Cell migration is a process which is essential during embryonic development, throughout adult life and in some pathological conditions. Cadherins, and more specifically the neural cell adhesion molecule N-cadherin, play an important role in migration. In embryogenesis, N-cadherin is the key molecule during gastrulation and neural crest development. N-cadherin mediated contacts activate several pathways like Rho GTPases and function in tyrosine kinase signalling (for example via the fibroblast growth factor receptor). In cancer, cadherins control the balance between suppression and promotion of invasion. E-cadherin functions as an invasion suppressor and is downregulated in most carcinomas, while N-cadherin, as an invasion promoter, is frequently upregulated. Expression of N-cadherin in epithelial cells induces changes in morphology to a fibroblastic phenotype, rendering the cells more motile and invasive. However in some cancers, like osteosarcoma, N-cadherin may behave as a tumour suppressor. N-cadherin can have multiple functions: promoting adhesion or induction of migration dependent on the cellular context. KEY WORDS: N-cadherin, cancer, embryogenesis, invasion, signallingInt. J. Dev. Biol. 48: 463-476 (2004) Migration and invasionCell migration is a process that is essential during embryonic development and throughout further life. In the adult, cell migration is crucial for homeostatic processes, such as effective immune responses and repair of injured tissues. To migrate, the individual cell body must modify its shape to interact with the surrounding tissue structures. The extracellular matrix (ECM) forms a substrate, as well as a barrier for the advancing cell body. Cell migration through tissues results from a continuous cycle of interdependent steps. In general, there are five steps involved in cell migration in the ECM. First comes the protrusion of the leading edge, where growing actin filaments connect to adapter proteins and push the cell membrane in an outward direction. In a second step cell-matrix interactions and focal contacts are formed. After that, surface proteases such as matrix metalloproteinases (MMP) are recruited and focal proteolysis takes place. Then the cell contracts by actomyosin activation, and finally the tail of the cell is detached from its substrate (Friedl and Wolf, 2003).Border cells of the Drosophila melanogaster ovary are nowadays used as a model for migration. There are three recently discovered signalling pathways that control distinct aspects of migration: a global steroid-hormone signal defines the timing of migration, a highly localised cytokine signal that activates the Janus kinase-signal transducer and activator of transcription is both necessary and sufficient to induce migration, and finally, a growth factor that is analogous to platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) contributes to guiding the cells to their destination (Montell, 2003).In embryonic morphogenesis two types of collective cell movement can ...

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BackgroundRecent scientific developments have shed more light on the importance of the host-microbe interaction, particularly in the gut. However, the mechanistic study of the host-microbe interplay is complicated by the intrinsic limitations in reaching the different areas of the gastrointestinal tract (GIT) in vivo. In this paper, we present the technical validation of a new device - the Host-Microbiota Interaction (HMI) module - and the evidence that it can be used in combination with a gut dynamic simulator to evaluate the effect of a specific treatment at the level of the luminal microbial community and of the host surface colonization and signaling.ResultsThe HMI module recreates conditions that are physiologically relevant for the GIT: i) a mucosal area to which bacteria can adhere under relevant shear stress (3 dynes cm−2); ii) the bilateral transport of low molecular weight metabolites (4 to 150 kDa) with permeation coefficients ranging from 2.4 × 10−6 to 7.1 × 10−9 cm sec−1; and iii) microaerophilic conditions at the bottom of the growing biofilm (PmO2 = 2.5 × 10−4 cm sec−1). In a long-term study, the host’s cells in the HMI module were still viable after a 48-hour exposure to a complex microbial community. The dominant mucus-associated microbiota differed from the luminal one and its composition was influenced by the treatment with a dried product derived from yeast fermentation. The latter - with known anti-inflammatory properties - induced a decrease of pro-inflammatory IL-8 production between 24 and 48 h.ConclusionsThe study of the in vivo functionality of adhering bacterial communities in the human GIT and of the localized effect on the host is frequently hindered by the complexity of reaching particular areas of the GIT. The HMI module offers the possibility of co-culturing a gut representative microbial community with enterocyte-like cells up to 48 h and may therefore contribute to the mechanistic understanding of host-microbiome interactions.

Decreased phagocytosis of S. aureus and an M2 activation phenotype in CRSwNP could potentially contribute to persistence of chronic inflammation in CRSwNP.

In chronic rhinosinusitis (CRS) different phenotypes have been reported based on cytokine profile and inflammatory cell patterns. The aim of this study was to characterize the intracytoplasmatic cytokines ofTcells infiltrating theinflamed sinonasal mucosa.MethodsInfiltrated T cells and tissue homogenates from sinonasal mucosal samples of 7 healthy subjects, 9 patients with CRS without nasal polyp (CRSsNP), 15 with CRS with nasal polyps (CRSwNP) and 5cystic fibrosis patients (CF-NP) were analyzed for cytokine expression using flow cytometry and multiplex analysis respectively. Intracytoplasmic cytokinesin T cells were analyzed after stimulation of nasal polyps with Staphylococcus aureus enterotoxin B for 24 hours.ResultsThe number of T cellsper total living cells was significantly higher in patients with CRSwNP vs. CRSsNP and controls. 85% of the CD4+ Tcells showed to be memory T cells. The effector T cells present in all tissues have apredominantTh1 phenotype. Only in CRSwNP, a significantfraction of T cellsproduced the Th2 cytokinesIL-4 and IL-5, while nasal polyps from CF patients were characterized by a higher CD4/CD8 T cell ratio and an increased number of Th17 cells. 24 h stimulation with SEB resulted in a significant induction of CD4+ T cells producing IL-10 (Tr1 cells).ConclusionT cell cytokine patternsin healthy and inflamed sinonasal mucosa revealed that Th2 cells (IL-4 and IL-5 producing cells) are significantly increased in CRSwNP mucosal inflammation. Exposure to SEB stimulates Tr1 cellsthat may contribute to the Th2 bias in CRSwNP.