Lactobacilli Attenuate the Effect of Infection in Gingival Epithelial Cells

Probiotics may be considered as an additional strategy to achieve a balanced microbiome in periodontitis. However, the mechanisms underlying the use of probiotics in the prevention or control of periodontitis are still not fully elucidated. This study aimed to evaluate the effect of two commercially available strains of lactobacilli on gingival epithelial cells (GECs) challenged by . OBA-9 GECs were infected with strain JP2 at an MOI of 1:100 and/or co-infected with La5 (La5) or Lr32 (Lr32) at an MOI of 1:10 for 2 and 24 h. The number of adherent/internalized bacteria to GECs was determined by qPCR. Production of inflammatory mediators (CXCL-8, IL-1β, GM-CSF, and IL-10) by GECs was determined by ELISA, and the expression of genes encoding cell receptors and involved in apoptosis was determined by RT-qPCR. Apoptosis was also analyzed by Annexin V staining. There was a slight loss in OBA-9 cell viability after infection with or the tested probiotics after 2 h, which was magnified after 24-h co-infection. Adherence of to GECs was 1.8 × 10 (± 1.2 × 10) cells/well in the mono-infection but reduced to 1.2 × 10 (± 1.5 × 10) in the co-infection with Lr32 and to 6 × 10 (± 1 × 10) in the co-infection with La5 (p < 0.05). GECs mono-infected with produced CXCL-8, GM-CSF, and IL-1β, and the co-infection with both probiotic strains altered this profile. While the co-infection of with La5 resulted in reduced levels of all mediators, the co-infection with Lr32 promoted reduced levels of CXCL-8 and GM-CSF but increased the production of IL-1β. The probiotics upregulated the expression of and downregulated in cells co-infected with . induced the upregulation of was attenuated by La5 but increased by Lr32. Furthermore, the transcription of the anti-apoptotic gene was upregulated, whereas the pro-apoptotic was downregulated in cells co-infected with and the probiotics. Infection with induced apoptosis in GECs, whereas the co-infection with lactobacilli attenuated the apoptotic phenotype. Both tested lactobacilli may interfere in colonization of the oral cavity by reducing its ability to interact with gingival epithelial cells and modulating cells response. However, La5 properties suggest that this strain has a higher potential to control associated periodontitis than Lr32.