DIFFERENTIAL CYTOKINE REGULATION OF TYPE-I AND TYPE-VII COLLAGEN GENE-EXPRESSION IN CULTURED HUMAN DERMAL FIBROBLASTS

Type VII collagen is the major component of anchoring fibrils in the cutaneous basement membrane zone. In this study, we have examined the effects of various cytokines on the expression of types I and VII collagen genes in dermal fibroblasts in culture. The pro-inflammatory cytokines, interleukin-1alpha (IL-1alpha), interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), and leukoregulin (LR) strongly elevated (approximately 5-9-fold) type VII collagen mRNA levels, as measured by Northern blot hybridizations. These effects were also observed at the protein level by indirect immunofluorescence using a monoclonal antibody specific for type VII collagen. By contrast, IL-1beta had only a slight stimulatory effect (approximately 2-fold) on type I collagen gene expression, while TNF-alpha and LR markedly reduced type I collagen mRNA steady-state levels. Interestingly, IL-1, TNF-alpha and LR had additive effects with transforming growth factor-beta (TGF-beta) on type VII collagen gene expression, whereas they counteracted the up-regulatory effect of TGF-beta on type I collagen gene expression. Thus, our data indicate that the modulation of type I and type VII collagen gene expression by cytokines involves different regulatory pathways.