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Macrophages Role in Integrating Tissue Signals and Biological Processes in Chronic Inflammation and Fibrosis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889453320 Year: Pages: 104 DOI: 10.3389/978-2-88945-332-0 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Allergy and Immunology
Added to DOAB on : 2018-02-27 16:16:45
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Macrophages comprehend a heterogeneous mononuclear phagocytic population with wide range phenotypes and roles in homeostasis maintenance and diseases, such as infections, autoimmunity and cancer. Technology improvements enable researchers to track different macrophage populations in different tissues and situations and hypothesize on their role in promoting inflammation or stimulating tissue repair. Through innate immune recognition system macrophages can launch several effector artilleries that culminate in the production of various types of inflammatory mediators as cytokines, chemokines, lipid mediators and oxygen reactive species, which in turn, influence the behavior of other cells. Furthermore, macrophages and interacting cells are also susceptible to metabolic changes that ultimately will define the outcome macrophage signaling and its effect in the tissue. Here, we present a concise series of discussions on the role of macrophages, its response to the microenvironment and effects on other cells during tissue injury and repair. Triggering of inflammasome in macrophage activation and function is of special interest in this issue. We will emphasize the role of different macrophage subpopulations and the plasticity of these cells during fibrotic process in different models of diseases.

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

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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

Metabolism and Immune Tolerance

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889457250 Year: Pages: 116 DOI: 10.3389/978-2-88945-725-0 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Allergy and Immunology
Added to DOAB on : 2019-01-23 14:53:43
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Historically the study of the immune system and metabolism have been two very separate fields. In recent years, a growing literature has emerged illustrating how the multiple processes of cellular metabolism are intricately linked to several aspects of immune function and development. This Research Topic covers recent progress in the field now known as “Immunometabolism” and the role of metabolism in immune tolerance. Immune tolerance is operationally defined as a state where a host’s immune system is balanced such that although self-reactive lymphocytes are present, they are kept in check by immune regulation. Perturbations to this homeostasis may result in self-reactive lymphocytes gaining the upper hand and mediating auto-immune disease. Maintenance of immune tolerance involves a large cast of different cell types including effector T cells, regulatory T cells, B cells, stromal cells, dendritic cells and macrophages.Intracellular pathways and individual enzymes of metabolism have been shown to be harnessed by cells of both the adaptive and innate immune system to allow particular immune functions to be achieved. Examples include metabolic enzymes serving ‘moonlighting’ functions in mRNA translation, gene splicing, and kinase activation. Other examples include the requirement for de novo fatty acid synthesis for differentiation into Th17 effectors and CD8 memory T cells or products of the TCA cycle promoting pro-inflammatory cytokine production. Likewise, the availability of extracellular metabolic substrates has a large impact on the maintenance of local immune tolerance. For example, there are different requirements for glucose, glutamine and fatty acids for effector versus regulatory T cell development. Also tolerogenic dendritic cells mediate lowering of extracellular essential amino acids by their enhanced catabolism, promoting the induction of regulatory T cells. The purpose of this Research Topic is to provide an update on the current understanding of the multiple roles for metabolism in regulating the immune system.

Obesity-induced inflammation and insulin resistance

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889194285 Year: Pages: 120 DOI: 10.3389/978-2-88919-428-5 Language: English
Publisher: Frontiers Media SA
Subject: Internal medicine --- Medicine (General)
Added to DOAB on : 2016-01-19 14:05:46
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Immune response and metabolic regulation are highly integrated and this interface maintains a central homeostatic system, dysfunction of which can cause obesity-associated metabolic disorder such as type 2 diabetes, fatty liver disease and cardiovascular disease. Insulin resistance is an underlying basis for the pathogenesis of these metabolic diseases. Overnutrition or obesity activates the innate immune system with subsequent recruitment of immune cells such as macrophages and T cells, which contributes to the development of insulin resistance. In particular, a significant advance in our understanding of obesity-associated inflammation and insulin resistance has been recognition of the critical role of adipose tissue macrophages (ATMs). ATMs are a prominent source of proinflammatory cytokines, such as TNF-a and IL-6, that can block insulin action in adipose tissue, skeletal muscle, and liver autocrine/paracrine signaling and cause systemic insulin resistance via endocrine signaling, providing a potential link between inflammation and insulin resistance. All articles in this topic highlight the interconnection between obesity, inflammation, and insulin resistance in all its diversity to the mechanisms of obesity-induced inflammation and role of immune system in the pathogenesis of insulin resistance and diabetes.

The metabolic challenges of immune cells in health and disease

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889196227 Year: Pages: 80 DOI: 10.3389/978-2-88919-622-7 Language: English
Publisher: Frontiers Media SA
Subject: Allergy and Immunology --- Medicine (General)
Added to DOAB on : 2016-08-16 10:34:25
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Obesity and its co-morbidities, including atherosclerosis, insulin resistance and diabetes, are a world-wide epidemic. Inflammatory immune responses in metabolic tissues have emerged as a universal feature of these metabolic disorders. While initial work highlighted the contribution of macrophages to tissue inflammation and insulin resistance, recent studies demonstrate that cells of the adaptive immune compartment, including T and B lymphocytes and dendritic cells also participate in obesity-induced pathogenesis of these conditions. However, the molecular and cellular pathways by which the innate and adaptive branches of immunity control tissue and systemic metabolism remain poorly understood. To engage in growth and activation, cells need to increase their biomass and replicate their genome. This process presents a substantial bioenergetic challenge: growing and activated cells must increase ATP production and acquire or synthesize raw materials, including lipids, proteins and nucleic acids. To do so, they actively reprogram their intracellular metabolism from catabolic mitochondrial oxidative phosphorylation to glycolysis and other anabolic pathways. This metabolic reprogramming is under the control of specific signal transduction pathways whose underlying molecular mechanisms and relevance to physiology and disease are subject of considerable current interest and under intense study. Recent reports have elucidated the physiological role of metabolic reprogramming in macrophage and T cell activation and differentiation, B- and dendritic cell biology, as well as in the crosstalk of immune cells with endothelial and stem cells. It is also becoming increasingly evident that alterations of metabolic pathways play a major role in the pathogenesis of chronic inflammatory disorders. Due to the scientific distance between immunologists and experts in metabolism (e.g., clinicians and biochemists), however, there has been limited cross-talk between these communities. This collection of articles aims at promoting such cross-talk and accelerating discoveries in the emerging field of immunometabolism.

Reassessing Twenty Years of Vaccine Development Against Tuberculosis

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889454464 Year: Pages: 110 DOI: 10.3389/978-2-88945-446-4 Language: English
Publisher: Frontiers Media SA
Subject: Medicine (General) --- Allergy and Immunology
Added to DOAB on : 2018-11-16 17:17:57
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Tuberculosis (TB) remains the prime bacterial infection worldwide with 10.4 million infections and a death toll of 1.7 million people in 2016 according to WHO statistics. Tuberculosis is caused by members of the Mycobacterium tuberculosis complex, facultative intracellular bacteria able to thrive within otherwise potent innate defense cells, the macrophages. In a world of increasing numbers of infections with drug resistant M. tuberculosis strains, the daunting race between developing new therapeutics and emerging resistant strains will hardly produce a winner. This cycle can only be broken by enhancing population wide immune control through a better vaccine as the only one currently in use, M. bovis Bacillus Calmette Guerin (BCG). The protective efficacy of BCG against pulmonary tuberculosis in all age groups is dissatisfying and geographically highly diverse with the tropical areas showing the lowest efficacy rates. Despite worldwide vaccination coverage, the impact of BCG on the steep decrease of tuberculosis incidence rates in the developed world seems therefore questionable and can rather be attributed to improved social, housing and nutritional conditions, better health care, surveillance and treatment systems. The last 15 years saw tremendous efforts to improve vaccination strategies against tuberculosis. Different paths of vaccine approaches were followed including genetically improved BCG strains, attenuated M. tuberculosis variants, recombinant viral vectors and subunit vaccine candidates combined with novel more potent adjuvants. With the first novel vaccine candidates being evaluated in clinical phases II and III and initial results chastening the expectations, a critical reassessment of all candidates is inevitable. Here, we assembled experts to review and assess the current status of novel anti-tuberculosis vaccine candidates, their efficacy and prospects for implementation as well as the pitfalls and possible measures for improvement.

Advances in Epithelial Ovarian Cancer: Model Systems, Microenvironmental Influences, Therapy, and Origins

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Book Series: Frontiers Research Topics ISSN: 16648714 ISBN: 9782889197699 Year: Pages: 176 DOI: 10.3389/978-2-88919-769-9 Language: English
Publisher: Frontiers Media SA
Subject: Oncology --- Medicine (General)
Added to DOAB on : 2016-04-07 11:22:02
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This eBook provides a compendium of the current state-of-the-art in research tools for, and understanding of, the critical research areas in epithelial ovarian cancer (EOC) with a strong emphasis on (HG-SOC). Research areas covered include therapy response and development, microenvironmental influences and the etiology and progression of EOC. Ten articles detail established and novel in vivo and in vitro model systems. These include primary and immortalized cell culture in 2D and 3D as well as genetically engineered, transgenic, spontaneous, syngeneic, classical xenograft and patient derived xenograft mouse models. The generation of genetically engineered mouse models of HG-SOC has been a major dilemma as models with the oncogenic aberrations common in the human malignancy do not accurately recapitulate HG-SOC. Conversely, commonly used HG-SOC cell lines have been found to not harbor the expected genetic changes. These issues as well as the rapid acceptance of patient derived xenograft models are reviewed. Five articles discuss different aspects of the tumor microenvironment including its role in therapy resistance, disease progression and metastasis. Mutation of BRCA1/2 continues to be the best defined risk factor for HG-SOC. Three articles discuss BRCA-loss in the context of disease development, targeted therapies and changes in preventative measures proposed for mutation carriers in light of the recent advances in knowledge regarding the origins of this malignancy. An image of HG-SOC with patchy BRCA1 expression is featured on the cover (image by VM Howell). A major clinical issue for patients with HG-SOC is the development of therapy resistance. Five articles focus on therapy resistance and different ways to overcome resistance. Overall, this eBook is an outstanding resource to aid researchers design their programs of research and determine the most appropriate and up-to-date EOC model systems to address their research questions.

Development and Application of Herbal Medicine from Marine Origin

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ISBN: 9783039212217 / 9783039212224 Year: Pages: 140 DOI: 10.3390/books978-3-03921-222-4 Language: eng
Publisher: MDPI - Multidisciplinary Digital Publishing Institute
Subject: Medicine (General)
Added to DOAB on : 2019-08-28 11:21:27
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Marine herbal medicine generally refers to the use of marine plants as original materials to develop crude drugs, or for other medical purposes. The term ‘marine plants’ usually denotes macroalgae grown between intertidal and subintertidal zones, including Chlorophyta, Phaeophyta, and Rhodophyta. Considerable progress has been made in the field of biomedical research into marine microalgae and microorganisms in the past decade. As the most important source of fundamental products in the world, marine plants have a very important role in biomedical research. Furthermore, worldwide studies have consistently demonstrated that many crude drugs derived from marine plants contain novel ingredients that may benefit health or can be used in the treatment of diseases; some have been developed into health foods, and some even into drugs. It is expected that there are many substances of marine plant origin that will have medical applications in terms of improving human health and are awaiting discovery.In this Special Issue, entitled “Development and Application of Herbal Medicine of Marine Origin”, we will provide a platform for researchers to publish biomedical studies on substances of marine plant origin. We welcome submissions from scientists and academics from across the world.

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