L'épidémiologie entre le terrain des épidémies et l'approche populationnelle, XIX-XXe siècle.

TITLE: L'épidémiologie entre le terrain des épidémies et l'approche populationnelle, XIX-XXe siècle. ABSTRACT: L'émergence d'une épidémiologie moderne est fréquemment associée au basculement de la discipline, d'une science des épidémies vers une science des populations. L'avènement et le développement d'une épidémiologie fondée sur une approche statistique et mathématique n'exclut cependant pas la persistance d'une épidémiologie sur le terrain des épidémies, dans le sillage de l'hygiène publique et de la bactériologie triomphante du tournant des XIXe et XXe siècles. De plus, l'histoire de l'épidémiologie ne saurait être cantonnée à une histoire de savoirs scientifiques ou de savoir-faire techniques et organisationnels. Elle doit intégrer, plus sans doute encore que d'autres branches de la médecine, les dimensions économiques et politiques qui participèrent à l'institutionnalisation et au développement de la discipline et à son inscription dans les processus de décision.

ATP6AP2 variant impairs CNS development and neuronal survival to cause fulminant neurodegeneration.

Vacuolar H+-ATPase-dependent (V-ATPase-dependent) functions are critical for neural proteostasis and are involved in neurodegeneration and brain tumorigenesis. We identified a patient with fulminant neurodegeneration of the developing brain carrying a de novo splice site variant in ATP6AP2 encoding an accessory protein of the V-ATPase. Functional studies of induced pluripotent stem cell-derived (iPSC-derived) neurons from this patient revealed reduced spontaneous activity and severe deficiency in lysosomal acidification and protein degradation leading to neuronal cell death. These deficiencies could be rescued by expression of full-length ATP6AP2. Conditional deletion of Atp6ap2 in developing mouse brain impaired V-ATPase-dependent functions, causing impaired neural stem cell self-renewal, premature neuronal differentiation, and apoptosis resulting in degeneration of nearly the entire cortex. In vitro studies revealed that ATP6AP2 deficiency decreases V-ATPase membrane assembly and increases endosomal-lysosomal fusion. We conclude that ATP6AP2 is a key mediator of V-ATPase-dependent signaling and protein degradation in the developing human central nervous system.

Transcriptome Analysis of Human Reninomas as an Approach to Understanding Juxtaglomerular Cell Biology.

Renin, a key component in the regulation of blood pressure in mammals, is produced by the rare and highly specialized juxtaglomerular cells of the kidney. Chronic stimulation of renin release results in a recruitment of new juxtaglomerular cells by the apparent conversion of adjacent smooth muscle cells along the afferent arterioles. Because juxtaglomerular cells rapidly dedifferentiate when removed from the kidney, their developmental origin and the mechanism that explains their phenotypic plasticity remain unclear. To overcome this limitation, we have performed RNA expression analysis on 4 human renin-producing tumors. The most highly expressed genes that were common between the reninomas were subsequently used for in situ hybridization in kidneys of 5-day-old mice, adult mice, and adult mice treated with captopril. From the top 100 genes, 10 encoding for ligands were selected for further analysis. Medium of human embryonic kidney 293 cells transfected with the mouse cDNA encoding these ligands was applied to (pro)renin-synthesizing As4.1 cells. Among the ligands, only platelet-derived growth factor B reduced the medium and cellular (pro)renin levels, as well as As4.1 renin gene expression. In addition, platelet-derived growth factor B-exposed As4.1 cells displayed a more elongated and aligned shape with no alteration in viability. This was accompanied by a downregulated expression of α-smooth muscle actin and an upregulated expression of interleukin-6, suggesting a phenotypic shift from myoendocrine to inflammatory. Our results add 36 new genes to the list that characterize renin-producing cells and reveal a novel role for platelet-derived growth factor B as a regulator of renin-synthesizing cells.

[Scientific integrity: the French proposals to implement the national charter]. / Intégrité scientifique : les propositions françaises pour mettre en oeuvre la charte nationale. Parler d'intégrité scientifique n'est plus tabou.

Scientific integrity: the french proposals to implement the national charter. Individual responsibility of the researcher in case of scientific misconduct is full. The researcher ensures the integrity of his research. Breaches of scientific integrity have been underestimated or ignored and not treated by research organizations and universities. Since 1999, Inserm has set up a delegation in scientific integrity. The Second World Conference on Research Integrity in Singapore in July 2010, defined the principles and recommendations on scientific integrity. In 2011, a "European code 'of conduct for research integrity was published for the European scientific community. In July 2014, the CNRS has published a guide "Promoting research integrity and responsibility". A national charter of deontology of the research profession was signed in January 2015 by public research organizations. The Secretary of State for Higher Education and Research requested in 2016 a report entitled "Review and proposals to implement the national charter of deontology". The main proposals are based on an explicit recognition of this problem, the appointment of a "scientific integrity" referent in institutions, to coordinate the information and training policy on scientific integrity, and handle allegations of misconduct. A network of these referents should coordinate these actions. The report recommends the creation of a national structure, tentatively named the French Office of Scientific Integrity. A new approach to science was born with digital sciences. Scientific integrity is consubstantial with the opening of science to all.

Intégrité scientifique : les propositions françaises pour mettre en oeuvre la charte nationale. La responsabilité individuelle du chercheur en cas de méconduite scientifique est entière ­ c'est lui qui assure l'intégrité de sa recherche. Les manquements à l'intégrité scientifique ont été sous-estimés, voire ignorés, et non traités par les organismes de recherche et les universités. Dès 1999, l'Inserm a créé une délégation à l'intégrité scientifique. La IIe Conférence mondiale sur l'intégrité scientifique, à Singapour en juillet 2010, a défini les principes et les recommandations en matière d'intégrité scientifique. En 2011, un « code européen ¼ de conduite pour l'intégrité de la recherche a été diffusé à la communauté scientifique européenne. En juillet 2014, le CNRS a publié un guide intitulé Promouvoir une recherche intègre et responsable. La Charte nationale de déontologie des métiers de la recherche a été signée en janvier 2015 par des organismes de recherche publique. Le secrétaire d'État chargé de l'Enseignement supérieur et de la Recherche a demandé en 2016 la rédaction d'un rapport intitulé Bilan et propositions de mises en oeuvre de la charte nationale d'intégrité scientifique. Les principales propositions de ce rapport s'appuient sur une reconnaissance explicite de ce problème, la nomination d'un référent « intégrité scientifique ¼ dans les établissements, pour coordonner la politique d'information et de formation sur l'intégrité scientifique, et gérer les allégations de méconduite. Un réseau de ces référents devrait permettre de coordonner ces actions. Le rapport recommande la création d'une structure nationale, appelée provisoirement l'Office français d'intégrité scientifique. Une nouvelle approche de la science voit le jour avec les sciences numériques. L'intégrité scientifique est consubstantielle à cette ouverture de la science à tous.

A chicken model of pharmacologically-induced Hirschsprung disease reveals an unexpected role of glucocorticoids in enteric aganglionosis.

The enteric nervous system originates from neural crest cells that migrate in chains as they colonize the embryonic gut, eventually forming the myenteric and submucosal plexus. Failure of the neural crest cells to colonize the gut leads to aganglionosis in the terminal gut, a pathological condition called Hirschsprung disease (HSCR) in humans, also known as congenital megacolon or intestinal aganglionosis. One of the characteristics of the human HSCR is its variable penetrance, which may be attributable to the interaction between genetic factors, such as the endothelin-3/endothelin receptor B pathway, and non-genetic modulators, although the role of the latter has not well been established. We have created a novel HSCR model in the chick embryo allowing to test the ability of non-genetic modifiers to alter the HSCR phenotype. Chick embryos treated by phosphoramidon, which blocks the generation of endothelin-3, failed to develop enteric ganglia in the very distal bowel, characteristic of an HSCR-like phenotype. Administration of dexamethasone influenced the phenotype, suggesting that glucocorticoids may be environmental modulators of the penetrance of the aganglionosis in HSCR disease.

[Renal tubular dysgenesis and mutations in the renin-angiotensin system genes]. / Dysgénésie tubulaire rénale et mutations des gènes du système rénine angiotensine.

Renal tubular dysgenesis is a severe disease characterized by the absence of differentiated proximal tubules, leading to fetal anuria and persistent oligohydramnios. The absence of amniotic fluid results in a series of malformations, including facial dysmorphia, limb deformation and also lung hypoplasia, leading to respiratory distress at birth. The disease is linked to mutations in the AGT, REN ACE andAGTR1 genes that compose the renin-angiotensin system (RAS). The absence of functional RAS leads to fetal and neonatal hypotension, renal hypoperfusion, and tubular dysgenesis. The use of cellular models expressing these mutations has advanced our understanding of the structure-function relationship of RAS proteins, notably by showing that defective misfolded proteins undergo either intracellular accumulation and retention, or rapid degradation. Moreover, these studies confirm that ACE has to be inserted in the plasma membrane to be active.

Absence of cell surface expression of human ACE leads to perinatal death.

Renal tubular dysgenesis (RTD) is a recessive autosomal disease characterized most often by perinatal death. It is due to the inactivation of any of the major genes of the renin-angiotensin system (RAS), one of which is the angiotensin I-converting enzyme (ACE). ACE is present as a tissue-bound enzyme and circulates in plasma after its solubilization. In this report, we present the effect of different ACE mutations associated with RTD on ACE intracellular trafficking, secretion and enzymatic activity. One truncated mutant, R762X, responsible for neonatal death was found to be an enzymatically active, secreted form, not inserted in the plasma membrane. In contrast, another mutant, R1180P, was compatible with life after transient neonatal renal insufficiency. This mutant was located at the plasma membrane and rapidly secreted. These results highlight the importance of tissue-bound ACE versus circulating ACE and show that the total absence of cell surface expression of ACE is incompatible with life. In addition, two missense mutants (W594R and R828H) and two truncated mutants (Q1136X and G1145AX) were also studied. These mutants were neither inserted in the plasma membrane nor secreted. Finally, the structural implications of these ACE mutations were examined by molecular modelling, which suggested some important structural alterations such as disruption of intra-molecular non-covalent interactions (e.g. salt bridges).

LPS activates ADAM9 dependent shedding of ACE from endothelial cells.

Angiotensin-I converting enzyme (ACE) is a zinc dependent peptidase with a major role in regulating vasoactive peptide metabolism. ACE, a transmembrane protein, undergoes proteolysis, or shedding, by an as yet unidentified proteinase to release a catalytically active soluble form of the enzyme. Physiologically, soluble ACE in plasma is derived primarily from endothelial cells. We demonstrate that ACE shedding from confluent endothelial cells is increased in response to bacterial lipopolysaccharide, but not phorbol esters. Characterisation of lipopolysaccharide stimulated shedding showed that there is a lag phase before soluble ACE can be detected which is sensitive to inhibitors of translation, NF-κB, TNFα and TNFR-I/II. The shedding phase is less sensitive to these inhibitors, but is ablated by BB-94, a Matrix Metalloproteinase (MMP)/A Disintegrin and Metalloproteinase (ADAM) inhibitor. Tissue Inhibitor of Metalloproteinase (TIMP) profiling suggested a requirement for ADAM9 in lipopolysaccharide induced ACE shedding, which was confirmed by depletion with siRNA. Transient transfection of ADAM9 and ACE cDNAs into HEK293 cells demonstrated that ADAM9 requires both membrane anchorage and its catalytic domain to shed ACE.

Link between adipose tissue angiogenesis and fat accumulation in severely obese subjects.

BACKGROUND: White adipose tissue (WAT) can rapidly expand or regress under different nutritional conditions. The role of angiogenesis in the expandability of human adipose tissue is established. However, whether sc and omental WAT (scWAT and oWAT) angiogenesis could influence fat distribution and metabolic diseases is not known. AIM: The aim of this study was to analyze whether the capacity of angiogenesis in scWAT and oWAT correlates with fat accumulation and fat loss, fat distribution, adipocyte hypertrophy, and metabolic disorders in obese subjects. METHODS: Samples of scWAT and oWAT were obtained during bariatric surgery in 29 obese nondiabetic subjects. Vascular density and inflammatory infiltrate were analyzed by immunohistochemistry, and expression of angiogenic genes was analyzed by quantitative PCR. These parameters were correlated with anthropometric and metabolic parameters. RESULTS: Vascular density of scWAT correlated positively with body mass index, whereas vascular density of the oWAT correlated with waist circumference. There was no correlation of markers of angiogenesis and metabolic disorders. The number of vessels per adipocyte and the expression level of receptor 2 of vascular endothelial growth factor correlated with adipocyte area in scWAT and oWAT. Finally, weight loss after bariatric surgery correlated negatively with adipocyte hypertrophy and vascular density and positively with inflammation and angiogenesis of WAT. CONCLUSION: Angiogenesis may influence WAT expansion and plasticity but does not appear to be involved in the development of insulin resistance in subjects with severe obesity.

Angiopoietin 2 alters pancreatic vascularization in diabetic conditions.

AIMS/HYPOTHESIS: Islet vascularization, by controlling beta-cell mass expansion in response to increased insulin demand, is implicated in the progression to glucose intolerance and type 2 diabetes. We investigated how hyperglycaemia impairs expansion and differentiation of the growing pancreas. We have grafted xenogenic (avian) embryonic pancreas in severe combined immuno-deficient (SCID) mouse and analyzed endocrine and endothelial development in hyperglycaemic compared to normoglycaemic conditions. METHODS: 14 dpi chicken pancreases were grafted under the kidney capsule of normoglycaemic or hyperglycaemic, streptozotocin-induced, SCID mice and analyzed two weeks later. Vascularization was analyzed both quantitatively and qualitatively using either in situ hybridization with both mouse- and chick-specific RNA probes for VEGFR2 or immunohistochemistry with an antibody to nestin, a marker of endothelial cells that is specific for murine cells. To inhibit angiopoietin 2 (Ang2), SCID mice were treated with 4 mg/kg IP L1-10 twice/week. RESULTS: In normoglycaemic condition, chicken-derived endocrine and exocrine cells developed well and intragraft vessels were lined with mouse endothelial cells. When pancreases were grafted in hyperglycaemic mice, growth and differentiation of the graft were altered and we observed endothelial discontinuities, large blood-filled spaces. Vessel density was decreased. These major vascular anomalies were associated with strong over-expression of chick-Ang2. To explore the possibility that Ang2 over-expression could be a key step in vascular disorganization induced by hyperglycaemia, we treated mice with L1-10, an Ang-2 specific inhibitor. Inhibition of Ang2 improved vascularization and beta-cell density. CONCLUSIONS: This work highlighted an important role of Ang2 in pancreatic vascular defects induced by hyperglycaemia.

Enhanced expression of ephrins and thrombospondins in the dermis of patients with early diffuse systemic sclerosis: potential contribution to perturbed angiogenesis and fibrosis.

OBJECTIVE: To determine the skin and fibroblast expression of ephrins (EphB4 and EphrinB2) and thrombospondins (TSPs: TSP1 and TSP2) in patients with SSc. METHODS: All experiments were performed in skin sections and dermal fibroblasts issued from control and clinically involved/non-involved SSc skin biopsies. Dermal fibroblasts were stimulated with hypoxia or TGF-ß, or treated with TGF-ß-neutralizing antibodies. Ephrin and TSP mRNA levels were assessed in skin tissue and dermal fibroblasts by in situ hybridization and quantitative RT-PCR, respectively, and protein levels were assessed by immunohistochemistry and western blots, respectively. RESULTS: Enhanced ephrin and TSP mRNA and protein levels were observed in clinically involved SSc skin. EphrinB2, TSP1 and TSP2 mRNA and protein levels were also up-regulated in non-involved SSc skin. Similar mRNA and protein levels of ephrinB2 and EphB4 were detected in unstimulated and stimulated control and SSc dermal fibroblasts. TSP1 and TSP2 mRNA and protein levels were significantly increased in fibroblasts issued from involved and non-involved SSc skin. This up-regulation was not modified by hypoxic exposure, but was markedly reduced by the addition of TGF-ß-neutralizing antibodies. Stimulation of healthy fibroblasts with TGF-ß significantly increased TSP1 and TSP2 mRNA and protein levels. CONCLUSION: EphB4 and EphrinB2 are up-regulated in clinically involved skin of SSc patients, suggesting their participation in SSc-perturbed angiogenesis. TSP1 and TSP2 are up-regulated in both clinically involved and non-involved SSc skin and are constitutively overexpressed in a TGF-ß-dependent and hypoxia-independent manner in SSc dermal fibroblasts, suggesting their potential early contribution in SSc pathogenesis.