1. Academic Validation
  2. Contribution of the exosome-associated form of secreted endoplasmic reticulum aminopeptidase 1 to exosome-mediated macrophage activation

Contribution of the exosome-associated form of secreted endoplasmic reticulum aminopeptidase 1 to exosome-mediated macrophage activation

  • Biochim Biophys Acta Mol Cell Res. 2018 Jun;1865(6):874-888. doi: 10.1016/j.bbamcr.2018.03.009.
Yoshikuni Goto 1 Yuko Ogawa 2 Hiroki Tsumoto 3 Yuri Miura 3 Takahiro J Nakamura 4 Kenji Ogawa 5 Yoshihiro Akimoto 6 Hayato Kawakami 6 Tamao Endo 3 Ryohei Yanoshita 2 Masafumi Tsujimoto 2
Affiliations

Affiliations

  • 1 Faculty of Pharmaceutical Sciences, Teikyo-Heisei University, Nakano, Tokyo 164-8530, Japan. Electronic address: y.goto@thu.ac.jp.
  • 2 Faculty of Pharmaceutical Sciences, Teikyo-Heisei University, Nakano, Tokyo 164-8530, Japan.
  • 3 Research Team for Mechanism of Aging, Tokyo Metropolitan Institute of Gerontology, Itabashi, Tokyo 173-0015, Japan.
  • 4 Department of Life Sciences, School of Agriculture, Meiji University, Kawasaki, Kanagawa 214-8571, Japan.
  • 5 Chemical Genetics Laboratory, RIKEN, Wako, Saitama 351-0198, Japan.
  • 6 Department of Anatomy, Kyorin University School of Medicine, Mitaka, Tokyo 181-8611, Japan.
Abstract

Macrophages secrete endoplasmic reticulum Aminopeptidase 1 (ERAP1) in response to lipopolysaccharide (LPS) and interferon (IFN)-γ to enhance their phagocytic and nitric oxide (NO) synthetic activities. In this study, we found that a subset of secreted ERAP1 bound to exosomes released from LPS/IFN-γ-treated murine RAW264.7 macrophages compared to untreated cells. ERAP1-bound exosomes enhanced phagocytic and NO synthetic activities of macrophages more efficiently than free ERAP1 and exosomes derived from untreated cells. Deletion of the exon 10 coding sequence in ERAP1 gene resulted in loss of binding to exosomes. By comparing the activities of exosomes derived from wild-type and ERAP1 gene-deficient RAW264.7 cells, we observed that ERAP1 contributed to the exosome-dependent phagocytosis and NO synthesis of the cells. Upon stimulation of RAW264.7 cells with LPS/IFN-γ, TNF-α, IFN-γ, and CCL3 were also associated with the released exosomes. Analyses of cytokine function revealed that while CCL3 in the exosomes was crucial to the phagocytic activity of RAW264.7 cells, TNF-α and IFN-γ primarily contributed to the enhancement of NO synthesis. These results suggest that treatment with LPS/IFN-γ alters the physicochemical properties of exosomes released from macrophages in order to facilitate association with ERAP1 and several cytokines/chemokines. This leads to exosome-mediated enhancement of macrophage functions. It is possible that packaging effector molecules into exosomes upon inflammatory stimuli, facilitates the exertion of effective pathophysiological functions on macrophages. Our data provide the first evidence that ERAP1 associated with exosomes plays important roles in inflammatory processes via activation of macrophages.

Keywords

Aminopeptidase; Cytokines; Exosome; Macrophages; Nitric oxide; Phagocytosis.

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