IADR Abstract Archives
The oral protozoan Entamoeba gingivalis causes oral inflammation and tissue destruction
Objectives: A metagenomics analysis showed a strongly increased frequency of the protozoan Entamoeba gingivalis (E.g) in inflamed periodontal pockets, where it contributed the second most abundant rRNA after human rRNA. This observation and the close biological relationship to Entamoeba histolytica, which causes inflammation and tissue destruction in the colon, raised our concern about a putative role of E.g in the pathogenesis of periodontitis.
Methods: E.g. frequency was determined in 138 patients and controls by polymerase chain reaction and microscopy. Histochemical staining visualized the presence of E.g in the oral mucosa. Quantitiative realtime PCR was performed to analyse the response of epithelial barrier mucin genes to E.g infection in gingival epithelial cells and of matrix metalloproteinases in gingival fibroblasts. The response of the proinflammatory cytokins IL1β and IL8 to E.g infection was tested in both cell types. The effect of contact of E.g to epithelial cells was analysed by quantification of cell proliferation. All effects were compared to infection with the oral bacterial pathogen Porphyromonas gingivalis (P.g.)
Results: In patients, E.g. had a frequency of 77% at inflamed and 22% at healthy periodontal sites. 16% of healthy oral cavities were colonized. Microscopy showed invasion into the inflamed or wounded gingival epithelium, where it moved and fed on host cells. Invasion correlated with abundant accumulation of neutrophils. In vitro infection of gingival epithelial cells with E.g but not with P.g. specifcally upregulated IL8 (1,900 fold, P=1.2x10-4 ) and Muc21 (7.7 fold, P=5x10-04). In fibroblasts, the collagenase MMP13 was upregulated (11.2 fold, P=5x10-4). Direct contact of E.g to gingival epithelial cells inhibited cell proliferation comparable to effects of P.g.
Conclusions: Invasion in inflamed periodontal sites, feeding on host cells in conjunction to the high frequency in the oral cavity and the known resistance to neutrophils, antimicrobial peptides and antibiotics, raise the awareness of E.g as a potential and underrated microbial driver of destructive periodontitis.
Methods: E.g. frequency was determined in 138 patients and controls by polymerase chain reaction and microscopy. Histochemical staining visualized the presence of E.g in the oral mucosa. Quantitiative realtime PCR was performed to analyse the response of epithelial barrier mucin genes to E.g infection in gingival epithelial cells and of matrix metalloproteinases in gingival fibroblasts. The response of the proinflammatory cytokins IL1β and IL8 to E.g infection was tested in both cell types. The effect of contact of E.g to epithelial cells was analysed by quantification of cell proliferation. All effects were compared to infection with the oral bacterial pathogen Porphyromonas gingivalis (P.g.)
Results: In patients, E.g. had a frequency of 77% at inflamed and 22% at healthy periodontal sites. 16% of healthy oral cavities were colonized. Microscopy showed invasion into the inflamed or wounded gingival epithelium, where it moved and fed on host cells. Invasion correlated with abundant accumulation of neutrophils. In vitro infection of gingival epithelial cells with E.g but not with P.g. specifcally upregulated IL8 (1,900 fold, P=1.2x10-4 ) and Muc21 (7.7 fold, P=5x10-04). In fibroblasts, the collagenase MMP13 was upregulated (11.2 fold, P=5x10-4). Direct contact of E.g to gingival epithelial cells inhibited cell proliferation comparable to effects of P.g.
Conclusions: Invasion in inflamed periodontal sites, feeding on host cells in conjunction to the high frequency in the oral cavity and the known resistance to neutrophils, antimicrobial peptides and antibiotics, raise the awareness of E.g as a potential and underrated microbial driver of destructive periodontitis.