title: Acute-phase ITIH4 levels distinguish multi-system from single-system Langerhans cell histiocytosis via plasma peptidomics.
abstract: BACKGROUND
  Langerhans cell histiocytosis (LCH) is a proliferative disorder in which abnormal Langerhans cell (LC)-like cells (LCH cells) intermingle with inflammatory cells. Whether LCH is reactive or neoplastic remains a controversial matter. We recently described Merkel cell polyomavirus (MCPyV) as a possible causative agent of LCH and proposed interleukin-1 loop model: LCH is a reactive disorder with an underlying oncogenic potential and we now propose to test this theory by looking for acute markers of inflammation. We detected MCPyV-DNA in the peripheral blood cells of patients with high-risk organ-type (LCH-risk organ (RO) (+)) but not those with non-high-risk organ-type LCH (LCH-RO (-)); this difference was significant. LCH-RO (-) is further classified by its involvement of either a single organ system (SS-LCH) or multiple organ systems (MS-LCH). In patients with LCH-RO (-), MCPyV-DNA sequences were present in LCH tissues, and significant differences were observed between LCH tissues and control tissues associated with conditions such as dermatopathic lymphadenopathy and reactive lymphoid hyperplasia. Although MCPyV causes subclinical infection in nearly all people and 22 % of healthy adults will harbor MCPyV in their buffy coats, circulating monocytes could serve as MCPyV reservoirs and cause disseminated skin lesions.
  
  
  METHODS
  Plasma sample from 12 patients with LCH-RO (-) (5 MS-LCH and 7 SS-LCH) and 5 non-LCH patients were analyzed by peptidomics. Mass spectrometry (MS) spectra were acquired and peptides exhibiting quantitative differences between MS-LCH and SS-LCH patients were targeted.
  
  
  RESULTS
  One new candidate biomarker, m/z 3145 was selected and identified after obtaining a MS/MS fragmentation pattern using liquid chromatography-MS/MS. This peak was identified as a proteolytic fragment derived from inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4, [PDB: Q14624]).
  
  
  CONCLUSIONS
  Peptidomics of LCH have revealed that the level of acute-phase ITIH4 distinguishes MS-LCH-RO (-) from SS-LCH-RO (-). Acute-phase proteins serve non-specific, physiological immune functions within the innate immune system. LCH may be a reactive disorder with both underlying neoplastic potential of antigen presenting cells harboring BRAF mutations and hyper-immunity of other inflammatory cells against MCPyV infection. Among LCH-RO (-), MCPyV-DNA sequences were present in both MS-LCH tissues and SS-LCH tissues without significant differences. ITIH4 may show that LCH activity or LCH subtypes correlates with the systemic or localized reactions of MCPyV infection.
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Murakami
authors.affiliation: Department of Pediatrics, Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498 Japan.
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Oh
authors.affiliation: Department of Pediatrics, Jichi Medical University School of Medicine, Shimotsuke, Tochigi 329-0498 Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Morimoto
authors.affiliation: Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8503 Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Sano
authors.affiliation: Division of Pediatrics and Perinatology, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8503 Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kanzaki
authors.affiliation: Department of Pathobiological Science and Technology, School of Health Science, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8503 Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Matsushita
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Iwasaki
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kuwamoto
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Masako
authors.initials: M
authors.lastname: Kato
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Nagata
authors.affiliation: Division of Molecular Pathology, Faculty of Medicine, Tottori University, 86 Nishi-cho, Yonago-shi, Tottori 683-8503 Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Hayashi
authors.affiliation: Division of Pediatrics and Hematology, Takasago-seibu Hospital, Takasago, Hyogo 676-0812 Japan.
authors.forename: Shinsaku
authors.initials: S
authors.lastname: Imashuku
authors.affiliation: Inserm U507 and U1016, Institut Cochin, 75014 Paris, France.
authors.forename: Jean
authors.initials: J
authors.lastname: Gogusev
authors.affiliation: AP-HP Hôpital Necker-Enfants Malades, University Paris Descartes (Paris 5), 75006 Paris, France.
authors.forename: Francis
authors.initials: F
authors.lastname: Jaubert
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama 700-8530 Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Oka
authors.affiliation: Department of Pathology, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama, Okayama 700-8530 Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Yoshino
keywords: Inter-alpha-trypsin inhibitor heavy chain 4 (ITIH4) [PDB: Q14624]; Interleukin-1 loop model; Langerhans cell histiocytosis; Peptidomics