title: Filifactor alocis Promotes Neutrophil Degranulation and Chemotactic Activity.
abstract: Filifactor alocis is a recently recognized periodontal pathogen; however, little is known regarding its interactions with the immune system. As the first-responder phagocytic cells, neutrophils are recruited in large numbers to the periodontal pocket, where they play a crucial role in the innate defense of the periodontium. Thus, in order to colonize, successful periodontal pathogens must devise means to interfere with neutrophil chemotaxis and activation. In this study, we assessed major neutrophil functions, including degranulation and cell migration, associated with the p38 mitogen-activated protein kinase (MAPK) signaling pathway upon challenge with F. alocis. Under conditions lacking a chemotactic gradient, F. alocis-challenged neutrophils had increased migration compared to uninfected cells, indicating that F. alocis increases chemokinesis in human neutrophils. In addition, neutrophil chemotaxis induced by interleukin-8 was significantly enhanced when cells were challenged with F. alocis, compared to noninfected cells. Similar to live bacteria, heat-killed F. alocis induced both random and directed migration of human neutrophils. The interaction of F. alocis with Toll-like receptor 2 induced granule exocytosis along with a transient ERK1/2 and sustained p38 MAPK activation. Moreover, F. alocis-induced secretory vesicle and specific granule exocytosis were p38 MAPK dependent. Blocking neutrophil degranulation with TAT-SNAP23 fusion protein significantly reduced the chemotactic and random migration induced by F. alocis Therefore, we propose that induction of random migration by F. alocis will prolong neutrophil traffic time in the gingival tissue, and subsequent degranulation will contribute to tissue damage.
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Cortney L
authors.initials: CL
authors.lastname: Armstrong
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Irina
authors.initials: I
authors.lastname: Miralda
authors.affiliation: Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Adam C
authors.initials: AC
authors.lastname: Neff
authors.affiliation: Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Shifu
authors.initials: S
authors.lastname: Tian
authors.affiliation: Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Aruna
authors.initials: A
authors.lastname: Vashishta
authors.affiliation: Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Lisandra
authors.initials: L
authors.lastname: Perez
authors.affiliation: Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Junyi
authors.initials: J
authors.lastname: Le
authors.affiliation: Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, Kentucky, USA rich.lamont@louisville.edu silvia.uriarte@louisville.edu.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Lamont
authors.affiliation: Department of Microbiology and Immunology, School of Medicine, University of Louisville, Louisville, Kentucky, USA rich.lamont@louisville.edu silvia.uriarte@louisville.edu.|Department of Medicine, School of Medicine, University of Louisville, Louisville, Kentucky, USA.|Department of Oral Immunology and Infectious Diseases, School of Dentistry, University of Louisville, Louisville, Kentucky, USA.
authors.forename: Silvia M
authors.initials: SM
authors.lastname: Uriarte
mesh_terms: D015550:Cell Degranulation / Q000502:physiology*; D002465:Cell Movement; D002633:Chemotaxis / Q000502:physiology*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000378:metabolism; D000068536:Bacillota / Q000502:physiology*; D005786:Gene Expression Regulation; D015696:Gene Products, tat; D006801:Humans; D009504:Neutrophils / Q000502:physiology*; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D015696:Gene Products, tat; D011993:Recombinant Fusion Proteins; D050600:SNARE Proteins; C582513:TAT-SNAP-23 fusion protein; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases