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

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

Mendelian randomization study of height and risk of colorectal cancer

Background: For men and women, taller height is associated with increased risk of all cancers combined. For colorectal cancer (CRC), it is unclear whether the differential association of height by sex is real or is due to confounding or bias inherent in observational studies. We performed a Mendelian randomization study to examine the association between height and CRC risk

A correction for sample overlap in genome-wide association studies in a polygenic pleiotropy-informed framework.

BACKGROUND: There is considerable evidence that many complex traits have a partially shared genetic basis, termed pleiotropy. It is therefore useful to consider integrating genome-wide association study (GWAS) data across several traits, usually at the summary statistic level. A major practical challenge arises when these GWAS have overlapping subjects. This is particularly an issue when estimating pleiotropy using methods that condition the significance of one trait on the signficance of a second, such as the covariate-modulated false discovery rate (cmfdr). RESULTS: We propose a method for correcting for sample overlap at the summary statistic level. We quantify the expected amount of spurious correlation between the summary statistics from two GWAS due to sample overlap, and use this estimated correlation in a simple linear correction that adjusts the joint distribution of test statistics from the two GWAS. The correction is appropriate for GWAS with case-control or quantitative outcomes. Our simulations and data example show that without correcting for sample overlap, the cmfdr is not properly controlled, leading to an excessive number of false discoveries and an excessive false discovery proportion. Our correction for sample overlap is effective in that it restores proper control of the false discovery rate, at very little loss in power. CONCLUSIONS: With our proposed correction, it is possible to integrate GWAS summary statistics with overlapping samples in a statistical framework that is dependent on the joint distribution of the two GWAS

Harmonizing and improving European education in prescribing: An overview of digital educational resources used in clinical pharmacology and therapeutics

Aim: Improvement and harmonization of European clinical pharmacology and therapeutics (CPT) education is urgently required. Because digital educational resources can be easily shared, adapted to local situations and re-used widely across a variety of educational systems, they may be ideally suited for this purpose. Methods: With a cross-sectional survey among principal CPT teachers in 279 out of 304 European medical schools, an overview and classification of digital resources was compiled. Results: Teachers from 95 (34%) medical schools in 26 of 28 EU countries responded, 66 (70%) of whom used digital educational resources in their CPT curriculum. A total of 89 of such resources were described in detail, including e-learning (24%), simulators to teach pharmacokinetics and/or pharmacodynamics (10%), virtual patients (8%), and serious games (5%). Together, these resources covered 235 knowledge-based learning objectives, 88 skills, and 13 attitudes. Only one third (27) of the resources were in-part or totally free and only two were licensed open educational resources (free to use, distribute and adapt). A narrative overview of the largest, free and most novel resources is given. Conclusion: Digital educational resources, ranging from e-learning to virtual patients and games, are widely used for CPT education in EU medical schools. Learning objectives are based largely on knowledge rather than skills or attitudes. This may be improved by including more real-life clinical case scenarios. Moreover, the majority of resources are neither free nor open. Therefore, with a view to harmonizing international CPT education, more needs to be learned about why CPT teachers are not currently sharing their educational materials

EurOP2E – the European Open Platform for Prescribing Education, a consensus study among clinical pharmacology and therapeutics teachers

Purpose Sharing and developing digital educational resources and open educational resources has been proposed as a way to harmonize and improve clinical pharmacology and therapeutics (CPT) education in European medical schools. Previous research, however, has shown that there are barriers to the adoption and implementation of open educational resources. The aim of this study was to determine perceived opportunities and barriers to the use and creation of open educational resources among European CPT teachers and possible solutions for these barriers. Methods CPT teachers of British and EU medical schools completed an online survey. Opportunities and challenges were identified by thematic analyses and subsequently discussed in an international consensus meeting. Results Data from 99 CPT teachers from 95 medical schools were analysed. Thirty teachers (30.3%) shared or collaboratively produced digital educational resources. All teachers foresaw opportunities in the more active use of open educational resources, including improving the quality of their teaching. The challenges reported were language barriers, local differences, lack of time, technological issues, difficulties with quality management, and copyright restrictions. Practical solutions for these challenges were discussed and include a peer review system, clear indexing, and use of copyright licenses that permit adaptation of resources. Conclusion Key challenges to making greater use of CPT open educational resources are a limited applicability of such resources due to language and local differences and quality concerns. These challenges may be resolved by relatively simple measures, such as allowing adaptation and translation of resources and a peer review system

Mendelian Randomization Study of Body Mass Index and Colorectal Cancer Risk

High body mass index (BMI) is consistently linked to increased risk of colorectal cancer (CRC) for men, whereas the association is less clear for women. As risk estimates from observational studies may be biased and/or confounded, we conducted a Mendelian randomization study to estimate the causal association between BMI and CRC

Cerebral small vessel disease genomics and its implications across the lifespan

White matter hyperintensities (WMH) are the most common brain-imaging feature of cerebral small vessel disease (SVD), hypertension being the main known risk factor. Here, we identify 27 genome-wide loci for WMH-volume in a cohort of 50,970 older individuals, accounting for modification/confounding by hypertension. Aggregated WMH risk variants were associated with altered white matter integrity (p = 2.5×10-7) in brain images from 1,738 young healthy adults, providing insight into the lifetime impact of SVD genetic risk. Mendelian randomization suggested causal association of increasing WMH-volume with stroke, Alzheimer-type dementia, and of increasing blood pressure (BP) with larger WMH-volume, notably also in persons without clinical hypertension. Transcriptome-wide colocalization analyses showed association of WMH-volume with expression of 39 genes, of which four encode known drug targets. Finally, we provide insight into BP-independent biological pathways underlying SVD and suggest potential for genetic stratification of high-risk individuals and for genetically-informed prioritization of drug targets for prevention trials.Peer reviewe