The proteomic profile of circulating pentraxin 3 (PTX3) complex in sepsis demonstrates the interaction with azurocidin 1 and other components of neutrophil extracellular traps.

Kenji Daigo, Naotaka Yamaguchi, Takeshi Kawamura, Koichi Matsubara, Shuying Jiang, Riuko Ohashi, Yukio Sudou, Tatsuhiko Kodama, Makoto Naito, Kenji Inoue, Takao Hamakubo

Research output: Contribution to journalArticle

Abstract

Pentraxin 3 (PTX3), a long pentraxin subfamily member in the pentraxin family, plays an important role in innate immunity as a soluble pattern recognition receptor. Plasma PTX3 is elevated in sepsis (~200 ng/ml) and correlates with mortality. The roles of PTX3 in sepsis, however, are not well understood. To investigate the ligands of PTX3 in sepsis, we performed a targeted proteomic study of circulating PTX3 complexes using magnetic bead-based immunopurification and shotgun proteomics for label-free relative quantitation via spectral counting. From septic patient fluids, we successfully identified 104 candidate proteins, including the known PTX3-interacting proteins involved in complement activation, pathogen opsonization, inflammation regulation, and extracellular matrix deposition. Notably, the proteomic profile additionally showed that PTX3 formed a complex with some of the components of neutrophil extracellular traps. Subsequent biochemical analyses revealed a direct interaction of bactericidal proteins azurocidin 1 (AZU1) and myeloperoxidase with PTX3. AZU1 exhibited high affinity binding (K(D) = 22 ± 7.6 nm) to full-length PTX3 in a calcium ion-dependent manner and bound specifically to an oligomer of the PTX3 N-terminal domain. Immunohistochemistry with a specific monoclonal antibody generated against AZU1 revealed a partial co-localization of AZU1 with PTX3 in neutrophil extracellular traps. The association of circulating PTX3 with components of the neutrophil extracellular traps in sepsis suggests a role for PTX3 in host defense and as a potential diagnostic target.

Original languageEnglish
JournalMolecular and Cellular Proteomics
Volume11
Issue number6
DOIs
Publication statusPublished - Jun 2012

ASJC Scopus subject areas

  • Medicine(all)

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