title: Enhancement of neutrophil autophagy by an IVIG preparation against multidrug-resistant bacteria as well as drug-sensitive strains.
abstract: Autophagy occurs in human neutrophils after the phagocytosis of multidrug-resistant bacteria and drug-sensitive strains, including Escherichia coli and Pseudomonas aeruginosa. The present study detected autophagy by immunoblot analysis of LC3B conversion, by confocal scanning microscopic examination of LC3B aggregate formation and by transmission electron microscopic examination of bacteria-containing autophagosomes. Patients with severe bacterial infections are often treated with IVIG alongside antimicrobial agents. Here, we showed that IVIG induced neutrophil-mediated phagocytosis of multidrug-resistant strains. Compared with untreated neutrophils, neutrophils exposed to IVIG showed increased levels of bacterial cell killing, phagocytosis, O(2)(-) release, MPO release, and NET formation. IVIG also increased autophagy in these cells. Inhibiting the late phase of autophagy (fusion of lysosomes with autophagosomes) with bafilomycin A1-reduced, neutrophil-mediated bactericidal activity. These findings indicate that autophagy plays a critical role in the bactericidal activity mediated by human neutrophils. Furthermore, the autophagosomes within the neutrophils contained bacteria only and their organelles only, or both bacteria and their organelles, a previously undocumented observation. Taken together, these results suggest that the contents of neutrophil autophagosomes may be derived from specific autophagic systems, which provide the neutrophil with an advantage. Thus, IVIG promotes the neutrophil-mediated killing of multidrug-resistant bacteria as well as drug-sensitive strains.
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Itoh
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Hidemasa
authors.initials: H
authors.lastname: Matsuo
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kitamura
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Sho
authors.initials: S
authors.lastname: Yamamoto
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Higuchi
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Hiromu
authors.initials: H
authors.lastname: Takematsu
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Kamikubo
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Tadakazu
authors.initials: T
authors.lastname: Kondo
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Kouhei
authors.initials: K
authors.lastname: Yamashita
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Masataka
authors.initials: M
authors.lastname: Sasada
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan.
authors.forename: Akifumi
authors.initials: A
authors.lastname: Takaori-Kondo
authors.affiliation: Departments of *Human Health Sciences and Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Department of Clinical Laboratory, Kyoto University Hospital, Kyoto, Japan; and Department of Hematology and Oncology, Shiga Medical Center for Adults, Shiga, Japan adachiso@kuhp.kyoto-u.ac.jp.
authors.forename: Souichi
authors.initials: S
authors.lastname: Adachi
mesh_terms: D001343:Autophagy; D001419:Bacteria / Q000187:drug effects*; D001770:Blood Bactericidal Activity; D024901:Drug Resistance, Multiple, Bacterial; D006801:Humans; D016756:Immunoglobulins, Intravenous / Q000494:pharmacology*; D018942:Macrolides / Q000494:pharmacology; D009504:Neutrophils / Q000187:drug effects* / Q000276:immunology; D009195:Peroxidase / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism
chemical_list: D016756:Immunoglobulins, Intravenous; D018942:Macrolides; D013481:Superoxides; C040929:bafilomycin A1; D009195:Peroxidase
keywords: NETs; bactericidal activity; phagocytosis; xenophagy