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Clearance of apoptotic cells

Xu Chen, Stefan Gustafsson, Thomas Whitington, Yan Borné, Erik Lorentzen, Jitong Sun, Peter Almgren, Jun Su, Robert Karlsson, Jie Song, Yi Lu, Yiqiang Zhan, Sara Hägg, Per Svensson, Karin E Smedby, Susan L Slager, Erik Ingelsson, Cecilia M Lindgren, Andrew P Morris, Olle Melander, Thomas Karlsson, Ulf de Faire, Kenneth Caidahl, Gunnar Engström, Lars Lind, Mikael C I Karlsson, Nancy L Pedersen, Johan Frostegård, Patrik K E Magnusson
Phosphorylcholine (PC) is an epitope on oxidized low-density lipoprotein (oxLDL), apoptotic cells and several pathogens like Streptococcus pneumoniae. Immunoglobulin M against PC (IgM anti-PC) has the ability to inhibit uptake of oxLDL by macrophages and increase clearance of apoptotic cells. From our genome-wide association studies (GWAS) in four European-ancestry cohorts, six SNPs in 11q24.1 were discovered (in 3002 individuals) and replicated (in 646 individuals) to be associated with serum level of IgM anti-PC (the leading SNP rs35923643-G, combined beta=0...
March 14, 2018: Human Molecular Genetics
Delphine Lumbroso, Soaad Soboh, Avi Maimon, Sagie Schif-Zuck, Amiram Ariel, Tal Burstyn-Cohen
The complete resolution of inflammation requires the uptake of apoptotic polymorphonuclear cells (PMN) by local macrophages (efferocytosis) and the consequent reprogramming of the engulfing phagocytes to reparative and pro-resolving phenotypes. The tyrosine kinase receptors TYRO3, AXL, and MERTK (collectively named TAM) are fundamental mediators in regulating inflammatory responses and efferocytosis. Protein S (PROS1) is a ligand for all TAM receptors that mediates various aspects of their activity. However, the involvement of PROS1 in the resolution of inflammation is incompletely understood...
2018: Frontiers in Immunology
Liliana L Cubas-Gaona, Elisabet Diaz-Beneitez, Marina Ciscar, José F Rodríguez, Dolores Rodríguez
Infectious bursal disease virus (IBDV) belongs to the Birnaviridae family and is the etiological agent of a highly contagious and immunosuppressive disease (IBD) that affects domestic chickens ( Gallus gallus ). IBD or Gumboro disease leads to high morbidity and mortality of infected animals, and is responsible for major economic losses to the poultry industry world-wide. IBD is characterized by a massive loss of IgM-bearing B lymphocytes and the destruction of the bursa of Fabricius. The molecular bases of the IBDV pathogenicity are still poorly understood, nonetheless, an exacerbated cytokine immune response and B cell depletion due to apoptosis are considered main factors contributing to the severity of the disease...
March 14, 2018: Journal of Virology
Seungyeop Lee, Si-On Lee, Gyu-Lee Kim, Dong-Kwon Rhee
AIMS: Streptococcus pneumoniae infection in acute bacterial meningitis can lead to widespread brain damage and mortality. Inflammatory responses by immune cells in the brain are thought to determine the degree of brain injury. Yet, the mechanisms underlying host responses to pneumococcal meningitis are largely unknown. To explore host responses as a potential therapeutic target for preventing brain injury after pneumococcal meningitis. METHODS: We evaluated signaling mechanisms that minimize neuronal damage caused by pneumococcal infection; specifically, we assessed pathways related to neuronal survival after enhancing estrogen receptor-β (ER-β) expression using a natural therapeutic substance known as ginsenoside Rb1 and Rg3 enhanced ginseng...
March 9, 2018: CNS Neuroscience & Therapeutics
Manon Viaud, Stoyan Ivanov, Nemanja Vujic, Madalina Duta-Mare, Lazaro-Emilio Aira, Thibault Barouillet, Elsa Garcia, François Orange, Isabelle Dugail, Isabelle Hainault, Christian Stehlik, Sandrine Marchetti, Laurent Boyer, Rodolphe Guinamard, Fabienne Foufelle, Andrea E Bochem, Kees G Hovingh, Edward B Thorp, Emmanuel L Gautier, Dagmar Kratky, Paul A Da Silva-Jardine, Laurent Yvan-Charvet
<u>Rationale:</u> Macrophages face a substantial amount of cholesterol following the ingestion of apoptotic cells and the lysosomal acid lipase (LIPA) has a major role in hydrolyzing cholesteryl esters in the endocytic compartment. <u>Objective:</u> Here, we directly investigated the role of LIPA-mediated clearance of apoptotic cells both in vitro and in vivo. <u>Methods and Results:</u> We show that LIPA inhibition causes a defective efferocytic response due to impaired generation of 25-OHC and 27-OHC...
March 9, 2018: Circulation Research
Reut Hilu-Dadia, Ketty Hakim-Mishnaevski, Flonia Levy-Adam, Estee Kurant
Development of the central nervous system involves elimination of superfluous neurons through apoptosis and subsequent phagocytosis. In Drosophila, this occurs mainly during three developmental stages: embryogenesis, metamorphosis and emerging adult. Two transmembrane glial phagocytic receptors, SIMU (homolog of the mammalian Stabilin-2) and Draper (homolog of the mammalian MEGF10 and Jedi), mediate glial phagocytosis of apoptotic neurons during embryogenesis. However, less is known about the removal of apoptotic neurons during later stages of development...
March 9, 2018: Glia
Angelo A Manfredi, Giuseppe A Ramirez, Patrizia Rovere-Querini, Norma Maugeri
Neutrophils recognize particulate substrates of microbial or endogenous origin and react by sequestering the cargo via phagocytosis or by releasing neutrophil extracellular traps (NETs) outside the cell, thus modifying and alerting the environment and bystander leukocytes. The signals that determine the choice between phagocytosis and the generation of NETs are still poorly characterized. Neutrophils that had phagocytosed bulky particulate substrates, such as apoptotic cells and activated platelets, appear to be "poised" in an unresponsive state...
2018: Frontiers in Immunology
Silvia Rodriguez-Fernandez, Irma Pujol-Autonell, Ferran Brianso, David Perna-Barrull, Mary Cano-Sarabia, Sonia Garcia-Jimeno, Adrian Villalba, Alex Sanchez, Eva Aguilera, Federico Vazquez, Joan Verdaguer, Daniel Maspoch, Marta Vives-Pi
Type 1 diabetes (T1D) is a metabolic disease caused by the autoimmune destruction of insulin-producing β-cells. With its incidence increasing worldwide, to find a safe approach to permanently cease autoimmunity and allow β-cell recovery has become vital. Relying on the inherent ability of apoptotic cells to induce immunological tolerance, we demonstrated that liposomes mimicking apoptotic β-cells arrested autoimmunity to β-cells and prevented experimental T1D through tolerogenic dendritic cell (DC) generation...
2018: Frontiers in Immunology
Megan N Michalski, Anna L Seydel, Erica M Siismets, Laura E Zweifler, Amy J Koh, Benjamin P Sinder, J Ignacio Aguirre, Kamran Atabai, Hernan Roca, Laurie K McCauley
A prolonged increase in proinflammatory cytokines is associated with osteoporotic and autoimmune bone loss and, conversely, anti-inflammatory pathways are associated with protection against bone loss. Milk fat globule-epidermal growth factor (MFG-E)-8 is a glycoprotein that is proresolving, regulates apoptotic cell clearance, and has been linked to autoimmune disease and skeletal homeostasis. The role of MFG-E8 in the young vs. adult skeleton was determined in mice deficient in MFG-E8 (KO). In vivo, trabecular bone was similar in MFG-E8KO and wild-type (WT) mice at 6 and 16 wk, whereas 22 wk adult MFG-E8KO mice displayed significantly reduced trabecular BV/TV...
February 22, 2018: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Antoni Domagala, Joanna Stachura, Magdalena Gabrysiak, Angelika Muchowicz, Radoslaw Zagozdzon, Jakub Golab, Malgorzata Firczuk
BACKGROUND: Accumulating evidence suggest that autophagy plays a pivotal role in various anticancer therapies, including photodynamic therapy (PDT), acting as a pro-death or pro-survival mechanism in a context-dependent manner. Therefore, we aimed to determine the role of autophagy in Photofrin-based PDT. METHODS: In vitro cytotoxic/cytostatic effects of PDT were evaluated with crystal violet cell viability assay. Autophagy induction was analyzed by immunoblotting and immunofluorescence using anti-LC3 antibody...
February 20, 2018: BMC Cancer
Kristen K Penberthy, Jeffrey J Lysiak, Kodi S Ravichandran
Specialized phagocytes are a newly appreciated classification of phagocyte that currently encompasses Sertoli cells (SCs) of the testes and the retinal pigment epithelial cells (RPE) of the retina. While these cells support very different tissues, they have a striking degree of similarity both as phagocytes and in ways that go beyond cell clearance. The clearance of apoptotic germ cells, cell debris, and used photoreceptor outer segments are critical functions of these cells, and the unique nature of their clearance events make specialized phagocytes uniquely suited for studying the larger implications of cell clearance in vivo...
February 14, 2018: Trends in Cell Biology
Siamon Gordon, Annette Plüddemann
As the body continues to grow and age, it becomes essential to maintain a balance between living and dying cells. Macrophages and dendritic cells play a central role in discriminating among viable, apoptotic, and necrotic cells, as selective and efficient phagocytes, without inducing inappropriate inflammation or immune responses. A great deal has been learnt concerning clearance receptors for modified and non-self-ligands on potential targets, mediating their eventual uptake, disposal, and replacement. In this essay, we assess current understanding of the phagocytic recognition of apoptotic cells within their tissue environment; we conclude that efferocytosis constitutes a more complex process than simply removal of corpses, with regulatory interactions between the target and effector cells, which determine the outcome of this homeostatic process...
2018: Frontiers in Immunology
Jennifer M Felton, Christopher D Lucas, David A Dorward, Rodger Duffin, Tiina Kipari, Sonja Vermeren, Calum T Robb, Kenneth G MacLeod, Bryan Serrels, Jürgen Schwarze, Christopher Haslett, Ian Dransfield, Adriano G Rossi
BACKGROUND: Eosinophils play a central role in the propagation of allergic diseases including asthma. Both recruitment and retention of eosinophils regulate pulmonary eosinophilia but the question of whether alterations in apoptotic cell clearance by phagocytes directly contributes to resolution of allergic airway inflammation remains unexplored. OBJECTIVES: In this study we investigated the role of the receptor tyrosine kinase Mer in mediating apoptotic eosinophil clearance and allergic airway inflammation resolution in vivo in order to establish whether apoptotic cell clearance directly impacts upon the resolution of allergic airway inflammation...
February 8, 2018: Journal of Allergy and Clinical Immunology
Scott P Davies, Gary M Reynolds, Zania Stamataki
Toxic substances and microbial or food-derived antigens continuously challenge the liver, which is tasked with their safe neutralization. This vital organ is also important for the removal of apoptotic immune cells during inflammation and has been previously described as a "graveyard" for dying lymphocytes. The clearance of apoptotic and necrotic cells is known as efferocytosis and is a critical liver function to maintain tissue homeostasis. Much of the research into this form of immunological control has focused on Kupffer cells, the liver-resident macrophages...
2018: Frontiers in Immunology
Marianne A Bryan, Daniela Giordano, Kevin E Draves, Richard Green, Michael Gale, Edward A Clark
Although the spleen is a major site for West Nile virus (WNV) replication and spread, relatively little is known about which innate cells in the spleen replicate WNV, control viral dissemination, and/or prime innate and adaptive immune responses. Here we tested if splenic macrophages (MΦs) were necessary for control of WNV infection. We selectively depleted splenic MΦs, but not draining lymph node MΦs, by injecting mice intravenously with clodronate liposomes several days prior to infecting them with WNV...
2018: PloS One
Fan Mao, Yue Lin, Zhiying He, Jun Li, Zhiming Xiang, Yang Zhang, Ziniu Yu
Cystatins are a large family of the proteins that function as reversible and tight-binding inhibitors of cysteine proteases, which consequently regulate multiple physiological activities including apoptosis and innate immunity. In the present study, we cloned a gene from Crassostrea gigas encoding cystatin, which is related to cystatin A superfamily. CgCytA was comprised of a cystatin-like domain with two conserved glycine residues (GG) near the N-terminal and a highly conserved glutamine-valine-glycine (Q-X-V-X-G) motif in the form of QVVAG loop...
January 30, 2018: Fish & Shellfish Immunology
Shigekazu Nagata
The human body generates 10-100 billion cells every day, and the same number of cells die to maintain homeostasis in our body. Cells infected by bacteria or viruses also die. The cell death that occurs under physiological conditions mainly proceeds by apoptosis, which is a noninflammatory, or silent, process, while pathogen infection induces necroptosis or pyroptosis, which activates the immune system and causes inflammation. Dead cells generated by apoptosis are quickly engulfed by macrophages for degradation...
February 5, 2018: Annual Review of Immunology
M H Madeira, K Rashid, A F Ambrósio, A R Santiago, T Langmann
Age-related macular degeneration (AMD) is characterized by pathological changes in the retinal pigment epithelium (RPE) and loss of photoreceptors. Growing evidence has demonstrated that reactive microglial cells trigger RPE dysfunction and loss of photoreceptors, and inflammasome pathways and complement activation contribute to AMD pathogenesis. We and others have previously shown that adenosine A2A receptor (A2AR) blockade prevents microglia-mediated neuroinflammatory processes and mediates protection to the retina...
February 2, 2018: Scientific Reports
Mario Songane, Mostafa Khair, Maya Saleh
The binary classification of mammalian caspases as either apoptotic or inflammatory is now obsolete. Emerging data indicate that all mammalian caspases are intricately involved in the regulation of inflammation and immunity. They participate in embryonic and adult tissue homeostasis, control leukocyte differentiation, activation and effector functions, and mediate innate and adaptive immunity signaling. Caspases also promote host resistance by regulating anti-oxidant defense and pathogen clearance through regulation of phagosomal maturation, actin dynamics and phagosome-lysosome fusion...
January 20, 2018: Seminars in Cell & Developmental Biology
Mandy O J Grootaert, Manon Moulis, Lynn Roth, Wim Martinet, Cécile Vindis, Martin R Bennett, Guido R Y De Meyer
In the present review, we describe the causes and consequences of loss of vascular smooth muscle cells (VSMCs) or their function in advanced atherosclerotic plaques, and discuss possible mechanisms such as cell death or senescence, and induction of autophagy to promote cell survival. We also highlight the potential use of pharmacological modulators of these processes to limit plaque progression and/or improve plaque stability. VSMCs play a pivotal role in atherogenesis. Loss of VSMCs via initiation of cell death leads to fibrous cap thinning and promotes necrotic core formation and calcification...
January 18, 2018: Cardiovascular Research
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