Limosilactobacillus reuteri supernatant attenuates inflammatory responses of human gingival fibroblasts to LPS but not to elevated glucose levels

AIM We investigated the in vitro effect of Limosilactobacillus reuteri DSM 17938 supernatant on the inflammatory response of human gingival fibroblasts (HGF) challenged by lipopolysaccharide (LPS) or elevated glucose levels. METHODS HGF were exposed to LPS (1 μg/mL), glucose (5, 12 mM or 25 mM), and dilutions of supernatant prepared from L. reuteri DSM 17938 (0.5 × 10$^{7}$, 1.0 × 10$^{7}$, 2.5 × 10$^{7}$, and 5.0 × 10$^{7}$ CFU/mL). After 24 h cell viability and levels of cytokines (IL-1β, IL-6 and IL-8) and TLR-2 were determined. RESULTS None of the tested L. reuteri (DSM 17938) supernatant concentrations reduced the viability of HGF. Supernatant concentrations (2.5 × 10$^{7}$ and 5 × 10$^{7}$ CFU/mL) significantly (p < .05) decreased the production of IL-1β, IL-6, IL-8, and TLR-2 in the presence of LPS. In contrast, inflammatory markers were not reduced by L. reuteri supernatant in the presence of glucose. Glucose concentrations of 12 mM and 24 mM still lead to an elevated production of the investigated biochemical mediators. CONCLUSION While L. reuteri (DSM 17938) supernatant attenuates the inflammatory response of HGF to LPS in a dose-dependent manner, elevated glucose levels suppress this action. These in vitro results support the overall anti-inflammatory efficacy of L. reuteri supplementation in plaque-associated periodontal inflammations.