title: Streptococcus suisSerotype 2 Biofilms Inhibit the Formation of Neutrophil Extracellular Traps.
abstract: Invasive infections caused byStreptococcus suisserotype 2 (SS2) has emerged as a clinical problem in recent years. Neutrophil extracellular traps (NETs) are an important mechanism for the trapping and killing of pathogens that are resistant to phagocytosis. Biofilm formation can protect bacteria from being killed by phagocytes. Until now, there have only been a few studies that focused on the interactions between bacterial biofilms and NETs. SS2 in both a biofilm state and a planktonic cell state were incubated with phagocytes and NETs, and bacterial survival was assessed. DNase I and cytochalasin B were used to degrade NET DNA or suppress phagocytosis, respectively. Extracellular DNA was stained with impermeable fluorescent dye to quantify NET formation. Biofilm formation increased up to 6-fold in the presence of neutrophils, and biofilms were identified in murine tissue. Both planktonic and biofilm cells induced neutrophils chemotaxis to the infection site, with neutrophils increasing by 85.1 and 73.8%, respectively. The bacteria in biofilms were not phagocytized. The bactericidal efficacy of NETs on the biofilms and planktonic cells were equal; however, the biofilm extracellular matrix can inhibit NET release. Although biofilms inhibit NETs release, NETs appear to be an important mechanism to eliminate SS2 biofilms. This knowledge advances the understanding of biofilms and may aid in the development of treatments for persistent infections with a biofilm component.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Ma
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China; College of Life Science, Luoyang Normal UniversityLuoyang, China.
authors.forename: Li
authors.initials: L
authors.lastname: Yi
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Ningwei
authors.initials: N
authors.lastname: Yu
authors.affiliation: National Center of Meat Quality and Safety Control, Nanjing Agriculture University Nanjing, China.
authors.forename: Guangyu
authors.initials: G
authors.lastname: Wang
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Zhe
authors.initials: Z
authors.lastname: Ma
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University Nanjing, China.
authors.forename: Huixing
authors.initials: H
authors.lastname: Lin
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural UniversityNanjing, China; Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Infectious Diseases and ZoonosesYangzhou, China.
authors.forename: Hongjie
authors.initials: H
authors.lastname: Fan
mesh_terms: D000818:Animals; D018441:Biofilms / Q000254:growth & development*; D002478:Cells, Cultured; D065206:Extracellular Traps / Q000378:metabolism*; D054884:Host-Pathogen Interactions; D008264:Macrophages / Q000276:immunology / Q000382:microbiology; D051379:Mice; D050296:Microbial Viability; D009504:Neutrophils / Q000276:immunology* / Q000382:microbiology; D010587:Phagocytosis; D065288:Serogroup; D017011:Streptococcus suis / Q000276:immunology* / Q000502:physiology*
keywords: NETs; bacterial biofilm; clinical therapy; streptococcus toxic shock-like syndrome; zoonosis