Regulation of Fibroblast Activity by Keratinocytes

In the healing of cutaneous wounds, paracrine communication between keratinocytes and fibroblasts regulates cell differentiation, proliferation and synthesis of extracellular matrix. Deficient epidermal coverage, as seen in burn-wounds, frequently results in hypertrophic scars. Previous studies suggest that keratinocytes downregulate the production of collagen and profibrotic factors in fibroblasts. We hypothesized that keratinocytes downregulate the expression of the profibrotic factor connective tissue growth factor (CTGF) in fibroblasts, and regulate fibroblast expression of genes important to wound healing. In keratinocyte-fibroblast cocultures, keratinocytes downregulated CTGF mRNA and protein in fibroblasts, through the secretion of interleukin-1 (IL-1) α. Using Affymetrix DNA microarrays, it was demonstrated that factors from keratinocytes regulate the expression of 69 genes important to wound healing. The regulation of 16 of these genes was confirmed by Northern blotting, and IL-1α from keratinocytes regulated all the 16 genes examined. IL-1-mediated CTGF gene regulation was further investigated. Both IL-1 isoforms, α and β, suppressed CTGF expression through an inhibition of CTGF promoter activity…


Structure and function of the skin
Epidermal-dermal interactions
Interactions in embryogenesis
Interactions in adult life
Interactions between keratinocytes and fibroblasts
Wound healin
Tissue remodeling
Growth factors and cytokines in wound healing
Transforming growth factor-E (TGF-E)
Connective tissue growth factor (CTGF)
Transforming growth factor-ȕ and connective tissue growth factor in fibrosis
Interleukin-1 in fibrosis
Present investigation
Materials and methods
Cells, cocultures and conditioned medium
Cultured human dermis
Burn wound biopsies
Ex vivo wound model
Northern blotting
Western blotting
Enzyme-linked immunosorbent assay (ELISA)
DNA microarrays
Transfection of cDNA and luciferase assay
Immunoprecipitation and Western blotting of Smad proteins
RNA extraction from dermis and real-time PCR
Statistical analysis
Paper I
Paper II
Paper III
Paper IV
General discussion
Keratinocyte-mediated downregulation of CTGF
Keratinocytes and regulation of gene expression in fibroblasts
Regulation of CTGF expression by interleukin-1
CTGF expression in the healing of split-thickness skin grafts, and
during reepithelialization – the effect of IL-1D on dermal CTGF

Author: Nowinski, Daniel

Source: Uppsala University Library

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