Invasion of Human Retinal Pigment Epithelial Cells by Porphyromonas gingivalis leading to Vacuolar/Cytosolic localization and Autophagy dysfunction In-Vitro

Sci Rep. 2020 May 4;10(1):7468. doi: 10.1038/s41598-020-64449-8.

Abstract

Recent epidemiological studies link Periodontal disease(PD) to age-related macular degeneration (AMD). We documented earlier that Porphyromonas gingivalis(Pg), keystone oral-pathobiont, causative of PD, efficiently invades human gingival epithelial and blood-dendritic cells. Here, we investigated the ability of dysbiotic Pg-strains to invade human-retinal pigment epithelial cells(ARPE-19), their survival, intracellular localization, and the pathological effects, as dysfunction of RPEs leads to AMD. We show that live, but not heat-killed Pg-strains adhere to and invade ARPEs. This involves early adhesion to ARPE cell membrane, internalization and localization of Pg within single-membrane vacuoles or cytosol, with some nuclear localization apparent. No degradation of Pg or localization inside double-membrane autophagosomes was evident, with dividing Pg suggesting a metabolically active state during invasion. We found significant downregulation of autophagy-related genes particularly, autophagosome complex. Antibiotic protection-based recovery assay further confirmed distinct processes of adhesion, invasion and amplification of Pg within ARPE cells. This is the first study to demonstrate invasion of human-RPEs, begin to characterize intracellular localization and survival of Pg within these cells. Collectively, invasion of RPE by Pg and its prolonged survival by autophagy evasion within these cells suggest a strong rationale for studying the link between oral infection and AMD pathogenesis in individuals with periodontitis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Autophagosomes* / metabolism
  • Autophagosomes* / microbiology
  • Autophagosomes* / ultrastructure
  • Autophagy*
  • Bacteroidaceae Infections* / metabolism
  • Bacteroidaceae Infections* / microbiology
  • Bacteroidaceae Infections* / pathology
  • Cell Line
  • Cytosol* / metabolism
  • Cytosol* / microbiology
  • Cytosol* / ultrastructure
  • Humans
  • Porphyromonas gingivalis* / metabolism
  • Porphyromonas gingivalis* / ultrastructure
  • Retinal Pigment Epithelium* / metabolism
  • Retinal Pigment Epithelium* / microbiology
  • Retinal Pigment Epithelium* / ultrastructure
  • Vacuoles* / microbiology
  • Vacuoles* / pathology
  • Vacuoles* / ultrastructure