Endogenous metalloprotease solubilizes IL-13 receptor α2 in airway epithelial cells

https://doi.org/10.1016/j.bbrc.2007.06.076Get rights and content

Abstract

IL-13 receptor α2 (IL-13Rα2) has been postulated to be a decoy receptor. The precise mechanisms for the generation of soluble IL-13Rα2 and the biological activity of the endogenous soluble form have not been reported. Hypothesizing that the soluble form of IL-13Rα2 is generated by proteolytic cleavage of membrane-bound receptors, we transfected human airway epithelial cells with adenoviral vectors encoding full-length IL-13Rα2. Eotaxin production from IL-13Rα2-transfected cells was suppressed, and soluble IL-13Rα2 in the supernatants was increased time-dependently after the transfection. The transfer of conditioned media from IL-13Rα2-transfected cells inhibited IL-13-induced eotaxin production and STAT6 phosphorylation in non-transfected cells. PMA enhanced the release of soluble IL-13Rα2, and metalloprotease inhibitors inhibited this release. These findings suggest that airway epithelial cells with upregulation of membrane-bound IL-13Rα2 secrete soluble IL-13Rα2 into its supernatant, causing the autocrine and paracrine downregulation of the IL-13/STAT6 signal. Metalloprotease(s) are responsible for the proteolytic cleavage of cell surface IL-13Rα2.

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Materials and methods

Cell culture. BEAS-2B cells, a human airway epithelial cell line transformed with the SV40 virus, were cultured in DMEM/F-12 medium with 10% FBS, penicillin, and streptomycin.

Adenovirus transfection and stimulation. A replication-defective ΔE1ΔE3 adenoviral vector expressing the IL-13Rα2 chain gene under the CMV promoter (Ad-IL-13Rα2) was constructed as described previously [18]. Another replication-defective adenoviral vector expressing the β-galactosidase gene (Ad-LacZ) was constructed in the

IL-13Rα2 gene induction in airway epithelial cells and secretion of soluble L-13Rα2

IL-13Rα2 mRNA levels were barely detectable in BEAS-2B cells. To establish airway epithelial cells with a high expression of IL-13Rα2, BEAS-2B cells were transfected with a full-length IL-13Rα2 using Ad-IL-13Rα2. Ad-IL-13Rα2 transfection, but not Ad-LacZ, induced IL-13 Rα2 mRNA in a multiplicity of infection (moi)-dependent manners (Fig. 1A). Maximal induction of IL-13Rα2 was observed at 30-moi transfection of Ad-IL-13Rα2. We also analyzed the time kinetics of IL-13Rα2 mRNA expression. The high

Discussion

We demonstrate that the transfection of full-length IL-13Rα2 induces the release of soluble IL-13Rα2 from airway epithelial cells and that the transfer of conditioned media from IL-13Rα2-transfected cells inhibits IL-13-induced eotaxin production and STAT6 phosphorylation in other non-transfected cells. PMA enhances the release of soluble IL-13Rα2, and metalloprotease inhibitors block this PMA-induced release of IL-13Rα2. These findings suggest that the upregulation of membrane-bound IL-13Rα2

Acknowledgments

We thank Ayako Hashizume, Tomoko Yoshimura, Yuki Yoshiura, and the Morphology Core, Faculty of Medicine, Kyushu University, for technical assistance.

References (32)

  • D.J. Hilton et al.

    Cloning and characterization of a binding subunit of the interleukin 13 receptor that is also a component of the interleukin 4 receptor

    Proc. Natl. Acad. Sci. USA

    (1996)
  • D.D. Donaldson et al.

    The murine IL-13 receptor alpha 2: molecular cloning, characterization, and comparison with murine IL-13 receptor alpha 1

    J. Immunol.

    (1998)
  • M.G. Chiaramonte et al.

    Regulation and function of the interleukin 13 receptor alpha 2 during a T helper cell type 2-dominant immune response

    J. Exp. Med.

    (2003)
  • N. Wood et al.

    Enhanced interleukin (IL)-13 responses in mice lacking IL-13 receptor alpha 2

    J. Exp. Med.

    (2003)
  • S. Fichtner-Feigl et al.

    IL-13 signaling through the IL-13alpha(2) receptor is involved in induction of TGF-beta(1) production and fibrosis

    Nat. Med.

    (2005)
  • M. Kioi et al.

    N-linked glycosylation of IL-13R alpha2 is essential for optimal IL-13 inhibitory activity

    FASEB J.

    (2006)
  • Cited by (0)

    This work was supported in part by Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science.

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