REGULATION OF KERATINOCYTE GROWTH-FACTOR GENE-EXPRESSION BY INTERLEUKIN-1

Keratinocyte growth factor (KGF) is a stromally derived member of the fibroblast growth factor family (FGF7) with potent mitogenic activity on a variety of epithelial cells. To identify molecules that regulate the expression of this paracrine mediator of epithelial proliferation, we investigated the effects of various cytokines and growth factors on KGF production by fibroblasts. The proinflammatory cytokine interleukin 1 (IL1) strongly induced the expression of KGF RNA in fibroblasts from multiple sources. Platelet-derived growth factor BB, IL6, and transforming growth factor a caused a moderate elevation, while tumor necrosis factor a and basic FGF did not alter the level of KGF RNA expression. The induction by IL1 of KGF transcript levels was time and dose dependent and specifically blocked by anti-IL1 antibodies. Nuclear run on experiments indicated that IL1 stimulated KGF gene transcription. Western blot analysis and keratinocyte proliferation assays demonstrated a corresponding increase in mitogenically active KGF protein in conditioned medium obtained from IL1-treated fibroblasts. The stimulation of KGF expression by IL1 and other cytokines such as IL6, transforming growth factor alpha, and platelet-derived growth factor may provide a mechanism for KGF induction during inflammation that would support its proposed role as mediator of reepithelialization and wound healing.