INVIVO CYTOKINE EXPRESSION IN NORMAL AND PERTURBED MURINE SKIN - ANALYSIS BY COMPETITIVE QUANTITATIVE POLYMERASE CHAIN-REACTION

Although cells from both epidermis and dermis have been shown to produ ce a variety of soluble mediators in vitro, it is not clear whether th is reflects the in vivo situation. To study in vivo cytokine expressio n, whole skin as well as dispase-separated epidermis and dermis from n ormal adult mice were prepared and snap-frozen immediately. RNA was th en extracted and analyzed both by conventional and by competitive quan titative polymerase chain reaction. Molecular analysis showed that mur ine skin in vivo constitutively expresses several cytokine genes at mo derate (e.g., interleukin-1alpha) or low (e.g., interleukin-6 and gran ulocyte-macrophage colony-stimulating factor) abundance. A striking, r apid upregulation was observed for some of these cytokines in the proc ess of tissue separation. Of interest, the epidermal and dermal compar tments exhibited different induction patterns: interleukin-1alpha, gra nulocyte-macrophage colony-stimulating factor, and tumor necrosis fact or-alpha expression were detected preferentially in the epidermis, whe reas upregulation of interleukin-6 was found to be most prominent in t he dermis. This pattern of cytokine expression was also reflected in s upernatants generated from the respective single-cell suspensions. Thu s, this study determines the baseline in vivo cytokine expression in t he skin and the occurrence of immediate, compartment-specific alterati ons on perturbation. These data should contribute to our understanding of both skin homeostasis and the host-defense mechanisms initiated fo llowing injury to this organ.