Vorkommen und funktionelle Bedeutung des Chemokinrezeptors CXCR7 in humanen astroglialen Tumoren

Das Chemokin CXCL12 und sein Rezeptor CXCR4 spielen eine wesentliche Rolle bei der Invasion, Proliferation und Metastasierung von Tumoren. Kürzlich wurde CXCR7 als neuer, alternativer Rezeptor für CXCL12 und mit geringerer Affinität für CXCL11 identifiziert. Im Rahmen dieser Arbeit wurde das Vorkommen dieser beiden Rezeptoren und ihrer Liganden in humanen Astrozytomen und Glioblastomen und insbesondere die funktionelle Bedeutung von CXCR7 untersucht. In situ wurde CXCR7 auf tumor-assoziierten Endothel- und Mikrogliazellen und vor allem auf einem Großteil der Glioblastomzellen exprimiert. Die Expression von CXCR4 hingegen ist neben Endothel- und Mikrogliazellen auf eine kleine Subpopulation von Glioblastomzellen mit Stammzellcharakter beschränkt. CXCL12 ist häufig kolokalisiert mit CXCR7 oder CXCR4, was darauf hindeutet, dass der Ligand an seine Rezeptoren gebunden vorliegt. In Homogenaten von soliden Astrozytomen wurde ein Anstieg der CXCR7-Transkription mit steigender Malignität festgestellt. In vitro wurde CXCR7 in allen untersuchten Glioblastomzelllinien auf hohem Niveau exprimiert, während CXCR4 nur in einer von acht Glioblastomzelllinien in geringem Maß detektiert wurde. Eine Glioblastomzelllinie mit Stammzellcharakter, die unter speziellen Stammzellkultivierungsbedingungen generiert worden war, hingegen exprimierte vor allem CXCR4. Bei seruminduzierter Differenzierung wurde die CXCR4-Expression geringer, während die Expression von CXCR7 drastisch zunahm. In einer konventionellen Glioblastomzelllinie wurde die Expression von CXCR7 weder durch Zytokine und Wachstumsfaktoren noch durch Hypoxie reguliert, wohingegen eine Modulation der CXCR4-Expression unter diesen Bedingungen bekannt ist. Durch Stimulation von CXCR7-positiven, CXCR4-negativen Glioblastomzellen mit CXCL12 wurde eine transiente Phosphorylierung der Kinasen ERK 1 / 2 (extracellular signal-related kinases) hervorgerufen, die andeutet, dass dieser Rezeptor funktionell aktiv ist. Eine Aktivierung der Transkriptionsfaktoren ELK-1, ATF2, CREB oder NF-κB wurde jedoch nicht beobachtet. Während die Proliferation und Migration von Glioblastomzellen nicht beeinflusst wurden, schützte die Stimulation mit CXCL12 diese Zellen vor einer Camptothecin-induzierten Apoptose. Daher ist auf differenzierten Glioblastomzellen CXCR7, nicht jedoch CXCR4, der vorherrschende Rezeptor für CXCL12 und vermittelt Apoptoseresistenz

Near-infrared molecular imaging of tumors via chemokine receptors CXCR4 and CXCR7

The chemokine CXCL12/SDF-1 and its receptors CXCR4 and CXCR7 play a major role in tumor invasion, proliferation and metastasis. Since both receptors are overexpressed on distinct tumor cells and on the tumor vasculature, we evaluated their potential as targets for detection of cancers by molecular imaging. We synthesized conjugates of CXCL12 and the near-infrared (NIR) fluorescent dye IRDye®800CW, tested their selectivity, sensitivity and biological activity in vitro and their feasibility to visualize tumors in vivo. Purified CXCL12-conjugates detected in vitro as low as 500 A764 human glioma cells or MCF-7 breast cancer cells that express CXCR7 alone or together with CXCR4. Binding was time- and concentration-dependent, and the label could be competitively displaced by the native peptide. Control conjugates with bovine serum albumin or lactalbumin failed to label the cells. In mice, the conjugate distributed rapidly. After 1–92 h, subcutaneous tumors of human MCF-7 and A764 cells in immunodeficient mice were detected with high sensitivity. Background was observed in particular in liver within the first 24 h, but also skull and hind limbs yielded some background. Overall, fluorescent CXCL12-conjugates are sensitive and selective probes to detect solid and metastatic tumors by targeting tumor cells and tumor vasculature

Дизайн-проект ортопедического стула-опоры для детей с ограниченными возможностями

Разработка дизайна ортопедического стула-опоры для реабилитации и обучению правильному сидению детей с нарушением функции мышц шеи, спины, нижних конечностей. Объектом исследования является ортопедический стул-опора. Целью работы является дизайн-проектирование ортопедического стула-опоры для детей с ограниченными возможностями. В результате исследования был разработан дизайн ортопедического стула-опоры. Созданы 3D модель и макет объекта.Development of the design of an orthopedic chair-support for rehabilitation and training in proper seating of children with impaired function of the muscles of the neck, back, lower limbs. The object of the study is an orthopedic chair-support. The aim of the work is to design an orthopedic chair-support for children with disabilities. As a result of the study, the design of an orthopedic chair-support was developed. 3D model and the layout of the object were created

Assessing the impacts of 1.5 °C global warming – simulation protocol of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b)

In Paris, France, December 2015, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to provide a "special report in 2018 on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways". In Nairobi, Kenya, April 2016, the IPCC panel accepted the invitation. Here we describe the response devised within the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) to provide tailored, cross-sectorally consistent impact projections to broaden the scientific basis for the report. The simulation protocol is designed to allow for (1) separation of the impacts of historical warming starting from pre-industrial conditions from impacts of other drivers such as historical land-use changes (based on pre-industrial and historical impact model simulations); (2) quantification of the impacts of additional warming up to 1.5°C, including a potential overshoot and long-term impacts up to 2299, and comparison to higher levels of global mean temperature change (based on the low-emissions Representative Concentration Pathway RCP2.6 and a no-mitigation pathway RCP6.0) with socio-economic conditions fixed at 2005 levels; and (3) assessment of the climate effects based on the same climate scenarios while accounting for simultaneous changes in socio-economic conditions following the middle-of-the-road Shared Socioeconomic Pathway (SSP2, Fricko et al., 2016) and in particular differential bioenergy requirements associated with the transformation of the energy system to comply with RCP2.6 compared to RCP6.0. With the aim of providing the scientific basis for an aggregation of impacts across sectors and analysis of cross-sectoral interactions that may dampen or amplify sectoral impacts, the protocol is designed to facilitate consistent impact projections from a range of impact models across different sectors (global and regional hydrology, lakes, global crops, global vegetation, regional forests, global and regional marine ecosystems and fisheries, global and regional coastal infrastructure, energy supply and demand, temperature-related mortality, and global terrestrial biodiversity)

Assessing the impacts of 1.5°C global warming -- simulation protocol of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2b)

In Paris, France, December 2015, the Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) invited the Intergovernmental Panel on Climate Change (IPCC) to provide a special report in 2018 on the impacts of global warming of 1.5 °C above pre-industrial levels and related global greenhouse gas emission pathways. In Nairobi, Kenya, April 2016, the IPCC panel accepted the invitation. Here we describe the response devised within the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) to provide tailored, cross-sectorally consistent impact projections to broaden the scientific basis for the report. The simulation protocol is designed to allow for (1) separation of the impacts of historical warming starting from pre-industrial conditions from impacts of other drivers such as historical land-use changes (based on pre-industrial and historical impact model simulations); (2) quantification of the impacts of additional warming up to 1.5 °C, including a potential overshoot and long-term impacts up to 2299, and comparison to higher levels of global mean temperature change (based on the low-emissions Representative Concentration Pathway RCP2.6 and a no-mitigation pathway RCP6.0) with socio-economic conditions fixed at 2005 levels; and (3) assessment of the climate effects based on the same climate scenarios while accounting for simultaneous changes in socio-economic conditions following the middle-of-the-road Shared Socioeconomic Pathway (SSP2, Fricko et al., 2016) and in particular differential bioenergy requirements associated with the transformation of the energy system to comply with RCP2.6 compared to RCP6.0. With the aim of providing the scientific basis for an aggregation of impacts across sectors and analysis of cross-sectoral interactions that may dampen or amplify sectoral impacts, the protocol is designed to facilitate consistent impact projections from a range of impact models across different sectors (global and regional hydrology, lakes, global crops, global vegetation, regional forests, global and regional marine ecosystems and fisheries, global and regional coastal infrastructure, energy supply and demand, temperature-related mortality, and global terrestrial biodiversity)

Resveratrol Alleviates the Early Challenges of Implant-Based Drug Delivery in a Human Glial Cell Model

Brain diseases are oftentimes life-threatening and difficult to treat. The local administration of drug substances using brain implants can increase on-site concentrations and decrease systemic side effects. However, the biocompatibility of potential brain implant materials needs to be evaluated carefully as implants can trigger foreign body reactions, particularly by increasing the microglia and astrocyte reactivity. To date, these tests have been frequently conducted in very simple in vitro models, in particular not respecting the key players in glial cell reactions and the challenges of surgical implantation characterized by the disruption of oxygen and nutrient supply. Thus, we established an in vitro model in which we treated human glial cell lines with reduced oxygen and glucose levels. The model displayed cytokine and reactive oxygen species release from reactive microglia and an increase in a marker of reactive astrocytes, galectin-3. Moreover, the treatment caused changes in the cell survival and triggered the production of hypoxia-inducible factor 1α. In this comprehensive platform, we demonstrated the protective effect of the natural polyphenol resveratrol as a model substance, which might be included in brain implants to ease the undesired glial cell response. Overall, a glial-cell-based in vitro model of the initial challenges of local brain disease treatment may prove useful for investigating new therapy options

Breaking the circulus vitiosus of neuroinflammation: Resveratrol attenuates the human glial cell response to cytokines

Neuroinflammation is both cause and effect of many neurodegenerative disorders. Activation of astrocytes and microglia leads to the release of cytokines and reactive oxygen species followed by blood-brain barrier leakage and neurotoxicity. Transient neuroinflammation is considered to be largely protective, however, chronic neuroinflammation contributes to the pathology of Alzheimer’s disease, multiple sclerosis, traumatic brain injury, and many more. In this study, we focus on the aspect of cytokine-induced neuroinflammation in human microglia and astrocytes. Here we show by mRNA and protein analysis that cytokines, released not only by microglia but also by astrocytes, lead to a circuit of proinflammatory activation. Moreover, we present how the natural compound resveratrol can stop the circuit of proinflammatory activation and facilitate return to resting conditions. These results will contribute to distinguishing between the causes and the effects of neuroinflammation, a better understanding of underlying mechanisms, and potential treatment options

The Chemokine Receptor CXCR6 Evokes Reverse Signaling via the Transmembrane Chemokine CXCL16

Reverse signaling is a signaling mechanism where transmembrane or membrane-bound ligands transduce signals and exert biological effects upon binding of their specific receptors, enabling a bidirectional signaling between ligand and receptor-expressing cells. In this study, we address the question of whether the transmembrane chemokine (C-X-C motif) ligand 16, CXCL16 is able to transduce reverse signaling and investigate the biological consequences. For this, we used human glioblastoma cell lines and a melanoma cell line as in vitro models to show that stimulation with recombinant C-X-C chemokine receptor 6 (CXCR6) or CXCR6-containing membrane preparations induces intracellular (reverse) signaling. Specificity was verified by RNAi experiments and by transfection with expression vectors for the intact CXCL16 and an intracellularly-truncated form of CXCL16. We showed that reverse signaling via CXCL16 promotes migration in CXCL16-expressing melanoma and glioblastoma cells, but does not affect proliferation or protection from chemically-induced apoptosis. Additionally, fast migrating cells isolated from freshly surgically-resected gliomas show a differential expression pattern for CXCL16 in comparison to slowly-migrating cells, enabling a possible functional role of the reverse signaling of the CXCL16/CXCR6 pair in human brain tumor progression in vivo

Expression of the chemokines CXCL12 and CX3CL1 and their receptors in human nerve sheath tumors

Peripheral nerve sheath tumors are in most cases slowly growing neoplasms that can be adequately cured by surgical resection. However, facing the risk of a neurosurgical intervention and the trend of multiple relapses of nerve sheath tumors the development of additional therapy strategies seems to be favourable, and therefore substantiated knowledge of molecular and cellular mechanisms in nerve sheath tumors should be achieved. Here, we firstly describe the expression of the chemokines CXCL12 (SDF-1) and CX3CL1 (fractal-kine) and their respective receptors CXCR4, CXCR7 and CX3CR1 in different entities of human nerve sheath tumors and normal control tissues. Both ligands and their receptors are expressed in high to moderate levels on mRNA and protein level in benign and malignant nerve sheath tumors. While CXCL12 was mainly found in schwannoma cells (S100+) in situ, its receptor CXCR4 is also partly found on CD11b-positive macrophages / microglia and its alternative receptor CXCR7 is also expressed by endothelial cells and macrophages. CX3CL1 is expressed by parts of the schwannoma and endothelial cells, whereas its receptor CX3CR1 is expressed by nearly all tumor cells and macrophages, but not by endothelial cells. Taken together, we could show the presence of CXCL12 and CX3CL1 and their respective receptors in benign and malignant human nerve sheath tumors. Further investigations may show their functional role in health and disease