title: Escherichia coli and Candida albicans induced macrophage extracellular trap-like structures with limited microbicidal activity.
abstract: The formation of extracellular traps (ETs) has recently been recognized as a novel defense mechanism in several types of innate immune cells. It has been suggested that these structures are toxic to microbes and contribute significantly to killing several pathogens. However, the role of ETs formed by macrophages (METs) in defense against microbes remains little known. In this study, we demonstrated that a subset of murine J774A.1 macrophage cell line (8% to 17%) and peritoneal macrophages (8.5% to 15%) form METs-like structures (METs-LS) in response to Escherichia coli and Candida albicans challenge. We found only a portion of murine METs-LS, which are released by dying macrophages, showed detectable killing effects on trapped E. coli but not C. albicans. Fluorescence and scanning electron microscopy analyses revealed that, in vitro, both microorganisms were entrapped in J774A.1 METs-LS composed of DNA and microbicidal proteins such as histone, myeloperoxidase and lysozyme. DNA components of both nucleus and mitochondrion origins were detectable in these structures. Additionally, METs-LS formation occurred independently of ROS produced by NADPH oxidase, and this process did not result in cell lysis. In summary, our results emphasized that microbes induced METs-LS in murine macrophage cells and that the microbicidal activity of these METs-LS differs greatly. We propose the function of METs-LS is to contain invading microbes at the infection site, thereby preventing the systemic diffusion of them, rather than significantly killing them.
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Pan
authors.initials: P
authors.lastname: Liu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Xiuping
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Chengshui
authors.initials: C
authors.lastname: Liao
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Xiaolei
authors.initials: X
authors.lastname: Liu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Du
authors.affiliation: Mucosal Immunology Laboratory, Pediatric Gastroenterology Unit, Massachusetts General Hospital East, Charlestown, Massachusetts, United States of America.
authors.forename: Haining
authors.initials: H
authors.lastname: Shi
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Xuelin
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Bai
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Peng
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Yu
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Key Laboratory for Zoonosis Research, Ministry of Education, Institute of Zoonosis, Jilin University, Changchun, China ; Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.
authors.forename: Mingyuan
authors.initials: M
authors.lastname: Liu
mesh_terms: D000818:Animals; D002176:Candida albicans / Q000502:physiology*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000378:metabolism; D004926:Escherichia coli / Q000502:physiology*; D005110:Extracellular Space / Q000382:microbiology*; D008264:Macrophages / Q000166:cytology* / Q000382:microbiology*; D051379:Mice; D010587:Phagocytosis; D013045:Species Specificity
chemical_list: D004272:DNA, Mitochondrial