563 research outputs found
Multiplex immunohistochemistry for mapping the tumor microenvironment of head and neck squamous cell carcinoma
No full textThe role of LYVE-1+ macrophages in the development of squamous cell carcinoma of the head and neck
No full textManagement of chronic immune thrombocytopenic purpura: targeting insufficient megakaryopoiesis as a novel therapeutic principle
No full textAndreas Rank, Oliver Weigert, Helmut OstermannMedizinische Klinik III – Grosshadern, Klinikum der Ludwig Maximilians-Universitaet Munich, Munich, GermanyAbstract: Traditionally, anti-platelet autoantibodies accelerating platelet clearance from the peripheral circulation have been recognized as the primary pathopysiological mechanism in chronic immune thrombocytopenia (ITP). Recently, increasing evidence supports the co-existence of insufficient megakaryopoiesis. Inadequate low thrombopoietin (TPO) levels are associated with insufficient proliferation and differentiation of megakaryocytes, decreased proplatelet formation, and subsequent platelet release. Recently two novel activators of TPO receptors have been made available: romiplostim and eltrombopag. In several phase III studies, both agents demonstrated increase of platelet counts in about 80% of chronic ITP patients within 2 to 3 weeks. These agents substantially broaden the therapeutic options for patients with chronic ITP although long-term results are still pending. This review will provide an update on the current conception of underlying mechanisms in ITP and novel, pathophysiologically based treatment options.Keywords: immune thrombocytopenia, romiplostim, eltrombopag, megakaryopoiesi
Extension of the color glass condensate approach to diffractive reactions
No full textWe present an evolution equation for the Bjorken x dependence of diffractive dissociation on hadrons and nuclei at high energies. We extend the formulation of Kovchegov and Levin by relaxing the factorization assumption used there. The formulation is based on a technique used by Weigert to describe interjet energy flow. The method can be naturally extended to other exclusive observables
Generierung von Sphingosin-1-Phosphat durch apoptotische Zellen und dessen Einfluss auf die Polarisierung von Makrophagen während der Tumorentwicklung
No full textThe removal of apoptotic cells (AC) can be regarded as an integral component of the program to terminate inflammation. Clearance of AC by professional phagocytes such as macrophages induces an anti-inflammatory phenotype in the latter ones. Anti-inflammatory or M2 polarization is also observed in macrophages infiltrating certain human tumors. These tumor-associated macrophages (TAM) contribute actively to tumor progression by promoting immune evasion, angiogenesis and tumor cell survival. The aim of my Ph.D. thesis was to approach the mechanisms as well as the characteristics of macrophage phenotype alterations induced by AC, and to elucidate a possible connection between tumor cell apoptosis and TAM generation. In the first part of my studies, I investigated the impact of AC on macrophage viability. I could show that macrophage survival against pro-apoptotic agents increased after the interaction with AC. Protection of macrophages against cell death required activation of phosphatidylinositol-3 kinase (PI3K), extracellular signal-regulated kinase 1/2 (ERK1/2) and Ca2+ signaling, and correlated with Bcl-XL and Bcl-2 up-regulation as well as Ser136-Bad phosphorylation. Unexpectedly, neither phagocytosis nor binding of apoptotic debris to the phagocyte was necessary to induce protection. AC released the bioactive lipid sphingosine-1-phosphate (S1P), dependent on sphingosine kinase (SphK) 2, as a survival messenger. These data indicated an active role of AC in preventing cell destruction in their neighborhood. My next aim was to elucidate the mechanism of S1P production by AC. During cell death, SphK 2 was cleaved at its N-terminus by caspase-1. Thereupon, the truncated but enzymatically active fragment of SphK 2 was released from cells. This release was coupled to phosphatidylserine exposure, a hallmark of apoptosis and a crucial signal for the phagocyte/apoptotic cell interaction. Thus, I observed a link between common signaling events during apoptosis and the extracellular production of S1P, which is known to affect immune cell attraction and polarization as well as angiogenesis in cancer. In the next part of my studies, I asked for a correlation between tumor cell apoptosis and TAM polarization. During co-culture of human macrophages with human breast cancer carcinoma cells (MCF-7), the latter ones were killed, while macrophages acquired an alternatively activated phenotype. This was characterized by decreased tumor necrosis factor (TNF)-α; and interleukin (IL)-12-p70 production, but increased formation of IL-8 and IL-10. Alternative macrophage activation required tumor cell death, because a co-culture with apoptosis-resistant colon carcinoma cells (RKO) or Bcl-2-overexpressing MCF-7 cells failed to induce phenotype alterations. These phenotype alterations were also achieved with conditioned media from apoptotic tumor cells, which again argued for a soluble factor being involved. Knock-down of SphK2, but not SphK1, to attenuate S1P formation in MCF-7 cells, repressed the otherwise observed alternative macrophage polarization during co-culture. Furthermore, macrophage polarization achieved by tumor cell apoptosis or substitution of authentic S1P was characterized by suppression of pro-inflammatory nuclear factor (NF)-κB DNA binding. These findings suggested that tumor cell apoptosis-derived S1P contributes to the macrophage polarization present in human tumors. To validate these in vitro data, I used an in vivo tumor model to clarify the relevance of SphK2 and S1P in tumor development. The growth of, as well as blood vessel infiltration into SphK2 knock-down MCF-7 (MCF-7-siSphK2) xenografts in nude mice was markedly decreased in comparison to control MCF-7 xenografts. In contrast, macrophage infiltration was similar or even more pronounced. These data provided a first hint for an in vivo role of SphK2-derived S1P in macrophage polarization associated with tumor promotion. In summary, these data indicate a new mechanism how AC themselves shape macrophage polarization, which results in the termination of inflammatory responses and macrophage survival. Furthermore, my studies present evidence that human tumors may utilize this mechanism to foster growth via increased angiogenesis.Die Phagozytose apoptotischer Zellen (AZ) kann als ein integraler Bestandteil des Mechanismus zur Beendigung von Entzündungsreaktionen angesehen werden. Die Beseitigung von AZ induziert einen anti-inflammatorischen Phänotyp in Makrophagen. Ein ähnlicher Phänotyp (M2) ist auch für Makrophagen beschrieben, die in humane Tumore infiltrieren. Diese Tumor- assoziierten Makrophagen (TAM) tragen aktiv zur Tumorprogression bei, indem sie die Gefäßbildung und das Überleben von Tumorzellen fördern, aber auch das körpereigene Immunsystem ausschalten. Das Ziel meiner Doktorarbeit war es, die Mechanismen und Charakteristika der Makrophagenpolarisierung durch AZ besser zu verstehen, und eine mögliche Verbindung von Tumorzell-Apoptose und der Ausprägung des TAM-Phänotyps aufzuzeigen. Im ersten Teil meiner Studien untersuchte ich den Einfluss von AZ auf die Überlebensfähigkeit von Makrophagen. Diese war nach der Interaktion mit AZ erhöht. Der Schutz vor Zelltod benötigte die Aktivierung der Phosphatidylinositol-3 Kinase (PI3K), der Mitogen-aktivierten Proteinkinasen ERK1/2, sowie Calcium-Signale, und korrelierte mit vermehrter Expression von Bcl-2 und Bcl-XL, sowie mit Phosphorylierung von Bad an Ser136. Interessanterweise war der Schutzeffekt unabhängig von Phagozytose oder direkter Interaktion zwischen Makrophagen und AZ, sondern vielmehr von der Freisetzung des bioaktiven Lipids Sphingosin-1-Phosphat (S1P) aus AZ, generiert durch die Sphingosinkinase (SphK) 2. Mein nächstes Ziel war es den dafür verantwortlichen Mechanismus aufzuzeigen. Während des Zelltods fand eine Spaltung der SphK2 durch die Caspase-1 an deren N-Terminus statt, woraufhin ein enzymatisch aktives Fragment aus den AZ freigesetzt wurde. Diese Freisetzung war eng an die Exposition von Phosphatidylserin gekoppelt, welche ein Kennzeichen von Apoptose, und ein wichtiges Signal bei der Interaktion von Makrophagen und AZ ist. Somit konnte ich eine Verknüpfung zwischen allgemeinen Signalwegen der Apoptose und der extrazellulären Produktion von S1P nachweisen. Von letzterem ist bekannt, dass es sowohl die Polarisierung und das Anlocken von Immunzellen, als auch die Gefäßbildung im Tumor beeinflussen kann. Im nachfolgenden Teil meiner Studien untersuchte ich eine mögliche Verbindung zwischen Tumorzell-Apoptose und der TAM- Polarisierung. In einer Ko-Kultur von menschlichen Makrophagen mit MCF-7 Brustkrebszellen wurden letztere getötet, woraufhin die Makrophagen einen alternativ aktivierten Phänotyp annahmen. Dieser war durch verminderte Produktion des Tumor-Nekrose-Faktors (TNF)-α; und des Interleukins (IL)-12p70 sowie durch erhöhte Freisetzung der Interleukine 8 und 10 charakterisiert. Die alternative Aktivierung der Makrophagen in den Ko-Kulturen war Tumorzelltod-abhängig, da Apoptose-resistente Darmkrebszellen (RKO) oder Bcl-2 überexprimierende MCF-7 Zellen diese nicht auslösten. Dies war jedoch mit Zellkulturüberständen von apoptotischen Tumorzellen der Fall, was wiederum auf einen löslichen Faktor hindeutete. Das Ausschalten der SphK2, nicht jedoch der SphK1, was die S1P- Freisetzung von MCF-7 Zellen unterband, verhinderte die alternative Aktivierung von Makrophagen in den Ko-Kulturen. Ein weiteres Charakteristikum der Makrophagenpolarisierung durch apoptotische Tumorzellen und S1P war die Hemmung der DNA-Bindung des entzündungsfördernden Transkriptionsfaktors NF-κB. Um die Relevanz der SphK2 und von S1P in der Tumorentwicklung genauer zu untersuchen, führte ich ein in vivo Tumormodell durch. Tumorzell-Implantate von SphK2-defizienten MCF-7 Zellen in Nacktmäusen wiesen sowohl deutlich reduziertes Wachstum, als auch Blutgefäßbildung, im Vergleich zu Kontrollimplantaten (MCF-7) auf. Die Einwanderung von Makrophagen war jedoch nicht vermindert, sondern eher erhöht. Diese Daten lieferten einen ersten Hinweis auf eine Rolle von SphK2-abhängig freigesetztem S1P in der Makrophagenpolarisierung, in Verbindung mit einer Förderung der Tumorentwicklung. Zusammengefasst deuten meine Daten auf einen neuen Mechanismus hin, wie AZ die Makrophagenpolarisierung gestalten. Dieser Prozess resultiert letztlich in der Beendigung von Entzündungsreaktionen und erhöhter Überlebensfähigkeit von Makrophagen. Weiterhin weisen meine Studien darauf hin, dass Tumore eventuell diesen Mechanismus nutzen, um ihr Wachstum durch vermehrte Gefäßbildung zu sichern
Cell Intrinsic IL-38 Affects B Cell Differentiation and Antibody Production
No full textIL-38 is an IL-1 family receptor antagonist with an emerging role in chronic inflammatory diseases. IL-38 expression has been mainly observed not only in epithelia, but also in cells of the immune system, including macrophages and B cells. Given the association of both IL-38 and B cells with chronic inflammation, we explored if IL-38 affects B cell biology. IL-38-deficient mice showed higher amounts of plasma cells (PC) in lymphoid organs but, conversely, lower levels of plasmatic antibody titers. Exploring underlying mechanisms in human B cells revealed that exogenously added IL-38 did not significantly affect early B cell activation or differentiation into plasma cells, even though IL-38 suppressed upregulation of CD38. Instead, IL-38 mRNA expression was transiently upregulated during the differentiation of human B cells to plasma cells in vitro, and knocking down IL-38 during early B cell differentiation increased plasma cell generation, while reducing antibody production, thus reproducing the murine phenotype. Although this endogenous role of IL-38 in B cell differentiation and antibody production did not align with an immunosuppressive function, autoantibody production induced in mice by repeated IL-18 injections was enhanced in an IL-38-deficient background. Taken together, our data suggest that cell-intrinsic IL-38 promotes antibody production at baseline but suppresses the production of autoantibodies in an inflammatory context, which may partially explain its protective role during chronic inflammation
Educational and Wage Risk: Social Insurance vs. Quality of Education
No full textIn this model of education, where individuals are exposed both to educational risk and to wage risk within the skilled sector, successful graduation depends both on individual effort to study and on public resources. We show that insuring the present risks is a dichotomic task: Wage risk is diversified ex post among the skilled by graduate taxation and skill-specific tuition fees. Educational risk of failure and inequality between skilled and unskilled workers are mitigated ex ante by enhancing the quality of education. The necessary expenditures are optimally financed by regressive tuition fees and the net revenue from the graduate tax.human capital investment, educational risk, wage risk, learning effort, graduate taxation, regressive tuition fees
MES SV40 Cells Are Sensitive to Lipopolysaccharide, Peptidoglycan, and Poly I:C Expressing IL-36 Cytokines
No full textMesangial cells (MC) maintain the architecture and cellular communication and indirectly join in the glomerular filtration rate for the correct functioning of the glomerulus. Consequently, these cells are activated constantly in response to changes in the intraglomerular environment due to a metabolic imbalance or infection. IL-36, a member of the IL-1 family, is a cytokine that initiates and maintains inflammation in different tissues in acute and chronic pathologies, including the skin, lungs, and intestines. In the kidney, IL-36 has been described in the development of tubulointerstitial lesions, the production of an inflammatory environment, and is associated with metabolic and mesangioproliferative disorders. The participation of IL-36 in functional dysregulation and the consequent generation of the inflammatory environment by MCs in the presence of microbial stimulation is not yet elucidated. In this work, the MES SV40 cell cultures were stimulated with classical pathogen-associated molecular patterns (PAMPs), mimicking an infection by negative and positive bacteria as well as a viral infection. Lipopolysaccharide (LPS), peptidoglycan (PGN) microbial wall components, and a viral mimic poly I:C were used, and the mRNA and protein expression of the IL-36 members were assessed. We observed a differential and dose-dependent IL-36 mRNA and protein expression under LPS, PGN, and poly I:C stimulation. IL-36β was only found when the cells were treated with LPS, while IL-36α and IL-36γ were favored by PGN and poly I:C stimulation. We suggest that the microbial components participate in the activation of MCs, leading them to the production of IL-36, in which a specific member may participate in the origin and maintenance of inflammation in the glomerular environment that is associated with infections
Association between spatial distribution of leukocyte subsets and clinical presentation of head and neck squamous cell carcinoma
No full textBackgroundInteractions between tumor cells and cells in the microenvironment contribute to tumor development and metastasis. The spatial arrangement of individual cells in relation to each other influences the likelihood of whether and how these cells interact with each other.MethodsThis study investigated the effect of spatial distribution on the function of leukocyte subsets in the microenvironment of human head and neck squamous cell carcinoma (HNSCC) using multiplex immunohistochemistry (IHC). Leukocyte subsets were further classified based on analysis of two previously published HNSCC single-cell RNA datasets and flow cytometry (FC).ResultsIHC revealed distinct distribution patterns of leukocytes differentiated by CD68 and CD163. While CD68hiCD163lo and CD68hiCD163hi cells accumulated near tumor sites, CD68loCD163hi cells were more evenly distributed in the tumor stroma. PD-L1hi and PD-1hi cells accumulated predominantly around tumor sites. High cell density of PD-L1hi CD68hiCD163hi cells or PD-1hi T cells near the tumor site correlated with improved survival. FC and single cell RNA revealed high variability within the CD68/CD163 subsets. CD68hiCD163lo and CD68hiCD163hi cells were predominantly macrophages (MΦ), whereas CD68loCD163hi cells appeared to be predominantly dendritic cells (DCs). Differentiation based on CD64, CD80, CD163, and CD206 revealed that TAM in HNSCC occupy a broad spectrum within the classical M1/M2 polarization. Notably, the MΦ subsets expressed predominantly CD206 and little CD80. The opposite was observed in the DC subsets.ConclusionThe distribution patterns and their distinct interactions via the PD-L1/PD-1 pathway suggest divergent roles of CD68/CD163 subsets in the HNSCC microenvironment. PD-L1/PD-1 interactions appear to occur primarily between specific cell types close to the tumor site. Whether PD-L1/PD-1 interactions have a positive or negative impact on patient survival appears to depend on both the spatial localization and the entity of the interacting cells. Co-expression of other markers, particularly CD80 and CD206, supports the hypothesis that CD68/CD163 IHC subsets have distinct functions. These results highlight the association between spatial leukocyte distribution patterns and the clinical presentation of HNSCC
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