Role of IL-27 in Epstein-Barr virus infection revealed by IL-27RA deficiency.

Epstein-Barr virus (EBV) infection can engender severe B cell lymphoproliferative diseases1,2. The primary infection is often asymptomatic or causes infectious mononucleosis (IM), a self-limiting lymphoproliferative disorder3. Selective vulnerability to EBV has been reported in association with inherited mutations impairing T cell immunity to EBV4. Here we report biallelic loss-of-function variants in IL27RA that underlie an acute and severe primary EBV infection with a nevertheless favourable outcome requiring a minimal treatment. One mutant allele (rs201107107) was enriched in the Finnish population (minor allele frequency = 0.0068) and carried a high risk of severe infectious mononucleosis when homozygous. IL27RA encodes the IL-27 receptor alpha subunit5,6. In the absence of IL-27RA, phosphorylation of STAT1 and STAT3 by IL-27 is abolished in T cells. In in vitro studies, IL-27 exerts a synergistic effect on T-cell-receptor-dependent T cell proliferation7 that is deficient in cells from the patients, leading to impaired expansion of potent anti-EBV effector cytotoxic CD8+ T cells. IL-27 is produced by EBV-infected B lymphocytes and an IL-27RA-IL-27 autocrine loop is required for the maintenance of EBV-transformed B cells. This potentially explains the eventual favourable outcome of the EBV-induced viral disease in patients with IL-27RA deficiency. Furthermore, we identified neutralizing anti-IL-27 autoantibodies in most individuals who developed sporadic infectious mononucleosis and chronic EBV infection. These results demonstrate the critical role of IL-27RA-IL-27 in immunity to EBV, but also the hijacking of this defence by EBV to promote the expansion of infected transformed B cells.

mBeRFP: a versatile fluorescent tool to enhance multichannel live imaging and its applications.

Cell and developmental biology increasingly require live imaging of protein dynamics in cells, tissues or living organisms. Thanks to the discovery and development of a panel of fluorescent proteins over the last decades, live imaging has become a powerful and commonly used approach. However, multicolor live imaging remains challenging. The generation of long Stokes shift red fluorescent proteins offers interesting new perspectives to bypass this limitation. Here, we provide a detailed characterization of mBeRFP for in vivo live imaging and its applications in Drosophila. Briefly, we show that a single illumination source is sufficient to stimulate mBeRFP and GFP simultaneously. We demonstrate that mBeRFP can be easily combined with classical green and red fluorescent proteins without any crosstalk. We also show that the low photobleaching of mBeRFP is suitable for live imaging, and that this protein can be used for quantitative applications, such as FRAP or laser ablation. Finally, we believe that this fluorescent protein, with the set of new possibilities it offers, constitutes an important tool for cell, developmental and mechano-biologists in their current research.

Antimicrobial activity of mucosal-associated invariant T cells.

Mucosal-associated invariant T lymphocytes (MAIT lymphocytes) are characterized by two evolutionarily conserved features: an invariant T cell antigen receptor (TCR) alpha-chain and restriction by the major histocompatibility complex (MHC)-related protein MR1. Here we show that MAIT cells were activated by cells infected with various strains of bacteria and yeast, but not cells infected with virus, in both humans and mice. This activation required cognate interaction between the invariant TCR and MR1, which can present a bacteria-derived ligand. In humans, we observed considerably fewer MAIT cells in blood from patients with bacterial infections such as tuberculosis. In the mouse, MAIT cells protected against infection by Mycobacterium abscessus or Escherichia coli. Thus, MAIT cells are evolutionarily conserved innate-like lymphocytes that sense and help fight off microbial infection.

An extract of Leontopodium alpinum inhibits catagen development ex vivo and increases hair density in vivo.

OBJECTIVES: Hair loss and reduction in hair volume are hallmarks of hair disorders, such as telogen effluvium, or male or female pattern hair loss, and hair ageing, which can cause severe distress in both men and women. Common anti-hair loss drugs carry some side effects; therefore, novel, safer approaches targeting milder phenotypes are highly advocated. In this context, we investigated an extract of the alpine plant Edelweiss, Leontopodium alpinum var. Helvetia, for its ability to modulate hair follicle (HF) growth ex vivo and inhibit hair loss while increasing hair regeneration in vivo. METHODS: Human amputated HFs were microdissected from three donors, two women and one man, and cultured ex vivo for 6 days. After treatment with 0.001% Edelweiss extract (EWDE), we investigated hair shaft production and anagen/catagen conversion, and measured known parameters associated with hair growth, that is hair matrix keratinocyte proliferation and apoptosis, dermal papilla inductivity, and growth factors, by quantitative (immuno)histomorphometry. To assess the anti-hair loss potential of the alpine plant compound, we performed a randomized, placebo-controlled human study enrolling Caucasian women and men, aged 18 to 65 years, with normal hair loss. After 5 months' daily use of an extract containing leave-on serum, we analysed hair density and anagen-to-catagen/telogen ratio by the Trichogram analysis. RESULTS: Our results revealed a significant prolongation in the anagen phase in HFs treated with 0.001% Edelweiss, as indicated by an increase in HFs remaining in anagen and a significant decrease in hair cycle score. In line with this effect, EWDE significantly stimulated hair matrix (HM) keratinocyte proliferation, and dermal papilla inductivity, as shown by a significant up-regulation of versican expression and alkaline phosphatase activity, and a tendential increase in FGF7 immunoreactivity in the dermal papilla of all HFs or only anagen VI HFs. Corroborating the ex vivo results, we observed a significant increase in growing hair shaft numbers (hair density) after treatment with Edelweiss extract formulation, and a tendential up-regulation in the anagen-to-catagen/telogen ratio. CONCLUSIONS: We show here, through several lines of evidence, that the selected extract of the alpine plant Leontopodium alpinum var Helvetia (Edelweiss) inhibits premature catagen induction, possibly by stimulating dermal papilla inductivity. It is therefore worth exploiting this extract clinically as an anti-hair loss agent, both for preventing ageing-associated hair shedding and as an adjuvant therapy for hair loss disorders.

OBJECTIFS: La perte de cheveux et la réduction du volume des cheveux sont caractéristiques des troubles capillaires, tels que l'effluvium télogène, ou la calvitie chez l'homme ou la femme, et le vieillissement des cheveux, qui peuvent causer une certaine détresse chez les hommes et les femmes. Les médicaments courants contre la chute des cheveux ont des effets secondaires, par conséquent, de nouvelles approches plus sûres ciblant des phénotypes légers sont fortement recommandées. Dans ce contexte, nous avons étudié un extrait de la plante alpine Edelweiss, Leontopodium alpinum var. Helvetia, pour sa capacité à stimuler la croissance du follicule pileux (HF) ex vivo et à inhiber la chute des cheveux tout en augmentant la régénération des fibres capillaires in vivo. MÉTHODES: Les follicules pileux (HF) humains prélevés ont été microdisséqués chez trois donneurs, deux femmes et un homme, et cultivés ex vivo pendant 6 jours. Après le traitement avec l'extrait d'Edelweiss à 0,001 % (EWDE), nous avons étudié la production de fibre capillaire et la conversion anagène/catagène, ainsi que mesuré les paramètres connus associés à la croissance des cheveux, à savoir, la prolifération des kératinocytes dans la matrice capillaire et l'apoptose, l'induction des papilles dermiques, et des facteurs de croissance, par (immuno-)histomorphométrie quantitative. Pour évaluer le potentiel des propriétés anti-chute du cheveu de l'extrait de plante alpine, nous avons réalisé une étude clinique aléatoire avec placebo, sur des femmes et des hommes de type caucasien âgés de 18 à 65 ans présentant une perte de cheveux normale. Après cinq mois d'utilisation quotidienne d'un sérum sans rinçage contenant l'extrait de plante, nous avons analysé la densité capillaire et le rapport anagène à catagène/télogène par trichogramme. RÉSULTATS: Nos résultats ont révélé une prolongation significative de la phase anagène dans les HF traités avec 0,001% d'Edelweiss, comme l'indique une augmentation des HF restant en phase anagène et une diminution significative du « hair cycle score ¼. En ligne avec cet effet, EWDE a stimulé de façon significative la matrice du cheveux (HM), la prolifération des kératinocytes, et l'induction de la papille dermique, comme le montre une augmentation significative de l'expression du versican et de l'activité de la phosphatase alcaline, et une augmentation tendancielle de l'immunoréactivité FGF7 dans la papille dermique de tous les HF ou seulement des HF anagènes VI. Corroborant les résultats ex vivo, nous avons observé une augmentation significative du nombre de fibres capillaires (densité de cheveux) après le traitement avec la formulation d'extrait d'Edelweiss, et une augmentation tendancielle dans le rapport anagène à catagène/télogène. CONCLUSIONS: Nous montrons ici, à travers plusieurs éléments de preuve, que l'extrait sélectionné de la plante alpine Leontopodium alpinum var Helvetia (Edelweiss) inhibe l'induction prématurée de la phase catagène, en stimulant la papille dermique. Il est donc possible d'utiliser cet extrait comme un agent anti-chute, à la fois pour prévenir la chute des cheveux associée au vieillissement mais aussi comme une thérapie complémentaire pour les troubles liés à la perte des cheveux.

CTP synthase 1 deficiency in humans reveals its central role in lymphocyte proliferation.

Lymphocyte functions triggered by antigen recognition and co-stimulation signals are associated with a rapid and intense cell division, and hence with metabolism adaptation. The nucleotide cytidine 5' triphosphate (CTP) is a precursor required for the metabolism of DNA, RNA and phospholipids. CTP originates from two sources: a salvage pathway and a de novo synthesis pathway that depends on two enzymes, the CTP synthases (or synthetases) 1 and 2 (CTPS1 with CTPS2); the respective roles of these two enzymes are not known. CTP synthase activity is a potentially important step for DNA synthesis in lymphocytes. Here we report the identification of a loss-of-function homozygous mutation (rs145092287) in CTPS1 in humans that causes a novel and life-threatening immunodeficiency, characterized by an impaired capacity of activated T and B cells to proliferate in response to antigen receptor-mediated activation. In contrast, proximal and distal T-cell receptor (TCR) signalling events and responses were only weakly affected by the absence of CTPS1. Activated CTPS1-deficient cells had decreased levels of CTP. Normal T-cell proliferation was restored in CTPS1-deficient cells by expressing wild-type CTPS1 or by addition of exogenous CTP or its nucleoside precursor, cytidine. CTPS1 expression was found to be low in resting T cells, but rapidly upregulated following TCR activation. These results highlight a key and specific role of CTPS1 in the immune system by its capacity to sustain the proliferation of activated lymphocytes during the immune response. CTPS1 may therefore represent a therapeutic target of immunosuppressive drugs that could specifically dampen lymphocyte activation.

The transcription factor PLZF directs the effector program of the NKT cell lineage.

The transcriptional control of CD1d-restricted NKT cell development has remained elusive. We report that PLZF (promyelocytic leukemia zinc finger, Zbtb16), a member of the BTB/POZ-ZF family of transcription factors that includes the CD4-lineage-specific c-Krox (Th-POK), is exquisitely specific to CD1d-restricted NKT cells and human MR1-specific MAIT cells. PLZF was induced immediately after positive selection of NKT cell precursors, and PLZF-deficient NKT cells failed to undergo the intrathymic expansion and effector differentiation that characterize their lineage. Instead, they preserved a naive phenotype and were directed to lymph nodes. Conversely, transgenic expression of PLZF induced CD4(+) thymocytes to acquire effector differentiation and migrate to nonlymphoid tissues. We suggest that PLZF is a transcriptional signature of NKT cells that directs their innate-like effector differentiation during thymic development.

SYK expression endows human ZAP70-deficient CD8 T cells with residual TCR signaling.

Autosomal recessive human ZAP70 deficiency is a rare cause of combined immunodeficiency (CID) characterized by defective CD4 T cells and profound CD8 T cell lymphopenia. Herein, we report two novel patients that extend the molecular genetics, the clinical and functional phenotypes associated with the ZAP70 deficiency. The patients presented as infant-onset CID with severe infections caused by varicella zoster virus and live vaccines. Retrospective TCR excision circle newborn screening was normal in both patients. One patient carried a novel non-sense mutation (p.A495fsX75); the other a previously described misense mutation (p.A507V). In contrast to CD4 T cells, the majority of the few CD8 T cells showed expression of the ZAP70-related tyrosine kinase SYK that correlated with residual TCR signaling including calcium flux and degranulation. Our findings highlight the differential requirements of ZAP70 and SYK during thymic development, peripheral homeostasis as well as effector functions of CD4 and CD8 T cells.

MAIT cells detect and efficiently lyse bacterially-infected epithelial cells.

Mucosal associated invariant T cells (MAIT) are innate T lymphocytes that detect a large variety of bacteria and yeasts. This recognition depends on the detection of microbial compounds presented by the evolutionarily conserved major-histocompatibility-complex (MHC) class I molecule, MR1. Here we show that MAIT cells display cytotoxic activity towards MR1 overexpressing non-hematopoietic cells cocultured with bacteria. The NK receptor, CD161, highly expressed by MAIT cells, modulated the cytokine but not the cytotoxic response triggered by bacteria infected cells. MAIT cells are also activated by and kill epithelial cells expressing endogenous levels of MRI after infection with the invasive bacteria Shigella flexneri. In contrast, MAIT cells were not activated by epithelial cells infected by Salmonella enterica Typhimurium. Finally, MAIT cells are activated in human volunteers receiving an attenuated strain of Shigella dysenteriae-1 tested as a potential vaccine. Thus, in humans, MAIT cells are the most abundant T cell subset able to detect and kill bacteria infected cells.

Human iNKT and MAIT cells exhibit a PLZF-dependent proapoptotic propensity that is counterbalanced by XIAP.

Invariant natural killer (iNKT) T cells and mucosal-associated invariant T (MAIT) cells represent peculiar T-lymphocyte subpopulations with innate-like properties that differ from conventional T cells. iNKT are reduced in the primary immunodeficiency caused by mutations in the X-linked inhibitor of apoptosis (XIAP). By studying the mechanism of this depletion, we herein report that iNKT cells exhibit a high susceptibility to apoptosis that is not observed with conventional T cells. Elevated expression of caspases 3 and 7 accounts for the proapoptotic phenotype of iNKT cells, which is inhibited by XIAP although it exerts a moderate effect in conventional T cells. Similarly, MAIT cells exhibit a proapoptotic propensity with elevated expression of activated caspases and are decreased in XIAP-deficient individuals. Knockdown of the transcription factor PLZF/ZBTB-16, which is involved in the effector program of iNKT cells, diminishes their proapoptotic phenotype. Conversely, overexpression of PLZF/ZBTB-16 in conventional T cells leads to a proapoptotic phenotype. Our findings identify a previously unknown pathway of regulation of innate-like T-cell homeostasis depending on XIAP and PLZF. The proapoptotic feature of iNKT cells also gives a reliable explanation of their exhaustion observed in different human conditions including the XIAP immunodeficiency.

Copy-neutral loss of heterozygosity and chromosome gains and losses are frequent in gastrointestinal stromal tumors.

BACKGROUND: A KIT gain of function mutation is present in 70% of gastrointestinal stromal tumors (GISTs) and the wild-type (WT) allele is deleted in 5 to 15% of these cases. The WT KIT is probably deleted during GIST progression. We aimed to identify the mechanism of WT KIT loss and to determine whether other genes are involved or affected. METHODS: Whole-genome SNP array analyses were performed in 22 GISTs with KIT exon 11 mutations, including 11 with WT loss, to investigate the mechanisms of WT allele deletion. CGH arrays and FISH were performed in some cases. Common genetic events were identified by SNP data analysis. The 9p21.3 locus was studied by multiplex quantification of genomic DNA. RESULTS: Chromosome instability involving the whole chromosome/chromosome arm (whole C/CA) was detected in 21/22 cases. The GISTs segregated in two groups based on their chromosome number: polyGISTs had numerous whole C/CA gains (mean 23, range [9 to 43]/3.11 [1 to 5]), whereas biGISTs had fewer aberrations. Whole C/CA losses were also frequent and found in both groups. There were numerous copy-neutral losses of heterozygosity (cnLOH) of whole C/CA in both polyGIST (7/9) and biGIST (9/13) groups. cnLOH were frequent on 4q, 11p, 11q, 1p, 2q, 3p and 10, and never involved 12p, 12q, 20p, 20q or 19q. Other genetic alterations included segmental chromosome abnormalities, complete bi-allelic deletions (homozygous deletions) and, more rarely, amplifications. Nine of 11 GISTs with homozygous KIT exon 11 mutations had cnLOH of chromosome 4. CONCLUSION: The cnLOH of whole C/CA is a frequent genetic alteration in GISTs and is closely associated with homozygous mutations of KIT and WT allele deletion.

Mucosal-associated invariant T cells: unconventional development and function.

Mucosal-associated invariant T (MAIT) cells are a population of T cells that display a semi-invariant T cell receptor (TCR) and are restricted by the evolutionarily conserved major histocompatibility complex related molecule, MR1. Here, we review recent knowledge of this T cell population. MAIT cells are abundant in human blood, gut and liver, and display an effector phenotype. They follow an atypical pathway of development and preferentially locate to peripheral tissues. Human and mouse MAIT cells react to bacterially infected cells in an MR1-dependent manner. They migrate to the infection site and can be protective in experimental infection models. MAIT cells secrete interferon-γ, and interleukin-17 under certain conditions. The species conservation, as well as the wide microbial reactivity, infer an important role for this cell population in immunity.

Whole-exome sequencing identifies Coronin-1A deficiency in 3 siblings with immunodeficiency and EBV-associated B-cell lymphoproliferation.

BACKGROUND: Primary immunodeficiencies are a rare group of inborn diseases characterized by a broad clinical and genetic heterogeneity. Substantial advances in the identification of the underlying molecular mechanisms can be achieved through the study of patients with increased susceptibility to specific infections and immune dysregulation. We evaluated 3 siblings from a consanguineous family presenting with EBV-associated B-cell lymphoproliferation at an early age (12, 7½, and 14 months, respectively) and profound naive T-cell lymphopenia. OBJECTIVE: On the basis of the hypothesis of a rare inborn immunodeficiency of autosomal recessive inheritance, we sought to characterize the underlying genetic defect. METHODS: We performed genome-wide homozygosity mapping, followed by whole-exome sequencing. RESULTS: We identified a homozygous inherited missense mutation in the gene encoding Coronin-1A (CORO1A) in the 3 siblings. This mutation, p. V134M, results in the substitution of an evolutionarily conserved amino acid within the ß-propeller domain, which abrogates almost completely the protein expression in the patients' cells. In addition to a significant diminution of naive T-cell numbers, we found impaired development of a diverse T-cell repertoire, near-to-absent invariant natural killer T cells, and severely diminished mucosal-associated invariant T cell numbers. CONCLUSIONS: Our findings define a new clinical entity of a primary immunodeficiency with increased susceptibility to EBV-induced lymphoproliferation in patients associated with hypomorphic Coronin-1A mutation.

Inactivation of cytidine triphosphate synthase 1 prevents fatal auto-immunity in mice.

De novo synthesis of the pyrimidine, cytidine triphosphate (CTP), is crucial for DNA/RNA metabolism and depends on the CTP synthetases, CTPS1 and -2. Partial CTPS1 deficiency in humans has previously been shown to lead to immunodeficiency, with impaired expansion of T and B cells. Here, we examine the effects of conditional and inducible inactivation of Ctps1 and/or Ctps2 on mouse embryonic development and immunity. We report that deletion of Ctps1, but not Ctps2, is embryonic-lethal. Tissue and cells with high proliferation and renewal rates, such as intestinal epithelium, erythroid and thymic lineages, activated B and T lymphocytes, and memory T cells strongly rely on CTPS1 for their maintenance and growth. However, both CTPS1 and CTPS2 are required for T cell proliferation following TCR stimulation. Deletion of Ctps1 in T cells or treatment with a CTPS1 inhibitor rescued Foxp3-deficient mice from fatal systemic autoimmunity and reduced the severity of experimental autoimmune encephalomyelitis. These findings support that CTPS1 may represent a target for immune suppression.

Human MAIT cells are xenobiotic-resistant, tissue-targeted, CD161hi IL-17-secreting T cells.

Mucosal-associated invariant T (MAIT) cells are very abundant in humans and have antimicrobial specificity, but their functions remain unclear. MAIT cells are CD161(hi)IL-18Rα(+) and either CD4(-)CD8(-) (DN) or CD8αß(int) T cells. We now show that they display an effector-memory phenotype (CD45RA(-)CD45RO(+)CD95(hi)CD62L(lo)), and their chemokine receptor expression pattern (CCR9(int)CCR7(-)CCR5(hi)CXCR6(hi)CCR6(hi)) indicates preferential homing to tissues and particularly the intestine and the liver. MAIT cells can represent up to 45% of the liver lymphocytes. They produce interferon-γ and Granzyme-B as well as high levels of interleukin-17 after phorbol myristate acetate + ionomycin stimulation. Most MAIT cells are noncycling cells (< 1% are Ki-67(+)) and express the multidrug resistance transporter (ABCB1). As expected from this phenotype, MAIT cells are more resistant to chemotherapy than other T-cell populations. These features might also allow MAIT cells to resist the xenobiotics potentially secreted by the gut bacteria. We also show that this population does not appear to have antiviral specificity and that CD8 MAIT cells include almost all the ABCB1(+)CD161(hi) CD8 T cells. Together with their already known abundance and antimicrobial specificity, the gut-liver homing characteristics, high expression of ABCB1, and ability to secrete interleukin-17 probably participate in the antibacterial properties of MAIT cells.

Primary T-cell immunodeficiency with immunodysregulation caused by autosomal recessive LCK deficiency.

BACKGROUND: Signals emanating from the antigen T-cell receptor (TCR) are required for T-cell development and function. The T lymphocyte-specific protein tyrosine kinase (Lck) is a key component of the TCR signaling machinery. On the basis of its function, we considered LCK a candidate gene in patients with combined immunodeficiency. OBJECTIVE: We identify and describe a child with a T-cell immunodeficiency caused by a homozygous missense mutation of the LCK gene (c.1022T>C) resulting from uniparental disomy. METHODS: Genetic, molecular, and functional analyses were performed to characterize the Lck deficiency, and the associated clinical and immunologic phenotypes are reported. RESULTS: The mutant LCK protein (p.L341P) was weakly expressed with no kinase activity and failed to reconstitute TCR signaling in LCK-deficient T cells. The patient presented with recurrent respiratory tract infections together with predominant early-onset inflammatory and autoimmune manifestations. The patient displayed CD4(+) T-cell lymphopenia and low levels of CD4 and CD8 expression on the T-cell surface. The residual T lymphocytes had an oligoclonal T-cell repertoire and exhibited a profound TCR signaling defect, with only weak tyrosine phosphorylation signals and no Ca(2+) mobilization in response to TCR stimulation. CONCLUSION: We report a new form of T-cell immunodeficiency caused by a LCK gene defect, highlighting the essential role of Lck in human T-cell development and responses. Our results also point out that defects in the TCR signaling cascade often result in abnormal T-cell differentiation and functions, leading to an important risk factor for inflammation and autoimmunity.

Saccharide isomerate ameliorates cosmetic scalp conditions in a Chinese study population.

BACKGROUND: Scalp conditions such as flaky or oily scalp affect people across ethnicities and age groups. In addition to flaking, increased sebum secretion, itching, and compromised scalp barrier function were described. Scalp conditions are aesthetically disturbing and may cause psychological distress in affected individuals who are looking for mild and effective treatment at the same time. Saccharide isomerate has a long history as a skin moisturizer, and it was found to improve skin barrier function, also suggesting possible beneficial effects on scalp. AIMS: To provide relevant claim substantiation to introduce saccharide isomerate as a new scalp care active against scalp flaking condition. MATERIAL AND METHODS: We conducted a placebo-controlled clinical study in an adult Chinese population affected by dandruff scalp as assessed by an adherent scalp flaking score. We monitored transepidermal water loss (TEWL), sebum secretion, and scalp flaking during 28 days. RESULTS: Formulations containing Saccharide isomerate significantly improved all parameters both over time as well as compared to the placebo formulation. CONCLUSION: We propose Saccharide isomerate for cosmetic formulations directed toward improving scalp conditions such as dandruff or oily scalp.

DISSECT is a tool to segment and explore cell and tissue mechanics in highly deformed 3D epithelia.

Understanding morphogenesis strongly relies on the characterization of tissue topology and mechanical properties deduced from imaging data. The development of new imaging techniques offers the possibility to go beyond the analysis of mostly flat surfaces and image and analyze complex tissue organization in depth. An important bottleneck in this field is the need to analyze imaging datasets and extract quantifications not only of cell and tissue morphology but also of the cytoskeletal network's organization in an automatized way. Here, we describe a method, called DISSECT, for DisPerSE (Discrete Persistent Structure Extractor)-based Segmentation and Exploration of Cells and Tissues, that offers the opportunity to extract automatically, in strongly deformed epithelia, a precise characterization of the spatial organization of a given cytoskeletal network combined with morphological quantifications in highly remodeled three-dimensional (3D) epithelial tissues. We believe that this method, applied here to Drosophila tissues, will be of general interest in the expanding field of morphogenesis and tissue biomechanics.

Differential roles of CTP synthetases CTPS1 and CTPS2 in cell proliferation.

The CTP nucleotide is a key precursor of nucleic acids metabolism essential for DNA replication. De novo CTP production relies on CTP synthetases 1 and 2 (CTPS1 and CTPS2) that catalyze the conversion of UTP into CTP. CTP synthetase activity is high in proliferating cells including cancer cells; however, the respective roles of CTPS1 and CTPS2 in cell proliferation are not known. By inactivation of CTPS1 and/or CTPS2 and complementation experiments, we showed that both CTPS1 and CTPS2 are differentially required for cell proliferation. CTPS1 was more efficient in promoting proliferation than CTPS2, in association with a higher intrinsic enzymatic activity that was more resistant to inhibition by 3-deaza-uridine, an UTP analog. The contribution of CTPS2 to cell proliferation was modest when CTPS1 was expressed but essential in absence of CTPS1. Public databases analysis of more than 1,000 inactivated cancer cell lines for CTPS1 or CTPS2 confirmed that cell growth is highly dependent of CTPS1 but less or not of CTPS2. Therefore, our results demonstrate that CTPS1 is the main contributor to cell proliferation.

Artificial Intelligence for Detecting Acute Fractures in Patients Admitted to an Emergency Department: Real-Life Performance of Three Commercial Algorithms.

RATIONALE AND OBJECTIVES: Interpreting radiographs in emergency settings is stressful and a burden for radiologists. The main objective was to assess the performance of three commercially available artificial intelligence (AI) algorithms for detecting acute peripheral fractures on radiographs in daily emergency practice. MATERIALS AND METHODS: Radiographs were collected from consecutive patients admitted for skeletal trauma at our emergency department over a period of 2 months. Three AI algorithms-SmartUrgence, Rayvolve, and BoneView-were used to analyze 13 body regions. Four musculoskeletal radiologists determined the ground truth from radiographs. The diagnostic performance of the three AI algorithms was calculated at the level of the radiography set. Accuracies, sensitivities, and specificities for each algorithm and two-by-two comparisons between algorithms were obtained. Analyses were performed for the whole population and for subgroups of interest (sex, age, body region). RESULTS: A total of 1210 patients were included (mean age 41.3 ± 18.5 years; 742 [61.3%] men), corresponding to 1500 radiography sets. The fracture prevalence among the radiography sets was 23.7% (356/1500). Accuracy was 90.1%, 71.0%, and 88.8% for SmartUrgence, Rayvolve, and BoneView, respectively; sensitivity 90.2%, 92.6%, and 91.3%, with specificity 92.5%, 70.4%, and 90.5%. Accuracy and specificity were significantly higher for SmartUrgence and BoneView than Rayvolve for the whole population (P < .0001) and for subgroups. The three algorithms did not differ in sensitivity (P = .27). For SmartUrgence, subgroups did not significantly differ in accuracy, specificity, or sensitivity. For Rayvolve, accuracy and specificity were significantly higher with age 27-36 than ≥53 years (P = .0029 and P = .0019). Specificity was higher for the subgroup knee than foot (P = .0149). For BoneView, accuracy was significantly higher for the subgroups knee than foot (P = .0006) and knee than wrist/hand (P = .0228). Specificity was significantly higher for the subgroups knee than foot (P = .0003) and ankle than foot (P = .0195). CONCLUSION: The performance of AI detection of acute peripheral fractures in daily radiological practice in an emergency department was good to high and was related to the AI algorithm, patient age, and body region examined.