title: The development of giant phagocytes in long-term neutrophil cultures.
abstract: We tested the hypothesis that in long-term culture conditions, some neutrophils remain viable and participate in debris clearance, and autophagy is involved in their prolonged survival. Neutrophils, classified as professional phagocytes, have the shortest half-life among leukocytes and are constitutively committed to apoptosis. Apoptotic neutrophils are actively removed by Mφ/DCs. However, early and acute inflammatory infiltrates primarily consist of neutrophils. Recently, neutrophils were suggested to facilitate debris clearance at inflammatory sites when the Mφ/DC system is insufficient. Here, purified CD15(+)/CD66b(+)/CD63(+) neutrophils were followed up to 7 days in culture using light, time-lapse, and confocal microscopy. After 3 days in culture, Annexin-V(-)/LC3B(+) large vacuolated cells, engulfing cellular residues, were noted among apoptotic neutrophils and cell debris. Thereafter, these cells were vastly enlarged and exhibited a neutrophilic phenotype (CD15(+)/CD63(+)/MPO(+)/CD66b(+)), phagocytosis, and oxidative burst activity. They also expressed CD68 scavenger receptors and internalized oxLDL. But, unlike in fresh neutrophils or cultured monocytes, oxLDL treatment increased their ROS production. Additionally, these phagocytes contained LC3B-coated vacuoles and LC3B aggregates, indicating the activation of autophagy. An intensive LC3B accumulation was also noted during oxLDL internalization. Importantly, the inhibition of autophagy by 3-MA or BafA1 prevented their development. In conclusion, the internalization of neutrophil remnants may induce activation of autophagic mechanisms in some neutrophil subsets or precursors. This may lead to cell adaptation and survival, resulting in their transformation into long-lived Gφ and potentially suggesting their involvement in inflammatory/anti-inflammatory processes.
authors.affiliation: The Lloyd Rigler Sleep Apnea Research Laboratory, Unit of Anatomy and Cell Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Larissa
authors.initials: L
authors.lastname: Dyugovskaya
authors.affiliation: The Lloyd Rigler Sleep Apnea Research Laboratory, Unit of Anatomy and Cell Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Slava
authors.initials: S
authors.lastname: Berger
authors.affiliation: The Lloyd Rigler Sleep Apnea Research Laboratory, Unit of Anatomy and Cell Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: Andrey
authors.initials: A
authors.lastname: Polyakov
authors.affiliation: The Lloyd Rigler Sleep Apnea Research Laboratory, Unit of Anatomy and Cell Biology, The Ruth and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel lenal@tx.technion.ac.il.
authors.forename: Lena
authors.initials: L
authors.lastname: Lavie
mesh_terms: D000328:Adult; D001343:Autophagy / Q000276:immunology; D018929:Cell Culture Techniques; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D008077:Lipoproteins, LDL / Q000378:metabolism; D008297:Male; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000276:immunology; D009504:Neutrophils / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D010586:Phagocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D010587:Phagocytosis / Q000276:immunology; D010641:Phenotype; D017382:Reactive Oxygen Species / Q000378:metabolism; D055815:Young Adult
chemical_list: D008077:Lipoproteins, LDL; C502070:MAP1LC3B protein, human; D008869:Microtubule-Associated Proteins; D017382:Reactive Oxygen Species; C099252:oxidized low density lipoprotein
keywords: LC3B; LC3B inhibitors; apoptosis; autophagy; oxidized LDL; reactive oxygen species