Comprehensive analysis of transcriptional profiles in oral epithelial-like cells stimulated with oral probiotic Lactobacillus spp.

Objective: The mechanisms of action of probiotics can vary among species and among strains of a single species; thus, they can affect host cells in a complex manner. In the present study, Lactobacillus spp. were evaluated for their ability to adhere to gingival epithelial-like cells. Comprehensive analyses of transcriptional profiles of mouse gingival epithelial GE1 cells treated with L. rhamnosus L8020 were performed to assess the putative in vivo probiotic potential of this strain. Methods: Five Lactobacillus spp., isolated from the oral cavity, traditional Bulgarian yoghurt, and the feces of a healthy human, were each co-cultured with GE1 cells. Adhesion assays with serial dilution plating and DNA microarray analysis were performed to identify differentially expressed genes (DEGs) in GE1 cells grown in co-culture with L. rhamnosus L8020. Results: The oral isolates L. rhamnosus L8020, L. casei YU3, and L. paracasei YU4 demonstrated significantly greater adhesion compared with the non-oral isolates. In total, 536 genes in GE1 cells exhibited more than twofold upregulation or downregulation, compared with the 0 h timepoint, during co-culture with L. rhamnosus L8020. Gene ontology enrichment analysis revealed that DEGs were differentially enriched in a time-dependent manner. Early responses involved widespread changes in gene expression. Conclusions: This study reveals changes in expression of genes involved in the epithelial physical barrier and immune response in gingival epithelial-like cells co-cultured with L. rhamnosus L8020. Further investigations regarding the molecular mechanisms by which L. rhamnosus L8020 serves as a probiotic may provide evidence to support clinical use.