Notch activation shifts the fate decision of senescent progenitors toward myofibrogenesis in human adipose tissue.

Senescence is a key event in the impairment of adipose tissue (AT) function with obesity and aging but the underlying molecular and cellular players remain to be fully defined, particularly with respect to the human AT progenitors. We have found distinct profiles of senescent progenitors based on AT location between stroma from visceral versus subcutaneous AT. In addition to flow cytometry, we characterized the location differences with transcriptomic and proteomic approaches, uncovering the genes and developmental pathways that are underlying replicative senescence. We identified key components to include INBHA as well as SFRP4 and GREM1, antagonists for the WNT and BMP pathways, in the senescence-associated secretory phenotype and NOTCH3 in the senescence-associated intrinsic phenotype. Notch activation in AT progenitors inhibits adipogenesis and promotes myofibrogenesis independently of TGFß. In addition, we demonstrate that NOTCH3 is enriched in the premyofibroblast progenitor subset, which preferentially accumulates in the visceral AT of patients with an early obesity trajectory. Herein, we reveal that NOTCH3 plays a role in the balance of progenitor fate determination preferring myofibrogenesis at the expense of adipogenesis. Progenitor NOTCH3 may constitute a tool to monitor replicative senescence and to limit AT dysfunction in obesity and aging.

Multiple Direct Effects of the Dietary Protoalkaloid N-Methyltyramine in Human Adipocytes.

Dietary amines have been the subject of a novel interest in nutrition since the discovery of trace amine-associated receptors (TAARs), especially TAAR-1, which recognizes tyramine, phenethylamine, tryptamine, octopamine, N-methyltyramine (NMT), synephrine, amphetamine and related derivatives. Alongside the psychostimulant properties of TAAR-1 ligands, it is their ephedrine-like action on weight loss that drives their current consumption via dietary supplements advertised for 'fat-burning' properties. Among these trace amines, tyramine has recently been described, at high doses, to exhibit an antilipolytic action and activation of glucose transport in human adipocytes, i.e., effects that are facilitating lipid storage rather than mobilization. Because of its close structural similarity to tyramine, NMT actions on human adipocytes therefore must to be reevaluated. To this aim, we studied the lipolytic and antilipolytic properties of NMT together with its interplay with insulin stimulation of glucose transport along with amine oxidase activities in adipose cells obtained from women undergoing abdominal surgery. NMT activated 2-deoxyglucose uptake when incubated with freshly isolated adipocytes at 0.01-1 mM, reaching one-third of the maximal stimulation by insulin. However, when combined with insulin, NMT limited by half the action of the lipogenic hormone on glucose transport. The NMT-induced stimulation of hexose uptake was sensitive to inhibitors of monoamine oxidases (MAO) and of semicarbazide-sensitive amine oxidase (SSAO), as was the case for tyramine and benzylamine. All three amines inhibited isoprenaline-induced lipolysis to a greater extent than insulin, while they were poorly lipolytic on their own. All three amines-but not isoprenaline-interacted with MAO or SSAO. Due to these multiple effects on human adipocytes, NMT cannot be considered as a direct lipolytic agent, potentially able to improve lipid mobilization and fat oxidation in consumers of NMT-containing dietary supplements.

Treatment of hyperpigmentation after burn: A literature review.

OBJECTIFY: Skin pigmentation disorders are one of the most frequent sequelae after burn injury. While these conditions often improve over time, some are permanent and cause severe psychological disorders (especially on the face). Given the frequency of these disorders and their benign nature, the scientific community has great difficulty postponing these patient follow-ups. Publications on their management are rare, and there is no consensus on the gold standard treatment for skin dyschromia. Herein, we performed a literature review including the various treatments currently proposed to manage these hyperpigmentations. METHODS: All reported articles up to February 2021 were reviewed on Pubmed. Studies on the treatment of hyperpigmented scars were included if they were secondary to burn injuries. Excluded articles evaluated transient treatments, such as makeup, and articles on inflammatory hyperpigmentation without etiological details or not secondary to burns. RESULTS: 201 articles were identified, and 13 studies were included. Topical creams used in inflammatory hyperpigmented lesions such as hydroquinone and first-line retinoids are controversial due to their inconstant efficacy. Various types of laser and pulsed light treatments have shown their effectiveness but can also aggravate pigmentation. CONCLUSION: Dyschromia after burn remains a therapeutic challenge. Hyperpigmentations after burn should be treated on a case-by-case basis, using data from the literature, clinical experience and measuring the risk/benefit ratio.

High doses of tyramine stimulate glucose transport in human fat cells

Among the dietary amines present in foods and beverages, tyramine has been widely studied since its excessive ingestion can cause catecholamine release and hypertensive crisis. However, tyramine exerts other actions than depleting nerve endings: it activates subtypes of trace amine associated receptors (TAARs) and is oxidized by monoamine oxidases (MAO). Although we have recently described that tyramine is antilipolytic in human adipocytes, no clear evidence has been reported about its effects on glucose transport in the same cell model, while tyramine mimics various insulin-like effects in rodent fat cells, such as activation of glucose transport, lipogenesis, and adipogenesis. Our aim was therefore to characterize the effects of tyramine on glucose transport in human adipocytes. The uptake of the non-metabolizable analogue 2-deoxyglucose (2-DG) was explored in adipocytes from human subcutaneous abdominal adipose tissue obtained from women undergoing reconstructive surgery. Human insulin used as reference agent multiplied by three times the basal 2-DG uptake. Tyramine was ineffective from 0.01 to 10 µM and stimulatory at 100 µM-1 mM, without reaching the maximal effect of insulin. This partial insulin-like effect was not improved by vanadium and was impaired by MAO-A and MAO-B inhibitors. Contrarily to benzylamine, mainly oxidized by semicarbazide-sensitive amine oxidase (SSAO), tyramine activation of glucose transport was not inhibited by semicarbazide. Tyramine effect was not dependent on the Gi-coupled receptor activation but was impaired by antioxidants and reproduced by hydrogen peroxide. In all, the oxidation of high doses of tyramine, already reported to inhibit lipolysis in human fat cells, also partially mimic another effect of insulin in these cells, the glucose uptake activation. Thus, other MAO substrates are potentially able to modulate carbohydrate metabolism. (AU)

High doses of catecholamines activate glucose transport in human adipocytes independently from adrenoceptor stimulation or vanadium addition.

BACKGROUND: When combined with vanadium salts, catecholamines strongly activate glucose uptake in rat and mouse adipocytes. AIM: To test whether catecholamines activate glucose transport in human adipocytes. METHODS: The uptake of 2-deoxyglucose (2-DG) was measured in adipocytes isolated from pieces of abdominal subcutaneous tissue removed from women undergoing reconstructive surgery. Pharmacological approaches with amine oxidase inhibitors, adrenoreceptor agonists and antioxidants were performed to unravel the mechanisms of action of noradrenaline or adrenaline (also named epinephrine). RESULTS: In human adipocytes, 45-min incubation with 100 µmol/L adrenaline or noradrenaline activated 2-DG uptake up to more than one-third of the maximal response to insulin. This stimulation was not reproduced with millimolar doses of dopamine or serotonin and was not enhanced by addition of vanadate to the incubation medium. Among various natural amines and adrenergic agonists tested, no other molecule was more efficient than adrenaline and noradrenaline in stimulating 2-DG uptake. The effect of the catecholamines was not impaired by pargyline and semicarbazide, contrarily to that of benzylamine or methylamine, which are recognized substrates of semicarbazide-sensitive amine oxidase. Hydrogen peroxide at 1 mmol/L activated hexose uptake but not pyrocatechol or benzoquinone, and only the former was potentiated by vanadate. Catalase and the phosphoinositide 3-kinase inhibitor wortmannin inhibited adrenaline-induced activation of 2-DG uptake. CONCLUSION: High doses of catecholamines exert insulin-like actions on glucose transport in human adipocytes. At submillimolar doses, vanadium did not enhance this catecholamine activation of glucose transport. Consequently, this dismantles our previous suggestion to combine the metal ion with catecholamines to improve the benefit/risk ratio of vanadium-based antidiabetic approaches.

High doses of tyramine stimulate glucose transport in human fat cells.

Among the dietary amines present in foods and beverages, tyramine has been widely studied since its excessive ingestion can cause catecholamine release and hypertensive crisis. However, tyramine exerts other actions than depleting nerve endings: it activates subtypes of trace amine associated receptors (TAARs) and is oxidized by monoamine oxidases (MAO). Although we have recently described that tyramine is antilipolytic in human adipocytes, no clear evidence has been reported about its effects on glucose transport in the same cell model, while tyramine mimics various insulin-like effects in rodent fat cells, such as activation of glucose transport, lipogenesis, and adipogenesis. Our aim was therefore to characterize the effects of tyramine on glucose transport in human adipocytes. The uptake of the non-metabolizable analogue 2-deoxyglucose (2-DG) was explored in adipocytes from human subcutaneous abdominal adipose tissue obtained from women undergoing reconstructive surgery. Human insulin used as reference agent multiplied by three times the basal 2-DG uptake. Tyramine was ineffective from 0.01 to 10 µM and stimulatory at 100 µM-1 mM, without reaching the maximal effect of insulin. This partial insulin-like effect was not improved by vanadium and was impaired by MAO-A and MAO-B inhibitors. Contrarily to benzylamine, mainly oxidized by semicarbazide-sensitive amine oxidase (SSAO), tyramine activation of glucose transport was not inhibited by semicarbazide. Tyramine effect was not dependent on the Gi-coupled receptor activation but was impaired by antioxidants and reproduced by hydrogen peroxide. In all, the oxidation of high doses of tyramine, already reported to inhibit lipolysis in human fat cells, also partially mimic another effect of insulin in these cells, the glucose uptake activation. Thus, other MAO substrates are potentially able to modulate carbohydrate metabolism.

Flap Venous Congestion and Salvage Techniques: A Systematic Literature Review.

Venous congestion is a frequent problem in flap surgery. Other than surgical revision, there are a multitude of procedures in the literature to tackle this problem, but their effectiveness is not clear. Through a systematic review, we aimed to identify and evaluate the different interventions available for managing flap venous congestion. METHODS: The MEDLINE, PubMed central, Embase, and Cochrane databases were searched. The study selection process was adapted from the PRISMA statement. All English and French original articles describing or comparing a method for managing flap venous congestion were included. For each article, a level of evidence was assigned, as defined by the Oxford Centre for Evidence-based Medicine. Lastly, we specifically analyzed the effectiveness of postoperative non-surgical methods. No formal analysis was performed. RESULTS: Through literature searches carried out in various databases, we identified 224 articles. Finally, 72 articles were included. The majority of these studies had a low-level evidence. A total of 17 different methods (7 pre- and intraoperative, and 10 postoperative) were found. Concerning non-surgical methods, the most represented were leeches, local subcutaneous injection of heparin with scarification, venocutaneous catheterization, negative pressure therapy, and hyperbaric oxygen therapy. CONCLUSIONS: Risks of venous congestion of flaps must always be present in a surgeon's mind, at every stage of flap surgery. Apart from studies on the use of leeches, which have a significant follow-up and large enough patient numbers to support their efficacy, the low-level evidence associated with studies of other methods of venous congestion management does not allow us to draw a scientifically valid conclusion about their effectiveness.

Is the dorsal vascular system sufficient to vascularize the entire teguments of the thumb?

PURPOSE: Simultaneous lesions of both proper digital arteries of the thumb are common in hand trauma surgery. The purpose of this anatomical study was to determine if the dorsal arterial network could be sufficient to ensure the vascularization of the thumb skin sheath. METHODS: We carried out a cadaveric study on 22 hands. The ulnar and radial proper digital arteries of the thumb were ligated at the base of the first phalanx. Red dye was injected into the radial artery and blue dye into the ulnar artery at the wrist level. Visual evaluation of skin staining and systematic photographs was done at 1, 3 and 10 min after injection of dyes. RESULTS: Staining of the thumb sheath was obtained in 100% of the dissections and complete in 91.91% of cases. Staining originated from mixed radial and ulnar artery origins in 81.82% of cases. It was incomplete in 9.09% of cases with a missing on the dorsoradial edge of the proximal phalanx. In one dissection, the whole hand skin was only stained red, and in another dissection only stained blue. CONCLUSION: The dorsal vascular network ensures the substitution of the skin vascularization in more than 90% of cases when ligating the proper digital arteries of the thumb. A clinical impression of good skin vascularization after injury of both proper digital arteries might lead the surgeon not to perform systematic revascularization, but the risk of variable damages of adjacent tissues due to an interruption of one major arterial system requires a palmar arterial anastomosis whenever possible.

Correcting of Calf Atrophy With a Custom-Made Silicone Implant: Contribution of Three-Dimensional Computer-Aided Design Reconstruction: A Pilot Study.

BACKGROUND: Calf shape is an essential aesthetic parameter of the leg, and calf atrophy can lead to complex problems. The functional consequences of calf atrophy are generally moderate. Prefilled silicone gel implants represent the vast majority of currently placed prostheses, but this technique does not ensure optimal adaptation of the implant shape due to loss of volume. OBJECTIVES: The aim of this study was to describe an innovative procedure for correcting acquired calf atrophy based on 3-dimensional (3D) modeling. METHODS: The study involved 22 patients treated for calf atrophy caused by illness. Implants were made with solid rubber silicone, and 3D reconstructions were created by computer-aided design based on computed tomography scans. The implants were introduced through a horizontal popliteal incision. RESULTS: Forty-one implants were placed. No cases of infection, hematoma, or compartment syndrome were encountered. We experienced 1 case of skin necrosis and 1 case of periprosthetic seroma. In addition, lipofilling was performed in 5 cases. Two patients sought to benefit from a surgical reduction in implant size. CONCLUSIONS: Our innovative procedure to correct calf atrophy with custom solid rubber silicone implants produces a calf shape that better adapts to volume loss than prefilled silicone gel implants. The material maintains its shape and facilitates retrofitting of the prosthesis. There is no risk of hull formation or breakage, and the life span of the implants is limitless. This 3D computer-aided design approach has optimized our reconstructions.

Development and characterization of a human Th17-driven ex vivo skin inflammation model.

Skin models mimicking features of psoriasis-related inflammation are needed to support the development of new drugs in dermatology. Reconstructed skin models lack tissue complexity, including a fully competent skin barrier, and presence and/or diversity of immune cells. Here, we describe InflammaSkin®, a novel human Th17-driven ex vivo skin inflammation model. In this model, skin-resident T cells are in situ activated by intradermal injection of anti-CD3 and anti-CD28 antibodies and Th17 cell polarization is sustained by culture in a chemically defined medium supplemented with IL-1ß, IL-23 and TGF-ß for seven days. The acquired Th17 signature is demonstrated by the sustained secretion of IL-17A, IL-17AF, IL-17F, IL-22, IFN-γ, and to some degree IL-15 and TNF-α observed in the activated ex vivo skin inflammation model compared with the non-activated skin model control. Furthermore, expression of S100A7 and Keratin-16 by keratinocytes and loss of epidermal structure integrity occur subsequently to in situ Th17cell activation, demonstrating cellular crosstalk between Th17 cells and keratinocytes. Finally, we demonstrate the use of this model to investigate the modulation of the IL-23/IL-17 immune axis by topically applied anti-inflammatory compounds. Taken together, we show that by in situ activation of skin-resident Th17 cells, the InflammaSkin® model reproduces aspects of inflammatory responses observed in psoriatic lesions and could be used as a translational tool to assess efficacy of test compounds.

Methylxanthines Inhibit Primary Amine Oxidase and Monoamine Oxidase Activities of Human Adipose Tissue.

Background: Methylxanthines including caffeine and theobromine are widely consumed compounds and were recently shown to interact with bovine copper-containing amine oxidase. To the best of our knowledge, no direct demonstration of any interplay between these phytochemicals and human primary amine oxidase (PrAO) has been reported to date. We took advantage of the coexistence of PrAO and monoamine oxidase (MAO) activities in human subcutaneous adipose tissue (hScAT) to test the interaction between several methylxanthines and these enzymes, which are involved in many key pathophysiological processes. Methods: Benzylamine, methylamine, and tyramine were used as substrates for PrAO and MAO in homogenates of subcutaneous adipose depots obtained from overweight women undergoing plastic surgery. Methylxanthines were tested as substrates or inhibitors by fluorimetric determination of hydrogen peroxide, an end-product of amine oxidation. Results: Semicarbazide-sensitive PrAO activity was inhibited by theobromine, caffeine, and isobutylmethylxanthine (IBMX) while theophylline, paraxanthine, and 7-methylxanthine had little effect. Theobromine inhibited PrAO activity by 54% at 2.5 mM. Overall, the relationship between methylxanthine structure and the degree of inhibition was similar to that seen with bovine PrAO, although higher concentrations (mM) were required for inhibition. Theobromine also inhibited oxidation of tyramine by MAO, at the limits of its solubility in a DMSO vehicle. At doses higher than 12 % v/v, DMSO impaired MAO activity. MAO was also inhibited by millimolar doses of IBMX, caffeine and by other methylxanthines to a lesser extent. Conclusions: This preclinical study extrapolates previous findings with bovine PrAO to human tissues. Given that PrAO is a potential target for anti-inflammatory drugs, it indicates that alongside phosphodiesterase inhibition and adenosine receptor antagonism, PrAO and MAO inhibition could contribute to the health benefits of methylxanthines, especially their anti-inflammatory effects.

Opipramol Inhibits Lipolysis in Human Adipocytes without Altering Glucose Uptake and Differently from Antipsychotic and Antidepressant Drugs with Adverse Effects on Body Weight Control.

Treatment with several antipsychotic drugs exhibits a tendency to induce weight gain and diabetic complications. The proposed mechanisms by which the atypical antipsychotic drug olanzapine increases body weight include central dysregulations leading to hyperphagia and direct peripheral impairment of fat cell lipolysis. Several investigations have reproduced in vitro direct actions of antipsychotics on rodent adipocytes, cultured preadipocytes, or human adipose tissue-derived stem cells. However, to our knowledge, no such direct action has been described in human mature adipocytes. The aim of the present study was to compare in human adipocytes the putative direct alterations of lipolysis by antipsychotics (haloperidol, olanzapine, ziprazidone, risperidone), antidepressants (pargyline, phenelzine), or anxiolytics (opipramol). Lipolytic responses to the tested drugs, and to recognized lipolytic (e.g., isoprenaline) or antilipolytic agents (e.g., insulin) were determined, together with glucose transport and amine oxidase activities in abdominal subcutaneous adipocytes from individuals undergoing plastic surgery. None of the tested drugs were lipolytic. Surprisingly, only opipramol exhibited substantial antilipolytic properties in the micromolar to millimolar range. An opipramol antilipolytic effect was evident against isoprenaline-, forskolin-, or atrial natriuretic peptide-stimulated lipolysis. Opipramol did not impair insulin activation of glucose transport but inhibited monoamine oxidase (MAO) activity to the same extent as antidepressants recognized as MAO inhibitors (pargyline, harmine, or phenelzine), whereas antipsychotics were inefficient. Considering its unique properties, opipramol, which is not associated with weight gain in treated patients, is a good candidate for drug repurposing because it limits exaggerated lipolysis, prevents hydrogen peroxide release by amine oxidases in adipocytes, and is thereby of potential use to limit lipotoxicity and oxidative stress, two deleterious complications of diabetes and obesity.

Growth and differentiation factor 15 is secreted by skeletal muscle during exercise and promotes lipolysis in humans.

We hypothesized that skeletal muscle contraction produces a cellular stress signal, triggering adipose tissue lipolysis to sustain fuel availability during exercise. The present study aimed at identifying exercise-regulated myokines, also known as exerkines, able to promote lipolysis. Human primary myotubes from lean healthy volunteers were submitted to electrical pulse stimulation (EPS) to mimic either acute intense or chronic moderate exercise. Conditioned media (CM) experiments with human adipocytes were performed. CM and human plasma samples were analyzed using unbiased proteomic screening and/or ELISA. Real-time qPCR was performed in cultured myotubes and muscle biopsy samples. CM from both acute intense and chronic moderate exercise increased basal lipolysis in human adipocytes. Growth and differentiation factor 15 (GDF15) gene expression and secretion increased rapidly upon skeletal muscle contraction. GDF15 protein was upregulated in CM from both acute and chronic exercise-stimulated myotubes. We further showed that physiological concentrations of recombinant GDF15 protein increased lipolysis in human adipose tissue, while blocking GDF15 with a neutralizing antibody abrogated EPS CM-mediated lipolysis. We herein provide the first evidence to our knowledge that GDF15 is a potentially novel exerkine produced by skeletal muscle contraction and able to target human adipose tissue to promote lipolysis.

Management of Pilonidal Sinus Disease with the Aesthetically Shaped Parasacral Perforator Flap: Multicenter Evaluation of 228 Patients.

BACKGROUND: The management of pilonidal sinus disease is still not standardized. Currently, the two main procedures are a lay-open excision procedure with secondary healing or coverage with local flaps. The authors present their experience with a one-stage excision-coverage with an innovative parasacral artery perforator flap propeller designed to respect the aesthetic unity of the buttocks. METHODS: Study patients were managed with this procedure in the Toulouse, Montpellier, and Rennes university hospitals between 2012 and 2018. Data were collected on clinical and surgical details, immediate and late postoperative complications, and long-term recurrence. Aesthetic satisfaction was evaluated with a self-evaluation questionnaire. RESULTS: The authors operated on 228 consecutive patients for pilonidal sinus disease with an aesthetically shaped parasacral artery perforator flap. The median patient age was 23.5 years, the median operative time was 46 minutes, the median flap length was 9.3 cm (range, 6.5 to 14 cm), and the median flap width was 4.1 cm (range, 4 to 6.5 cm). There were five distal necroses but no complete flap necrosis. There were six postoperative hematomas, 11 infections, and 18 wound dehiscences. The median follow-up period was 27.9 months. Median hospital length of stay was 4.2 days. Three recurrences of pilonidal sinus disease and six instances of hidradenitis suppurativa were detected. Approximately 82 percent of the women and more than 85 percent of the men were "satisfied" or "very satisfied" with the aesthetic outcome, without significant differences between the sexes (p = 0.901). CONCLUSIONS: The aesthetically shaped parasacral artery perforator flap combines very satisfactory results regarding recurrence and postoperative recovery with cosmetic outcome. This procedure is technically more demanding than other flap procedures, although it is accessible to numerous surgeons as the first-line treatment for pilonidal sinus disease after initial learning. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.

Methylamine Activates Glucose Uptake in Human Adipocytes Without Overpassing Action of Insulin or Stimulating its Secretion in Pancreatic Islets.

Background: Methylamine, a natural soluble amine present in foods, is known to be a substrate of primary amine oxidase (PrAO) widely expressed in animal tissues. Methylamine has been reported to activate glucose transport in fat cells and to facilitate glucose disposal in rabbits but the interests and limits of such insulin-mimicking actions have not been further explored. This work aimed to perform a preclinical study of the inter-individual variations of these biological properties to study the putative link between PrAO activity and insulin resistance. Methods: Methylamine was tested on human adipocyte preparations and in rabbit pancreatic islets to determine its influence on glucose uptake and insulin release, respectively. PrAO activity and related responses were determined in adipose tissues obtained from two cohorts of non-obese and obese women. Results: Adipose tissue PrAO activity was negatively correlated with insulin resistance in high-risk obese women. PrAO-dependent activation of glucose uptake was negatively correlated with body mass index and reflected the decrease of insulin responsiveness of human fat cells with increasing obesity. Methylamine exhibited antilipolytic properties in adipocytes but was unable to directly activate insulin secretion in isolated pancreatic islets. Conclusions: PrAO activation by its substrates, e.g., methylamine, increases glucose utilization in human adipocytes in a manner that is linked to insulin responsiveness. Methylamine/PrAO interaction can therefore contribute to adipose tissue enlargement but should be considered as potentially useful for diabetes prevention since it could limit lipotoxicity and facilitate glucose handling, at the expense of favoring healthy fat accumulation.