Importance Of Toll-Like Receptors For B Lymphocyte Survival In Primary Sjögren’s Syndrome

The Sjögren's syndrome is a systemic autoimmune disease characterized by lymphocytic infiltration of the glands responsible for mouth and eyes dryness. A minority of infiltrating B cells is organized as germinal centers while the majority is aggregated into clusters of transitional and marginal zone B cells. The Toll-like receptor 9 (TLR9) recognizes microbial DNA but also, sometimes, the self DNA. It appears to be a key determinant of the survival and differentiation of B lymphocytes. After laser micro-dissection of B cells from salivary glands, analyses by quantitative RT-PCR showed that transitional B cells express high level of TLR9 mRNA unlike B cells from germinal centers. B lymphocytes from healthy donors were sorted by flow cytometry and stimulated in vitro with their TLR9. It induces survival, activation and proliferation associated with phenotypic changes. Transitional B cells exhibited characteristics of the marginal zone, whereas mature B cells expressed follicular germinal center specificities. Finally, IgM and IgG were secreted by both population, but with elevated production of autoantibodies by the transitional B cells. Increased expression of TLR9 by transitional B cells suggests that they may be highly sensitive to differentiate into autoantibody secreting cells through maturation into the marginal zone into the salivary glands. TLR9 might be a target for forthcoming biotherapies. Le syndrome de Gougerot-Sjögren est une maladie autoimmune systémique caractérisée par une infiltration lymphocytaire des glandes responsable d'une sécheresse buccale et oculaire. Une minorité des lymphocytes B infiltrants est organisée en centres germinatifs tandis que la majorité est regroupée en agrégats de lymphocytes B transitionnels et de la zone marginale. Le Toll-like receptor 9 (TLR9) reconnaît l'ADN microbien mais aussi, parfois, l'ADN du soi. Il apparaît donc comme un élément déterminant de la survie et la différenciation des lymphocytes B. Après micro-dissection laser des lymphocytes B des glandes salivaires, une analyse par RT-PCR quantitative a montré que les lymphocytes B transitionnels expriment fortement l'ARNm de TLR9 contrairement à ceux des centres germinatifs. Des lymphocytes B de donneurs sains ont été triés par cytométrie en flux puis stimulés in vitro par leur TLR9. Il s’ensuit une survie, une activation et une prolifération associées à des modifications phénotypiques. Les lymphocytes B transitionnels présentent des caractéristiques de la zone marginale, tandis que les lymphocytes B matures expriment des spécificités folliculaires des centres germinatifs. Enfin, des IgM et des IgG sont sécrétées par les deux types de population, mais avec une production d'auto-anticorps plus élevée issue de la différenciation des lymphocytes B transitionnels. L’expression accrue de TLR9 par les lymphocytes B transitionnels suggère qu'ils pourraient être particulièrement sensibles à une différenciation en cellules sécrétrices d'auto-anticorps par une maturation vers la zone marginale au sein des glandes salivaires. Le TLR9 pourrait bien devenir la cible des futures biothérapies.The Sjögren's syndrome is a systemic autoimmune disease characterized by lymphocytic infiltration of the glands responsible for mouth and eyes dryness. A minority of infiltrating B cells is organized as germinal centers while the majority is aggregated into clusters of transitional and marginal zone B cells. The Toll-like receptor 9 (TLR9) recognizes microbial DNA but also, sometimes, the self DNA. It appears to be a key determinant of the survival and differentiation of B lymphocytes. After laser micro-dissection of B cells from salivary glands, analyses by quantitative RT-PCR showed that transitional B cells express high level of TLR9 mRNA unlike B cells from germinal centers. B lymphocytes from healthy donors were sorted by flow cytometry and stimulated in vitro with their TLR9. It induces survival, activation and proliferation associated with phenotypic changes. Transitional B cells exhibited characteristics of the marginal zone, whereas mature B cells expressed follicular germinal center specificities. Finally, IgM and IgG were secreted by both population, but with elevated production of autoantibodies by the transitional B cells. Increased expression of TLR9 by transitional B cells suggests that they may be highly sensitive to differentiate into autoantibody secreting cells through maturation into the marginal zone into the salivary glands. TLR9 might be a target for forthcoming biotherapies. Le syndrome de Gougerot-Sjögren est une maladie autoimmune systémique caractérisée par une infiltration lymphocytaire des glandes responsable d'une sécheresse buccale et oculaire. Une minorité des lymphocytes B infiltrants est organisée en centres germinatifs tandis que la majorité est regroupée en agrégats de lymphocytes B transitionnels et de la zone marginale. Le Toll-like receptor 9 (TLR9) reconnaît l'ADN microbien mais aussi, parfois, l'ADN du soi. Il apparaît donc comme un élément déterminant de la survie et la différenciation des lymphocytes B. Après micro-dissection laser des lymphocytes B des glandes salivaires, une analyse par RT-PCR quantitative a montré que les lymphocytes B transitionnels expriment fortement l'ARNm de TLR9 contrairement à ceux des centres germinatifs. Des lymphocytes B de donneurs sains ont été triés par cytométrie en flux puis stimulés in vitro par leur TLR9. Il s’ensuit une survie, une activation et une prolifération associées à des modifications phénotypiques. Les lymphocytes B transitionnels présentent des caractéristiques de la zone marginale, tandis que les lymphocytes B matures expriment des spécificités folliculaires des centres germinatifs. Enfin, des IgM et des IgG sont sécrétées par les deux types de population, mais avec une production d'auto-anticorps plus élevée issue de la différenciation des lymphocytes B transitionnels. L’expression accrue de TLR9 par les lymphocytes B transitionnels suggère qu'ils pourraient être particulièrement sensibles à une différenciation en cellules sécrétrices d'auto-anticorps par une maturation vers la zone marginale au sein des glandes salivaires. Le TLR9 pourrait bien devenir la cible des futures biothérapies

The action of physiological and synthetic steroids on the calcium channel CatSper in human sperm

The sperm-specific channel CatSper (cation channel of sperm) controls the intracellular Ca2+ concentration ([Ca2+]i) and plays an essential role in sperm function. It is mainly activated by the steroid progesterone (P4) but is also promiscuously activated by a wide range of synthetic and physiological compounds. These compounds include diverse steroids whose action on the channel is so far still controversial. To investigate the effect of these compounds on CatSper and sperm function, we developed a high-throughput screening (HTS) assay to measure changes in [Ca2+]i in human sperm and screened 1,280 approved and off-patent drugs including 90 steroids from the Prestwick chemical library. More than half of the steroids tested (53%) induced an increase in [Ca2+]i and reduced the P4-induced Ca2+ influx in human sperm in a dose-dependent manner. Ten of the most potent steroids (activating and P4-inhibiting) were selected for a detailed analysis of their action on CatSper and their ability to act on sperm acrosome reaction (AR) and penetration in viscous media. We found that these steroids show an inhibitory effect on P4 but not on prostaglandin E1-induced CatSper activation, suggesting that they compete for the same binding site as P4. Pregnenolone, dydrogesterone, epiandrosterone, nandrolone, and dehydroepiandrosterone acetate (DHEA) were found to activate CatSper at physiologically relevant concentrations within the nanomolar range. Like P4, most tested steroids did not significantly affect the AR while stanozolol and estropipate slightly increased sperm penetration into viscous medium. Furthermore, using a hybrid approach integrating pharmacophore analysis and statistical modelling, we were able to screen in silico for steroids that can activate the channel and define the physicochemical and structural properties required for a steroid to exhibit agonist activity against CatSper. Overall, our results indicate that not only physiological but also synthetic steroids can modulate the activity of CatSper with varying potency and if bound to CatSper prior to P4, could impair the timely CatSper activation necessary for proper fertilization to occur

TOLL-LIKE RECEPTOR 9 DRIVES THE MATURATION OF B LYMPHOCYTES IN THE SALIVARY GLANDS OF PATIENTS WITH SJÖGREN’S SYNDROME

Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

Change of tRNA identity leads to a divergent orthogonal histidyl-tRNA synthetase/tRNAHis pair

Mature tRNAHis has at its 5′-terminus an extra guanylate, designated as G−1. This is the major recognition element for histidyl-tRNA synthetase (HisRS) to permit acylation of tRNAHis with histidine. However, it was reported that tRNAHis of a subgroup of α-proteobacteria, including Caulobacter crescentus, lacks the critical G−1 residue. Here we show that recombinant C. crescentus HisRS allowed complete histidylation of a C. crescentus tRNAHis transcript (lacking G−1). The addition of G−1 did not improve aminoacylation by C. crescentus HisRS. However, mutations in the tRNAHis anticodon caused a drastic loss of in vitro histidylation, and mutations of bases A73 and U72 also reduced charging. Thus, the major recognition elements in C. crescentus tRNAHis are the anticodon, the discriminator base and U72, which are recognized by the divergent (based on sequence similarity) C. crescentus HisRS. Transplantation of these recognition elements into an Escherichia coli tRNAHis template, together with addition of base U20a, created a competent substrate for C. crescentus HisRS. These results illustrate how a conserved tRNA recognition pattern changed during evolution. The data also uncovered a divergent orthogonal HisRS/tRNAHis pair

High Abundance Proteins Depletion vs Low Abundance Proteins Enrichment: Comparison of Methods to Reduce the Plasma Proteome Complexity

BACKGROUND: To date, the complexity of the plasma proteome exceeds the analytical capacity of conventional approaches to isolate lower abundance proteins that may prove to be informative biomarkers. Only complex multistep separation strategies have been able to detect a substantial number of low abundance proteins (<100 ng/ml). The first step of these protocols is generally the depletion of high abundance proteins by the use of immunoaffinity columns or, alternatively, the enrichment of by the use of solid phase hexapeptides ligand libraries. METHODOLOGY/PRINCIPAL FINDINGS: Here we present a direct comparison of these two approaches. Following either approach, the plasma sample was further fractionated by SCX chromatography and analyzed by RP-LC-MS/MS with a Q-TOF mass spectrometer. The depletion of the 20 most abundant plasma proteins allowed the identification of about 25% more proteins than those detectable following low abundance proteins enrichment. The two datasets are partially overlapping and the identified proteins belong to the same order of magnitude in terms of plasma concentration. CONCLUSIONS/SIGNIFICANCE: Our results show that the two approaches give complementary results. However, the enrichment of low abundance proteins has the great advantage of obtaining much larger amount of material that can be used for further fractionations and analyses and emerges also as a cheaper and technically simpler approach. Collectively, these data indicate that the enrichment approach seems more suitable as the first stage of a complex multi-step fractionation protocol

A Modern Mode of Activation for Nucleic Acid Enzymes

Through evolution, enzymes have developed subtle modes of activation in order to ensure the sufficiently high substrate specificity required by modern cellular metabolism. One of these modes is the use of a target-dependent module (i.e. a docking domain) such as those found in signalling kinases. Upon the binding of the target to a docking domain, the substrate is positioned within the catalytic site. The prodomain acts as a target-dependent module switching the kinase from an off state to an on state. As compared to the allosteric mode of activation, there is no need for the presence of a third partner. None of the ribozymes discovered to date have such a mode of activation, nor does any other known RNA. Starting from a specific on/off adaptor for the hepatitis delta virus ribozyme, that differs but has a mechanism reminiscent of this signalling kinase, we have adapted this mode of activation, using the techniques of molecular engineering, to both catalytic RNAs and DNAs exhibiting various activities. Specifically, we adapted three cleaving ribozymes (hepatitis delta virus, hammerhead and hairpin ribozymes), a cleaving 10-23 deoxyribozyme, a ligating hairpin ribozyme and an artificially selected capping ribozyme. In each case, there was a significant gain in terms of substrate specificity. Even if this mode of control is unreported for natural catalytic nucleic acids, its use needs not be limited to proteinous enzymes. We suggest that the complexity of the modern cellular metabolism might have been an important selective pressure in this evolutionary process

Resistance to antimicrobials in poultry production chain isolated bacteria

La resistencia bacteriana a los antimicrobianos es un problema global. Una posible causa de aparición de resistencia es su uso como promotores de crecimiento en aves. Esto puede producir fallos terapéuticos e incrementar la transmisión de bacterias resistentes al hombre. El objetivo de este trabajo es determinar la sensibilidad a antimicrobianos en bacterias aisladas de aves y subproductos para consumo humano. Se estudiaron 60 muestras, aislándose Escherichia coli, Salmonella spp. y Enterococcus faecalis. Un 80% de las muestras de granja presentaron recuentos >103 UFC/g para E. coli y 95% para E. faecalis; 70% de las de frigorífico tuvieron recuentos >103 UFC/g de E. coli y 85% de las de supermercado presentaron recuentos >103 UFC/g de E. faecalis, 15% de E. coli; y 5% presentó desarrollo de Salmonella spp. De 53 aislamientos de E. coli, 47,1% fueron resistentes a fluoroquinolonas, 9,4% resistentes a cefalosporinas de tercera generación, y 3,8% a colistina. De 39 cepas de E. faecalis, una fue resistente a ciprofloxacina, y ninguna a vancomicina. El aislamiento de Salmonella spp. fue resistente a ciprofloxacina. Nuestros resultados revelarían la necesidad de intensificar los controles higiénico-sanitarios en la cadena de manipulación de aves, e implementar mejoras para la reducción de patógenos.Bacterial resistance to antimicrobials is a global problem. A possible cause of the emergence of resistance is their use as growth promoters. This can cause therapeutic failures and increase the transmission of resistant bacteria. The objective of this work was to determine the sensitivity to antimicrobials of isolated bacteria from poultry and products for human consumption. Sixty samples were studied and Escherichia coli, Salmonella spp. and Enterococcus faecalis were isolated. Around 80 % of the farm samples showed counts of >103 UFC/g for E. coli and 95 % for E. faecalis; 70 % of the refrigerated samples showed counts of >103 UFC/g for E. coli, and 85 % of the market samples showed counts of > 103 CFU /g for E. faecalis, 15 % for E. coli; and 5 % developed Salmonella spp. Of the 53 E. coli isolations, 47.1 % were resistant to fluoroquinolones, 9.4 % to third-generation cephalosporins, and 3.8 % to colistin. Of the 39 E. faecalis iso- lated strains, one was resistant to ciprofloxacin, and none to vancomycin. The isolated Salmonella spp. was resistant to ciprofloxacin. Our results reveal the need to intensify sanitary and higyene controls poultry manipulation chain and implement improvements to pathogens reduction.Fil: López, Victoria. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Guerrier, Leonor. Instituto de Análisis Fares Taie; ArgentinaFil: Elorza, Victoria. Instituto de Análisis Fares Taie; ArgentinaFil: Krüger, Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Colello, Rocío. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil. Centro de Investigación Veterinaria de Tandil. Universidad Nacional del Centro de la Provincia de Buenos Aires. Centro de Investigación Veterinaria de Tandil. Provincia de Buenos Aires. Gobernación. Comision de Investigaciones Científicas. Centro de Investigación Veterinaria de Tandil; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Medici, Sandra Karina. Instituto de Análisis Fares Taie; ArgentinaFil: Espinosa, Mónica. Instituto de Análisis Fares Taie; ArgentinaFil: Casado, Paula. Instituto de Análisis Fares Taie; ArgentinaFil: Recavarren, Mariana Ines. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; Argentina. Instituto de Análisis Fares Taie; ArgentinaFil: Keller, L.. Instituto de Análisis Fares Taie; Argentin

<i>Gaia</i> Data Release 1. Summary of the astrometric, photometric, and survey properties

Context. At about 1000 days after the launch of Gaia we present the first Gaia data release, Gaia DR1, consisting of astrometry and photometry for over 1 billion sources brighter than magnitude 20.7. Aims. A summary of Gaia DR1 is presented along with illustrations of the scientific quality of the data, followed by a discussion of the limitations due to the preliminary nature of this release. Methods. The raw data collected by Gaia during the first 14 months of the mission have been processed by the Gaia Data Processing and Analysis Consortium (DPAC) and turned into an astrometric and photometric catalogue. Results. Gaia DR1 consists of three components: a primary astrometric data set which contains the positions, parallaxes, and mean proper motions for about 2 million of the brightest stars in common with the HIPPARCOS and Tycho-2 catalogues – a realisation of the Tycho-Gaia Astrometric Solution (TGAS) – and a secondary astrometric data set containing the positions for an additional 1.1 billion sources. The second component is the photometric data set, consisting of mean G-band magnitudes for all sources. The G-band light curves and the characteristics of ∼3000 Cepheid and RR-Lyrae stars, observed at high cadence around the south ecliptic pole, form the third component. For the primary astrometric data set the typical uncertainty is about 0.3 mas for the positions and parallaxes, and about 1 mas yr−1 for the proper motions. A systematic component of ∼0.3 mas should be added to the parallax uncertainties. For the subset of ∼94 000 HIPPARCOS stars in the primary data set, the proper motions are much more precise at about 0.06 mas yr−1. For the secondary astrometric data set, the typical uncertainty of the positions is ∼10 mas. The median uncertainties on the mean G-band magnitudes range from the mmag level to ∼0.03 mag over the magnitude range 5 to 20.7. Conclusions. Gaia DR1 is an important milestone ahead of the next Gaia data release, which will feature five-parameter astrometry for all sources. Extensive validation shows that Gaia DR1 represents a major advance in the mapping of the heavens and the availability of basic stellar data that underpin observational astrophysics. Nevertheless, the very preliminary nature of this first Gaia data release does lead to a number of important limitations to the data quality which should be carefully considered before drawing conclusions from the data

Heterodimerization of the human RNase P/MRP subunits Rpp20 and Rpp25 is a prerequisite for interaction with the P3 arm of RNase MRP RNA

Rpp20 and Rpp25 are two key subunits of the human endoribonucleases RNase P and MRP. Formation of an Rpp20–Rpp25 complex is critical for enzyme function and sub-cellular localization. We present the first detailed in vitro analysis of their conformational properties, and a biochemical and biophysical characterization of their mutual interaction and RNA recognition. This study specifically examines the role of the Rpp20/Rpp25 association in the formation of the ribonucleoprotein complex. The interaction of the individual subunits with the P3 arm of the RNase MRP RNA is revealed to be negligible whereas the 1:1 Rpp20:Rpp25 complex binds to the same target with an affinity of the order of nM. These results unambiguously demonstrate that Rpp20 and Rpp25 interact with the P3 RNA as a heterodimer, which is formed prior to RNA binding. This creates a platform for the design of future experiments aimed at a better understanding of the function and organization of RNase P and MRP. Finally, analyses of interactions with deletion mutant proteins constructed with successively shorter N- and C-terminal sequences indicate that the Alba-type core domain of both Rpp20 and Rpp25 contains most of the determinants for mutual association and P3 RNA recognition