The effect of Mogibacterium timidum to human gingival fibroblasts

Objectives: Mogibacterium timidum, asaccharolytic obligate anaerobic gram positive rods, has been reported to be detected from the deep pockets of periodontitis frequently. However, it is not yet elucidated whether this bacteria has the pathogenicity and etiologic factors for the periodontitis. In this study, we examined influence to production of inflammatory cytokines (TNF-alpha, interleukin-1beta, interleukin-6 and interleukin-8) from human gingival fibroblasts (HGF) stimulated with M. timidum. Methods: M. timidum ATCC 33093, Porphyromonas gingivalis ATCC 33277 and Actinomyces viscosus ATCC 19246 were cultured on blood plates in anaerobic box. The bacterial suspensions were prepared by centrifugation and washing in PBS. HGF were inoculated to 6 well plates and incubated to confluent. And then HGF were treated with the bacterial suspensions from MOI= 0.1 to 1000 at 4, 8, 24 and 48 hours. After the treatment, the supernatant were collected and measured the quantity of inflammatory cytokines by ELISA. Also mRNA was prepared from HGF after stimulation by bacterial species and mRNA expression was determined by RT-PCR. Results: The stimulated HGF with M. timidum did not increase production of inflammatory cytokines. On the other hand, the stimulations by P. gingivalis and A. viscosus increased production of them. However, these increased cytokine productions were inhibited when HGF were stimulated with P. gingivalis and M. timidum together. Conclusion: These results were suggested that asaccharolytic obligate anaerobic gram positive bacteria alone may not affect to production of inflammatory cytokines from the host cells. However, it is possible that these bacteria may be related to the chronicity of periodontitis, when these bacteria are combined with other bacteria in the periodontal pockets.