1,720,990 research outputs found
Immunoregulatory mechanisms of the arachidonic acid pathway in cancer
Full text linkThe arachidonic acid (AA) pathway promotes tumor progression by modulating the complex interactions between cancer and immune cells within the microenvironment. In this Review, we summarize the knowledge acquired thus far concerning the intricate mechanisms through which eicosanoids either promote or suppress the antitumor immune response. In addition, we will discuss the impact of eicosanoids on immune cells and how they affect responsiveness to immunotherapy, as well as potential strategies for manipulating the AA pathway to improve anticancer immunotherapy. Understanding the molecular pathways and mechanisms underlying the role played by AA and its metabolites in tumor progression may contribute to the development of more effective anticancer immunotherapies
Lipoxins and aspirin-triggered lipoxins in resolution of inflammation
No full textThe resolution of the inflammatory response is highly regulated by the timely biosynthesis of a number of endogenous lipid mediators. Among these, lipoxins (LX) and their 15-epimers, aspirin triggered lipoxins (ATL) derived by the lipoxygenase (LO) route of arachidonic acid metabolism. In particular, they are formed and released by cells expressing 5-,12- and 15-LO such as leukocytes, platelets, vascular endothelium and epithelium, alone or during transcellular interactions. ATL biosynthesis requires cyclooxygenase-2 acetylation by aspirin. LX and ATL exert potent bioactions on leukocytes, vascular and epithelial cells to stop inflammation and promote resolution. They have shown to be beneficial in a broad spectrum of preclinical models of disease as well as in some clinical trials. Counter-regulatory signaling by LXA4 and 15-epi-LXA4 follows the activation of a G protein-coupled receptor, termed ALX/FPR2, which is emerging as a key anti-inflammatory receptor
Proresolving Lipid Mediators and Receptors in Stem Cell Biology: Concise Review
No full textSummary Accumulating evidence indicates that stem cells (SCs) possess immunomodulatory, anti‐inflammatory, and prohealing properties. The mechanisms underlying these functions are being investigated with the final goal to set a solid background for the clinical use of SCs and/or their derivatives. Specialized proresolving lipid mediators (SPMs) are small lipids formed by the enzymatic metabolism of polyunsaturated fatty acids. They represent a leading class of molecules that actively and timely regulate the resolution of inflammation and promote tissue/organ repair. SC formation of these mediators as well as expression of their receptors has been recently reported, suggesting that SPMs may be involved in the immunomodulatory, proresolving functions of SCs. In the present review, we summarize the current knowledge on SPMs in SCs, focusing on biosynthetic pathways, receptors, and bioactions, with the intent to provide an integrated view of SPM impact on SC biology. Stem Cells Translational Medicine 2019;8:992–99
Epigenetic regulation of the formyl peptide receptor 2 gene
No full textpoxin (LX) A4, a main stop signal of inflammation, exerts potent bioactions by activating a specific G proteincoupled
receptor, termed formyl peptide receptor 2 and recently renamed ALX/FPR2. Knowledge of the regulatory
mechanisms that drive ALX/FPR2 gene expression is key for the development of innovative antiinflammatory
pharmacology. Here, we examined chromatin patterns of the ALX/FPR2 gene. We report that in
MDA-MB231 breast cancer cells, the ALX/FPR2 gene undergoes epigenetic silencing characterized by low acetylation
at lysine 27 and trimethylation at lysine 4, associated with high methylation at lysine 27 of histone 3. This
pattern, which is consistent with transcriptionally inaccessible chromatin leading to low ALX/FPR2 mRNA and
protein expression, is reversed in polymorphonuclear leukocytes that express high ALX/FPR2 levels. Activation
of p300 histone acetyltransferase and inhibition of DNA methyltransferase restored chromatin accessibility and
significantly increased ALX/FPR2 mRNA transcription and protein levels in MDA-MB231 cells, as well as in pulmonary
artery endothelial cells. In both cells types, changes in the histone acetylation/methylation status enhanced
ALX/FPR2 signaling in response to LXA4. Collectively, these results uncover unappreciated epigenetic
regulation of ALX/FPR2 expression that can be exploited for innovative approaches to inflammatory disorders
MicroRNA-181b regulates ALX/FPR2 expression and proresolution signaling in human macrophages.
No full textRegulatory mechanisms of ALX/FPR2, the lipoxin A4 receptor, expression have considerable relevance in inflammation resolution. Because microRNAs (miRs) are emerging as key players in inflammation resolution, here we examined microRNA-mediated regulation of ALX/FPR2 (lipoxin A4 receptor/formyl peptide receptor 2) expression. By matching data from bioinformatic algorithms, we found 27 miRs predicted to bind the 3'-UTR of ALX/FPR2. Among these, we selected miR-181b because of its link with inflammation. Using a luciferase reporter system, we assessed miR-181b binding to ALX/FPR2 3'-UTR. Consistent with this, miR-181b overexpression in human macrophages significantly down-regulated ALX/FPR2 protein levels (-25%), whereas miR-181b knockdown gave a significant increase in ALX/FPR2 (+60%). miR-181b levels decreased during monocyte to macrophage differentiation (-50%), whereas ALX/FPR2 expression increased significantly (+60%). miR-181b overexpression blunted lipoxin A4 (0.1-10 nm)- and resolvin D1 (0.01-10 nm)-stimulated phagocytic activity of macrophages. These results unravel novel regulatory mechanisms of ALX/FPR2 expression and ligand-evoked macrophages proresolution responses mediated by miR-181b, thus uncovering novel components of the endogenous inflammation resolution circuits
The diadenosine tetraphosphate hydrolase ApaH contributes to Pseudomonas aeruginosa pathogenicity
No full textThe opportunistic bacterial pathogen Pseudomonas aeruginosa causes a wide range of infections that are difficult to treat, largely because of the spread of antibiotic-resistant isolates. Antivirulence therapy, & iacute;.e. the use of drugs that inhibit the expression or activity of virulence factors, is currently considered an attractive strategy to reduce P. aeruginosa pathogenicity and complement antibiotic treatments. Because of the multifactorial nature of P. aeruginosa virulence and the broad arsenal of virulence factors this bacterium can produce, the regulatory networks that control the expression of multiple virulence traits have been extensively explored as potential targets for antivirulence drug development. The intracellular signaling molecule diadenosine tetraphosphate (Ap4A) has been reported to control stress resistance and virulence-related traits in some bacteria, but its role has not been investigated in P. aeruginosa so far. To fill this gap, we generated a mutant of the reference strain P. aeruginosa PAO1 that lacks the Ap4A-hydrolysing enzyme ApaH and, consequently, accumulates high intracellular levels of Ap4A. Phenotypic and transcriptomic analyses revealed that the lack of ApaH causes a drastic reduction in the expression of several virulence factors, including extracellular proteases, elastases, siderophores, and quorum sensing signal molecules. Accordingly, infection assays in plant and animal models demonstrated that ApaH-deficient cells are significantly impaired in infectivity and persistence in different hosts, including mice. Finally, deletion of apaH in P. aeruginosa clinical isolates demonstrated that the positive effect of ApaH on the production of virulence-related traits and on infectivity is conserved in P. aeruginosa. This study provides the first evidence that the Ap4A-hydrolysing enzyme ApaH is important for P. aeruginosa virulence, highlighting this protein as a novel potential target for antivirulence therapies against P. aeruginosa
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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