A Genome-Wide Scan of Ashkenazi Jewish Crohn's Disease Suggests Novel Susceptibility Loci

Crohn's disease (CD) is a complex disorder resulting from the interaction of intestinal microbiota with the host immune system in genetically susceptible individuals. The largest meta-analysis of genome-wide association to date identified 71 CD–susceptibility loci in individuals of European ancestry. An important epidemiological feature of CD is that it is 2–4 times more prevalent among individuals of Ashkenazi Jewish (AJ) descent compared to non-Jewish Europeans (NJ). To explore genetic variation associated with CD in AJs, we conducted a genome-wide association study (GWAS) by combining raw genotype data across 10 AJ cohorts consisting of 907 cases and 2,345 controls in the discovery stage, followed up by a replication study in 971 cases and 2,124 controls. We confirmed genome-wide significant associations of 9 known CD loci in AJs and replicated 3 additional loci with strong signal (p<5×10−6). Novel signals detected among AJs were mapped to chromosomes 5q21.1 (rs7705924, combined p = 2×10−8; combined odds ratio OR = 1.48), 2p15 (rs6545946, p = 7×10−9; OR = 1.16), 8q21.11 (rs12677663, p = 2×10−8; OR = 1.15), 10q26.3 (rs10734105, p = 3×10−8; OR = 1.27), and 11q12.1 (rs11229030, p = 8×10−9; OR = 1.15), implicating biologically plausible candidate genes, including RPL7, CPAMD8, PRG2, and PRG3. In all, the 16 replicated and newly discovered loci, in addition to the three coding NOD2 variants, accounted for 11.2% of the total genetic variance for CD risk in the AJ population. This study demonstrates the complementary value of genetic studies in the Ashkenazim

Genome-wide association analysis identifies six new loci associated with forced vital capacity

Forced vital capacity (FVC), a spirometric measure of pulmonary function, reflects lung volume and is used to diagnose and monitor lung diseases. We performed genome-wide association study meta-analysis of FVC in 52,253 individuals from 26 studies and followed up the top associations in 32,917 additional individuals of European ancestry. We found six new regions associated at genome-wide significance (P < 5 × 10−8) with FVC in or near EFEMP1, BMP6, MIR129-2–HSD17B12, PRDM11, WWOX and KCNJ2. Two loci previously associated with spirometric measures (GSTCD and PTCH1) were related to FVC. Newly implicated regions were followed up in samples from African-American, Korean, Chinese and Hispanic individuals. We detected transcripts for all six newly implicated genes in human lung tissue. The new loci may inform mechanisms involved in lung development and the pathogenesis of restrictive lung disease

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

Molecular mechanisms of high-density lipoprotein biogenesis, metabolism and function: relevance to cardiovascular disease prevention and treatment

Coronary artery disease (CAD) remains the primary source of global mortality. Multiple epidemiologic studies support a low level of high-density lipoprotein cholesterol (HDL-C) to be an independent risk factor for CAD. We believe that a complete understanding of the mechanisms underlying HDL biogenesis, metabolism, and function will aid in defining the therapeutic potential of raising HDL in treating CAD. This thesis consists of five inter-related studies with the central unifying theme of HDL physiology. First, we examine the cellular mechanism of HDL biogenesis involving the lipidation of apolipoprotein A-I (apoA-I) by the ATP-binding cassette transporter (ABCA)1. We show that the lipidation of apoA-I occurs in two distinguishable compartments, the plasma membrane and intracellular compartments. Second, we investigate the interaction between apoA-I and an ABCA1/phospholipid microdomain binding site(s) called the high-capacity binding site (HCBS). Using sucrose density fractionation, we observe that both ABCA1 and the HCBS are localized to detergent-soluble membrane domains and that apoA-I selectively removes phosphatidylcholine (PtdC) from detergent-soluble membrane domains. Additionally, we observe that cholesterol loading or depletion or PtdC depletion modifies apoA-I binding to ABCA1/HCBS, and that incubation with apoA-I leads to transcriptional induction of PtdC synthesis enzymes, as well as PtdC synthesis. Third, we examine nascent HDL-remodeling in vitro by developing a lipid-transfer assay and in vivo in a rabbit model. This study suggests that nascent HDL remodeling involves plasma apoB-containing lipoproteins and phospholipid transfer protein (PLTP). Fourth, we assess the capacity of a novel small molecule, RVX-208, to increase apoA-I and HDL-C levels in vitro and in vivo. We show that RVX-208 increases apoA-I and HDL-C production and maintains HDL-C function with respect to reverse cholesterol transport. Fifth, we examine the HDL proteome in acute coronary syndromes (ACS) subjects by shotgun proteomics. Our results support that the HDL proteome differs between control, CAD and ACS patients. Although strong epidemiological evidence exists to support HDL-C as an independent risk factor for CAD, it remains to be determined whether increasing HDL-C levels or improving HDL function in man will reduce residual CAD events. We believe that the aforementioned areas of research will aid in identifying new therapeutic targets and/or biomarkers to assess new HDL-targeted therapeutics. Specifically, we believe that understanding HDL biogenesis and metabolism is of critical importance to develop HDL-elevating compounds, while analysis of HDL protein composition gives insight into previously unknown or unappreciated functions of HDL. Together, this allows a better assessment of the therapeutic potential of raising HDL levels and/or function in preventing or regressing atherosclerosis.La maladie coronarienne athéroscléreuse (MCAS) demeure la principale cause de mortalité à l'échelle mondiale. Plusieurs études épidémiologiques ont démontré que des niveaux abaissés de cholestérol HDL (C-HDL) représentent un facteur de risque indépendant de MCAS. Nous croyons qu'une compréhension approfondie des mécanismes de biogenèse, du métabolisme et de la fonction des HDL aidera à mieux définir le potentiel thérapeutique visant à augmenter les niveaux de C-HDL dans le traitement de la MCAS. Cette thèse comporte cinq études interdépendantes ayant comme thème central et conducteur l'étude de la physiologie des particules HDL.Dans un premier temps nous avons examiné les mécanismes cellulaires liés à la biogenèse des HDL, impliquant la lipidation de l'apolipoprotéine A-I (apoA-I) par le transporteur ABCA1. Nous démontrons que la lipidation de l'apoA-I survient dans deux régions cellulaires distinctes : la membrane cellulaire et les compartiments intracellulaires. Deuxièmement, nous avons examiné l'interaction de l'apoA-I avec un/des site(s) de liaison constitués de microdomaines ABCA1/phospholipides que nous avons désignés « site de liaison de grande capacité (HCBS) ». En utilisant le fractionnement cellulaire sur gradient de densité de sucrose, nous observons que l'ABCA1 et le HCBS sont localisés dans des domaines membranaires solubles aux détergents et que l'apoA-I désorbe sélectivement la phosphatidylcholine (PtdC) de ces domaines. De plus, nous mettons en évidence qu'une charge en cholestérol ou un épuisement en PtdC dans la cellule modifient la liaison de l'apoA-I à l'ABCA1/HCBS. Nous observons d'autre part qu'une incubation de la cellule avec l'apoA-I induit une activité transcriptionnelle d'enzymes de synthèse de la PtdC ainsi que de synthèse de PtdC. Troisièmement, nous avons examiné le remodelage de la particule HDL naissante in vitro en développant un essai qui mesure le transfert de lipides in vivo dans un modèle de lapin. Cette étude suggère que le remodelage de la particule HDL naissante implique l'apolipoprotéine B plasmatique et la protéine de transfert des phospholipides. Quatrièmement, nous avons évalué la capacité d'une nouvelle molécule, le RVX-208, à augmenter les niveaux d'apoA-I et de C-HDL in vitro et in vivo. Nous démontrons que le RVX-208 augmente l'apoA-I et la production de C-HDL et améliore la fonction des HDL dans la voie de retour du cholestérol. Cinquièmement, nous avons procédé à des analyses protéomiques des HDL dans le syndrome coronarien aigu (ACS) chez des sujets. Nos résultats supportent le concept que la signature protéomique des HDL diffère entre des témoins contrôles, des patients MCAS et des patients ACS.Bien que de fortes évidences épidémiologiques supportent le C-HDL comme facteur de risque indépendant de la MCAS, il demeure à déterminer si une augmentation des niveaux de C-HDL plasmatique ou une amélioration de la fonction des HDL chez l'humain réduisent la MCAS. Nous croyons quel les pistes de recherches explorées ci-haut aideront à l'identification de nouvelles cibles thérapeutiques et/ou de biomarqueurs dans l'évaluation de nouvelles thérapies ciblant les HDL. Plus particulièrement, nous croyons qu'une compréhension de la biogenèse et du métabolisme des HDL est d'une importance cruciale pour l'élaboration de composés augmentant les niveaux de HDL. D'autre part, l'analyse de la composition en protéines des HDL fournit des informations sur des fonctions jusqu'alors non connues ou considérées des HDL. Ces données mises ensembles permettent une meilleure évaluation du potentiel thérapeutique à augmenter les niveaux de C-HDL et/ou améliorer la fonction des HDL dans la prévention ou la régression de l'athérosclérose coronarienne

Semliki Forest virus and Kunjin virus RNA replicons elicit comparable cellular immunity but distinct humoral immunity

RNA replicons offer a number of qualities which make them attractive as vaccination vectors. Both alphavirus and flavivirus replicon vaccines have been investigated in preclinical models yet there has been little direct comparison of the two vector systems. To determine whether differences in the biology of the two vectors influence immunogenicity, we compared two prototypic replicon vectors based on Semliki Forest virus (SFV) (alphavirus) and Kunjin virus (KUN) (flavivirus). Both vectors when delivered as naked RNAs elicited comparable CD8+ T cell responses but the SFV vectors elicited greater humoral responses to an encoded cytoplasmic antigen beta-galactosidase. Studies in MHC class II-deficient mice revealed that neither vector could overcome the dependence of CD4+ T cell help in the development of humoral and cellular responses following immunization. These studies indicate that the distinct biology of the two replicon systems may differentially impact the adaptive immune response and this may need to be considered when designing vaccination strategies. (c) 2005 Elsevier Ltd. All rights reserved