogramming of macrophages goes along with inflammatory responses dependently on stimuli and tissue environment, we aimed to decipher the role of glycolysis and oxidative phosphorylation in the IL-1β-induced microcrystal response. Methods Briefly, an in vitro study (metabolomics and real-time extracellular flux analysis) on MSU and CPP crystal-stimulated macrophages was performed to demonstrate the metabolic phenotype of macrophages. Then, the role of aerobic glycolysis in IL-1β production was evaluated, as well in vitro as in vivo using 18F-fluorodeoxyglucose positron emission tomography imaging and glucose uptake assay, and molecular approach of glucose transporter 1 (GLUT1) inhibition. Results We observed that MSU and CPP crystals led to a metabolic rewiring toward the aerobic glycolysis pathway explained by an increase in GLUT1 plasma membrane expression and glucose uptake on macrophages. Also, neutrophils isolated from human synovial fluid during gout flare expressed GLUT1 at their plasma membrane more frequently than neutrophils isolated from bloodstream. Both glucose deprivation and treatment with either 2-deoxyglucose or GLUT1 inhibitor suppressed crystal-induced NLRP3 activation and IL-1β production, and microcrystal inflammation in vivo. Conclusion In conclusion, we demonstrated that GLUT1-mediated glucose uptake is instrumental during the inflammatory IL-1β response induced by MSU and CPP crystals. These findings open new therapeutic paths to modulate crystal-related inflammation

Peri-operative red blood cell transfusion in neonates and infants: NEonate and Children audiT of Anaesthesia pRactice IN Europe: A prospective European multicentre observational study

BACKGROUND: Little is known about current clinical practice concerning peri-operative red blood cell transfusion in neonates and small infants. Guidelines suggest transfusions based on haemoglobin thresholds ranging from 8.5 to 12 g dl-1, distinguishing between children from birth to day 7 (week 1), from day 8 to day 14 (week 2) or from day 15 (≥week 3) onwards. OBJECTIVE: To observe peri-operative red blood cell transfusion practice according to guidelines in relation to patient outcome. DESIGN: A multicentre observational study. SETTING: The NEonate-Children sTudy of Anaesthesia pRactice IN Europe (NECTARINE) trial recruited patients up to 60 weeks' postmenstrual age undergoing anaesthesia for surgical or diagnostic procedures from 165 centres in 31 European countries between March 2016 and January 2017. PATIENTS: The data included 5609 patients undergoing 6542 procedures. Inclusion criteria was a peri-operative red blood cell transfusion. MAIN OUTCOME MEASURES: The primary endpoint was the haemoglobin level triggering a transfusion for neonates in week 1, week 2 and week 3. Secondary endpoints were transfusion volumes, 'delta haemoglobin' (preprocedure - transfusion-triggering) and 30-day and 90-day morbidity and mortality. RESULTS: Peri-operative red blood cell transfusions were recorded during 447 procedures (6.9%). The median haemoglobin levels triggering a transfusion were 9.6 [IQR 8.7 to 10.9] g dl-1 for neonates in week 1, 9.6 [7.7 to 10.4] g dl-1 in week 2 and 8.0 [7.3 to 9.0] g dl-1 in week 3. The median transfusion volume was 17.1 [11.1 to 26.4] ml kg-1 with a median delta haemoglobin of 1.8 [0.0 to 3.6] g dl-1. Thirty-day morbidity was 47.8% with an overall mortality of 11.3%. CONCLUSIONS: Results indicate lower transfusion-triggering haemoglobin thresholds in clinical practice than suggested by current guidelines. The high morbidity and mortality of this NECTARINE sub-cohort calls for investigative action and evidence-based guidelines addressing peri-operative red blood cell transfusions strategies. TRIAL REGISTRATION: ClinicalTrials.gov, identifier: NCT02350348

Rôle d’IRF5 dans les adaptations métaboliques des macrophages au cours d’un stress métabolique

L’obésité et le diabète de type-2 (DT2) sont des pathologies à étiologie multifactorielle : métabolique et inflammatoire. L’inflammation métabolique est initiée par l’activation des macrophages tissulaires, notamment orchestrée par le facteur de transcription pro-inflammatoire Interferon regulatory factor (IRF)-5. Le métabolisme cellulaire contribue à la polarisation des cellules immunitaires. Ces mécanismes immunométaboliques et le potentiel rôle d’IRF5 restent à élucider dans des contextes obésogènes. Des souris spécifiquement invalidées pour IRF5 dans les cellules myéloïdes (IRF5-KO) sont soumises à un régime gras. Lors d’un stress métabolique, nous observons une répression de l’activité mitochondriale, IRF5-dépendante, dans les macrophages du tissu adipeux. Ce phénotype hyperoxydatif est inductible et réversible en modulant l’activité d’IRF5 in vitro. Les macrophages IRF5-KO présentent une altération du cycle de Krebs et une surface de crêtes mitochondriales augmentée par rapport aux macrophages WT. L’analyse couplée de RNA-seq et de ChIP-seq d’IRF5 a permis d’identifier Growth Hormone Inducible Transmembrane Protein (GHITM) comme cible transcriptionnelle d’IRF5 en réponse à un stress métabolique. GHITM permet le maintien de la structure des crêtes mitochondriale et son inhibition IRF5-dépendante participe à la répression de la fonction mitochondriale des macrophages du TA. En parallèle de son rôle canonique dans l’inflammation, IRF5 contrôle le métabolisme cellulaire des macrophages, en inhibant la respiration mitochondriale, via la répression transcriptionnelle de GHITM. Cette thèse souligne le rôle clé du métabolisme cellulaire dans l'activation des macrophages.Obesity and type 2 diabetes (T2D) are growing pandemics. These diseases are of both etiologies: metabolic and inflammatory. The abnormal and ectopic accumulation of fat in the organism leads to the accumulation and activation of tissue resident immune cells, and particularly adipose tissue macrophages (ATM). This phenomenon is the starting point of the so-called metabolic inflammation which is a sterile, systemic and lowgrade inflammation. This pro-inflammatory environment favors the progression of obesity and its complications. The pro-inflammatory transcription factor interferon regulatory factor (IRF) 5 plays a key role in the activation of ATMs during obesity. An emerging field of research places cellular metabolism at the center of immune-effector function. M1 macrophages display an increase of glycolysis while M2 macrophages rely on oxidative respiration to produce energy. This thesis focuses on the potential role of IRF5 in the bioenergetic adaptations of macrophages upon a metabolic stress. Mice with a specific myeloid deletion of IRF5 (IRF5-KO) were fed with a high fat diet. Analysis of the bioenergetic and transcriptional profile of IRF5-KO and WT ATMs revealed that IRF5 represses the mitochondrial activity. Combined analysis of RNA-seq and ChIP-seq data indicate that IRF5 represses the expression of the Growth Hormone Inducible Transmembrane Protein, a mitochondrial protein. This transcriptional repression triggers AT maladaptation to caloric excess. This non-canonical IRF5-GHITM axis extends to ATMs and monocytes from T2D and/or obese patients. Overall, this thesis underlies the powerful function of cellular metabolism in controlling macrophage activation

Rôle d’IRF5 dans les adaptations métaboliques des macrophages au cours d’un stress métabolique

Obesity and type 2 diabetes (T2D) are growing pandemics. These diseases are of both etiologies: metabolic and inflammatory. The abnormal and ectopic accumulation of fat in the organism leads to the accumulation and activation of tissue resident immune cells, and particularly adipose tissue macrophages (ATM). This phenomenon is the starting point of the so-called metabolic inflammation which is a sterile, systemic and lowgrade inflammation. This pro-inflammatory environment favors the progression of obesity and its complications. The pro-inflammatory transcription factor interferon regulatory factor (IRF) 5 plays a key role in the activation of ATMs during obesity. An emerging field of research places cellular metabolism at the center of immune-effector function. M1 macrophages display an increase of glycolysis while M2 macrophages rely on oxidative respiration to produce energy. This thesis focuses on the potential role of IRF5 in the bioenergetic adaptations of macrophages upon a metabolic stress. Mice with a specific myeloid deletion of IRF5 (IRF5-KO) were fed with a high fat diet. Analysis of the bioenergetic and transcriptional profile of IRF5-KO and WT ATMs revealed that IRF5 represses the mitochondrial activity. Combined analysis of RNA-seq and ChIP-seq data indicate that IRF5 represses the expression of the Growth Hormone Inducible Transmembrane Protein, a mitochondrial protein. This transcriptional repression triggers AT maladaptation to caloric excess. This non-canonical IRF5-GHITM axis extends to ATMs and monocytes from T2D and/or obese patients. Overall, this thesis underlies the powerful function of cellular metabolism in controlling macrophage activation.L’obésité et le diabète de type-2 (DT2) sont des pathologies à étiologie multifactorielle : métabolique et inflammatoire. L’inflammation métabolique est initiée par l’activation des macrophages tissulaires, notamment orchestrée par le facteur de transcription pro-inflammatoire Interferon regulatory factor (IRF)-5. Le métabolisme cellulaire contribue à la polarisation des cellules immunitaires. Ces mécanismes immunométaboliques et le potentiel rôle d’IRF5 restent à élucider dans des contextes obésogènes. Des souris spécifiquement invalidées pour IRF5 dans les cellules myéloïdes (IRF5-KO) sont soumises à un régime gras. Lors d’un stress métabolique, nous observons une répression de l’activité mitochondriale, IRF5-dépendante, dans les macrophages du tissu adipeux. Ce phénotype hyperoxydatif est inductible et réversible en modulant l’activité d’IRF5 in vitro. Les macrophages IRF5-KO présentent une altération du cycle de Krebs et une surface de crêtes mitochondriales augmentée par rapport aux macrophages WT. L’analyse couplée de RNA-seq et de ChIP-seq d’IRF5 a permis d’identifier Growth Hormone Inducible Transmembrane Protein (GHITM) comme cible transcriptionnelle d’IRF5 en réponse à un stress métabolique. GHITM permet le maintien de la structure des crêtes mitochondriale et son inhibition IRF5-dépendante participe à la répression de la fonction mitochondriale des macrophages du TA. En parallèle de son rôle canonique dans l’inflammation, IRF5 contrôle le métabolisme cellulaire des macrophages, en inhibant la respiration mitochondriale, via la répression transcriptionnelle de GHITM. Cette thèse souligne le rôle clé du métabolisme cellulaire dans l'activation des macrophages

Rôle d’IRF5 dans les adaptations métaboliques des macrophages au cours d’un stress métabolique

Obesity and type 2 diabetes (T2D) are growing pandemics. These diseases are of both etiologies: metabolic and inflammatory. The abnormal and ectopic accumulation of fat in the organism leads to the accumulation and activation of tissue resident immune cells, and particularly adipose tissue macrophages (ATM). This phenomenon is the starting point of the so-called metabolic inflammation which is a sterile, systemic and lowgrade inflammation. This pro-inflammatory environment favors the progression of obesity and its complications. The pro-inflammatory transcription factor interferon regulatory factor (IRF) 5 plays a key role in the activation of ATMs during obesity. An emerging field of research places cellular metabolism at the center of immune-effector function. M1 macrophages display an increase of glycolysis while M2 macrophages rely on oxidative respiration to produce energy. This thesis focuses on the potential role of IRF5 in the bioenergetic adaptations of macrophages upon a metabolic stress. Mice with a specific myeloid deletion of IRF5 (IRF5-KO) were fed with a high fat diet. Analysis of the bioenergetic and transcriptional profile of IRF5-KO and WT ATMs revealed that IRF5 represses the mitochondrial activity. Combined analysis of RNA-seq and ChIP-seq data indicate that IRF5 represses the expression of the Growth Hormone Inducible Transmembrane Protein, a mitochondrial protein. This transcriptional repression triggers AT maladaptation to caloric excess. This non-canonical IRF5-GHITM axis extends to ATMs and monocytes from T2D and/or obese patients. Overall, this thesis underlies the powerful function of cellular metabolism in controlling macrophage activation.L’obésité et le diabète de type-2 (DT2) sont des pathologies à étiologie multifactorielle : métabolique et inflammatoire. L’inflammation métabolique est initiée par l’activation des macrophages tissulaires, notamment orchestrée par le facteur de transcription pro-inflammatoire Interferon regulatory factor (IRF)-5. Le métabolisme cellulaire contribue à la polarisation des cellules immunitaires. Ces mécanismes immunométaboliques et le potentiel rôle d’IRF5 restent à élucider dans des contextes obésogènes. Des souris spécifiquement invalidées pour IRF5 dans les cellules myéloïdes (IRF5-KO) sont soumises à un régime gras. Lors d’un stress métabolique, nous observons une répression de l’activité mitochondriale, IRF5-dépendante, dans les macrophages du tissu adipeux. Ce phénotype hyperoxydatif est inductible et réversible en modulant l’activité d’IRF5 in vitro. Les macrophages IRF5-KO présentent une altération du cycle de Krebs et une surface de crêtes mitochondriales augmentée par rapport aux macrophages WT. L’analyse couplée de RNA-seq et de ChIP-seq d’IRF5 a permis d’identifier Growth Hormone Inducible Transmembrane Protein (GHITM) comme cible transcriptionnelle d’IRF5 en réponse à un stress métabolique. GHITM permet le maintien de la structure des crêtes mitochondriale et son inhibition IRF5-dépendante participe à la répression de la fonction mitochondriale des macrophages du TA. En parallèle de son rôle canonique dans l’inflammation, IRF5 contrôle le métabolisme cellulaire des macrophages, en inhibant la respiration mitochondriale, via la répression transcriptionnelle de GHITM. Cette thèse souligne le rôle clé du métabolisme cellulaire dans l'activation des macrophages

Metabolic and Molecular Mechanisms of Macrophage Polarisation and Adipose Tissue Insulin Resistance

International audienceInflammation plays a key role in the development and progression of type-2 diabetes (T2D), a disease characterised by peripheral insulin resistance and systemic glucolipotoxicity. Visceral adipose tissue (AT) is the main source of inflammation early in the disease course. Macrophages are innate immune cells that populate all peripheral tissues, including AT. Dysregulated AT macrophage (ATM) responses to microenvironmental changes are at the root of aberrant inflammation and development of insulin resistance, locally and systemically. The inflammatory activation of macrophages is regulated at multiple levels: cell surface receptor stimulation, intracellular signalling, transcriptional and metabolic levels. This review will cover the main mechanisms involved in AT inflammation and insulin resistance in T2D. First, we will describe the physiological and pathological changes in AT that lead to inflammation and insulin resistance. We will next focus on the transcriptional and metabolic mechanisms described that lead to the activation of ATMs. We will discuss more novel metabolic mechanisms that influence macrophage polarisation in other disease or tissue contexts that may be relevant to future work in insulin resistance and T2D

Développement des collectifs de travail et développement de la sécurité : une étude sur les décisions à risque en anesthésie

International audienc

Développement des collectifs de travail et développement de la sécurité : une étude sur les décisions à risques en anesthésie

International audienc

Développement des collectifs de travail et développement de la sécurité : une étude sur les décisions à risques en anesthésie

International audienc