Netosis

NETosis: Immunity, Pathogenesis and Therapeutics takes a focused approach to the clinical aspects of NETosis and drug development, bringing critical findings. Chapters introduce NETosis, consider mechanisms and antimicrobial strategies regulating NETosis, examine NETosis in neonates, explore the role of NETosis in autoimmunity, delve into NETosis and other diseases, and present therapeutic approaches for dysregulated NETosis. Since Brinkamm, et al, discovered an unrecognized neutrophil anti-microbial mechanism responsible for the extracellular killing of invading pathogens in 2004, the novel process in which nuclear chromatin de-condenses and DNA is ejected into the extra cellular environment, trapping and inactivating tissue pathogens has rapidly evolved. Presents an up-to-date and detailed analysis of NETosis Brings together critical findings on NETosis as a comparatively novel immune mechanism Focuses on the clinical aspects of NETosis that lead to drug development Covers the topic with a cogency and passion that is based on years of scientific research

NETosis is a unique form of cell death that is characterized by the release of decondensed chromatin and granular contents to the extracellular space. The initial observation of NETosis placed the process within the context of the innate immune response to infections. Neutrophils, the most numerous leukocytes that arrive quickly at the site of an infection, were the first cell type shown to undergo extracellular trap formation. However, subsequent studies showed that other granulocytes are also capable of releasing nuclear chromatin following stimulation. The extracellular chromatin acts to immobilize microbes and prevent their dispersal in the host. Bacterial breakdown products and inflammatory stimuli induce NETosis and the release of NETs requires enzyme activities. Histones in NET chromatin become modified by peptidylarginine deiminase 4 (PAD4) and cleaved at specific sites by proteases. NETs serve for attachment of bactericidal enzymes including myeloperoxidase, leukocyte proteases, and the cathelicidin LL-37. While the benefit of NETs in an infection appears clear, NETs also figure prominently at the center of various pathologic states. Therefore, it is important for NETs to be efficiently cleared; else digestive enzymes may gain access to tissues where inflammation takes place. Persistent NET exposure at sites of inflammation may lead to a further complication: NET antigens may provoke acquired immune responses and, over time, could initiate autoimmune reactions. Recent studies identified aberrant NET synthesis and/or clearance in inflammatory/autoimmune conditions such as systemic lupus erythematosus (SLE), psoriasis, ANCA-positive vasculitis, gout and Felty’s syndrome. In the case of SLE, for example, it appears that LL-37 exposed in the NETs may be a significant trigger of type I Interferon responses in this disease. Recent evidence also implicates aberrant NET formation in the development of endothelial damage, atherosclerosis and thrombosis. NETosis is thus of interest to researchers who investigate innate immune responses, host-pathogen interactions, chronic inflammatory disorders, cell and vascular biology, biochemistry, and autoimmunity. As we approach the 10-year-anniversary of the initial discovery of NETosis, it is useful and timely to review the so far identified mechanisms and pathways of NET formation, their role in bacterial and fungal defense and their putative importance as inducers of autoimmune responses. We look forward to a rich and rigorous discussion of these and related issues that benefit from interdisciplinary approaches, collaborations and exciting discoveries.

NETosis, a form of cell death that manifests by the release of decondensed chromatin to the extracellular space, provides valuable insights into mechanisms and consequences of cellular demise. Because extracellular chromatin can immobilize microbes, the extended nucleohistone network was called a neutrophil extracellular trap (NET), and the process of chromatin release was proposed to serve an innate immune defense function. Extracellular chromatin NETs were initially observed in studies of neutrophils and are most prominent in these types of granulocytes. Subsequent studies showed that other granulocytes and, in a limited way, other cells of the innate immune response may also release nuclear chromatin following certain kinds of stimulation. Variations of NETosis were noted with cells that remain temporarily motile after the release of chromatin. Numerous stimuli for NETosis were discovered, including bacterial breakdown products, inflammatory stimuli, particulate matter, certain crystals, immune complexes and activated thrombocytes. Fundamental explorations into the mechanisms of NETosis observed that neutrophil enzyme activity (PAD4, neutrophil elastase, proteinase 3 and myeloperoxidase) and signal transduction pathways contribute to the regulation of NETosis. Histones in NET chromatin become modified by peptidylarginine deiminase 4 (PAD4) and cleaved at specific sites by proteases, leading to extensive chromatin externalization. In addition, NETs serve for attachment of bactericidal enzymes including myeloperoxidase, leukocyte proteases, and the cathelicidin LL-37. NETs are decorated with proteases and may thus contribute to tissue destruction. However, the attachment of these enzymes to NET-associated supramolecular structures restricts systemic spread of the proteolytic activity. While the benefit of NETs in an infection appears obvious, NETs also participate as key protagonists in various pathologic states. Therefore, it is essential for NETs to be efficiently cleared; otherwise digestive enzymes may gain access to tissues where inflammation takes place. Persistent NET exposure at sites of inflammation may lead to a further complication: NET antigens may provoke acquired immune responses and, over time, could initiate autoimmune reactions, serve as antigen for nuclear autoantibodies and foster DNA immune complex-related inflammation. Neutrophil products and deiminated proteins comprise an important group of autoantigens in musculoskeletal disorders. Aberrant NET synthesis and/or clearance are often associated with inflammatory and autoimmune conditions. Recent evidence also implicates aberrant NET formation in the development of endothelial damage, atherosclerosis and thrombosis. Intravital microscopy provides evidence for conditions that induce NETosis in vivo. Furthermore, NETs can easily be detected in synovial fluid and tissue sections of patients with arthritis and gout. NETosis is thus of interest to researchers who investigate innate immune responses, host-pathogen interactions, chronic inflammatory disorders, cell and vascular biology, biochemistry, and autoimmunity. As we enter the second decade of research on NETosis, it is useful and timely to review the mechanisms and pathways of NET formation, their role in bacterial and fungal defense and their importance as inducers of autoimmune responses.

Inflammasome Biology: Fundamentals, Role in Disease States, and Therapeutic Opportunities is a complete reference on the role of inflammasomes in health and disease. Sections cover the different types of inflammasomes, including cellular signaling, structural and evolutive aspects, overview the role of inflammasomes in key diseases, microbial infections and human body systems conditions, cover the interplay between Inflammasomes and cell death processes, and discuss current therapeutic opportunities driven by inflammasome research, including targeting, blocking and inhibiting the development of inflammasomes through both synthetic and natural compounds. This book is the perfect reference for cell biologists, immunologists and research clinicians to understand the foundations of inflammasomes and explore the therapeutic opportunities they present. Pharma researchers may also find this reference invaluable in devising new approaches to developing anti-inflammatory drugs. Provides comprehensive coverage of the subject of inflammasome biology Authored by leading experts worldwide Provides biological insights that have both health implications and therapeutic potential

This book presents current understanding of the importance of modern immunology in the etiopathogenesis of human diseases and explores how this understanding is impacting on diagnosis, prognosis, treatment, and prophylaxis. As the core of modern immunology, the “danger/injury model” is introduced and addressed throughout the book. Volume I of the book describes the network of damage-associated molecular pattern molecules (DAMPs) and examines the central role of DAMPs in cellular stress responses and associated regulated cell death, the promotion and resolution of inflammation, the activation of innate lymphoid cells and unconventional T cells, the stimulation of adaptive immunity, and tissue repair. The significance of DAMPs in a wide range of human diseases will then be explored in Volume II of the book, with discussion of the implications of injury-induced innate immunity for present and future treatments. This book is written for professionals from all medical and paramedical disciplines who are interested in the introduction of innovative data from immunity and inflammation research into clinical practice. The readership will include practitioners and clinicians such as hematologists, rheumatologists, traumatologists, oncologists, intensive care anesthetists, endocrinologists such as diabetologists, psychiatrists, neurologists, pharmacists, and transplantologists.

Starting with basic principles, this reference and handbook discusses examples of the most advanced models of bacterial infection with regard to their value as paradigms to understand the molecular cross-talks between microbes and their host and tissue targets. It adopts a very forward-looking, advanced approach, placing special emphasis on the main global challenges facing scientists today, such as pathogenicity vs. commensalisms, infections in immunocompromised hosts and species specificity issues.