Thrombospondin-1 differentially regulates release of IL-6 and IL-10 by human monocytic cell line U937 |
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Authors: | Yamauchi Yasushi Kuroki Motomu Imakiire Takayuki Abe Hironori Uchida Hiroko Beppu Richiko Yamashita Yuichi Kuroki Masahide Shirakusa Takayuki |
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Affiliation: | First Department of Biochemistry, Fukuoka University School of Medicine, 7-45-1 Nanakuma, Jonan-ku, Fukuoka 814-0180, Japan. |
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Abstract: | We investigated possible regulatory effects of thrombospondin-1 (TSP-1), a multifunctional extracellular matrix protein, on cytokine release from macrophages. Immobilized TSP-1 enhanced IL-6 release from the human monocytic U937 cells stimulated with phorbol myristate acetate and LPS, whereas it inhibited IL-10 release. The 70-kDa fragment of TSP-1 containing the type 1 repeats showed the same regulatory effects. The enhanced IL-6 release by TSP-1 was inhibited by anti-CD36 antibody or antibody against the sequence of the binding site to CD36 in the type 1 repeats of TSP-1. Conversely, the decrease in IL-10 release by TSP-1 was strengthened by the blocking of the interaction between CD36 and TSP-1. Furthermore, the involvement of TGF-beta1 in the inhibition of IL-10 release by TSP-1 was indicated by the facts that (i) TSP-1 induced activation of TGF-beta1 produced by the U937 cells, (ii) exogenously added TGF-beta1 inhibited IL-10 release, and (iii) antibody against TGF-beta1 blocked the inhibition of IL-10 release by TSP-1. Together, the present findings suggest that TSP-1 enhances IL-6 release from macrophages by interaction with CD36, whereas IL-10 release is regulated by the balance between the enhancing effect of TSP-1 via CD36 and the suppressive effect by TSP-1-activated TGF-beta1. |
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Keywords: | thrombospondin-1 IL-6 IL-10 CD36 TGF-β1 U937 macrophage |
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