IN-VITRO SENESCENCE ENHANCES IL-6 PRODUCTION IN HUMAN GINGIVAL FIBROBLASTS INDUCED BY LIPOPOLYSACCHARIDE FROM CAMPYLOBACTER-RECTUS

The production of interleukin-6 (IL-6) in human gingival fibroblasts ( Gin cells) is increased by lipopolysaccharide (LPS) from Campylobacter rectus (C. rectus), which is associated with adult periodontitis; how ever, the age-related changes in the susceptibility of Gin cells to C. rectus LPS remain unclear. We examined the influence of in vitro sene scence on C. rectus LPS-stimuiated IL-6 production in Gin cells. LPS w as prepared from C. rectus ATCC 33238 using hot phenol-water. The Gin cells were established from healthy gingival tissue removed from three patients, aged 10-12 years. The cells were cultured until confluence then stimulated with LPS (0.01, 0.1, 1.0 and 10.0 mu g/ml). Levels of IL-6 released in the medium were measured after incubation for 3, 6, 9 , 12, and 24 h. In both young (5-6 population doublings) and senescent (17-20 population doublings) cells, LPS stimulated IL-6 production in a dose- and time-dependent manner. In response to 0.01-10.0 mu g/ml o f LPS, IL-6 production in the senescent cells was higher than that in the young cells. Using cells from each of the three donors, we found t hat this phenomenon of higher LPS-stimulated IL-6 production in senesc ent cells was reproducible. The greater capacity of the senescent cell s to synthesize IL-6 in response to LPS was a higher production of mRN A for IL-6. This increase of IL-6 production induced by C. rectus LPS in senescent Gin cells could help to explain the increased susceptibil ity to periodontal diseases shown by aged individuals.