Cocultures of fibroblasts and keratinocytes, physically separated by a membrane, were carried out for 48 h, and large-scale gene expression in the fibroblasts was analyzed by Affymetrix microarrays of expressed mRNAs. Two independent experiments were performed with cells from different individuals. A total of 243 genes were upregulated twofold or more and 100 genes were negatively regulated (reduction by half or more) in both experiments. A total of 69 of these 343 genes coded for growth factors, cytokines, chemokines, or their receptors; extracellular matrix molecules or enzymes involved in their synthesis; adhesion receptors; proteinases/proteinase inhibitors or their receptors; cell cycle regulators; apoptosis-regulating factors; prostaglandin-related factors; or growth-factor-binding proteins. Most of the remaining genes coded for proteins involved in signal transduction or general metabolism. Sixteen genes selected from these groups were further analyzed by northern blot analysis to confirm the array data. Finally, experiments with interleukin-1α (IL-1α)-blocking antibodies or IL-1 receptor antagonists demonstrate that IL-1α is one important factor involved in keratinocyte-mediated regulation of gene expression in fibroblasts. Taken together, the results suggest that keratinocytes regulate fibroblast gene expression with implications for the wound healing process during reepithelialization.
