title: Inhibition of ATP-binding cassette transporter downregulates interleukin-1beta-mediated autocrine activation of human dermal fibroblasts.
abstract: Fibroblasts constitute an important source of cytokines during inflammatory processes in the skin. Interleukin-1 is a potent, pleiotropic cytokine that is induced in activated human dermal fibroblasts. Interleukin-1 further induces many inflammatory mediators, including the chemokine interleukin-8. As fibroblasts express both interleukin-1 and the interleukin-1 receptor complex, the cellular response may be enhanced by autocrine activation. Interleukin-1alpha and interleukin-1beta lack a signal peptide and are translocated at the plasma membrane using an alternative secretory pathway, which may involve ATP-binding cassette transporter proteins. We hypothesize that inhibition of this pathway prevents secretion of interleukin-1, thereby downregulating interleukin-1-dependent autocrine induction of interleukin-8. We used the ATP-binding cassette 1 transporter inhibitor glybenclamide, which has been previously shown to block interleukin-1beta secretion in human monocytes. Using enzyme-linked immunosorbent assay, we assessed the effect of glybenclamide on interleukin-8 production in human dermal fibroblasts. In interleukin-1beta-transfected human dermal fibroblasts, interleukin-8 was induced through an autocrine activity of interleukin-1beta. Glybenclamide disabled this activation loop and significantly reduced interleukin-8. In human dermal fibroblasts that were stimulated with tumor necrosis factor alpha to reach high interleukin-1 expression levels, glybenclamide similarly suppressed interleukin-8. In contrast, glybenclamide did not affect interleukin-8 production in cells stimulated with interleukin-1 only. Glybenclamide did not affect caspase-1 in fibroblasts, which was expressed as an inactive precursor form, irrespective of treatments with tumor necrosis factor alpha and/or glybenclamide. Using overexpressing, interleukin-1-transfected COS-1 cells, inhibition of interleukin-1alpha and interleukin-1beta secretion was directly demonstrated on Western blots. These results are consistent with glybenclamide preventing externalization of interleukin-1 and subsequent autocrine induction of interleukin-8 in human dermal fibroblasts. Acting through such a mechanism, ATP-binding cassette transporter inhibitors may downregulate inflammation locally.
authors.affiliation: Laboratory of Oral Cell Biology, University of Bern, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Lottaz
authors.forename: Z
authors.initials: Z
authors.lastname: Beleznay
authors.forename: M
authors.initials: M
authors.lastname: Bickel
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000037:antagonists & inhibitors*; D000818:Animals; D019898:Autocrine Communication / Q000502:physiology*; D019556:COS Cells; D002478:Cells, Cultured; D015536:Down-Regulation; D005347:Fibroblasts / Q000187:drug effects / Q000502:physiology*; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D007375:Interleukin-1 / Q000037:antagonists & inhibitors / Q000502:physiology*; D016209:Interleukin-8 / Q000037:antagonists & inhibitors / Q000378:metabolism; D012867:Skin / Q000166:cytology; D012879:Skin Physiological Phenomena; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D018528:ATP-Binding Cassette Transporters; D007375:Interleukin-1; D016209:Interleukin-8; D014409:Tumor Necrosis Factor-alpha; D005905:Glyburide