Dispase is a bacterial neutral protease which is obtained from the culture filtrate of Bacillus polymyxa. After 24-h treatment of the human skin with 500 and 1000 U/ml dispase, the epidermal sheet was easily peeled from the dermis, and its undersurface retained rete ridges. Electron microscopic observation showed that the basal surface was composed of cells with numerous slender villi and cytoplasmic projections. Although the intercellular spaces of the spinous as well as the basal layers were wide, all desmosomes were intact with their accompanying tonofilaments. An epidermal cell suspension was obtained by incubating the dispase-separated epidermal sheet in trypsin solution for 15 min and the viability of the cells was more than 95% as measured by the trypan blue dye exclusion test. A culture of keratinocytes was established by seeding the dissociated cells in the usual way.
Interleukin-6 (IL-6) is thought to be a major mediator of the host's defense against infection, and it regulates immune responses in inflamed tissue. In this study, we investigated the regulation of IL-6 production in human gingival fibroblasts (HGF) and human periodontal ligament fibroblasts (HPLF). Pro-inflammatory cytokines including interleukin (IL)-1 alpha, IL-1 beta and tumor necrosis factor (TNF)-alpha stimulated IL-6 production in HGF and HPLF in a time- and dose-dependent manner. This IL-1 alpha, IL-1 beta, or TNF-alpha-induced IL-6 production was enhanced, but the cAMP accumulation they induced was inhibited by the addition of indomethacin. This result suggests that endogenous prostaglandin E2 (PGE2) partially inhibits IL-1 or TNF-alpha-induced IL-6 production and that the enhancement of IL-6 production by IL-1 or TNF-alpha may not be caused through endogenous PGE2-induced cAMP-dependent pathway. Dexamethasone (DEX), a glucocorticoid which is a inhibitor of nuclear factor kappa B (NF-kappa B activation, markedly inhibited IL-1 (alpha or beta) or TNF-alpha-induced IL-6 production; so this production may be partially mediated through NF-kappa B. IL-1 (alpha or beta) and TNF-alpha enhanced IL-6 production synergistically. IL-6 production in HGF or HPLF stimulated with IL-1 beta was augmented by the addition of interferon (IFN)-gamma, but was slightly suppressed by the addition of IL-4. Endogenous IL-6 enhanced IL-1 (alpha or beta)-induced IL-6 production in the presence of IL-6 soluble receptor (IL-6sR). Accordingly, in inflamed periodontal tissues, gingival fibroblasts and periodontal ligament fibroblasts stimulated with pro-inflammatory cytokines such as IL-1 or TNF-alpha, may produce IL-6, and this production can be differentially modulated by endogenous PGE2, IL-6sR, T cell-derived cytokines such as IFN-gamma or IL-4, and glucocorticoids.
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