Novel Blood Pressure Locus and Gene Discovery Using Genome-Wide Association Study and Expression Data Sets From Blood and the Kidney.

Elevated blood pressure is a major risk factor for cardiovascular disease and has a substantial genetic contribution. Genetic variation influencing blood pressure has the potential to identify new pharmacological targets for the treatment of hypertension. To discover additional novel blood pressure loci, we used 1000 Genomes Project-based imputation in 150 134 European ancestry individuals and sought significant evidence for independent replication in a further 228 245 individuals. We report 6 new signals of association in or near HSPB7, TNXB, LRP12, LOC283335, SEPT9, and AKT2, and provide new replication evidence for a further 2 signals in EBF2 and NFKBIA Combining large whole-blood gene expression resources totaling 12 607 individuals, we investigated all novel and previously reported signals and identified 48 genes with evidence for involvement in blood pressure regulation that are significant in multiple resources. Three novel kidney-specific signals were also detected. These robustly implicated genes may provide new leads for therapeutic innovation

Genome-wide association study identifies six new loci influencing pulse pressure and mean arterial pressure.

Numerous genetic loci have been associated with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in Europeans. We now report genome-wide association studies of pulse pressure (PP) and mean arterial pressure (MAP). In discovery (N = 74,064) and follow-up studies (N = 48,607), we identified at genome-wide significance (P = 2.7 × 10(-8) to P = 2.3 × 10(-13)) four new PP loci (at 4q12 near CHIC2, 7q22.3 near PIK3CG, 8q24.12 in NOV and 11q24.3 near ADAMTS8), two new MAP loci (3p21.31 in MAP4 and 10q25.3 near ADRB1) and one locus associated with both of these traits (2q24.3 near FIGN) that has also recently been associated with SBP in east Asians. For three of the new PP loci, the estimated effect for SBP was opposite of that for DBP, in contrast to the majority of common SBP- and DBP-associated variants, which show concordant effects on both traits. These findings suggest new genetic pathways underlying blood pressure variation, some of which may differentially influence SBP and DBP

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

Analysis of the role of CD8beta in co-receptor function.

The T cell receptor is found on the surface of the T cell in association with a complex of invariant proteins that are essential for functional signal transduction. One such molecule, CD8, is a co-receptor that binds to invariant parts of the MHC Class I molecule. CD8 comprises a disulphide linked α and β chain. Although the α chain has been shown to interact with the MHC as a CD8αα homodimer, the β chain is implicated in this interaction. The majority of CD8 molecules exist as αβ heterodimers rather than αα homodimers. Previous studies have identified biochemical alterations in CD8β upon T cell activation, predicted to occur in the hinge region between the Ig like domain and the transmembrane domain. In order to study the nature of this region specifically, a transgenic mouse was created expressing an altered CD8β chain. The mutated CD8β chain comprises the Ig like, transmembrane and cytoplasmic domain of CD8β, but the hinge region of CD8α. By comparing functional and biochemical data from these mice with wild type data, the project aims to define how TcR-CD8/ MHC interactions regulate T cell differentiation and activation. In this thesis it is shown that the mutated CD8β chain cannot restore selection in the thymus when expressed as a transgene on a CD8β knockout background, similarly to mice lacking CD8β altogether. Polyclonal mice were backcrossed onto the Rag-/- F5 TcR monoclonal background, where many characteristic maturation markers are comparable with wild type in the mutated mice. However certain phenotypic markers suggest there is a defect in the cells at the double positive stage, where they fail to advance through positive selection. There is a corresponding drop in the percentage and overall numbers of CD8+ T cells in the periphery in mice expressing the mutated transgene, similar to that of mice lacking CD8β. Antibodies specific for the Ig-like domain of CD8 were able to bind the chimeric molecule, the stoichiometry of the molecule was comparable to wild type, and that it was able to associate with the signaling molecule LCK. Like wild type, the mutated molecule became a faster migrating species on activation, probably due to de-sialylation, and data collected using lectins showed that in post translational modification, glycans are attached to the mutated molecule via the same specific linkages as wild type. Nevertheless there were striking differences between cells expressing the mutated molecule and those expressing wild type CD8αβ. Double positive thymocytes were significantly less able to bind cognate MHC, while the calcium flux in response to TcR/co-receptor crosslinking was also severely reduced in lymphocytes expressing the mutated molecule compared to wild type. When challenged with antigen peptide the response of lymphocytes expressing the mutated molecule is slightly different to that of wild type cells. This difference in response is also demonstrated when blocking antibodies are included in the assay. Cells expressing the mutated molecule go through more cell cycles and have a higher percentage of CD25hi cells than wild type controls, and blocking antibodies have little effect on this response. These data suggest that the glycosylation of CD8β has a very specific influence on development and selection in the thymus, and that CD8β could be acting in a regulatory fashion in the periphery

Particle size and activation threshold: a new dimension of danger signaling

Previous studies have shown that single-stranded RNA (ssRNA) mixed with protamine forms particles and activates immune cells through Toll-like receptors (TLRs). We have found that the size of protamine-RNA particles generated depends on the electrolyte content when mixing the 2 components. Moreover, we have evidenced that (1) nanometric particles induce production of interferon-alpha, whereas (2) micrometric particles mainly induce production of tumor necrosis factor-alpha (TNF-alpha) in human immune cells. We found that the mechanisms underlying these observations are (1) nanoparticles but not microparticles are selectively phagocytosed by plasmacytoid dendritic cells (pDCs), which produce interferon-alpha and (2) monocytes that produce TNF-alpha have a higher activation threshold than that of pDCs. Thus, at the same time as sensing pathogen-associated molecular patterns such as ssRNA, the immune system distinguishes the size of the associated structure in such a way as to trigger the adapted antivirus (nanometric) or antibacterial/antifungal (micrometric) immune response. Our results introduce a new dimension in danger signaling--how size qualitatively affects innate response

Antigen kinetics determines immune reactivity

A current paradigm in immunology is that the strength of T cell responses is governed by antigen dose, localization, and costimulatory signals. This study investigates the influence of antigen kinetics on CD8 T cell responses in mice. A fixed cumulative antigen dose was administered by different schedules to produce distinct dose-kinetics. Antigenic stimulation increasing exponentially over days was a stronger stimulus for CD8 T cells and antiviral immunity than a single dose or multiple dosing with daily equal doses. The same was observed for dendritic cell vaccination, with regard to T cell and anti-tumor responses, and for T cells stimulated in vitro. In conclusion, stimulation kinetics per se was shown to be a separate parameter of immunogenicity. These findings warrant a revision of current immunization models and have implications for vaccine development and immunotherapy

Mutual Mistrust in the Medical Care of Drug Users: The Keys to the “Narc” Cabinet

OBJECTIVE: Caring for patients who are active drug users is challenging. To better understand the often difficult relationships between illicit drug–using patients and their physicians, we sought to identify major issues that emerge during their interactions in a teaching hospital. DESIGN: Exploratory qualitative analysis of data from direct observation of patient care interactions and interviews with drug-using patients and their physicians. SETTING: The inpatient internal medicine service of an urban public teaching hospital. PARTICIPANTS: Nineteen patients with recent active drug use, primarily opiate use, and their 8 physician teams. RESULTS: Four major themes emerged. First, physicians feared being deceived by drug-using patients. In particular, they questioned whether patients' requests for opiates to treat pain or withdrawal might result from addictive behavior rather than from “medically indicated” need. Second, they lacked a standard approach to commonly encountered clinical issues, especially the assessment and treatment of pain and opiate withdrawal. Because patients' subjective report of symptoms is suspect, physicians struggled to find criteria for appropriate opiate prescription. Third, physicians avoided engaging patients regarding key complaints, and expressed discomfort and uncertainty in their approach to these patients. Fourth, drug-using patients were sensitive to the possibility of poor medical care, often interpreting physician inconsistency or hospital inefficiency as signs of intentional mistreatment. CONCLUSION: Physicians and drug-using patients in the teaching hospital setting display mutual mistrust, especially concerning opiate prescription. Physicians' fear of deception, inconsistency and avoidance interacts with patients' concern that they are mistreated and stigmatized. Medical education should focus greater attention on addiction medicine and pain management

Genetic analysis of over one million people identifies 535 novel loci for blood pressure

High blood pressure is the foremost heritable global risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits to date (systolic, diastolic, pulse pressure) in over one million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also reveal shared loci influencing lifestyle exposures. Our findings offer the potential for a precision medicine strategy for future cardiovascular disease prevention

Genetic analysis of over 1 million people identifies 535 new loci associated with blood pressure traits

High blood pressure is a highly heritable and modifiable risk factor for cardiovascular disease. We report the largest genetic association study of blood pressure traits (systolic, diastolic and pulse pressure) to date in over 1 million people of European ancestry. We identify 535 novel blood pressure loci that not only offer new biological insights into blood pressure regulation but also highlight shared genetic architecture between blood pressure and lifestyle exposures. Our findings identify new biological pathways for blood pressure regulation with potential for improved cardiovascular disease prevention in the future