1,720,961 research outputs found
Toll-like receptor-4 drives pro-inflammatory cytokine response & tissue degradation in human bacterial keratitis
No full textPurpose: : Toll-like Receptor-4 (TLR4) is a key component of the innate immune response during bacterial infections. Pathways and downstream effectors relating to TLR signalling in human bacterial keratitis (BK) remain unknown. By activating the TLR4 signalling cascade with bacterial lipoploysaccharide (LPS), we investigated whether TLR4 influenced matrix metalloproteases (MMP-2, MMP-9) and cytokine expression in diseased human primary corneal fibroblast (CF) cells are altered.Methods: : Human primary CF cells from patients with severe corneal ulceration from patients with gram negative bacterial keratitis were grown ex vivo and cultured in conjunction with healthy controls. CF cells were treated with exogenous LPS derived from Pseudomonas Aeruginosa.Results: : TLR4, MMP-2 and MMP-9 were constitutively expressed in both ulcerated and control CF cells. Diseased CF cells showed greater responsiveness to LPS stimulation. TLR4 and MMP-9 expression was dose-dependently increased by LPS. MMP-2 expression was not affected by LPS. Analysis on cytokine expression revealed that IL-2, IL-8, IL-10, IL-12p70, GM-CSF, IFNγ and TNF-α expression increased following LPS treatment but only in the diseased cells.Conclusions: : TLR4 activation with LPS increases TLR4, MMP-9 and cytokine expression in CF cells cultured from human BK patients. Over expression of these products may provide a local mechanism to eradicate bacterial infection but also contribute to corneal ulceration and perforation. This is the first description of the effect of TLR4 activation in human bacterial keratitis
Lipopolysaccharide regulation of Toll-like receptor-4 and matrix metalloprotease-9 in human primary corneal fibroblasts
No full textPurpose.: Toll-like receptor 4 (TLR4) is a key component of the innate immune response related to microbial keratitis (MK). Pathways and downstream effectors relating to TLR signaling remain unknown in human bacterial MK. To this effect, by activating the TLR4 signaling cascade with lipopolysaccharide (LPS), the authors investigated whether TLR4, matrix metalloproteases (MMP)-2, MMP-9, and cytokine expression in diseased human primary corneal fibroblasts (CFs) were altered.Methods.: Human primary CFs from patients with severe corneal ulceration were cultured in conjunction with healthy control CFs and treated with LPS derived from Pseudomonas aeruginosa.Results.: TLR4, MMP-2, and MMP-9 were constitutively expressed in both ulcerated and control CFs. Diseased CFs showed greater responsiveness to LPS stimulation. TLR4 and MMP-9 expression was dose-dependently increased by LPS. MMP-2 expression was not affected by LPS. Analysis on cytokine expression revealed that IL-2, IL-8, IL-10, IL-12p70, GM-CSF, IFNγ, and TNFα expression increased after LPS treatment but only in diseased cells.Conclusions.: TLR4 activation with LPS increases TLR4, MMP-9, and cytokine expression in CFs cultured from patients with microbial keratitis. Overexpression of these products may provide a local mechanism to eradicate bacterial infection but may also aid corneal ulceration and perforation
MicroRNA-155 targets SMAD2 and modulates the response of macrophages to transforming growth factor-{beta}
No full textTransforming growth factor-beta (TGF-?) is a pleiotropic cytokine with important effects on processes such as fibrosis, angiogenesis, and immunosupression. Using bioinformatics, we identified SMAD2, one of the mediators of TGF-? signaling, as a predicted target for a microRNA, microRNA-155 (miR-155). MicroRNAs are a class of small non-coding RNAs that have emerged as an important class of gene expression regulators. miR-155 has been found to be involved in the regulation of the immune response in myeloid cells. Here, we provide direct evidence of binding of miR-155 to a predicted binding site and the ability of miR-155 to repress SMAD2 protein expression. We employed a lentivirally transduced monocyte cell line (THP1-155) containing an inducible miR-155 transgene to show that endogenous levels of SMAD2 protein were decreased after sustained overexpression of miR-155. This decrease in SMAD2 led to a reduction in both TGF-?-induced SMAD-2 phosphorylation and SMAD-2-dependent activation of the expression of the CAGA(12)LUC reporter plasmid. Overexpression of miR-155 altered the cellular responses to TGF-? by changing the expression of a set of genes that is involved in inflammation, fibrosis, and angiogenesis. Our study provides firm evidence of a role for miR-155 in directly repressing SMAD2 expression, and our results demonstrate the relevance of one of the two predicted target sites in SMAD2 3'-UTR. Altogether, our data uncover an important role for miR-155 in modulating the cellular response to TGF-? with possible implications in several human diseases where homeostasis of TGF-? might be altered
The interleukin 13 (IL-13) pathway in human macrophages is modulated by microRNA-155 via direct targeting of interleukin 13 receptor ?1 (IL13R?1)
No full textMacrophages play a central role in the balance and efficiency of the immune response and are at the interface between innate and adaptive immunity. Their phenotype is a delicate equilibrium between the M1 (classical, pro-Th(1)) and M2 (alternative, pro-Th(2)) profiles. This balance is regulated by cytokines such as interleukin 13 (IL-13), a typical pro-M2-Th(2) cytokine that has been related to allergic disease and asthma. IL-13 binds to IL-13 receptor ?1 (IL13R?1), a component of the Type II IL-4 receptor, and exerts its effects by activating the transcription factor signal transducer and activator of transcription 6 (STAT6) through phosphorylation. MicroRNAs are short (?22 nucleotide) inhibitory non-coding RNAs that block the translation or promote the degradation of their specific mRNA targets. By bioinformatics analysis, we found that microRNA-155 (miR-155) is predicted to target IL13R?1. This suggested that miR-155 might be involved in the regulation of the M1/M2 balance in macrophages by modulating IL-13 effects. miR-155 has been implicated in the development of a healthy immune system and function as well as in the inflammatory pro-Th(1)/M1 immune profile. Here we have shown that in human macrophages, miR-155 directly targets IL13R?1 and reduces the levels of IL13R?1 protein, leading to diminished activation of STAT6. Finally we also demonstrate that miR-155 affects the IL-13-dependent regulation of several genes (SOCS1, DC-SIGN, CCL18, CD23, and SERPINE) involved in the establishment of an M2/pro-Th(2) phenotype in macrophages. Our work shows a central role for miR-155 in determining the M2 phenotype in human macrophages
MicroRNA-155 modulates the pathogen binding ability of dendritic cells (DCs) by down-regulation of DC-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN)
No full textMicroRNA-155 (miR-155) has been involved in the response to inflammation in macrophages and lymphocytes. Here we show how miR-155 participates in the maturation of human dendritic cells (DC) and modulates pathogen binding by down-regulating DC-specific intercellular adhesion molecule-3 grabbing non-integrin (DC-SIGN), after directly targeting the transcription factor PU.1. During the maturation of DCs, miR-155 increases up to 130-fold, whereas PU.1 protein levels decrease accordingly. We establish that human PU.1 is a direct target for miR-155 and localize the target sequence for miR-155 in the 3'-untranslated region of PU.1. Also, overexpression of miR-155 in the THP1 monocytic cell line decreases PU.1 protein levels and DC-SIGN at both the mRNA and protein levels. We prove a link between the down-regulation of PU.1 and reduced transcriptional activity of the DC-SIGN promoter, which is likely to be the basis for its reduced mRNA expression, after miR-155 overexpression. Finally, we show that, by reducing DC-SIGN in the cellular membrane, miR-155 is involved in regulating pathogen binding as dendritic cells exhibited the lower binding capacity for fungi and HIV protein gp-120 when the levels of miR-155 were higher. Thus, our results suggest a mechanism by which miR-155 regulates proteins involved in the cellular immune response against pathogens that could have clinical implications in the way pathogens enter the human organism
Receptor-mediated interactions between colloidal gold nanoparticles and human umbilical vein endothelial cells
No full textA new strategy to manipulate cell operations is demonstrated, based on membrane-receptor-specific interactions between colloidal peptide-capped gold nanoparticles and human umbilical vein endothelial cells. It is shown that colloidal gold nanoparticles of similar charge and size but capped with different peptide sequences can deliberately trigger specific cell functions related to the important biological process of blood vessel growth known as angiogenesis. Specific binding of the peptide-capped particles to two endothelial-expressed receptors (VEGFR-1, NRP-1), which control angiogenesis, is achieved. The cellular fate of the functional nanoparticles is imaged and the influence of the different peptide-coated nanoparticles on the gene expression profile of hypoxia-related and angiogenic genes is monitored. The findings open up new avenues towards the deliberate biological control of cellular functions using strategically designed nanoparticle
Role of retinoic acid or vitamin D analogue in models of human keratinocyte apoptosis Interactions with the IGF system
No full textAvailable from British Library Document Supply Centre- DSC:DXN060380 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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