Human Trophoblast-Derived Exosomal Fibronectin Induces Pro-Inflammatory Il-1β Production by Macrophages

Authors

  • Safinur Atay,

    1. Department of Microbiology & Immunology, University of Louisville School of Medicine, Louisville, KY, USA
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  • Cicek Gercel-Taylor,

    1. Department of Obstetrics, Gynecology and Women’s Health, University of Louisville School of Medicine, Louisville, KY, USA
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  • Douglas D. Taylor

    1. Department of Microbiology & Immunology, University of Louisville School of Medicine, Louisville, KY, USA
    2. Department of Obstetrics, Gynecology and Women’s Health, University of Louisville School of Medicine, Louisville, KY, USA
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Douglas D. Taylor, PhD, Department of Obstetrics, Gynecology, and Women’s Health, 505 South Hancock St., CTRB 316, University of Louisville School of Medicine, Louisville, KY 40202, USA.
E-mail: ddtaylor@louisville.edu

Abstract

Citation Atay S, Gercel-Taylor C, Taylor DD. Human trophoblast-derived exosomal fibronectin induces pro-inflammatory Il-1β production by macrophages. Am J Reprod Immunol 2011; 66: 259–269

Problem  Our previous studies demonstrated that trophoblast-derived exosomes induced synthesis and release of pro-inflammatory cytokines, including interleukin-1β (IL-1β) by macrophages. The objective of this study was to characterize the mechanism and receptors associated with this induction.

Method of study  Exosomes were isolated from Sw71 trophoblast-conditioned media by ultrafiltration and ultracentrifugation. Using macrophages isolated from normal donors, cytochalasin D was used to block exosome uptake. Induction of IL-1β mRNA was investigated by qRT-PCR, pro-IL-1β protein by western immunoblotting, and mature IL-1β release by ELISA. RGD peptides were used to block fibronectin binding by macrophage α5β1 integrin.

Results  Uptake of exosomes by macrophages was completely blocked by pre-treatment with cytochalasin D. Although induction of some cytokines (such as C4A and CCL11) requires uptake, induction of IL-1β occurred without exosome internalization. Cytochalasin D treatment did not inhibit exosome-mediated induction of IL-1β mRNA, production of the pro-protein, or release of mature IL-1β. Blocking of fibronectin binding using RGD peptides demonstrated the abrogation of exosome-mediated IL-1β production.

Conclusion  Although trophoblast-derived exosomes have been demonstrated to induce IL-1β, this is the first demonstration of IL-1β induction by exosome-associated fibronectin. Based on this pro-inflammatory role of exosome-associated fibronectin, it may represent an important general immunoregulatory mechanism.

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