title: Natalizumab-induced POU2AF1/Spi-B upregulation: A possible route for PML development.
abstract: OBJECTIVE
  To assess messenger RNA (mRNA) expression of POU2AF1 and Spi-B and their potential regulatory microRNAs (miRNAs) in natalizumab-treated patients with multiple sclerosis and in therapy-associated progressive multifocal leukoencephalopathy (PML).
  
  
  METHODS
  Expression of POU2AF1/Spi-B was analyzed by using real-time reverse transcription PCR assays on isolated B/CD8(+) T lymphocytes and peripheral blood mononuclear cells (PBMCs) from cohorts of untreated and natalizumab-treated patients with and without PML. Longitudinal expression analysis was performed on CD4(+), CD8(+) T and B cells from 14 patients who interrupted natalizumab therapy for 8 weeks. The miRNA profiling was conducted in PBMCs from 5 untreated and 5 natalizumab-treated patients using low-density arrays followed by validation with single miRNAs assays in untreated and natalizumab-treated patients.
  
  
  RESULTS
  POU2AF1 and Spi-B mRNAs were upregulated in B and CD8(+) T cells from natalizumab-treated patients, which was validated in PBMCs from different cohorts of natalizumab-treated patients with and without PML, with a noteworthy higher expression of Spi-B in patients with PML. In contrast, downregulation of POU2AF1/Spi-B expression was measured in B and CD8(+) T cells after natalizumab discontinuation. Seventeen differentially expressed miRNAs including miR-10b, a regulator of POU2AF1 mRNA, were identified in long-term natalizumab-treated patients compared with untreated ones.
  
  
  CONCLUSIONS
  Upregulation of POU2AF1 and Spi-B, known transactivators of the JC virus, the causative agent for PML, and its association with occurrence of PML in natalizumab-treated patients, corroborates POU2AF1/Spi-B as potential biomarkers for PML risk, which merits further evaluation.
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Meira
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Sievers
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Francine
authors.initials: F
authors.lastname: Hoffmann
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Aiden
authors.initials: A
authors.lastname: Haghikia
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Maria
authors.initials: M
authors.lastname: Rasenack
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Bernhard F
authors.initials: BF
authors.lastname: Décard
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Kuhle
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Derfuss
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Kappos
authors.affiliation: Clinical Neuroimmunology (M.M., C.S., F.H., M.R., B.F.D., J.K., T.D., L.K., R.L.P.L.), Departments of Biomedicine and Neurology, University Hospital Basel, Switzerland; and Department of Neurology (A.H.), St. Josef-Hospital, Ruhr-University Bochum, Germany.
authors.forename: Raija L P
authors.initials: RL
authors.lastname: Lindberg