Fibroblast functions both as a structural element and as a vital immunoregulatory cell. Fibroblasts regulate inflammation through governing of chemokine expression. In order to elucidate the mechanisms by which the expressions of chemokines were regulated, the co-stimulatory effects of Th1 and proinflammatory cytokines were compared using nasal mucosal fibroblasts.

Human nasal mucosa was obtained from surgery for septal deviation and the growth of fibroblasts was established. Fibroblasts from 4th to 6th passage were stimulated with various combinations of cytokines. To inhibit selected signaling pathways, fibroblasts were pretreated with cyclosporin A, wortmannin, staurosporine, and dexamethasone prior to the stimulation with cytokines. The supernatants were collected and chemokines were detected with a sandwich enzyme-linked immunosorbent assay.

TNF-α/IFN-γ-induced production of RANTES was inhibited by all inhibitors used. MCP-1 was produced constitutively and TNF-α-induced or TNF-α/IFN-γ-induced production of MCP-1 was not inhibited by cyclosporin A or wortmannin, but by stauroporine or dexamethasone. All inhibitors used in this experiment inhibited TNF-α/IFN-γ-induced or IL-1β/IFN-γ-induced production of MCP-2 in nasal mucosal fibroblasts. Although staurosporine or dexamethasone showed strong inhibitory effects, cyclosporin A or wortmannin did not inhibit the production of MCP-3 by IL-1β/IFN-γ treatment.

Chemokines were strongly induced by stimulation of cytokines in combination and showed different pattern of inhibition by the inhibitors. Therefore, it was assumed that cytokines acted on multiple pathways or on unknown pathways which converged to gene-specific transcription factors.