Probiotics alter the immune response of gingival epithelial cells challenged by Porphyromonas gingivalis

Abstract

Background and Objective Although previous studies revealed the potential use of probiotics in the control of periodontitis, little is known about their interactions with gingival epithelial cells (GECs). Since GECs comprise the first defense in the subgingival microenvironment, the aim of this study was to evaluate the effect of probiotic lactobacilli and bifidobacteria strains on OBA‐9 cells challenged with Porphyromonas gingivalis. Methods Immortalized human GECs (OBA‐9) were challenged with live P. gingivalis (strains W83 and ATCC33277) and co‐infected with one of 12 tested probiotic strains at a multiplicity of infection (MOI) of 1:1000 for 2 hours. Bacterial adhesion and invasion were determined by antibiotic exclusion analysis and CFU counting. OBA‐9 viability was assessed by MTT assay, and levels of inflammatory mediators (TNF‐α, IL‐1β, and CXCL8) in the supernatants were determined by ELISA. The expression of genes encoding Toll‐like receptors (TLR2, TLR4) was evaluated by RT‐qPCR. Results Both strains of P. gingivalis were able to adhere and invade OBA‐9 cells, with significant loss in cell viability, increase in the levels of TNF‐α and IL‐1β, and upregulation of TLR4. However, co‐infection with probiotics attenuated these effects in P. gingivalis challenged GECs. Most probiotics maintained OBA‐9 viability and reduced pathogens adhesion and invasion. Furthermore, probiotics were able to adhere to GECs, which was enhanced for most strains in the presence of P. gingivalis. The synthesis of IL‐1β and TNF‐α by P. gingivalis in challenged GECs was reduced in co‐culture with most of the tested probiotics, whereas the secretion of CXCL8 increased, and TLR4 was downregulated. Conclusion Probiotics can alter the interaction of GECs with P. gingivalis by modulating the pathogen's ability to adhere and invade these cells, as well as by regulating the innate immune response. Such properties are strain‐specific and may indicate the most efficient probiotics to control periodontitis.

Probiotics alter biofilm formation and the transcription of Porphyromonas gingivalis virulence-associated genes

“…Moreover, FIMA is associated with pathogen adhesion/invasion to epithelial cells [44] and it is recognition by host cells through TLR2 and TLR4 receptors with downstream activation of pro-inflammatory cytokines [45]. Thus, fimA down-regulation may explain our previous study that found a modulation of the immune response triggered in gingival epithelial cells followed by a reduction in the adhesion of P. gingivalis ATCC 33277 [9]. Curiously, all tested probiotics supernatants were able to down-regulate the expression of mfa1 in multi-species biofilm assays.…”

“…Virulence of P. gingivalis is mediated by an array of factors involved in several functions, such as attachment to host surfaces and other oral microorganisms, acquisition of nutrients, induction of a destructive inflammatory response and evasion of host response. Probiotics were not only able to decrease the abundance of P. gingivalis in multispecies biofilms but were also able to inhibit adhesion and invasion of P. gingivalis to GECs [9]. Once again, these activities were dependent on the P. gingivalis strain, since the tested lactobacilli were able to inhibit P. gingivalis W83 adhesion to but not the invasion of GECs, whereas both adhesion and invasion of ATCC 33277 were inhibited.…”

“…Our previous study [9] bacteria in GECs revealed that most studied genes were regulated by at least one probiotic, and the transcription profiles were probiotic-strain and P. gingivalis-strain specific (Figure 4a3,b3,c3,d3,e3,f3). L acidophilus LA5 showed prominent activity on VAF transcription, including the downregulation of the fimbriae encoding genes mfa1, in both strains of P. gingivalis, and fimA, in ATCC 33277 ( Figure 4a3); gingipains encoding genes kgp, rgpA, and the quorum sensing luxS in ATCC 33277 or W83 interacting with GECs (Figure 4).…”

“…The assays were performed according to our previous work [9]. Briefly, immortalized human gingival epithelial cells (OBA-9/GECs) were cultured in Keratinocyte-Serum Free Medium (KSFM) (GIBCO™, Life Technologies, Carlsbad, CA, USA) supplied with human recombinant epidermal growth factor.…”

“…We have previously shown that probiotic strains of the genera Lactobacillus and Bifidobacterium promote a reduction in P. gingivalis adhesion to and invasion of gingival epithelial cells, and alter the cell response to the pathogen [9]. These beneficial microorganisms may also directly exert an effect on certain pathogens by attenuating their virulence components [10], such as by impairing toxins production [11].…”