1,721,053 research outputs found
Role of Mitochondrial Protein TCAIM in Preventing Lung Infiltration and T cell-induced Immunopathology
Full text linkSeasonal outbreaks of Influenza A virus (IAV) infections repeatedly challenge the immune system, which is in charge of controlling viral replication and facilitating clearance and subsequently recovery. T cells, which are part of the adaptive immune system, provide a highly specific response towards IAV during the acute infection phase that supports viral clearance. For that, activated effector T cells migrate from the lung-draining lymph nodes (drLN) to the side of infection, where they induce cell death of infected cells. Besides effector function in the lung, the follicular T helper cell subset provides help to B cells in drLN thereby supporting plasma cell differentiation and production of neutralizing antibodies. Furthermore, memory T cells reside long term in the body and serve as protection against re-infections. Although the T cell response is crucial for virus control, it has to be tightly regulated as T cell induced immunopathology and collateral tissue damage is disadvantageous.
The protein T cell activation inhibitor, mitochondrial (TCAIM) was previously found to interfere with effector T cell differentiation and function. Yet, TCAIM overexpressing T cells were able to respond to activating stimuli by entering the proliferation cycle and reduced cytokine production. Thus, within the scope of this work, the question was addressed, if the degree of T cell activation and differentiation in TCAIM overexpressing mice is sufficient to facilitate viral clearance and to support establishment of a protective memory T cell pool. Furthermore, no in vivo data are available for TCAIM deficient T cells, but previous in vitro work showed an advantage in T cell activation under sub-optimal stimulation conditions. This raises the question, whether viral control is improved in TCAIM deficient mice.
The here presented data show an impaired lung infiltration of TCAIM overexpressing T cells upon IAV infection, which is linked to the failure to modulate CD44 and CD62L receptor expression and upregu-lation of genes involved in migration and effector T cell differentiation. As a functional consequence cytokine production was diminished and viral clearance delayed. Nevertheless, TCAIM overexpressing mice did recover from IAV infection and were able to respond to infection induced activation stimuli seen in undisturbed type I interferon (IFN) signalling and T cell expansion within drLN. Importantly, reduced T cell response at the side of infection prevented T cell induced immunopathology since TCAIM overexpressing mice only slightly lost weight. Surprisingly, although generation of lung homing effector and tissue resident memory T cells was impaired, neutralizing antibodies were formed which might serve as protection during re-infection. TCAIM deficient T cells were found to predominantly accumulate at the side of infection. Early upregulation of Ifng and genes involved in T cell activation however did not translate into increased IFN-γ production at the peak of infection and improved viral control.
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In conclusion, the data within this work highlight the impact of TCAIM on T cell migration and the prevention of T cell induced immunopathology thereby proposing a beneficial role during IAV infections
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
mathematical modeling and data analysis of antibody-peptide reactivity data
Full text linkHumorale Immunantworten gehen einher mit der Veränderung der Zusammensetzung und der Konzentration des Antikörper (AK)-Repertoires. Signalintensitäts-basierte AK-Bindungsprofile (ABP), gemessen mit Zufallspeptidmikroarrays, versuchen diese Veränderungen zu detektieren, um sie für serologische Diagnostik nutzbar zu machen. Gegenstand dieser Arbeit ist die Analyse des Einflusses des AK-Repertoires auf ABP mittels eines mathematischen Modells für AK-Peptidbindung. Das Modell basiert auf dem MWG und beinhaltet als Parameter (i) AK- und Peptidsequenzen sowie (ii) AK-Konzentrationen. Die Affinität simulierter monoklonaler AK hängt nichtlinear von den Aminosäurepositionen in den Peptidsequenzen ab. Das Modell wurde mathematisch analysiert und in silico implementiert. Simulationen ergaben, dass ABP von Mischungen hochdiverser, zufällig generierter AK-Sequenzen, welche nicht durch wenige AK konzentrationsdominiert sind, genannt ideale Mischungen, linear ausschließlich mit Hilfe der Aminosäurezusammensetzung der Peptidbibliothek vorhergesagt werden können. Dieser Zusammenhang führte zu der Formulierung eines linearen Regressionsmodells, aus welchem Aminosäure-assoziierte Gewichte (AAWS) hervorgehen, welche eine kompakte, verlustfreie Abbildung von ABP idealer Mischungen darstellen. Für niedrig-diverse Mischungen ist die Vorhersagekraft des Regressionsmodells eingeschränkt. Die in vitro-Relevanz der mathematisch vorhergesagten Ensembleeigenschaften von AK-Mischungen wurde durch Inkubationen monoklonaler AK und Serum-AK mit derselben Peptidbibliothek bestätigt. Diese Arbeit zeigt, dass Kenntnisse über die Zusammensetzung einer polyklonalen Mischung essentiell für die Interpretation von ABP in Bezug auf serologische Diagnostik und Epitopkartierung sind. Die Spezifität und damit auch die Klassifizierbarkeit von ABP ist sowohl eine Funktion der untersuchten AK-Mischung als auch technologischer Faktoren.Humoral immune responses are associated with changes of both the composition and the concentration of serum antibodies. Signal intensity- based antibody binding profiles (ABP) measured with random-sequence peptide microarrays attempt to capture these changes to render them applicable to serological diagnostics. In this work, the antibody repertoire’s impact on ABP is studied. This model is based on the law of mass action and incorporates as parameters (i) antibody and peptide sequences and (ii) antibody concentrations. The binding affinity of simulated monoclonal antibodies depends non-linearly on amino acid positions in the peptide sequences. The model was both mathematically analyzed and implemented in silico. Mathematical analysis and simulations predicted that mixtures of highly diverse random antibodies which are not dominated concentration-wise by few antibodies, termed unbiased mixtures, could be linearly predicted based only on the amino acid composition of the peptide library used. This linear relationship led to the formulation of a linear regression model of which amino acid associated-weights (AAWS) emerge as a compact, lossless representation of unbiased mixtures’ ABP. For lowly diverse antibody mixtures, this linear regression model breaks down. In order to test the in vitro relevance of the mathematically predicted ensemble properties of antibody mixtures, monoclonal and serum antibodies were incubated with the same peptide library. In conclusion, this work shows that serum antibody ensemble properties impact the genesis of ABP measured with random-sequence peptide microarrays. This thesis indicates that a knowledge of both a polyclonal mixture’s diversity and composition is essential for the interpretation of ABP with respect to both serological diagnostics and B-cell epitope mapping. Specificity, and thus classifiability, of serum ABP is a function of both the investigated antibody mixtures and technological features
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Vorklinische Untersuchungen zur Wirkung einer Tumorvakzine in der Therapie Human Papillomvirus-assoziierter Tumorerkrankungen
Full text linkNeuartige Vakzinierungsstrategien zur Aktivierung einer Tumor-spezifischen zellulären Immunantwort sind vielversprechende Ansätze zur Therapie von Tumoren, insbesondere Human Papillomvirus (HPV)-assoziierte Tumore. Bisherige HPV-Impfstudien zeigen zwar die Aktivierung einer spezifischen zellulären Immunantwort, eine Tumorreduktion bleibt jedoch aus. Um diesen Effekt auf Immunzellebene zu definieren, wurde die Wirkung der HPV-Vakzine Ad p14 im Mausmodell und an Untersuchungsmaterial humaner Tumore analysiert. In Mäusen bildeten sich HPV+ TC1-Tumore einer frühen Entwicklungsphase nach Vakzinierung zurück. Tumore einer späten Entwicklungsphase wuchsen dagegen in zwei Intervallen aus. Immunologische Eigenschaften der Tumorzellen blieben dabei unverändert. Unterschiede zeigten sich in den Frequenzen Tumor-infiltrierender Lymphozyten; in progressiven Phasen wurden nur CD4+ T Zellen nachgewiesen, in Regressionsphasen zusätzlich zytotoxische CD8+ T Zellen. Immunmodulatoren, wie Interferon alpha oder DTA-1, einem Antikörper für den Glucocorticoid-induzierten Tumornekrosefaktor-Rezeptor, unterstützten die Wirkung der Vakzine; letzterer erhöhte die Anzahl zytotoxischer CD8+ T Zellen und führte zur Abstoßung der TC1-Tumore. HPV+ Tumorgewebe des Menschen, wie auch ihre Vorstufen, zeigten im Vergleich zu anderen Tumoren, wie Bronchial oder Kolonkarzinomen einen signifikant höheren Anteil an CD4+ und CD8+ T Zellen und an Forkhead Box P3+ regulatorischen T Zellen. Die Ergebnisse deuten darauf hin, dass die immunologischen Abläufe bei der Entwicklung HPV-assoziierter Tumore mit denen vorangeschrittener chronischer Erkrankungen vergleichbar sind, in denen sich CD4+ und CD8+ T Zellantworten erschöpfen während sich gleichzeitig immunsuppressive Mechanismen verstärken. Um die Entwicklung von Impfstoffen zur Therapie HPV-assoziierter Tumore zu verbessern sollten diese Mechanismen ausführlicher betrachtet werden.Novel vaccination strategies, activating cellular tumour specific immune responses represent a promising approach for the treatment of cancer. Especially featured for these treatments are tumours evolving from chronic human papillomavirus (HPV) infections. But current strategies have not yet proved efficacious for complete tumour regression. Addressing cellular immunological aspects of tumour vaccination, this work focused on effects of HPV vaccine Ad p14 in mice and in samples of human tumours. In mice vaccination resulted in complete regression of early stage murine HPV+ TC1 tumours. Late stage TC1 tumours increased discontinuously. During that process, TC1 cells preserved their immunological characteristics. But frequencies of tumour-infiltrating lymphocytes varied; in progressing tumours only CD4+ T cells occurred, in temporary regressing tumours also CD8+ T cells were detected. Immune modulators, like interferon alpha or glucocorticoid-induced tumour necrosis factor receptor targeting antibody DTA-1 aggravated the effects of vaccination; latter raised cytotoxic CD8+ T cell numbers and resulted in complete tumour regression. Human HPV+ tumours as well as HPV+ precancerous stages revealed numbers of CD4+ and CD8+ T cells and especially of forkhead box P3+ regulatory T cells that were significantly increased compared to melanoma, bronchial or colon carcinoma. To assist further analysis of human HPV-associated cervical cancer and facilitate studies on therapeutic approaches, a humanized mouse model was established. The present work points to immunological exhaustion in the development of HPV-related tumours comparable to chronic diseases where CD4+ and CD8+ T cells exhaust and immunosuppression by regulatory T cells increases at the same time. For the development of appropriate strategies to enhance efficacy in HPV-associated tumour therapy, further knowledge of mechanisms involved in specific T cell activation, T cell exhaustion and immunosuppression is necessary
Identification of differential regulation in central carbon metabolism between related cell lines
Full text linkDarmkrebszellen und T-Zellen regulieren ihren zentralen Kohlenstoffmetabolismus um
ihren anabolen Bedarf zu erfüllen. Tumorzellen mit einer KRAS- oder BRAF-Mutation
zeigen ein schnelles Wachstum, welches eine Umprogrammierung des Metabolismus vor
aussetzt. Der mitochondriale T-Zellen-Aktivierungsinhibitor (TCAIM) ist bekannt dafür
die mitochondriale Zellstruktur zu beeinflussen. Der Einfluss auf den Metabolismus nicht
klar.
In dieser Arbeit präsentiere ich erstmalig ein mathematische Model des zentralen Kohlen
stoffmetabolismus in Darmkrebszellen und T-Zellen. Mithilfe dieses Modells analysiere
ich, wie sich die Regulation in ähnlichen Zelllinien unterscheidet. In Bezug auf die Darm
krebszellen vergleiche ich BRAF-(CaCO2-BRAFV600E), KRAS-(CaCO2-KRASG12V) mu
tierte Zelllinien mit einer Basiszelllinie (CaCO2-control) und zeige, dass der Kohlenstoff
metabolismus in BRAF-mutierten Zellen im Vergleich zu den beiden übrigen Zelllinien
herabreguliert ist. Das Modell bestätigt außerdem, dass der Monocarboxylattransporter
(MCT) in den Darmkrebszellen eine wichtige Rolle, insbesondere in den KRAS mu
tierten Zellen, spielt. In T-Zellen zeigt der Vergleich von Wildtypzellen (CD8 T-Zellen)
mit TCAIM homozygoten Zellen (TCAIM homozygote CD8 T-Zellen), dass der Kohlen
stoffmetabolismus in zweiteren überwiegend herabreguliert und weniger aktiv ist. Diesen
Effekt konnte ich durch die Analyse von RNASeq-Daten der jeweiligen Zelltypen bestä-
tigen. Des Weiteren stelle ich fest, dass sich der Tricarbonsäurezyklus umkehrt, wenn
durch die Glykolyse nicht ausreichend Laktat exportiert und die Biomasseproduktion
unterstützt werden kann.
Meine Arbeit stellt damit insgesamt einen neuartigen Ansatz zur Integration von Meta
bolomik und RNAseq Daten dar, um die Regulation des zentralen Kohlenstoffmetabo
lismus zu verstehen.Colon cancer cells and T cells regulate central carbon metabolism to meet their anabolic
needs. In KRAS and BRAF tumors, metabolic reprogramming is a premise to support
rapid proliferation. In T cells, the mitochondrial T cell activation inhibitor (TCAIM)
is known to affect mitochondrial morphology but its effect on cellular metabolism is
not well understood. Via mathematical modelling, I investigate the differential regulation of closely related cell lines. I present the first mathematical model for colon cancer and T cell metabolism, unraveling differential regulation between related cell lines.
The model shows that CaCO2-BRAFV600Ecells are mostly downregulated compared to
CaCO2-KRASG12Vand CaCO2-control. Additionally, it demonstrates the critical role
of monocarboxylate transporter (MCT), especially for CaCO2-KRASG12V. Concerning T cells, I compare wild-type T cells to homozygous TCAIM T cells. This unveils
that TCAIM homozygous cells have a mostly downregulated TCA cycle, validated by
RNASeq data, and are less metabolically active than wild-type T cells. Furthermore,
if the glycolytic flux is not sufficient to support lactate export and biomass production,
the model reveals that the TCA cycle is reversed as it requires less regulation. Taken
together, this work presents a novel approach to integrate data referring to metabolic
and genetic regulation of metabolism. On this basis, we can now better discriminate the
metabolic capacity of CaCO2-control, CaCO2-BRAFV600E, CaCO2-KRASG12V, wildtype CD8 T cells, and homozygous TCAIM CD8 T cells
Lokalisierung und Charakterisierung Foxp3+ regulatorischer T-Zellen bis zu 30 Tage nach mechanischer und ischämischer Läsion des Gehirns
Full text linkNach einer Läsion im Gehirn kommt es trotz der Bildung autoreaktiver T-Zellen zu keiner autoimmunen Neuropathologie. Foxp3+ regulatorische T-Zellen (Tregs) vermitteln möglicherweise Immuntoleranz nach zerebraler Läsion. Deswegen wurde in dieser Studie die Rolle der Tregs 7, 14 und 30 Tage nach einem transienten Verschluss der mittleren Hirnarterie (MCAO), einem Modell für ischämischen Schlaganfall, und nach entorhinaler Kortexläsion (ECL) in der Maus untersucht. Durchflusszytometrisch wurde in beiden Modellen 14 und 30 Tage nach Läsion eine Akkumulation der Tregs in der ipsilateralen Hemisphäre beobachtet. Mikroskopisch wurden an der Läsion Zellkontakte der Tregs mit antigenpräsentierenden Zellen beobachtet. Weitere Experimente wurden ausschließlich nach MCAO durchgeführt. Am Tag 14 und 30 war in der ipsilateralen Hemisphäre eine Akkumulation der Mikroglia zu beobachten. Makrophagen und dendritische Zellen wurden an den Tagen 7, 14 und 30 detektiert. Am Tag 7 und 14 waren ipsilateral im Gehirn ca. 60 % der Tregs positiv für den Proliferationsmarker Ki-67. In zwei Versuchsansätzen wurden naive CD45RBhigh/CD4+ Zellen aus lymphatischen Organen von Foxp3EGFP Mäusen, mit Wildtyp T-Zellrezeptor (TCR), oder 2D2.Foxp3EGFP Mäusen, mit TCR spezifisch gegen Myelin-Oligodendrozyten-Glykoprotein, isoliert. Die Zellen wurden einen Tag vor MCAO in RAG1-/- Mäuse, welche keine adulten T- und B-Zellen besitzen, transferiert. Am Tag 14 nach MCAO war in den RAG1-/- Mäusen keine de novo Induktion Foxp3EGFP+ Tregs zu beobachten. CD25+ Tregs wurden durch die Injektion eines Antikörpers gegen CD25 depletiert, um deren Wirkung nach MCAO zu untersuchen. Nach Depletion konnte bis zu 27 Tage nach MCAO keine Veränderung des Läsionsvolumen und des Gangverhaltens beobachtet werden. In dieser Studie wurde im Gehirn eine späte Präsenz und Proliferation Foxp3+ Tregs nach Läsion nachgewiesen. Mikroglia und periphere Immunzellen sind langfristig an Immunvorgängen im lädierten Gehirn beteiligt.After brain lesion autoreactive T cells specific against brain antigens are expanded, but no delayed autoimmune neuropathology evolves. Immune suppressive CD4+/Foxp3+ regulatory T cells (Tregs) could have an important role in maintaining immune tolerance in the lesioned brain. Therefore, this study sought to analyse the role of Tregs in mice 7, 14 and 30 days after transient middle cerebral artery occlusion (MCAO), a model for ischemic stroke, and entorhinal cortex lesion (ECL). An accumulation of Tregs was detected in the brain by flow cytometry in both models at days 14 and 30 after lesion. Using immunohistochemistry Tregs were found in close cell-cell contact with antigen presenting cells at the lesion site. Further experiments were performed solely with MCAO. On days 14 and 30 after MCAO a strong accumulation of microglia occurred in the ipsilesional hemisphere. Macrophages and dendritic cells were found ipsilesionally on days 7, 14 and 30. On days 7 and 14 about 60% of Tregs were positive for the proliferation marker Ki-67 in the lesioned hemisphere. In two different setups naïve CD45RBhigh/CD4+ cells were isolated from lymphatic organs of Foxp3EGFP mice, carrying a wild type T cell receptor (TCR), or 2D2.Foxp3EGFP mice, carrying a TCR specific for myelin oligodendrocyte glycoprotein. One day before MCAO naïve CD45RBhigh/CD4+ cells depleted of Foxp3EGFP+ Tregs were transferred into RAG1-/- mice, which lack adult B and T cells. At day 14 after MCAO no de novo generation of Foxp3EGFP+ Tregs was observed. The effects of Tregs on stroke outcome were tested by depleting CD25+/Foxp3EGFP+ Tregs with an antibody against CD25. After depletion no effects on lesion volumes and gait parameters were detected up to 27 days following MCAO. The present study demonstrates for the first time a sustained presence and proliferation of Tregs in the lesioned brain. Local microglia and peripheral immune cells are involved in long-lasting immune processes following brain lesion
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