Ju Young Jang1, Keum Jin Baek2, Youngnim Choi2, Suk Ji3. 1. Department of Periodontics, Institute of Oral Health Science, Ajou University School of Medicine, Suwon, South Korea. 2. Department of Oromaxillofacial Infection & Immunity, BK21 CLS, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, South Korea. 3. Department of Periodontics, Institute of Oral Health Science, Ajou University School of Medicine, Suwon, South Korea. Electronic address: sukji@aumc.ac.kr.
Abstract
OBJECTIVE: Bacterial invasion into host cells is a common strategy to escape the host immune system. Gingival fibroblasts (GFs) are the most predominant non-phagocytic cell type in gingival connective tissue. Therefore, invasion into GFs was thought to be the first strategy for the survival of Porphyromonas gingivalis. The present study compared the invasive ability of P. gingivalis into GFs with those of other red-complex and relatively less pathogenic bacterial strains, especially Fusobacterium nucleatum. MATERIALS AND METHODS: Invasive ability of bacterial strains into GFs was measured using a flow cytometric invasion assay at a multiplicity of infection of 1000. The effect of dual infection with F. nucleatum CCUG 37843T on P. gingivalis ATCC 49417 invasion was investigated. The invasive ability of F. nucleatum and P. gingivalis was confirmed using confocal microscopy. RESULTS: The invasive ability of red-complex bacteria was markedly lower than that of F. nucleatum or Campylobacter gracilis. The invasive ability of 4 types and 10 clinical strains of P. gingivalis was less than 6%, and that of F. nucleatum strains was greater than 45%. Confocal analysis revealed that the percentage of bacteria invading GFs in the cell-treated P. gingivalis and F. nucleatum were 0.0068% and 1.22%, respectively. Dual infection with F. nucleatum increased the invasive ability of P. gingivalis. CONCLUSION: The invasive capacities of P. gingivalis into GFs were comparatively lower than those of relatively less pathogenic bacteria. Invasion into GFs cannot be the first strategy for survival of P. gingivalis in gingival connective tissue.
OBJECTIVE: Bacterial invasion into host cells is a common strategy to escape the host immune system. Gingival fibroblasts (GFs) are the most predominant non-phagocytic cell type in gingival connective tissue. Therefore, invasion into GFs was thought to be the first strategy for the survival of Porphyromonas gingivalis. The present study compared the invasive ability of P. gingivalis into GFs with those of other red-complex and relatively less pathogenic bacterial strains, especially Fusobacterium nucleatum. MATERIALS AND METHODS: Invasive ability of bacterial strains into GFs was measured using a flow cytometric invasion assay at a multiplicity of infection of 1000. The effect of dual infection with F. nucleatumCCUG 37843T on P. gingivalis ATCC 49417 invasion was investigated. The invasive ability of F. nucleatum and P. gingivalis was confirmed using confocal microscopy. RESULTS: The invasive ability of red-complex bacteria was markedly lower than that of F. nucleatum or Campylobacter gracilis. The invasive ability of 4 types and 10 clinical strains of P. gingivalis was less than 6%, and that of F. nucleatum strains was greater than 45%. Confocal analysis revealed that the percentage of bacteria invading GFs in the cell-treated P. gingivalis and F. nucleatum were 0.0068% and 1.22%, respectively. Dual infection with F. nucleatum increased the invasive ability of P. gingivalis. CONCLUSION: The invasive capacities of P. gingivalis into GFs were comparatively lower than those of relatively less pathogenic bacteria. Invasion into GFs cannot be the first strategy for survival of P. gingivalis in gingival connective tissue.