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The role of phagocytosis, oxidative burst and neutrophil extracellular traps in the interaction between neutrophils and the periodontal pathogen Porphyromonas gingivalis
Author(s) -
Jayaprakash K.,
Demirel I.,
Khalaf H.,
Bengtsson T.
Publication year - 2015
Publication title -
molecular oral microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.18
H-Index - 77
eISSN - 2041-1014
pISSN - 2041-1006
DOI - 10.1111/omi.12099
Subject(s) - porphyromonas gingivalis , phagocytosis , neutrophil extracellular traps , microbiology and biotechnology , respiratory burst , chemistry , extracellular , streptococcus gordonii , innate immune system , reactive oxygen species , biology , inflammation , bacteria , immunology , biochemistry , receptor , streptococcaceae , genetics , antibiotics
Summary Neutrophils are regarded as the sentinel cells of innate immunity and are found in abundance within the gingival crevice. Discovery of neutrophil extracellular traps ( NET s) within the gingival pockets prompted us to probe the nature of the interactions of neutrophils with the prominent periopathogen Porphyromonas gingivalis . Some of the noted virulence factors of this Gram‐negative anaerobe are gingipains: arginine gingipains (RgpA/B) and lysine gingipain (Kgp). The aim of this study was to evaluate the role of gingipains in phagocytosis, formation of reactive oxygen species, NET s and CXCL 8 modulation by using wild‐type strains and isogenic gingipain mutants. Confocal imaging showed that gingipain mutants K1A (Kgp) and E8 (RgpA/B) induced extracellular traps in neutrophils, whereas ATCC 33277 and W50 were phagocytosed. The viability of both ATCC 33277 and W50 dwindled as the result of phagocytosis and could be salvaged by cytochalasin D, and the bacteria released high levels of lipopolysaccharide in the culture supernatant. Porphyromonas gingivalis induced reactive oxygen species and CXCL 8 with the most prominent effect being that of the wild‐type strain ATCC 33277, whereas the other wild‐type strain W50 was less effective. Quantitative real‐time polymerase chain reaction revealed a significant CXCL 8 expression by E8. All the tested P. gingivalis strains increased cytosolic free calcium. In conclusion, phagocytosis is the primary neutrophil response to P. gingivalis , although NET s could play an accessory role in infection control. Although gingipains do not seem to directly regulate phagocytosis, NET s or oxidative burst in neutrophils, their proteolytic properties could modulate the subsequent outcomes such as nutrition acquisition and survival by the bacteria.