Improving the potency of biomaterials for tissue growth

In recent years, it has been shown that synthetic biomaterials are not optimal supports for tissue growth due to their lack of intrinsic biochemical signalling potential. To improve the biological potency of these biomaterials and increase the reach of tissue engineering, key signalling proteins can be attached. However, when these proteins are attached via non-specific conjugation chemistries, they suffer a drastic loss of activity. There is therefore a need for site-selective approaches for protein- biomaterial conjugation. In this PhD, ligand-directed chemistry was studied to achieve this goal, with two new approaches to achieve site selective modification of proteins without the need for protein engineering. The first approach was based on using peptides as protein-binding ligands, while the second approach was based on the use of 2-pyridinecarboxaldehydes as N-terminal targeting ligands. This thesis will first introduce the peptide approach in Chapter 2, with details of the synthesis and modification of the peptides required, then will focus in Chapter 3 on the binding of these modified probes to their protein of interest. In Chapter 4, the use of these binding peptides for the formation of ligand-directed probes will be discussed. Chapter 5 will develop similar chemistry on 2- pyridinecarboxaldehydes, and finally Chapter 6 will describe the results using these two types of probes for the modification of proteins. Our results demonstrate that we can achieve site-selective modification of model proteins, representing the first traceless modification of protein using pyridinium oxime and N-acyl-N- sulphonamide (PyOx/NASA) system on a peptide in a traceless manner. With more optimization still needed, these preliminary results are important for the biomedical field in which protein-biomaterial conjugation is key for the formation of in-vitro tissue models for the study of various disease such as myocardial infarction, diabetes, and osteoarthritis

Photochemical Methods for Peptide Macrocylization

Photochemical reactions have been the subject of renewed interest over the last two decades, leading to the development of many new diverse and powerful chemical transformations. More recently, these developments have been expanded to enable the photochemical macrocylization of peptides and small proteins. These constructs benefit from increased stability, structural rigidity, and biological potency over their linear counterparts, providing opportunities for improved therapeutic agents. In this review, we provide an overview of both the established and emerging methods for photochemical peptide macrocyclization, highlighting both the limitations and opportunities for further innovation in the field

Characterization of neutralizing antibodies reacting with the 213-224 amino-acid segment of human galectin-9.

Extra-cellular galectin-9 (gal-9) is an immuno-modulatory protein with predominant immunosuppressive effects. Inappropriate production of gal-9 has been reported in several human malignancies and viral diseases like nasopharyngeal, pancreatic and renal carcinomas, metastatic melanomas and chronic active viral hepatitis. Therefore therapeutic antibodies neutralizing extra-cellular gal-9 are expected to contribute to immune restoration in these pathological conditions. Two novel monoclonal antibodies targeting gal-9 -Gal-Nab 1 and 2-have been produced and characterized in this study. We report a protective effect of Gal-Nab1 and Gal-Nab2 on the apoptotic cell death induced by gal-9 in primary T cells. In addition, they inhibit late phenotypic changes observed in peripheral T cells that survive gal-9-induced apoptosis. Gal-Nab1 and Gal-Nab2 bind nearly identical, overlapping linear epitopes contained in the 213-224 amino-acid segments of gal-9. Nevertheless, they have some distinct functional characteristics suggesting that their three-dimensional epitopes are distinct. These differences are best demonstrated when gal-9 is applied on Jurkat cells where Gal-Nab1 is less efficient than Gal-Nab2 in the prevention of apoptotic cell death. In addition, Gal-Nab1 stimulates non-lethal phosphatidylserine translocation at the plasma membrane and calcium mobilization triggered by gal-9 in these cells. Both Gal-Nab1 and 2 cross-react with murine gal-9. They bind its natural as well as its recombinant form. This cross-species recognition will be an advantage for their assessment in pre-clinical tumor models

Conservative management or cesarean hysterectomy for placenta accreta spectrum: the PACCRETA prospective study

BackgroundPlacenta accreta spectrum is a life-threatening condition that has increased dramatically in recent decades along with cesarean rates worldwide. Cesarean hysterectomy is widely practiced in women with placenta accreta spectrum; however, the maternal outcomes after cesarean hysterectomy have not been thoroughly compared with the maternal outcomes after alternative approaches, such as conservative management.ObjectiveThis study aimed to compare the severe maternal outcomes between women with placenta accreta spectrum treated with cesarean hysterectomy and those treated with conservative management (leaving the placenta in situ).Study DesignFrom a source population of 520,114 deliveries in 176 hospitals (PACCRETA study), we designed an observational cohort of women with placenta accreta spectrum who had either a cesarean hysterectomy or a conservative management (the placenta left in situ) during cesarean delivery. Clinicians prospectively identified women meeting the inclusion criteria and included them at delivery. Data collection started only after the women had received information and agreed to participate in the study in the immediate postpartum period. The primary outcome was the transfusion of >4 units of packed red blood cells within 6 months after delivery. Secondary outcomes were other maternal complications within 6 months. We used propensity score weighting to account for potential indication bias.ResultsHere, 86 women had conservative management and 62 women had cesarean hysterectomy for placenta accreta spectrum during cesarean delivery. The primary outcome occurred in 14 of 86 women in the conservative management group (16.3%) and 36 of 61 (59.0%) in the cesarean hysterectomy group (risk ratio in propensity score weighted model, 0.29; 95% confidence interval, 0.19–0.45). The rates of hysterectomy, total estimated blood loss exceeding 3000 mL, any blood product transfusion, adjacent organ injury, and nonpostpartum hemorrhage-related severe maternal morbidity were lower with conservative management than with cesarean hysterectomy (all adjusted, P≤.02); but, the rates of arterial embolization, endometritis, and readmission within 6 months of discharge were higher with conservative management than with cesarean hysterectomy.ConclusionAmong women with placenta accreta spectrum who underwent cesarean delivery, conservative management was associated with a lower risk of transfusion of >4 units of packed red blood cells within 6 months than cesarean hysterectomy

Morphology and genomic hallmarks of breast tumours developed by ATM deleterious variant carriers

Abstract Background The ataxia telangiectasia mutated (ATM) gene is a moderate-risk breast cancer susceptibility gene; germline loss-of-function variants are found in up to 3% of hereditary breast and ovarian cancer (HBOC) families who undergo genetic testing. So far, no clear histopathological and molecular features of breast tumours occurring in ATM deleterious variant carriers have been described, but identification of an ATM-associated tumour signature may help in patient management. Methods To characterise hallmarks of ATM-associated tumours, we performed systematic pathology review of tumours from 21 participants from ataxia-telangiectasia families and 18 participants from HBOC families, as well as copy number profiling on a subset of 23 tumours. Morphology of ATM-associated tumours was compared with that of 599 patients with no BRCA1 and BRCA2 mutations from a hospital-based series, as well as with data from The Cancer Genome Atlas. Absolute copy number and loss of heterozygosity (LOH) profiles were obtained from the OncoScan SNP array. In addition, we performed whole-genome sequencing on four tumours from ATM loss-of-function variant carriers with available frozen material. Results We found that ATM-associated tumours belong mostly to the luminal B subtype, are tetraploid and show LOH at the ATM locus at 11q22–23. Unlike tumours in which BRCA1 or BRCA2 is inactivated, tumours arising in ATM deleterious variant carriers are not associated with increased large-scale genomic instability as measured by the large-scale state transitions signature. Losses at 13q14.11-q14.3, 17p13.2-p12, 21p11.2-p11.1 and 22q11.23 were observed. Somatic alterations at these loci may therefore represent biomarkers for ATM testing and harbour driver mutations in potentially ‘druggable’ genes that would allow patients to be directed towards tailored therapeutic strategies. Conclusions Although ATM is involved in the DNA damage response, ATM-associated tumours are distinct from BRCA1-associated tumours in terms of morphological characteristics and genomic alterations, and they are also distinguishable from sporadic breast tumours, thus opening up the possibility to identify ATM variant carriers outside the ataxia-telangiectasia disorder and direct them towards effective cancer risk management and therapeutic strategies

Services culturels et récréatifs

Les écosystèmes agricoles sont l’un des six volets de l’Evaluation française des écosystèmes et des services écosystémiques (EFESE), programme lancé en 2012 par le Ministère en charge de l’Environnement pour apporter des connaissances sur l’état actuel et l’utilisation durable des écosystèmes (voir encadré 2). En 2014, le Ministère de l’Environnement a sollicité l’Inra pour prendre en charge le volet relatif aux écosystèmes agricoles. Le programme fédérateur de recherche EcoSerV (Services rendus par les écosystèmes), lancé par l’Inra en 2013, a également soutenu cette étude qu’il va ensuite compléter et étendre. L’écosystème agricole, vu comme l’ensemble des parcelles dédiées à la production de biomasse agricole, est configuré et géré par l’agriculteur qui combine, dans ses pratiques de production, processus écologiques et apports d’intrants exogènes. L’un des enjeux forts associés à l’analyse des services écosystémiques est la conception de systèmes de production reposant sur la valorisation de ces services, donc peu consommateurs en intrants exogènes et répondant aux enjeux de société tels que la conservation de la biodiversité ou la limitation des impacts environnementaux

Biens produits par l'écosystème

Dans EFESE-écosystèmes agricoles, la production agricole de biomasse végétale n’est pas conceptualisée comme un SE d’approvisionnement mais comme un processus de production de biens agricoles (cf. section 3.1). Le niveau de production agricole résulte des interactions entre les SE de régulation dont bénéficie l’agriculteur, appelés « SE intrants » ci-après, et des apports d’intrants exogènes (ex. énergie du travail du sol, fertilisants et amendements, eau d’irrigation, produits phytosanitaires). Différents modes de production de biens végétaux peuvent être distingués suivant la part relative de la production agricole permise par les SE de régulation pour un niveau de production donnée. Par exemple, il est possible de distinguer les systèmes de production « conventionnels » dont le niveau de production agricole est fortement basé sur les intrants exogènes, des systèmes de production, souvent qualifiés d’« agroécologiques », dont le niveau de production agricole est fortement déterminé par les SE dit « intrants » (Bommarco et al., 2013; Duru et al., 2015a; Gliessman, 2007; Therond et al., 2017)

: Rapport scientifique de l'étude réalisée par l'INRA - Novembre 2017

L’ambition de l’étude Inra "EFESE-EA" est de décrire les mécanismes et déterminants de la fourniture des services écosystémiques par les écosystèmes agricoles sur la base d'une revue des connaissances existantes, et de procéder à leur évaluation à l’échelle nationale sur la base d’indicateurs définis dans le cadre de l’étude. L’organisation du travail, telle que prévue en début d’étude, se voulait séquentielle : (1) identification et spécification biophysiques d’une liste de biens agricoles et services écosystémiques ; (2) évaluation biophysique : quantification du niveau de fourniture des biens et services identifiés à l’étape (1) (3) évaluation économique : quantification de la valeur économique des services (le plus souvent dans une unité monétaire) Dans le temps imparti à l’étude, le collectif d’experts a donné la priorité aux volets biophysiques (1) et (2) afin : - d’instruire de façon robuste la conceptualisation des biens et services (volet 1) : ce travail constitue un front de recherche actuel, associé à une littérature académique abondante mais parfois non stabilisée, que le collectif d’experts s’est attaché à analyser de façon à proposer des choix de conceptualisation argumentés ; - de pousser au maximum l’exercice d’évaluation biophysique (volet 2) dans le cadre de la demande initiale formulée par le MEEM : cartographier la production d’un large panel de biens agricoles et les SE rendus par les écosystèmes agricoles à la résolution spatiale la plus fine possible, et à l’échelle France entière. A noter que le présent exercice ne constituant pas un projet de recherche mais bien une étude institutionnelle Inra (au sens des procédures DEPE), l’ensemble des évaluations développées dans le présent rapport est réalisée à partir de données existantes, aucun travail d’expérimentation visant à acquérir de nouvelles données de terrain n’ayant été conduit. Il résulte de ce choix de priorisation que : - le volet d’évaluation économique (3) est initié pour quelques SE mais peu développé en comparaison des volets (1) et (2) ; - tout en veillant à élaborer des méthodologies d’évaluation biophysiques traçables et robustes, les experts ont pris le parti de proposer des méthodologies plus exploratoires pour quelques SE pour lesquels les données actuelles ne permettent pas d’évaluer directement le niveau de fourniture à l’échelle France entière : dans ces cas particuliers (signalés explicitement dans les sections du rapport dont ils font l’objet), les méthodologies ont été mises en œuvre jusqu’à la réalisation des cartographies dans le but de donner à voir le potentiel qu’offrent ces méthodologies et la nature des résultats qu’elles peuvent produire sous condition de leur validation France entière, plutôt que dans le but d’interpréter pour eux-mêmes les résultats obtenus. Les experts se sont alors particulièrement attachés à relativiser les résultats quantitatifs ainsi produits, et à accompagner les cartographies d’un descriptif détaillé des protocoles de validation qu’il faudrait mettre en œuvre dans les suites de l’étude pour stabiliser et valider ces méthodologies exploratoires. Ce parti pris du groupe de travail EFESE-écosystèmes agricoles est compatible avec l’objectif poursuivi dans le programme EFESE, qui se donne pour objectif de produire un guide méthodologique pour l’évaluation des biens et SE en en pointant les limites, difficultés, précautions et améliorations possibles associées à chacune des pistes avancées