AMINO ACID RESTRICTION AND HYDROGEN SULFIDE IN VASCULAR HOMEOSTASIS

Dietary Restriction (DR), defined as reduced food intake without malnutrition, was first described nearly a century ago to extend lifespan in rats. Since then, DR has been extensively studied, in a multitude of organisms, and evidence supports that DR increases lifespan and confers protection against age-associated diseases such as hypertension, ischemia of the limbs, heart or brain. Angiogenesis, the formation of new blood vessels by endothelial cells (EC), is crucial for the protection and recovery from blood vessel occlusion. Hypoxia is the best understood pro-angiogenic trigger, but therapies targeting this pathway have largely failed to demonstrate long-term benefits. Here, we hypothesized that a nutrient-based pathway regulates angiogenesis independent of hypoxia. We found that dietary sulfur amino acid restriction (methionine and cysteine) promoted VEGF expression and capillary growth in skeletal muscle of mice independent of hypoxia or the transcription factor HIF1, instead requiring the amino acid- sensing translation initiation factor eIF2 kinase GCN2 and the transcription factor ATF4. GCN2/ATF4 activation increased cystathionine--lyase expression and pro-angiogenic hydrogen sulfide (H2S) production. In human EC, H2S boosted glycolytic ATP production by inhibiting mitochondrial electron transport, and was required for angiogenesis triggered by amino acid deprivation, exercise or local VEGF overexpression. H2S is an endogenously produced gas with broad protective effects on the vascular system, and can be measured in blood serum. Using a cohort of patients undergoing vascular surgery (for advanced occlusive disease) and matched healthy patients, we found that healthy patients had the highest serum H2S production. Importantly, among patients that underwent surgery for vascular disease, the percentage of survival in the low H2S (defined as < median) was lower compared to high H2S (defined as > median) suggesting that it may serve as an easily quantified measure with biological significance with regards to vascular health. -- La restriction alimentaire (RA), définie comme une réduction des apports alimentaires sans malnutrition, fut décrite il y a près d'un siècle. Depuis, la RA a été étudiée dans une multitude d'organismes, démontrant que la RA permet d’augmenter l’espérance de vie et de protéger contre les maladies associées à l'âge telles que l'hypertension, l'ischémie cardiaque, cérébrale et des membres inférieurs. L'angiogenèse, soit la formation de nouveaux vaisseaux sanguins par les cellules endothéliales (EC), protège et facilite la récupération lors d’une occlusion vasculaire (ischémie). L'hypoxie est le stimulus pro-angiogénique le plus étudié; cependant, les thérapies ciblant cette voie ont à l’heure actuelle largement échouées. Nous avons donc émis l'hypothèse qu'une voie indépendante, nutrio-sensible, pouvait réguler la formation de nouveaux vaisseaux. Nos résultats suggèrent que la restriction d’acides aminés soufrés (méthionine et cystéine) favorise l'expression du factor de croissance vasculaire VEGF et la croissance capillaire in-vivo, indépendamment de l'hypoxie ou de l'HIF1α mais nécessitant la kinase GCN2 et le facteur de transcription ATF4. L'activation de GCN2/ATF4 augmente l'expression de cystathionine-y-lyase et la production de sulfure d'hydrogène (H2S), connu pour ses propriétés pro-angiogéniques. Dans les EC humaines, le H2S favorise l’angiogenèse en inhibant le transport d'électrons mitochondrials, stimulant la production d'ATP glycolytique. H2S est un gaz produit de manière endogène avec des effets protecteurs sur le système vasculaire, et peut être mesuré dans le sérum. Dans une cohorte de patients hospitalisés pour une maladie vasculaire occlusive avancée et de patients sains nous avons constaté que les taux sériques d’H2S étaient plus élevés chez les patients sains. De plus, parmi les patients qui ont subi une intervention chirurgicale pour les maladies vasculaires, la survie à 6 et 24 mois était plus élevée chez les patients avec un taux préopératoire élevé d’H2S. En conclusion, nos résultats démontre qu’une RA, via H2S participent à la fonction du système vasculaire et pourrait jouer un rôle majeur dans la survie/ récupération des patients ayant subi un intervention vasculaire

Amino Acid Restriction Triggers Angiogenesis via GCN2/ATF4 Regulation of VEGF and H2S Production

Angiogenesis, the formation of new blood vessels by endothelial cells (ECs), is an adaptive response to oxygen/nutrient deprivation orchestrated by vascular endothelial growth factor (VEGF) upon ischemia or exercise. Hypoxia is the best-understood trigger of VEGF expression via the transcription factor HIF1 alpha. Nutrient deprivation is inseparable from hypoxia during ischemia, yet its role in angiogenesis is poorly characterized. Here, we identified sulfur amino acid restriction as a proangiogenic trigger, promoting increased VEGF expression, migration and sprouting in ECs in vitro, and increased capillary density in mouse skeletal muscle in vivo via the GCN2/ATF4 amino acid starvation response pathway independent of hypoxia or HIF1 alpha. We also identified a requirement for cystathionine-gamma-lyase in VEGF-dependent angiogenesis via increased hydrogen sulfide (H2S) production. H2S mediated its proangiogenic effects in part by inhibiting mitochondrial electron transport and oxidative phosphorylation, resulting in increased glucose uptake and glycolytic ATP production.11Ysciescopu

Versican is differentially regulated in the adventitial and medial layers of human vein grafts

Changes in extracellular matrix proteins may contribute significantly to the adaptation of vein grafts to the arterial circulation. We examined the production and distribution of versican and hyaluronan in intact human vein rings cultured ex vivo, veins perfused ex vivo, and cultured venous adventitial and smooth muscle cells. Immunohistochemistry revealed higher levels of versican in the intima/media compared to the adventitia, and no differences in hyaluronan. In the vasa vasorum, versican and hyaluronan associated with CD34 + progenitor cells. Culturing the vein rings for 14 days revealed increased versican immunostaining of 30–40% in all layers, with no changes in hyaluronan. Changes in versican accumulation appear to result from increased synthesis in the intima/media and decreased degradation in the adventitia as versican transcripts were increased in the intima/media, but unchanged in the adventitia, and versikine (the ADAMTS-mediated cleavage product of versican) was increased in the intima/media, but decreased in the adventitia. In perfused human veins, versican was specifically increased in the intima/media in the presence of venous pressure, but not with arterial pressure. Unexpectedly, cultured adventitial cells express and accumulate more versican and hyaluronan than smooth muscle cells. These data demonstrate a differential regulation of versican and hyaluronan in human venous adventitia vs. intima/media and suggest distinct functions for these extracellular matrix macromolecules in these venous wall compartments during the adaptive response of vein grafts to the arterial circulation

Scoring systems as outcomes assessment of the treatments for haemorrhoidal disease: a systematic review of the literature

The comparison between haemorrhoidal treatments is still unclear. Attempts have been made to adopt a unifying postoperative scoring system and thus ensure adequate comparison between clinical trials. We aimed to systematically review the available outcome scores of haemorrhoidal treatment

Proximal deep vein thrombosis and pulmonary embolism in COVID-19 patients: a systematic review and meta-analysis

Background: COVID-19 appears to be associated with a high risk of venous thromboembolism (VTE). We aimed to systematically review and meta-analyze the risk of clinically relevant VTE in patients hospitalized for COVID-19. Methods: This meta-analysis included original articles in English published from January 1st, 2020 to June 15th, 2020 in Pubmed/MEDLINE, Embase, Web of science, and Cochrane. Outcomes were major VTE, defined as any objectively diagnosed pulmonary embolism (PE) and/or proximal deep vein thrombosis (DVT). Primary analysis estimated the risk of VTE, stratified by acutely and critically ill inpatients. Secondary analyses explored the separate risk of proximal DVT and of PE; the risk of major VTE stratified by screening and by type of anticoagulation. Results: In 33 studies (n = 4009 inpatients) with heterogeneous thrombotic risk factors, VTE incidence was 9% (95%CI 5-13%, I2 = 92.5) overall, and 21% (95%CI 14-28%, I2 = 87.6%) for patients hospitalized in the ICU. Proximal lower limb DVT incidence was 3% (95%CI 1-5%, I2 = 87.0%) and 8% (95%CI 3-14%, I2 = 87.6%), respectively. PE incidence was 8% (95%CI 4-13%, I2 = 92.1%) and 17% (95%CI 11-25%, I2 = 89.3%), respectively. Screening and absence of anticoagulation were associated with a higher VTE incidence. When restricting to medically ill inpatients, the VTE incidence was 2% (95%CI 0-6%). Conclusions: The risk of major VTE among COVID-19 inpatients is high but varies greatly with severity of the disease. These findings reinforce the need for the use of thromboprophylaxis in all COVID-19 inpatients and for clinical trials testing different thromboprophylaxis regimens in subgroups of COVID-19 inpatients. Trial registration: The review protocol was registered in PROSPERO International Prospective Register of Systematic Reviews (CRD42020193369).</p

Sodium thiosulfate acts as a hydrogen sulfide mimetic to prevent intimal hyperplasia via inhibition of tubulin polymerisation

Background Intimal hyperplasia (IH) remains a major limitation in the long-term success of any type of revascularisation. IH is due to vascular smooth muscle cell (VSMC) dedifferentiation, proliferation and migration. The gasotransmitter Hydrogen Sulfide (H2S), mainly produced in blood vessels by the enzyme cystathionine- γ-lyase (CSE), inhibits IH in pre-clinical models. However, there is currently no H2S donor available to treat patients. Here we used sodium thiosulfate (STS), a clinically-approved source of sulfur, to limit IH. Methods Low density lipoprotein receptor deleted (LDLR−/−), WT or Cse-deleted (Cse−/−) male mice randomly treated with 4 g/L STS in the water bottle were submitted to focal carotid artery stenosis to induce IH. Human vein segments were maintained in culture for 7 days to induce IH. Further in vitro studies were conducted in primary human vascular smooth muscle cells (VSMCs). Findings STS inhibited IH in WT mice, as well as in LDLR−/− and Cse−/− mice, and in human vein segments. STS inhibited cell proliferation in the carotid artery wall and in human vein segments. STS increased polysulfides in vivo and protein persulfidation in vitro, which correlated with microtubule depolymerisation, cell cycle arrest and reduced VSMC migration and proliferation. Interpretation STS, a drug used for the treatment of cyanide poisoning and calciphylaxis, protects against IH in a mouse model of arterial restenosis and in human vein segments. STS acts as an H2S donor to limit VSMC migration and proliferation via microtubule depolymerisation.ISSN:2352-396

In vivo magnetic resonance P-31-Spectral Analysis With Neural Networks: 31P-SPAWNN

Purpose: We have introduced an artificial intelligence framework, 31P-SPAWNN, in order to fully analyze phosphorus-31 (P-31) magnetic resonance spectra. The flexibility and speed of the technique rival traditional least-square fitting methods, with the performance of the two approaches, are compared in this work.Theory and Methods: Convolutional neural network architectures have been proposed for the analysis and quantification of P-31-spectroscopy. The generation of training and test data using a fully parameterized model is presented herein. In vivo unlocalized free induction decay and three-dimensional P-31-magnetic resonance spectroscopy imaging data were acquired from healthy volunteers before being quantified using either 31P-SPAWNN or traditional least-square fitting techniques.Results: The presented experiment has demonstrated both the reliability and accuracy of 31P-SPAWNN for estimating metabolite concentrations and spectral parameters. Simulated test data showed improved quantification using 31P-SPAWNN compared with LCModel. In vivo data analysis revealed higher accuracy at low signal-to-noise ratio using 31P-SPAWNN, yet with equivalent precision. Processing time using 31P-SPAWNN can be further shortened up to two orders of magnitude.Conclusion: The accuracy, reliability, and computational speed of the method open new perspectives for integrating these applications in a clinical setting