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Antimicrobial Peptides

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ISBN: 9783038420729 9783038420736 Year: Pages: 336 DOI: 10.3390/books978-3-03842-073-6 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2015-10-22 10:29:38
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Antimicrobial peptides (AMPs) are gene-encoded, ancient (and important) mediators of innate host defense that exert direct or indirect antimicrobial action as well as possessing other important biologic activities (e.g., neutralization of endotoxin and anti-biofilm action) that help to protect vertebrates, invertebrates and plants from invading pathogens. While the emergence of multi-antibiotic resistant pathogens (and the desperate need to develop new anti-infectives) has been a recent force driving the field, interest in AMPs has an earlier origin in studies of how phagocytes kill bacteria by oxygen-independent processes. AMPs responsible for such killing of microbes by rabbit and human neutrophils were later purified by Ganz, Selsted and Lehrer, which they termed defensins; at the time of this writing, literally thousands of defensin-based publications can be found in the scientific literature! The initial reports on defensins and the earlier report by Boman’s group on the purification and action of an insect AMP represented a historical and defining point for the AMP field as they, in hindsight, demanded the recognition of AMP research as a unique discipline that has important linkages to other important fields of medicine, especially those of microbiology, infectious diseases and immunology. On a personal note, I remember conferences on phagocytes and host defense in the early 1980s where the topic of AMPs was relegated to one short session in a five day period! Now, we have hundreds of international “AMPologists” with expertise in chemistry, biochemistry, molecular and structural biology, cell biology, microbiology, pharmacology, or medicine who have built their research careers around AMPs and can now attend international conferences dedicated to advances in AMP research.

HLA-G-mediated Immune Tolerance: Past and New Outlooks

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451197 Year: Pages: 92 DOI: 10.3389/978-2-88945-119-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2017-07-06 13:27:36
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The non-classical HLA class I molecule HLA-G is different from classical HLA class I molecules because of the low polymorphism in the coding region, the fact that HLA-G primary transcript is alternatively spliced in seven isoforms, and the inhibitory action on immune cells. Although HLA-G is low polymorphic, variants in both promoter and 3’ un-translated region (UTR) of HLA-G locus regulate its expression. In healthy conditions, a basal level of HLA-G gene transcription is observed in most cells and tissues; however, translation into HLA-G protein is restricted to trophoblasts in the placenta, where it participates in promoting tolerance at the fetal-maternal interface. HLA-G is also expressed by thymic epitelial, cornea, mesenchymal stem cells, nail matrix, pancreatic beta cells, erythroid, and endothelial precursors. HLA-G can be neo-expressed in adult tissues in pathological conditions, and its expression has been documented autoimmune disorders, viral infections, and cancer. In the latter setting de novo HLA-G expression is associated with the capability of tumor cells to evade the immune control. In the last decade it has become evident that HLA-G expression on T cells and antigenpresenting cells confers to these cells tolerogenic properties. This Research Topic focused on i) summarizing updated clinical and immunological evidences that HLA-G expression is associate with beneficial or detrimental tolerance, ii) gathering new insights into the mechanisms governing the expression of HLA-G in healthy and pathological conditions, such as pre-eclampsia, and iii) examining the mechanisms underlying HLA-G mediated tolerance.

Understanding Crohn's Disease: Immunity, Genes and Microbes

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889452149 Year: Pages: 126 DOI: 10.3389/978-2-88945-214-9 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2017-10-13 14:57:01
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Crohn's disease (CD) is a chronic, relapsing, inflammatory bowel disease resulting in considerable morbidity and reduced quality of life. Although still under intense debate, CD seems to result from an enhanced and uncontrolled immune response to the gut microbiota. CD is thought to be multifactorial depending on genetic and environmental determinants. In recent years, nearly 100 single nucleotide polymorphisms (SNPs) were associated with increased risk of developing CD (some of the SNPs also associated with susceptibility to ulcerative colitis, another type of IBD). These SNPs are mostly located in genes involved in innate and adaptive immunity mechanisms, such as autophagy, expression of pattern-recognition receptors and citokine signaling. Epigenetics is also probably playing a role in CD susceptibility, as it is sensitive to environmental conditions and may mediate gene-environment interactions. Environmental factors possibly involved in CD development include diet, gut microbiota composition and infection with specific pathogens, of which the most consistently associated to CD are Mycobacterium avium subsp. paratuberculosis and adherent-invasive Escherichia coli. This Topic aimed at bringing together contributions covering different genetic, epigenetic, immunological and microbial processes involved in the development of CD, helping to drive forward the understanding of CD immunopahtology.

Bioactive Compounds from Microbes

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889451852 Year: Pages: 142 DOI: 10.3389/978-2-88945-185-2 Language: English
Publisher: Frontiers Media SA
Subject: Microbiology --- Science (General)
Added to DOAB on : 2017-08-28 14:01:09
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Microorganisms have had a long and surprising history. They were “invisible” until invention of microscope in the 17th century. Until that date, although they were extensively (but inconsciously) employed in food preservation, beer and wine fermentation, cheese, vinegar, yogurt and bread making, as well as being the causative agents of infectious diseases, they were considered as “not-existing”. The work of Pasteur in the middle of the 19th century revealed several biological activities performed by microorganisms including fermentations and pathogenicity. Due to the urgent issue to treat infectious diseases (the main cause of death at those times) the “positive potential” of the microbial world has been neglected for about one century. Once the fight against the “evil” strains was fulfilled also thanks to the antibiotics, industry began to appreciate bacteria’s beneficial characteristics and exploit selected strains as starters for both food fermentations and aroma, enzyme and texturing agent production. However, it was only at the end of the 20th century that the probiotic potential of some bacteria such as lactic acid bacteria and bifidobacteria was fully recognized. Very recently, apart from the probiotic activity of in toto bacteria, attention has begun to be directed to the chemical mediators of the probiotic effect. Thanks also to the improvement of techniques such as transcriptomics, proteomics and metabolomics, several bioactive compounds are continuously being discovered. Bioactive molecules produced by bacteria, yeasts and virus-infected cells proved to be important for improving or impairing human health. The most important result of last years’ research concerns the discovery that a very complex network of signals allows communication between organisms (from intra-species interactions to inter-kingdom signaling). Based on these findings a completely new approach has arisen: the system biology standpoind. Actually, the different organisms colonizing a certain environmental niche are not merely interacting with each other as individuals but should be considered as a whole complex ecosystem continuously exchanging information at the molecular level. In this context, this topic issue explores both antagonistic compounds (i.e. antibiotics) and “multiple function” cooperative molecules improving the physiological status of both stimulators and targets of this network. From the applicative viewpoint, these molecules could be hopefully exploited to develop new pharmaceuticals and/or nutraceuticals for improving human health.

Phytoalexins: Current Progress and Future Prospects

ISBN: 9783038420583 9783038420590 Year: Pages: 516 Language: English
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Added to DOAB on : 2016-05-12 11:33:35
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Phytoalexins are antimicrobial substances of low molecular weight produced by plants in response to infection or stress, which form part of their active defense mechanisms. It is now clear that phytoalexins exhibit toxicity across much of the biological spectrum, prokaryotic and eukaryotic. Starting in the 1950s, research on phytoalexins has begun with biochemistry and bio-organic chemistry, resulting in the determination of their structure, their biological activity as well as mechanisms of their synthesis and their catabolism by microorganisms. Elucidation of the biosynthesis of numerous phytoalexins has also permitted the use of molecular biology tools for the exploration of the genes encoding enzymes of their synthesis pathways and their regulators. This has led to potential applications for increasing plant resistance to diseases. Phytoalexins display an enormous diversity belonging to various chemical families such as isoflavones, isoflavanones, pterocarpans, isoflavans, flavanones, coumestans, furanoacetylenes, phenylpropanoids, steroid glycoalkaloids, norsesquiterpenoids/sesquiterpenoids, coumarins, diterpenes, ent-kaurane-related diterpenoids, acidic sesquiterpenoids, 3-deoxyanthocyanidins, naphthaldehydes, indoles and stilbenes.Research papers dealing with all aspects of phytoalexins, including structure elucidation; chemical synthesis; methods for phytoalexin analysis in plant extracts or biological fluids; biosynthesis studies including modulation of phytoalexin synthesis; engineering of phytoalexin biochemical pathways in plants and microbes; biological activities; structure/activity relationships; phytoalexin metabolism in planta and by micro-organisms; roles and ATP Binding Cassette (ABC) transporters or Multi-Drugs Efflux (MDE) transporters are welcome for inclusion in this Special Issue of Molecules. Review articles, particularly those dealing with the themes mentioned above are also particularly welcome for inclusion.

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