Potentiel antidiabétique de métabolites de polyphénols : les urolithines

The objective of our thesis was to study the anti-diabetic potential of metabolites of ellagic acid tanins, present notably in pomegranate and nuts, that are formed by the colon microbiote. The metabolites are urolithins A, B, C and D.The first part of thesis is bibliographic and reviews: •The control of glycemic plasma levels, and in particular the role of insulin secretion in this process; •The pathophysiology of Type 2 Diabetes (T2D); •The various polyphenols and their metabolites, along with their potential anti-diabetic activity.The second part describes the effects of urolithins on various experimental models: •On a model of insulin secreting beta cells (the INS-1cell line), urolithins concentration-dependently amplified insulin secretion induced by glucose, but also by insulinotropic drugs used in the treatment of T2D such as a GLP-1 analogue or a sulfonylurea. In addition, urolithins were able to induce insulin secretion on cells rendered unresponsive to glucose by oxidative stress. •The insulinotropic effect of urolithins was also confirmed on isolated rat islets of Langerhans. •As urolithin C appeared to be the most promising antidiabetic compound, we further characterized its activity on an ex vivo model mimicking the physiological situation, the isolated infused pancreas. While urolithin C (20µM) had no effect in the presence of 5 mM glucose concentration, it amplified the stimulation of insulin secretion in the presence of 8.3mM glucose. The effect of urolithin C was also strictly glucose-dependent, as insulin secretion immediately returned to basal level when glucose concentration was switched from 8.3 to 5mM glucose in the presence of urolithin C. •We also conducted studies aiming at designing a validated methodology for rat plasma urolithin C determination using a liquid chromatography-electrospray ionization-tandem mass spectrometry method. The applicability of this assay was demonstrated in a preclinical pharmacokinetic study carried out in rats receiving intraperitoneal administration of urolithin C (10mg/kg). We found that the urolithin C followed a three-compartment model, suggesting a long-term tissue storage of urolithin C.Some other (confidential) results, not described in this abstract, confirmed urolithin C as a potential glucose-dependent insulinotropic treatment for type 2 diabetes.Notre travail de thèse avait pour objet l’étude du potentiel anti-diabétique des urolithines A, B, C et D, métabolites de polyphénols formés par le microbiote colique à partir des tanins de l’acide ellagique (présents notamment dans la grenade et les noix). La première partie, bibliographique, constitue un rappel :•de la régulation de l’équilibre glycémique et le rôle de la sécrétion d’insuline dans cette régulation ; •de l ‘épidémiologie et la physiopathologie du diabète type 2 (DT2) ; •des polyphénols et leurs métabolites, ainsi que de leurs effets antidiabétiques potentiels.La seconde partie décrit les effets des urolithines sur différents modèles expérimentaux : •Sur un modèle de cellules β insulino-sécrétrices (lignée INS-1), les urolithines induisent une amplification concentration-dépendante de la sécrétion d’insuline induite par le glucose, mais également par d’autres sécrétagogues comme un analogue du GLP-1 ou une sulfonylurée (médicaments utilisés dans le diabète). Les urolithines préviennent également l’altération sécrétoire induite par un stress oxydant. •L’effet insulino-sécrétoire des urolithines a été confirmé sur îlots de Langerhans isolés. •L’urolithine C étant apparu comme le composé le plus prometteur, nous avons poursuivi la caractérisation de son activité sur un modèle ex vivo mimant la situation physiologique, le pancréas isolé perfusé. Alors que l’effet sécrétoire de l’urolithine C n’apparaît pas en présence de 5mM de glucose, l’urolithine C (20µM) a stimulé la sécrétion d’insuline dans des conditions de stimulation modérée de la sécrétion d’insuline par le glucose (8.3mM). Cet effet est strictement dépendant du glucose, la sécrétion d’insuline retournant immédiatement à son niveau basal lors du passage de 8,3 à 5mM de glucose en présence d’urolithine C. •Des études de pharmacocinétique ont permis de mettre au point une méthodologie de dosage plasmatique de l’urolithine C dans le plasma de rat par chromatographie liquide / ionisation electrospray /spectrographie de masse en tandem. Cette méthodologie a été appliquée à une première étude pharmacocinétique chez le rat après injection de 10mg/kg d’urolithine C par voie intra-péritonéale. Cette étude montre notamment que le profil pharmacocinétique suit un modèle à 3 compartiments et suggère un stockage tissulaire du composé.D’autres résultats (confidentiels) ne peuvent être évoqués dans ce résumé mais confirment l’intérêt potentiel de l’urolithine C dans le traitement du diabète de type 2 en tant que médicament insulinotrope dépendant du glucose

Antidiabetic potential of polyphenol metabolites : urolithins

Notre travail de thèse avait pour objet l’étude du potentiel anti-diabétique des urolithines A, B, C et D, métabolites de polyphénols formés par le microbiote colique à partir des tanins de l’acide ellagique (présents notamment dans la grenade et les noix). La première partie, bibliographique, constitue un rappel :• de la régulation de l’équilibre glycémique et le rôle de la sécrétion d’insuline dans cette régulation ; •de l ‘épidémiologie et la physiopathologie du diabète type 2 (DT2) ; •des polyphénols et leurs métabolites, ainsi que de leurs effets antidiabétiques potentiels.La seconde partie décrit les effets des urolithines sur différents modèles expérimentaux : •Sur un modèle de cellules β insulino-sécrétrices (lignée INS-1), les urolithines induisent une amplification concentration-dépendante de la sécrétion d’insuline induite par le glucose, mais également par d’autres sécrétagogues comme un analogue du GLP-1 ou une sulfonylurée (médicaments utilisés dans le diabète). Les urolithines préviennent également l’altération sécrétoire induite par un stress oxydant. •L’effet insulino-sécrétoire des urolithines a été confirmé sur îlots de Langerhans isolés. •L’urolithine C étant apparu comme le composé le plus prometteur, nous avons poursuivi la caractérisation de son activité sur un modèle ex vivo mimant la situation physiologique, le pancréas isolé perfusé. Alors que l’effet sécrétoire de l’urolithine C n’apparaît pas en présence de 5mM de glucose, l’urolithine C (20µM) a stimulé la sécrétion d’insuline dans des conditions de stimulation modérée de la sécrétion d’insuline par le glucose (8.3mM). Cet effet est strictement dépendant du glucose, la sécrétion d’insuline retournant immédiatement à son niveau basal lors du passage de 8,3 à 5mM de glucose en présence d’urolithine C. •Des études de pharmacocinétique ont permis de mettre au point une méthodologie de dosage plasmatique de l’urolithine C dans le plasma de rat par chromatographie liquide / ionisation electrospray /spectrographie de masse en tandem. Cette méthodologie a été appliquée à une première étude pharmacocinétique chez le rat après injection de 10mg/kg d’urolithine C par voie intra-péritonéale. Cette étude montre notamment que le profil pharmacocinétique suit un modèle à 3 compartiments et suggère un stockage tissulaire du composé.D’autres résultats (confidentiels) ne peuvent être évoqués dans ce résumé mais confirment l’intérêt potentiel de l’urolithine C dans le traitement du diabète de type 2 en tant que médicament insulinotrope dépendant du glucose.The objective of our thesis was to study the anti-diabetic potential of metabolites of ellagic acid tanins, present notably in pomegranate and nuts, that are formed by the colon microbiote. The metabolites are urolithins A, B, C and D.The first part of thesis is bibliographic and reviews: •The control of glycemic plasma levels, and in particular the role of insulin secretion in this process; • The pathophysiology of Type 2 Diabetes (T2D); •The various polyphenols and their metabolites, along with their potential anti-diabetic activity.The second part describes the effects of urolithins on various experimental models: •On a model of insulin secreting beta cells (the INS-1cell line), urolithins concentration-dependently amplified insulin secretion induced by glucose, but also by insulinotropic drugs used in the treatment of T2D such as a GLP-1 analogue or a sulfonylurea. In addition, urolithins were able to induce insulin secretion on cells rendered unresponsive to glucose by oxidative stress. • The insulinotropic effect of urolithins was also confirmed on isolated rat islets of Langerhans. •As urolithin C appeared to be the most promising antidiabetic compound, we further characterized its activity on an ex vivo model mimicking the physiological situation, the isolated infused pancreas. While urolithin C (20µM) had no effect in the presence of 5 mM glucose concentration, it amplified the stimulation of insulin secretion in the presence of 8.3mM glucose. The effect of urolithin C was also strictly glucose-dependent, as insulin secretion immediately returned to basal level when glucose concentration was switched from 8.3 to 5mM glucose in the presence of urolithin C. •We also conducted studies aiming at designing a validated methodology for rat plasma urolithin C determination using a liquid chromatography-electrospray ionization-tandem mass spectrometry method. The applicability of this assay was demonstrated in a preclinical pharmacokinetic study carried out in rats receiving intraperitoneal administration of urolithin C (10mg/kg). We found that the urolithin C followed a three-compartment model, suggesting a long-term tissue storage of urolithin C.Some other (confidential) results, not described in this abstract, confirmed urolithin C as a potential glucose-dependent insulinotropic treatment for type 2 diabetes

De l’Ile-de-France à l’Europe du nord-ouest : les peuplements humains avant le dernier maximum glaciaire, bilan, objectifs et perspectives de la recherche

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Protection of pancreatic β-cell function by dietary polyphenols

Diabetes mellitus is a complex metabolic disorder and is considered a fast-growing global health problem. Type 2 diabetes (T2D) represents the majority of total diabetes prevalence and b-cell dysfunction has been described as a crucial point for this disease development and progression. To date, all of the common anti-hyperglycaemic drugs used for diabetes management cause undesirable side effects or problems with long-term efficacy or safety and the development of alternative approaches for the prevention as well as for the treatment of T2D might be a valuable solution to meet this rising demand. In this regards, numerous epidemiological studies indicate that exposure to certain polyphenol compounds is associated with the prevention of chronic diseases, including diabetes. Here, we review growing evidence suggesting that polyphenols can modulate the activity of various molecular targets, which are known to control b-cell function, involved in the development and the progression of this diabetes. The protective effects of polyphenols on b-cell function is reported with a particular focus on the mechanism of action behind polyphenol putative bioactivity. Animal and in vitro studies selected in this review, reporting about both flavonoid and non-flavonoid compounds, highlight the direct action of polyphenols on pancreatic b-cells, stimulating insulin secretion through the activation of specific cellular targets and protecting these cells from damages mediated by oxidative stress and inflammation, both typically elevated in diabetes. Some of the reviewed studies describe polyphenol effects comparable to those exerted by many drugs commonly used in diabetes treatment, and, in some occasions, synergistic polyphenol-drug interactions. Finally, future studies need to be addressed to the effects of specific polyphenol human and microbial metabolites, which are still poorly studied, in order to better define the preventive and therapeutic approach to contrast b-cell failure and diabetes progression

Proof of concept study of mass cytometry in septic shock patients reveals novel immune alterations

Abstract Innovative single cell technologies such as mass cytometry (CyTOF) widen possibilities to deeply improve characterisation of immune alterations mechanisms in human diseases. So far, CyTOF has not been used in sepsis – a condition characterized by complex immune disorders. Here, we evaluated feasibility of CyTOF analysis in patients with septic shock. We designed a mass cytometry panel of 25 extracellular markers to study mononuclear cells from 5 septic shock patients and 5 healthy donors. We explored single-cell data with global and specific unsupervised approaches such as heatmaps, SPADE and viSNE. We first validated relevance of our CyTOF results by highlighting established immune hallmarks of sepsis, such as decreased monocyte HLA-DR expression and increased expressions of PD1 and PD-L1 on CD4 T cells and monocytes. We then showed that CyTOF analysis reveals novel aspects of sepsis-induced immune alterations, e.g. B cell shift towards plasma cell differentiation and uniform response of several monocyte markers defining an immune signature in septic patients. This proof of concept study demonstrates CyTOF suitability to analyse immune features of septic patients. Mass cytometry could thus represent a powerful tool to identify novel pathophysiological mechanisms and therapeutic targets for immunotherapy in septic shock patients

Le Pléistocène de la Région Centre-Val de Loire : nouvelles données issues de l’archéologie préventive.

International audienc

SARS-CoV-2 viral load in nasopharyngeal swabs in the emergency department does not predict COVID-19 severity and mortality

International audienceIntroduction The ongoing COVID-19 pandemic has led to devastating repercussions on health care systems worldwide. This viral infection has a broad clinical spectrum (ranging from influenza-like disease, viral pneumonia, and hypoxemia to acute respiratory distress syndrome requiring prolonged intensive care unit stays). The prognostic impact of measuring viral load on nasopharyngeal swab specimens (by reverse transcriptase polymerase chain reaction [RT-PCR]) is yet to be elucidated. Methods Between March 3 and April 5, 2020, we conducted a retrospective study on a cohort of COVID-19 patients (mild or severe disease) who were hospitalized after presenting to the emergency department (ED) and had at least one positive nasopharyngeal swab during their hospital stay. We led our study at the University Hospitals of Strasbourg in the Greater East region of France, one of the pandemic's epicenters in Europe. Results We have collected samples from a cohort of 287 patients with a confirmed diagnosis of COVID-19 who were included in our study. Nearly half of them (50.5%) presented a mild form of the disease, while the other half (49.5%) presented a severe form, requiring mechanical ventilation. Median (interquartile range) viral load on the initial upper respiratory swab at admission was 4.76 (3.29–6.06) log10 copies/reaction. When comparing survivors and nonsurvivors, this viral load measurement did not differ according to subgroups (p = 0.332). Additionally, we have found that respiratory viral load measurement was predictive of neither in-hospital mortality (adjusted odds ratio [AOR] = 1.05, 95% confidence interval [CI] = 0.85 to 1.31, p = 0.637) nor disease severity (AOR = 0.88, 95% CI = 0.73 to 1.06, p = 0.167). Conclusion Respiratory viral load measurement on the first nasopharyngeal swab (by RT-PCR) during initial ED management is neither a predictor of severity nor a predictor of mortality in SARS-CoV-2 infection. Host response to this viral infection along with the extent of preexisting comorbidities might be more foretelling of disease severity than the virus itself

Rapid Antigen Test Combined with Chest Computed Tomography to Rule Out COVID-19 in Patients Admitted to the Emergency Department

Objective: Correct and timely identification of SARS-CoV-2-positive patients is critical in the emergency department (ED) prior to admission to medical wards. Antigen-detecting rapid diagnostic tests (Ag-RDTs) are a rapid alternative to Reverse-transcriptase polymerase chain reaction (RT-PCR) for the diagnosis of COVID-19 but have lower sensitivity.Methods: We evaluated the performance in real-life conditions of a strategy combining Ag-RDT and chest computed tomography (CT) to rule out COVID-19 infection in 1015 patients presenting in the ED between 16 November 2020 and 18 January 2021 in order to allow non-COVID-19 patients to be hospitalized in dedicated units directly. The combined strategy performed in the ED for patients with COVID-19 symptoms was assessed and compared with RT-PCR.Results: Compared with RT-PCR, the negative predictive value was 96.7% for Ag-RDT alone, 98.5% for Ag-RDT/CT combined, and increased to 100% for patients with low viral load.Conclusion: A strategy combining Ag-RDT and chest CT is effective in ruling out COVID-19 in ED patients with high precision

Functional and pharmacological explorations of quercetin-like compounds on glucose-induced insulin secretion

International audienc