Mast cell-fibroblast interactions: human mast cells as source and inducers of fibroblast and epithelial growth factors.

As mast cells have been implicated in cutaneous repair processes, we have examined the ability of human mast cells to produce important epithelial and fibroblast growth factors or to stimulate the production of such factors in dermal fibroblasts. Isolated, highly purified human dermal mast cells and human leukemic mast cells were examined for mRNA and partly also for protein expression of these molecules as such or after preincubation with interleukin-4, stem cell factor, or with phorbol myristate acetate. In addition, mast cells were studied for their ability to induce fibroblast growth factor 2 and fibroblast growth factor 7 secretion from dermal fibroblasts. Both dermal and leukemic mast cells expressed fibroblast growth factor 2, fibroblast growth factor 7, and heparin-binding epidermal growth factor, but not hepatocyte growth factor at mRNA level, and dermal mast cells expressed fibroblast growth factor 10 in addition. At protein level, spontaneous fibroblast growth factor 2 secretion was noted that was markedly enhanced by phorbol myristate acetate, whereas no fibroblast growth factor 7 protein was detected under these conditions. Instead, human mast cell-1 supernatants induced enhanced fibroblast growth factor 7 secretion from dermal fibroblasts, with phorbol-myristate-acetate-stimulated supernatants being more effective. This effect could be reproduced with histamine and was H1-receptor mediated. Tryptase was ineffective but stimulated instead fibroblast growth factor 2 secretion from fibroblasts. These data demonstrate for the first time the ability of mast cells to express and/or secrete several growth factors of the fibroblast growth factor family as well as heparin-binding epidermal growth factor directly or indirectly via stimulation of fibroblasts, underlining the potentially pivotal role of these cells during human tissue repair and homeostasis.