Sumner T.,London School of Hygiene and Tropical Medicine |
Houben R.M.G.J.,London School of Hygiene and Tropical Medicine |
Rangaka M.X.,University College London |
Rangaka M.X.,University of Cape Town |
And 7 more authors.
AIDS | Year: 2016
Background: In HIV-uninfected individuals, isoniazid preventive therapy (IPT) has been associated with long-term protection against tuberculosis (TB). For HIV-infected/antiretroviral therapy (ART)-naive individuals, high TB rates have been observed following completion of IPT, consistent with a lack of 'cure' of infection. Recent trial data of IPT among HIV-infected individuals on ART in Khayelitsha, South Africa, have suggested that the effect of IPT persisted following completion of IPT. Methods: Using mathematical modelling, we explored if this increased duration of protection may be due to an increased curative ability of IPT when given in combination with ART. The model was used to estimate the annual risk of infection and proportion of individuals whose latent infection was 'cured' by IPT, defined such that they must be reinfected to be at risk of disease. Results: The estimated annual risk of infection was 4.0% (2.6-5.8) and the estimated proportion of individuals whose latent Mycobacterium tuberculosis infection was cured following IPT was 35.4% (2.4-76.4), higher than that previously estimated for HIV-infected/ART-naive individuals. Our results suggest that IPT can cure latent M. tuberculosis infection in approximately one-third of HIV-infected individuals on ART and therefore provide protection beyond the period of treatment. Conclusion: Among HIV-infected individuals on ART in low incidence settings, 12 months of IPT may provide additional long-term benefit. Among HIV-infected individuals on ART in high incidence settings, the durability of this protection will be limited because of continued risk of reinfection, and continuous preventive therapy together with improved infection control efforts will be required to provide long-term protection against TB. © 2016 Wolters Kluwer Health, Inc. All rights reserved.
Wilson R.,Francis Crick Institute Mill Hill Laboratory |
McGuire C.,Francis Crick Institute Mill Hill Laboratory |
Mohun T.,Francis Crick Institute Mill Hill Laboratory |
Adams D.,Wellcome Trust Sanger Institute |
And 24 more authors.
Nucleic Acids Research | Year: 2016
The Deciphering the Mechanisms of Developmental Disorders (DMDD) consortium is a research programme set up to identify genes in the mouse, which if mutated (or knocked-out) result in embryonic lethality when homozygous, and initiate the study of why disruption of their function has such profound effects on embryo development and survival. The project uses a combination of comprehensive high resolution 3D imaging and tissue histology to identify abnormalities in embryo and placental structures of embryonic lethal lines. The image data we have collected and the phenotypes scored are freely available through the project website (http://dmdd.org.uk). In this article we describe the web interface to the images that allows the embryo data to be viewed at full resolution in different planes, discuss how to search the database for a phenotype, and our approach to organising the data for an embryo and a mutant line so it is easy to comprehend and intuitive to navigate. © The Author(s) 2015.
Thavayogarajah T.,University of Marburg |
Gangopadhyay P.,University of Marburg |
Rahlfs S.,Justus Liebig University |
Becker K.,Justus Liebig University |
And 3 more authors.
PLoS ONE | Year: 2015
Plasmodium falciparum invades human red blood cells, residing in a parasitophorous vacuole (PV), with a parasitophorous vacuole membrane (PVM) separating the PV from the host cell cytoplasm. Here we have investigated the role of N-myristoylation and two other N-terminal motifs, a cysteine potential S-palmitoylation site and a stretch of basic residues, as the driving force for protein targeting to the parasite plasma membrane (PPM) and subsequent translocation across this membrane. Plasmodium falciparum adenylate kinase 2 (Pf AK2) contains these three motifs, and was previously proposed to be targeted beyond the parasite to the PVM, despite the absence of a signal peptide for entry into the classical secretory pathway. Biochemical and microscopy analyses of PfAK2 variants tagged with green fluorescent protein (GFP) showed that these three motifs are involved in targeting the protein to the PPM and translocation across the PPM to the PV. It was shown that the N-terminal 37 amino acids of PfAK2 alone are sufficient to target and translocate GFP across the PPM. As a control we examined the N-myristoylated P. falciparum ADP-ribosylation factor 1 (PfARF1). PfARF1 was found to co-localise with a Golgi marker. To determine whether or not the putative palmitoylation and the cluster of lysine residues from the N-terminus of PfAK2 would modulate the subcellular localization of PfARF1, a chimeric fusion protein containing the N-terminus of PfARF1 and the two additional PfAK2 motifs was analysed. This chimeric protein was targeted to the PPM, but not translocated across the membrane into the PV, indicating that other features of the N-terminus of PfAK2 also play a role in the secretion process. © 2015 Thavayogarajah et al.
Lai R.P.J.,Francis Crick Institute Mill Hill Laboratory |
Meintjes G.,University of Cape Town |
Meintjes G.,Imperial College London |
Wilkinson K.A.,Francis Crick Institute Mill Hill Laboratory |
And 19 more authors.
Nature Communications | Year: 2015
Patients with HIV-Associated tuberculosis (TB) initiating antiretroviral therapy (ART) may develop immune reconstitution inflammatory syndrome (TB-IRIS). No biomarkers for TB-IRIS have been identified and the underlying mechanisms are unclear. Here we perform transcriptomic profiling of the blood samples of patients with HIV-Associated TB. We identify differentially abundant transcripts as early as week 0.5 post ART initiation that predict downstream activation of proinflammatory cytokines in patients who progress to TB-IRIS. At the characteristic time of TB-IRIS onset (week 2), the signature is characterized by over-representation of innate immune mediators including TLR signalling and TREM-1 activation of the inflammasome. In keeping with the transcriptional data, concentrations of plasma cytokines and caspase-1/5 are elevated in TB-IRIS. Inhibition of MyD88 adaptor and group 1 caspases reduces secretion of cytokines including IL-1 in TB-IRIS patients. These data provide insight on the pathogenesis of TB-IRIS and may assist the development of specific therapies.
Rockwood N.,Imperial College London |
Rockwood N.,University of Cape Town |
Meintjes G.,Imperial College London |
Meintjes G.,University of Cape Town |
And 7 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2016
There are contrasting data in the literature about antituberculosis plasma drug concentrations in HIV-1-coinfected patients. We report the pharmacokinetics of rifampin, isoniazid, and pyrazinamide in a cohort of patients being treated for active tuberculosis, the majority of whom were coinfected with HIV-1 and had commenced antiretroviral therapy within 2 months of starting antituberculosis treatment. We also examined the association between antituberculosis drug concentrations and reported drug side effects at the 2-month clinical review. One hundred patients with pulmonary tuberculosis (65% coinfected with HIV-1) were intensively sampled to determine rifampin, isoniazid, and pyrazinamide plasma concentrations after 7 to 8 weeks of a daily quadruple- therapy regimen dosed according to World Health Organization (WHO) weight bands. Pharmacokinetic parameters were determined for each patient by using nonlinear mixed-effects models. HIV-1-coinfected patients had lower clearance rates for rifampin (21% decrease) and isoniazid (23% decrease) than HIV-1-uninfected patients, with resulting higher areas under the concentration-time curve from 0 to 24 h (AUC0-24) and maximum concentrations of drug in serum (Cmax). Antiretroviral therapy (ART) that included double-standard-dose lopinavir/ritonavir further lowered rifampin clearance, by 46%, and increased the AUC0-24. The current uniform dosing (per kilogram of body weight) acrossWHOweight bands was associated with a trend of decreased pharmacokinetic exposures for the lowest weight band. Use of fat-free mass as opposed to total body weight for allometric scaling of clearance significantly improved the model. Ambulant HIV-1-coinfected patients, the majority of whom were coprescribed ART, did not have reduced antituberculosis drug concentrations compared to HIV-1-uninfected patients. Copyright © 2016 Rockwood et al.
Diedrich C.R.,University of Cape Town |
O'Hern J.,University of Cape Town |
O'Hern J.,Royal Hobart HospitalTAS |
Wilkinson R.J.,University of Cape Town |
And 2 more authors.
Tuberculosis | Year: 2016
Summary Infection with HIV-1 greatly increases the risk of active tuberculosis (TB). Although hypotheses suggest HIV-1 disrupts Mycobacterium tuberculosis (Mtb) granuloma function, few studies have examined this directly. The objective of this study was to determine what evidence exists about the effect HIV-1 co-infection has upon Mtb granulomas. A systematic search of PubMed, Web of Science, and Medline up to 20 March 2015 was conducted, to identify studies comparing Mtb-infected tissue from HIV-1 infected and uninfected persons, or HIV-1 infected persons with stratified peripheral CD4 T cell (pCD4) counts. We summarized findings that focused on how HIV-1 changes granuloma formation, bacterial presence, cellular composition, and cytokine production. Nineteen studies with a combined sample size of 899 persons were included. Although studies frequently were limited by variable or inadequately described definitions of outcomes and analytical methods, HIV-1 was found to be associated with increased bacillary load within Mtb-infected tissue. Reductions in pCD4 counts within co-infected persons associated with both poorer granuloma formation and higher bacterial load. The high degree of heterogeneity among studies combined with experimental limitations made it difficult to conclusively support previously published and prevalent hypotheses about HIV-1/Mtb co-infection granulomas. To elucidate the validity of these hypotheses we have described areas that can be improved in future studies in order to clarify the influence HIV-1 co-infection has upon the Mtb granuloma. © 2016 Elsevier Ltd.
Lowe D.M.,University of Cape Town |
Lowe D.M.,Imperial College London |
Lowe D.M.,University College London |
Bangani N.,University of Cape Town |
And 11 more authors.
Annals of the American Thoracic Society | Year: 2015
Rationale: Experimental and epidemiological evidence suggests that neutrophils are important in the host response to tuberculosis. HIV infection, which increases the risk of tuberculosis, adversely affects neutrophil function. Objectives: To determine the impact of HIV and antiretroviral therapy on neutrophil antimycobacterial activity. Methods: We performed a cross-sectional comparison of neutrophil functions in 20 antiretroviral-naive HIV-infected and 20 HIV-uninfected individuals using luminescence-, flow cytometry-, and ELISA-based assays. We then conducted a prospective study in the HIV-infected individuals investigating these parameters during the first 6 months of antiretroviral therapy. Surface markers of neutrophil activation were investigated in a separate cohort using flow cytometry. Measurements and Main Results: HIV infection impaired control of Mycobacterium tuberculosis by neutrophils (mean ratio of mycobacterial luminescence in neutrophil samples vs. serum controls at 1 hour in HIV-infected participants, 0.88±0.13 vs. HIVuninfected participants, 0.76±0.14; P = 0.01; at 24 hours, 0.82± 0.13 vs. 0.71±0.13; P = 0.01). The extent of impairment correlated with log[HIV viral load]. Neutrophil cell death after 24 hours' incubation with M. tuberculosis was higher in the HIV-infected cohort (85.3±11.8% vs. 57.9±22.4% necrotic cells; P<0.0001). Neutrophils from HIV-infected participants demonstrated significantly more CD62L-negative cells (median, 23.0 vs. 8.5%; P = 0.008) and CD16-negative cells (3.2 vs. 1.3%, P = 0.03). Antiretroviral therapy restored mycobacterial restriction and pattern of neutrophil death toward levels seen in HIV-uninfected persons. Conclusions: Neutrophils in antiretroviral-naive HIV-infected persons are hyperactivated, eliminate M. tuberculosis less effectively than in HIV-uninfected individuals, and progress rapidly to necrotic cell death. These factors are ameliorated by antiretroviral therapy. Copyright © 2015 by the American Thoracic Society.
Grice J.,Francis Crick Institute Mill Hill Laboratory |
Noyvert B.,Francis Crick Institute Mill Hill Laboratory |
Doglio L.,Francis Crick Institute Mill Hill Laboratory |
Elgar G.,Francis Crick Institute Mill Hill Laboratory
PLoS ONE | Year: 2015
Background: Determining the function of regulatory elements is fundamental for our understanding of development, disease and evolution. However, the sequence features that mediate these functions are often unclear and the prediction of tissue-specific expression patterns from sequence alone is non-trivial. Previous functional studies have demonstrated a link between PBX-HOX and MEIS/PREP binding interactions and hindbrain enhancer activity, but the defining grammar of these sites, if any exists, has remained elusive. Results: Here, we identify a shared sequence signature (syntax) within a heterogeneous set of conserved vertebrate hindbrain enhancers composed of spatially co-occurring PBX-HOX and MEIS/PREP transcription factor binding motifs. We use this syntax to accurately predict hindbrain enhancers in 89% of cases (67/75 predicted elements) from a set of conserved non-coding elements (CNEs). Furthermore, mutagenesis of the sites abolishes activity or generates ectopic expression, demonstrating their requirement for segmentally restricted enhancer activity in the hindbrain. We refine and use our syntax to predict over 3,000 hindbrain enhancers across the human genome. These sequences tend to be located near developmental transcription factors and are enriched in known hindbrain activating elements, demonstrating the predictive power of this simple model. Conclusion: Our findings support the theory that hundreds of CNEs, and perhaps thousands of regions across the human genome, function to coordinate gene expression in the developing hindbrain. We speculate that deeply conserved sequences of this kind contributed to the cooption of new genes into the hindbrain gene regulatory network during early vertebrate evolution by linking patterns of hox expression to downstream genes involved in segmentation and patterning, and evolutionarily newer instances may have continued to contribute to line-age-specific elaboration of the hindbrain. © 2015 Grice et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Campbell K.,University of Cambridge |
Vowinckel J.,University of Cambridge |
Keller M.A.,University of Cambridge |
Ralser M.,University of Cambridge |
Ralser M.,Francis Crick Institute Mill Hill Laboratory
Antioxidants and Redox Signaling | Year: 2016
Nutrient uptake and metabolism have a significant impact on the way cells respond to stress. The amino acid methionine is, in particular, a key player in the oxidative stress response, and acting as a reactive oxygen species scavenger, methionine is implicated in caloric restriction phenotypes and aging. We here provide evidence that some effects of methionine in stress situations are indirect and caused by altered activity of the nicotinamide adenine dinucleotide phosphate (NADPH) producing oxidative part of the pentose phosphate pathway (PPP). In Saccharomyces cerevisiae, both methionine prototrophic (MET15) and auxotrophic (met15Δ) cells supplemented with methionine showed an increase in PPP metabolite concentrations downstream of the NADPH producing enzyme, 6-phosphogluconate dehydrogenase. Proteomics revealed this enzyme to also increase in expression compared to methionine self-synthesizing cells. Oxidant tolerance was increased in cells preincubated with methionine; however, this effect was abolished when flux through the oxidative PPP was prevented by deletion of its rate limiting enzyme, ZWF1. Stress resistance phenotypes that follow methionine supplementation hence involve the oxidative PPP. Effects of methionine on oxidative metabolism, stress signaling, and aging have thus to be seen in the context of an altered activity of this NADP reducing pathway. Antioxid. Redox Signal. 24, 543-547. © Kate Campbell et al., 2016.
Lai R.P.,Francis Crick Institute Mill Hill Laboratory
Nature Medicine | Year: 2016
Tuberculosis is classically divided into states of latent infection and active disease. Using combined positron emission and computed tomography in 35 asymptomatic, antiretroviral-therapy-naive, HIV-1-infected adults with latent tuberculosis, we identified ten individuals with pulmonary abnormalities suggestive of subclinical, active disease who were substantially more likely to progress to clinical disease. Our findings challenge the conventional two-state paradigm and may aid future identification of biomarkers that are predictive of progression. © 2016 Nature Publishing Group, a division of Macmillan Publishers Limited. All Rights Reserved.