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Platelets as immune cells in physiology and immunopathology

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197408 Year: Pages: 111 DOI: 10.3389/978-2-88919-740-8 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2016-04-07 11:22:02
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Are platelets cells? (Not everyone agrees, since they are non-nucleate). And if platelets are cells - which all specialists consider at the time being - are they immune cells? The issue that platelets participate in immunity is no longer debated; however, the issue that they are key cells in immunity is challenged. It has even been proposed a couple of years ago that platelets can present antigen to T-lymphocytes by using their HLA class I molecules. No one has the same functional definition of platelets. The ‘Frontiers Research Topic’- coordinators’ own view is that platelets are primarily repairing cells, what they do in deploying tools of physiological inflammation. This function is better acknowledged as primary hemostasis, i.e. platelet adherence to injured or wounded vessels, followed by activation, aggregation, and constitution of the initial clot. Platelets would thus repair damaged vascular endothelium; so doing, as they patrol to detect damages, they sense danger along the vascular arborescence. As the latter is immense, platelets get close to tissues, which are not allowed to them under ‘physiological’ conditions but are readily accessible in pathology. Platelets are equipped with a variety of Pathogen Recognition Receptors such as TLRs; they have a complete signalosome, which is functional until the phosphorylation of NFkB; they have been proved to retro-transcribe RNA and synthesize de novo proteins; etc. Platelets participate to inflammation along the whole spectrum: from physiological (tissue repair, healing) to acute/severe inflammation (as can be seen in e.g. sepsis). In general, platelets engage complex interactions with most infectious pathogens. We propose there to cover those topics - from physiology to pathology, that put platelets within cells that not only take place in-, but also are key players of-, innate immunity. The relation of platelets with adaptive immunity is even more complex. Not everyone is convinced that platelets present antigens; however, platelets influence adaptive immunity since they have mutual interactions with Dendritic cells, Monocytes/Macrophages, and B-lymphocytes (the key players of antigen presentation); they also have mutual interactions with T-lymphocytes, though is issue is less clearly deciphered. We propose to also cover these topics - or to present the forum. There is another issue which is medically relevant - speaking of physiology/physiopathology-: this is fetal maternal incompatibility of platelet specific antigens (the HPA system) and the likely formation of maternal antibodies that often injure the newborn with risks of severe thrombocytopenia and intracranial hemorrhage. We propose an update on this issue as well. Last, platelets are very special because they can be directly therapeutic (by transfusion), even when being offered by a generous blood donor displaying given genetic and phenotypic parameters to a patient/recipient in need, who also display his/her own genetic and phenotypic parameters, which - for a large part - differ from the donor's ones. Besides immunization - via mechanisms probably close to the fetal maternal platelet incompatibility, but likely not similar -, transfusion has allowed the identification of the tremendous capacity of platelets to mediate inflammation: we propose to conclude the Topics with this item/forum.

Keywords

platelets --- Infection --- Inflammation --- immunity

Nutrients, Infectious and Inflammatory Diseases

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ISBN: 9783038427919 9783038427926 Year: Pages: CCCXLVIII, 18 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Internal medicine
Added to DOAB on : 2018-04-27 16:16:52
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Foodborne disease like salmonellosis and toxoplasmosis are amongst the most significant causes of hospitalization in the U.S. and globally. Gastrointestinal infections alter gut microbiomes and increase permeability to toxins. Various invasions by microbial, fungal, viral and parasitic agents stimulate inflammation, a defensive mechanism of the body’s immune system. Other stimuli include environmental stimuli, oxidative stress, aging and the physiological process. A long-lasting, persistent and excessive inflammatory response is a significant risk factor for developing various chronic inflammatory and infectious diseases.Different nutritional and dietary life styles, whether poor or lacking essential nutritional elements, as well as excess intake, can result in inflammatory complications and loss of function. Nutritional deficiency is linked with several infectious and inflammatory diseases as a cause or consequence. For instance, protein deficiency was reported in orphanages to provoke microbial and fungal complications including Pneumocystis pneumonia. Similarly, protein deficiency is a tell-tale sign of several parasitic diseases. Studies indicate that nutrients, such as amino acids, oligosaccharides, and short-chain fatty acids exert inhibitory and anti-inflammatory functions. These investigations help to understand nutritional contributions to the prevention, treatment and taming of certain inflammatory and infectious diseases. Infectious and inflammatory complications go hand-in-hand with malnutrition.The purpose of this Special Issue is to publish related new, basic and translational findings and clinical trials in this area. Other investigations or review articles were sought to link infectious and inflammatory diseases with nutrients. In addition, novel diagnostic, preventive and therapeutic modalities were invited to aid the development of nutritional strategies for the treatment and/or prevention of inflammation and infection. Original reviews were of particular interest to advance our understanding of signaling pathways, and the molecular and biochemical mechanisms behind the effects of nutrients on inflammatory and infectious diseases.

Comparative studies between HTLV-1 and HTLV-2 function and pathobiology

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194988 Year: Pages: 94 DOI: 10.3389/978-2-88919-498-8 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2015-11-16 15:44:59
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Human T-cell leukemia viruses type 1 and 2 (HTLV-1 and HTLV-2) share a common genetic organization, expression strategy and ability to infect and immortalize T-cells in vitro; however, HTLV-1 and HTLV-2 are strikingly different in terms of clinical impact. HTLV-1 is recognized as the aetiological agent of adult T-cell leukemia/lymphoma (ATLL), and HTLV-associated myeolopathy/tropical spastic paraparesis (HAM/TSP), in contrast, HTLV-2 does not cause hematologic disorders and is only sporadically associated with cases of subacute myelopathy. HTLV-1 and HTLV-2 also exhibit distinct cellular tropisms in vivo: HTLV-1 is mainly found in CD4+T lymphocytes, whereas CD8+T-cells are the preferred target for HTLV-2. The articles contributed in this Research Topic are covering all the different aspects that characterize HTLV-1 and HTLV-2, by highlighting differences in their biology that might provide clues to their distinct pathogenic properties.

Keywords

HTLV-1 --- HTLV-2 --- Expression --- Proteins --- Co-infection

M1/M2 Macrophages: The Arginine Fork in the Road to Health and Disease

Authors: --- ---
Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194995 Year: Pages: 280 DOI: 10.3389/978-2-88919-499-5 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2015-12-03 13:02:24
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Macrophages have unique and diverse functions necessary for survival. And, in humans (and other species), they are the most abundant leukocytes in tissues. The Innate functions of macrophages that are best known are their unusual ability to either "Kill" or "Repair". Since killing is a destructive process and repair is a constructive process, it was stupefying how one cell could exhibit these 2 polar – opposite functions. However, in the late 1980’s, it was shown that macrophages have a unique ability to enzymatically metabolize Arginine to Nitric Oxide (NO, a gaseous non – specific killer molecule) or to Ornithine (a precursor of polyamines and collagen for repair). The dual Arginine metabolic capacity of macrophages provided a functional explanation for their ability to kill or repair. Macrophages predominantly producing NO are called M1 and those producing Ornithine are called M2. M1 and M2 – dominant responses occur in lower vertebrates, and in T cell deficient vertebrates being directly driven by Damage and Pathogen Associated Molecular Patterns (DAMP and PAMP). Thus, M1 and M2 are Innate responses that protect the host without Adaptive Immunity. In turn, M1/M2 is supplanting previous models in which T cells were necessary to "activate" or "alternatively activate" macrophages (the Th1/Th2 paradigm). M1 and M2 macrophages were named such because of the additional key findings that these macrophages stimulate Th1 and Th2 – like responses, respectively. So, in addition to their unique ability to kill or repair, macrophages also govern Adaptive Immunity. All of the foregoing would be less important if M1 or M2 – dominant responses were not observed in disease. But, they are. The best example to date is the predominance of M2 macrophages in human tumors where they act like wound repair macrophages and actively promote growth. More generally, humans have become M2 – dominant because sanitation, antibiotics and vaccines have lessened M1 responses. And, M2 dominance seems the cause of ever - increasing allergies in developed countries. Obesity represents a new and different circumstance. Surfeit energy (e.g., lipoproteins) causes monocytes to become M1 dominant in the vessel walls causing plaques. Because M1 or M2 dominant responses are clearly causative in many modern diseases, there is great potential in developing the means to selectively stimulate (or inhibit) either M1 or M2 responses to kill or repair, or to stimulate Th1 or Th2 responses, depending on the circumstance. The contributions here are meant to describe diseases of M1 or M2 dominance, and promising new methodologies to modulate the fungible metabolic machinery of macrophages for better health.

Keywords

macrophage --- innate immunity --- M1 --- M2 --- wound --- Cancer --- Infection --- Atherosclerosis

Human Polyomaviruses and Papillomaviruses

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ISBN: 9783038972204 9783038972211 Year: Pages: 196 DOI: 10.3390/books978-3-03897-221-1 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Biology --- Oncology
Added to DOAB on : 2018-09-21 09:25:07
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The interest in human polyomaviruses (HPyV) has seen a renaissance because of new species that have been isolated and their previously unknown association with diseases. Likewise, the increasing evidence for the association of human papillomaviruses (HPV) with oropharyngeal cancer has sparked the attention of researchers and clinicians. The Special Issue “Human Polyomaviruses and Papillomaviruses” presents studies describing the nuclear egress of BK polyomavirus mediated by the viral agnoprotein and the cellular -SNAP protein. In addition, a study examines the promoter activity of two different variants of human polyomavirus 9 in different cell lines. This Special Issue offers an interesting perspective on the epidemiology of HR-HPV in different cancers and on the mechanisms by which these viruses target host cell proteins to replicate their genome, express their genes, interfere with autophagy, and induce cancer. Other topics that are highlighted include the role of co-factors, such as smoking and co-infection, novel therapeutic strategies, and surface immunoregulatory proteins, chemokines, and cytokines as possible biomarkers to determine the stage of a tumor and to predict clinical outcomes.

The Neonatal Immune System: A Unique Host-Microbial Interface

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889454037 Year: Pages: 175 DOI: 10.3389/978-2-88945-403-7 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Pediatrics --- Allergy and Immunology --- Science (General) --- Microbiology
Added to DOAB on : 2018-11-16 17:17:57
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Emerging from the protective environment of the uterus, the newborn is exposed to a myriad of microbes, and quickly establishes a complex microbiome that shapes the infant’s biology in ways that are only now beginning to come to light. Among these exposures are a number of potential pathogens. The host responses to these pathogens in the neonatal period are unique, reflecting a developing immune system even with delivery at term. Preterm infants are delivered at a time when host defense mechanisms are even less developed and therefore face additional risk. As such, the organisms that cause disease in this period are different from the pathogens that are common in other age groups, or the disease they cause manifests in more severe fashion. Developmental alterations in both innate and adaptive immune responses in neonates have been documented among many cell types and pathways over the last several decades. Contemporary insights into the human immune system and methodologies that allow an “omics” approach to these questions have continued to provide new information regarding the mechanisms that underlie the human neonate as an “immunocompromised host.” This Research Topic highlights studies related to this unique host-pathogen interface. Contributions include those related to the innate or adaptive immune system of neonates, their response to microbial colonization or infection, and/or the pathogenesis of microbes causing disease in neonates.

The Role of Iron in Bacterial Pathogenesis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889456628 Year: Pages: 156 DOI: 10.3389/978-2-88945-662-8 Language: English
Publisher: Frontiers Media SA
Subject: Science (General) --- Internal medicine
Added to DOAB on : 2019-01-23 14:53:43
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The collection of articles published in this eBook represent different facets of the interactions between pathogens and their host concerning the battle for iron. Pathogens have developed different strategies to acquire iron from their host. These include the production of siderophores, heme acquisition and ferrous iron uptake.

Penicilina em Portugal (anos 40-50 do século XX): receção, importação e primeiros tratamentos

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Book Series: Ciências e Culturas ISBN: 9789892612232 Year: Pages: 138 DOI: https://doi.org/10.14195/978-989-26-1224-9 Language: Portuguese
Publisher: Coimbra University Press
Subject: Medicine (General)
Added to DOAB on : 2019-04-23 16:21:06
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In September 1944, Portugal began to import a regular supply of penicillin from the US. The Portuguese Red Cross scrupulously controlled the supply distribution of the antibiotic. In 1945, as world production increased, penicillin began to be distributed through regular channels. The analysis of archive material concerning the reception and distribution of penicillin enabled the author to ascertain how they took place and present case study regarding the first treatments with the antibiotic in Portugal, in Coimbra University Hospitals.

Structural and computational glycobiology: immunity and infection

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196388 Year: Pages: 102 DOI: 10.3389/978-2-88919-638-8 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2015-10-30 16:33:44
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Interest in understanding the biological role of carbohydrates has increased significantly over the last 20 years. The use of structural techniques to understand carbohydrate-protein recognition is still a relatively young area, but one that is of emerging importance. The high flexibility of carbohydrates significantly complicates the determination of high quality structures of their complexes with proteins. Specialized techniques are often required to understand the complexity of carbohydrate recognition by proteins. In this Research Topic, we will focus on structural and computational approaches to understanding carbohydrate recognition by proteins involved in immunity and infection. Particular areas of focus include cancer immunotherapeutics, carbohydrate-lectin interactions, glycosylation and glycosyltransferases.

CD4+ T cell differentiation in infection: amendments to the Th1/Th2 axiom

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889195657 Year: Pages: 111 DOI: 10.3389/978-2-88919-565-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2016-01-19 14:05:46
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CD4+ T lymphocytes play an essential role in host defense against bacterial, parasitic and viral infections. During infection, under the influence of intrinsic signals received through peptide-MHC/TCR interactions and extrinsic signals provided by pathogen-conditioned dendritic and other accessory cells, CD4+ T cells proliferate and differentiate into specialized T helper (Th) effectors, which produce distinct sets of cytokines tailored to combat a specific class of microbes. The concept of CD4+ T cell multi-functionality was developed after the seminal discovery of Th1 and Th2 cells nearly 30 years ago. Although the Th1/Th2 paradigm has successfully withstood the test of time, in the past decade additional Th subsets (Th17, Tfh, Th22, Th9) have been identified. Similarly, single cell analyses of cytokines and master transcriptional factors have revealed that, at the population level, CD4+ T cell responses are far more heterogeneous than initially anticipated. While some of the checkpoints in Th cell specification have been identified, recent studies of transcriptional and epigenetic regulation have uncovered a significant flexibility during the course CD4+ T lymphocyte polarization. In addition, Th cells expressing cytokines with counteracting functions, as a measure of self-regulation, display yet another level of diversity. Understanding the mechanisms that control the balance between stability vs. plasticity of Th effectors both at the time of initiation of immune response and during development of CD4 T cell memory is critical for the rational design of better vaccines and new immunotherapeutic strategies. This research topic will cover current views on Th cell development, with a focus on the mechanisms that govern differentiation, function and regulation of effector Th cells in the context of microbial infections.

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