The immune response of oral epithelial cells induced by single-species and complex naturally formed biofilms.
BACKGROUND
In the oral cavity, the surfaces are constantly exposed to a complex variety of microorganisms organized in biofilms. As part of a sophisticated local immune response, gingival epithelial cells (GECs) express antimicrobial peptides, such as human beta-defensin-2 (hBD-2), ribonuclease 7 (RNAase-7), and psoriasin (PSO), and pro-inflammatory mediators, such as interleukin-8 (IL-8) and 5-lipoxygenase (5-LO). The aim of the present study was to test whether GECs show a differential immune response to single-species biofilms compared with multi-species biofilms.


METHODS
GECs were cultured from biopsies derived from three different healthy donors (n = 3). To obtain naturally formed biofilm (NFB), polymer disks were attached to prostheses and carried intraorally for 12, 24, 36, and 48 h. In addition, single-species biofilms (SSB; Streptococcus mutans and Streptococcus mitis) were cultured on polymer disks in vitro (12, 24, 36, and 48 h). The messenger RNA (mRNA) expression of hBD-2, RNAase-7, PSO, IL-8, 5-LO, and glycerylaldehyde-3-phosphate dehydrogenase was analysed using semi-quantitative reverse transcription-polymerase chain reaction.


RESULTS
In GECs, the hBD-2 mRNA expression was significantly upregulated in response to S. mitis-biofilm stimulation compared with S. mutans-biofilm stimulation (P < 0.0001). In contrast, the RNAase-7 mRNA expression was significantly higher in GECs when responding to both S. mutans biofilms and naturally formed biofilms compared with S. mitis biofilms (P < 0.0001 and P < 0.001, respectively). The IL-8 and 5-LO mRNA was significantly upregulated in response to S. mutans biofilms (P < 0.0001 and P = 0.0002, respectively).


CONCLUSIONS
This in vitro study found biofilm-dependent expression of antimicrobial peptides and inflammatory mediators in GECs.
Eberhard
J
J
Department of Preventive Dentistry, Periodontology and Cariology, University Hospital Göttingen, Robert-Koch-Str. 40, Göttingen 37075, Germany. joerg.eberhard@gmx.net
Pietschmann
R
R
Falk
W
W
Jepsen
S
S
Dommisch
H
H
D023181:Antimicrobial Cationic Peptides / Q000096:biosynthesis*; D001094:Arachidonate 5-Lipoxygenase / Q000096:biosynthesis; D018441:Biofilms / Q000254:growth & development*; D002135:Calcium-Binding Proteins / Q000096:biosynthesis; D002478:Cells, Cultured; D015169:Colony Count, Microbial; D004847:Epithelial Cells / Q000276:immunology*; D015870:Gene Expression; D005881:Gingiva / Q000276:immunology*; D006801:Humans; D018836:Inflammation Mediators / Q000378:metabolism*; D016209:Interleukin-8 / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D012260:Ribonucleases / Q000096:biosynthesis; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; D034361:Streptococcus mitis / Q000276:immunology; D013295:Streptococcus mutans / Q000276:immunology; D023083:beta-Defensins / Q000096:biosynthesis
D023181:Antimicrobial Cationic Peptides; D002135:Calcium-Binding Proteins; D018836:Inflammation Mediators; D016209:Interleukin-8; D012333:RNA, Messenger; D000075023:S100 Calcium Binding Protein A7; D009418:S100 Proteins; C089242:S100A7 protein, human; D023083:beta-Defensins; D001094:Arachidonate 5-Lipoxygenase; D012260:Ribonucleases; C470000:Ribonuclease 7