title: Effect of Clarithromycin on the Expression of UL16-Binding Protein 2 in Human Cells.
abstract: BACKGROUND
  Clarithromycin is a macrolide antibiotic that possesses anti-inflammatory and immunomodulatory properties. Although recent data suggests that macrolide antibiotics enhance Pseudomonas aeruginosa clearance from the lung, involving natural killer (NK) T cells in this process by activating the NKG2D-NKG2D ligand system, the precise underlying mechanism is still unclear. In this study, we examined the effect of clarithromycin on a potent NKG2D ligand, UL16-binding protein 2 (ULBP2), in the lung and its shedding mechanism.
  
  
  METHODS
  The gene expressions of ULBP2 and the shredder proteinases of ULBP2, a disintegrin and metalloproteinase domain 10 (ADAM10) and ADAM17, were measured using real-time PCR. The cell surface ULBP2 expression was measured by flow cytometry. The amount of solubilized ULBP2 (sULBP2) was measured using an ELISA. The activity of ADAM17 was examined by measurement of fluorescence intensity from the fluorescence resonance energy transfer peptide substrate cleaved by ADAM17.
  
  
  RESULTS
  Clarithromycin significantly induced transcription of ULBP2 and ADAM17 in both A549 and LCSC #2 cells, which endogenously express minimal and abundant levels of ULBP2, respectively. However, there was no significant change on transcription of ADAM10. The same tendency was observed when LCSC #2 cells were treated with tumor necrosis factoralpha processing inhibitor-2 to inhibit ADAM17 activity. The amount of sULBP2 was significantly decreased in both A549 and LCSC #2 cells by treatment with clarithromycin. Finally, clarithromycin significantly inhibited the activity of ADAM17 in LCSC #2 cells.
  
  
  CONCLUSIONS
  These findings suggest that clarithromycin induces ULBP2 expression and reduces the amount of sULBP2, by possibly inhibiting the activity of the potent ULBP2-shedding enzyme ADAM17. Because these changes in ULBP2 and sULBP2 levels could activate NKT cells, this finding might indicate a novel mechanism by which clarithromycin improves the clearance of P. aeruginosa in chronic respiratory diseases.
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Kensaku
authors.initials: K
authors.lastname: Okada
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan ; †Center for Infectious diseases, Tottori University Hospital, Yonago 683-8504, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Chikumi
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Miyako
authors.initials: M
authors.lastname: Takata
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Yamaguchi
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Makino
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kitaura
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan ; †Center for Infectious diseases, Tottori University Hospital, Yonago 683-8504, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Nakamoto
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yamasaki
authors.affiliation: †Center for Infectious diseases, Tottori University Hospital, Yonago 683-8504, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Igishi
authors.affiliation: ‡Department of Pathological Science and Technology, School of Health Science, Tottori University Faculty of Medicine, Yonago 683-8503, Japan.
authors.forename: Naoto
authors.initials: N
authors.lastname: Burioka
authors.affiliation: Division of Medical Oncology and Molecular Respirology, Department of Multidisciplinary Internal Medicine, School of Medicine,Tottori University Faculty of Medicine, Yonago 683-8504, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Shimizu
keywords: Pseudomonas aeruginosa; UL16 binding protein 2; a disintegrin and metalloprotease domain 17 protein; clarithromycin