Cytokine | EPFL Graph Search

Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Due to their size, cytokines cannot cross the lipid bilayer of cells to enter the cytoplasm and therefore typically exert their functions by interacting with specific cytokine receptors on the target cell surface. Cytokines have been shown to be involved in autocrine, paracrine and endocrine signaling as immunomodulating agents. Cytokines include chemokines, interferons, interleukins, lymphokines, and tumour necrosis factors, but generally not hormones or growth factors (despite some overlap in the terminology). Cytokines are produced by a broad range of cells, including immune cells like macrophages, B lymphocytes, T lymphocytes and mast cells, as well as endothelial cells, fibroblasts, and various stromal cells; a given cytokine may be produced by more than one type of cell. They act through cell surface receptors and are especially important in the immune system; cytokines modulate

Modulation of Dendritic Cells Function by H. polygyrus Products

Blaise Dayer

Dendritic cells (DCs) are crucial antigen-presenting cells that can drastically change the development of an immune response by polarising T helper cells toward a Th1 or a Th2 phenotype. Heligmosomoides polygyrus, a murine model of human helminth, has been shown to strongly down-regulate its host immune response. At the DC level, its excretory/secretory products (HES) modulate the cytokine response and co-stimulatory marker expression to bacterial stimulation in favour of an antiinflammatory environment. A regulatory T cell-inducing TGF[beta]-like activity was also discovered in HES. In this work, we further characterised the immunomodulatory properties of HES and heat-inactivated HES both in vitro, using LPS-pulsed GM-CSF-grown bone marrowderived DCs, and in in vivo adoptive transfer of HES-, bacterial extract- or co-pulsed DCs. To determine if the TGF[beta], C-type lectin receptors (CLRs) or toll-like receptors (TLRs) were implicated in this immunomodulation, we treated DCs with blocking antibodies, chemical kinase inhibitors and grew DCs from knockout mice. These studies revealed that HES immunomodulation of DCs was independent of the TGF[beta] receptor, the two CLRs, Dectin-1 and 2, as well as any TLR. Spleen tyrosine kinase (Syk), which is crucial for the signalling of many CLRs, and phosphoinositide 3- kinase seemed not to be needed as well. In an attempt to reduce the number of potential immunomodulators in HES, HES size fractions were tested for their ability to reduce LPS-induced inflammatory cytokine production of DCs. The activity was limited to few fractions, fraction 14 being the most potent. Finally, physical interactions between DCs and biotinylated HES were measured by flow cytometry and revealed that CD24, a molecule required for HES interactions with B cells, was implicated, but not crucial. HES binding to CD24-/- DCs was reduced, but the LPS-induced cytokines and co-stimulatory markers levels were still down-regulated upon HES co-treatment.

2011

A Novel 3D hydrogel based microfluidic cell culture platform

Keshav Krishnamani

Breakthroughs in health care over the coming decades may well consist of cell based therapeutics, potentially allowing the repair and replacement of damaged tissues and organs. Recently developed induced pluripotency methods as well as advances in stem cell biology show hope of such a reality. But such prospects come with the need to have a robust understanding and control over cell development and differentiation processes. Cells in the body develop in tightly controlled and specialized micro-environments that provide many complex cues and interactions that guide cell fate by directing gene expression. But current cell culture techniques that are most widely used to study the cell outside the body have not significantly changed from when first started over a century ago, using simple containers and flasks with plastic surfaces. Many studies have shown that three-dimensions (3D) over conventional 2D cell culture alone, showed to have increased levels of cell organization, morphology and function. By combining novel biomaterials and microfabrication methods, this project aims to create a tool that allows the study of cells within a simplified 3D environment. With the potential to build up the physical and soluble complexity of this environment in a tailor made fashion, a "dissection" of the functions and influences of external factors may be understood. Such a tool can also be used for the development of cell based models, highly relevant for drug discovery application as well as potentially for the development of cell based therapeutics. We have developed a novel microfluidic 3D cell culture platform that allows controlled soluble factor perfusion in an enzymatically formed and cell responsive PEG-based hydrogel. Soft lithographic processes were used to mold microchannels on a layer of hydrogel. In a second step, a flat hydrogel layer is placed on top to enclose and form the microchannels . The system allows the control over soluble factor delivery and it is able to perform long-term cell culture and generate user controlled gradients of soluble factors. With continuous perfusion, metabolic waste is constantly removed and cells are supplied with fresh medium. The platform also can allow creation of tailor made environments building up complexity in a controlled fashion. Higher throughput is also achieved by arraying individual culture chambers. The device was applied towards the culture of mouse embryonic stem cells (mESC) in order to demonstrate their self-renewal capacity on the microfluidic platform. The effects of some cytokine factors were also studied. Meaningful readouts such as fluorescence are easily used for analysis and cells can possibly be extracted from the device for further downstream analysis and processing. Through this device we show that microfluidics technologies combined with biomaterials enables the creation of platforms that are biologically relevant for the study and understanding of cell processes from cancer to stem cell development, processes which are fundamentally regulated by interactions with the microenvironment. The platform developed may also be used to develop human tissue models perhaps more relevant than current animal based testing, providing new tools for drug development and also potentially new approaches for developing cell based therapeutics

2009

Epithelial-mesenchymal plasticity determines estrogen receptor positive breast cancer dormancy and epithelial reconversion drives recurrence

Giovanna Ambrosini, Patrik Aouad, Cathrin Brisken, Fabio De Martino, Kelly Spry Maggs, Hazel Margaret Quinn, Georgios Sflomos, Céline Marie Victoria Stibolt, Yueyun Zhang

More than 70% of human breast cancers (BCs) are estrogen receptor α-positive (ER+). A clinical challenge of ER+ BC is that they can recur decades after initial treatments. Mechanisms governing latent disease remain elusive due to lack of adequate in vivo models. We compare intraductal xenografts of ER+ and triple-negative (TN) BC cells and demonstrate that disseminated TNBC cells proliferate similarly as TNBC cells at the primary site whereas disseminated ER+ BC cells proliferate slower, they decrease CDH1 and increase ZEB1,2 expressions, and exhibit characteristics of epithelial-mesenchymal plasticity (EMP) and dormancy. Forced E-cadherin expression overcomes ER+ BC dormancy. Cytokine signalings are enriched in more active versus inactive disseminated tumour cells, suggesting microenvironmental triggers for awakening. We conclude that intraductal xenografts model ER + BC dormancy and reveal that EMP is essential for the generation of a dormant cell state and that targeting exit from EMP has therapeutic potential.

2022