Table 1: Virulence factors of periodontopathogenic bacteria, and their effects on host cells.

Bacterial virulence factorEffect on host cellsReferences

Fimbriae, flagellaePromote bacterial colonization, adherence and invasion of host cells[37, 38]
Modulate inflammatory response

Lipoteichoic acids (LTAs)Mediate bacterial adhesion to human cells and teeth[3947]
Arrest growth and decrease mitosis in epithelial cells
Stimulate leukocytes, activate complement
Increase cytokine and inflammatory mediator production
Stimulate bone resorption

Lipopolysaccharides (LPSs)Increase epithelial cell permeability, penetrate gingival epithelium[39, 45, 4858]
Stimulate JE basal cell proliferation at high concentration (5000 μg/mL)
Stimulate gingival fibroblast proliferation at low concentration (<10 μg) and suppress at high concentration
Stimulate T-helper cell proliferation
Increase cytokine and inflammatory mediator production
Activate osteoclasts

Short chain fatty acids (SCFAs)Raise inflammatory response[5963]
Inhibit gingival epithelial cell and fibroblast proliferation

ProteinasesActivate host MMP:s, degrade extracellular matrix components, immunoglobulins and complement proteins
Promote apoptosis in gingival fibroblasts[64]
Induce human β-defensin-2 expression in gingival epithelial cells in vitro

Heat shock proteinsActivate epithelial cells and osteoclasts at low concentrations and cause cell death at high concentrations[65]

Cytolethal distending toxinUpregulate RANKL expression in T cells[66]

LeukotoxinCause apoptosis and necrosis of PMNs, T cells, natural killer cells[48]

CapsuleIncrease resistance to phagocytosis[48]

Ammonium, hydrogen sulphideToxic to cells, cause cell vacuolization, inhibit collagen formation[67, 68]