Inflammatory responses increase secretion of MD-1 protein

Richard Thomas Jennings, Erdenezaya Odkhuu, Akina Nakashima, Naoko Morita, Toshihiko Kobayashi, Ikuko Yamai, Miyako Tanaka, Takayoshi Suganami, Sanae Haga, Michitaka Ozaki, Yasuharu Watanabe, Yoshinori Nagai, Kiyoshi Takatsu, Takane Kikuchi-Ueda, Isao Ichimonji, Yoshihiro Ogawa, Hidekazu Takagi, Tatsuya Yamazaki, Kensuke Miyake, Sachiko Akashi-Takamura

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Radioprotective 105 (RP105) is a type I transmembrane protein, which associates with a glycoprotein, MD-1. Monoclonal antibody (mAb)-mediated ligation of RP105/MD-1 robustly activates B cells. RP105/MD-1 is structurally similar to Toll-like receptor 4 (TLR4)/MD-2. B-cell responses to TLR2 and TLR4/MD-2 ligands are impaired in the absence of RP105 or MD-1. In addition to RP105/MD-1, MD-1 alone is secreted. The structure of MD-1 shows that MD-1 has a hydrophobic cavity that directly binds to phospholipids. Little is known, however, about a ligand for MD-1 and the role of MD-1 in vivo. To study the role of RP105/MD-1 and MD-1 alone, specific mAbs against MD-1 are needed. Here, we report the establishment and characterization of two anti-MD-1 mAbs (JR2G9, JR7G1). JR2G9 detects soluble MD-1, whereas JR7G1 binds both soluble MD-1 and the cell surface RP105/MD-1 complex. With these mAbs, soluble MD-1 was detected in the serum and urine. The MD-1 concentration was altered by infection, diet and reperfusion injury. Serum MD-1 was rapidly elevated by TLR ligand injection in mice. The quantitative PCR and supernatant-precipitated data indicate that macrophages are one of the sources of serum soluble MD-1. These results suggest that soluble MD-1 is a valuable biomarker for inflammatory diseases.

Original languageEnglish
Pages (from-to)503-512
Number of pages10
JournalInternational immunology
Volume28
Issue number10
DOIs
Publication statusPublished - Oct 1 2016
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Immunology and Allergy
  • Immunology

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