Effects of potential probiotics on the expression of cytokines and human β-defensins in human gingival epithelial cells and in vivo efficacy in a dog model

The aims of this study were to examine the effects of probiotic strains on the expression of cytokines and human β-defensins-2-4 in human gingival epithelial cells and to investigate the in vivo efficacy of probiotics in a dog model.Selected probiotics, Lacticaseibacillus paracasei SD1, L. rhamnosus SD4, L. rhamnosus SD11 and Limosilactobacillus fermentum SD7, were examined for the expression of human β-defensins-2-4, and cytokine responses after stimulated by various periodontopathogens. Subsequently, an in vivo study was set as a randomized, double-blind, placebo-controlled intervention in a dog model. A total of 20 dogs with mild gingivitis were randomly assigned to either the probiotic or control group. The effects of probiotics on periodontopathogenic- and cytokine levels were analyzed after 4 weeks of intervention.It showed that all probiotics could induce human β-defensins-2-4, interleukin-1β, interleukin-6, interleukin-8, and tumor necrosis factor-α expressions in human gingival epithelial cells; however, a significant difference had been found among the strains. When individual probiotic strain was combined to periodontopathogens, a significant reduction of IL-8 expression was found. Results of the in vivo study demonstrated that the bacterial levels, especially Porphyromonas gingivalis, and the interleukin-8 levels were significantly decreased after receiving the probiotic products compared to the controls.The results of the in vitro and in vivo studies in dogs are encouraging to support the effectiveness of a mixture of probiotic treatments for improvement of periodontal health by reducing periodontopathogens and interleukin-8 levels. Therefore, such probiotics preparation could possibly have therapeutic potential in human periodontitis.