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Die Rolle des Immunsystems nach MI hat innerhalb der letzten Jahrzehnte immer mehr Aufmerksamkeit erfahren, trotzdem herrschen weiterhin einige Unklarheiten. Daher war es Ziel dieser Arbeit, das Verhalten der T-Zellen nach MI im Mausmodell näher zu betrachten und zu analysieren. Dafür wurde einerseits mittels Durchflusszytometrie die T-Zell-Immunantwort im Herzen und in verschiedenen lymphatischen Organen mit Fokus auf pro- und antiinflammatorische Zytokine und deren Transkriptionsfaktoren genauer analysiert und andererseits ein Protokoll etabliert, um die T-Zellen im Herzen und in den Lymphknoten mittels Lichtblattmikroskopie sichtbar zu machen.
Dabei konnte festgestellt werden, dass die Expression von LAP, welches nicht-kovalent an das antiinflammatorische Zytokin TGF-ß1 gebunden ist und das wichtig für eine ausgeglichene Immunantwort ist, indem es überschießende Entzündungsreaktionen verhindert, in T-Zellen im Herzen nach MI im Vergleich zu naiven und scheinoperierten Mäusen signifikant hochreguliert war. Dieses Ergebnis konnte nur im Herzen und in keinem anderen der untersuchten Organe erzielt werden, weshalb es sich somit um eine lokale Immunreaktion handeln muss, die nur im Herzen nach MI stattfindet. Eine weitere Besonderheit war, dass die Häufigkeit des Vorkommens an Foxp3+ Treg im Herzen im Vergleich zu den anderen untersuchten Organen durchgehend am höchsten war, sowohl bei den Mäusen nach MI als auch bei naiven und scheinoperierten Mäusen. Dies unterstreicht, dass Foxp3+ Treg im Herzen eine wichtige Rolle spielen.
Dank der Verbesserung des Protokolls zur bildlichen Darstellung von T-Zellen im Herzen konnte gezeigt werden, dass sich diese nach MI insbesondere im Infarktgewebe befinden und dort relativ gleichmäßig verteilt sind. Außerdem konnten die mediastinalen Lymphknoten im Ganzen dargestellt und die einzelnen T-Zellen sichtbar gemacht werden.
Insgesamt lässt sich sagen, dass durch die vorliegende Arbeit neue Erkenntnisse zur Charakterisierung der T-Zell-Immunantwort nach MI im Mausmodell hinzugewonnen werden konnten. Die LAP+ T-Zellen scheinen nach MI im Herzen eine wichtige Rolle zu spielen, weshalb die Funktion dieser Zellen im Reparaturprozess nach MI in zukünftigen Versuchen genauer betrachtet werden sollte. Außerdem wurde der Grundstein zur Anfärbung und Darstellung von T-Zellen in Herzen und in Lymphknoten mittels Lichtblattmikroskopie gelegt, weshalb daran weitergearbeitet werden sollte, um auch andere Immunzellen neben den T-Zellen zeigen zu können. Dadurch können weitere Hinweise auf das Zusammenspiel der Immunzellen nach MI erhalten werden, um die immunologischen Vorgänge immer besser verstehen zu können.
Although the field of fungal infections advanced tremendously, diagnosis of invasive pulmonary aspergillosis (IPA) in immunocompromised patients continues to be a challenge. Since IPA is a multifactorial disease, investigation from different aspects may provide new insights, helpful for improving IPA diagnosis. This work aimed to characterize the human immune response to Aspergillus fumigatus in a multilevel manner to identify characteristic molecular candidates and risk factors indicating IPA, which may in the future support already established diagnostic assays. We combined in vitro studies using myeloid cells infected with A. fumigatus and longitudinal case-control studies investigating patients post allogeneic stem cell transplantation (alloSCT) suffering from IPA and their match controls.
Characteristic miRNA and mRNA signatures indicating A. fumigatus-infected monocyte-derived dendritic cells (moDCs) demonstrated the potential to differentiate between A. fumigatus and Escherichia coli infection. Transcriptome and protein profiling of alloSCT patients suffering from IPA and their matched controls revealed a distinctive IPA signature consisting of MMP1 induction and LGAL2 repression in combination with elevated IL-8 and caspase-3 levels. Both, in vitro and case-control studies, suggested cytokines, matrix-metallopeptidases and galectins are important in the immune response to A. fumigatus. Identified IPA characteristic molecular candidates are involved in numerous processes, thus a combination of these in a distinctive signature may increase the specificity. Finally, low monocyte counts, severe GvHD of the gut (grade ≥ 2) and etanercept administration were significantly associated with IPA diagnosis post alloSCT. Etanercept in monocyte-derived macrophages (MDM) infected with A. fumigatus downregulates genes involved in the NF-κB and TNF-α pathway and affects the secretion of CXCL10.
Taken together, identified characteristic molecular signatures and risk factors indicating IPA may in the future in combination with established fungal biomarkers overcome current diagnostic challenges and help to establish tailored antifungal therapy. Therefore, further multicentre studies are encouraged to evaluate reported findings.
Rolle der gammadelta T-Zellen in der Immunantwort bei Patienten mit gastrointestinalen Tumoren
(2022)
Zusammenfassend konnte im Rahmen der vorliegenden Arbeit die Frage nach der Fähigkeit der selektiven Stimulierung mittels des Phosphorantigens HMBPP und den beiden BTN3 Antikörpern bestätigt werden. Es konnte zudem wie erwartet hierbei ein Unterschied zwischen den beiden Kohorten detektiert werden. Dabei zeigte die Kohorte der Normalspender erwartungsgemäß eine stärkere Aktivierungs- sowie Proliferations-fähigkeit. Normalspender ließen sich signifikant besser mit HMBPP aktivieren und bei bestimmter Konzentration signifikant besser proliferieren, bei BTN3A und sc20.1 konnten keine signifikanten Unterschiede ermittelt werden, allerdings anhand der Mittelwerte eine deutlich stärkere Aktivierung und Proliferation aufgezeigt werden. Außerdem konnten interessante interindividuelle Unterschiede detektiert werden, die neue Erkenntnisse brachten. Mit Hilfe der untersuchten Oberflächenmoleküle CD45RA und CD27 und der Einteilung der gammadelta T-Zellen in unterschiedliche Subgruppen konnten so mögliche Erklärungen für die Unterschiede zwischen den Kohorten aufgezeigt werden. Normalspender zeigten signifikant höhere Anteile an naiven gammadelta T-Zellen und nicht signifikant höhere Anteile an central memory T-Zellen, demnach eine deutliche Verschiebung in Richtung nicht differenzierter Subsets, wohingegen die Tumorkohorte signifikant höhere effector memory T-Zellen aufwiesen und somit eine deutliche Verschiebung in Richtung differenzierter Subsets. Dadurch kann erklärt werden, weshalb Normalspender besser aktiviert werden und besser proliferieren können. Auch die Einteilung in unterschiedliche Profile 1-6 anhand CD28, CD27 und CD16 lieferte Gründe für den Unterschied zwischen den Kohorten, wobei Normalspender der Gruppe 1 und 2, Tumorpatienten der Gruppe 3 und 4 angehörten. Durch Ermittlung weiterer signifikanter Änderungen einiger exprimierter Oberflächenmoleküle CD39, CD161 und PD1 wurde mit Hilfe der vorliegenden Arbeit bekräftigt, dass einige Faktoren betrachtet werden müssen, die die Proliferation und Aktivierung der gammadelta T-Zellen positiv und negativ beeinflussen können. Es konnte jedoch auch erneut verdeutlicht werden, wie komplex und weitgreifend der Aktivierungsmechanismus, die damit verbundene Expansion und die Auslösung der einzelnen Effektorfunktionen ist.
The SF-1 transcription factor target gene FATE1 encodes a cancer-testis antigen that has an important role in regulating apoptosis and response to chemotherapy in adrenocortical carcinoma (ACC) cells. Autoantibodies directed against FATE1 were previously detected in patients with hepatocellular carcinoma. In this study, we investigated the prevalence of circulating anti-FATE1 antibodies in pediatric and adult patients with adrenocortical tumors using three different methods (immunofluorescence, ELISA and Western blot). Our results show that a pervasive anti-FATE1 immune response is present in those patients. Furthermore, FATE1 expression is a robust prognostic indicator in adult patients with ACC and is associated with increased steroidogenic and decreased immune response gene expression. These data can open perspectives for novel strategies in ACC immunotherapy.
Objectives
The severity of Coronavirus Disease 2019 (COVID-19) is largely determined by the immune response. First studies indicate altered lymphocyte counts and function. However, interactions of pro- and anti-inflammatory mechanisms remain elusive. In the current study we characterized the immune responses in patients suffering from severe COVID-19-induced acute respiratory distress syndrome (ARDS).
Methods
This was a single-center retrospective study in patients admitted to the intensive care unit (ICU) with confirmed COVID-19 between March 14th and May 28th 2020 (n = 39). Longitudinal data were collected within routine clinical care, including flow-cytometry of lymphocyte subsets, cytokine analysis and growth differentiation factor 15 (GDF-15). Antibody responses against the receptor binding domain (RBD) of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Spike protein were analyzed.
Results
All patients suffered from severe ARDS, 30.8% died. Interleukin (IL)-6 was massively elevated at every time-point. The anti-inflammatory cytokine IL-10 was concomitantly upregulated with IL-6. The cellular response was characterized by lymphocytopenia with low counts of CD8+ T cells, natural killer (NK) and naïve T helper cells. CD8+ T and NK cells recovered after 8 to 14 days. The B cell system was largely unimpeded. This coincided with a slight increase in anti-SARS-CoV-2-Spike-RBD immunoglobulin (Ig) G and a decrease in anti-SARS-CoV-2-Spike-RBD IgM. GDF-15 levels were elevated throughout ICU treatment.
Conclusions
Massively elevated levels of IL-6 and a delayed cytotoxic immune defense characterized severe COVID-19-induced ARDS. The B cell response and antibody production were largely unimpeded. No obvious imbalance of pro- and anti-inflammatory mechanisms was observed, with elevated GDF-15 levels suggesting increased tissue resilience.
Inflammation and dysregulation of the immune system are hallmarks of several neurodegenerative diseases. An activated immune response is considered to be the cause of myelin breakdown in demyelinating disorders. In the peripheral nervous system (PNS), myelin can be degraded in an autophagy-dependent manner directly by Schwann cells or by macrophages, which are modulated by T-lymphocytes. Here, we show that the NF-κB activator Pleckstrin homology containing family member 5 (Plekhg5) is involved in the regulation of both Schwann cell autophagy and recruitment of T-lymphocytes in peripheral nerves during motoneuron disease. Plekhg5-deficient mice show defective axon/Schwann cell units characterized by myelin infoldings in peripheral nerves. Even at late stages, Plekhg5-deficient mice do not show any signs of demyelination and inflammation. Using RNAseq, we identified a transcriptional signature for an impaired immune response in sciatic nerves, which manifested in a reduced number of CD4\(^+\) and CD8\(^+\) T-cells. These findings identify Plekhg5 as a promising target to impede myelin breakdown in demyelinating PNS disorders.
Interleukin-2-regulatory T cell axis critically regulates maintenance of hematopoietic stem cells
(2017)
The role of IL-2 in HSC maintenance is unknown. Here we show that Il2\(^{−/-}\) mice develop severe anomalies in HSC maintenance leading to defective hematopoiesis. Whereas, lack of IL-2 signaling was detrimental for lympho- and erythropoiesis, myelopoiesis was enhanced in Il2\(^{−/-}\) mice. Investigation of the underlying mechanisms of dysregulated hematopoiesis in Il2\(^{−/-}\) mice shows that the IL-2-T\(_{reg}\) cell axis is indispensable for HSC maintenance and normal hematopoiesis. Lack of T\(_{reg}\) activity resulted in increased IFN-γ production by activated T cells and an expansion of the HSCs in the bone marrow (BM). Though, restoring T\(_{reg}\) population successfully rescued HSC maintenance in Il2\(^{-/-}\) mice, preventing IFN-γ activity could do the same even in the absence of T\(_{reg}\) cells. Our study suggests that equilibrium in IL-2 and IFN-γ activity is critical for steady state hematopoiesis, and in clinical conditions of BM failure, IL-2 or anti-IFN-γ treatment might help to restore hematopoiesis.
Background
Invasive fungal infections with Candida albicans (C. albicans) occur frequently in extremely low birthweight (ELBW) infants and are associated with poor outcome. Phagocytosis of C.albicans initializes apoptosis in monocytes (phagocytosis induced cell death, PICD). PICD is reduced in neonatal cord blood monocytes (CBMO).
Hypothesis
Phagocytosis of C. albicans causes PICD which differs between neonatal monocytes (CBMO) and adult peripheral blood monocytes (PBMO) due to lower stimulation of TLR-mediated immune responses.
Methods
The ability to phagocytose C. albicans, expression of TLRs, the induction of apoptosis (assessment of sub-G1 and nick-strand breaks) were analyzed by FACS. TLR signalling was induced by agonists such as lipopolysaccharide (LPS), Pam3Cys, FSL-1 and Zymosan and blocked (neutralizing TLR2 antibodies and MYD88 inhibitor).
Results
Phagocytic indices of PBMO and CBMO were similar. Following stimulation with agonists and C. albicans induced up-regulation of TLR2 and consecutive phosphorylation of MAP kinase P38 and expression of TNF-α, which were stronger on PBMO compared to CBMO (p < 0.005). Downstream, TLR2 signalling initiated caspase-3-dependent PICD which was found reduced in CBMO (p < 0.05 vs PBMO).
Conclusion
Our data suggest direct involvement of TLR2-signalling in C. albicans-induced PICD in monocytes and an alteration of this pathway in CBMO.
Parent-of-origin imprints have been implicated in the regulation of neural differentiation and brain development. Previously we have shown that, despite the lack of a paternal genome, human parthenogenetic (PG) embryonic stem cells (hESCs) can form proliferating neural stem cells (NSCs) that are capable of differentiation into physiologically functional neurons while maintaining allele-specific expression of imprinted genes. Since biparental ("normal") hESC-derived NSCs (N NSCs) are targeted by immune cells, we characterized the immunogenicity of PG NSCs. Flow cytometry and immunocytochemistry revealed that both N NSCs and PG NSCs exhibited surface expression of human leukocyte antigen (HLA) class I but not HLA-DR molecules. Functional analyses using an in vitro mixed lymphocyte reaction assay resulted in less proliferation of peripheral blood mononuclear cells (PBMC) with PG compared with N NSCs. In addition, natural killer (NK) cells cytolyzed PG less than N NSCs. At a molecular level, expression analyses of immune regulatory factors revealed higher HLA-G levels in PG compared with N NSCs. In line with this finding, MIR152, which represses HLA-G expression, is less transcribed in PG compared with N cells. Blockage of HLA-G receptors ILT2 and KIR2DL4 on natural killer cell leukemia (NKL) cells increased cytolysis of PG NSCs. Together this indicates that PG NSCs have unique immunological properties due to elevated HLA-G expression.
Background
To use combinatorial epitope mapping ("fingerprinting") of the antibody response to identify targets of the humoral immune response in patients with transitional cell carcinoma (TCC) of the bladder.
Methods
A combinatorial random peptide library was screened on the circulating pool of immunoglobulins purified from an index patient with a high risk TCC (pTa high grade plus carcinoma in situ) to identify corresponding target antigens. A patient cohort was investigated for antibody titers against ubiquitin.
Results
We selected, isolated, and validated an immunogenic peptide motif from ubiquitin as a dominant epitope of the humoral response. Patients with TCC had significantly higher antibody titers against ubiquitin than healthy donors (p<0.007), prostate cancer patients (p<0.0007), and all patients without TCC taken together (p<0.0001). Titers from superficial tumors were not significantly different from muscle invasive tumors (p = 0.0929). For antibody response against ubiquitin, sensitivity for detection of TCC was 0.44, specificity 0.96, positive predictive value 0.96 and negative predictive value 0.41. No significant titer changes were observed during the standard BCG induction immunotherapy.
Conclusions
This is the first report to demonstrate an anti-ubiquitin antibody response in patients with TCC. Although sensitivity of antibody production was low, a high specificity and positive predictive value make ubiquitin an interesting candidate for further diagnostic and possibly immune modulating studies.