Abstract
Periodontitis is a chronic inflammatory disease caused by various periodontal pathogens. Weissella cibaria CMU (oraCMU) is a probiotic that promotes oral health. However, its anti‑inflammatory effects against periodontal pathogens have not yet been investigated. The present study evaluated the anti‑inflammatory effects of live oraCMU against stimulation with the formalin‑inactivated periodontal pathogen Aggregatibacter actinomycetemcomitans in RAW 264.7 macrophages. Cell viability was analyzed by the MTS assay in a dose‑dependent manner (at multiplicities of infection of 0.1, 1, 10, 100 and 1,000). Nitric oxide (NO) was monitored using the Griess test. The mRNA expression of proinflammatory cytokines such as interleukin (IL)1β and IL6 was assessed by reverse transcription‑quantitative PCR. Western blotting was used to examine the effects of oraCMU on the phosphorylation of NF‑κB inhibitor α (IκBα) and IκBα kinase (IKK), the nuclear translocation of the NF‑κB subunit p65 and the expression of inducible NO synthase (iNOS). Live oraCMU had no cytotoxic effects on RAW 264.7 macrophages. In A. actinomycetemcomitans‑stimulated RAW 264.7 macrophages, oraCMU reduced NO production by suppressing iNOS expression and downregulating the mRNA expression of proinflammatory cytokines in a dose‑dependent manner. IKK phosphorylation and IκBα degradation were dose‑dependently inhibited by oraCMU and the nuclear translocation of p65 via the canonical NF‑κB pathway was simultaneously reduced. The results indicated that oraCMU possessed anti‑inflammatory activity associated with the inhibition of NF‑κB signal activation in response to periodontal pathogens. This suggests that oraCMU is a beneficial anti‑inflammatory probiotic that can aid in the maintenance of oral health.