Untersuchungen zur Immunantwort unter lymphopenischen Bedingungen und zur Funktion des IgE B-Zellrezeptors

This work deals with two different aspects of the adaptive immune response against viruses and worm parasites. The first part covers the functionality of memory-like CD8 T cells in CD4Cre/R-DTA mice. In CD4Cre/R-DTA mice naïve T cells are deleted due to diphtheria toxin α expression which leads to a reduced number of CD4 and CD8 T cells. These cells differentiate to memory-like T cells (TML), because of homeostatic proliferation. In this work the participation of these memory-like T cells in protective immune responses against the lymphocytic choriomeningitis virus (LCMV) was analyzed. Analysis of CD4Cre/R-DTA mice after infection with LCMV depicted an impaired functionality of memory-like T cells. It could be shown that the number of LCMV-specific T cells was strongly reduced in CD4Cre/R-DTA mice and restimulation experiments proved that the number of Interferon-γ (IFN) producing CD4 and CD8 T cells was strongly decreased. Additionally, the humoral immune response was impaired, because of reduced numbers of germinal center B cells as well as reduced numbers of follicular T helper cells compared to control mice. No difference in LCMV-specific immunoglobulin (Ig) M and IgG1 antibodies could be found, but LCMV-specific IgG2c antibodies were highly diminished. Although an in vivo killing assay demonstrated that CD8 T cells in CD4Cre/R-DTA mice are able to eliminate target cells, the viral load could not be reduced. A block of PD-L1 (programmed cell death 1 ligand 1) could not rescue the functionality of memory-like CD8 T cells. However, a transfer of naïve polyclonal CD4 T cells was able to restore the functional capacity at least partially. As a result, the number of LCMV-specific CD8 T cells and the number of IFN-γ and tumor necrosis factor-α (TNF) CD8 T cells reached a normal level and the viral load was reduced compared to CD4Cre/R-DTA mice. In the second part of this work it should be analyzed if next to the intracellular part of IgG1 the intracellular part of IgE is important for the IgE immune response. To address this the immune response of mice with an inactivated immunoglobulin tail tyrosine (ITT) motif in membrane bound IgG1 or IgE was analyzed after infection with Nippostrongylus brasiliensis (N.b.). Additionally, mice with a truncated intracellular IgE tail were analyzed. It could be demonstrated that the ITT motif in membrane bound IgG1 is important for the IgG1 immune response, but not for the IgE immune response by flow cytometry (FACS) and ELISAs (enzyme-linked immunosorbent assay). On the other hand, the intracellular part of IgE and especially the ITT motif in membrane bound IgE is important for the IgE immune response, what could be confirmed by in vivo experiments and by in vitro data. Surface staining showed that the ITT motif in IgE+ plasma cells promotes the expression and accumulation of membrane bound IgE and thereby enhances their survival after an infection with Nippostrongylus brasiliensis. It could also be shown that the ITT motif in membrane bound IgE is important for the increase of the IgE serum concentration after a systemic allergic reaction and that this has an impact on the mast cell activation.Diese Arbeit befasst sich mit zwei unterschiedlichen Aspekten der adaptiven Immunantwort gegen Viren und Wurmparasiten. Im ersten Teil geht es um die Funktionalität von memory like CD8 T-Zellen in CD4Cre/R-DTA Mäusen. In CD4Cre/R-DTA Mäusen werden naive T-Zellen durch die Expression von Diptherietoxin-α deletiert, was zu einer stark reduzierten Anzahl an CD4 und CD8 T-Zellen führt. Diese entwickeln sich auf Grund von homeostatischer Proliferation zu memory-like T-Zellen (TML). In dieser Arbeit sollte untersucht werden inwieweit diese Zellen an der Immunantwort gegen das lymphozytäre Choriomeningitis Virus (LCMV) beteiligt sind. Die Analyse der CD4Cre/R-DTA Mäuse nach einer Infektion mit LCMV ergab eine eingeschränkte Funktionalität der memory-like T-Zellen. Es konnte gezeigt werden, dass die Anzahl LCMV-spezifischer T-Zellen in CD4Cre/R-DTA Mäusen stark reduziert war, und Restimulationsversuche belegten, dass auch die Zahl Interferon-γ (IFN) produzierender CD4 und CD8 T-Zellen stark vermindert war. Auch die humorale Immunantwort war beeinträchtigt, da sowohl die Anzahl an Keimzentrums-B-Zellen als auch die Zahl der follikulären T-Helferzellen im Vergleich zu Kontrollmäusen verringert war. Die LCMV-spezifischen Immunoglobulin (Ig) M und IgG1 Antikörper zeigten keinen Unterschied zu Kontrollmäusen, doch die LCMV-spezifischen IgG2c Antikörper waren stark reduziert. Obwohl sich durch einen in vivo Zytotoxizitätsnachweis herausstellte, dass die zytotoxischen CD8 T-Zellen in CD4Cre/R-DTA Mäusen in der Lage waren Zielzellen zu eliminieren, konnte die Viruslast nicht eingedämmt werden. Die Blockade von PD-L1 (programmed cell death 1 ligand 1) konnte die Funktionalität der memory-like CD8 T-Zellen nicht verbessern. Doch der Transfer von polyklonalen naiven CD4 T-Zellen war in der Lage die Funktionalität zumindest teilweise wiederherzustellen. Dabei stieg die Zahl der LCMV-spezifischen CD8 T-Zellen und die der IFN-γ und Tumornekrosefaktor-α (TNF) produzierenden CD8 T-Zellen wieder auf ein normales Level an und die Viruslast verringerte sich im Vergleich zu CD4Cre/R-DTA Mäusen. Im zweiten Teil dieser Arbeit sollte herausgefunden werden, ob der intrazelluläre Teil von IgG1 oder IgE wichtig für die IgE Antwort ist. Dazu wurde die Immunantwort von Mäusen, in denen das „immunoglobulin tail tyrosine“ (ITT)-Motiv im intrazellulären Teil von membrangebundenem IgG1 oder IgE inaktiviert wurde, nach einer Infektion mit Nippostrongylus brasiliensis (N.b.) analysiert. Zusätzlich wurden Mäuse untersucht, deren intrazellulärer IgE Teil auf drei Aminosäuren reduziert war. Durch durchflusszytometrische Analysen (FACS) und ELISAs (enzyme-linked immunosorbent assay) konnte gezeigt werden, dass das ITT-Motiv in membrangebundenem IgG1 zwar wichtig für die IgG1 Immunantwort, aber nicht für die IgE Immunantwort ist. Dagegen ist der intrazelluläre Teil von IgE und im Speziellen das ITT-Motiv in membrangebundenem IgE wichtig für die IgE Immunantwort, was neben in vivo Experimenten auch durch in vitro Daten belegt werden konnte. Durch Oberflächenfärbung konnte gezeigt werden, dass IgE+ Plasmazellen das ITT-Motiv für die Expression und die Akkumulation von membrangebundenem IgE nach einer Infektion mit Nippostrongylus brasiliensis benötigen und dadurch ihr Überleben gefördert wird. Es konnte ferner gezeigt werden, dass das ITT-Motiv in membrangebundenem IgE für die Zunahme der IgE Konzentration im Serum nach einer systemischen allergischen Reaktion wichtig ist und dass dies Auswirkungen auf die Mastzellaktivierung hat

CD4 T Helper Cells Instruct Lymphopenia-Induced Memory-Like CD8 T Cells for Control of Acute LCMV Infection

Lymphopenic conditions lead to expansion of memory-like T cells (TML), which develop from naïve T cells by spontaneous proliferation. TML cells are often increased in the elderly population, AIDS patients, and patients recovering from radio- or chemotherapy. At present, it is unclear whether TML cells can efficiently respond to foreign antigen and participate in antiviral immunity. To address this question, we analyzed the immune response during acute low-dose infection with lymphocytic choriomeningitis virus-WE in T cell lymphopenic CD4Cre/R-diphtheria toxin alpha (DTA) mice in which most peripheral T cells show a TML phenotype. On day 8 after infection, the total number of effector T cells and polyfunctional IFN-γ and TNF-α producing CD8 T cells were three- to fivefold reduced in CD4Cre/R-DTA mice as compared to controls. Viral clearance and the humoral immune response were severely impaired in CD4Cre/R-DTA mice although CTLs efficiently killed transferred target cells in vivo. Transfer of naïve CD4 T cells but not anti-PD-L1 blockade restored the expansion of antigen-specific polyfunctional CD8 T cells and resulted in lower viral titers. This finding indicates that under lymphopenic conditions endogenous CD4 TML cell lack the capacity to promote expansion of CTLs. However, CD8 TML cells retain sufficient functional plasticity to participate in antiviral immunity in the presence of appropriate help by fully functional CD4 T cells. This capacity might be exploited to develop treatments for improvement of CD8 T cell functions under various clinical settings of lymphopenia

The Predictive Value of PITX2 DNA Methylation for High-Risk Breast Cancer Therapy: Current Guidelines, Medical Needs, and Challenges

High-risk breast cancer comprises distinct tumor entities such as triple-negative breast cancer (TNBC) which is characterized by lack of estrogen (ER) and progesterone (PR) and the HER2 receptor and breast malignancies which have spread to more than three lymph nodes. For such patients, current (inter)national guidelines recommend anthracycline-based chemotherapy as the standard of care, but not all patients do equally benefit from such a chemotherapy. To further improve therapy decision-making, predictive biomarkers are of high, so far unmet, medical need. In this respect, predictive biomarkers would permit patient selection for a particular kind of chemotherapy and, by this, guide physicians to optimize the treatment plan for each patient individually. Besides DNA mutations, DNA methylation as a patient selection marker has received increasing clinical attention. For instance, significant evidence has accumulated that methylation of the PITX2 (paired-like homeodomain transcription factor 2) gene might serve as a novel predictive and prognostic biomarker, for a variety of cancer diseases. This review highlights the current understanding of treatment modalities of high-risk breast cancer patients with a focus on recommended treatment options, with special attention on the future clinical application of PITX2 as a predictive biomarker to personalize breast cancer management

Costly third-party interventions: The role of incidental anger and attention focus in punishment of the perpetrator and compensation of the victim

publisher: Elsevier articletitle: Costly third-party interventions: The role of incidental anger and attention focus in punishment of the perpetrator and compensation of the victim journaltitle: Journal of Experimental Social Psychology articlelink: http://dx.doi.org/10.1016/j.jesp.2016.04.004 content_type: article copyright: © 2016 Elsevier Inc. All rights reserved

Application of Complexity Measures to Stratospheric Dynamics

This thesis examines the utility of mathematical complexity measures for the analysis of stratospheric dynamics. Through theoretical considerations and tests with artificial data sets, e.g., the iteration of the logistic map, suitable parameters are determined for the application of the statistical entropy measures sample entropy (SE) and Rényi entropy (RE) to methane (a long-lived stratospheric tracer) data from simulations of the SOCOL chemistry-climate model. The SE is shown to be useful for quantifying the variability of recurring patterns in a time series and is able to identify tropical patterns similar to those reported by previous studies of the ``tropical pipe'' region. However, the SE is found to be unsuitable for use in polar regions, due to the non-stationarity of the methane data at extra-tropical latitudes. It is concluded that the SE cannot be used to analyse climate complexity on a global scale. The focus is turned to the RE, which is a complexity measure of probability distribution functions (PDFs). Using the second order RE and a normalisation factor, zonal PDFs of ten consecutive days of methane data are created with a Bayesian optimal binning technique. From these, the RE is calculated for every day (moving 10-day window). The results indicate that the RE is a promising tool for identifying stratospheric mixing barriers. In Southern Hemisphere winter and early spring, RE produces patterns similar to those found in other studies of stratospheric mixing. High values of RE are found to be indicative of the strong fluctuations in tracer distributions associated with relatively unmixed air in general, and with gradients in the vicinity of mixing barriers, in particular. Lower values suggest more thoroughly mixed air masses. The analysis is extended to eleven years of model data. Realistic inter-annual variability of some of the RE structures is observed, particularly in the Southern Hemisphere. By calculating a climatological mean of the RE for this period, additional mixing patterns are identified in the Northern Hemisphere. The validity of the RE analysis and its interpretation is underlined by showing that qualitatively similar patterns can be seen when using observational satellite data of a different tracer. Compared to previous techniques, the RE has the advantage that it requires significantly less computational effort, as it can be used to derive dynamical information from model or measurement tracer data without relying on any additional input such as wind fields. The results presented in this thesis strongly suggest that the RE is a useful new metric for analysing stratospheric mixing and its variability from climate model data. Furthermore, it is shown that the RE measure is very robust with respect to data gaps, which makes it ideal for application to observations. Hence, using the RE for comparing observations of tracer distributions with those from model simulations potentially presents a novel approach for analysing mixing in the stratosphere

Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London