Normal human gingival fibroblasts stimulated in vitro by lipopolysaccharides (LPS) from oral Bacteroides species produced ceUl-free and cell-associated thymocyte-activating factors (TAF). Neutralization assays using antisera to human interleukin-la (HuIL-la), HuIL-l0, and HuIL-6 revealed that ceUl-free TAF was attributable mainly to IL-1" and that IL-6 augmented the TAF activity of IL-1" in the culture supernatant. Another factor(s), however, may also be involved in cell-free TAF. By contrast, the active entity of cell-associated TAF was ascribed to IL-la alone. Furthermore, IL-6 was detected mainly in the supernatant of fibroblast cultures stimulated with Bacteroides LPS. Fibroblasts pretreated with natural human beta or gamma interferon, but not those pretreated with alpha interferon, synthesized higher levels of cell-associated IL-la in response to stimulation by Bacteroides LPS; however, no interferons exhibited direct IL-i-inducing activity or synergistic IL-i-inducing activity with LPS. Endogenously induced beta interferon was suggested to be necessary for fibroblasts to produce cell-associated IL-la in response to Bacteroides LPS.

No abstract

No abstract

A 24-kDa polypeptide which activated the incorporation of [3Hlthymidine into human fibroblasts was isolated from the outer membrane vesicles of Porphyromonas gingivalis W50. This polypeptide, named fibroblast activating factor (FAF), was isolated by 3-[(3-cholamidopropyl)-dimethyl-ammonioJ-1-propanesulfonate (CHAPS) detergent extraction and purified by DEAE ion-exchange chromatography and preparative isoelectric focusing. Purified FAF (100 ng of protein per ml) caused a 400%o increase in [3H]thymidine incorporation into human gingival fibroblasts (HGFs) compared with results for controls. FAF was characterized as (i) a polypeptide with molecular masses of 24 kDa when heated at 100°C for 5 min and 44 kDa when unheated, (ii) heat sensitive but not affected by selected reducing reagents, and (iii) possessing slight phosphatase activity. N'-terminal sequence analysis revealed no homology with P. gingivalis peptides or with any host-derived growth factors. These data suggest that FAF functions as a significant virulence factor which in vivo is capable of modulating homeostasis in local connective tissues.