Dietary Cholesterol-Induced Post-Testicular Infertility

This work shows that an overload of dietary cholesterol causes complete infertility in dyslipidemic male mice (the Liver X Receptor-deficient mouse model). Infertility resulted from post-testicular defects affecting the fertilizing potential of spermatozoa. Spermatozoa of cholesterol-fed lxr−/− animals were found to be dramatically less viable and motile, and highly susceptible to undergo a premature acrosome reaction. We also provide evidence, that this lipid-induced infertility is associated with the accelerated appearance of a highly regionalized epididymal phenotype in segments 1 and 2 of the caput epididymidis that was otherwise only observed in aged LXR-deficient males. The epididymal epithelial phenotype is characterized by peritubular accumulation of cholesteryl ester lipid droplets in smooth muscle cells lining the epididymal duct, leading to their transdifferentiation into foam cells that eventually migrate through the duct wall, a situation that resembles the inflammatory atherosclerotic process. These findings establish the high level of susceptibility of epididymal sperm maturation to dietary cholesterol overload and could partly explain reproductive failures encountered by young dyslipidemic men as well as ageing males wishing to reproduce

Impact of Vitamin D Supplementation on Influenza Vaccine Response and Immune Functions in Deficient Elderly Persons: A Randomized Placebo-Controlled Trial

Background: Immunosenescence contributes to reduced vaccine response in elderly persons, and is worsened by deficiencies in nutrients such as Vitamin (Vit-D). The immune system is a well-known target of Vit-D, which can both potentiate the innate immune response and inhibit the adaptive system, and so modulate vaccination response.Objective: This randomized placebo-controlled double-blind trial investigated whether Vit-D supplementation in deficient elderly persons could improve influenza seroprotection and immune response.Design: Deficient volunteers (Vit-D serum <30 ng/mL) were assigned (V1) to receive either 100,000 IU/15 days of cholecalciferol (D, n = 19), or a placebo (P, n = 19), over a 3 month period. Influenza vaccination was performed at the end of this period (V2), and the vaccine response was evaluated 28 days later (V3). At each visit, serum cathelicidin, immune response to vaccination, plasma cytokines, lymphocyte phenotyping, and phagocyte ROS production were assessed.Results: Levels of serum 25-(OH)D increased after supplementation (D group, V1 vs. V2: 20.7 ± 5.7 vs. 44.3 ± 8.6 ng/mL, p < 0.001). No difference was observed for serum cathelicidin levels, antibody titers, and ROS production in D vs. P groups at V3. Lower plasma levels of TNFα (p = 0.040) and IL-6 (p = 0.046), and higher ones for TFGβ (p = 0.0028) were observed at V3. The Th1/Th2 ratio was lower in the D group at V2 (D: 0.12 ± 0.05 vs. P: 0.18 ± 0.05, p = 0.039).Conclusions: Vit-D supplementation promotes a higher TGFβ plasma level in response to influenza vaccination without improving antibody production. This supplementation seems to direct the lymphocyte polarization toward a tolerogenic immune response. A deeper characterization of metabolic and molecular pathways of these observations will aid in the understanding of Vit-D's effects on cell-mediated immunity in aging. This clinical trial was registered at clinicaltrials.gov as NCT01893385

Cushing's Syndrome and Fetal Features Resurgence in Adrenal Cortex–Specific Prkar1a Knockout Mice

Carney complex (CNC) is an inherited neoplasia syndrome with endocrine overactivity. Its most frequent endocrine manifestation is primary pigmented nodular adrenocortical disease (PPNAD), a bilateral adrenocortical hyperplasia causing pituitary-independent Cushing's syndrome. Inactivating mutations in PRKAR1A, a gene encoding the type 1 α-regulatory subunit (R1α) of the cAMP–dependent protein kinase (PKA) have been found in 80% of CNC patients with Cushing's syndrome. To demonstrate the implication of R1α loss in the initiation and development of PPNAD, we generated mice lacking Prkar1a specifically in the adrenal cortex (AdKO). AdKO mice develop pituitary-independent Cushing's syndrome with increased PKA activity. This leads to autonomous steroidogenic genes expression and deregulated adreno-cortical cells differentiation, increased proliferation and resistance to apoptosis. Unexpectedly, R1α loss results in improper maintenance and centrifugal expansion of cortisol-producing fetal adrenocortical cells with concomitant regression of adult cortex. Our data provide the first in vivo evidence that loss of R1α is sufficient to induce autonomous adrenal hyper-activity and bilateral hyperplasia, both observed in human PPNAD. Furthermore, this model demonstrates that deregulated PKA activity favors the emergence of a new cell population potentially arising from the fetal adrenal, giving new insight into the mechanisms leading to PPNAD

Cellular and molecular biology of Neisseria meningitidis colonization and invasive disease

The human species is the only natural host of Neisseria meningitidis, an important cause of bacterial meningitis globally, and, despite its association with devastating diseases, N. meningitidis is a commensal organism found frequently in the respiratory tract of healthy individuals. To date, antibiotic resistance is relatively uncommon in N. meningitidis isolates but, due to the rapid onset of disease in susceptible hosts, the mortality rate remains approx. 10%. Additionally, patients who survive meningococcal disease often endure numerous debilitating sequelae. N. meningitidis strains are classified primarily into serogroups based on the type of polysaccharide capsule expressed. In total, 13 serogroups have been described; however, the majority of disease is caused by strains belonging to one of only five serogroups. Although vaccines have been developed against some of these, a universal meningococcal vaccine remains a challenge due to successful immune evasion strategies of the organism, including mimicry of host structures as well as frequent antigenic variation. N. meningitidis express a range of virulence factors including capsular polysaccharide, lipopolysaccharide and a number of surface-expressed adhesive proteins. Variation of these surface structures is necessary for meningococci to evade killing by host defence mechanisms. Nonetheless, adhesion to host cells and tissues needs to be maintained to enable colonization and ensure bacterial survival in the niche. The aims of the present review are to provide a brief outline of meningococcal carriage, disease and burden to society. With this background, we discuss several bacterial strategies that may enable its survival in the human respiratory tract during colonization and in the blood during infection. We also examine several known meningococcal adhesion mechanisms and conclude with a section on the potential processes that may operate in vivo as meningococci progress from the respiratory niche through the blood to reach the central nervous system

Intérêt diagnostique du dosage de la Copeptine chez les patients se présentant aux urgences pour une douleur thoracique suspecte de syndrome coronarien aigu, sans élévation du segment ST et avec une Troponine inférieure au 99ème percentile à l'admission

L'objectif principal de notre étude était d'évaluer la valeur diagnostic de la copeptine ultrasensible chez les patients admis aux urgences pour une douleur thoracique avec un ECG non ST+ et un dosage de troponine négatif< 99ème percentile. Etude de cohorte prospective bicentrique (CHU Clermont-Ferrand, CH Aurillac) réalisée en aveugle des résultats de la copeptine. Les patients admis aux urgences avec une douleur thoracique de moins de 12h suspecte de suspecte de syndrome coronarien aigu été inclus dans l'étude. Un examen clinique, un électrocardiogramme ainsi que des analyses biologiques ont été réalisés à l'admission, puis à 2, 4, 6 et 12h. La troponine I ultra-sensible a été dosé avec les automates Dimension Vista® (Siemens Healthcare Diagnostic) et la copeptine ultra-sensible avec le KRYPTOR Compact PLUS système (B.R.A.H.M.S). Entre mars 2011 et mars 2012, 102 patients ont été analysés. Notre population se composait de 7,8% de patients avec un syndrome coronarien aigu non ST+ (SCANST+), 3,9% avec un angor instable, 8,9% avec une douleur cardiaque non coronarienne, 52% avec une douleur non cardiaque et 27,4% avec une origine indéterminée de la douleur thoracique. Aucune différence significative n'a été mise en évidence entre les patients avec un SCANST+ et les autres étiologies concernant les taux de copeptine. A l'admission 7 patients avec un SCANST+ et une troponine < 99ème percentile sur 8 avaient également une copeptine négative et se seraient vu exclu du diagnostic d'infarctus du myocarde. Nos résultats permettent de conclure que la copeptine ultrasensible, en association avec la troponine ultrasensible, ne permet pas d'exclure un syndrome coronarien aigu sans sus décalage du segment ST, chez les pateints se présentant aux urgences pour douleur thoracique.CLERMONT FD-BCIU-Santé (631132104) / SudocSudocFranceF

Facteurs de transcription nucléaires (RARs, RXRs, LXRs) et membranes amniotiques (métabolisme des rétinoïdes et stratégies d'identification de nouveaux gènes cibles des rétinoïdes)

Les membranes amniotiques humaines constituent une entité tissulaire et fonctionnelle singulière dont l'intégrité est indispensable au bon déroulement de la grossesse. Elles se composent essentiellement de deux feuillets, l'amnios et le chorion, dont toute altération peut conduire à leurs ruptures. Structure transitoire en apparence simple, les membranes amniotiques présentent un grand nombre d'évènements tissulaires et cellulaires, suggérant probablement une fine régulation moléculaire. Cependant les connaissances sur des processus comme l'angiogenèse, la prolifération, la différenciation, ou l'apoptose restent fragmentaires et leurs mécanismes moléculaires de régulation sont à ce jour peu connus. La vitamine A exerce une grande variété d'effets sur la différentiation, l'homéostasie tissulaire, la prolifération cellulaire et l'apoptose. Nous avons donc initié ce travail dans le but d'explorer le rôle de la vitamine A dans la physiologie des membranes et l'implication moléculaire des rétinoïdes via des facteurs de transcription nucléaires, les Retinoic Acid Receptors ou RARs et les Retinoid X Receptors ou RXRs. En 1er lieu, nous avons caractérisé le profil d'expression des différents acteurs moléculaires du métabolisme de la vitamine A au niveau des tissus et cellules des membranes. Deuxièmement, nous avons étudié, dans les tissus humains et murins, un partenaire hétérodimérisant avec RXR, impliqué dans la physiologie membranaire : LXR. Troisièmement, nous avons développé des techniques de bioinformatique, de culture d'explants et moléculaires permettant d'identifier des gènes cibles des rétinoïdes potentiellement impliqués dans la physiopathologie membranaire. Parmi ces gènes, nous avons choisi d'étudier plus particulièrement le +PA. Nous avons pu démontrer l'induction directe du +PA en transcrits et en protéines en culture d'explants d'amnios ainsi que le rôle du DR5 dans son activation transcriptionelle. En conclusion, l'étude du métabolisme du rétinol et l'étude de ses gènes cibles dans les membranes amniotiques, nous a permis d'aborder la régulation moléculaire de processus physiopathologiques dans cette structure. A terme, ces données pourront être utilisées pour une meilleure compréhension de la physiopathologie des membranes amniotiques afin de développer une meilleure prise en charge diagnostique (test biologique de rupture prématurée des membranes amniotiques) et thérapeutique ("amniopatch" à la vitamine A) en obstétrique.CLERMONT FD-BCIU-Santé (631132104) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Retinol potentiates the inhibitory effect of ascorbic acid on uric acid assay

International audienceThe interference of ascorbic acid in the determination of plasma uric acid concentrations, by decreasing the formation of chromophore in Trinder's reaction, is well known. By contrast, the effects of other antioxidant vitamins, such as retinol and alpha-tocopherol have not been investigated. Knowledge of the analytical interaction of these antioxidants in the uric acid assay would be useful

Placental Implications of Peroxisome Proliferator-Activated Receptors in Gestation and Parturition

International audienceThe placenta is a transitory structure indispensable for the proper development of the embryo and fetus during mammalian gestation. Like other members of the nuclear receptor family, the peroxisome proliferator-activated receptors (PPARs) are known to be involved in the physiological and pathological events occurring during the placentation. This placental involvement has been recently reviewed focusing on the early stages of placental development (implantation and invasion, etc.), mouse PPARs knockout phenotypes, and cytotrophoblast physiology. In this review, we describe the placental involvement of PPARs (e.g., fat transport and metabolism, etc.) during the late stages of gestation and in the amniotic membranes, highlighting their roles in the inflammation process (e.g., chorioamnionitis), metabolic disorders (e.g., diabetes), and parturition

Retinoids regulate human amniotic tissue-type plasminogen activator gene by a two-step mechanism

International audienceThe collagenolytic effects of the tissue-type plasminogen activator (t-PA) leading to extracellular matrix degradation are clearly involved in the physiopathology of human foetal membranes rupture. Nevertheless, the regulation of t-PA gene expression in extraembryonic developmental contexts remains unknown. The aim of our study is to propose the retinoic acids (RAs) as molecular regulators of t-PA expression in foetal membranes. RA induced t-PA mRNA and proteins in a time-dependent manner in amniotic membrane explants and Wistar Institute Susan Hayflick (WISH) cells. Furthermore, the use of cycloheximide revealed a two-step regulation of t-PA gene. Gene reporter assays confirmed that the RA-induced t-PA gene expression occurred through interactions of retinoid receptors (RARs and RXRs) with a DR5 response element located at -7 kb from the transcription site. Site-directed mutagenesis of this region of the t-PA promoter showed that SP1 factor was also retinoid-mediated induction, and immunoprecipitation assays revealed that SP1 and RAR/RXR interacted physically. Chromatin immunoprecipitation demonstrated that interactions between RARs, RXRs and t-PA promoter were time dependent: RAR-alpha/RXR-alpha bound DR5 motif before and up to 12 hrs of RA exposure, and RAR-beta/RXR-alpha bound DR5 response element after 12 hrs of RA treatment. Finally, experiments using shRNA and RAR-beta-specific antagonist revealed that reducing RAR-beta induction decreased t-PA induction. Altogether, our results established that the RA-mediated regulation of t-PA in human foetal membranes occurred through two steps, with a major role played by RAR-beta