262 research outputs found

    Chemoattractant Signaling between Tumor Cells and Macrophages Regulates Cancer Cell Migration, Metastasis and Neovascularization

    Get PDF
    Tumor-associated macrophages are known to influence cancer progression by modulation of immune function, angiogenesis, and cell metastasis, however, little is known about the chemokine signaling networks that regulate this process. Utilizing CT26 colon cancer cells and RAW 264.7 macrophages as a model cellular system, we demonstrate that treatment of CT26 cells with RAW 264.7 conditioned medium induces cell migration, invasion and metastasis. Inflammatory gene microarray analysis indicated CT26-stimulated RAW 264.7 macrophages upregulate SDF-1α and VEGF, and that these cytokines contribute to CT26 migration in vitro. RAW 264.7 macrophages also showed a robust chemotactic response towards CT26-derived chemokines. In particular, microarray analysis and functional testing revealed CSF-1 as the major chemoattractant for RAW 264.7 macrophages. Interestingly, in the chick CAM model of cancer progression, RAW 264.7 macrophages localized specifically to the tumor periphery where they were found to increase CT26 tumor growth, microvascular density, vascular disruption, and lung metastasis, suggesting these cells home to actively invading areas of the tumor, but not the hypoxic core of the tumor mass. In support of these findings, hypoxic conditions down regulated CSF-1 production in several tumor cell lines and decreased RAW 264.7 macrophage migration in vitro. Together our findings suggest a model where normoxic tumor cells release CSF-1 to recruit macrophages to the tumor periphery where they secrete motility and angiogenic factors that facilitate tumor cell invasion and metastasis

    Eosinophil Development, Regulation of Eosinophil-Specific Genes, and Role of Eosinophils in the Pathogenesis of Asthma

    Get PDF
    Eosinophils arise from hematopoietic CD34+ stem cells in the bone marrow. They acquire IL-5Rα on their surface at a very early stage during eosinophilopoiesis, and differentiate under the strong influence of interleukin (IL)-5. They then exit to the bloodstream, and enter the lung upon exposure to airway inflammatory signals, including eotaxins. In inflamed tissues, eosinophils act as key mediators of terminal effector functions and innate immunity and in linking to adaptive immune responses. Transcription factors GATA-1, CCAAT/enhancer-binding protein, and PU.1 play instructive roles in eosinophil specification from multipotent stem cells through a network of cooperative and antagonistic interactions. Not surprisingly, the interplay of these transcription factors is instrumental in forming the regulatory circuit of expression of eosinophil-specific genes, encoding eosinophil major basic protein and neurotoxin, CC chemokine receptor 3 eotaxin receptor, and IL-5 receptor alpha. Interestingly, a common feature is that the critical cis-acting elements for these transcription factors are clustered in exon 1 and intron 1 of these genes rather than their promoters. Elucidation of the mechanism of eosinophil development and activation may lead to selective elimination of eosinophils in animals and human subjects. Furthermore, availability of a range of genetically modified mice lacking or overproducing eosinophil-specific genes will facilitate evaluation of the roles of eosinophils in the pathogenesis of asthma. This review summarizes eosinophil biology, focusing on development and regulation of eosinophil-specific genes, with a heavy emphasis on the causative link between eosinophils and pathological development of asthma using genetically modified mice as models of asthma

    Neuronal Deletion of Caspase 8 Protects against Brain Injury in Mouse Models of Controlled Cortical Impact and Kainic Acid-Induced Excitotoxicity

    Get PDF
    system. mice demonstrated superior survival, reduced seizure severity, less apoptosis, and reduced caspase 3 processing. Uninjured aged knockout mice showed improved learning and memory, implicating a possible role for caspase 8 in cognitive decline with aging.Neuron-specific deletion of caspase 8 reduces brain damage and improves post-traumatic functional outcomes, suggesting an important role for this caspase in pathophysiology of acute brain trauma

    HIV-2 interaction with cell coreceptors: amino acids within the V1/V2 region of viral envelope are determinant for CCR8, CCR5 and CXCR4 usage

    Get PDF
    © 2014 Santos-Costa et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Background: Human immunodeficiency virus 1 and 2 (HIV-1 and HIV-2) use cellular receptors in distinct ways. Besides a more promiscuous usage of coreceptors by HIV-2 and a more frequent detection of CD4-independent HIV-2 isolates, we have previously identified two HIV-2 isolates (HIV-2MIC97 and HIV-2MJC97) that do not use the two major HIV coreceptors: CCR5 and CXCR4. All these features suggest that in HIV-2 the Env glycoprotein subunits may have a different structural organization enabling distinct - although probably less efficient - interactions with cellular receptors. Results: By infectivity assays using GHOST cell line expressing CD4 and CCR8 and blocking experiments using CCR8-specific ligand, I-309, we show that efficient replication of HIV-2MIC97 and HIV-2MJC97 requires the presence of CCR8 at plasma cell membrane. Additionally, we disclosed the determinants of chemokine receptor usage at the molecular level, and deciphered the amino acids involved in the usage of CCR8 (R8 phenotype) and in the switch from CCR8 to CCR5 or to CCR5/CXCR4 usage (R5 or R5X4 phenotype). The data obtained from site-directed mutagenesis clearly indicates that the main genetic determinants of coreceptor tropism are located within the V1/V2 region of Env surface glycoprotein of these two viruses. Conclusions: We conclude that a viral population able to use CCR8 and unable to infect CCR5 or CXCR4-positive cells, may exist in some HIV-2 infected individuals during an undefined time period, in the course of the asymptomatic stage of infection. This suggests that in vivo alternate molecules might contribute to HIV infection of natural target cells, at least under certain circumstances. Furthermore we provide direct and unequivocal evidence that the usage of CCR8 and the switch from R8 to R5 or R5X4 phenotype is determined by amino acids located in the base and tip of V1 and V2 loops of HIV-2 Env surface glycoprotein.This work was supported by grants from: Fundação para a Ciência e Tecnologia (FCT; PPCDT/SAU-IMI/55726/2004); Fundação para a Ciência e Tecnologia and Ministério da Saúde de Portugal (VIH/SAU/0006/2011); and from Gilead Sciences Portugal (Programa Gilead Génese).info:eu-repo/semantics/publishedVersio
    • …
    corecore