Regulation of interleukin 1 generation in immune-activated fibroblasts.
In the present study we have demonstrated that fibroblasts can generate the inflammatory cytokine interleukin 1 (IL 1) under conditions similar to those abundant in cellular immune responses. Thus, induction of IL 1 requires a sequential two-step protocol which consists of preactivation of mouse embryo fibroblasts (MEF) with crude preparations of T cell or macrophage-derived conditioned media (CM; 72 h), followed by a challenge with lipopolysaccharide (LPS; 24 h). Unstimulated fibroblasts or such cells activated by either CM or LPS produced only low levels of IL 1, while a synergism between both signals was observed for obtaining maximal IL 1-like activity in MEF. Each of a series of individual recombinant lymphokines and cytokines (IL 2, granulocyte/macrophage-colony-stimulating factor, tumor necrosis factor, IL 1 beta and interferons-alpha, beta and gamma) was shown to serve as an efficient priming signal for the induction of IL 1. IL 1-like activity in fibroblasts was detected in cell lysates or associated with the producing-cell membrane but not in culture fluids. Immune-stimulated fibroblasts, activated under such experimental conditions, were shown to actively transcribe mRNA of both IL 1 genes (alpha and beta). For the expression of IL 1-specific mRNA in fibroblasts a single stimulus, provided by either LPS or a lymphokine/cytokine, was sufficient; however, a more intense signal was observed when both stimuli were applied. The IL 1-like biological activity of fibroblast origin was significantly reduced by anti-IL 1 alpha antibodies. Thus, fibroblasts, when activated by immune and bacterial products, generate IL 1 which in turn possibly amplifies cellular immune responses or inflammatory processes in connective tissues.
Huleihel
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M
Department of Microbiology and Immunology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
Douvdevani
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A
Segal
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Apte
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RN
D000818:Animals; D001685:Biological Factors / Q000494:pharmacology; D016207:Cytokines; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000276:immunology; D007375:Interleukin-1 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008222:Lymphokines / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D014158:Transcription, Genetic
D001685:Biological Factors; D016207:Cytokines; D007375:Interleukin-1; D008070:Lipopolysaccharides; D008222:Lymphokines